JP2875912B2 - Camera using film with magnetic storage - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head for reproducing information written in a magnetic storage unit provided on a film during film feeding, and amplifies an analog signal reproduced by the magnetic head. Circuit using a film with a magnetic storage unit, comprising: an amplifier circuit for converting the analog signal from the amplifier circuit into a digital signal; and a speed detecting means for detecting a feeding speed of the film. It is about.

[0002]

2. Description of the Related Art In recent years, a film having a magnetic storage unit is used, and photographing information such as shutter time, aperture value, date, title, and the like is written into the magnetic storage unit by a magnetic head.
A camera that reads out the photographing information as required has been proposed in US Pat. No. 4,977,419.

[0003] By the way, a film take-up sp
When the film is wound on the spool, the diameter of the film winding spool gradually increases, so that the film feeding speed increases. That is, the film feeding speed differs between the first frame and the last frame.

[0004]

When reading information with a magnetic head in conjunction with film feeding, the magnitude of the signal level detected by the magnetic head is proportional to the film feeding speed. In other words, the first frame has a relatively slow film feeding speed,
Since the level of the signal detected by the magnetic head is low and the film feeding speed increases as the last frame, the signal level detected by the magnetic head increases.

[0005] The digital conversion level of an A / D (analog-digital) converter arranged in a magnetic reproducing circuit is as follows.
Magnetic head 4 so that it is not affected by external noise
When it is not driven, that is, it is desired to set the level higher than the level in the steady state. However, if the level is set high and constant as described above, the film feeding speed is slow in the first photographing frame as described above. The signal level reproduced during the state is low, and a signal which does not reach the digital conversion level is generated, which may result in an information reading error.

If the digital conversion level is set to be lower and constant than the level in the steady state, the digital conversion level is easily affected by extraneous noise regardless of the film feeding speed, and the noise is digitally converted. There is a possibility that the reproduced signal will be different from the signal (write signal).

On the other hand, the film feeding speed and the rate at which the film feeding speed is increased depend on the winding diameter of the film take-up spool of the camera, the film thickness, the characteristics of the film feeding motor, It depends on the characteristics of the camera's power battery.

An object of the present invention is to eliminate a conversion error such as signal omission or conversion of external noise as data when converting an analog signal detected by a magnetic head into a digital signal, and to output an appropriate reproduced signal. It is an object of the present invention to provide a camera using a film with a magnetic storage unit that can perform the operation.

[0009]

According to the present invention, a digital conversion level for converting an analog signal into a digital signal in an A / D conversion circuit is changed according to a film feeding speed detected by a speed detecting means. Conversion level changing means for performing the conversion.

[0010]

Since the output level of the analog signal detected by the magnetic head greatly changes according to the film feeding speed, the digital conversion level is changed according to the detected film feeding speed, and the digital conversion level is changed. It is made to correspond to this.

[0011]

1 to 4 show a mechanical structure according to a first embodiment of the present invention, and FIG. 1 is a perspective view showing a main part of a camera.

In FIG. 1, 1 is a film cartridge, 2 is a film provided with a magnetic storage unit (magnetic track) T, and 3 is a perforation (P1, P2) of the film 2.
, Etc.), and a photo sensor for feeding the film at a fixed length. The time required for the photo sensor 3 to detect from perforations to perforations during film feeding. Is measured, the feeding speed of the film can be detected. 4 is a magnetic track T of the film 2
A magnetic head that slides on and writes or reads information.
Reference numeral 5 denotes a pad located at a position facing the magnetic head 4 with the film 2 interposed therebetween and having a function of pressing the film 2 against the magnetic head 4.

G is a film feeding mechanism for transmitting the output of the film feeding motor 1 to the fork 70, the details of which will be described later with reference to FIG. 57 is a film take-up spool.

Here, the film cartridge 1 used in this embodiment has the following structure proposed in US Pat. No. 4,834,306 and the like.

