JPH052130B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a camera with an electronic flash device that combines a flash device using a strobe discharge tube or the like and a camera that generates signals for starting and stopping the flash.

(Prior Art) The present inventor has filed applications such as Japanese Patent Application No. 53-011138 regarding the electronic flash device of the above type.

When the main capacitor of the flash device is charged with enough electrical energy to cause the discharge tube to emit light, a flash-enabled signal is transmitted to the camera side, and when the photographer learns of this from the display in the viewfinder, he or she presses the shutter button. When the contact is closed, a light emission signal is transmitted to the flasher side, causing the discharge tube to emit light. This flashlight is received within the camera, and when a certain amount of light is reached, a dimming signal is transmitted from the camera side to the flasher side. This invention was applied to an electronic flash device that stops emitting light, and it simplifies the connection structure between the flash device and camera.

That is, the above connection structure reduces the number of signal lines by allowing a single connection line to transfer the charge completion signal and the dimming signal by switching semiconductor switches.

(Problem to be Solved by the Invention) The camera side of the above-mentioned flash device should be able to display the completion of charging of the main capacitor in the camera's viewfinder, or switch to automatically synchronize the shutter speed of the camera. It can be configured as a circuit.

However, there is a problem in displaying in the viewfinder of the camera whether or not the strobe discharge tube has adjusted its light, that is, has achieved proper exposure.

First of all, in order to perform dimming display, the following things are necessary.

Remember that the charging completion signal was issued. From the time the X contact was turned on, the strobe discharge tube would have emitted light for a certain period of time of about 1 to 3 ms.
The flash light receiving circuit is activated only during this time, and a dimming signal is sent out. Multiplying this value indicates that the strobe discharge tube has dimmed, and this can be displayed in the camera's viewfinder. In order to enable dimming display in this way, the camera's IC circuit must be
Must detect contact ON. However, in addition to the dedicated strobe, various types of strobes are connected to the camera's X contact, and high voltages ranging from several tens of volts to 2 to 300 volts are applied. For this reason, receiving the closing signal from the camera's X contact into the IC circuit requires a special protection circuit to avoid damage to the IC circuit.
Undesirable.

An object of the present invention is to connect an electronic flash device with a simple connection structure, and to receive a signal from a change in a thyristor operated by an X contact of the camera to start a flash discharge tube of an electronic light control device into the camera side. It is an object of the present invention to provide a camera with an electronic flash device that operates a display and a photometry circuit on the camera side related to light control.

(Means for Solving the Problem) In order to achieve the above object, a camera with an electronic flash device according to the present invention includes a switching element _T4 that detects that the main discharge capacitor _C0 is charged and becomes conductive; A Zener diode ZD ₁ generates a constant voltage across both ends when the switch element T ₄ conducts, and in order to transmit the constant voltage generated in the Zener diode ZD ₁ , one end of the Zener diode ZD ₁ is connected to one end of the Zener diode ZD 1. A parallel circuit of a diode D ₁ and a capacitor C ₁ connected to each other, a common terminal B for receiving a dimming signal and sending a charging completion signal, to which the other end of the parallel circuit is connected, and
a contact terminal X; a thyristor _Th3 connected to the X contact terminal
The base of the flash tube Xe, which is flashed by conduction of the thyristor, is connected to the connection point between one end of the Zener diode ZD ₁ and one end of the parallel circuit, and the collector terminal or emitter terminal is connected to the common terminal B. a transistor T ₂ which is connected to one of them and becomes conductive when a dimming signal from the camera is input to the common terminal B;
A capacitor C ₂ is connected to the connection point of one end of the parallel circuit of switches T ₁ , T ₂ , Th ₂ that stop the flash light emitting tube Xe when T ₂ is conductive, and one end of the Zener diode ZD ₁ . A camera that operates coupled to an electronic flash device having a connecting terminal G connected thereto, an X contact switch connected to the X contact terminal X, and a voltage appearing at the common terminal B when the charging is completed. The charge display section is driven by the circuit IC ₃ which generates an output, and the thyristor is activated by the operation of the X contact switch.
A dimming signal generation circuit IC ₁ , T that starts integrating the photocurrent by a signal appearing at the connection terminal G when Th ₃ is made conductive and sends a dimming signal to the common terminal B when a certain voltage is reached. ₆ , PD, _C7 , _IC7
It consists of

According to the above configuration, the charging completion signal can be reliably transmitted from the flash unit to the camera side until the flash signal is generated, and after the flash signal is generated, the dimming signal can be transmitted from the camera side to the flash unit without error. .

