JPH1031253A - Camera with film detection device - Google Patents

Abstract

(57) [Problem] To provide a camera with a film detecting device capable of reliably recognizing a film feeding state. SOLUTION: A light emitting element 15a for projecting light on a film F to be fed, a light receiving element 15b for receiving light from the light emitting element 15a, and light emission based on a magnitude relationship between a light receiving amount of the light receiving element 15b and a predetermined light amount threshold value. Film F facing element 15a
And a CPU 1 for increasing or decreasing the light amount of the light emitting element 15a in accordance with the presence or absence of the film F facing the light emitting element 15a so that the difference between the light receiving amount and the light amount threshold value increases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera with a film detecting device for detecting a film feeding state.

[0002]

2. Description of the Related Art There is known a camera for detecting a film feeding state using a photo sensor. With this camera,
The presence or absence of a film and perforation are detected by comparing the amount of light received by the light receiving element of the photo sensor (output voltage of the light receiving element) with a predetermined threshold light amount (threshold voltage).

[0003]

However, if the change in the amount of light received by the light receiving element is small, or if the maximum or minimum value of the change is close to the threshold, the chatter signal or noise may be reduced. Therefore, there is a problem that the feeding state of the film is erroneously recognized.

It is an object of the present invention to provide a camera with a film detecting device capable of reliably recognizing a film feeding state.

[0005]

FIG. 1 shows an embodiment of the present invention.
3 will be described with reference to FIG. 3. According to the first aspect of the present invention, there is provided a light projecting means 15a for projecting light onto a fed film F.
And light receiving means 15b for receiving light from the light emitting means 15a
And detecting means 1 and 6 for detecting the presence or absence of the film F facing the light projecting means 15a based on the magnitude relationship between the light receiving amount of the light receiving means 15b and a predetermined light amount threshold value, and the difference between the light receiving amount and the light amount threshold value increases. As described above, the above-described object is achieved by including the control unit 1 that increases or decreases the light amount of the light projecting unit 15a in accordance with the presence or absence of the film F facing the light projecting unit 15a. According to a second aspect of the present invention, there is provided a light projecting means 15a for projecting light on the fed film F, a light receiving means 15b for receiving light from the light projecting means 15a, a light receiving amount of the light receiving means 15b and a predetermined light quantity. Detecting means 1 and 6 for detecting the edge of the perforation 12 of the film F by recognizing that the magnitude relationship with the threshold is reversed; and detecting the perforation 12 following the first edge when the first edge of the perforation 12 is detected. So that the difference between the light amount threshold for detecting the second edge and the received light amount becomes large.
The above-mentioned object is achieved by providing the control means 1 for increasing and decreasing the amount of light.

According to the first aspect of the present invention, the light quantity of the light projecting means 15a is increased or decreased according to the presence or absence of the film F facing the light projecting means 15a so that the difference between the light receiving quantity and the light quantity threshold value becomes large. According to the second aspect of the present invention, when the first edge of the perforation 12 is detected, the difference between the light amount threshold for detecting the second edge of the perforation 12 following the first edge and the received light amount is large. Thus, the light amount of the light projecting means 15a is increased or decreased.

In the means and means for solving the above problems which explain the constitution of the present invention, the drawings of the embodiments are used to make the present invention easy to understand. However, the present invention is not limited to this.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a camera with a film detecting device according to the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing a camera according to the present embodiment. In FIG. 1, 1 is a CPU (one-chip microcomputer), 2 is an LCD display device, 3
Is a cartridge lid switch that is turned on and off in conjunction with the opening and closing operation of a cartridge lid that opens and closes the film cartridge chamber, 4 is a release switch that is turned on when a release button is pressed, and 5 is a nonvolatile memory (E) that stores various information. ² PROM), 6 is a photosensor circuit for detecting the feeding state of the film F described later, 7 is a motor for feeding the film F, and 8 is a motor drive circuit for driving the motor 7.

FIG. 2 shows a film used in the camera of this embodiment. In FIG. 2, the film F is wound around a spool shaft of a cartridge (not shown) and stored in the cartridge. When the spool shaft rotates in a predetermined direction by the forward rotation of the motor 8, the film F in the cartridge is pushed out of the cartridge and sent out in the P direction. When the spool shaft rotates in the opposite direction due to the reverse rotation of the motor 8, the film F is fed in the Q direction and rewound into the cartridge. As shown in FIG. 2, the film F has two rectangular perforations 1 for each video recording unit 11 for one frame.
2 is formed, and a trapezoidal cutout 13 is formed at the leading end of the film F.

