JPH04229851A - Camera with magnetic head - Google Patents

Abstract

PURPOSE:To keep off any possible malfunction in a magnetic head through a camera therewith. CONSTITUTION:Each inner wall surface of two guide projections 11c, 11d is made up into a taper form so as to have a distance with these guide projections 11a, 11b narrowed to some extent. While a film 3 is fed to each interval between the guide projections 11a and 11c as well as 11b and 11d, a side end 3b of the film 3 is pushed upward as in illustration by each inner wall surface of the guide projections 11c, 11d, and thereby a side end 3a is pushed aside to each side of the guide projections 11a, 11b. Therefore, a snaking motion of the film 3 is kept back, and a positional relationship between a head surface 12a of a magnetic head 12 and a magnetic recording layer of the film 3 is always kept constant. A track slippage is prevented from occurring, while this film is in no case tilted in a film passage, and an azimuth loss becomes extremely lessened, thus such a regenerative signal as less in noise is securable.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera equipped with a magnetic head that uses a photographic film provided with a magnetic recording layer to read and write film data, photographic data, etc. on the magnetic recording layer.

0002

2. Description of the Related Art Cameras using a film having a magnetic recording layer are known, for example, from International Publication No. WO 90/04201 and WO 90/04202. This camera reads data such as the film type and film sensitivity from a magnetic recording layer coated on the film and uses it for photographing, or writes photographic data to the magnetic recording layer.

0003

[Problems to be Solved by the Invention] By the way, since the film guide of a camera usually has a margin of about 0.1 mm on one side, the film has a maximum margin of 0.2 mm in the width direction when being fed.
mm meandering. If the position of the magnetic head is fixed with reference to the film guide, the center of the recording/reproducing track of the magnetic head will shift by about ±0.1 mm at most due to the meandering of the film.

It is also known that when the gap during reproduction has an angular (azimuth) error of θ from the track width direction with respect to that during recording, the reproduction output is attenuated according to the following equation 1.

[0005]

[Math 1] This is generally called azimuth loss.

Here, "λ" is the recording wavelength, and if the recording density is 1000 BPI and the recording method is the tri-bit method, then λ=25.4 mm/(1000×1/3)
=8.5μ. Further, W is the track width, which is assumed to be 1 mm. In addition, θ is the inclination within the camera as shown in Fig. 12, and in the largest case, tan −1(
0.7/50)=0.8°. However, film 80
The width D1 is the initial value standard 35.00 (-0.1 to +0)
mm, but due to changes over time etc. min34.5mm
Since it is also possible, it is set to 34.5 mm. Also, the width D2 of the film gate in the film width direction is 35.00 (-0
~+0.2) mm, and the width D3 in the feeding direction is 50 mm. Note that the reference numeral 81 in the figure represents an aperture, and the reference numeral 82 represents a magnetic head.

When the azimuth loss is calculated from the fluctuation of the film position in the current camera according to equation 1, Lθ=1
The result is 5.3dB. Generally, in a digital magnetic recording system, it is said that S/N≧30 dB is required from the viewpoint of reliability, but the occurrence of this azimuth loss shows that reliability is significantly impaired.

The above-mentioned film meandering and azimuth loss cause problems such as a reduction in the playback output and unerased previous information during overwriting, resulting in noise during playback, which is a major cause of malfunction.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a camera with a magnetic head that prevents malfunction of the magnetic head.

0010

[Means for Solving the Problems] In order to achieve the above object, a camera with a magnetic head of the present invention is provided on both sides of a film path through which a film is fed, and is provided on both sides of a film path through which a film is fed, so that the position in the width direction of the film at an exposure position is controlled. two film guide members for regulating the film, a magnetic head provided in the middle of the film path for performing magnetic recording/reproduction by contacting a magnetic recording layer provided on the film, and shifting the film to one of the film guide members. and a film biasing means for maintaining a constant position in the width direction of the film in contact with the magnetic head. The film biasing means is a plurality of protruding members that act on one edge of the film along the film running direction, and is provided on the film so as to press the other edge of the film against one of the film guide members. The magnetic recording layer is stabilized in a predetermined position. Further, the film biasing means is a sprocket that engages with a perforation of the film to bias the film toward one of the film guide members. Further, the film biasing means includes a plurality of spring members provided along the film running direction and abutting one edge of the film to bias the film toward one film guide member. The film biasing means includes a plurality of cylindrical members provided along the film running direction and abutting one edge of the film to bias the film toward one film guide member.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGS. 1 and 2 showing the main parts of a camera according to the present invention, an aperture 4 is formed in a camera body 2 to define an exposure range for a film 3. Inner rails 6a and 6b are formed for positioning the film 3 in the optical axis direction, and outer rails 7a and 7b are further formed on the outside thereof for regulating the position in the film width direction.
is formed.

