JPH01100725A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a reproducing image with high quality by driving and controlling an actuator only in the constant rotational phase of a rotary drum. CONSTITUTION:An actuator driving circuit 8 controlled by a control circuit 10 supplies a voltage only in the period of the specific rotational phase of a magnetic head 7 loaded fixedly on a drum 4, and the magnetic head 7 whose protrusive quantity is set in advance protrudes furthermore in the radial direction of the rotary drum 1 by the displacement of the actuator 5. Therefore, the head touch of the magnetic head 7 with a magnetic tape 6 can be maintained satisfactorily even at parts where the magnetic head 7 starts to abut with and completes the abutting with the magnetic tape 6, and it is possible to keep the envelope of reproducing output Eh reproduced by the magnetic head 7 constant extending over entire length of the recording track of the magnetic tape 6. In such a way, the image with high quality can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording and reproducing apparatus such as a video tape recorder that records and reproduces signals on a magnetic tape using a magnetic head mounted on a rotating drum.

BACKGROUND ART FIGS. 5 and 6 show an example of a rotating drum used in a conventional magnetic recording/reproducing device. FIG. 5 shows a conventional rotating drum 1.
1 is a perspective view of FIG. In FIG. 5, the magnetic tape 6 supplied from the supply reel passes through several tape guide posts and erasing heads (none of which are shown), and then passes through the inlet tape guide post 12 of the rotary drum 11 to the rotary drum. 11 at a predetermined angle, and comes into contact with an audio control head (not shown) through the output tape guide post 13, and is further held by a capstan and a pinch roller (both not shown) and transported at a constant speed. After that, it is configured to be wound onto a take-up reel (not shown). A side sectional view of the rotary drum 11 is shown in FIG.
4 and a motor 2 for rotationally driving the upper drum 14
, the motor 2 is fixed, the magnetic tape 6 is guided by the outer circumferential surface of the motor 2, and the magnetic tape 6 is guided to the rotating drum 1 by a lead portion 15 provided on a part of the outer circumferential surface.
1 is constituted by a fixed lower drum 16 that guides it relative to 1. The upper drum 14 is fixed to the rotating shaft 3 of the motor 2 so as to rotate integrally with the motor 2. A magnetic head 7 for recording signals on the magnetic tape 6 and reproducing signals recorded on the magnetic tape 6 is fixedly supported by a head base 17, and the head base 17 is a part of the upper drum 14. It is fixed using screws etc. In this case, in order to exchange signals between the magnetic tape 6 and the magnetic head 7, the magnetic head 7 is provided to protrude from the outer peripheral surface of the upper drum 14 so as to come into contact with the magnetic tape 6. ing.

Further, in order to electrically connect the magnetic head 7 and the signal processing circuit, the upper drum 14 is fixed to the upper drum 14.
A rotor side 18 of the rotary transformer that rotates integrally with the rotary transformer 4 and a stator side 19 of the rotary transformer that is fixed to the lower drum 16 are arranged to face each other.

Problem to be Solved by the Invention With the rotation of the rotary drum 11 and the start of running of the magnetic tape 6, the magnetic head 7 starts contacting the magnetic tape 6 near the lower end of the magnetic tape 6, and the magnetic head 7 starts contacting the magnetic tape 6 near the upper end. The contact with tape 6 is completed. However, since the tape tension of the magnetic tape 6 is lower near the upper and lower ends of the magnetic tape 6 compared to the center, it is difficult for the magnetic head 7 to come into contact with the magnetic tape 6, resulting in poor head touch. Therefore, when reproducing a signal recorded on the magnetic tape 6, the upper end of the magnetic tape 6,
It becomes difficult to contact the tape end side of the recording track at the bottom end.

In general, the head touch is particularly bad at the part where the magnetic head 7 starts contacting the magnetic tape 6. FIG. It shows the envelope, Rh
indicates the playback output level, as is clear from the figure.
The envelope of the reproduction output of the magnetic head 7 is the magnetic tape 6.
There has been a problem in that the output decreases significantly at the start of contact with the holder, resulting in deterioration of the reproduced image.

The present invention solves the above-mentioned problems, and provides a magnetic recording and reproducing device that improves the contact between the magnetic head and the magnetic tape and makes it possible to keep the reproduction output reproduced from the magnetic head constant. .

