JPH10186498A - Camera using magnetically recordable film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately judge whether it is an unexposed frame or an exposed frame by reproducing magnetic data recorded in each frame of film. SOLUTION: The moving speed of a film 10 at the time of winding the film by a winding spool 15 is detected, the number of frames of the film 10 wound by the spool 15 is detected, and the rotating speed of a motor 9 driving the spool 15 is calculated according to a moving speed detected value and a wound frame number detected value concerning the film 10. The threshold is changed in accordance with the calculated value of the rotating speed and the magnetic data recorded on each frame of the film 10 is transduced into an electrical signal, and then the transduced signal is compared with the threshold and whether it is the exposed frame or the unexposed frame is judged according to the compared result. Thus, the unexposed frame is accurately detected without adding a special equipment for detecting a noise level such as an A/D converter, and program-searching the unexposed frame is accurately performed when a film cartridge exposed halfway is reloaded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a camera using a magnetically recordable film.

[0002]

2. Description of the Related Art There is known a camera which magnetically records data on a magnetically recordable film as a digital signal obtained by pulse position modulation (for example, Japanese Patent Application Laid-Open No. 7-1993).
No. 24). In this type of camera, calendar information such as date and time, and shooting information such as aperture and shutter speed are magnetically recorded on a film. The magnetic recording information is information determined after photographing each frame, and the information of each frame is recorded in a magnetic recording unit set for each frame.

[0003] Further, using a film provided with two perforations on each frame, the moving speed of the perforation is measured by a photo sensor while feeding the film,
There is known a method of calculating a recording frequency based on a moving speed to perform magnetic recording (for example, Japanese Patent Application Laid-Open No. 6-33206).
No. 5).

On the other hand, in a camera that electrically feeds a film, the film is wound up by one frame for each photographing, and the film is rewound to the cartridge when the photographing of the last frame is completed. When magnetically recording photographed data on film with this electric camera, the photographed data determined at the time of exposure of each frame is stored in memory, and when the film is rewound, the photographed data is collectively recorded in the magnetic recording unit of each frame. There is a way to do it.

In the above-mentioned electric camera, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Application Laid-Open No. 71433, when a film taken halfway is reloaded, data recorded magnetically on each frame is reproduced to determine whether the frame is a photographed frame or an unexposed frame. Then, the film is fed to the unexposed frame.

In order to reload a film that has been photographed halfway and locate the unexposed frame, very small magnetic data recorded on the film must be reproduced and read.
Since the reading of the magnetic data is performed during the feeding of the film by the motor, there is a possibility that accurate reading of the data may not be possible due to the mixing of the magnetic noise and the brush noise of the motor during the reading. Therefore, generally, the number of pulses of the reproduction signal is counted, or the reproduction signal is integrated to detect a signal difference between a portion having no magnetic recording and a portion having magnetic recording to determine an unexposed frame.

[0007]

However, since the magnitude of the motor noise and the reproduction signal change depending on the number of rotations of the motor and the feeding speed of the film, the number of rotations of the motor and the feeding speed of the film depend on the power supply voltage and the ambient temperature. However, there is a problem in that a camera in which the unexposed frame is determined by comparing the reproduced signal with a certain threshold value tends to cause an erroneous determination.

Therefore, it is conceivable to measure a noise level in a portion where there is no magnetic recording and determine a threshold for judging a reproduced signal based on the measurement result. A D converter and the like are required, and the cost increases.

SUMMARY OF THE INVENTION It is an object of the present invention to reproduce magnetic data recorded on each frame of a film and accurately determine whether the frame is unexposed or exposed.

