JPH01303672A - Optical disc player data slicing 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 Field of the Invention The present invention relates to a data slicing device for an optical disc player.

BACKGROUND OF THE INVENTION In recent years, compact disc players, which are representative products in the consumer field of optical disc players, have become widely popular as their software has been improved and system products are also equipped as standard equipment. A compact disc is a high-density memory recorded in a CLV (constant linear velocity) format, and one of its characteristics is that it is highly accessible because it is a disc memory.

An example of the operation of the conventional data slicing device for an optical disc player described above will be described below with reference to the drawings.

FIG. 3 shows a block diagram of a conventional data slicing device for an optical disc player.

In FIG. 3, 1 is an optical disk, 2 is a spindle motor that rotates the disk at a predetermined speed, 3 is a pickup that reads the signal recorded on the disk, 4 is a head amplifier that linearly amplifies the output of the pickup, 6
is a comparator that converts the output of the head amplifier into a binary digital signal, 6 is a reference voltage generator that sets the reference level of the comparator, 7 is a rotation servo circuit that rotates the spindle motor at a predetermined speed, and 8 is a signal It is a processing circuit.

CL with the optical disc player configured as above.
The operation of the data slicing device when reproducing a disc recorded in the V format will be explained.

The amplitude of the output signal of the pickup 3 is usually very small as shown in FIG. 4 (-), and it is difficult to convert it directly into a digital signal. Therefore, the waveform is linearly amplified by the head amplifier 4 to have a large amplitude as shown in FIG. 4(b), and then inputted to the comparator 6 and
) is converted into a digital signal as shown in

The output of the comparator 5 is sent to the rotary servo circuit γ and at the same time to the signal processing circuit 8.

The reference voltage generator 6 may generate a fixed constant voltage, or may be configured to change following fluctuations in the DC component of the output of the head amplifier 4.

In the CLV state, the rotary servo circuit 7 compares the phases of a reference clock obtained by frequency-dividing the output clock of a crystal oscillator (not shown) and a synchronization signal output from a synchronization signal detector included in the normal signal processing circuit 8. 2 spindle motor drive signals are outputted equally, and in a rough servo state where the CLV state is not achieved, a specific cycle (for example, the shortest cycle or longest cycle) of the digital signal output from the comparator 6 is detected, and the cycle is set to a predetermined value. A drive signal for the spindle motor 2 is output so that the value becomes .

Problems that the invention aims to solve However, in the above configuration, FIG. 6(a).

As shown in (b), the output of pickup 3 and head amplifier 4
When noise is included in the output of the comparator 6, the output of the comparator 6 will have a whisker as shown in FIG. 6(C). Such a state mainly occurs when the driver controlling the focus and tracking of the pickup 3 consumes a large amount of current and is likely to turn off the power, such as during an access operation.

Also, when playing a disc recorded in CLV format, such as a compact disc, the rotation speed changes depending on the position of the pickup, so in order to speed up access, it is necessary to It is necessary to make the rotational speed follow the movement of the disk in the radial direction. To do this, a method is used to detect a specific cycle of the output of comparator 5, but if this signal has a whisker as shown in Figure 6(c), it may falsely detect that the rotation speed is high. As a result, the disk rotates at a slower speed than the normal speed, making it impossible to read data and speeding up access.

As a countermeasure for this, applying Schmitt to the comparator 6 will eliminate the whiskers as shown in Figure 6(d), but the precision of the time information on the edges of the output digital signal will be lost.
Jitter increases.

In view of the above-mentioned problems, the present invention provides a data slicing device for an optical disc player that stably follows the rotational speed during access and suppresses jitter during normal playback.

Means for Solving the Problems In order to solve the above-mentioned problems, the data slicing device for an optical disc player of the present invention includes a pickup that reads a signal on the disc, and a device that compares the output of the pickup with a predetermined reference level. a comparator for converting into a binary digital signal; a reference voltage generator for setting a reference level of the comparator; a positive feedback means for applying positive feedback to the comparator in order to cause the comparator to perform Schmitt operation; and the positive feedback means. This configuration includes a controller that turns on/off the operation of the controller.

Alternatively, a pickup that reads the signal on the disk, a normal comparator that compares the output of the pickup with a predetermined reference level and converts it into a binary digital signal, and a normal comparator that compares the output of the pickup with a predetermined reference level and converts it into a binary digital signal. This configuration includes a Schmitt comparator that converts a value into a digital signal, and a reference voltage generator that sets a reference level for the normal comparator and the Schmitt comparator.

Operation The data slicing device for an optical disc player of the present invention has the above-described configuration, so that when data is read during normal playback, it is possible to play back a digital signal with a small chicness through the operation of a normal comparator, and when accessing data, it is possible to play back a digital signal with a small chicness. The operation of the comparator provides an output of a digital signal without any whiskers, making it possible to stably follow the rotational speed, thereby increasing the access speed.

