JPS605928B2 - Shutter-second control device for flash photography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shutter time control system for a camera that performs flash photography by causing a flash device to synchronously emit light.

When performing flash photography using a flash device, it is necessary to set the shutter time depending on the type of flash device used.

In other words, when using a strobe with a short flash duration,
The synchronization time is different when using a flash bulb with a long flash duration, and if you use a flash bulb to take pictures with the synchronization time for a strobe, the shutter will close even though the flash is firing, resulting in uneven exposure. occurs, making it impossible to perform proper flash photography. For this reason, when taking flash photography, it is necessary to select and set the shutter time in advance according to the flash duration of the flash device being used, and if the shutter time is set incorrectly, the flash photography will fail. This may cause other inconveniences.

The present invention aims to solve the above-mentioned drawbacks of the conventional device by automatically adjusting the shutter time according to the light emission duration of the flash device used and constantly preventing the shutter from closing during flash light emission. .

To achieve the above object, the present invention has a detection circuit (implemented) that detects the light emitting state of a flash device that is activated to emit light by movement to open the shutter during flash photography, and outputs a light emitting signal while the flash device is in the light emitting state. Example, SPC2, R4 in Fig. 1,
Corresponds to A2. ) and a flash second time signal output circuit (C3, R5, SC in FIG.
R,,Q,Q. Corresponds to Q5 and Q6. ) and a switching means (corresponding to Q2 in FIG. 1) that generates a first output in response to the light emission signal and generates a second output when the light emission signal disappears; A timer circuit that starts timing upon receiving the second output of the switching means and the output from the flash second time signal output circuit (embodiment, R
,,corresponds to C2. ) and a shutter time control circuit (corresponding to T in FIG. 1 in the embodiment) which sends out a shutter opening signal in response to the timer output. The shutter time control device of the present invention controls the shutter closing operation during the duration of the flash, and can be applied to either a focal plane shutter or a lens shutter, regardless of the type of camera shutter. According to the present invention, it is possible to save the trouble of manually selecting the shutter time depending on the type of flash device when taking flash photography, and it is also possible to eliminate the need to manually select the shutter speed according to the type of flash device. The effect is great because the shutter closes immediately after the movement is finished. Furthermore, as mentioned above, regardless of the type of flash device, shutter closing operation is prohibited during flash emission, so regardless of the type of flash device used, the flash device can be triggered using the × contact. It also has a certain effect. In other words, even if you trigger an FP class bulb with the × contact, the shutter will not close while the light is being emitted as described above, so the entire light of the bulb will be exposed, and even if you trigger the × contact bulb, you will not be able to take flash photography with the bulb. It is possible to do it properly. The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a circuit connection diagram showing an embodiment of the shutter time control system according to the present invention, in which exposure is performed for the duration of the flash of a flash device in an aperture-priority electric shirt printer. In the figure, SPC is a light-receiving element, and a device with excellent light response characteristics, such as a silicon photocell, is used. A is an operational amplifier, and 1 is a photographic information source, which sets photographic information such as film sensitivity and aperture, and inputs its output to A. D. is a diode which is inserted into the feedback path of A to obtain the abex value of the shutter time by performing abex calculations on the luminance from the SPC and various information from 1, with the characteristic of A being a logarithmic compression characteristic. S2 is a memory switch that is turned off in conjunction with the release operation of the shutter button. C, is a storage capacitor that is charged by the output of the arithmetic circuit when S2 is on. Q, is a transistor of the time constant circuit for controlling the seconds; C2, which acts as an extension, is the same capacitor; and R, is a protective resistor of Q. Note that S3 is a start switch that is turned off in conjunction with the shutter opening operation. Q
Reference numeral 2 denotes a transistor that operates as a switch and functions to open and close both ends of the capacitor C2 during flash photography. T, is a time control circuit, and M, is an electromagnetic magnet that causes the shutter to close. The aperture pocket memory type electric shutter is configured as described above. Next, S4 is a power switch for a circuit for flash photography, which is turned on by attaching a flash device to the camera and activating the device, or by manual operation if it is built-in. R2 and R3 are resistors forming a voltage dividing circuit;
SPC2 is a light receiving element such as a silicon photocell for receiving light emitted from a flash device, A2 is an operational amplifier, and R4 is A
This is the resistance of the second return path. C3 and R5 are capacitors and resistors constituting a differentiating circuit, and SCR is a thyristor whose output controls a transistor switching circuit consisting of Q3, Q4 and Q5. Q6 is a transistor that functions as a switch for a circuit that charges the capacitor C2 of the time constant circuit with the output of the switching circuit. The operation of the illustrated apparatus when performing flash photography using, for example, a strobe will be described.

