CN1039556C - Track counting servo circuit and method thereof - Google Patents

Abstract

The track counting servo circuit for compensating the track counting error that occurs when the optical disc device is accessed at high speed, advantageously has a track counting error detector to detect the error of the track counting signal generated when reading the track counting signal, A rectangular wave is generated, the velocity of the rectangular wave coincides with the target velocity in the error portion of the detected track count signal, and compensation is performed in the error interval. Therefore, the trace access speed can be improved.

Description

Track counting servo circuit and method thereof

The present invention relates to a track counting servo circuit of an optical disc device, more specifically, it relates to a track counting servo circuit for compensating the track counting error generated when the optical disc is accessed at high speed.

Generally, various deviations in some optical disc devices such as compact disc read only memory (CD-ROM), compact disc graphic drive (CDG) and compact disc drive (CDP) can be compensated by various servo devices. Examples of these servos include: focus servos, tracking servos, constant linear velocity (CLV) servos, feed servos, and the like. The focus servo mechanism compensates by detecting the up and down (radial direction) fluctuation of the optical track caused by the rotation of the optical disc, while the tracking servo mechanism detects the left and right (latitude direction) of the optical track also caused by the rotation of the optical disc. ) fluctuations to compensate. In addition, the CLV servo mechanism compensates the time value of the data according to the fluctuation of the disc rotation. And, there are two methods according to the movement of the light spot in the optical disc device: one is a tracking jump method for moving the objective lens, and the other is a sled method for moving the pickup itself. Thus, a micro-tracking servo is used to track on the optical disc track using objective lens movement, and a sled servo is used to track on the optical track using the motion of the pickup head itself.

In these optical disc servo mechanism devices, since for CD-ROM, the speed at which the information contained on the optical disc is read determines the quality of the product, which is different from CDG or CDP. Therefore, it is necessary to use the slide rail (sled) motor to Pickup transport, track jumping and track transport are precisely controlled to reduce access time.

Fig. 1 is a block diagram of a conventional servo control circuit. With reference to Fig. 1, this servo control circuit comprises: optical disc 11; Pick-up head 12, is used for reading data from optical disc 11; Radio frequency (RF) amplifier 13, is used for enlarging the track count that pick-up head 12 detects when counting track number signal; a counter 14 for counting the number of tracks; and a microcomputer 15 for controlling the tracking servo mechanism.

The working process of the servo control circuit with the structure shown in Figure 1 is: the microcomputer 15 calculates the number of tracks from a given point to the target track and drives the slide rail (sled) motor, so that the pickup head 12 is sent to the calculated track number. The radio frequency amplifier 13 amplifies and outputs an RF signal representing the optical track, which is input by moving the pickup 12 according to the instruction of the microcomputer 15 . Counter 14 counts the number of tracks currently input, and if it equals the number of tracks calculated by microcomputer 15, then microcomputer 15 will issue an instruction to stop the slide rail (sled) motor, so that the pick-up head 12 can be delivered to the target track.

The conventional movement of the pickup head described by the above method will cause a problem: due to the limitation of the signal reading frequency and external influences in the high-speed drive, the pickup head cannot count the number of optical tracks within a predetermined period, so the pickup head will move over the target Tracks, whose number is equal to the number of uncounted tracks, become a serious problem in high-speed access.

SUMMARY OF THE INVENTION To solve the above-mentioned problems, it is an object of the present invention to provide a track count servo circuit for compensating the error portion of the track count signal so as to minimize the access time.

Another object of the present invention is to provide a track count servo method for compensating the error portion of the track count signal so as to minimize the access time.

In order to achieve the above-mentioned first object, the present invention provides a track counting servo circuit of an optical disc drive device, which includes: a track counter, which uses the track counting signal read out from the disc by the pick-up head to count the tracks , to determine how many traces the pick-up head needs to transmit in order to reach the target trace; a microcomputer, used to control the movement of the pick-up head; a trace count error detection device, used to test the error that occurs when reading the trace count signal The track count error; and the track count signal compensating means, used to compensate the measured track count error to the track count signal, so as to provide a compensation signal for the track counter.

To achieve another object, the present invention provides a track counting servo method of a track counting servo circuit having: a track counter for counting tracks using a track counting signal read from a disc by a pickup head Counting is performed to determine how many traces the pickup head needs to transmit to reach the target location; a microcomputer is used to control the movement of the pickup head; a trace counting error detection device is used to test the number of traces that appear when reading the trace counting signal A trace count error occurs; and a trace count signal compensating device for compensating the measured trace count error to the trace count signal, thereby providing a compensation signal for the trace counter, the servo method comprising the following steps:

Read the trace count signal;

detecting a trace count error from the read out trace count signal;

A corrected track count signal is generated using the detected error data and the read track count signal.

By describing the preferred embodiment in the accompanying drawings, the above-mentioned purpose of the present invention and some other advantages will be more apparent:

Fig. 1 is a block diagram of a conventional servo control circuit;

Fig. 2 is a block diagram of the track counting servo circuit of the present invention;

Fig. 3 shows several waveforms of various parts of the trace counting servo circuit according to an embodiment of the present invention;

FIG. 4 is a flowchart illustrating the track count servo method of the present invention.

2 is a block diagram of a trace count servo circuit according to an embodiment of the present invention;

Referring to Fig. 2, the track counting servo circuit of the present invention includes:

An RF amplifier 23 is used to amplify the track count signal, which is read when the pickup 22 reads data from the disc 21;

Track counting error detection means 24, used for detecting errors in the track counting signal that occur when reading the track counting signal;

Track counting signal compensating means 25, used for compensating and outputting the track counting signal, with a quantity equal to the measured track counting error;

a track counter 26 for receiving the compensated track count signal to count the number of tracks;

A microcomputer 27 is used to control the tracking servo mechanism.

The trace counting signal compensating device 25 comprises:

A target speed rectangular wave generator 251, which is used to generate and output the error part signal of the track count signal measured by the track count error detection device 24, as a rectangular wave consistent with the target speed;

A "NOT gate" 252 for inverting and outputting the count pulse of the track count signal output from the RF amplifier 23, thereby generating an error portion signal with a logic "low" signal;

An exclusive OR gate (XOR) means 253 for performing an exclusive OR operation of the signal output from the target rectangular wave generator means 251 and the signal of the "inverter" 252 to generate a compensated trace count signal.

Fig. 3 shows several waveforms of various parts of the trace count servo circuit according to one embodiment of the present invention.

Referring to FIG. 3, waveform 31 is the signal waveform at node A of FIG. 2, which represents the amplified track count signal amplified by RF amplifier 23. Referring to FIG. Waveform 32 is the signal waveform at node B in FIG. 2, which represents the inverted waveform 31 from NOT gate 252, wherein the error generating portion goes "low". Waveform 33 is the signal waveform at node C in FIG. 2 where the error portion of waveform 31 goes "high". Waveform 34 is the signal waveform at node D in FIG. 2 and represents a signal having pulses at the same frequency as the track count signal generated by target velocity square wave generator 251 during the "high" period of waveform 33. Waveform 35 is the signal waveform at node E in FIG.

FIG. 4 is a flow chart of forming a correction signal according to the track counting servo method of the present invention.

Referring to Fig. 4, the track counting servo method comprises the following steps:

The signal reading step 41 is used to read the optical trace counting signal;

an error detection step 42 for detecting a track count error from the read track count signal; and

A correction signal forming step 43 is used to generate a corrected track count signal which is corrected using the detected error data and the read track count signal.

The correction signal forming step 43 includes: step 44, which is used to generate a rectangular wave whose frequency corresponds to the target speed in the detected error part; step 45, which is used to invert the read trace count signal; step 46 , used to perform an exclusive-or operation (XOR) on the rectangular wave generated in step 44 and the inverted count signal generated in step 45 .

The track count signal compensating method of the track count servo circuit according to the present invention having the above-mentioned structure will be described in more detail below with reference to the accompanying drawings.

The track count signal is composed of a rectangular wave having a predetermined frequency. In high-speed trace access, an interval E (waveform 31 in FIG. 3) occurs during which the pulses constituting the track count signal cannot be read due to the limitation of the signal reading frequency and other reasons.

