JPH07272394A - Disk reproducing device - Google Patents

Abstract

PURPOSE:To inexpensively detect a linear velocity of a disk without separately using parts such as optical devices by providing a linear velocity detecting function of the disk in a control part. CONSTITUTION:Each part and circuit of the device are controlled via a subcontrol part 131 by a control part 13 in accordance with an operation from a key operating part 14. In addition to the above function, the control part has three functions of a track jumping means, a time measuring means, a calculating means of disk linear velocity. An information reading position of an information reading head of the disk is moved backward in the reproducing direction by a prescribed number of tracks from a prescribed track position by the track jumping means. Then, the information reading position is moved to follow tracks, and a time until the information reading position reaches a prescribed track position again is measured by the time measuring means. Then, a linear velocity of the disk is calculated by a calculating means from the measured time and a radius in the prescribed track position. Consequently, the linear velocity of the disk can be detected without separately providing parts such as optical devices, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc reproducing method for reading information from a disc having a spiral track on which information is recorded, such as a compact disc, by rotating the disc so that the linear velocity of the track becomes constant. Regarding the device.

[0002]

2. Description of the Related Art In recent years, compact discs have been used not only for music but as a recording medium that can be mass-produced at low cost.
The CD-ROM is also widely used as a recording medium for images and computer data. Along with this, in the use of the compact disc, it is required to speed up the search of the reproducing device.

For that purpose, it is necessary to quickly detect the target address position, move the information reading position at high speed in the radial direction of the disk, and bring it to the target address position quickly. Here, in order to detect the target address position quickly, the number of tracks to the target address position is calculated in advance, the number of tracks is counted in the middle of moving the information reading position, and the information reading position is set to the target address position. The method of matching is effective.

However, since information is recorded at a constant density on the compact disc in order to increase the information recording density, the number of tracks to the target address position cannot be simply obtained from the difference between the target address and the current address. , The disk radius at the target address position and the current address position is greatly affected. FIG. 4 is a simplified diagram of a disk for explaining the method of calculating the number of tracks up to the target address, where r ₀ is the radius from the center to the position of the start address A ₀ , and is the radius at the start position of the program area. is there. r is the radius from the center to the position of the target address A.

Now, a minute radius width d at the position of radius r
The track length dx of the annular region of r can be regarded as a collection of dr / p circular tracks having a circumference of 2πr, where p is the pitch of the spiral. Therefore, dx = 2πr · dr / p (1) expressed.

Therefore, the length x of the spiral from the radius r ₀ to the radius r is

[0007]

[Equation 1]

It is represented by From this, the radius r is represented by r = ((p / π) x + r ₀ ² ) ^1/2 (3). If r = r ′ + r ₀ = N · p + r ₀ (4), the number of tracks N up to the target address is N = 1 / p ((p / π) x + r ₀ ² ) ^1/2 −r ₀ ) ... (5)

Further, when the data of the recording linear density (= the number of blocks per unit length) D is reproduced at the reproduction speed (the number of blocks reproduced per unit time) u, the linear velocity v _L is v _L = u / It is represented by D (6). Here, the linear density D is represented by the target address A and the length x of the spiral to the target address A as D = A / x (7), so that the expression (6) is v _L = u · x / A (8), and the spiral length x is expressed by x = v _L · A / u (9).

By substituting this into the equation (5), the number of tracks N up to the target address A is N = 1 / p (((p · v _L · A / π · u) + r ₀ ² ) ^1/2 − r ₀ ) ... (10), and the number N of tracks is obtained. Here, in order to calculate the number N of tracks up to the target address A, it is necessary to detect the linear velocity of the disk. Conventionally, as shown in FIG. 5, the linear velocity of a disc is determined by providing light and dark stripes 22 below a turntable 21 holding a disc 20 on which information is recorded, and using a light emitting element 23 and a light receiving element 24 as optical elements. The generated pulse was detected using the pulse counter 27 and the microcomputer 28.

The calculation of the linear velocity v _L is expressed by v _L = ωr = 2πr · n / N _rot (11) Here, ω is the rotational angular velocity, r is the radius at an arbitrary position on the disk, N _rot is the number of pulses generated per rotation, and n is the number of pulses generated per unit time.

