JPH05150324A - Magnetic reproducing device of camera - Google Patents

Abstract

(57) [Abstract] [Purpose] Without complicating the structure of the magnetic reproducing circuit,
It is possible to always reproduce appropriate information regardless of the change in the film feeding speed. A track width changing means 16 for changing the effective track width of the magnetic head H and a control means 8 for controlling the track width changing means according to the film feeding speed are provided to prevent fluctuations in the film feeding speed. Accordingly, the effective track width of the magnetic head is changed so that the magnitude of the reproduction signal is within a certain range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic reproducing apparatus for a camera equipped with a magnetic head for reproducing information from a magnetic storage section provided in a film.

[0002]

2. Description of the Related Art In recent years, a film having a magnetic track (magnetic storage portion) has been used, and information such as the date of the year, shutter time, aperture value, etc. can be written on this magnetic track by a magnetic head, or when necessary. In accordance with U.S. Pat. No. 4,864,332, there is proposed a camera capable of reading the information or reading information such as the film sensitivity and the number of specified film frames recorded in advance.

[0003]

However, in this type of camera, the film feed speed of the camera may change within a range of several times depending on the power supply battery, load fluctuation due to the number of film frames, temperature, and the like. Therefore, since the film feeding speed at the time of magnetic reproduction has a great influence on the size of the reproduction signal, a large input dynamic range is required on the reproduction circuit side, and the circuit becomes complicated.

The object of the present invention is to solve the above problems,
It is an object of the present invention to provide a magnetic reproducing device for a camera, which can always reproduce appropriate information without complicating the structure of the magnetic reproducing circuit and regardless of the fluctuation of the film feeding speed.

[0005]

According to the present invention, there are provided track width changing means for changing the effective track width of a magnetic head, and control means for controlling the track width changing means according to the film feeding speed. There is.

[0006]

The effective track width of the magnetic head is changed according to the change of the film feeding speed so that the magnitude of the reproduced signal is kept within a certain range.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing an internal structure of a main part of a camera which is a first embodiment of the present invention.

In the figure, reference numeral 1 is a photoreflector for detecting a perforation P of a film F, which will be described later, and generating a signal for indexing one frame of the film F and a signal for the timing of writing information. 2 is a film feeding motor disposed in the spool, 3 is a gear train for decelerating and switching between winding and rewinding, 4 is a rewinding fork, C is a film cartridge, and F is a belt. -The above-mentioned film provided with a magnetic track (magnetic track) T on the side, P is the above-mentioned perforation, H is the writing of information on the magnetic track T on the film F, or A magnetic head for reading. Reference numeral 5 denotes a pad that presses the film F against the magnetic head H, and has a concave portion at the central portion for increasing the adhesion of the head gap between the film F and the magnetic head H.

FIG. 2 is a circuit block diagram of the main part of the camera.

In the figure, 7 is a power supply battery for the camera, and 8
Is a control circuit such as a microcomputer for controlling various operations of the camera, 9 is a release switch for starting photography, and 10 is the film feeding mode for winding and rewinding the film F. A film feed circuit for driving the image pickup device 2; a pulse detection circuit 11 for converting a perforation signal from the photoreflector 1 into a corresponding signal for the control circuit 8; and 12 for supplying various information to the magnetic track T of the film F. A magnetic recording circuit for driving the magnetic head H for recording, a film F through the magnetic head H.
Magnetic reproducing circuit for reading magnetic information from the magnetic track T of
Reference numeral 14 is an AE that performs known photometry, distance measurement, and shutter control.
An AF / SH circuit, 15 is a liquid crystal display for displaying the number of frames of the film F, and 16 is a switching means for changing the effective track width among the three tracks 1 to 3 provided in the magnetic head H.

FIG. 3 is a flow chart showing the operation of the control circuit 8.
It is a chart, and will be described below according to this. [Step 1] Whether or not the film cartridge C is loaded is determined from the state of the film presence / absence switch (not shown), and the process proceeds to step 2 by determining that it is loaded. [Step 2] The film feeding motor 2 is normally rotated through the film feeding circuit 10 to start winding the film F. [Step 3] Here, the feeding speed of the film F is detected.

