KR0131713B1 - High speed track search method in a compact disc player - Google Patents

Abstract

By manipulating the selection key of the key input part(22), the track jump mode is established, and the microcomputer subtracts the present track from the objective track and from the result, the sense count value(T) is set. If the sense count value(T) is above the established value, the microcomputer outputs, at the digital signal processing part(16), control data(D), clock signal(CL) and latch signal(LA) in order to carry out the high speed search. The digital signal processing part(16) by-passes the thread move order and the thread accelerating move order to the pick-up servo part and controls the thread motor to the high speed move.

Description

High Speed Track Search Method of Compact Disc Player

1 is a main block diagram of a compact disc player to which the fast track search method according to the present invention is applied.

FIG. 2 is a diagram showing the main part signal input and output of the digital signal processor shown in FIG.

3 is a flowchart illustrating the operation of the fast track search method of the compact disc player according to the present invention.

4 is a view showing the speed profile of the sled motor by the high-speed track search method according to the present invention.

FIG. 5 is a diagram for explaining the output waveform of the sense signal SE shown in FIG.

* Explanation of symbols for main parts of the drawings

2: compact disc 4: spindle motor

6: spindle motor drive unit 8: pickup

10: sled motor 12: RF amplifier

14 pickup pickup unit 16 digital signal processing unit

16A: CPU interface section 16B: Servo auto sequencer

18: digital / analog converter 20: microcomputer

22: key input unit

The present invention relates to a high speed track search method of a compact disc player, and more particularly, to a high speed track search method of a compact disc player that can significantly reduce the track search time when the high speed track search function of a compact disc player. .

In general, the tracks of compact discs are arranged at very fine intervals of approximately 1.6 μm, and the number of such tracks is approximately 20,000 tracks for an hour-hour disc. The function of the tracking servo is to inject a laser beam while accurately finding such a track, and the basic operation of the servo is to move the objective lens and the optical pickup body in the radial direction of the disc based on an electrical signal corresponding to the light reception state of the laser beam. By moving, the position of the beam is modified to track a given track.

There are two methods of moving the beam: the optical pickup body and the objective lens in the lateral direction. The electrons cannot move quickly because of the mass of the inertial mass, but can move largely instead. . In the latter case, the actuator (the objective lens and the driving unit) is light in weight, and therefore high-speed response is possible. However, since the movable range is narrow, there is a limit in the movable distance. Therefore, when searching for a track, the pickup body is first moved by a sled motor to select a rough position, and then the target track is caught. Then, the sled motor is restarted to correct the pickup position so that the objective lens is positioned at the center of the optical system.

As the tracking servo method, the conventional three-beam (rack-pinion) compact disc player employs the CXD 2500 series digital signal processing integrated circuit proposed by Sony of Japan as a digital signal processing integrated circuit. In the case where the CXD 2500 series digital signal processing integrated circuit is employed, the track is searched using the auto sequence function of the integrated circuit. These autosequence functions are for long-term track jumps, and 2N-track jump mode and M track jump mode are used. When performing long-term track jumps using these jump modes, the number of tracks desired by the microcomputer is processed. When set to an integrated circuit, the integrated circuit operates the sled motor by an automatic servo loop, and counts track jump count signals and mirror signals one by one, repeating servo on / off and searching for the target track. There was a problem that it takes a long time to move.

Accordingly, an object of the present invention is to provide a high speed track search method for a compact disc player capable of searching a track at high speed using a sense monitor function and a sense toggle function of a digital signal processor. .

According to a preferred embodiment of the high-speed track search method of a compact disc player according to the present invention for achieving the above object, in addition to digital signal processing data projected from the compact disc by the pickup according to the control data of the microcomputer In the track search method of a compact disc player having a digital signal processing unit for receiving data with a pickup servo unit for track access of the compact disc, when the long distance track search function is executed, the microcomputer commands sled movement command as control data. And a sense monitor command and a sense toggle command applied to the digital signal processor, based on a sense output signal toggled at a predetermined set track period and output from the digital signal processor to a target track according to the toggle of the sense output signal. The predetermined track in the number of moving tracks The subtracting operation is performed until the number of moving tracks is doubled to the predetermined set track so that the sled moving command functions as a high speed moving command until the first toggle of the sense signal occurs. It is converted into a movement command and maintained until the number of movement tracks is doubled to a predetermined set number of tracks so as to reach the vicinity of the target track. A high speed track search method for a compact disc player comprising the steps of performing the same.

