JPH02297746A - Tape feed controller for magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To suppress the oscillation of an integral arm due to resonance and to stabilize the control of tape tension by supplying viscous resistance to the rotation of the integral arm around a supporting shaft. CONSTITUTION:The viscous resistance is attached on the rotation of the integral arm 24 by inserting felt 27 and grease 28 to the lower plane of the integral arm 24 around the supporting shaft. Therefore, the integral arm 24 can be provided with attenuation resistance decided by the viscous resistance against the oscillation in a rotational direction. Thereby, even when the integral arm 24 is excited with a magnetic tape 3 and its frequency coincides with the resonance frequency of the integral arm 24, the amplitude of the integral arm 24 in resonance can be suppressed according to an attenuation constant, which obtains a function to keep the tape tension constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] This invention is applicable to a helical scan type VTR,
The present invention relates to a tape running control device for a magnetic recording/reproducing device that causes a magnetic tape to be wound around a tape guide drum having a rotating magnetic head and run.

[Prior Art] In a helical scan type VTR, the magnetic tape has a long travel path, and there are many guide pins along the way to guide the tape travel. Also, since magnetic tape is wound around a tape guide drum with a rotating head,
The running resistance of the magnetic tape is large, and the running resistance changes greatly within the running route. Furthermore, the running resistance varies depending on the type of magnetic tape, the degree of use of the magnetic tape, etc., and the running resistance also changes depending on the ambient temperature and humidity.

When the running resistance of the magnetic tape changes in this way, the tape tension changes over a wide range. If the tape tension becomes excessive, the tape may stretch or the contact pressure with the guide pin may increase, making the tape more likely to be damaged. On the other hand, if the tape tension is too low, the contact between the magnetic tape and the magnetic head will become unstable, and proper output may not be obtained, or the magnetic tape may become slack and detach from the guide pin, causing damage to the tape. .

In order to avoid the above-mentioned problems, means for maintaining tape tension at an appropriate value during tape running has been proposed.

FIG. 3 is a schematic plan view showing the configuration of a tape running control device of a conventional VTR, and FIG. 4 is an enlarged view of the main parts of FIG. It has a magnetic head.

(2) is a capstan motor that connects the take-up reel stand (
6) is rotated. (7) is the winding side reel, (8)
is the supply side reel, (9) is the supply side reel stand, (10),
(11) is a brake, which is provided corresponding to the take-up side reel stand (6) and the supply side reel stand (9), respectively. Each of these brakes (10) and (11) is connected to a support shaft (12).
), (13), each reel stand (6), (
Brake shoes (14) and (1) that slide on the outer peripheral surface of
Brake arms (16), (17) with brake shoes (14), (15) having
), (9), and springs (18) and (19) that bias the brake arms (16) and (17) to rotate in one direction so as to come into sliding contact with the outer peripheral surfaces of the brake arms (16) and (9). (20),
(21) is a detection pin that detects tape tension, and is located in the middle of the tape running path from the take-up side reel stand (6) to the tape guide drum (1) and from the supply side reel stand (9) to the tape guide drum (1). They are placed in the middle of the tape running path leading to the magnetic tape (22), respectively, and come into contact with the magnetic tape (22). (2
3), (24) are integrated arms, and the brake (10),
It is constructed integrally with the brake arms (16) and (17) of (11), and pins (20) and (21) are supported at their tips. As a result, the braking force is configured to increase or decrease depending on changes in the tape tension applied to the detection pins (20) and (21). (25) is tape reel (7)
, (8) in a tape cassette containing magnetic tape (2).
2) is housed so as to run between both reels (7) and (8). (26) is a guide pin that is placed between the take-up reel (7) and the tape guide drum (1) and between the supply reel (8) and the tape guide drum (1) to guide the running of the magnetic tape (22). ) are installed between each of them.

Next, among the operations of the above configuration, the fast forward operation will be explained.

