JPS6239412B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a warning erroneous display prevention circuit in a programmable electric shutter linked to a light receiving aperture.

A programmable electric shutter linked to the light receiving aperture is already known, in which the light receiving window is opened in advance for a warning operation, and after the light receiving window is shielded, the light receiving aperture is also opened in conjunction with the opening of the shutter blades that also serve as aperture blades. However, in this type of programmed electric shutter, if the light receiving window is blocked, the same condition as the low brightness warning occurs, resulting in an erroneous display.

The present invention eliminates the drawbacks of the conventional circuit described above, and operates a delay circuit before shifting to the opening operation of the shutter blade, and latches the warning circuit to a disabled state by an electric signal indicating the end of the operation. To provide a circuit for preventing erroneous warning display in a programmable electric shutter linked to a light receiving aperture, which operates properly regardless of whether a self-timer is used, and which prevents erroneous display from occurring.

Embodiments of the present invention will be described below based on the drawings.

First, the structure of the shutter mechanism shown in FIGS. 1 to 5 will be explained. 1 is a shutter plate which forms an exposure opening 1a and a light receiving window 1b, and has pins 1c to 1i implanted therein. Reference numeral 2 denotes a release plate, which has long grooves 2a, 2b and a bend 2c that fit with pins 1c, 1d, has a pin 2d planted therein, and is given an upward movement habit by a spring 3. 4 is a closing drive plate, which has long grooves 4a and 4b that fit with pins 1c and 1e, a hook 4c, and arms 4d and 4.
In addition to forming a slope 4f and a flat surface 4g, pins 4h and 4i are installed, and springs 5 applied to the pins 1e and 4h provide a rightward movement habit. Reference numeral 6 denotes a leaf spring member, which is fixed on the closing drive plate 4 with screws 6a and 6b, as shown in FIG.
Bends 6 protruding toward the back side of the closing drive plate 4 at both ends
c and 6d, and have slopes 6c' and 6d', respectively. The bend 6c is adapted to engage with the bend 2c of the release plate 2. 7 is a shutter release lever pivotally connected to a shaft 8, which forms arms 7a, 7b and another arm 7c that can engage with a pin 1f;
The distal end 7a of the arm 7a is bent so as to be located within the motion locus of the bend 6d, and a spring 9 imparts dextrorotation so that the arm 7a' engages the pin 1f. Reference numeral 10 denotes an opening/closing lever pivotally attached to a shaft 11, which has an arm 10a that can engage with the arm 7c, and has a non-conductive pin 10b, a protrusion 10c, and pins 10d to 10f implanted therein. A conductive ring 12 is fitted onto the pin 10b. A spring 13 also serves as a lead wire, and is hung between the pin 1i and the conductive ring 12, giving levorotation to the opening/closing lever 10. The arm 4e of the closing drive plate 4 is the opening/closing lever 1
The arm 4e and the conductive ring 12 constitute a synchro switch. 1
Reference numeral 4 denotes a shutter blade, one of which is one of a set of two blades, which also serves as an aperture blade, and includes long grooves 14a and 14b that fit with pins 1g and 1h, and long groove 1 that fits with pin 10d.
4c, a shutter opening 14d, an exposure warning information introduction opening 14e, and an exposure information introduction opening 14f. For other shutter blades (not shown), with the exposure warning information introduction opening aligned with the exposure warning information introduction opening 14e of the shutter blade 14, the shutter opening and the exposure information introduction opening are connected to each other. They are formed laterally symmetrically with each other, and the long grooves corresponding to the long grooves 14b are fitted with the pins 10e. The light-receiving element is arranged corresponding to the light-receiving window 1b so as to be able to receive field light through the aperture 14e or 14f. Reference numeral 15 denotes an iron piece lever pivotally attached to the shaft 16, and a bending portion 15a capable of locking the arm 4d.
and other bends 15b and 15c.
Reference numeral 17 denotes an iron piece, which is pivotally mounted on the bend 15b by a pin 18. Reference numeral 19 denotes a hold lever pivotally connected to the shaft 16, and has a pin 19a implanted therein that can engage the slope 4f and the flat surface 4g, and a bending lever 15c.
An arm 19b is formed that engages one side surface of the arm 19b, and a spring 20 imparts dextrorotation. Reference numeral 21 denotes an iron piece spring, which is hung between the iron piece lever 15 and the hold lever 19, and acts to press the bending part 15c and the arm 19b. Reference numeral 22 designates a timer lever pivotally connected to the shaft 16, which forms a bend 22a that can engage with the hook 4c and an arm 22b that engages with the other side of the bend 15c. is given.

