JPS5945656A - Guide post for magnetic tape - Google Patents

Abstract

PURPOSE:To run stably a tape and to improve the sound quality and image quality of a VTR, by using a guide post constituted of a barlike attenuation part consisting of a resin material and a film vapor deposited with Si on the outside circumference thereof. CONSTITUTION:A guide post is constituted of a barlike attenuation part 22 consisting of a polyamide resin of 3mm. diameter and a film 23 vapor deposited with Si on the outside peripheral surface thereof, and is fixed by press fitting to a base 2. The part 22 has a high viscosity attenuating characteristic. Deformation strain is generated in the part 22 by the bending vibration of the guide post but the oscillation damping force acts in the direction of hampering the vibration of the post by the viscosity resistance of the polyamide resin, thereby suppressing the self-vibration. The self-vibration between the tape and the post is thus suppressed and the external vibration to be transmitted to the tape is averted, whereby the tape is run stably and the sound quality and image quality of a VTR are improved.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a magnetic tape guide post (hereinafter referred to as a guide post) that guides the running of a magnetic tape (hereinafter referred to as a tape) in a magnetic recording/reproducing device. be.

Structure of a conventional example and its problems As a conventional guide post, a guide post for a video tape recorder (hereinafter referred to as VTR), which requires particularly high stable tape running performance, will be explained.

FIG. 1 shows a tape running system of a VTR. The tape 1 is attached to various guide posts 3 fixed to the base 2.
8, and travels while coming into contact with a rotary head assembly 9 for recording and reproducing image signals or various heads 10, 11, and 12 for recording and reproducing audio signals in a predetermined relative positional relationship. 13 is a supply reel, 14 is a take-up reel, and 15 and 16 are a capstan and a pinch roller that drive the tape 1. Moreover, 1γ is a tension post □ that is used to control the tension of the running tape 1 at a constant level.

Now, the accuracy of the relative movement between various magnetic heads and the tape in a VTR has a significant effect on the quality of recorded and reproduced images and sounds. In other words, as in a normal audio tape recorder, fluctuations in the speed of the running tape not only cause distortion of the audio, that is, wow, but also cause fluctuations in the image.

Also, even higher frequency (10 (D ~ 1oO00) (z)
Fluctuations in the tape speed, that is, minute vibrations of the tape, also appear in the form of image thickening, and decisively control the quality of the VTR. These fluctuations in tape running speed are caused by the vibrations of the VTR's mechanical drive system, such as the tape drive motor, being transmitted through the chassis to the various heads, guide posts, and then to the tape. Some are caused by frictional vibration, which is a type of self-excited vibration generated by sliding contact with a guide post, etc. In particular, the latter is caused by the frictional characteristics between the tape and the guide post. In recent years, so-called alloy tapes and vapor-deposited tapes, which have been put into practical use to improve the recording density of magnetic tapes, are tapes in which conventional magnetic powder is coated with a resin binder.

The surface properties of these tapes are completely different, and they are more likely to occur, posing a serious problem in putting these new tapes into practical use.

FIG. 2 shows the structure of a conventional guide post, in which a tape 19 is wound around a guide post 20 at a predetermined angle and runs at a predetermined speed U. guide post 2
0 is firmly press-fitted into the base 2 in order to accurately guide the running position of the tape. Furthermore, the material of the guide post is stainless steel, which has stable properties, in order to ensure wear resistance during tape sliding. The mechanism of generation of self-excited vibration due to tape sliding friction in a guide post having such a configuration is considered as follows. FIG. 3 is a model of a mechanical vibration system consisting of a guide post and a tape. Here, the system consisting of the mass m and the spring is a model of bending vibration of a guide post, and the belt 21 running at a constant speed U is a tape model. The equation of motion of this system is expressed as m5c'+f(x-u)+kx == O(1).

In equation (1), X is the displacement of the mass m from the static equilibrium position, f(ul is the frictional force that the mass m receives from the belt, and is a function of the relative sliding velocity <−u>).

In this system, the function in equation (1) has a negative velocity dependence (
The frictional force decreases as the relative sliding speed U increases), and the slope of the negative speed dependence (the rate of decrease in the frictional force with respect to the increase in the relative sliding speed) is determined by the mass m and the spring k. If the value exceeds the critical value, self-excited vibrations such as the stick-slip phenomenon are generated, for example.

In an actual tape running system, the coefficient of friction between the tape and the guide post has a negative velocity dependence, and is affected by various factors such as guide post rigidity, tape wrapping angle, and changes in environmental conditions such as humidity. , self-excited vibrations are easily generated.

