JPH035567B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a strobe tuning device for an automatic exposure control camera using a dedicated strobe.

In recent years, automatic exposure control has also been implemented in strobe photography. In this system, a special auto strobe is attached to an ordinary automatic exposure control camera, the camera's aperture is set by the signal from the strobe, the shutter is controlled by the camera's shutter control signal, and the strobe fires. is also controlled. Therefore, when a strobe other than a dedicated strobe is attached, the aperture and shutter speed must be set manually, but if you mistake it for a dedicated strobe and take a photo without setting the aperture or shutter speed, Proper exposure cannot be obtained.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a strobe tuning device for a camera that has a function of preventing malfunctions when a strobe other than a dedicated strobe is attached.

Hereinafter, one embodiment of a tuning device according to the present invention will be described with reference to the drawings. FIG. 1 is its circuit diagram. Negative power supply terminal -Vb is connected to resistance through switch 10
Connected to one end of 12. The switch 10 is a normally open switch and is closed in conjunction with depression of the release button. The other end of the resistor 12 is connected via a switch 14 to the positive power supply terminal Vcc. The switch 14 is a normally closed switch and is opened in conjunction with the start of travel of the front shutter curtain. The connection point between switch 14 and resistor 12 is oscillator 16
It is connected to the reset terminal R of the binary counter 18 which counts the clock pulses output by the counter. The counter 18 is composed of N flip-flops and has N output terminals ₁ - _N . Further, the connection point between the resistor 12 and the switch 14 is connected to the set end of the flip-flop 22 via the inverter 20, and is also connected to the set end of the flip-flop 22 via the resistor 24.
connected to the base of The emitter of the transistor 26 is connected to one end of the capacitor 28 and also to the negative power supply terminal -Vb via the switch 10. The other end of the capacitor 28 is the transistor 2
6, the anode of the photodiode 30, and the inverting input terminal of the differential amplifier 32. The photodiode 30 is placed behind the mirror of the camera at a position where it does not obstruct the optical path to the film and receives reflected light from the film and the shutter front curtain. The cathode of photodiode 30 is grounded. The Nth digit output terminal _N of the counter 18 is connected to the base of the PNP transistor 6 via a resistor 34. The emitter of transistor 36 is connected to the cathode of photodiode 30, and the collector of transistor 36 is connected to the anode of photodiode 30 through resistor 38. One end of the constant current source circuit 40 is grounded, and the other end is connected to the non-inverting input terminal of the differential amplifier circuit 32 and also to the negative power supply terminal -Vb via the variable resistor 42 and the switch 10. Differential amplifier 3
The output terminal of 2 is connected to a light emission control terminal 44 and one input terminal of a NAND gate 46, and is also connected to one input terminal of a NAND gate 50 via an inverter 48.

The positive power supply terminal Vcc is grounded via a switch 52 and a resistor 54. The switch 52 is a normally open switch and is closed in conjunction with depression of the release button. The connection point between the switch 52 and the resistor 54 is connected to one end of an aperture control magnet 60 and a release magnet 62 via an aperture control circuit 56 and an electromagnetic release circuit 58, respectively. The other ends of the aperture control magnet 60 and the release magnet 62 are connected to the positive addition source end Vcc.

The output terminal of NAND gate 46 is NAND gate 6
Connected to one input end of 4. NAND gate 6
The output terminal of 4 is connected to the base of an NPN transistor 68 via a resistor 66. transistor 68
The emitter is connected to the anode of the Zener diode 70 and the emitter of the NPN transistor 72, and is also connected to the negative power supply terminal -Vb via the switch 10. The collector of the transistor 68 is connected to the cathode of a Zener diode 70 and the collector of a transistor 72, and is also grounded via a trailing curtain locking magnet 74. The base of the transistor 72 is connected to the M-th digit output terminal _M of the counter 18 via a resistor 76.

The emitter of transistor 72 is grounded via resistor 78 and switch 80. The connection point between the resistor 78 and the switch 80 is connected to one input terminal of the NAND gate 82 and the aperture control circuit 56.
It is connected to the other input terminal of NAND gate 46, the other input terminal of NAND gate 50, and one input terminal of NAND gate 86 via inverter 84.
The output terminal _X of the X digit of the counter 18 is the reset terminal of the flip-flop 22, and the NAND gate 82.
is connected to the value input terminal of NAND gate 82
The output terminal of is connected to the other input terminal of the NAND gate 64. The Q output of flip-flop 22 is connected to the first NAND gate 90 via inverter 88.
Connected to the input end. An output terminal of NAND gate 50 is connected to a second input terminal of NAND gate 90.

