JPH08161802A - Magnetic recording / reproducing device - Google Patents

Abstract

(57) [Summary] [Structure] The screw mounting part of the cylinder is configured to have a rigidity higher than that of the cylinder base near the cylinder mounting surface. [Effect] The cost of parts can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device of a cylinder for mounting a magnetic head of a home video tape recorder (hereinafter referred to as VTR).

[0002]

2. Description of the Related Art First, FIG. 2 shows a recording / reproducing state of a home VTR. In the cassette 5, there are reel 21 on the feeding side.
The magnetic tape 6 wound around the take-up reel 22 is stored. Magnetic tape 6 ejected from the feeding reel 21
Is a guide pin 7 arranged on the chassis base 30, a tension pin 8, a fixed guide 9, and a guide roller 1.
It is wound around a cylinder 4 having a magnetic head for recording / reproduction (not shown) through a tilt guide 11. Next, the tilt guide 12, the guide roller 13, the AC head 1
4, via the fixed guide 3, the capstan 1 is pressed by the pinch roller 15 to receive the driving force of the magnetic tape 6. Further, the magnetic tape 6 is wound around the take-up reel 22 by winding the pull-out pin 2. This traveling system is a well-known technique and its detailed description is omitted. FIG. 3 shows a plan view of the cylinder base 25 on which the cylinder 4 is placed. The cylinder 4 has 25b, 25c, 25 on the cylinder base 25.
It is screwed through the 3 holes of d. 25e,
Chassis base 30 through 3 holes of 25f and 25g
Screwed to.

The linearity of the track pattern recorded on the magnetic tape 6 is called track bending. In order to keep the track pattern within a predetermined track bending range, the guide roller 1 is used.
It is common to adjust the height of 0 and 13. This is because the accuracy of track bending is on the order of a few microns, and this order cannot be achieved by combining parts with ordinary processing technology. 4 is a cross section taken along line BB of FIG.
The partial cross section figure of the attachment part of the cylinder 4 of a prior art example is shown. The height of the guide rollers 10 and 13 is the lead 4a of the cylinder.
The lower end of the magnetic tape 6 is adjusted along the (guide portion at the lower end of the tape). The magnetic head is positioned with high accuracy with respect to the lead 4a, and the lead 4a is processed so as to have a linearity of several microns or less. Therefore, when the magnetic tape 6 runs along the lead 4, it is most stable. Recording / playback conditions can be obtained.

However, as shown in FIG. 5, when the flatness of the chassis base 30 is poor, the screwed cylinder base 25 may be deformed following the surface of the chassis base 30. Alternatively, the mounting surface 2 of the cylinder 4 of the cylinder base 25 due to poor accuracy of the cylinder base 25
When 5a deviates from the ideal plane, a strong fastening force is applied from the mounting screw 26 of the cylinder 4 in the direction of arrow A to the cylinder 4
May be deformed, and the lead 4a may deteriorate the linearity. Normally, the mounting screw 26 uses a M3 meter coarse screw, and the tightening torque is about 8 kg-cm. The fastening force in the direction of arrow A at this time reaches approximately 200 kg to 300 kg. The cylinder 4 is usually made of aluminum and the wall thickness near the screwed portion is about several mm, so that the cylinder 4 is easily deformed by this fastening force.

When the linearity of the lead 4a is deteriorated, the trace of the magnetic head on the magnetic tape 6 becomes non-linear and the track is bent, so that the specification for compatibility adjustment is not satisfied. That is, when a tape recorded by another recording / reproducing apparatus such as a soft tape is reproduced, a problem such as noise on a part of the screen may occur.

The following are means for dealing with the deterioration of the linearity of the lead 4a, but there are disadvantages in each case.

(1) The tightening torque of the mounting screw 26 is weakened.

A means for setting a tightening torque so that the cylinder 4 is tightened in an area where it is not deformed.

For example, if the current tightening torque of 8 kg-cm is reduced to 0.8 kg-cm, the cylinder 4 of the mounting screw 26 will be
The load applied to is 1/10. At this time, the deterioration of the linearity of the lead 4a is negligible. However, lowering the tightening torque means that the crest of the male screw does not sufficiently mesh with the trough of the female screw, so that the mounting screw 26 loosens when vibration is applied. If the screwing portion of the cylinder and the cylinder mounting surface of the cylinder base do not coincide with each other, the cylinder 4 is lifted when the mounting screw 26 is loosened, and a track bend occurs during recording and reproduction. Further, in some cases, the cylinder 4 may fall out.

(2) High accuracy of the cylinder 4 mounting surface of the cylinder base 25.

There is a means for improving the accuracy in order to suppress the deformation of the lead 4a of the cylinder 4 to several micrometers or less even if the flatness tolerances of the individual components are overlapped. However, in this case, it is necessary to perform machining because the accuracy cannot be improved by ordinary molding, which results in an increase in cost due to an increase in processing cost.