When the magnetic tape (22) is running under tension in the direction of the arrow (R) in the figure, the magnetic tape (22) is
) is in contact with the detection pin (21), which is in contact with the magnetic tape (2
2) receives tension (fl) and (fl). As a result, the tension (fl) and the resultant force (f3) of (fl) act on the detection pin (21). This resultant force (f3) generates a counterclockwise torque (Tt) about the support shaft (13).

On the other hand, the spring (19) causes the brake arm (17
), and this tensile force (f4) causes a clockwise torque (Ts
), and the reaction force (f5) that the brake shoe (15) of the brake arm (17) receives from the reel stand (9)
This generates a counterclockwise torque (Tb) around the support shaft (13).

The following equation (1) is established by each of the above torques.

Tt+ Tb= Ts ---(1) Also, the brake shoe (of the brake arm (17)) from the reel stand (9)
The reaction force (f5) to the brake shoe (15) causes the brake shoe (1
5) to the reel stand (9)
), and the tension (f6) that pulls out the magnetic tape (22) from the supply tape (22b) generates a torque (Qt) that rotates the supply tape (22b), thereby establishing the following equation (2). .

qb=qt ---(2) Here, if the running resistance of the magnetic tape (22) is large,
Tape tension (fl) acting on the detection pin (21), (
As f2) increases, the resultant force (f3) of each tape tension increases, and the counterclockwise torque (Tt)
is about to increase. However, the clockwise torque (T
Since s) hardly changes, the counterclockwise torque (Tb) decreases in an attempt to satisfy the above equation (1), and accordingly, the brake torque (Qb) decreases. As a result, the torque (Q
t) becomes smaller, the tension (f6) to pull out the tape becomes smaller, and the tape tension (f6) acting on the detection pin (21) becomes smaller.
fl) and (f2) hardly increase, and the subsequent tape tensions at the guide pin (26) and tape guide drum (1) also hardly change.

Furthermore, even when the running resistance of the magnetic tape (22) is small, the counterclockwise torque (Tt) tends to decrease as described above, but the counterclockwise torque (Tb) increases and the brake torque ( Qb) is increased, and as a result,
The torque (Qt) for rotating the supply tape (22b) increases, the tension (f6) for pulling out the tape increases, and the tape tension (fl) acting on the detection pin (21), CF
2) also hardly changes, and is stable in a state where equations (1) and (2) are satisfied.

Up to this point, we have explained the effect on the running resistance of the magnetic tape (22). However, when the running resistance changes due to changes in ambient temperature and humidity, or when the tape running speed changes, the effect on the running resistance of the magnetic tape (22) Even if the running resistance changes, the tape tension can be kept constant by acting in exactly the same way as in the above case.

In the above explanation, the fast-forward operation was taken as an example, but in the rewind operation, the tape running direction is reversed, the capstan motor (2) rotates in the opposite direction, and the idler (5) By rotating the side reel stand (9), the effect of keeping the tension of the tape (22) constant as in the case of fast forwarding operation can be obtained.

[Problem to be solved by the invention]

Since the conventional VTR tape running control device is configured as described above, the integrated arm (23).

(24) has a certain natural frequency. In both fast forward mode and rewind mode, disturbances of various frequencies are applied to the tape tension while the magnetic tape is running. If this frequency matches the natural frequency, the integrated arms (23) and (24) will resonate, making it impossible to properly control the tape tension. In order to avoid this, the natural frequency can be set apart from the predicted frequency of the outer tongue, but in conventional devices, the integrated arms (23) and (24), which are the elements that determine the natural frequency, Due to spatial constraints, it is not possible to significantly change the moment of inertia of the tape and the spring constant of the spring.As a result, the natural frequency cannot be separated from the frequency of the disturbance, and the tape tension cannot be properly controlled during resonance. The problem was that there was no.

