JPH0465464B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention has a stepped portion formed on the outer circumferential surface thereof that extends spirally along a tape guiding area and guides the side edge of the tape. The present invention relates to a method of forming a coating on the spiral stepped portion of a tape guide drum of a rotary head drum mechanism for 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 in a spiral manner along the lower part of the tape guide area. Therefore, the magnetic tape 6 wound spirally across the outer circumferential surface 3a of the upper drum 3 and the inner circumferential surface 2a of the lower drum 2 has its lower end 6a guided by the upward step 5, When the magnetic 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 step portion 5 is integrally formed on the outer circumferential surface 2a of the lower drum 2 by cutting is as follows.
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 require extremely high cost because the lower drum 2 would need to be polished to a sufficiently high precision. It's becoming impractical.

[Problem that the invention seeks to solve]

Therefore, the present inventors used a PVD process (Physical Vapor Deposition Process) such as vapor deposition to apply an extremely thin and hard-to-peel hard coating made of a wear-resistant metal oxide such as aluminum oxide to the lower tape guide drum 2 in an upward direction. Threaded stepped portion 5
I came up with the idea of forming it. In this case, since the formed film is extremely thin, the dimensional accuracy of the lower drum 2 falls within the tolerance range, so there is no need to cut the lower drum 2 again after the film is formed, which reduces costs. It is possible to measure the reduction of

However, in the PVD process such as the above-mentioned vapor deposition, it is usually necessary to initialize the inside of the PVD apparatus to about 10 ^-5 Torr, so the time required for one process can extend to several hours. Therefore, the above PVD
It is efficient to process a large number of lower tape guide drums 2 at the same time in one process. However, as shown in FIG. 4, the width of the stepped portion 5 of the lower tape guide drum 2 is extremely small compared to the overall size of the lower tape guide drum 2. Also,
As shown in FIG. 1, in the PVD process, a deposited material from a deposited material source such as an evaporation source is diffused in a nearly radial manner. For this reason, the attitude of the lower tape guide drum 2 with respect to the source of adherend material,
That is, depending on the relative positional relationship, the step 5 may be hidden from the adherend material source 14 by other parts of the lower tape guide drum 2, and this step 5 may have abrasion resistance. The oxide film will not be sufficiently formed. Furthermore, it is necessary to form a film several times thicker than the film thickness of the film formed on the outer peripheral surface 2a on the stepped portion 5, which wears more rapidly than the outer peripheral surface 2a of the lower drum 2. .

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a recording/reproducing device for use in a recording/reproducing device that has a stepped portion that extends spirally along a tape guiding area formed on the outer circumferential surface of the device and guides the side edges of the tape. In a method for forming a coating on the spiral stepped portion of a tape guide drum of a rotating head drum mechanism, a source of a deposition material and a plurality of tape guide drums are respectively disposed in a PVD apparatus, and a coating material such as aluminum oxide, titania, zirconium oxide, etc. is disposed in a PVD apparatus. A coating made of a wear-resistant metal oxide is deposited on the stepped portion by a PVD process such as vapor deposition, ion plating, or sputtering, and at this time, the deposition material source is placed on a predetermined virtual center line. and further, the plurality of tape guide drums are spaced approximately equidistant from each other in the direction in which the imaginary center line extends from the adherend material source so that the step portions substantially face the adherend material source, and from the imaginary center line. The method is characterized in that the plurality of tape guide drums are arranged at substantially equal distances from each other, and each of the plurality of tape guide drums is rotated on its own axis.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

1 and 2 show a vapor deposition apparatus 10, which includes a rotary head drum, a lower tape guide drum 2, which has substantially the same structure as that shown in FIG. A coating 7 made of aluminum oxide and having a thickness of, for example, 1 to 5 μm is formed on the threaded stepped portion 5 having a width of, for example, about 0.2 mm, as described in detail below.

First, the configuration of the vapor deposition apparatus will be explained based on FIGS. 1 and 2. A vacuum chamber 27 is formed by a base 13 made of stainless steel or the like and a bell gear type outer casing 26 made of stainless steel or the like. There is. A vapor deposition source 14 made of aluminum oxide is placed near the base 13 on a virtual center line L ₀ extending vertically through approximately the center of the vacuum chamber 27 . This vapor deposition source 14 is filled in a crucible 20 disposed near the base 13, and an electron gun 15 is disposed adjacent to the crucible 20.

A support disk 11 having a central opening 11 a is provided in the vacuum chamber 27 , and the support disk 11 is fixed to the base 13 by a plurality of columns 12 .
A driven shaft 22 extending substantially parallel to the above-described virtual center line L ₀ is rotatably supported on the base 13 and the support disk 11 via bearings 31 and 32. The attached bevel gear 23 meshes with a bevel gear 24 attached to a drive shaft 25 driven by a motor or the like.

