JPS61166282A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a sharp picture quality even when the tape moving speed is changed by providing the 1st rotary head and the 2nd rotary head and changing the height of one rotary head in the 1st and 2nd rotary heads in response to the tape moving speed. CONSTITUTION:A servo circuit 5 detects the moving speed of a tape. An output of the servo circuit 5 is fed to a converting circuit 6. The converting circuit 6 generates an output signal to place a rotary head 3 to a proper height based on a conversion table in response to the speed information outputted from the servo circuit 5. The conversion table is obtained in advance by the tape moving speed and the distance between the rotary heads 2 and 3 and written on the converting circuit 6. An output of the converting circuit 6 is fed to a comparator circuit 7. The comparator circuit 7 compares the optimum height of the rotary head 3 outputted from the converting circuit 6 with the height of the present rotary head 3, the result is fed to a bimorph 9, which is displaced in response to the comparison output so that the height of the rotary head 3 is controlled to be an optimum position.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magnetic recording/reproducing device for recording, for example, a digital image signal on a magnetic tape using a rotating head, and in particular, it relates to a magnetic recording/reproducing device that records digital image signals on a magnetic tape using a rotating head, and in particular, it relates to a magnetic recording/reproducing device that records digital image signals on a magnetic tape using a rotating head. It is concerned with improving the reproduced image when the speed changes.

[Conventional technology]

Image data for one field is obliquely recorded on the magnetic tape by a rotating head. For example, during slow motion playback, the phase shift speed of the magnetic tape changes, so if you use the same rotating head as for normal playback, the rotating head will not accurately scan the recorded pattern and the magnetic tape will not be recorded. It is not possible to obtain complete information.

For analog VTRs, for example,
As shown in Japanese Patent No. 528, in order to compensate for the mismatch between the scanning trajectory of the rotary head and the video track, 1. In addition to the main head for recording and reproducing, an auxiliary head with a fixed height was provided, and the output signals of the main head and the auxiliary head were switched using a control signal.

[Problem that the invention seeks to solve]

However, if the speed ratio is not determined to be a predetermined value, the reproduced signal may be missing even if reproduction is performed using an auxiliary head having a fixed height. Furthermore, switching between the main head and the auxiliary head requires a complicated mechanism and control circuit.

Therefore, an object of the present invention is to provide a magnetic recording and reproducing apparatus that does not require complicated mechanisms or control circuits and can provide clear image quality even when the phase shift speed of the tape changes.

Means for Solving Problem C8] The present invention provides a magnetic recording/reproducing device including a first rotary head 2 and a second rotary head 3.
This magnetic recording and reproducing apparatus is characterized in that it includes means for varying the height of one of the rotary heads 2.3 in accordance with the tape phase shift speed.

[Effect]

The height of one of the first and second rotary heads is variable. When the tape phase shift speed changes, for example during slow motion playback, the height of one of the rotary heads changes to the optimum position in accordance with the tape phase shift speed. By changing the height in this way, the first and second rotary heads can obtain recorded information on the magnetic tape without missing it.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 2 shows the arrangement of the rotary head in one embodiment of the invention. The head cylinder, which rotates in the direction shown, is provided with four rotating heads 1.2, 3.4. The rotating head 1 is a recording head, the rotating head 2 is a reproducing head, the rotating head 3 is a monitoring head, and the rotating head 4 is an erasing head. The rotary head 3 operates as an auxiliary head for reproduction, for example, during slow motion redirection. The height of this rotary head 3 is variable.

If the phase shift speed of the tape changes, the slope of the trajectory that the rotary head scans over the magnetic tape changes. Therefore, the rotary head 2 alone cannot completely obtain the information recorded on the magnetic tape, for example, during slow motion reproduction. The rotating head 3 then operates as an auxiliary head. In other words, if the height of the rotary head 3 is controlled to the optimum height according to the phase shifter of the tape, the information of the part that cannot be traced by the rotary head 2 can be obtained by the rotary head 3 and recorded on the magnetic tape. Complete information can be obtained.