[0012]

However, the above-mentioned conventional method for detecting the linear velocity of the disk has a problem that it requires two optical elements, that is, a light emitting element and a light receiving element, so that it is expensive. Furthermore, the two optical elements are accurately arranged,
Since it has to be fixed, there is also a problem that assembly is troublesome.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a disc reproducing apparatus for detecting the linear velocity of a disc by an inexpensive method without separately using parts such as optical elements. .

[0014]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention rotates a disk having spiral tracks on which information is recorded so that the linear velocity of the tracks is constant, and an information reading head is provided. In a disc reproducing apparatus for reading information from the track by controlling the information reading position of the track to follow the track, the information reading position of the information reading head is moved backward from the predetermined track position by a predetermined number of tracks in the reproduction direction. Track jump means, a time measuring means for measuring the time until the information read position reaches the predetermined track position again following the track after the information read position is moved by the track jump means, and the time measuring means. Of the disc and the disc radius at the predetermined track position. Characterized by comprising a calculating means for calculating the velocity.

Further, the track jump means repeatedly performs a process of moving the information reading position backward from the predetermined track position by a predetermined number of tracks a plurality of times, and the time measuring means reads the information by the track jump means. Each time the position moves, the time is measured, and the calculating means calculates a plurality of linear velocities of the disk based on the time measured each time the reading position moves, and calculates the linear velocities of the plurality of linear velocities. An average value is used as the linear velocity of the disk.

[0016]

According to the present invention, the information reading position of the information reading head of the disk is moved backward from the predetermined track position by the predetermined number of tracks by the track jump means, and after the information reading position is moved by the time measuring means, The time until the information reading position reaches the predetermined track position again is made to follow the track, and the linear velocity of the disk is calculated from the time measured by the calculating means and the radius at the predetermined track position. Therefore, it is possible to detect the linear velocity of the disk without separately using a component such as an optical element.

According to another aspect of the invention, a plurality of linear velocities of the disk are calculated, and the average value of the plurality of linear velocities is used as the linear velocity of the disk, so that the linear velocity detection accuracy can be improved. , More accurate linear velocity can be obtained.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. The control unit 13 controls each unit via the sub-control unit 131 according to an operation from the key operation unit 14. The sub-control unit 131 operates each servo circuit according to the command code generated by the control unit 13, and when the process for the command code is completed, a process completion code is generated. The control unit 13 detects the processing completion code to obtain the timing for outputting the next command code.

Reference numeral 1 denotes a disc on which information to be reproduced and index information necessary for reproduction thereof are recorded as a digital signal containing a synchronizing signal. The disc 1 is loaded and ejected at a reproducing position (on a turntable (not shown)) by a loading mechanism (not shown) according to an operation of a key operation unit. The motor M drives the loaded disk 1 at a predetermined rotation speed. The reproduced information and the index information recorded on the recording tracks of the disc 1 are optically read by the pickup 2. The signal read by the pickup 2 is sent to the signal conversion circuit 12 via the preamplifier 3 and is also input to the tracking servo circuit 5, the focus servo circuit 7, and the disc signal level detection unit 11.

The tracking error detection unit 4 detects from the output signal of the pickup 2 that the focus position of the reading beam emitted from the pickup 2 is displaced inward or outward from the track on the information recording surface of the disc 1, The corresponding positive and negative analog signals are output to the tracking servo circuit 5. The tracking servo circuit 5 is controlled to operate or not operate by the output signal from the sub-control unit 131, and in the operating state, the reading beam follows the track on the disk 1 in response to the signal from the tracking error detection unit 4. A tracking actuator (not shown) is driven. Also, a large movement that cannot be followed by the tracking actuator is detected by the pickup feed servo circuit 1 according to the signal from the tracking error detection unit 4.
5 operates to move the pickup 2 to a predetermined position by a motor by a pickup transfer mechanism (not shown).

The focus error detection unit 6 detects from the output signal of the pickup 2 whether the focus position of the reading beam is above or below the information recording surface of the disk 1, and the positive and negative analog signals corresponding to each are detected. Is output to the zero-cross detection unit 10 and the terminal X of the switch SW3.
If the focus position of the reading beam is on the recording surface of the disc, the output signal of the focus error detector 6 is zero. If the output signal of the focus error detection unit 6 is 0, the zero-cross detection unit 10 outputs an “H” signal to the sub control unit 131. From the output of the zero-cross detector 10, the sub controller 131 can determine whether or not the focus position of the reading beam of the pickup 2 is on the recording surface of the disc.