That is, the film 2 having the film passing slit and one end fixed to the supply spool and wound around the supply spool, and the radially extending outermost periphery of the film disposed coaxially with the supply spool. Regulation 2
A pressing member (not shown) for preventing the outermost periphery of the film cartridge from substantially contacting the inner wall of the film cartridge; and a part of the pressing member is deformed to prevent the outermost peripheral portion of the film from being restricted in the radial direction of the pressing member. The fork 70 is provided with a releasing portion (not shown) for continuously releasing, and a guiding portion (not shown) for guiding a portion of the film 2 released from the regulation to the film passage slit.
The outer periphery of the film 2 and the holding member are kept in a slip-free state by the expansion of the outermost periphery caused by the loosening of the film 2 caused by the rotation of the supply spool (not shown) engaged with the supply spool in the film pushing direction. And the film 2 can be extruded from the film cartridge 1.

The film 2 is extruded from the inside of the film cartridge 1 by a film feeding mechanism which will be described later, and then the film take-up spool 57 of the camera is used by known means.
It is wound up and fed.

FIGS. 2 to 4 are views showing specific examples of the structure of the film feeding mechanism G. FIG.

In these figures, reference numeral 51 denotes a film feeding motor, which rotates forward (in the direction of arrow B in FIG. 3) when winding up the film and reversely rotates (in the direction of arrow C in FIG. 4) when rewinding the film. Reference numeral 52 denotes a pinion gear fixed to the rotating shaft of the motor 51. A first sun gear 53 meshes with the pinion gear 52. Reference numeral 54 denotes a first planetary gear, which meshes with the first sun gear 53. 55
Connects the first sun gear 53 and the first planetary gear 54, and holds the first planetary gear 54 rotatably while generating a frictional force between the first sun gear 53 and the first planetary gear 54; This is a first connection lever in which the first planetary gear 54 revolves around the first sun gear 53 as a rotation center when one sun gear 53 rotates. The first sun gear 53, the first planetary gear 54, and the first connection lever 5
5 constitutes a known planetary gear mechanism. Reference numeral 56 denotes a spool gear which meshes with the first planetary gear 4 only when the film feeding motor 51 rotates forward. Reference numeral 57 denotes a film take-up spool which is fixed to the spool gear 56 and moves integrally.

A first idler gear 58 always meshes with the first sun gear 53, a first gear 59 has a large gear portion 59a and a small gear portion 59b, and a large gear portion 59a meshes with the first idler gear 58. The two-stage gear, 60 is the first gear
The second idler gear meshing with the small gear portion 59b of the two-stage gear 59, 61 is a third idler gear meshing with the second idler gear 60, 62 is a second sun gear meshing with the third idler gear 61, 63 is This is a second planetary gear that meshes with the second sun gear 62. 64 is the third
And the second planetary gear 13 meshes with the second sun gear. 65 connects the second sun gear 62, the second planetary gear 63 and the third planetary gear 64 with arms 65a and 65b, respectively, and holds each planetary gear rotatably while generating frictional force; The second planetary gear 63 and the third planetary gear 64 are second connecting levers that revolve around the second sun gear 62 as a center of rotation by rotation of the second sun gear 62. . The second sun gear 62 and the second and third planetary gears 63 and 64
The second coupling lever 65 and the second coupling lever 65 constitute a known planetary gear mechanism.

Reference numeral 66 denotes a fourth idler gear. When the film feed motor 51 is rotated forward, the second idler gear is driven by the second connecting lever 65.
When the motor 51 rotates in the left direction around the sun gear 62, it meshes with the second planetary gear 63, but does not mesh with the third planetary gear 64. This is a gear that meshes with the third planetary gear by rotation in the direction, but does not mesh with the second planetary gear 63. 67 has a large gear portion 67a and a small gear portion 67b; a second two-stage gear in which the large gear portion 67a meshes with a fourth idler 66; 68 has a large gear portion 68a and a small gear portion 68b; Part 6
8a is a third two-stage gear engaged with the small gear 67b of the second two-stage gear 67, 69 is a fork gear engaged with the small gear 68b of the third two-stage gear 68, and 70 is the fork gear. The fork rotating integrally with the gear 69 rotates a supply spool (not shown) in the film cartridge 1 to extrude and wind the film 2 from the cartridge 1. .

Reference numeral 71 denotes a stopper provided on the camera body (not shown) for regulating the position of the first connecting lever 55 in the left rotation direction.

