JPS5838777B2 - Film Makimodo Shijidoutei Shisouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic stop device for film rewinding in a camera, and more particularly to an automatic stop device for film rewinding in an electric drive device in which operations such as film winding, rewinding, and shutter release are driven by a motor. It is something.

For example, when photographing using film stored in a cartridge such as in a 35 mm still camera, it is necessary to take out the film that has been rewound into the cartridge after photographing is completed and put it back into the developing machine for processing.

If the leading edge of the film is sticking out of the cartridge, you can just pull it out, but if the film is completely wound up inside the cartridge, either destroy the cartridge or use a special tool to remove the film. have to pull it out.

In a 35 mm camera, when manually rewinding the film after shooting, the photographer sensitively senses the torque change on the rewind shaft and stops the film rewinding operation, so that the film is completely unrolled. It is possible to stop rewinding before the rewind is reeled in. However, when performing electric rewinding using an electric drive device, a means is required to detect the end of rewinding and automatically stop the rewinding operation. It is.

Conventional electric drive devices have a method of mechanically detecting the presence or absence of film on the take-up spool on the camera side, and use a signal from this to stop the rewind motor on the electric drive device side. .

In this type of stopping device, it is necessary to provide a mechanical detection mechanism on the camera side, which complicates the structure of the camera, which goes against the idea of making the camera smaller and lighter. For users of the camera, this detection mechanism is unnecessary and has the disadvantage of increasing the price of the camera.

The present invention provides an automatic film rewinding stop device for an electric drive device that eliminates the above-mentioned drawbacks, and utilizes the fact that the rewinding load changes between when the film is rewinded and when the rewinding is finished. Means for mechanically detecting load changes is provided on the electric drive device, thereby detecting the end of rewinding, and automatically stopping the rewinding operation at the end of rewinding.

During this automatic stopping operation, the motor is provided with an electric circuit that suppresses the braking action to prevent the film from being caught in the cartridge.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a mechanical configuration diagram of an electric camera showing an embodiment of the film rewinding automatic stop device according to the present invention, and FIG. 2 is a mechanical detection system for detecting a decrease in load during rewinding of the device in FIG. 1. An enlarged cross-sectional view of the vessel.

FIG. 3 is a connection diagram showing one embodiment of the circuit of the film rewind automatic stop device according to the present invention.

In Fig. 1, 1 is the camera body, 2 is the rewinding spool,
3 is a sprocket.

4 is a cartridge loaded in the camera, and 5 is a film.

Reference numeral 7 denotes a rewinding shaft in the electric rewinding device 6, at its upper end there is a rewinding coupler 8 that engages with the spool shaft 4' in the cartridge chamber 4, and at its lower end there is a rewinding coupler 8 whose detailed structure is shown in FIG. It is connected to the shaft 9 via a load detector 10 which shows the load detector 10 shown in FIG.

A claw clutch 9a and a rewind lever 11 are provided at the lower end of the shaft 9.
A disk 12 that engages with one end 11a of is fixed.

A spring 13 is disposed between the rewind device main body 6 and the disk 12 to always restrain the rewind shafts I and 9 downward.

An intermediate portion of the rewinding shaft 7 passes through the inside of a worm wheel 14 rotatably supported by the electric rewinding main body 6.

A pawl clutch 14a is fixed to the lower part of the worm wheel 14, and the worm wheel 14 is connected to a motor M via a worm 15 and a speed reduction device 16.

The shaft on the opposite side of the motor M is connected to a winding shaft 18 via a film advance control mechanism 17, and when the motor M rotates in the forward direction, the film is advanced through a winding coupler 19 and a camera side spool 2. .

The shirt release of the camera may be performed electrically by providing a known motorized release device within the motorized rewind device, or may be performed manually.

One end 1 of a rewind lever 11 rotatably supported on the main body
A pin 20 is installed in 1a, and a pin 21 is installed in the other end 11b.

When the rewind lever 11 is rotated clockwise as shown in the figure, the normally open switch S1 is switched from off to on by the pin 20, and the normally closed switch S2 is switched from on to off.

In addition, when the rewind lever 11 rotates clockwise, the double-throw switches S3 and S4 switch from the state where a and C and a/ and J are connected to contact b and C and b' and C/ due to the pin 21. The state is switched to

FIG. 2 shows an enlarged cross section of the load detection mechanism 10 described above.

Reference numeral 22 denotes an elastic joint that connects the above-mentioned unwinding shafts 7 and 9, and although a plate spring is shown in the figure, a coil spring may also be used.

Numerals 23 and 24 are cylindrical insulators placed over the unwinding shafts 7 and 9, on which cylindrical conductors 25 and 26 with contacts 25' and 26' are fixed.

Further, the cylindrical conductors 25 and 26 constitute an on-off switch S5 with contacts 25' and 26', which is a switch that is closed by swinging between the shafts 7 and 9.

That is, it is opened when the load is relatively small, and closed when the load exceeds a certain amount.

In FIG. 3, E is a power supply, and 2γ is a film winding and shirt release control circuit.

Resistor R1 and capacitor C1 are connected to motor M at the start of rewinding.
It constitutes a time constant circuit to supply power to.

Transistor TR1 is a control circuit that controls the supply of power E to motor M.

Further, the transistors TR2 and TR3, the diode D1, and the resistor R2 constitute a braking circuit for the motor M.

