WO2014107406A1 - Lighting system and color temperature adjusting circuit - Google Patents

Lighting system and color temperature adjusting circuit Download PDF

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Publication number
WO2014107406A1
WO2014107406A1 PCT/US2013/078007 US2013078007W WO2014107406A1 WO 2014107406 A1 WO2014107406 A1 WO 2014107406A1 US 2013078007 W US2013078007 W US 2013078007W WO 2014107406 A1 WO2014107406 A1 WO 2014107406A1
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WO
WIPO (PCT)
Prior art keywords
light
emitting
circuit
emitting unit
color temperature
Prior art date
Application number
PCT/US2013/078007
Other languages
French (fr)
Inventor
Steven Lu
Original Assignee
Misem Technology, Inc.
Huang, Alice Y.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Misem Technology, Inc., Huang, Alice Y. filed Critical Misem Technology, Inc.
Publication of WO2014107406A1 publication Critical patent/WO2014107406A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V23/00—Arrangement of electric circuit elements in or on lighting devices
    • F21V23/003—Arrangement of electric circuit elements in or on lighting devices the elements being electronics drivers or controllers for operating the light source, e.g. for a LED array
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S10/00—Lighting devices or systems producing a varying lighting effect
    • F21S10/02—Lighting devices or systems producing a varying lighting effect changing colors
    • 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]
    • H05B45/20—Controlling the colour of the light

Definitions

  • the present invention relates to a lighting system and a color temperature adjusting circuit, and more particularly to a lighting system and a color temperature adjusting circuit which modulate the color temperature of the light-emitting diode (LED) in the way of pulse width modulation, and simultaneously maintain a stable driving voltage and a stable driving current.
  • LED light-emitting diode
  • the lighting system includes a power supply unit 11 and a light-emitting device 10.
  • the power supply unit 11 includes a control unit 111.
  • the light- emitting device 10 includes a light-emitting unit 101 and a rectifying unit 102.
  • the light- emitting unit 101 includes a plurality of light- emitting diodes 1011.
  • the rectifying unit 102 includes a transistor 1021 and a plurality of light- emitting diodes 1022.
  • the control unit 111 provides a control signal to the transistor 1021.
  • the transistor 1021 When the transistor 1021 is turned on, the potential of the rectifying unit 102 is lowered, which causes II to be risen abruptly. However, when the transistor 1021 is turned off, the potential of the rectifying unit 102 is risen, which causes II to be lowered abruptly.
  • the substantial variation of the transient current not only causes the light- emitting diodes 1011, 1022 to be flickering, but also increases the difficulty in regulating the output over the load transients for the power supply unit 11.
  • the lighting system includes a power supply unit 21 and a light-emitting device 11.
  • the power supply unit 21 includes a control unit 211.
  • the light- emitting device 11 includes a light-emitting unit 111 and a rectifying unit 112.
  • the light- emitting unit 111 includes a plurality of light- emitting diodes 1111.
  • the rectifying unit 112 includes a transistor 1122 and a plurality of light- emitting diodes 1121.
  • the control unit 211 provides a control signal to the transistor 1122. When the transistor 1122 is turned on, II is risen and Vo is lowered.
  • the voltage difference of the rectifying unit 112 is to be similar to that of the light- emitting unit 111, when the light- emitting diode 1111 is formed by a bluelight- emitting chip and phosphors, which has a forward conduction voltage of about 3 V, and the light-emitting diode 1121 is the redlight-emitting diode having a forward conduction voltage of about 2 V, the amount of the light- emitting diodes 1121 in the rectifying unit 112 is about 1.5 times that in the light-emitting unit 111.
  • the redlight-emitting diode 1121 is replaced with a light- emitting diode which is also formed by a bluelight-emitting chip and phosphors, intrinsically having same forward conduction voltage of about 3 V as well, the amount of the light-emitting diodes 1121 in the rectifying unit 112 is about the same as that in the light- emitting unit 111. Therefore, to make the voltage difference of the light- emitting unit 111 similar to that of the rectifying unit 112, 2 times the amount of the light-emitting diodes 1111 in the light-emitting unit 111 is required at the least. That is, more materials are consumed, and a larger space is required to receive the light- emitting device 11.
  • a lighting system and a color temperature adjusting circuit are provided.
  • the particular design in the present invention not only solves the problems described above, but also is easier to be implemented.
  • the present invention has the utility for the industry.
  • a lighting system and a color temperature adjusting circuit are provided.
  • the color temperature of the light- emitting diode is modulated in the way of PWM, a lesser amount of light- emitting diodes is used, and the voltage and current for driving the light- emitting diode can be maintained more stably. This improves the flickering of the light- emitting diode, enhances the performance of the light- emitting diode, reduces the requirement for the high load regulation specification of the power supply unit, and reduces the cost.
