JPS60125975A - Pickup position controlling method - Google Patents

Abstract

PURPOSE:To decrease the time required for random access by operating the difference between a radial position of an object position and a present radial position of a pickup and moving the pickup toward the object position based on the difference. CONSTITUTION:When a music playing at present is finished, a processor 9a of a microcomputer 9 reads a time record value tc corresponding to the music number to be selected next from an RAM 9c, extracts a time record value ta in response to the present position of the pickup 2 from a digital signal processing circuit 5 and those are outputted to a distance operating section 13. The operating section 13 operates a distance DELTAR between the radial direction position of a music to be selected and the radial direction position occupied by the pickup 2 at present by using a formula and gives an output to a pickup feed pulse generating circuit 14. After the pickup 2 is moved near the object position via a slider motor drive circuit 15 and a slider motor 16, the pickup is positioned to the object position by a tracking servo circuit. In the formula, r is the innermost radius of a program area where the digital information of a compact disc 1 is recorded, v is a linear velocity of the compact disc 1 to the pickup 2 and DELTAh is the track pitch.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a pickup position control method in a disc device such as a video disc player or a compact disc player. move the pickup toward the target position using time information according to
The present invention relates to a pickup position control method for controlling the position of the pickup.

<Prior Art> In disc devices such as compact disc players and video disc players, a pickup is positioned at a desired position and information can be read from that position (random access).

There is the following method as a conventional pickup position control method in such random access.

The first method is to calculate the number of tracks between the current pickup position and the target position, and when the number of tracks the pickup has jumped to matches the number of tracks, it is assumed that the target position has been reached and the movement of the pickup is stopped. The second method is to move the pickup at regular intervals until it passes the target position, and then return the pickup if it has gone too far.

<Disadvantages of the Prior Art> Now, in the first method, the time required for each track to make one revolution is stored, or the correspondence between the number of tracks and time information is stored, and the pickup The number of tracks from the initial position to the target position and the current position is calculated using the time information corresponding to the target position and the current position and the stored information, and the number of tracks to the target position is calculated by taking the difference. However, the first method has disadvantages in that it requires a lot of effort and processing to calculate the number of tracks between the target position and the current position, and requires a considerable amount of memory capacity.

In addition, in the second method, it is necessary to monitor whether the target position has been passed, so the subcoding recorded on the compact disk must be read every time the target position is moved. The disadvantage is that it takes a long time.

<Objective of the Invention> The object of the present invention is to calculate the radial distance between the target position and the current position by a powerful calculation process, move the pickup toward the target position based on the distance, and perform random access. An object of the present invention is to provide a pickup position control method that can shorten the time required.

<Overview of the Invention> The present invention provides time information according to the target position of the pickup;
From the disk M) 1V, the difference between the radial position of the target position and the current radial position of the pickup is calculated from the time information according to the current position of the pickup included in the digital information, and the pickup is started based on the difference. This is a pickup position control method that controls the position of the pickup by driving a drive motor (referred to as a slider motor) to move the pickup toward a target position. 1. -F y' + ri /y -r
+jl -/ l) A'r rim, freezing, sub+4
↓1 is a block diagram showing an embodiment in which the time required for random access can be shortened and is applied as necessary to calculate the difference.A compact disc 1 has an acoustic signal. It is recorded digitally, and the frame synchronization signal and
Control data called bucoding is recorded. ・The bucoding is P, Q, R, 3°T, U,
Consisting of 8 bits V and W, one block is formed by 98 sub-coatings, the P channel of this block records information indicating the beginning of the song, and the Q channel records (a) information indicating the current position of the pickup. Pick up the corresponding song Vj and (b) how many minutes and seconds (called a time record) and what frame from the beginning of the song number.

(c) and an absolute time record from the initial position of the pickup.