A photosensor circuit 6 shown in FIG. 3 includes a photosensor (photoreflector) 15 including a light emitting element (LED) 15a and a light receiving element 15b, and a transistor T.
r1, Tr2 and resistors R1, R2, R3. Note that the resistance values of the resistor R1 and the resistor R2 are equal. The base of the transistor Tr1 is the port P of the CPU1.
1, the base of the transistor Tr2 is connected to the port P2 of the CPU 1, and the output terminal of the photosensor 15 is connected to the port P0 of the CPU 1.

As shown in FIG. 3, a light emitting device (LED) 1
The anode of 5a is connected to a power supply voltage (VDD) terminal,
The cathode of the light emitting element 15a is connected to one ends of the resistors R1 and R2. The other ends of the resistors 1 and 2 are connected to the ground terminal via the transistors Tr1 and Tr2, respectively.

When the port P1 is set to "H", the transistor Tr1 conducts, and when the port P1 is set to "L", the transistor Tr1 is turned off. When the port P2 is set to “H”, the transistor Tr2 is turned on, and when the port P2 is set to “L”, the transistor Tr2 is turned off. Since the light emitting element 15a has substantially constant voltage characteristics, the current supplied to the light emitting element 15a
And a value substantially inversely proportional to the resistance value of the combined resistance by the resistor R2. Therefore, transistors Tr1 and T
The current of the light emitting element 15a when both r2 are turned on is
The current is about twice as large as the current when only one of the transistors Tr1 and Tr2 is turned on. When both the transistors Tr1 and Tr2 are turned off, no current flows through the light emitting element 15a.

The photo sensor 15 is a film F to be fed.
Is provided at a position facing the perforation 12 of
A reflection plate is provided on the film rail surface facing the photo sensor 15. When the film F does not face the photosensor 15, the light emitted from the light emitting element 15a is reflected by the reflector and received by the light receiving element 15b. On the other hand, when the film F is opposed to the photo sensor 15, only a part of the light emitted from the light emitting element 15a passes through the film F, so that the amount of light returning to the light receiving element 15b decreases. The output current of the light receiving device 15b changes according to the amount of light received by the light receiving element 15b, and the current of the light receiving element 15b increases as the amount of light increases. When the output current of the light receiving element 15b increases, the voltage value of the port P0 increases. Therefore, it is possible to determine the presence or absence of the opposing film F from the voltage value of the port P0. In FIG. 2, a dashed line 151 on the film F indicates a position where the photosensor 15 is opposed.

Next, the operation of the camera according to the present embodiment will be described with reference to FIGS. <Main Routine> The sequence of the main routine shown in FIG. 4 is started when the power of the camera is turned on. In step S101, it is determined whether a film cartridge is loaded in the camera. If it is determined that it is loaded, the process proceeds to step S102, and if it is determined that it is not loaded, step S101 is repeated. When the film cartridge is loaded and the cartridge lid is closed, the cartridge lid switch 3 is turned off. Therefore, in step S101, if the cartridge lid switch 3 is off, the film cartridge is loaded, and if it is on, the film cartridge is loaded. Are determined as not loaded.

In step S102, step S200 is called to perform a thrust process. The thrust process is a process of extruding the film F from the cartridge until the first frame of the film F is in a shooting state. The details of the thrust processing will be described later.

In step S103, it is determined whether a thrust error has occurred in the thrust processing. If it is determined that no error has occurred, the process proceeds to step S104, and if it is determined that an error has occurred, step S108
Proceed to. In step S104, the process waits for the release switch 4 to be turned on. If it is determined that the release switch 4 has been turned on, the process proceeds to step S105.

In step S105, photographing is performed. Distance measurement and photometry of the subject are performed by a known method, and based on the results, the lens is extended to a focus position, and a shutter is opened for a predetermined time according to the photometry value. In addition, a strobe light is emitted as needed. The photographing is completed by these processes.

When the photographing is completed, the process proceeds to step S106, in which step S300 is called to perform a winding process. The winding process will be described later. Step S107
Then, it is determined whether or not the end of the film F is detected during the winding process. If it is determined that the terminal has not been detected, the process returns to step S104. If it is determined that the terminal has been detected, the process proceeds to step S108.