  • a lighting system in accordance with another aspect of the present invention, includes a power supply unit; and a light-emitting device coupled to the power supply unit, having a driving current, and including a first light- emitting unit; and a color temperature adjusting circuit connected in series to the first light- emitting unit, adjusting a color temperature of the light- emitting device, and including a first circuit electrically connected to the first light- emitting unit, having a first voltage drop and a second light- emitting unit, and adjusting the color temperature to a first status; and a second circuit connected in parallel to the first circuit, having a second voltage drop and a third light-emitting unit, and adjusting the color temperature to a second status, wherein the second voltage drop is smaller than the first voltage drop so that when the second circuit is turned on, the first circuit is turned off, and when one of the first circuit and the second circuit is in operation, the driving current has a variation quantity proportional to a difference between the first voltage drop and the second voltage
  • a color temperature adjusting circuit for adjusting a color temperature of a light- emitting device.
  • the light- emitting device has a driving current and a first light-emitting unit connected in series to the color temperature adjusting circuit.
  • the color temperature adjusting circuit includes a first circuit electrically connected to the first light- emitting unit, having a first voltage drop and a second light-emitting unit, and adjusting the color temperature to a first status; and a second circuit connected in parallel to the first circuit, having a second voltage drop and a third light- emitting unit, and adjusting the color temperature to a second status, wherein the second voltage drop is smaller than the first voltage drop so that when the second circuit is turned on, the first circuit is turned off, and when one of the first circuit and the second circuit is in operation, the driving current has a variation quantity proportional to a difference between the first voltage drop and the second voltage drop.
  • a color temperature adjusting circuit for adjusting a color temperature of a light- emitting device.
  • the light-emitting device has a first light- emitting unit connected in series to the color temperature adjusting circuit.
  • the color temperature adjusting circuit includes a first circuit electrically connected to the first light- emitting unit, having a second light- emitting unit, and adjusting the color temperature to a first status; and a second circuit connected in parallel to the first circuit, having a third light- emitting unit, and adjusting the color temperature to a second status.
  • Fig. 1(A) shows a lighting system for modulating the color temperature of the light- emitting diode in the prior art
  • Fig. 1(B) shows another lighting system for modulating the color temperature of the light- emitting diode in the prior art
  • Fig. 2 shows a lighting system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
  • the lighting system includes a power supply unit 31 and a light-emitting device 2.
  • the power supply unit 31 includes a control unit 311.
  • the light- emitting device 2 includes a first light- emitting unit 23 and a color temperature adjusting circuit 4.
  • the color temperature adjusting circuit 4 includes a first circuit 22 and a second circuit 21.
  • the first light-emitting unit 23 includes a plurality of light-emitting diodes 231-233.
  • the first circuit 22 includes a second light- emitting unit 221.
  • the second light-emitting unit 221 includes a plurality of light- emitting diodes 2211-2213.
  • the second circuit 21 includes a third light- emitting unit 211 and a transistor 212.
  • the third light-emitting unit 211 includes a plurality of light- emitting diodes 2111, 2112.
  • the anode of the light- emitting diode 231 is connected to the positive terminal of the power supply unit 31.
  • the cathode of the light- emitting diode 233 is connected to the anode of the light- emitting diode 2111 and the anode of the light- emitting diode 2211 respectively.
  • the cathode of the light- emitting diode 2213 is connected to the source of the transistor 212 and grounded.
  • the drain of the transistor 212 is connected to the cathode of the light- emitting diode 2112, the gate thereof is connected to the control unit 311, and the source thereof is connected to the negative terminal of the power supply unit 31 and grounded.
  • the control unit 311 provides a PWM signal to the gate of the transistor 212.
  • the PWM signal controls the transistor 212 to be turned on or turned off, thereby causing the third light-emitting unit 211 to be turned on or turned off. That is, when the transistor 212 is controlled by the PWM signal to be turned on, the third light- emitting unit 211 is turned on so that the light- emitting diodes 2111, 2112 emit light. However, when the transistor 212 is controlled by the PWM signal to be turned off, the third light- emitting unit 211 is turned off so that the light- emitting diodes 2111, 2112 do not emit light.
  • the forward conduction voltage of the second circuit 21 has to be smaller than that of the first circuit 22 so that when the transistor 212 is turned on, the second light- emitting unit 221 is turned off, and when the transistor 212 is turned off, the second light- emitting unit 221 is turned on.
