JPH0712981Y2 - Flash photography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a flash photographing apparatus, and more particularly to a flash photographing apparatus for photography.

[Conventional technology]

Photographic flash photography devices typically use DC, as shown in FIG.
/ DC converters 2 to 6,8 to 11,26, a main capacitor 14 for storing light energy, light emission synchronization trigger circuits 17 to 23, and a light emitting section 24. Then, when the flash circuit is activated, the DC / DC converter operates first, and the main capacitor 14 is charged through the rectifying diode. When it is detected that this charge has reached a predetermined value, the operation of the DC / DC converter is stopped, and after that, a trigger signal is given from the trigger circuit to transfer the energy stored in the main capacitor 14 to a xenon tube or the like. It discharges to the light emitting part and emits light.

Conventionally, four input / output terminals for controlling this photographic flash photographing device have been required as shown in FIG.

That is, there are four terminals: a DC / DC converter operation stop terminal A ₂ , a DC / DC converter start terminal A ₃ , a main capacitor charge completion detection terminal A ₄ , and a light emission synchronization trigger input terminal A ₅ .

[Problems to be solved by the device]

Since the conventional one has such a large number of input / output terminals, not only is the manufacturing time-consuming and costly,
Operation could even be unstable due to poor terminal connections.

An object of the present invention is to provide a flash photography device having a small number of control terminals, which solves such a problem.

[Means (and Action) for Solving the Problems]

The present invention has been made in view of the above matters, and includes a DC / DC converter, a main capacitor charged by the converter output, a discharge tube that emits light when electric charge accumulated in the main capacitor is discharged, The detection means for detecting the charge state of the main capacitor and outputting a signal according to the charge state of the main capacitor, the signal line connected to the output of the detection means, and the signal line connected to the signal line A flashing device circuit having switching means for shifting from a first switching state to a second switching state to shift the DC / DC converter to a non-operating state when a predetermined level different from the predetermined level range is shown. Section, at least a terminal connected to the signal line, and a signal input through the terminal have a specific level within the predetermined level range. A camera circuit having a determination circuit for determining whether or not there is a signal, and a control circuit for forming the signal of the predetermined level in response to the output from the determination circuit, outputting the signal to the terminal, and performing shooting sequence control. And the DC / DC through the terminal, the charging state of the main capacitor is transmitted to the camera circuit section through the terminal.
A flash photographing device configured to transmit a signal for deactivating a converter to a flash device circuit section.

〔Example〕

FIG. 1 shows an embodiment of a photographic flash photography apparatus to which the present invention is applied, 1 is a DC voltage source, 2 is an oscillation transistor which constitutes a DC / DC converter, 3 is a resistor, 4 is an emitter of the oscillation transistor 2. An oscillation stop transistor connected between the bases, 5 and 6 are resistors, 7 is an oscillation transformer for boosting, 9 is a diode for high voltage rectification, and 10 is detection that the voltage between terminals of the main capacitor 15 has reached a predetermined value. Zener diode for driving, 11 is a transistor for driving an oscillation stop transistor, 14 is a xenon discharge tube for illuminating an object, 16 is a reference voltage source, 17 and 18 are resistors for voltage division, 19 is a comparator, 20 is a buffer circuit, 30 Is a well-known control IC (integrated circuit) that controls the camera sequence provided in the camera, TA is DC / DC
The converter start-up terminal, TB, transmits a signal corresponding to the state of charge of the main capacitor 15 to the control IC 30, and sends a DC / DC converter operation stop signal from the camera side (II) to a transistor.
A common terminal for transmitting to the base of 11, TC is a trigger input terminal for light emission synchronization. In FIG. 1, I is the flash unit side and II is the camera side. The flash device provided on the flash device unit side may of course be detachable.

Next, the operation of the embodiment shown in FIG. 1 will be described.

When the shooting preparation operation is started and it is determined in the control IC 30 that light emission is necessary at low brightness and backlight, etc., the potential of the DC / DC converter start terminal TA becomes low level. , The oscillation transistor 2 is turned on, and the blocking oscillation circuit operates. The high voltage AC signal induced in the secondary winding of the oscillating transformer 7 is rectified by the diode 9 and the charging of the main capacitor 15 is started.

If the battery 1 is deteriorated, the charging voltage of the main capacitor 15 rises extremely gradually, and it takes a long time to reach the predetermined voltage. In this case, in this embodiment, a timer (not shown) is provided in the control IC 30, starts at the same time as the signal is applied to the DC / DC converter start terminal TA, and generates a timer end signal after a predetermined time. In response to the signal, the control IC 30 sends an oscillation stop signal to the buffer circuit 20 to save power.
Output to. The buffer circuit 20 turns on the transistor 11 in order to output a voltage V _H sufficient to turn on the transistor 11 in response to the input signal for stopping oscillation, and also turns on the transistor 4 to turn on the transistor 4 for stopping oscillation. Causes a short circuit between the emitter bases of the oscillating transistor 2, so that the oscillation of the DC / DC converter is stopped and the camera sequence thereafter is stopped.