In step S108, the rewind processing 400 is called. In the rewinding process, the motor for winding the film F into the cartridge is stopped. After the rewinding process is completed, the user of the camera can open the cartridge cover and take out the cartridge. The cartridge lid switch 3 is turned on by removing the cartridge, but when the user loads the next new film F into the camera, the switch 3 is closed, and the process is restarted by proceeding from step S101 to step S102. The rewinding process will be described later.

<Thrust Processing> FIGS. 5 and 6 show the sequence of the thrust processing. As described above, the process proceeds from step S102 of the main routine to step S200,
Thrust processing is started. Step S20 shown in FIG.
At 0, the motor 7 is stopped, and the film F is wound in the cartridge. In step S201, a threshold for determining whether or not the film F faces the photo sensor 15 is set. This threshold value is a voltage value for determining whether or not the film F faces the photosensor 15 based on the magnitude relationship with the output value of the photosensor 15 (the voltage value of the port P0). The threshold value is set to, for example, a voltage value that is about 1/2 of the power supply voltage VCC shown in FIG.

In step S202, the ports P1 and P2 are set to "H". Time a shown in FIG. 7 corresponds to the operation in step S202. In step S203, the normal rotation of the motor 7 is started, and subsequently, in step S204, the thrust error detection timer is set to 8 seconds, and time measurement is started. In step S205, the thrust error detection timer is read. If it is determined that the time of the thrust error detection timer has expired, the process proceeds to step S218 (FIG. 6), and if it is determined that the time has not expired, the process proceeds to step S206. Step S206
In step, the magnitude of the voltage value of the port P0 and the threshold value are determined, and if it is determined that the voltage value of the port P0 is higher, the process proceeds to step S207, and if it is determined that the threshold value is higher, the process returns to step S205. Note that the above-described step S206
Then, by comparing the voltage value of the port P0 with the threshold value,
It is determined whether or not the leading end of the film F has reached the position of the photo sensor 15. If the error detection timer has expired in step S205, it means that the leading end of the film F has not been detected within a predetermined time. In this case, it is determined that a thrust error has occurred. Step S205 and step S2
Since the processing speed of 06 is sufficiently fast, the arrival of the leading end of the film F is immediately detected in step S206.

If it is determined in step S206 that the leading end of the film F has been detected, the flow advances to step S207. In step S207, the port P2 is switched to "L" while the port P1 is maintained at "H", and the transistor Tr2 is turned off. To As a result, the current of the light emitting element 15a is reduced to about 1/2.
To reduce the light emission amount of the light emitting element 15a. As shown by the one-dot chain line 151 in FIG. 2, the detection position of the photo sensor 15 may be located on the notch 13, but if the light amount of the light emitting element 15a is reduced, the notch 13 cannot be detected. There is no risk of misrecognition as 12. That is, as shown in FIG. 9, when the port P1 is set to “H” and the port P2 is set to “L”, the voltage value of the peak 13B when the notch 13 passes is the peak value when the perforation 12 passes. It is smaller than the voltage value, and the voltage value of the peak 13B does not reach the threshold value. This is because a part of the light emitted from the light emitting element 15 a is blocked around the notch 13, so that the light receiving element 1 is more visible than when the photo sensor 15 faces the perforation 12.
This is because the amount of received light of 5b decreases. In the present embodiment, since the port P2 is switched from “H” to “L” at time b in FIG. 7, the peak 13A corresponding to the notch 13 does not reach the threshold, and the notch 13 is not detected. Note that, as shown in FIGS.
Has the same waveform as that of FIG. 8 from time a to time b, and has the same waveform as that of FIG. 9 after time b.

In step S207 of FIG.
After switching the current of No. 5, the process proceeds to step S208 shown in FIG. In step S208, the thrust error detection timer is reset to 8 seconds, and time measurement is started. Next, step S
In 209, the thrust error detection timer is read, and if it is determined that the time of the thrust error detection timer has expired, the process proceeds to step S218, and if it is determined that the time has not expired, the process proceeds to step S210. In step S210, the voltage value of the port P0 is compared with the threshold value. If it is determined that the magnitude relationship between the voltage value of the port P0 and the threshold value has been reversed from the previous time, it is determined that the edge of the perforation 12 has been detected, and the process proceeds to step S211. If it is determined that the rotation has not been reversed, it is determined that no edge has been detected, and the process returns to step S209. Step S211
By switching the port P2 from “L” to “H” or from “H” to “L”, the light amount of the light emitting element 15a is switched. In step S212, step S210
Is counted, and if it is determined that the current edge is the fourth edge, the process proceeds to step S213.
Proceed to. If it is determined that the current edge is not the fourth edge, the process returns to step S208.