A sprocket 19 is attached near the upper end of the driven shaft 22, and the endless chain 21 that is attached to this sprocket 19 is also attached to each of the six sprockets 17. The middle portions of these sprockets 17 are attached to the lower ends of rotary shafts 18 which are each rotatably supported by the support disk 11 via bearings 16, and are approximately equally spaced from the virtual center line _L0 described above. They are arranged at equal angles to each other at distances.

A cylindrical drum support 35 having a supporting collar 35a at its lower end is fitted onto the upper end of the rotating shaft 18. Then, after fitting the lower tape guide drum 2 to the drum support 35 with the upper and lower sides turned upside down, the holding plate 37 presses the lower drum 2 against the drum support 35 using the fixing bolts 36.
is attached to the drum support 35.
Next, a method for forming the coating 7 made of aluminum oxide on the lower tape guide drum 2 using the vapor deposition apparatus 10 having the above configuration will be described.
The lower drums 2 made of aluminum or aluminum alloy are fitted into the two drum supports 35 with the upper and lower sides upside down, and then the fixing bolts 3
The presser plates 37 are attached to the drum supports 35 by the pressers 6, and the lower drum 2 is fixed by pressing the presser plates 37 against the drum supports 35. In this case, the six lower drums 2 are the deposition sources 1
4 in the vertical direction extending from the virtual center line L ₀ mentioned above, and are arranged almost symmetrically at equidistant positions with respect to this center line L ₀ , and at equal angles to each other. . Therefore, assuming a rotating body with the vapor deposition source 14 as the apex, the virtual center line L ₀ as the rotation axis, and the bottom surface as a circle connecting the six lower drums 2, this rotating body will have a substantially inverted conical shape. In addition, in this state, the spiral stepped portion 5 is attached to the lower drum 2.
A part of the support disk 11 substantially faces the evaporation source 14 through the central opening 11a of the support disk 11.

Next, the vacuum chamber 27 is opened using a vacuum device not shown.
Create a vacuum of about 10 ^-5 Torr. Also, before and after this,
A drive shaft 2 is used to rotate the tape guide drum 2.
Rotate 5. Note that the rotation of the drive shaft 25 is caused by the bevel gears 24 and 23, the driven shaft 22, the sprocket 19,
The power is transmitted to the lower drum 2 via the endless chain 21, the sprocket 17, the rotating shaft 18, and the drum support 35 in order, so the lower drum 2 rotates at a constant speed of, for example, about 10 r.Pm. Therefore, the portion of the stepped portion 5 of the lower drum 2 that faces the evaporation source 14 through the central opening 11a is sequentially replaced, so that during one rotation of the lower drum 2, the portion of the stepped portion 5 facing the evaporation source 14 through the central opening 11a is changed over almost the entire circumference of the lower drum 2. The entire spirally formed step portion 5 faces the evaporation source 14.

Next, the electron beam 28 is emitted by the electron gun 15, and a magnetic field is applied to the electron beam 28 by a device not shown in the figure to change the traveling direction of the electron beam 28.
Deflect 180 degrees. Therefore, the electron beam 28 enters the evaporation source 14 from almost directly above and heats the evaporation source 14 to an extremely high temperature.
A wear-resistant oxide evaporates from 4. The evaporated wear-resistant oxide passes through the opening 11a of the disk 11 and adheres to the lower drum 2, forming a wear-resistant oxide coating 7.
form. As shown in FIG. 1, the spiral stepped portion 5 of the lower drum 2 is almost opposed to the evaporation source 14, but the outer peripheral surface 2a of the lower drum 2 is oriented toward the evaporation source 14. As shown in FIG. 3, the outer peripheral surface 2 of the lower drum 2
The coating 7 is hardly formed on the part a, and the spiral step part 5 and the upper end surface 38 facing in almost the same direction as the spiral step part 5 are formed on the part a.
A coating 7 is mainly formed on the surface of the substrate and the like. Furthermore, when comparing the thickness of the coating 7 formed on two surfaces equidistant from the evaporation source 14 and facing in the same direction with respect to the evaporation source 14, the size is as shown in FIG. It has been experimentally confirmed that , is approximately inversely proportional to the evaporation angle θ formed with respect to the virtual center line L ₀ .

Therefore, as shown in FIGS. 1 and 2, by arranging the six lower drums 2 symmetrically with respect to the virtual center line _L0 and rotating these drums 2, the The coating 7 made of the wear-resistant oxide can be formed almost uniformly over the entire spiral step 5.

