JPS6241304Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a flash information generation device for a camera. Specifically, when a camera and a speedlight are connected to take flash photography, the camera side generates information indicating that the speedlight has been triggered. related to a device for

Recently, especially when using flash photography using auto-flash speedlights, for example, to display the success or failure of auto-flash control, or to transmit the output signal of the camera's photometry circuit in cameras with TTL flash control, it is necessary to connect the camera and speedlight. A large number of information transmission circuits are required between the two. The connection points for this information transmission circuit are provided within the accessory shoe provided in the camera or speedlight, and the number of connection points has inevitably increased.

However, there is a structural limit to the number of connection points that can be installed within this accessory shoe, and therefore there is a limit to the amount of information that can be transmitted between the camera and the speedlight unless a separate transmission circuit is provided. Therefore, Utility Model Application Publication No. 49-148053, by closing the X contact, causes the charging energy of the trigger capacitor to flow directly into the coil provided on the camera side via the X contact, and the positive pulse generated in the coil is Discloses a technology used for automatic switching of flash seconds. Although this has the advantage that the camera can detect that the speedlight has been triggered, it has the following drawbacks. That is, since the coil is DC-coupled to the trigger circuit, the impedance of the trigger circuit increases, causing energy loss, and the high voltage required to excite the flash discharge tube is not generated on the secondary side of the trigger coil. be. As a result, a failure in photographing may occur due to failure of the flash to emit light.

The purpose of the present invention is to substantially increase the amount of information that can be transmitted between the camera and the speedlight while eliminating the above-mentioned drawbacks. It is an object of the present invention to provide a flash information generating device for a camera, which controls the operation of a light amount integrating circuit and a dimming success/failure display circuit of a speedlight based on information.

This invention focuses on the fact that when a camera and speedlight are connected to take flash photography, a resonant current from the speedlight side flows through the camera's synchro circuit when the speedlight flashes, and this resonant current is extracted using an electromagnetic induction circuit. This is used as flash information.

The present invention will be explained below based on the drawings. The figure shows an example of a circuit in which the present invention is applied to a TTL automatic dimming speedlight.

In the figure, in the flashlight emitting unit 1, the power source 2
By main capacitor C ₁ and trigger capacitor
C ₂ is being charged. The primary winding of a trigger coil 4 for exciting the flash discharge tube 3 is connected via a synchro terminal 5 to an X contact 6 of the camera.

A pickup coil 7 for generating flash information is wound around a synchro circuit line 6a of the camera including this X contact 6 (coupled with electromagnetic induction).

Now, when the X contact 6 is closed, the charge stored in the trigger capacitor _C2 is discharged through the primary winding of the trigger coil 4. Therefore, flash discharge tube 3
is excited by the high voltage pulse generated in the secondary winding of the trigger coil 4, and at the same time the first SCR 8 becomes conductive, so the flash discharge tube 3 starts emitting flash light.

At this time, the synchro circuit line 6a on the camera side
A resonant current flows through the synchro terminal 5 due to the inductance of the trigger coil 4 and the capacitance of the trigger capacitor _C2 . The pickup coil 7 is excited by this current and instantaneously generates a voltage Vp between its terminals. This terminal voltage is used as flash information.

This voltage Vp causes the transistor Q ₁ to become conductive momentarily. Then, the output terminal Q of the R, S flip-flop circuit consisting of resistors R ₁ and R ₂ and NAND gate circuits G ₁ and G ₂ becomes L level, and the transistor
Q ₂ becomes a cutoff.

This flip-flop circuit acts as a memory circuit.

The flash generated by the flash discharge tube 3 illuminates the subject, and the reflected light passes through a photographing lens of a camera (not shown) and enters a phototransistor Qp of a light receiving section 9 built into the camera. photo transistor
The amount of light received by Qp is stored as an electrical amount in the integrating capacitor _C3 , and when it reaches a predetermined value, the comparator circuit 1
0 makes the second SCR 11 conductive. This second
Due to the conduction of the SCR 11, the third
The SCR 12 becomes conductive and reverse biases the first SCR 8 to cut it off.

Autoflash photography is performed in this way, and when the rear shutter curtain of the camera (not shown) closes, the switch is turned off.
SW is closed and transistor _Q3 conducts,
The output terminal Q of the RS flip-flop circuit becomes H level. Therefore, transistor _Q2 conducts to reset integrating capacitor _C3 in preparation for the next flash photography.

The present invention has been applied to the resetting of the integrating capacitor of a TTL automatic dimming speedlight, but there are various other possible applications such as resetting the display of the success or failure of dimming on the camera side.

As described above, in the case of flash photography by connecting a camera and a speedlight, when the camera's Since the flash information is retrieved by the camera and the speedlight, it is possible to prevent the flash from firing incorrectly, and there is no need to install a special information circuit between the camera and the speedlight. The amount of information that can be transmitted can be increased.

[Brief explanation of the drawing]

The figure is a circuit diagram showing an embodiment of the present invention. Explanation of the symbols of the main parts: flashlight emitting unit...1, flashlight discharge tube...3, trigger coil...4, pick-up coil...7, main capacitor... _C1 , trigger capacitor... _C2 .

Claims (1)

[Scope of utility model registration request] A pickup coil that is electromagnetically coupled to the synchro circuit line on the camera side and excited by a resonant current flowing from the speedlight side to the synchro circuit line via the X contact, and the excitation output of the pickup coil as the set input. A memory circuit that enters the first state and enters the second state by using a reset input signal generated in response to the shooting end operation, and is controlled by a controlled device placed on the camera side according to the output of the memory circuit according to the state. A flash information generating device for a camera, characterized by switching the operation of a part.