JPH0115946B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pause mechanism for a disk playback device, and in particular provides a pause mechanism suitable for a so-called digital audio disk playback device that records audio signals in digital format. .

In recent years, so-called video disks that record video signals at high density have been put into practical use, and digital audio disks that use this technology to digitize and record audio signals are about to be put into practical use. . In both video discs and digital audio discs, the tracks, which correspond to the sound grooves of conventional records, are minute, about 1 micron in width and pitch, due to high-density recording. Therefore,
If you want to pause the performance (pause) in the middle of the disc and then start playing from the same part again, there is a method that returns the pick-up by one track each time the disc rotates (kickback) and plays the same track repeatedly. It is common to use It is undesirable to cut off the tracking servo, which corresponds to "raising the needle" in conventional records, because it does not necessarily mean that the track will start from the same track when the record is played again.

When performing one kickback per rotation as described above, a still image can be obtained with a video disc, but with a digital audio disc, because of the discontinuous portion of each revolution, it is difficult to hear the sound. It is difficult to determine its contents. However, it is also true that there are cases where it is desired to know from which part of the music piece the music piece will start when playback starts again. There is a strong demand for accurate cueing, especially at broadcast stations and studios.
The main focus of the present invention is on the above points, and by making it possible to emit sound for a short time in a pause state, it is possible to aurally confirm the first sound when playback starts again, and moreover. , provides a pause mechanism that allows playback to be started from the position where the pause state has been entered.

The configuration of the present invention will be described with reference to one embodiment.

FIG. 1 illustrates a disc playback device to which an example of the pause mechanism of the present invention is applied. A frequency generator (hereinafter referred to as FG) 3 is coaxially attached to a motor 2 that rotationally drives a disc 1. It rotates while its speed is controlled by the servo circuit 4. A signal recorded on the disk 1 is read out without contact by an optical pickup 5, demodulated by a demodulator 6 into an analog signal (for example, an audio signal), and supplied to an output terminal 7.

The optical pickup 5 is accompanied by well-known servo circuits such as a tracking servo circuit 8 and a focus servo circuit (not shown), which operate to cause the light beam to follow the tracks on the disk.

In order to obtain a pause operation, normally, a pulse signal of one wave is injected into the output signal of the tracking servo circuit 8 every time the disk 1 rotates, causing the optical pickup 5 to kick back and keep the track always on the same track. Perform an operation that causes it to follow you. Therefore, the frequency of the FG3 signal is divided by the frequency divider 9, and the frequency is divided by 1 per rotation.
wave pulse signal, and this signal is used as pulse generator 1.
0 is triggered, converted into a signal with the required pulse width and voltage, and mixed with the output signal of the tracking servo circuit 8.

The pause mechanism of the disc playback apparatus of the present invention differs from conventional pause mechanisms in the operations of the frequency divider 9 and pulse generator 10. That is, the frequency divider 9 rotates the disk N times (N is an integer greater than or equal to 1,
A frequency divider that generates a pulse signal of one wave each time (fixed or variable) (modulo N frequency divider)
The pulse generator 10 is designed to generate N waves of pulse signals using one wave of the trigger pulse.

FIG. 2 compares the operation of the conventional pause mechanism and the pause mechanism of the present invention on the same time axis, where a and b are the outputs of the frequency divider 9 in the conventional pause mechanism. The output of the pulse generator 10 is shown, and c and d show the corresponding signal waveforms in the pause mechanism of the present invention.

The pulse signal a is outputted one wave at a time each rotation of the disk, and correspondingly, the pulse signal b is outputted one wave at a time each rotation of the disk. Therefore, the optical pickup is rapidly moved back one track each time the disk rotates, resulting in it remaining on one track.

On the other hand, in c, one wave of pulses is output every two rotations, and correspondingly, in d, two waves of pulse signals are output every two rotations. Therefore, the optical pickup is returned at high speed by two tracks every two revolutions of the disk, resulting in repeated reproduction of two consecutive tracks. Therefore, in the case of an audio signal, the time for continuous reproduction of the signal is twice as long as in the past, and it becomes easier to determine from the content of the music which part of the disc is being paused. If the above-mentioned integer N is set to be larger than 2, for example, if the track is returned at high speed by 4 tracks every 4 rotations, even longer continuous playback can be obtained.

As an example, if the rotation speed of the disk is 450 revolutions per minute, the continuous playback time in the conventional pause mechanism is 133 msec, and it is difficult to identify the content of the song. However, if the above N is set to 10 This allows continuous playback of 1.33 seconds, making it easy to identify the content of the song. Therefore, when the pause is released, it is possible to audibly confirm from which part of the music the playback will start.

Note that if the disc is recorded using the constant linear velocity (CLV) method, the time required for one revolution of the disc differs between the inner and outer parts, so this is corrected and the time required for one rotation of the disc differs between the inner and outer parts. However, it is preferable to obtain the same continuous playback time during the pause operation. As a means for this purpose, the value of N is changed stepwise between the inner and outer peripheries of the disk, for example, at the innermost periphery, it is returned by 10 tracks every 10 revolutions, and at the outermost periphery, it is returned every 5 revolutions. This is a method that returns five tracks at a time and changes the middle part stepwise. Specifically, it is sufficient to simultaneously change the frequency division ratio N of the frequency divider 9 and the number N of pulses generated by the pulse generator 10 in one trigger. It is easy to realize a similar circuit.

As described above, the pause mechanism of the disc playback device of the present invention allows the first part of the musical tone after the pause is released to be heard in advance by increasing the continuous playback time during the pause operation, and the pause mechanism allows the user to listen to the first part of the musical tone after the pause is released. It is fully applicable to applications requiring precise cueing, and has great practical effects.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the configuration of a pause mechanism of a disc playback device according to the present invention. FIG. 2 is a signal waveform diagram of each part comparing the operations of the conventional pause mechanism and the pause mechanism of the present invention on the same time axis. 4... Servo circuit, 6... Demodulator, 8... Tracking servo circuit, 9... Frequency divider, 10... Pulse generator.

Claims (1)

[Claims] 1. Means for continuously reproducing sections included in N consecutive tracks (N is an integer of 2 or more) forming a part of a spiral track formed on a disk during a pause, and a means for continuously reproducing sections included in N consecutive tracks forming a part of a spiral track formed on a disk; and a means for returning the pick-up to the top position of the N tracks at high speed each time the pick-up is completed, and returns the number N of tracks including the above-mentioned continuous playback section to the disk recorded at a constant linear velocity. Larger on the inner periphery;
A pause mechanism for a disc playback device that is characterized by changing its size so that it becomes smaller at the outer periphery.