JPH03192512A - Magnetic recording and reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a magnetic recording and reproducing device including a rotating head assembly, such as a video tape recorder, a digital audio tape recorder, and the like.

[Prior Art] FIG. 5 is a sectional view showing the main parts of a conventional magnetic recording/reproducing device, and FIG. 6 is a view taken along the line V--■ in FIG. 5.

In Figures 5 and 6, (1) is a fixed drum, (2)
is a bearing attached to this fixed drum, (3) is a rotating shaft supported by this bearing (2) and rotates, (4) is a pedestal fitted to one end of this rotating shaft (3), (5) is a rotating drum attached to this pedestal (4) using screws (6).

(7) is a magnetic head drive unit attached to the rotating drum (5) using screws (8), (9) is a lower transformer attached to the fixed drum (1), and (10) is a pedestal (4).
), (11) is a wiring board attached to the rotating drum (5), and (12) is a non-rotating contact for supplying control current to the magnetic head drive unit (7). .

(13) has a pedestal (
A rotating electrode (14) is provided in a part of 4), and (14) is a connection part that electrically connects this electrode (13) to the magnetic head drive part (7) via the connection part (15) and the wiring board (11). ,
(16) is a magnetic head attached to the magnetic head drive section (7), which includes a connecting section (17), a wiring board (11),
It is electrically connected to the upper transformer (10) via the connection part (15).

(18) is a recess provided in a part of the rotating drum (5) to house the magnetic head drive unit (7);
16) so that the position of the magnetic head drive unit (7) can be adjusted.
It is formed larger. (19) is a magnetic head (
16) is a position adjustment hole for position adjustment, and (20) is a magnetic tape that comes into sliding contact with the magnetic head (16).

Figures 7, 8 and 9 show the magnetic drive unit (7) in more detail.
1) is a first yoke made of a magnetic material, (22) is a columnar first permanent magnet fixed to this first yoke (21), (
23) is a second yoke made of a magnetic material that has a convex portion (23b) on a part of its inner circumference and is attached to the first yoke (21); (20 is attached to this second yoke (23); A third yoke made of magnetic material is attached.

(25) is a columnar second permanent magnet fixed to the third yoke (24) with the same magnetic poles as those of the first permanent magnet (22) facing each other; (26) is this second permanent magnet (25); and the first permanent magnet (22), and is a pole piece made of a magnetic material and fixed to either one of them.

(27) is a plate spring made of a thin non-magnetic material, which is held between the first yoke (21) and the second yoke (23), and whose extending portion (27a) is connected to the first yoke (21). and a window (21a) provided in the second yoke (23)
,.

(23a) and protrudes outward, and a magnetic head (16) is attached to the tip thereof.

(28) is a plate spring made of a thin non-magnetic material, which is held between the second yoke (23) and the third yoke (24). (29) is a fixed member held by the leaf spring (27) and (2B), respectively, and (30) has an inner circumference of the first permanent magnet (22), the second permanent magnet (25), and the pole piece (26). A bobbin (31) is fixed to a fixing member (29) using an adhesive (32) at a position where there is a gap between the wire and the outer circumference of the bobbin (31). The coil has an annular gap (Gl) over the entire circumference between it and the convex portion (23b) of the second yoke (23).

Next, the operation of 1.1-formed structural acid will be explained with reference to FIG.

First, the first permanent magnet (22) is a pole piece (26),
A magnetic flux (DJ) is generated by a closed magnetic path created by the second yoke (23) and the first yoke (21).

Similarly, the second permanent magnet (25) is connected to the pole piece (26).
, the closed magnetic path created by the second yoke (23) and the third yoke (24) creates a 1-3 pi magnetic flux (magnetic flux fE in the opposite direction to Dl).
generate l.

The magnetic flux generated in this way (DJ and El both cross the annular gap (F), fG) in the same direction, and the coil (31) is connected to the first permanent magnet (22) and the second permanent magnet (25). The total magnetic flux of traverses.

In this state, when current is applied to the coil (31) from the contactor (12) through the electrode (13), the connection parts (15) and (14), the coil (31), the bobbin (30) and the magnetic head (1
6) move in a straight line parallel to 1-F.

This causes the magnetic head (16) to connect to the magnetic tape (20).
is displaced in the width direction, and traces magnetic recording traces with precision.

Figure 10 shows the hysteresis characteristics between the drive current and displacement of the magnetic head drive unit (7), and Figure 11 shows the magnetic properties when recording is performed by the magnetic head drive unit (7) having such hysteresis characteristics. It represents a recording track ('') on the tape (20).

As is clear from FIG. 1O and FIG. 11 above.

When only adjusting the magnetic head drive unit (7) at the initial stage, the reference position of the magnetic head (16) changes due to the hysteresis characteristics shown in Fig. 10, and when recording, the recording track (Tl) changes. They overlap as shown by (α).

