JPH04372739A - Information recording disk, tracking sensitivity measuring instrument and tracking controller - Google Patents

Abstract

PURPOSE:To attain the recording and reproduction of exact information by recording tracking sensitivity information in a disk as one piece of TOC information and reading the TOC information in order to control a suitable tracking. CONSTITUTION:A CPU 7 decides whether or not the information concerning to the gain of a tracking servo is present in the read TOC information. When the gain information of the tracking servo is not present, the tracking sensitivity is measured at the inner periphery and outer periphery of a disk 1, and the information of the tracking sensitivity obtained after the measurement is recorded in the disk 1 as the TOC information. That is, the CPU 7 moves a head 2 through a servo circuit 4 to the prescribed position of the inner periphery of the disk 1. Then, the tracking servo is turned OFF at the position, so that the optical tracking can be controlled, and the recording or reproduction of the exact information can be operated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording disk such as a compact disk or an optical disk, and a tracking sensitivity measuring device and a tracking control device thereof.

0002

2. Description of the Related Art Conventionally, when measuring the tracking sensitivity of a compact disk, for example, a head is caused to cross a track, and calculations are made from the peak value of the tracking signal obtained at that time. That is, as shown in FIG.
The value obtained by dividing the difference (amplitude) V1 between the positive peak and negative peak of the tracking error signal at the time of track crossing by the level V2 at the mirror surface portion was measured as the tracking sensitivity. When the tracking sensitivity is equal to or higher than a predetermined reference value, the disc is determined to be an acceptable product.

0003

[Problems to be Solved by the Invention] Conventional devices have been designed to measure tracking sensitivity from the amplitude of the tracking error signal at the time of track crossing, and therefore have had the problem of not being able to accurately measure tracking sensitivity. Ta.

The present invention has been made in view of the above situation, and it is an object of the present invention to more accurately measure tracking sensitivity and to perform correspondingly more accurate tracking control.

[0005]

The information recording disk according to the first aspect is characterized in that tracking sensitivity information corresponding to the radial position is recorded as one of the TOC information.

[0006] The tracking sensitivity measuring device according to claim 2 includes: a measuring means for measuring the tracking sensitivity when the information recording disk is loaded; and a recording means for recording the tracking sensitivity on the information recording disk as TOC information. It is characterized by having the following.

[0007] This measuring means is constituted by a tracking sensitivity measuring circuit 6 in the embodiment. Further, the recording means is constituted by the head 2.

A tracking sensitivity measuring device according to a third aspect of the present invention includes: a control means for controlling the head to cross the track of the information recording disk; and a measuring means for measuring the slope of the tracking error signal obtained at that time at zero cross. It is characterized by having the following.

In the embodiment, the control means is constituted by a servo circuit 4, and the measuring means is constituted by a tracking sensitivity measuring circuit 6.

[0010] The tracking control device according to claim 4 includes a measuring means for measuring the tracking sensitivity at a predetermined radial position of the information recording disk, a storage means for storing the tracking sensitivity, and a storage means corresponding to the stored tracking sensitivity. and a control means for performing tracking control.

In the embodiment, this measuring means is constituted by a tracking sensitivity measuring circuit 6, and the storing means is comprised of a tracking sensitivity measuring circuit 6.
The control means is constituted by a servo circuit 4.

0012

In the information recording disk according to the first aspect, tracking sensitivity information is recorded as one of the TOC information. Therefore, it becomes possible to read the TOC information and perform appropriate tracking control.

In the tracking sensitivity measuring device according to the second aspect of the present invention, when a disk is loaded, its tracking sensitivity is measured, and the measured tracking sensitivity is recorded on the disk as TOC information. Therefore, it becomes possible to perform correct tracking control without measuring the tracking sensitivity each time in the disc playback device.

In the tracking sensitivity measuring device according to the third aspect of the present invention, the tracking sensitivity is measured from the slope at zero crossing of the tracking error signal obtained when the head crosses the track of the disk. Therefore,
This makes it possible to measure tracking sensitivity more accurately.

In the tracking control device according to the fourth aspect of the present invention, tracking sensitivity is measured at the time of disk loading, and the measured tracking sensitivity is stored in the storage means. Tracking control is performed in accordance with the stored tracking sensitivity. Therefore, even if the tracking sensitivity is not recorded on the disc, it is possible to perform appropriate tracking control.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the configuration of an embodiment of a tracking sensitivity measuring device according to the present invention. Concentric circles (
Information is optically recorded or reproduced by a head 2 on an information recording disk 1 having a track (or a spiral shape). The head 2 is driven by a tracking actuator 3 controlled by a servo circuit 4, and its tracking position is adjusted.

The head amplifier 5 amplifies the signal output from the head 2 and outputs it to the tracking sensitivity measurement circuit 6 and address detection circuit 8. Or again, CPU7
The recording signal supplied from the head 2 is amplified and supplied to the head 2. Tracking sensitivity measurement circuit 6 and address detection circuit 8
supplies its output to the CPU 7. RAM9 is
It stores the data supplied from the CPU 7 and also supplies the stored data to the CPU 7. The sensor 10 detects loading of the disc 1.

