JP2732592B2 - Optical disk drive - Google Patents

Description

Description: Object of the Invention (Field of Industrial Application) The present invention relates to an optical disk device for optically recording and reproducing information, and particularly to a track access in an optical disk of a sample servo format system. And an optical disk device.

(Prior Art) Recently, on concentric or spiral tracks,
A pattern consisting of a clock pit located at the center of the track and first and second wobbled pits distributed left and right with respect to the center of the track is formed intermittently along the track direction. An optical disk device has been developed which uses a so-called sample servo format type optical disk and irradiates it with a light beam to record and reproduce information.

FIG. 5 shows an example of an optical disk of the sample servo format system, in which 51 is a track, 52 is a data area for recording or reproducing an information signal, and 53 is a servo area in which clock pits and wobbled pits are formed in advance. Shown respectively.

FIG. 6 (a) is an enlarged view of a part of FIG. 5. In the servo area 53, a clock pit 62 is arranged at a track center 61, and the clock pits 62 are located right and left with respect to the track center 61. First and second wobbled pits 63,6
4 are located. The light beam spot 65 relatively moves on the optical disk from left to right on the paper. At this time, the output signal of the photodetector that detects the reflected light from the light beam is:
The result is as shown in FIG.

By the way, in an optical disk device, generally, a light beam for recording and reproduction is moved to a desired track.
Track access operation is essential. For this purpose, it is essential to determine the direction in which the light beam crosses the track (hereinafter, referred to as the track crossing direction). When an optical disk with a guide groove conventionally used in an optical disk device is used, when an optical beam crosses a track (guide groove) from an inner peripheral side to an outer peripheral side and when an optical beam crosses a track (guide groove) from an outer peripheral side to an inner peripheral side, Since the phase relationship between the sum signal and the difference signal of the two outputs of the two-segment photodetector is different, the track crossing direction can be easily determined by detecting this phase relationship.

However, since the sum signal cannot be obtained stably because there is no guide groove in the optical disk of the sample servo format method, it is necessary to determine the track traversing direction in an optical disk device using an optical disk with a guide groove. Therefore, there is a problem that track access cannot be performed using only signals obtained from the optical disk.

(Problems to be Solved by the Invention) As described above, the track crossing direction cannot be determined in the optical disk apparatus using the optical disk of the sample servo format according to the conventional technique, so that the track cannot be accessed only by the signal obtained from the optical disk. was there.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical disk apparatus that can perform track access while using an optical disk of a sample servo format.

[Constitution of the Invention] (Means for Solving the Problems) In the present invention, a track following error indicating a following error of a light beam with respect to a track by detecting a difference in intensity of light reflected from the first and second wobbled pits. A signal is generated, a change in intensity of reflected light from the clock pit is detected, and a clock pit detection signal corresponding to the change in intensity is generated. From the clock pit detection signal and the track following error signal, the first and second pulse trains are generated each time the light beam crosses the track from the inner circumference to the outer circumference and from the outer circumference to the inner circumference on the optical disk. .

In this pulse train generating means, after the track following error signal is binarized, the rising edge and the falling edge are detected to obtain a rising edge detection pulse and a falling edge detection pulse, and these rising edge detection pulse and falling edge are detected. The first and second pulse trains are generated by taking the logical product of the edge detection pulse and the binarized clock pit detection signal.

For the first and second pulse trains generated in this way, it is determined whether the pulse train is the same-direction pulse train corresponding to the direction in which the light beam should move or the reverse-direction pulse train corresponding to the opposite direction. These co- and reverse-pulse trains are:
By being input to a counting means such as an up-down counter, counting is performed in a decreasing direction and an increasing direction, respectively.

Here, the number of tracks that the light beam should cross, for example, is set as the initial value in the counting means. In that case, the movement of the light beam is stopped when the content of the counting means becomes zero, so that the track access operation is performed. finish.

According to another embodiment of the present invention, the counting means is set to zero as an initial value. In that case, the counting means is further provided with a storage means for storing the number of tracks to be traversed by the light beam. When the contents match, the movement of the light beam is stopped, thereby ending the track access operation.

(Operation) In the present invention, a clock pit detection signal generating means corresponding to the intensity change of the reflected light from the clock pit is newly provided separately from the track following error signal generating means, and these clock pit detection signals and track following error signals are used. hand,
Each time a light beam crosses a track, first and second pulse trains are generated corresponding to the track crossing direction. That is, the first and second pulse trains including the information on the track traversal direction can be obtained while using the optical disk of the sample servo format system. If these pulse trains are discriminated into a same-direction pulse train and a reverse-direction pulse train according to the direction in which the light beam should move, and counted by an up-down counter or the like, the count value is determined by the light beam moving in the designated direction. Indicates the number of tracks crossed. Therefore, when the number of tracks reaches the designated number, that is, when the content of the counting means becomes zero (when the number of tracks to be traversed by the light beam is set as an initial value) or the content of the counting means When the movement of the light beam is stopped when the number of tracks to be traversed matches the number of tracks to be crossed set in the storage means (when zero is set as an initial value), the light beam rides on a desired track and the track access is stopped. Becomes possible.