To compensate for the signal at the error interval E, the RF amplifier 23 amplifies and outputs the track count signal read from the disc 21 by the pickup 22 in step 41 . Then, if an error generation interval such as signal 31 in 3 is detected in step 42, the track count error detecting means 24 receives the track count signal and then detects an erroneous part of the track count signal in which no pulse is read. Here, as shown in the waveform 33 in FIG. 3, the normal signal interval of the signal detected by the track counting error detection device 24 is shown as a "low" level, and the error interval E, that is, the pulse-free interval is shown as a "high" level. flat.

In the step 44 of the correction signal forming step 43, the target speed rectangular wave generator 251 receives the signal 33 and generates a pulse whose frequency is the same as the clock frequency of the track counting signal corresponding to the target speed during the error generation interval, thereby outputting the signal 33.

The clock frequency of the track counting signal corresponding to the target speed is determined by estimating the moving speed of the track and by means of the access time of the designed system.

In step 45 of correction signal forming step 43, NOT gate 252 inverts signal 31 generated by RF amplifier 23 to obtain signal 32 and thus generates a "low" level signal which marks the generation of the error. On the other hand, at step 46, an exclusive OR (XOR) operation is performed on the signals 34 and 32 respectively provided by the target velocity square wave generator 251 and the NOT gate 252 to generate an error-corrected signal such as the signal 35 of FIG. The optical track counter 26 receives the error correction signal to count the optical tracks accurately, and the microcomputer 27 uses the counting result to control the tracking servo mechanism.

Thus, the track count servo circuit of the present invention compensates the error portion of the track count signal, thereby effectively increasing the track access speed.

While the present invention has been particularly shown and described with reference to specific embodiments, it will be understood by those skilled in the art that changes in form and details may be made without departing from the spirit and scope of the invention as defined by the appended claims. Make various modifications.

Claims (4)

1. the optical track of disc drive unit counting servo circuit has and is used to control the radio frequency amplifier that picks up cephalomotor microcomputer and be used to amplify the optical track count signal of being read from CD by pick-up head, it is characterized in that described circuit further comprises:

The optical track counter is used for from the optical track count signal optical track being counted, so that pick-up head was transported some optical tracks, up to impact point;

Optical track counting error pick-up unit is used to detect the optical track counting error that produces when reading described optical track count signal; With

Optical track count signal compensation system is used for the amount the same with the optical track counting error of described detection compensated to described optical track count signal, so that the signal that affords redress for the optical track counter.

2. optical track counting servo circuit as claimed in claim 1, wherein said optical track count signal compensation equipment comprises:

A target velocity square-wave generator is used for producing and exporting the error part signal of the optical track count signal that is recorded by optical track counting error pick-up unit, as the square wave consistent with target velocity;

An inverter is used for making by described pick-up head anti-phase from the count pulse of the optical track count signal of dish output, and to make the error part signal be " low " signal, thereby export anti-phase signal; And

An XOR device (XOR) is used for two signals of target velocity square wave generating means and inverter output are carried out XOR (XOR) computing, thereby generates the optical track count signal of compensation.

3. the optical track of an optical track counting servo circuit is counted servo method, and sort circuit has an optical track counter, from the optical track count signal that pick-up head reads from dish optical track is counted, and arrives destinations pick-up head is transported some optical tracks; A microcomputer, be used for controlling the motion of pick-up head, optical track counting error pick-up unit, be used for detecting the optical track counting error that produces when reading the optical track count signal, optical track count signal compensation system, be used for the amount the same with the optical track counting error that is detected compensated to the optical track count signal, described servo method comprises:

Read the signal read step of optical track count signal;

From the optical track count signal that reads, detect the error detection step of optical track counting error; And

Form step by the correction signal of using error information that detects and the optical track count signal that reads to produce the optical track count signal of proofreading and correct.

4. optical track counting servo method as claimed in claim 3, wherein said correction signal forms step and comprises:

Square wave forms step, is created in the error part square wave consistent with target velocity that is detected;

The anti-phase step of count signal is used for making the optical track count signal that reads anti-phase; And

The signal operation step is used for to being formed the square wave that step forms by square wave and the anti-phase count signal that is produced by the anti-phase step of count signal carried out XOR.

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