Furthermore, it is possible to obtain a signal comparable to the power supply voltage of the camera-side IC circuit for starting dimming, and the object of the present invention is completely achieved.

(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings and the like.

FIG. 1 is a circuit diagram showing an embodiment of an electronic flash device according to the present invention. This circuit diagram shows the parts related to the present invention in the electric circuits of the flash device and camera.

First, I will explain the movement of the arm on the flash side.

When the power switch SW ₀ is turned on, the high voltage generation circuit is activated and the main capacitor C ₀ is charged with electrical energy.

When the charging voltage reaches a certain constant voltage, that is, a voltage sufficient to bring the amount of light emitted from the strobe discharge tube Xe to a specified value, the neon tube Ne notifies the completion of charging and at the same time turns on the transistor _T4 .

A charging completion signal is generated from the emitter of the transistor _T4 on the line A in the figure, and this signal is passed through the resistor _R1 and then to the diode which is the first semiconductor switch.
It appears at the common terminal B through _D1 as an H level charge completion signal.

A second semiconductor switch is connected to the common terminal B.
The emitter of PNP transistor T ₂ is connected. Furthermore, the base of the transistor T ₁ that receives the dimming signal is connected to the collector of this transistor T 2, and the base of the transistor T ₁ that receives the dimming signal is connected to the collector of this transistor T ₂ .
The collector is connected to a circuit that stops light emission, which will be described later.

The circuit that stops the light emission is activated when transistor T ₂ becomes conductive.

By the way, since the base of the transistor _T2 is connected to the intersection of the resistor _R1 and the diode _D1 via the resistor _R2 , the charging completion signal of the transistor _T2 appears on the common line at the same time. A charging completion signal also appears at the base, making transistor _T2 non-conductive.

Therefore, the charging completion signal on the common line appears only at the common terminal B without being input to the transistors T ₂ and T ₁ .

Next, after the flash light emission signal is input to the flash device, the discharge tube emits light and the first and second semiconductor transistors are switched on and off, and at the same time, the following steps are performed until a signal for dimming display is generated. That's right.

When the X-contact X-SW turns on, a light emission signal is input to the flash diode _D3 . Diode _D3 ,
Resistor 3, 4, capacitor C ₅ and thyristor Th ₃
A drive circuit for emitting light from the discharge tube is formed by the above. This drive circuit has a resistor at the terminals of capacitor _C5 .
An H level charge completion signal is input through _R3 , and when the above light emission signal is transmitted to the intersection of capacitor _C5 and resistor _R3 through diode _D3 , the cathode of thyristor _Th3 is switched to the negative side. Thyristor Th ₃ becomes conductive and generates an output. Therefore, no output is generated when the H level charge completion signal is not input via the resistor _R3 .

When thyristor Th ₃ conducts, a high voltage trigger pulse is generated in the trigger coil and the thyristor
_Th1 is also made conductive and the discharge tube Xe starts discharging.

At the same time, a negative voltage is generated at the intersection of C ₄ and R ₅ by the differentiating circuit consisting of capacitor C ₄ and resistor R ₅ , and is passed through resistor R ₆ to diode D ₂ , capacitor C ₂ , resistors R ₁ and R ₆ . Pull the intersection F to L level.

The voltage at point F is suppressed to about -0.8V by diode _D2 . At this time, the charge completion signal generated at the common terminal B becomes L level and disappears, and the base of transistor _T2 also becomes L level and the transistor
_T2 is switched to accept signals. During this switching operation, the diode _D1 is connected to prevent a malfunction in which a charging completion signal is input to the transistor _T1 .
A capacitor _C1 is connected in parallel with .

This will be explained using the waveform diagram in FIG.

() shows when capacitor C ₁ is not connected, () shows when capacitor C ₁ is connected _. ,
and each output waveform of strobe light emission.

If capacitor _C1 is not connected, (1) the voltage at the common terminal will slowly drop as shown by the waveform at point B. Therefore, the base of the transistor _T1 remains at the H level until the voltage at point B falls below a certain level, and the discharge tube that has started emitting light immediately stops.