[Problems to be Solved by the Invention] The conventional magnetic recording/reproducing device is configured as described above, and since there is hysteresis between the drive current and displacement,
When recording after performing special playback or normal playback, the magnetic head does not move to a fixed position and the magnetic head does not move 180°.
There is a difference in height between the two opposing magnetic heads, and as a result, the recording tracks overlap each other, making it impossible to obtain good recording tracks, leading to problems such as deterioration of image quality.

This invention was made to solve the above problems, and it is possible to adjust the height between head channels during recording, obtain good tracks, and improve image quality. The purpose of the present invention is to provide a magnetic recording/reproducing device that can perform the following functions.

[Means for Solving the Problems] The magnetic recording and reproducing device according to the present invention positions the magnetic head along the outer peripheral surfaces of the rotating drum and the fixed drum, before the entrance where the magnetic tape starts to be wound around the rotating drum. The present invention is characterized in that it is configured to include an optical position detector for detection and a means for feeding back the detection information to the magnetic head drive device to control the position of the magnetic head.

[Operation] According to the present invention, the position of the magnetic head is detected by an optical position detector, and the detected information is fed back to the magnetic head drive device, so that the height at which the magnetic head enters the magnetic tape is always determined. A good recording track can be obtained by keeping it constant.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described based on the drawings.

FIG. 1 is a schematic plan view of a magnetic recording and reproducing apparatus according to an embodiment of the present invention, and FIG. 2 is a side view thereof. In the figure, (33) is an optical position for detecting the position of the magnetic head (16). This optical position detector (33) detects the outer peripheral surfaces of the rotating drum (5) and fixed drum (1) just before the entrance where the magnetic tape (20) starts to be wound around the rotating drum (5). is located along.

As clearly shown in Fig. 3, the L light distribution position detector (33)
A light emitting part (33a) that emits light and a light receiver part (33a) that receives light.
33b), one light emitting section (33a) uses an LED, and the light receiver section (33b) consists of a position detection element.

Next, the operation of the above configuration will be explained with reference to FIG.

The optical position detector (33) is irradiated with light (L) from the LED of the light emitting part (33a), and when the magnetic head (18) does not pass, it is reflected at point T in FIG.
When the light beam 6) passes through, it is reflected at eight points in FIG. 3 and enters the light receiver section (33b) at each point.

The light incident on the light receiver section (33b) in this way is detected by the position detection element, and the output of the difference voltage is amplified by the sensor amplifier (33c). The information obtained here represents the height (X) between the magnetic head (16) and the lower end U.

During recording, a magnetic head (1) is attached to the magnetic tape (20).
The output from the optical position detector (33) at the height from the lower end U when 6) enters according to the standard is defined as the specified voltage, and this specified voltage and the output from the optical position detector, that is, the sensor amplifier (33c) The output voltage is subtracted by a subtracter (33d), the difference is taken, and the magnetic head (16) of the magnetic head drive unit (7) is moved via the driver (34) so that this difference disappears. By doing so, the magnetic head (16) is displaced to the standard position.

By performing such an operation in each magnetic head drive section (7), it is possible to eliminate the difference in level between channels during recording.

In the above embodiment, an LED was used as the light emitting part (33a) of the optical position detector (33), but the magnetic head (1
6) Even if a laser or the like is used as long as the position can be detected, the same effect as in the above embodiment can be obtained.

[Effects of the Invention] As described above, according to the present invention, the optical position for detecting the position of the magnetic head is located on the outer peripheral surface of the rotating drum and the fixed drum, before the entrance where the magnetic tape starts to be wound around the rotating drum. By providing a detector and feeding back the detected information to the magnetic head drive unit (6), it is possible to move the magnetic head to a fixed position and eliminate the level difference between each magnetic head, resulting in good recording. This has the effect that the track can be obtained and the image quality can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view of a magnetic recording/reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a side view of FIG. 1, and FIG.
γf1 on the In -III line of the optical position detector shown in the figure.
4 is a diagram explaining the path for feeding back information obtained from the optical position detector to the magnetic head drive device, and FIG. 5 is the main part of the magnetic recording RF4 generation device including the conventional magnetic head drive device. FIG. 6 is a sectional view taken along the line ■-V in FIG. 5, FIG. 7 is an enlarged plan view of the main part showing details of the magnetic head drive device, and FIG. ■－■
9 is a side view of FIG. 8, FIG. 10 is a diagram showing the hysteresis characteristic between the magnetic head drive current and displacement, and FIG. 11 is a diagram when recording is performed by the magnetic head drive device. FIG. (1)...Fixed drum, (5)...Rotating drum, (
7)...Magnetic head drive device, (I6)...Magnetic head, (20)...Magnetic tape, (33)...Optical position detector. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A magnetic head movable parallel to the central axis of a rotating drum, a magnetic head drive device housed in the rotating drum, and a fixed drum rotatably supporting the rotating drum via a bearing. In the magnetic recording/reproducing device, an optical position detector is disposed along the outer circumferential surface of both drums in front of an entrance where the magnetic tape starts to be wound around the rotating drum, and detects the position of the magnetic head; 1. A magnetic recording and reproducing device comprising means for feeding back information detected by a position detector to the magnetic head driving device.