JPH0216413Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head mounting angle inspection device that can easily and accurately inspect the mounting angle of a magnetic head relative to a reference surface of a magnetic head assembly.

An example of a 2-head helical scan VTR that requires high assembly accuracy, especially angular accuracy.
Regarding the cylinder assembly of the video head used in the video head, the azimuth accuracy of the video head's operating gap is limited to about ±10' for home VCRs in order to prevent the head output from decreasing due to azimuth loss. This is the actual situation.
This accuracy is closely related to the degree of deterioration in image quality when performing compatible playback between devices, and if this accuracy is not guaranteed, the image quality cannot be guaranteed when dubbing images between devices. It disappears. Especially in the case of image recording equipment used for broadcast VCRs,
Because high resolution is required, the recording frequency range is wide, and signals in higher frequency ranges must be recorded.Azimuth loss also increases accordingly, and compatibility between devices requires high quality even before dubbing editing. images must be guaranteed. Therefore, the azimuth accuracy of the magnetic head assembly is required to be even higher. For example, if a 7.5MHz high frequency signal is
When recording at 5.6 m/s and the recording track width is 175 μm, approximately ±
Requires azimuth accuracy of 1.5′.

Figure 1 shows the external appearance of a video head used in a helical scan type VTR.It has an operating gap 2 on the magnetic tape sliding surface 1, and a winding window 4 on the side surface 3 of the head chip (the winding is not shown). ] is attached to the base 5. Figure 2 shows a cylinder assembly in which this video head is attached to a rotating cylinder.The base 5 of the video head is fixed to the head base mounting surface 7 of the cylinder 6 with screws 8, and the magnetic tape of the video head slides. The operating gap 2 appearing on the surface 1 must be assembled at a predetermined angle (azimuth angle) with respect to the mounting reference surface 9 of the cylinder 6. In the case of mass-produced products such as home VCRs, this accuracy is determined by: 1. The perpendicularity of the gap 2 of the video head chip and the side surface 3 of the head chip, 2. The accuracy of adhesion of the video head core to the base 5, and 3. The mounting of the cylinder 6 on the head base. By controlling the parallelism of the surface 7 and the cylinder mounting reference surface 9, it is possible to maintain a tolerance of approximately ±10'. On the other hand, VTR for recording images for broadcasting
In this case, when attaching the head base 5 to the base attachment surface 7 of the cylinder 6, attachment adjustments are made, such as attaching a spacer to this intervening surface.

Regarding the conventional method of measuring the azimuth angle of such a cylinder assembly, the cylinder 6 is fixed to an XY table whose perpendicularity in the interlocking direction is guaranteed,
Adjust the mounting reference plane 9 of the cylinder 6 so that it is parallel to one direction of movement of the XY table, focus so that the gap 2 of the magnetic head can be observed in the field of view of the microscope, and The azimuth angle can be measured by moving the XY table in the moving direction and measuring the amount of deviation at both ends of the gap line with reference to the microscope visual field scale line. However, in this method, for example, when the track width is 175 μm and the amount of deviation at both ends of the gap line is 0.5 μm, the azimuth error is about 10', and azimuth error measurement of this order is the limit.

As described above, the present invention provides a magnetic head mounting angle inspection device that can easily detect minute angular errors that cannot be measured using conventional methods. Generally, it is relatively easy to process the squareness of an object with high precision by machining such as cutting. This ensures the linearity of the movement of the work table on which the workpiece is mounted, adjusting the perpendicularity of the two axes of movement, and then aligning the workpiece with a ridge line or, in the case of a magnetic head, a gapped bar. After adjusting the gap line so that it is parallel to one table movement direction, the table is moved in a direction perpendicular to this and the cutting wheel is used to cut the workpiece, making it possible to process workpieces with highly accurate squareness. This is because. For example, if the linearity of the table's motion is adjusted to 1 μm/100 mm and the perpendicularity to 1 μm/100 mm, the perpendicularity of the machine tool table's motion direction will be approximately 2″, and the workpiece
If a 25 mm long magnetic head bar is attached and cut with parallel adjustment of 1 μm/25 mm, the angular accuracy will be approximately 10", and processing can be performed with fairly high precision. Therefore, as shown in Figure 2. The azimuth accuracy of the magnetic head in the cylinder assembly is determined by the parallelism between the mounting reference surface 9 of the cylinder and the side surface 3 of the magnetic head chip when the perpendicularity accuracy of the gap 2 of the head chip and the side surface 3 of the chip is guaranteed as described above. This can be guaranteed by keeping it within certain tolerance limits.