A magnetic head unit 10 as shown in the figure is fixed to the film pressure plate 5 at a portion slightly removed from the aperture 4. The magnetic head unit 10 includes four guide protrusions 11a, 11b, 11c, and 11d, and has a magnetic head 12 fixed to the inner upper part. The guide protrusions 11a and 11b are formed so that when the side end 3a of the film 3 comes into contact with each of the inner wall surfaces thereof, the film feeding direction and the ridgeline of the head surface 12a of the magnetic head 12 are exactly at right angles. has been done.

The inner wall surfaces of the guide projections 11c and 11d are as follows:
It is formed in a tapered shape so that the distance from the guide protrusions 11a, 11b becomes narrower toward the back. As a result, when the film 3 is fed between the guide protrusions 11a and 11c and between the guide protrusions 11b and 11d, the side end 3b of the film 3 is moved upward in the drawing by the inner wall surfaces of the guide protrusions 11c and 11d. It is pushed up, and the side end portion 3a is shifted toward the guide projections 11a and 11b.

The head surface 12a of the magnetic head 12 contacts a magnetic recording layer 13 coated in stripes on the base surface side of the film 3 to write and read digital data. The data read from the film 3 includes, for example, the type of film, the film sensitivity, the number of frames taken, etc. The data written to the film 3 includes data representing the shooting conditions, such as object color temperature, brightness, contrast, shooting distance, strobe light, etc. These include light intensity, shutter speed, aperture, etc. Further, the magnetic recording layer 13 is not limited to a stripe-like one, but may be a transparent magnetic recording layer coated on the entire base surface of the film 3.

The operation of the camera of the present invention constructed as above will be explained. Open the back cover of the camera, pull out the tip of the leader section of the cartridge over the take-up spool provided in the film take-up chamber, and close the back cover. The film 3 is sandwiched between them, and the side end 3b of the film 3 is pushed up by the tapered surface of the guide projections 11b, 11d, and the side end 3a of the film 3 is pushed up by the guide projections 11a, 1.
The guide protrusions 11a, 11 until they come into contact with the inner wall surface of 1c.
It is shifted to side c. At this time, the guide projections 11b, 1
The side end 3b of the film 3 pushed up by the tapered surface 1d is curved, but this is exaggerated in FIG. 2 to make it easier to understand, and it actually does not affect film exposure.

As a result, the film 3 is fed while the side end 3a slides on the inner wall surface of the guide protrusions 11a, 11c, so meandering of the film 3 is prevented and the head surface of the magnetic head 12 is The positional relationship between the magnetic recording layer 12a and the magnetic recording layer 13 of the film 3 is always maintained constant. As a result, not only is track deviation prevented, but also the film 3 is not tilted within the film path, so the so-called azimuth loss is extremely reduced, and a noise-free reproduced signal can be obtained.

In the embodiment described above, a guide protrusion is used as a means for shifting the film 3 to one side, but another example will be explained with reference to FIGS. 3 to 8. The example shown in Figure 3 is
A sprocket is used to shift the film 3 to one side, and the sprocket 20 is loosely inserted into the shaft 21.
It is biased toward the outer rail 24 by a coil spring 23 installed between it and a washer 22 fixed to the outer rail 24 . Before loading the film 3, the sprocket 20 is locked by a locking mechanism (not shown) at a position where it can easily engage with the perforation 3c, and is unlocked in conjunction with the closing operation of the back cover.

Therefore, when the film 3 is loaded and the back cover is closed, the pawl 20a of the sprocket 20 pushes up the end of the perforation 3c of the film 3 engaged with this toward the outer rail 24, and pushes the side end 3a. It is brought into contact with the outer rail 24. As a result, the position of the film 3 in the width direction with respect to the magnetic head 25 is kept constant, and track deviation is prevented. Note that reference numeral 26 is a stopper that restricts the movement range of the sprocket 20.