Hereinafter, a high speed track search method of a compact disc player according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of the main components of a compact disc player to which the fast track search method according to the present invention is applied. In the figure, reference numeral 2 denotes a compact disc containing predetermined reproducible information, 4 denotes a spindle motor for rotating the compact disc 2, and 6 denotes a spindle motor for driving control of the spindle motor 4. 8 is a pickup for optically reading data recorded on the compact disc 2, and 12 is an RF signal, a focusing error signal and a tracking error signal from a photodetector (not shown) installed in the pickup 8; RF pickup unit for amplifying a, 14 is a pickup servo unit for controlling the sled motor 10 to transfer the pickup (8) or to control the focusing and tracking of the objective lens (not shown) installed in the pickup (8) to be.

In addition, the reference numeral 16 receives the RF signal from the RF amplifying unit 12 and performs digital demodulation and error correction, for example, EFM (Eight to Four-teen Modulation), and outputs a digital audio signal. Digital signal for controlling the tracking servo, the focusing servo and the sled moving servo by outputting a drive control signal to the spindle motor driving unit 6 according to control data of The digital signal processing unit 16 is composed of a digital signal processing integrated circuit of the CXD 2500 series proposed by Sony Corporation of Japan. Here, the digital audio signal output from the digital signal processor 16 is digitally converted by the digital / analog converter 18 and then output to the audio output unit (not shown).

Reference numeral 22 denotes a key input unit having a playback key for reproducing the compact disc 2 and a music selection key for selecting a song which is a recording content stored in the compact disc 2, and the reference numeral 22 denotes the key input unit 22. By outputting the clock signal CL, the latch signal LA, and the control data DA as a control signal to the digital signal processing unit 16 according to the key operation from the above), the overall system of the system such as the spindle servo and the pickup transfer servo It is a microcomputer which performs control.

FIG. 2 is a diagram showing the main part signal input / output of the digital signal processor 16 shown in FIG. As shown in the figure, in the digital signal processing unit 16, the clock signal CL, the latch signal LA, and the control data DA from the microcomputer 20 are servo-automatically via the CPU interface unit 16A. Servo auto sequencer (16B) is applied to the pickup servo unit 14 in accordance with the control data from the microcomputer 20, the control data (DA0) and the clock signal (CL0) and A latch signal LA0 is output to control the pickup servo unit 14, and a focus ok input signal FOK and a track jump count input signal CNIN from the pickup servo unit 14; The mirror input signal MIRR and the sense input signal SEIN are input and output the sense output signal SE to the microcomputer 20.

Here, the sense output signal SE is changed in the form of the output signal according to the control data DA from the microcomputer 20. In the present invention, the sense monitor command [XBX; Where B is a register address and X is the number of tracks to be counted. In the present invention, 200 tracks are set and a sense toggle command [CX; Where C is a register address and X is DON'T CARE] to the digital signal processor 16 to count the sense output signal SE set in the sense monitor command. Output is toggled for each track number. As shown in FIG. 5, the track monitor count input signal CNIN is counted from the rising point of the latch signal LA after the sense monitor command BX and the sense toggle command CX are output. Each time the number reaches 200, the level of the sense signal SE is toggled.

Next, a high speed track search method for a compact disc player according to the present invention will be described with reference to the flowchart shown in FIG. 3 and the above-described first and second views.

First, in step S1, when the track jump mode is set by an operation of the selection key of the key input unit 22 (eg, selection of recording contents (songs) 4 after reproduction of recording contents (songs) 1), the microcomputer ( 20) indicates the target track (e.g., the track number of the recorded content (song) 4) in step S2; Recorded in the TOC] is subtracted from the current track (recorded in the subcode Q channel) and the result calculated as 200 (corresponding to the number of tracks counted by the sense monitor command). Set to.

Thereafter, in step S3, the microcomputer 20 sets the sensing count value T to a predetermined set value [T1; For example, it is determined whether 3 (equivalent to 600 tracks)] or more (that is, fast track search is required), and if it is determined that the sense count value T is less than or equal to a predetermined set value T1, fast track search is executed. On the other hand, when it is determined that the sense count value T is equal to or greater than the predetermined set value T1, the control proceeds to step S4.

In step S4, the microcomputer 20 outputs the control data DA, the clock signal CL, and the latch signal LA to the digital signal processor 16 to perform the high-speed track search.

In this case, the control data DA is first of any one of a sled shift command (a sled forward shift command or a sled backward shift command (for example, in the case of a shift from the record content 1 to the record content 4). )] Is outputted to the digital signal processor 16, and then a sled acceleration movement command in which the gain of the sled motor becomes 2 is outputted to the digital signal processor 16, which is input by the digital signal processor 16. The sled shift command and the sled acceleration shift command are bypassed to the pickup servo unit 14 so that the pickup servo unit 14 controls the high speed movement as shown in the speed profile of FIG.