In the above configuration, after the film cartridge 1 is loaded in a cartridge chamber (not shown), a film feed motor 51 (pinion gear 52) is provided as shown in FIG.
Is rotated in the direction of arrow B (when it is rotated forward), the first sun gear 53 rotates clockwise, and accordingly, the first planetary gear 54 is actuated by the action of the first connecting lever 55. Revolves clockwise about the first sun gear 53 as the center of rotation, and eventually meshes with the spool gear 56, whereby the driving force of the film feed motor 51 is transmitted to the spool gear 6 and the film take-up The rule 57 rotates clockwise.

The driving force of the first sun gear 53 is transmitted through an idler gear 58 which is another gear meshing with the first sun gear 53.
The light is transmitted to the second sun gear 62 via the third idler gear 61. Therefore, since the second sun gear rotates counterclockwise, the second planetary gear 63 and the third planetary gear 64 rotate about the second sun gear by the action of the second coupling lever 65. Revolving in the counterclockwise direction, the second planetary gear 63 eventually meshes with the fourth idler gear 66. As a result, the driving force in the direction B of the film feeding motor 51 is transmitted to the fourth idler gear 66 as a driving force in the counterclockwise direction, and furthermore, the second two-stage gear 67 and the third two-stage gear 68. Through the fork gear 69,
The fork 70 rotates clockwise.

Here, the gear ratio of the gear train is configured as follows.

The peripheral speed of the film take-up spool 57 is "V1", and the fork 70 controls the film cartridge 1
Assuming that the speed of the film 2 extruded from is “V2”,
There is a relationship of “V1> V2”.

When the film 2 is extruded from the film cartridge 1 by the clockwise rotation of the fork 70, the leading end of the film 2 is moved by a known means (a claw provided on the film take-up spool 57). The perforation P of the film 2 is hooked, or the means for pressing the film 2 against the film take-up spool 57 provided on the camera body side, etc. It is wound around the take-up spool 57.
Thereafter, the film 27 is wound up only by the rotation of the film take-up spool 57 by the film feeding motor 51 for the following reason.

When the film 2 is wound around the film take-up spool 57 in accordance with the relationship of "V1>V2", the film take-up spool 57 is connected to the fork gear 69 and the third The gears are transmitted in the order of the step gear 68, the second two-stage gear 67, and the fourth idler gear 66, and the second planetary gear 6
The fourth idler gear 66 is lower than the clockwise rotational speed of the third idler gear 66.
The rotation speed in the counterclockwise direction is higher, but at this time, the fourth idler gear 66 bounces off the second planetary gear 63,
This is because the meshing between the second planetary gear 63 and the fourth idler gear 66 is disengaged momentarily, and the speed difference is absorbed.

Next, the operation at the time of film rewinding will be described.

This operation will be described with reference to FIG. 4. When the film feed motor 51 is rotated in the direction of arrow C, the first connection lever 55 and the first planetary gear 54 are connected to the first sun gear 5
The first connection lever 55 revolves in the counterclockwise direction around the rotation center 3 until the end 55a of the first connection lever 55 contacts the stopper 71. Therefore, the first planetary gear 54 and the spool gear 56
Is disengaged.

At this time, the second sun gear 62 rotates clockwise, whereby the second planetary gear 63 and the third planetary gear 64 are rotated by the action of the second connecting lever 65. Revolves clockwise around the gear 62 as the center of rotation.
The second idler gear 66 is disengaged from the second planetary gear 63, and the fourth idler gear 66 and the third planetary gear 64 are engaged instead. Therefore, the fork gear 69 rotates in the counterclockwise direction, and the fork 70 causes the supply spool (not shown) in the film cartridge 1 to rotate in the reverse direction, whereby the film 2 is wound into the cartridge 1. Go.

FIG. 5 is a circuit block diagram of the camera according to the first embodiment of the present invention.

In FIG. 5, reference numeral 101 denotes a control circuit which is constituted by a microcomputer or the like and controls various operations of a camera; 102, an AF / AE control circuit which controls focusing of a photographing lens and operation of an exposure control shutter; A film feeding motor 103 drives the film feeding motor 51.
A data drive circuit 104 for driving the magnetic head 4 to perform an information write operation; and 105 a relay.
When this switch is turned on, the camera is released. Reference numeral 106 denotes a cartridge loading switch that is turned on when the film cartridge 1 is loaded into the camera, and 107 denotes a back cover switch that is turned on when the back cover is closed.
The control circuit 101 drives the film feed motor driver circuit 103 by turning on both the switches 6 and 107 to start cueing of the first frame of the film 2.