A dedicated strobe terminal 92 is connected to an input terminal of a detection circuit 94 . The output terminal of the detection circuit 94 is connected to the base of a PNP type transistor 98 and the aperture control circuit 56 via a resistor 96. transistor 9
The emitter of the transistor 98 is grounded, and the collector of the transistor 98 is connected to the negative power supply terminal -Vb through the resistor 100 and the switch 10.
2 to the other input terminal of the NAND 86. The output of NAND gate 86 is connected to the third input of NAND gate 90. The output end of NAND gate 90 is connected to one end of capacitor 106 via inverter 104. capacitor 10
The other end of 6 is connected to the gate of thyristor 108. A resistor 110 is connected between the gate and cathode of the thyristor 108, the cathode of the thyristor 108 is grounded, and the anode of the thyristor 108 is connected to a tuning terminal 112. Ground terminal 114 is grounded. The above-mentioned light emission control terminal 44, dedicated strobe terminal 92, tuning terminal 112, and ground terminal 114
is used for grounding with a strobe device, which will be described later.

FIG. 2 is a circuit diagram of an autostroboscopic device dedicated to a camera having the tuning device shown in FIG.
The positive terminal of the high voltage power supply 116 is the main capacitor 118
and one end of the strobe tube 120. The negative terminal of high voltage power supply 116 is connected to switch 122.
is connected to the anode of the Zener diode 124 via the zener diode 124. The anode of the Zener diode 112 is connected to the dedicated strobe terminal 92 via a resistor 126. The cathode of the Zener diode 124 is the other end of the main capacitor 118, and the thyristor 128
is connected to the cathode and ground terminal 114 of.
The anode of the thyristor 128 is the strobe tube 120
It is connected to the other end and one end of the capacitor 130. The light emission control terminal 44 is connected to the input end of the light emission amount control circuit 133 , and the output end of the light emission amount control circuit 133 is connected to the other end of the capacitor 130 . The tuning terminal 112 is connected to the input end of the trigger circuit 132, and the output end of the trigger circuit 132 is connected to the strobe tube 12.
The control terminal of the trigger circuit 132 is connected to the gate of the thyristor 128.

FIG. 3 is a circuit diagram of a general strobe device that is not exclusive to this camera. Components that are the same as those in FIG. 2 are given the same numbers and their explanations will be omitted. In other words, the strobe device shown in FIG. 3 cannot control the amount of light emitted;
is not provided.

The operation of this embodiment will be explained below. First, the case where the dedicated autostroboscopic device shown in FIG. 2 is installed will be described. In this case, it is a programmable EE that automatically controls the aperture, shutter speed, and strobe light output depending on the brightness of the subject.
Of course, even when using an auto flash, the aperture priority type
EE is possible, but the basic operation is the same, so the explanation will be omitted. The switch 80 functions as a switch for changing the shutter speed control mode, and is opened when the automatic mode is set and closed when the manual mode is set. That is, the open/closed state of the switch 80 is determined depending on whether the attached strobe device is a dedicated auto strobe or not. Here, the switch 80 is naturally open. The photographer first closes the switch 122 of the flash device. As a result, the main capacitor 118 is charged via the Zener diode 124. zener diode 1
A Zener voltage is generated across the terminal 24, and this voltage is supplied to the detection circuit 94 on the camera side via the resistor 126 and the dedicated strobe terminal 92. When the release button is pressed, switches 10 and 52 are closed and power supply voltage is supplied to all circuits. The detection circuit 94 detects the completion of charging of the capacitor 118. The output signal of the detection circuit 94 becomes L level, and the transistor 98 becomes conductive. Since the H level collector signal of the transistor 98 is made to the L level via the inverter 102 and is supplied to the NAND gate 86,
The output terminal of NAND gate 86 is at H level.
Since switch 80 is open, the output terminal of inverter 84 is at H level. Before the leading shutter curtain runs, the transistor 26 is in a conductive state, so the capacitor 28 is not charged, and the terminal voltage of the capacitor 28 is zero. Therefore, the output terminal of the differential amplifier 32 is at H level, and the output terminal of inverter 48 is at L level. Since both input ends of the NAND gate 50 are at H and L, the output end is at H level. Also, before the shutter front curtain runs, the output terminal of the inverter 20 is at the L level, so the flip-flop 22
is set, and the output terminal of inverter 88 is at L level. Therefore, NAND gate 90
Since one of the input terminals is at L level, the output terminal is at H level. Since the output end of the NAND gate 90 is connected to one end of the capacitor 106 via the inverter 104, the thyristor 108 is in a non-conducting state and the strobe tube 120 does not emit light.

