JPH0312365B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for adjusting the height of a magnetic head, and in particular, to adjusting the relative height of a plurality of magnetic heads assembled to a cylinder used in a VTR playback cylinder. The present invention relates to a method for adjusting the height of a magnetic head to adjust the deviation of the magnetic head.

[Background of the invention]

First, a VTR playback cylinder and a conventional magnetic head height adjustment method will be explained using drawings.

FIG. 3 is a plan view showing an example of a VTR playback cylinder, FIG. 4 is a central sectional view of the VTR playback cylinder according to FIG. 3, and FIG. 5 is for explaining a conventional magnetic head height adjustment method. FIG.

In FIGS. 3 and 4, 2 is a cylinder, and 4 is a head base made of brass, for example, to which the magnetic head 1 is attached.
The magnetic heads 1 are assembled onto the upper surface of the cylinder 2 by means of assembly screws 5 so that the tips of the magnetic heads 1 are located on the outer circumferential side of the cylinder 2. 6 is
A screw hole 7 drilled in the back side of the head base 4 of the cylinder 2 is an adjustment screw that is screwed into the screw hole 6 and can push the head base 4 with its tip to bend it. ε is the difference between the height a of the left magnetic head 1 and the height b of the right magnetic head 1, and this is the relative height deviation.

In the VTR reproducing cylinder constructed in this manner, in order to correctly reproduce recordings on a magnetic tape (not shown), the relative height deviation ε of the magnetic head 1 must be within several microns.

The conventional magnetic head height adjustment method will be explained below [Hitachi Video Deck U Type Chassis Service Book (Video No. 18-2, 1977)]
)]. The outline of this adjustment method is to press the tip of the adjustment screw 7 against the head base 4 and bend the head base 4 to perform adjustment in the height direction.

A more detailed explanation using FIG. 5 is as follows.

Cylinder 2 is set on rotary table 8, which provides accurate 180° indexing. The tip of the magnetic head 1 is photographed by the TV camera 9, and the operator places the cursor line c on the enlarged image p to read the height of the magnetic head 1. Next, the rotary table 8 is rotated, and the magnetic head 1 facing the magnetic head 1 is rotated.
Read the height of by similar means. Compare these two read values and move the lower magnetic head 1 by the difference between the above read values to the driver 41 while looking at the image p.
Adjustment is made by rotating the adjusting screw 7.

Since this adjustment work is time-consuming, there are problems that need to be improved.

In order to deal with this, automation of the above-mentioned adjustment work was considered, but there were the following difficulties in automation.

The first difficulty is that the deflection of the head base 4 due to the adjustment screw 7 must be within a predetermined range. If the amount of deflection of the head base 4 is small, the head base 4 can be moved by a slight external force.
This causes unnecessary deflection, which causes the height of the magnetic head 1 to be incorrect during use of the VCR. On the other hand, if the deflection of the head base 4 is large, the tip of the magnetic head 1 will come into contact with the magnetic tape obliquely.
The playback function does not work properly.

The second difficulty is that the rotational phase of the adjusting screw 7 must be accurately recognized. When the operator makes adjustments, the height of the tip of the magnetic head 1 can be adjusted while looking at the enlarged image p. However, when automated, it takes time to recognize the height of the tip of the magnetic head 1. Therefore, the automatic adjustment device must operate without information during the rotation of the adjustment screw 7. For this reason, it is necessary to recognize the rotational phase of the adjusting screw 7 before adjustment and to accurately rotate the adjusting screw 7 by the required amount from that position.

Due to the above-mentioned difficulties, there was a problem in that this adjustment work could not be automated.

[Purpose of the invention]

The present invention improves the problems of the prior art described above, and provides a magnetic head that can automatically adjust the relative height deviations of a plurality of magnetic heads assembled to a cylinder used in a VTR playback cylinder. The object is to provide a head height adjustment method.

