JPH06176433A - Magnetic recording and reproducing device and magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To cope with various kinds of magnetic tapes, to remarkably expand their use and then to improve electromagnetic conversion characteristics of the magnetic tapes by using a light source having a wavelength of <=700nm as an optical means. CONSTITUTION:A hole 34 is bored in one part of a groove part 33 provided parallel to a surface 32 behind the side of the tape loading direction in the longitudinal direction of a tape cassette 30 on the side of a back surface 31 of the tape cassette 30. Then, the tape cassette 30 is used as the light source of the wavelength <=700nm. Then, it is used by a VTR device capable of performing high density reproduction with an LED of 560nm used as the light source, so that the recording and reproducing with further higher density than the conventional can be performed. Then, since the magnetic tape having its improved electromagnetic conversion characteristic is used, a picture having a particularly superior S/N can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus and a magnetic recording / reproducing system.

[0002]

2. Description of the Related Art Generally, for example, in a cassette type video tape recorder, a magnetic recording medium (magnetic tape) housed in a cassette case has a start end and an end.
A transparent leader tape having a predetermined length and having a light transmitting property is provided. The magnetic tape is housed in the cassette case by clamping the leader tape to a reel hub rotatably supported in the cassette case. Focusing on the fact that a transparent leader tape portion is provided at the beginning of such a magnetic tape, the leader end and the end of the magnetic tape are detected by detecting this leader tape using an optical detecting means. The detection device described above has been used conventionally. This type of detection device sandwiches the running path where the magnetic tape in the cassette case runs,
For example, it is composed of a light emitting element such as an LED and a light receiving element for receiving light from the light emitting element. That is, the light emitting element is arranged at a position to be inserted into the light emitting element housing portion formed in the cassette case when the tape cassette is mounted on the magnetic recording / reproducing apparatus on the apparatus side. On the other hand, the light receiving element is arranged on the device side at a position of the tape running path that faces the through hole formed in the side surface in the cassette case of the mounted tape cassette. The leader tape is detected by detecting the light from the light emitting element that is transmitted when the transparent leader tape passes through the optical path from the light emitting element to the light receiving element. The end of the tape is detected.

A conventional example will be described below with reference to FIGS. 4 and 5. By the way, the tape cassette used in the VHS (registered trademark) type VTR has an upper half 1, a lower half 2 and a tape protecting tape as shown in FIGS. Guard panel
It consists of three. The upper half 1 has a supply reel hub 4 having a first tape reel incorporated therein.
And a reel reel hub 5 having a second tape reel.
It is possible to confirm the winding amount of the magnetic tape 6 wound on the outside, for example, transparent window portions 7 and 8 made of a material formed of transparent AS resin or the like are formed. The upper half 1, the lower half 2 and the guard panel 3 have a thickness of, for example, about 2 mm and about 1% by weight so that light does not enter the inside except for the transparent windows 7 and 8. Carbon black is mixed to some extent to give a black color.
Further, the lower half 2 is provided with a light emitting element housing 9 into which the light emitting element 13 of the tape cassette is inserted when the tape cassette is mounted on the recording and / or reproducing apparatus, and the side wall portion of the tape cassette. In the hole 1 so that the light emitted from the light emitting element 13 advances to the light receiving elements 14 and 15 of the recording and / or reproducing apparatus and the light is detected by the light receiving elements 14 and 15.
0 and 11 are provided.

That is, when the tape cassette is mounted in the recording / reproducing apparatus, the light emitting element 13 of the recording / reproducing apparatus is located in the light emitting element housing 9 of the tape cassette, and the light emitting element 13 located in the housing 9 is located. Light passes through a not-shown cutout window in the storage section 9, passes through the transparent leader tape section at the end of the magnetic tape, and the transmitted light passes through the holes 10 and 11 in the side wall of the tape cassette, that is, in FIG. When the light travels as indicated by the arrow of the alternate long and short dash line, the light is detected by the light receiving elements 14 and 15 of the recording / reproducing apparatus, and the tape running is stopped by detecting that the light has reached the end of the tape. . Therefore, the light detection by the light receiving elements 14 and 15 is wrong,
For example, if the light receiving elements 14 and 15 detect and detect light during recording / reproduction, the tape running is stopped even during recording / reproduction, and recording / reproduction cannot be performed.

