JPH02100482A - Reproducing device - Google Patents

Abstract

PURPOSE:To stably reproduce a voice immediately after track feeding by replacing a reproduced signal with prescribed DC voltage when a reproducing head is moved on a track. CONSTITUTION:When a magnetic head 12 is fed by a head driving circuit 32 in the radial direction of a magnetic disk 10, a system control circuit 38 switching a switch 36 to the side of a (b) constant, namely, the side of a constant voltage circuit 34. Consequently, during the track feeding, constant voltage equivalent to DC center potential when a sound recorded signal is FM- demodulated is impressed to deemphasis circuits 18 and 24. Thus, the large fluctuation of the output of an FM demodulating circuit 16 to occur when the magnetic head 12 crosses a picture track, especially a high resolution picture track, or crosses an unrecorded track or an erased track is never transmitted to the deemphasis circuits 18 and 24, and the reproduction of the voice immediately after the track feeding can be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reproducing device, and more specifically to a reproducing device for a recording medium capable of recording information signals using a plurality of recording methods.

[Conventional technology]

As an example of the above-mentioned media, the still video floppy standards established by the Still Video Floppy Council include:
In addition to images, recording formats for audio signals are also specified.According to this, audio signals are compressed on the time axis, the frequency band is increased to the band of image signals, and the audio signals are recorded using the same recording system as image signals. There are possible ways. F for audio recording
The center frequency of M modulation is 6 for the 525-60 system.
MHz, 5 MHz for a 625-50 system. On the other hand, the sync chip frequency of the luminance signal is 6M)lz
, the white peak frequency is 7.5 MHz, which is approximately 6.7 MHz when converted to the center carrier frequency.

In such image and audio recording systems, standards have been proposed that allow recording with even higher resolution of luminance signals. In this case, the synchronized frequency is 7
．． 7 MHz, the white peak frequency is 9.7 MHz, which is approximately 8.7 M) I when converted to the center frequency.
Becomes z.

When reproducing a signal recorded in accordance with this standard, the center carrier frequency of the reproduced signal obtained from the reproducing head is 6 or 5 MHz in the case of an audio track, and approximately 6.7 MHz in the case of a low-band image track.

In the case of a high-band image track, it is approximately 8.7 MHz, so the DC center potential of the demodulated output of the FM demodulation circuit that demodulates the playback head output is different for the audio, low-band image, and high-band image. However, since this demodulated signal is transmitted by AC coupling inside the subsequent reproduction processing circuit, the DC potential difference is absorbed there,
Sufficient dynamic range is ensured.

[Problem to be solved by the invention]

However, in the above conventional example, since the DC potential of the FM demodulated signal changes greatly depending on the center frequency, a large amplitude sag occurs in the output video signal due to the AC coupling circuit included in the playback processing circuit immediately after track feeding. As a result, the reproduced screen has the disadvantage that unsightly symptoms such as vertical misalignment or white bands occur.

Further, even during track feeding, the DC level of the demodulated output of the FM demodulation circuit fluctuates so much that it exceeds the dynamic range of the circuit. As a result, the reproduced signal may become distorted.

Furthermore, when a desired audio track is immediately reproduced after the head crosses an unrecorded track or an erased track, the DC potential of the demodulated signal fluctuates greatly, causing a similar problem.

Therefore, an object of the present invention is to provide a playback device that solves these problems.

[Means to solve the problem]

A reproducing apparatus according to the present invention is an apparatus for reproducing a recorded signal of a recording medium on which information signals are recorded using a plurality of recording methods, and when moving a reproducing head on a track, the reproducing apparatus generates a reproduced signal at a predetermined oscillation frequency. The present invention is characterized in that it is provided with a replacement means for replacing the signal with the signal.

[Effect]

With the above means, a signal with a predetermined oscillation frequency is sent to the reproducing circuit system instead of a reproducing signal when moving a track, and the reproducing circuit system operates stably regardless of the recording state and recorded content of the track that it traverses. can be done. Therefore, the playback operation can be stabilized even immediately after track forwarding.

