JPH11242265A - Light receiving circuit and flash device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve a response characteristic to a received light signal in a flash device having a slave function, and to provide a flash device capable of accurately controlling and setting a response distance range to a received light signal within a desired range. provide. A first transistor for absorbing an output of a light receiving sensor in response to a base bias state is provided.
Having the same characteristics as the first transistor 20, and changing the base bias state of the first transistor 20 to a plurality of resistors 10,
11 and a second control transistor 21 controlled together with the capacitor 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light receiving circuit for receiving an externally supplied signal light (pulse light), and a light receiving circuit incorporating the light receiving circuit. The present invention relates to a flash device provided with a so-called slave function that can be controlled by a computer.

[0002]

2. Description of the Related Art Conventionally, a flash device has been useful as an artificial light source for taking a picture, and has a so-called slave function capable of controlling its own light emitting operation by receiving a signal light supplied from the outside. Flash devices are also well known (Japanese Unexamined Patent Publication No. Sho 61
No. 17133).

A flash device having a slave function receives a signal light (pulse light) supplied from the outside, generates a light signal in response to the received signal light, and absorbs the light signal. And a light emission control circuit for controlling a light emission operation of the flash tube to a light emission operation in response to the signal light by an output signal of the light reception circuit.

FIG. 2 is a main part electric circuit diagram of the flash device disclosed in Japanese Patent Application Laid-Open No. 61-17133, including the above-mentioned light receiving circuit. The flash device shown in FIG. 2 includes a DC low-voltage power supply 1 having a configuration known as a flash device, such as a DC low-voltage power supply as a battery, and a DC / DC converter circuit, and a main unit connected to both ends of the DC high-voltage power supply 1. A series body of a capacitor 2, a flash tube 3 connected to both ends of the main capacitor 2, and a control element 4, for example, an insulated gate bipolar transistor for controlling the light emitting operation of the flash tube 3, and the flash tube 3 and the control element A light emission control circuit 5 for controlling the light emission operation of the flash tube 3 by controlling the operation of the flash tube 3.

A light receiving circuit 6 which receives an externally supplied signal light and generates an output signal for controlling the operation of the light emission control circuit 5 receives the signal light and outputs an electric signal. A light receiving sensor 7 and a control transistor 9 having a collector and an emitter connected to both ends of the light receiving sensor 7
A plurality of resistors 10 and 11 connected in series between the power supply Vd and the base of the control transistor 9; a capacitor 12 connected between the base and the emitter of the control transistor 9; a connection point C1 of the resistors 10 and 11; A diode 13 connected in the forward direction between a connection point C2 between the light-receiving sensor 7 and the collector of the control transistor 9, and connected to both ends of the light-receiving sensor 7; A differential circuit comprising a series body of a capacitor and a resistor, and an amplifier circuit for amplifying and outputting a signal generated in the resistor and supplying the amplified signal to the light emission control circuit as an output signal of the light receiving circuit. Have been.

[0006] First, the base of the control transistor 9 in the absorbing means 8 is provided with a resistor 10 in order to prevent adverse effects on the light receiving sensor 7 due to fluctuations in the steady light (ambient light) and the intensity of the signal light. , 11, a capacitor 12, and a diode 13 apply a predetermined bias.

When the light receiving sensor 7 receives the signal light supplied from the outside, the light receiving sensor 7 converts the signal light into an electric signal and supplies a current to the differentiating circuit 14. At this time, the signal generated in the resistor 16 is amplified. Input to the circuit 17.

The amplification circuit 17 amplifies the input signal and supplies the amplified signal to the light emission control circuit 5, whereby the light emission control circuit 5 starts operating, for example, a so-called light emission start operation or light emission stop operation of the flash tube 3. The light emission operation is controlled.

The light receiving circuit 6 operates so that the light emission control circuit 5 does not operate with respect to the fluctuation of the steady light other than the supply of the signal light.

That is, in general, the fluctuation of the stationary light is slower in rising characteristics than when the signal light (pulse light) is generated. Therefore, the fluctuation of the stationary light is reduced by the time constant of the resistors 10 and 11 and the capacitor 12. The operation of the control transistor 9 is controlled accordingly.

Therefore, the control transistor 9 operates so as to absorb the electric signal generated in the light receiving sensor 7 due to the fluctuation of the steady light when the fluctuation of the steady light.

As a result, the light reception sensor 7
The electric signal generated in the differential circuit 14 and the amplifying circuit 17
Is not transmitted to the light emission control circuit 5 via the That is, the absorbing means 8 including the resistors 10 and 11 and the control transistor 9 prevents a malfunction in which the light emission control circuit 5 operates based on the steady light fluctuation.