Numeral 108 detects magnetic information written in the magnetic storage section T of the film 2 via the magnetic head 4,
A reproduction circuit which amplifies the analog signal and converts the digital signal into information for the control circuit 101. The signal amplifier 108a detects an output from the magnetic head 4 and amplifies the analog signal. Is converted into a digital signal.

Reference numeral 109 denotes a frame number display comprising a liquid crystal display or the like for displaying the number of photographed frames, 110 denotes a display driving circuit for driving the frame number display 109 to count up or down, and 111 denotes the display driving circuit. A photosensor driving circuit 112 for driving the photosensor 3 is a storage circuit for storing a film feeding speed and the like described later.

FIG. 6 is a circuit diagram showing a specific configuration example of the A / D converter 108b of FIG.

In this figure, reference numerals 31 and 32 denote comparators for digitizing a positive signal and a negative signal (the level in a steady state is "0") of the analog signal amplified by the signal amplifier 108a, respectively. , 33 are RS flip-flops for converting the positive and negative signals digitized by the comparators 31 and 32 into digital signals, and 34 to 37 are analog switches for switching the signal inversion levels of the comparators 31 and 32. , 38 to 43 are resistors for setting the signal inversion level of the comparators 31 and 32, and these resistances are represented by R38, R39, R40 and R.
41, R42 and R43.

The analog switches 34 to 37 operate as follows. That is, the switching signal AS from the control circuit 101
When 1 is input, the analog switches 34 and 35 are turned on, and when the switching signal AS2 is input, the analog switches 36 and 37 are turned on.

Here, the voltages applied to the terminals a and b are represented by Va,
When the analog switches 36 and 37 are in the ON state, the signal inversion levels Vref31 and Vref32 are Vref31 = (R39 + R40) / (R38 + R39 + R40) × Va Vref32 = R43 / (R41 + R42 + R43) × Vb. When 35 is in the ON state, the signal inversion levels Vref31 and Vref32 are as follows: Vref31 = R40 / (R38 + R39 + R40) × Va Vref32 = (R42 + R43) / (R41 + R42 + R43) × Vb.

By the way, when the rotation speed of the film take-up spool 57 is the same, the amount of the film 2 wound around the film take-up spool 57,
That is, as described above, the level of the analog signal detected by the magnetic head 4 is proportional to the film feeding speed, and is proportional to the winding diameter. Therefore, the level of the analog signal detected by the magnetic head 4 is proportional to the winding diameter of the film 2 at the film take-up spool 57.

The diameter of the film take-up spool 57 is D, the thickness of the film 2 is d, the pitch of one frame is L, and the aperture when the leading end of the film is wound around the film take-up spool 57 once. Assuming that the position is the first frame, the film 2 when the film is wound around the film take-up spool 57 up to n frames.
Is the total length Fn of Fn = (n-1) L + Dπ, and the total length Fm of the film up to the m-th lap is = {(D-2d) m + dm (m + 1)} π, and how many laps is the nth frame Can be represented by Therefore, the inner winding diameter D of the n-th frame
n can be expressed by Dn = D + f (m) × 2 × d (where f (m) is a function for rounding down the decimal part of m). Therefore, as an example, D = 10 m
Substituting the general values of m, d = 0.14 mm and L = 38 mm, the inner winding diameter D1 of the first frame → “10.28 mm” The inner winding diameter D36 of the 36th frame → 30.60 mm .

Therefore, the level of the analog signal is the first
The difference between the frame and the 36th frame is about three times, and as described above, the digital conversion of the A / D converter 108b in the reproduction circuit 108 is performed so as not to be affected by external noise. If you try to set the level to a constant value that makes the difference from the level in the steady state as large as possible,
If the film feeding speed is slow, there is a problem that a reproduced signal which does not reach the digital conversion level is generated, causing information reading error, and conversely, the digital conversion level differs from the steady state level. Is set to a constant value that reduces the noise, it is susceptible to extraneous noise irrespective of the film feeding speed, and even the noise is digitally converted.

