JPS6213070Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor drive device for a camera.

The motor drive device of a camera supplies power to the motor for a specified time to wind the film, and when this is complete, it cuts off the power to the motor and allows the shutter to be released. If an accident or other reason prevents the film from being wound normally, the film winding will not be completed and power will continue to be supplied to the motor, damaging the film. For this reason, in the past, the motor was turned off when it was detected that power had been supplied to the motor for longer than the film winding time. However, if a higher voltage battery case could be attached to such a motor drive device, the film winding time would be shorter and the film winding force would be greater, so it would be necessary to turn off the motor power for a time shorter than the film winding time.

An object of the present invention is to provide a camera motor drive device that can automatically adjust the time until the power supply to the motor is cut off according to the output voltage of a power supply housed in a battery case.

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

Motor drive device including motor M in Figure 1
A high voltage battery case Bc installed in the MD and motor drive device MD is shown. Inside the battery case Bc is a power supply for generating high voltage.
Ba is contained. The battery case has output terminals 1 and 2 and a pin 3 protruding from this case.
is installed. Input terminals 11 and 12 are installed in the motor drive device MD,
and a switch contact piece 13 arranged at the rear of the hole 14.
A constitutes a normally closed switch 13 together with a contact piece 13b.

A low-voltage battery case (not shown) accommodates a power source for generating low voltage within the case, and has a configuration in which pin 3 is removed from the battery case Bc in FIG. 1.

Figure 2 shows the circuit inside the motor drive MD.
A motor M for driving the winding mechanism inside the camera body, input terminals 11 and 12, switch contacts 13a and 13b, a switch 21 that is turned on when the shutter rear curtain runs and turned off when winding is completed, and controls the motor M. A timer circuit consisting of a transistor Tr ₄ , a resistor R, capacitors C ₁ and C ₂ , and a transistor Tr ₇ , which controls the transistor Tr ₄ , and a capacitor.
Transistor Tr ₆ for discharging C ₁ and C ₂ , input terminal 1
It is composed of a Zener diode Zd that controls the voltage at point Vz to always be constant even if the voltage between points 1 and 12 changes, and a spike prevention diode D.

Next, the operation of the first embodiment described above will be explained.

First, we will discuss the case where a low-voltage battery case is attached to the motor drive device MD. In this case, since there is no pin 3 in the case, the switch contact piece 13a is not pushed by the pin 3, and the switch 13 is turned on as shown in FIG. Also, after winding is completed and before shutter release, switch 2 is pressed as shown in Figure 2.
1 is off, so each transistor Tr ₁ to Tr ₅ ,
Tr ₇ is off and transistor Tr ₆ is on.
Therefore, motor M is stopped, and capacitors C ₁ and C ₂ are both discharged via transistor Tr ₆ . When the shutter button (not shown) is pressed to release the shutter from the state shown in FIG. 2, the film is exposed, the shutter trailing curtain runs, and the switch 21 is turned on. Therefore, transistors Tr ₁ to Tr ₅ are turned on immediately, and the transistors Tr 1 to Tr 5 are turned on immediately.
Tr ₆ turns off immediately. Transistor Tr ₇ remains off. In this way, when the transistor Tr ₄ is turned on, current from the power supply flows through the terminal 1, the terminal 11, the motor M, the transistor Tr ₄ , the terminal 12, and the terminal 2, and the motor M rotates. This motor M then rotates. This motor M drives a winding mechanism within the camera body to perform winding operations such as film winding and shutter charging. When the winding of one frame is completed, the switch 21 is turned off and the initial state shown in FIG. 2 is duplicated. If the shutter button (not shown) is held down, the shutter release and winding operations are repeated alternately, resulting in continuous shooting.

Capacitors C ₁ and C ₂ are always discharged by turning on transistor Tr ₆ before shutter release. When the rear shutter curtain (not shown) runs and the switch 21 is turned on and the transistor Tr ₆ is turned off, the battery is charged via the transistor Tr ₂ and the resistor R.
The terminal voltages of capacitors C ₁ and C ₂ reach a voltage (threshold voltage) that turns on transistor Tr ₇ after a predetermined time has elapsed from the start of charging. Note that this predetermined time is determined by C ₁ , C ₂ and R. Further, this predetermined time is set to be somewhat longer than the time normally required for winding up one frame (the time from turning the switch 21 on to turning it off).

Therefore, normally, the energization of the motor M is controlled by turning the switch 21 on and off, and the timer circuits R, C ₁ , C ₂ and Tr ₇ have no influence on the motor M. That is, charging of the capacitors C ₁ and C ₂ starts at the same time as the switch 21 is turned on, but when winding is completed and the switch 21 is turned off, the capacitors C ₁ and C ₂
is discharged, and the timer circuit is reset before it has counted the predetermined time.

However, if the winding is not completed even after the winding time for one frame has elapsed due to an unexpected accident, the switch 21 remains on. Therefore, the transistor Tr ₆ also remains off. Therefore, when a predetermined time longer than the winding time for one frame has passed and the terminal voltages of capacitors C ₁ and C ₂ reach a predetermined voltage, transistor Tr ₇ is turned on for the first time, and transistor Tr ₄ is turned on for the first time.
is forcibly turned off. Then, motor M is stopped.

In this way the battery case for low voltage
If Bc' is attached and power is being supplied to the motor for longer than the winding time of one frame of film, the power supply will be forcibly cut off.

