JPS6247629A - Strobe light emission controller - Google Patents

Abstract

PURPOSE:To display the function of a focal plane shutter sufficiently by performing control so that a strobe emits light only when the run end point of the leading curtain of the shutter leads the run start point of the trailing curtain. CONSTITUTION:A focal plane shutter device 12 starts running the leading curtain with a shutter curtain operation command (a) from a shutter control circuit 11 and sends out a leading curtain run end signal (b) when the run is finished. Further, a light quantity integrating circuit 14 starts integration simultaneously with the command (a) and when its output coincides with the reference voltage of a comparator 15, the circuit 11 lowers the signal to a low level with the pulse of a differentiating circuit 17 to start running the trailing curtain. If a signal (b) is sent out before the pulse, the signals (a) and (b) after being passed through a differentiating circuit 21 and an RS FF 18 are inputted to an AND gate 22 and the strobe 24 emits light. When the pulse is sent out early, the FF 18 is reset through an inverter 19 and the strobe does not emit light. Thus, strobe photography is enabled up to a limit shutter speed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a strobe light emission control device, specifically, a strobe light emission control device for controlling light emission of a strobe that can cooperate with a camera having a curtain-running focal plane shutter. Regarding equipment.

[Prior Art] When performing strobe photography using a camera with a curtain-running focal plane shutter, as shown in FIG. If you fire the strobe at a high-speed shutter speed when the rear curtain 3 starts running, so-called slit exposure, the flashing time of the strobe is very short, and the shadow of the shutter curtain will appear on the photographic screen 1. This results in uneven exposure. In order to prevent this, after the leading curtain 2 reaches the tip of the photographic screen 1 and completes its travel, the trailing curtain 3 starts running, and at a low speed shutter speed that completely exposes the entire area of the photographic screen 1. Only strobe light must be allowed.

Conventionally, in conventional cameras, the shutter speed is determined by calculating the photometric information of outside light before the actual shooting, and when using a strobe,
The strobe is set to emit light at a brightness that provides a shutter speed that completely exposes the photographic screen, and is prevented from emitting light at a brightness that provides a shutter speed that is faster than that.

[Problems to be solved by the invention] By the way, the shutter speed that can be synchronized with the strobe allows you to take pictures without camera shake even when the surroundings are dark, or allows you to take pictures more freely during daytime synchronization. In order to improve speed, it is desirable to be able to set the shutter speed as fast as possible.

However, in the method described above in which it is determined whether or not to fire the strobe based on the aIIj light information before taking a picture, there is a time lag between the time of metering and the time of exposure, and the metering information is generally It is difficult to completely match the shutter speed calculated from the above with the shutter speed during actual exposure. For this reason, in reality, the capacity of the mechanical system that drives the shutter curtain is, for example, 1/125 s, taking into account that there is an error in the timing of the shutter curtains between the two.
Even if the strobe can be synchronized up to 1/60 s when using an ec shutter, for safety reasons,
The shutter operation is performed at the shutter speed of the EC, which has the drawback that the capabilities of the shutter mechanical system cannot be fully utilized.

The present invention has been made in view of these problems, and an object of the present invention is to provide a strobe light emission control device that makes full use of the shutter time that the shutter has as a mechanical system and can synchronize with the strobe. shall be.

[Means and operations for solving the problem] This strobe light emission control device is designed to emit a first signal when the leading curtain of a curtain running type focuser/I/brane shutter completes running, and also to issue a first signal when the running of the trailing curtain is completed. A second signal is generated at the start, and when the first signal temporally precedes the second signal, the control circuit generates a signal that allows the strobe to emit light.

[Example] Hereinafter, the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a block diagram of an electric circuit of a strobe light emission control device showing one embodiment of the present invention. In this strobe light emission control device, first, the general shutter control operation is performed using the third
To explain with reference to the time chart in the figure, a shutter curtain operation command a is issued from a shutter control circuit 11 within the camera. This shutter curtain operation command a is issued by pressing the release button to start exposure.
To rise to the H” level and complete the exposure, the light receiving element 1
3. Light amount integration circuit 14. This is a signal that falls to the "L" level due to the output of the photometric circuit comprising the comparator 15, the differentiating circuit 17, etc. when an appropriate amount of light is obtained. The focal plane shutter device 12 is controlled by this shutter curtain operation command a,
When the rising edge of the shutter curtain operation command a is guided to the shutter device 12, the front curtain starts running. When the front curtain completes running, the shutter device 12 issues a front curtain run completion signal to the shutter control circuit 11.