That is, the light detected by the light receiving elements 14 and 15 is the light emitted from the light emitting element 13 which is transmitted through the transparent leader tape portion at the end of the magnetic tape and is incident (indicated by the one-dot chain line arrow in FIG. 5). Not only the light path) but also the light hitting the outer surface of the tape cassette diffuses inside the recording / reproducing device, and a part of it reaches the light receiving element 14 (15), or the transparent windows 7, 8 The more transmitted light is scattered inside the tape cassette, and some of this light goes out of the tape cassette through holes 10 and 11 and reaches the light receiving element 14 (15), which leads to the end of the magnetic tape. However, there is a case where the tape end detection mechanism is activated by the light from the outside and the tape running is suddenly stopped. From the viewpoint of preventing such a malfunction of the tape end detection mechanism, it is unnecessary to mix the material of the tape cassette case with, for example, a predetermined amount of carbon black as a light blocking substance, and to make it black, as described above. This is to prevent the adverse effects of light.

On the other hand, in the magnetic tape contained in the tape cassette, carbon black as a light shielding material is mixed in the magnetic layer or the back coat layer from this viewpoint, and in particular, in order to shield the light on the long wavelength side. The material is mixed in the magnetic layer. In this type of conventional device, a tungsten filament light bulb or the above-mentioned LED was used as the light emitting element (light emitting source) 13, but in any case, they had light with a wavelength of 800 nm or more. Things are used.

[0007]

By the way, in recent years, as the demands on the performance of magnetic tapes have become strict, various measures have been taken to improve the electromagnetic conversion characteristics. That is, various experiments have been conducted to optimize the content of alloy magnetic powder, non-magnetic powder, surfactant, etc. contained in the magnetic layer. However, as described above, in the conventional magnetic tape, in order to prevent malfunction of the tape end detection mechanism, a light blocking material such as carbon black is mixed in the magnetic layer or the back coat layer. In particular, when the light blocking material is mixed in the magnetic layer, the electromagnetic conversion characteristics deteriorate due to the decrease in the amount of the magnetic material. Further, if it is mixed in the back coat layer, there is a drawback that the manufacturing cost is increased. On the other hand, as described above, the tape cassette is also made black by adding carbon black to prevent malfunction of the tape end detection mechanism. For example, if you want to use another color according to your preference Had the drawback of not being able to do that.

The present invention has been made in view of the above points, and as a first invention, the detected portions formed at the start end portion and the end portion of the magnetic recording medium are detected by optical means to detect the magnetic recording medium. In a magnetic recording / reproducing apparatus for detecting the start and end, 700 nm is used as an optical means.
As a second invention, a magnetic recording / reproducing apparatus using a light source having the following wavelength is provided between a first tape reel and a second tape reel in a tape cassette having a detection hole on the side wall of the cassette. , A magnetic tape provided with a magnetic layer provided on one surface of a non-magnetic support, and a magnetic recording medium having no or a small amount of carbon black in the magnetic layer and provided with a detected portion at its start end and end. 700 as an optical means for detecting a detected portion formed at the start end and the end of the magnetic recording medium using a cassette
A magnetic recording / reproducing system using a light source having a wavelength of nm or less is provided.