Next, the case where the high voltage battery case Bc is attached to the motor drive device MD will be described.
In this case, the motor M is driven by the high voltage of the power source Ba, and the time required to wind one frame of film is shorter than when the motor M is driven by the low voltage power source described above. In other words, the time from when the switch 21 is turned on until it is turned off is shortened.
On the other hand, since the switch contact piece 13a of the switch 13 is pressed by the pin 3 when the battery case is attached, the switch 13 is turned off. Even if the power supply voltage changes to a high voltage, the Zener diode Zd always controls the voltage at the Vz point to be a constant voltage, so the voltage across the capacitor _C2 is controlled by the transistor.
The time to reach the threshold voltage of Tr ₇ is determined by the resistor R and capacitor C ₂ ,
By turning off the switch 13, the time required for the capacitor _C1 to reach the threshold voltage is shortened by the fact that the capacitor C1 becomes independent of the charging time. The predetermined time required for the voltage of the capacitor _C2 to reach the threshold voltage of the transistor _Tr7 is set to be somewhat longer than the winding time for winding one frame of film using the high voltage power supply Ba. In this way, by using the high voltage power supply Ba, the predetermined time counted by the timer circuits R, C ₂ and Tr ₇ is shortened by the amount of time that the winding time is shortened. The other elements operate in exactly the same way as when the low-voltage battery case is attached, so their explanation will be omitted.

When the high-voltage battery case Bc is installed in this way, the counting time of timer circuits R, C ₂ , and Tr ₇ is shortened by the amount of time that the hoisting time is shortened. If winding is not completed even after the time required for high-speed winding of one frame of film has elapsed during operation, the terminal voltage of capacitor _C2 reaches the threshold voltage of transistor _Tr7 , forcing the power supply to motor M. cut off.

Therefore, even if the film winding time is shortened by employing a high voltage battery case, no excessive winding force is transmitted to the film.

FIG. 3 shows a second embodiment according to the present invention, in which a conductive plate 4 is provided in a low voltage battery case _Bc'1 . The motor drive device MD1 is provided with terminals 15 and 16 made up of coil springs. Therefore, when the low voltage battery case Bc' ₁ is attached to the motor drive device MD1, the conductive plate 4 is pressed against the coil springs 15 and 16, and the terminals 15 and 16 are brought into electrical continuity.

Moreover, the conductive plate 4 is not provided in the high voltage battery case. Therefore, when a high voltage battery case is attached to the motor drive device MD,
Although the wall surface of the battery case is pressed against the terminals 15 and 16, there is no electrical continuity between the terminals 15 and 16.

As described above, in this embodiment, the determination is made based on the difference in shape (that is, whether the battery case is provided with the conductive plate 4 or not (that is, whether it is for high voltage or low voltage) and whether the terminals 15 and 16 are conductive or nonconductive. That is, in the second embodiment, the pin 3 of the first embodiment is replaced with a conductive plate 4, and the switch means 13a, 13b of the first embodiment are replaced with switch means consisting of springs 15, 16. Other elements in this embodiment are the same as those in the first embodiment described above. Furthermore, since the operation is similar to that of the first embodiment described above, the explanation will be omitted here.

The coil springs 15 and 16 used in this embodiment act as terminals and at the same time serve to push the battery case out of the battery case housing (not shown) in the motor drive device MD. Therefore, the second embodiment is convenient when taking out the battery case from the storage section.

In the embodiments described above, the connection of the capacitor is controlled by the battery case and the time constant of the timer circuit is selected, but in the present invention, the time constant may be selected by a method different from that in the embodiments.

In addition, a resistor can be connected to the emitter of transistor Tr ₇ , and depending on the battery case, the resistor can be connected to the emitter or _disconnected from the emitter. The same effect as in the embodiment described above can be achieved by increasing or decreasing the base voltage. That is, the time from the start of charging the capacitor until the transistor Tr ₇ turns on can be selected depending on the battery case.

As described in detail above, according to the present invention, the time for cutting off the power supply to the motor is automatically selected based on the output voltage of the power supply housed in the battery case.
Therefore, even if a high-voltage battery case is attached, the film winding force increases and the winding time is shortened, the power supply to the motor can be cut off in a short time, and there is no risk of damaging the film.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the relationship between a battery case and a motor drive device according to a first embodiment of the present invention, and FIG. 2 is a circuit diagram for controlling the motor. FIG. 3 is a perspective view showing a second embodiment of the present invention. Explanation of symbols of main parts, {Ba...High voltage power supply,
Ba1'...Low voltage power supply} Power supply, {Bc...High voltage battery case, Bc'1...Low voltage battery case} Battery case, R, C ₁ , C ₂ , Tr ₇
...Timer circuit, Tr ₄ ...Control circuit, 13a,
13b,; 15, 16... switch means.

Claims (1)

[Claims for Utility Model Registration] A timer circuit is activated in accordance with the power supply to the motor from the power source in the battery case, and after a predetermined period of time has elapsed, the timer circuit activates a control circuit to supply power to the motor. In a camera motor drive device that cuts off the timer; the timer circuit is configured to operate the control circuit after counting either a first predetermined time or a second predetermined time shorter than the first predetermined time, and the timer circuit is housed. A switch means is provided for determining the identification signal of the battery case when a battery case having different identification signals depending on the output voltage of the power source is installed, and when the output voltage is low, the timer circuit The switching means controls the time counted by the timer circuit according to the output voltage of the battery case so that the first predetermined time is counted, and the second predetermined time is counted when the output voltage is high. A device characterized by switching.