JPS629536A - Restarting method for performance in compact disc device - Google Patents

Abstract

PURPOSE:To keep a normal time and a relation of position at generation of a tracking error by muting an output at the detection of tracking error so as to calculate a pickup access time thereby obtaining the access position. CONSTITUTION:When time information is not consecutive, a signal processing circuit 4 turns off the tracking servo and mutes an audio signal. Then the circuit 4 uses a position before and after the generation of tracking error to calculate the required time restoring a pickup 2 to a position before jumping of the pickup 2. Then the circuit 4 uses a position before the generation of error and the access time to obtain an object position positioning the pickup 2. Then the pickup 2 is accessed to the obtained access position to release the muting. Thus, even if a tracking error takes place, the normal time and the relation of position are maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for restarting a performance in a compact disc device (hereinafter referred to as a CD device), and particularly to a method for restarting a performance in a CD device when a tracking error occurs.

<Prior Art> In a CD device, it is necessary to correctly position a beam spot on a track with a pitch of 1.6 μm, and to move the spot correctly on the track according to the rotation of the disk.

The positioning accuracy must be controlled to within 10.1 .mu.m, and it must be possible to correct positional errors of up to ±70 .mu.m. For this reason, CD devices are equipped with a tracking servo mechanism, which generates a tracking signal having a voltage value according to the deviation between the spot position and the track, and performs servo control using the tracking signal to move the beam spot to the track. While positioning directly above,
The spot is set in accordance with the rotation of the disk to accurately track the track.

Incidentally, vehicle-mounted CD devices are subject to vibrations from the vehicle. Therefore, the vibration may cause the pickup to jump over several trucks. Conventionally, if such a jump occurs, in other words, if a tracking error occurs, the pickup is returned to the position before the tracking error occurred (before the jump), and the performance is restarted from that position.

FIGS. 4(A) to 4(C) are explanatory diagrams illustrating a conventional performance restart method when such a tracking error occurs, and are explanatory diagrams illustrating a conventional performance restart method when such a tracking error occurs. is the total elapsed time from the initial position, and xI is the radial position of the pickup. Fourth
Figure (A) shows a diagram of the relationship between time and position during normal times,
The normal positions of the pickup corresponding to times t0, tl, and t2 are xo, x11x2. Now, in FIG. 4(B), when a tracking error occurs at time t1 and the pickup jumps from X to x1', conventionally, as shown in FIG. 4(C), the position x
The return time to return the pickup to 1 is Δt),
The performance is started again from the position X.

<Problem to be solved by the invention> Conventionally, when a tracking error occurs, the sound is cut off and the performance is restarted from the position X before the flight, in other words, the sound deadening time (Δt) Since the performance restart position is not advanced by a minute, there is a problem in that the normal relationship between time and position is deviated, causing a sense of discomfort to the listener.

In view of the above, an object of the present invention is to provide a performance restart method that can maintain the correct time and position relationship even if a tracking error occurs, or in other words, can restart the performance from a position advanced by the mute time.

Means for Solving the Problems> FIG. 1 shows the main blocks of a CD device that can realize the present invention.

1 is a compact disk, 2 is a pickup, 3 is a waveform processing circuit, 4 is a signal processing circuit, 5 is a tracking servo circuit, 6 is a pickup feed circuit, 7 is a feed motor, 8
1 is a rotational speed control unit, 9 is a spindle motor, 10 is an operation panel, 11 is a display device, 12 is an I)A converter, and 13 is an audio circuit.

Function> The signal processing circuit Ms4 checks the discontinuity of the time information included in the subcoding Q channel read by the pickup 2. If a tracking error is detected, the audio output is muted.

Thereafter, the signal processing circuit 4 calculates the position t0 before the occurrence of tracking blur and the position 1 . (Each position t0゜1, is the total elapsed time from the initial position, obtained from the Q channel of subcoding).The time required to return pickup 2 to the position t0 before flying (access time) Calculate t.

Next, a target position (access position) for positioning the pickup is determined using the position t before the tracking error occurred and the access time t.

Then, the pickup is made to access the access position, and after the access is completed, the mute is released.

<Embodiment> FIG. 1 shows a main block of a CD device that can realize the present invention.