The sprocket 30 shown in FIG. 4 has each pawl 31 formed into a tapered shape. As a result, when the film 3 is loaded and the back cover is closed, and the film pressure plate 33 presses the film 3 from the base surface side, the film 3 moves toward the outer rail 34 side along the tapered surface of the claw 31 engaged with the perforation 3c. It is pushed to one side. Reference numeral 35 indicates an inner rail, and reference numeral 36 indicates a magnetic head.

In the example shown in FIGS. 5 to 7, the film passage 3
Two spring members 41 are attached to one film guide 39 side of 8.
, 42 are provided, and the distance L1 from the part of these most protruding into the film path 38 to the other film guide 43 is
For example, the width D0 of the film 3 is set to −0.5 mm, and the film 3 is shifted toward a film guide 43 as shown in FIG.

Spring members 41, 4 are provided in the film passage 38.
2, an optical sensor 44 for frame detection, a roller 45,
Three positioning pins 46a, 46b, and 46c are attached. The roller 45 is provided at a position facing a magnetic head 48 attached to a film pressure plate 47, and brings the magnetic recording layer of the film 3 into close contact with the magnetic head 48 by means of an elastic support arm 49.

In addition to the magnetic head 48, a substrate 50 is mounted on the film pressure plate 47, and the film pressure plate 47 alone serves as a magnetic recording/reproducing unit. The board 50 includes a head driver IC 51 that drives the magnetic head 48, a reproduction amplifier IC 52, and a main CPU 5 that controls modulation/demodulation, recording/reproduction sequences, etc.
3rd grade has been implemented. Further, the film pressure plate 47 includes
Guide holes 56a, 56b, 56c corresponding to the positioning pins 46a, 46b, 46c are formed so that the magnetic head 48 is held at a constant position facing the roller 45.

Cutouts 47a and 47b are formed in the film pressure plate 47 at positions corresponding to the spring members 41 and 42,
The movement of the spring members 41 and 42 is prevented from being restricted by the film pressure plate 47. In addition, the film pressure plate 47
As shown in FIG.
It is attached to the back cover 59 of. Note that the spring 57 is omitted in FIGS. 5 and 7 to avoid complication. Further, as shown in FIG. 7, an electromagnetic shielding plate 62 made of a material such as Cu, Al, or ferrite is provided inside the camera body 58 near the film winding chamber 61.
This prevents electromagnetic noise from the motor 63 from being induced in the magnetic head 48.

Furthermore, if the film shifting means shown in this embodiment is used in individual cameras and printers, the recording track can always be accurately traced by the playback head, thereby improving compatibility between cameras and printers. Accurate information reading can be achieved. In addition, as described above, the magnetic head 4
8 is stable and the film 3 is always pressed against the magnetic head 48 by the roller 45, so that contact between the magnetic head 48 and the magnetic recording layer of the film 3 may be poor due to film curl or camera vibration. It never becomes.

In the example shown in FIG. 8, the spring members 41, 4
2 is replaced by a cylindrical member, for example a rod 6 with a diameter of 3 mm.
5 and 66 are attached so as to slightly protrude from one film guide 67 into the film passage 68, and the distance L2 from their peripheral edge to the other film guide 69 is, for example, the width D0 of the film 3 +0.003 mm. This is how it was done. Note that the frame indicated by the reference numeral 71 indicates the position of the magnetic head. Further, the rods 65 and 66 may be rotary rollers, or may be biased toward the film passage 68 by springs.

FIGS. 9 to 11 show the results of measuring the amount of film meandering for the above-described example using the spring members 41 and 42, the example using the rods 65 and 66, and the conventional example without a mechanism for shifting the film to one side. In these experiments, an LED was installed at a position corresponding to the magnetic head, and the film was fed while blinking at regular intervals.The film was then developed and the position of the exposed point image was measured by turning on the LED. did.

The attachment accuracy of the magnetic head 48 to the film pressure plate 47 is controlled within ±0.05 mm, and the inclination error between the film pressure plate 47 and the magnetic head 48 is controlled within ±5'. However, in the conventional example shown in Fig. 11, the swing width is as high as ±0.19 mm, and the maximum swing width is 0.28 mm.
It can even reach mm. This means that the azimuth angle is as much as 0.5°, and the azimuth loss is 10 dB. Expressed as a ratio, the reproduction output decreases by about 0.3 times. On the other hand, the spring member 4 according to the embodiment of the present invention
In the example of 1,42, as shown in Figure 9, the amplitude is ±0.
．． It has decreased to 0.03mm, and the maximum swing width is 0.04m.
m, the azimuth angle is 0.05°. Therefore, the azimuth loss is 1 dB, and the reproduction output is approximately 0.9 times as large. In addition, in the example using the rods 65 and 66, as shown in FIG. 10, the swing width is reduced to ±0.05 mm,
Maximum swing width is 0.02mm and azimuth angle is 0.03°
becomes. Therefore, the azimuth loss is 0.5 dB, and the reproduction output is approximately 0.95 times as large.

