CN1305352C

CN1305352C - Charging IC circuit of camera flash lapm

Info

Publication number: CN1305352C
Application number: CNB021602662A
Authority: CN
Inventors: 林静坤; 陈勇志; 陈天赐
Original assignee: YUANCHUANG SCIENCE AND TECHNOLOGY Co Ltd
Current assignee: YUANCHUANG SCIENCE AND TECHNOLOGY Co Ltd
Priority date: 2002-12-31
Filing date: 2002-12-31
Publication date: 2007-03-14
Anticipated expiration: 2022-12-31
Also published as: CN1514526A

Abstract

The present invention relates to a charging IC circuit for a flash lamp of a camera, which comprises a single hit unit, an R-S locking device, a pulse width modulation control circuit and a ready control unit, wherein the single hit unit is used for providing a square signal; the R-S locking device is connected to the single hit unit; the pulse width modulation control circuit is mainly composed of a reference voltage source, an oscillator, a pulse width modulation comparator, a voltage boosting comparator and a current source; the ready control unit is mainly composed of a field effect transistor whose source electrode is connected to the output end of the R-S locking. Because the circuit is integrated to control the charge of the flash lamp, the present invention has the advantages of small size, easy integration, charging current control, charging speed increase, automatic recharging, etc.

Description

The charging integrated circuit of camera flash-light

Technical field

The present invention relates to photoflash lamp, more detailed it, be the charging integrated circuit that refers to a kind of camera flash-light.

Background technology

Known camera flash-light charging circuit is normally combined by a plurality of dispersion electronic components (for example electric capacity, transistor, resistance or the like), and not only overall volume is bigger, also more consuming time during assembling, consumption cost.Known in addition camera flash-light charging circuit all has immediate current excessive, the shortcoming that the stand-by period is of a specified duration excessively, and charging current belongs to big electric current, easily causes battery to damage.

Summary of the invention

Main purpose of the present invention is promptly providing a kind of charging integrated circuit of camera flash-light, and its immediate current is less, and can reach ready state fast, and the stand-by period is shorter.

Of the present invention time a purpose is the charging integrated circuit that is to provide a kind of camera flash-light, and electric current is controlled in its charging process, more can not damage battery.

A further object of the present invention provides a kind of charging integrated circuit of camera flash-light, and the volume of its integrated circuit is littler than known circuits, has better product applicability.

For achieving the above object, the invention provides a kind of charging integrated circuit of camera flash-light, include:

First one shots is a circuit and square-wave, and square-wave signal is provided;

The R-S latch, have one and set end (set), reset end (reset) and at least one output, this setting end is electrically connected at this first one shots, and the output voltage values of this output can be subjected to the signal controlling of this setting end and this replacement end and remain in a kind of output state;

Pulse width modulation control (PWM control) circuit, mainly by a reference voltage source, an oscillator, a pulse width modulation (PWM) comparator, boost comparator and a current source are formed, wherein, this reference voltage source provides reference voltage, this oscillator is connected in the first input end of this pulse width modulation comparator, a reference voltage partial pressure unit is connected in second input of this pulse width modulation comparator, the output of this R-S latch is connected in the 3rd input of this pulse width modulation comparator by an inverter and field-effect transistor, and this current source also is connected in the 3rd input; The output of this comparator that boosts is connected in the replacement end of this R-S latch;

Ready control unit mainly is made of a field-effect transistor, and the gate of this field-effect transistor is connected in the output of this R-S latch.

The charging integrated circuit of described camera flash-light, wherein more include: one is filled (refresh) circuit again, have a partial pressure unit and be connected in this reference voltage source, the output of this partial pressure unit is less than reference voltage, be connected in second one shots by a comparator, this second one shots is connected in the setting end of this R-S latch.

Via above-mentioned structure, can know and understand advantage of the present invention:

One, the charging interval is short: allow pwm pulse open charging at the very start when charging, save from starting to the time of delay that begins to charge, can reach ready state in the short time at the utmost point, can use photoflash lamp in the very short time interval.

Two, charging current is controlled, more can not damage battery: utilize the characteristic of pwm control circuit, electric current can effectively be avoided damaging battery, and then prolonged the life-span of battery by little and greatly to capacitor of flash lamp charging, avoid the instantaneous large-current phenomenon.

Three, volume is less: the present invention is integrated in the element that majority disperses in the integrated transistor, can effectively reduce the integrated circuit volume, has better product applicability.

Four, provide and recharge the road, the convenient use: utilize the circuit detecting because of capacity fall off produces the phenomenon of undertension, recharge automatically, increase the convenience that uses to the voltage of setting.

Description of drawings

Fig. 1 is the circuit structure diagram of a preferred embodiment of the present invention;

Fig. 2 is the operating principle key diagram of a preferred embodiment of the present invention.