Embodiment Hereinafter, a data slicing device for an optical disc player according to a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a data slicing device for an optical disc player in a first embodiment of the present invention. 1 to 8 in FIG. 1 are common components with those in FIG. 3, and will be represented by the same numbers. 1 is a positive feedback means for applying positive feedback to the comparator, and 1Q is a controller for turning on/off the operation of the positive feedback means.

A controller 1o is also provided in a conventional optical disc player to control trick plays such as normal playback and access, and in the present invention, signals necessary for controlling a data slicing device are extracted from the controller and connected. It means to do.

CL with the optical disc player configured as above.
The operation of the data slicing device when reproducing a disc recorded in the V format will be described below.

When the controller 10 instructs normal reproduction 17, it receives the signal and turns off the operation of the positive feedback means 9. Then, the comparator 5 no longer performs the Schmitt operation, but compares the output of the head amplifier 4 with the reference level set by the reference voltage generator 6, and outputs a binary digital signal depending on the magnitude thereof. At this time, the noise in the output of the hesoad amplifier 4 is small, the output digital signal of the comparator 6 is less likely to have whiskers, and the edge jitter is also small.

When the controller 10 instructs the access mode, upon receiving the signal, the positive feedback means 9 is turned on. Then, the comparator 5 will perform Schmitt operation, and even if there is some noise on the input, no whiskers will occur in the output digital signal. 1 At this time, the output digital signal °
Although the edge jitter increases, it is small when considered as a ratio to the shortest period, and can be greatly improved by setting the Schmidt level symmetrically in both directions with respect to the reference level, and there is almost no problem with tracking the rotation speed. There isn't. Further, since it is not necessary to constantly read data while the pickup is moving, an increase in jitter does not cause a problem in that respect as well.

Note that the correspondence relationship between the mode instructed by the controller 1o and the ON/FF mode of the positive feedback means 9 may be freely set as necessary.

A data slicing device for an optical disc player according to a second embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of a data slicing device for an optical disc player showing a second embodiment of the invention. Reference numerals 1 to 8 in FIG. 2 are common components with those in FIG. 3, and they will be represented by the same numbers. 11 in FIG. 2 is a Schmidt comparator. However, comparator 5 means a normal comparator that does not apply Schmidt, unlike the 11 Schmidt comparators.

CI with the optical disc player configured as above.
, V format, the operation of the data slicing device will be described below.

Rotary servo circuit A may have some jitter in the edge time signal, but since it requires a digital signal without whiskers as input, it inputs the output of the Ishmit comparator 11, which does not cause whiskers.

Since the signal processing circuit 8 receives as input a digital signal containing highly accurate edge time information, it receives the output of the normal comparator 6, which is resistant to jitter.

The rotary servo circuit 7 requires the comparator output in the rough servo state of the rotary servo, such as during access, and the signal processing circuit 8 mainly requires the comparator output during normal playback with little noise.

Note that the output of the normal comparator 6 and the output of the Schmitt comparator 11 are connected to the rotation servo circuit 7 and signal processing by using a multiplexer and a controller, and switching the multiplexer according to instructions from the controller as in the first embodiment. The same signal may be selected and sent to the circuit 8.

Effects of the Invention As described above, in addition to the conventional configuration, the data slicing device for an optical disc player of the present invention has a comparator that selects between normal operation and Schmitt operation to reduce jitter during normal playback. It is possible to achieve a data slicing device for a high-performance optical disc player by achieving both of the two contradictory elements of small playback and stable rotational speed followability during access.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a data slicing device for an optical disc player that is a first embodiment of the present invention, and FIG. 2 is a block diagram of a data slicing device for an optical disc player that is a second embodiment of the present invention. Figure 3 is a block diagram of a data slicing device for a conventional optical disc player.
FIG. 4 is an exemplary output waveform diagram of each component when there is no noise, and FIG. 5 is an exemplary output waveform diagram of each component when there is large noise. 1...Optical disc, 2...Spindle motor, 3...Pickup, 4...
...Head amplifier, 6...Comparator, 6.
...Reference voltage generator, 7 ... Rotating servo circuit, 8 ... Signal processing circuit, 9 ... Positive feedback means, 1o ... Controller, 11...
...Schmidt comparator. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 Ginkai

Claims (2)

[Claims] (1) A pickup that reads the signal on the disk, and compares the output of the pickup with a predetermined reference level.
a comparator for converting a value into a digital signal; a reference voltage generator for setting a reference level of the comparator; a positive feedback means for applying positive feedback to the comparator in order to cause the comparator to perform a Schmitt operation; A data slicing device for an optical disc player, comprising a controller that turns on/off the operation. (2) A pickup that reads the signal on the disk, and compares the output of the pickup with a predetermined reference level.
A normal comparator that converts the value into a digital signal,
A Schmitt comparator that compares the output of the pickup with a predetermined reference level and converts it into a binary digital signal, and a reference voltage generator that sets a reference level for the normal comparator and the Schmitt comparator. A data slicing device for optical disc players.