[0009]

EXAMPLE FIG. 1 is a characteristic diagram showing wavelength dependence of light transmittance of a magnetic tape, and FIG. 2 is an enlarged sectional view of the magnetic tape. In the following description, referring to FIG. 4 and FIG. 5 which are conventional examples as necessary, the same parts as those will be described using the same reference numerals, but a detailed description of the same parts will be omitted. By the way, VHS (registered trademark) and S-VH
When the wavelength dependence of the light transmittance of the magnetic tape commercially available for S (registered trademark) was measured, the data as shown in FIG. 1 was obtained. In addition, in FIG. 1, A, B, C, D
Indicate magnetic tapes, respectively. As is clear from FIG. 1, it was found that the light transmittance suddenly increased from around 700 nm, and monotonically increased toward the longer wavelength side. This phenomenon can be qualitatively explained with reference to FIG. FIG. 2 is a vertical cross-sectional view of the magnetic tape. In the figure, 20 is magnetic particles such as fine powder metal magnetic powder, 21
Is a light-blocking material carbon black, 22 is a binder, 23 is a non-magnetic powder abrasive particles such as alumina,
24 is a support such as PET, 25 is a back coat layer, 26 is light of long wavelength, and 27 is light of short wavelength.

Light is a wave, and when the light hits an obstacle in which particles are dispersed, the probability that the light will be transmitted by diffraction increases if the wavelength is long. On the other hand, when the wavelength is short, the probability of scattering increases and the rate of transmission decreases. Further, the light transmittance of the magnetic tape as shown in FIG. 2 is 800 n when the magnetic tape is repeatedly used or the light emitting element 13 as shown in FIG.
It is said that it is necessary to have a wavelength of m or more and to have a light transmittance of 1.0% or less in consideration of variations in manufacturing. On the other hand, VHS (registered trademark) and S
-The light transmittance was measured by a measuring instrument using a light source having a wavelength of 800 nm based on the VHS (registered trademark) standard. As a result, the magnetic tape of D having the structure shown in FIG. The light transmittance of Further, when the back coat layer of the magnetic tape of the same D was removed and the light transmittance was measured, the transmittance was as high as 80%. This is a standard
It is far from 1.0% or less. That is,
Without the back coat layer, the magnetic tape of D cannot block the light on the long wavelength side, which may cause the tape end detection mechanism to malfunction. Therefore, VHS (registered trademark)
And S-VHS (registered trademark) VTRs cannot be used.

Here, when the light transmittance was measured using an LED having a wavelength of 560 nm as the light emitting element 13, all of the magnetic tapes A, B, C and D shown in FIG. Was found. Further, when the back coat layer of the magnetic tape D was removed and measured, it was found that the light transmittance was 0.04%. This is because if a light source with a short wavelength is used, VHS (registered trademark) and S-VHS (registered trademark) can be used without a back coat layer.
It can be used for the VTR of.

Further, in order to compare the light transmittances with and without carbon black, magnetic tapes having the following compositions were prepared. Example 1 About 100 parts by weight of Co-containing γ-Fe2 O3 as magnetic powder was suspended in about 300 parts by weight of an equal mixture of methyl ethyl ketone / toluene / cyclohexane, and the fatty acid salt of amine was used as a dispersant in this suspension. For example, Tuomin TDO
Approximately 1 part by weight (manufactured by Kao Corporation) is added, and then V is used as a binder.
10 parts by weight of AGH (vinyl chloride / vinyl acetate-vinyl alcohol copolymer manufactured by UCC) and 2 parts by weight of alumina as an additive (abrasive) are added, mixed and dispersed to prepare a magnetic paint.

Example 2 In Example 1, 3 parts by weight of polyurethane resin N2304 (manufactured by Nippon Polyurethane Industry Co., Ltd.) was used in place of VAGH as a binder, and carbon black was usually commercially available in place of alumina as an additive. A magnetic paint is prepared in the same manner as in Example 1 except that 3 parts by weight, which is smaller than the amount of the magnetic tape mixed in, is used. That is, two types of magnetic paints are prepared, one using carbon black as an additive and the other not using it. And these Example 1, Example 2
The magnetic coating material obtained in (1) is dispersed and kneaded with a paint conditioner, and then coated with a doctor blade so that the finished thickness of the magnetic layer is 4 μm, to prepare a magnetic tape. The back coat layer is not provided. In the following description, the magnetic tape containing carbon black will be referred to as CB, and the magnetic tape without carbon black will be referred to as NCB for the sake of convenience.