Further, as described above, the film feeding speed varies depending on the thickness of the film 2, the characteristics of the film feeding motor 51, the consumption of a battery serving as a driving source thereof, and the like.
Also, due to these causes, the rate at which the film feeding speed changes according to the number of film shooting frames also changes.

Therefore, it is of course not possible to make the digital conversion level constant, and even if the digital conversion level is changed, or if the digital conversion level is changed only by the number of photographed frames of the film 2, the above-described reading error and noise Digital conversion occurs.

Therefore, in this embodiment, the film feed speed is measured and stored, and based on the measured film feed speed, when the film feed speed is low, the signal is not output in the steady state. The digital conversion level is set so that the difference from the level is small, and when the film feeding speed is high, the difference from the steady state level is large.

The film feeding speed is calculated by measuring the time t from the start of film feeding until the photosensor 3 detects the perforation P1 of the film 2.
Assuming that the pitch between the perforations P1 and P2 is L,
The film feed speed a is "L / t", and as will be described later, the digital conversion level is changed depending on whether or not the film feed speed a is equal to or higher than a predetermined value a1.

In FIGS. 7, 8 and 9 described below, the level in the steady state described above is represented as "V0".

FIGS. 7 and 8 show the case where the film feeding speed is lower than the predetermined value a1 and the case where the film feeding speed is lower than the predetermined value a1.
FIG. 9 shows output waveforms of the respective units at a higher speed.

More specifically, FIGS. 7 (a) and 8 (a) show the magnetic head 4 when it is slower and faster than the predetermined value a1.
7 (b) and 8 (b) show the output signal of the signal amplifier 108a for amplifying the input of FIG.
(c) and FIG. 8 (c) show the output signals of the A / D converter 108b for A / D converting the input.

The digital conversion level V in FIG.
Ref31-a and Vref32-a are as follows: Vref31-a = R40 / (R38 + R39 + R40) × Va Vref32-a = (R42 + R43) / (R41 + R42 + R43) × Vb. In this case, the analog switches 34 and 35 are ON
It is in a state.

Vref31-b and Vref32-b in FIG.
Vref31-b = (R39 + R40) / (R38 + R39 + R40) × Va Vref32-b = R43 / (R41 + R42 + R43) × Vb. In this case, the analog switches 36 and 37 are ON
It is in a state.

FIG. 9 shows that the film feeding speed a is a predetermined value a1.
9 (a). More specifically, FIG. 9 (a)
9A shows a detection signal of the magnetic head 4 at the film feeding speed a1, and FIG. 9B shows a signal amplifier 10 for amplifying the input.
FIG. 9C shows the output signal of the A / D converter 108b for A / D-converting the input of the output signal 8a.

The peak of the upper limit of the output signal shown in FIG.
The peak and the lower limit are digital conversion level V, respectively.
This is a limit state where the voltage is larger than ref31-b and smaller than Vref32-b.

Therefore, in this embodiment, when the film feed speed a of the previous frame is less than the predetermined value a1, the digital conversion levels are Vref31-a and Vref32-a. -b, Vref32-b.