  • the conduction voltage of the first light- emitting unit 23 being connected in series to the second circuit 21 is very close to that of the first light- emitting unit 23 being connected in series to the first circuit 22. Therefore, the alternation of the second circuit 21 and the first circuit 22 only causes a tiny transient variation in the driving current II.
  • the variation in the driving current II is proportional to the difference between the forward conduction voltage of the first circuit 22 and the forward conduction voltage of the second circuit 21.
  • the first light-emitting unit 23 emits the white light having a color temperature of 4500 K (Kelvin).
  • the second light- emitting unit 221 emits the white light having a color temperature of 5000 K.
  • the third light- emitting unit 211 emits the red light.
  • the ratio of the lumen value of the first light-emitting unit 23 to the lumen value of the second light- emitting unit 22 is 50:45.
  • the proportion of the red light in the total lumen value is changed by the ratio of the turn-on time of the third light-emitting unit 211 so that the light-emitting device 2 can emit white lights having different color temperatures.
  • the higher the ratio of the turn-on time of the third light- emitting unit 211 is, the lower the color temperature of the white light emitted by the light emitting device 2 is.
  • the first light- emitting unit 23 includes a single light-emitting diode, a plurality of light- emitting diodes connected in parallel, a plurality of light-emitting diodes connected in series, or a plurality of light- emitting diode modules connected in series, wherein each light- emitting diode module includes a plurality of light- emitting diodes connected in parallel.
  • the second light- emitting unit 221 includes a single light-emitting diode, a plurality of light- emitting diodes connected in parallel, a plurality of light-emitting diodes connected in series, or a plurality of light- emitting diode modules connected in series, wherein each light- emitting diode module includes a plurality of light- emitting diodes connected in parallel.
  • the third light- emitting unit 211 includes a single light-emitting diode, a plurality of light- emitting diodes connected in parallel, a plurality of light-emitting diodes connected in series, or a plurality of light- emitting diode modules connected in series, wherein each light- emitting diode module includes a plurality of light- emitting diodes connected in parallel.
  • the transistor 212 is a MOSFET.
  • the amount of light- emitting diodes used in the second light- emitting unit 221 of the present invention plus that used in the first light- emitting unit 23 of the present invention is equal to that used in the light-emitting unit 111 of Fig.
  • the amount of light-emitting diodes used in the third light- emitting unit 211 of the present invention is less than that used in the rectifying unit 112 of Fig. 1(B). Accordingly, the amount of overall light- emitting diodes used in the present invention can be greatly reduced.
  • a lighting system comprising:
  • a light- emitting device coupled to the power supply unit, having a driving current, and including:
  • a color temperature adjusting circuit connected in series to the first light- emitting unit, adjusting a color temperature of the light-emitting device, and including:
  • a first circuit electrically connected to the first light- emitting unit, having a first voltage drop and a second light-emitting unit, and adjusting the color temperature to a first status
  • a second circuit connected in parallel to the first circuit, having a second voltage drop and a third light-emitting unit, and adjusting the color temperature to a second status, wherein the second voltage drop is smaller than the first voltage drop so that when the second circuit is turned on, the first circuit is turned off, and when one of the first circuit and the second circuit is in operation, the driving current has a variation quantity proportional to a difference between the first voltage drop and the second voltage drop.
  • the power supply unit has a positive terminal and a negative terminal, and includes a control unit providing a control signal
  • the first light- emitting unit has a first terminal connected to the positive terminal, and a second terminal;
  • the first circuit has a third terminal connected to the second terminal, and a fourth terminal being grounded;
  • the second circuit has a fifth terminal and a sixth terminal, and includes a transistor, wherein the fifth terminal is connected to the second terminal, the sixth terminal is connected to a source of the transistor, the negative terminal and grounded, and the transistor is controlled by the control signal to be one of turned on and turned off to control the third light- emitting unit to be one of turned on and turned off;
  • the transistor when the transistor is turned off, the third light-emitting unit is turned off, and the second light-emitting unit is turned on.
  • control signal is a pulse width modulation (PWM) signal.
  • PWM pulse width modulation
  • the first light- emitting unit includes one selected from a group consisting of a single light- emitting diode, a plurality of light-emitting diodes connected in parallel, a plurality of light- emitting diodes connected in series, and a plurality of light- emitting diode modules connected in series; and each the light- emitting diode module includes the plurality of light- emitting diodes connected in parallel.
  • the second light- emitting unit includes one selected from a group consisting of a single light-emitting diode, a plurality of light- emitting diodes connected in parallel, a plurality of light-emitting diodes connected in series, and a plurality of light-emitting diode modules connected in series; and
  • each the light- emitting diode module includes the plurality of light- emitting diodes connected in parallel.