Acicular magnetic material (8500e, BET
Surface area: 40m2/g) 10 parts by weight of vinyl acetate copolymer acrylate 60 parts by weight and urethane acrylate 4
Apply magnetic coating liquid dispersed in 0 parts by weight of binder to a thickness of 5μ over the entire surface.
Digital recording was performed at a recording density of 500 BPI and a speed of 30 mm/s using a permalloy head with a cylindrical film sliding surface, a gap length of 5 μm, and a track width of 1.4 μm using a film with a substantially transparent magnetic layer coated with M. After recording, we measured the S/N at the head terminal when the film was fed in reverse and played back using the same head, and the S/N was 21 dB with a conventional film feeding system without a biasing mechanism. On the other hand, in the embodiment using the spring members 41 and 42 of the present invention, S/
N=30dB, in the embodiment with rods 65 and 66, S/
It can be seen that good recording and reproducing is performed with N=31 dB.

[0029]

As described above, according to the camera with a magnetic head of the present invention, the film is biased toward one film guide member so that the widthwise position of the film in contact with the magnetic head is maintained constant. Therefore, it is possible to prevent film meandering that causes noise, minimize azimuth loss, and prevent malfunction of the magnetic head.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing essential parts of an embodiment of the present invention.

FIG. 2 is a sectional view showing essential parts of an embodiment of the present invention.

FIG. 3 is a partially cutaway plan view showing essential parts of another embodiment of the present invention.

FIG. 4 is a sectional view showing essential parts of another embodiment of the present invention.

FIG. 5 is a perspective view showing essential parts of still another embodiment of the present invention.

FIG. 6 is a sectional view showing essential parts of the embodiment shown in FIG. 5;

FIG. 7 is a sectional view showing essential parts of the embodiment shown in FIG. 5;

FIG. 8 is a plan view showing essential parts of yet another embodiment of the present invention.

9 is a graph showing the amount of meandering of the film as the film is fed according to the embodiment shown in FIG. 5; FIG.

10 is a graph showing the amount of meandering of the film as the film is fed according to the embodiment shown in FIG. 6;

FIG. 11 is a graph showing the amount of meandering of the film during film feeding according to a conventional example.

FIG. 12 is a schematic plan view showing the relationship between a film and a magnetic head in a conventional camera.

[Explanation of symbols]

5, 33, 47 Film pressure plate 7a, 7b, 24, 34 Outer rail 10 Magnetic head unit 11a, 11b, 11c, 11d Guide protrusion 12,
25, 36, 42, 48 Magnetic head 13 Magnetic recording layer 20, 30 Sprocket 20a, 31 Pawl 23 Coil spring 38, 68 Film passage 39, 43, 67, 69 Film guide 41, 42
Spring member 45 Roller 50 Substrate 65, 66 Rod

Claims (5)

[Claims] 1. Two film guide members provided on both sides of a film path through which the film is fed to regulate the position of the film in the width direction at the exposure position; and two film guide members provided in the middle of the film path and provided on the film. a magnetic head that performs magnetic recording and reproduction by contacting the magnetic recording layer;
A camera with a magnetic head, comprising a film biasing means for biasing the film toward one film guide member and maintaining a constant position in the width direction of the film in contact with the magnetic head. 2. The film biasing means is a plurality of projecting members that act on one edge of the film along the film running direction, and presses the other edge of the film against one of the film guide members, 2. A camera with a magnetic head according to claim 1, wherein the magnetic recording layer provided on the film is stabilized at a predetermined position. 3. A camera with a magnetic head according to claim 1, wherein said film biasing means is a sprocket that engages with a perforation of the film to bias the film toward one of the film guide members. 4. The film biasing means includes a plurality of spring members provided along the film running direction and abutting one edge of the film to bias the film toward one film guide member. A camera with a magnetic head according to claim 1. 5. The film biasing means is a plurality of cylindrical members provided along the film running direction and abutting one edge of the film to bias the film toward one film guide member. Claim 1
A camera with a magnetic head.