JPH06259901A - Device for controlling accessing to objective track for pick-up - Google Patents

Abstract

PURPOSE:To prevent the runaway of a linear motor by correcting a noise eliminating characteristic when an erroneous speed detection is decided by an erroneous speed detection deciding means even when the noise eliminating characteristics is switched in accordance with the detected speed of a speed detection means. CONSTITUTION:A noise component is eliminated from a tracking error signal A by a noise elimination circuit 91 and sent to a speed detection circuit 13 (not shown in the figure). The moving speed of the pick-up at the time of accessing is detected by the circuit 13 and the noise eliminating is detected by the circuit 13 and the noise eliminating characteristics of the circuit 91 is switched by a noise eliminating characteristics switching circuit 200. When the generation of disturbance by the erroneous speed detection deciding circuit 100 is detected by the output C of the circuit 91, the erroneous switching of the circuit 91 is corrected by its output F. Thus, even when disturbance is generated by damage, dust, etc., and moving speed is erroneously detected by the circuit 13 and the circuit 91 is switched to an erroneous characteristics, erroneous switching can be corrected and runaway of the linear motor is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording / reproducing pickup in an optical disk device or the like, with an arbitrary desired track among a large number of information recording / reproducing tracks formed on the disk surface as a target track. The present invention relates to a device for controlling access to a target track of a pickup when the target track is moved across the other tracks and accessed.

[0002]

2. Description of the Related Art In recent years, an optical or magneto-optical signal recording / reproducing apparatus has been developed as an optical disk apparatus or the like. These devices are mounted on an optical disc that is an information carrier.
A light beam generated from a light source such as a semiconductor laser is convergently irradiated by a converging lens, and a signal is recorded by the intensity of the light beam. On the other hand, at the time of reproduction, the irradiation light amount of the light beam is set to a relatively weak constant value, and the reflected light from the optical disk is read by the photoelectric conversion element and converted into an electric signal.

A servo signal for performing focus control and tracking control is also obtained from reflected light from the optical disk. The focus servo is control of the position of the converging lens so that the light beam always keeps the converged state on the recording film surface of the optical disc, and the tracking servo is
This is a control for the light beam to always follow the track.

In order to record and reproduce information (data) on a track at an arbitrary desired position on the optical disk, control for moving a light beam to a desired track, that is, so-called track Access control is required. At the time of access control, the tracking servo is turned off, the pickup equipped with the light source is moved in the direction crossing the track by the linear motor, and when the light beam reaches the target address (target track), the tracking servo is turned on again. Turn on to make the pickup follow the target track.

In order to access at high speed and stably,
During the access operation, the speed of the linear motor is controlled so that the light beam moves at a substantially predetermined speed. The speed control is to detect the moving speed of the light beam with respect to the track from the period of the tracking error signal output from the tracking error detection means when the light beam crosses the track, and feed back this speed detection signal to the linear motor. It is done by.

Here, the tracking error detecting means originally detects the amount of positional deviation between the pickup and the pickup when the pickup follows the track, and outputs it as a tracking error signal. When the pickup is forcibly moved, the tracking error detecting means outputs a substantially sinusoidal waveform every time the pickup crosses one track, so that the moving speed of the light beam with respect to the track can be detected from the cycle. You can do it.

The tracking error signal obtained when the light beam crosses the track is a sinusoidal signal as described above. However, if the disk surface is scratched or damaged, the track address or the like will be affected. The period of the obtained tracking error signal (sinusoidal signal) is disturbed by the influence of the preformatted portion on the recorded disc surface or the disturbance such as noise.

The relative speed between the light beam and the track during access is about 1 m / s at the maximum, and the frequency of the sinusoidal tracking error signal is about 600 KHz. Therefore, the frequency of the tracking error signal at the time of access is DC to 6
Since it changes over a very wide range of 00 KHz, a noise component (a component caused by a disturbance such as the aforementioned scratch) contained in the tracking error signal is passed by passing the tracking error signal through a noise removal circuit having a single characteristic. Very difficult to remove.

Since the moving speed of the pickup (light beam) in the direction traversing the track at the time of access is detected by the period of the sinusoidal waveform included in the tracking error signal, if the above-mentioned disturbance occurs, Since the detection of the period of the sinusoidal waveform is disturbed and the detection of the moving speed is not correctly performed, the speed control is disturbed.
Also, the distance from the current position of the pickup to the target track is detected from the number of cycles of the sinusoidal tracking error signal, so if there is the above-mentioned disturbance, the detection of the number of cycles of the sinusoidal waveform will be disturbed and the target The access operation ends at a position deviated from the position.

As described above, the disturbance of the speed control may cause the linear motor to run out of control, and the access of the pickup to a desired track may be inaccurate, resulting in a significant decrease in the reliability of the access control device. . As described above, this is because the frequency of the tracking error signal when the pickup accesses the target track is DC to 60.
Since it changes over a wide range from 0 KHz, the noise component contained in the tracking error signal (the component caused by the above-mentioned external disturbance such as scratches) is removed by passing the tracking error signal through a noise removal circuit having a single characteristic. It is difficult to do.

Therefore, as one of means for solving such a problem, the characteristic of the noise removing circuit is changed according to the speed detection result when the pickup accesses the target track, that is, the speed at the time of access is By switching the removal characteristics of the noise removal circuit between the high speed and the low speed, it is possible to sufficiently remove the noise component (the component caused by the disturbance such as the aforementioned scratch) included in the tracking error signal. The proposed method is proposed.

FIG. 11 is a block diagram showing the structure of a conventional access control device according to the above-mentioned proposal. Less than,
It will be described with reference to FIG.

In FIG. 11, the optical disk 1 is rotated by a spindle motor 2 at a predetermined rotation speed. The pickup 3 is composed of a semiconductor laser 30 and the like,
Information is recorded or reproduced by irradiating a light beam on the information track formed on the optical disc 1.

The light beam emitted from the semiconductor laser 30, which serves as a light source, is collimated by the collimator lens 31 and then collected on the optical disk 1 through the polarization beam splitter 32, the quarter-wave plate 33, and the objective lens 34. Be illuminated. The reflected light from the optical disc 1 passes through the quarter-wave plate 33, is reflected by the polarization beam splitter 32, and enters the two-divided light receiving element 36 which is a photoelectric conversion element.

A current proportional to the intensity of incident light is output from the two-division light receiving element 36, and current-voltage conversion circuits 37, 38 are output.
Is converted into a voltage signal. The subtraction circuit 5 subtracts between the outputs of the current-voltage conversion circuits 37 and 38, and outputs it as a tracking error signal to the tracking control circuit 7 and the cross track detection circuit 9.

In the tracking control circuit 7, in the tracking mode, the tracking actuator 35 is driven based on the tracking error signal by the mode switching signal (J) from the control mode switching circuit 17 so that the light beam follows the desired track. . The output of the tracking control circuit 7 is also input to the linear motor control circuit 8, and the mode switching signal (J) from the control mode switching circuit 17 causes the linear control based on the output of the tracking control circuit 7 in the tracking mode. The motor 4 is driven to cause the light beam to follow a desired track.

Next, the operation of accessing the desired track on the surface of the disc 1 of the pickup 3 will be described. In FIG. 11, the outputs of the current-voltage conversion circuits 37 and 38 are summed in the adder circuit and output to the address reproduction circuit 10 as a reproduction signal. The address reproducing circuit 10 reproduces the address of the track recorded in the pre-formatted portion of the optical disc 1. Further, the address of the desired target track is input to the address input circuit 11.

The microcomputer 12 transfers the address N1 of the reproduction track currently being reproduced by the pickup 3 from the address reproduction circuit 10 to the address input circuit 12.
Then, the address N0 of the desired target track is read out, and the difference (N0-N1) between the two is calculated and output to the track count circuit 14.

Further, by outputting an access start signal from the microcomputer 12 to the control mode switching circuit 17, the mode switching circuit 17 outputs a mode switching signal (J) indicating that the access is in progress to the tracking control circuit 7 and the linear controller. It is output to the motor control circuit 8.

By the mode switching signal (J), the tracking control circuit 7 and the linear motor control circuit 8 are
Switch to access mode. In the access mode, the tracking control circuit 7 suppresses the vibration of the objective lens 34 by driving the tracking actuator 35 based on the output of the objective lens position sensor 39 that detects the radial position of the objective lens 34.