Thereafter, the microcomputer 20 generates a sense monitor command [XBX] as control data DA to obtain a sense output signal SE toggled every 200 tracks at the sense terminal of the digital signal processing unit 16; Where B is a register address and X is the number of tracks to be counted. In the present invention, 200 tracks are outputted to the digital signal processor 16, and then a sense signal [#CX; Where C is a register address and X is DON'T CARE.] Is output to the digital signal processing unit 16. Here, after each instruction is finished, the latch signal is output and the next instruction is Begins).

Subsequently, in step S5, the microcomputer 20 determines whether there is a toggle of the sense output signal SE at the sense terminal. When the sense output signal SE is toggled (that is, moves 200 tracks), control is next. The process proceeds to step S6.

In step S6, the microcomputer 20 outputs a sled constant velocity shift command in which the gain of the sled motor is 1 to the digital signal processor 16, and the sled constant velocity input input by the digital signal processor 16. The command is bypassed to the pickup servo unit 14 so that the pickup servo unit 14 controls the constant velocity movement as shown in the speed profile of FIG. At the same time, the microcomputer 20 decreases the sense count value T calculated in step S2 by one.

Next, in step S7, the microcomputer 20 determines whether the value obtained by subtracting 2 from the sense count value T reduced in step S6 (that is, T-2) is greater than or equal to zero, and is determined to be greater than or equal to zero. The process returns to the above-described step S5, whereas if it is not 0 or more, control proceeds to the next step S8. The reason for subtracting 2 from the above step S7 is to set a radius track of 200 tracks around the target track in the velocity profile of FIG. 4 as the target circle and to move the track 200 tracks away from the target circle (that is, 400 tracks away from the target track). Track) to decelerate the sled motor.

In step S8, the microcomputer 20 outputs a sled deceleration moving command in which the gain of the sled motor becomes zero to the digital signal processing unit 16, and the digital signal processing unit 16 inputs the sled deceleration moving command. The command is bypassed to the pickup servo section 14 so that the pickup servo section 14 controls the deceleration movement as shown in the speed profile of FIG. As a result, the light spot of the pickup enters the target circle shown in FIG.

As described above, the control by the fast track search method according to the present invention is terminated, and the existing short track search method, which is a binary track search method, is used to allow the optical spot of the optical pickup to reach the target track.

In the binary track search method, first move 128 tracks in the forward direction (progressive direction), and then read the Q channel of the subcode recorded in the track to determine whether the current track has passed the target track, and if not, It is determined whether the target track has been passed after moving 128 tracks in the forward direction, and if it has passed, it has moved 64 tracks corresponding to 1/2 of 128 in the reverse direction of the travel direction, and then again passed the target track. By judging continuously, the target track is reached by moving 32, 16, 8, 4, and 1 tracks.

Using the present invention described above, the track search time from the innermost track to the outermost track of a 12 cm compact disc was measured. The total required time was measured to be less than 2 seconds, which is significantly shorter than the conventional method which takes 3.2 seconds.

As described above, according to the high-speed track search method of a compact disc player according to the present invention, a target circle near a target track using a sense monitor function and a sense toggle function of a digital signal processing unit at a long distance track search (the specific embodiment described above) Since the track search can be performed while maintaining the servo-on state up to a radius of 200 tracks around the target track and counting only the sensed state, the track search time can be significantly shortened.

Claims (1)

The pickup servo unit 14 performs digital signal processing of data read out from the compact disc 2 by the pickup 8 and track access to the compact disc 2 according to the control data of the microcomputer 20. In the track search method of a compact disc player equipped with a digital signal processing unit 16 for receiving data from and to a data, when the long distance track search function is executed, the microcomputer 20 uses the sled shift command and the sense monitor command as the control data. Based on the sense output signal toggled for each predetermined track period by the digital signal processor 16 according to the sense signal applied to the digital signal processor 16, a target track according to the toggle of the sense output signal. By subtracting the predetermined number of tracks from the number of moving tracks until the number of moving tracks is twice the predetermined set track, After the sled movement command functions as a high speed movement command until the first occurrence of the toggle of the sense signal, it is converted into a constant speed movement command so that the movement track number is maintained until twice the predetermined set number of tracks. A high speed track search method of a compact disc player, comprising the steps of reaching a target track and converting the command into a deceleration movement command in the vicinity of the target track to perform a short distance track search to the target track.