JPH0119567B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a film feeding method for accurately feeding one frame of film in a camera equipped with an automatic winder mechanism.

Various cameras equipped with automatic winder mechanisms have been known for a long time, but in order to feed one frame of film in these conventional cameras, the film feeding motor is turned on and off with a switch that is turned on and off each time the film is wound. It was something to control. . For this reason, it is affected by changes in the output voltage of the battery (power supply), film variations, and motor load fluctuations due to changes in ambient temperature, resulting in the disadvantage that the amount of film fed is not constant and the film frame spacing varies. Ta.

The present invention has been made in view of this point, and includes a film feeding method in which a film feeding motor is controlled using pulses generated for each unit movement of the film to feed the film. comprising means for counting the subsequent pulses and means for measuring the interval between the pulses, and measuring the interval between the pulses after a period of time has elapsed until the film movement speed reaches a substantially constant speed after the start of feeding; The amount of overrun at this moving speed is predicted from the measured value using a correspondence table prepared in advance, and in anticipation of this predicted amount of overrun, the drive of the film feeding motor is stopped and braking is applied. By using the film feeding method characterized by the following, it is possible to always feed the film at a constant rate per frame without being affected by the above-mentioned factors, and moreover, the film feeding method can be carried out in a short time. This has been realized.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing one embodiment of the method of the present invention, in which 10 is a pulse generator, 20 is a waveform shaping circuit, 30 is a switching circuit, 40 is a one-chip microcomputer (hereinafter abbreviated as MC), 50
is a motor drive circuit, and 60 is a battery.

The pulse generator 10, when winding the film,
It outputs a pulse signal for each unit movement of the film, and is arranged opposite to a Siemens star-shaped slit disk (hereinafter referred to as the Siemens star) 11 that rotates in conjunction with the film feeding, with the Siemens star 11 in between. It is composed of an LED 12 and a phototransistor 13. siemen star 11
is a circular plate provided with a large number of slits 11a of equal pitch in a radial direction, and when this rotates,
The beam irradiated from the LED 12 to the phototransistor 13 is intermittent.
still. The LED 12 and phototransistor 13 include
The battery 60 is connected via resistors 12a and 13a, respectively.
is applied to the output voltage.

The mechanism portion that specifically rotates the Siemens Star 11 is constructed as shown in FIG. That is, a reel 53 is connected to the output shaft of the film feeding motor 51 via a reduction gear train 52, and the film 102 is fed by the rotation of the reel 53, and the sprocket is activated as the film 102 is fed. 101 is rotated, and the rotation is transmitted to gears 103 → 104 → 105 → 106 forming the speed increasing gear train, thereby rotating the Siemens star 11 integrated with gear 106. In addition, 15 is Siemens Star 1
A fixed Siemens star located coaxially with 1. With the above configuration, a pulse signal is output from the phototransistor 13 for each unit movement amount of the film 102.

The waveform shaping circuit 20 is, for example, a Schmitt trigger circuit, and shapes the pulse signal given from the phototransistor 13 into a pulse signal suitable for the MC 40. The switching circuit 30 controls ON/OFF of the power supply to the pulse generator 10 and the waveform shaping circuit 20 based on the control signal from the MC 40, and controls the power supply to the pulse generator 10 and the waveform shaping circuit 20 using the transistor TR.
and resistors R ₁ and R ₂ . The output voltage V of the battery 60 is applied to the emitter of this transistor TR.
is applied, and there is a resistance between the base and emitter.
R ₁ is connected. Furthermore, the base is connected to the output port _O1 of MC40 through a resistor _R2 , and when the signal is LOW, the transistor TR is ON, and conversely, when the signal is HIGH, the transistor TR is ON.
It becomes OFF.

The MC 40 executes a predetermined program, reads pulse signals, and controls various parts, and includes a ROM 42 that stores programs, a RAM 43 that stores data, a central processing unit (hereinafter referred to as CPU) 41 that is the center of control, and a data storage system. I/O port 44 for control input/output,
It consists of a clock oscillator 45 that supplies clock pulses for the CPU 41. Furthermore, CPU4
1 connects the ROM 42 and RAM 4 via the bus 46.
3 and the I/O port 44 to exchange data and control signals. The I/O port 44 is
Normally, it consists of an input port and an output port, each consisting of a register that temporarily stores information, a so-called latch, and a decoder for address selection of input/output circuits. The output signal of the waveform shaping circuit 20 is introduced to the input port _I1 , and the output signal of the waveform shaping circuit 20 is input to the output port _O1 .
sends a control signal to the switching circuit 3, and
Output port O ₂ sends a control signal to motor drive circuit 50 .

The motor drive circuit 50 includes a film feeding motor 51
The current flowing through the motor 51 is interrupted by a transfer switch 53 of a relay 52. The switch 53 is controlled to turn on and off by energizing the solenoid 54 of the relay 52, and when the switch 53 is turned off, the motor current is cut off and the film feeding motor 51 is braked.