Further, the linear motor control circuit 8 drives the linear motor 4 based on the speed error signal from the subtraction circuit 16 so that the relative speed between the light beam and the track follows a predetermined target speed. Control is provided to move the light beam across the track toward the target track.

When the light beam moves and crosses the track, a sinusoidal tracking error signal whose track pitch is one cycle is output from the subtraction circuit 5. This tracking error signal (A) is applied to the cross track detection circuit 9
Entered in. The cross track detection circuit 9 includes a binarization circuit 90 and a noise removal circuit 91.

In the binarization circuit 90, the input tracking error signal (A) is converted into a binary digital signal of "H" level and "L" level. The output of the binarization circuit 90 contains a disturbance component due to the pre-format section or the like. The noise removing circuit 91 removes a pulse having a predetermined time width from the output of the binarizing circuit 90 based on the speed determination signal (D) from the speed detecting circuit 13 as the above-mentioned disturbance component, and removes the pulse. The latter signal is sent to the speed detection circuit 13
And to the track count circuit 14.

In the speed detecting circuit 13, the noise removing circuit 9
The moving speed of the light beam with respect to the track is detected from the cycle of the pulse (sine wave) from 1 and is output to the subtraction circuit 16 as a speed signal. Further, it is determined whether or not the detected speed is equal to or higher than a predetermined speed, and the result is output as a speed determination signal (D). Here, for simplification, a signal of "H" level when the speed is equal to or higher than a predetermined speed Vr, and an "L" level signal when the speed is equal to or lower than Vr is output to the noise removal circuit 91 as a speed determination signal (D). I shall.

Here, the operation of the noise removing circuit 91 will be described. The relative speed between the light beam and the track is Vr,
When the track interval is P, the time Wr required for the light beam to traverse one track is represented by Wr = P / Vr (Equation 1), and the output of the binarization circuit 90 is about Wr / 2. Pulse signals of "H" level and "L" level of the time width are generated.

Therefore, when the relative velocity between the light beam and the track is Vr or less, that is, when the velocity discrimination signal (D) is at "L" level, the time width of the pulse output from the binarization circuit is W.
A pulse having a time width of r / 2 or more and Wr / 2 or less is
It can be determined that the pulse is an extra pulse (noise component) generated by a disturbance in the pre-format section or the like.

The maximum speed at the time of access is Vm,
At this time, the time Wm required for the light beam to traverse one track is expressed by Wm = P / Vm (Equation 2), and the output of the binarization circuit 90 is "H" with a time width of about Wm / 2. A pulse signal of level "L" will be generated.

Therefore, in the range where the relative velocity between the light beam and the track is Vr or more and Vm or less, that is, when the velocity discrimination signal (D) is at "H" level, the time width of the pulse output from the binarization circuit 90 is A pulse having a time width of Wm / 2 or more and Wm / 2 or less can be determined to be an extra pulse (noise component) generated by disturbance in the pre-format section or the like.

Therefore, for example, the speed discrimination signal (D) is "
At the L "level, pulses with a time width of Wr / 4 or less are removed as noise components, and the speed determination signal is" H ".
At the level, by removing the pulse having the time width of Wm / 4 or less as the noise component, the component due to the disturbance in the pre-format portion or the like can be removed.

When the pulses having a time width of Wr / 2, Wm / 2 or less are removed, the relative speed between the light beam and the track changes due to speed fluctuations near Vr and Vm.
Since there is a risk of removing correct pulses other than extra pulses due to disturbance, pulses with a time width of Wr / 4 and Wm / 4 or less are removed here.

In the track count circuit 14, each time a pulse is input from the noise removal circuit 91, the counter value is down-counted, and this count value is output to the speed command circuit 15 and the control mode switching circuit 17. The speed command circuit 15 generates a predetermined reference speed signal according to the distance from the output of the track count circuit 14 to the target track, and outputs it to the subtraction circuit 16.

The subtraction circuit 16 subtracts between the speed signal input from the speed detection circuit 13 and the reference speed signal input from the speed command circuit 15, and outputs it as a speed error signal to the linear motor control circuit 8. . In the linear motor control circuit 8, the linear motor 4 is driven based on this speed error signal.
By controlling the relative velocity of the light beam and the track.

In the control mode switching circuit 17, when the count value of the track count circuit 14 reaches 0, that is, when the target track is reached, a mode switching signal (J) for switching from the access mode to the track following mode is sent to the tracking control circuit 7 and the linear control circuit. Output to the motor control circuit 8. By this mode switching signal (J), the tracking control circuit 7 and the linear motor control circuit 8 are switched to the track following mode, control is performed so that the light beam follows the desired track, and the access operation is completed. It will be.

As related documents describing this type of apparatus, for example, Japanese Patent Application Laid-Open No. 2-98878 and Japanese Patent Application Laid-Open No.
No. 232582, etc. can be mentioned.

[0035]

However, the above-mentioned prior art has the following problems. This problem will be described with reference to FIG. 12
FIG. 12 is a waveform diagram showing signals of various parts in the circuit of FIG. 11.

In FIG. 12, (A) is a tracking error signal (output of the subtraction circuit 5), and (B) is a binarization circuit 90.
, (C) is the output of the noise removal circuit 91, and (D) is the speed determination signal from the speed detection circuit 13. Signals (A) to (D) in FIG. 12 indicate a case where the relative speed between the light beam and the track is 2 Vr or more in the access mode.

Since the tracking error signal (A) is disturbed as shown in FIG. 12 due to scratches and dust on the pre-format section and the disk, an extra pulse is added to the output (B) of the binarization circuit. Occurrence and omission of (noise component) occur.

Here, pulse widths t2, t3, t5, t6
Is t2, t3, t5, t6 <(Wm / 4) (Equation 3), and the pulse widths t1 and t4 are

T1, t4> (Wm / 4) (Equation 4), and the pulse widths t7, t8 are

It is assumed that t7, t8> Wr (Equation 5) and that the pulse width t9 is t9 <(Wr / 4) (Equation 6).

In the noise removing circuit 91 of FIG. 11, the binarizing circuit 9 is provided during the period when the speed discrimination signal (D) is at "H" level.
Since the pulse having the time width of Wm / 4 or less is removed from the output (B) of 0 as a noise component, the time width of the pre-format portion is short, that is, the time widths t2 and t.
Each pulse of 3, t5 and t6 is removed.

On the other hand, a disturbance due to scratches, dust, etc. occurs, and 2
When a pulse having a period of time width Wr or more is detected a plurality of times (here, twice) in the output (B) of the binarization circuit 90,
The speed detection circuit 13 erroneously determines from the cycle that the relative speed between the light beam and the track has become Vr or less, and instead of the "H" level speed determination signal up to that point, "L" level speed determination. The signal (D) is output.

When the speed discriminating signal (D) becomes "L" level, the noise removing circuit 91 operates so as to remove a pulse of Wr / 4 or less as a noise component. When the relative speed is 2 Vr or more, the time width of the pulse output from the binarization circuit 90 is Wr / 4 or less, so the time width t
The pulse of 9 will be removed as a noise component.

Therefore, all the normal pulses after the disturbance caused by scratches, dust, etc. are erroneously recognized as noise components and are removed. Since the speed detecting circuit 13 detects the speed from the output of the noise removing circuit 91, it outputs a low speed signal and controls the speed of the linear motor 4 based on this speed signal. You will be out of control.

As described above, in the conventional access control device as shown in FIG. 11, the relative speed of the light beam and the track is detected by the output of the noise removing circuit 91, and the detection result of the noise removing circuit 91 is detected. Since the feedback loop is configured to change the noise removal characteristic, once the disturbance due to scratches, dust, etc. occurs and the speed detection circuit 13 erroneously determines that the speed is slow, the noise removal circuit 91 A normal signal is also removed as a noise component, which causes a problem that the linear motor 4 runs out of control.

Therefore, the problem to be solved by the present invention is that the speed discrimination signal of the relative speed of the light beam and the track at the time of access is output in an erroneous state due to the above problem, that is, scratches and dust on the disk. It can be said that the problem that the normal binary signal (pulse) is removed by the noise removing circuit thereafter is solved.

Therefore, an object of the present invention is to solve such a problem and to output the speed discrimination signal of the relative speed of the light beam and the track at the time of access in an erroneous state due to scratches or dust on the disk. Even if the noise removal circuit does not remove normal binary signals (pulses), the access control device to the target track of the pickup is provided, which enables stable access operation. To do.

[0048]

To achieve the above object, according to the present invention, an information recording / reproducing medium such as an optical disc on which a track is formed, a pickup for recording or reproducing information on the medium, and a tracking error detecting means. And a moving means for forcibly moving the pickup in the direction crossing the track to access the target track,

When the pickup moves to a target track by the moving means, the output from the tracking error detecting means, which is output as a substantially sinusoidal waveform every time the pickup crosses one track, is input and pulsed. A binarizing means for converting and outputting the binarized output;

An output of the binarizing means is input, a noise removing means for removing and outputting a noise component contained therein, and the pulsed binarized output after noise removal by the noise removing means. Track counting means for counting, calculating and outputting the number of remaining tracks up to the target track of the moving pickup,

Speed detection means for inputting the pulsed binarized output after noise removal by the noise removal means, detecting the crossing speed of the moving pickup with respect to the track from the pulse period, and outputting it. Control means for controlling the access operation of the pickup to the target track by the moving means based on the output of the track counting means and the output of the speed detecting means,

Further, the speed detected by the speed detecting means is set when the speed is high and reset when the speed is low, and the noise removing characteristic of the noise removing means is set to the moving speed of the pickup by the set output and the reset output. In the access control device to the target track of the pickup equipped with a set / reset means for switching according to

Speed erroneous detection determining means for determining whether or not the speed detecting means is erroneously detecting the speed due to a disturbance factor from the output of the binarizing means and the output of the noise removing means. When the speed error detection determination means determines that the speed error is being detected, the operation error added to the set / reset means is corrected because the speed detection means performs the speed error detection. And an erroneous operation correcting means for performing a correction operation for performing the correction operation based on the determination output of the determination means.

In the access control device, the remaining track number determining means for determining whether or not the number of remaining tracks output from the track counting means is equal to or more than a predetermined number of tracks,

When the speed detecting means erroneously detects the speed due to a disturbance factor, and if an erroneous operation is applied to the set / reset means, a correcting operation for correcting the erroneous operation is performed. And an erroneous operation correcting means for performing the determination output of the remaining track number determining means.

[0056]

As a result, due to scratches and dust on the disc (information recording / reproducing medium), the speed detecting means erroneously detects the speed, and the noise removing characteristic of the noise removing means is erroneously corrected. In addition, since the speed error detection determination means detects that the speed error has been detected, and the error correction of the noise removal characteristic is corrected by the detection output, the runaway of the linear motor, which has occurred conventionally, etc. Occurs, and stable access operation can be realized.

[0057]

EXAMPLES Examples of the present invention will be described below. Figure 1
It is a block diagram which shows the principal part of one Example of this invention. That is, it is a block diagram showing details of a cross track detection circuit portion (corresponding to 9 in FIG. 11) of an embodiment (access control device for a target track of a pickup) of the present invention. In other words, in FIG. 11, the cross track detecting circuit 9 shown in FIG.
By using A, the access control device as one embodiment of the present invention is realized.

The operating principle of the present invention will be briefly described with reference to FIGS. In FIG. 11, the noise removing circuit 9
1 is the output (B) of the binarization circuit 90 (at the time of access operation,
Each time the pickup crosses one track, the sine waveform (A) binarized output output from the subtraction circuit 5 as the tracking error detection means is taken in, and the noise component is removed from it (as C). As described above, it is passed to the speed detection circuit 13. At this time, the speed detection circuit 13 detects the moving speed of the pickup at the time of access from the output (the cycle of the sine waveform) of the binarization circuit 90, and the detection output (D) depends on whether the detected speed is high or low. It has also been described above that the noise removal characteristics of the noise removal circuit 91 are switched by outputting

Here, in the present invention, if there are scratches or dust on the disk, the speed detection circuit 13 erroneously detects the speed due to the effect, and as a result, an erroneous detection output (D) is output, and the noise removal circuit is output. Since the noise removal characteristic of 91 may be erroneously corrected, a speed error detection determination means for detecting that the speed detection circuit 13 has made an error in speed detection is provided, and the noise removal circuit 91 outputs the error detection determination output. The principle of operation is to correct the erroneous correction of the noise removal characteristics of. In FIG. 1, a speed error detection determination circuit (sometimes called a pulse removal detection circuit from its operation mode) 100 corresponds to the speed error detection determination means and corrects the noise removal characteristics of the noise removal circuit 91. The means are the output (F) from the comparison circuit 104 and the OR circuit 202. After roughly understanding the above, a detailed description will be given below step by step.

In FIG. 1, 100 is a speed error detection determination circuit (pulse removal detection circuit), and 200 is a removal characteristic switching circuit (for the noise removal circuit 91). The erroneous speed detection determination circuit (pulse removal detection circuit) 100 includes a rising edge detection circuit 101 that detects a rising edge of the output (C) of the noise removal circuit 91, a counter 102, and the number of times a pulse is continuously removed (speed error). Reference value 103 for setting detection criteria), output of counter 102 and reference value 10
It is composed of a comparison circuit 104 for comparing the three.

Further, the removal characteristic switching circuit 200 has a rising edge detection circuit 201 for detecting the rising edge of the speed discrimination signal (D) from the speed detection circuit 13 and an output (F) of the speed error detection circuit 100 and a rising edge. OR circuit 2 for calculating the logical sum of the outputs (G) of the edge detection circuit 201
02, the falling edge detection circuit 203 for detecting the falling edge of the speed discrimination signal (D), the output (H) of the falling edge detection circuit 203 and the control mode switching circuit 17
O that calculates the logical sum of the signals obtained by inverting the output (J) from
Outputs of R circuit 204 and OR circuit 202 and OR circuit 20
It is composed of an RS flip-flop 205 which is set / reset by the output of 4.

The circuit operation of the cross track detection circuit 9A shown in FIG. 1 will be described with reference to the waveform charts of the signals of the respective parts shown in FIG. FIG. 2 is a signal waveform diagram of each part showing the operation when the disturbance due to scratches or dust on the disc does not occur in the input signal (A) of the binarization circuit 90. In FIG. 2, the same signals as those shown in FIG. 1 are designated by the same reference numerals.

Please refer to FIG. 1 and FIG. In the follow-up mode in which the light beam follows a predetermined track instead of the access control mode, the control mode changeover circuit 17 inputs the control mode changeover signal (J) of "L" level to the removal characteristic changeover circuit 200. A signal obtained by inverting the control mode switching signal (J) is passed through the OR circuit 204 to R
Since it is input to the reset terminal of the −S flip-flop 205, the “L” level characteristic switching signal (I) is output from the RS flip-flop 205 to the noise removal circuit 91.

When the characteristic switching signal (I) is at "L" level, the noise removing circuit 91 determines that the relative speed between the light beam and the track is a speed equal to or lower than a predetermined speed Vr, and binarizes it. A pulse having a time width Wr / 4 or less is removed from the signal (B) input from the circuit 90.

Next, in FIG. 11, when a signal for instructing access start is input from the microcomputer 12 to the control mode switching circuit 17, the control mode switching signal (J) becomes "H" level and the access operation is started. To do. When the control mode switching signal (J) is switched to the “H” level, the output of the OR circuit 204 becomes the “L” level in FIG. 1, and the RS flip-flop 205.
Reset is released.

In the erroneous speed detection determination circuit 100, the edge detection circuit 101 detects the rising edge of the output (C) of the noise removal circuit 91 and outputs this detection signal (E) to the clear terminal CLR of the counter 102. ing. The output (B) of the binarization circuit 90 is the counter 102.
Is input to the clock terminal CLK. Counter 10
The count value of 2 is compared with the reference value 103 by the comparison circuit 104.
When the count value is equal to or larger than the reference value, a "H" level signal is output as a speed error detection determination output.

The noise removing circuit 9 is used when no disturbance due to scratches or dust occurs on the pre-format portion of the disk.
The output (C) of 1 is a signal obtained by delaying the output (B) of the binarization circuit 90 by the time required for the processing for removing the pulse having the predetermined time width or less. Therefore, the counter 10
The same number of pulses are input to the second clock terminal CLK and the clear terminal CLR, and the count value repeats 0 and 1,
It cannot be more than 2.

For example, 4 is set as the reference value 103, and in the comparison circuit 104, the reference value and the counter 102 are set.
Since the outputs of the two are compared, "L" is output from the comparison circuit 104.
The level signal (G) is output. At this time, the speed detection circuit 13 is supplied with the output (C) of the noise removal circuit 91 and detects the moving speed of the pickup (light beam).
Correctly detects the speed and never detects the speed incorrectly.

The speed detecting circuit 13 (FIG. 11) detects the relative speed (moving speed) between the light beam and the track from the period of the rising edge of the output (C) of the noise removing circuit 91, and for example, two times in succession. If the cycle becomes Wr or less, it is determined that the speed becomes Vr or more at that point, and the "H" level speed determination signal (D) is output (t1, t2 in FIG. 2). <Wr).

In FIG. 1, the rising edge detection circuit 2
In 01, the rising edge caused by the speed discrimination signal (D) becoming "H" level is detected, and the detection output is output to the OR circuit 202. The logical sum of the output (H) of the rising edge detection circuit 201 and the “L” level signal (F) output from the comparison circuit 104 is the OR circuit 202.
And the operation result is calculated by the RS flip-flop 2
05 set terminal.

As a result, the RS flip-flop 20
The characteristic switching signal (I) of “H” level is output from the signal 5 to the noise removing circuit 91. In the noise removing circuit 91,
When the characteristic switching signal (I) is at "H" level, it is determined that the relative speed between the light beam and the track is a speed equal to or higher than a predetermined speed Vr, and the signal (B ), Pulses having a time width of Wm / 4 or less are removed as noise components.

When the light beam approaches the target track, the linear motor 4 is decelerated so that the relative speed between the light beam and the track becomes smaller. In the speed detection circuit 13,
When the cycle of the rising edge of the output (C) of the noise removal circuit 91 is, for example, twice in succession and the cycle becomes Wr or more, it is determined that the speed becomes Vr or less, and the "L" level speed determination signal (D ) Is output (in FIG. 2, t3, t4>
Wr).

The falling edge detection circuit 203 detects the falling edge of the speed discrimination signal (D), and the OR circuit 2
Output to 04. The OR circuit 204 calculates the logical sum of the output (H) of the falling edge detection circuit 203 and the inverted signal of the control mode switching signal (J). The result of this calculation is input to the reset terminal of the RS flip-flop 205, and the characteristic switch signal (I) at the “L” level is output from the RS flip-flop 205 to the noise removal circuit 91. As a result, the noise removal circuit 91 operates so as to remove a pulse having a time width Wr / 4 or less from the signal (B) input from the binarization circuit 90 as a noise component.

The above is the operation when the disturbance due to scratches or dust does not occur, in other words, since the disturbance due to scratches or dust does not occur, the speed detection circuit 13 does not erroneously detect, and therefore the speed error detection determination circuit 100 also. , That is not detected, and as a result, the output of the speed error detection determination circuit 100 (F)
Is the circuit operation when there is no need to function.

Next, referring also to FIG. 3, the operation when a disturbance due to scratches or dust occurs, in other words, the disturbance due to scratches or dust occurs, and therefore the speed detection circuit 13 erroneously detects the speed, Therefore, the circuit operation in the case where the speed error detection determination circuit 100 also detects this, and as a result, the output (F) of the speed error detection determination circuit 100 functions will be described.

FIG. 3 is a signal waveform diagram of each part showing the operation when a disturbance due to a scratch or dust occurs when the relative velocity between the light beam and the track is 2 Vr or more.
In FIG. 3, since the tracking error signal (A) is disturbed as shown in the figure due to scratches and dust on the preformat section and the disk, an extra pulse (noise) is output to the output (B) of the binarization circuit 90. Ingredients) are generated and missing.

In the noise removing circuit 91, the speed detecting circuit 1
While the speed discrimination signal (D) from 3 is at "H" level,
Since the operation is performed so as to remove the pulse having the time width of Wm / 4 or less from the output (B) of the binarization circuit 90, the pulse having the short time width of the pre-format portion is removed.

Therefore, two or more pulses are output from the binarization circuit 90 between the rising edge and the rising edge of the output (C) of the noise removing circuit 91.
The number of pulses is counted by the counter 102 in the speed error detection determination circuit 100. The count value of the counter 102 is compared with the reference value 103 by the comparison circuit 104, and when the count value is larger than the reference value, the comparison circuit 104 outputs the comparison result of “H” level.

Here, the reference value 103 is set to a value larger than the count value of the counter 102 in the pre-format section (here, the reference value is 4), and the output of the comparison circuit 104 in the pre-format section is " The L "level signal is output. Next, the cycle of the output (C) of the noise removal circuit 91 becomes longer due to the disturbance due to scratches and dust, and the cycle of the rising edge is, for example, twice in succession, and when the cycle becomes Wr or more, the speed becomes The speed detection circuit 13 determines that the voltage is equal to or lower than Vr, and outputs the "L" level speed determination signal (D) (t1, t2> Wr in FIG. 3).

The falling edge detection circuit 203 detects the falling edge of the speed discrimination signal (D) from the speed detection circuit 13 and outputs it to the OR circuit 204. The OR circuit 204 calculates the logical sum of the output (H) of the falling edge detection circuit 203 and the signal obtained by inverting the control mode switching signal (J). This operation result is the RS flip-flop 2
The characteristic switching signal (I) at the “L” level is input to the reset terminal of 05 and output from the RS flip-flop 205 to the noise removing circuit 91.

As a result, in the noise removing circuit 91, the time width Wr / from the signal (B) input from the binarizing circuit 90 is calculated.
It operates to remove pulses of 4 or less. When the relative speed is 2 Vr or more, the time width of the pulse output from the binarization circuit 90 is Wr / 4 or less. Therefore, after the disturbance due to scratches or dust is generated, the noise removal circuit 91 up to the normal pulse width signal is generated. Will be removed.

In the rising edge detecting circuit 101 of the speed error detection judging circuit 100, the rising edge of the output (C) of the noise removing circuit 91 is not detected and the counter 102 is not cleared. Therefore, the counter 102 counts the number of pulses of the output (B) of the binarization circuit 90. The count value of the counter 102 is the reference value 103
When the above is reached, the comparison circuit 104 outputs an “H” level signal (F).

The output (F) of the comparison circuit 104 is ANDed with the output of the rising edge detection circuit 201 by the OR circuit 202. The result of this operation is input to the set terminal of the RS flip-flop, and the "H" level characteristic switching signal (I) is output to the noise removal circuit 91. As a result, the noise removal circuit 91 outputs a signal obtained by removing the pulse having the time width Wm / 4 or less from the signal (B) input from the binarization circuit 90.

When the rising edge detection signal of the output (C) of the noise removal circuit 91 is input from the edge detection circuit 101 to the clear terminal CLR of the counter 102, the counter 102 is cleared and the output of the comparison circuit 104 (F )But"
When the cycle of the rising edge of the output (C) of the noise removing circuit 91 becomes twice Wr or less consecutively, it is determined that the speed becomes Vr or more, and the speed becomes Vr or more. The detection circuit 13 outputs the "H" level speed determination signal (D) (set t3 and t4 <Wr in FIG. 3) The description of the circuit operation in FIG.

FIG. 4 is a block diagram showing a main part (cross-track detection circuit 9B) of another embodiment of the present invention. FIG. 4 is not a simple determination range of whether the relative velocity of the light beam with respect to the track is high or low.
This is an example in the case of being composed of a plurality of discrimination ranges, and here, the case of discriminating into five ranges is shown.

In FIG. 4, an erroneous speed detection determination circuit (pulse removal detection circuit) 100 detects a rising edge of the output (B) of the binarization circuit 90 after the noise removal of the output (B). Detection circuit 101, counter 10
2. A reference value 103 for setting the number of consecutive pulse removals as a reference for speed error detection determination, and a comparison circuit 104 for comparing the output of the counter 102 with the reference value 103.

Further, the removal characteristic switching circuit 200 is
-S flip-flop 206, counter 207, reference value 208, comparison circuit 209 for comparing the output of counter 207 and reference value 208, the output (K) of RS flip-flop 206 and the logical sum of speed discrimination signals D0 to D3 The OR circuits 210 to 213 for calculating

As for the speed discrimination signal, when the speed is Vr0 or higher, the speed discrimination signal D0 becomes the "H" level signal, when the speed is Vr1 or higher, the speed discrimination signal D1 becomes the "H" level signal, and when the speed is Vr2 or higher. The discrimination signal D2 becomes the "H" level signal, and the velocity discrimination signal D3 becomes the "H" level signal when the speed is Vr3 or higher.

In the noise removing circuit 91, the speed discrimination signals D0 to D3 are at "L" level (hereinafter D = "000").
In the case of "0"), pulses having a time width of Wr1 / 4 or less are removed from the output (B) of the binarization circuit 90, D0 is at "H" level, and D1 to D3 are at "L". In the case of a level (hereinafter referred to as D = “0001”), a pulse having a time width of Wr2 / 4 or less is removed from the output (B) of the binarization circuit 90, and D0 and D1 are at “H” level and D2. And D3
Is at the "L" level (hereinafter referred to as D = "0011"), pulses having a time width of Wr3 / 4 or less are removed from the output (B) of the binarization circuit 90,

D0 to D2 are "H" level, D3 is "H" level.
In the case of L "level (hereinafter referred to as D =" 0111 "), pulses having a time width of Wr4 / 4 or less are removed from the output (B) of the binarization circuit 90, and D0 to D3 are at" H "level. In the case of (hereinafter referred to as D = “1111”), it is assumed that the operation is performed so as to remove the pulse having the time width of Wm / 4 or less from the output (B) of the binarization circuit 90.

The circuit operation of the cross-track detection circuit 9B shown in FIG. 4 will be described with reference to the signal waveform chart of each part shown in FIG. In FIG. 5, the relative velocity between the light beam and the track is Vr4.
In the above case, it is a signal waveform diagram of each part showing the operation when a disturbance such as a scratch or dust occurs.

In FIG. 5, the tracking error signal (A) is caused by scratches and dust on the pre-format portion and the disc.
However, since it is disturbed as shown, the binarization circuit 90
The output (B) of 1 has an extra pulse (noise component) generated and missing. Since the noise removing circuit 91 operates so as to remove a pulse having a time width of Wm / 4 or less from the output (B) of the binarizing circuit 90 during the period of the speed discrimination signal D = “1111”, the pre-format The pulse with a short time width of the part is removed.

Therefore, two or more pulses are output from the binarizing circuit 90 between the rising edge and the rising edge of the output (C) of the noise removing circuit 91, and thus the number of pulses is counted by the counter 102. Is counted.
The count value of the counter 102 is compared with the reference value 103 by the comparison circuit 104, and when the count value is larger than the reference value, the comparison result of “H” level is output. Here, the reference value 103 is the counter 1 in the pre-format section.
It is set to a value larger than the count value of 02 (here, the reference value is set to 4), and the comparison circuit 1 is used in the pre-format section.
The output of 04 outputs an "L" level signal.

Next, the cycle of the output (C) of the noise removing circuit 91 becomes longer due to the disturbance due to scratches and dust, and the cycle of the rising edge is, for example, twice in succession. Is determined to be Vr3 or less, the speed detection circuit 13 outputs the speed determination signal D = "0011" (t1, t2> Wr3 in FIG. 5).

In the noise removing circuit 91, the binarizing circuit 90
From the signal (B) input from, the operation is performed so as to remove the pulse having the time width Wr3 / 4 or less, and after the disturbance due to scratches / dust is generated, the normal signal is also removed by the noise removal circuit 91.

The rising edge detection circuit 101 does not detect the rising edge of the output (C) of the noise removal circuit 91, and the counter 102 is not cleared. Therefore, the counter 102 counts the number of pulses output from the binarization circuit 90. The count value of the counter 102 is greater than or equal to the reference value 103 (here, the reference value 103 = 4
Then, the comparison circuit 104 outputs an “H” level signal.

The output of the comparison circuit 104 is input to the set terminal of the RS flip-flop 206, and the output (K) of the RS flip-flop 206 becomes "H" level. The output (K) of the RS flip-flop 206 is O
It is input to the R circuits 210 to 213, the logical sum is calculated with the speed discrimination signals D0 to D3, and the calculation result is output as the characteristic switching signals I0 to I3.

As a result, the characteristic switching signal (I) becomes "
1111 ″, and the noise removal circuit 91 operates so as to remove a pulse having a time width Wm / 4 or less from the signal (B) input from the binarization circuit 90. As a result, the output (B ), The normal signal from which the pulse having the time width Wm / 4 or less is removed is output from the noise removal circuit 91.

When the cycle of the falling edge of the output (C) of the noise removing circuit 91 becomes twice Wr4 or less consecutively, it is determined that the speed becomes Vr4 or more, and the speed detecting circuit 13 , And outputs the speed determination signal D = “1111” (set t3 and t4 <Wr4 in FIG. 5). In the count circuit 207, the output (C) of the noise removal circuit 91
When the counter value reaches or exceeds the reference value 208, the comparison circuit 209 outputs an "H" level signal.

From the output of the noise removing circuit 91,
The reference value 208 is set to be equal to or more than the number of pulses required for the speed detection circuit 13 to determine the speed. The output of the comparison circuit 209 is input to the reset terminal of the RS flip-flop 206, and the “L” level signal (K) is input from the RS flip-flop 206 to the OR circuits 210 to 213. As a result, the OR circuits 210 to 213 output the speed determination signal (D) as the characteristic switching signal (I). In addition, the counter 207 outputs a signal obtained by inverting the output (K) of the RS flip-flop 206 to the clear terminal CL.
Since it is input to R, the counter 207 is cleared.

FIG. 6 is a block diagram showing a main part (cross-track detection circuit 9C) of still another embodiment of the present invention. In FIG. 6, the same functional parts as those shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted unless necessary, in order to avoid duplication.

In FIG. 6, 300 is a remaining track number detection circuit (remaining until the target track is reached from the current position), and 200 is a removal characteristic switching circuit.
The remaining track number detection circuit 300 includes a noise removal circuit 91.
Reference value 301 for setting the number of remaining tracks, which represents the time when the characteristics of the above are switched, as a reference value, track count circuit 1
4 and the reference value 301.

The removal characteristic switching circuit 200 includes a rising edge detection circuit 201 for detecting a rising edge of the speed discrimination signal (D) from the speed detection circuit 13 and an output (L) of the remaining track number detection circuit 300. An OR circuit 214 that calculates the logical sum of the speed determination signals (D), a falling edge detection circuit 203 that detects the falling edge of the output (M) of the OR circuit 214, and a falling edge detection circuit 2
OR circuit 20 for calculating the logical sum of the output signal (H) of 03 and the output signal (J) of the control mode switching circuit 17
4. Output (G) of rising edge detection circuit 201 and OR
RS set / reset by the output of the circuit 204
It is composed of a flip-flop 205.

Here, the reference value 301 is set as follows. When the pickup (light beam) accesses the target track, the speed command circuit 15 (FIG. 11) generates a predetermined reference speed signal according to the distance from the output of the track count circuit 14 to the target track. Therefore, the relative speed between the light beam and the track is controlled so as to follow the reference speed. Therefore, the number of remaining tracks up to the target track and the relative speed of the light beam and the tracks correspond to each other almost one to one.

Since the noise removing circuit 91 removes the pulse having the time width Wr / 4 or less when the characteristic switching signal (output of the flip-flop 205) is at "L" level, the relative speed between the light beam and the track is reduced. In the case of 2 Vr or more, if the characteristic switching signal becomes the “L” level for some reason, all the pulses input from the binarization circuit 90 will be removed.

Therefore, the reference value 301 is set to the number of remaining tracks at which the reference speed is 2 Vr or less so that the characteristic switching signal does not become "L" level when the number of remaining tracks at which the reference speed is 2 Vr or more (for example, The number of remaining tracks at which the reference speed is 1.5 Vr is set as the reference value).