Next, the configuration of the shutter control circuit shown in FIG. 8 will be explained in relation to the shutter mechanism. Reference numeral 101 is a power supply battery, the (-) pole of which is grounded. Reference numeral 102 denotes a power switch, which is provided opposite to the pin 2d of the release plate 2. 103 is a light receiving element such as a photovoltaic element, the anode of which is grounded, and the cathode of which is connected to the amplifier circuit 1.
It is connected to the inverting input terminal (-) of 04. 1
A logarithmic compression diode 05 has a cathode connected to the inverting input terminal (-) and an anode connected to the output terminal of the amplifier circuit 104. 10
6 is a reference voltage circuit. 107 is a window comparator, whose inverting input terminal (-) 107a is connected to the output terminal of the amplifier circuit 104, and its non-inverting input terminals (+) 107b and 107c are connected to the output terminals 106a and 106b of the reference voltage circuit 106, respectively. There is. 108 and 109 are LEDs (lamp etc. can be used) for high brightness warning and low brightness warning, and output terminals 107d, 10 of the window comparator 107
7e and the power supply battery 10 via the power switch 102.
1 (+) pole. Reference numeral 110 denotes a capacitor for controlling exposure time, one end of which is connected to the (+) pole of the power supply battery 101 via the power switch 102, and the other end of which is grounded via the collector and emitter of the logarithmic expansion transistor 111. The base of transistor 111 is connected to the output terminal of amplifier circuit 104. Reference numeral 112 denotes a switch for starting exposure time measurement, which is connected in parallel to the capacitor 110 and placed opposite to the pin 10f of the opening/closing lever 10. 113 is a comparator whose non-inverting input terminal (+) is the output terminal 106 of the reference voltage circuit 106
c, and its inverting input terminal (-) is connected to the connection point between the other end of the capacitor 110 and the collector of the transistor 111. A resistor 114 is connected to the output terminal 113a of the comparator 113. An electromagnet 115 is connected between the resistor 114 and the (+) pole of the power battery 101 via the power switch 102. 116 is an amplifier circuit,
The non-inverting input terminal (+) is connected to the output terminal 106d of the reference voltage circuit 106, and the output terminal is connected to the necessary inverting input terminal (+) of the amplifier circuit 104. A variable resistor 117 is connected between the output terminal of the amplifier circuit 116 and the inverting input terminal (-). 118 is a resistor, one end of which is connected to the connection point between the inverting input terminal (-) of the amplifier circuit 116 and the variable resistor 117, and the other end of which is grounded. 119 and 12
Reference numeral 0 denotes a resistor and a capacitor constituting a delay circuit for a self-timer. One end of the resistor 119 is connected to the (+) pole of the power battery 101 via the power switch 102, and one end of the capacitor 120 is grounded. 121 is a switch for starting the measurement of the delay circuit, which is connected in parallel to the capacitor 120;
It is provided opposite to the pin 4i of the closing drive plate 4. 12
2 and 123 are a self-timer set/reset switch and a resistor with an extremely small value.
The series circuit is connected in parallel to resistor 119. 124 is a comparator whose inverting input terminal (-) is connected to the output terminal 106i of the reference voltage circuit 106.
The non-inverting input terminal (+) is connected to the resistor 119.
The inverting output terminal 124c is connected to the connection point between the capacitor 120 and the window comparator 1.
07 gate input terminal G107f.

125, 126, and 127 are capacitors, resistors, and inverters that constitute a differential circuit, one end of the capacitor 125 is connected to the output terminal 124a of the comparator 124, and one end of the resistor 126 is grounded. 128 is a current amplification circuit whose input terminal is connected to the output terminal of the inverter 127 and whose output terminal is connected to one end of the electromagnet 115. 12
9 is a NAND gate whose input terminals are connected to non-inverting output terminals 113b and 124b of comparators 113 and 124, respectively. 130, 131, and 132 are capacitors, resistors, and inverters that constitute a differential circuit, one end of the capacitor 130 is connected to the output terminal of the NAND gate 129, and the resistor 1
One end of the battery 31 is connected to the (+) pole of the power battery 101 via a power switch 102. 133 is
The SCR has a gate connected to the output terminal of the inverter 132 and grounded via a resistor 134, and a cathode grounded. Reference numeral 135 denotes an electroflash trigger circuit, which is connected between the anode and cathode of the SCR 133.