However, if capacitor C ₁ is connected,
(2) As shown by the waveform at point B, a negative differential pulse is generated at the same time as a negative voltage is input to point F, and even though transistor _T2 becomes conductive, the transistor
The base of T ₁ does not become H level. Therefore, if a capacitor is connected in parallel to the diode _D1 , the switching of the transistor _T2 will be performed normally.

On the other hand, the negative voltage at point F is applied to capacitor _C2 and transmitted through terminal G to the camera side.

This signal is an X contact ON signal used as a signal to start dimming.

Next, the operation of the circuit that stops the discharge tube when a dimming signal is input from the camera side will be explained.

When the dimming signal is input to the transistor T ₁ through the transistor T ₂ , the transistor T ₃ is turned on and makes the thyristor Th ₂ conductive. thyristor
When Th ₂ becomes conductive, a negative pulse is generated by the capacitor C ₃ at the anode of the cyristor Th ₁ , which turns off the thyristor Th ₁ and stops emitting light.

Next, the circuit on the camera side will be explained. This circuit section shows only the part that receives the charge completion signal and the part that emits the dimming signal.

First, when a charging completion signal is sent from the flash unit through the common terminal B, this signal is input to one input terminal of the AND circuit IC ₃ on the camera side.

This AND circuit outputs an H level when the other input terminal is in negative logic. Therefore, when the charging completion signal is input, the output terminal Q of the flip-flop connected to the other input terminal is in flip-flop logic, so the output of the AND circuit IC ₃ becomes H level, and a charging completion signal is input into the finder. The information is transmitted to the display circuit.

At the same time, the output of IC ₃ is input to the S terminal of flip-flop IC ₄ , and the completion of charging is memorized. The output of IC ₄ is used as one of the signals for the dimming display, which will be described later, and is also used as a signal to automatically change the shutter speed to synchronize with the flash, and also to change the shutter speed display, etc. Ru. Circuits related to these shutter speeds are omitted.

Next, when the shutter is turned off and the X-contact X-SW is turned on, the flash light emission signal is transmitted to the flash device side, the circuit on the flash device side operates as described above, and the terminal G receives the X contact ON signal, that is, the start of dimming. An L level signal appears at the common terminal B and is transmitted to the camera.

First, the L level signal that appears at common terminal B is
This signal is sent to a circuit that turns the output of IC ₃ to L level and indicates that charging is complete.

Next, a signal for starting dimming is converted into a negative slope pulse by a differentiating circuit including a capacitor _C2 and a resistor _r1 , inverted by an inverter, and inputted to the S terminal of the flip-flop _IC1 .

The Q terminal of IC ₁ is connected to the other input terminal of IC ₃ , the gate of transistor T ₅ , and the base of transistor T ₆ via an inverter. Also connected is the input terminal of IC ₃ , which is composed of three D-FFs.

IC ₃ becomes t=2 when the Q terminal of IC ₁ becomes HR level.
~3ms later, output is generated from that output terminal.
This is a circuit that resets _IC1 .

Therefore, the Q terminal (I point) of IC ₃ has about 2 to 3
A ms wide pulse is generated, turning on transistor _T5 and turning off transistor _T6 for that period.

PD is a photodetector that receives strobe light, and the photocurrent charges capacitor _C7 .

IC ₇ , whose normal input terminal is connected to the intersection of PD and C ₇ , is a comparator, and when the voltage at the normal input terminal is higher than the reference voltage Vref input to the inverting input terminal, its output terminal becomes H level. do. The transistor _T6 described above is connected in parallel to the capacitor _C7 , and before the signal to start dimming is input, _T6 is on and is not charged, but _T6 When the PD turns off, the PD receives strobe light and begins charging.

When a certain amount of light is reached, IC ₇ generates a dimming signal. This dimming signal is transmitted from the common terminal B to the flash device through the transistor _T5 , which had been previously turned on, and stops emitting light.

On the other hand, this dimming signal is also input to the input terminal of IC ₅ , and the other input terminal of IC ₅ already contains the H signal stored at the completion of charging of IC ₄ , so the output of IC ₅ becomes H level and the flip-flop is turned on. Operate it and display the dimming display.

In this example, the power switch is set on the flash unit side.
When you turn on SW ₀ and press the shutter on the camera side, the flash unit and camera operate respectively, and the flash photography ends by exchanging signals.