The circuit operation of the cross-track detection circuit 9C of FIG. 6 will be described with reference to the signal waveform diagrams of FIGS. 7 and 8. First, FIG. 7 shows scratches and dust on the disk. FIG. 7 is a signal waveform diagram of each part showing the circuit operation when no disturbance due to is generated. In FIG. 7, FIG.
The same reference numerals are given to the same signals as the signals in each section indicated by.

Please refer to FIG. 6 and FIG. In the tracking mode in which the light beam follows a predetermined track, the control mode switching circuit 17 (FIG. 11) inputs a control mode switching signal (J) of "L" level to the removal characteristic switching circuit 200. A signal obtained by inverting the control mode switching signal (J) is input to the reset terminal of the RS flip-flop 205 via the OR circuit 204, so that RS
The characteristic switching signal (I) of “L” level is output from the flip-flop 205 to the noise removing circuit 91.

When the characteristic switching signal (I) is at the "L" level, the noise removal circuit 91 determines that the relative speed between the light beam and the track is a speed equal to or lower than a predetermined speed Vr, and the binarization circuit 91. A pulse having a time width Wr / 4 or less is removed from the signal (B) input from 90 as a noise component.

Next, the microcomputer 12 (see FIG.
When the signal for instructing access start is input to the control mode switching circuit 17 from 1), the control mode switching signal (J) becomes "H" level and the access operation is started. When the control mode switching signal (J) switches to "H" level, the output of the OR circuit 204 becomes "L" level and the reset of the RS flip-flop 205 is released. In the comparison circuit 302, the track count circuit 14
And the reference value 301 is compared, and if the number of remaining tracks is equal to or greater than the set value, an "H" level signal is output.

The speed detecting circuit 13 (FIG. 11) detects the relative speed of the light beam and the track from the period of the rising edge of the output (C) of the noise removing circuit 91.
For example, when the cycle becomes Wr or less twice in succession, it is determined that the speed becomes Vr or higher, and the "H" level speed determination signal (D) is output (t1, t2 <Wr in FIG. 7).
And).

The rising edge detection circuit 201 detects the rising edge of the speed discrimination signal (D) and outputs it to the set terminal of the RS flip-flop 205. As a result, the RS flip-flop 205 outputs the “H” level characteristic switching signal (I) to the noise removing circuit 91. Therefore, the characteristic switching signal (I) is at the “L” level during the period when the relative speed between the light beam and the track is low immediately after the start of access, and the noise removing circuit 9
At 1, the pulse having the time width Wr / 4 or less is removed from the signal (B) input from the binarization circuit 90.

When the relative speed between the light beam and the track becomes high and the characteristic switching signal (I) becomes "H" level,
The time width W from the signal (B) input from the binarization circuit 90
Pulses of m / 4 or less are removed.

When the light beam approaches the target track and the number of remaining tracks from the output of the track count circuit 14 to the target track becomes equal to or less than the reference value 301, the comparison circuit 302 outputs a signal of "L" level. It Further, when the light beam approaches the target track, the linear motor 4 is decelerated so that the relative speed between the light beam and the track becomes smaller.

In the speed detecting circuit 13, the noise removing circuit 9
When the cycle of the rising edge of the output (C) of 1 is, for example, twice in succession and the cycle becomes Wr or more, it is determined that the speed becomes Vr or less, and the "L" level speed determination signal (D).
Is output (t3, t4> Wr in FIG. 7).
In the OR circuit 214, the speed discrimination signal (D) and the comparison circuit 3
The output (L) of 02 is calculated and output to the falling edge detection circuit 203.

In the falling edge detection circuit 203, the speed discrimination signal (D) and the output (L) of the comparison circuit 302 are "L".
When the level is reached, the falling edge is detected and OR
Output to the circuit 204. Falling edge detection circuit 203
(H) and the signal obtained by inverting the control mode switching signal (K) are calculated by the OR circuit 203. The result of this operation is input to the reset terminal of the RS flip-flop 205, and the RS flip-flop 205 outputs "
The characteristic switching signal (I) at the L ″ level is output to the noise removing circuit 91. As a result, the noise removing circuit 91
Then, the operation is performed so as to remove the pulse having the time width Wr / 4 or less from the signal (B) input from the binarization circuit 90.

FIG. 8 is a signal waveform diagram of each part showing the circuit operation when a disturbance due to a scratch or dust on the disk occurs when the relative speed between the light beam and the track is 2 Vr or more. In FIG. 8, the tracking error signal (A) is caused by scratches and dust on the pre-format section and the disc.
However, since it is disturbed as shown, the binarization circuit 90
In the output (B) of 1), extra pulses are generated and dropped.

The noise removing circuit 91 operates so as to remove a pulse having a time width of Wm / 4 or less from the output (B) of the binarizing circuit 90 while the speed discrimination signal (D) is at "H" level. Therefore, the pulse having a short time width in the pre-format portion is removed.

Next, the cycle of the output (C) of the noise removing circuit 91 becomes longer due to the disturbance due to scratches and dust, and the speed becomes high at the time when the cycle of the rising edge becomes, for example, two times and the cycle becomes Wr or more. The speed detection circuit 13 determines that the voltage is equal to or lower than Vr, and outputs the speed determination signal (D) of "L" level (t1, t2> Wr in FIG. 8).

The reference value 301 is, for example, a reference speed of 1.5.
Since the number of remaining tracks to be Vr is set and the relative speed between the light beam and the tracks is 2 Vr or more,
The "H" level signal is output from the comparison circuit 302.
Therefore, even when the speed determination signal (D) is at the “L” level, the OR circuit 214 outputs the “H” level signal, and the falling edge detection circuit 203 does not detect the falling edge. Therefore, the RS flip-flop 205 is not reset, and the “H” level characteristic switching signal (I) is output to the noise removing circuit 91.

In the noise removing circuit 91, the binarizing circuit 90
Since it operates so as to remove a pulse having a time width of Wm / 4 or less from the signal (B) input from, the normal signal is not removed even after the disturbance due to scratches / dust is generated. After the disturbance due to scratches or dust has occurred, when the cycle of the rising edge of the output (C) of the noise removal circuit 91 is twice consecutive and the cycle becomes Wr or less, it is determined that the speed becomes Vr or more, and the speed is detected. The "H" level speed determination signal (D) is output from the circuit 13 (t3, t4 <W in FIG. 8).
r).

Next, FIG. 9 is a block diagram showing a main part (cross-track detection circuit 9D) of still another embodiment of the present invention. In FIG. 9, the same functional portions as those shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted unless necessary, in order to avoid duplication.

In FIG. 9, 92 is a band variable filter,
Reference numeral 93 is a binarization circuit, 100 is a speed error detection determination circuit (pulse removal detection circuit), and 200 is a removal characteristic switching circuit. The output (B) of the binarization circuit 90 and the output (C) of the binarization circuit 93 are input to the speed error detection determination circuit 100, and the band variable filter 92 outputs the sine of the tracking error signal (A). It is detected whether the wave signal is removed and the pulse signal is no longer output from the binarization circuit 93, and it is output to the removal characteristic switching circuit 200.

In the removal characteristic switching circuit 200, the speed discrimination signal (D) from the speed detection circuit 13 and the output (F) of the speed error detection determination circuit 100 are input, and the band is changed from the speed error detection determination circuit 100. When the signal indicating that the sine wave signal of the tracking error signal (A) has been removed by the filter 92 is output, the characteristic switching signal (I) for switching the band of the band variable filter 92 to the characteristic when the relative speed is high is output. I am trying to output.

In the band variable filter 92, the band of the filter 92 is set to Fr when the characteristic switching signal (I) is at "L" level, and the band of the filter 92 is set when the characteristic switching signal (I) is at "H" level. Fm. Here, if the relative velocity between the light beam and the track is Vr and the track interval is P, the frequency Fr of the tracking error signal when the light beam crosses the track is expressed by Fr = Vr / P (Equation 7). It

Therefore, when the relative velocity between the light beam and the track is Vr or less, that is, when the velocity discriminating signal (D) is at "L" level, the frequency of the tracking error signal (A) is less than Fr and the frequency greater than Fr. It can be determined that the component of is a signal generated by a disturbance in the pre-format section or the like. The maximum speed during access is Vm, and the frequency Fr of the tracking error signal when the light beam crosses the track at this time is expressed by Fm = Vm / P (Equation 8).

