JPH04330661A - Tape tension control mechanism - Google Patents

Abstract

PURPOSE:To add prescribed back tension by providing a substrate where multiple electrodes are alternately arranged in a comb form at one end of a tension arm, giving positive and negative charges to the electrodes and attracting a magnetic tape. CONSTITUTION:Electrodes 31, 33 and 35 are provided for the electrode substrate 30 fixed to the tension arm 38 in contact to the magnetic tape 2. When positive and negative high voltages are alternately impressed on the electrodes 31, 33 and 35 so as to give the positive and negative charges, polarization is executed at the internal part of the magnetic tape 2 in accordance with the polarity of the electrodes, and the tape 2 is attracted to the substrate 30 with the static adsorption force of different kinds of static electricity occurring in the electrodes 31, 33 and 35 and the tape 2. Thus, the back tension of the magnetic tape 2 occurs due to dynamic friction force with the surface 37 of the substrate. Consequently, prescribed back tension can be given by controlling a potential difference between the electrodes 31 and 33 and the electrodes 33 and 35 based on the detection position of the arm 38 by an optical sensor 42.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape tension control mechanism for video tape recorders, digital audio tape recorders, etc.

0002

2. Description of the Related Art FIG. 7 is a plan view showing a tape running system of a conventional video tape recorder, and FIG.
FIG. 2 is a plan view of the tape tension control mechanism disclosed in Japanese Patent No. 0136. In FIG. 7, 1 is a tape cassette that stores the magnetic tape 2, and 3 is a supply reel hub that winds and holds the magnetic tape 2 and supplies the magnetic tape 2 to the outside of the tape cassette 1 during recording and playback. The drive reel 29 is connected coaxially with the drive reel 29. 4, 6,
Reference numerals 8, 9, 11, 12, 14, and 17 are guide pins that support the magnetic tape 2 when the magnetic tape 2 is conveyed in the tape running system. Reference numeral 10 denotes a rotating cylinder for recording signals on the magnetic tape 2 or reproducing signals recorded on the magnetic tape 2. 7 is an erase head, and 13 is an audio/control head. Reference numeral 15 denotes a capstan shaft, which is pressed against the magnetic tape 2 by a pinch roller 16, and as the capstan shaft 15, which is connected to a drive source, rotates, a driving force is transmitted to the magnetic tape 2 by frictional force with the magnetic tape 2. do. Reference numeral 18 denotes a winding-side reel hub that winds and holds the magnetic tape 2 and stores the magnetic tape 2 inside the tape cassette 1 during recording and reproduction, and a drive reel 1 that drives this.
It is connected and arranged coaxially with 9. In FIG. 8, 24
is a tension arm, and one end of the tension arm is rotatably supported around a rotation support shaft 27. In addition, a tension pin 25 is attached to the other end.
The magnetic tape 2 is supported at this portion. Further, a spring 26 whose other end is fixed by a fixing member 28 is attached to the tension arm 24.
4, always counterclockwise around the rotation support shaft 27 5
It is arranged so as to apply a biasing force to 1. Further, the other end of the brake belt 21 whose other end is fixed by the fixing member 22 is also attached to the tension arm 24, and the position of the brake belt 21 changes from 52 to 52 as shown in the figure depending on the rotational position of the tension arm 24. , or 53, and is arranged so as to apply a braking force to the reel drive shaft 29 on the tape supply side via the brake pad 23.

Next, the operation of the above configuration will be explained. As shown in FIG. 7, the magnetic tape 2 coming out from the supply reel hub 3 is supported by a plurality of guide pins,
0, the reel hub 18 on the winding side
It is wound up. At this time, the rotating cylinder 10 is
Back tension is constantly applied to the magnetic tape 2 while it is running so that the magnetic tape 2 can stably come into contact with a magnetic head (not shown) attached to the magnetic head (not shown). The magnetic tape 2 is ejected from the supply reel hub 3 in response to the driving force transmitted from the capstan shaft 15 to the magnetic tape 2 . Back tension generates braking force by pressing the brake pad 23 attached to the brake belt 21 against the drive reel 29 linked to the supply reel hub 3, controls the rotation of the supply reel hub 3, and applies this force. There is.

