JPS624693B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a camera malfunction prevention device for preventing malfunctions of an electric shutter camera due to electrical and mechanical failures.

In general, camera shutter control involves moving the leading shutter curtain in response to a release operation, and then running the trailing shutter curtain to close the shutter after a time period corresponding to the brightness of the subject after the shutter is opened. Therefore, when the electromagnet for controlling the shutter trailing curtain does not operate normally because the power supply battery is exhausted or the battery is forgotten to be inserted, proper shutter control cannot be performed. For this reason, in conventional cameras, the power supply voltage is checked, and when the power supply voltage is below a predetermined level, the release is locked and the release operation is disabled.

However, in the case of such conventional cameras, if the power supply voltage is above a predetermined level, the camera will start up, so after startup, electrical failures such as disconnection of the shutter control circuit or poor soldering, or failure of the electromagnet can occur. If the shutter trailing curtain malfunctions due to dirt or foreign matter on the suction surface, deformation or damage to the electromagnetic suction member, etc., the shutter rear curtain may malfunction, making it impossible to properly control the exposure time. I couldn't get a photo of the exposure. Particularly in such cases, even if a malfunction occurs, the shutter etc. will operate normally at first glance, and the camera operator will not be able to recognize that a malfunction has occurred until the film is developed. It had the serious drawback of wasting time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a camera malfunction prevention device that can minimize damage even when an electrical or mechanical failure as described above occurs.

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

FIG. 1 shows the internal mechanism of the camera. Reference numeral 1 denotes a release type electromagnet having a permanent magnet 1a, and the armature 1b of this electromagnet 1 is always attracted by the magnetic force of the permanent magnet 1a. Reference numeral 2 denotes a holding lever of the armature 1b, and this holding lever 2 is biased to rotate counterclockwise by a spring 3. Such an electromagnet is cased by a frame 4 made of a non-magnetic material, and a shielding member 5 is provided on the lower surface of the frame 4 to shield the influence of magnetic force. The shaft 2a of the holding lever 2 protrudes from the frame 4 and has a start lever 6 attached thereto, and a pin 6a that engages with one end of the release lever 7 is implanted at one end of the start lever 6. A pin 6b that engages with a charge plate 8a of the armature is implanted at the other end. Reference numeral 9 denotes an automatic aperture lever that is biased to rotate counterclockwise by a spring 9a, and this automatic aperture lever 9 engages with a pin installed in an aperture drive ring that narrows down the aperture of a photographic lens (not shown). This automatic aperture lever 9 has a spring 10 coaxially attached to it.
An automatic aperture accumulating lever 10, which is biased to rotate clockwise by a lever a, is pivotally mounted. A common lever 11 is pivotally supported at the center of the automatic throttling energy storage lever 10 via a spring 11a. Further, the automatic throttling energy storage lever 10 is locked to a locking lever 12,
This locking lever 12 is engaged with the other end of the release lever 7. Release lever 7 is spring 7
a, and when the release lever 7 rotates clockwise against the spring 7a, the locking lever 12 and the automatic throttling stocking lever 10 are unlocked. It's getting old. The common lever 11 is engaged with the falling portion 9b of the aperture lever 9 at its end, and the common lever 11
has a pin 11c that engages with one end of the automatic aperture return signal lever 13. Reference numeral 14 denotes a stopper pin that restricts the rotation range of the automatic throttle accumulating lever 10. Reference numeral 15 denotes a charge lever, and the charge lever 15 has a pin 15a that can be engaged with one end 10c of the automatic throttle accumulating lever 10, and the charge lever 15 has a pin 16b attached to the intermediate lever 16 provided with the charge plate 8a. It can be rotated clockwise. This intermediate lever 1
6, the hoisting force of the hoisting lever (not shown) is applied to the hoisting shaft 1.
7, the winding cam 18, the roller 19, and the pin 20a of the transmission lever 20 to which the roller 19 is attached.

