CN114928915A - Lighting circuit - Google Patents

Lighting circuit Download PDF

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Publication number
CN114928915A
CN114928915A CN202111613289.0A CN202111613289A CN114928915A CN 114928915 A CN114928915 A CN 114928915A CN 202111613289 A CN202111613289 A CN 202111613289A CN 114928915 A CN114928915 A CN 114928915A
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CN
China
Prior art keywords
circuit
light emitting
power supply
light source
voltage
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Pending
Application number
CN202111613289.0A
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Chinese (zh)
Inventor
内山义浩
吉田峻一郎
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Koito Manufacturing Co Ltd
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Koito Manufacturing Co Ltd
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Publication date
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Publication of CN114928915A publication Critical patent/CN114928915A/en
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/40—Details of LED load circuits
    • H05B45/44—Details of LED load circuits with an active control inside an LED matrix
    • H05B45/46—Details of LED load circuits with an active control inside an LED matrix having LEDs disposed in parallel lines
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
    • H05B47/10—Controlling the light source
    • H05B47/165—Controlling the light source following a pre-assigned programmed sequence; Logic control [LC]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
    • B60Q1/00—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor
    • B60Q1/26—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic
    • B60Q1/34—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic for indicating change of drive direction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
    • B60Q1/00—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor
    • B60Q1/26—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic
    • B60Q1/34—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic for indicating change of drive direction
    • B60Q1/36—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to indicate the vehicle, or parts thereof, or to give signals, to other traffic for indicating change of drive direction using movable members, e.g. arms with built-in flashing lamps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
    • B60Q11/00—Arrangement of monitoring devices for devices provided for in groups B60Q1/00 - B60Q9/00
    • B60Q11/005—Arrangement of monitoring devices for devices provided for in groups B60Q1/00 - B60Q9/00 for lighting devices, e.g. indicating if lamps are burning or not
    • B60Q11/007—Arrangement of monitoring devices for devices provided for in groups B60Q1/00 - B60Q9/00 for lighting devices, e.g. indicating if lamps are burning or not the lighting devices indicating change of drive direction
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/345—Current stabilisation; Maintaining constant current
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/395—Linear regulators
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/40—Details of LED load circuits
    • H05B45/44—Details of LED load circuits with an active control inside an LED matrix
    • H05B45/48—Details of LED load circuits with an active control inside an LED matrix having LEDs organised in strings and incorporating parallel shunting devices
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
    • H05B45/52—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits in a parallel array of LEDs
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
    • H05B45/54—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits in a series array of LEDs
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
    • H05B47/10—Controlling the light source
    • H05B47/155—Coordinated control of two or more light sources
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Lighting Device Outwards From Vehicle And Optical Signal (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

The invention provides a lighting circuit capable of suppressing influence caused by variation of power supply voltage. The lighting circuit is applied to a turn signal lamp for a vehicle, and includes: a first drive circuit that supplies a first drive current to a first light source including at least one light emitting element; a first resistor and a first switch which are provided between a power supply line to which a power supply voltage is applied and a ground line and are connected in series; and a first control circuit that turns on the first switch when the power supply voltage is lower than a first predetermined value, and turns off the first switch when the power supply voltage is higher than the first predetermined value.