Embodiment

Relevant detailed structure of the present invention, feature and effect below are lifted a preferred embodiment now, and cooperate diagram to be further described, wherein:

See also Fig. 1, the charging integrated circuit 10 of a kind of camera flash-light that a preferred embodiment of the present invention provided, can be used to cooperate and be implemented on the camera (not shown), this charging integrated circuit 10 mainly is made up of first one shots 11, R-S latch 21, pulse width modulation control (PWM control) circuit 31 and a ready control unit 41, wherein:

This first one shots 11 is circuit and square-wave, and square-wave signal is provided;

This R-S latch 21, have a setting (Set) 22, replacements of end (Reset) end 24 and at least one output Q26, this setting end 22 is electrically connected at this first one shots 11, and the output voltage values of this output Q26 can be subjected to the signal controlling of this setting end 22 and this replacement end 24 and remain in a kind of output state;

This pulse width modulation control circuit 31 mainly is made up of a reference voltage source 32, oscillator 34, PWM (pulse width modulation) comparator 36, boost comparator 38 and a current source 39.Wherein:

This reference voltage source 32 is in order to provide reference voltage;

This oscillator 34 is connected in the first input end (-) of this PWM comparator 36, a reference voltage partial pressure unit is connected in second input (+) of this PWM comparator 36, adjustable settings PWM maximum pulse, the output of this R-S latch 21 is connected in the 3rd input (+) of this PWM comparator 36 by an inverter 361 and field-effect transistor 362, the 3rd input also is connected in an external SS end, can be for cooperating an external electric capacity (not shown), to determine whether this pulse width modulation control circuit 31 starts, reach the speed that pulse is changed from small to big;

This current source 39 also is connected in the 3rd input (+) of this PWM comparator 36;

This output that boosts comparator 38 is connected in the replacement end 24 of this R-S latch 21;

This ready control unit 41, being mainly a field-effect transistor constitutes. and the gate of this field-effect transistor (gate) is connected in the output of this R-S latch 21, drain (drain) is to be output, can be for the ready signal light (not shown) that is connected on the camera (not shown);

The present invention more includes:

Fill (refresh) circuit 51 again, have a partial pressure unit 52 and be connected in reference voltage source 32, the output of this partial pressure unit 52 be about this reference voltage source 32 magnitude of voltage 90%, promptly less than reference voltage in a predetermined value.Be connected in second one shots 56 by a comparator 54, this second one shots 56 is connected in the setting end 22 of this R-S latch 21;

By the combination of foregoing circuit, can provide the charging circuit for flashlamp that a volume is less, charging rate is fast.

Please consult Fig. 1 again, the present invention is when using, can be with the installation of on the camera, when the user judge or the extraneous light of the photosensitive elements sense of camera own after think and need to use photoflash lamp and charging circuit is opened, then this first one shots 11 is promptly received the signal that is changeed high signal (high) by low signal (low), and the square wave that sends proper width makes R-S latch 21 enter set condition, the output Q26 of this R-S latch 21 promptly sends the signal of high signal (high) and starts this pulse width modulation control circuit 31, and the output of this ready control unit 41 is low signal (low), when if this output is connected in preparation (ready) signal light, then preparing (ready) signal light can be not shinny;

As shown in Figure 2, when this pulse width modulation control circuit 31 begins to move, to be external in the trough of SS end pwm control circuit electric capacity (not shown) current potential quick charge relatively at the beginning earlier to these oscillator 34 output triangular waves, after arriving trough, switching to this current source (1uA) 39 charges, pwm pulse is opened, beginning is extremely charged to capacitor of flash lamp greatly by little, so can output promptly be arranged at pulse width modulation control circuit 31 at the beginning, the electric capacity of photoflash lamp promptly begins charging, can reduce the whole time of capacitor of flash lamp charging like this; Voltage in the capacitor of flash lamp and reference voltage can be compared by this comparator 38 that boosts and to learn and be charged to predetermined voltage whether, after reaching predetermined voltage, this comparator 38 that boosts is promptly exported high signal (high), this R-S latch 21 is promptly reseted (reset), this output Q26 promptly exports low signal (low), this pulse width modulation control circuit 31 promptly cuts out, and the output of this ready control unit 41 is high signal (high), has so far finished the program of charging.

If all be not activated photoflash lamp always, the then electric leakage (leakagecurrent) that capacitor of flash lamp can be slowly, voltage promptly can slowly descend, in case reduce to predetermined voltage (for example 90%), then this comparator 54 that recharges road 51 can be judged undertension and export high signal (high) with this reference voltage source 32 by this partial pressure unit 52, this second one shots 56 promptly sends the square wave of proper width and makes this R-S latch 21 enter set condition, and and then starts this pulse width modulation control circuit 31 and charge.

Start photoflash lamp after finishing charging, then capacitor of flash lamp is a sudden discharge, and capacitance voltage is promptly much smaller than predetermined voltage, and then this pulse width modulation control circuit 31 promptly can start once more, enters charge mode, and repeats aforementioned process.

Claims

1, a kind of charging integrated circuit of camera flash-light is characterized in that, includes:

The R-S latch, have one and set end, reset end and at least one output, this setting end is electrically connected at this first one shots, and the output voltage values of this output can be subjected to the signal controlling of this setting end and this replacement end and remain in a kind of output state;

The pulse width modulation control circuit, mainly by a reference voltage source, an oscillator, a pulse width modulation comparator, boost comparator and a current source are formed, wherein, this reference voltage source provides reference voltage, this oscillator is connected in the first input end of this pulse width modulation comparator, a reference voltage partial pressure unit is connected in second input of this pulse width modulation comparator, the output of this R-S latch is connected in the 3rd input of this pulse width modulation comparator by an inverter and field-effect transistor, and this current source also is connected in the 3rd input; The output of this comparator that boosts is connected in the replacement end of this R-S latch;

2, the charging integrated circuit of camera flash-light according to claim 1, it is characterized in that: wherein more include: one recharges the road, have a partial pressure unit and be connected in this reference voltage source, the output of this partial pressure unit is less than reference voltage, be connected in second one shots by a comparator, this one shots is connected in the setting end of this R-S latch.