  • the third light-emitting unit includes one selected from a group consisting of a single light-emitting diode, a plurality of light- emitting diodes connected in parallel, a plurality of light-emitting diodes connected in series, and a plurality of light-emitting diode modules connected in series; and
  • each the light- emitting diode module includes the plurality of light- emitting diodes connected in parallel.
  • the first light- emitting unit emits a first white light having a first color temperature of 4500 K (Kelvin);
  • the second light-emitting unit emits a second white light having a second color temperature of 5000 K.
  • a color temperature adjusting circuit for adjusting a color temperature of a light- emitting device wherein the light- emitting device has a driving current and a first light-emitting unit connected in series to the color temperature adjusting circuit, comprising:
  • a first circuit electrically connected to the first light-emitting unit, having a first voltage drop and a second light-emitting unit, and adjusting the color temperature to a first status
  • a second circuit connected in parallel to the first circuit, having a second voltage drop and a third light-emitting unit, and adjusting the color temperature to a second status, wherein the second voltage drop is smaller than the first voltage drop so that when the second circuit is turned on, the first circuit is turned off, and when one of the first circuit and the second circuit is in operation, the driving current has a variation quantity proportional to a difference between the first voltage drop and the second voltage drop.
  • a color temperature adjusting circuit for adjusting a color temperature of a light- emitting device wherein the light- emitting device has a first light- emitting unit connected in series to the color temperature adjusting circuit, comprising:
  • a first circuit electrically connected to the first light-emitting unit, having a second light- emitting unit, and adjusting the color temperature to a first status
  • a second circuit connected in parallel to the first circuit, having a third light- emitting unit, and adjusting the color temperature to a second status.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

A color temperature adjusting circuit for adjusting a color temperature of a light-emitting device is provided. The light-emitting device has a first light-emitting unit connected in series to the color temperature adjusting circuit. The color temperature adjusting circuit includes a first circuit electrically connected to the first light-emitting unit, having a second light-emitting unit, and adjusting the color temperature to a first status; and a second circuit connected in parallel to the first circuit, having a third light-emitting unit, and adjusting the color temperature to a second status.

Description

LIGHTING SYSTEM AND COLOR TEMPERATURE ADJUSTING
CIRCUIT
CROSS-REFERENCE TO RELATED APPLICATION AND CLAIM OF PRIORITY
[0001] The application claims the benefit of Taiwan Patent Application No. 102200228, filed on January 4, 2013, in the Taiwan Intellectual Property Office, the disclosures of which are incorporated herein in their entirety by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a lighting system and a color temperature adjusting circuit, and more particularly to a lighting system and a color temperature adjusting circuit which modulate the color temperature of the light-emitting diode (LED) in the way of pulse width modulation, and simultaneously maintain a stable driving voltage and a stable driving current.
BACKGROUND OF THE INVENTION
[0003] Please refer to Fig. 1(A), which shows a lighting system for modulating the color temperature of the light- emitting diode in the prior art. The lighting system includes a power supply unit 11 and a light-emitting device 10. The power supply unit 11 includes a control unit 111. The light- emitting device 10 includes a light-emitting unit 101 and a rectifying unit 102. The light- emitting unit 101 includes a plurality of light- emitting diodes 1011. The rectifying unit 102 includes a transistor 1021 and a plurality of light- emitting diodes 1022. The control unit 111 provides a control signal to the transistor 1021. When the transistor 1021 is turned on, the potential of the rectifying unit 102 is lowered, which causes II to be risen abruptly. However, when the transistor 1021 is turned off, the potential of the rectifying unit 102 is risen, which causes II to be lowered abruptly. The substantial variation of the transient current not only causes the light- emitting diodes 1011, 1022 to be flickering, but also increases the difficulty in regulating the output over the load transients for the power supply unit 11.
[0004] Please refer to Fig. 1(B), which shows another lighting system for modulating the color temperature of the light- emitting diode in the prior art. The lighting system includes a power supply unit 21 and a light-emitting device 11. The power supply unit 21 includes a control unit 211. The light- emitting device 11 includes a light-emitting unit 111 and a rectifying unit 112. The light- emitting unit 111 includes a plurality of light- emitting diodes 1111. The rectifying unit 112 includes a transistor 1122 and a plurality of light- emitting diodes 1121. The control unit 211 provides a control signal to the transistor 1122. When the transistor 1122 is turned on, II is risen and Vo is lowered. However, when the transistor 1122 is turned off, II is lowered and Vo is risen. The substantial variations of the transient current and voltage not only cause the light- emitting diodes 1111, 1121 to be flicking, but also increases the difficulty in regulating the output over the load transients for the power supply unit 21. Moreover, if the voltage difference of the rectifying unit 112 is to be similar to that of the light- emitting unit 111, when the light- emitting diode 1111 is formed by a bluelight- emitting chip and phosphors, which has a forward conduction voltage of about 3 V, and the light-emitting diode 1121 is the redlight-emitting diode having a forward conduction voltage of about 2 V, the amount of the light- emitting diodes 1121 in the rectifying unit 112 is about 1.5 times that in the light-emitting unit 111. Even if the redlight-emitting diode 1121 is replaced with a light- emitting diode which is also formed by a bluelight-emitting chip and phosphors, intrinsically having same forward conduction voltage of about 3 V as well, the amount of the light-emitting diodes 1121 in the rectifying unit 112 is about the same as that in the light- emitting unit 111. Therefore, to make the voltage difference of the light- emitting unit 111 similar to that of the rectifying unit 112, 2 times the amount of the light-emitting diodes 1111 in the light-emitting unit 111 is required at the least. That is, more materials are consumed, and a larger space is required to receive the light- emitting device 11.