[0010]

[Means for Solving the Problems]

(1) A conversion means for converting magnetic data recorded on each frame of a film into an electric signal, a comparison means for comparing an output signal of the conversion means with a threshold value, and a comparison between the comparison means A camera using a magnetically recordable film, comprising: a determination unit for determining whether an exposed frame or an unexposed frame based on a result, wherein the moving speed detects a moving speed of the film when the film is wound by a winding spool. Detecting means, a frame number detecting means for detecting the number of frames wound on the winding spool, and a rotation speed for calculating a rotation speed of a motor for driving the winding spool based on the film moving speed detection value and the frame number detection value. Calculating means, and a threshold value changing means for changing the threshold value according to the rotation speed calculation value. Detects the moving speed of the film when the film is wound by the winding spool. The rotation speed of the motor to be operated is calculated. Then, while changing the threshold value according to the rotation speed calculation value, the magnetic data recorded on each frame of the film is converted into an electric signal, the converted signal is compared with the threshold value, and the exposure is performed based on the comparison result. It is determined whether the frame is an already-exposed frame or an unexposed frame. The magnetic noise and brush noise generated from the film winding motor are shown in FIG.
As shown in the actual measurement results shown in FIG. Therefore, the rotation speed of the film winding motor is calculated based on the moving speed of the film, the number of winding frames, and the winding radius of the winding spool, and the threshold value is changed according to the rotation speed. Compare. This makes it possible to accurately detect an unexposed frame without adding a special device such as an A / D converter for detecting a noise level. The cue of a piece can be accurately performed. Usually, the moving speed of the film and the number of winding frames are physical quantities detected for controlling the feeding of the film. Therefore, by estimating the motor rotation speed based on these physical quantities, the encoder or the like is used to wind the motor or the film. It is not necessary to directly detect the motor rotation speed in addition to the mechanism, so that cost increase can be avoided. (2) A camera using a magnetically recordable film according to claim 2, further comprising a perforation detecting means for detecting the perforation of the film, wherein the moving speed detecting means determines a moving speed of the film based on a perforation detection result by the perforation detecting means. The frame number detecting means detects the number of winding frames of the film based on the perforation detection result by the perforation detecting means. (3) A camera using a magnetically recordable film according to claim 3, further comprising a moving amount detecting means for detecting a moving amount of the film, wherein the moving speed detecting means is based on a film moving amount detected value by the moving amount detecting means. The moving speed of the film is detected, and the number-of-frames detecting means detects the number of winding frames of the film based on the detected value of the moving amount of the film by the moving amount detecting means. (4) The invention according to claim 4 is a conversion means for converting magnetic data recorded on each frame of the film into an electric signal, a comparison means for comparing an output signal of the conversion means with a threshold value, and a comparison between the comparison means. A camera using a magnetically recordable film, comprising: a determination unit for determining whether an exposed frame or an unexposed frame based on a result, and a rotation speed detection unit for detecting a rotation speed of a film feeding motor. Threshold value changing means for changing the threshold value in accordance with the rotation speed detection value. The rotation speed of the film feeding motor is detected, and the threshold value is changed according to the detected rotation speed value. Then, the magnetic data recorded on each frame of the film is converted into an electric signal,
The conversion signal is compared with a threshold value to determine whether the frame is an exposed frame or an unexposed frame based on the comparison result. Magnetic noise and brush noise generated from the film winding motor change according to the rotation speed of the motor as shown in the measurement results shown in FIG. Therefore, the rotation speed of the film feeding motor is detected, the threshold value is changed according to the rotation speed, and compared with the electric signal of the magnetic data. This makes it possible to accurately detect unexposed frames without adding a special device such as an A / D converter for detecting a noise level. The cue of a piece can be accurately performed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, referring to FIG. 1, the relationship between a magnetization pattern and data and the relationship between a magnetization pattern and a read voltage of a magnetic head when a digital recording method is used for recording magnetic data will be described. (A) shows the current waveform of the magnetic head when data is recorded by the pulse position method. The pulse position data means that the time T0 from the time when the current flowing through the magnetic head is reversed from the direction to the direction to the time when the current is reversed again from the direction to the direction is defined as one bit. → If the time of inversion in the direction is the first half of the one-bit time T0, data “0”;
1 ".

