JPS637944Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for finely adjusting the position of a magnetic head of a tape recorder.

One of the magnetic recording methods used in tape recorders is audio or video recording (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. The same applies when information is recorded on a magnetic tape using this method. Since the movement of the magnetic head is usually carried out from a step motor through a gear train, many factors related to the motor and gears, such as installation errors in the motor and gears, backlash due to wear of the gears, and motor stop positions, can be caused by the magnetic head. Since this affects the position of the magnetic head, it is necessary to finely adjust the reference position (so-called zero point position) of the magnetic head not only during assembly but also during subsequent use. Adjustment of the zero point of the magnetic head is essential, especially from the standpoint of not losing compatibility with cassette tapes. However, the magnetic head fine adjustment devices proposed in the past have had problems in that they are difficult to operate, the fine adjustment effect cannot be expected to be that great, and the structure becomes complicated when trying to improve the adjustment precision.

In view of the above points, the present invention proposes a magnetic head fine adjustment device that is simple in structure and operation, and has high adjustment precision. A spherical body, such as a steel ball, is held in this head mounting member so as to be able to roll freely through an elastic member, and the spherical body has a spiral groove that is engaged with the ball and is biased in one direction by a disc spring or a spring. A driving member is provided, and an adjusting member is provided that can move the driving member in the opposite direction against the biasing of the driving member in one direction. A preferable example of the adjusting member is a lever that can be operated from the outside. There is a screw that moves back and forth as the lever rotates.

According to the present invention, the position of the magnetic head can be finely adjusted with a simple structure and operation, so that, for example, when a different cassette tape is loaded, fine adjustment can be made while playing back the video. Therefore, compatibility of cassette tapes is not lost.

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

The illustrated embodiment is an example in which the magnetic head fine adjustment device according to the present invention is mounted on a video tape recorder. FIG. Only the mechanism is 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 and is pulled out from the outlet 2'.
It passes between the capstan 4 and the pinch roller 5, is guided by the tape guide 3, and is 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 Figure 2,
The magnetic head 6 is attached to the tip of the shaft 8,
The upper part of this mounting shaft 8 is loosely supported by a rising part 11a of a support block 11 mounted on the base 1, and the lower part thereof is moved up and down via a steel ball 9 by a support plate 12 also mounted on the base 1. It is supported so that it moves but does not 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 8, and the raised portion 10 of the leaf spring 10
An elastic oil-impregnated felt 13 is interposed between a and the shaft 8. This oil-impregnated felt 1
3 is supplied with oil from an oil supply port 8a provided on the mounting shaft 8. A hole 1 is provided in the floating portion 10a of the leaf spring 10.
4 is formed, and a steel ball 15 is housed in this 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. Bearing 1
A washer 19 is provided immediately above the washer 19, 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. A threaded portion 16a is formed slightly below the center of the drive shaft 16, and the threaded portion 16a is fitted into the hole 14 of the leaf spring 10 provided at the bottom of the mounting shaft 8, which has already been described. A steel ball 15 is rotatably engaged. A gear 21 is fixed to the upper part of the drive shaft 16. On the other hand, a step motor 23 is fixed to the base 1, and a gear 24 is fixed to its rotating shaft 23a.
The gear 24 is connected to the drive shaft 1 via an idler gear 25.
It meshes with the gear fixed at 6. 26 is a rotating shaft of the idler gear 25.

Now, the magnetic head position fine adjustment device according to the present invention has a bearing 18 which supports the drive shaft 16 at the upper end.
A bearing set screw 27 is screwed onto the rising portion 11a of the support block 11, and a fine adjustment lever 28 is fixed to the upper surface of the bearing set screw 27 by suitable means such as screws. Fine adjustment lever 2
It is convenient to provide a knob 28a at the rear end of 8 for adjustment operations. As shown in FIG. 3, a scale is engraved on the outer surface of the case of the tape recorder to indicate the amount of adjustment by the lever 28.
It is preferable that if the magnetic head is moved in the direction of arrow A, the magnetic head will rise slightly, and if it is moved in the direction of arrow B, it will be slightly lowered.

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

First, height adjustment of the magnetic head 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 15 degrees (as an example, when recording and reproducing 200 tracks on a 0.5 inch wide tape), this rotation is fixed to the drive shaft 16 via gears 24 and 25. The signal is transmitted to gear 21. As a result, the drive shaft 16 is rotated by 9 degrees, which corresponds to 1/40th of a 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 moved slightly 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. The steel ball 15 is screwed into the threaded portion 16a by the spring action of the floating portion 10a of the leaf spring 10.
Since the steel ball 15 and the threaded portion 16a are lightly pressed against each other, the engagement between the steel ball 15 and the threaded portion 16a is difficult to disengage.
The rotation is light. Since oil from the oil-impregnated felt 13 is gradually supplied to the steel ball 15 from the hole 14 formed in the floating portion 10a of the leaf spring 10, the steel ball 15 rolls more lightly. In this manner, each time the reproduction of each track on the magnetic tape is completed, the magnetic head 6 detects the 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 is moved upward by all tracks at a time in preparation for the next recording or reproduction.

Now, in order to finely adjust the height position of the magnetic head 6 in such a magnetic head drive device, move the fine adjustment lever 28 by two scales in the A direction using the adjustment amount scale shown in FIG. , since the bearing set screw 27 rotates slightly counterclockwise,
A slight gap is created between the lower end surface of the bearing set screw 27 and the upper surface of the bearing 18. Therefore, the drive shaft 16
The whole is moved upward by the gap by the spring 20. Since the steel ball 15 held by the head mounting shaft 8 via the leaf spring 10 is lightly pressed and engaged with the valley of the threaded portion 16a of the drive shaft 16, the slight upward movement of the drive shaft 16 is prevented. Along with this, the mounting shaft 8 is also moved upward. As a result, the magnetic head 6 is also moved slightly upward. When the fine adjustment lever 28 is moved in the direction B, the bearing retaining screw 27 is moved slightly downward, so the entire drive shaft 16 is moved downward against the force of the spring 20. This movement is transmitted to the head mounting shaft 8 through the engagement between the threaded portion 16a and the steel ball 15, and as a result, the magnetic head 6 is moved downward.

FIG. 4 shows another embodiment of the magnetic head position fine adjustment device according to the present invention, in which only the main parts are shown in cross section, and the same reference numerals as in FIG. 2 indicate the same components. A bearing restraining plate 27' is placed on the upper surface of the upper bearing 18 of the drive shaft 16, and a fine adjustment screw 30 is provided above the bearing restraining plate 27' on a plate member 29 fixed to the rising portion 11 of the support block. Fine adjustment of the magnetic head is performed by turning this fine adjustment screw 30 with a screwdriver or the like. For example, when the screw 30 is turned to the right, the screw 30 moves downward and the bearing restraining plate 27' is pushed by the lower end of the screw 30, thereby pushing the bearing 18 and further the drive shaft 16 downward against the force of the spring 20. As a result, as described above, the magnetic head mounting shaft 8 is moved downward, so that the magnetic head 6 is slightly lowered. Fine adjustment screw 3
If you turn 0 to the left, it will move upwards, so screw 30
The drive shaft 16 is moved upward by the spring 20 by the amount of movement. The magnetic head 6 is thus slightly raised.

The drive shaft 16 in the embodiment described above has a threaded portion 16
Although a is integrally fixed to the shaft, the present invention is not limited to this type of drive shaft, but can also be used for drive shafts with a structure in which the threaded part is attached to the shaft via a bearing. Of course it's a good thing.

The present invention employs a configuration in which the magnetic head drive shaft is elastically supported at one end and moved in the axial direction at the other end to finely adjust the magnetic head, resulting in a simple structure. By providing means for moving the drive shaft in the axial direction at a location that can be easily operated from the outside of the tape recorder, fine adjustment operations have become easier. Therefore, the user can load another cassette and adjust the magnetic head to the optimum height position while viewing the image. Since there are many mechanical factors that affect the amount of movement of the magnetic head in video tape recorders, there has been a desire for a fine adjustment device that can finely adjust the magnetic head with a simple structure and operation. It is worth fulfilling.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the magnetic head position fine adjustment device according to the present invention installed in a video tape recorder together with a magnetic head drive device;
2 is a sectional view showing the fine adjustment device shown in FIG. 1 together with a magnetic head drive device, FIG. 3 is a plan view of the main part of the same fine adjustment device, and FIG. FIG. 6 is a cross-sectional view of main parts of another embodiment of the adjustment device. 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 comprising a drive member having a groove and biased in one direction, and an adjustment member capable of moving the drive member in the opposite direction against the bias in one direction. position fine adjustment device.