[Summary of the invention]

The structure of the magnetic head height adjustment method according to the present invention is that a plurality of head bases having magnetic heads attached thereto are assembled on the top surface of a cylinder so that the tips of the respective magnetic heads are on the outer circumferential side of the cylinder.
The height of the magnetic head of the VTR playback cylinder is
In the magnetic head height adjustment method, the adjustment screw is screwed into a screw hole drilled on the back side of the head base of the cylinder and the drive shaft of the driver is rotated to give a deflection to the head base for adjustment. , the driver is a driver equipped with a torque detection device on its drive shaft, the contact point between the adjustment screw and the head base is detected by the torque detection device for all magnetic heads, and the adjustment screw is adjusted from the contact point. By rotating the magnetic head by a predetermined amount using the driver, the head base is larger than the limit at which it is deflected by external force, and smaller than the limit at which the attitude of the tip of the magnetic head affects the signal reading and reproducing function. After performing coarse adjustment of the magnetic head by deflecting the head base by an initial amount within the range, the position of the magnetic head to be finely adjusted is recognized, the amount of magnetic head adjustment for that magnetic head is calculated, and the adjustment amount for the magnetic head is calculated. The initial position of the adjusting screw is detected by the torque detection device, and the adjusting screw is rotated from the initial position by the magnetic head adjustment amount using the driver, thereby finely adjusting the magnetic head. It is something.

[Embodiments of the invention]

Before entering into the description of the embodiments, basic matters related to the present invention will be explained.

In the magnetic head height adjusting method of the present invention, the magnetic head height is adjusted separately into coarse adjustment and fine adjustment. The above-mentioned first difficulty was solved by giving a predetermined amount of rotation to the adjusting screw in advance at the stage of rough adjustment to give an appropriate deflection to the head base. The second difficulty was also solved by providing a torque detection device to accurately detect the phase (ie, initial position) of the adjustment screw before adjustment.

The structure of the present invention based on the above-mentioned basic matters will be described in more detail as follows.

The drive shaft of the driver that rotates the adjustment screw is equipped with a torque detection function, and after detecting the point of contact between the adjustment screw and the head base, a predetermined amount (in this case,
Make coarse adjustments to all magnetic head heights by rotating the adjustment screw by an amount (no magnetic head adjustment has been calculated) to deflect the head base an initial amount. Next, after recognizing the position of the magnetic head to be finely adjusted and calculating the adjustment amount related to the magnetic head adjustment amount, the initial phase of the adjustment screw of the magnetic head is detected by the torque detection function, and from that point. The adjustment screw is precisely rotated by the driver by an amount corresponding to the adjustment amount.

Examples will be explained below.

FIG. 1 is a cross-sectional view of a main part of a magnetic head height adjusting device used to implement a magnetic head height adjusting method according to an embodiment of the present invention, and FIG. It is a control block diagram showing the control structure of a height adjustment device.

To give an overview of this embodiment device, the driver is a driver 41A having a drive shaft 13 with a strain gauge 34, which is a torque detection device, and a drive cylinder 10 which is a moving device that moves this driver 41A in the direction of the drive shaft. , a pulse motor 14 for rotating the drive shaft 13, a rotary table 8 on which the cylinder 2 is mounted and fixed and capable of rotating the cylinder 2, a TV camera 9 for observing the tip of the magnetic head 1, and the TV. An image processing device 35 that processes the image from the camera 9, and the amount of magnetic head adjustment can be calculated based on data related to the height of the tip of the magnetic head 1 from the image processing device 35, and the strain gauge When a torque generation signal is received from 34, if the magnetic head adjustment amount has been calculated, the pulse motor 14 is rotated by the magnetic head adjustment amount, and if not, the pulse motor 14 is rotated by a predetermined angle. The microprocessor 32 has a microprocessor 32 that can be rotated by 30 degrees.