Here, two specific examples of the method for detecting the feeding speed of the film F will be shown with reference to FIGS. 4 and 5.

In FIG. 4, the movement of the film F is not actually detected, but the power supply voltage is changed in step 41,
2 is a flow chart in which the ambient temperature is detected, and in step 43, the feeding speed is predicted and calculated from the above information.

Unlike FIG. 4, FIG. 5 shows an example of a flow chart for detecting the actual feeding speed from the photo reflector 1 and the perforation P.

That is, when the perforation signal is detected in step 51, the process proceeds to step 52 and the timer is started. Then, in step 53, the process stays in step 53 until the next perforation is detected. When the next perforation is detected, the process proceeds to step 54 and the timer is stopped. As a result, the known perforation interval and the time required for feeding can be obtained from the timer, and the feeding speed is calculated based on this in step 55. [Step 4] It is determined whether the feeding speed obtained in Step 3 is within the standard range, is fast, or is slow. If it is fast, the reproduction signal is large, so go to Step 5. , The playback signal is small if it is slow, so step 7
To, respectively. "Step 5" The width of the track from which magnetic information is read is narrowed by the switching means 16 and the process proceeds to step 8. "Step 6" The width of the track from which magnetic information is read is standardized by the switching means 16 and the process proceeds to step 8. "Step 7" The width of the track for reading the magnetic information is widened by the switching means 16 and the process proceeds to step 8.

A method of changing the width of the track from which magnetic information is read will be described later. [Step 8] The magnetic information recorded on the magnetic track T of the film F is reproduced by the magnetic head H and the magnetic reproducing circuit 13, and the film sensitivity, the number of films, etc. are set in the camera. [Step 9] The perforation signal from the photoreflector 1 is detected through the pulse detection circuit 11, and it is determined whether or not the number of photographed frames has reached the first frame. If not, this step Stay at 9 and reach step 10 if reached. [Step 10] The driving of the film feeding motor 2 is stopped through the film feeding circuit 10 and the winding of the film F is stopped. [Step 11] From this point onward, only magnetic writing is performed after the end of photographing, so the track width is switched to be wider. [Step 12] It is determined whether or not the release switch 9 is turned on, and if it is turned on, the process proceeds to step 13. [Step 13] Subject brightness information is obtained by the AE / AF / SH circuit 14 to determine the shutter opening / closing conditions. [Step 14] Here, the AE / AF / SH circuit 14
The subject distance information is obtained to drive the lens barrel to focus on the subject. [Step 15] The AE / AF / SH circuit 14 is driven to perform opening / closing control of the shutter, that is, exposure control based on the shutter opening / closing conditions obtained in step 13 above. [Step 16] The film feeding motor 2 is rotated in the forward direction via the film feeding circuit 10 to start winding the photographing frame. [Step 17] Magnetic Head H and Magnetic Recording Circuit 13
Is driven to write the shooting date, shutter speed, aperture value, etc. to the shooting frame during film feeding. [Step 18] It is determined whether or not one frame of perforation signal is input from the photoreflector 1 via the pulse detection circuit 11, and the process proceeds to step 19 by determining that it is input. [Step 19] The number of frames (frame) displayed on the liquid crystal display 15 is counted up. [Step 20] The driving of the film feeding motor 2 is stopped through the film feeding circuit 10 and the winding of the film F is stopped. [Step 21] Here, the specified frame number information fetched by the means for detecting the last frame of the film (not shown) is compared with the current number of frames, and if the film is finished (there is no remaining frame), the process proceeds to step 22. If not completed, the process returns to step 12. [Step 22] The film feeding motor 2 is reversely rotated through the film feeding circuit 10 to rewind the film F. [Step 23] Whether or not the film cartridge C has been removed from the camera is determined from the state of the film presence / absence switch (not shown), and the process returns to step 1 by determining that it has been removed.