Next, the operation of this embodiment will be explained using the shutter mechanism shown in FIGS. 1 to 5 and the shutter control circuit shown in FIG. 8.

First, the warning operation will be described.

When the release plate 2 is pushed down against the tension of the spring 3, the power switch 10 is turned off by the displacement of the pin 2d.
2 is closed and voltage is supplied to each part of the circuit.
At this time, the light receiving element 103 is irradiated with field light passing through the light receiving window 1b and the exposure warning information introduction opening 14e, so a photocurrent i is generated and is amplified by the amplifier circuit 104. . In the amplifier circuit 104, a logarithmic compression diode 105 is connected between the output terminal and the inverting input terminal (-) and feedback is applied, so that the output terminal receives a photocurrent i.
A compressed voltage proportional to the logarithm of is generated, and this voltage is applied to the inverting input terminal (-) 107a of the window comparator 107. Here, this voltage is applied to the output terminal 106a of the reference voltage circuit 106.
If the voltage is higher than the high-intensity warning reference voltage given to the non-inverting input terminal (+) 107b from the output terminal 106b, only the LED 108 connected to the output terminal 107d lights up, and the voltage is changed from the output terminal 106b to the non-inverting input terminal (+) 107c. If the voltage is lower than the reference voltage for low brightness warning given to
Both 108 and 109 do not light up. Note that the low brightness warning operation signal is sent to the window comparator 107.
It is designed to be reversed inside the .

Next, let's talk about automatic shooting. In this case, the switch 122 is closed by a switching member for automatic photography and self-timer photography (not shown), and a resistor 123 with a small value is connected in parallel to the resistor 119, making the combined resistance small. .

First, the switch 112 is closed, the inverting input terminal (-) of the comparator 113 is at the (+) pole level of the power supply battery 101, and the output terminal 113a is at the (+) pole level of the power supply battery 101.
are placed at the "L" level, so the electromagnet 115 is excited from the time the power switch 102 is closed, but its current is limited by the resistor 114. Therefore, the iron piece lever 15
7 is held in the state shown in FIG. 1 without being attracted to the electromagnet 117. When the release lever 2 is further pushed down from the warning operation stage, the bend 2c is removed from the bend 3c of the leaf spring member 6. As a result, the closing drive plate 4 on which the leaf spring member 6 is mounted is moved to the right by the tension of the spring 5. Then, the drive plate 4
As shown in the figure, the hook 4c is attached to the timer lever 22.
It is temporarily stopped by being locked to the bend 22a of.

On the other hand, the switch 121 is opened due to the displacement of the pin 4i as the closing drive plate 4 moves to the right. Therefore, capacitor 120 starts charging via resistors 119 and 123. Comparator 124
Since the combined resistance value is small, capacitor 1
The potential of the non-inverting input terminal (+) to which the charging voltage of 20 is applied is the potential of the inverting input terminal (-) to which the output terminal 106i of the reference voltage circuit 106 is applied.
The potential immediately becomes higher than that of the output terminal 124a and is inverted, and the output terminal 124a becomes the "H" level.

As a result, the capacitor 125 in the differentiating circuit
A positive differential pulse is generated at the connection point of the resistor 126 and a negative pulse is generated at the output terminal of the inverter 127, and therefore, via the current amplification circuit 128,
A negative pulse is applied to one end of the electromagnet 115, and although a small current had been flowing through the electromagnet 115 until then, a large current was instantaneously passed through the electromagnet 115, and the magnetic force increased to attract the iron piece 17 (note that this After the suction operation, the electromagnet 115 is able to attract and hold the iron piece 17, although the pulse disappears and the energization becomes a minute current again.)The iron piece lever 15 and the timer lever 22
Since the arm is rotated to the right against the tension of the spring 23, the bend 15a is placed within the locus of movement of the arm 4d, and the bend 22a is removed from the hook 4c.