Description

Lighting circuit
Technical Field
The present invention relates to a lighting circuit.
Background
As a vehicle lamp, for example, a vehicle winker (hereinafter, referred to as a "turn signal lamp") using a so-called sequential technique in which a plurality of light sources are sequentially turned on is known (for example, patent document 1). Electric power is supplied from a battery of the vehicle to a lighting circuit applied to the vehicle direction indicator lamp.
Documents of the prior art
Patent literature
Patent document 1: japanese patent laid-open publication No. 2017-119449
Disclosure of Invention
Problems to be solved by the invention
The battery voltage of the vehicle (hereinafter referred to as a power supply voltage) is not always constant but decreases according to use. When the power supply voltage is high, power consumption of an IC or the like provided in the lighting circuit increases (heat generation increases), and a failure is likely to occur. Under the condition that the power supply voltage is low, the power consumption is low, and the hidden danger that the disconnection is detected by mistake exists.
The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a lighting circuit capable of appropriately controlling power consumption in accordance with a change in power supply voltage.
Means for solving the problems
The present invention, which solves the above problems, is a lighting circuit applied to a turn signal lamp for a vehicle, the lighting circuit including: a first drive circuit that supplies a first drive current to a first light source including at least one light emitting element; a first resistor and a first switch which are provided between a power supply line to which a power supply voltage is applied and a ground line, and which are connected in series; and a first control circuit that turns on the first switch when the power supply voltage is lower than a first predetermined value, and turns off the first switch when the power supply voltage is higher than the first predetermined value.
Effects of the invention
According to the present invention, it is possible to provide a lighting circuit capable of appropriately controlling power consumption according to a change in power supply voltage.
Drawings
Fig. 1 is a diagram showing an example of a lighting unit 10 mounted on a vehicle 1.
Fig. 2 is a schematic block diagram showing an example of the system configuration of the turn signal lamp 10A.
Fig. 3 is a schematic block diagram showing an example of the configuration of the lighting circuit 11A.
Fig. 4 is a diagram showing an example of the structure of the linear regulator 42A.
Fig. 5 is a diagram showing an example of the configuration of the detection circuit 43A.
Fig. 6 is a diagram showing an example of the configuration of the control circuit 46.
Fig. 7 is a schematic block diagram showing an example of the configuration of the lighting circuit 11B.
Fig. 8 is a diagram showing an example of the structure of the linear regulator 72A.
Fig. 9 is a diagram showing an example of the voltage detection circuit 76.
Fig. 10 is a timing chart for explaining the operation of the lighting circuit 11.
Fig. 11 is an explanatory diagram illustrating a lighting state of the light sources 20 and 30.
Fig. 12 is an explanatory diagram of currents flowing through the resistors R41 and R50.
Fig. 13 is a schematic block diagram showing an example of the configuration of a lighting circuit 11C according to a second embodiment of the lighting circuit 11B.
Fig. 14 is a timing chart for explaining the operation of the lighting circuit 11 according to the second embodiment.
Description of the reference numerals
1: a vehicle; 3: a movable part; 4: a fixed part; 10: a lighting unit; 10A: a turn signal lamp; 11. 11A, 11B, 11C: a lighting circuit; 12A, 12B: a cable; 13: a movable unit; 14: a fixing section unit; 20: a light source; 21-26: a light emitting section; 30: a light source; 41A, 41B, 41C: a PMOSFET; 42A, 42B, 42C: a linear regulator; 43A, 43B, 43C: a detection circuit; 44. 45: an I/F circuit; 46: a control circuit; 47: a capacitor; 48: a Schottky barrier diode; 49: an NMOSFET; 51: a constant current circuit; 52: a disconnection detection circuit; 53: a voltage regulation circuit; 54: a comparator; 55. 61: a PNP transistor; 56. 60, 67: a capacitor; 57. 62: an NPN transistor; 63. 64, 65, 66: a resistance; 71A, 71B: a PMOSFET; 72A, 72B: a linear regulator; 73. 77: an NMOSFET; 74. 75: an I/F circuit; 76: a voltage detection circuit; 81: a Zener diode; 82. 83: a resistance; 91: a constant current circuit; 92: a disconnection detection circuit; 93: a voltage regulation circuit; 94: a comparator; 100: an ECU; 110: a battery; 120: a switch; 461: a timer circuit; 462: a latch circuit; l1: a power line; l2: a ground line; A. b, C1-C4, D, E: a terminal; D1-D30: a light emitting element; R1-R15, R41, R42, R43, R50, R51 and R52: a resistance; vbat: a supply voltage; VT: a steering voltage; S1-S4: a signal.
Detailed Description
At least the following matters will be made clear from the description of the present specification and the drawings.
In the first embodiment, the first embodiment is described as follows
< construction of Turn Signal light 10A > >
Fig. 1 is a diagram showing an example of a lighting unit 10 mounted on a vehicle 1. Fig. 2 is a schematic block diagram showing an example of the system configuration of the turn signal lamp 10A.
A fixed portion 4 that is a part of a vehicle body and a movable portion 3 (a trunk door in the present embodiment) that can be opened and closed with respect to the fixed portion 4 are provided behind the vehicle body of the vehicle 1 shown in fig. 1. Here, the movable portion 3 is an example of a trunk door, but the present invention is not limited to this. For example, in the case of a hatchback type vehicle, the hatchback door corresponds to the movable portion 3.
The lighting unit 10 is a vehicle lamp provided behind the vehicle body of the vehicle 1, and includes a movable unit 13 (tail lamp (TL) unit) provided in the movable portion 3 and a fixed unit 14 (rear combination lamp (RCL) unit) provided in the fixed portion 4. As shown in fig. 1, the lighting unit 10 is configured to be symmetrical with respect to the center in the width direction (left-right direction) of the vehicle 1. In the following description, the right side portion (enlarged portion) will be mainly described, but the left side portion has the same configuration.
The lighting unit 10 includes a turn signal lamp 10A. The turn signal lamp 10A is a vehicle direction indicator lamp indicated by oblique lines in the enlarged view of fig. 1, and is disposed so as to straddle the fixed portion 4 and the movable portion 3 of the vehicle 1. The lighting unit 10 includes a tail lamp, a brake lamp, and the like in addition to the turn signal lamp 10A. The vehicle 1 is provided with a disconnection detection device (not shown) that detects whether or not the light emitting element of the turn signal lamp 10A is disconnected based on a current input from a battery 110 (described later) to the turn signal lamp 10A.
As shown in fig. 2, the turn signal lamp 10A includes a lighting circuit 11, a light source 20, a light source 30, and resistors R1 to R15.
The light source 20 is a light source including a light emitting element, and is provided in the movable portion 3. In the present embodiment, the light source 20 corresponds to a second light source. The light source 20 is divided into six light emitting sections (light emitting sections 21 to 26), and as shown in fig. 1, the six light emitting sections are arranged in parallel in a substantially horizontal direction (width direction of the vehicle 1).
The light emitting parts 21 to 26 are connected in parallel, and the light emitting elements connected in series are arranged in parallel in each light emitting part. For example, in the case of the light emitting section 21, the light emitting element D1 and the light emitting element D2 connected in series are connected in parallel with the light emitting element D3 and the light emitting element D4 connected in series.
In addition, the light emitting units 22 to 26 are provided with four light emitting elements, respectively, in the same manner as the light emitting unit 21. Therefore, the light source 20 is provided with 24 light emitting elements (D1 to D24).
The structures of light emitting units 21 to 26 are not limited to the above structures, and may include at least one light emitting element. For example, the plurality of light emitting elements may not be connected in series. In addition, three or more rows of light-emitting elements may be connected in parallel to one light-emitting unit. In addition, the number of light emitting elements, a connection method, and the like may be different in each light emitting section.
The light source 30 is a light source that is turned on after the light source 20 is turned on, and the light source 30 is provided in the fixing portion 4. In the present embodiment, the light source 30 corresponds to a first light source. Six light emitting elements (D25 to D30) are arranged in series and in parallel in the light source 30. Specifically, the light-emitting element D25, the light-emitting element D26, the light-emitting element D27, and the light-emitting element D28 connected in series, and the light-emitting element D29 and the light-emitting element D30 connected in series are connected in parallel. The light source 30 is arranged in parallel with the light source 20 of the movable portion 3. The configuration of the light source 30 is not limited to the above configuration, and may include at least one light emitting element.
The lighting circuit 11 is a circuit that is applied to the turn signal lamp 10A and lights the light emitting elements of the light sources by supplying driving currents to the light sources 20 and 30. The lighting circuit 11 of the present embodiment includes a lighting circuit 11A, a lighting circuit 11B, a cable 12A, and a cable 12B.
The lighting circuit 11A is a circuit for lighting each light emitting element of the light source 20, and the lighting circuit 11A is provided in the movable portion 3. The lighting circuit 11B is a circuit for lighting each light emitting element of the light source 30, and the lighting circuit 11B is provided in the fixing portion 4. The configuration of the lighting circuit 11A and the lighting circuit 11B will be described later.
The cable 12A is a cable for transmitting a signal (signal S1 described later) from the movable portion 3 to the fixed portion 4. The cable 12B is a cable for transmitting a signal (signal S2 described later) from the fixed unit 4 to the movable unit 3. Since the movable portion 3 is openable and closable with respect to the fixed portion 4, the cables 12A and 12B are wired via the shaft portion of the movable portion 3 that is opened and closed. Therefore, long cables having a length of, for example, 5 to 10m are used for the cables 12A and 12B.
The resistors R1 to R15 are resistors for dispersing power consumption of an IC (specifically, a linear regulator described later) in each lighting circuit. The resistors R1 to R12 are provided in the movable portion 3, and are connected in series between the two light emitting elements of the light source 20 connected in series and the lighting circuit 11A. The resistors R13 to R15 are provided in the fixing portion 4, and are connected in series between the two light emitting elements of the light source 30 connected in series and the lighting circuit 11B. In the present embodiment, a current control resistor (not shown) is also provided in the IC of the lighting circuit 11, and the current value (in other words, the luminance) can be changed for each light emitting unit (or the row of light emitting elements) by setting the resistance value of the current control resistor.