The above-mentioned VHS (registered trademark) and S-V
The light transmittance of CB tape and NCB tape was measured by a measuring instrument using a light source with a wavelength of 800 nm based on the HS (registered trademark) standard. The light transmittance of the former was 5% and that of the latter was 12%.
%, Which did not satisfy the standard of 1.0% or less. On the other hand, when the light transmittance was measured by a measuring instrument using an LED with a wavelength of 560 nm as a light source, CB
The light transmittance of the tape and NCB tape is 0.0 in the former case.
3, the latter was 0.08. That is, if a short wavelength light source is used, there is no carbon black, or
When the mixing amount is smaller than that of the conventional one, it is possible to satisfy the standard value of the light transmittance of 1%. This means that the amount of the magnetic substance in the magnetic layer can be increased, and the electromagnetic conversion characteristics can be improved.

By the way, the tape cassettes used in VTRs must be compatible with each other. As described above, when a short-wavelength light source is used, carbon black can be eliminated or the amount thereof can be reduced in comparison with the conventional one, so that the amount of the magnetic substance in the magnetic layer can be increased. As a result, a magnetic tape having an improved electromagnetic conversion characteristic can be obtained as compared with the conventional one. However, when this magnetic tape is used, for example, when magnetic recording is performed and it is reproduced by a conventional VTR device, the magnetic tape itself. Due to the different characteristics of, the problem that normal reproduction cannot be performed occurs. That is, there arises a problem that so-called compatibility cannot be achieved.

Therefore, according to the present invention, by eliminating the need for carbon black or reducing the amount of carbon black as compared with the conventional one, a magnetic tape having improved electromagnetic conversion characteristics is mounted in the cassette housing, With this improved electromagnetic conversion characteristic,
That is, in order to distinguish a tape cassette loaded with a magnetic tape capable of high-density recording / reproduction from other tape cassettes for the reason to be described later, its discriminating portion has the same outer shape as that of the conventional tape cassette as shown in FIG. In the tape cassette 30 having a shape, a hole formed in a part of a groove 33 provided on the back surface 31 side of the tape cassette 30 in the longitudinal direction of the tape cassette 30 and parallel to the rear surface 32 on the tape mounting direction side.
This is done by providing it as 34. Therefore,
The tape cassette 30 capable of high-density recording / reproduction in which a hole 34 is formed in a predetermined portion of the tape cassette back surface 31 is a light source having a wavelength of 700 nm or less by being clearly distinguished from other tape cassettes, for example, By using a 560 nm LED as a VTR device capable of high-density recording and reproduction, which uses a light source for detecting the detected portions formed at the start and end portions, recording and reproduction at higher density than ever before can be achieved. Is possible. As a matter of course, even if recording and reproducing are performed using a tape cassette loaded with a magnetic tape having the conventional performance in the VTR device capable of high density reproduction using the 560 nm LED as a light source, As described above, since the transmittance of the magnetic tape is less than the detection limit, the same recording / reproduction can be performed. Therefore, the compatibility issue is resolved.

Further, when high density recording / reproducing is performed by using the magnetic tape cassette 30 in which the magnetic tape having the improved electromagnetic conversion characteristics is mounted, a VTR device equipped with a magnetic head or the like capable of recording / reproducing the magnetic tape is used. By mounting at a predetermined position, recording / reproduction can be performed on a magnetic tape having an improved electromagnetic conversion characteristic by the same operation as in the past. In this case, by using the magnetic tape having the improved electromagnetic conversion characteristics as described above, an image having a remarkably excellent S / N is obtained as compared with the one recorded / reproduced by the conventional VTR device.