Next, to explain the operation of the embodiment of the present invention configured as described above, first, for shutter release and film winding, switches S3 and S4 are set to the normally closed side, that is, the side where a and C and a' and J contact each other. , a film advance control mechanism 17, a known electric drive mechanism and film winding mechanism (not shown),
This is done by causing the shutter release control circuit 27 to rotate the motor in the forward direction.

After photographing a predetermined number of images, to perform electric rewinding, first press the R button (not shown) to make the sprocket 3 rotatable, and then rotate the rewinding lever 11 clockwise.

In conjunction with the clockwise rotation of the rewind lever, the pin 20
The switch S1 is turned on and the switch S2 is turned off, and the switches S3 and S4 are turned on, respectively.
It switches from '-c' on to b-c and b'-c' on.

At the same time, the end 11a of the rewind lever pushes up the rewind shafts 9 and I against the spring 13, thereby engaging the pawl clutches 9a and 14a.

When the switch S1 is turned on, power E is supplied to the rewinding circuit, and when the switch S2 is turned off, the short circuit between both ends of the capacitor C1 is released.

As a result, transistor TR1 becomes conductive, so power supply E - switch S1 - diode D1 - switch S3 b
, c-M-switch S4b', cl-transistor TR
1- A closed circuit of the power source E is formed and the motor M rotates in the opposite direction.

The rotation of the motor M in the opposite direction is performed by the reduction gear 16, the worm 15, the worm wheel 14, and the pawl clutch 14a.

The signal is transmitted to the cartridge 4 via the rewind shaft 9, the load detector 10, the rewind shaft I, and the rewind coupler 8, and rewinds the film 5 into the cartridge 4.

When rewinding is started, the deflection elastic joint 22 in the load detector 10 starts to deflect due to the load of each member rotating during rewinding, and as a result, the switches 25', 26' is closed, that is, the switch S5 is turned on, and the rewinding shaft continues to rotate.

Here, the time constant is set to be shorter than the time required for unwinding the time constant of the resistor R1 and the capacitor C1, which constitute a time constant circuit for keeping the transistor TR1 in a conductive state.

Even if the transistor Tr1 becomes non-conductive due to the time constant circuit during rewinding, the switch S5 is already conductive at this time, so power is supplied to the motor M through S5, and therefore the motor M rotates in the opposite direction. continue.

Next, when the rewinding is completed and the film 5 is removed from the rewinding spool 2, the rotation of the take-up spool 20 is stopped, so the load of rewinding is reduced, and the load detector 10 installed at the rewinding shaft 7°9 is The amount of deflection of the elastic joint 22 decreases.

This causes contact 25'. 26' becomes open again and switch S5 is turned off.

Needless to say, it is necessary to adjust the strength of the leaf spring 220 depending on the relationship between the amount of load reduction at the end of rewinding and the opening/closing of the switch S5 based on this amount.

By opening the switch S5, the transistor TR1 is already in a non-conducting state, so the supply of the power E to the motor M is cut off.

Then, due to the electromotive force of the motor M, the transistors TR2 and T
Since both R3 become conductive, both ends of the motor M are short-circuited and stop instantaneously, stopping rewinding.

Next, when the rewinding lever 11 is rotated counterclockwise, each member returns to the phase on the winding side.

As described above, according to the present invention, the rewind end detection mechanism is activated when the film comes off the take-up spool, and the film is completely inserted into the cartridge in order to apply the brake and stop the film. You can stop rewinding before it gets caught.

Furthermore, according to the present invention, when the camera and the electric rewinding device are separate, the end of rewinding can be detected entirely on the electric rewinding device side, so there is no need to provide a complicated mechanism on the camera body side, which is effective. In addition to this, the motor can be driven independently of the detection means at the start of rewinding when the rewinding load is unstable, so there is no trouble starting rewinding, and rewinding can be started easily. It has many advantages and its effects are unique.

[Brief explanation of the drawing]

Fig. 1 is an embodiment of the film rewinding automatic stop device according to the present invention, and is a mechanical configuration diagram of an electrically driven camera.
FIG. 3 is an enlarged sectional view of the mechanical detector in the device shown in the figure, and a circuit connection diagram showing an embodiment of the automatic film rewinding stop device according to the present invention. 1...Camera body, 6...Electric drive device, 10...Load change detector, 11...
- Winding/rewinding switching lever, 16... Speed reduction device, M... Motor, 17... Winding control mechanism, 27... Film winding, shutter release control circuit.

Claims (1)

[Claims] 1. A first power supply path and a second power supply path are formed in the film rewinding motor, a first switch is connected in the first power supply path, and a first switch is connected in the second power feed path. A second switch is connected, and a timer circuit is used to turn on the first switch for a time shorter than the time required for rewinding, supplying power to the motor, and detecting a change in the film rewinding load. When the unwinding load exceeds a predetermined value by the detection means, the second switch is turned on to supply power to the motor, and when the unwinding load becomes below a predetermined value, the second switch is turned off. An automatic film rewinding stop device characterized in that the film is brought into a conductive state and stops power supply to the motor. 2. The device according to claim 1, further comprising a transistor braking circuit connected in parallel to the rewinding motor;
An automatic film rewinding stop device characterized in that when both the first switch and the second switch become non-conductive, the transistor is controlled by the electromotive force of the motor to perform a braking action on the motor. .