JPH06208160A - Film feeder for camera - Google Patents

Abstract

PURPOSE:To provide the film feeder of a camera capable of correctly feeding a film even at a low feeding speed of the film when feeding the film by one frame, for example, by optically detecting the perforations of the film. CONSTITUTION:Perforations of a film fed by a motor are detected by a photo- reflector, the detected information is digitally converted at each time set by a timer (step 7 through step 9), the digitally converted conversion value PF-AD is compared with the threshold value LEVEL (step 10). If the film is fed at a low feeding speed when perforations are counted (steps 11, 12), the time of the timer is extended (ADTIME=Y is set in step 1).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film feeding device for a camera which optically detects the perforation of a film, for example, the film feeding of one frame.

[0002]

2. Description of the Related Art As a device for detecting a film feed amount of a camera, an optical sensor such as a photoreflector including a light emitting / receiving element is provided in the camera, and the light is projected from the light emitting element toward a film surface on which a perforation is formed. Light is emitted, and the reflected light is received by the light receiving element, and reflected on the film surface.
It has already been proposed to detect non-perforation by utilizing non-reflection in perforation.

The signal photoelectrically converted by the light receiving element is an analog signal, and this analog signal converted into a digital signal at regular intervals is compared with a threshold value (a value for determining that a perforation edge has come), and the threshold value is set. A pulse corresponding to the perforation is output depending on whether or not the pulse exceeds.

Although it is ideal that the waveform of the analog signal is a sine wave, when the film feeding speed becomes low, the entire waveform tends to be in a dull shape.

[0005]

By the way, it is ideal that the waveform of the analog signal photoelectrically converted by the light receiving element should be a sine wave, but when the film feeding speed becomes low, the entire waveform is delayed. It tends to look good.

For this reason, the AD-converted value becomes linear, and even if there is a slight noise, it becomes an object of comparison with the threshold value, so that there is a possibility that the perforation is erroneously detected.

SUMMARY OF THE INVENTION It is an object of the present invention to solve such a conventional problem and to provide a film feeding device for a camera which can accurately detect perforations even when the film feeding speed is lowered. To do.

[0008]

The constitution for achieving the object of the present invention is as set forth in the claims. For example, the perforation of the film fed by the film feeding means is optically performed. It has an optical sensor for detecting, and perforation counting means for digitally converting the detection information from the optical sensor for each time set in the timer means and comparing the digitally converted value with a threshold value to count perforations. In the film feeding device of the camera, the perforation counting means, when it judges that the film feeding speed is low, lengthens the set time of the timer means.

In the film feeding device of the camera having the above-described structure, when the film feeding speed is low, the time from the conversion of the analog signal photoelectrically converted by the optical sensor into the digital signal until the next conversion. Since the interval (hereinafter abbreviated as AD conversion interval) is lengthened, the amount of change (voltage difference) in the analog signal during that time increases, and even if noise occurs in the received light signal, the effect of this noise is reduced.

[0010]

FIG. 4 is a block diagram showing a first embodiment of a film feeding device for a camera according to the present invention.

Reference numeral 1 is a microcomputer for controlling the operation of the camera (hereinafter abbreviated as microcomputer), 2 is a motor driver for driving a film feeding motor 3, and 4 is a light projecting element 4.
a and a photoreflector composed of the light receiving element 4b, 5
Is a constant current circuit for the photo reflector 4, and 6 is a film feeding low speed mode switch (MSW).

The microcomputer 1 sets the output terminal L2 to a high level (hereinafter abbreviated as "H") to operate the well-known constant current circuit 5 to light the light projecting element 4a. Reflected light from the film surface projected by the light projecting element 4a is received by the light receiving element 4b. However, if the light projecting surface is perforation, the reflected light is small, and if not, the reflected light is large. The light-receiving element 4b passes a current in proportion to the amount of reflected light, and the input terminal L3 receives the current × R1.
A voltage of (resistance value) is generated.