1 is a compact disk, 2 is a pickup, 3 is a waveform processing circuit, 4 is a signal processing circuit, 5 is a tracking servo circuit, 6 is a pickup feed circuit, 7 is a feed motor, 8
1 is a rotational speed control section, 9 is a spindle motor, 10 is an operation panel, 11 is a display device, 12 is a DA converter, and 13 is an audio circuit.

Acoustic signals are digitally recorded on the compact disc 1, and control data called frame synchronization signals and subcoding are recorded for each predetermined number of data. In addition, sub-coding is P and Q.

R, S, T, U, V, W (7)811'), one block is formed by 98 sub-codings, and the P channel of the block contains information indicating the beginning of the song. The Q channel contains (i) the track number corresponding to the current position of the pickup, (iii) information on how many minutes, seconds (time information) and frame the pickup is located from the beginning of the track number; (Ii+) and absolute time information from the initial position of the pickup, etc. are recorded.

The pickup 2 optically reads the digital information recorded on the compact disc 1 and sends it to the waveform processing circuit 3.
Enter. The waveform processing circuit 3 amplifies the RF signal output from the pickup 2, shapes the waveform at a predetermined slice level, and inputs the signal obtained by waveform shaping (referred to as an EFM signal) to the signal processing circuit 4.

The signal processing circuit 4 demodulates the EFM signal, separates the audio data and sub-coding, performs error detection/correction processing on the audio data, performs DA conversion with the DA converter 12, and outputs the signal to audio circuit #113. Further, the signal processing circuit 4 analyzes the Q channel of the sub-coding, extracts data indicating the current song number of the mortar, the elapsed time for each song, the total elapsed time, etc., and displays it on the display device 11 as appropriate, and also displays it on the display device 11 as appropriate. Random access processing is performed based on information input from the panel 10. Further, the signal processing circuit 4 executes performance restart processing, which will be described later, when a tracking error occurs.

The tracking servo circuit 5 generates a tracking signal TR3 using the detection signal derived from the pickup 2 and drives a tracking actiniator (not shown) to move the objective lens OBL in the horizontal direction so that the spot of the laser beam is centered on the pit. control to come.

The pickup feed circuit 6 receives a feed signal given from the signal processing circuit 4 when positioning the pickup 2 at a predetermined target position (access position) or when moving the pickup 2 to follow a track in accordance with i performance. P.S.
Based on S and tracking signal TR3, feed motor 7
Rotate.

The CLV circuit 8a of the rotational speed control section 8 generates an EFM signal and a crystal oscillator built in the signal processing circuit 4.
A drive signal for rotating the spindle motor 9 at a constant linear velocity is generated using the 8 MHz clock signal CLS, and the drive circuit 8b rotates the spindle motor 9 based on the drive signal.

Conventionally, when a tracking error occurs, the sound is cut off and the performance is restarted from the position before the jump. However, as shown in FIG. 4(D), the present invention maintains a normal time and position relationship (to, X0i t,, x,
i t,, x2), in other words, the performance is restarted from the position X, +ΔX which is a minute after the mute time Δ.

The method for resuming playing according to the present invention will be explained below according to the flowchart shown in FIG.

(1) The signal processing circuit 4 demodulates the EFM signal input from the waveform processing circuit 3 and separates sub-coding. After that, absolute time information from the initial position included in the Q channel is extracted and set as to. Note that when playing from the first song, 10=0.

(2) Next, the signal processing circuit 4 converts the time information included in the Q channel of the next read subcoding to the current time 1. shall be.

(3) If the time interval between adjacent subcodings is ΔT, the signal processing circuit 4 checks whether the following equation (1) holds true, in other words, whether the time information is continuous.

Note that the above equation is not checked every time adjacent sub-coding is read, and t0+T and t are checked every predetermined time T. It can also be configured to check the continuity of. However, when the difference between t0+T and 1n is less than or equal to the allowable value, it is determined that there is continuity.

(4) If the time information is continuous, the signal processing circuit 4 is 1-
+1 and repeat the process from step (2) onwards.

(5) However, if the time information is no longer continuous in step (3), the signal processing circuit 4 turns off the tracking servo and exports the audio signal. In addition, the method of muting is (DA converter 12 of al acoustic data)
(b) by operating a mute circuit (not shown) of the audio circuit 13.