The switch S4 is in the on state when the flash device is ready to emit light, and when the shutter button is pressed, S2 and S3 are turned off and the shutter front curtain runs. Almost at the same time, a strobe emits light at the X contact, and the light is received by the SPC2. The output of the SPC2 is passed through an amplifier A2 to a differentiating circuit, and its high frequency component (pulse waveform) is applied to the control electrode of the SCR to trigger it. Due to the conduction of SCR, transistor Q3 of the switching circuit is turned on, Q4 is turned off, and Q is turned on, and a flash signal is generated at the output of Q5. The electric charge in the capacitor C2 of the time control circuit for controlling the seconds is discharged and reset when the flash light is emitted and the instantaneous output turns on the transistor Q2. While the flash continues to emit light in this state, Q2 is turned on and the shutter remains open. Then, when the light emission stops, the output disappears, so Q2 is turned off, and after a time constant of, for example, 1 sec between the L resistor R and C2, the second control circuit T is triggered and the magnet M is activated. Close the shutter. Therefore, the shutter closing operation is performed immediately after the strobe light emission ends, and completely synchronized light emission is performed. Next, when photographing is performed using a flash bulb, the duration of the flash is about 20 seconds, so the output of SPC2 is maintained during this period, and transistor Q2 remains on during this period. In this case as well, when the light emission ends, Q2 turns off,
Instantaneous C2 is charged by the time constant of R and C2, and T is reversed to activate M, and the shutter closes immediately after the flash bulb stops emitting light. As described above, in this device, regardless of the type of flash, the shutter can always synchronously emit light using the X contact, and the time to close the shutter is automatically determined depending on the length of the light emission. Next, FIG. 2 is a circuit connection diagram showing another embodiment of the present invention. In this device, after a certain period of time after the flash device emits light, for example, 1 se
After c, the presence or absence of a flash output is detected by a light receiving element, and the type of flash is identified based on the presence or absence. In the figure, the same parts as in FIG. 1 are designated by the same reference numerals. R6 and C4 are a time-fixing resistor and capacitor for the 1 sec timer circuit, Q3 is a switching transistor that turns on and off both ends of C4, and T2 is a sand-time control circuit. Q4 is an emitter-follower stage transistor that operates with the output of T2, and its output operates the switching transistor Q5, false, and also serves as a charging circuit for a strobe consisting of Q7 and R7 or a charging circuit for a flash bulb consisting of Q8 and R8. Power the circuit. Transistors Q5-Q, . The circuit consisting of the switching transistor Q2 of the second time control circuit
This is a circuit for controlling. The operation of this device is such that when the shutter button is released, the flash device is triggered by the × contact in synchronization with the release of the shutter, and a flash is emitted. This emitted light is received by the light receiving element SPC2, amplified by A2, and its high frequency component is sent to the S
is applied to the control electrode of the CRI to trigger it. S.C.
The conduction of RI turns off transistor Q3 and charges C4 through R6. Since the time constant of this circuit is set to 1 sec, T2 is inverted 1 sec after the light is emitted, and a flash signal is generated at its output. This signal generates a voltage at the emitter of Q, turning transistor Q5 on and transistor Q6 off. On the other hand, when SCRI is turned on, Q9 is turned on, T,. Off, Q,
．． is turned on, and at the same time as the flash is emitted, the transistor Q2 connected to both ends of the capacitor C2 of the timer circuit is turned on, resetting C2.Then, Q6 is turned off after 1 sec, so Q2 is At this point, if the flash device is a strobe, it has finished emitting light before 1 sec, so there is no output from SPC2 and A2, so PNP transistor Q7 is turned on and NPN transistor Q8 is turned off. C2 is charged through the resistor K7, and the second control circuit T, is inverted and the shutter is closed by M.The time constants of R7 and C2 are extremely short (as they are set, the shutter operates at a second time of approximately 1 second). Next, in the case of a flash bulb, the light emission continues even when the 1 skin sec timer is activated, so there is an output from SPC2, so in this case Q7 is turned off and Q8 is turned on. When Q8 is turned on, C2 is charged through resistor R8.The time constant of R8 and C2 is set to 20 msec, so the shutter is open for 20 seconds from 1 second after the light emission starts. If the light emission stops during this time, Q? will be turned on and Q8 will be turned off, as before, and C will be turned on by R7.
2 is instantly charged, T is reversed, and the shutter is closed. As described above, this device distinguishes between a strobe and a flash bulb based on whether or not the flash continues for a certain period of time after the flash is emitted, and activates the seconds control circuit. In this case, the exposure time is set to 20 seconds, or if the exposure time is shorter than that, the shutter is closed when the light emission stops.
FIG. 3 is a circuit connection diagram showing another embodiment of the present invention. The circuit configuration is similar to the embodiment shown in FIG. It is designed to perform exposure for a certain period of time.