Next, the operation of the control circuit 101 will be described with reference to the flowchart of FIG. "Step 99" When the power of the camera is turned on, the process proceeds to step 100. [Step 100] By turning on both the film cartridge loading switch 106 and the switch 107,
It is determined that the film cartridge 1 is loaded in the camera, and the flow advances to step 101. "Step 101" Film feed motor drive circuit 10
The film feed motor 51 is driven via the motor 3, and the first frame of the film 2 is located at the aperture position, and a so-called empty film feed operation is started. [Step 102] During the above-mentioned film idle feeding operation, the photo sensor 3 is driven via the photo sensor driving circuit 111 to detect the perforation of the film 2, and
The time required from the formation to the next perforation is measured, and the film feeding speed a is calculated. As described above, if the pitch of the perforation is L and the time required between them is t1, the film feed speed a can be calculated by "t1 / L". The speed a is stored in the storage circuit 112, and then the film feeding speed a is compared with a predetermined value a1. When the speed is higher than a1, the process proceeds to step 103, and when it is lower than a1, the process proceeds to step 104. [Step 103] The switching signal AS2 is output to turn on the analog switches 36 and 37, and the digital conversion level is set to Vref31-b and Vref32-b as shown in FIG. 8B. [Step 104] The switching signal AS1 is output to turn on the analog switches 34 and 35, and the digital conversion level is set to Vref31-a and Vref32-a as shown in FIG. 7B. [Step 105] The reproduction circuit 108 is driven to read out the film such as the film sensitivity, the number of frames, and the type of film (negative or positive) previously written in the magnetic storage unit T of the film 2 read by the magnetic head 4. The information is read, and a noise component is removed from the detection signal according to the time constant of the filter set in step 103 or step 104,
After being converted into a digital signal by a known circuit, this is stored in the storage circuit 112. "Step 106" It is determined whether or not the cueing of the first frame has been completed by a known means (for example, detection of a film feed amount by an encoder, motor energization time, and photo sensor 3
The detection proceeds to the step 107 by detecting the first frame. "Step 107" Film feed motor drive circuit 10
The film feed motor 51 is stopped via the control unit 3 to stop the idle feeding of the film, and the display driving circuit 110 is stopped.
Is driven to cause the frame number display 109 to indicate that it is the first frame. "Step 108" The state of the release switch 105 is determined. If the release switch 105 is ON, it is determined that the release has been made, the number of times of release of the film is stored in the storage circuit 112, and the process proceeds to step 109. [Step 109] The AF / AE control circuit 102 is driven to perform a known photographing operation such as an exposure operation by focusing a photographing lens or opening and closing a shutter. [Step 110] A comparison is made between the number of film frames read out in step 105 and the number of film frames that can be shot in advance by a known means and the number of currently shot frames, and it is determined whether or not there are remaining film frames. . As a result, when there is a remaining frame, the process proceeds to step 111, and when there is no remaining frame, the process proceeds to step 119. [Step 111] It is determined whether or not the film speed speed a at the time of feeding the previous frame stored in the storage circuit 1113 is equal to or higher than a1.
When it is smaller than 1, the process proceeds to step 113.

Assuming that the film feeding speed a at the time of feeding the previous frame is the time when the shooting of the first frame is completed at present,
The film feeding speed at the time of loading, that is, the film feeding speed calculated in step 102 and stored in the storage circuit 113. If it is assumed that the current time is the time when the photographing of the second and subsequent frames is completed, the following step will be described. This is the film feeding speed after the photographing of the previous frame is completed, which is stored at 116. [Step 112] The switching signal AS2 is output to turn on the analog switches 36 and 37, and the digital conversion level is set to Vref31-b and Vref32-b as shown in FIG. [Step 113] The switching signal AS1 is output to turn on the analog switches 34 and 35, and the digital conversion levels are set to Vref31-a and Vref32-a as shown in FIG. 7B. "Step 114" Film feed motor drive circuit 10
The film feed motor 51 is driven via 3 to start winding one frame to the next frame, and at the same time, start the timer. "Step 115" When the film 2 is wound up to the next frame, the magnetic head 4 is driven via the data writing circuit 104, and photographing information such as shutter speed, aperture value, photographing is stored in the magnetic storage unit T of the film 2. The information such as the written date is written, or the reproducing circuit 108 is driven as necessary to read the information written on the film from the magnetic head 4. "Step 116" The photosensor driving circuit 11 detects that the photosensor 3 has detected the performance of the next frame.
If the detection is made through step 1, it is determined that the winding of the film 2 to the next frame has been completed, and the flow advances to step 116. Also, at this time,
The timer started in step 114 is stopped, and winding is started.
Then, the time required until the application is detected is calculated, the film feeding speed a is calculated by the above-described method, and stored in the storage circuit 112. "Step 117" Film feed motor drive circuit 10
The driving of the film feeding motor 51 is stopped via 3;
Stop film feeding. [Step 118] The display driving circuit 110 is driven, and the frame number display 109 advances the frame number display by one frame. Thereafter, the process returns to step 108.