In fig. 2, an ECU (electronic control unit) 100 is a control circuit provided on the vehicle body side and based on a microcomputer or the like. The lighting circuit 11 (the lighting circuit 11A and the lighting circuit 11B) of the present embodiment lights the light source 20 and the light source 30 constituting the turn signal lamp in a gradation manner in accordance with an instruction from the ECU 100.
In fig. 2, the switch 120 is an element for applying a power supply for operating the lighting circuit 11 to the power supply line L1 of the turn signal lamp 10A. The switch 120 is, for example, a mechanical contact relay, a contactless relay using a semiconductor element, or the like. A power supply voltage Vbat of the vehicle battery 110 is applied to one end of the switch 120, and the other end of the switch 120 is connected to a power supply line L1. Therefore, when the switch 120 is turned on based on an instruction from the ECU100, the power supply voltage Vbat is applied to the power supply line L1. The power supply line L1 is a wire for supplying power to circuits inside the lighting circuit 11 (the lighting circuit 11A and the lighting circuit 11B).
For example, when the driver of the vehicle 1 operates a direction indicator (not shown) to turn on the turn signal lamp 10A of the lighting unit 10, the ECU100 turns on and off the switch 120 at a predetermined cycle Tx. Thereby, a voltage with a period Tx is applied to the power supply line L1 of the lighting circuit 11.
The ground line L2 is a line for applying a voltage of a ground level to the circuits inside the lighting circuit 11 (the lighting circuit 11A and the lighting circuit 11B). The power supply line L1 and the ground line L2 are branched and connected to the lighting circuit 11A and the lighting circuit 11B, respectively. In the following description, the ground line L2 is not shown, but it means that the grounded portion is connected to the ground line L2 in the lighting circuit 11A and the lighting circuit 11B. Hereinafter, the voltage from the switch 120 applied to the power supply line L1 is referred to as the steering voltage VT. Therefore, the steering voltage VT varies between 0V and the supply voltage Vbat.
< construction of Lighting Circuit 11A >)
Fig. 3 is a schematic block diagram showing an example of the configuration of the lighting circuit 11A. In the movable unit 13 shown in fig. 3, the parts other than the light source 20 (light emitting unit 21 to light emitting unit 26) and the resistors R1 to R12 correspond to the lighting circuit 11A. The components constituting the lighting circuit 11A are mounted on a substrate, not shown.
The lighting circuit 11A includes a diode 40, a PMOSFET41A, a PMOSFET41B, a PMOSFET41C, a linear regulator 42A, a linear regulator 42B, a linear regulator 42C, a detection circuit 43A, a detection circuit 43B, a detection circuit 43C, an interface circuit (hereinafter referred to as an I/F circuit) 44, an interface circuit 45, a control circuit 46, a capacitor 47, a schottky barrier diode 48, an NMOSFET49, a resistor R41, a resistor R42, and a resistor R43.
The diode 40 is an element for protecting a circuit from an influence and preventing a failure when the polarity of the battery 110 is mistaken and the battery is connected (when the battery is connected in the reverse direction). The steering voltage VT is applied to the anode of the diode 40, and the cathode of the diode 40 is connected to the PMOSFET 41A.
The PMOSFET41A, the PMOSFET41B, and the PMOSFET41C are elements for supplying the power of the power supply line L1 to the light source 20, and are provided so as to be connected in series in this order between the power supply line L1 (more specifically, the cathode of the diode 40) and the light source 20. The voltage between the PMOSFET41A and the cathode of the diode 40 (node N1) is a value that is reduced by the amount of voltage drop of the forward voltage of the diode 40 with respect to the power supply voltage Vbat, and is set to Vp 1. The PMOSFET41A, the PMOSFET41B, and the PMOSFET41C control conduction/non-conduction (on-off control) by the linear regulator 42A, the linear regulator 42B, and the linear regulator 42C, respectively. When the power supply voltage Vbat becomes higher than a predetermined value (for example, 11V), the PMOSFET41A is adjusted so that the on-resistance becomes large (described later). In this embodiment, the PMOSFET41A corresponds to a second transistor.
The capacitor 47 and the schottky barrier diode 48 are circuits for surge protection, and are connected in parallel between the PMOSFET41C and the light source 20.
The linear regulators 42A, 42B, and 42C are circuits for generating a drive current based on the power from the power supply line L1 and supplying the drive current to the light emitting elements of the light emitting portions of the light source 20, and are each formed of an Integrated Circuit (IC).
Linear regulator 42A is connected to light emitting unit 21 and light emitting unit 22 of light source 20, and supplies drive current to light emitting elements D1 to D8. The linear regulator 42B is connected to the light emitting units 23 and 24 of the light source 20, and supplies a drive current to the light emitting elements D9 to D16. The linear regulator 42C is connected to the light emitting units 25 and 26 of the light source 20 and supplies a drive current to the light emitting elements D17 to D24. The circuit for supplying the drive current to the light source 20 is not limited to the linear regulator, and other circuits (for example, a switching regulator) may be used.
In the present embodiment, the linear regulators 42A, 42B, and 42C correspond to the second drive circuit. The drive currents supplied to the light emitting elements of the light source 20 by the linear regulators 42A, 42B, and 42C correspond to the second drive current. In the present embodiment, the light emitting portions of the light source 20 are sequentially turned on using three regulators, but the present invention is not limited thereto, and all the light emitting portions included in the light source 20 may be sequentially turned on using one regulator (driving circuit). The configuration examples of the linear regulators 42A, 42B, and 42C will be described later.
The detection circuit 43A is a circuit that detects whether or not all of the light emitting elements connected to the linear regulator 42A are lit. The detection circuit 43B is a circuit that detects whether or not all of the light emitting elements connected to the linear regulator 42B are lit. The detection circuit 43C is a circuit that detects whether or not all of the light emitting elements connected to the linear regulator 42C are lit.
Based on the detection results of the detection circuits, the operation of the next linear regulator (in the case of the detection circuit 43C, the linear regulators 72A and 72B on the fixed unit 14 side described later) is started. The configuration examples of the detection circuit 43A, the detection circuit 43B, and the detection circuit 43C will be described later.
The I/F circuit 44 is a circuit that transmits a signal S1 based on the detection result of the detection circuit 43C to the I/F circuit 74 of the fixed unit 14 via the cable 12A. The I/F circuit 44 includes an inverter, not shown, and outputs a signal S1 obtained by inverting the logic level of the detection result of the detection circuit 43C. In the present embodiment, since the output of the detection circuit 43C is at a low level (hereinafter referred to as "L" level), the signal S1 becomes a high level (hereinafter referred to as "H" level).
In addition, the I/F circuit 44 applies the signal S1 to the gate of the NMOSFET49, and also sends the signal S1 to the control circuit 46.
The I/F circuit 45 is a circuit that receives a signal S2 from the I/F circuit 75 on the fixed unit 14 side and transmits the signal to the control circuit 46. The signal S2 is a signal indicating whether or not the voltage applied to the light source 30 is higher than a predetermined value (whether or not preparation for lighting the light emitting element of the light source 30 is completed).
The control circuit 46 is a circuit for controlling the operation of the linear regulator 42A. For example, when the I/F circuit 45 receives a signal S2 indicating that preparation for lighting the light emitting elements of the light source 30 is completed (the voltage applied to the light source 30 is higher than a predetermined value) at the time of power-on, the linear regulator 42A generates a drive current. Further, the control circuit 46 maintains the state in which the operation of the linear regulator 42A is stopped when the signal S2 is not received from the stationary unit 14 within a predetermined period from the transmission of the signal S1 indicating that the light-emitting section of the light source 20 is fully lit by the I/F circuit 44. By stopping the operation of the linear regulator 42A, the PMOSFET41A is turned off, and thus the light source 20 on the movable unit cell 13 side is also turned off. An example of the configuration of the control circuit 46 will be described later.
The resistor R41 is a resistor for adjusting the value of the current supplied from the battery 110 to the lighting circuit 11A (in other words, adjusting the power consumption), and is connected in parallel to the light source 20 (each light emitting unit).
The NMOSFET49 is connected in series with a resistor R41, and a signal S1 is applied to the gate. Therefore, the NMOSFET49 is turned on and off based on the signal S1, and when the NMOSFET49 is turned on, current flows through the resistor R41. The resistor R41 corresponds to a second resistor.
The resistor R42 and the resistor R43 are resistors for dividing the voltage Vp2 at the node N2 between the PMOSFET41C and the light source 20, and are connected in series between the node N2 and the ground (the ground line L2). The voltage Vdiv at the connection point between the resistor R42 and the resistor R43 is applied to a comparator 54 (described later) in the linear regulator 42A via a terminal E of the linear regulator 42A.
< Linear regulator 42A >
As described above, the lighting circuit 11A is provided with the three linear regulators 42A, 42B, 42C. In the following, the linear regulator 42A is mainly described as an example, but the linear regulators 42B and 42C are also configured in the same manner.
Fig. 4 is a diagram showing an example of the linear regulator 42A.
The linear regulator 42A includes a constant current circuit 51, a disconnection detection circuit 52, a voltage adjustment circuit 53, a comparator 54, and a plurality of terminals (terminal a, terminal B, terminals C1 to C4, terminal D, and terminal E). Further, electric power (applied voltage Vp1) is supplied from the node N1 between the diode 40 and the PMOSFET41A of the power supply line L1 to a terminal (not shown), and the linear regulator 42A is activated. Therefore, the linear regulator 42A can operate when the steering voltage VT becomes the power supply voltage Vbat, regardless of the on/off states of the PMOSFETs 41A to 41C.
The terminal a is an enable terminal, and the linear regulator 42A starts an operation of supplying a drive current by applying an "L" level signal to the terminal a.
The terminal B is a terminal for connecting the voltage adjustment circuit 53 to the gate of the PMOSFET 41A. The voltage adjustment circuit 53 adjusts the gate voltage of the PMOSFET41A through the terminal B.
The terminals C1 to C4 are terminals for connecting the constant current circuit 51 to each of the light emitting elements of the light emitting unit 21 and the light emitting unit 22, and are terminals for causing a drive current to flow through each of the light emitting elements. In the linear regulator 42A of the present embodiment, four terminals, i.e., the terminal C1 to the terminal C4, are provided as terminals to which the light emitting elements are connected, but the present invention is not limited thereto, and three or less terminals may be provided, or five or more terminals may be provided.