(3) Cylinder mounting with spring screw.

Since the above two problems cannot be solved, conventionally, the mounting screw is provided with the spring 27a as shown in FIG. Since the screw provided with the stopper is configured to apply the load of the compression spring to the cylinder 4 to fix it,
A constant load can be applied at all times, and the cylinder 4 is not deformed. However, the special screw 27 to which the spring 27a is attached is required, and the cost of parts is increased.

(4) A slit is added to the cylinder.

Further, as disclosed in JP-A-4-30361, there is a means for forming a slit in the cylinder 4 in order to prevent the deformation of the cylinder 4. However, forming a slit in a cylinder made of an aluminum material makes the processing method difficult and increases the processing cost.

[0016]

The above-mentioned conventional techniques result in an increase in component cost or a processing cost.

The object of the present invention is to prevent deformation of the cylinder 4 without being affected by the accuracy of the cylinder base 25 or the chassis base 30 near the mounting surface 25a on which the cylinder 4 is mounted.
It is to secure the linearity of the cylinder lead 4a without increasing the cost.

[0018]

In order to achieve the above object, the rigidity of the cylinder base 25 near the cylinder screwing portion is made smaller than the rigidity of the cylinder screwing portion.

[0019]

With the above means, if the plane of the cylinder mounting surface of the cylinder base and the cylinder screw stop portion do not coincide, the cylinder base is deformed so as to follow the cylinder when the screw is tightened, Can be prevented from being deformed. As a result, the magnetic tape can travel while being guided by the leads whose linearity is ensured.

[0020]

Embodiments of the magnetic recording / reproducing apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial cross-sectional view of the mounting portion of the cylinder 4 of the mechanism of one embodiment of the present invention. The amount of deformation of the cylinder base 25 when receiving the load when the screw is fastened in the direction of arrow A by the cylinder mounting screw 26 is
It is designed to be larger than the amount of deformation near the screwed part of. This can be obtained from the difference in structure such as material and wall thickness of the cylinder base 25 and the cylinder 4. In this embodiment, a portion 25h having a smaller wall thickness than other portions is provided near the mounting surface of the cylinder 4 of the cylinder base 25. Therefore, when the cylinder mounting surface 25a of the cylinder base 25 does not coincide with the flat surface of the screwed portion of the cylinder 4 due to poor accuracy of the cylinder base 25 or poor flatness of the chassis base 30, the wall thickness of the cylinder base 25 is reduced. The small portion 25h is deformed, and the cylinder 4 is not deformed.

The maximum deformation amount is about 0.5 mm. The weight of the cylinder 4 is about 400 g, and the impact load is 40 kg even if the set is dropped and a shock of 100 G is applied, for example. This value is an order of magnitude smaller than the tightening load of 200 kg to 300 kg received from the mounting screw 26, does not deform when dropped, and
It is easily possible to design the portion 25h having a small wall thickness that is deformed by the above amount when a load is applied from the.

In this embodiment, the portion 25h having a small wall thickness is set, but the wall thickness of the cylinder base 25 is made uniform,
Moreover, it is easy to design a shape that is deformed by the tightening load of the mounting screw 26.

[0024]

According to the present invention, if the cylinder mounting surface of the cylinder base and the flat surface of the screwing portion of the cylinder do not coincide with each other, the cylinder base is deformed. There is no need to use special screws with springs, and no additional machining is required. Therefore, the cost of component reduction can be reduced without deteriorating the running specifications of the magnetic tape.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a cylinder screw fastening portion showing an embodiment of the present invention.

FIG. 2 is a plan view of a magnetic recording / reproducing device.

FIG. 3 is a plan view of a cylinder base.

FIG. 4 is a sectional view taken along the line BB of FIG.

FIG. 5 is a partial cross-sectional view of a conventional example.

FIG. 6 is a partial cross-sectional view of a conventional example.

[Explanation of symbols]

4 ... Cylinder, 6 ... Magnetic tape, 25 ... Cylinder base, 26 ... Cylinder mounting screw, 27 ... Spring-loaded screw.

Claims (2)

[Claims] 1. A magnetic recording / reproducing apparatus for pulling out a magnetic tape from a cassette and winding the magnetic tape around a cylinder equipped with a magnetic head for magnetic recording / reproducing. The rigidity of the mounting portion of the screw of the cylinder for mounting the cylinder on the cylinder base is larger than the rigidity near the cylinder mounting surface of the cylinder base so that it is not changed by screwing to the base. Recording / playback device. 2. The magnetic recording / reproducing apparatus according to claim 1, further comprising a portion near the cylinder mounting surface of the cylinder base having a thickness smaller than that of a peripheral portion.