JPS60119658A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain the recording and reproducing state with high performance by forming the outer circumferential face of a rotary drum so as to be prolonged to a position close to the fixed drum in excess of a head mounting reference face thereby decreasing the gap between the rotary drum and the fixed drum and stabilizing the running of a magnetic tape. CONSTITUTION:The outer circumferential face of the rotary drum 12 is formed downward further in excess of the head mounting reference face 8, that is, so as to be prolonged to a position close to the fixed drum. Thus, the outer circumferential ring 13 projected downward is formed to the outer circumferential ridge of the head mounting reference face 8 and the gap between the rotary drum and the fixed drum is narrowed by the height l3 of the outer circumferential ring 13. That is, when a moving head is used as a magnetic head, the gap between the rotary head and the fixed head is decreased without narrowing the moving range of the moving head. As a result, the deformation of a part of the magnetic tape positioned on the gap formed between both the drums is decreased and the stable running of the magnetic tape is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a rotary head type magnetic recording/reproducing device such as a VTR.

[Prior art] In general, a rotating drum with a magnetic head attached thereto is rotatably mounted on a fixed drum, and signals recorded on magnetic tapes wound diagonally on the outer peripheral surfaces of both drums are rotated together with the rotating drum. In a helical scan type VTR that uses a magnetic head to perform playback, the recorded video track and the trajectory of the magnetic head do not match during so-called special playback such as slow or stall playback, or during high-speed playback. Therefore, by supporting the magnetic head with a piezoelectric element such as a bimorph and displacing the magnetic head in a direction perpendicular to the scanning direction according to the magnitude of the electric signal applied to the bimorph, the video track and the magnetic head can be separated. Conventionally, a method has been used to match the trajectory and obtain good image quality without noise. This is called auto-tracking using a movable head.

Figure 1 shows such a general helical scan method V
FIG. 3 is a perspective view showing a drum portion of the TR.

In the figure, a magnetic tape 1 is wound obliquely on the outer peripheral surface of a fixed drum 2 and a rotating drum 3.

The rotating drum 3 has a magnetic head 4 mounted on a head mounting reference surface facing the fixed drum 2. Further, a gap 5 is formed between the rotating drum 3 and the fixed drum 2.

FIG. 2 is a sectional view of the drum portion shown in FIG. 1.

The magnetic head 4 is bonded to the tip of a piezoelectric element 6 such as a bimorph whose one end is fixed to the rotating drum 3 . Since the piezoelectric element 6 is displaced up and down when a voltage is applied thereto, the magnetic head 4 is also displaced in a direction perpendicular to the scanning direction thereof. In the case of a movable head in which the magnetic head 4 can be displaced up and down in this manner, the size U of the gap 5 between the rotating drum 3 and the fixed drum 2 is smaller than that in the case where a fixed head is used. , it is widened to accommodate the movement of the head. This will be explained in more detail using FIGS. 3 to 7.

Figure 3 shows A in Figure 1 when using a fixed head.
FIG. 3 is an enlarged view of a corresponding portion. In the figure, the magnetic head 4a is attached via a head base 7 to a head attachment reference surface 8 of a rotating drum 3 facing the fixed drum 2. The wire-wound coil 9 wound around the magnetic head 4a protrudes below the magnetic head 4a, but does not come into contact with the fixed drum 2 because a gap 5 is formed between the rotating drum 3 and the fixed drum 2. Conventionally, the end of the downward extension of the outer peripheral surface of the rotating drum 3 was defined at the portion where the head mounting reference surface 8 was located.

The dimension rL2 of the gap 5 needs to be large enough to allow the winding coil 9 to escape, but if it becomes too large, it will cause disturbances in the running of the magnetic tape. This will be explained using FIG. 4.

Figure 4 shows the gap 5 between the rotating drum 3 and the fixed drum 2.
FIG. 3 is a cross-sectional view showing a deformed state of the magnetic tape 1 passing above. As shown in the figure, if the gap 5 between the rotating drum 3 and the stationary drum 2 is too large, a deformed portion 10 will be formed in the portion of the magnetic tape 1 located above the gap 5. In an extreme case, this deformed recess 1o comes into contact with a corner of the rotating drum 3 or the fixed drum 2. Since the way of contact changes constantly and this causes disturbances in the running of the magnetic tape 1, the magnetic tape 1 and the magnetic head 4a during recording and playback are
It becomes difficult to obtain reproducibility of the contact state.

The larger the dimension of the gap 5 between the rotary drum 3 and the fixed drum 2, the larger the depression of the deformed recess 1o becomes, and as a result, the running of the magnetic tape 1 is more likely to be disturbed. Note that the dimension 2 of this gap 5 is, for example, VH8VTR.
In this case, it is set at about 0.4 to 0.451 m.