By setting the output terminal L4 of the microcomputer 1 to a low level (hereinafter abbreviated as "L") and the output terminal L5 to "H", the motor driver 2 uses the output terminals L6 and L7 to feed the motor 3 to the film. The signal for driving control is output to. If both the output terminals L4 and L5 of the microcomputer 1 are set to "H", the motor driver 2 outputs the output terminal L6,
A signal for stopping the motor 3 is output from L7.

The microcomputer 1 also determines whether or not the film feeding speed is low, and there are the following three cases when it can be determined that the film feeding speed is low.

: When the power supply voltage is low: When the film feeding mode is low: When the feeding speed is low

In the above case, for example, the terminal L1
A / D conversion is performed on the divided voltage of the power supply voltage at, and the decrease in the power supply voltage is detected by checking the value,
Predict that the feeding speed will be low.

In the above case, for example, the MSW switch 6
When is turned on, the input terminal L8 of the microcomputer 1 becomes "L", and it is detected that the film feeding speed is designated to the low speed mode. Here, when the low speed mode is designated, the terminal L
5 is "H" and the terminal L4 is duty-driven to reduce the speed of the motor 3 to reduce the film feeding speed.

In the above case, the film feeding time for one frame is always stored, and before feeding, the previous feeding time is checked to judge whether the feeding speed is low or not.

Further, the microcomputer 1 is a photo reflector 4
Analog signal from the light receiving element 4b of
D conversion is performed and the converted value is compared with a threshold value, and the level of this threshold value is set during auto loading.

The photoreflector 4 is constantly operating during feeding, sends the data to the microcomputer 1, and the microcomputer 1 performs AD conversion according to the AD conversion interval to detect perforation. In addition, the detection operation is performed many times between the perforations.

Therefore, if the conversion output time becomes long,
The amount of detected data (voltage) increases accordingly.

Next, the operation of this embodiment will be described with reference to the flow chart shown in FIG.

When the microcomputer 1 enters the film feeding operation, it is judged in step 1 whether or not the film feeding speed is low, and if it is low, the interval for converting the analog signal from the light receiving element 4b into a digital signal. Is a constant Y for the AD conversion interval variable (ADTIME) that is
Input (Y> X), proceed to step 2, and enter the constant current circuit 5
To drive the photo reflector 4 and step 3
At 3, the motor 3 is driven to feed the film, and the process proceeds to step 4.

In step 4, the current time (TIME) is input to the time variable T1 and the process proceeds to step 5.

In step 5, 0 is input to a counter (PF_CNT) that counts the boundary between the perforations of the film (the boundary between the hole and the non-hole portion), and it is determined whether or not the perforation is detected. 0 is input to EG_FLG used as a discriminator for discriminating that what is to be done is the opposite of this time (EG_FLG =
(Determined by 0, 1), the process proceeds to step 6.

Step 6 includes steps 7 to 12
In the perforation count processing operation, the perforation count processing operation is repeatedly performed until the count of the perforation boundary becomes 16 or more. When the count of the perforation boundary becomes 16 or more, it is determined that one frame has been fed. The driving of the motor 3 is stopped (step 13), and the operation of the photo reflector 4 is stopped (step 14).

The perforation count processing operation in steps 7 to 12 is as follows. First, in step 7, while the time from the start of film feeding to the current time is smaller than the AD conversion interval input in step 1, 8 forms an infinite loop that does not shift to 8 and, for example, if the film feeding speed is low, ADTI
Y is input to ME, and this conversion time becomes longer (Y> X) than in the case of a normal feeding speed.

When this conversion time has elapsed, the current time (TIME) is input to the time variable T1 (step 8), and the process proceeds to step 9 in preparation for the next counting operation.

In step 9, the voltage value photoelectrically converted by the light receiving element 4b of the photo reflector 4 is converted into a digital signal. Therefore, if the film feeding speed is low, the voltage change amount value increases correspondingly, and the influence of noise decreases.

In step 10, A in step 9
The D-converted AD conversion value is compared with the threshold value (LEVEL). If the AD conversion value is higher than the threshold value, the process proceeds to step 11, and if it is low, the process proceeds to step 12.

