JPH04188982A - Magnetic recording reproducing method - Google Patents

Abstract

PURPOSE:To make SN ratio better and to improve recording density by adding a regenerative signal that the signal phases of two magnetic heads are same. CONSTITUTION:The output of a regenerative head amplifier 4 is added to the output of a regenerative head amplifier 5 in an adding circuit 7, being made a time delay in a delay circuit 6 by time difference Lg/v in the case of the regeneration of the same signal determined by the distance of the gaps between a magnetic head 2 and a magnetic head 3, Lg and the relative speed v by the magnetic heads 2, 3 and a magnetic tape 1. The signal processing at the time of the regeneration is performed with this adding signal added in the adding circuit 7. Thus, the characteristic of CN is made better and the recording density is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application to Industry The present invention relates to a magnetic recording and reproducing method in a video tape recorder (abbreviated as VTR) for recording and reproducing high-quality video signals and the like.

2. Description of the Related Art Conventionally, VH8 system and 8-video VTRs have been put into practical use as home VTRs and are widely used.

Problems to be Solved by the Invention In conventional home VTRs, video signals are frequency modulated (F
M) and recorded in the form of an analog signal. In such conventional home VTRs, due to the nonlinear input/output characteristics of the magnetic tape head system during recording and playback, the playback output is subject to large distortions, and as a result, the image quality of the playback video signal deteriorates. There are some problems.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention records and reproduces a video signal in the form of a digital signal on a magnetic tape head, and also miniaturizes the device and lengthens the recording and reproduction time. In order to perform high-density recording to enable high-density recording, the same track is reproduced by two heads, the time axes of the reproduction head amplifier outputs are matched by a delay circuit, and then added by an adder.

Effects of the Invention With the above-described configuration, the present invention is capable of suppressing random thermal noise caused by head impedance, which is a determining factor of noise output, and CN characteristics at high frequencies and short wavelengths when digital signals are recorded and reproduced on a magnetic tape head. This improves the recording density by 3 dB, greatly contributing to the improvement of recording density and increasing the margin of the equipment system.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of essential parts of an embodiment of the present invention.

FIG. 1 shows a block diagram when two magnetic heads 2 and 3 are scanning a magnetic tape 1 on which digital signals have already been recorded. First, the magnetic head 2 scans the track 1 in FIG. 2, and a reproduction signal is amplified by the reproduction head amplifier 4. Similarly to the magnetic head 2, the magnetic head 3 also scans the track 1 in FIG. 2, and the reproduction signal is amplified by the reproduction head amplifier 5.

In FIG. 1, the output of the reproducing head amplifier 4 is the time difference L when reproducing the same signal determined by the gap distance Lg between the magnetic heads 2 and 3 and the relative speed V between the magnetic heads 2 and 3 and the magnetic tape 1. The signal is delayed by g/'v in a delay circuit 6 and added to the output of the reproduction head amplifier 5 in an adder circuit 7. The signal added by the adder circuit 7 is converted to O (Low) by the digital signal decoding circuit 8.
) or 1 (High) level, and then input to the error correction circuit 9. Then, the reproduced digital signal whose error has been corrected by the error correction circuit 9 is converted by the reproduction side video signal processing circuit 10 into a format whose band and dynamic range satisfy the baseband video signal standards, and is output from the output terminal 11. The reproduced image is displayed on a CRT or projection TV.

In FIG. 1, the delay time L g / v of the delay circuit is:
In order to minimize the error rate of the reproduced digital signal in the error correction circuit 9, Lg/v±Δ is set, with Δ being a minute time.
is controlled by feedback.

This feedback control can also be performed by, for example, feedforward controlling the time axis fluctuation during reproduction, and in this case, the probability of error occurrence is further reduced.

In the present invention, the outputs of two magnetic heads are added, but the same effect of improving the SN ratio can be obtained even if the outputs of three or more magnetic heads are added in phase.