The other end 10b of the automatic aperture accumulating lever 10 is engaged with a mirror drive lever 21 which is urged to rotate counterclockwise by a spring 21a. A mirror flip-up lever 22 is coaxially connected to the mirror drive lever 21.
is pivotally mounted, and the mirror flip-up lever 22
is engaged with a hook portion 23a of a flip-up locking pawl 23 pivotally attached to the mirror drive lever 21. This locking pawl 23 is urged to rotate clockwise by a spring 23b. The mirror flip-up lever 22 is engaged with a pin 24a implanted in one end of an intermediate lever 24, and the other end of this intermediate lever 24 is engaged with a pin 25a implanted in a mirror receiving plate 25. .
26 is a rotation axis of the mirror receiving plate 25 provided with the mirror 27. Further, the mirror drive lever 21 is provided with a protrusion 21b that engages with one end of the leading curtain locking lever 28, and the other end of this leading curtain locking lever 28 locks the bent piece of the leading curtain release lever 29. There is. The tip of the front curtain release lever 29, which is rotationally biased by a spring 29a, is engaged with a front curtain tensioning lever 30 for starting the shutter front curtain of the shutter mechanism. Reference numeral 31 denotes a trailing curtain signal lever coaxially and independently pivotally connected to the leading curtain locking lever 28, and one end of this trailing curtain signal lever 31 is connected to a signal lever 32 which is activated by a shutter trailing curtain operation end signal of the shutter mechanism. The other end of the mirror return signal lever 33 is engaged with one end of the mirror return signal lever 33. This mirror return signal lever 33
A pin 33a planted in the center of the mirror engages with the other end of the flip-up locking pawl 23, and the other end of the mirror return signal lever 33 engages with the other end of the automatic aperture return signal lever 13. are doing. Reference numeral 34 denotes a suction type trailing curtain control electromagnet, and the armature 34a of this electromagnet 34 is attached to a trailing curtain tensioning lever 35, and this trailing curtain tensioning lever 35 separates the armature 34a from the electromagnet 34 by a spring 36. It is energized as follows. 37 is a shutter rear curtain tensioning camera, and this cam 37 has a protrusion 3 of the tensioning lever 35.
5a is engaged, and this engagement is caused by the tension lever 35
It is designed to be released when rotated by a spring 36. An armature set lever 39 is attached to the tension lever 35 and is capable of coming into contact with the front curtain of the mirror drive lever 21. SW4
is an abnormality detection switch that is opened and closed in conjunction with the rotation of the tension lever 35. Reference numeral 40 denotes a front curtain master gear of the shutter, and a pin 40a that engages with the notch 30a of the front curtain tensioning lever 30 is implanted on the master gear 40. 41 is a rear curtain master gear of the shutter;
A pin 41a is implanted in the pin 41a. A charge interlocking gear 42 charges the shutter via a winding lever (not shown), and a charge gear 43 meshes with the charge interlocking gear 42 for charging the shutter leading curtain and the shutter trailing curtain. Reference numeral 44 denotes a shutter leading curtain pinion fixed to the leading ribbon shaft 45, and the pinion 44 meshes with the leading master gear 40. In addition, the leading ribbon shaft 45
Further, two leading curtain rollers 46 and 47 are fixedly attached to the leading curtain rollers 46 and 47, respectively, around which leading ribbon ribbons 48 and 49 are wound. Reference numeral 50 denotes a trailing curtain pinion of the shutter that meshes with the trailing curtain master gear 41, and the trailing curtain pinion 50 is fixed to the trailing curtain drum shaft 51. Further, a trailing curtain drum 52 on which a trailing curtain 53 of the shutter is wound is further fixed to the trailing curtain drum shaft 51, and a shaft 52 is attached above the trailing curtain drum 52 to guide the leading ribbon 48. A leading curtain guide roller 54 is rotatably supported on a shaft, and a roller 55 similar to the roller 54 is provided below the trailing curtain drum 52. Note that the end of the shaft 51 is fixed to the trailing curtain tensioning cam 37. 56 is a spring that applies a clockwise biasing force to the front curtain tensioning lever 30, SW3 is a count start switch for controlling exposure time, and the switch SW3 is a movable contact piece SW3a.
