JPH0460915A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To make the height of a magnetic head at the time of bumping into a magnetic tape always constant and to obtain good recording tracks by detecting the position of the magnetic head with a photosensor and controlling the position of the magnetic head. CONSTITUTION:The device is provided with a 1st yoke 33 of a hollow cylindrical shape and a permanent magnet 34 fitted around the outer circumference of a cylindrcal coil bobbin 30, opposite to a cylindrical coil 31 to form the same gap over the whole circumference and also magnetized in the radial direction. A 2nd yoke 35 fixed on the outer circumference of this permanent magnet 34 and a 3rd yoke 36 fixed to the 2nd yoke 35, in which the 1st yoke 33 is fixed are provided, while the photosensor 37 is arranged in the 1st yoke 33, and the position of the magnetic head 16 is controlled with detecting information obtained by reflecting light generated by the photosensor 37 with a reflecting plate 38 provided in the cylindrical coil bobbin 30. By this method, the height between head channels is adjusted at the recording time while the good tracks is obtained thus improving the picture quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing device, and in particular to a magnetic recording and reproducing device equipped with a rotating head assembly such as a video tape recorder and a digital video tape recorder. This invention relates to improvement of the head drive unit.

[Conventional technology]

FIG. 5 is a cross-sectional view of a conventional magnetic recording/reproducing apparatus, not showing the main parts, and FIG. 6 is a view taken along the line Vl--Vl in FIG.

In Fig. 5 and Fig. 6, 1 is a fixed drum, 2 is a bearing attached to this fixed truck J, 3 is a rotating shaft Ii that is supported by this bearing 2 and rotates, and 4 is a rotating shaft of this rotating shaft 3. A pedestal 5 fitted at one end is a rotating drum attached to the pedestal 4 using screws 6. 7 is a magnetic head drive device that is attached to the bipedal rotating drum 5 using screws 8;
9 is the lower transformer attached to the two-legged fixed drum 1;
Reference numeral 10 indicates an upper lance attached to the base 4, 11 a wiring board attached to the rotating drum 5, and 12 a non-rotating contact for supplying control current to the magnetic head drive device 7.

13 is a pedestal 4 which is in sliding contact with the bipedal contact 12.
A rotating electrode 14 is connected to the magnetic head drive unit 7 from the electrode 13 via a contact part 15 and a wiring board 11, and a connection part 16 is attached to the magnetic head drive unit 7. It is a magnetic head with a connection part 17.
．． The wiring board 11 is electrically connected to the dowel-1 lance 10 via the connection portion 15 . 18 is a magnetic head drive device 7
This is a recess provided in a part of the rotating drum 5 for storing the magnetic head 16, and is larger than the magnetic head drive unit 7 so that the position of the magnetic head 16 can be adjusted. 19 is a position adjustment hole for position adjustment of the magnetic head 16, and 20 is a magnetic tape that comes into sliding contact with the magnetic head 16.

In addition, Figures 7, 8, and 9 are
The actuator 7 is shown in more detail, and in each figure, 21 is a first yoke made of a magnetic material, 22 is a columnar first permanent magnet fixed to the first yoke 21,
23 has a convex portion 23b on a part of the inner periphery.
The yoke 24 is a third yoke made of a magnetic material attached to the second yoke 23.

25 is a columnar second permanent magnet fixed to the third yoke 24 with the same magnetic poles as the first permanent magnet 22 facing each other; This is a pole piece made of a magnetic material that is located between the permanent magnets 22 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
The extending portion 27a projects outward through windows 21a to 23a provided in the first yoke 21 and the second yoke 23, and the magnetic head 16 is attached to the tip thereof. A plate spring 28 is made of a thin non-magnetic material and is held between the second yoke 23 and the third yoke 24.

Reference numeral 29 denotes a fixed member held by the plate 27.28, and 30 indicates a position where the inner circumference has a gap between the outer circumferences of the first permanent magnet 22, the second permanent magnet 25, and the pole piece 26. A bobbin 31 is fixed to the fixing member 29 using an adhesive 32, and 31 is a coil made of an electric wire having a covering material wound around the bobbin 30. It has an annular gap G over the entire circumference.

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

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

Similarly, the second permanent magnet 25 is connected to the pole piece 26, the second
A closed magnetic path formed by the yoke 23 and the third yoke 24 generates a magnetic flux in the opposite direction to the above magnetic flux.

Both the magnetic flux and the magnetic flux E generated in this way cross the annular gaps F and G in the same direction, and cause the coil 31 to pass through the first
The total magnetic flux of the permanent magnet 22 and the second permanent magnet 25 intersects.

In this state, when a current is passed through the coil 31 from the contactor 12 through the electrode 13 and the connecting portion 15.14, the coil 31, bobbin 30, and magnetic head 16 move linearly in parallel up and down as one body.

As a result, the magnetic head 16 is displaced in the width direction of the magnetic tape 20 and traces the magnetic recording trace with high accuracy.

FIG. 10 shows the hysteresis characteristics between the drive current and displacement of the magnetic head drive device 7, and FIG. 11 shows the magnetic tape 20-1 when recording is performed by the magnetic head drive section 7 having such hysteresis characteristics. The record of - represents 7.