(Effects of the Invention) As is clear from the above description, in the camera with an electronic flash device according to the present invention, the charging completion signal and the dimming signal are exchanged on the common line using the first semiconductor switch and the second semiconductor switch, respectively. The first semiconductor switch is conductive until the X contact is turned on, and when the X contact is turned on, this ON signal is used to cause the second semiconductor switch to conduct, so the charging completion signal can be sent without malfunction. and can exchange dimming signals.

In addition, the structure is such that a signal comparable to the power supply voltage of the camera IC circuit to start dimming can be transmitted from the flash unit to the camera at the same timing as the semiconductor switch is switched, so the camera IC circuit can be destroyed. It becomes possible to perform dimming display without fear of

Note that one signal line is added to transmit the dimming signal to the camera side, but this is applied to a flash device that transfers the charging completion signal and the dimming signal over a single common line. Therefore, two signal lines can exchange three signals: a charging signal, a signal for dimming signal, and a dimming signal, and a flash type that uses separate signal lines to exchange the charging completion signal and dimming signal This has the advantage that the number of signal lines is the same as that of the device, and the connection structure between the camera and the flash device is not complicated.

Furthermore, since it is possible to extract semiconductor switch switching signals and dimming signals from the drive circuit that generates output when the thyristor conducts, it is possible to control the thyristor so that it does not conduct unless a charge completion signal is generated. , the following operations, namely strobe light emission, semiconductor switch switching, and generation of signals for starting dimming, can be suppressed.

Furthermore, it is of course possible to display the completion of charging or change of shutter in the viewfinder.

As described above, according to the present invention, a camera with an electronic flash device that has a simple connection structure between the flash device and the camera and is highly reliable can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of a camera with an electronic flash device according to the present invention. FIG. 2 is a waveform diagram for explaining the operating circuit of the circuit shown in _FIG . The waveform is shown when not. T ₁ , T ₃ , T ₄ , T ₅ , T ₆ ...transistor,
Th ₁ , Th ₂ , Th ₃ ... Thyristor, Xe ... Discharge tube, SW ₀ ... Switch, X-SW ... X contact switch, X, G, B ... Connection point between camera and flashlight, C ₀ , C ₁ , C ₂ , C ₃ , C ₄ , C ₅ , C ₆ , C ₇ ... Capacitor, D ₁ ... Diode (first semiconductor switch), T ₂ ... Transistor (second semiconductor switch), ZD ₁ ... Zena diode, D ₂ , D ₃ ... Diode, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ ... Resistor,
IC ₁ , IC ₄ , IC ₆ ... flip-flop, PD ... light receiving element.

Claims (1)

[Claims] 1 A switching element _T4 that conducts when it detects that the main discharge capacitor _C0 is charged, and a Zener diode that generates a constant voltage across it when the switching element _T4 conducts.
ZD ₁ and a diode whose one end is connected to one end of the Zener diode ZD ₁ in order to transmit the constant voltage generated in the Zener diode ZD ₁ .
A parallel circuit of D ₁ and capacitor C ₁ , a common terminal B for receiving a dimming signal and sending a charge completion signal, to which the other end of the parallel circuit is connected, and an X contact terminal
, a thyristor _Th3 connected to the X contact terminal X and made conductive by a flash light emission signal from the camera inputted to the X contact terminal X, and a flash light emitting tube Xe caused to flash by the conduction of the thyristor.
and its base is connected to a connection point between one end of the Zener diode ZD ₁ and one end of the parallel circuit, and either a collector terminal or an emitter terminal is connected to the common terminal B, and the common terminal B
a transistor T ₂ that becomes conductive when a dimming signal from a camera is input to the transistor T 2 , switches T ₁ , T ₃ , and Th ₂ that stop light emission of the flash tube Xe when the transistor T ₂ becomes conductive; and the Zener diode A camera that operates by being coupled to an electronic flash device having a connection terminal G connected to one end of the parallel circuit at one end of ZD ₁ via a capacitor C ₂ , wherein the X contact terminal A circuit that generates an output based on the connected X contact switch and the voltage appearing at the common terminal B when the charging is completed.
When the charge display section driven by IC ₃ and the thyristor Th ₃ are made conductive by the operation of the X contact switch, integration of the photocurrent is started by the signal appearing at the connection terminal G, and a constant voltage is reached. A camera with an electronic flash device comprising a dimming signal generation circuit IC ₁ , T ₆ , PD, C ₇ , and IC ₇ that sends a dimming signal to the common terminal B.