JPS61220162A - Drum for tape guide - Google Patents

Abstract

PURPOSE:To improve the wear resistance of a tape running surface and to prevent the occurrence of noises due to static electricity by forming the tape running surface of a drum for guide with conductive ceramic materials and forming a hard plating layer on a tape guide surface. CONSTITUTION:A drum 3 for video tape guide consists of a cylindrical tape running surface 4a and a guide member 11 having a guide surface 4 which is cylindrical on a plane and has an inclined part. The running surface 4a of a drum body 3a of this drum 3 consists of conductive ceramic materials ground to a prescribed dimension precision. These ceramic materials have hardness higher than that of magnetic powder materials included in a magnetic tape and have a very high wear resistance. Since 5-2% TiC, TiN, or the like having the electric conductivity is dispersed uniformly in an Si3N4 sintered body to produce these ceramic materials, they have a conductivity to prevent the occurrence of the noise due to static electricity.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a tape guide drum.

[Technology]

As is well known, the head drum assembly of a conventional tape recorder, such as a household magnetic head rotary VTR, has a first
As shown in the figure, which is a side view of an example of essential parts, two magnetic heads 2 are attached to the lower surface of a rotating (head) drum (upper drum) 1, and a fixed tape guide drum (lower drum) 3 is mounted below the magnetic heads 2. is provided, the video tape 5 is guided by a tape guide 6, and the video tape 5 is guided by a guide surface 4 on the guide drum 3.
The tape 5 is configured so that the lower edge of the tape moves along the rotating surface of the rotary head drum 1, and the tape 5 is run diagonally along the running surface 4a of the tape guide drum 3 and the guide surface 4. At the same time, by rotating the rotating drum 1, the magnetic head 2 is made to scan the video tape 5 obliquely to the running direction of the video tape 5, thereby recording or reproducing information.

In this type of conventional video tape recorder, the scanning direction of the magnetic head 2 on the video tape 5 is oblique to the tape traveling direction, and the pitch of the signal tracks recorded on the video tape 5 is extremely high density ( For example 20~60μ
m, etc.) Therefore, if the scanning position of the magnetic head 2 relative to the video tape 5 changes even slightly, information cannot be recorded/reproduced properly, causing vertical vibration of the video tape relative to the magnetic head 2. It is necessary to always be able to travel to a predetermined position with high precision without any trouble.

However, the tape guide drum 3 in the head drum assembly of this type of video tape recorder is generally made of aluminum alloy, especially silicon eutectic, which has relatively good wear resistance, because of its light weight and good workability. It is made of an aluminum alloy material, and this alloy material has a lower hardness than the various magnetic powders included in the recording surface of the videotape 5. Therefore, when the videotape runs in contact with the recording surface of the videotape 5, the guide drum will deteriorate over time. Particularly, the guide surface 4 of the videotape guide section No. 3 is worn out, and as a result, the running position of the videotape inevitably changes. FIG. 2 shows an enlarged cutaway sectional view of the tape guide portion of the guide drum 3 in FIG. 1. Reference numeral 4b denotes a tool escape portion during cutting of the guide surface 4 and running surface 4a.

For the reasons mentioned above, conventional video tape recorders of this type have the disadvantage of not being able to record/reproduce information stably and well over a long period of time.

In addition, the tape running surface 4a is similarly worn and its surface roughness changes, causing stick-slip during tape running, and abrasion powder on the drum surface and magnetic powder from fallen tape due to contact running of the video tape. There was a possibility that the head gap of the magnetic head 2 would become clogged, which would prevent image reproduction.

〔the purpose〕

The present invention has been made in view of the problems of the conventional example as described above, and at the same time eliminates the drawbacks of the conventional example as described above, it also reduces wear due to contact running of the tape and maintains the running position of the tape for a long period of time. The purpose of the present invention is to provide a tape guide drum that can properly regulate the

〔Example〕

The present invention will be explained below based on examples. In Figure 3,
A side view of an embodiment of the tape guide drum 3 according to the present invention is shown, and the same 1fc and the same reference numerals as in the conventional example shown in FIGS. 1 and 2 indicate the same reference numerals. The videotape guide drum 3 consists of a cylindrical tape running surface 4a and a guide member 11 having a cylindrical planar guide surface 4 and an inclined portion. A feature of the present invention is that at least the tape running surface 4a of the drum body 3a of the guide drum 3 is made of a conductive ceramic material that has been ground to a predetermined dimensional accuracy. This ceramic material has higher hardness than the magnetic powder material contained in the magnetic tape and has extremely high wear resistance. Furthermore, this conductive ceramic material is manufactured by uniformly dispersing 5 to 25 qb of electrically conductive TiC, TiN, etc. in a sintered body of silicon nitride (S is N4). be. The reason for using these conductive ceramic materials having an electrical conductivity of 10 to 10 s/cyx is that ordinary ceramic materials are non-conductive (i.e., have an electrical conductivity of 10 to 10 s/cyx).
Qs/am), if the video tape wound around the guide drum runs in contact with the guide drum, static electricity may be generated and the image quality may deteriorate due to noise.

