JPS63293716A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a reproduced image of high quality by comparing a reproduced output reproduced from a magnetic head with a reference level and driving and controlling an actuator in accordance with the compared output. CONSTITUTION:A reproduced output Eh obtained from the magnetic head 7 is detected by a comparator 9 and compared with the output level Es of a reference signal outputted from a reference signal generator and the compared output (Es-Eh) is inputted to a control circuit 10. The control circuit 10 controls an actuator driving circuit 8 in accordance with the compared output to drive the actuator 5. When the output level Eh of the reproduced output is lower than the output level Es of said reference signal, voltage is impressed to the actuator 5 by the circuit 8, and when the actuator 8 is displayed, the head 7 previously set up to a projection value delta1 is furthermore projected in the diameter direction of a rotary drum 1. Consequently, the envelope of the reproduced output Eh reproduced from the head 7 can be fixed over the whole length of recording tracks on a magnetic tape and an image of 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.

2. Description of the Related Art FIGS. 7 and 8 show an example of a rotating drum used in a conventional magnetic recording/reproducing device. Figure 7 shows the conventional rotating drum 1
1 is a perspective view of FIG. In FIG. 7, 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, passes through the output tape guide post 13, contacts an audio control head (not shown), is further pinched by a capstan and a pinch roller, and is transferred at a constant speed. It is configured to be rolled up. A side sectional view of the rotating drum 11 is shown in FIG. In the figure, the rotating drum 11
The magnetic chip 16 has a scanning contact member (an upper drum 14 rotatably provided, a motor 2 for rotationally driving the upper drum 14, and a magnetic tape 6 on the outer peripheral surface of which the motor 2 is fixed). It is composed of a fixed lower drum 16 that guides the magnetic tape 6 relative to the rotating drum 11 by means of a lead portion 15 provided on a part of its outer peripheral surface.The upper drum 14 is connected to the motor 2. It is fixed to the rotating shaft 3 of the motor 2 so as to rotate integrally with the motor 2.A magnetic head 7 is used for recording signals on the magnetic tape 6 and reproducing signals recorded on the magnetic tape 6. , is firmly supported by a head base 17, and the head base 17 is fixed to a part of the upper drum 14 using screws or the like.In this case, there is no transmission or reception of signals between the magnetic tape 6 and the magnetic head 7. In order to perform A rotor side 18 of a rotary transformer fixed to the upper drum 14 and rotating integrally with the upper drum 14 and a stator side 19 of the rotary transformer fixed to the lower drum 16 are arranged to face each other. There is.

Problem to be Solved by the Invention With the rotation of the rotary drum 11 and the start of running of the magnetic tape 60, the magnetic head 7 starts contacting the magnetic tape 6 near the lower end of the magnetic tape 6, and contacts the magnetic tape 6 near the upper end. 6 and finish the contact. However, since the tape tension of the magnetic tape 6 is lower near the upper and lower ends of the magnetic tape 6 than in the center, the magnetic head 7 and the magnetic tape 6 tend to come into contact with each other, resulting in poor head touch. . Therefore, when reproducing a signal recorded on the magnetic tape 6, it is difficult for the upper and lower ends of the magnetic tape 6 to come into contact with the tape end side of the recording track. The head touch is particularly bad at the starting point. Figure 9 shows the envelope of the playback output when the signal recorded on the magnetic tape 6 is played back by the magnetic head 7, and Eh is the level of the playback output. As is clear from the figure, the envelope of the reproduction output of the magnetic head 7 has a problem in that the output decreases significantly at the beginning of contact with the magnetic tape 6, leading to 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. In a magnetic recording and reproducing device, an actuator that supports the magnetic head movably in a radial direction of the rotating drum, an actuator drive circuit that drives the actuator, and a comparison circuit that compares reproduction output reproduced from the magnetic head. and a control circuit that drives and controls an actuator so that the reproduction output reproduced from the magnetic head is constant based on the comparison output obtained by the comparison circuit.

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 6. In these figures, the same components as those explained in FIGS. 7 to 9 are denoted by the same reference numerals, and the explanation thereof will be omitted.

Figure 1 is a side sectional view of the rotating drum of this embodiment, and Figure 2 (a
) 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 l shown in Fig. 1, the motor 2
One end of an actuator 5 is fixed to the upper drum 4 fixed to the rotating shaft 3 of the motor 2 so as to rotate integrally with the motor 2, and the other end of the actuator 5 has a magnetic tape 6 for recording signals. A magnetic head 7 for reproducing signals recorded on the magnetic tape 6 is fixed by means of adhesive or the like. The magnetic head 7 is shown in FIG. 2(b).
As shown in FIG. 2, the upper drum 4 is provided in advance so as to protrude from the outer circumferential surface of the upper drum 4 by a protrusion amount δ1 so as to come into contact with the magnetic tape 6.

The actuator 5 is configured so that the direction of the displacement can be obtained in the radial direction of the rotary drum 1 using, for example, a laminated piezoelectric element that can obtain displacement by applying a voltage. Therefore, the actuator 5
is driven by the actuator drive circuit 8 shown in FIG.
It can be freely moved in and out in the radial direction shown by. 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 magnetic head 7
A good head touch can be achieved by protruding the head. In the block diagram of FIG. 3, a comparison circuit 9 is for comparing the reproduction output Eh reproduced by the magnetic head 7. Further, the control circuit 10 controls the reproduction output Eh reproduced from the magnetic head 7 to be constant based on the comparison output obtained by the comparison circuit 9.
This is for driving and controlling the actuator 5 to change the amount of protrusion of the magnetic head 7.