Further, when a green filter is provided on the front surface of the light receiving element, or when a light receiving element having sensitivity only to green is used, the sensitivity is only to a specific wavelength range, and therefore the color of the cassette half is changed. The selectivity can be expanded. Currently, the color of the cassette half of VHS (registered trademark) or S-VHS (registered trademark) is black or a color similar to black in order to prevent external light from reaching the light receiving element as described above. In other words, light with a long wavelength such as red or infrared light has a larger diffraction effect than light with a short wavelength, and V
This is because it is easy to enter even inside the TR. As described above, V having a light source in a specific wavelength range in which the sensitivity of the light receiving element is limited
In the TR device, malfunctions due to external light do not occur even if a more colorful cassette half is used. Therefore, since the cassette case can be colored, it can be selectively used according to preference. It should be noted that, in the above-mentioned embodiment, the example of using the transparent leader tape portions provided at the start end portion and the end portion of the magnetic tape as the end detection has been described, but the present invention is not limited to this, and for example, the magnetic tape It goes without saying that the present invention is also applied to a type in which a silver foil is used for the start end and the end to reflect this.

[0019]

As described above in detail, in the magnetic recording / reproducing apparatus according to the present invention, the detected portions formed at the start end and the end of the magnetic recording medium are detected by the optical means to detect the start and end of the magnetic recording medium. By using a light source having a wavelength of 700 nm or less as an optical means in a magnetic recording / reproducing apparatus that detects the end of a magnetic tape, it can be applied to various magnetic tapes and its application is dramatically expanded. The electromagnetic conversion characteristics can be improved, the manufacturing cost of the magnetic tape can be reduced, and the color of the cassette case can be supported by selecting the light receiving element corresponding to this light source. There is. Also,
In the magnetic recording / reproducing system according to the present invention, a magnetic layer is provided on one surface of a non-magnetic support between a first tape reel and a second tape reel in a tape cassette having a detection hole on the side wall of the cassette. A magnetic tape cassette is used in which a magnetic recording medium containing no or a small amount of carbon black in the magnetic layer and provided with a detected portion at its start end and end is used, and By using a light source having a wavelength of 700 nm or less as an optical means for detecting the detected portions formed at the start end portion and the end portion, this magnetic tape cassette can be used for recording / reproducing the magnetic tape cassette, etc. By installing the VTR on a predetermined position and recording / reproducing on / from this, it is possible to obtain an image with an excellent S / N in each stage as compared with the one recorded / reproduced by the conventional VTR. There is a long.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing wavelength dependence of light transmittance of a magnetic tape.

FIG. 2 is an enlarged cross-sectional view of a magnetic tape.

FIG. 3 is a bottom view and a bottom perspective view of a magnetic tape cassette according to the present invention.

FIG. 4 is a schematic overall view of a conventional magnetic tape cassette.

FIG. 5 is a plan view of removing the upper half of a conventional magnetic tape cassette.

[Explanation of symbols]

 3 Opening / closing lid 4 Supply side reel hub 5 Winding side reel hub 6 Magnetic tape 9 Storage section 30 Magnetic tape cassette 31 Bottom surface 32 Rear surface 33 Groove section 34 Detection hole

Claims (2)

[Claims] 1. A magnetic recording / reproducing apparatus for detecting the start and end of a magnetic recording medium by detecting detected portions formed at the start and end of the magnetic recording medium by optical means. A magnetic recording / reproducing apparatus characterized in that a light source having a wavelength of 700 nm or less is used as a means. 2. A magnetic layer is provided on one surface of a non-magnetic support between a first tape reel and a second tape reel in a tape cassette having a detection hole on the side wall of the cassette. A magnetic tape cassette loaded with a magnetic recording medium containing no or a small amount of carbon black and having a detected portion at the start end and the end, and at the start and end of the magnetic recording medium. A magnetic recording / reproducing system characterized in that a light source having a wavelength of 700 nm or less is used as an optical means for detecting the formed detected portion.