The scan signal generator 8 includes a sub controller 13
In response to the signal from 1, positive and negative analog signals are output to the terminal Y of the switch SW3. The switch SW3 connects the focus servo circuit 7 to one of the terminal X and the terminal Y in response to a signal from the sub control unit 131. The focus servo circuit 7 has a focusing actuator (not shown) provided with the objective lens (not shown) of the pickup 2 in the pickup 2 according to the output signal of the focus error detector 6 or the scan signal generator connected through the switch SW3. Up and down.

Here, if the switch SW3 is connected to the X side, the focus servo circuit 7 responds to the focus detection section 6 to perform negative feedback control so that the focus of the reading beam is on the recording surface of the disk 1. Will be done. The disc signal level detector 11 shapes the signal from the pickup 2 and inputs it to the controller 13. The disk rotation servo circuit 9 controls the rotation speed of the motor M so that the frequency of the internal reference signal and the frequency of the synchronization signal included in the output signal of the pickup 2 match.
There are four operating states: a kick-up operation for driving the motor M at a predetermined rotation speed at the start of reproduction, a brake operation for driving in the opposite direction to the rotation to forcibly stop the rotation, and a non-operation. The operation state is switched by the sub control unit 131.

The signal conversion circuit 12 performs processing such as error correction and EFM demodulation on the signal from the pickup 2 to convert it into a digital audio signal, and outputs it to an analog system circuit via a digital-analog converter (not shown). , A sub-code, which is control data recorded by being mixed with the digital audio signal, is extracted and output to the control unit 13. The subcode includes the address of the digital audio signal and the like.

The signal conversion circuit 12 outputs an error signal to the control unit 13 when the extracted subcode is abnormal due to a scratch on the disk 1 or the like. Disc reproducing apparatus 100
Consists of the above. The control unit 13 in the present embodiment further performs control for surely searching for data, searches for data at the start position of the program area, and then jumps one track or a few tracks from the data to the inner circumference. The linear velocity of the disk is calculated based on a timer that measures the time until the data is searched again and the time measured by the timer.

Next, the operation of this embodiment will be described. FIG. 2 is a flowchart showing the processing operation of the control unit 13 according to the first embodiment of the present invention. First, the disc reproducing apparatus 10
When the disk 1 is loaded into the disk 0, the spindle motor M
Is rotated, and the TOC (Table 1) which is data such as the number and time information of each music stored in the disc 1 recorded in the lead-in area which is the innermost circumference of the disc by the pickup 2 is rotated.
e of Contents) is read, and the control unit 1
Data is input to 3 (step a1).

Then, the pickup 2 searches for the start position (hereinafter referred to as data block 1) of the spiral track-shaped program area recorded outside the lead-in area of the disk 1 (step a).
2) It is determined whether or not this data block 1 is detected (step a3). When the data block 1 is detected in step a3, the control unit 13 stores the data block 1, activates the timer, and starts counting the rotation cycle T (step a4). Next, the control unit 13 causes the pickup 2 to jump K tracks (for example, K = 1) to the inner circumference, contrary to the reproduction direction of the disc 1 (from the inner circumference to the outer circumference), and again at the reproduction speed from the inner circumference to the outer circumference. Tracing is started (step a5), and it is determined whether the pickup 2 has detected the data block 1 stored in the control unit 13 again (step a6). When the data block 1 is detected in step a6, the timer of the control unit 13 stops counting (step a7), and from the counted rotation period T and the radius r from the center of the disk 1 to the data block 1, The linear velocity v _L is calculated by the following equation (Equation 12) (step a8). However, ω is the rotational angular velocity.

V _L = ωr = 2πr · K / T (12) Then, based on the linear velocity v _L of the disk thus calculated, the number of tracks is calculated by the formula (10) described in the above-mentioned conventional technique. Find N. As described above, according to the first embodiment of the present invention, parts such as an optical element for detecting the linear velocity of the disk are unnecessary, which is advantageous in cost.