If it is determined in step 110 that there is no remaining film, step 11 is executed as described above.
Go to 9. "Step 119" Film feed motor drive circuit 10
The film feed motor 51 is driven in the reverse direction via the motor 3, and the operation of rewinding the film to the film cartridge 1 is started. "Step 120" It is determined by a known means whether or not the rewinding of the film 2 into the film cartridge 1 is completed. "Step 121" Film feed motor drive circuit 10
The driving of the film feeding motor 51 is stopped via 3;
Stop rewinding the film. [Step 122] A series of operations of the camera are ended.

11 to 13 are views showing a second embodiment of the present invention. FIG. 11 is a perspective view showing a main part of the camera. FIG. 12 is a view showing the pulse plate and the pulse contact piece of FIG. It is an enlarged view. The same parts as those in the first embodiment are denoted by the same reference numerals.

In these figures, reference numeral 6 denotes a roller pressed against the film 2, which is rotatably mounted on a camera body (not shown). 7 is a disk that moves integrally with the roller 6,
Reference numeral 8 denotes a pulse plate fixed on the disk 7 and having a conductive portion 8a and a non-conductive portion 8b. Numerals 9 and 10 denote pulse contacts, which generate pulse signals by contacting the conducting portions 8a on the pulse plate 8 and transmit the amount of rotation of the pulse plate 8 to the control circuit 101 of the camera. Obviously,
For one rotation of the pulse plate 8, the pulse contact pieces 9, 10 are n1
ON and OFF are repeated once (four times in this embodiment).

Here, assuming that the diameter of the roller 6 is D and the time required to generate n2 pulses is t2, the film feeding speed a is calculated by (Dπ / t2) × (n2 / n1). it can.

Thus, after the film feeding speed a is calculated in the first half of the winding operation of the frame, the digital conversion level is set, and the information of the frame is read out in the latter half of the winding operation of the frame.

FIG. 13 is a flowchart showing the operation in the second embodiment of the present invention. Here, only the operation different from the first embodiment shown in FIG. 7 will be described. "Step 110" It is determined whether or not there is a remaining frame of the film. If there is a remaining frame, the process proceeds to Step 114. If there is no remaining frame, the process proceeds to Step 119. "Step 114" Film feed motor drive circuit 10
The film feed motor 51 is driven via the motor 3 to start winding one frame of the film 2. "Step 114-1" The roller 6 rotates with the above-mentioned film feeding, and a pulse is generated by the pulse plate 8 and the contact pieces 9 and 10. First, a time t2 required to generate n2 pulses. Is detected. Then, "a = (D
.pi. / t2) .times. (n2 / n1) ", and if it is equal to or greater than a1, the film feed speed a is calculated at step 114-.
The process proceeds to step 2, and if smaller than a1, the process proceeds to step 114-3. "Step 114-2" The switching signal AS2 is output, the analog switches 36 and 37 are turned on, and the digital conversion levels are changed to Vref31-b and Vref32- as shown in FIG.
Set to b. [Step 114-3] The switching signal AS1 is output to turn on the analog switches 34 and 35, and the digital conversion levels are set to Vref31-a and Vref32- as shown in FIG.
Set to a. [Step 115] The information written in the magnetic storage unit T of the film 2 is removed by the magnetic head 4 while removing noise components at the digital conversion level set in step 114-2 or step 114-3. The data is read out and taken into the control circuit 101. Alternatively, the photographing information is written via the data writing circuit 104 as necessary.

The other operations are the same as in the first embodiment.

FIG. 14 is a perspective view showing a main part of a camera according to a third embodiment of the present invention, in which the same parts as those in the first and second embodiments are denoted by the same reference numerals.

In this embodiment, the film feed speed is not directly detected from the film 2 but the film feed motor 5 is used.
1 shows an example of calculating by detecting the number of rotations of 1.
According to this method, it is possible to detect the film feeding speed finely and without contact with the film 2.

In FIG. 14, reference numeral 11 denotes a film feeding mode.
The slit disk 12 fixed to the output shaft of the filter 51 is a photosensor, and the photosensor 12 detects the light and dark portions of the slit disk 11.

In this case, the slit disk 11 is m
It is assumed that one light and dark can be detected. It is also assumed that the film feeding motor 51 rotates N times and the film take-up spool 57 of the camera makes one rotation.
Then, if m2 brightnesses can be detected during the time T, the film feeding speed a can be obtained as follows.

