JPH0312861A - Still picture reproducing device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a noise bar by substituting a reproduction signal for a prescribed signal in a substitution means when the level of the reproduction signal is less than a prescribed level while a reproduction head shifts a track. CONSTITUTION:A control circuit 34 checks whether the output level of an amplifier is large than a threshold TH 2 by the output of a comparator 24 with the start of the shift of the head. When it is less than the threshold TH 2, namely, when the level of the reproduction signal is less than the prescribed value, a switch 26 feeds back the output of a 1H delay line 28 to the input of the 1H delay line 28, and the reproduction signal which is 1H before is used instead of the present reproduction signal at the same time as the compensation time of drop out. Then, the level of reproduction output is compared with the threshold TH 2 until the shift of the track terminates and the switch 26 is controlled. When the shift of the track terminates, the control circuit 34 changes the threshold TH 2 in the middle of the shift of the track to a threshold TH 1 for compensating drop out. Thus, the occurrence of the noise bar in the middle of the shift of the track can be controlled and prevented.

Description

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

[Prior Art] As a recording medium for still images, there is a small magnetic disk called a still video floppy.

In a still/video reproducing apparatus that reproduces still images recorded on such a magnetic disk, a signal reproduced from a recording medium is subjected to reproduction processing and outputted from a video output terminal as a video signal conforming to, for example, NTSC. While the playback head moves to different tracks on the magnetic disk,
No special processing is performed.

[Problems to be Solved by the Invention] However, while the playback head moves to another track, the output signal level of the playback head changes. For example, when the signal level decreases, the display on the monitor device connected to the video output terminal changes. Noise bars appear on the screen.

Therefore, it is an object of the present invention to provide a still image reproducing device in which such noise bars and the like do not occur.

[Means for Solving the Problems] A still image playback device according to the present invention includes a level detection means for detecting a playback signal level, an alternative means for substituting a predetermined signal for the playback signal, and, during track movement of the playback head, [Function] The above means causes the playback head to move to another track. Even if the reproduced signal level drops while the vehicle is moving, it is replaced by a predetermined signal, thereby preventing the generation of unpleasant noise bars.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic block diagram of an embodiment of the present invention. 10 is a video floppy which is a recording medium; 12 is a motor that rotates the video floppy 10; 14 is a playback head that electromagnetically converts the signal recorded on the video floppy; 16 is a connection between the playback head 14 and the video floppy 10;
18 is a reproduction amplifier, 20 is an FM demodulation circuit, 22 is a detector for detecting the reproduction signal level, and 24 is a head moving device for moving the output level of the detector 22 in the radial direction. 26 is a switch, 28 is an IH delay line, 30 is a reproduction processing circuit that reproduces the FM demodulated reproduction signal so that it can be displayed as an image on a monitor device, 32 is a monitor device,
34 is a control circuit that controls the entire illustrated apparatus; 36 is an operation key for inputting predetermined instructions to the control circuit 34;

The detector 22 and the comparison circuit 24 constitute a dropout detection circuit, and the switch 26 and the IH delay line constitute a dropout compensation circuit. From the control circuit 34 to the comparison circuit 24
The threshold value TH (TH1) applied to is the threshold value for determining whether or not to perform dropout compensation during normal playback, but in this embodiment, as described below, when the noise bar is It can also be used to prevent outbreaks.

FIG. 2 shows an operation flowchart of this embodiment.

The operation shown in FIG. 1 will be explained with reference to FIG. Control circuit 3
4 is a track movement command for moving the magnetic head 14 in the radial direction of the video floppy 10 using the operation key 3.
6 (Sl), and if there is a track movement command, the threshold value T H to be applied to the comparison circuit 24 is determined.
is switched to the threshold value TH2 at the time of track movement (S2
), then the head moving device 16 moves the magnetic head 14
starts moving (S3). At the start of head movement, the control circuit 34 uses the output of the comparison circuit 24 to adjust the output level of the amplifier (specifically, the output level of the detector 22) to the threshold value T.
Check whether it is larger than H2 (S4), and if it is larger than the threshold TH2, connect the switch 26 to the contact side (S6).
), when it is below the threshold TH2, it connects to the contact a side (S
5). That is, if the reproduced signal level is below a predetermined value,
The output of the IH delay line 28 is fed back to the input of the IH delay line 28 by the switch 26, and as in the case of dropout compensation,
The reproduction signal before IH is used instead of the current reproduction signal.

Then, until the track movement is completed (S7), the playback output level is compared with the threshold value TH2 and the switch 26 is controlled (S4, 5.6). When the track movement is completed, the control circuit 34 changes the threshold value T H2 during the track movement to the threshold value THI for dropout compensation (S8).

When the magnetic head 14 moves between tracks, the reproduction output level of the magnetic head 14 decreases between tracks. If the level drops to a level where synchronization cannot be achieved, noise bars will appear in the reproduced video. In this embodiment, a dropout compensation circuit is used to focus on the fact that the signal level drop during track movement is similar to the signal at the point where a dropout occurs, and an existing dropout compensation circuit is used to reduce the signal level. Prevent the above noise bars.

In this embodiment, when the reproduced signal level decreases, the signal of the previous line is substituted, but a signal of a specific level may be substituted.

[Effects of the Invention] As can be easily understood from the above description, according to the present invention, noise bars can be suppressed and prevented during track movement with a very simple configuration.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the configuration of an embodiment of the present invention, and FIG. 2 is a flowchart thereof. 10: Video floppy 12: Motor 14: Playback head 16: Head moving device 18: Playback amplifier 2
0: FM demodulation circuit 22: Detector 24: Comparison circuit 26
°Switch 28: IH delay line 30: Regeneration processing circuit 32: Monitor device 34, control circuit 36: Operation key

Claims (1)

[Claims] a level detection means for detecting a playback signal level; an alternative means for substituting a predetermined signal for the playback signal; 1. A still image reproducing device comprising: a control means for substituting a predetermined signal.