The pickup 2 optically inputs the information recorded on the compact disc 1 into the physical processing circuit 3. The waveform shaping processing circuit 3 amplifies the RF signal output from the pickup 2, slices it at a predetermined slice level, shapes the waveform, and sends the signal obtained by waveform shaping (referred to as gFM signal) to the CLV circuit 4 and a digital signal. It is input to the processing circuit 5. The CLV circuit 4 is composed of a known PLL circuit 4a, a phase comparator circuit 4b, etc.
The PLL circuit 4a reproduces the basic unit clock signal included in the EFM signal, and the phase comparator circuit 4b outputs the reproduced clock signal RC8 output from the PLL circuit 4a and a crystal oscillator (not shown) built in the digital signal processing circuit 5. The clock signal CLS to be output moves according to the phase difference.
The driving signal DVS is applied to the spindle motor 7 via the amplifier 6. Note that when the reproduced clock signal RC8 and the clock signal CLS are synchronized, the spindle motor 7 rotates with respect to the pickup 2 at a predetermined linear velocity (1.2 to 1.4 m/It).

On the other hand, the digital newsletter processing circuit 5 demodulates the EFM signal, separates the audio data and sub-coding, performs error detection/correction processing on the audio data, inputs it to the next stage DA converter 8, and also outputs the sub-coding. is output to the microcomputer 9. The DA converter 8 performs DA conversion on the 16-bit audio data input from the digital signal processing circuit 5, and inputs the output to the audio circuit 10.
outputs audio from a speaker (not shown). Microcomputer 9
analyzes the sub-coding Q channel, extracts data indicating the current song number, elapsed time for each song, total elapsed time, etc., inputs it to the display device 11 for display, and also inputs it from the operation panel 12. Random access processing is executed based on the input information. In addition, RAM 9C of the microcomputer 8 contains information from the lead-in area (TOC: Table of Contents) of the compact disc 1 in advance. Information such as what number of songs starts (minutes, seconds, and frames), (b) the first and last song numbers, and (c) the time record value at which all songs end are read out and stored.

Now, Compact Disc Player Operation Guide 12
When the currently playing song ends, the processor 9a of the microcomputer 9 selects the next song from the RAM 9c under the control of the control program stored in the ROM 9b. The time record value tc corresponding to the exponent music number is read out and output to the distance calculation section 13. Further, the processor 9a analyzes the sub-coding input from the digital signal processing circuit 5, extracts a time record value ta corresponding to the current position of the pickup included in the Q channel, and similarly performs distance calculation on this value. It outputs to section 13.

The distance calculation unit 13 inputs r + V + Δ in advance.
Using h and t c + t 11, the radial position of the song to be selected and the position currently occupied by the pickup are determined by the following formula:
The distance .DELTA.R between the radial positions is calculated and outputted to the virtual feed noise generation circuit 14. Note that r in equation (1) is the radius of the innermost circumference of the program area PA in which digital information is recorded, referring to the cross-sectional view of the compact disc 1 in FIG. Linear velocity of 1 to pickup 2, Δh &'i
) is the rack pitch. Further, the reason why the distance ΔR is determined by equation (1) is as follows. In other words, the initial position force・
Letting t be the time record value between them, the distance t in the circumferential direction that the pickup 2 moves from the initial position during the time t can be expressed as t==y-j (2) using the following equation. Also, if R is the radial position where the pickup exists after the elapse of time, then the area (third
(See the shaded area in the figure), the force-ratio formula % formula % (3), which can be expressed as the product of the moving distance t in one circumferential direction and the track width, holds true. From equations (2) and (3), if we subtract R, we get R
:',, i −y−−(4). Therefore, in equation (4), if t - tc, the radial position of the target position is calculated, if t = ta, the radial position currently occupied by pickup 2 is calculated, and by taking the difference, equation (1) is derived. Incidentally, FIG. 4 shows a relationship diagram between the radius R and the time record value.

Returning to FIG. 1, the pickup feed pulse generation circuit 14
When ΔR is input, a pickup feed pulse PPP is generated whose pulse width corresponds to the magnitude of ΔR. The slider motor drive circuit 15 uses the pickup feed pulse P
PP is amplified and applied to the slider motor 16 to rotate the slider motor. As a result, the pickup 2 moves toward the target position and reaches near the target position at the time when the pickup sending pulse is interrupted. After that, a tracking servo circuit (not shown) picks up the pickup 2.
The digital information is read from the compact disc 1 while sequentially positioning it on the tracks, and if it detects a track with '1' written in the sub-coding P channel, the pickup 2 will select the first track number of the desired track number.
This means that it is positioned at e.

