JPS6240664A - Data slicing circuit for disk reproducing device - Google Patents

Abstract

PURPOSE:To generate the correct digital data even in the track jumping-over condition by adding the correcting signal of the prescribed level to the reference slicing level in the track jumping-over condition of the pick-up. CONSTITUTION:When a track jumping-over is requested, a reference slicing level S outputted from a direct current component detecting circuit 17 is level- shifted. At such a time, a correcting signal C of a constant level is generated from a system controller 20, and by an adder circuit 19, the level S outputted from the circuit 17 and the signal C are added. The output signal of the circuit 19 comes to be the data slicing level and is supplied to a comparing circuit 15. For such a reason, the reference slicing level is level-shifted up to the reference slicing level at the time of usual reproduction. Consequently, even in the track jumping over condition, an RF signal can be sliced by the same reference slicing level as the usual reproducing condition at the time of the ON track, and therefore, the correct digital data can be generated.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a disc playback device such as an optical compact disc player, and in particular to data slicing for converting a signal read by a pickup into binary digital data. Regarding circuit improvement.

[Technical background of the invention and its problems] As is well known, in optical disc playback devices such as compact disc players and video disc players, signals read by an optical pickup are converted into binary digital data. In order to convert, data slicing is performed.

This data slicing is performed by comparing the level of a signal read by an optical pickup with a reference slice level and converting the signal into a binary signal of, for example, 0.1.

In this case, the important thing is to set the above reference slice level to
The goal is to control the occurrence rates of 0 and 1 to be approximately equal. For this reason, a feedback loop is formed to control the reference slice level so that the time integral value of the θ period of digital data obtained by data slicing is approximately equal to the time integral value of one period. is being carried out.

FIG. 3 shows a conventional data slicing means in an optical compact disc player. That is, numeral 11 in the figure is a disk, which is rotationally driven by a disk motor 12. At this time, disk l! The information signal recorded on is read via the optical pickup 13 and supplied to one input terminal of the comparison circuit 15 via the amplifier circuit 4.

This comparator circuit 15 performs data slicing by comparing the reference slice level S supplied to the other input terminal with the level of the signal (RF multiplied signal) output from the amplification circuit 14, and converts the digital data into This digital data is then outputted to a demodulation/reproduction circuit system (not shown) via the output terminal 1B.
It is used for playback operation.

At this time, the digital data output from the comparison circuit 15 is supplied to the DC component detection circuit 17.

This DC component detection circuit (7) controls the reference slice level S so that the time integral value between 0 and 1 period of the digital data is approximately equal to the time integral value over one period. Data is generated.

By the way, with the conventional data slicing means as described above, there is no problem in normal disc playback conditions, but for example, when performing a search operation to quickly search for a desired portion of the information signal recorded on the disc 11, To,
When the optical pickup 13 is moved at high speed in the radial direction of the disk 11, that is, when it skips tracks, the following problem occurs.

That is, as shown in FIG. 4, the RF multiplied signal level output from the amplifier circuit 14 is approximately constant during normal disk playback, and the reference slice level S output from the DC component detection circuit 17 is also correct. value. However, in the track skipping state, as shown in FIG. 4, the RF multiplied signal level fluctuates greatly, so the reference slice level S
is level-shifted as shown by the dotted line S' in the figure.

In this case, as shown in FIG. 5, the portion where the RF multiplied signal level is high is
This is the on-track portion.

On the other hand, in a compact disc player, disc 11
The rotation speed is controlled to be constant linear velocity (CLV). This control to keep the linear velocity constant is performed by controlling the rotational speed of the disk motor 12 based on digital data output from the comparison circuit 15.

In addition, when jumping over a truck, the optical pickup 1
When the disc 11 reaches the target position and starts reproduction, it is required that the rotational speed of the disc 11 reaches a speed corresponding to the reproduction of the target position as soon as possible.

From the above, when skipping tracks, the digital data obtained from the on-track portion of the optical pickup 13 is used for control to keep the linear velocity constant, and as the optical pickup 13 approaches the target position, the disc 11 It is necessary to bring the rotation speed of the target position closer to the speed corresponding to reproduction of the target position.

However, in the on-track portion of the optical pickup 13, the correct RF multiplied signal reference slice level is the level shown by S in FIG. 5, but as described above,
When skipping tracks, the standard slice level S is level-shifted to S゛, so accurate digital data cannot be obtained in the on-track state, and in the end the rotational speed of the disk U is adjusted to the correct speed corresponding to the reproduction of the target position. The problem is that it cannot be controlled so that it approaches .