FIG. 4 (Al, 81, (C) is an enlarged sectional view of the main part showing the method of forming the guide portion of this embodiment. First, in FIG. 4, a guide drum made of conductive ceramic is A groove 1.0 is formed in advance on the main body 3a along a predetermined inclined surface of the guide portion, and an activation treatment is performed so that a plating layer can be formed on the surface thereof.

Then, as shown in FIG. 4, hard electroless nickel plating N (exaggeratedly shown) is formed. Next, as shown in FIG. 4 (CI), the tape guide surface 4 that guides one end edge of the video tape 5 is cut using a diamond cutting tool using a known lead processing machine to provide the clearance required for the cutting process. The portion 4b is provided and formed by mirror cutting with a predetermined dimensional accuracy.

Electroless nickel plating has a surface hardness of about 400 to 500° Vickers Hv, compared to the surface hardness of silicon eutectic aluminum alloy materials commonly used in the past, which is about 140′ Vickers Hv. Therefore, the wear resistance during running in contact with the tape is significantly improved. Note that the ceramic material has a stiffness that is seven times higher than that of an aluminum alloy, so it can be constructed with a relatively thin wall.
Weight can be saved.

[Other Examples]

FIG. 5 shows another embodiment of the guide section according to the present invention.

In this embodiment, the guide member 11 in the first embodiment shown in FIG. 3 is intermittently divided into a plurality of guide members 11a, and the method of forming them is completely similar to the method described above. With this configuration, foreign matter attached to the edge of the tube that runs in contact with the guide surface of the videotape will fall through the gaps and there is no risk of it adhering to the upper part of the guide surface, thereby improving the accuracy of the guide surface. can be maintained,
Contributes to stable image quality.

Furthermore, as another embodiment, although not particularly illustrated, 1
The tape running surface of the guide drum is preformed into a hollow cylindrical shape using the conductive ceramic material mentioned above, and an ordinary aluminum alloy drum that fits into the inner diameter of this hollow cylinder is cold-fitted, or a ceramic hollow cylindrical member is used. It can also be integrally formed by shrink fitting, adhesion, or the like. According to this configuration, the amount of this type of relatively expensive ceramic material to be used can be reduced, and the material cost can be reduced.

In all of the examples above, the linear expansion coefficient of this type of ceramic material is approximately 3 to 7×1067°C, and the linear expansion coefficient of conventional aluminum alloy is 20×10°C.
/”C, it has the advantage that the adverse effect on image quality due to temperature changes is significantly reduced.Although the above embodiment has been explained for the case of a videotape drum, the present invention is of course applicable to this. For example, it is not limited to digital audio,
It can also be applied to tape recorders (DAT) and the like.

〔effect〕

As explained above, according to the present invention, the tape running surface of the tape guide drum is made of a conductive ceramic material, and a hard plating layer is formed on the tape guide surface, so that the tape does not run in contact with the drum. The abrasion resistance of the guide surface and tape running surface has been significantly improved, making it possible to guide the tape to the correct position over a long period of time, making stable and good information recording/reproduction possible. In addition, the use of conductive ceramic material eliminates the generation of noise due to static electricity, and the material's small coefficient of linear expansion reduces the negative effects of temperature changes, making it possible to obtain high-quality recording/playback characteristics. Became.

[Brief explanation of the drawing]

FIG. 1 is a side view of essential parts of an example of a head drum assembly of a conventional VTR, FIG. 2 is an enlarged cutaway sectional view of the tape guide portion of the guide drum in FIG. 1, and FIG. 3 is an inventive invention. FIG. 4 (A) is a side view of an embodiment of the guide drum according to
J, (Bl, tc+a, each explanatory diagram of the method of forming the guide part of this embodiment, FIG. 5 shows another embodiment of the guide part. 1. Rotating head drum 3.・・・・・・
...Video tape guide drum 3a...Drum body (made of conductive ceramic material) 4...Guide surface 4a...Tape running surface 5... ...Video tape 10...Mizo

Claims (1)

[Claims] 1) A tape guide drum having a tape running surface around which a tape is wound and running, and a guide surface guiding one edge of the tape, at least the tape running surface being made of a conductive ceramic material. A drum for a tape guide, characterized by having a formed shape. 2) The tape guide drum according to claim 1, wherein the guide surface is formed of a hard plating layer member having the guide surface.