JPS637943Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head position adjustment device for a tape recorder.

One of the magnetic recording methods used in tape recorders is audio or video (hereinafter referred to as ``information'').
There is a method of recording information (called ``track'') on multiple tracks in the longitudinal direction of a magnetic tape, but in order to reproduce the information recorded using this method, it is necessary to move the magnetic head one track at a time. As the number of tracks recorded on a magnetic tape having a certain width increases, high accuracy is required for the movement of the magnetic head. Various magnetic head position adjustment devices have been proposed in the past, but a preferred one is one in which the magnetic head is attached to the tip of a partially male-threaded shaft, and the female thread that fits with the male thread is fixed to the tape recorder body. There is a type in which the position of the magnetic head is adjusted by rotating the female screw to move the shaft up and down and move the magnetic head up and down. This type of adjustment device is convenient for raising and lowering the head because it moves the head up and down by a prescribed amount when the female screw is rotated by a prescribed amount, but since it utilizes the fitting of a male screw and a female screw, It is difficult to manufacture with high precision, and when used frequently, looseness occurs in the fit and the precision in adjusting the height of the head gradually decreases. An even bigger problem is that the rotation of the screw for screw fitting is heavy, resulting in a large driving load. If the fitting is loosened in order to reduce the driving load, that is, to lighten the rotation of the screw, play will occur and the feed accuracy will decrease. Another problem is that the shaft on which the magnetic head is attached cannot be supported widely, so the tip of the shaft tends to tilt.

In view of the above points, the present invention proposes a position adjustment device that can reciprocate the magnetic head with a small driving force and high adjustment accuracy. A spherical body such as a steel ball is rotatably held on the head mounting member via an elastic member, and a drive member is provided which is rotated by a drive source when adjusting the head position. The sphere is rolled into engagement with a spiral groove formed in the groove.

According to the present invention, a sphere is held rollably on a shaft with a magnetic head attached to the tip, and this sphere is brought into engagement with a spiral groove formed on the drive shaft.
Since the magnetic head mounting shaft is configured to reciprocate through the sphere by the rotation of the drive shaft, the driving load is smaller and lighter than in the conventional adjusting device where a male thread and a female thread are fitted. In addition, since the rolling engagement between the groove and the sphere via the elastic member is used, the problem of engagement accuracy, that is, backlash, is not as big of a problem compared to the fitting of screws, and the feeding accuracy of the magnetic head, that is, adjustment. Does not affect accuracy. Furthermore, since the magnetic head mounting shaft can be supported at a relatively wide position, it is possible to prevent the mounting shaft from tilting.

The present invention will be described below with reference to the accompanying drawings.

The embodiment described below is an example in which the magnetic head position adjustment device according to the present invention is mounted on a video tape recorder, and FIG. Only the magnetic head position adjustment device and tape guide mechanism according to the present invention are shown. A fixed reel 2 and a tape guide 3 are attached to the upper surface of the base 1, and the magnetic tape T goes around the fixed reel 2, is pulled out from the outlet 2', and passes between the carburetor 4 and the pinch roller 5. It is guided by the tape guide 3 and driven to run endlessly. The magnetic head 6 is provided between a pair of tape guides 7, 7' provided along the tape running path. As clearly shown in FIG. 2, the magnetic head 6 is mounted on the tip of a shaft 8, and the upper part of the mounting shaft 8 is loosely supported by a rising portion 11a of a support block 11 mounted on the base 1. Its lower part is supported by a support plate 12 also attached to the base 1 so that it can move up and down via steel balls 9 but cannot rotate. The steel ball 9 is pushed by a coil spring 9a (see FIG. 3). A leaf spring 10 is mounted near the bottom of the mounting shaft 8 so as to be partially lifted from the circumferential surface of the shaft.
An oil-impregnated felt 13 having elasticity is interposed between the floating portion 10a of the shaft 8 and the shaft 8. This oil-impregnated felt 13 is supplied with oil from an oil supply port 8a provided on the mounting shaft 8. A hole 14 is formed in the floating portion 10a of the leaf spring 10, and a steel ball 15 is housed in the hole 14.

A drive shaft 16 is provided parallel to the mounting shaft 8, and its lower end is supported by a bearing 17 attached to the support plate 12, and its upper end is supported by a bearing 18 attached to the rising portion 11a of the support block 11. A washer 19 is provided immediately above the lower bearing 17, and a spring 20 and a collar that support the drive shaft 16 are provided between the washer 19 and the threaded portion 16a of the drive shaft 16. A disc spring may be used instead of the spring 20. The drive shaft 16 has a threaded portion 16a formed slightly below its center, and a steel plate inserted into the hole 14 of the leaf spring 10 provided at the lower part of the mounting shaft 8 described above is inserted into the valley of this threaded portion 16a. A ball 15 is rotatably engaged. A gear 21 is fixed to the upper part of the drive shaft 16, and an adjustment screw 2 for fine adjustment of the magnetic head is further provided above the upper end of the gear 21.
2 is placed. On the other hand, a step motor 23 is fixed to the base 21, and this rotating shaft 2
A gear 24 is fixed to 3a. The gear 24 meshes with a gear 21 fixed to the drive shaft 16 via an idler gear 25. 26 is a rotating shaft of the idler gear 25.

Next, the operation of the magnetic head position adjusting device constructed as described above will be explained.