Control over variations in tape tension is as follows:
This is handled by the mechanism shown in FIG. In a steady state, when the back tension of the magnetic tape 2 increases, the tension arm 24, which is balanced at the position a in FIG. It rotates clockwise 50 and is displaced to position b. Accordingly, the brake belt 21 whose one end is fixed to the tension arm 24 moves in the direction 52, and the contact force between the drive reel 29 and the brake pad 23 pressed against it decreases. As a result, the braking force acting on the supply side reel hub 3 is reduced, acting to reduce the back tension to a steady state. On the other hand, when the back tension of the magnetic tape 2 decreases, the tension arm 24 cannot resist the spring force applied in the counterclockwise direction 51 around the rotation support shaft 27, and rotates in the counterclockwise direction 51 to the position c. Displace. Accordingly, the brake belt 21 whose one end is fixed to the tension arm 24 moves in the direction 53, and the contact force between the drive reel 29 and the brake pad 23 pressed against it increases. This increases the braking force acting on the supply side reel hub 3, and acts to increase the back tension to a steady state.

[0005]

[Problems to be Solved by the Invention] In the conventional tape tension control mechanism configured as described above, in response to fluctuations in tape tension, the control is fed back as a braking force of the supply side reel hub. The back torque added to is uniquely determined corresponding to the tape tension at that time. However, since the winding diameter of the magnetic tape wound around the supply reel hub is not always constant, the back tension applied to the magnetic tape changes as the winding diameter changes. That is, when the winding diameter decreases, the applied back tension increases, and when the winding diameter increases, the applied back tension decreases. Furthermore, tension fluctuations pose a problem in the rotating cylinder where the magnetic head and magnetic tape come into contact to record and reproduce signals, but when the tension fluctuates, the state of contact between the two changes slightly, resulting in poor image quality. This directly affects the sound quality. Therefore, when considering factors such as disturbances, it is desirable to detect and control tape tension in an area as close to the rotating cylinder as possible. However, in the conventional method of applying braking force to the supply side reel hub, The problem is that the control mechanism is controlled at the farthest position from the ground, making the control mechanism susceptible to external disturbances such as environmental changes. Furthermore, the conventional method has the problem that the tension in the width direction of the tape cannot be controlled.

[0006] This invention was made in order to solve the above-mentioned problems, and it is possible to apply a constant back tension without being affected by changes in the magnetic tape winding diameter of the reel hub. It is an object of the present invention to provide a tape tension control mechanism that is capable of detecting tape tension and controlling it in the width direction in an area adjacent to a rotating cylinder.

[0007]

[Means for Solving the Problems] A tape tension control mechanism according to the present invention includes a tension arm rotatably supported on a base, one end of which is fixed to the tension arm, and the tension arm is rotatably supported. A spring that applies force, a sensor that detects the position of the tension arm, and a substrate that alternately arranges three or more electrodes in a comb shape on one end of the tension arm that applies positive and negative charges and attracts the magnetic tape. , which is equipped with a high voltage generator that applies a high voltage to the electrode.

[0008] Furthermore, the control mechanism is provided with a sensor for detecting the tension in the width direction of the tape. Also,
A flexible substrate is used as the substrate.

[Operation] In the tape tension control mechanism configured as described above, the acting force received from the magnetic tape on the member in contact with the magnetic tape changes in accordance with fluctuations in the tension of the magnetic tape, and a position where this and the spring force are balanced is reached. Since the tension arm is positioned, by detecting the balanced position of the tension arm with a sensor, it is possible to detect the tape tension applied to the magnetic tape. On the other hand, when positive and negative charges are applied to the electrodes provided on the member fixed to the tension arm and in contact with the magnetic tape, the magnetic tape is polarized in accordance with the polarity of the electrode, and the electrode on the contact member and the magnetic The magnetic tape slides against the member due to the attraction force generated between the different polarities within the tape, and back tension is applied to the magnetic tape due to the dynamic frictional force with the member.