When the intensity of the supply signal light is high, for example, when the supply source of the signal light is located very close, the light receiving circuit 6 operates so that the light receiving sensor 7 is not saturated.

That is, when the signal light intensity is high, the electric signal generated by the light receiving sensor 7 also increases, so that the collector potential of the control transistor 9 also increases.

On the other hand, when the collector potential of the control transistor 9 becomes high, the current which has been flowing in the loop of the resistor 10 and the diode 13 up to that point flows as the base current of the control transistor 9 via the resistor 11.

This situation is the same as the fact that the bias of the base of the control transistor 9 is deepened. As a result, a larger amount of the electric signal generated in the light receiving sensor 7 flows through the control transistor 9, that is, the electric signal is absorbed. Will be done.

In other words, the absorption means 8 including the resistor 10 and the control transistor 9 prevents the light receiving sensor 7 from being saturated due to the strong signal light intensity, thereby accurately responding to the strong signal light and flashing. The light emission operation of the tube 3 can be controlled.

Conversely, when the intensity of the supplied signal light is weak, for example, when the source of the signal light is located at a very distant position, the light receiving circuit 6 operates accurately in response to the weak signal light.

That is, in such a case, the electric signal generated when the light receiving sensor 7 receives the signal light also becomes small, and the fluctuation of the base bias of the control transistor 9 is different from the case where the signal light supply source is located at the very close position. The electric signal is hardly absorbed by the control transistor 9 and is supplied to the differentiating circuit 14 as it is.

As a result, the small electric signal is
The light is supplied to the light emission control circuit 5 via the amplifier circuit 17, whereby the light emission operation of the flash tube 3 is controlled. In other words, the light receiving circuit 6 accurately responds to the weak signal light. Operate.

The light-receiving sensor 7 of the light-receiving circuit 6 shown in FIG. 2 is connected between the collector and the emitter of the control transistor 9. For example, as shown by a broken line in FIG.
The light-receiving sensor 7 is connected to the power supply
Also, a light receiving circuit having a configuration of connecting between d and the collector of the control transistor 9 and a configuration in which the cathode of the light receiving sensor 7 in this broken line configuration is connected to another power source instead of the power source Vd,
The function of absorbing the output electric signal of the light receiving sensor 7 by the absorbing means 8 can be expected as it is.

[0022]

The light receiving circuit shown in FIG. 2 includes a light receiving sensor 7, a control transistor 9, a diode 13, and the like and includes an absorbing means 8 for absorbing an electric signal output from the light receiving sensor 7. Irrespective of the connection location of the light receiving sensor 7, it is not affected by the fluctuation of the steady light,
Also, when the intensity of the signal light supplied from the outside is high or low, the operation of the light emission control circuit 5 can be controlled accurately in response to the signal light.

However, the base bias of the control transistor 9 is set so that the light receiving circuit 6 operates in response only to the supply of the signal light without being affected by the steady light fluctuation.
0, 11, and the time constant is controlled in advance by the capacitor 12 or the like.

Therefore, the characteristics of the components used as the diode 13 and the control transistor 9 vary depending on the variation of the threshold voltage.

For example, when the threshold voltage of the diode 13 becomes smaller due to variations, the bias of the control transistor 9 becomes shallower, and when the signal light is continuously supplied from a short distance, the electric signal output from the light receiving sensor 7 is output. It is conceivable that the bypass cannot be performed sufficiently, and the light receiving sensor 7 is saturated, so that the light receiving signal cannot be output accurately.

This situation is nothing short of a limit on the short distance side to the signal light supply source to which the light receiving circuit 6 can respond. For this reason, there occurs an inconvenience that the response distance range to the signal light supply source to which the light receiving circuit 6 can respond shifts from the initially set desired distance range to the far side.

Conversely, when the threshold voltage of the diode 13 increases, the bias of the control transistor 9 increases, and when the signal light is supplied from a long distance and the intensity of the signal light decreases, the control transistor 9 needs to bypass the signal light. It is conceivable that the signal is bypassed and the light receiving sensor 7 cannot output the light receiving signal.

This situation is nothing short of the limitation on the long distance to the signal light supply source to which the light receiving circuit 6 can respond. For this reason, there arises an inconvenience that the response distance range to the signal light supply source to which the light receiving circuit 6 can respond shifts from the initially set desired distance range to the short distance side.