Therefore, the closing drive plate 4 immediately moves to the right again, and the arm 4d moves to the iron piece lever 15, as shown in FIG.
However, in the process up to that point, the slope 4f
pushes the pin 19a to place it on the flat surface 4g, rotates the hold lever 19 to the left while resisting the tension of the spring 20, and charges the iron piece spring 21. Further, from the point in time in FIG. 2, the leaf spring member 6 is in a state where the bend 6c faces within the return locus of the bend 2c of the release lever 2 and prevents the release lever 2 from returning, thus maintaining the closed state of the power switch 102. do. on the other hand,
The bend 6d pushes the bend 7a' to turn the shutter release lever 7 to the left against the tension of the spring 9. As the lever 7 is rotated to the left, the arm 7c is removed from the arm 10a, so the opening/closing lever 10 is rotated to the left by the tension of the spring 13, and the shutter blade 1 is rotated by the pins 10d and 10e.
4 to the right (other shutter blades not shown are to the left), and the switch 112 is opened by displacing the pin 10f. Shutter blade 14
As the light-receiving element 103 moves, the aperture 14e first displaces and temporarily blocks the light-receiving window 1b, and since the switch 112 is already open at this point, the capacitor 110 is charged by the current corresponding to the dark current of the light-receiving element 103. will be started. Subsequently, the exposure information introduction opening 14f starts opening the light receiving window 1b first, and a little later the shutter opening 14d opens the exposure opening 1a. Here, the so-called mechanical delay is corrected by charging the capacitor 110 due to the dark current and the prior opening of the light receiving window 1b. Then, in response to the increase in the aperture 14f that is linked to the increase in the shutter aperture 14d, the light irradiating the light receiving element 103 gradually increases, and a current proportional to the photocurrent flows through the transistor 111.
, the capacitor 110 is further charged, and the potential at the inverting input terminal (-) of the comparator 113 gradually decreases.

Here, when the field light is doubled, the photocurrent is doubled, and when the field light is quadrupled, the photocurrent is quadrupled, so the so-called gamma characteristic is "1". When an element is used, the collector current of the transistor 111 is proportional to the photocurrent, so charging the capacitor 110 means integrating the amount of light. Furthermore, since the apertures 14d and 14f are formed on the same member and have substantially similar shapes, it can be said that the integrated amount of photocurrent and the amount of exposure on the image plane are in a directly proportional relationship. Therefore, a constant potential is applied to the non-inverting input terminal (+) of the comparator 113 in the reference voltage circuit 10.
When applied from the output terminal 106c of No. 6, this potential provides a reference for a constant image plane exposure amount, and the exposure amount can be controlled by comparison with the potential corresponding to the integrated amount of photocurrent. Then, as the capacitor 110 is charged, the potential of the inverting input terminal (-) becomes lower than the potential of the non-inverting input terminal (+), the comparator 113 is inverted and the output terminal 113a becomes "H" level. Therefore, the electromagnet 115 is demagnetized. As a result, the iron piece lever 15 is rotated to the left by the charged iron piece spring 21, and the bend 15a is removed from the arm 4d. Therefore, the closing drive lever 4 is further moved to the right by the tension of the spring 5, as shown in FIG. By this movement to the right, the arm 4e first contacts the conductive ring 12 and rotates the opening/closing lever 10 to the right against the tension of the spring 13.
From the middle, a non-conductive protrusion 1 replaces the conductive ring 12.
0c and rotate the opening/closing lever 10 to the right to the final range. Therefore, the shutter blade 14 closes the exposure aperture 1a during the opening of the exposure aperture 1a by the aperture 14d or from the fully open state, corresponding to the timing when the conductive ring 12 is pushed by the arm 4e according to the field light. Close. Further, since the switch 112 is pushed by the pin 10f and closed, the charge in the capacitor 110 is discharged. Furthermore, since the bend 6c of the leaf spring member 6 is removed from the bend 2c, the release lever 2 returns upward due to the tension of the spring 3, and the power switch 102 is opened by the pin 2d. On the other hand, since the bend 6d separates from the bend 7a', the shutter release lever 7 rotates clockwise due to the tension of the spring 9 until the arm 7a abuts the pin 1f, and the arm 7c moves within the left rotation trajectory of the arm 10a of the opening/closing lever 10. Coming. Moreover, the timer lever 22 is rotated to the left due to the tension of the spring 23 due to the displacement of the bending portion 15c accompanying the left rotation of the iron piece lever 15 described above.

Next, in the case of self-timer photography, for example, the dial is set to the self-timer position and the switch 122 is opened. As a result, the low resistor 123 having a small value is disconnected, and only the resistor 119 is connected to the capacitor 120.

Therefore, as the above-mentioned closing drive plate 4 moves until it is once locked with the timer lever 22, the pin 4i
When the switch 121 is opened due to the displacement of the capacitor 120, charging of the capacitor 120 starts via the resistor 119. Then, as the charging of the capacitor 120 progresses, the comparator 124 is inverted in the same manner as described above after, for example, 10 seconds as a self-timer operation. The subsequent operation is similar to that described above.