The rotary head 3 is controlled by a control circuit shown in FIG. 1 to have an optimal height depending on the phase shift speed of the tape.

In FIG. 1, 5 is a servo circuit. A servo circuit 5 detects the phase shift speed of the tape.

The output of the servo circuit 5 is supplied to a conversion circuit 6.

The conversion circuit 6 orders an output signal for positioning the rotary head 3 at an optimal height based on the speed information output from the servo circuit 5 based on a conversion table. This conversion table is determined in advance from the distance between the rotating head 2 and the rotary head 3 at a tape phase shift speed of 2, and is written in the conversion circuit 6.

The output of the conversion circuit 6 is supplied to a comparison circuit 7.

The rotary heel 3 is attached to one end of a bimorph 9 as an electro-mechanical conversion element. Bimorph 9 has
A strain gauge (not shown) is attached, and the height of the rotary head 3 is detected by this strain gauge. The output from the strain gauge is supplied to a comparator circuit 7 via a strain gauge amplifier 10.

In the comparison circuit 7, the rotary head 3 output from the conversion circuit 6
The optimum height of the rotary head 3 is compared with the current height of the rotary head 3. This comparison output is supplied to the bimorph 9 via the drive amplifier 8, and the bimorph 9 is displaced in accordance with the comparison output, so that the height of the rotating hand 3 is controlled to be at an optimal position.

FIG. 3 shows an example of a reproducing circuit that processes data obtained from the rotary heads 2 and 3.

In FIG. 3, signals recorded on magnetic tape 11 are supplied from rotary heads 2 and 3 to sync detection circuits 12 and 13. The outputs of the sink detection circuits 12 and 13 are supplied to address detection circuits 14 and 15. The outputs of address detection circuits 14 and 15 are supplied to a memory circuit 16 and also to a field store detection circuit 17.

The field store detection circuit 17 is the address detection circuit 1
From the address signals detected by 4 and 15, it is detected whether data for one field has been recorded in the memory circuit 16.

When the writing of data for one field is completed, the field store detection circuit 17 provides the memory control circuit 18 with information indicating that the data writing has been completed. The memory control circuit 18 generates successive clocks from the reference clock from the terminal 19.

The memory circuit 16 includes three field memories 16A, 1
It is composed of 6B and 16C. Among the outputs of the address detection circuits 14 and 15, data of the same field is stored in the field memory 16A.

They are stored in the same corresponding field memories in 16B and 16C. 3 field memories 16A, 16B
, 16C are controlled by the memory control circuit 18. 1
When the writing of data for one field is completed, a command is given from the memory control circuit 18 to the memory circuit 16, and the field memory 16A.

Among the field memories 16B and 16C, the field memory to which writing has been completed becomes a read state and is taken out from the output terminal 20.

Note that the recording head 1 may be used as the auxiliary head for reproduction.

In this embodiment, when the tape phase shift speed changes such as in slow motion, a monitor head or a playback head can be used as an auxiliary head, so there is no need to add a dedicated auxiliary head. However, the present invention may also be applied to a two-head rotating VTR in which a dedicated rotating head is added.

〔Effect of the invention〕

According to this invention, since the auxiliary head is set at the optimal height according to the phase shift speed of the tape, recording signals can always be obtained in the optimal state regardless of changes in the phase shift speed of the tape. can. Furthermore, since the optimal position for setting the height of the auxiliary head is determined in advance, there is no need to perform closed-loop control, and the control circuit does not become complicated.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the invention, FIG. 2 is a plan view showing the head arrangement in an embodiment of the invention, and FIG. 3 is a block diagram of an example of a reproduction circuit in an embodiment of the invention. It is. Explanation of main symbols in the drawings 1.2, 3.4: rotating head, 5: servo circuit, 6: conversion circuit, 9: bimorph.

Claims (1)

[Claims] In a magnetic recording and reproducing device comprising a first rotary head and a second rotary head, the height of one of the first and second rotary heads is shifted from the tape phase. A magnetic recording/reproducing device characterized by comprising means for varying the speed according to the speed.