and a grounded earth pin SW3b. Note that the movable contact piece SW3a is normally press-fitted and engaged with the ground pin SW3b. Here, FIG. 2 shows the exposure control circuit of the camera shown in FIG.
1 to the power supply terminal Vcc for supplying power to each circuit. 62 and 63 are resistors forming a bias circuit for the transistor 61, and their connection point is connected to the base of the transistor 61. 64
is a normally open power supply start switch that is linked to a shutter release button (not shown) and is closed when pressed to the first stage; one end of the switch 64 is connected to the power supply circuit forming switch via the resistor 63 The base of the transistor 61 is connected to the base of the transistor 61. Reference numeral 65 denotes a normally open switch that is linked to the release button and closes when pressed to the second stage. One end of the switch 65 is connected to the first input terminal of a NAND gate 66 forming a latch circuit and an inverter 69 to be described later. connected to the input end of the 67 is a NAND gate that forms a latch circuit together with the NAND gate 66 to maintain the power supply state of the transistor 61 of the power supply circuit;
The output terminal of the gate 67 is connected to the second input terminal of the NAND gate 66. Reference numeral 68 denotes an NPN transistor forming an output circuit of the latch circuit, and the transistor 68 is connected in parallel to the power supply start switch 64. 71 is a resistor connected to the base of the transistor 68; 72 and 73 are first resistors;
The output terminal of one NAND gate 72 is connected to the third input terminal of AND gate 70, and the output terminal of one NAND gate 72 is connected to the third input terminal of AND gate 70. Connected to one input terminal. Further, the output terminal of the AND gate 70 is connected to an npn for exciting the release electromagnet 1 via a monostable multivibrator (hereinafter referred to as mono-multi).
Connected to the base of transistor 75. 80～
85 is each element forming an abnormal operation display circuit;
1 is a NAND gate having a first input terminal connected to the output terminal of the latch circuit and a second input terminal connected to the output terminal of the trailing curtain running detection circuit via an inverter 80, 82 a resistor, and 83 a light emitting diode. (hereinafter abbreviated as LED) 84 is a PNP transistor for driving the LED, and 85 is a current limiting resistor connected between the anode of the LED 84 and the power supply terminal Vcc. 86 to 90 are each element forming the shutter trailing curtain running completion detection circuit described above, 86 is a current limiting resistor connected to the collector of the NPN transistor 88, and 87 is used together with a capacitor 89 to determine the lighting time of the abnormal operation display LED 84. A resistor 90 forming a timing circuit is a switch for detecting the completion of running of the shutter rear curtain 53, which is closed in conjunction with the completion of the advance of the rear curtain 53 and opened in conjunction with the completion of winding of the film. Ru. Further, one end of the switch 90 is connected to the second input end of the AND gate 70. 3
4, SW3 and 91 to 96 are elements forming an exposure time control circuit; SW3 is a count start switch shown in the first figure that is opened in conjunction with the movement of the front shutter curtain; Capacitor 9 of the time-fixed circuit that determines the exposure time as shown in
2 are connected in parallel. 93 is the capacitor 92
Resistors 94 and 95, which together form the time-fixing circuit, are resistors for forming a voltage dividing circuit, and their connection point is connected to the input terminal (+) of a comparator 96. 34 is the first
This is the illustrated trailing curtain control magnet. SW4 and 97 to 100 are elements forming a circuit that detects an abnormality and prohibits resetting of the power supply holding latch circuit, SW4 is the abnormality detection switch shown in the first diagram, and 97, 98, and 99 are the power supply holding latch circuits. Two NAND gates and an npn transistor form a reset inhibit circuit for inhibiting the reset of the latch circuit. 100 is a current limiting resistor connected to Vcc. Reference numeral 101 is a NAND gate for resetting the latch circuit for holding the power supply circuit. In the case of this embodiment, a logic circuit formed of transistors, a so-called TTL circuit, is used as each gate.

Next, the operation of the camera according to the above configuration will be explained, but first, a case where the camera operates normally will be explained.

When the release button (not shown) is pressed in the winding completed state, the power supply start switch 64 is closed in the first stage operation, a forward bias is applied to the base of the transistor 61, and the transistor 61
turns on. Therefore, each circuit is supplied with power from the battery 60 via the power supply terminal Vcc.

Furthermore, when the transistor 61 turns on, a low level (hereinafter abbreviated as "0") signal is momentarily output from the power up clear circuit (not shown), so that the third input terminal of the NAND gate 67 The PUC and the second input terminal PUC of the NAND gate 98 become "0". Therefore, the latch circuit for holding the power supply circuit and the reset prohibition circuit are reset in synchronization with the closing of the switch 64, the NAND gates 66 and 97 are set to "0", and the NAND gates 67 and 98 are set to high level (hereinafter abbreviated as "1"). ). When the power supply holding latch circuit is reset as described above, "0" is applied to the first input terminal of the NAND gate 72 of the control circuit, so the control circuit is set and the output of the NAND gate 72 is "0". 1”.

When the switch 65 is closed by further pressing the release button, the first input terminal of the NAND gate 66 of the latch circuit for holding the power supply circuit becomes "0".
Therefore, the latch circuit is set. Therefore, "1" is applied to the base of the transistor 68, and the transistor 68 is turned on. Then, when the switches 64 and 65 are opened by releasing the press of the release button, the first input terminal of the NAND gate 66 of the latch circuit for holding the power supply circuit becomes "1", but the second input terminal thereof becomes "1". Since "0" continues to be applied by the output of switch 67, the latch circuit remains set and transistor 68 is turned on in synchronization with the opening of switch 65. Therefore, transistor 6
1 is maintained in the power supply state by a power supply circuit holding latch circuit.

On the other hand, when the switch 65 is closed as described above by pressing the release button, the output of the inverter 69 is also inverted from "0" to "1", so the first input terminal of the AND gate 70 becomes "1". to be reversed. Also, at this point, the switch 90 has been opened due to the completion of winding of the film, so the AND gate 7
The second input terminal of 0 is "1", and the third input terminal of AND gate 70 is also "1" as mentioned above.
It is becoming.

Therefore, when the switch 65 is closed in conjunction with the pressing of the release button, the latch circuit for holding the power supply circuit is set as described above, and the output of the AND gate 70 for starting the release electromagnet becomes "1". ”, and the coil of the release electromagnet 1 becomes excited via the monomulti 74 and the transistor 75. For this reason, armature 1b has spring 3
As the holding lever rotates, the start lever 6, which is integrated with it, also rotates, so the release lever 7 rotates clockwise against the spring 7a and locks. The lock between the lever 12 and the automatic throttle accumulating lever 10 is released. Therefore, the automatic throttle accumulating lever 10 is rotated clockwise by the spring 10a, and the automatic throttle lever 9 is rotated clockwise via the common lever 11. This narrows down the photographic lens. Further, the other end 10b of the automatic aperture storage lever 10 is the mirror drive lever 21.
The mirror drive lever 21 is rotated counterclockwise by the spring 21a since the mirror drive lever 21 is rotated in the direction further away from the mirror drive lever 21.
Therefore, the tip of the mirror drive lever 21 releases the hold on the armature set lever 39. Further, a mirror flip-up lever 22 coaxial with the mirror drive lever 21 is locked to a hook portion 23a of a locking pawl 23, so that they rotate together. As a result, the intermediate lever 24 rotates counterclockwise, and the mirror receiving plate 25 is flipped upward about the shaft 26. Furthermore, the counterclockwise rotation of the mirror drive lever 21 causes the front curtain locking lever 28 to rotate clockwise and disengage from the bent piece of the front curtain release lever 29. Therefore, the front curtain release lever 29 is rotated clockwise by the spring 29a, and the front curtain tensioning lever 30 is rotated in the direction of arrow A, so that the notch 30a of the front curtain tensioning lever 30 and the pin 40a are engaged with each other. The engagement is released, the front curtain master gear 40 is rotated counterclockwise by the shutter front curtain spring (not shown), and the front curtain pinion 44 is rotated counterclockwise.
The front curtain shutter ribbons 48 and 49 start running through. In synchronization with this movement of the front shutter curtain, the insulating pin b of the front curtain tensioning lever 30 pushes out the contact piece SW3a of the count switch SW3, so the contact piece
SW3a separates from ground pin SW3b, and count switch SW3 becomes open. As a result, the capacitor 92 is charged via the variable resistor 93, and the output of the comparator 96 changes from "0" to "1" after a time determined by the values of the variable resistor 93 and the capacitor 92.
Then, the trailing curtain control electromagnet 34 is de-energized. Therefore, the trailing curtain tensioning lever 35 to which the armature 34a is attached is rotated counterclockwise by the spring 36, so that the engagement with the trailing curtain tensioning cam 37 is released, and the trailing curtain master gear 41 and the trailing curtain pinion 50 are disengaged from each other. A rear shutter curtain 53 runs through the shutter. At this point, the switch SW4 is turned on from off, and a high level voltage between the terminals of the time-limiting capacitor 92 is applied to the first input terminal of the NAND gate 97. Since it is set to "1" for output, the reset prohibition circuit is not set and its transistor 99 remains off. When the transistor 99 remains off, the voltage between both terminals of the capacitor 92, that is, the voltage corresponding to a high level, is applied to the second input terminal of the NAND gate 101 for resetting the latch circuit for holding the power supply circuit.

After that, the trailing curtain 53 completes running and the switch 90
When the transistor 88 turns on from off, the transistor 88 turns on for a time determined by the resistor 87 and the capacitor 89, so that the reset NAND gate 101
is inverted from "1" to "0" in synchronization with the closing of the switch 90, the latch circuit for holding the power supply circuit is reset, the output of the NAND gate 66 becomes "0", and the transistor 68 is turned off. Therefore, the power supply transistor 61 is also turned off, and the power supply to each circuit is cut off. On the other hand, shutter curtain 5
The signal lever 32 is rotated in the direction of arrow B in response to the shutter operation end signal upon completion of travel in step 3, and the trailing curtain signal lever 31 is rotated counterclockwise. Therefore, the mirror return signal lever 33 rotates clockwise, and the locking pawl 23 rotates counterclockwise to release the engagement with the mirror flip-up locking lever 22. As a result, the mirror receiving plate 25 is released from the raised state and returned to the lowered position by a spring (not shown). Further, since the other end of the mirror return signal lever 33 rotates the automatic aperture return signal lever 13 counterclockwise, the common lever 11 rotates counterclockwise to release the engagement with the automatic aperture lever 9. Therefore, the automatic aperture lever 9 is rotated counterclockwise by the spring 9a to return to its original position, and the aperture of the photographic lens is opened to complete photographing. To wind the film after shooting, when the winding lever is raised, the winding shaft 17 and charge cam 18 are rotated in the direction of arrow C, and the above-mentioned shutter is rotated through the charge interlocking gear 42 and charge gear 43. The mechanism is charged and the film is wound.
At this time, the rotation of the charge cam 18 is controlled by the roller 19,
It is transmitted to the intermediate lever 16 via the pin 20a of the transmission lever 20. As a result, the intermediate lever 16 is rotated clockwise, the pin 6b is pressed by the charge plate 8a, the start lever 6 is rotated, and the armature 1b of the holding lever 2 is attracted to the electromagnet 1. At this time, the armature 1b is attracted to the release electromagnet 1 by the magnetic flux of the permanent magnet 1a. Further, since the rotation of the start lever 6 releases the locking of the release lever 7 by the pin 6a, the release lever 7 is rotated counterclockwise by the spring 7a. Since the clockwise rotation of the intermediate lever 16 rotates the charge lever 15 clockwise,
The automatic throttle accumulating lever 10 is rotated counterclockwise against the spring 10a. This rotation of the automatic aperture accumulating lever 10 causes the locking lever 12 to be locked, and also rotates the mirror drive lever 21 clockwise against the spring 21a. This rotation of the mirror drive lever 21 locks the mirror flip-up lever 22 to the locking pawl 22 and also causes the front curtain release lever 29 to lock the mirror flip-up lever 22 to the locking claw 22.
is locked to the leading curtain locking lever 28. The rotation of the mirror drive lever 21 presses and holds the armature set lever 39, and the protrusion 35a of the trailing curtain tensioning lever 35 engages with the shutter trailing curtain tensioning cam 37, causing the armature 34a to engage the electromagnet 34. It returns to the same state as the state in which it was adsorbed.

Next, a case will be described in which the power supply voltage is sufficient to drive the electromagnet 1, but a failure has occurred in other electric circuits or mechanical elements. This electrical circuit failure is when a signal is not output from the trailing curtain control circuit due to damage to an element in the trailing curtain control circuit, poor soldering, etc., or faulty soldering or disconnection of the terminal of the trailing curtain control electromagnet 34. It's time to be. Mechanical failures include dirt on the attracting surface of the trailing curtain control electromagnet 34, contamination of foreign matter, insufficient setting of the armature 34a, deformation or damage of the electromagnet 34 and the armature 34a, and the attraction force of the electromagnet 34 is insufficient to tighten the trailing curtain. This is a case where the spring pressure of the spring 36 that biases the constant lever 35 is greater and the armature 34 is not attracted to the electromagnet 34.

First, when the release button is pressed, the switch 64 is closed in the first step, and power supply voltage is applied to each circuit at the same time as described above. At this time, the control circuit is also set in synchronization with the signal output from the power up clear circuit as described above, and the output of the NAND gate 72 becomes "1". When the release button is further pressed, the switch 6
When the switch 5 is closed, the switch 90 is opened due to the completion of winding, so in synchronization with the closing of the switch 65, the output of the AND gate 70 becomes "1" at the same time as the normal operation, and the mono The coil of the release electromagnet 1 is energized via the multi-74 transistor 75, and the magnetic flux of the permanent magnet is canceled out by the magnetic flux generated by the excitation of the coil, and the armature 1
The suction of b is cut off. Therefore, the holding lever 2 is rotated by the spring 3. On the other hand, as described above, when the transistor 75 is turned on, the second input terminal of the NAND gate 73 of the control circuit becomes "0", so the control circuit is immediately reset to enable the next activation of the release electromagnet 1. Ru. Then, when the holding lever 2 is rotated again by the spring 3,
Since the start lever 6 also rotates together with this, the release lever 7 rotates clockwise against the spring 7a, and the locking lever 12 and the automatic aperture storage lever 10
Release the lock. Therefore, the automatic throttle accumulating lever 10 is rotated clockwise by the spring 10a, and the automatic throttle lever 9 is rotated clockwise via the common lever 11. This narrows down the aperture of the photographic lens. Also, since the other end 10b of the automatic aperture storage lever 10 rotates in a direction away from the mirror drive lever 21, the mirror drive lever 21 is moved by the spring 2.
1a starts rotation in the counterclockwise direction, and the tip of the lever 21 releases the hold on the armature set lever 39. At this time, because the armature 34a is not attracted to the electromagnet 34 due to the above-mentioned electrical failure or mechanical failure, the trailing blade tensioning lever 35 is rotated by the spring 36 to close the switch SW4. At this point, since the leading shutter curtain has not started running, the count switch SW3 is closed. Therefore, when the abnormality detection switch SW4 is closed as described above, the abnormal operation detection switch SW4 is closed as described above.
The first input terminal of the NAND gate 97 of the reset inhibit circuit connected to the capacitor 92 becomes the voltage across the capacitor 92, that is, "0". Therefore, the reset prohibition circuit is set, the output of the NAND gate 97 becomes "1", and the transistor 99 is enabled to turn on. Further, since the mirror drive lever 21 rotates the coaxial mirror flip-up lever 22 integrally, the intermediate lever 24 rotates counterclockwise to flip the mirror receiving plate 25 upward about the shaft 26. Furthermore, the counterclockwise rotation of the mirror drive lever 21 causes the front curtain locking lever 28 to rotate clockwise and disengage from the bent piece of the front curtain release lever 29. For this reason, the front curtain release lever 29 has a spring 29
a to rotate clockwise to release the leading curtain tensioning lever 30.
is rotated in the direction of the arrow, so the leading shutter curtain of the shutter mechanism runs in the same manner as described above.

However, since the rear shutter curtain is not locked by the tension lever 35, it runs at the same time as the front shutter curtain, and the shutter is not released.
No film exposure is performed.

Then, when the switch 90 is closed upon completion of the travel of the rear shutter curtain 53, the transistor 88 is turned off as described above, and the reset NAND gate 1 is turned off.
The first input terminal of 01 changes from "0" to "1".
However, at this point, the capacitor 9 for exposure time control, which starts charging as the leading curtain runs,
The transistor 99 is turned on by the charging voltage of 2,
In addition, since the second input terminal of the reset NAND gate 101 is set to "0", the first input terminal of the NAND gate 101 is inverted from "0" to "1" in synchronization with the closing of the switch 90 as described above. However, the latch circuit for holding the power supply circuit is not reset, and the output of the NAND gate 66 remains at "1".
Therefore, the transistor 68 remains on, and the power supply transistor 61 continues to supply power to each circuit.

In addition, the latch circuit for holding the power supply circuit continues to be set for the above-mentioned reason, and its NAND gate 66
Since the output of the NAND gate 81 is kept at "1", when the transistor 88 is turned on due to completion of running of the trailing curtain as described above, the output of the NAND gate 81 becomes "0", the transistor 83 is turned on, and the LED 8 is turned on.
4 lights up to indicate to the photographer that an abnormality has occurred. Note that this warning display will occur after a certain period of time determined by the values of the resistor 87 and capacitor 89.
8 is turned on again, it is automatically stopped. Even though the LED 84 lights up to warn you of a malfunction, if you wind the camera as described above and press the release button again, the switch 64 will close. Since the transistor 61 is maintained in the power supply state by the latch circuit for holding the power supply circuit, the transistor 61
No change occurs in 1. Then, since the transistor 61 continues to be on, the power up clear signal is not outputted either. Therefore, the output of the NAND gate 66 of the latch circuit for holding the power supply circuit maintains the "1" state, and the control circuit, which was reset by turning on the transistor 75 during the previous photographing process, maintains the reset state. , the output of the NAND gate 72 maintains the state of "0". Thereafter, when the switch 65 is closed by further pressing the release button, "1" is added to the first input terminal of the AND gate 70 via the inverter 69; Since “0”, which is the output of the NAND gate 72, is applied to the
maintains the state of "0". Therefore, the coil of the release electromagnet 1 is not excited and the start lever 6 is not operated, so even if the camera release button is pressed as described above, the camera is prohibited from starting.

As explained above, when the rear shutter curtain malfunctions due to circuit breakage or mechanical failure of the electromagnet, the state is memorized in the memory circuit, and the next time the release button is pressed, the shutter curtain malfunctions. Providing a camera malfunction prevention device that prohibits the generation of a release start signal even when the camera is in use, so the photographer can easily determine that the camera is malfunctioning since no shutter operation is performed, and that can minimize wasted film. do.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a camera malfunction prevention device according to an embodiment of the present invention, and FIG. 2 is an electrical control circuit diagram of the device shown in FIG. In the figure, 1... electromagnet for release, 6...
Start lever, 34... Rear curtain control electromagnet,
SW3... Count switch, SW4... Abnormality detection switch, 66, 67... NAND gate forming a latch circuit for holding the power supply circuit, 72, 73...
NAND gate for forming a control circuit, 90... switch for detecting trailing curtain travel, 97, 98... NAND gate for forming a reset prohibition circuit, 99... transistor,
61...Transistor, 101...NAND gate.

Claims (1)

[Scope of Claims] 1. A mirror drive mechanism that rotates a movable mirror to a shooting retreat position in response to a shutter release, a first electromagnet that causes a leading shutter curtain to travel, and a first electromagnet that causes a trailing shutter curtain to travel. In a camera having a second electromagnet for performing the shutter release time, and a timer circuit for setting the shutter release time, the first release start signal is generated in response to the output of the switch activated by pressing the release button. The electromagnetic coil is energized to separate the armature for the shutter front curtain to run.
an electromagnet control circuit that controls the energization of the coil of the second electromagnet to separate the armature to run the rear shutter curtain after a preset time set in the timer circuit has elapsed; and the switch is operated by pressing the release button. Even if the release start signal is not generated, the armature of the second electromagnet is moved to the attraction position in conjunction with the rotation operation of the movable mirror by the mirror drive mechanism to the photography retracted position. Holding that is moved from a holding position to a holding release position that allows the armature to move away from the holding position, and returning from the holding release position to the holding position after the trailing curtain of the shutter runs. member, and after the holding member has been moved to the holding release position and before the set seconds of the timer circuit have elapsed,
a detection circuit for detecting that the armature of the second electromagnet has moved away and the shutter rear curtain has erroneously moved; a memory circuit that maintains the memory state regardless of whether the switch is activated or deactivated when the switch is pressed; and when the detection circuit detects the erroneous running;
warning display means for displaying a warning by operating an electro-optical element based on a timer operation signal for a predetermined time set by a timer circuit; When it is detected that the release start signal is generated, the prohibition circuit is activated to prohibit generation of the release start signal even when the release button is pressed again, and when it is detected that the storage signal is not generated, the prohibition circuit is activated. A camera malfunction prevention device comprising: a control circuit that operates an electromagnet control circuit.