Note that the vapor deposition apparatus 10 configured as described above
When the evaporation angle θ with respect to the stepped portion 5 of the lower drum 2 is made smaller, the thickness of the coating 7 formed on the stepped portion 5 of the lower drum 2 becomes greater than the thickness of the coating 7 formed on the outer peripheral surface 2a. be large enough. However, in order to reduce the evaporation angle θ, the lower drums 2 must be brought closer to each other, and for this purpose the number of lower drums 2 that are subjected to the PVD process at once must be reduced. On the other hand, in bulk
In order to increase the number of lower drums 2 subjected to the PVD process, the evaporation angle θ of the lower drum 2 with respect to the stepped portion 5 is
If , the thickness of the coating 7 formed on the stepped portion 5 of the lower drum 2 cannot be made sufficiently larger than the thickness of the coating 7 formed on the outer peripheral surface 2a. This means that the thickness of the coating 7 made of wear-resistant metal oxide, which is formed on the helical step 5 which is the part of the lower drum 2 that is most likely to wear prematurely, can be adjusted to the thickness of the coating 7 that is formed on the helical step 5, which is the part of the lower drum 2 that is most prone to early wear. This means that it cannot be made sufficiently larger than that of a certain outer peripheral surface 2a. Therefore, the thickness of the coating 7 formed on the stepped portion 5 of the lower drum 2 is larger than that on the outer circumferential surface 2a, and the PVD process is applied to a certain number of lower drums 2 at once. It is important to set the evaporation angle θ that is possible. Therefore, in this embodiment, the six lower drums 2 are
The PVD process is applied, and the thickness of the coating formed on the spiral step portion 5 is 5 to 6 times the thickness of the coating 7 formed on the outer peripheral surface 2a.
The evaporation angle θ of the lower drum 2 with respect to the stepped portion 5 is set to 10 to 15.
It is set within the range of degrees.

Although the embodiments of the present invention have been described above, various changes and modifications can be made to the embodiments described above without departing from the technical idea of the present invention. For example, a rotating shaft 18 for rotating the lower drum 2
does not need to be arranged vertically, and may be inclined to some extent if necessary. In addition, in the embodiments described above, the evaporation device 1 is used to perform the PVD process.
Although 0 is used, a device that performs sputtering, ion plating, etc. may also be used. Also,
In the embodiment described above, the support disk 11 is interposed between the lower drum 2 and the evaporation source 14, but this support disk 11 is arranged above the lower drum 2, and the lower drum 2 may be configured to be suspended from the support disk 11. Further, in the embodiment described above, the movement of the lower drum 2 is only rotation, but revolution may also be added. In this case, the support disk 11 is configured to be rotationally driven, and the lower drum 2 The drive mechanism for rotating the drum 2 may also be driven to rotate together with the support disk 11.

〔Effect of the invention〕

As described above, according to the present invention, a coating made of a wear-resistant oxide is formed on the spiral step portion for guiding the tape side end of the tape guide drum. Improved wear resistance,
A tape guide drive gear with dramatically improved durability can be obtained.

In addition, since the coating made of wear-resistant oxide is formed on the spiral step part of the tape guide drum by the PVD process, it is possible to form a uniform, extremely thin coating that is difficult to peel off. The dimensional accuracy of the tape guide drum can be kept within the tolerance range without any special adjustment of dimensional accuracy after forming a coating on the tape guide drum. do not have.

In addition, since the plurality of tape guide drums are arranged so that the stepped portions are substantially opposed to the adherend material source, the thickness of the coating formed on the stepped portions is made larger than that on the outer circumferential surface of the tape guide drums. be able to.

The plurality of tape guide drums are spaced approximately equidistant from each other in a direction extending from the imaginary centerline from the source of adherend material, and disposed approximately equidistantly from each other from the imaginary centerline; Since each drum is made to rotate, a coating of wear-resistant metal oxide can be applied evenly to the helical steps of each of the multiple tape guide drums within the limited internal space of the equipment for performing the PVD process. It can be formed uniformly and efficiently.

[Brief explanation of the drawing]

Figures 1 to 3 show one embodiment of the present invention, in which Figure 1 is a vertical cross-sectional view of a vapor deposition apparatus, Figure 2 is a cross-sectional view taken along the line - - of Figure 1, and Figure 3 is a bottom view. FIG. 4, which is a vertical sectional view of a portion of the side tape guide drum, is a perspective view of a conventional general rotary head drum mechanism to which the present invention can be applied. In addition, in the symbols used in the drawings, 1...
Rotating head drum mechanism, 2... Lower tape guide drum, 5... Spiral step, 10... Vapor deposition device, 1
1... Support disk, 14... Evaporation source.

Claims (1)

[Claims] 1. The spiral step portion of a tape guide drum of a rotary head drum mechanism for a recording/reproducing device, which extends spirally along a tape guide area formed on its outer peripheral surface and has a step portion for guiding the side edge portion of the tape. In the method of forming a coating of a wear-resistant metal oxide, a coating material source and a plurality of tape guide drums are respectively disposed in a PVD apparatus to form a coating of a wear-resistant metal oxide.
The deposit is formed on the stepped portion by a PVD process, and at this time, the deposited material source is placed on a predetermined virtual center line, and the deposited material source is placed so that the stepped portion substantially opposes the deposited material source. a plurality of tape guide drums disposed approximately equidistantly from each other in a direction along the imaginary centerline from the source of deposited material and disposed approximately equidistantly from each other from the imaginary centerline; A method characterized by causing each of the two to rotate on its own axis.