The present invention has been devised in view of this point, and the light beam from the monochromatic light source is split into two by a beam splitter, and the first beam obtained after irradiating the side surface of the magnetic head chip and the second beam obtained after irradiating the reference mirror are split into two by a beam splitter. an interference optical system that forms an image on an eyepiece of a chip side image having a constant angular relationship with the head gap of the magnetic head chip and interference fringes with the reference mirror as a level by interference of two second light beams; A microscope lens barrel, a reference mirror adjusting means for adjusting a fixed angle of the reference mirror, and a plurality of spaced apart locations where the lens barrel can be moved parallel to a column mounted on a base and a focusing direction of the interference optical system. a plurality of parallel holding means coupled by a plurality of parallel holding means, a moving means for moving the lens barrel in the focusing direction, and a mounting reference surface of a cylinder assembly to which the magnetic head chip is attached, are held in a constant posture on the column. It is equipped with a holding means. The present invention will be explained below based on drawings showing an example of implementation. 3 and 4 show the entire device of the present invention, and FIG. 5 shows the measurement principle of the interference microscope used in the present invention. In FIG. 5, first, the cylinder 6 to which the magnetic head chip 10 is attached is mounted and fixed on the cylinder mounting base 26 via the mounting reference surface 9, and the side surface 3 of the chip is observed by interference using an optical system. Monochromatic light 11 passes through a collimator lens 12 to a beam splitter 13
One side irradiates the side surface 3 of the magnetic head chip, returns to the beam splitter 13, passes through the objective lens 14, and the eyepiece 15, and the other side irradiates the reference mirror 16, returns to the same objective lens 14,
It passes through the eyepiece lens 15. Due to the interference of these two light beams, interference fringes representing contour lines with the reference mirror 16 as a level are observed in the observation field together with the image of the magnetic head chip 10. Therefore, after adjusting the above-mentioned optical system using the cylinder assembly for calibration in which the parallelism between the mounting reference surface 9 of the cylinder 6 and the side surface 3 of the magnetic head chip is guaranteed, the cylinder assembly to be inspected is observed with the above-mentioned optical system, and the observation is performed. The degree of parallelism between the mounting reference surface 9 of the cylinder assembly and the side surface 3 of the magnetic head chip can be measured by the amount of movement of the interference fringes. When a sodium lamp is used as a monochromatic light source, the height difference between interference fringes is about 0.3 μm, and when the width of the magnetic head chip is 3 mm, it is possible to determine an angle of about 20 inches per fringe.

Even with this method of using interference fringes, which enables high-resolution angle determination, it is necessary to suppress the movement accuracy of the movement mechanism for focusing the microscope in order to construct an inspection device with guaranteed accuracy when used as an actual inspection device.

The present invention is a particularly improved focusing mechanism. In the inspection apparatus of the present invention shown in FIGS. 3 and 4, a collimator lens 12 and a beam splitter 1 are included in the interference optical system shown in FIG.
3. An interference objective lens device 17 consisting of a set of an objective lens 14 and a reference mirror 16 and an eyepiece lens 15 are attached to a lens barrel 19, and a column 22 attached to bases 20 and 20 and the mirror The cylinders 19 are connected vertically in parallel to each other by leaf springs 23 and 24 forming parallel springs. The movement of the lens barrel 19 for focusing is carried out by the base 2.
This is done by rotating the motor threaded wheel 25 attached to the lens barrel 19 and pushing up the lower end of the lens barrel 19. The distance between the pair of leaf springs 23 and 24 is sufficient, and the movement of the lens barrel 19 is an ideal parallel movement with respect to the column 22, which is suitable for high-resolution angle determination by the above-mentioned interference fringe measurement. Angular errors due to microscope focusing are not introduced.