-]- As is clear from Figs. 10 and 11, when only adjusting the magnetic/rad drive unit 7 at the initial stage,
Due to the hysteresis characteristics shown in Figure 10, the magnetic node]
The reference position of 6 changes, and the recording tracks T overlap as shown by d during recording.

[Problem to be solved by the invention]

Conventional magnetic recording and reproducing devices are configured as described above, and since there is hysteresis between the drive current and displacement,
Special playback 2 When recording after performing normal playback, the air bend at a fixed location does not move and the 180
There is a difference in height between the two opposing magnetic heads, and as a result, the recording trunks overlap each other, making it impossible to obtain a good recording trunk and causing problems such as deterioration of image quality.

This invention was made in order to solve the above-mentioned problems, and it is possible to adjust the height between the head channels during recording, and to obtain a good 1-2 rack, which improves the image quality. An object of the present invention is to provide a magnetic recording/reproducing device that can achieve the following.

[Means to solve the problem]

The magnetic recording/reproducing device according to the present invention includes a hollow cylindrical first yoke made of a magnetic material formed on the inner periphery of a cylindrical coil bobbin, and a cylindrical coil formed on the outer periphery of the cylindrical coil bobbin, facing the cylindrical coil and having the same gap around the entire circumference. a permanent magnet mounted to form a permanent magnet and magnetized in a radial direction;
A second yoke is fixed to the outer periphery of the permanent magnet, and a second yoke is fixed to the second yoke and has the first yoke fixed to the inside thereof.
and a third yoke that fixes the yoke of the yoke.
An optical sensor is disposed inside the hollow cylindrical first yoke, and a reflection plate is installed inside the cylindrical coil bobbin that moves together with a leaf spring having the magnetic hem 1 attached to the extension part. This device is characterized in that the light generated by the optical sensor is reflected and the position of the magnetic head is controlled based on the detected information.

[Effect]

According to this invention, the position of the magnetic head is detected by an optical sensor, and the position of the magnetic head is controlled based on the detected information, so that the height when the magnetic head plunges into the magnetic tape is always kept constant. A good recording trunk can be obtained.

〔Example] Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a cross-sectional view showing a magnetic head drive unit of a magnetic recording and reproducing device according to an embodiment of the present invention, and FIG. 2 is an operation of the drive system of the magnetic recording and reproducing device of the magnetic recording and reproducing device according to an embodiment of the present invention. Figure 3 is a diagram for explaining the operation of the optical sensor in Figure 1, and Figure 4 is a diagram for explaining the operation of controlling the magnetic head by the optical sensor in Figure 1. be.

In FIG. 1, 33 is a hollow cylindrical first cork made of a magnetic material formed on the inner circumference of the cylindrical coil bobbin 3 (), and 34 is a hollow cylindrical first cork formed on the outer circumference of the cylindrical coil bobbin 30, facing the cylindrical coil 31, and extending all around the cylindrical coil bobbin 30. Permanent magnets magnetized in the radial direction are attached to form the same gap, 35 is a second yoke fixed to the outer periphery of the permanent magnet 34, 36 is fixed to the second yoke 35 and its 1st inside
37 is a light sensor fixed to the third yoke 36 in the hollow part of the first yoke 33; 38 is a reflector that reflects the light generated by the light sensor 37; . The reflection plate 38 is arranged so as not to come into contact with the first yoke 33 during operation, and is arranged so as not to contact the first yoke 33 during operation.
0.

As shown in FIG. 3, the optical sensor 37 is composed of a light emitting section 37a that emits light and a light receiving section 37b that receives light.The light emitting section 37a uses a light generating element such as an LED or a semiconductor laser. However, the light receiving section 37b is composed of a position detection element.

In the above embodiment, the reflection plate 38 is connected to the cylindrical coil bobbin 3.
Although the reflector plate 38 is shown as being installed in FIG. 0, the reflector plate 38 may be provided on the extension portion by providing an extension portion on the plate wing 27 to which the magnetic head 16 is attached.

Next, the operation will be explained.

In FIG. 2, a permanent magnet 34, which has a hollow cylindrical shape and is magnetized in the radial direction, is connected to a first yoke 33 and a second yoke 3.
5. The third yoke 36 generates a magnetic flux I by a closed magnetic path. The magnetic flux 1-1 crosses the annular gap I, and the subsequent operation is the same as the conventional one. In this state, a contact is placed on the coil 31. When a current is passed from the coil 31 to the electrode 13 and the connecting portion 15.14, the coil 31, bobbin 30, and magnetic head 16 move vertically and in parallel in a straight line as a unit. It is displaced in the width direction, and the magnetic recording trace is accurately traced.

On the other hand, as shown in FIG. 3, when a current is applied to the coil 31, the cylindrical coil bobbin 30, whose upper and lower ends are supported by leaf springs 27, moves in the J direction. This direction coincides with the axial direction in which the drum rotates.

The light emitted from the light emitting section 37a of the optical sensor 37 is reflected by the reflecting plate 38 and enters the light receiving section 37b, and the incident light is detected by the position detection element of the light receiving section 37b.