〔Example〕

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

FIG. 1 shows a block diagram of an embodiment of the present invention.
0 is a magnetic disk, 12 is a magnetic head, 14 is a preamplifier, 16 is an FM demodulation circuit, 18 is a de-emphasis circuit when the reproduction signal is an image, 20 is an image reproduction circuit, 22 is an image output terminal, and 24 is a reproduction signal. De-emphasis circuit for audio, 26 an audio playback circuit, 28 an audio output terminal, 32 a head drive circuit, 34 generates a DC voltage corresponding to the DC center potential when the playback signal from the audio track is FM demodulated. 36 is a constant voltage circuit 34
A switch 38 is a system control circuit that controls the switching of the switch 36 and the track feeding by the head drive circuit 32.

The signal reproduced from the magnetic disk 10 by the magnetic disk 12 is amplified by the preamplifier 14, and then sent to the FM demodulation circuit 1.
6. The signal demodulated by the FM demodulation circuit 16 is outputted to the output terminal 22 via the switch 36, the de-emphasis circuit 18 and the image reproduction circuit 20 in the case of an image signal, and is outputted to the output terminal 22 via the switch 36, the de-emphasis circuit 18 and the image reproduction circuit 20 in the case of an audio signal. The signal is output to the output terminal 28 via the emphasis circuit 24 and the audio reproduction circuit 26.

When the head drive circuit 32 moves the magnetic head 12 in the radial direction of the magnetic disk 10, that is, during track feeding, the system control circuit 38 switches the switch 36 to the b contact side, that is, to the constant voltage circuit 34 side. As a result, during track feeding, a constant voltage corresponding to the DC center potential when the audio recording signal is subjected to FMul modulation is applied to the de-emphasis circuit 18.24. 'If M1 Kiherad 12 crosses an image track, especially a high-resolution image track,
If an unrecorded track or an erased track is crossed, the output of the FM demodulation circuit 16 will vary greatly, but this variation will not be transmitted to the de-emphasis circuit 18.24.

When track feeding is completed, the system control circuit 38 switches the switch 36 to the a contact (output of the FM demodulation circuit 16) side. If the playback signal is an audio signal, switch 3
Since the DC potential is the same before and after switching switch 36,
Even with this switching, the DC potential of the output of the switch 36 does not fluctuate, which means that audio reproduction immediately after track forwarding can be performed stably.

FIG. 2 shows a block diagram of another embodiment of the present invention.

The same components as in FIG. 1 are given the same reference numerals. 40
is an oscillation circuit that oscillates at 5 or 6 MHz, which is the FM center carrier frequency in the case of an audio signal, and 42 is a preamplifier 14.
A switch 44 is a system control circuit that controls switching of the switch 42 and track feeding of the magnetic helad 12 by the head drive circuit 32.

In this embodiment, during normal playback, the switch 42 is
It is connected to the contact (preamplifier 14) side, and the reproduced image signal is obtained from the output terminal 22 and the reproduced audio signal is obtained from the output terminal 28. During track feeding, the system control circuit 44 switches the switch 42 to the b contact (oscillation circuit 40) side.

Then, the FM demodulation circuit 16 outputs a constant DC voltage corresponding to the output frequency of the oscillation circuit 40. Therefore, even if the magnetic head 12 crosses an image track, especially a high-resolution image track, or an unrecorded track or an erased track during track feeding, the output of the FMI adjustment circuit 16 is The FMyL modulation output becomes a constant DC voltage.

When the track feeding is completed, the system control circuit 44 switches the switch 42 to the a contact side. When the reproduced signal is an audio signal, the center frequency of the input signal to the FM demodulation circuit 160 is the same before and after switching the switch 44,
Therefore, the DC potential of the output of the FM demodulation circuit 16 also does not fluctuate. This allows stable audio playback immediately after track forwarding.

〔Effect of the invention〕

As can be easily understood from the above description, according to the present invention, audio playback immediately after track forwarding can be stabilized.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a block diagram of another embodiment of the present invention. 10--Magnetic disk 12--Magnetic head 14-
・・Preamplifier 16−・−FM demodulation circuit 34・・Constant voltage circuit 40−・−・Oscillation circuit

Claims (1)

[Claims] An apparatus for reproducing a recorded signal of a recording medium on which information signals are recorded using multiple types of recording methods, the apparatus having a replacement means for replacing the reproduced signal with a signal of a predetermined oscillation frequency when moving a reproducing head on a track. A playback device characterized in that: