JPS59171080A - Track jump control circuit of disk record reproducing device - Google Patents

Abstract

PURPOSE:To raise the correction of a track jump error by controlling a moving speed so that the frequency detector of a ripple portion in a pickup output becomes equal to a track jump number per unit time from its output signal. CONSTITUTION:As for the operation of the time of a jump control, a pickup 13 moves toward an object track by a jump command. A spot S moves in the direction as indicated with an arrow by a focus servo, cross the track, and photodetecting quantity of a photodetecting part 17 is varied. Frequency generated in its output signal corresponds to the moving speed of the pickup, detected by a detector 29, and the output of an FV transducer 30 is varied in accordance with the frequency, the moving speed of the pickup 13 is controlled variably so that the number of tracks crossing per unit time of an optical beam becomes constant. The number of tracks crossed by the spot per unit time becomes constant, therefore, a substantially exact search operation is executed. Therefore, the error of a track jump in a speed varying period is corrected sufficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a disc record playback device suitable for, for example, a CD (optical disc) system DAD (digital audio disc), and particularly relates to a disc record playback device suitable for a CD (optical disc) type DAD (digital audio disc). Concerning improvements to skip control circuits.

[Technical background of the invention]

Recently, in the field of audio equipment, a digital recording and reproducing method using PCM (Gruscordomo, Solulation) technology is being adopted in order to achieve high fidelity reproduction as much as possible. In other words, this is what is called digital audio conversion. This is because it has been established in principle that the optical characteristics are independent of the characteristics of the recording medium and are much superior to those using conventional analog recording and reproducing methods.

In this case, a system that uses a disk as a recording medium is called a DAD system, and optical, electrostatic, and mechanical recording methods have been proposed. Regardless of which method is adopted, the playback device that embodies it must be able to satisfy a variety of advanced control functions and performance that cannot be found in conventional devices. ing.

In other words, if we take the CD system as an example,
CLV is a disk made by coating a transparent resin disk with a diameter of 12 cm and a thickness of 1.2 cm with a metal thin film that forms bits (irregularities with different reflectances) corresponding to digital (PCM) data. Approximately 500 depending on the (constant linear velocity) method
It is driven to rotate at a variable rotation speed of ~200 (r, p, m), and reproduced in a linear tracking manner from the inner circumference side to the outer circumference side using an optical pickup containing a semiconductor laser and a photoelectric conversion element. However, the disc has a track pitch of 16 [μm], and a huge amount of information is recorded in the program area (radius 25 to 58 [111111]), which can be played in stereo for about an hour on one side. Those index data etc. are stored in the lead-in area (radius 23 to 25 [: mm
This can be easily seen from the fact that it is included in ).

FIG. 1 shows a conventional disc record reproducing apparatus of the CD type. That is, in FIG. 1, numeral 11 is a disk, on one side of which a bit string is recorded, and is rotated by the disk motor 2 at the aforementioned variable rotation speed. At the bottom of this disk 110 in the figure, a big aperture /7'''13 is provided. It consists of 19 mag.

The objective lens 14 is operated by a tracking actuator 18 and a focus actuator 19.
The tracking direction (the radial direction of the disk II) and the focus direction (the direction perpendicular to the surface of the disk 11) are controlled respectively. Such an objective lens 14 is irradiated with a light beam emitted from a laser emitting section 16 via a beam splitter 15. Therefore, the light beam is focused (spotted) on the signal recording surface of the disk 1 by the objective lens 14, as shown by the dotted line in the figure.
are combined and reflected according to changes in the bits of disk II. This reflected light travels backward through the objective lens 14, is reflected at right angles by the beam splitter 15, and is received by the light receiving section 17. The light receiving section 17 then outputs a signal having frequency characteristics corresponding to the presence or absence of bits. This output signal is converted into an RF multiplied signal and is supplied to a demodulation and reproduction system circuit (not shown) via the output terminal 20, and is subjected to well-known demodulation and reproduction processing.

Further, the output signal from the light receiving section 17 is also supplied to the focus servo circuit 21. The focus servo circuit 21 generates a focus error signal corresponding to a focus error (focus error) of the light beam on the signal recording surface of the disk 11 based on the detection signal. By supplying this focus error signal to the focus actuator 19, the objective lens 14 is moved in the focus direction so that the focus of the beam of light is correctly aligned on the signal recording surface of the disk 11. ,
Focus servo is applied here.

Furthermore, the output signal is also supplied to the tracking circuit 22. This Tragging User? The circuit 22 is
Based on the above output signal 7, the file on the disk 11,)
A tracking error signal is generated corresponding to a shift (tracking error) of the spot of the light beam with respect to the row in the forward and reverse directions (radial direction of the 7j isk 11). and,
By supplying this tracking error signal to the tracking actuator 18, the objective lens 14 is moved in the tracking direction so that the spot is always correctly positioned on the bit string, and a mark (?) is applied here in the tracking direction. It has become so.