[0005] In order to overcome the drawbacks in the prior art, a lighting system and a color temperature adjusting circuit are provided. The particular design in the present invention not only solves the problems described above, but also is easier to be implemented. Thus, the present invention has the utility for the industry.
SUMMARY OF THE INVENTION
[0006] In accordance with an aspect of the present invention, a lighting system and a color temperature adjusting circuit are provided. Through the present invention, when the color temperature of the light- emitting diode is modulated in the way of PWM, a lesser amount of light- emitting diodes is used, and the voltage and current for driving the light- emitting diode can be maintained more stably. This improves the flickering of the light- emitting diode, enhances the performance of the light- emitting diode, reduces the requirement for the high load regulation specification of the power supply unit, and reduces the cost.
[0007] In accordance with another aspect of the present invention, a lighting system is provided. The lighting system includes a power supply unit; and a light-emitting device coupled to the power supply unit, having a driving current, and including a first light- emitting unit; and a color temperature adjusting circuit connected in series to the first light- emitting unit, adjusting a color temperature of the light- emitting device, and including a first circuit electrically connected to the first light- emitting unit, having a first voltage drop and a second light- emitting unit, and adjusting the color temperature to a first status; and a second circuit connected in parallel to the first circuit, having a second voltage drop and a third light-emitting unit, and adjusting the color temperature to a second status, wherein the second voltage drop is smaller than the first voltage drop so that when the second circuit is turned on, the first circuit is turned off, and when one of the first circuit and the second circuit is in operation, the driving current has a variation quantity proportional to a difference between the first voltage drop and the second voltage drop.
[0008] In accordance with a further aspect of the present invention, a color temperature adjusting circuit for adjusting a color temperature of a light- emitting device is provided. The light- emitting device has a driving current and a first light-emitting unit connected in series to the color temperature adjusting circuit. The color temperature adjusting circuit includes a first circuit electrically connected to the first light- emitting unit, having a first voltage drop and a second light-emitting unit, and adjusting the color temperature to a first status; and a second circuit connected in parallel to the first circuit, having a second voltage drop and a third light- emitting unit, and adjusting the color temperature to a second status, wherein the second voltage drop is smaller than the first voltage drop so that when the second circuit is turned on, the first circuit is turned off, and when one of the first circuit and the second circuit is in operation, the driving current has a variation quantity proportional to a difference between the first voltage drop and the second voltage drop.
[0009] In accordance with further another aspect of the present invention, a color temperature adjusting circuit for adjusting a color temperature of a light- emitting device is provided. The light-emitting device has a first light- emitting unit connected in series to the color temperature adjusting circuit. The color temperature adjusting circuit includes a first circuit electrically connected to the first light- emitting unit, having a second light- emitting unit, and adjusting the color temperature to a first status; and a second circuit connected in parallel to the first circuit, having a third light- emitting unit, and adjusting the color temperature to a second status.
[0010] The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed descriptions and accompanying drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Fig. 1(A) shows a lighting system for modulating the color temperature of the light- emitting diode in the prior art;
[0012] Fig. 1(B) shows another lighting system for modulating the color temperature of the light- emitting diode in the prior art; and
[0013] Fig. 2 shows a lighting system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0014] The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for the purposes of illustration and description only; it is not intended to be exhaustive or to be limited to the precise form disclosed.