FIG. 6, FIG. 7, and FIG. 8 show step 4 of FIG.
7 to 7 show specific circuits for performing the operation of switching the track width, track width states, and magnetic head shapes.

L ₁ , L ₂ and L ₃ are coils for signal reproduction which are wound around a core portion divided into three parts. The core parts C ₀₄ , C ₀₃ , and C ₀₂ divided into three parts have a gap g with the core part C _01.
To form tracks T ₁ , T ₂ and T ₃ , respectively.

SWA and SAB are switches constituting the switching means 16, and the control circuit 8 according to the film feeding speed.
And the coil as shown in FIG. 9 is selected.

FIG. 10 shows the shape of a magnetic head according to the second embodiment of the present invention, in which a gap g is formed in an arc shape in the track width direction.

FIG. 11 shows an operation example of the magnetic head H of FIG. 9, in which the pad 6a and the spring 6b control the force for pressing the magnetic track T of the film F against the magnetic head, and this force can be switched. As a result, the amount by which the magnetic track T closely contacts the gap g of the magnetic head H is switched, the magnetic flux amount of the signal reproduced by the coil L changes, and the output level of the reproduced signal can be controlled.

According to each of the above-mentioned embodiments, since the means for changing the track width of the magnetic head is provided, the amount of the magnetic flux reproduced by the magnetic head is changed by changing the track width to adjust the reproduction output. Therefore, the magnetic reproduction signal, which greatly changes depending on the film feeding speed, can be kept within a certain range, and the subsequent processing circuit can be simplified. Alternatively, it no longer requires control of the film feed rate.

Further, in the coil switching type as in the first embodiment, when the track width is narrowed, the resonance frequency of the head alone can be increased, the impedance is lowered, and the thermal noise is generated. It becomes possible to make it small. In addition, when n coils are added, the signal becomes n times and the noise becomes root n times, which is also effective in terms of S / N.

[0024]

As described above, according to the present invention,
A track width changing means for changing the effective track width of the magnetic head and a control means for controlling the track width changing means according to the film feeding speed are provided, and the magnetic head is effective according to the film feeding speed fluctuation. Change the track width,
The size of the reproduced signal is kept within a certain range. Therefore, it is possible to always reproduce appropriate information without complicating the structure of the magnetic reproducing circuit and without depending on the fluctuation of the film feeding speed.

[Brief description of drawings]

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

FIG. 2 is an electric block diagram of a main part of the camera shown in FIG.

FIG. 3 is a flowchart showing the operation of the control circuit of FIG.

FIG. 4 is a flowchart showing an example when a film feeding speed is detected in step 3 of FIG.

5 is a flow chart showing another example at the time of detecting the film feeding speed in step 3 of FIG.

FIG. 6 is a circuit diagram showing a configuration of a magnetic head and a switching means in the first embodiment of the present invention.

FIG. 7 is a diagram for explaining a state of a reproduction track by the magnetic head as shown in FIG.

FIG. 8 is a diagram showing the structure of a magnetic head according to the first embodiment of the invention.

9 is a diagram showing the relationship between the selection of tracks by the selection means of FIG. 6 and the reproduction signals accompanying it.

FIG. 10 is a diagram showing a structure of a magnetic head according to a second embodiment of the invention.

11 is a diagram showing an example of controlling the output level of a reproduction signal using the magnetic head of FIG.

[Explanation of sign]

2 film feeding motor 8 control circuit 10 film feeding circuit 13 magnetic reproducing circuit 16 switching means F film with magnetic track H magnetic head T ₁ , T ₂ , T ₃ track

Claims (1)

[Claims] 1. A magnetic reproducing apparatus for a camera having a magnetic head for reproducing information from a magnetic storage unit provided in a film, and a track width changing means for changing an effective track width of the magnetic head, and a film feeding. A magnetic reproducing apparatus for a camera, comprising: a control unit that controls the track width changing unit according to a speed.