The shutter mechanism is set by moving the closing drive plate 4 to the left against the tension of the spring 5. That is, during this leftward movement process, the leaf spring member 6 overcomes the bend 2c of the release lever 2 on the slope 6c' of the bend 6c, as shown in FIG.
The slope 6d' of the other bend 6d overcomes the bend 7a' of the shutter release lever 7, and after overrunning, the bend 6c returns and engages with the bend 2c. On the other hand, due to the return of the closing drive plate 4, the pin 19a is moved from the flat surface 4.
g. Since the slope 4f comes off, hold the hold lever 19.
rotates to the right along with the iron piece lever 15 due to the tension of the spring 20, the bend 15a faces within the locus of movement of the arm 4d, and the iron piece 17 comes into contact with the electromagnet 115. Further, as the closing drive plate 4 moves, the timer lever 22 further rotates to the left, so that the bend 22a faces within the movement trajectory of the hook 4c, and the switch 121 is closed by the displacement of the pin 4i, and the capacitor 120 is closed. Charge is discharged. As a result, all the members are
Return to the state shown in the figure.

In each of the above operations, the shutter blade 14
Immediately before the opening operation, the light receiving element 103 is temporarily shielded from field light. This state is the same as the low brightness warning, but due to the previous inversion of the comparator 124, the inverted output terminal 124c becomes "L" level, and this signal is given to the gate input terminal G107f of the window comparator 107. Therefore, the output terminal 107d of the comparator 107,
107e are both placed at the "H" level, therefore,
LEDs 108 and 109 are no longer able to light up.

Therefore, if you perform self-timer photography under brightness conditions where LED 108 or 109 lights up, the LED 108 or 109 will turn on.
The turning off of the light at 9 also indicates the transition from the end of the self-timer operation to the shutter release.

Note that the shutter mechanism of this embodiment allows daytime synchronized photography. That is, the arm 4e of the closing drive plate 4 and the conductive ring 1 on the opening/closing lever 10
2 constitute a synchro switch, so that the opening/closing lever 10 is sufficiently rotated to the left so as to fully open the shutter blade 14, and the conductive ring 12 moves toward the arm 4e.
or when the arm 4e contacts the conductive ring 12 in order to close the shutter blade 14 from the middle of opening, the synchro switch is closed and the flash device emits light at the respective maximum opening point. . However, as shown in FIG. 4, at the final point of the closing operation, the arm 4e is separated from the conductive ring 12 and engages the non-conductive protrusion 10c, so that the flashing device does not erroneously emit light.

The shutter control circuit of this embodiment also incorporates an electrical synchro switch. That is, in each of the above operations, when the comparator 124 is inverted, one input terminal of the NAND gate 129 is set to "H" by the non-inverted output terminal 124b.
When the comparator 113 is inverted at the time when the shutter blade is closed and the shutter blade is closed, the non-inverted output terminal 113b
As a result, the other input terminals also become "H" level, and as a result, the gate is closed and the output terminal becomes "L" level. Therefore, the SCR 133 becomes conductive when a positive differential pulse is applied to its gate by the differentiating circuit, and the trigger circuit 135 is driven in synchronization with the maximum opening time of the shutter blade 14 to cause the electroflash to emit light.

Furthermore, resistors 119 and 123 during automatic shooting
Although the delay time caused by This has an effect that can be used to absorb the adjustment mechanism's adjustment when applied to a camera equipped with such a device.

Next, a self-timer mechanism in which the self-timer mechanism is reset after one exposure operation will be described with reference to FIGS. 6 and 7. A pin 1j is further planted in the shutter plate 1, and a timer lever 22
Further, a protrusion 22c is formed therein. Reference numeral 24 designates a timer set lever pivotally connected to a shaft 25, in which a pin 24a for opening and closing the switch 122 and a set pin 24b are embedded, forming a long groove 24c.
Reference numeral 26 designates a timer reset lever pivotally attached to a shaft 27, which is fitted with a long groove 24c and has a pin 26a embedded therein that can push the protrusion 22c, and which engages with the back of the bend 15c of the iron piece lever 15. arm 26b
A spring 28, which is stronger than the spring 33 (not shown), provides dextrorotation until the arm 26b comes into contact with the pin 1j. FIG. 6 shows the self-timer set state. In order to end the self-timer operation, when the iron piece 17 is attracted to the electromagnet 115 and the iron piece lever 15 is moved to the right end, the iron piece lever 15 is bent.
5c is removed from the arm 26b, the reset lever 26 is rotated to the right by the tension of the spring 28, and the pin 26a causes the set lever 24 to be rotated to the left, and the protrusion 22c is pushed to release the timer lever 2.
2 is rotated to the right against the tension of a spring 23 (not shown). As a result, the state shown in Fig. 7 is reached, and the pin 24
a is retreated and the switch 122 is closed,
The bending 22a of the timer lever 22 is the closing drive plate 4.
The hook 4c is held at a position away from the movement trajectory of the hook 4c.