Effects of the Invention In the present invention, as described above, by adding the reproduced signals of the two magnetic heads whose signal phases are aligned, the signal component and the noise component are increased by 6 dB and 3 dB, respectively, and the S/N ratio is increased. can be improved by up to 3 dB. Therefore, the recording density can be doubled at most.
It becomes possible to downsize the device and extend playback time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a main part of an embodiment of the present invention, and FIG. 2 is an explanatory diagram for explaining scanning of two heads in FIG. 1. 1...Magnetic tape, 2...Magnetic head 1.3...Magnetic head 2.4, 5...
Playback head amplifier, 6...Delay circuit, 7...
...Addition circuit, 8...Decoding circuit, 9...
...Error correction circuit, 10...Reproduction side video signal processing circuit, 11...Output terminal. Name of agent: Patent attorney Haruaki Ogata and 2 others --- Kazuichi, →

Claims (9)

[Claims] (1) When the distance between the gap between the first and second magnetic heads is Lg and the relative speed of the first and second magnetic heads with respect to the magnetic recording medium increases in the playback mode, the playback mode is activated. A second magnetic head, which is also in the reproduction mode, scans the recording pattern scanned by the first magnetic head, with a delay of time Lg/v, and the first magnetic head amplifies the reproduction output of the first magnetic head. signal processing during reproduction using the sum signal added to the output of the second reproduction head amplifier which delays the output of the reproduction head amplifier by a time Lg/v in a delay circuit and amplifies the reproduction output of the second magnetic head; A magnetic recording and reproducing method characterized by performing the following. (2) The magnetic recording and reproducing method according to claim 1, wherein the first and second magnetic heads have the same structure and are made to have substantially the same reproduction output. (3) Claim (1) characterized in that the second magnetic head is mounted on the rotating cylinder so as to scan over the recording track scanned immediately before by the first magnetic head.
The described magnetic recording and reproducing method. (4) When the gap distance between the first and second magnetic heads is Lg, and the relative speed of the first and second magnetic heads with respect to the magnetic recording medium in the reproduction mode is v, then during recording, A signal is recorded by the first or second magnetic head, and during reproduction, the second magnetic head, which is also in the reproduction mode, scans the recording pattern scanned by the first magnetic head, which is in the reproduction mode, for a time Lg/v. scan with a delay of
The output of a first reproducing head amplifier that amplifies the reproducing output of the magnetic head is delayed by a time Lg/v in a delay circuit, and is added to the output of a second reproducing head amplifier that amplifies the reproducing output of the second magnetic head. A magnetic recording and reproducing method characterized in that signal processing at the time of reproduction is performed using the added signal. (5) The magnetic recording/reproducing method according to claim (4), wherein the first and second magnetic heads have the same structure and are made to have substantially the same reproduction output. (6) Claim (4) characterized in that the second magnetic head is mounted on the rotating cylinder so as to scan over the recording track scanned immediately before by the first magnetic head.
The described magnetic recording and reproducing method. (7) When the distance between the gap between the first and second magnetic heads is Lg, and the relative speed of the first and second magnetic heads with respect to the magnetic recording medium in the reproduction mode is v, then during recording: The first magnetic head erases data, the second magnetic head records a signal, and during playback, the first magnetic head scans the recorded pattern, which is also in the playback mode. A second magnetic head scans with a delay of time Lg/v, and a delay circuit delays the output of a first reproduction head amplifier that amplifies the reproduction output of the first magnetic head by a time Lg/v. A magnetic recording and reproducing method characterized in that signal processing during reproduction is performed using an added signal added to the output of a second reproducing head amplifier that amplifies the reproducing output of a magnetic head. (8) The magnetic recording/reproducing method according to claim (7), wherein the first and second magnetic heads have the same structure and are made to have substantially the same reproduction output. (9) Claim (7) characterized in that the second magnetic head is mounted on the rotating cylinder so as to scan over the recording track scanned immediately before by the first magnetic head.
The described magnetic recording and reproducing method.