JPH0213369B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a base for a magnetic head that facilitates adjustment of the azimuth angle of the magnetic head in a magnetic recording and reproducing apparatus that has a magnetic head and performs recording and reproduction.

First, we will discuss azimuth loss using Figure 1. In FIG. 1, if the gear line direction A of the recording pattern 1 and the gear line direction B of the reproduction head 2 are not parallel, deterioration of the reproduction output known as azimuth loss occurs, and the gear line direction A of the recording pattern 1 and the gear line direction B of the reproduction head 2 Let θ be the angle formed by the gear line direction B, the track width be W, and the recording wavelength be λ, then the azimuth loss will be La=20log ₁₀ |sin(πWθ/λ)/πWθ/λ|(dB). Therefore, the azimuth loss is determined by the angle θ between the gear line direction A of the recording pattern 1 and the gear line direction B of the magnetic reproducing head 2 and the track width W.
The larger the value is, and the shorter the recording wavelength λ is, the larger the value is. For example, in the case of self-recording and reproducing (reproducing with the same recording device) using a magnetic head that can perform both recording and reproduction, no azimuth loss occurs because the inclination of the magnetic recording head and the inclination of the reproducing head are the same. However, when the magnetic recording head and the magnetic reproducing head are separate, or when recording and reproducing are performed using different devices, azimuth loss occurs due to the difference in the inclination of each magnetic head during recording and reproducing. In order to prevent this, the inclinations of the magnetic heads must be made the same.

Next, an example of setting the azimuth angle in a two-head helical magnetic recording/reproducing apparatus, particularly a video tape recorder for general home use, will be described with reference to FIGS. 2 and 3. A, b, and c in FIG. 2 are a plan view, a front view, and a side view, respectively. In the figure, 3 is a magnetic head, 4 is a magnetic head base (hereinafter simply referred to as the head base), 5 is a cylinder mounting screw hole, B' is the gear line direction of the magnetic head 3, and C is parallel to the plane of the head base 4. The plane α is the angle between the direction B' and the plane C. In addition, in FIG. 3, a is a perspective view, and b is a perspective view, showing the state in which the magnetic head 3 and head base 4 are attached to the cylinder.
A partial cross-sectional view seen from the D direction in the figure, c is a partially enlarged portion seen from the E direction in Figure A. In the figure, 5' is a cylinder mounting screw, 6 is a cylinder, 7 is a cylinder reference plane, 8 is a magnetic head height adjustment screw, F is a plane parallel to the cylinder reference plane, α' is a direction B' and a plane F It is the angle formed by First, in FIG. 2, a magnetic head 3 is adhered to a head base 4 with an adhesive. At this time, magnetic head 3
In order to prevent azimuth errors caused by poor contact between the magnetic head 3 and the head base 4, the adhesive
The magnetic head 3 is installed at a predetermined position on the head base 4, and then adhesive is applied to the side surface of the magnetic head 3 to adhere it to the head base 4, without applying any adhesive to the interface where the head and head base 4 come into contact. Next, as shown in FIG. 3, the magnetic head 3 and head base 4 are attached to a cylinder 6 with cylinder attachment screws 5'. At this point, the accuracy of angle α' is about 10 minutes, and similar devices are manufactured so that α' is almost the same. As mentioned above, in video tape recorders for general home use, due to technological improvements in the manufacturing process, the azimuth angle is rarely set, and even when it is done, the height of the magnetic head is adjusted using the height adjustment screw 8. remains.

However, in cases where high image quality and compatibility are important, such as for business use, the above-mentioned accuracy of about 10 minutes is still insufficient, and even higher azimuth accuracy is required. For example, if we assume that the track width of the cassette tape is 180 μm, which is larger than the cassette tape of a home video tape recorder, and the recording wavelength is approximately 0.8 μm, then if the azimuth angle difference during recording and playback is 10 minutes, it will be approximately 7 dB. This shows the deterioration of the playback output. Furthermore, if recording and reproduction are performed sequentially using different devices, that is, if compatibility is considered three times, a maximum deterioration of 21 dB will occur. Since the azimuth accuracy has a large influence when the track width is wide or recording is performed using a short wavelength, a means for accurately adjusting the azimuth accuracy is essential. Therefore, it has been desired to develop an azimuth adjustment means.

The present invention makes it possible to easily improve the azimuth accuracy by significantly changing the shape of the conventional head base and providing adjustment means using screws.

Below is the fourth section regarding the shape of the head base mentioned above.
This will be explained using FIG. FIG. 4 shows the shape of the head base, and FIG. 5 shows the head base attached to the cylinder. Figure 4 a, b
are a front view and a side view, respectively. In the figure, 4' is the shape of the head base, and in particular, in the head base 4', 8 is the arm part, 9 is the neck part, and 10 is the shape of the head base.
is named the head part, and 11 is named the base part. 5A and 5B are a plan view and a sectional view, respectively. In the figure, reference numeral 12 denotes a height adjustment screw of the magnetic head that comes into contact with the lower surface of the head section 10, and 13 denotes an azimuth adjustment screw that comes into contact with the lower surface of the arm section 8. G is a contact point between the lower surface of the head portion 10 and the height adjustment screw 12, and H is a contact point between the lower surface of the arm portion 8 and the azimuth adjustment screw 13. Here, the head portion 10 is moved in the direction of the arrow I shown in FIG. 5b by means of a height adjustment screw 12, which is known in the art. Furthermore, the azimuth adjustment screw 13 causes the arm portion 8 to move in the direction of the arrow J shown in FIG. think). In this way, delicate adjustments can be made using the height adjustment screw 12 and azimuth adjustment screw 13. Further, in FIG. 6, reference numeral 14 is a spacer, and by providing the spacer 14 in this way and giving an inclination to the head base 4' in advance, adjustment in the direction opposite to the direction of arrow J in FIG. 5b is also possible. It becomes possible.