FIG. 3B shows the magnetization state of the magnetic recording surface when the data shown in FIG. (C)
FIG. 6 shows a voltage waveform when the magnetization pattern shown in FIG. An electromotive force is generated in the magnetic head at the position where the magnetization pattern changes, and the direction of the electromotive force differs depending on the direction of the change in the magnetization pattern.

Next, the relationship between the motor noise and the amplitude of the magnetic read signal will be described with reference to FIG. FIG.
7C shows a waveform when noise is superimposed on the output voltage waveform of FIG. In this example, since the amplitude of the noise is ± 1 and the amplitude of the reproduction signal is +2 and −2, if a threshold value is provided between +1 and +2 and between −1 and −2, the reproduction signal and the noise Can be accurately determined. (B) shows an output voltage waveform when the motor rotation speed is higher and the film feeding speed is higher than in (a). In this example, since both the magnetic flux of the noise and the signal magnetic flux change more rapidly than in the case of (a), the amplitude of the noise increases to ± 2, and the amplitude of the reproduced signal increases to +4 and -4. Therefore, unless a threshold value is provided between +2 and +4 and between -2 and -4, the reproduced signal and noise cannot be determined. That is, the same threshold value as in (a) cannot be used.

FIG. 3 shows the configuration of one embodiment. A microcomputer (hereinafter, referred to as an MCU) 1 performs various calculations and controls of the camera. The magnetic signal read circuit 2 reproduces and reads a magnetic signal by scanning the magnetic recording portion of the film 10 with the magnetic head 6. The magnetic signal readout circuit 2 includes an amplifier 13 having a filter function for high frequencies.
And a comparator 14 configured so that the threshold value can be varied by the D / A output of the MCU 1, and outputs the read magnetic signal to the MCU 1. The film feeding circuit 3
The film feed motor 9 is controlled according to a command from the CU 1. The film feeding motor 9 drives the film winding spool 15 to wind the film 10.

The magnetic recording circuit 4 uses the magnetic head 6 to write photographic information in the magnetic recording section of the film 10. EEP
The ROM 5 is a non-volatile memory that retains stored information even when the power of the camera is turned off. Reflection type photo sensor 7,
8 outputs to the MCU 1 a signal of a level corresponding to the reflectivity between the rail surface 11 and the film surface viewed through the perforation of the film 10. The MCU 1 detects the position of the film 10 and the feeding speed based on this signal. The film cartridge 12 has a data disk (not shown). MCU1 is a type of film recorded on a data disk by a data reading device (not shown),
Reads information such as sensitivity and number of frames that can be shot. The MCU 1 is further connected to devices for performing photometry, distance measurement, shutter control, aperture control, display, storage, and the like, but these are not directly related to the present invention, and thus illustration and description thereof are omitted.

FIG. 4 shows the arrangement of the photo sensors 7, 8 and the magnetic head 6 with respect to the magnetically recordable film 10.
10a is a film exposure range, 10b is a perforation indicating the start position of the film exposure range, 10c is a perforation indicating the end of the film exposure range, 1
0d is a magnetic recording unit. The magnetic head 6 includes the film 1
0 is disposed at a position passing the magnetic recording unit 10d. In addition,
The magnetic recording data must be recorded in the magnetic recording section 10d of the film 10. The photo sensors 7 and 8 are arranged at positions where the perforations 10b and 10c of the film 10 pass.

FIG. 5 shows the relationship between the number of rotations of the film motor 9 and the magnetic noise generated by the motor.
, And the vertical axis represents the voltage amplitude after amplification by the amplifier 13. The magnetic noise due to the motor 9 increases as the rotation speed of the motor increases and the speed at which the leaked magnetic poles reverse increases, and at the same time, the frequency of the magnetic noise increases as the rotation speed increases. The frequency characteristic of the amplifier 13 has a characteristic of filtering a signal having a frequency higher than the frequency of the original magnetic signal. Therefore, the relationship between the number of rotations of the film motor 9 and the voltage amplitude after the magnetic noise generated by the motor is amplified by the amplifier 13 is a curve as shown in FIG. This curve shows the structure of the feed motor 9 and the amplifier 1
The frequency characteristic is determined by the frequency characteristic of No. 3 and, in practice, an approximate expression or a table for the actually measured value is used. This approximate expression or table is stored in a ROM (not shown) in the MCU 1.