The aperture control circuit 56 operates in response to an L level signal from the connection point between the switch 80 and the resistor 78 and the detection circuit 94, and energizes the aperture control magnet 60 to set the aperture according to the brightness of the subject. Generally, when photographing with a strobe, the subject is dark, so the aperture is set at or close to wide open. However, if the strobe is fired in this condition, the flash must be stopped in an extremely short period of time, making strobe control time-consuming. This will result in overexposure. Also,
From the point of view of depth of field, it is preferable to take a photograph with the aperture closed to a certain extent, so this aperture control circuit 56 sets the aperture to a certain aperture (for example, F5, F6).
It is configured so that it cannot be opened any further.

When the release button is pressed and the switch 52 is closed, the mirror is raised, and when the mirror has finished raising, the electromagnetic release circuit 58 starts running the front shutter curtain. When the switch 14 is opened in conjunction with the start of running of the shutter front curtain, the counter 18 is reset and the transistor 26 becomes non-conductive, so that the photovoltaic current of the photodiode 30 charges the capacitor 28.
The terminal voltage of increases gradually. When the switch 14 is opened, the output terminal of the inverter 20 becomes H level, but at this time, since all output terminals of the counter 18 are at the H level, the output terminal of the flip-flop 22 is kept at the H level. Therefore, NAND
The output terminal of gate 90 is kept at H level, and thyristor 108 is not conductive.

The X-digit output terminal _X of the counter 18 is the time from when the counter 18 is reset, that is, from when the leading shutter curtain starts running until the running of the leading shutter curtain ends (1/1 in this embodiment). 60
seconds), it changes from H level to L level. The flip-flop 22 is reset because its reset terminal goes to the L level, and the output terminal Q changes to the L level, so the output end of the inverter 88 changes to the H level. At this time, photodiode 3
If the amount of light received at 0, that is, the charging voltage of the capacitor 28 has not reached the predetermined voltage determined by the variable resistor 42, the output terminal of the differential amplifier 32 remains at H level, so the 3 inputs of the NAND gate 90 All ends are at H level. Therefore, the output terminal of the NAND gate 90 changes from H level to L level, and the output terminal of inverter 104 changes from L level to H level.
level, and the output terminal of inverter 104 is L.
The thyristor 108 changes from level to H level.
A positive pulse voltage is applied between the gate and cathode of. As a result, the thyristor 108 becomes conductive, the trigger circuit 132 of the strobe device is energized, and the strobe tube 120 emits light.

When the terminal voltage of the capacitor 28 reaches a predetermined voltage, the output terminal of the differential amplifier 32 changes to L level, the light emission amount control circuit 133 is energized, and the strobe tube 120 stops emitting light. At the same time,
The output terminal of NAND gate 46 is H level, NAND
The output terminal of gate 64 becomes L level. and,
The transistor 68 is made non-conductive, the shutter trailing curtain locking magnet 74 is deenergized, the shutter trailing curtain is moved, and the shutter operation is completed.

In this way, the running of the shutter trailing curtain is controlled at the timing when the amount of light received by the photodiode 30 reaches a predetermined value, but the shutter time cannot be shortened indefinitely for mechanical reasons. Also,
Even when the subject is dark, it is necessary to set a certain limit on the shutter speed, since if the shutter speed is extended indefinitely, inconveniences will occur, such as not being able to take the next shot forever or increasing battery consumption. The Mth digit output terminal _M of the counter 18 becomes L level after the shortest shutter time (for example, 1/1000 seconds) after being reset, and the Nth digit output terminal _N goes to the L level after the shortest shutter time (for example, 1/1000 seconds) after being reset. It is set to become L level later. Therefore, when this _M output terminal is at H level, the output terminal of differential amplifier 32 is at L level.
Even if the transistor 68 is turned off, the shutter trailing curtain will not run because the transistor 72 is still turned on. Then, after the _M output terminal of the counter 18 becomes L level, that is, after 1/1000 seconds have passed since the leading shutter curtain was run, the trailing shutter curtain is run. In this way, the shutter time is always longer than 1/1000 second. Further, when the _N output terminal of the counter 18 becomes L level, the transistor 36 becomes conductive and the output terminal of the differential amplifier 32 becomes L level regardless of the terminal voltage of the capacitor 28. Therefore, the transistor 68 becomes non-conductive and the shutter trailing curtain runs. That is, the shutter time will never be longer than 4 seconds.

On the other hand, if the amount of light received by the photodiode 30 reaches a predetermined value before the output terminal of _X of the counter 18 reaches the L level, when the output terminal of the differential amplifier 32 changes to the L level, the shutter The rear curtain is running. At this time, the output terminal of the NAND gate 50 becomes L level, so the output terminal of the NAND gate 90 necessarily becomes H level, and the thyristor 10
8 is not electrically connected and the strobe tube 120 does not emit light.