[0009]

【Example】

Example 1. FIG. 1 is a plan view showing one embodiment of the present invention, and FIGS. 2 and 3 are perspective views of the tape tension control mechanism portion of the present invention taken out from the embodiment of FIG. In the figures, parts that are the same as or equivalent to those of the conventional device described above are given the same numbers and their explanations will be omitted. 1 to 3, 30 is an electrode substrate, and the substrate surface 3
7, three electrodes 31, 33, and 35 are arranged alternately in a comb shape, and each electrode is connected via connecting terminals 32, 34, and 36, as shown in the most detail in FIG. Not connected to power. This electrode substrate 30
is fixed to one end of a tension arm 38 that is rotatably supported by a rotating shaft 40. The tension arm 38 is further fixed with the other end of a spring 39 whose one end is fixed with a spring fixing hook 41, which applies a rotational force around the rotating shaft 40 to the tension arm 38.
As shown in FIG. 1, typically the substrate surface 35 of the electrode substrate 30
This is arranged so that the biasing force acts in the direction of pressing the magnetic tape 2 against the magnetic tape 2. Further, 42 is an optical sensor incorporating a light source and a received light amount detector, and although details are not shown, one end of the tension arm 38 is inserted into the optical sensor 42 without contact. The tension arm 38 is arranged so that the aforementioned end portion of the tension arm 38 blocks the light emitted from the light source inside the optical sensor 42 toward the received light amount detector.

Next, the operation will be explained. In the tape tension control mechanism configured as described above, the acting force received from the magnetic tape 2 on the electrode substrate 30 sliding in contact with the magnetic tape 2 changes in accordance with fluctuations in the tape tension of the magnetic tape 2. The tension arm 38 is positioned at a position where the forces received from the two are balanced. In FIG. 2, as tape tension increases, tension arm 38 pivots in direction 55, and as tape tension decreases, tension arm 38 pivots in direction 54. Depending on the balance position of the tension arm 38, the other end of the tension arm 38 rotates in the direction 56 or 57, which changes the amount of light shielded by the optical sensor 42, and detects the amount of light received at this time. This allows the position of the tension arm 38 to be determined. Conversely, by detecting the position of this tension arm 38, it becomes possible to detect the tape tension that the magnetic tape 2 is subjected to. On the other hand, when positive and negative charges are applied to the electrodes 31, 33, and 35 provided on the electrode substrate 30 fixed to the tension arm 38 and in contact with the magnetic tape 2, as shown in FIG.
Corresponding to the polarities of the electrodes 31, 33, and 35, polarization occurs inside the magnetic tape 2, and the polarity between the electrodes 31, 33, and 35 on the substrate surface 37 of the electrode substrate 30 and the different polarities generated within the magnetic tape 2 is polarized. The magnetic tape 2 is attracted to the electrode substrate 30 by the attractive force of the static electricity 46, 47, and 48, and back tension is applied to the magnetic tape 2 by the dynamic frictional force with the substrate surface 37.

This electrostatic attraction force increases as the potential difference between the electrodes 31 and 33 and between the electrodes 33 and 35 increases. In general, the dynamic friction force increases as the contact force between sliding objects increases. Therefore, when controlling the back tension applied to the magnetic tape 2, it is necessary to increase the potential difference between the electrodes 31 and 33 and between the electrodes 33 and 35. If this is done, the back tension will increase, and if the potential difference is made smaller, the back tension will be decreased. Therefore, when controlling the tape tension to be constant, the position of the tension arm is detected by the optical sensor 42, and by detecting the tape tension at this time, the difference from the steady state is determined, and the direction to correct the difference is determined. By changing the voltage, the tape tension can be controlled. Also, the potential difference between the electrodes 31 and 33 and the electrode 3
By changing the potential difference between 3 and 35, it is possible to control tension fluctuations in the width direction of the tape.