FIG. 6 shows the relationship between the number of winding frames of the film 10 and the radius r of the winding spool 15. As the number of frames wound up by the spool 15 increases, the radius of the spool 15 increases due to the thickness of the film 10, so that the relationship shown in FIG. 6 is obtained. This curve is
And the thickness of the film 10. In practice, it is appropriate to use a table of the radius r with respect to the number of frames.

From the above, the current spool radius is obtained from FIG. 6 based on the current number of frames, and the film moving speed S at that time is detected. 9 are obtained.

M = k · (S / 2πr) [rpm] Here, k is a proportional constant between the rotation speed of the feeding motor and the rotation speed of the take-up spool. Further, the noise amplitude E with respect to the motor speed M [rpm] using the relationship of FIG.
[V] can be obtained.

The flowcharts shown in FIGS.
The operation of the embodiment will be described with reference to a time chart shown in FIG. In this case, the film is exposed up to the 8th frame,
The operation when the magnetically recorded “film cartridge in the middle of shooting” is reloaded into the camera will be described as an example. FIG. 7 is a flowchart showing the processing of the microcomputer 1 when the cartridge is loaded in the camera. In a step 101, a variable CNT1F (described later) is cleared to 0, and in a subsequent step 102, the driving of the feeding motor 9 in the winding direction (forward rotation) is started (point a in FIG. 12). Thereby, both the spool of the film cartridge 12 and the take-up spool 15 shown in FIG. 3 start rotating clockwise, and the leading end of the film 10 is pushed out of the cartridge 12. Further, when the film 10 is extruded, the leading end of the film 10 winds around the take-up spool 15,
The film 10 is wound by a winding spool 15 and moves from right to left in FIG.

In step 103, the value of the timer counter TMR is cleared to 0, and time counting is started. In step 104, wait until the value of the variable CNT1F becomes 3, and
When the value of TIF becomes 3, the process proceeds to step 105.

Here, variables CNT1F and CNT2F
Indicates the count value of the falling edge of the output which occurs when the photosensors 7 and 8 detect the passage of the leading edge of the film and the perforation, that is, the number of times the leading edge of the film and the end of the perforation aperture have passed. These counting processes are respectively performed by the INT shown in FIG.
This is performed by one falling interrupt and the INT2 falling interrupt shown in FIG. The output of the photo sensor 7 is M
8 is started at the falling edge of the output of the photosensor 7 and the variable CNT1F is incremented at step 801. The output of the photo sensor 8 is the MCU 1
10 is started at the falling edge of the output of the photo sensor 8, and the variable CNT2F is incremented in step 1001.

On the other hand, the variables CNT1R and CNT2R indicate the count value of the rising edge of the output of the photosensors 7 and 8, that is, the number of times the tip of the perforation opening has passed. These counting processes correspond to the INT1 rising interrupt shown in FIG. 9 and the INT2 rising interrupt shown in FIG.
This is performed by a rising interrupt. The interrupt processing shown in FIG. 9 is started at the rising edge of the output of the photosensor 7, and the variable CNT1R is incremented in step 901. Similarly, at the rising edge of the output of the photo sensor 8, the interrupt processing shown in FIG.
At 101, the variable CNT2R is incremented.

When the film 10 is correctly fed, FIG.
At the point b in the time chart shown in FIG. 7, the output of the photosensor 7 falls once as the leading end of the film 10 passes through the position of the photosensor 7. Further, when the film 10 moves, the second perforation of the film 10 at the point c in FIG. 12, that is, the end of the perforation 10b located on the leading end side of the first piece passes through the position of the photosensor 7, so that the variable CNT1F
Becomes 3. The position of the film 10 is exactly the photographing preparation position of the first frame. In step 105, the variable FCNT representing the film counter is initialized to 1, and in the following step 106, the value of the variable FCNT is stored in the EEPROM 5.

In step 111, the variables CNT1F,
CNT2F and CNT2R are cleared to 0, and in the following step 112, the process waits until the value of the variable CNT2R becomes 1. FIG.
At point d in the time chart shown in FIG.
Reaches the position of the photosensor 8, the variable CNT2R becomes 1, and the first perforation
Proceed to 13. In step 113, the timer counter TM
Clear R to 0 and start time counting again.
Next, at step 114, the process waits until the variable CNT2R becomes 2. Film 10 up to point e in the time chart of FIG.
Is sent, the second perforation of the film 10 reaches the position of the photosensor 8, the variable CNT2R becomes 2, and the routine proceeds to step 115. In step 115, the time counting of the timer counter TMR is stopped.

At step 116, the timer counter TMR
From the D / A terminal of MCU1 using the value of
4 is determined. The value of the timer counter TMR at this time indicates the time that the film 10 travels from the leading end of the first perforation opening to the leading end of the second perforation opening. Since the perforation interval is a fixed value, the timer counter TMR
Then, the moving speed of the film 10 is obtained from the running time counted and the perforation interval, and the noise amplitude of the motor 9 is obtained by using the above-described formula 1 and the relationship between FIGS. Then, a value larger than the calculated noise amplitude is determined as the threshold value, and the comparator 14
Output to

In step 118, the process waits until the variable CNT2F becomes 2. When the film 10 is fed to the point f in the time chart of FIG. 12, the end of the second perforation opening reaches the position of the photosensor 8, and the variable CNT2F
Becomes 2, and the routine proceeds to step 119. Here, the point f is also immediately before the magnetic track 10 d of the first frame approaches the magnetic head 6. In step 119, the variable CNTH is set to 0.
Then, counting of the pulses input to the CNT terminal of the MCU 1 is started. This variable CNTH indicates a value obtained by counting the number of pulses input to the CNT terminal by hardware. The output of the magnetic signal read circuit 2 is connected to the CNT terminal of the MCU 1.
Then, the magnetic data recorded in the magnetic recording section at the time of film feeding is detected via the reproducing head 6, amplified by the amplifier 13 and compared with the threshold by the comparator 14, and a magnetic signal equal to or larger than the threshold is detected. Output to the CNT terminal of MCU1.

At step 120, the value of the variable CNT1F becomes 2
Wait to become. If the normal operation is performed, FIG.
At the time point h, when the end of the first perforation (for example, 10b) of the next frame of the film 10 has passed the position of the photosensor 7, CNT1F becomes 2 and step 1
Proceed to 21. In step 121, it is determined whether or not the content of the variable CNTH exceeds 200. At this time, the variable CNTH indicates the number of pulses of the magnetic reproduction signal generated during the transmission of one frame of the film 10. If the frame is an exposed frame, more than 200 pulses of the magnetic reproduction signal enter the variable CNTH, and In the case of exposure frames, the value of the variable CNTH becomes a value of 200 or less due to only slightly mixed noise. If the variable CNTH exceeds 200 and the frame has been exposed, the process proceeds to step 122. If the variable CNTH is 200 or less and the frame has not been exposed, the process proceeds to step 131.

Here, a film cartridge which has been exposed up to the eighth frame and is being photographed is described as an example.
The first frame has been exposed.
A magnetic reproduction signal as shown at points f to g is input to the CNT terminal. If an exposed frame is detected, step 12
In step 2, the film counter FCNT is incremented. In step 123, the content of the variable FCNT is stored in the EEPROM.
To memorize. After that, the process returns to step 111 and the operations of steps 111 to 123 are repeated.