Further, based on the photometric output from the differentiating circuit 17, it is determined whether the falling edge of the shutter curtain operation command a is detected by the shutter device 1.
2, the trailing curtain starts running, and when the trailing curtain completes running, a trailing curtain running completion signal C is issued. Although some time lag t occurs between the rise and fall of the shirt flap operation command a and the time when the shirt flap starts running, this time lag t is negligible.

By the way, only when the shutter curtain operation command a falls after the leading curtain run completion signal S is issued, that is, at the shutter shutter second when the photographing screen 1 shown in FIG. 2 is fully opened, the camera is activated. The attached strobe 24 is configured to emit light, and the strobe 24 does not emit light at a high speed shutter time that precedes the fall of the shutter curtain operation command a or the time of the leading curtain travel completion signal. ing. Next, the strobe light emission control device shown in FIG. 1 will be further explained in detail with reference to the time chart shown in FIG. 4.5.

A set/reset function is used to generate the strobe light emission start signal A from the shutter curtain operation command a issued from the shutter control circuit 11 and the front curtain run completion signal issued from the focal plane shutter device 12 in response to the command a. R-8 type flip-flop (hereinafter referred to as R8
-FF)18 is used, and this R3-
Reset terminal R of FF18 and the above-mentioned shirt shutter curtain operation command a
An inverter 19, a differentiation circuit 20 consisting of a capacitor 20a, a resistor 20b, and a diode 20c are connected between the signal line of the capacitor 21 and the set terminal S.
Differential circuit 2 consisting of a, resistor 21b, and diode 21C
1 to the signal line for the shutter curtain operation command a.

An output terminal Q of R8-FF IFl is connected to a terminal Ta for sending a light emission start signal A to the strobe 24 via an AND gate 22. A terminal Tb for sending a light emission stop signal B to the strobe 24 is connected to the output terminal of the differential circuit 17 of the allJ optical circuit.

First, let's talk about the operation when the strobe 24 emits light.
To explain with reference to the drawings, when the release button is pressed to start exposure, a trigger pulse is emitted, and after a certain time lag, the shutter control circuit 11 issues an "H" level shutter curtain operation command a. When the shutter curtain operation command a is guided to the focal plane shutter device 12, the front curtain starts running after a slight time lag t from its rising edge (see FIG. 3). Further, at the time when the shutter curtain operation command a is generated, the shutter control circuit 11 sends an integration start signal to the light amount integrating circuit 14 of the photometry circuit to cancel the reset, and the light amount integrating circuit 14 starts integrating the light amount. . Before the integration start signal is input, the light amount integration circuit 14
is in a state where the integral has been reset.

In this case, since the object light is dark, the integrated voltage that is the output of the light amount integrating circuit 14 increases with a gentle slope.

In addition, since the shirt shutter curtain operation command a is guided to the set terminal S of R3-FF1g via the differentiating circuit 21, R
The output of 5-FF 18 becomes H” level. At this time,
When the front curtain run completion signal S is generated from the focal plane shutter device 12 and guided to the AND gate 22, it is sent to the terminal Ta as a strobe light emission start signal A. Then, the strobe 24 attached to this camera starts emitting light in response to the strobe light emission start signal A.

After the strobe 24 emits light, the output of the light amount integrating circuit 14 rises with a steep slope, and when proper exposure is obtained, the output matches the predetermined reference voltage VR set by the variable resistor 16 of the comparator 15, <The output of the regulator 15 becomes "H" level. Then, at the rising edge of the output of the comparator 15, a differential pulse is emitted from the differentiating circuit 17, and this differential pulse is guided to the shutter control circuit 11 and sets the shutter curtain operation command a to the "L" level. Therefore, as mentioned above, the rear curtain starts running, and R3-FF18
An inverter 19 and a differentiating circuit 20 are connected to the reset terminal R of
A pulse generated by the input terminal Q is input, and the output terminal Q becomes "L" level. Further, since the output differential pulse of the differentiation circuit 17 is sent to the terminal Tb as a strobe light emission stop signal B, the strobe 24 stops emitting light by this strobe light emission stop signal B. In this way, if the leading curtain running completion signal S occurs earlier than the falling time of the shutter curtain operation command a, the leading curtain running completion signal S is generated earlier than R5-FF18 is reset, and the shutter curtain operation command a falls. Since the light passes through the gate 22, the strobe light emission start signal A is generated at the time when the above-mentioned signal A is generated.