Means for Solving the Problems In order to solve the above problems, the present invention involves winding a magnetic tape over a predetermined angle around a rotating drum equipped with a magnetic head, and recording and reproducing signals on the magnetic tape using the magnetic head. A magnetic recording/reproducing device comprising: an actuator that movably supports the magnetic head in a radial direction of the rotating drum; an actuator drive circuit that drives the actuator; and a rotational phase detection means that detects a rotational phase of the rotating drum. and a control circuit that drives and controls the actuator only during a certain rotational phase of the rotating drum.

Operation With the above-described configuration, the magnetic recording/reproducing apparatus of the present invention can make the reproduction output reproduced from the magnetic head constant over the entire length of the recording track of the magnetic tape, and therefore can obtain a high-quality reproduced image.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 to 4. In these figures, the same parts as those explained in FIGS. 5 and 6 are denoted by the same reference numerals, and the explanation thereof will be omitted.

Fig. 1 is a side sectional view of the rotating drum of this embodiment, Fig. 2 fa
t and (b) are respectively an enlarged plan view and an enlarged side sectional view of the main parts near the magnetic head mounted on the rotating drum of the same embodiment, and FIG. 3 is a block diagram of the magnetic recording and reproducing apparatus of the present invention. be. In the rotating drum 1 shown in FIG.
One end of an actuator 5 is fixed to the upper drum 4 fixed to the upper drum 4, and the other end of the actuator 5 is used for recording signals on a magnetic tape 6 and reproducing signals recorded on the magnetic tape 6. A magnetic helad 7 is fixed by adhesive or other means. The magnetic head 7 is shown in FIG.
ag, (as shown in bl, the actuator 5 is provided in advance to protrude from the outer peripheral surface of the upper drum 4 by a protrusion amount δ1 so as to come into contact with the magnetic tape 6. The configuration is such that the direction of the displacement can be obtained in the radial direction of the rotating drum 1 by using a laminated piezoelectric element that can obtain displacement.

Therefore, by driving the actuator 5 by the actuator drive circuit 8 shown in FIG. 3, the magnetic hend door fixed and mounted on the actuator 5 can be freely moved in the radial direction of the rotating drum 1 as shown by the arrow A in FIG. It can be made to appear. Furthermore, even if the tape tension is low and the head contact between the magnetic head 7 and the magnetic tape 6 is poor, the configuration is such that good head contact can be achieved by protruding the magnetic head 7.

In FIG. 1, a rotational phase detection means 20 for detecting the rotational phase of the upper drum 4 is provided on the lower drum 16. The rotational phase detection means 20 is composed of, for example, a magnetically sensitive element, and magnetic poles 21 are provided at a plurality of specific phases on the end surface 4a of the upper drum 4 so as to face the rotational phase detection means 20. The configuration is such that the rotational phase of the upper drum 4 is detected. Alternatively, the rotational phase detecting means 20 is constituted by a light-emitting light-receiving element, and portions 21 with high light reflectance are provided at a plurality of specific phases on the end surface 4a of the upper drum 4, so that the light reflectance changes. The rotational phase of the upper drum 4 is detected by detecting the change in the amount of light caused by the change in the amount of light. Alternatively, the rotor (not shown) of the motor 2 that rotationally drives the upper drum 4 and the magnetic head 7 of the upper drum 4 are set in advance to have a predetermined phase, and the rotational position of the rotor of the motor 2 is detected. means (not shown) is also used as the rotational phase detection means 20, and the upper drum 4
In addition, in the block diagram of FIG. 3, the control circuit 10 operates the actuator drive circuit 8 in accordance with the output obtained by the rotational phase detection means 20.
The actuator 5 is driven and IM controlled, and the magnetic helad 7
This is to change the amount of protrusion.

The operation of the present invention will be explained using FIGS. 3 and 4. Figure 4! a+ is a waveform diagram of the reproduction output envelope of the conventional device, and (b) is the output of the rotational phase detection means 20.
The figure (C1 is the protrusion amount of the magnetic head 7, and the figure (d) is a waveform diagram of the reproduction output envelope of the apparatus of the present invention.
When the magnetic head 7 starts to run and comes into contact with the magnetic tape 6, in the conventional apparatus, the magnetic head 7 obtains a reproduction output Rh as shown in ta+ in FIG. After that, the playback output becomes Es and becomes stable, but the playback output decreases again at the portion where the magnetic head 7 finishes contacting the magnetic tape 6. In the apparatus of the present invention, the magnetic head 7 The phase of the upper drum 4 just before it starts contacting the magnetic tape 6 (A), the phase of the upper drum 4 at which the playback output envelope of the conventional device becomes Es and stabilizes (B), and the magnetic helad 7 is connected to the magnetic tape. The rotational phase detection means 20 detects the phase (1) of the upper drum 4 immediately before the magnetic head 7 finishes contacting the magnetic tape 6, and the phase (1) of the upper drum 4 immediately after the magnetic head 7 finishes contacting the magnetic tape 6. By detection, an output as shown in FIG. 4(b) is obtained. This output is detected by the control circuit IO as shown in the block diagram of FIG. The actuator drive circuit 8 is controlled so that the actuator drive circuit 8 operates. The actuator drive circuit 8 controlled by the control circuit 10 drives the actuator 5 to a magnetic head 7 fixedly mounted on the upper drum 4.
By supplying a voltage only during a specific rotational phase period and displacing the actuator 5, the magnetic head 7, which has been previously set to a protrusion amount δ1, further protrudes in the radial direction of the rotary drum 1.