In the time chart shown in FIG.
At the points i,..., 200 or more magnetic reproduction signals are generated, and thus the frame is an exposed frame. Only after reaching the point k in FIG. 12 corresponding to the ninth frame, 200 or less unexposed frames are detected by the magnetic reproduction signal. When an unexposed frame is detected,
In step 131, short-circuit brake is applied to the feed motor 9,
In the subsequent steps 132 and 133, a wait of 20 ms is waited (point m in FIG. 12). The position of the film 10 at this point is a position where the perforation of the exposure start position of the tenth frame has finished passing through the position of the photosensor 7, and has passed the exposure position of the first unexposed frame. Therefore, one frame must be rewound from here. Step 1
In step 34, the variable CNT1R is cleared to 0, and in step 135, the feed motor 9 is driven to rotate in the reverse direction. As a result, the film 10 starts moving in the rewinding direction.

In step 136, the value of the variable CNT1R becomes 3
, And when the variable CNT1R becomes 3, the routine proceeds to step 137. If the normal operation is performed, FIG.
At point n, the film 10 is rewound by one frame, and the opening end of the third perforation passes through the position of the photosensor 7, so that the variable CNT1R becomes 3. At step 137, a short-circuit brake is applied to the feed motor 9; at steps 138 to 139, a wait of 50 ms is waited; and at step 140, the power supply to the feed motor 9 is released (FIG. 12).
O point). At this time, the first unexposed frame is set at the shooting preparation position. In step 141, the film counter FC
The value of NT is transferred to the variable SCNT. In other words, the first photographed frame of the loaded film cartridge in the middle of photographing is the first unexposed frame, and its frame number is stored. In step 142, the value of the variable SCNT is stored in the EEPROM 5, and the film loading process ends.

Thereafter, the film is actually photographed from the frame in the photographing ready state, the film is wound up by one frame for each photographing, and the photographing information of each frame is stored in the memory. Then, when the shooting has been completed up to the last frame or when the user performs a rewind operation, the shooting information is magnetically recorded for each frame up to the first frame shot this time while reading the shooting information from the memory. Since these operations are not directly related to the present invention, detailed description will be omitted.

In the above-described embodiment, the rotation speed of the motor is calculated from the film feeding speed in order to detect the rotation speed of the motor without adding a new member. A similar effect can be obtained by providing a sensor for detecting the rotation speed of the motor and directly detecting the rotation speed of the motor. Further, in the above-described embodiment, an example in which the moving speed of the film and the number of winding frames are detected based on the detection result of the perforation has been described.However, for example, the moving amount of the film is detected by a film encoder, and the film per unit time is detected. The moving speed of the film may be detected based on the moving amount, and the number of winding frames may be detected based on the moving amount of the film.

In the configuration of the above embodiment of the present invention,
The magnetic head 6 is a converting means, the comparator 14 is a comparing means, the microcomputer 1 is a determining means, a rotation speed calculating means and a threshold value changing means, and the photo sensors 7, 8 and the microcomputer 1 are a moving speed detecting means and a frame. The photo sensors 7 and 8 constitute the perforation detecting means, and the number detecting means constitutes the perforation detecting means.

[0035]

As described above, according to the present invention,
Detects the moving speed of the film when the film is wound by the winding spool, detects the number of frames of the film wound on the winding spool, and drives the winding spool based on the detected value of the moving speed of the film and the detected number of frames. The rotation speed of the motor to be operated is calculated. Then, while changing the threshold value according to the rotation speed calculation value, the magnetic data recorded on each frame of the film is converted into an electric signal, the converted signal is compared with the threshold value, and the exposure is performed based on the comparison result. Since it is determined whether the frame has been exposed or not, the unexposed frame can be accurately detected without adding a special device such as an A / D converter for detecting a noise level. When the film cartridge in the middle is reloaded, the cueing of the unexposed frame can be accurately performed. Usually, the moving speed of the film and the number of winding frames are physical quantities detected for controlling the feeding of the film. Therefore, by estimating the motor rotation speed based on these physical quantities, the encoder or the like is used to wind the motor or the film. It is not necessary to directly detect the motor rotation speed in addition to the mechanism, so that cost increase can be avoided. Further, according to the present invention, the rotation speed of the film feeding motor is detected,
The threshold value is changed according to the rotation speed detection value. And
Since the magnetic data recorded on each frame of the film is converted into an electric signal, and the converted signal is compared with a threshold to determine whether an exposed frame or an unexposed frame based on the comparison result,
Unexposed frames can be accurately detected without adding special equipment such as an A / D converter for detecting the noise level, and the unexposed frames are caught when a film cartridge in the middle of shooting is reloaded. Can be performed accurately.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a magnetization pattern and data and a relationship between a magnetization pattern and a read voltage of a magnetic head when a digital recording method is used for recording magnetic data.

