JPS6235096B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tuning contact device for a programmable electric shutter.

Cameras with built-in lens-type electric shutters are
Exposure time is automatically controlled depending on the brightness of the subject. There are two types of cameras: those equipped with an aperture and those with a programmable shutter blade that also serves as the aperture.

In the former type of camera with an aperture, the aperture aperture is controlled according to the shooting distance during night photography, and the shutter blades are fully opened and the synchronizing contact is turned on when the shutter begins to close, causing the flash device to fire.

In the latter case, a programmable camera without an aperture,
It is not possible to control the aperture according to the shooting distance. Therefore, set the delay time according to the shooting distance,
The flash device emits light while the shutter blades are fully open, and the aperture diameter of the shutter is well matched to the time when the flash device emits light.

Many modern cameras have built-in flash devices that allow them to perform not only night photography, but also synchronized photography during the day. This daytime synchronized shooting is
The EE mechanism and flash device are linked together to take pictures, and since the flash device is used as auxiliary lighting, it has the advantage of being able to take clear pictures even in backlight.

The former camera with an aperture can perform daytime synchronized photography by controlling the exposure time according to the brightness of the subject and controlling the aperture according to the shooting distance.

However, the latter type of camera without an aperture has the disadvantage that synchronized photography during daytime cannot be performed because the electric shutter and flash device are not synchronized. In other words, in daytime synchronized photography, the subject brightness is high and the exposure time is short, so if the flash device fires according to the shooting distance, the flash device fires later than the exposure time, so the electric The flash device fires after the shutter is closed.

SUMMARY OF THE INVENTION In view of the above drawbacks, it is an object of the present invention to provide a synchronization contact device for a programmable electric shutter that allows the shutter and flash device to be properly synchronized even during daytime synchronized photography.

The device of the present invention is provided with a detection means for detecting the start of closing of the programmable electric shutter, a delay means for setting a delay time according to the photographing distance, and a synchronization switch means that is turned on by signals from both of these means. The present invention is characterized in that the tuning switch means is turned on by a signal from the earlier one of the detection means and the delay means to cause the flash device to emit light.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing an outline of the present invention. The shutter closure detection circuit 1 electrically or mechanically detects when the programmable electric shutter starts to close. The delay circuit 2 sets a delay time according to the shooting distance from the time when the electric shutter starts opening.

The output signals from both circuits 1 and 2 are sent to a tuning switch circuit 3. The tuning switch circuit 3 includes a semiconductor switching element such as a thyristor inserted into a trigger circuit (not shown) of the strobe circuit 4, and the thyristor is turned on.
When this occurs, the trigger circuit is activated to cause the strobe to fire.

When photographing at night, the electric shutter is set to the lowest speed, for example around 1/30 second, which does not cause camera shake. At this exposure time, the shutter blades are fully open. By turning the distance ring on the lens according to the distance to the subject, the delay circuit is controlled in conjunction with this distance ring, and a delay time is set according to the shooting distance.

When you press the release button, the electric shutter is activated and the shutter blades are fully opened. At this time,
Since the exposure time is long, the signal from delay circuit 2 is always sent to tuning switch circuit 3 earlier. Therefore, when the desired shutter aperture is reached while the shutter blade is fully open, the tuning switch circuit 3 is turned on at a timing depending on the shooting distance, causing the flash tube (not shown) of the strobe circuit 4 to emit light.

Daytime synchro photography involves firing a strobe during EE photography, so the exposure time of the electric shutter is automatically set according to the brightness of the subject. In this daytime sync photography, the exposure time is quite short. Therefore, in most cases, the signal from the shutter closure detection circuit 1 enters the tuning switch circuit 3 earlier than the signal from the delay circuit 2. As a result, the flash tube of the strobe circuit 4 emits light when the shutter starts to close. Note that the signal from the delay circuit 2 may be faster depending on the relationship between the subject brightness and the subject distance. In this case, similarly to night photography, the strobe emits light when the shutter aperture diameter reaches a diameter corresponding to the photographing distance. In this way, in both night photography and daytime synchronized photography, the shutter and flash device are synchronized to provide appropriate exposure.

FIG. 2 is a circuit diagram showing a specific configuration of the present invention.

A light receiving element 10 and a capacitor 11 are connected in series to form a delay circuit of an electric shutter. A series circuit of a diode 12 and a trigger switch 13 is connected in parallel with this capacitor 11.

The charging voltage of the capacitor 11 and the resistor 14,
A comparator 16 compares the voltage with a reference voltage set by a comparator 15 . A shutter closing magnet 17 is connected to the output terminal of the comparator 16.

Electric shutter 18 composed of the above-mentioned parts
is supplied with power from the power source 20 while the power switch 19 is on. The strobe circuit 21 includes a booster circuit, a capacitor, a trigger circuit, a flash tube, etc., and is built into the camera. This strobe circuit 21 is connected to a power source 20 via a power switch 22.

A capacitor 24 is connected to the output terminal of the comparator 16 via a diode 23. Resistors 25 and 26 forming a discharge circuit are connected in parallel to this capacitor 24.

Generally, even when the shutter closing magnet 17 is demagnetized, the shutter blades do not immediately follow suit, but are accompanied by a certain mechanical delay. Therefore, the discharge time of the capacitor 24 is utilized to correct the mechanical delay of the shutter blade.

