JPH01876A - video playback device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a video playback device.

[Conventional technology and its problems]

In a video playback device used in a VTR, two playback heads are arranged on a rotating drum and alternately trace the recording trunk of a video tape to obtain a continuous playback video signal. However, if foreign matter gets between the playback head and the video tape and sufficient playback output cannot be achieved, or if a good recording track cannot be formed during recording, the continuity of the playback video signal may be lost. It may happen. Conventional video playback devices have been unable to provide satisfactory playback images in such cases.

In recent years, disk-shaped recording media (so-called optical disks, magneto-optical disks, compact disks, etc.) that can record continuous images over a sufficient length have become available.
Such sudden or instantaneous playback failures can occur not only in video tapes but also in disk-shaped recording media. However, even in video playback devices using disk-shaped recording media, no means have been taken to correct such playback defects.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a video playback device in which even if a playback failure occurs in a plurality of playback heads, the playback image is not affected by the playback failure.

[Means for solving problems]

A video playback device according to the present invention has a plurality of playback means for playing back recorded signals of a video recording medium, and is a video playback device that obtains continuous video signals by switching and using the playback means, the playback means an error detecting means for detecting whether the reproduced signal is normal or not and outputting a reproduction error signal in the case of a reproduction failure; a memory means capable of storing a video signal for a predetermined period; When the signal is not output, the memory means is controlled to write mode to write a normal reproduction signal, and when the error detection means outputs the reproduction error signal, the memory means is controlled to read mode. The present invention is characterized in that it comprises a memory control means for reading out a stored signal, and an output means for selecting and outputting an output signal of the memory means when there is a reproduction failure.

[Effect]

The memory means memorizes and saves the normally reproduced signal, and in the event of a reproduction error, the signal stored in the memory means immediately before is substituted, so even if a reproduction error occurs in the reproduction means, the reproduced image will be , the reproduced image becomes almost the same as the reproduced image when no reproduction defect occurs, the continuity of the image can be maintained, and the viewer does not feel discomfort.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a block diagram of an embodiment in which the present invention is applied to a video tape playback device having a rotary head.

In Figure 1, 10.12 is a rotating drum (not shown)
a rotary head disposed on the radially opposite side of 14;
．． 16 are video R from rotating head 10°12 respectively.
This is a preamplifier that amplifies the F signal. 18 is an input terminal for a head switching signal formed from a signal indicating the rotational phase of the VTR rotating drum; 20 is an analog switch that switches according to the head switching signal; when the head switching signal is at "H" level, the rotation The trace output signal from the head 10 is selected, and when it is "L", the trace output signal from the rotary head 12 is selected.

22 is a video signal processing circuit that performs playback processing such as demodulation and time axis correction; 24 is a playback output detection circuit that monitors the playback signal from the rotary head 10° 12; and 26 is at least one
This is a video memory circuit with a storage capacity equivalent to one field, and includes an A/D converter for digital storage and a D/A converter for analog output. 28 is a head switching signal from the input terminal 18 and a reproduction output detection circuit 24;
This is a memory control circuit that controls the video memory circuit 26 according to the detection signal of. Reference numeral 30 designates an analog switch that switches according to a switching signal from the memory control circuit 28 to select either the output of the video signal processing circuit 22 or the output of the video memory circuit 26, and 32 represents a reproduction signal output terminal.

Next, the operation of the illustrated embodiment will be explained with reference to FIGS. 2 and 3. FIG. 2 shows a case where no reproduction signal is obtained from the rotary head 12, and FIG. 3 shows a case where no reproduction signal is obtained from the rotary head 10. In Figures 2 and 3 (
al indicates the head switching signal applied to the input terminal 18, (b) indicates the output of the analog switch 20, and (C
) shows the playback error signal output from the playback output detection circuit 24, and (d) shows the video output signal output by the memory control circuit 28.
The write (W) or read (R) control signal te of the memory circuit 26 is a switching signal from the memory control circuit 28 to the analog switch 30, and (f) is the output signal of the reproduction signal output terminal 32. In this example, -., (n-2).

Tracks (n-1) and n were being played normally, but after that, (n+1) and (n+3).

Assume that trunks (n+5) and (n+7) cannot provide sufficient playback output for some reason.

In the case of FIG. 2, when the head switching signal shown in FIG. A reproduction signal as shown in FIG. keep it in condition.

Therefore, the stored contents of the video memory circuit 26 are updated sequentially by the output of the video signal processing circuit 22.

When the period (n+1) arrives and no reproduction signal is obtained from the rotary head 12, the reproduction output detection circuit 24 outputs a reproduction error signal. Then, in response to the reproduction error signal, the memory control circuit 28 puts the video memory circuit 26 into the read mode (FIG. 2(d)).
6 to output a video signal of period n. At the same time, a switching signal ((e)) is output to switch the analog switch 30 to the output side of the video memory circuit 30.

Thereafter, during the periods (n+2), (n+4), and (n+6) during which normal playback output is obtained from the rotary disk 10, the video memory circuit 26 is put into a write operation state, a normal playback signal is written, and a playback error is detected. period (n+3
), (n+5), and (n+7), the signals written in the video memory circuit 26 in the previous period are read out. Operation switching of video memory circuit 26 and switch 3
By switching to 0, a reproduced video signal of a normal level is obtained at the output terminal 32 as shown in FIG. 2(f).

FIG. 3 shows a case in which no reproduced signal is obtained from the rotary head 10, but since it is basically the same as the case in FIG. 2, the explanation will be omitted.

The above embodiment is for playing back a video tape, but in principle, a video playback device has a plurality of playback heads (optical pickups in the case of optical playback) and switches and uses them on a field-by-field basis. The same is true in the case of , and the present invention can be applied to such video playback devices in general.

Further, in the above embodiment, the case where two reproducing heads are used selectively has been described, but it goes without saying that the present invention can be similarly applied to the case where more reproducing heads are selectively used.

〔Effect of the invention〕

As can be easily understood from the above explanation, according to the present invention, even if the reproduction from one of the plurality of reproduction means becomes defective, the continuity of the reproduced output signal can be maintained and the influence on the reproduced image can be reduced. It can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the configuration of an embodiment of the present invention, and FIGS. 2 and 3 are timing charts thereof. 10.12 One-turn head 14.16-Preamplifier 1
8--Head switching signal input terminal 26--Video memory circuit 28--Memory control circuit 32--Video output terminal

Claims (1)

[Claims] A video playback device that has a plurality of playback means for playing back signals recorded on a video recording medium, and that obtains continuous video signals by selectively using the playback means, wherein the playback device determines whether or not the playback signal by the playback means is normal. an error detection means for detecting a playback error and outputting a playback error signal in the case of a playback failure; a memory means capable of storing a video signal for a predetermined period; and a memory for detecting a playback error when the error detection means does not output the playback error signal. A memory that controls the means to a write mode to write a normal reproduction signal, and when the error detection means outputs the reproduction error signal, controls the memory means to a read mode to read the stored signal. 1. A video reproducing apparatus comprising: a control means; and an output means for selecting and outputting an output signal from the memory means in the event of a reproduction failure.