[0015] Please refer to Fig. 2, which shows a lighting system according to an embodiment of the present invention. The lighting system includes a power supply unit 31 and a light-emitting device 2. The power supply unit 31 includes a control unit 311. The light- emitting device 2 includes a first light- emitting unit 23 and a color temperature adjusting circuit 4. The color temperature adjusting circuit 4 includes a first circuit 22 and a second circuit 21. The first light-emitting unit 23 includes a plurality of light-emitting diodes 231-233. The first circuit 22 includes a second light- emitting unit 221. The second light-emitting unit 221 includes a plurality of light- emitting diodes 2211-2213. The second circuit 21 includes a third light- emitting unit 211 and a transistor 212. The third light-emitting unit 211 includes a plurality of light- emitting diodes 2111, 2112. The anode of the light- emitting diode 231 is connected to the positive terminal of the power supply unit 31. The cathode of the light- emitting diode 233 is connected to the anode of the light- emitting diode 2111 and the anode of the light- emitting diode 2211 respectively. The cathode of the light- emitting diode 2213 is connected to the source of the transistor 212 and grounded. The drain of the transistor 212 is connected to the cathode of the light- emitting diode 2112, the gate thereof is connected to the control unit 311, and the source thereof is connected to the negative terminal of the power supply unit 31 and grounded. [0016] The control unit 311 provides a PWM signal to the gate of the transistor 212. The PWM signal controls the transistor 212 to be turned on or turned off, thereby causing the third light-emitting unit 211 to be turned on or turned off. That is, when the transistor 212 is controlled by the PWM signal to be turned on, the third light- emitting unit 211 is turned on so that the light- emitting diodes 2111, 2112 emit light. However, when the transistor 212 is controlled by the PWM signal to be turned off, the third light- emitting unit 211 is turned off so that the light- emitting diodes 2111, 2112 do not emit light.
[0017] The forward conduction voltage of the second circuit 21 has to be smaller than that of the first circuit 22 so that when the transistor 212 is turned on, the second light- emitting unit 221 is turned off, and when the transistor 212 is turned off, the second light- emitting unit 221 is turned on. The conduction voltage of the first light- emitting unit 23 being connected in series to the second circuit 21 is very close to that of the first light- emitting unit 23 being connected in series to the first circuit 22. Therefore, the alternation of the second circuit 21 and the first circuit 22 only causes a tiny transient variation in the driving current II. The variation in the driving current II is proportional to the difference between the forward conduction voltage of the first circuit 22 and the forward conduction voltage of the second circuit 21.
[0018] The first light-emitting unit 23 emits the white light having a color temperature of 4500 K (Kelvin). The second light- emitting unit 221 emits the white light having a color temperature of 5000 K. The third light- emitting unit 211 emits the red light. When the current is the same, the ratio of the lumen value of the first light-emitting unit 23 to the lumen value of the second light- emitting unit 22 is 50:45. The proportion of the red light in the total lumen value is changed by the ratio of the turn-on time of the third light-emitting unit 211 so that the light-emitting device 2 can emit white lights having different color temperatures. The higher the ratio of the turn-on time of the third light- emitting unit 211 is, the lower the color temperature of the white light emitted by the light emitting device 2 is.
[0019] According to an embodiment of the present invention, the first light- emitting unit 23 includes a single light-emitting diode, a plurality of light- emitting diodes connected in parallel, a plurality of light-emitting diodes connected in series, or a plurality of light- emitting diode modules connected in series, wherein each light- emitting diode module includes a plurality of light- emitting diodes connected in parallel.
[0020] According to an embodiment of the present invention, the second light- emitting unit 221 includes a single light-emitting diode, a plurality of light- emitting diodes connected in parallel, a plurality of light-emitting diodes connected in series, or a plurality of light- emitting diode modules connected in series, wherein each light- emitting diode module includes a plurality of light- emitting diodes connected in parallel.
[0021] According to an embodiment of the present invention, the third light- emitting unit 211 includes a single light-emitting diode, a plurality of light- emitting diodes connected in parallel, a plurality of light-emitting diodes connected in series, or a plurality of light- emitting diode modules connected in series, wherein each light- emitting diode module includes a plurality of light- emitting diodes connected in parallel.
[0022] According to an embodiment of the present invention, the transistor 212 is a MOSFET.
[0023] On condition that the voltage drop of the rectifying unit 112 of Fig. 1(B) is identical to that of the light-emitting unit 111 of Fig. 1(B), and that the luminance of the light-emitting device 11 of Fig. 1(B) is identical to that of the light-emitting device 2 of the present invention, the amount of light- emitting diodes used in the second light- emitting unit 221 of the present invention plus that used in the first light- emitting unit 23 of the present invention is equal to that used in the light-emitting unit 111 of Fig. 1(B), and the amount of light-emitting diodes used in the third light- emitting unit 211 of the present invention is less than that used in the rectifying unit 112 of Fig. 1(B). Accordingly, the amount of overall light- emitting diodes used in the present invention can be greatly reduced.