When the magnetic head 6 detects a track switching signal recorded in advance on each track of the magnetic tape T, a drive pulse is supplied to the step motor 23. As a result, the step motor 23 is rotated, for example, by 15 degrees (for example, when recording and reproducing 200 tracks on a 0.5-inch wide tape), the step motor 23 is rotated by a gear fixed to the drive shaft 16 via the rotating gear 25. 21. As a result, the drive shaft 16 is 1/40
It is rotated by 9 degrees, which corresponds to the rotation. Since the steel ball 15 is engaged with the valley of the threaded portion 16a of the drive shaft 16, as the threaded portion 16a rotates, the steel ball 15 is guided by the valley and slightly moved downward. The gear ratio and the pitch of the threaded portion 16a are set in advance so that the amount of downward movement of the magnetic head 6 at this time corresponds to one track. Steel ball 15 is leaf spring 1
Due to the spring action of the floating portion 10a, the threaded portion 1
Since the steel ball 15 is lightly pressed against the threaded portion 16a, the engagement between the steel ball 15 and the threaded portion 16a is difficult to disengage, and the threaded portion 16
During rotation a, the steel ball 15 rolls in the valley, so the rotation of the drive shaft 16 is light. The steel ball 15 is gradually supplied with oil from the oil-impregnated felt 13 through the hole 14 formed in the floating portion 10a of the leaf spring 10.
Rolling becomes even easier. In this manner, each time the reproduction of each track on the magnetic tape is completed, the magnetic head 6 detects a track switching signal and is moved downward by one track. The operation of the magnetic head adjustment device is exactly the same for recording operations. When all tracks on the magnetic tape have been recorded or reproduced, the magnetic head detects a switching signal and reverses the pulse motor to move the magnetic head upward by all tracks at a time in preparation for the next recording or reproduction.

FIG. 4 shows another embodiment of the magnetic head position adjusting device according to the present invention, in which the same reference numerals as in FIG. 2 indicate the same components. The magnetic head mounting shaft 8' is loosely supported at its upper part by an upper horizontal part 11'a of a frame 11' fixed to the base 1 of the tape recorder, and at its lower part a steel ball 9 is inserted into a groove 8'a by a spring 9.
It is supported in such a way that it can be moved up and down by pressing it with a, but cannot be rotated. A head mounting base 8'b is fixed to the upper part of the head mounting shaft 8', and the magnetic head 6 is mounted on the tip of the head mounting base 8'b. A leaf spring 10 is fixed to the center of the mounting shaft 8',
Its configuration is exactly the same as in FIG. A drive shaft 16' is provided parallel to the head mounting shaft 8', and its upper and lower ends are fixedly supported by a frame 11'. A drive screw 29 is provided slightly below the center of the drive shaft 16' via bearings 27 and 28, and a steel ball 15 is pressed into the groove of this screw 29. The lower outer periphery of the screw 29 is threaded, and the lower horizontal portion 1 of the bearing 28 and the frame 11'
1'b, an elastic member such as a disc spring 30 is provided. The drive screw 29 meshes with a gear 24 fixed to the shaft 23a of the step motor 23 at its lower portion.

Now, the operation of the height adjusting device of the above embodiment will be explained.

When the magnetic head 6 detects a track switching signal recorded on the magnetic tape, the step motor 23 rotates by a predetermined angle (for example, 15 degrees). This rotation is transmitted to the drive screw 29 via the gear 24. When the drive screw 29 rotates, the steel ball 1 engaged with its valley
5 is guided by the valley and moves downward by a predetermined distance. The gear 2 is set so that the magnetic head 6 moves one track for each rotation of the step motor 23 by a predetermined angle.
4 and the gear ratio of the drive screw 29 and the pitch of the drive screw 29 are determined in advance. When recording or reproduction is completed on all tracks on the magnetic tape, the magnetic head is returned to the topmost track in the same manner as in the embodiment shown in FIG.

The present invention uses a mechanism in which a sphere is lightly pressed into a spiral groove and rolled into engagement in order to move the magnetic head up and down, so the driving force required to move the head is small and there is no play in engagement. Because there is no such thing, the adjustment accuracy can be high. Furthermore, since the number of parts can be reduced, costs can be reduced.

Although the present invention has been described above with respect to a position adjusting device for a magnetic head, it goes without saying that the technical idea of the present invention is not limited to magnetic heads and can be applied to other similar position adjusting devices.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the magnetic head position adjustment device according to the present invention installed in a video tape recorder, FIG. 2 is a sectional view of the position adjustment device shown in FIG. 1, and FIG. 3 4 is a plan view of the main part of the adjusting device, and FIG. 4 is a sectional view similar to FIG. 2 of another embodiment of the magnetic head position adjusting device according to the present invention. 1...Base, 2...Fixed reel, 3,7,
7'...Tape guide, 4...Capstan, 5
... Pinch roller, 6 ... Magnetic head, 8 ... Magnetic head mounting shaft, 9, 15 ... Steel ball, 10 ... Leaf spring, 11 ... Support block, 12 ... Support plate,
13...Oil-impregnated felt, 16...Drive shaft, 16
a... Threaded part, 17, 18... Bearing, 20... Spring, 21, 24, 25... Gear, 22...
Adjustment screw, 23...Step motor.

Claims (1)

[Scope of utility model registration request] A magnetic head mounting member supported reciprocally on a part of the tape recorder body, a spherical body rotatably held by the magnetic head mounting member via an elastic member, and a helical shape that engages with the spherical body. A magnetic head position adjustment device comprising a drive member having a groove and a drive source for rotating the drive member.