Therefore, when the optical pickup 13 reaches the target position, accurate reproduction cannot be performed immediately.

Further, as a conventional data slicing means, there is also one as shown in FIG. That is, this is an RF multiplied signal as shown in FIG. 7(a) output from the amplifier circuit 14, and a signal with the DC component cut as shown in FIG. 7(b) via the bypass filter circuit 18. RF", and this signal RF" is compared in level with the ground level S in a comparator circuit 15.

However, in such a configuration, the signal RF- is level-shifted as a whole in the track skipping state, and the slice level S is constant, so accurate digital data cannot be generated when on-track. It is something.

Supplementally speaking, the slice level S' shown by the dotted line in FIG. 7(b) is the correct slice level in this case.

[Object of the Invention] The present invention has been made in consideration of the above circumstances, and an object thereof is to provide an extremely good data slicing circuit for a disc playback device that can generate accurate digital data even in a track skipping state. shall be.

[Summary of the Invention] That is, the data slice circuit of the disc playback device according to the present invention adds a correction signal of a predetermined level to the reference slice level in the track skipping state of the pickup to determine the reference slice level in the track skipping state. By performing a level shift, accurate digital data can be generated even when tracks are skipped.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, the same parts as in FIG. 3 are shown with the same symbols, and only the different parts will be explained here. That is, the output terminal of the DC component detection circuit 17 is connected to one input terminal of the adding circuit 19.

The other input terminal of this adder circuit 19 is supplied with a correction signal C output from a system controller 20. Further, the output terminal of the adder circuit 19 is connected to the other input terminal of the comparator circuit 15.

Here, the system controller 2o is composed of, for example, a microcomputer, etc., and controls various operations of the compact disc player, and generates a correction signal C at a certain level when track skipping is requested. It is something. The various control signals output from the system controller 2o are supplied to various control circuits (not shown) via the output terminal 21.

In a normal reproduction state, the amplifier circuit 14 outputs an RF multiplied signal as shown in FIG. The RF signal is sliced based on the reference slice level S output from the detection circuit 17, and digital data is generated.

Here, when track skipping is requested, the reference slice level S output from the DC component detection circuit 17 is first level-shifted as shown by the dotted line in FIG. At this time, the system controller 20 sends
) A correction signal C of a certain level is generated as shown in
The addition circuit 19 adds the reference slice level S output from the DC component detection circuit 17 and the correction signal C.

Then, the output signal of this adder circuit 19 becomes a data slice level and is supplied to the comparator circuit 15. Therefore, the reference slice level S' shown by the dotted line in FIG.
As shown in FIG. 2(a), the level is shifted to the standard slice level S for normal reproduction.

Therefore, according to the configuration of the above embodiment, even in a track skipping state, the RF signal can be sliced at the same reference slice level S as in the normal playback state during on-track, so that the optical pickup 13 is The digital data obtained in the on-track portion can be used for control to keep the linear velocity constant, and as the optical pickup 13 approaches the target position, the rotational speed of the disc ti is adjusted to a speed corresponding to reproduction of the target position. This is something that can be brought closer to .

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications without departing from the gist thereof.

[Effects of the Invention] Therefore, as detailed above, according to the present invention, it is possible to provide an extremely good data slicing circuit for a disc playback device that can generate accurate digital data even in a track skipping state. .

[Brief explanation of drawings]

1 and 2 are block configuration diagrams showing one embodiment of a data slice circuit of a disc playback device according to the present invention and waveform diagrams for explaining its operation, and FIGS. 3 to 5 are respectively conventional 6 and 7 are block diagrams showing other conventional data slicing means and waveform diagrams explaining their operations, respectively. It is a diagram. 11... Disc, 12... Disc motor, 13
...Optical pickup, 14...Amplification circuit, 15
... Comparison circuit, 16 ... Output terminal, 17 ... DC component detection circuit, 18 ... Bypass filter circuit, 19
... Addition circuit, 20 ... System controller, 2
1... Output terminal. Applicant's agent Patent attorney Takehiko Suzue 113 JJ

Claims (1)

[Claims] The information signal recorded on the disk is read through a pickup, and based on the signal read by the pickup, a reference slice level for converting the signal into a binary signal is generated, and the level of the signal and the reference slice are In a disc playback device, the disc playback device includes a slicing unit that generates digital data by comparing levels with a level, and a speed control unit that controls a rotational speed of the disc based on a signal read by the pickup. The disc is characterized by comprising a correction means for level-shifting the reference slice level in the track skipping state by adding a correction signal of a predetermined level to the reference slice level in the track skipping state of the pickup. Data slicing circuit of playback device.