Next, the background of determining the shape of the head base 4' will be explained. One of the features of this head base is the neck 9.
This means that there is a The reason why the neck part 9 is provided is that the deformation of the head base 4' during the adjustment work performed using the height adjustment screw 12 and the azimuth adjustment screw 13 is stopped at the arm part 8 and the head part 10, and the base part 1
This is to prevent it from reaching 1. In FIG. 7, a indicates the width of the neck portion 9;
needs to be as narrow as possible for the reasons mentioned above.
If the neck portion 9 is not provided and the width a is sufficiently wide and the rigidity is large, the following disadvantages a and b will occur.

(a) The deformation of the head base 4' during the adjustment work extends to the base part 11, and the cylinder mounting screw 5'
This causes deterioration of the head base 4' and the cylinder 6, resulting in a decrease in the degree of close contact between the head base 4' and the cylinder 6, resulting in positional deviation.

(a) When the head base 4' is deformed during the azimuth adjustment work performed by the azimuth adjustment screw 13, the height that does not correspond to the azimuth change also changes significantly, which is unfavorable for the adjustment work.

Therefore, it is necessary to provide the neck portion 9 and to make the width a sufficiently narrow.

Here, focusing on (a) and using Figures 8 and 9,
An embodiment of the present invention will be described. K is the center point of the neck 9, L-L' is a straight line passing through the center point K and parallel to the gear depth, M is the perpendicular intersection of the line L-L' from the contact point H, and b is the contact point H and the center point. L- with K
The distance c in the L' direction is the thickness of the neck 9.
Now, when a force N is applied to the arm part by the azimuth adjustment screw 13 as shown in Fig. 8b, the change Δh in the center point K caused by the bending moment Mx at the intersection M is Δh=4Nb/Pac ³ (where P is Young rate). Here, if b=0, Δh=0, and the height change associated with the azimuth adjustment performed by the azimuth adjustment screw 13 is eliminated, and the adjustment work is significantly improved. FIG. 9 shows the head base shape of an embodiment of the present invention that satisfies this condition. In Figure 9,
The head base shape is such that the center point K of the neck portion 9 and the intersection of the perpendicular line drawn from the center point H to the straight line L-L' match, minimizing height changes due to azimuth adjustment performed using the azimuth adjustment screw 13. suppress. As a result of experiments with this head base shape, we were able to secure an azimuth adjustment resolution of 10 seconds, achieving extremely high azimuth accuracy.

In recent years, when high image quality and compatibility have become important in video tape recorders, higher precision azimuth is required, and the development of a means for adjusting it has been desired. The present invention has met these demands by achieving extremely high azimuth adjustment accuracy, and by considering the balance with height adjustment, the azimuth adjustment work has been made very easy. As described above, the present invention can prevent changes in the head height even if the azimuth is adjusted using the azimuth adjustment screw, and the azimuth adjustment and height adjustment can be adjusted independently. This has the excellent effect of being highly accurate and extremely easy to perform.

[Brief explanation of drawings]

The first is an explanatory diagram for explaining azimuth loss, the second
The figure shows a magnetic head base to which a conventional magnetic head is attached, and a, b, and c are respectively a plan view, a front view, and
The side view and Figure 3 show a state in which a conventional magnetic head base is attached to a cylinder, in which a is a perspective view, b is a partial sectional view seen from direction D in figure a, and c is a partial sectional view seen from direction E in figure a. FIG. 4a is a front view of the specially shaped magnetic head base, FIG. 4b is a side view of the same, and FIG. 5a is a plan view showing the magnetic head base in FIG. 4 attached to a cylinder. , Fig. 5b is the same sectional view, Fig. 6
7 is a front view of the head base, FIGS. 8 a and b are enlarged views of the same, and FIG. 9 is an explanatory diagram of the magnetic head base in one embodiment of the present invention. . 3...Magnetic head, 4'...Base for magnetic head,
8...Arm part, 9...Neck part, 10...Head part, 11
...Base part, 12...Height adjustment screw, 13...Azimuth adjustment screw, H...Point of contact with azimuth adjustment screw in arm part, K...Center point of neck part.

Claims (1)

[Claims] 1 A base part having a cylinder mounting screw hole, a part connected to this base part via a neck part whose width is smaller than the width of the base part, and a part on the lower surface that comes into contact with the height adjustment screw of the magnetic head, and a part at the tip thereof. It consists of a head portion having a magnetic head, and an arm portion connected to the head portion and having a portion that abuts the azimuth adjustment screw of the magnetic head on the lower surface, and is connected to a straight line passing through the center point of the neck portion and parallel to the gear depth direction. A base for a magnetic head configured such that an intersection point of a perpendicular line drawn from a point of contact with the azimuth adjustment screw on the arm portion coincides with a center point of the neck portion.