Next, the case where the strobe does not emit light because the shutter speed is fast will be explained with reference to FIG. 5. As in the case described above, when the shutter curtain operation command a is issued after the exposure start trigger pulse is generated, This shirt curtain operation command a
The front curtain starts running at the rising edge of , and the light amount integrating circuit 14 is reset and starts integrating the photocurrent of the light receiving element 13 . By the way, in this case, since the subject light is bright, the integrated voltage rises at a steep slope, and the integrated voltage rises before the leading curtain completes its travel, that is, before the leading curtain travel completion signal is issued. Since the reference voltage VR of the comparator 15 is reached and a differential pulse is emitted from the differential circuit 17 of the optical circuit A11j, at this point the shutter curtain operation command a
becomes “L” level, and the rear curtain starts running. Then, after the trailing curtain starts running, the leading curtain completes running, a leading curtain running completion signal is issued, and the exposure ends. Therefore, when the falling point of the shutter curtain operation command a precedes the timing of the leading curtain running completion signal, R5-FF18 is already connected to the reset terminal R when the above signal is led to the AND gate 22. Since the reset pulse is input, the output terminal Q
is at “L” level, and strobe light emission start signal A
cannot be emitted. Therefore, the strobe 24 does not emit light. Therefore, even if a differential pulse is emitted from the differential circuit 17 during the proper exposure and guided to the terminal Tb, it is natural that this pulse will not be used as the strobe light emission stop signal B.

Note that R3- of the strobe light emission control device shown in FIG.
FF 1g, inverter 19. The circuit consisting of the differentiating circuits 20, 21 and the AND gate 22 may be replaced with an AND gate 23, as shown in FIG. That is, in the embodiment shown in FIG. 6, one input terminal of the AND gate 23 receives the shirt shutter curtain operation command a.
The other input terminal of the AND gate 23 is connected to the signal line for the front curtain run completion signal, and the output terminal of the AND gate 23 is a terminal Ta for sending out the strobe light emission start signal A. It is connected to the.

The other circuit configurations can be the same as those shown in FIG. 1, so illustrations are omitted. In the embodiment of the configuration using this AND gate 23,
When the leading curtain running completion signal S is issued within the section where the shutter curtain operation command a is at the "H" level, the strobe light emission start signal A is issued from the AND gate 23 in synchronization with this leading curtain running completion signal. (See Figure 4). In other words,
When the leading curtain travel completion signal S is generated before the trailing curtain operation command a falls, which is the time the trailing curtain starts traveling, the strobe is activated at the initial point when the leading curtain has completed traveling and the shooting screen is fully opened. It starts to emit light. Therefore, in any other state, that is, if the shutter curtain operation command a falls to the "L" level and the trailing curtain starts running before the leading curtain running completion signal is issued, the trailing curtain starts running. ), the output of the AND gate 23 remains at the "L" level, and the strobe light emission start signal A is not generated.

[Effects of the Invention] As described above, according to the present invention, when the signal emitted when the front curtain of the focal plane shutter completes running is temporally earlier than the signal emitted when the rear curtain starts running, the strobe light is emitted. As a result, the permissible range of strobe use (strobe synchronization range) can be extended to the shutter speed, which is the limit of the ability of the mechanical system that drives the shutter curtain, and the shutter speed is faster than before. Flash photography is now possible up to the second hour.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an electric circuit of a strobe light emission control device showing an embodiment of the present invention. FIG. 2 is a front view of the vicinity of the photographing screen for explaining the running operation of a curtain-running focal plane shutter. 3 is a time chart for explaining the basic operation of shutter control in the strobe light emission control device shown in FIG. 1 above, and FIG. 4 is a time chart for explaining the basic operation of shutter control in the strobe light emission control device shown in FIG.
FIG. 5 is a time chart of signals of various parts during operation when the strobe emits light, and is a time chart of the strobe light emission control device shown in FIG. 1 above.
Time chart of signals of various parts during operation when the strobe does not emit light. FIG. 6 is a block diagram of main parts of an electric circuit of a strobe control device showing another embodiment of the present invention. 2・・・・・・・・・・・・First act 3・・・・・・
. . . Rear curtain 11 . . . Shutter control circuit (means for emitting the first signal) 12 . . . Focal plane shutter device (means for emitting the second signal) 23...And gate (control circuit) 24
・・・・・・・・・Strobe % 2nd ward % 3rd ward 4th ward Tori gamma fear ■−−−−−−−−−−−−− Kazuma 5th ward

Claims (1)

[Scope of Claims] Means for generating a first signal at the time when the leading curtain of the curtain-running focal plane shutter completes running, and means for generating a second signal at the time when the trailing curtain starts running; and a control circuit that receives the signal and the second signal and generates a signal that allows the strobe to emit light only when the first signal temporally precedes the second signal. A strobe light emission control device characterized by: