JPH0228512Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a motor control device used in an automatic rewind camera that automatically rewinds photographic film when it stops running. This invention relates to a motor control device that prevents a relay from turning on and rewinding photographic film.

Conventional automatic rewind cameras are equipped with a timer circuit that is reset by the film running signal, and when the photographic film stops running, the forward rotation relay is turned OFF and the reverse rotation relay is turned ON instead. The motor is reversed to automatically rewind the photographic film. As this timer circuit, a combination of a CR time setting circuit and a comparator is usually used.

When the power supply is exhausted and the voltage drops, a large current flows through the motor when it starts rotating, causing the reference voltage of the comparator to drop. Due to this drop in the reference voltage, the comparator is inverted and the forward rotation relay is turned off, even though the capacitor is not charged to a predetermined voltage. When this relay for forward rotation turns OFF, no current flows to the motor, so the reference voltage increases as the power supply voltage recovers.
The comparator returns to "L" again and turns on the forward rotation relay. As a result, the forward rotation relay causes chattering and the motor does not rotate forward.

On the other hand, since the reverse rotation relay turns ON when the forward rotation relay turns OFF, a reverse rotation circuit for the motor is formed. When rewinding the photographic film, the load is small since there is no shutter set, so the motor starts rotating in reverse, and the photographic film is rewound halfway through the photographing process.

Based on the above background, it is an object of the present invention to provide a motor control device that prevents the rewinding of photographic film due to a drop in power supply voltage.

The present invention is characterized in that a resistor is connected in series with the reversing relay to increase the voltage applied to the reversing relay. As a result, when the power supply voltage drops to such a level that the forward rotation relay causes chattering, the reverse rotation relay cannot turn on the relay switch to form a reverse circuit, so the motor will not rotate in reverse.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In FIG. 1, a motor 1 is housed, for example, in a take-up spool (not shown), and is used to wind and rewind photographic film, set a shutter, etc. When forward rotation relay switch S1 is connected to contact a and reverse rotation relay switch S2b, motor 1 and power supply 2 are connected in series, and motor 1 rotates forward to wind the photographic film. Perform the shutter set. Conversely, when the forward rotation relay switch S1 is connected to the contact point b and the reverse rotation relay switch S2 is connected to the contact point a, the motor 1 rotates in the reverse direction to rewind the photographic film.

Frame feed switch S3 connects to contact b and turns OFF when the sprocket (not shown) rotates by a predetermined amount and the photographic film has been fed by one frame.
After the shutter operates and while the photographic film is being fed by one frame, it is connected to contact a and remains in the ON state. Therefore, when winding photographic film, motor 1 rotates when this frame advance switch S3 is turned on, and motor 1 stops when it is turned off.
During this time, the photographic film is wound.

The jump feed switch S4 is connected in parallel with the frame feed switch S2, and is turned ON during the winding of the next frame after the start piece, and turned OFF during the winding of the first frame.
become. This blank feed switch S4 is operated in conjunction with a counter mechanism that displays the number of frames to be photographed. When the jump feed switch S4 is ON, the motor 1 continues to rotate even if the frame feed switch S3 is turned OFF, so the jump feed pieces can be wound up continuously.

A CR time setting circuit consisting of a resistor 3 and a capacitor 4 is connected between the connection point P and the frame advance switch S3. A connection point A between the resistor 3 and the capacitor 4 is connected to the + side input terminal of the comparator 5. One input terminal of this comparator 5 is connected to a connection point B between resistors 6 and 7. These components constitute a forward rotation timer circuit that measures a time t that is shorter than the time T required to wind up one frame of photographic film (see FIG. 2). It is preferable that this time t is a sufficient time to judge the running condition of the photographic film, but in consideration of errors in the film running signal, which will be described later, it is preferable that T/2≦t<T.

A forward rotation relay coil (hereinafter simply referred to as a forward rotation relay) 8 is connected to the output terminal of the comparator 5, and is energized when the output is "L" to change the forward rotation relay switch S1 from contact b to contact a. Switch to rotate motor 1 in the forward direction.

A transistor 9 is connected in parallel to the capacitor 4, and as shown in FIG.
Turn on with the pulse signal to discharge capacitor 4,
Reset the forward rotation timer circuit. This differentiating circuit 10 outputs one or more pulse signals at the falling edge or rising edge of the film running signal from the film running detection switch S5.
The film running detection switch S5 is turned on and off by a plurality of pins provided on a driven sprocket that is rotated by engaging with the perforation of the photographic film, for example. A lamp 11 is connected to the output terminal of the differentiating circuit 10, and the running state of the photographic film is indicated by blinking the lamp 11.

Between the connection point Q and the frame advance switch S3,
A capacitor 12 and a resistor 13 are connected in series, and their connection point is connected to the positive input terminal of a comparator 14. Also, comparator 1
A connection point between resistors 15 and 16 is connected to one side input terminal of 4.

This timer circuit, at the start of frame advance,
It is activated when the frame advance switch S3 is connected to contact a, and the output terminal of the comparator 14 is set to "H".
The time required for reversing from "L" to "L" is delayed by a time sufficient for the forward rotation relay switch S1 to switch from contact B to contact A. In this case, when the forward rotation relay switch S1 is connected to contact a, the timer circuit becomes inactive, so the output terminal of the comparator 14 remains at "H". This also means that in order to rewind the photographic film, the forward rotation relay switch S1 moves away from contact a and contacts b.
It also operates when switching to comparator 1.
4 is delayed, and then the output terminal of the comparator 14 is set to "L" to energize the reversing relay coil (hereinafter simply referred to as the reversing relay) 17, and the reversing relay switch S2 is switched to contact a. Further, this comparator 14 is also used to shut off the reverse rotation relay 17 and stop the motor 1 during reverse rotation when the frame advance switch S3 is turned off after rewinding is completed.

A series circuit of a resistor 18 and a capacitor 19 and a series circuit of resistors 20 and 21 are connected between the anode of the power supply 2 and the connection point P, respectively. The connection point C between the resistor 18 and the capacitor 19 is connected to the positive input terminal of the comparator 22, and the connection point C between the resistor 18 and the capacitor 19 is
Connection point D of 1 is connected to one side input terminal.
This reversal timer circuit is activated when the reversing relay switch S2 is connected to contact a to form a reversing circuit for the motor 1, and the capacitor 19 is continuously charged and the voltage at point C changes to the voltage at point D. The output terminal of the comparator 22 is set to "L" only during the time it takes to rise to the voltage. Note that this time is desirably set to be relatively long in order to completely wrap the leading edge of the photographic film into the cartridge. Said capacitor 1
A transistor 23 is connected in parallel with 9,
It is turned on by the pulse signal of the differentiating circuit 10.

The comparators 14 and 22 are open collectors, and when either one is "L", the reversing relay 17 is energized. Comparator 14
is used to regulate the start and end of energization of the reversing relay 17, and the comparator 22 acts during that time to reverse the motor 1 and rewind the photographic film into the cartridge.

In order to increase the voltage applied to the reversing relay 17, a resistor 24 is connected in series therewith. For example, the power supply/voltage is 3V, the resistance value of motor 1 is 1.4Ω,
When the resistance value of the reversing relay 17 is 12Ω,
The resistance value of the resistor 24 should be about 3Ω.

The rewind switch S6 is used to rewind the photographic film from the middle of shooting, and once it is turned on, the comparators 14 and 22 are activated and the reversing relay 17 is turned on. You can rewind photographic film without having to keep this on.

The delay time t of the forward rotation timer circuit is set to be shorter than one frame, and the film travel signal is obtained in conjunction with a driven sprocket driven by the photographic film, so that the photographic film can be pulled out from the cartridge. Even if the perforation is broken by the drive sprocket when it runs out, the photographic film can be rewound. However, if we do not take into account perforation breakage,
The delay time t may be longer than one frame, and the film travel signal may be obtained in synchronization with the rotation of the drive sprocket.

Next, the operation of the present invention having the above configuration will be explained.

Load photographic film into the camera and press the release button to release the shutter.
Frame advance switch S3 connects to contact a. As a result, the output terminal of the comparator 5 becomes "L", the forward rotation relay 8 is turned on, and the forward rotation relay switch S1 is connected to the contact a. Reversing relay 17
is OFF, so reverse relay switch S2
is connected to contact b. Therefore, motor 1
A normal rotation circuit is formed, current flows through the motor 1 in the direction shown by the solid line, and the motor 1 rotates in the normal direction. Motor 1
pulls out the photographic film from the cartridge, winds it onto the take-up spool, and sets the shutter.

During the winding of the photographic film, the film running detection switch S is operated in conjunction with the driven sprocket, etc.
5 is turned ON eight times for one piece, for example. As shown in detail in FIG. 4, the differentiating circuit 10 outputs a pulse signal at the falling edge of the film running signal, blinks the lamp 11 to display the film running status, and turns on the transistor 9 at a predetermined period. . Since the capacitor 4 is discharged by the transistor 9, the forward rotation timer circuit is reset at regular intervals. Therefore, the output terminal of the comparator 5 remains at "L", and the forward rotation relay 8 is turned off until the frame advance switch S3 is turned OFF.
energize.

During winding of the film frame, the film frame feed switch S4 is activated in conjunction with the counter disc that displays the number of film frames.
is on. As a result, the photographic film frame is wound up and the frame advance switch S3 is turned off.
Even when turned off, comparator 5 remains in operation,
The motor 1 rotates continuously and winds up a total of three free-feeding pieces. Since the jump feed switch S4 is turned OFF during the winding of the first frame, when the frame feed switch S3 is then turned OFF and it is detected that one frame has been wound, the comparator 5 becomes inactive. Its output terminal becomes "H".
This turns off the forward rotation relay 8 and switches the forward rotation relay switch S1 to contact b.
The motor 1 suddenly stops when the electric brake is applied.

If you press the release button after winding up the first frame, the shutter will operate and the first frame will be photographed. When the shutter operates, the frame advance switch S3
turns on, motor 1 rotates forward again and winds up the second piece.

If the cartridge you are using has a 36-shot capacity, you will normally be unable to pull out the photographic film from the cartridge once the 37th frame has been wound. In this case, since the photographic film stops running, no pulse signal is output from the differentiating circuit 10. Since the capacitor 4 is continuously charged, the voltage at point A increases to the voltage at point B after a time t, which is shorter than the time T required to wind up one frame, has elapsed.

As shown in FIG. 3, when time t has elapsed after the film stopped running, the comparator 5 is reversed and its output terminal becomes "H", the forward rotation relay 8 is cut off, and the motor 1 is stopped. . In this case, since the frame advance switch S3 is ON,
When the forward rotation relay switch S1 leaves contact a, the potential at point Q becomes ten. As a result, the comparator 14 becomes operational, and its output terminal becomes "L". When the output terminal of the comparator 14 becomes "L", the reversing relay 17 is energized and the reversing relay switch S2 is switched from contact b to contact a. The motor 1 starts reversing because a reversing circuit is formed, and at the same time, the comparator 22 becomes operational and its output terminal becomes "L".

When the motor 1 starts rotating in reverse, the photographic film wound on the take-up spool is rewound into the cartridge, and at the same time the shutter is set. While the photographic film is being rewound, the transistor 23 is repeatedly turned on and off in response to a pulse signal from the differentiating circuit 10, thereby discharging the capacitor 19. Therefore, since the reversal timer circuit is reset at a predetermined period, the output terminal of the comparator 22 is held at "L".