It should be noted that when the reflected light from the film surface is received, the amount of reflected light is large and the AD-converted value is also high. Conversely, when the reflected light from the perforation is received, the reflected light is reflected. Since the amount of light is small, the AD-converted value is also low. In this embodiment, the threshold level is set when the film is automatically loaded.

At step 11, it is judged whether or not EG_FLG is 0. If it is 0, EG_FLG is set to 1 and PF_
Count 1 CNT.

In step 12, EG_FLG is 1
If it is 1, EG_FLG is set to 0, and P
Count F_CNT by 1.

That is, EG_FLG = 0 indicates that the film surface is detected, and EG_FLG = 1 indicates that perforation is detected. Therefore, when the threshold level is changed next time, the film is naturally changed. It is expected that the detection state will switch from the surface to the perforation, and from the perforation to the film surface, so when the expected result is obtained, it is sure that the movement from the film surface to the perforation and the movement from the perforation to the film surface ( It can be said that the boundary positions on both sides of the perforation) have been detected, and the counter PF_CNT at the boundary of the perforations is incremented by one. And the count number of PF_CNT is 16, that is, 8
When the number of perforations is counted, it is determined that the film for just one frame has been fed, and the perforation counting operation is ended.

In steps 11 and 12, EG
If _FLG is not what is expected, the process returns to step 7 and the same operation is repeated.

FIG. 2 is a flow chart showing a second embodiment of the present invention. In this embodiment, when the film feeding speed is low, each AD conversion value is not compared with the threshold value each time, and the previous AD conversion is performed. A value obtained by averaging the converted value and the AD converted value of this time is compared with the threshold value.

In step 1, if the film feeding speed is low, the speed flag SPEED_LOW =
1, the photo reflector 4 is turned on (step 2), the film feeding drive of the motor 3 is performed (step 3), and the current time is input (step 4) as in the first embodiment, and PF_CNT = 0 in step 5. EG_FLG = 0,
Previous perforation AD conversion value PF_OLDAD
= 0 and proceed to step 6.

In step 6, the value of PF_CNT is 16
Until the above is reached, the perforation count processing operation from step 7 to step 15 is executed. And
When the value of PF_CNT becomes 16 or more, the motor 3 is stopped (step 16) and the photo reflector 4 is turned off.

In step 7, 1 is input to the old and new conversion value flag N which determines the old and new of the AD conversion value, and the AD conversion value is assumed to be new.

In step 8, the process of steps 9 to 15 is waited for until a certain AD conversion time has elapsed, and after the current time is input (step 9), AD conversion is performed (step 10). ).

If the speed flag is 1 in step 11, the film feeding speed is low, so the process proceeds to step 12.

In step 12, the AD conversion value is the new A
If it is a D conversion value (N = 1), that value is converted to the old conversion value (PF
_OLDAD), flag N = 2, and old A
It indicates that the D conversion value exists, and the process returns to step 8. If the old conversion value exists, the sum of the old AD conversion value and the new AD conversion value is divided by 2, and the averaged value is compared with the threshold value in step 13 (PF_A
D), the flag N is set to 1, and the next AD conversion data is set as a new AD conversion value.

Then, in steps 13 to 15, the same processing as in steps 10 to 12 of the first embodiment is performed, and the perforations are counted.

That is, in contrast to the conventional comparison of each AD-converted value with a threshold value, in the present embodiment, for example, the averaged value of the first, second, third, and fourth AD-converted values. Is compared with the threshold, even if there is a small amount of noise when the film feeding speed is low, this is averaged and there is less risk of false detection of perforation.

Of course, if the film feeding speed is not low, the process proceeds from step 11 to step 13 without performing the process of step 12, and the perforation counting process similar to the conventional one is performed.

FIG. 3 is a flow chart showing the third embodiment of the present invention.

In the present embodiment, when the film feeding speed is low, the threshold value (LVL) for comparing AD conversion values is made variable, and the level is lowered when perforation is detected (LVL = LEVEL-α). At the time of detection, the level is increased (LVL = LEVEL + α) to reduce the influence of noise.