The tracking sensitivity measuring circuit 6 is constructed as shown in FIG. In this embodiment, a zero-crossing detection circuit 21 detects a zero-crossing of the output of the head amplifier 5, a counter 22 starts and stops counting a predetermined clock in response to the output, and a counter 22 detects the zero-crossing of the output of the head amplifier 5. a sampling circuit 23 that samples in synchronization with a predetermined clock;
RAM 24 that stores data sampled by
and a level difference detection circuit 29 that detects a level difference between two predetermined timings read from the RAM 24. The RAM 24 includes timing pulse generation circuits 25 and 27 that generate timing pulses at the first and second sampling times as circuits for generating timing signals at two timings;
Address generators 26 and 28 are attached to generate addresses when the timing pulses are generated.

Next, the operation will be explained with reference to the flowchart shown in FIG. The CPU 7 first determines whether a disc has been loaded in step S1. That is, the CPU 7 monitors the output of the sensor 10, and when the sensor 10 detects loading of the disk 1, the process proceeds to step S2. In step S2, disk 1
Read the TOC information recorded in the . That is, the CPU
7 moves the head 2 to the innermost track of the disk 1 via the servo circuit 4, and reads the TOC recorded there.
Make the information read. This TOC information is input to the CPU 7 via the head amplifier 5.

Next, the CPU 7 determines whether or not the TOC information read in step S3 includes information regarding the gain of the tracking servo. If this tracking servo gain information does not exist, the process proceeds to step S4, where the tracking sensitivity is measured at the inner and outer circumferences of the disk 1, and the tracking sensitivity information obtained as a result of the measurement is recorded on the disk 1 as TOC information.

That is, the CPU 7 moves the head 2 to a predetermined position on the inner circumference of the disk 1 via the servo circuit 4. Then, the tracking servo is turned off at that position. As a result, the trajectory of the laser beam irradiated onto the disk 1 from the head 2 on the disk 1 becomes as shown in FIG. That is, since the disk 1 is normally rotated eccentrically with respect to the track T, the trace locus B of the light beam crosses the track T. As a result, a signal as shown in FIG. 5 is obtained as a tracking error signal. This tracking error signal is supplied to the tracking sensitivity measurement circuit 6, where the tracking sensitivity is measured.

That is, in the tracking sensitivity measuring circuit 6, its zero cross detection circuit 21 detects the zero cross of the tracking error signal supplied from the head amplifier 5. For example, as shown in FIG. 6, the zero cross detection circuit 21 detects at each zero cross timing when the tracking error signal changes from negative to positive and from positive to negative.
The detection pulse is output to the counter 22. The counter 22 starts counting a predetermined clock when a detection pulse is input from the zero-cross detection circuit 21, and repeats the operation of continuing counting until the next detection pulse is input from the zero-cross detection circuit 21. As a result, Figure 6
The interval times T1 and T2 between the two zero crossing points in
is detected. These times T1 and T2 are supplied to the CPU 7.

On the other hand, the sampling circuit 23 samples the tracking error signal supplied from the head amplifier 5 at a predetermined clock, and supplies the sampled data to the RAM 24 (which may also be a shift register).
Make me remember. As a result, data at each sampling time of the tracking error signal is stored in the RAM 24.

The counter 22 outputs a signal to the timing pulse generation circuits 25 and 27 at the switching time t, which is measured at times T1 and T2 in FIG. The timing pulse generation circuit 25 generates a timing pulse at a timing Δt/2 before time t, and outputs it to the address generator 26. The address generator 26 generates an address for a time Δt/2 before time t, and outputs it to the RAM 24. This allows R.A.
Data at the address specified by the address generator 26 is read from M24 and supplied to the level difference detection circuit 29. Here, Δt is a predetermined time (for example, a time corresponding to one clock).

On the other hand, the timing pulse generation circuit 27
A timing pulse is generated at a timing Δt/2 after time t, and the address generator 28 generates an address at the time when this timing pulse is generated. The RAM 24 outputs data corresponding to the address supplied from the address generator 28, and outputs data corresponding to the address supplied from the address generator 28.
supply to. The level difference detection circuit 29 calculates the difference (ΔZ) between data read from the RAM 24 at a timing Δt/2 before time t and data at a timing Δt/2 after time t, C.P.
Output to U7.

The CPU 7 calculates the speed v1 immediately before the time t and the speed v2 immediately after the time t from the following two equations. v1=(P/2)/t1 v2=(P/2)/t2

[0027] Here, P means track pitch.

Then, the average value v0 of these two speeds is determined from the following equation. v0=(v1+v2)/2

Then, the CPU 7 calculates the tracking sensitivity St from the following equation. St=ΔZ/(v0×Δt)

That is, the denominator in the above equation represents the displacement of the head 2 per unit time, and the numerator represents the level change of the tracking error signal when the displacement occurs. In other words, this results in correct tracking sensitivity being obtained.