FIG. 3 is a flow chart showing the processing operation of the control unit 13 according to the second embodiment of the present invention. Similar to the first embodiment, the disc 1 is placed in the disc reproducing apparatus 100.
Is loaded, the spindle motor M rotates, and the pickup 2 reads the TOC, which is the data such as the number and time information of each music stored in the disc 1 recorded in the innermost lead-in area of the disc. , Data is input to the control unit 13 (step b1).

Then, after the number of repetitions for repeatedly counting the rotation cycle T _n is set as m times (step b2), n = 1 is set and the count of the first rotation cycle T _n is set. (Step b3). Next, similarly to the previous embodiment, the pickup 2 searches the data block 1 (step b4) and determines whether or not the data block 1 is detected (step b5). If the data block 1 is detected in step b5, the control unit 1
3 stores this data block 1, activates a timer, and starts counting the rotation period T _n (step b).
6). Next, the control unit 13 moves the pickup 2 to the inner track by K tracks (for example, K =
1) A jump is made and tracing is again started from the inner circumference to the outer circumference at the reproduction speed (step b7), and it is judged whether or not the pickup 2 has again detected the data block 1 stored in the control unit 13 (step b8). ). When the data block 1 is detected in step b8, the timer of the control unit 13 stops counting the rotation cycle T _n (step b9). Then, it is determined whether or not the count repetition number m set in step b2 and the current repetition number n match (step b10), and when the set repetition number m does not match the current repetition number n, At step b11, 1 is added to the value of the current number of iterations n (n = n
+1), the process returns to step b4, and the processes from step b4 to step b10 are repeated. On the other hand, when they match in step b10, the average value of T _n repeatedly counted m times is calculated as

[0031]

[Equation 2]

It is calculated by the equation (13), and this value is used as the value of the rotation cycle T (step b12). Then, the control unit 13
From this rotation cycle T and the radius r from the center of the disk 1 to the data block 1 which is the program area start position,
The disk linear velocity v _L is calculated in the same manner as the equation (12) (step b13). Further, as in the first embodiment, the number of tracks N is calculated by the equation (10).

As described above, according to the second embodiment of the present invention, in addition to the effect of the first embodiment, the value of the rotation period T is an average value of a plurality of times counted,
It is possible to improve the accuracy of the rotation cycle T and the disk linear velocity v _L thereby.

[0034]

As described above, according to the present invention, parts such as an optical element for detecting the linear velocity of the disk are unnecessary, so that the cost can be reduced and the assembling can be performed easily. Further, by counting the rotation cycle T a plurality of times, it is possible to improve the accuracy of detecting the linear velocity of the disk.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a processing operation of a control unit 13 according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing a processing operation of a control unit 13 according to the second embodiment of the present invention.

FIG. 4 is a simplified diagram of a disc.

FIG. 5 is a block diagram showing a configuration of a conventional disc linear velocity detection method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Disc 2 ... Pickup 12 ... Signal conversion circuit 13 ... Control unit 131 ... Sub control unit M ... Spindle motor 100 ... Disc playback device

Claims (2)

[Claims] 1. A disk having spiral tracks on which information is recorded is rotated so that the linear velocity of the tracks is constant, and the information reading position of an information reading head is controlled so as to follow the tracks. In a disc reproducing apparatus for reading information from the track, a track jump means for moving the information reading position of the information reading head backward from a predetermined track position by a predetermined number of tracks, and an information reading position moved by the track jump means. After that, the time measuring means for measuring the time until the information reading position reaches the predetermined track position again following the track, the time measured by the time measuring means, and the disk radius at the predetermined track position, And a calculating means for calculating the linear velocity of the disk. Disc playback device. 2. The disc linear velocity detecting method according to claim 1, wherein the track jump means repeats a process of moving the information reading position backward from a predetermined track position by a predetermined number of tracks a plurality of times in a reproduction direction. The time measuring means measures the time each time the reading position is moved by the track jump means, and the calculating means measures the line of the disk according to the time measured each time the reading position moves. A disc reproducing apparatus, wherein a plurality of velocities are calculated and an average value of the plurality of linear velocities is used as a linear velocity of the disc.