Further, even when the ambient temperature fluctuates, the temperature characteristics of the control transistor 9 and the diode 13 are different. As a result, the bias of the control transistor 9 fluctuates. There is a disadvantage that the response distance range to the light source shifts from the initially set desired distance range to the short distance side or the long distance side.

An object of the first invention according to the present application is to provide a light receiving circuit with improved response characteristics to a supply signal light.

An object of a second invention according to the present application is to provide a flash device including a light receiving circuit having improved response characteristics to a supply signal light.

[0032]

According to a first aspect of the present invention, there is provided a light receiving circuit configured to receive an external signal light and generate an electric signal responsive to the received signal light. A light receiving sensor, and an absorbing means for absorbing the electric signal from the light receiving sensor, the absorbing means comprising: a first control transistor for absorbing the light receiving output with an absorption amount responsive to a base bias state thereof; And a plurality of resistors connected in series between the base of the first control transistor, a capacitor connected between the base and the emitter of the first control transistor, and a collector having the same characteristics as the first control transistor. And a second control transistor connected between a connection point between the plurality of resistors and a connection point between the light receiving sensor and the collector of the first control transistor. Those were.

With the above configuration, the response range to the signal light can be accurately controlled and set without being affected by the intensity of the signal light and the fluctuation of the ambient temperature.

A flash device for realizing the object of the second invention according to the present application has a light receiving circuit having the above-described configuration and control means for controlling a flash operation based on a light receiving signal from the light receiving circuit. It is.

The configuration of the flash device is provided with a so-called slave function, and the response range to the signal light can be controlled and set accurately without being affected by the intensity of the signal light and the fluctuation of the ambient temperature. The response distance range from the short distance side to the long distance side which can respond to the light emitting light source that emits light can be accurately controlled and set to the initially set desired range.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a flash device according to the present invention will be described below with reference to FIG.

FIG. 1 is an electric circuit diagram of a main part of a flash device according to an embodiment of the present invention. In the drawing, elements having the same reference numerals as those in FIG. 2 indicate the same functional elements.

As is clear from FIG. 1, the flash device according to the present embodiment has a DC high-voltage power supply 1, a main capacitor 2, a flash tube 3, and the like as in the example of the flash device shown in FIG.
It comprises a control element 4 and a light emission control circuit 5, and further comprises a light receiving circuit 18 having a configuration different from the configuration of the light receiving circuit 6 of the example of the flash device shown in FIG.

The light receiving circuit 18 receives the signal light supplied from the outside and outputs an electric signal.
Absorbing means 1 for absorbing an electric signal output by light receiving sensor 7
9, a differentiating circuit 14 comprising a capacitor 15 and a resistor 16
And an amplification circuit 17 that amplifies a signal generated in the resistor 16 and supplies the amplified signal to the light emission control circuit 5 as an output signal of the light receiving circuit 6.

The absorbing means 19 includes a first control transistor 20 whose collector and emitter are connected to both ends of the light receiving sensor 7, a power supply Vd and a first control transistor 2
0, a plurality of resistors 10, 11 connected in series between bases
A capacitor 12 connected between the base and the emitter of the first control transistor 20;
0, the base and the collector are directly connected, and the collector and the emitter are connected between the connection point C1 between the resistors 10 and 11, the light receiving sensor 7, and the first control transistor 20.
And a second control transistor 21 connected between the node C2 and the collector of the second transistor.

The present embodiment differs from the conventional flash device shown in FIG. 2 in that the diode 12 in the conventional flash device shown in FIG.
The point is that the second control transistor 21 having the same characteristics as 0 is employed. In the present embodiment, the first control transistor 20 and the second control transistor 21 are replaced by the same manufacturer's product of the same model name,
_BE -I _C characteristic (base-emitter voltage - collector current characteristic) electrical characteristics of such are set to be the same properties.

In this embodiment, the basic operation of the light receiving circuit 18 when the steady light fluctuates or when the intensity of the supplied signal light is high, is the same as that of the light receiving circuit 6 in the conventional flash device shown in FIG. The operation is equivalent to the operation described above.

That is, the light receiving circuit 18 of the present embodiment
The absorbing means 19 comprising the second control transistor 21 and the like
By controlling the bias of the first control transistor 20 to control the absorption operation of the electric signal output from the light receiving sensor 7, the signal light supplied from the outside can be accurately output without being affected by the steady light fluctuation or the like. Operate in response.