The operation of controlling the magnetic head 16 by the optical sensor 37 will be described below with reference to FIG.

The voltage output of the light detected by the position detection element of the light receiving section 37b of the optical sensor 37 is amplified by the sensor amplifier 37C. Here, the reference height to which the magnetic head 16 is moved is defined as H1, and the voltage obtained by the optical sensor 37 at that position is defined as the specified voltage 40. For example, during recording, the height at which the magnetic head 16 plunges into the magnetic tape 20 according to the standard is set as the reference height, and the voltage at that time is set as the specified voltage 40. And the specified voltage 40 and the optical sensor 37,
That is, the subtracter 37d subtracts the voltage output from the sensor amplifier 37c, the difference is taken, and the magnetic head 16 of the magnetic head drive device 7 is displaced via the driver 39 so that the difference disappears.

By measuring the positional relationship between external parts such as a drum and the magnetic head 16 in advance, the absolute position of the cylindrical coil bobbin 30 can be determined.

In this way, in this embodiment, the position of the magnetic head 16 is detected by the optical sensor 37, and the absolute position of the cylindrical coil bobbin 30 is grasped based on the detected information, and the position of the magnetic head 16 is controlled. The height when the magnetic head plunges into the magnetic tape can be kept constant, and in each magnetic head drive device 7, there can be no difference in level between channels during recording. It is also possible to maintain the level difference positional relationship according to the standard.

Further, by using the position information of the cylindrical coil bobbin 30 to configure a closed-loop position servo, it is also possible to electrically increase the rigidity against disturbances.

Further, an observer or the like is configured for the magnetic head drive device, the speed of the coil bobbin is estimated from the drive current of the magnetic head drive device and the position information of the cylindrical coil bobbin, and electrical damping can also be performed by negative feedback of the estimated speed.

〔Effect of the invention〕

As described above, according to the present invention, a gap is formed by the magnetism between the hollow cylindrical first yoke and the hollow cylinder magnetized in the radial direction, and the gap is formed inside the hollow cylindrical first yoke. An optical sensor is placed on the cylindrical coil bobbin, which moves together with a leaf spring attached to the magnetic head on the extension part.A reflective plate is provided inside the cylindrical coil bobbin, and this reflective plate reflects the light generated by the optical sensor, and based on the detected information. Since the configuration is configured to control the position of the magnetic head, it is possible to move the magnetic head to a fixed position and eliminate the level difference between the magnetic spatulas 1 and ° of each channel. This has the effect that it is possible to maintain the data according to the standard, obtain a good recording track, and improve the image quality.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a magnetic head drive device of a magnetic recording and reproducing device according to an embodiment of the present invention, and FIG. 2 is an operation of the drive system of the magnetic head drive device of a magnetic recording and reproducing device according to an embodiment of the present invention. FIG. 3 is a diagram illustrating the operation of the optical sensor of the magnetic recording/reproducing apparatus according to an embodiment of the present invention, and FIG. 5 is a cross-sectional view showing the main parts of a conventional magnetic recording/reproducing device; FIG. 6 is a view taken along the line VT-VT in FIG. 5;
FIG. 7 is an enlarged plan view of the main parts showing details of a conventional magnetic head drive device, and FIG. 8 is a sectional view taken along the line v in FIG. 7.
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 of a conventional magnetic recording/reproducing device, and FIG. It is a diagram showing the track when I went there. 7 is a magnetic head drive device, 16 is a magnetic head, 27 is a plate blade, 30 is a cylindrical coil bobbin, 33 is a first yoke,
34 is a permanent magnet, 35 is a second yoke, 36 is a third yoke, 37 is an optical sensor, 37a is a light emitting section, 37b is a light receiving section, 37c is a sensor amplifier, 37d is a subtracter, 38 is a reflecting section, 39 For example, the driver 40 is a specified voltage. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A cylindrical coil bobbin having a cylindrical coil fixed to its outer periphery; a pair of leaf springs made of a non-magnetic material that supports the cylindrical coil bobbin through trampoline action; and an extension of one of the pair of leaf springs. In the magnetic recording and reproducing device, the magnetic head drive unit that drives the magnetic head includes a hollow cylindrical first yoke made of a magnetic material formed on the inner periphery of the cylindrical coil bobbin; , a permanent magnet attached to the outer periphery of the cylindrical coil bobbin so as to face the cylindrical coil so as to form the same gap around the entire circumference, and magnetized in the radial direction; and a permanent magnet fixed to the outer periphery of the permanent magnet. 2 yoke above 2nd
A third yoke is fixed to the yoke, and the first yoke is fixed inside the third yoke, and a plate spring formed inside the cylindrical coil and having the magnetic head attached to the extension part is integrated with the third yoke. a reflecting section that operates as a trampoline; a light emitting section; and a light receiving section, the light emitting section being fixed to a third yoke in the hollow interior of the first yoke, and the light emitted by the light emitting section being reflected by the reflecting section and receiving the light. 1. A magnetic recording and reproducing device comprising: an optical sensor that detects the position of the cylindrical coil bobbin by receiving light at the cylindrical coil bobbin.