More specifically, the drive cylinder 10 attached to the pedestal 12 can move the movable base 11 of the driver 41A up and down by being guided by its slide 29 and the guide 12a provided on the pedestal 12. A drive shaft 13 related to the drive section is coupled to a pulse motor 14 through a coupling 15 and is held on the movable base 11 via ball bearings 16 and 17. A hexagonal hole 18 is bored at the lower end of the drive shaft 13, into which a hexagonal ball 20 at the upper end of the shaft 19 is fitted.
This shaft 19 is held by a ball bearing 21, and this ball bearing 21 is held by the movable base 11 via rubber 22. Therefore, although the rotational force from the drive shaft 13 is transmitted to the shaft 19, it has compliance in the radial direction. Further, a spline hole 23 is bored in the lower part of the shaft 19, and a spline shaft 25 of the head of the adjustment driver 24 is fitted into this spline hole 23. This adjustment driver 24 receives a downward force from a spring 26. In addition, adjustment driver 2
A hexagonal ball 28 is provided at the lower end of 4.
This hexagonal ball 28 is fitted into a hexagonal hole 27 in the head of an adjustment screw 7A for adjusting the height of the magnetic head, so that adjustments can be made by rotating the adjustment screw 7A. A strain gauge 34, which is a torque detection device capable of detecting the amount of torque, is attached to the drive shaft 13, and the output from the strain gauge 34 is transmitted through a slip ring on a mold 31 fixed to the drive shaft 13. 38, brush 39,
The signal is sent via a lead wire 40 to an A/D converter 36, which will be described later. The rotary table 8 holds the cylinder 2 by means of a chuck 30 and can rotate and index the cylinder 2 through 180 degrees. The tip position of the magnetic head 1 is
It is designed to be photographed by a TV camera 9.

The control configuration will be explained using FIG. 2. The microprocessor 32 instructs the motor drive circuit 33 to drive the pulse motor 14. The image processing device 35 also processes images from the TV camera 9,
Data regarding the height of the magnetic head 1 is sent to the microprocessor 32. The signal from strain gauge 34 is digitized by A/D converter 36 and sent to microprocessor 32. Further, the microprocessor 32 sends a command to a motor drive circuit 37 that drives the rotary table 8.

The operation of the magnetic head height adjusting device constructed in this way will be explained using FIGS. 1, 2, and 6.

FIG. 6 is a sectional view of a main part for explaining the adjustment operation of the magnetic head height adjustment device according to FIG. 1.

Cylinder 2 is placed on rotary table 8, chuck 3
When set to 0, the driver 41A descends and the tip of the adjustment driver 24 comes into contact with the head of the adjustment screw 7A while being pushed by the spring 26 from behind.

When the pulse motor 14 is turned ON, the adjustment driver 24 rotates, and when the hexagonal ball 28 and the hexagonal hole 27 on the head of the adjustment screw 7A are in the same phase,
The adjustment driver 2 is adjusted by the pressing force of the spring 26.
4 further descends, and the hexagonal ball 28 and hexagonal hole 27
The two fit together. The state at this time is as shown in FIG. 6a, and almost no torque is generated on the drive shaft 13. When the pulse motor 14 rotates further, the adjusting screw 7A hits the head base 4, resulting in the state shown in FIG. 6b. At this time, torque is generated by the reaction force from the head base 4, and based on the signal from the strain gauge 34, the microprocessor 32 recognizes the contact between the head base 4 and the adjusting screw 7A. At this point, data on the height of the tip of the magnetic head 1 has not been input from the image processing device 35, and the magnetic head adjustment amount has not been calculated.
The microprocessor 32 is a motor drive circuit 33.
a predetermined amount (determined in advance through experiments)
A rotation command is given to the head base 4 by an initial amount. The initial amount is the amount by which the head base is deflected within a range that is greater than the limit at which the head base is deflected by external force and smaller than the limit at which the posture of the tip of the magnetic head affects the signal reading and reproducing function. be.

Subsequently, the driver 41A is raised, the rotary table 8 is rotated 180 degrees, and the other head base 4 is also deflected by the same initial amount in the same manner as described above. After the rough adjustment is performed in this way, the following fine adjustment is performed.

The microprocessor 32 issues commands to the image processing device 35 and receives data on the height of the tip of the magnetic head 1. Next, the rotary table 8 is rotated, and the tip height data of the other magnetic head 1 is obtained. The microprocessor 32 compares these two data and
calculates the adjustment amount for the lower magnetic head 1, that is, the difference between the height of the higher magnetic head and the height of the lower magnetic head. This value is the amount that should be finely adjusted. By rotating the rotary table 8,
The lower magnetic head 1 is located below the driver 41A, and the driver 41A descends, and the tip of the adjustment driver 24 comes into contact with the head of the adjustment screw 7A while being pushed by the spring 26 from behind. . The pulse motor 14 rotates, and the hexagonal ball 28 and hexagonal hole 27 fit together in the same manner as in the coarse adjustment, resulting in the state shown in FIG. 6c. The strain gauge 34 detects the torque due to the reaction force from the head base 4 the moment they are fitted. When the microprocessor 32 detects the torque detection signal, it has already calculated the adjustment amount of the magnetic head to be finely adjusted as described above, so it issues a new rotation command for the adjustment amount and performs the adjustment. The driver 24 rotates by that amount, and the fine adjustment is completed. Then, the driver 41A rises and completes the entire operation.

