JPH0421243B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a correction circuit for a magnetic recording/reproducing apparatus that improves image deterioration due to differences in characteristics of a plurality of video heads.

[Description of prior art]

In a magnetic recording/reproducing device, a magnetic recording tape is wound approximately half a turn around a rotating head and run at high speed, and two video heads alternately slide into contact with the magnetic recording tape wound around the rotating head to reproduce images. Differences in video head characteristics cause flicker on the playback screen. For this reason, conventional magnetic recording and reproducing apparatuses are provided with a correction circuit as shown in FIG. In FIG. 1, a first channel video head 1 and a second channel video head 2 are
The output of the video head selected by the switch 3 is suitably amplified by the head amplifier 4 and supplied to the correction circuit 5. This correction circuit 5 consists of an AGC circuit 6 and a phase correction circuit 7, and the AGC circuit 6 corrects the difference in the magnitude of the reproduced output due to the difference in the characteristics of the first and second channel video heads 1 and 2. death,
Furthermore, the phase shift caused by the AGC circuit 6 and the like is appropriately corrected by a phase correction circuit 7, and the resulting signal is provided to a subsequent video head signal processing circuit (not shown).

By the way, the correction by the AGC circuit 6 of the above-mentioned conventional correction circuit 5 is based on the magnitude of the FM carrier band component for recording the original video signal on the magnetic recording tape. , 2 was used to correct the magnitude of the output.

For this reason, the sideband band components for transmitting the original video signal are not sufficiently corrected for the differences in characteristics between the first and second channel video heads 1 and 2, and the edge portions of the playback screen are not sufficiently compensated for. This caused flicker and degraded image quality.

[Summary of the invention]

The present invention has been made to further improve the above-mentioned conventional technology, and is intended to further improve the FM output from the output of the video head.
The carrier band component and the sideband band component are each extracted, and the sizes of the extracted FM carrier band component and sideband band component are corrected and then combined to create a playback screen that is caused by differences in the characteristics of the video head. An object of the present invention is to provide a correction circuit for a magnetic recording/playback device that prevents flicker and improves image quality.

[Explanation of Examples]

Hereinafter, embodiments of the present invention will be described with reference to FIG. FIG. 2 is a block circuit diagram showing an embodiment of the correction circuit of the magnetic recording/reproducing apparatus of the present invention. In FIG. 2, the same members as in FIG. 1 are designated by the same reference numerals, and redundant explanations will be omitted.

In FIG. 2, the correction circuit 8 has first and second filters 9 and 10 which receive the output of the head amplifier 4 as input. The first filter 9 is a high-pass filter that passes high frequencies of about 3 MHz or higher, and extracts the FM carrier band component from the output of the video head. Moreover, the second filter 10 is approximately
It consists of a low-pass filter that passes low frequencies below 3MHz, and extracts sideband components from the output of the video head. Further, the output of the first filter 9 is corrected by the first AGC circuit 11, and the output of the first filter 9 is corrected by the first AGC circuit 11.
The FM carrier band components output from the two are assumed to have the same size. The output of the second filter 10 is
The sideband components output from the first and second channel video heads 1 and 2 are corrected by the AGC circuit 12 to have the same magnitude. Furthermore, the outputs of the first and second AGC circuits 11 and 12 are connected to the first and second phase correction circuits 13 and 12, respectively.
14, the phase is corrected appropriately, and the synthesis circuit 15
The FM carrier band component and the sideband band component are combined again by the FM carrier band component and provided to a subsequent video head signal processing circuit (not shown).

Therefore, even if the characteristics of the first and second channel video heads 1 and 2 are different, the combining circuit 15
From this, it is possible to obtain a video head signal in which both the FM carrier band component and the sideband band component are corrected to the same magnitude, and no flicker occurs on the playback screen. In particular, it does not cause flickering even at the edges of the playback screen.
Image quality can be improved.

〔Effect of the invention〕

As explained above, according to the correction circuit of the magnetic recording/playback device having the above configuration, the FM carrier band component and the sideband band component are corrected for each video head in response to the difference in characteristics of a plurality of video heads. Since the correction is made so that the signals have the same magnitude, the magnitudes of the video head signals do not differ due to differences in the characteristics of each video head, and flicker does not occur on the playback screen.
In particular, it has excellent effects such as preventing flickering at the edge portions of the reproduced screen and improving the quality of the reproduced image.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of a correction circuit of a conventional magnetic recording/reproducing apparatus, and FIG. 2 is a block circuit diagram showing an embodiment of the correction circuit of a magnetic recording/reproducing apparatus of the present invention. In the figure, 1...first channel video head, 2...second channel video head, 3...
...Switch, 5, 8...Correction circuit, 6...
AGC circuit, 9...first filter, 10...second filter, 11...first AGC circuit, 12
...Second AGC circuit, 15...Synthesizing circuit.

Claims (1)

[Claims] 1. In a magnetic recording/playback device in which an image is constructed by switching between a plurality of video heads, a first filter extracts an FM carrier band component from the output of the video head, and a second filter corrects the output of the first filter. a second AGC circuit for extracting a sideband component from the output of the video head; a second AGC circuit for correcting the output of the second filter;
1. A correction circuit for a magnetic recording/reproducing apparatus, comprising a synthesis circuit for synthesizing an output of an AGC circuit and an output of the first AGC circuit.