As described above, when the tracking sensitivity measurement at a predetermined radial position is completed, the CPU 7 controls the servo circuit 4 to move the head 2 to the next measurement position (for example, a predetermined position on the outer periphery of the disk 1). Transfer to. Then, the same operation as described above is performed to measure the tracking sensitivity at that position. The tracking sensitivity measured at multiple positions in this way is
9 is temporarily stored. When the tracking sensitivity measurement is completed, the CPU 7 moves the head 2 via the servo circuit 4 to the TOC information writing position on the disk 1. Then, the tracking sensitivity information read from the RAM 9 (or data obtained by converting it into tracking servo gain information) is supplied to the head 2 via the head amplifier 5 and recorded as TOC information on the disk 1.

Next, returning to FIG. 3, in step S4,
When the tracking sensitivity measurement and writing are completed as described above, or when it is determined in step S3 that the servo gain information exists as TOC information, the process proceeds to step S5, and each of the disks 1 is stored in the RAM 9. Store the optimal tracking gain for the radial position (each zone). Then, in step S6, the radial position of the head 2 is detected. This detection is performed by the address detection circuit 8. That is, a reproduction signal reproduced from the disk 1 by the head 2 is supplied to the address detection circuit 8 via the head amplifier 5. The address detection circuit 8 reads address information from the input signal and outputs the reading result to the CPU 7.

When the radial position (address) of the head 2 is thus given, the CPU 7 then stores the tracking gain corresponding to the radial position in the RAM in step S7.
9 and causes the servo circuit 4 to set it. Thereby, the servo circuit 4 changes the tracking servo gain in accordance with the radial position of the head 2 according to the data supplied from the CPU 7. This process will be repeated until the end of the recording or reproducing operation is instructed in step S8.

The present invention can be applied to either the sample servo method or the continuous servo method.

[0035]

As described above, according to the information recording disk according to the first aspect, since the tracking sensitivity information is recorded as one of the TOC information, tracking servo can always be performed in an appropriate state. Therefore, accurate recording or reproduction of information becomes possible.

According to the tracking sensitivity measuring device according to the second aspect, when a disc is loaded, the measured tracking sensitivity is recorded as TOC information, so that the tracking sensitivity is checked each time the disc is loaded in the playback device. Appropriate tracking control can be performed without measurement.

According to the tracking sensitivity measuring device according to the third aspect, since the slope of the tracking error signal obtained when the head crosses the track at the time of zero crossing is measured, it is possible to measure the correct tracking sensitivity. become.

According to the tracking control device according to the fourth aspect, the tracking sensitivity is measured when the disc is loaded, and the measured tracking sensitivity is stored, so that even if the tracking sensitivity is not recorded on the disc, Even in this case, tracking control can always be performed in an appropriate state.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of a tracking sensitivity measuring device of the present invention.

FIG. 2 is a block diagram showing a more detailed configuration of the tracking sensitivity measurement circuit in FIG. 1;

FIG. 3 is a flowchart illustrating the operation of the embodiment of FIG. 1;

FIG. 4 is a diagram illustrating movement of a light beam during tracking sensitivity measurement.

FIG. 5 is a waveform diagram of a tracking error signal during tracking sensitivity measurement.

FIG. 6 is a diagram illustrating an operation when measuring tracking sensitivity in the embodiment of FIG. 2;

FIG. 7 is a diagram illustrating conventional measurement of tracking sensitivity.

[Explanation of symbols]

1 Disk 2 Head 3 Tracking actuator 5 Head amplifier 6 Tracking sensitivity measurement circuit 7 CPU 8 Address detection circuit 9 RAM 21 Zero cross detection circuit 22 Counter 23 Sampling circuit 24 RAM 25, 27 Timing pulse generation circuit 26, 28
Address generator 29 Level difference detection circuit

Claims (4)

[Claims] Claim 1: An information recording disk having tracks on which information is recorded concentrically or spirally, wherein tracking sensitivity information corresponding to the radial position is TO
An information recording disc characterized in that information is recorded as one of C information. 2. When an information recording disk is loaded, a measuring means for measuring tracking sensitivity at a predetermined radial position of the information recording disk, and a tracking sensitivity measured by the measuring means being stored in the information recording disk as TOC information. A tracking sensitivity measuring device comprising a recording means for recording. 3. A tracking sensitivity measuring device for measuring tracking sensitivity of an information recording disk, comprising: a control means for controlling a head for recording or reproducing information on the information recording disk so as to cross tracks of the information recording disk; A tracking sensitivity measuring device comprising: measuring means for measuring the slope at zero crossing of a tracking error signal obtained when the head crosses a track of the information recording disk. 4. Measuring means for measuring tracking sensitivity at a predetermined radial position of the information recording disk when the information recording disk is loaded; storage means for storing the tracking sensitivity measured by the measuring means; A tracking control device comprising: control means for performing tracking control in accordance with tracking sensitivity stored in the means.