FIG. 2 is a diagram illustrating a relationship between motor noise and the amplitude of a magnetic read signal.

FIG. 3 is a diagram illustrating a configuration of an embodiment.

FIG. 4 is a diagram showing an example of the arrangement of a photosensor and a magnetic head on a magnetically recordable film.

FIG. 5 is a diagram showing a relationship between the number of rotations of a film feed motor and magnetic noise caused by the motor.

FIG. 6 is a diagram showing a relationship between the number of film winding frames and a radius r of a winding spool.

FIG. 7 is a flowchart showing a film loading process.

FIG. 8 is a flowchart showing processing at the time of INT1 falling interrupt.

FIG. 9 is a flowchart showing processing when an INT1 rising interrupt occurs.

FIG. 10 is a flowchart showing processing at the time of INT2 falling interrupt.

FIG. 11 is a flowchart showing processing at the time of INT2 rising interrupt.

FIG. 12 is a time chart showing outputs of a motor, a photo sensor, and a comparator when the film is fed after the film is loaded.

[Explanation of symbols]

 Reference Signs List 1 microcomputer (MCU) 2 magnetic signal reading circuit 3 film feeding circuit 4 magnetic recording circuit 5 EEPROM 6 magnetic head 7, 8 photosensor 9 film feeding motor 10 film 10a exposure range 10b, 10c perforation 10d magnetic recording unit 11 Rail surface 12 Cartridge 13 Amplifier 14 Comparator 15 Winding spool

Claims (4)

[Claims] A converter for converting magnetic data recorded on each frame of the film into an electric signal; a comparator for comparing an output signal of the converter with a threshold; and a comparison result of the comparator. A camera using a magnetically recordable film, comprising: a determination unit for determining whether the frame is exposed or unexposed; and a moving speed detecting unit that detects a moving speed of the film when the film is wound by a winding spool. Frame number detecting means for detecting the number of frames wound on the winding spool; rotation for calculating a rotation speed of a motor for driving the winding spool based on the film moving speed detection value and the frame number detection value. Using a magnetically recordable film, comprising: speed calculation means; and threshold value changing means for changing the threshold value according to the rotation speed calculation value. Camera. 2. A camera using a magnetically recordable film according to claim 1, further comprising a perforation detecting means for detecting perforation of the film, wherein said moving speed detecting means is based on a perforation detection result by said perforation detecting means. A camera using a magnetically recordable film, wherein the number of frames detecting means detects the number of winding frames of the film based on a perforation detection result by the perforation detecting means. 3. A camera using a magnetically recordable film according to claim 1, further comprising a movement amount detection means for detecting a movement amount of the film, wherein the movement speed detection means moves the film by the movement amount detection means. Magnetic recording capable of detecting a moving speed of the film based on the detected amount of the film, wherein the number-of-frames detecting means detects the number of winding-up frames of the film based on the detected value of the film moving amount by the moving-amount detecting means. Cameras using various films. 4. A converting means for converting magnetic data recorded on each frame of the film into an electric signal, a comparing means for comparing an output signal of the converting means with a threshold value, and based on a comparison result of the comparing means. A camera using a magnetically recordable film, comprising: a determination unit that determines whether the frame is exposed or unexposed, and a rotation speed detection unit that detects a rotation speed of a film feeding motor; A camera using a magnetically recordable film, comprising: threshold changing means for changing the threshold according to a speed detection value.