In the above explanation, 8R is calculated by calculating equation (1), but the correspondence between t and R is stored in memory at a predetermined time interval ΔL in advance, and the relationship corresponding to 70+ta is calculated in advance. Radius Rc
o You may consider Ra from the corresponding relationship and calculate △R using the following formula % formula % (5. In addition, in such a case, the time ftJj and the next ∆ can be expressed as the following time t (1 + 1). The radius value R corresponding to the time t(mouth〈1(111+1)) between is the radius value R1 corresponding to the time ti and the time t(1+
It is determined by linear interpolation (proportional distribution) from the radius value R(1+1) corresponding to l+ using the following equation.

Further, although the case where ΔR is calculated by the distance calculation unit 13 has been described, it is also possible to calculate it by the microcomputer 9 and output it to the pickup feed pulse generation circuit 14.

<Effects of the Invention> As explained above, according to the present invention, the distance #tΔR between the target position and the current position 1#11 can be calculated by using the expression (1) for the radial short distance ~ "ΔJ?" In addition, unlike the conventional method, there is no need to read digital information from a compact disk every predetermined movement distance, and the simple performance allows the pickup to be moved close to the target position in a short time. You can lick the direction distance,
As a result, the pickup can be positioned near the target position in a short time, and the time required for random access can be shortened.

Further, according to the present invention, the radial distance ΔR'& can be calculated using the information (time receipt value) recorded on the compact disc using equation (1) or from a correspondence table of radius values and time record values. Because I can do it, ΔR
The amount of memory required to store the data can be kept to a minimum.

Although the present invention has been described in detail with reference to the case where it is applied to a compact disc player, the present invention is not limited to this, and can of course be applied to disc devices such as video disc players.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment in which the present invention is applied to a compact disc player, Fig. 2 is a sectional view explaining the program area of the compact disc, and Fig. 3 is an explanation of calculation of the radial distance between the target position and the current position. FIG. 4 is a diagram showing the relationship between the radius R and the time record value. 1...Compact disc, 2...Pickup,
4... CLV circuit, 5... Digital signal processing circuit, I... Spindle motor, 9... Microcomputer, 12
...Operation panel, 13...Distance calculation section, 14...
Pickup feed pulse generation circuit, 15...Slider motor drive circuit, 16...Slider motor. Patent Applicant Alvine Co., Ltd. Agent Patent Attorney Chiki Saito

Claims (6)

[Claims] (1) In a pickup position control method that reads information recorded on a disk, from time information according to the target position of the pickup and time information according to the current position of the pickup included in the information read from the disk,
Calculate the difference between the radial position of the target position and the current radial position of the pickup, drive the pickup drive motor based on the difference, move the pickup toward the target position, and control the radial position of the pickup. A pickup position control method characterized by: (2) The time information according to the target position is the time from the initial position until the desired song number starts playing, and the time information according to the current position of the pickup is the cumulative playing time from the initial position. Claim No. 1 characterized in that
) The pickup position control method described in section 2. (3) A correspondence relationship between each of the song numbers and the time at which the song starts is read out from a disk in advance and stored in a memory, and time information corresponding to a desired song number is read from the memory. A pickup position control method according to claim (2). (4) When the radius of the innermost circumference of the program area on the disc on which information is recorded is r1, the linear velocity of the disc with respect to pickup is V, the track pitch is Δ, and the time information is t, the radial position R can be calculated using the following formula 8 [Formula %]
) or (2) or (3). (5) A correspondence relationship between time information t and radial position R is stored in a memory in advance, and a radial position according to the time information is determined from the correspondence relationship. ) or (2) or (3). (6) The pink-up position control method according to claim 11, characterized in that a pulse with a time width corresponding to the difference is generated to drive a pickup drive motor.