[0024] Embodiments
1. A lighting system, comprising:
a power supply unit; and
a light- emitting device coupled to the power supply unit, having a driving current, and including:
a first light- emitting unit; and
a color temperature adjusting circuit connected in series to the first light- emitting unit, adjusting a color temperature of the light-emitting device, and including:
a first circuit electrically connected to the first light- emitting unit, having a first voltage drop and a second light-emitting unit, and adjusting the color temperature to a first status; and
a second circuit connected in parallel to the first circuit, having a second voltage drop and a third light-emitting unit, and adjusting the color temperature to a second status, wherein the second voltage drop is smaller than the first voltage drop so that when the second circuit is turned on, the first circuit is turned off, and when one of the first circuit and the second circuit is in operation, the driving current has a variation quantity proportional to a difference between the first voltage drop and the second voltage drop.
2. The lighting system of Embodiment 1, wherein:
the power supply unit has a positive terminal and a negative terminal, and includes a control unit providing a control signal;
the first light- emitting unit has a first terminal connected to the positive terminal, and a second terminal;
the first circuit has a third terminal connected to the second terminal, and a fourth terminal being grounded;
the second circuit has a fifth terminal and a sixth terminal, and includes a transistor, wherein the fifth terminal is connected to the second terminal, the sixth terminal is connected to a source of the transistor, the negative terminal and grounded, and the transistor is controlled by the control signal to be one of turned on and turned off to control the third light- emitting unit to be one of turned on and turned off;
when the transistor is turned on, the third light-emitting unit is turned on, and the second light- emitting unit is turned off; and
when the transistor is turned off, the third light-emitting unit is turned off, and the second light-emitting unit is turned on.
3. The lighting system of any one of Embodiments 1-2, wherein the control signal is a pulse width modulation (PWM) signal.
4. The lighting system of any one of Embodiments 1-3, wherein:
the first light- emitting unit includes one selected from a group consisting of a single light- emitting diode, a plurality of light-emitting diodes connected in parallel, a plurality of light- emitting diodes connected in series, and a plurality of light- emitting diode modules connected in series; and each the light- emitting diode module includes the plurality of light- emitting diodes connected in parallel.
5. The lighting system of any one of Embodiments 1-4, wherein:
the second light- emitting unit includes one selected from a group consisting of a single light-emitting diode, a plurality of light- emitting diodes connected in parallel, a plurality of light-emitting diodes connected in series, and a plurality of light-emitting diode modules connected in series; and
each the light- emitting diode module includes the plurality of light- emitting diodes connected in parallel.
6. The lighting system of any one of Embodiments 1-5, wherein:
the third light-emitting unit includes one selected from a group consisting of a single light-emitting diode, a plurality of light- emitting diodes connected in parallel, a plurality of light-emitting diodes connected in series, and a plurality of light-emitting diode modules connected in series; and
each the light- emitting diode module includes the plurality of light- emitting diodes connected in parallel.
7. The lighting system of any one of Embodiments 1-6, wherein the transistor is a MOSFET.
8. The lighting system of any one of Embodiments 1-7, wherein the MOSFET has a drain connected to the third light- emitting unit, a gate receiving the control signal, and a source connected to the negative terminal and grounded.
9. The lighting system of any one of Embodiments 1-8, wherein:
the first light- emitting unit emits a first white light having a first color temperature of 4500 K (Kelvin);
the second light-emitting unit emits a second white light having a second color temperature of 5000 K; and
the third light- emitting unit emits a red light. 10. A color temperature adjusting circuit for adjusting a color temperature of a light- emitting device, wherein the light- emitting device has a driving current and a first light-emitting unit connected in series to the color temperature adjusting circuit, comprising:
a first circuit electrically connected to the first light-emitting unit, having a first voltage drop and a second light-emitting unit, and adjusting the color temperature to a first status; and
a second circuit connected in parallel to the first circuit, having a second voltage drop and a third light-emitting unit, and adjusting the color temperature to a second status, wherein the second voltage drop is smaller than the first voltage drop so that when the second circuit is turned on, the first circuit is turned off, and when one of the first circuit and the second circuit is in operation, the driving current has a variation quantity proportional to a difference between the first voltage drop and the second voltage drop.
11. A color temperature adjusting circuit for adjusting a color temperature of a light- emitting device, wherein the light- emitting device has a first light- emitting unit connected in series to the color temperature adjusting circuit, comprising:
a first circuit electrically connected to the first light-emitting unit, having a second light- emitting unit, and adjusting the color temperature to a first status; and
a second circuit connected in parallel to the first circuit, having a third light- emitting unit, and adjusting the color temperature to a second status.
[0025] While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.