The above steps S209 to S21
The change in the voltage value of the port P0 due to the operation 2 will be described with reference to FIG. The port P2 is maintained at “L” from the time when the leading edge of the film F is detected (Step S206, Step S207) to the time when the perforation edge is first detected (Step S210, Step S211). Therefore, from the time point b to the time point c, the voltage waveform of the port P0 is the same as the waveform shown in FIG.

When the first edge is detected in step S206, the port P2 is switched from "L" to "H" in step S211 at time c (FIG. 7). The waveform is the same as the waveform shown in FIG. When the second edge is detected in step S210 (time d), the port P2 is switched from "H" to "L" again, and the voltage waveform of the port P0 after the time d is the same as that shown in FIG. Becomes Further, the port P2 is switched to "H" by detecting the third edge (time e) and to "L" by detecting the fourth edge (time f) at each time.
As described above, every time a perforation edge is detected, the voltage of the port P2 switches between “L” and “H”, and the light amount of the light emitting element 15a changes according to the switching. Therefore, the voltage waveform at the port P0 is a combination of the waveforms shown in FIGS. 8 and 9, and the amplitude increases as shown in FIG.

After four perforation edges have been detected, if it is determined in step S212 that four edges have been detected as shown in FIG. 6, the flow advances to step S213. In step S213, the motor 7 is stopped. In the following step S214, the motor 7 is driven for a predetermined time (about 5 ms).
The brake is applied by applying a reverse voltage to. Further, in step S215, the terminal of the motor 7 is short-circuited for a predetermined time (about 80 ms) to apply a brake, and the film F
Stop feeding completely. At this time, the first frame of the film F faces the aperture surface. In step S216, "1" is displayed on the film counter of the display device 2.
Next, the process returns from step S216 to step S103 in FIG.

As described above, when it is determined in step S205 or S209 that the error detection timer has expired, it is determined that a thrust error has occurred, and the flow advances to step S218. Step S
At 218, the thrust error detection flag is set to the RA of the CPU1.
Set on M. This flag is an identification flag indicating that a thrust error has occurred during the thrust processing, and the determination of the occurrence of the error in the above-described step S105 is made based on the presence or absence of this flag. After setting the flag in step S218, similar to the case where winding is completed normally,
The process proceeds to steps S213 to S216, and the feeding of the film F is stopped. However, if the thrust error detection flag is set in step S218, step S21 is performed to notify the occurrence of a thrust error.
In step 6, "E" is displayed on the film counter of the display device 2. After completing all the processing, the process returns from step S216 to step S103 in FIG.

<Winding Process> FIG. 10 shows the winding process of the camera according to the present embodiment. The winding process is a film feeding process in which the next frame to be shot is opposed to the aperture surface after the shooting is completed. Step S105 shown in FIG.
When the photographing ends in step, step S300 shown in FIG. 10 is called in step S106. In step S301, normal rotation of the motor 7 is started to feed the film F in the winding direction. Next, in step S302, an end detection timer for detecting the end of the film F is set to 2 seconds, and time measurement is started.

In step S303, the end detection timer is read. If it is determined that the end detection timer has timed out, it is determined that the end of the film F has been reached, and the flow advances to step S308. If it is determined that the end detection timer has not expired, the process proceeds to step S304. In step S304, the voltage value of the port P0 and the threshold value are compared, and if it is determined that the magnitude relationship between the voltage value of the port P0 and the threshold value has been reversed from the previous time, the performance 12
It is determined that the edge has been detected and the process proceeds to step S305. If it is determined that the edge has not been reversed, it is determined that the edge has not been detected and the process returns to step S303. In step S305, the voltage of the port P2 is changed from “H” to “L”.
Or from “L” to “H”. Step S3
At 06, the number of times of detection of the perforation edge is read, and if it is determined that the number of times of detection is 4, the process proceeds to step S309. If it is determined that the number of detections is not four, the process proceeds to step S307. In step S307, the end detection timer is set to 2 seconds to start timing, and the process returns to step S303.

As described above, when it is determined in step S306 that the number of times of detection of the edge of the perforation 12 is four, the process proceeds to step S309. In step S309, the motor 7 is stopped, and in step S310
To apply a reverse voltage to the motor 7 for a predetermined time (5 ms) to apply a brake. Further, a predetermined time (8
0 ms) The terminal of the motor 7 is short-circuited to apply a brake, and the feeding of the film F is completely stopped. At this time, the next frame to be photographed faces the aperture surface. Next, in step S312, the display of the film counter of the display device 2 is incremented by "1", and the process proceeds to step S1 in FIG.
Return to 07.

As described above, if it is determined in step S303 that the end detection timer has expired, the flow advances to step S308. In step S308, an end detection flag is set in the RAM of CPU1.
This flag indicates that the end of the film has been detected during the winding process, and the determination in step S107 is made based on the presence or absence of this flag. Step S3
When the flag is set in step 08, as in the case where the winding is normally completed, steps S310 to S3 are performed.
In step S12, the film feeding is stopped in step S12.
The process returns from step 312 to step S107 in FIG. However, in this case, the addition of the film counter of the display device 2 is not performed in step S312.

<Rewinding Process> FIG. 11 shows the rewinding process. The rewinding process is a film feeding process for rewinding the film F. If it is determined in step S103 shown in FIG. 4 that a thrust error has occurred, and if it is determined in step S107 that the end of the film F has been detected, step S400 is performed in step S108.
Is called.

The process proceeds from step S400 to step S401. In step S401, the edge number counter is set to "4".
Set to. Next, in step S402, the reverse rotation of the motor 7 is started. In step S403, the rewind completion detection timer is set to a predetermined time (8 seconds), and time measurement is started.
If it is determined in step S404 that the rewind completion detection timer has expired, the process proceeds to step S411. If it is determined that the time has not expired, the process proceeds to step S411.
Proceed to 405. In step S405, the port P0
Is read, and if it is determined that the magnitude relationship between the voltage value of the port P0 and the threshold value is reversed, the process proceeds to step S406. If it is determined that the magnitude relationship is not reversed, the process returns to step S404. In step S406, the port P2 is switched from "H" to "L" or from "L" to "H". In step S407, the edge counter is decremented by "1". In step S408, the edge number counter is read, and the edge number counter is set to "0".
Is determined, it is determined that the film F has been rewound by one frame, and the flow advances to step S409. If it is determined that the edge number counter is not "0", it is determined that the frame has not been rewound by one frame, and the process returns to step S403.
In step S409, the film counter is decremented by "1". In step S410, the number-of-edges counter is set to "4", and the process returns to step S403.

If it is determined in step S404 that the rewind completion detection timer has expired,
It is determined that the film F has been completely rewound, and the flow advances to step S411. In step S411, the motor 7 is stopped. In step S412, a reverse voltage is applied to the motor 7 to apply a brake. In step S413, the terminal of the motor 7 is short-circuited to apply a brake, and the film feeding is completely stopped. When the film feeding is stopped, the process returns to the main routine, and the sequence ends (FIG. 4).

As described above, in the winding process and the rewinding process, similarly to the thrust process, the port P2 is switched between "H" and "L" every time an edge of the perforation is detected, and the light emitting element 15a is turned off. The amount of light is changed. Therefore, the waveform shown in FIG. 7 (after time c)
Similarly to the above, the amplitude of the voltage at the port P0 increases.

As described above, in the present embodiment,
When the leading end of the film F is detected, the light amount of the light emitting element 15a is reduced to reduce the output of the photo sensor 15, that is, the voltage value of the port P0. Can be prevented. Also,
Since the light amount of the light emitting element 15a is switched when the edge of the perforation 12 is detected, the difference between the output voltage value of the photo sensor 15 and the threshold value can always be maintained at a certain value or more. , The degree of contamination of the reflection plate, or various noises can be secured. Therefore, the edge of the perforation 12 can be reliably detected.

The reason why erroneous detection of the edge of the perforation 12 can be prevented by increasing the output amplitude of the photosensor 15 will be further described with reference to FIGS. 8 and 9 correspond to a conventional camera in which the light amount of the light emitting element 15a is not changed. Light emitting element 15
The light projected from a is transmitted through the film F, is reflected by the reflector, and is received by the light receiving element 15b. Since the output value of the photo sensor changes according to the presence or absence of the film F, the presence or absence of the film F can be detected by setting a threshold value within the range of the change width. However, when the amount of reflected light decreases due to, for example, contamination of the reflector, the output value of the photosensor when there is no film F approaches the threshold as shown in FIG. Further, since the light transmittance varies depending on the type of the film, for example, when a film having a high transmittance is used, the output value of the photo sensor when the film is present approaches the threshold value as shown in FIG. As described above, when the output value of the photosensor approaches the threshold value, the output value of the photosensor easily reaches the threshold value when the output value of the photosensor fluctuates due to the influence of noise or the like. It is erroneously recognized as having detected the edge.