The operation of the present invention will be explained using FIGS. 3 and 4. FIG. 4 is a waveform diagram of the reproduction output envelope of the apparatus. When the magnetic head 7 starts contacting the magnetic tape 6 due to the rotation of the rotary drum 1 and the start of running of the magnetic tape 6 on which signals are recorded, the magnetic head 7 generates a reproduction output Eh as shown in FIG. is obtained. This reproduced output Eh is detected by a comparison circuit 9 incorporating a reference signal generator (not shown), and compared with the output level Es of the reference signal output from the reference signal generator, and the comparison output (Es -Eh) is input to the control circuit 10. The control circuit 10 controls the actuator drive circuit 8 according to the comparison output to drive the actuator 5. The output level Eh of the reproduction output is equal to the output level E of the reference signal.
s, the actuator drive circuit 8 applies a voltage to the actuator 5, and as the actuator 5 is displaced, the magnetic head 7, which has been set in advance to the protrusion amount δ1, further extends in the radial direction of the rotary drum 1. stand out. The amount of protrusion of the magnetic head 7 is controlled by the control circuit IO, and its maximum value is as shown in FIG.
As shown by the dashed line in (b), the distance is 62 from the outer peripheral surface of the upper drum 4 of the rotating drum 1. Once the level of the reproduced output Eh reaches the output level Es of the reference signal, the magnetic head 7 will continue to operate until the level of the reproduced output Rh becomes smaller than the output level ES of the reference signal.
The upper drum 4 is retracted in the radial direction by the actuator 5, and is constantly controlled by the control circuit 10 so as not to protrude the magnetic head 7 more than necessary. Since the magnetic head 7 freely protrudes in this way, the magnetic head 7 and the magnetic The head touch of the tape 6 is improved, and as shown in FIG. 6, the envelope of the reproduction output Rh reproduced from the magnetic head 7 can be made constant over the entire recording track length of the magnetic tape 6, making it possible to produce high-quality images. Obtainable.

The comparison circuit 9 has a built-in reference signal generator (not shown) and is configured to compare the reference signal generated by the reference signal generator with the reproduced output, as shown in FIG. , the reproduction output Eh may be sampled at a certain time interval Δt, and the previous and subsequent sample outputs Hp may be constantly compared. That is, at a certain time Tn (n=1.2.
If En+1<En, then the actuator drive circuit 8 drives the actuator 5 in response to the command from the control circuit 10. Then, the magnetic head 7 protrudes. And En+1 and E
If the levels of n are approximately equal, then En+1<En
The magnetic head 7 is retracted by the actuator 5 until . In this way, the output level of the reproduced output is held constant. Further, since the magnetic head 7 does not protrude beyond the upper drum 4 more than necessary, wear of the magnetic head 7 does not increase.

Furthermore, in the conventional magnetic recording/reproducing device, the magnetic head 7
When the magnetic head 7 is worn out, the amount of protrusion of the magnetic head 7 decreases,
There has been a problem that the head touch deteriorates and the reproduction output Eh decreases, but in the magnetic recording and reproducing apparatus of the present invention, even if the magnetic head 7 is worn out, the above-described operation allows the magnetic head 7 to always perform proper reproduction. The amount of protrusion is maintained to ensure the output level.

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 comparison circuit that compares reproduction outputs reproduced from the magnetic head; and a comparison obtained by the comparison circuit. The control circuit is equipped with a control circuit that drives and controls an actuator so that the reproduction output reproduced from the magnetic head is constant based on the output, so that the reproduction output reproduced from the magnetic head is controlled over the entire length of the recording track of the magnetic tape. It is possible to maintain a constant value and obtain high-quality reproduced images. Further, even if the magnetic head wears out, the above-described configuration provides an excellent effect in that the magnetic head can always maintain an appropriate reproduction output level.

[Brief explanation of drawings]

FIG. 1 is a side cross-sectional view of a rotating drum according to an embodiment of the present invention, and FIGS. 3 is a block diagram of the magnetic recording/reproducing device of the present invention, FIG. 4 is a waveform diagram of a reproduction output envelope, and FIG. 7 is a rotating drum of a conventional magnetic recording/reproducing device. 8 is a side sectional view of the rotating drum, and FIG. 9 is a waveform diagram of the playback output envelope of the device. 1... Rotating drum, 5... Actuator. , 7... Magnetic head, 8... Actuator drive circuit, 9... Comparison circuit, 10...
...Control circuit. Name of agent: Patent attorney Toshio Nakao Master craftsman - Rotating drum 5° - Actuator 7 - Magnetic head Fig. 1 Fig. 2 5-7474-"1-97 - Magnetic head Fig. 4 Fig. 5: jSG diagram Figure 8 Figure 9

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, wherein the magnetic head is movable in a radial direction of the rotating drum. an actuator supported by the magnetic head, an actuator drive circuit that drives the actuator, a comparison circuit that compares the reproduction output reproduced from the magnetic head, and a comparison output obtained by the comparison circuit to reproduce reproduction reproduction from the magnetic head. 1. A magnetic recording and reproducing device comprising: a control circuit that drives and controls an actuator to keep the output constant.