Claims

WHAT IS CLAIMED IS:
1. A lighting system, comprising:
a power supply unit; and
a light- emitting device coupled to the power supply unit, having a driving current, and including:
a first light- emitting unit; and
a color temperature adjusting circuit connected in series to the first light- emitting unit, adjusting a color temperature of the light-emitting device, and including:
a first circuit electrically connected to the first light- emitting unit, having a first voltage drop and a second light-emitting unit, and adjusting the color temperature to a first status; and
a second circuit connected in parallel to the first circuit, having a second voltage drop and a third light-emitting unit, and adjusting the color temperature to a second status, wherein the second voltage drop is smaller than the first voltage drop so that when the second circuit is turned on, the first circuit is turned off, and when one of the first circuit and the second circuit is in operation, the driving current has a variation quantity proportional to a difference between the first voltage drop and the second voltage drop.
2. A lighting system as claimed in Claim 1, wherein:
the power supply unit has a positive terminal and a negative terminal, and includes a control unit providing a control signal;
the first light- emitting unit has a first terminal connected to the positive terminal, and a second terminal; the first circuit has a third terminal connected to the second terminal, and a fourth terminal being grounded;
the second circuit has a fifth terminal and a sixth terminal, and includes a transistor, wherein the fifth terminal is connected to the second terminal, the sixth terminal is connected to a source of the transistor, the negative terminal and grounded, and the transistor is controlled by the control signal to be one of turned on and turned off to control the third light- emitting unit to be one of turned on and turned off;
when the transistor is turned on, the third light-emitting unit is turned on, and the second light- emitting unit is turned off; and
when the transistor is turned off, the third light-emitting unit is turned off, and the second light-emitting unit is turned on.
3. A lighting system as claimed in Claim 2, wherein the control signal is a pulse width modulation (PWM) signal.
4. A lighting system as claimed in Claim 2, wherein:
the first light- emitting unit includes one selected from a group consisting of a single light- emitting diode, a plurality of light-emitting diodes connected in parallel, a plurality of light- emitting diodes connected in series, and a plurality of light- emitting diode modules connected in series; and
each the light- emitting diode module includes the plurality of light- emitting diodes connected in parallel.
5. A lighting system as claimed in Claim 2, wherein:
the second light- emitting unit includes one selected from a group consisting of a single light-emitting diode, a plurality of light- emitting diodes connected in parallel, a plurality of light-emitting diodes connected in series, and a plurality of light-emitting diode modules connected in series; and
each the light- emitting diode module includes the plurality of light- emitting diodes connected in parallel.
6. A lighting system as claimed in Claim 2, wherein:
the third light-emitting unit includes one selected from a group consisting of a single light-emitting diode, a plurality of light- emitting diodes connected in parallel, a plurality of light-emitting diodes connected in series, and a plurality of light-emitting diode modules connected in series; and
each the light- emitting diode module includes the plurality of light- emitting diodes connected in parallel.
7. A lighting system as claimed in Claim 2, wherein the transistor is a MOSFET.
8. A lighting system as claimed in Claim 7, wherein the MOSFET has a drain connected to the third light-emitting unit, a gate receiving the control signal, and a source connected to the negative terminal and grounded.
9. A lighting system as claimed in Claim 2, wherein:
the first light- emitting unit emits a first white light having a first color temperature of 4500 K (Kelvin);
the second light-emitting unit emits a second white light having a second color temperature of 5000 K; and
the third light- emitting unit emits a red light.
10. A color temperature adjusting circuit for adjusting a color temperature of a light- emitting device, wherein the light- emitting device has a driving current and a first light-emitting unit connected in series to the color temperature adjusting circuit, comprising:
a first circuit electrically connected to the first light-emitting unit, having a first voltage drop and a second light-emitting unit, and adjusting the color temperature to a first status; and
a second circuit connected in parallel to the first circuit, having a second voltage drop and a third light-emitting unit, and adjusting the color temperature to a second status, wherein the second voltage drop is smaller than the first voltage drop so that when the second circuit is turned on, the first circuit is turned off, and when one of the first circuit and the second circuit is in operation, the driving current has a variation quantity proportional to a difference between the first voltage drop and the second voltage drop.
11. A color temperature adjusting circuit for adjusting a color temperature of a light- emitting device, wherein the light- emitting device has a first light- emitting unit connected in series to the color temperature adjusting circuit, comprising:
a first circuit electrically connected to the first light-emitting unit, having a second light- emitting unit, and adjusting the color temperature to a first status; and
a second circuit connected in parallel to the first circuit, having a third light- emitting unit, and adjusting the color temperature to a second status.
PCT/US2013/078007 2013-01-04 2013-12-27 Lighting system and color temperature adjusting circuit WO2014107406A1 (en)

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