JPS6148142B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flash photography synchronization device for a camera.

A conventional flash photography synchronization device for a camera is configured to mechanically detect the completion of one-shot operation of the shutter and close a synchronization contact to obtain a flash light emission signal. This configuration has disadvantages in that the mechanical configuration is complicated because of the mechanical detection of the completion of one-act travel, the device is large, and the manufacturing cost is high.

The present invention aims to solve the above-described drawbacks of the conventional structure by electrically obtaining a flash light emission signal, and to provide a flash photography synchronization device that is structurally simple, compact, and inexpensive.

The present invention electrically starts timing at the same time the shutter starts running for the first act, and issues a second shutter run start signal and a flash light emitting signal after different preset times to start the second act and start flashing. The present invention provides a flash photography synchronization device in which each of the following is independently controlled.

As described above, the flash photography synchronization device of the present invention uses the start of the first shutter act as the starting point for timing, and causes the flash to fire and the second act to start running after an appropriate time. It is possible to appropriately set the temporal relationship with The present invention will be explained below with reference to Examples.

FIG. 1 shows a circuit of one embodiment of the present invention. A high-level signal is applied to terminal a when the single-lens reflex mirror (not shown) is raised by a switch that is closed when the single-lens reflex mirror is raised. This signal makes the left transistors T1 and T2 conductive.
The electric charge of the capacitor C1, which has been charged in advance from the power supply, is discharged through the transistor T2 and the coil of the magnet Mg1. The magnet Mg1 has a permanent magnet core and holds an attracting piece in advance, and is reverse excited by the discharge current of the capacitor to release the attracting piece, thereby starting one shot of the shutter. A signal indicating completion of charging of the main capacitor of the flash light emitting power source is applied as a high level signal from the flash light emitting device to the terminal J1. When not performing flash photography, terminal J1 is set to low level and gated.
AG1 is closed, and a high signal is applied to one input terminal of AND gate AG2 through inverting circuit NO1. In this state, when terminal a also goes high, the shutter starts running and the two input terminals of AND gate AG2 go high, so AG
2 is opened, and the output pulses of the pulse generator PG are sent to the counter CO2 through AG2 and counted. The pulse generator and counter CO2 constitute one timekeeping device. 1
is a photometric circuit that outputs a digital signal according to the subject brightness to preset the counter CO2. When the CO2 count reaches this preset value, a high level signal is output to terminal d, and this signal is sent to the OR circuit. The charged charge of the capacitor C2, which is applied to the base of the transistor T3 through OG1, and which is previously charged when T3 becomes conductive, is applied to the magnet.
It is discharged through a Mg2 coil. magnet
Mg2 has the same structure as Mg1, and capacitor C2
The discharge current causes reverse excitation to start the second shutter curtain, thus achieving an exposure time that corresponds to the brightness of the subject.

Next, when taking flash photography, when the main capacitor of the flash device is fully charged, terminal J1 becomes high level and is applied to one input terminal of AND gate AG1, and one input terminal of AND gate AG2 becomes low, so AG2 Closed. When the single-lens reflex mirror is raised and terminal a becomes high level, the shutter starts to run and the AND gate AG
Since the other input terminal of 1 becomes high, AG1
is opened and the output pulse of the pulse generator PG is
It is applied to counter CO1 through AG1 and counted. In this case, the pulse generator PG and the counter CO1 constitute another timekeeping device. Figure 2 is a travel diagram of the shutter curtain, where the horizontal axis is time and the vertical axis is the amount of travel of the shutter curtain, and the shutter curtain runs from bottom to top. In the figure, t1 indicates the point in time when the terminal a becomes high level, and the curve f is the traveling curve of one shot of the shutter, which starts traveling from the point t1. In the figure, the two horizontal dotted lines represent the film surface, and the shutter is fully opened at time t2. Returning to Fig. 1, the first shutter act starts running, counter CO1 starts counting, and the count ends at a certain point before the first shutter act is fully opened (t3 in Fig. 2).
When the value corresponding to (time of 2) is reached, a high-level signal is first output to terminal c and applied to the base of transistor T3 through OR circuit OG1, causing the shutter second curtain to start running as in the case of normal shooting. . The traveling curve of the second shutter curtain in this case is shown in FIG. 2S. As is clear from FIG. 2, the second act appears on the film surface at time t4, which is later than time t3 when running starts. After that, when the counting progresses further and reaches the value corresponding to the time when the shutter is fully open for the first time (t2 in Figure 2),
A high level signal is output to terminal b, thyristor SC2 is made conductive, magnet Mg3 is excited, and switch Sw is closed. This Sw is a synchro switch that triggers a flashlight emitting device via terminals J2 and J3. At this time t2, as shown in FIG. 2, the second shutter curtain does not appear on the film surface. In this way, t3 is selected to ensure flash synchronization.

As described above, the present invention is provided with a counting means that starts counting at the same time as the first shutter curtain starts running, and when the count advances to the point where flash synchronization is guaranteed even if the second shutter curtain starts running, In addition to starting the movement of the shutter, the flash was configured to emit light when the count progressed to the point where the first curtain was fully opened after the start of the second curtain, so it was possible to mechanically indicate the completion of the first curtain. Compared to a system that detects the flash and starts the second act at the same time as the flash emits light, the time from when the first act is fully opened to when this first act completes its journey and the time it takes for the second act to start running. The synchronization speed for flash photography can be increased by an amount of time approximately equivalent to the sum of the time it takes for these two acts to appear on the film surface. Furthermore, since the present invention does not mechanically detect the completion of one shot of the shutter, it is possible to provide a flash photography synchronization device that is mechanically simple, compact, inexpensive, and highly reliable.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a graph showing the movement of the shutter curtain in this embodiment. a...Trigger signal input means; T1, T2, R
1, C1, Mg1...first magnet circuit, J
1...Light emission preparation signal input means, PG, GA1, CO
1...Counting means, T3, T4, C2, Mg2
...Second magnet circuit, SC2, Mg3,
Sw, J2, J3...Light emission start signal output means.

Claims (1)

[Claims] 1 means for inputting a trigger signal for one-act running of the shutter; a first magnet circuit for starting one-act running of the shutter in response to the trigger signal; and means for inputting a light emission ready signal from the flash device. , a counting means that starts counting when a trigger signal is input while a light emission ready signal is being input, and a second act of the shutter when the count value of this counting means reaches a predetermined value that guarantees flash synchronization. a second magnet circuit for starting, and means for outputting a flash light emission start signal when the count value of the counting means reaches a value corresponding to the time when the first shutter curtain is fully opened after the second shutter curtain starts running. A camera flash photography synchronization device equipped with