That is, the magnetic head 7 protrudes from the outer peripheral surface of the upper drum 4 of the rotary drum 1 to a position 62, as shown by the dashed line in FIGS.

This protrusion amount δ2 is a value set in advance so that the reproduction output is constant, and the voltage applied to the actuator 5 to obtain this protrusion amount δ2 is also set in advance. It shows the change in the amount of protrusion of the head 7. Also, during the periods of the upper drum 40 phases (A) to (T) and phases (1) to (A), the control circuit 1
0 controls the actuator drive circuit 8,
Since the actuator drive circuit 8 does not supply voltage to the actuator 5, the displacement of the actuator 5 is restored and the amount of protrusion of the magnetic head 7 becomes δ1. In this way, by protruding the magnetic head 7 for only a certain period of time, the magnetic head 7 can prevent the magnetic tape 6 from coming into contact with the magnetic tape 6 even in the parts where the tape tension is low, such as the part where the magnetic head 7 starts contacting the magnetic tape 6 and the part where the contact ends. The head contact between the magnetic head 7 and the magnetic tape 6 becomes good, and the envelope of the reproduction output Rh reproduced from the magnetic head door can be made constant over the entire length of the recording track of the magnetic tape 6, as shown in FIG. 4 (dl). , high quality images can be obtained.

Effects of the Invention As described above, the present invention provides a magnetic recording and reproducing apparatus that winds a magnetic tape at a predetermined angle around a rotating drum equipped with a magnetic head, and uses the magnetic head to record and reproduce signals on the magnetic tape. an actuator that supports a head movably in the radial direction of the rotating drum; an actuator drive circuit that drives the actuator; a rotational phase detection means that detects a rotational phase of the rotating drum; Since it is equipped with a control circuit that drives and controls the actuator only during the phase period, the head touch between the magnetic head 7 and the magnetic tape 6 can be maintained well even in the portion where the tape tension is low. The reproduction output reproduced from the magnetic head can be made constant over the entire length of the recording track of the magnetic tape, and a high-quality reproduced image can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a rotating drum according to an embodiment of the present invention, and FIG. 3 is a block diagram of the magnetic recording and reproducing apparatus of the present invention, and FIG. 4 (al is a waveform diagram of the reproduction output envelope of the conventional apparatus, in the same figure) is a diagram showing the output of the rotational phase detection means. , the same figure (C1 is a diagram showing the change in the amount of protrusion of the magnetic head 7, the same figure (dl is a waveform diagram of the reproduction output envelope of the device of the present invention, and FIG. 5 is a diagram showing the rotary drum of the conventional magnetic recording and reproducing device) 6 is a side sectional view of the rotating drum. 1...Rotating drum, 5...Actuator, 7...Magnetic head, 8... ... Actuator drive circuit, 10 ... Control circuit, 20
...Rotational phase detection means. Name of agent: Patent attorney Toshio Nakao 1 name
Figure Knee "Same rotation Y"
Ram S--Actuator 7-(Ij Dari Ryo"z to Nt 7 R0-11 Hiro 4 was violated, Figure 4)

Claims (1)

[Claims] A magnetic recording and reproducing device that winds a magnetic tape over a predetermined angle around a rotating drum equipped with a magnetic head, and records and reproduces signals on the magnetic tape using the magnetic head, the magnetic head being oriented in the radial direction of the rotating drum. an actuator that is movably supported; an actuator drive circuit that drives the actuator; a rotational phase detection means that detects a rotational phase of the rotating drum; 1. A magnetic recording/reproducing device comprising: a control circuit for controlling the magnetic recording/reproducing device.