Therefore, the light receiving circuit 18 of the present embodiment
Performs the light receiving operation of the signal light supplied by the light receiving sensor 7 without being affected by the steady light fluctuation and regardless of the intensity of the signal light supplied from the outside. To control the operation of the light emission control circuit 5 in response to the operation.

In the light receiving circuit 18 of the present embodiment, since the first control transistor 20 and the second control transistor 21 employ transistors having the same characteristics, for example, a change in the threshold voltage due to a variation in individual components. Is present, the influence of the fluctuation on the base bias of the first control transistor 20 is smaller than the influence of the fluctuation caused by the individual components between the control transistor 9 and the diode 13 in the conventional flash device shown in FIG. And become smaller.

Further, in this embodiment, since the first control transistor 20 and the second control transistor 21 employ transistors having the same characteristics, the temperature characteristics of the two control transistors 20 and 21 are substantially equal. Therefore, the first temperature caused by the fluctuation of the ambient temperature
The effect of the control transistor 20 on the base bias is also smaller than that of the conventional flash device shown in FIG.

Note that the light receiving circuit 18 in the present embodiment is
The light-receiving sensor 7 is connected between the collector and the emitter of the first control transistor 20. However, for example, the light-receiving circuit configuration in the development as shown by the broken line in FIG. The present embodiment is also applicable to a configuration in which the sensor 7 is connected between the power supply Vd and the collector of the first control transistor 20 and a configuration in which the cathode of the light receiving sensor 7 is connected to another power supply instead of the power supply Vd in the broken line configuration. Of course, an action equivalent to the action in can be expected.

[0048]

According to the first aspect of the present invention, since the absorbing operation of absorbing the extra output signal of the light receiving sensor can be performed accurately without being affected by the variation of the components and the change of the environmental temperature, the light receiving sensor can be used. The output from the device does not shift the response distance range to the light source of the signal light that can respond from the initially set desired distance range to the short distance side or the long distance side. The light receiving operation with the adjusted characteristics can be performed.

According to the second aspect of the present invention, since the response distance range of the light receiving circuit can be accurately controlled and set within a desired distance range, the response characteristic to signal light is improved, and the light receiving operation with stable characteristics is achieved. , And the control operation of the light emission control circuit.

[Brief description of the drawings]

FIG. 1 is a main part electric circuit diagram of an embodiment of a flash device according to the present invention.

FIG. 2 is a main part electric circuit diagram of a conventional flash device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 DC high voltage power supply 2 main capacitor 3 flash tube 4 control element 5 light emission control circuit 7 light receiving sensor 10 resistor 11 resistor 12 capacitor 14 differentiating circuit 15 capacitor 16 resistor 17 amplifier circuit 18 light receiving circuit 19 absorption means 20 first control transistor 21 second Control transistor

Claims (8)

[Claims] A light receiving sensor for receiving an external signal light and generating an electric signal in response to the received signal light;
Absorbing means for absorbing the electric signal from the light receiving sensor, wherein the absorbing means absorbs the light receiving output with an amount of absorption in response to the base bias state; a power supply; A plurality of resistors connected in series between the bases of the control transistors, a capacitor connected between the base and the emitter of the first control transistor, and having the same characteristics as the first control transistor; A light receiving circuit comprising: a connection point between the plurality of resistors; and a second control transistor connected between a connection point between the light receiving sensor and a collector of the first control transistor. 2. A light-receiving sensor for receiving an external signal light and generating an electric signal in response to the received signal light;
A first control transistor having a collector and an emitter connected at both ends of the light receiving sensor, a plurality of resistors connected in series between a power supply and a base of the first control transistor, and a base and an emitter of the first control transistor; And a capacitor connected to the first control transistor and having the same characteristics as the first control transistor. The base and the collector are directly connected, and the collector and the emitter are connected between the plurality of resistors, the light receiving sensor, and the first control transistor. And a second control transistor connected between a connection point of the first control transistor and the collector. 3. The light receiving circuit according to claim 1, wherein the light receiving sensor is connected between a collector and an emitter of the first control transistor. 4. The light receiving circuit according to claim 1, wherein the light receiving sensor is connected between the power supply and a collector of the first control transistor. 5. The light receiving circuit according to claim 1, wherein the light receiving sensor is connected between a power supply different from the power supply and a collector of the first control transistor. 6. The signal light according to claim 1, wherein the signal light is pulsed light.
6. The light receiving circuit according to 2, 3, 4, or 5. 7. A flash device having the light receiving circuit according to claim 1. 8. A flash device comprising: the light receiving circuit according to claim 1; and control means for controlling a flash operation based on a light receiving signal from the light receiving circuit.