An example of the relationship between the amount of film movement and the speed is shown by curve a in FIG. 3. That is,
When the film feeding motor 51 is energized, the moving speed increases and reaches a constant speed Va at a moving amount _S1 . After that, the film feeding motor 5 is moved at the moving amount Sa.
Even if the film feeding motor 51 stops moving, the film feeding motor 51
Due to overrun, it stops at the movement amount Sc.
This amount of overrun is approximately proportional to the speed Va at constant speed. Curve b in FIG. 3 is a characteristic curve when the battery is exhausted or the ambient temperature drops, and the amount of movement S ₂ until reaching constant speed and the speed Vb at constant speed are different from curve a. Therefore, in order to make the film movement amount Sc, for example, it is necessary to stop driving the film feeding motor 51 at a movement amount Sb that is different from the case of curve a. Characteristics also change due to film variations in the same way as described above. However, in either case, the overrun amount has a constant relationship with the speed (Va, Vb) at constant speed. Therefore, MC4
0 stores a correspondence table of film feeding speed and overrun amount for cameras equipped with the MC40.

Next, the operation of the apparatus configured as above will be explained with reference to the flowchart shown in FIG.
This operation starts at the end of shooting, and first, MC40
is the predetermined number B of pulses generated until the film movement speed reaches a sufficiently constant speed (for example, the number of pulses until the movement amount Sk shown in FIG. ). Then the output port
A LOW signal is sent from _O2 to energize the solenoid 54, and the switch 53 is turned on to start the film feeding motor 51. As a result, the film 102 starts to move, and the pulse generator 10 generates a pulse signal, which is input to the input port _I1 of the MC 40 via the waveform shaping circuit 20. MC4
0 detects the rising edge of this pulse and subtracts 1 from the contents (Acc) of the accumulator Acc. After this subtraction, whether the pulse count number reached B or not,
That is, check whether (Acc) has become 0 or not,
If it is 1 or more, the pulses that arrive again are counted. When (Acc)=0, a built-in timer is started, and the next rising edge of the pulse is detected and the timer is stopped. This measures the pulse interval T (corresponding to the reciprocal of Va and Vb) at constant speed. From this T value, a predicted overrun amount D is determined using a film feeding speed/overrun amount correspondence table, and the remaining number of pulses C until the drive of the film feeding motor 51 is stopped is calculated based on the following equation.

C=A-B-D-1 However, A: The number of pulses required to move one frame.
It is stored in ROM42.

1: Correction value for one uncounted pulse when measuring pulse interval T This value C is loaded into the accumulator Acc, and then subtracted (Acc) by 1 every time a pulse is detected. At this time, it is determined whether (Acc)=0 or not, and pulse counting is continued until (Acc)=0.
When (Acc)=0, a HIGH signal is output from the output port _O2 , the switch 53 is turned off, and the drive of the film feeding motor 51 is stopped. This results in
After the film feeding motor 51 overruns due to inertia, it completely stops. As the film feeding motor 51 completely stops, the film 102 also stops. The deviation of the stop position of the film 102 from the normal stop position is equal to the deviation of the predicted overrun amount D from the actual overrun amount. by the way,
Since this predicted overrun amount D is obtained from a film feed speed/overrun amount correspondence table (this correspondence table is obtained experimentally) for a certain type of camera, the above-mentioned deviation is extremely small. That is, the film 102 stops in a substantially normal state.

Incidentally, in the above embodiment, the configuration is shown in which the period of the output pulse of the pulse generator 10 is sufficiently larger than the period of the clock pulse of the MC 40.
If the period of the output pulse becomes small and is not sufficiently large compared to the period of the clock pulse, the MC4
Pulse generator 1 with external or built-in counter at 0
It is also possible to control film feeding using a pulse obtained by appropriately dividing the zero output pulse.
Also, the first frame of photographing is set by feeding three frames of film (blank feed);
Regarding the amount of overrun when feeding a frame, either store it in the MC40 in advance and use it, or use 3A instead of A in the calculation formula for C.
The feeding can be controlled using .

As explained above, according to the method of the present invention, one frame of film can be fed without being affected by battery voltage fluctuations, variations in various films, motor load fluctuations due to changes in ambient temperature, etc. Therefore, the piece spacing is always constant.

Further, since the voltage applied to the film feeding motor during driving is always the maximum voltage, the film feeding time becomes the shortest.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the film feeding method of the present invention, FIG. 2 is a schematic configuration diagram of the Siemens star portion, and FIG. 3 is a characteristic diagram showing the relationship between film movement amount and speed. FIG. 4 is a flowchart for explaining the operation. 10...Pulse generator, 40...Microcomputer, 50...Motor drive circuit, 51...
Film feeding motor.

Claims (1)

[Claims] 1. A film feeding method in which the film is fed by controlling a film feeding motor using pulses generated for each unit movement of the film, including means for counting the pulses after the start of film feeding; A means for measuring the interval is provided, and after a period of time has elapsed until the film moving speed reaches a substantially constant speed after the start of feeding, the pulse interval is measured, and the overrun amount at this moving speed is calculated from the measured value. ,
A film feeding method characterized in that the amount of overrun is predicted using a correspondence table prepared in advance, and the drive of the film feeding motor is stopped and braking is applied in anticipation of the predicted amount of overrun.