Next, a case will be described in which a general strobe device shown in FIG. 3 is attached. At this time, automatic exposure control is not possible, and the shutter speed is 1/60 seconds.
The aperture is manually set to the value determined by the strobe's guide number. At this time, switch 80 is closed. Furthermore, since a general strobe device is not provided with the light emission control terminal 44 and the strobe connection terminal 92, the transistor 98 is not conductive and the output terminal of the inverter 102 is at H level. However, since the switch 80 is closed, the output terminal of the inverter 84 is at the L level, and the output terminal of the NAND gate 86 is at the H level, the same as when the dedicated autostroboscopic device is installed. Also, since the output terminal of the inverter 84 is at L level,
The output terminal of the NAND gate 50 is always at H level regardless of the level of the output terminal of the differential amplifier 32. Before the leading shutter curtain runs, the flip-flop 22 is set, so the output terminal of the inverter 88 is at the L level, the output terminal of the NAND gate 90 is at the H level, and the thyristor 108 is not conductive.

Even when the shutter leading curtain is run, the flip-flop 22 remains set as in the case described above.
When 1/60 second has elapsed since the shutter leading curtain started running, _{the X} output terminal of the counter 18 becomes L level, so the flip-flop 22 is reset, and the thyristor 108 is made conductive as in the case described above, and the strobe tube 120 is turned on. It emits light. Here, since the output terminal of the inverter 84 is at L level,
The output terminal of the NAND gate 46 is always at H level. At this time, the output terminal of the NAND gate 82 also becomes H level due to the _X output signal of the counter 18, so that the output terminal of the NAND gate 64 becomes L level. As a result, the transistor 68 is rendered non-conductive, and the trailing curtain of the shutter starts running.

Here, the operation when a photograph is taken with the switch 80 left open due to an operational error will be described below. That is, even though the dedicated auto strobe is not installed, the changeover switch 80 remains set to auto mode, and the shutter speed is not set. Here, since the detection circuit 94 is not energized and the transistor 98 is non-conductive, both input terminals of the NAND gate 86 are at H level. Therefore, the NAND gate 90 is 1
Since the two input terminals are at L level, the output terminal is always at H level. This means that thyristor 10
8 means never conductive, and the strobe tube 120 never emits light. Therefore, normal EE photography is performed using natural light, and vertical stripes do not appear on the film due to synchronization errors between the strobe and shutter. When the strobe tube does not emit light, the photographer knows that the dedicated strobe is not attached, and from the next shoot he either replaces it with a dedicated strobe or switches the switch 80 to the universal mode to ensure proper exposure. You can take pictures with.

As explained above, according to the present invention, when a strobe other than a dedicated strobe is attached, the strobe will not fire unless the exposure is manually set.
It is possible to provide a strobe synchronization device for a camera that does not cause malfunction of the automatic exposure control circuit of the camera and failure to obtain proper exposure.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of an embodiment of a camera strobe tuning device according to the present invention, Fig. 2 is a circuit diagram of an auto strobe device exclusively for this camera, and Fig. 3 is a circuit diagram of a general strobe device not exclusively for this camera. It is a circuit diagram. 10, 14, 52...Switch, 18...Counter, 22...Flip-flop, 28...Capacitor, 30...Photodiode, 32...Differential amplifier, 44...Light emission control terminal, 74...Shutter rear curtain Locking magnet, 80... Selector switch, 92... Dedicated strobe terminal, 108... Thyristor, 112... Tuning terminal, 114... Grounding terminal.

Claims (1)

[Claims] 1 In a camera strobe synchronization device used with a dedicated strobe that supplies a dedicated strobe signal to the camera side and starts and stops flashing in response to a flash start signal and a flash stop signal supplied from the camera side, receives the reflected light of
A photometer that outputs a light emission stop signal to the strobe side when the amount of received light reaches a predetermined amount of light and also generates a shutter control signal, and an auto mode as a shutter control mode in which the shutter operation ends in response to the shutter control signal. , a manual mode in which the shutter speed is set to a constant strobe synchronization speed;
a strobe discrimination means for determining whether a dedicated strobe or a general strobe is attached according to the presence or absence of the dedicated strobe signal; a light emission trigger means for outputting a light emission start signal to the strobe; and the switching means; It is connected to a strobe discrimination means and a light emission trigger means, and operates upon detecting that the switching means selects the auto mode and the strobe discrimination means discriminates whether the general strobe is attached, and the light emission trigger operates. A strobe device for a camera, comprising a blocking means for preventing the means from outputting a light emission start signal.