FIG. 5 is an enlarged view of a portion corresponding to portion A in FIG. 1, in which a movable head 4 is used as the magnetic head. FIG. 6 is a diagram showing the operation of the movable head 4 shown in FIG. 5. FIG. 7 is a sectional view of the portion shown in FIG. 5 viewed from the side.

In the case of an auto-tracking type VTR, as shown in FIG. 6, when a voltage is applied to the piezoelectric element 6, the movable head 4 is vertically displaced as shown by the broken line and the two-dot chain line in the figure. Therefore, the dimension of the gap 5 between the rotating drum 3 and the fixed drum 2 is increased by the amount of movement of the magnetic head 4 compared to the case of the fixed head shown in FIG. That is, the relationship is ft+>Qz. This will become clearer with reference to FIG. In other words, in this figure, the form when the fixed head is installed is shown by broken lines,
The solid line shows the configuration when the movable head 4 is attached. Look at the dimensions of the gap 5 when the movable head 4 is installed.
Looking at the dimensions of gap 5 when the fixed head is installed, Δ
Only Chu is getting bigger. Therefore, as is clear from what has been described above, in the case of an IC using a movable head, the deformation of the magnetic tape over the gap 5 is large, which tends to cause disturbances in the running of the magnetic tape. Therefore, since the recording condition of the tape has deteriorated considerably, when attempting to follow the recording track using the auto-tracking method, the amount of correction required to correct the tracking using the piezoelectric element becomes large and complicated. As a result, there has been a drawback that the cost for producing the movable head drive pattern is higher.

[Summary of the Invention] This invention has been made to eliminate the above-mentioned drawbacks, and its main purpose is to reduce the running of the magnetic tape by minimizing the gap between the rotating drum and the stationary drum. It is an object of the present invention to provide a magnetic recording and reproducing device that is stabilized and thereby can obtain a high-performance recording and reproducing state.

In summary, the present invention is a magnetic recording/reproducing device in which the outer circumferential surface of a rotating drum is formed so as to extend beyond a head mounting reference surface to a position closer to a fixed drum.

[Embodiments of the Invention] In this invention, the shape of the rotating drum is devised in order to prevent deformed recesses from occurring in the magnetic tape portion located above the gap between the rotating drum and the fixed drum. Before explaining, an example of a conventional rotating drum is shown in the eighth section.
As shown in the figure. FIG. 8 shows the conventional rotating drum 3 from below.
That is, it is a perspective view seen from the fixed drum side, and the magnetic head is removed for convenience. A head mounting opening 11 is formed in a head mounting reference surface 8 facing the fixed drum at a portion where a magnetic head is to be mounted. In the conventional rotary drum 3, as shown in the figure, the downward extension of the outer circumferential surface of the rotary drum 3 has its end defined at a portion where the head attachment reference surface 8 is located.

FIG. 9 is a perspective view of an example of a rotating drum used in the magnetic recording/reproducing apparatus according to the present invention, viewed from below, with the magnetic head removed for convenience. In the case of the illustrated rotating drum 12, its outer circumferential surface is formed to extend further downward beyond the head mounting M semi-surface 8, that is, to a position approaching the fixed drum. Therefore, an outer circumferential edge ring 13 that protrudes downward is formed on the outer circumferential edge of the head attachment reference surface 8 . Therefore, the gap between the rotating drum and the fixed drum should be narrowed by the height of the outer peripheral ring 13 (for example, 200 μm) compared to the conventional rotating drum 3 shown in FIG. I can do it. In other words, when a movable head is used as the magnetic head, the gap between the rotary head and the fixed head can be reduced without narrowing the movable range of the movable head. As a result, deformation of the magnetic tape portion located above the gap formed between both drums can be reduced, and the running of the magnetic tape can be stabilized.

This will be explained in more detail using FIGS. 10 to 12.

FIG. 10 is a sectional view of a drum section using the rotating drum shown in FIG. 9. The magnetic head 4 is a movable head that is supported by a piezoelectric element 6 and can be vertically displaced.

A gap 5 between the rotating drum 12 and the fixed drum 2
In this case, only the height of the outer peripheral ring 13 is smaller than that of the conventional one, making it a garden. FIG. 11 is an enlarged view of portion C in FIG. 10 viewed from the front. In this figure, the part indicated by a square is the height of the outer circumferential edge ring 13 that protrudes downward from the head mounting reference surface 8 of the rotating drum, and the gap between the rotating drum 12 and the fixed drum 2 is equal to this figure. The dimension u4 of 5 becomes smaller. That is, if the dimension of the gap between the rotating drum and the fixed drum when the outer peripheral ring 13 is not provided is L (see FIG. 5), then the gun becomes -ul-. FIG. 12 is a sectional view of the portion shown in FIG. 11 viewed from the side. The gap 5 between the rotating drum 12 and the stationary drum 2 is reduced to a gong 4. As a result, a stable tape running condition can be obtained.