When the photo film is almost finished rewinding, the perforation will come off the sprocket.
The film running signal is no longer output from the film running detection switch S5. As a result, the differentiating circuit 10 no longer outputs a pulse signal, the lamp 11 stops blinking, and the transistor 23 is turned off. When the capacitor 19 is charged with an approximately constant current and the voltage at point C is charged up to the voltage at point D, the output terminal of the comparator 22 becomes "H". However, since the output terminal of the comparator 14 is set to "L" due to the ON of the frame advance switch S3, the reversal relay 17 is continuously energized. And the frame advance switch S3 is OFF.
Then, since the comparator 14 becomes inactive, its output terminal becomes "H" and the reversing relay 17 is cut off.

When the reversing relay 17 is cut off, the reversing relay switch S2 switches to contact b, so that the motor 1 is electrically braked and then stopped.

For example, a 3V power supply is used as the power supply 2,
Until the voltage drops to 1V, the motor 1 can rotate and the camera mechanism can be set. However, if the power source is consumed and the voltage drops due to use, the load during winding is large, and when the motor 1 attempts to rotate, the power source voltage will drop significantly. Therefore, since the voltage at point B decreases, the comparator 5 is inverted and becomes "H" before the voltage at point A reaches the normal inversion level. As a result, the forward rotation relay 8 is turned off, and the forward rotation circuit of the motor 1 is turned off. Then, since the power supply voltage is restored to its original level, the comparator 5 becomes "L" again, causing chattering.

Since the capacitor 12 is charged while the comparator 5 is chattering, the comparator 14 becomes "L" and the reverse relay 17 is turned on.
Make it. During rewinding, the load on motor 1 is small, so the motor starts reversing.

Therefore, a resistor 24 is connected in series with the reversing relay 17 to increase the voltage to prevent the motor 1 from forming a reversing circuit. That is, when the voltage of the comparator 5 drops to such a level that it causes chattering, the current in the reversing relay 17 becomes small, the magnetic force becomes small, and the reversing relay switch S2 cannot be switched to contact a. As a result, since the motor 1 remains stopped, the photographic film is not rewound from the middle.

In the present invention having the above configuration, a resistor is connected in series with the reversing relay to increase the applied voltage, so that when the voltage drops to such a level that the forward reversing relay causes chattering, a reversing circuit of the motor is formed. This can prevent the photographic film from being rewound from the middle.

Note that relays for forward rotation and relays for reverse rotation may have different voltages, but this is inconvenient in terms of manufacturing and hinders rationalization. Although the present invention requires one extra resistor, it is convenient to handle because the same expensive relay for forward rotation and relay for reverse rotation can be used.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a timing chart during winding, Fig. 3 is a timing chart during rewinding, and Fig. 4 shows the reset state of the forward rotation timer circuit in detail. This is a timing chart. 1...Motor, 8...Relay for forward rotation, 10...
Differential circuit, 17...Relay for reverse rotation, 24...Resistor, S1...Relay switch for forward rotation, S2...Relay switch for reverse rotation, S3...Switch for frame feed, S4...Switch for blank feed, S5... Film travel detection switch, S6... Rewind switch.

Claims (1)

[Scope of utility model registration request] A motor that winds the photographic film during forward rotation and rewinds the photographic film during reverse rotation, a forward rotation timer circuit that determines the film running state at the time of winding based on the presence or absence of a film running signal, and a motor that determines the film running state at the time of winding based on the presence or absence of the film running signal. a reversal timer circuit that determines the film running state; a forward rotation relay that rotates the motor in the forward direction when the forward rotation timer circuit is operating; and a forward rotation relay that causes the motor to rotate forward when the reversal timer circuit is operating. A reversing relay for reversing the rotation; a reversing control timer circuit that operates when the forward reversing relay is turned off to turn on the reversing relay; and a resistor connected in series with the reversing relay to increase its voltage. A motor control device comprising: a motor control device which prevents a reversing relay from being turned on due to fluctuations in power supply voltage, thereby preventing rewinding of photographic film.