(6) After the tracking error has occurred, the signal processing circuit 4 uses the position (time information) to before the tracking error occurred and the position (time information) t after the occurrence of the tracking error to move the pickup 2 to the position before the tracking error occurred (the tracking error occurred). The time (access time) t required to return to the previous position) to is calculated.

Note that this access time is calculated as follows.

Now, referring to the cross-sectional view of the compact disc 1 in FIG. 3(A), the radius of the innermost circumference of the program area PA where digital information is recorded is r1, the linear velocity of the compact disc 1 with respect to the pickup 2 is v, and the rack pitch Δh
1. If the absolute time information from the initial position is t, the distance 1IIL in the circumferential direction moved from the initial position during time t is L=V-t (2). Also, if the radial position where the pickup 2 exists after the elapse of time is R, then the area surrounded by the circle with radius R and the innermost periphery of the program area (see the shaded area in Figure 3 (B)) is the area in the circumferential direction. It is the product of the moving distance @L and the track width Δh, and the following equation 1% (3) holds true.

If R is determined from equations (2) and (3), R=F〒W;-F=(4). Therefore, if we set 1 = 10 in equation (4), we can obtain the radial position R before the tracking error occurs,
Also 1=1. Then, the radial position R after the tracking error occurs is obtained, and the radial distance ΔR traveled by the pickup due to the tracking error is ΔR=R−R(5).

From the above, if the fast forwarding speed of the pickup 2 is vp, the access time t can be obtained from the following equation (6).

(7) Next, the signal processing circuit 4 uses the position t0 before the occurrence of the tracking error and the access time t to determine the target position (access position) t at which the pickup 2 is positioned according to the following equation 1% (7).

(8) After the signal processing circuit 4 moves to the current position 1. , and the access position tp in the forward direction (11,>1.,
) or in the backward direction (when 1,<1r), the pickup 2 is moved toward the target position, the tracking servo circuit 5 is turned on near the target position, and finally the pickup 2 the target position tP
position.

Note that whether or not the target position has been reached is determined by the current position 1. ,
The radial distance ΔR' between the target position tP and
), calculate the number of tracks N to jump from the current position t1 to the target position 1p using the following formula N=lΔR'1/Δh (8), and recognize it by monitoring the number of tracks actually skipped. I can do it.

(9) Perform the positioning process in step (8) until the positioning is completed.

(11) When the positioning is completed, it is checked whether the time t has elapsed since the positioning start time.

(11) When time t has elapsed, the signal processing circuit 4 cancels the mute and resumes the performance.

Note that the process in step (II) may be omitted.

<Effects of the Invention> According to the present invention, the steps of detecting the occurrence of a tracking error by checking the discontinuity of time information included in the sub-coding read by the pickup, and outputting when a tracking error is detected. a step of calculating the access time of the pickup from the positions before and after the occurrence of the tracking error; a step of determining the access position of the pickup from the position before the occurrence of the tracking error and the access time; Since the method for restarting the performance when a tracking error occurs is composed of the step of accessing the pickup and the step of canceling the mute after the access is completed, the normal time and position relationship can be maintained even if a tracking error occurs.In other words, Since the performance can be resumed from a position that has proceeded by the muted time, the listener will not feel any discomfort.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the main parts of a CD device that can realize the present invention, Fig. 2 is a flowchart of the processing of the present invention, Fig. 3 is an explanatory diagram of access time calculation method, Fig. 4 (A) to (C) is an explanatory diagram of the conventional method, Fig. 4 (D
) is an explanatory diagram of the method of the present invention. 1. Compact disc, 2. Pickup, 3. Waveform processing circuit, 4. Signal processing circuit, 5. Tracking servo circuit, 6. Pickup feed 9 circuit, 7. Feeding motor, 13. Audio circuit

Claims (1)

[Claims] A step of detecting the occurrence of a tracking error by checking the discontinuity of time information included in the sub-coding read by the pickup, a step of muting the output when a tracking error is detected, a tracking error. Calculating the access time of the pickup from the positions before and after the tracking error occurred; Obtaining the access position of the pickup from the position and access time before the tracking error occurred; Making the pickup access the access position; Mute after the access is completed. 1. A method for resuming performance in a compact disc device, comprising the step of canceling.