Example 2. FIG. 5 shows a rotating roller 64 at one end.
, a spring fixing hook 6 attached to the support rod 65 at the other end.
a tension sensor arm 59 to which a spring 60 fixed at 2 is attached and rotatably supported by a rotating shaft 61;
It is equipped with three sets of. Further, 63 is an optical sensor incorporating three pairs of light sources and three pairs of received light amount detectors,
Although details are not shown, the tension sensor arm 59
One end is inserted into the optical sensor 63 in a non-contact manner, and the light emitted from the light source inside the optical sensor 63 toward the received light amount detector is transmitted to the tension sensor arm 59. This is arranged so that the ends are shielded.

In the tape tension sensor configured as described above, the acting force received from the rotating roller sliding in contact with the magnetic tape 2 changes in accordance with fluctuations in the tape tension of the magnetic tape 2, and the force received from the spring 60 changes. The tension sensor arm 59 is positioned at a position where the tension sensor arm 59 is balanced. In FIG. 5, when tape tension increases, tension sensor arm 59 rotates in direction 66, and when tape tension decreases, tension sensor arm 59 rotates in direction 66.
rotates in direction 67. This tension sensor arm 5
9, the tension sensor arm 59
The other end rotates in the direction 68 or 69, which changes the amount of light shielded by the optical sensor 63.
By detecting the amount of light received at this time, the position of the tension sensor arm 59 can be determined. Conversely, by detecting the position of this tension sensor arm 59, it becomes possible to detect the tape tension applied to the magnetic tape 2. By using these three sets of tension sensor arms 59, it is possible to detect tension fluctuations in the width direction of the tape, making it possible to control back tension with higher precision.

Example 3. FIG. 6 shows the substrate 30 shown in FIG.
70 is a tape guide that supports the flexible substrate 30. By using this flexible substrate 30 together with the tension sensor of the second embodiment, it becomes possible to control the tape tension in an area closer to the rotating cylinder.

[0015]

As described above, according to the present invention, there is provided a tension arm that is rotatably supported on a base, and a spring that has one end fixed to the tension arm and applies a rotational force to the tension arm. A sensor detects the position of the tension arm, and a multi-electrode of three or more is arranged on the surface of a member that contacts the magnetic tape at one end of the tension arm and applies back tension to the magnetic tape, and this electrode has positive and negative electrodes. By providing a device that adds an electric charge, it is possible to apply a constant back tension without being affected by changes in the magnetic tape winding diameter of the reel hub.
This has the effect of providing a tape tension control mechanism capable of detecting tape tension and controlling tension in the width direction of the tape.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention.

FIG. 2 is a perspective view showing the tape tension control mechanism portion of Example 1 of the present invention.

FIG. 3 is a perspective view showing an electrode substrate portion of Example 1 of the present invention.

FIG. 4 is a sectional view showing a contact portion between a magnetic tape and an electrode substrate in Example 1 of the present invention.

FIG. 5 is a perspective view showing a tape tension sensor portion according to a second embodiment of the present invention.

FIG. 6 is a perspective view showing an electrode substrate portion of Example 3 of the present invention.

FIG. 7 is a plan view showing a conventional tape running system.

FIG. 8 is a plan view showing a conventional tape tension control mechanism.

[Explanation of symbols]

2 Magnetic tape 3 Supply side reel hub 10 Rotating cylinder 30 Electrode substrate 31 Electrode 33 Electrode 35 Electrode 38 Tension arm 39 Spring 40 Rotation axis 41 Spring fixing hook 42 Optical sensor 59 Tension arm sensor 60 spring 61 Rotation axis 62 Spring fixing hook 63 Optical sensor 64 Rotating roller 65 Support rod 70 Tape guide

Claims (3)

[Claims] 1. A tension arm rotatably supported on a base, a spring having one end fixed to the tension arm and applying a rotational biasing force to the tension arm, and detecting the position of the tension arm. sensor and
One end of the tension arm is provided with a substrate in which three or more multi-electrodes are alternately arranged in a comb shape to apply positive and negative charges to attract the magnetic tape, and a high voltage generator to apply a high voltage to the electrodes. Features a tape tension control mechanism. 2. The tape tension control mechanism according to claim 1, wherein the control mechanism includes a sensor for detecting tension in the width direction of the tape. 3. The tape tension control mechanism according to claim 1, wherein a flexible substrate is used as the substrate.