In the embodiment described above, an auto-tracking VTR
Although the present invention has been described using an example, the present invention is not limited to this, and can be similarly applied to a magnetic recording/reproducing device having a fixed head instead of a movable head, and similar effects can be expected.

[Effects of the Invention] As described above, according to the present invention, the outer circumferential surface of the rotating drum is formed to extend beyond the head mounting reference surface to a position roughly approaching the fixed drum. The gap between the magnetic tape and the fixed drum can be reduced, and the running state of the magnetic tape can be stabilized. As a result, it is possible to improve image quality and performance.

In particular, as explained in the preferred embodiment, if the present invention is utilized in a magnetic recording/reproducing device having a movable head, the drive pattern of the movable head can be simplified;
Thereby, cost reduction can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a drum section of a helical Skillen type VTR. FIG. 2 is a sectional view of the drum section shown in FIG. 1. FIG. 3 is an enlarged view of a portion corresponding to portion A in FIG. 1 when a fixed head is used. FIG. 4 is a sectional view showing a deformed state of the tape passing over the gap between the rotating drum and the fixed drum. FIG. 5 is an enlarged view of a portion corresponding to portion A in FIG. 1, and a movable head is used as the magnetic head. FIG. 6 is a diagram showing the operation of the movable head shown in FIG. 5. FIG. 7 is a sectional view of the portion shown in FIG. 5 viewed from the side. FIG. 8 is a perspective view of a conventional rotating drum viewed from below, that is, from the stationary drum side, with the magnetic l\\rad removed for convenience. FIG. 9 is a perspective view of an example of a rotating drum used in the magnetic recording/reproducing apparatus according to the present invention, viewed from below, with the magnetic head removed for convenience. FIG. 10 is a sectional view of a drum section using the rotating drum shown in FIG. 9. FIG. 11 is an enlarged view of portion C in FIG. 10 viewed from the front. FIG. 12 is a cross-sectional view of the portion shown in FIG. 11, viewed from the side. In the figure, 1 is a magnetic tape, 2 is a fixed drum, 4 is a magnetic head, 5 is a piezoelectric element 111111.6, 8 is a head mounting reference surface, 12 is a rotating drum, and 13 is an outer peripheral ring. Agent Masuo Oiwa Fig. 3 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Procedural amendment (spontaneous) Mr. Commissioner of the Japan Patent Office 1, Indication of case Patent application 1983- 228015f2, Invention name Fatty recording and reproducing device 3, Relationship to the amended case Patent applicant address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name Name
(601) Mitsubishi Electric Co., Ltd. Representative Hitoshi Katayama 4, Agent 5, Detailed explanation of the invention column and Brief explanation of drawings column 6 of the specification subject to amendment, Contents of amendment (1) Description 5th page, 1st line [wA between 5 and position 4-
[to the part located above the gap 5 of the magnetic data 1] is corrected to [the part located above the gap 5 of the magnetic data 1]. (2) “No. 1” on page 9, lines 18 and 19 of the specification
FIG. 1 is an enlarged view of portion C in FIG. 10 viewed from the front. ” was corrected to “Figure 11 is an enlarged view of the outside of the outer periphery of portion C in Figure 10.” (3) Akira $1! ! [FIG. 12 is a sectional view of the portion shown in FIG. 11 viewed from the side. '' was corrected to ``Figure 12 is an enlarged view of the part corresponding to Figure 10 @C3lI.''. (4) Mei S, page 12, lines 10 to 12 [11th
The figure is an enlarged view of portion C in FIG. 10 viewed from the front. J [FIG. 11 is an enlarged view of the outside of the outer periphery of portion C in FIG. 10. ” was corrected. (5) [[ on page 12, line 12 and line 13 of the specification]
FIG. 12 is a cross-sectional view of the portion shown in FIG. 11, viewed from the side. 1. FIG. 12 is an enlarged view of a portion corresponding to portion C in FIG. 10. Corrected to J. that's all

Claims (2)

[Claims] (1) A rotary drum with a magnetic head attached to a head mounting reference surface facing the fixed drum is rotatably provided on the fixed drum, and a magnetic tape is recorded on a magnetic tape wound obliquely on the outer circumferential surface of both drums. In a magnetic recording and reproducing device that reproduces a signal from a magnetic head that rotates with a rotating drum, the outer circumferential surface of the rotating drum is formed to extend beyond the head mounting reference surface to a position closer to the fixed drum. A magnetic recording and reproducing device. (2) the magnetic head is supported by a piezoelectric element;
2. The magnetic recording and reproducing device according to claim 1, wherein the device is capable of being displaced in a direction perpendicular to the scanning direction of the piezoelectric device depending on the magnitude of an electric signal applied to the piezoelectric device.