The self-timer mechanism is set by rotating the set lever 24 to the right from the state shown in FIG. 7 by operating the pin 24b by a set member (not shown). That is, the reset lever 26 is rotated to the left against the tension of the spring 28 by the right rotation of the set lever 24, and the back of the arm 26b engages the side surface of the bend 15c. When this is overcome, the state shown in Fig. 6 is reached and the setting is completed. By incorporating this reset mechanism, when the iron piece lever 15 is attracted to the electromagnet 115, the load for turning the timer lever 22 to the right is reduced, so that the attraction operation becomes more reliable.

Furthermore, in this embodiment, light reception time control and self-timer control are performed using one electromagnet.
Separate electromagnets may also be used.

As described above, according to the present invention, the light-receiving window is opened in advance for the warning operation, and after the light-receiving window is once shielded, the light-receiving diaphragm is also opened in conjunction with the opening of the shutter blades that also serve as aperture blades. In the programmable electric shutter linked to the light-receiving diaphragm, the delay circuit is operated before the transition to the opening operation of the shutter blade, and the warning display circuit is latched to a disabled state by an electric signal indicating the end of the operation. ,
No erroneous display occurs at that stage, and a camera that is extremely convenient to use can be provided.

[Brief explanation of the drawing]

Fig. 1 shows the shutter mechanism in the set state, Fig. 2 shows the stage before transitioning to the opening operation of the shutter blade, Fig. 3 shows the shutter in the open state, Fig. 4 5 is a bottom view showing the relationship between the closing drive plate and the leaf spring member, FIGS. 6 and 7 are views showing the setting and resetting of the self-timer mechanism, and FIG. FIG. 8 is a circuit diagram showing the shutter control circuit. 1... Shutter plate, 1a... Exposure opening, 1b
...Light receiving window, 2...Release lever, 4...Closing drive plate, 4c...Hook, 4d, 4e...Arm, 6...Flat spring member, 7...Shutter release lever, 10...Opening/closing lever, 14...Shutter blade, 14d... Shutter opening, 14e...Exposure warning information introduction opening, 14f
...Exposure information introduction opening, 15...Silver lever, 17
... Iron piece, 19 ... Hold lever, 22 ... Timer lever, 24 ... Timer set lever, 26 ... Timer reset lever, 101 ... Power supply battery, 10
2... Power switch, 103... Light receiving element, 104,
116, 129... Amplifier circuit, 105... Logarithmic compression diode, 106... Reference voltage circuit, 107... Window comparator, 108, 109... LED, 1
13, 124... Comparator, 115... Electromagnet,
125, 126, 127...Capacitors, resistors, inverters forming the differential circuit, 110, 120...
Capacitor, 114, 118, 119, 123...
Resistor, 117... Variable resistor, 111... Logarithmic expansion transistor, 112, 121, 122... Switch.

Claims (1)

[Scope of Claims] 1. A shutter operation in which the light receiving window is opened in advance for the exposure warning operation, and after the light receiving window is once shielded, the light receiving diaphragm is also opened in conjunction with the opening of the shutter blade that also serves as the aperture blade. is a programmable electric shutter linked to a light receiving aperture, which is controlled via an electromagnetic device activated by an electric signal at the end of the operation of a delay circuit activated in response to a release operation, and has a fixed reference voltage. a comparison circuit that generates the electric signal by an output that compares a voltage that changes with the passage of time of the delay circuit and inverts when the voltage change changes from a certain direction and exceeds the reference voltage value; A warning operation disabling circuit that disables the operation of the exposure warning circuit by a signal generated from the comparison circuit at the same timing as the generation of the electric signal, and a delay time of the delay circuit when photographing using a self-timer. A warning error display prevention circuit comprising: delay time switching means for switching between a long time required for shooting and a short time when shooting without using a self-timer;