Therefore, in the range where the relative velocity between the light beam and the track is Vr or more and Vm or less, that is, when the velocity discrimination signal (D) is at "H" level, the frequency of the tracking error signal (A) is Fm or less. , Fm and higher frequency components can be judged to be signals generated by disturbance in the pre-format section or the like. Therefore, for example, when the speed determination signal (D) is at "L" level, the band of the band variable filter 92 is set to Fr, and the speed determination signal (D) is "
At the H "level, the band of the band variable filter 92 is set to Fm, so that the disturbance in the pre-format section or the like can be removed.

FIG. 10 is a signal waveform diagram of each part showing the operation when a disturbance due to scratches or dust on the disk occurs when the relative speed between the light beam and the track is Vr or higher. In FIG. 10, the same signals as those of the respective parts shown in FIG. 9 are designated by the same reference numerals.

In FIG. 10, the tracking error signal (A) is caused by scratches and dust on the pre-format portion and the disc.
However, since it is disturbed as shown, the binarization circuit 90
The output (B) of 1 has an extra pulse and a missing pulse. In the band variable filter 92, the speed discrimination signal (D)
In the period of "H" level, the component of the tracking error signal (A) having a frequency higher than Fm is removed.

Therefore, from the output (N) of the variable band filter 92, the high-frequency component of the preformat section is removed. Next, the cycle of the output (C) of the binarization circuit 93 becomes longer due to the disturbance due to scratches and dust, and the speed becomes Vr or less at the time when the cycle of the rising edge becomes, for example, twice consecutively and becomes Wr or more. Then, the speed detection circuit 13 outputs the "L" level speed determination signal (D) (t1, t2> Wr in FIG. 10).

The falling edge detection circuit 203 detects the falling edge of the speed discrimination signal (D), and the OR circuit 2
Output to 04. The OR circuit 204 calculates the logical sum of the output (H) of the falling edge detection circuit 203 and the inverted signal of the control mode switching signal (J). The calculation result is input to the reset terminal of the RS flip-flop 205, and the "L" level characteristic switching signal (I) is output to the band variable filter 92.

The band variable filter 92 operates so as to remove the frequency component of Fr or higher of the tracking error signal (A). When the relative velocity is Vr or higher, the frequency of the tracking error signal (A) is Fr or higher, so that after the disturbance due to scratches or dust is generated, the normal tracking error signal is removed by the band variable filter 92.

In the rising edge detection circuit 101, the rising edge of the output (C) of the binarization circuit 93 is not detected,
The counter 102 is not cleared. Therefore, the counter 102 counts the number of pulses of the output (B) of the binarization circuit 90. When the count value of the counter 102 exceeds the reference value 103, the comparison circuit 104
Outputs an "H" level signal (F).

The output (F) of the comparison circuit 104 is ANDed with the output of the rising edge detection circuit 201 by the OR circuit 202. The operation result is input to the set terminal of the RS flip-flop, and the "H" level characteristic switching signal (I) is output to the band variable filter 92.

As a result, in the variable band filter 92,
A signal from which the frequency component of Fm or higher of the tracking error signal (A) has been removed is output. When the rising edge detection signal (E) of the output (C) of the binarization circuit 93 is input from the edge detection circuit 101 to the clear terminal CLR of the counter 102, the counter 102 is cleared and the comparison circuit 10
The output (F) of 4 becomes "L" level.

Further, when the cycle of the rising edge of the output (C) of the binarization circuit 93 is twice consecutive and the cycle becomes Wr or less, it is determined that the speed becomes Vr or more, and the speed detecting circuit 13 Outputs an "H" level speed determination signal (D) (t3, t4 <Wr in FIG. 10).

In the various embodiments described above, when the detection of the speed range or the number of remaining tracks up to the target track is discriminated in two stages or five stages and the characteristics of the noise elimination circuit or the band variable filter are switched. However, when the characteristics are continuously switched according to the speed or the number of remaining tracks up to the target track,
It is possible to easily configure and implement this embodiment.

In short, when the speed error detection determination circuit (pulse removal detection circuit) detects that the number of removed pulses exceeds a predetermined value, or the number of remaining tracks up to the target track is predetermined. If the number of tracks is equal to or more than the number of tracks, the characteristics of the noise removing circuit may be the characteristics when the speed is high, that is, the time width of the pulse to be removed may be shortened or the band of the band variable filter may be increased.

[0139]

As described above, according to the present invention, when the number of removed pulses becomes equal to or more than a predetermined value in the speed error detection determination circuit (pulse removal detection circuit) (that is, the movement of the pickup). If the speed is erroneously detected or if the number of tracks up to the target track is equal to or greater than a predetermined number of tracks, the characteristics of the noise removal circuit (even if it is switched to the characteristics when the speed is slow) , Because it is an error), it switches to the characteristics when the speed is high, that is, the time width of the pulse to be removed is shortened or the band of the variable band filter is increased.

Even if the speed discrimination signal is erroneously output due to scratches or dust on the disc, the normal signal (normal signal output every time the pickup crosses the track) is not removed, and therefore access is made. It is possible to prevent the linear motor that is performing the operation from running away and to perform a stable access operation to the target track.

[Brief description of drawings]

FIG. 1 is a block diagram showing a cross-track detection circuit as an essential part of an embodiment of the present invention.

FIG. 2 is a signal waveform diagram of each part showing a waveform of each part signal in a normal operation in the circuit of FIG.

3 is a signal waveform diagram of each part showing an operation waveform of each part signal in the circuit of FIG. 1 when a disturbance occurs.

FIG. 4 is a block diagram showing a cross-track detection circuit as an essential part of another embodiment of the present invention.

5 is a signal waveform diagram of each part showing an operation waveform of each part signal in the circuit of FIG. 4 when a disturbance occurs.

FIG. 6 is a block diagram showing a cross track detection circuit as a main part of still another embodiment of the present invention.

7 is a signal waveform diagram of each part showing a waveform of each part signal in a normal operation in the circuit of FIG. 6;

8 is a signal waveform diagram of each part showing an operation waveform of each part signal in the circuit of FIG. 6 when a disturbance occurs.

FIG. 9 is a block diagram showing a cross-track detection circuit as an essential part of still another embodiment of the present invention.

10 is a signal waveform diagram of each part showing an operation waveform of each part signal in the circuit of FIG. 9 when a disturbance occurs.

FIG. 11 is a block diagram showing a configuration of a conventional access control device for a target track of a pickup.

12 is a signal waveform diagram of each part showing an operation waveform of each part signal in the circuit of FIG. 11 when a disturbance occurs.

[Explanation of symbols]

1 ... Disc, 3 ... Pickup, 4 ... Linear motor,
9 ... Cross track detection circuit, 13 ... Speed detection circuit, 1
4 ... Track count circuit, 17 ... Control mode switching circuit, 90 ... Binarizing circuit, 91 ... Noise removing circuit, 92
... band variable filter, 93 ... binarization circuit, 100 ... speed error detection determination circuit (pulse removal detection circuit), 200 ... removal characteristic switching circuit, 300 ... remaining track number detection circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisamitsu Tanaka, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Pref.Inside of Hitachi Media Visual Media Research Institute (72) Inventor Kensho Miyake, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Incorporated company Hitachi Image Information System

Claims (7)