The terminal D is a terminal for outputting a signal indicating that the gradation operation in the line regulator (here, the line regulator 42A) is completed, and in the present embodiment, the detection circuit 43A described later detects that the drive current flows through the light emitting element D7 and the light emitting element D8 connected to the terminal C4, and forcibly sets the terminal D to the "L" level. As a result, the terminal a of the next linear regulator (here, the linear regulator 42B) becomes the "L" level, and the operation of supplying the drive current is started.
The terminal E is a terminal for introducing a divided voltage (voltage Vdiv) generated by the resistor R42 and the resistor R43 connected in series with the node N2 of the power supply line L1 into the linear regulator 42A.
The constant current circuit 51 is a circuit that generates a predetermined drive current based on the power of the power supply line L1. When generating the drive current, the higher the power supply voltage Vbat, the greater the power consumption (the greater the amount of heat generation). The generated driving current is supplied to the light emitting elements of the light emitting unit 21 and the light emitting unit 22 through the terminals C1 to C4. In the present embodiment, the linear regulators 42A, 42B, and 42C have the same configuration, but the magnitude of the generated drive current differs depending on, for example, the setting of the magnitude of the internal resistance (not shown). Specifically, the drive current generated by the linear regulator 42A is 40mA, the drive current generated by the linear regulator 42B is 60mA, and the drive current generated by the linear regulator 42C is 80 mA.
A timer, not shown, is provided in the constant current circuit 51, and a drive current can be caused to flow through the terminals C1 to C4 with timing shifted. In the present embodiment, after the driving current flows through the terminal C1 and the terminal C2 (in other words, through the light-emitting elements of the light-emitting section 21) at the same time, the driving current flows through the terminal C3 and the terminal C4 (in other words, through the light-emitting elements of the light-emitting section 22) at a slightly delayed timing (see fig. 10). However, the present invention is not limited to this, and for example, the timing may be shifted for each terminal.
The disconnection detection circuit 52 is a circuit connected to the connection lines between the terminals C1 to C4 and the constant current circuit 51, respectively, and detects the presence or absence of a disconnection. The method of detecting a disconnection is not particularly limited, and there are, for example, a method of detecting a voltage increase and a method of detecting a current non-flow.
The voltage adjustment circuit 53 is a circuit that controls the gate voltage of a PMOSFET (here, PMOSFET 41A). When the linear regulator 42A is activated, the voltage regulator circuit 53 regulates the gate voltage of the PMOSFET41A via the terminal B, turning on the PMOSFET 41A. Similarly, the voltage adjustment circuit 53 of the linear regulator 42B turns on the PMOSFET41B, and the voltage adjustment circuit 53 of the linear regulator 42C turns on the PMOSFET 41C. Then, all of the PMOSFET41A, the PMOSFET41B, and the PMOSFET41C are turned on, so that each light emitting portion (light emitting portion 21 to light emitting portion 26) of the light source 20 is in a state of being able to be lit.
When any one of the light emitting elements 21 and 22 is turned on and the light emitting element is not turned on (when detected by the disconnection detection circuit 52), the linear regulator 42A turns off the PMOSFET41A through the voltage adjustment circuit 53. Similarly, when any one of the light emitting elements 23 and 24 is turned on and the light emitting element is not turned on, the linear regulator 42B turns off the PMOSFET 41B. When any one of the light emitting elements 25 and 26 is turned on, the linear regulator 42C turns off the PMOSFET41C if the light emitting element is not turned on.
Since the PMOSFETs 41A to 41C are connected in series, when any one of them is turned off, no current flows through the light source 20 (the light source 20 is completely turned off).
The voltage adjustment circuit 53 adjusts the gate voltage of the PMOSFET41A based on the output of the comparator 54 (described later). The voltage adjustment circuit 53 of the linear regulator 42A corresponds to a second adjustment circuit.
A voltage at the E terminal (voltage Vdiv obtained by dividing the voltage Vp2 by the resistors R42 and R43) is applied to the inverting input terminal (-terminal) of the comparator 54, and a voltage Vref is applied to the non-inverting input terminal (+ terminal). Then, the comparator 54 compares the voltage Vdiv with the voltage Vref. In the present embodiment, the level of the voltage Vref and the resistance values of the resistor R42 and the resistor R43 are determined such that the voltage Vdiv is larger than the voltage Vref when the steering voltage VT (power supply voltage Vbat) becomes higher than a predetermined voltage (for example, 11V). The predetermined voltage (e.g., 11V) corresponds to the third predetermined value.
The comparator 54 outputs a signal of "L" level when the voltage Vdiv is higher than the voltage Vref, and outputs a signal of "H" level when the voltage Vdiv is lower than the voltage Vref. Then, when the output of the comparator 54 is at the "L" level, the voltage adjustment circuit 53 adjusts the gate voltage so that the on-resistance of the PMOSFET41A becomes large. This increases heat generation in the PMOSFET41A, and can disperse power consumption to the PMOSFET 41A.
In the present embodiment, since the resistors (the resistor R1 to the resistor R15) are provided between each linear regulator and the light emitting element of each light emitting unit, and further the resistor R41 is provided in parallel with the light source 20, power consumption can be further dispersed. Therefore, when the voltage of the power supply voltage Vbat is large (specifically, 11V or more), heat generation of the linear regulator can be suppressed.
< detection Circuit 43A >
Fig. 5 is a diagram showing an example of the configuration of the detection circuit 43A. In fig. 5, the position of the terminal D is shown shifted beside the terminal C4 for convenience of explanation.
The detection circuit 43A detects whether or not a current flows through the light emitting element (here, the light emitting element D7 and the light emitting element D8 connected in series) to which the drive current is supplied last among the plurality of light emitting elements D1 to D8 connected to the linear regulator 42A. Specifically, the detection circuit 43A detects whether or not all of the light-emitting elements D1 to D8 of the light-emitting unit 21 and 22 are lit based on the voltage Vp2 of the line LA on the anode side (the anode side of the light-emitting element D7) and the voltage Vp3 of the line LB on the cathode side (the cathode side of the light-emitting element D8) of the light-emitting element D7 and the light-emitting element D8 connected in series. As shown in fig. 5, the detection circuit 43A includes a PNP transistor 55, a capacitor 56, an NPN transistor 57, and a resistor R44 and a resistor R45.
The emitter of the PNP transistor 55 is connected to the line LA, and is connected to the base of the PNP transistor 55 via the capacitor 56. The base of the PNP transistor 55 is connected to the line LB via a resistor R44. The collector of the PNP transistor 55 is connected to the base of the NPN transistor 57 via a resistor R45.
The collector of NPN transistor 57 is connected to the connection line between terminal D of linear regulator 42A and terminal a of linear regulator 42B. A voltage Vp2 is applied to the connection line. Further, the emitter of the NPN transistor 57 is grounded.
With the above configuration, in a state where no drive current flows through the light-emitting element D7 or the light-emitting element D8, the PNP transistor 55 is turned off, and the NPN transistor 57 is also turned off. Therefore, the terminal D of the linear regulator 42A and the terminal a of the linear regulator 42B are changed to the "H" level by the applied voltage Vp 2.
When a driving current flows through the light-emitting element D7 and the light-emitting element D8, the PNP transistor 55 is turned on. Thereby, a current is supplied to the base of NPN transistor 57, and NPN transistor 57 turns on. Therefore, the terminal D of the linear regulator 42A and the terminal a of the linear regulator 42B are forcibly set to the "L" level, and the linear regulator 42B starts the operation of supplying the drive current.
In this way, the detection circuit 43A detects that the most recently lit row (here, the light emitting element D7 and the light emitting element D8) among the rows of light emitting elements connected to the linear regulator 42A is lit, and starts the operation of the linear regulator 42B. Thus, when the plurality of light emitting units are lit using the plurality of linear regulators, continuity of lighting of the plurality of light emitting units can be improved.
The detection circuit 43B and the detection circuit 43C are also configured similarly to the detection circuit 43A, and therefore, the description thereof is omitted. The detection circuit 43B detects whether or not all of the light emitting elements D9 to D16 of the light emitting section 23 and 24 have been turned on based on the voltage Vp2 of the line on the anode side (the anode side of the light emitting element D15) and the voltage Vp4 of the line on the cathode side (the cathode side of the light emitting element D6) of the light emitting element (here, the light emitting element D15 and the light emitting element D16 connected in series) to which the drive current is finally supplied, among the plurality of light emitting elements D9 to D16 connected to the linear regulator 42B.
The detection circuit 43C detects whether or not all of the light emitting section 25 and the light emitting elements D17 to D24 of the light emitting section 26 are lit based on a voltage Vp2 of a line on an anode side (an anode side of the light emitting element D23) and a voltage Vp5 of a line on a cathode side (a cathode side of the light emitting element D24) of the light emitting element (here, the light emitting element D23 and the light emitting element D24 connected in series) to which the drive current is finally supplied, among the plurality of light emitting elements D17 to D24 connected to the linear regulator 42C.
< control Circuit 46>
Fig. 6 is a diagram showing an example of the configuration of the control circuit 46.
The control circuit 46 includes a timer circuit 461 and a latch circuit 462.
A signal S1 is input from the I/F circuit 44 to the timer circuit 461, and a signal S2 is input from the I/F circuit 45 to the timer circuit 461. The timer circuit 461 is not operated at the time of power-on, and starts counting (becomes an operating state) of the timer when the signal S1 becomes "H" level (the terminal D of the linear regulator 42C becomes "L" level).
When the signal S2 becomes the "L" level within a predetermined period of time after the start of counting, the timer circuit 461 sets the signal S3 to the node N5 of the latch circuit 462 to the "L" level to operate the latch circuit 462. The "L" level signal S2 indicates that the preparation for lighting the light emitting elements of the light source 30 is not yet completed (the voltage applied to the light source 30 is lower than a predetermined value), and the details thereof will be described later.
On the other hand, if the signal S2 does not become the "L" level within a predetermined period of time after the timer circuit 461 starts counting, the timer circuit 461 stops operating (is reset).