When this self-excited vibration occurs, vibration is excited not only in the guide post but also in the tape, causing jitter and wow, and in extreme cases, vibration accompanied by a sharp sound.
This is a fatal defect for VTRs.Purpose of the Invention The present invention solves the above-mentioned defects, improves the stability of tape running, and improves the quality of audio or images of magnetic recording and reproducing devices. The present invention has a rod-shaped damping section made of a resin material, and a part or all of the outer peripheral surface of the damping section is formed with a material having higher wear resistance than the tape magnetic surface. By using a tape guide post made of a film in a magnetic recording/reproducing device, self-excited vibrations caused by sliding friction between the tape and the guide post can be suppressed, and external vibrations can be transmitted to the guide post and tape. The present invention is intended to improve the stability of tape running and improve the quality of the audio or image of the magnetic recording/reproducing device.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a partially sectional perspective view showing a guide post in the first embodiment of the present invention. In FIG. 4, 22 is a rod-shaped damping section made of polyamide resin with a diameter of 3B and a surface roughness of about 18, and 23 is a coating formed on the entire outer peripheral surface of the damping section 22 by vapor deposition of St.sub.2. This guide post is fixed to the base 2 by press-fitting, and the coating part is covered with tape (tension: 6 to 20 g, running speed: 14 degrees/banquet).
is sliding in contact. In the guide post having the above configuration, the Si-deposited coating 23 has higher wear resistance than the tape magnetic surface, so it will not be worn out by sliding. The damping section 22 made of a solid polyamide resin has strong damping characteristics. 1. Considering the vibration of the guide post, the fifth
As shown in the figure, the joint with the base 2 is the fixed end, and the bending vibration exhibiting the maximum amplitude is performed at the second part. Therefore, deformation strain occurs in the damping portion 22 of the guide post of the present invention,
During the process of generating this deformation strain, due to the viscous resistance of the polyamide resin constituting the damping section 22, a large damping force acts in a direction that impedes the movement of the guide post. In other words, providing the damping section 22 means adding a positive damping section to the right side of equation (1), and from an isometric perspective, equation (1)
) can be converted to 11-, making it possible to suppress self-excited vibrations.

You can also use external vibrations! - It is clear that the vibration of the post can also be damped by providing the damping section 22, and that the vibration of the guide post and furthermore the vibration of the tape can be easily suppressed. Therefore, by using the guide post according to the present invention, it is possible to prevent self-excited vibrations based on the sliding friction characteristics between the guide post and the tape, and furthermore to avoid external vibrations being transmitted to the guide post or the tape. can. This makes it possible to run the tape stably, and the VT
It is possible to improve the quality of R audio and images.

In the above embodiment, the damping portion 22 has a diameter of 3 rubs.
, polyamide resin with a surface roughness of about 18 was used,
There are no particular limitations on the diameter and surface roughness, and any resin material may be used. Further, although a Si film is used as the film 23, it may be a nitride or carbide of an element such as Ti or Si.In short, the film should be made of a highly wear-resistant material that does not wear out due to sliding with the tape magnetic layer. Good to have. Further, although a vapor deposition method was used as a film forming method, a plating method may also be used. Although we have described the case where the guide post is fixed to the base 2 by press-fitting, it is clear that other fixing methods may be used. Furthermore, the coating 23
The coating may be applied to the entire surface of 2, or may be applied only to the portion that contacts the tape.

Effects of the Invention As described above, the present invention provides a rod-shaped damping section made of a resin material, and a coating formed on the entire or part of the outer peripheral surface of the damping section with a material having higher wear resistance than the tape magnetic surface. By using a tape guide post made of It becomes possible to run stably, and the quality of the audio or image of the magnetic tape recording/reproducing device can be improved, and its practical effects are significant.

[Brief explanation of drawings]

Figure 1 is a perspective view of a video recorder, Figure 2 is a partial cross-sectional perspective view of a conventional guide post, Figure 3 is a model diagram to explain the sliding friction between the guide post and tape, and Figure 4. 5 is a partially cross-sectional perspective view showing a guide post in an embodiment of the present invention, and FIG. 5 is a diagram showing a vibration state of the guide post. 2...Base, 19... ・Tape, 22...
...Attenuation part, 23...Coating. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3

Claims (2)

[Claims] (1) A rod-shaped damping part made of a resin material and having an axial direction substantially perpendicular to the running direction of the magnetic tape, and a part or the entire outer circumferential surface of the damping part having more wear resistance than the magnetic surface of the magnetic tape. A magnetic tape guide post comprising a coating made of a material having a high temperature, the coating being able to come into contact with the magnetic tape. (2) The magnetic tape guide post according to claim 1, wherein the coating is made of Si, Ti nitride or carbide.