In the film feeding process according to the present embodiment, the film feeding speed is discriminated in step 1, and the speed flag SPEED_LOW is set to 1 if the speed is low and 0 if not low. Steps 2 to 4 perform the same processing as steps 2 to 4 in FIG.
, 0 is input to PF_CNT and EG_FLG, and the variable threshold LVL is set to the normal level (LVEL).
Set to.

Then, in step 6, step 7
When the perforation boundary count reaches 16 or more by the perforation count processing operation of step 12, the motor 3 is stopped (step 13) and the photo reflector is turned off (step 14).

In steps 7 to 9, the photoelectric conversion information detected by the photo reflector 4 is AD-converted at regular intervals, and in step 10, the AD conversion value (P
F_AD) is compared with the variable threshold (LVL).

If the AD conversion value is higher than the variable threshold value, EG_FLG is determined in step 11.
If EG_FLG = 0 and the film feeding speed is low (SPEED_LOW = 1), the level of the variable threshold for the next comparison is lowered (LVL = LEVEL-α).
At the same time, EG_FLG is set to 1 and PF_CNT is incremented by 1.

If the AD conversion value is lower than the variable threshold value, EG_FLG is determined in step 12, and if EG_FLG = 1 and the film feeding speed is low (SPEED_LOW = 1), Raise the level of the variable threshold for the next comparison (LVL = LEVEL
+ Α), EG_FLG is set to 0, and PF_CNT is incremented by 1.

That is, if the threshold level is always constant as in the conventional case, noise generated in the AD conversion value may exceed the threshold value. Therefore, in the case of the AD conversion value on the film surface, the threshold value is lowered. In the case of the AD conversion value of perforation, the threshold value is raised to avoid the influence of noise.

[0054]

As described above, according to the present invention,
When the film feeding speed is low, the signal waveform during one perforation detected by the optical sensor becomes a sine wave which is almost flat, but the process of lengthening or averaging the time for AD conversion of the signal from the optical sensor By adjusting the AD conversion value with, even if there is noise in the signal from the optical sensor, it will not be affected and the perforation can be accurately detected.

When the film feeding speed is low, A
The perforation can be accurately detected by adjusting the threshold level for detecting the boundary of the perforation without adjusting the D conversion value to a level less susceptible to the noise included in the signal from the optical sensor. .

[Brief description of drawings]

FIG. 1 is a flowchart showing the operation of the first embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the second embodiment.

FIG. 3 is a flowchart showing the operation of the third embodiment.

FIG. 4 shows a first film feeding device for a camera according to the present invention.
3 shows a block diagram of an embodiment.

[Explanation of symbols]

 1: Microcomputer 2: Motor driver 3: Motor 4: Photoreflector 5: Constant current circuit

Claims (3)

[Claims] 1. An optical sensor for optically detecting a perforation of a film fed by a film feeding means, and detection information from the optical sensor is digitally converted at every time set in a timer means, and the digital conversion is performed. In a film feeding device of a camera having a perforation counting means for comparing the converted value with a threshold value and counting the perforation, the perforation counting means judges that the film feeding speed is low, the timer means. A film feeding device for a camera, which is characterized in that the setting time of is increased. 2. An optical sensor for optically detecting the perforation of the film fed by the film feeding means, and detection information from the optical sensor is digitally converted at every time set in the timer means, and the digital conversion is performed. In a film feeding apparatus of a camera having a perforation counting means for comparing the converted value with a threshold value and counting the perforation, the perforation counting means determines that the first film feeding speed is low. A film feeding device for a camera, wherein an average value of a sum of a conversion value and a second conversion value converted thereafter is compared with a threshold value. 3. An optical sensor for optically detecting the perforation of the film fed by the film feeding means, and detection information from the optical sensor is digitally converted at every time set in the timer means, and the digital conversion is performed. In a film feeding device of a camera having a perforation counting means for comparing the converted value with a threshold value and counting the perforation, the perforation counting means judges that the film feeding speed is low when the perforation counting means judges that the film feeding speed is low. A film feeding device for a camera, characterized in that the level is changed to a level less susceptible to noise included in detection information from the optical sensor.