In the figure, the same parts as in FIGS. 1 and 2 are designated by the same reference numerals. The operation of the device in the figure is almost the same as the one in Figure 2, but in this device, the circuit configuration of SCR2 and Q, 2, R9, Q, 3, R, o is used for the second control circuit when flashing. It is being That is, when using a strobe, the light emission stops when the 1 second timer R6, C4 and L are reversed after the flash light is emitted, and SCR2 is turned off by the flash signal from SPC2 and A2, so the transistors Q,
2 is turned on, the time setting capacitor C2 is immediately charged through R9, T, is inverted, and the shutter is closed by M. In the case of a flash bulb, lwsec. When the timers R6, C4, and L operate to generate an output, the light emission is still continuing, which turns on Q and 3 and charges C2 through R and o. The time constant of this circuit is 20ms
ec. Therefore, in the case of a flash bulb, the shutter is set at 20 msec. It will be closed. The operations of the other circuits are the same as those of the apparatus shown in FIGS. 1 and 2, so their explanation will be omitted. As described above, since the shutter control device according to the present invention prohibits the shutter closing operation while the flash device continues to emit light, there is no need to manually select the shutter time depending on the type of flash when taking flash photography. Even during daytime flash photography using a strobe, the shutter is closed immediately after the flash stops, so there is no blurring due to camera shake or subject movement, which is very effective.

In addition, according to this method, the synchronization contact of the camera can always be the × contact, so it has the feature that flash photography can be easily performed with any type of shutter, and is extremely effective in terms of the configuration of the camera and flash device. There is something.

[Brief explanation of drawings]

FIG. 1 is a circuit connection diagram showing one embodiment of the shutter time control method according to the present invention, and FIGS. 2 and 3 are circuit connection diagrams showing other embodiments of the method of the present invention. SPC1, SPC2. ．． ．．・・・． silicon photocell,
1... Photography information source, A,, A2... Operational amplifier, D. ...Log diode, T, ...secondary control circuit, M, ...magnet, Q, ~Q. 3...
Transistor, SCRI...Cirisu, C, ~C4...
...Capacitor, S, ~S4...Switch, E
...Power battery. Meat ship meat N Funayu, m ship

Claims (1)

[Claims] 1. A detection circuit that detects the light emitting state of the flash device that is activated to emit light in conjunction with the shutter opening operation during flash photography and outputs a light emitting signal while the flash device is in the light emitting state, and a detection circuit that is ready for operation in response to the light emitting signal. a flash second time signal output circuit that operates and generates an output when the light emitting signal disappears, and a switching means that generates a first output in response to the light emitting signal and generates a second output when the light emitting signal disappears. a timer circuit that starts timing upon receiving the second output of the switching means and the output from the flash seconds signal output circuit; and a shutter seconds control that sends out a shutter close signal in response to the timer output. 1. A flash shutter control device comprising a circuit.