Here, the above pick-up f13 is 1. The disk 11 is moved in the radial direction by a feed motor 23. That is, this is the rotating shaft 2 of the feed motor 23.
．． Shaft 2 connected to 9a and having a thread groove on the circumferential side
4 is Pickan f1. ? The feed motor 2 is designed to pass through a screw hole (not shown) provided in the
The pick-up 7'' 13 is moved toward the outer and inner peripheries of the disk 11 in response to the rotational direction of the disk 11.
The rotary drive is performed in accordance with the polarity and voltage level of the drive voltage output from the drive voltage.

Here, the feed motor drive circuit 25 outputs a drive IE pressure corresponding to the tracking error signal during the above-described reproducing operation to move the pick-up lens f13 to follow the movement of the objective lens 14, It has linear tracking.

The playback operation of the disc 11 has been explained above, but this kind of disc record playback device has a search function, which quickly selects (searches for) any data portion from among the digitized data recorded on the disc 1. Therefore, it is possible to perform track skipping control in which the pickup 13 is moved in the radial direction of the disk 11.

This track skipping control means will be explained below by giving an example. That is, in FIG. 1 again, a track skipping command signal based on a track jumping operation command from a keyboard section (not shown) is supplied to the input terminal 2-6. This track skipping command signal includes distance information between the current playback position (current position) of the pickup 13 and the target position (target position), and information on the distance between the current position ft2 and the target position on the disk 1.
It includes moving direction information indicating whether the track is on the inner or outer circumference of the track 1, and is supplied to the tracking servo circuit 22 and the track skipping signal generation circuit 27 via the input terminal 26, respectively. Then, the tracking servo circuit 22 first stops outputting the tracking error signal and changes the tracking direction? will be stopped.

On the other hand, the track skipping signal generation circuit 22 generates a track skipping signal based on the distance information and moving direction information. In other words, this track skipping signal is a voltage signal that has positive or negative polarity depending on the moving direction information and whose output time is set depending on the distance information. When such a truck is flying, the feed motor drive circuit 25 is supplied. Then, this feed motor drive circuit 25 outputs a drive voltage having a positive or negative polarity for a time set according to the distance information based on the -L, Rack skipping signal, and drives the feed motor. 23 is driven to rotate.

Here, the rotating shaft 23a of the feed motor 23 has a rotational speed/'
A voltage converter (hereinafter referred to as FG converter) 28 is connected to detect the rotational speed of the feed motor 23. Then, the output gain of the feed motor drive circuit 25 is variably controlled based on the detection signal from the FC converter 28, so that the feed motor 23 is always rotated at a constant speed. FG servo is applied so that the moving speed of the robot is constant.

Therefore, the pick-up f13 moves toward the target position at a constant speed for only the time set by the distance information, so when the bi-quad 4-de 13 stops, the spot is If the number 0 is on the white track, the search operation will be performed here. Then, when the pickup 13 stops,
Immediately, a tracking error signal is output from the tracking servo circuit 22, and the tracking servo is applied, and the reproduction state is returned.

[Problems with background technology]

However, since the conventional track jumping control circuit as described above is provided with the F'G converter 28, there are problems in that a load is applied to the feed motor 23 and the volume occupied is also increased.

In addition, in practice, the disk 11 has eccentricity and variations in track pitch based on this (C), so even if the moving speed of the pickup 0 is made constant by the FG servo, the number of tracks that the spot crosses in the nest time is Therefore, even if the track jumping signal is generated accurately, the pickup 13 cannot be stopped on the target track.
This makes it impossible to perform a good search operation.

[Purpose of the invention]

This invention was made in consideration of the above-mentioned problems, and aims to accurately pick up a device with a simple configuration.
An object of the present invention is to provide an extremely good track skip control circuit for a disc record playback device that can be moved to a rack.

[Summary of the invention]

That is, the trunk jumping control circuit of the disc record playback device according to the present invention includes track jumping control means for moving the pickup to the target position based on distance information between the current position of the pickup and the target position to which the pickup is to be moved. In the moving state of the pickup, the frequency of the slip-pull generated in the output signal of the pickup is detected. The present invention is characterized by comprising means for controlling the moving speed of the pickup so that the number of tracks is always equal.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 2, parts that are the same as those in FIG. 1 are designated by the same reference numerals, and only the different parts will be explained here. That is, the output signal from the light receiving section 17 of the big anno f13' is supplied to the ripple detector 29. This ripple detector 29 detects the frequency component of the resile that occurs in the output signal each time the spot crosses a track during track skipping as described above. The output signal of this resill detector 29 is supplied to a frequency/voltage converter (hereinafter referred to as F/V converter) 30, which generates a voltage signal corresponding to the frequency component and supplies it to the feed motor drive circuit 25. .