Next, to explain the operation according to the actual measurement work procedure, first, the cylinder assembly 6' for calibration, in which the parallelism of the cylinder mounting reference surface 9 and the side surface of the magnetic head chip 10 is guaranteed, is mounted on the cylinder mounting pedestal 26. Then, the mounting reference surface 9 of the cylinder is brought into close contact with the reference surface of the mounting base 26. Next, by moving the lens barrel 19 up and down using the focusing wheel 25, the image of the side surface of the magnetic head chip 10 is adjusted to fit in the field of view of the microscope. In this state, the angle of the reference mirror 16 is adjusted using the reference mirror adjustment knob 27 so that the interference fringes appearing on the side surface of the magnetic head chip 10 within the field of view of the microscope are uniformly spread. Next, the cylinder assembly 6' of the object to be measured is mounted on the cylinder mounting base 26 so that the mounting reference surface 9 of the cylinder is in close contact with the reference surface of the mounting base 26. In this state, the lens barrel 19 is moved up and down using the focusing wheel 25 to adjust the focus so that the side surface of the magnetic head chip 10 to be measured is focused within the field of view of the microscope, and the interference fringes appearing on the side surface are observed. The interference fringes observed in this state represent the mounting angle error from the above-mentioned mounting orientation of the magnetic head chip of the calibration cylinder assembly as a reference, and the magnetic head mounting angle error can be detected with high precision in the interference fringe unit. Is possible.

The present invention can be implemented as described above, and in the above series of operations, the posture of the interference optical system, which serves as a reference for interference fringes, is tilted due to the movement of the lens barrel for focusing. With high precision,
Although highly reliable measurement is impossible, according to the present invention, the movement of this lens barrel is achieved by a parallel plate spring mechanism (parallel holding means) that allows for highly accurate parallel movement, and high-resolution angle determination using interference fringes. Together with this, we have realized a highly accurate and reliable magnetic head mounting angle measuring device.

As an example of the present invention, we have described the case where it is applied to the cylinder assembly of a video head, but by changing the shape of the reference pedestal attached to the column, it can be used to inspect the angular accuracy of various magnetic head assemblies to be inspected. Of course, this can be done.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the video head, Fig. 2 is a front view of the video head cylinder assembly, Fig. 3 is a front view of a magnetic head installation angle inspection device according to an embodiment of the present invention, and Fig. 4 is a side view of the same. FIG. 5 is a diagram showing the measurement principle of the interference microscope used in the present invention. 3...Head chip side, 6...Cylinder,
6'...Cylinder assembly, 9...Mounting reference surface, 1
0... Magnetic head chip, 15... Eyepiece,
17... Interference objective lens device, 19... Lens barrel, 2
0,21...base, 22...column, 23,24
... Leaf spring, 25 ... Wheel, 26 ... Cylinder mounting pedestal.

Claims (1)

[Scope of utility model registration request] A light beam from a monochromatic light source is split into two by a beam splitter, and the head gap of the magnetic head chip is divided by the interference of the first beam obtained after irradiating the side surface of the magnetic head chip and the second beam obtained after irradiating the reference mirror. an interference microscope barrel having a built-in interference optical system that forms an image on an eyepiece of a chip side image having a constant angular relationship with the reference mirror and interference fringes with the reference mirror as a level; and a reference mirror that adjusts the fixed angle of the reference mirror. an adjustment means, a plurality of parallel holding means that connect the lens barrel at a plurality of spaced apart locations such that the lens barrel can be moved in parallel to a column mounted on a base in the focusing direction of the interference optical system; A magnetic head mounting angle inspection comprising: a moving means for moving in the focusing direction; and a holding means for holding the mounting reference surface of the cylinder assembly to which the magnetic head chip is mounted in a constant posture on the column. Device.