According to the embodiment described above, the problem of adjusting the height of the magnetic head by pressing the adjustment screw against the head base and flexing it is solved by automation, so that it is inexpensive and uniform. This has the advantage that it is possible to produce VTR playback cylinders that are of high quality.

In this embodiment, an A/D converter 36 is provided between the strain gauge 34 and the microprocessor 32.
However, a threshold value discrimination circuit is provided in place of the A/D converter, and its output is sent to the motor drive circuit 3.
3 may be input. In this case, when the input from the strain gauge 34 exceeds the threshold, the pulse motor 14 stops and the microprocessor 32
indirectly detects the torque generation signal from the strain gauge 34.

Further, in this embodiment, the strain gauge 34 is used as the torque detection device, but a pulse motor current detector may be provided to detect the torque.

Furthermore, in this embodiment, a command is given from the microprocessor 32 to the image processing device 35,
The microprocessor 32 receives data on the height of the tip of the magnetic head 1, and also sends commands to the motor drive circuit 37 to rotate the rotary table 8. However, these commands are not necessarily transmitted by the microprocessor. It is not necessary to give the command from the setter 32; for example, a sequence controller may be separately provided and the command may be issued from this sequence controller.

Furthermore, in this embodiment, a case has been described in which two magnetic heads 1 are attached to the cylinder 1 facing each other, but the present invention can be similarly applied to a case where there are three or more magnetic heads. .

〔Effect of the invention〕

As explained in detail above, according to the present invention,
It is possible to provide a magnetic head height adjustment method that can automatically adjust the relative height deviation of a plurality of magnetic heads assembled to a cylinder used in a VTR reproduction cylinder.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part of a magnetic head adjusting device used to implement a magnetic head height adjusting method according to an embodiment of the present invention, and FIG. 2 is a sectional view of a magnetic head height adjusting device according to FIG. FIG. 3 is a plan view showing an example of a VTR reproducing cylinder; FIG. 4 is a central cross-sectional view of the VTR reproducing cylinder according to FIG. 3; and FIG. 5 is a conventional one. FIG. 6 is a schematic diagram for explaining the magnetic head height adjustment method of FIG. 1...Magnetic head, 2...Cylinder, 4...Head base, 6...Screw hole, 7A...Adjustment screw,
8... Rotating table, 9... TV camera, 10...
... Drive cylinder, 12 ... Frame, 13 ... Drive shaft, 14 ... Pulse motor, 24 ... Adjustment driver, 32 ... Microprocessor, 34 ... Strain gauge, 35 ... Image processing device, 41A ... driver.

Claims (1)

[Claims] 1. A plurality of head bases having magnetic heads attached thereto are assembled on the top surface of a cylinder such that the tips of the respective magnetic heads are on the outer circumferential side of the cylinder.
The height of the magnetic head of the VTR playback cylinder is
In the magnetic head height adjustment method, the adjustment screw is screwed into a screw hole drilled on the back side of the head base of the cylinder and the drive shaft of the driver is rotated to give a deflection to the head base for adjustment. , the driver is a driver equipped with a torque detection device on its drive shaft, the contact point between the adjustment screw and the head base is detected by the torque detection device for all magnetic heads, and the adjustment screw is adjusted from the contact point. By rotating the driver by a predetermined amount,
A roughness of the magnetic head that deflects the head base by an initial amount within a range that is greater than the limit at which the head base is deflected by external force and smaller than the limit at which the posture of the tip of the magnetic head affects the signal reading and reproducing function. After making the adjustment, the position of the magnetic head to be finely adjusted is recognized, the magnetic head adjustment amount of the magnetic head is calculated, and the initial position of the adjustment screw for the magnetic head is detected by the torque detection device. A method for adjusting the height of a magnetic head, characterized in that the magnetic head is finely adjusted by rotating the adjustment screw by the magnetic head adjustment amount using the driver from its initial position.