JPH045086Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention consists of a tape guide drum having a tape guide area formed on its outer peripheral surface, and a tape running while being guided by the tape guide area. a rotating head, and configured such that a side edge of the tape is guided by a stepped portion formed on the outer peripheral surface of the tape guide drum so as to extend spirally along the tape guide area. The present invention relates to a tape guide drum in a rotary head drum mechanism of a recording/reproducing apparatus.

[Conventional technology]

Conventionally, the rotary head drum mechanism in recording and reproducing devices such as video tape recorders has generally been
It is configured as shown in the figure. That is, the rotary head drum mechanism 1 includes a lower tape guide drum 2 fixed to the chassis of the recording/reproducing apparatus, and an upper tape guide drum 3 concentrically and rotatably arranged above the lower tape guide drum 2. A plurality of rotating magnetic heads 4 are attached to the lower end of 3 so as to face the outer periphery thereof. Both drums 2 and 3 are usually made of aluminum or aluminum alloy. Further, on the outer circumferential surface 2a of the lower drum 2, an upward step 5, usually called a tape lead, is formed by cutting, and extends spirally along the lower part of the tape guide area. Therefore, the magnetic tape 6, which is spirally wound across the outer circumferential surface 3a of the upper drum 3 and the outer circumferential surface 2a of the lower drum 2, has its lower end 6a guided by the upward step 5, and is magnetically When the tape 6 runs, the lower end 6a comes into sliding contact with the upward step 5.

In this way, the structure in which the upward stepped portion 5 is integrally formed on the outer circumferential surface 2a of the lower drum 2 by cutting,
Although it has the advantage of increasing precision during machining, since the material of the lower drum 2 is aluminum or aluminum alloy, it lacks wear resistance, and the lower end 6a of the magnetic tape 6 while it is running causes the upward step. 5 had a defect that caused it to wear out prematurely. It is also possible to form the lower drum 2 integrally from a hard material with excellent wear resistance, but this would be extremely costly as the lower drum 2 would need to be polished to a sufficiently high precision. It's not practical.

Furthermore, even when integrally formed from aluminum or aluminum alloy as described above, the upward step 5 needs to be mirror-finished even if it is not surface-treated.
The finishing cutting has to be repeated several times, and therefore, the cutting of the upward step 5 itself requires a large number of man-hours and is very costly.

In order to correct such defects, as shown in FIG. 5, a downward stepped portion 5 is formed on the outer circumferential surface 2a of the lower tape guide drum 2 so as to extend spirally along the tape running area. A rotary head drum mechanism 11 in which a plurality of lead blocks 8 made of a wear-resistant material are attached along the downward step 5 in an area opposite to the tape running area of the downward step 5. is possible.
In the mechanism 11 shown in FIG. 5, the height of the end surfaces of the lead blocks 8 is reduced by pressing the lead blocks 8 with an elastic body to elastically press the end surfaces of the lead blocks 8 against the downward step portions 5. The end faces of these lead blocks 8 are regulated by the downward step portion 5, and in this installed state are made to protrude outward beyond the tape guide area of the lower drum 2. The lower end 6a of the tape 6 is guided by the upward step for guiding the tape.

[Problem that the invention attempts to solve]

However, as shown in FIG. 5, in the lower tape guide drum 2 using lead blocks 8, the lead blocks 8 are arranged in a spiral within a tolerance range so that the magnetic tape 6 runs smoothly in the tape guide area. There must be. However, as mentioned above, the upward step for guiding the tape formed on the lower drum 2 requires very high precision due to its nature, and therefore, the lower drum 2 must be formed within the above-mentioned tolerance range. It is very difficult to arrange the lead blocks 8 in a spiral and maintain this arrangement within the above tolerance range.

[Means for solving problems]

The present invention comprises a tape guide drum having a tape guide area formed on its outer circumferential surface, and a rotary head that scans a running tape while being guided by the tape guide area. In a rotary head drum mechanism of a recording/reproducing apparatus, the side edge portion of the tape is guided by a step formed on a surface so as to extend spirally along the tape guide area. PVD processes such as vapor deposition, sputtering, and ion plating
The present invention relates to a tape guide drum characterized in that it has a coating made of a wear-resistant oxide such as aluminum oxide, titania, or zirconium oxide formed by a deposition process.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on FIG. 1. The rotating head drum mechanism 1 has a spiral step 5 formed on the lower tape guide drum 2 made of aluminum oxide and having a thickness of 1 to 5 μm, for example. The structure is substantially the same as that shown in FIG. 4, except that the coating 7 of about 100 liters is formed by vapor deposition. Note that when forming the coating 7 on the lower drum 2 by a PVD process such as vapor deposition, sputtering, or ion plating, a source of deposited material such as an evaporation source,
The thickness of the coating 7 changes depending on its position relative to the surface of the lower drum 2 on which the coating 7 is formed. Therefore, in order to effectively form the coating 7 on the helical step 5, it is necessary that the helical step 5 face substantially in front of the source of the deposited material. In this way, the coating 7 is hardly formed on the outer peripheral surface 2a of the lower drum 2, and the coating 7 is mainly formed on the spiral step 5 and the upper end surface which is a surface in almost the same direction. .