The latch circuit 462 includes a capacitor 60, a capacitor 67, a PNP transistor 61, an NPN transistor 62, and a resistor 63, a resistor 64, a resistor 65, and a resistor 66. The resistors 63 and 64, and the resistors 65 and 66 are connected in series, respectively.
A voltage Vp1 is applied to an electrode at one end of the capacitor 60, and an electrode at the other end of the capacitor 60 is connected to a base of the PNP transistor 61. Here, as described above, the voltage Vp1 is a value smaller than the power supply voltage Vbat by the forward voltage of the diode 40. In addition, a resistor 63 is provided in parallel with the capacitor 60.
The base of the PNP transistor 61 is connected to the collector of the NPN transistor 62 via the resistor 64, the emitter of the PNP transistor 61 is connected to the electrode at one end of the capacitor 60, and the collector of the PNP transistor 61 is connected to the base of the NPN transistor 62 via the resistor R65.
The emitter of the NPN transistor 62 is grounded, and a signal S3 is input from the timer circuit 461 to a connection node N5 between the collector of the NPN transistor 62 and the resistor 64.
An electrode at one end of the capacitor 67 is connected to the base of the NPN transistor 62, and an electrode at the other end is grounded.
Further, a connection node N6 between the collector of the PNP transistor 61 and the resistor 65 is connected to the terminal a of the linear regulator 42A. Further, a signal S4 is output from the node N6 to the linear regulator 42A.
Next, the operation of the control circuit 46 will be described.
When the power is turned on, that is, when the steering voltage VT is the power supply voltage Vbat, the timer circuit 461 and the latch circuit 462 are not operated, and the PNP transistor 61 and the NPN transistor 62 are both turned off regardless of the voltage Vp 1. Therefore, when the power is turned on, the signal S4 output from the node N6 becomes "L" level, and the linear regulator 42A starts operating.
When all the light emitting portions (light emitting elements) of the light source 20 are turned on, the signal S1 becomes "H" level, and the timer circuit 461 operates. After that, if the signal S2 does not become the "L" level within the predetermined period, the timer circuit 461 stops operating (is reset). On the other hand, when the signal S2 becomes "L" level within the predetermined period (when the light source 30 is not lit), the output signal of the timer circuit 461 becomes "L" level.
When the signal S3 (node N5) from the timer circuit 461 becomes "L" level, the PNP transistor 61 of the latch circuit 462 becomes on state. Thereby, a current flows from the collector of the PNP transistor 61 to the base of the NPN transistor 62 via the resistor 65, and the NPN transistor 62 is also turned on. The collector of the NPN transistor 62 is connected to the base of the PNP transistor 61, and therefore the PNP transistor 61 is maintained in an on state. That is, the signal S4 from the node N6 is held at the "H" level, and the operation of the linear regulator 42A is stopped. This turns off the PMOSFET41A, and thus all light emitting parts of the light source 20 are turned off. When a direction indicator (not shown) for blinking turn signal lamp 10A is operated, latch circuit 462 holds signal S4 at the logic level described above.
< construction of Lighting Circuit 11B >)
Fig. 7 is a schematic block diagram showing an example of the configuration of the lighting circuit 11B. Note that, in the fixing unit 14 shown in fig. 7, the lighting circuit 11B corresponds to a portion other than the light source 30 (the light emitting element D25 to the light emitting element D30) and the resistors R13 to R15. The components constituting the lighting circuit 11B are mounted on a substrate, not shown.
The lighting circuit 11B includes a diode 70, a PMOSFET71A, a PMOSFET71B, a linear regulator 72A, a linear regulator 72B, NMOSFET73, an I/F circuit 74, an I/F circuit 75, a voltage detection circuit 76, and a resistor R50, a resistor R51, and a resistor R52.
The diode 70 is an element for protecting the circuit from the influence and preventing the malfunction when the polarity of the battery 110 is shifted and the connection is made (when the battery is connected in the reverse direction), similarly to the diode 40 of the lighting circuit 11A. The steering voltage VT (0V to the power supply voltage Vbat) is applied to the anode of the diode 70, and the cathode is connected to the PMOSFET 71A.
The PMOSFETs 71A and 71B are elements that function as switches when power of the power supply line L1 is supplied to the light source 30, and are connected in series between the diode 70 and the light source 30. The voltage between the PMOSFET71A and the diode 70 (node N7) is set to a value (here, voltage Vp6) that is reduced by the amount of voltage drop of the forward voltage of the diode 70 with respect to the power supply voltage Vbat. The PMOSFET71A and the PMOSFET71B are controlled to be conductive/non-conductive (on/off control) by the linear regulator 72A and the linear regulator 72B, respectively. In addition, when the power supply voltage Vbat becomes higher than a predetermined value (for example, 11V), the PMOSFET71A is adjusted so that the on-resistance becomes large by the linear regulator 72A. The PMOSFET71A corresponds to the second switch and the first transistor.
The linear regulators 72A and 72B are circuits for generating a drive current based on the power from the power supply line L1 and supplying the drive current to the light-emitting elements of the light source 30, and are each formed of an Integrated Circuit (IC).
Fig. 8 is a diagram showing an example of the structure of the linear regulator 72A. The linear regulator 72A includes a constant current circuit 91, a disconnection detection circuit 92, a voltage adjustment circuit 93, and a comparator 94. The constant current circuit 91, the disconnection detection circuit 92, the voltage adjustment circuit 93, and the comparator 94 are the same as the constant current circuit 51, the disconnection detection circuit 52, the voltage adjustment circuit 53, and the comparator 54 of the linear regulator 42A (fig. 4), respectively, and therefore, description thereof is omitted.
The linear regulator 72A supplies a drive current of 105mA to the light emitting element D29 and the light emitting element D30 connected in series to the terminal C1, and the linear regulator 72B supplies a drive current of 105mA to the light emitting element D25 and the light emitting element D26 connected in series to the terminal C1, and the light emitting element D27 and the light emitting element D28 connected in series to the terminal C2. The linear regulators 72A and 72B correspond to the first drive circuit. The drive currents supplied to the light emitting elements of the light source 30 by the linear regulators 72A and 72B correspond to the first drive current. The voltage adjustment circuit 93 in the linear regulator 72A corresponds to a second control circuit and a first adjustment circuit. In the present embodiment, the light source 30 (light emitting element D25 to light emitting element D30) is turned on using two regulators, but the present invention is not limited thereto. For example, the light source 30 may be turned on by one regulator.
The I/F circuit 74 is a circuit that receives the signal S1 via the cable 12A. The I/F circuit 74 includes an inverter, not shown, and outputs a signal obtained by inverting the logic value of the signal S1 to the a terminals of the linear regulators 72A and 72B. For example, when the signal S1 is at the "H" level, an "L" level signal is output. Thus, the linear regulators 72A and 72B start supply of the drive current at the same timing.
The I/F circuit 75 detects whether or not the voltage applied to the light source 30 (the voltage Vp7 at the node N8) is higher than a predetermined voltage, and transmits a signal S2 indicating the state. The signal S2 is received by the I/F circuit 45 of the movable part unit 13 via the cable 12B. Here, when the light source 30 is disconnected, the PMOSFET71A and the PMOSFET71B are controlled to be turned off by the linear regulators 72A and 72B. Then, the voltage Vp7 is lowered to 0V by turning off the PMOSFET71A and the PMOSFET 71B. Therefore, in this case, the I/F circuit 75 transmits a signal S2 indicating that the PMOSFET71A and the PMOSFET71B are turned off.
The resistor R50 and the NMOSFET73 are connected in series between the power supply line L1 (here, the node N8) and the ground (the ground line L2). The NMOSFET73 functions as a switch for causing a current to flow through the resistor R50, and is turned on and off by the voltage detection circuit 76. The resistor R50 is a resistor for current adjustment for preventing erroneous detection of disconnection of the light emitting element on the vehicle side when the power supply voltage Vbat is low. Note that the resistor R50 corresponds to a first resistor, and the NMOSFET73 corresponds to a first switch.
The voltage detection circuit 76 is a circuit that controls on/off of the NMOSFET73 based on the voltage Vp6 at the node N7 (cathode side of the diode 70). The voltage detection circuit 76 corresponds to a first control circuit. Since the voltage detection circuit 76 is connected to the cathode side of the diode 70, it can be unaffected even if the battery 110 is connected in reverse. In the present embodiment, the voltage detection circuit 76 turns on (turns on) the NMOSFET73 based on the voltage Vp6 when the power supply voltage Vbat is lower than 9.6V, and turns off (turns off) the NMOSFET73 based on the voltage Vp6 when the power supply voltage Vbat is higher than 9.6V. An example of the configuration of the voltage detection circuit 76 will be described later. The voltage Vp6 when the power supply voltage Vbat is 9.6V is, for example, 8.9V (9.6 to 0.7V (forward voltage)).
The resistor R51 and the resistor R52 are connected in series between a node N8 to which the source of the PMOSFET71B and the resistor R50 are connected and the ground (the ground line L2). Further, a connection point between the resistor R51 and the resistor R52 is connected to the terminal E of the linear regulator 72A. Thus, as in the linear regulator 42A on the movable unit cell 13 side, when the steering voltage VT (power supply voltage Vbat) becomes higher than a predetermined voltage (for example, 11V), the voltage adjustment circuit 93 of the linear regulator 72A adjusts the gate voltage so that the on-resistance of the PMOSFET71A becomes large. Note that the predetermined voltage (for example, 11V) corresponds to the second predetermined value.
This increases heat generation in the PMOSFET71A, and can disperse power consumption to the linear regulator 72A, the linear regulator 72B, and the PMOSFET 71A. As described above, in the present embodiment, the movable unit 3 is further provided with the PMOSFET41A provided between the power supply line L1 and the light source 20, the resistance R41 provided between the PMOSFET41A and the ground (the ground line L2), and the linear regulator 42A for increasing the on resistance of the PMOSFET when the power supply voltage Vbat is greater than the predetermined value. This can disperse power consumption to the PMOSFET41A and the resistor R41 on the light source 20 (movable part 3) side. Therefore, power consumption can be further dispersed.
< Voltage detection Circuit 76>
Fig. 9 is a diagram showing an example of the configuration of the voltage detection circuit 76. The voltage detection circuit 76 of fig. 9 includes a zener diode 81, a resistor 82, a resistor 83, a resistor 86, and an NPN transistor 85.