On the other hand, when the battery 1 is not deteriorated and is normal, and the charging voltage of the main capacitor 15 reaches a predetermined value (breakdown voltage of the Zener diode 10), a Zener current flows through the resistors 12 and 13, The potential of the common terminal TB rises. This potential is compared with a predetermined reference potential V _{C of the} reference voltage source 16 by the comparator 19, and when it exceeds the reference potential V _C , a signal indicating completion of charging is input from the comparator 19 to the control IC 30. After the charge completion signal is input, the control signal is output from the control IC 30 to the buffer circuit 20, and then the buffer circuit 20.
A voltage V _H sufficient to turn on transistor 11 from 20
Is output.

Here, the charge completion detection potential V _C is lower than the potential V _ON when the transistor 11 is turned on, and the voltage V _H generated after the completion of charge detection is higher than the above-mentioned potential V _ON. , 13 and voltage dividing resistors 17, 18 are set. Because if the oscillation stop transistor drive transistor 11 turns on below V _C , the control IC
This is because, even though the charge completion signal is not input to 30, the oscillation operation is stopped and the charge completion signal is not detected thereafter even if the charge is actually completed.

When the potential of the common terminal TB becomes V _H and the transistor 11 is turned on and the collector-emitter of the transistor 11 becomes conductive, the oscillation stopping transistor 4 short-circuits between the emitter and the base of the oscillation transistor 2 so that the blocking occurs. Oscillation stops.

After that, when a signal synchronized with the opening of the shutter is output from the control IC 30 to the terminal C, a trigger signal is output from the trigger signal generation circuit 31 in synchronization with this, and the electrical energy stored in the main capacitor 15 is xenon. The light is emitted from the discharge tube 14 as light emission energy, and an object (not shown) is illuminated.

Although the NPN type transistor element 11 is used as a transistor for driving the oscillation stopping transistor 4 in the first illustrated embodiment, various configurations are possible by combining with the oscillation stopping transistor element 4. Is clear.

[Effect of device]

As described above, according to the present invention, the charging completion detection terminal and the DC / D
Since the number of pins is reduced by sharing the C converter oscillation stop pin, it is possible to reduce the cost by reducing the number of IC pins and work man-hours, and it is expected that the operation stability will be improved by reducing the number of IC pins. It can be done.

As described above, when the charge signal transmission terminal and the DC / DC converter operation stop signal transmission terminal are shared, charging is performed when the signal level of the charge completion signal is the same as that of the DC / DC converter operation stop signal. Since the oscillation operation of the DC / DC converter is stopped at the same time as the completion, the charging completion signal is not input to the control IC 30 although the main capacitor is actually charged.

Therefore, the next sequence processing using the charge completion signal in the control IC 30 cannot be performed, and the sequence of the camera cannot be advanced.However, in the present application, the above-mentioned signal levels are different and the DC / DC converter causes Since it does not stop at the same time as the occurrence, it is possible to reliably advance the sequence of the camera using the charge completion signal.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of a flash photography device for photography to which the present invention is applied, and FIG. 2 is a circuit diagram of a conventional flash photography device. In the figure, 11 ... Transistors, 12, 13 ... Dividing resistors 16 ... Reference voltage source, 19 ... Comparator 20 ... Buffer circuit, 30 ... Control IC (integrated circuit).

Claims (1)

[Scope of utility model registration request] 1. A DC / DC converter, a main capacitor charged by the output of the converter, a discharge tube that emits light when electric charge accumulated in the main capacitor is discharged, and a charge state of the main capacitor is detected. Then, a detection unit that outputs a signal according to the state of charge of the main capacitor, a signal line connected to the output of the detection unit, and a signal line connected to the signal line, and the signal on the line is different from the predetermined level range When a predetermined level is shown, the first switching state shifts to the second switching state and the DC
A flashing device circuit section having a switching means for shifting the / DC converter to an inoperative state, a terminal connected to at least the signal line, and a signal input through the terminal within the predetermined level range. A determination circuit for determining whether or not the level has been reached, and a control circuit for forming a signal of the predetermined level in response to an output from the determination circuit, outputting the signal to the terminal, and controlling an imaging sequence. A camera circuit section is provided, the charge state of the main capacitor is transmitted to the camera circuit section through the terminal, and a signal for deactivating the DC / DC converter is transmitted to the flash device circuit section through the terminal. A flash photography device characterized by the above.