The diameter of the film take-up spool 57 of the camera is D, the thickness of the film 2 is d, the pitch of one frame is L, and the position where the leading end of the film is wound around the film take-up spool 57 is the first position. Assuming that the frame is the frame, the total length Fn of the film 2 when the film is wound around the film take-up spool 57 up to n frames is given by Fn = (n-1) L + Dπ. = {(D-2d) m + dm (m + 1)} π, and how many laps is the nth frame Can be represented by Therefore, the inner winding diameter D of the n-th frame
n can be expressed by Dn = D + f (m) × 2 × d (where f (m) is a function for rounding off decimal places of m). Therefore, the film feed speed a is calculated by the following equation: a = {D + f (m) × 2 × d} · π · m2 / (m1 · N · T), and the digital conversion level is changed according to the result.

According to each of the above embodiments, the digital conversion level of the A / D converter 108b in the reproduction circuit 108 is changed according to the feeding speed of the film 2, so that the reading by the magnetic head 4 is performed. When converting an analog signal into a digital signal, a dropout of the signal may occur, or extraneous noise may be converted as data and erroneous information may be output as a reproduced signal. Disappears.

[0069]

As described above, according to the present invention,
Conversion level changing means for changing a digital conversion level for converting an analog signal into a digital signal in the A / D conversion circuit according to the film feeding speed detected by the speed detecting means is provided. The digital conversion level is changed according to the feeding speed so as to correspond to the change in the output level of the analog signal detected by the magnetic head according to the film feeding speed.
Therefore, when converting an analog signal detected by a magnetic head into a digital signal, it is possible to eliminate a conversion error such as converting missing signal or external noise as data, and to provide a camera which outputs a proper reproduction signal. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main configuration of a camera according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a gear train of the film feeding mechanism of FIG.

FIG. 3 is a plan view showing the arrangement of gears when the film feeding mechanism of FIG. 2 winds up the film.

FIG. 4 is a plan view showing an arrangement of gears when the film feeding mechanism in FIG. 2 rewinds the film.

FIG. 5 is a circuit block diagram of a camera according to the first embodiment of the present invention.

6 is a circuit diagram showing a specific configuration of the A / D converter of FIG.

FIG. 7 is a diagram showing signal waveforms for explaining a digital conversion level when the film feeding speed is equal to or less than a predetermined value in the first embodiment of the present invention.

FIG. 8 is a diagram showing signal waveforms for explaining a digital conversion level when the film feeding speed is equal to or higher than a predetermined value in the first embodiment of the present invention.

FIG. 9 is a diagram showing signal waveforms for explaining a digital conversion level when the film feeding speed is equal to a predetermined value in the first embodiment of the present invention.

FIG. 10 is a flowchart showing the operation of the control circuit of FIG. 5;

FIG. 11 is a perspective view illustrating a main configuration of a camera according to a second embodiment of the present invention.

FIG. 12 is a plan view showing a pulse plate and a pulse contact piece of FIG. 11;

FIG. 13 is a flowchart showing an operation in the second embodiment of the present invention.

FIG. 14 is a perspective view illustrating a main configuration of a camera according to a third embodiment of the present invention.

[Description of sign]

 Reference Signs List 3 photo sensor 4 magnetic head 7 pulse plate 8 pulse piece 11 slit disk 12 photo sensor 51 film feeding motor 101 control circuit 103 film feeding motor driving circuit 104 magnetic head driving circuit 108 reproduction circuit 108a signal amplifier 108b A / D converter 111 Photosensor drive circuit

Claims (1)

(57) [Claims] A magnetic head for reproducing information written in a magnetic storage unit provided on the film during film feeding; an amplification circuit for amplifying an analog signal reproduced by the magnetic head; In a camera using a film with a magnetic storage unit, comprising: an A / D conversion circuit for converting an analog signal from an amplifier circuit into a digital signal; and a speed detecting means for detecting a feeding speed of the film. A conversion level changing means for changing a digital conversion level for converting an analog signal into a digital signal in the A / D conversion circuit in accordance with the film feeding speed to be supplied. Camera using film.