On the other hand, in the camera of this embodiment,
When the photo sensor 15 is not facing the film F, the light amount of the light emitting element 15a is increased, and when the photo sensor 15 is facing the film F, the light amount of the light emitting element 15a is decreased. The voltage difference between the value and the threshold can be kept at a value equal to or higher than a certain value. Therefore, even though the edge of the perforation 12 is not actually detected, the output value of the photosensor 15 reaches the threshold value due to noise or the like, and erroneous detection of erroneously determining that the edge has been detected is eliminated. Further, even when the difference in the amount of received light due to the presence or absence of the film F is small, for example, when the light transmittance of the film F is high, sufficient detection accuracy can be maintained, so that erroneous detection can be prevented.

Also, since a weak high-frequency noise is superimposed on the output of the photosensor, the output value of the conventional camera crosses the threshold value twice or more with respect to one edge, and there are a plurality of edges. However, in the camera according to the present invention, the output value is quickly separated from the threshold value by the first detection, so that such an erroneous recognition can be prevented.

In this embodiment, the reflection type photo reflector 15 is used, but a transmission type photo interrupter may be used instead of the reflection type photo reflector.
In the present embodiment, the detection of the edge of perforation and the like is performed by one determination, but the same signal may be read twice to make the detection more reliable. In this embodiment, a reflector is attached to the rail surface so that stronger light is received when the film F is not facing the photoreflector, but the rail surface is a non-reflective surface,
When the film F is opposed to the film F, that is, when the film F is used as a reflection surface, the reflected light may be further increased.

Hereinafter, the correspondence between the present embodiment and the claims will be described. The light emitting element 15a serves as a light emitting means, and the light receiving element 15b
Corresponds to the light receiving means, the CPU 1 and the photo sensor circuit 6 correspond to the detecting means, and the CPU 1 corresponds to the control means.

[0042]

According to the first aspect of the present invention, the light quantity of the light projecting means is increased or decreased so that the difference between the light receiving quantity of the light receiving means and the light quantity threshold is increased. Is prevented from being erroneously detected. According to the second aspect of the present invention, when the first edge of perforation is detected, the light amount of the light projecting means is increased or decreased, so that erroneous detection of perforation due to a chatter signal or noise is prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a camera with a film detection device according to the present invention.

FIG. 2 is a view showing a film used for the camera of the embodiment shown in FIG. 1;

FIG. 3 is an electric circuit diagram showing a photo sensor circuit of the camera according to the embodiment shown in FIG.

FIG. 4 is a flowchart showing the operation of the camera according to the embodiment shown in FIG.

FIG. 5 is a flowchart showing the operation of the camera according to the embodiment shown in FIG. 1;

FIG. 6 is a flowchart showing the operation of the camera according to the embodiment shown in FIG. 1;

FIG. 7 is a diagram showing a photosensor output voltage waveform of the camera according to the embodiment shown in FIG. 1;

FIG. 8 is a diagram showing a photosensor output voltage waveform when a port P2 is fixed at “H”.

FIG. 9 is a diagram showing a photosensor output voltage waveform when a port P2 is fixed at “L”.

FIG. 10 is a flowchart showing the operation of the camera according to the embodiment shown in FIG. 1;

FIG. 11 is a flowchart showing the operation of the camera according to the embodiment shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CPU 11 Perforation 15 Photosensor 15a Light emitting element 15b Light receiving element F film

Claims (2)

[Claims] 1. A light projecting means for projecting light on a film to be fed, a light receiving means for receiving light from the light projecting means, and a light-receiving means for receiving light from the light-receiving means and a predetermined light amount threshold value. Detecting means for detecting the presence or absence of a film facing the light projecting means, such that the difference between the received light amount and the light amount threshold is increased, A camera with a film detecting device, comprising: a control unit for increasing and decreasing the amount of light. 2. A light projecting means for projecting light on a film to be fed, a light receiving means for receiving light from the light projecting means, and a magnitude relation between a light receiving amount of the light receiving means and a predetermined light amount threshold is reversed. Detecting means for detecting a perforation edge of the film by detecting that the first edge of the film is detected, and detecting a second edge of the perforation following the first edge when detecting a first edge of the perforation. A camera with a film detection device, comprising: control means for increasing or decreasing the light quantity of the light projecting means so that the difference between the light quantity threshold value and the light reception quantity becomes large.