[Claims] 1. An information recording / reproducing medium (1) having a track for recording or reproducing information, a pickup (3) for recording or reproducing information on or from the information recording / reproducing medium, and the pickup. When following the track of the information recording / reproducing medium, a tracking error detecting means (5) for detecting a positional deviation amount between the two and outputting it as a tracking error signal, and the pickup is forcibly moved in a direction crossing the track. A moving means (4) for accessing the target track by means of which the tracking means outputs a substantially sinusoidal waveform each time the pickup crosses one track when the pickup accesses the target track. A binarization device that receives the output from the error detection means, converts it into a pulse-shaped binarized output, and outputs the binarized output. And (90), wherein the input the output of the binarizing means, the noise removal means for outputting by removing noise components contained therein (91)
Track counting means (14) for counting the number of pulse-shaped binarized outputs after noise removal by the noise removing means, calculating the number of remaining tracks up to a target track of a moving pickup, and outputting the track count; Speed detection means (13) for inputting the pulsed binarized output after noise removal by the noise removal means, and detecting and outputting a crossing speed of the moving pickup with respect to the track from the pulse cycle; Control means (8) for controlling the access operation of the pickup to the target track by the moving means based on the output of the track counting means and the output of the speed detecting means.
Furthermore, when the speed detected by the speed detecting means is high, the speed is set, and when the speed is low, the speed is reset and the noise removing characteristics of the noise removing means are moved by the set output and the reset output. In an access control device for a target track of a pickup equipped with a set / reset means (205) that switches according to speed, a disturbance is generated in the speed detecting means from the output of the binarizing means and the output of the noise removing means. When the speed error detection determination means (100) determines whether or not the speed error detection due to the factor is performed, and the speed error detection determination means determines that the speed error is detected, A correction for correcting an erroneous operation applied to the set / reset means since the speed detecting means erroneously detects the speed. The operation, erroneous correction means performs the determination output of the determination means (202),
An access control device for a target track of a pickup, comprising: 2. The access control apparatus for a target track of a pickup according to claim 1, wherein said noise removing means (91) has a predetermined pulse width when the output of said binarizing means is inputted. The means for removing the following pulses as noise, which comprises means for changing the pulse width of the pulse to be removed as noise when the noise removal characteristics are switched by the set / reset means, When the determination means (100) determines that the number of pulses removed by the noise removal means as the pulse having a predetermined pulse width or less is greater than or equal to a predetermined number, the speed detection means causes a speed change due to a disturbance factor. An access control device for a target track of a pickup, comprising: means for determining that erroneous detection has been performed. 3. An information recording / reproducing medium (1) having a track for recording or reproducing information, a pickup (3) for recording or reproducing information on the information recording / reproducing medium, and the pickup. When following the track of the information recording / reproducing medium, a tracking error detecting means (5) for detecting a positional deviation amount between the two and outputting it as a tracking error signal, and the pickup is forcibly moved in a direction crossing the track. A moving means (4) for accessing the target track by means of which the tracking means outputs a substantially sinusoidal waveform each time the pickup crosses one track when the pickup accesses the target track. A binarization device that receives the output from the error detection means, converts it into a pulse-shaped binarized output, and outputs the binarized output. And (90), wherein the input the output of the binarizing means, the noise removal means for outputting by removing noise components contained therein (91)
Track counting means (14) for counting the number of pulse-shaped binarized outputs after noise removal by the noise removing means, calculating the number of remaining tracks up to a target track of a moving pickup, and outputting the track count; Speed detection means (13) for inputting the pulsed binarized output after noise removal by the noise removal means, and detecting and outputting a crossing speed of the moving pickup with respect to the track from the pulse cycle; Control means (8) for controlling the access operation of the pickup to the target track by the moving means based on the output of the track counting means and the output of the speed detecting means.
Furthermore, when the speed detected by the speed detecting means is high, the speed is set, and when the speed is low, the speed is reset and the noise removing characteristics of the noise removing means are moved by the set output and the reset output. In an access control device for a target track of a pickup equipped with a set / reset means (205) for switching according to speed, whether or not the remaining track number output from the track counting means (14) is equal to or more than a predetermined track number. When the erroneous operation is applied to the set / reset means when the remaining track number determination means (300) for determining whether or not and the speed detection means erroneously detect the speed due to a disturbance factor. The erroneous operation correction procedure for performing the correction operation for correcting it by the discrimination output of the remaining track number discriminating means. (214) and it provided with the access control device to the target track of the pick-up characterized by. 4. The access control device for a target track of a pickup according to claim 3, wherein when the output of the binarizing means is input, the noise removing means (91) has a predetermined pulse width therein. Means for removing the following pulse as noise, characterized in that it comprises means for changing the pulse width of the pulse removed as noise when the noise removal characteristics are switched by the set / reset means. Access control device for pickup target truck. 5. An information recording / reproducing medium (1) having a track for recording or reproducing information, a pickup (3) for recording or reproducing information on the information recording / reproducing medium, and the pickup. When following the track of the information recording / reproducing medium, a tracking error detecting means (5) for detecting a positional deviation amount between the two and outputting it as a tracking error signal, and the pickup is forcibly moved in a direction crossing the track. A moving means (4) for accessing the target track by means of which the tracking means outputs a substantially sinusoidal waveform each time the pickup crosses one track when the pickup accesses the target track. The first 2 which receives the output from the error detecting means, converts it into a pulse-like binarized output, and outputs it Means (90), is inputted an output from said tracking error detecting means,
A filter means (92) for removing and outputting a frequency component of a predetermined frequency or higher contained therein as a noise component, and an output of the filter means, which is inputted and converted into a pulsed binarized output and output. 2 binarizing means (93) and a track count for counting the binarized outputs from the second binarizing means to calculate and output the number of remaining tracks up to the target track of the moving pickup. Means (14)
And a speed detecting means (13) for inputting a binarized output from the second binarizing means, detecting a transverse speed of the moving pickup with respect to a track from the pulse period, and outputting the traversing speed. Control means (8) for controlling the access operation of the pickup to the target track by the moving means based on the output of the counting means and the output of the speed detecting means.
Furthermore, when the speed detected by the speed detecting means is high, the speed is set, and when the speed is low, the speed is reset, and the set output and the reset output change the filter characteristic of the filter means to the moving speed of the pickup. In an access control device for a target track of a pickup equipped with a set / reset means (205) for switching in accordance with the output of the first binarization means and the output of the second binarization means, A speed error detection determination unit (100) that determines whether or not a speed error due to a disturbance factor is detected in the speed detection unit, and a speed error detection is performed by the speed error detection determination unit. When the determination is made, in order to correct an erroneous operation applied to the set / reset means because the speed detection means erroneously detects the speed. Corrective operation, erroneous correction means performs the determination output of the determination means (202),
An access control device for a target track of a pickup, comprising: 6. The access control device for a target track of a pickup according to claim 5, wherein the speed error detection determining means (100) has a predetermined number or more of pulses removed by the filter means. When the determination is made, the access control device for the target track of the pickup, which comprises means for determining that the speed detection means has erroneously detected the speed due to a disturbance factor. 7. An information recording / reproducing medium (1) having a track for recording or reproducing information, a pickup (3) for recording or reproducing information on or from the information recording / reproducing medium, and the pickup. When following the track of the information recording / reproducing medium, a tracking error detecting means (5) for detecting a positional deviation amount between the two and outputting it as a tracking error signal, and the pickup is forcibly moved in a direction crossing the track. A moving means (4) for accessing the target track by means of which the tracking means outputs a substantially sinusoidal waveform each time the pickup crosses one track when the pickup accesses the target track. The first 2 which receives the output from the error detecting means, converts it into a pulse-like binarized output, and outputs it Means (90), is inputted an output from said tracking error detecting means,
A filter means (92) for removing and outputting a frequency component of a predetermined frequency or higher contained therein as a noise component, and an output of the filter means, which is inputted and converted into a pulsed binarized output and output. 2 binarizing means (93) and a track count for counting the binarized outputs from the second binarizing means to calculate and output the number of remaining tracks up to the target track of the moving pickup. Means (14)
And a speed detecting means (13) for receiving a binarized output from the second binarizing means and detecting and outputting a traversing speed of the moving pickup with respect to a track from the pulse period thereof, Control means (8) for controlling the access operation of the pickup to the target track by the moving means based on the output of the counting means and the output of the speed detecting means.
Further, when the speed detected by the speed detecting means is high speed, it is set and when it is low speed, it is reset, and the filter characteristic of the filter means is set to the moving speed of the pickup by the set output and the reset output. In a device for controlling access to a target track of a pickup equipped with a set / reset means (205) for switching according to whether the remaining track number output from the track counting means (14) is equal to or more than a predetermined track number. When the remaining track number discriminating means (300) for discriminating and the speed detecting means erroneously detect the speed due to a disturbance factor, if an erroneous operation is applied to the set / reset means, The erroneous operation correcting means (the operation for correcting the Access control to the target track of the pickup, characterized by comprising a 14), the.