This invention was made to solve the above problems, and even if resonance occurs due to disturbance, the vibration of the integrated arm due to resonance is suppressed by increasing the damping constant.
It is an object of the present invention to provide a tape running control device for a magnetic recording/reproducing device that can stably control tape tension.

[Means to solve the problem]

A tape running control/device for a magnetic recording/reproducing device according to the present invention includes a detection pin that contacts a magnetic tape to detect tape tension, a brake that acts on a reel stand by rotation around a spindle, and a tape that is applied to the detection pin. The present invention includes an integrated arm that is integrated so as to increase or decrease the braking force according to changes in tension, and provides viscous resistance to rotation of the integrated arm around a support shaft.

[Operation J] In this invention, since the integrated arm has a viscous resistance to rotation around the support shaft, the integrated arm has a damping resistance determined by the viscous resistance to vibration in the direction of rotation. ing. Therefore, the amplitude of the integrated arm when it resonates is suppressed according to the attenuation constant, and the tape tension is maintained at an appropriate value [Embodiment j] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2. Figure 1 is an enlarged view of the main part, Figure 2 is line II of Figure 1.
In FIG. 0, which is an enlarged cross-sectional view of II, the same or corresponding parts as the conventional device are given the same reference numerals and explanations are omitted, (27) and (28) are the support shafts of the integrated arm (24). (13) Felt and grease inserted into the lower surface around it, (29) is a retaining ring.

By inserting felt (27) and grease (28) into the lower surface of the integrated arm (24) around the support shaft, the integrated arm (24) will be able to resist viscous resistance against rotation around the support shaft. As a result, the integrated arm (24) has a damping resistance determined by the viscous resistance to vibrations in its rotational direction. Therefore, the integrated arm (2
4) is excited by the magnetic tape (22), and even if the frequency matches the resonant frequency of the integrated arm (24), the amplitude at the time of resonance of the integrated arm (24) is suppressed according to the attenuation constant, This provides the effect of keeping the tension of the magnetic tape (22) constant.

In the above explanation, we have explained what gives viscous resistance to the integrated arm (24) on the supply side reel stand (9) side. The structure for providing this is also the same as that of the integrated arm (24), so its explanation will be omitted.

[Effect of the Invention J As described above, according to the present invention, since a viscous resistance is provided to the rotation of the integrated arm around the spindle, the tape tension can be kept constant in both fast forward and rewind modes. In addition, even if the integrated arm resonates due to a disturbance, the damping constant is sufficiently large so that the amplitude can be suppressed even at the time of resonance, resulting in the effect that appropriate control can be performed.

[Brief explanation of the drawing]

FIG. 1 is an enlarged view of essential parts according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view taken along line II-II in FIG. 1, FIG. 3 is a schematic plan view showing a conventional device, and FIG. This is an enlarged view of the main part of Figure 3. In the figure, (1) is the tape guide drum, (6) is the take-up reel stand, (7) is the take-up reel, (8) is the supply reel, (9) is the supply reel stand, (10), (11)
is the brake, (20), (21) is the detection pin, (22)
is a magnetic tape, (23) and (24) are integrated arms, (
27) indicates felt, and (28) indicates grease. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Patent Attorney Masuo Oiwatt(to) 24 23 Knee'; 11(1tJ)

Claims (1)

[Claims] (1) It has reel stands on the winding side and the supply side that rotatably support the tape reel, and a rotating magnetic head, and the magnetic tape running between the reel stands comes into contact with the rotating magnetic head. A magnetic recording and reproducing device having a tape guide drum wound around the magnetic tape, a plurality of guide pins for guiding the running of the magnetic tape, a detection pin for detecting tape tension by contacting the magnetic tape, and a detection pin for detecting tape tension around the spindle. and an integrated arm that integrates the detection pin and the brake so that the braking force increases or decreases depending on the tape tension applied to the detection pin. 1. A tape running control device for a magnetic recording/reproducing device, characterized in that a viscous resistance is applied to the rotation of the integrated arm around a support shaft.