When the capacitor 24 is discharged, the base voltage of the transistor 27 increases.
Turn off. Each component from the diode 23 to the transistor 27 constitutes the shutter closure detection circuit 1.

A time constant circuit consisting of a variable resistor 28 and a capacitor 29 is connected in series to the transistor 27. The resistance value of the variable resistor 28 is adjusted in conjunction with the distance ring of the lens. A bypass resistor 30 is connected in parallel with these time-fixing circuits.

The transistor 31 controls the start of operation of the timer circuit, and its base is connected to the + pole of the power supply 20 via a diode 32 and a resistor 33. Moreover, the anode of the diode 32 is
It is connected to the cathode of the diode 12 of the electric shutter 18 via a diode 34, and turns on the transistor 31 when the trigger switch 13 is turned off and the shutter is opened.

A Schmitt trigger circuit consisting of transistors 35 and 36 is connected to the time setting circuit. The collector of this transistor 36 is connected to the power supply 20 via a resistor 37. A delay circuit 1 is constituted by each of these circuits.

A series circuit of a diode 38 and a capacitor 39 is connected to the resistor 37. This capacitor 39 turns on the trigger circuit of the strobe circuit 21.
The gate of the thyristor 40 is connected to the gate of the thyristor 40. Tuning switch circuit 3 is formed by each of these parts.
is configured.

Next, the operation of the above embodiment will be explained. When the power switch 19 is turned on and the shutter button is pressed, the shutter is released and the shutter blades are opened. Since the trigger switch 13 is turned off when the shutter blade opens, the capacitor 11 is charged with a photocurrent corresponding to the brightness of the subject.
When the voltage of this capacitor 11 reaches the reference voltage, the comparator 16 is inverted and its output terminal changes from "L" to "H". Accordingly, the energization of the shutter closing magnet 17 is cut off, the closing operation of the shutter blade is started, and the exposure time is automatically controlled.

When taking strobe photography, also turn off the power switch 22.
Turn it on. When the shutter button is pressed to turn off the trigger switch 13, the transistor 31
turns on. At the same time, comparator 16
Since the output terminal of is set to "L", transistor 27 is also turned on. Further, the transistor 36 of the Schmitt trigger circuit is also turned on.

These transistors 27, 31, 36 are ON
When this happens, the capacitor 39 is charged. In addition,
The capacitor 24 is charged when the power switches 19 and 22 are turned on, regardless of the trigger switch 13. On the other hand, capacitor 2 constituting the time constant circuit
9 is gradually charged through a resistor 28 that is adjusted according to the shooting distance.

In night photography, since the photocurrent of the light receiving element 10 is small, the exposure time is longer and the shutter is fully opened. Therefore, before the comparator 16 is inverted, the capacitor 29 is charged to a predetermined level,
This inverts the Schmitt trigger circuit. As a result, the transistor 36 turns off, so
Capacitor 39 discharges and turns on thyristor 40
Make it. When this thyristor 40 is turned ON, the trigger circuit of the strobe circuit 21 is closed, so that the flash tube emits light. In this way, in night photography,
While the shutter blades are fully open, the flash fires at a timing appropriate to the shooting distance.

In daytime synchronized photography, the photocurrent of the light receiving element 10 is large, so the exposure time is short. Therefore, the comparator 16 reverses quickly and demagnetizes the shutter closing magnet 17. This comparator 1
When 6 is reversed, diode 23 is reverse biased and capacitor 24 starts discharging. When this capacitor 24 is discharged, the transistor 2
7 is turned off. This transistor 27 is OFF
When this happens, the transistor 36 is also turned off, so the ignition current enters the gate of the thyristor 40,
Turn this on and the strobe will fire. Thus, in daytime synchronized photography, the strobe lights when the shutter starts to close.

The present invention having the above configuration causes the flash device to emit light in synchronization with the earlier of the shutter closing start time and the delay time depending on the photographing distance, so it can be used not only for night photography but also for daylight photography. Even in medium sync shooting, you can reliably synchronize and get the correct exposure.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the outline of the present invention, Figure 2 is a block diagram showing the outline of the present invention.
The figure is a circuit diagram showing one embodiment of the present invention. 10... Light receiving element, 13... Trigger switch,
16... Comparator, 17... Shutter closing magnet, 28... Variable resistor that changes depending on the shooting distance, 40... Thyristor.

Claims (1)

[Scope of Claims] 1. Detection means for detecting the start of closing of the electric shutter, delay means for setting a delay time according to the shooting distance from the start of opening of the electric shutter, and signals from the detection means and the delay means. a synchronized switch means which is turned on and causes the flash device to emit light;
A programmable electric shutter that automatically controls the exposure time according to the brightness of the subject, with the flash device firing in synchronization with the earlier of the electric shutter's start of closing or a delay time depending on the shooting distance. In the tuned contact device, the detection means has a delay circuit, and the delay circuit includes a first transistor that turns off after a predetermined time has elapsed after the shutter closing magnet is demagnetized, and the delay means A CR time constant circuit is connected in series with the first transistor and whose time constant is adjusted according to the photographing distance.The CR time constant circuit is connected in series with the first transistor and is turned on when the trigger switch of the electric shutter is turned off. a second transistor for operating a CR time setting circuit; and a Schmitt trigger circuit for detecting the level of a capacitor of the CR time setting circuit; A tuning contact device for an electric shutter, characterized in that it is equipped with a thyristor that turns on when the shutter is turned on.