Here, this feed motor drive circuit 25 cuts off the input of the voltage signal from the FA converter 30 during the reproducing operation, and when the track skip signal is supplied from the track skip signal generation circuit 27, the FA A voltage signal from the converter 30 is input, and the output gain of the drive voltage supplied to the feed motors 2 and 9 is variably controlled in response to the voltage signal.

In the above configuration, the operation during track skip control will be described below. That is, the input terminal 2
When a truck/jump command signal is supplied to the pickup 13 and the pickup 13 moves toward the target track, the focuser is applied to the big anno 7° 13, so the focuser is applied to the pickup 13 as shown in Figure 3. As shown, each time the light beam spot (S) moves in the direction of the arrow in the figure and crosses multiple tracks (...T1.~T, l...),
The amount of light received by the light receiving section 17 changes, and the amount of light received by the light receiving section 1 changes accordingly.
In the output signal from 7, a glitch occurs as shown in FIG. 3(B). The frequency for this ripple naturally corresponds to the moving speed of the pickup 13, and this frequency is detected by the ripple detector 29 and
When supplied to the /V converter 30, the voltage level of the voltage signal output from the /V converter 30 to b changes in accordance with the frequency. By using such a voltage signal to variably control the output gain of the feed motor drive circuit 25, the moving speed of the pickup 13 can be varied such that the number of tracks that the light beam spot crosses per unit time is constant. become controlled.

Therefore, it is not necessary to connect the FG converter 28 to the rotating shaft 2'3a of the feed motor 23 as in the conventional track jumping control means, so the load on the feed motor 23 is reduced, and the ripple detector Since the converters 29 and 30 can be formed on a substrate on which other circuits are formed, this results in miniaturization.

Furthermore, even if the bit string recorded on the disk 11 has eccentricity or variations in track pitch, the number of tracks that the spot crosses per unit time is constant.
This allows a substantially accurate search operation to be performed.

Although not shown in the above embodiment, during the acceleration period from when the picker f13 starts moving until it reaches the above-mentioned movement speed, and during the deceleration period from the M movement speed until it stops, the number of tracks that the spot crosses per unit time is kept constant. However, since the number of tracks that the spot crosses during these speed change periods can be calculated in advance, the input terminal 26
By correcting the truck jumping command signal supplied to the vehicle in advance using the above calculation result, it is possible to sufficiently correct the difference in truck jumping during the speed change period.

Furthermore, this invention is not limited to the above embodiments,
In addition, various modifications can be made without departing from the gist of the invention.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide an extremely good track skip control circuit for a disc record reproducing apparatus that can accurately move a pickup to a target track with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional disc record playback device, FIG. 2 is a block diagram showing an embodiment of a track skip control circuit of the disc record playback device according to the present invention, and FIG. 3 is a block diagram showing an embodiment of the disc record playback device according to the present invention. FIG. 3 is a diagram for explaining the characteristics of a pickup output signal when the pickup in the device jumps over tracks. 11... Disc, 12... Disc motor, 13
...Pickup, 14...Objective lens, I5...
・Beam sinter, 16... Laser emitting part, 17.
... Light receiving section, 18... Tracking actuator,
19... Focus actuator, 2θ... Output terminal, 21... Focus servo circuit, 22... Tracking servo circuit, 23... Feed motor, 24...
・・Shaft, 25・・Feed motor drive circuit, 26・
...Input terminal, 27...Track skipping signal generation circuit, 28...FG converter, 29...Lisyl detector,
30...Sill converter. -48: Figure 2 Flute Figure 3'°■---111---0

Claims (1)

[Claims] A pickup reads out the digitized data by tracing the pit string on a disk on which digitized data obtained by encoding an information signal is recorded as a bit string, and the current position of the pickup and the pickup are moved. In a disc record reproducing apparatus, the disc record reproducing apparatus includes a track skipping control means for moving the pickup to a target position by moving the pickup at a constant speed for a predetermined time based on distance information between the pickup and the target position, the track skipping control means A rip-pull detector detects a frequency corresponding to a riffle that occurs in the output signal of the pink-up when the pickup is in a moving state, and a ripple-pull detector detects the frequency that the pickup jumps per unit time based on the output signal of the rip-pull detector. 1. A track skip control circuit for a disc record reproducing apparatus, comprising means for controlling the moving speed of the pick amplifier so that the number of tracks is always equal.