The zener diode 81, the resistor 82, and the resistor 83 are connected in series between the node N7 of the power supply line L1 and the ground (the ground line L2). The zener diode 81 adjusts a relationship between a voltage between the resistors R82 and R83 connected in series and a threshold voltage of the NPN transistor 85. The resistor R82 and the resistor R83 divide the voltage Vp6 reduced in voltage by the zener diode 81. Note that the zener voltage of the zener diode 81 and the resistance values of the resistor R82 and the resistor R83 are determined such that the NPN transistor 85 is turned on when the power supply voltage Vbat is higher than a predetermined value (9.6V in the present embodiment), and the NPN transistor 85 is turned off when the power supply voltage Vbat is lower than the predetermined value. The predetermined value (e.g., 9.6V) corresponds to the first predetermined value.
The base of the NPN transistor 85 is connected between the resistor R82 and the resistor R83 connected in series. The emitter of the NPN transistor 85 is grounded, the collector is applied with a voltage Vp6 via a resistor R86, and the collector is connected to the gate of the NMOSFET 73.
With the above configuration, when the power supply voltage Vbat is higher than the predetermined value (9.6V), the NPN transistor 85 is turned on and the NMOSFET73 is turned off. Therefore, no current flows through the resistor R50.
On the other hand, when the power supply voltage Vbat becomes lower than the predetermined value (9.6V), the NPN transistor 85 is turned off. Accordingly, the NMOSFET73 turns on, and a current flows through the resistor R50. As a result, even when the power supply voltage Vbat is lower than the predetermined value (9.6V), the power consumption of the lighting circuit 11B can be increased. This prevents the light emitting element from being erroneously detected as a disconnection on the vehicle side.
The configuration of the voltage detection circuit 76 is not limited to the configuration shown in fig. 9, and may be any configuration having the same function. For example, a comparator may be used to turn the NMOSFET73 on and off according to the power supply voltage Vbat.
< operation of Lighting Circuit 11 >
Fig. 10 is a timing chart for explaining the operation of the lighting circuit 11. Fig. 11 is an explanatory diagram illustrating a lighting state of the light sources 20 and 30. Fig. 12 is an explanatory diagram of currents flowing through the resistor R41 and the resistor R50. In fig. 11, the light-emitting state (luminance) of the light-emitting section is indicated by diagonal lines, and the greater the number of diagonal lines (the narrower the interval between diagonal lines), the brighter the light-emitting section is.
For example, when a direction indicator (not shown) for blinking a turn signal lamp is operated, the ECU100 of the present embodiment repeatedly turns on and off the switch 120 at a predetermined cycle Tx (e.g., 700 ms). The period during which the switch 120 is turned on and off in the period Tx is a half of the period Tx (350ms), respectively. Thus, the steering voltage VT is applied to the power supply line L1 during a half of the cycle Tx. In the period (time t0 to time t7 in fig. 10) in which the light emitting units of the light source 20 are sequentially turned on in the period (period in which the steering voltage VT becomes the H level (period in which the power supply voltage Vbat becomes), the input current is small, and therefore, a disconnection detection circuit (not shown) provided on the vehicle side may erroneously detect that the light source 20 or the light source 30 is disconnected. Therefore, the disconnection detection circuit on the vehicle side is shielded and does not detect the disconnection during the above period.
First, at time t0, the steering voltage VT becomes "H" level, and the power supply voltage Vbat of the battery 110 is applied to the power supply line L1. Thereby, the linear regulators of the lighting circuits 11A and 11B are activated, and the drive currents can be supplied to the light sources 20 and 30. Then, the linear regulator 42A (specifically, the voltage adjustment circuit 53) of fig. 3 turns on the PMOSFET 41A. Likewise, the linear regulator 42B turns on the PMOSFET41B, and the linear regulator 42C turns on the PMOSFET 41C. Thereby, the power supply line L1 and the light source 20 are brought into a conductive state.
Similarly, in the lighting circuit 11B of fig. 7, the linear regulator 72A turns on the PMOSFET71A, and the linear regulator 72B turns on the PMOSFET 71B. Thereby, the power supply line L1 and the light source 30 are brought into a conductive state. Further, I/F circuit 75 transmits signal S2 of "H" level indicating that the voltage applied to light source 30 is higher than the predetermined voltage (lighting preparation is completed), and signal S2 is received by I/F circuit 45 of movable unit 13 via cable 12B and input to control circuit 46. The control circuit 46 outputs a signal S4 of "L" level to the a terminal of the linear regulator 42A based on a signal S2 of "H" level indicating that the voltage applied to the light source 30 is higher than a predetermined voltage (the lighting preparation is completed). The linear regulator 42A starts the operation of supplying the drive current by inputting the signal S4 at the "L" level to the a terminal.
First, at time t1, the linear regulator 42A supplies a drive current of 40mA (total 80mA) to each of the two rows of light emitting elements (light emitting element D1, light emitting element D2, light emitting element D3, and light emitting element D4) of the light emitting section 21 via the terminal C1 and the terminal C2. Thereby, the light emitting unit 21 is turned on.
Next, at time t2, the linear regulator 42A supplies a drive current of 40mA (total 80mA) to each of the two rows of light-emitting elements (light-emitting element D5, light-emitting element D6, light-emitting element D7, and light-emitting element D8) of the light-emitting section 22 via the terminal C3 and the terminal C4. Thereby, the light emitting unit 22 is turned on. When the disconnection detection circuit 52 detects that any one of the light emitting elements 21 and 22 is not turned on, the linear regulator 42A (specifically, the voltage adjustment circuit 53) turns off the PMOSFET 41A. Thereby, each light emitting element of the light source 20 is turned off.
In addition, the detection circuit 43A detects that the light emitting elements of the light emitting section 21 and the light emitting section 22 have all been turned on based on the voltage Vp2 and the voltage Vp3 in the light emitting element (here, the light emitting element D7, the light emitting element D8) turned on last in the light emitting section 21 and the light emitting section 22, and sets the a terminal of the linear regulator 42B to the "L" level. Thereby, the linear regulator 42B starts the operation of supplying the drive current.
At time t3, the linear regulator 42B supplies a drive current of 60mA (total 120mA) to each of the two rows of light-emitting elements (light-emitting element D9, light-emitting element D10, light-emitting element D11, and light-emitting element D12) of the light-emitting section 23 via the terminal C1 and the terminal C2. This makes light emitting unit 23 brighter than light emitting units 21 and 22.
Next, at time t4, the linear regulator 42B supplies a drive current of 60mA (total 120mA) to each of the two rows of light-emitting elements (the light-emitting element D13, the light-emitting element D14, the light-emitting element D15, and the light-emitting element D16) of the light-emitting section 24 via the terminal C3 and the terminal C4. Thereby, the light emitting unit 24 is lit at the same brightness as the light emitting unit 23. When any of the light emitting elements of the light emitting unit 23 and the light emitting unit 24 is not turned on, the linear regulator 42B turns off the PMOSFET 41B. Thereby, each light emitting element of the light source 20 is turned off.
Further, the detection circuit 43B detects that the light emitting elements of the light emitting section 23 and the light emitting section 24 have all been turned on based on the voltage Vp2 and the voltage Vp4 in the lines across the light emitting element D15, the light emitting element D16, which have been turned on last in the light emitting section 23 and the light emitting section 24, and sets the a terminal of the linear regulator 42C to the "L" level. Thereby, the linear regulator 42C starts the operation of supplying the drive current.
At time t5, the linear regulator 42C supplies a drive current of 80mA (160 mA in total) to each of the two rows of light emitting elements (light emitting element D17, light emitting element D18, light emitting element D19, and light emitting element D20) of the light emitting section 25 via the terminal C1 and the terminal C2. This causes light emitting unit 25 to light brighter than light emitting unit 23 and light emitting unit 24.
Next, at time t6, the linear regulator 42C supplies a drive current of 80mA (total 160mA) to each of the two rows of light-emitting elements (the light-emitting element D21, the light-emitting element D22, the light-emitting element D23, and the light-emitting element D24) of the light-emitting section 26 via the terminal C3 and the terminal C4. Thereby, the light emitting unit 26 is lit at the same luminance as the light emitting unit 25. When any of the light emitting elements of the light emitting unit 25 and the light emitting unit 26 is not turned on, the linear regulator 42C turns off the PMOSFET 41C. Thereby, each light emitting element of the light source 20 is turned off.
The detection circuit 43C detects that all the light-emitting elements of the light-emitting section 25 and the light-emitting section 26 (in other words, all the light sources 20) have been turned on, based on the light-emitting element D23 turned on last in the light-emitting section 25 and the light-emitting section 26 (in other words, in the light source 20), and the voltage Vp2 and the voltage Vp5 in the lines across the light-emitting element D24. Then, the detection circuit 43C sends a signal indicating the detection result (here, a signal of "L" level) to the I/F circuit 44.
At time t7, the I/F circuit 44 inverts the logic level of the "L" level signal and transmits the "H" level signal S1. The signal S1 is transmitted from the movable unit 3 to the fixed unit 4 via the cable 12A, and is received by the I/F circuit 74 of the lighting circuit 11B.
At time t7, an "H" level signal S1 is applied to the gate of the NMOSFET49, turning on the NMOSFET49, and causing a current to flow through the resistor R41. Further, the signal S1 is input to the control circuit 46, and the timer circuit 461 of the control circuit 46 starts counting.
The I/F circuit 74 receives the "H" level signal S1, and causes the linear regulators 72A and 72B to start the operation of supplying the drive current to the light source 30. The linear regulator 72B supplies a drive current of 105mA to each of the two rows of light emitting elements (the light emitting element D25, the light emitting element D26, the light emitting element D27, and the light emitting element D28) of the light source 30. The linear regulator 72A supplies a drive current of 105mA to the light emitting elements D29 and D30 connected in series. Therefore, a total of 315mA of drive current is supplied to the light source 30, and the light source 30 is brighter than each light emitting section of the light source 20. In the present embodiment, the luminances of the light emitting parts of the light source 20 and the light source 30 are changed, but the present invention is not limited thereto, and for example, the light emitting parts may be turned on at the same luminance. In the present embodiment, since each light emitting section of the light source 20 is connected in parallel to the light source 30, the luminance can be easily changed.
When the steering voltage VT becomes the "L" level at time t8, the light sources 20 and 30 are turned off. Hereinafter, the same process is performed in accordance with the cycle Tx of the steering voltage VT.
When any one of the light-emitting elements D25 through D28 of the light source 30 is not turned on due to disconnection or the like, the linear regulator 72B turns off the PMOSFET 71B. Similarly, when the light emitting elements D29 and D30 of the light source 30 are not turned on, the linear regulator 72A turns off the PMOSFET 71A. Thereby, the light source 30 is completely extinguished. Further, for example, an "L" level signal S2 indicating that the voltage supplied to the light source 30 is lower than the predetermined value is transmitted from the I/F circuit 75 to the control circuit 46 via the cable 12B and the I/F circuit 45 of the movable portion 3.
The control circuit 46 holds the signal S4 to the linear regulator 42A at the "H" level when receiving the signal S2 at the "L" level for a predetermined period of time from the reception of the signal S1 at the "H" level. Thereby, the linear regulator 42A stops the supply of the drive current, and turns off the PMOSFET 41A. Therefore, the light source 20 is also turned off. Therefore, in the present embodiment, when the light source 30 side is not in a state of being able to be turned on, such as when the light emitting element of the light source 30 is disconnected, both the light source 20 and the light source 30 are turned off.
As described above, in the lighting circuit 11 of the present embodiment, the detection result ("H" level signal S1) indicating that all the light emitting elements of the light source 20 on the movable portion 3 side are already lit is transmitted to the fixed portion 4 via the cable 12A, and the supply of the driving current to the light source 30 is started. Thus, even if the light source 20 and the light source 30 are connected in parallel, overlapping or delay of the lighting timings can be avoided. Therefore, the continuity of lighting can be improved. Further, in the movable section 3, the supply of the drive current by the next linear regulator is started based on the detection result of the detection circuit indicating that all the light emitting sections connected to the respective linear regulators are lit up. Therefore, the continuity of lighting can be improved.
In the lighting circuit 11 of the present embodiment, power (power supply voltage Vbat) is supplied from the battery 110, but the power supply voltage Vbat is not always constant but decreases according to use. Therefore, there is a possibility that a malfunction occurs depending on the magnitude of the power supply voltage Vbat. For example, when the power supply voltage Vbat is low (for example, when it is lower than 9.6V), the input current to the lighting circuit 11 becomes small, and thus there is a possibility that the disconnection detection circuit (not shown) on the vehicle side erroneously detects that the disconnection has occurred in the lighting circuit 11.
Therefore, in the present embodiment, the resistor R50 and the NMOSFET73 connected in series between the power supply line L1 to which the power supply voltage Vbat of the lighting circuit 11B is applied and the ground (the ground line L2) and the voltage detection circuit 76 that turns on and off the NMOSFET73 in accordance with the magnitude of the power supply voltage Vbat are provided.
As described above, the voltage detection circuit 76 turns on the NMOSFET73 when the power supply voltage Vbat is lower than 9.6V, and turns off the NMOSFET73 when the power supply voltage Vbat is higher than 9.6V. As a result, as shown in fig. 10 and 12, when the power supply voltage Vbat is lower than 9.6V, a current flows through the resistor R50, and power consumption increases. As shown in fig. 10, during a period in which the disconnection detection circuit on the vehicle side is not shielded (a period from time t7 to time t8 at which the light source 30 is turned on), the NMOSFET49 is turned on in response to the signal S1, and a current flows through the resistor R41, so that erroneous detection can be prevented. When the light source 30 is not turned on due to disconnection or the like, the PMOSFET71A is turned off, and no current flows through the resistor R50. Therefore, reduction in power consumption can be achieved.
On the other hand, when the power supply voltage Vbat is high (for example, when it is higher than 11V), power consumption when each linear regulator of the lighting circuit 11 generates a drive current becomes large (the amount of heat generation becomes large), which may cause a failure. In the present embodiment, in the lighting circuit 11B, when the power supply voltage Vbat is higher than 11V, the linear regulator 72A adjusts the gate voltage so that the on-resistance of the PMOSFET71A becomes large. This can disperse power consumption to the PMOSFET 71.
In the lighting circuit 11A, when the power supply voltage Vbat is higher than 11V, the linear regulator 42A adjusts the gate voltage so that the on-resistance of the PMOSFET41A becomes large. This can disperse power consumption to the PMOSFET 41A. In the lighting circuit 11A, as shown in fig. 10 and 12, since a current flows through the resistor R41 connected in parallel with the light source 20, the power can be dispersed to the resistor R41. As shown in fig. 12, when the power supply voltage Vbat becomes higher than 11V, the on-resistance of the PMOSFET41A becomes large, and therefore the change (the slope with respect to the voltage) of the current flowing through R41 becomes small.
In this way, the first and second embodiments can be implemented in a simple manner
Fig. 13 is a schematic block diagram showing an example of the configuration of a lighting circuit 11C according to a second embodiment of the lighting circuit 11B. The configuration of the lighting circuit 11A is the same as that of the first embodiment. In fig. 13, the same components as those of the lighting circuit 11B (fig. 7) according to the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
The lighting circuit 11C of the second embodiment is different from the lighting circuit 11B of the first embodiment in that it includes a resistor R53 and an NMOSFET 77.
The resistor R53 is a resistor for adjusting the value of the current supplied from the battery 110 to the lighting circuit 11C, and the resistor R53 is connected in parallel with the light source 30.
The NMOSFET77 is connected in series with a resistor R53, and a signal S1 is applied to the gate from the I/F circuit 74. Therefore, the NMOSFET77 turns on and off based on the signal S1. In this embodiment, when the I/F circuit 74 receives the signal S1 at the "H" level, the NMOSFET77 is turned on, and a current flows through the resistor R53.
Fig. 14 is a timing chart for explaining the operation of the lighting circuit 11 according to the second embodiment. Since the signal S1 is applied to the gate of the NMOSFET77, the NMOSFET77 is turned on and off at the same timing as the NMOSFET49 of the movable portion 3. In other words, the current flows through the resistor R53 at the same timing as the resistor R41 of the movable portion 3.
Specifically, at time t1 to t7 when the light-emitting elements of the light source 20 are sequentially turned on, the signal S1 is at the "L" level, and therefore the NMOSFET77 is turned off, and no current flows through the resistor R53. At time t7, the signal S1 becomes "H" level, the NMOSFET77 turns on, and current flows through the resistor R53. At time t8, the signal S1 changes to the "L" level, the NMOSFET77 turns off, and no current flows through the resistor R53.
As described above, in the second embodiment, the resistor R53 connected in parallel with the light source 30 is provided in the lighting circuit 11C on the fixed unit 4 side, and by passing a current through the resistor R53 while the light source 30 is lit, the input current can be increased even on the fixed unit 4 side, and erroneous detection of a disconnection by a disconnection detection circuit (not shown) on the vehicle side as a disconnection can be further suppressed. In addition, when the power supply voltage Vbat is higher than 11V, the linear regulator 72A adjusts so that the on-resistance of the PMOSFET71A becomes large, and therefore the current characteristic of the resistor R53 with respect to the input voltage is substantially the same as the resistor R41 of fig. 12. By providing the resistor R53 in the fixed unit 4 in this manner, power consumption can be further dispersed when the power supply voltage Vbat is high.
The term "a", "an", and "the" are intended to be used interchangeably
The lighting circuit 11 of the present embodiment has been described above. The lighting circuit 11 includes a linear regulator 72A and a linear regulator 72B that supply driving currents to the light source 30 including the light emitting elements D25 to D30. Further, a resistor R50 and an NMOSFET73 are connected in series between a power supply line L1 to which a power supply voltage Vbat is applied and a ground (a ground line L2), and the voltage detection circuit 76 turns on the NMOSFET73 when the power supply voltage Vbat is lower than 9.6V, and turns off the NMOSFET73 when the power supply voltage Vbat is higher than 9.6V. This can increase the current amount when the power supply voltage Vbat is low, and can improve power consumption.
In addition, a PMOSFET71A is provided between the power supply line L1 and the light source 30, and a resistor R50 and an NMOSFET73 are provided between the PMOSFET71A and the ground (ground line L2). When no current flows when the light emitting elements D29 and D30 of the light source 30 are turned on, the linear regulator 72A turns off the PMOSFET 71A. Thus, when the light source 30 is not lit, current can be prevented from flowing through the resistor R50, and power consumption can be reduced.
The voltage detection circuit 76 controls on/off of the NMOSFET73 based on the voltage on the cathode side of the diode 70 having the anode applied with the power supply voltage Vbat and the cathode connected to the PMOSFET 71A. Thereby, the circuit can be prevented from being affected in the case where the battery 110 is reversely connected.
In addition, in the case where the power supply voltage Vbat is higher than 11V, a voltage adjustment circuit (not shown) in the linear regulator 72A adjusts the gate voltage of the PMOSFET71A so that the on-resistance of the PMOSFET71A becomes large. Thus, when the power supply voltage Vbat is high, the power consumption of the PMOSFET71A can be increased, and the power consumption can be dispersed.
Further, the lighting circuit 11 includes: a linear regulator 42A that supplies a drive current to the light source 20 including the light emitting element D1 to the light emitting element D24; a PMOSFET41A provided between the power supply line L1 and the light source 20; and a resistor R41 provided between the PMOSFET41A and the ground (ground line L2). When the power supply voltage Vbat is higher than 11V, the voltage adjusting circuit 53 of the linear regulator 42A adjusts the PMOSFET41A so that the on-resistance of the PMOSFET41 becomes large. This can disperse power consumption to the PMOSFET41A and the resistor R41.
The light source 30, the resistor R50, the NMOSFET73, and the linear regulator 72A are provided on one of the fixed part 4 and the movable part 3 (the fixed part 4 in the present embodiment) that is openable and closable with respect to the fixed part 4 of the vehicle 1, and the light source 20, the PMOSFET41A, the resistor R41, and the linear regulator 42A are provided on the other of the fixed part 4 and the movable part 3 (the movable part 3 in the present embodiment). Thus, when the power supply voltage Vbat is higher than 11V, power consumption can be distributed in the fixed unit 4 and the movable unit 3, respectively.
The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention can be modified and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof.