Note that in normal electroplating, the current is concentrated and strong in the convex portions and becomes weaker in the concave portions, so the thickness of the coating is thicker in the convex portions and thinner in the concave portions. On the other hand, since the lower tape guide drum 2 has a spiral end portion 5, the shape of its outer circumferential surface 2a is not smooth in the vicinity of the spiral step portion 5. Therefore, if it is attempted to form the coating 7 on the spiral step 5 of the lower tape guide drum 2 by ordinary electroplating, the coating 7 formed on the spiral step 5 will have irregularities.

On the other hand, when the coating 7 is formed by the above-mentioned PVD process, the coating 7 formed on the spiral step portion 5 does not have the above-described unevenness due to the characteristics of the PVD process. In addition, since the coating 7 is formed of a wear-resistant oxide, it has extremely high wear resistance, and even if the film thickness is, for example, about 1 to 5 μm,
The lower end 6a of the tape can sufficiently prevent the upward step 5 from being worn out prematurely.
If the thickness of the coating 7 exceeds the above-mentioned range of 1 to 5μ, the time required to form the coating 7 will increase, resulting in increased production costs and the thickness of the coating 7 will become non-uniform. At the same time, the coating 7 becomes easy to peel off.

Next, regarding the case where the coating 7 is formed on the spiral stepped portion 5 of the lower tape guide drum 2 as described above, and the case where the coating 7 is not formed thereon, the lower side of the tape 6 due to the lower end 6a will be explained. The wear characteristics of the stepped portion 5 of the drum 2 will be explained based on FIGS. 2 and 3.

As shown in FIG.
It is wound in an Ω-shape around the lower drum 2, and the lower end 6a thereof slides on the stepped portion 5 of the lower drum 2 while traveling as shown by the arrow A. Further, the position θ in the circumferential direction of the spiral stepped portion 5 of the lower drum 2 in FIG. 3 is, as shown in _FIG . This L ₀
It is expressed as an angle with respect to

The experiment to investigate the wear characteristics consisted of an aluminum oxide film 7, a tape 6 coated with a cobalt-added ferromagnetic iron oxide base, a tape speed of 24 cm/sec, a tape contact pressure of 2 to 4 Kg/cm ² , and a tape running time of 1000.
carried out under the conditions of time. Note that even when the coating 7 is formed from a wear-resistant oxide other than aluminum oxide, such as titania or zirconium oxide,
Abrasion resistance similar to that in the following cases was obtained.

In FIG. 3, the case where the wear-resistant oxide coating 7 is not formed on the stepped portion 5 is indicated by a broken line, and in this case, the vicinity of the inlet and outlet of the tape 6 in the lower drum 2 In this case, the wear of the stepped portion 5 is severe and reaches a maximum of 8μ. However, the wear of the stepped portion 5 is not severe between the vicinity of the tape inlet and the tape outlet. On the other hand, the case where the coating 7 made of a wear-resistant oxide is formed on the stepped portion 5 is shown by a solid line. In this case, the wear of the stepped portion 5 of the lower drum 2 is caused by It is extremely small both in the vicinity of the exits as well as between them, and is therefore approximately uniform throughout.

As is clear from the above facts, fixed drum 2
A coating 7 made of a wear-resistant oxide such as aluminum oxide is formed on the stepped portion 5 by a PVD process.
It can be seen that the anti-wear function can be fully fulfilled.

Although the present invention has been described above with reference to its embodiments, various changes and modifications can be made to the present invention without departing from the technical idea of the present invention.

[Effect of idea]

As described above, according to the present invention, since the spiral stepped portion for guiding the tape side end of the tape guide drum has a coating made of a wear-resistant oxide, the wear resistance of the spiral stepped portion is improved. As a result, the durability of the tape guide drum can be dramatically improved without providing a lead block or the like to the tape guide drum.

In addition, since the coating made of wear-resistant oxide is formed on the spiral stepped portion of the tape guide drum by the PVD process, it is possible to obtain a coating that is uniform, extremely thin, and difficult to peel off, and therefore the tape The dimensional accuracy of the tape guide drum can be kept within the allowable error range without any particular dimensional accuracy adjustment after the coating is formed on the guide drum.
Therefore, there is no need to particularly perform finishing cutting.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of a portion of the lower tape guide drum in an embodiment of the present invention, and Fig. 2 is a plan view of the rotary head drum mechanism in a state in which the tape is wound in an Ω-shape and the upper tape guide drum is omitted. , FIG. 3 is a curve diagram showing the wear characteristics of the spiral stepped portion of the lower tape guide drum shown in FIG. 2, and FIG. 4 is a perspective view of a conventional general rotary head drum mechanism to which the present invention can be applied. FIG. 5 is a perspective view of another rotating head drum mechanism. In addition, in the symbols used in the drawings, 1...
Rotating head drum mechanism, 2...Lower tape guide drum, 3...Upper tape guide drum, 5...Spiral step, 7...Coating.

Claims (1)

[Scope of utility model registration request] The tape guide drum includes a tape guide drum having a tape guide area formed on its outer circumferential surface, and a rotary head that scans the running tape while being guided by the tape guide area, In a rotary head drum mechanism of a recording/reproducing apparatus, the side edge of the tape is guided by a stepped portion formed in a spiral manner along a guide area, wherein the spiral stepped portion is
A tape guide drum characterized in that it has a coating made of a wear-resistant oxide formed by a PVD process.