Claims (7)

1. A lighting circuit applied to a turn signal lamp for a vehicle,
the lighting circuit includes:
a first drive circuit that supplies a first drive current to a first light source including at least one light emitting element;
a first resistor and a first switch which are provided between a power supply line to which a power supply voltage is applied and a ground line, and which are connected in series; and
a first control circuit that turns on the first switch when the power supply voltage is lower than a first predetermined value, and turns off the first switch when the power supply voltage is higher than the first predetermined value.
2. The lighting circuit according to claim 1,
the lighting circuit includes:
a second switch disposed between the power line and the first light source; and
a second control circuit that turns off the second switch when no current flows through a predetermined light emitting element of the first light source when the predetermined light emitting element is turned on,
the first resistor and the first switch are disposed between the second switch and the ground line.
3. The lighting circuit according to claim 2,
the lighting circuit includes a diode, the anode of which is applied with the power supply voltage, and the cathode of which is connected to the second switch,
the first control circuit controls on/off of the first switch based on a voltage of the cathode.
4. The lighting circuit according to claim 2 or 3,
the second switch is a first transistor and the second switch is a second transistor,
the lighting circuit includes a first adjustment circuit that increases an on-resistance of the first transistor when the power supply voltage is higher than a second predetermined value.
5. The lighting circuit according to any one of claims 1 to 4,
the lighting circuit includes:
a second drive circuit that supplies a second drive current to a second light source including at least one light emitting element;
a second transistor disposed between the power supply line and the second light source;
a second resistor provided between the second transistor and the ground line; and
and a second adjustment circuit that increases an on-resistance of the second transistor when the power supply voltage is higher than a third predetermined value.
6. The lighting circuit according to claim 5,
the first light source, the first resistor, the first switch, and the first control circuit are provided on one of a fixed part and a movable part that is openable and closable with respect to the fixed part of the vehicle,
the second light source, the second transistor, the second resistor, the second drive circuit, and the second adjustment circuit are provided on the other of the fixed unit and the movable unit.
7. A lighting circuit applied to a turn signal lamp for a vehicle,
the lighting circuit includes:
a drive circuit that supplies a drive current to a light source including at least one light emitting element;
a transistor provided between a power supply line to which a power supply voltage is applied and the light source;
a resistor disposed between the transistor and a ground line; and
and an adjustment circuit that increases an on-resistance of the transistor when the power supply voltage is higher than a predetermined value.
CN202111613289.0A 2021-02-03 2021-12-27 Lighting circuit Pending CN114928915A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2021015835A JP2022118963A (en) 2021-02-03 2021-02-03 Lightning circuit
JP2021-015835 2021-02-03

Publications (1)

Publication Number Publication Date
CN114928915A true CN114928915A (en) 2022-08-19

Family

ID=82804212

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111613289.0A Pending CN114928915A (en) 2021-02-03 2021-12-27 Lighting circuit

Country Status (2)

Country Link
JP (1) JP2022118963A (en)
CN (1) CN114928915A (en)

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JP2022118963A (en) 2022-08-16

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