(Example) Hereinafter, an example of the present invention is described with reference to drawings.

FIG. 1 is a block diagram showing a configuration of an optical disk device according to one embodiment of the present invention. In FIG. 1, an optical disc 1 is a sample servo format optical disc as shown in FIGS. 5 and 6, for example, and a light beam from a laser light source 2 is collimated by a collimator lens 3, a beam splitter 4 and an objective during recording and reproduction. The light is irradiated as a minute spot through the lens 5 and the like. During playback, the optical disk 1
Reflected light passes through the objective lens 5 in the opposite direction to the irradiation light,
The light is guided to the photodetector 6 via the beam splitter 4. The laser light source 2, the collimating lens 3, the beam splitter 4, the objective lens 5, and the photodetector 6 constitute an optical head 7, and are moved in a radial direction of the optical disk 1 by a head slider (not shown) to perform a track access operation. Perform

An output signal (referred to as a reflection signal) a of the photodetector 6 is guided to a reproduction signal processing circuit (not shown) and is also input to a track access control circuit 10 according to the present invention. The track access control circuit 10 is configured as follows.

First, the reflected signal a is binarized by the waveform shaper 11 and then input to the clock regenerator 12. Clock regenerator
Reference numeral 12 reproduces a clock signal with reference to a clock pit in a servo area on the optical disk 1. Timing generator
13 generates timing signals 14, 15, 16 (c) for detecting peak values of the first and second wobbled pits and clock pits using the clock signal.

The reflection signal a is also input to the track following error signal generation circuit 17, and the two sample hold circuits 18 and 19 detect the peak values of the first and second wobbled pits based on the timing signals 14 and 15, respectively. By inputting these peak values to the differential amplifier 20, a track following error signal e indicating the following error of the light beam with respect to the track is generated. The track following error signal e is shaped into a binary signal waveform by the waveform shaper 21 and becomes a binary track following error signal f.

The reflected signal a is also input to the level comparator 22, where it is compared with a predetermined DC reference level Vref to become a binary signal b. The output signal of the level comparator 22 is input to the D input terminal of the flip-flop 23, and CK (clock)
A clock pit detection signal d is generated by detecting the logical level of the clock pit from the timing generator 13 for detecting the peak value of the clock pit inputted to the terminal.

The track following error signal f binarized by the waveform shaper 21 is input to a first monostable multivibrator 24, where a rising edge is detected. The falling edge is detected by being input to 26, and a rising edge detection pulse g and a falling edge detection pulse h are obtained, respectively. Then, the first AND circuit 27 that takes the logical product of the rising edge detection pulse g and the clock pit detection signal d causes the first AND circuit 27 to perform the first operation every time the light beam crosses the track on the optical disc 1 from the inner circumference to the outer circumference. And a second AND circuit 28 that takes the logical product of the falling edge detection pulse h and the clock pit detection signal d causes the light beam to travel from the outer circumference to the inner circumference on the optical disc 1. Each time a track is crossed, a second pulse train j is generated. That is, each time a light beam crosses a track on the optical disc 1 from the inner circumference to the outer circumference by the pulse train generating means including the waveform shaper 21, the monostable multivibrator 24, the inverter 25, and the monostable multivibrator 26. Thus, a first pulse train i is obtained and a second pulse train j is generated each time the light beam crosses the track on the optical disc 1 from the outer circumference to the inner circumference.

The microprocessor 29 generates a movement direction command signal k indicating the direction in which the light beam should move when accessing the track. The third and fourth AND circuits 31 and 32 take the logical product l and m of the movement direction command signal k and the first pulse train i, and the fifth and sixth AND circuits 33 and 34 produce the second pulse train j. And a signal k 'obtained by inverting the moving direction command signal k by the inverter 30 and n and o. The first OR circuit 35 takes the logical sum p of the logical product l and the logical product o, and the second OR circuit 36 takes the logical sum q of the logical product m and the logical product n. At this time, the OR output p is the first
And a pulse train corresponding to the same direction as the direction in which the light beam is to be moved is determined and extracted from the second and third pulse trains i and j, and the logical sum output q is the light output from the first and second pulse trains i and j. Only the pulse train corresponding to the direction opposite to the direction in which the beam should move is determined and extracted as a reverse pulse train.

The microprocessor 29 further generates data r of the number of tracks to be moved by the light beam at the time of track access, and sets it as an initial value in the counter 37. The counter 37 is an up / down counter. The same direction pulse train p from the OR circuit 35 is inputted to the down count input D, and the backward pulse train q from the OR circuit 36 is inputted to the up count input U.
Is entered. When the light beam moves across the number of tracks specified by the number-of-tracks data r to be moved in the direction specified by the movement direction command signal k from the microprocessor 29, the count output s of the counter 37 becomes 0.
Becomes The output s is input to the digital comparator 24 to which 0 is given as a reference value. When it is determined that s has become 0, a track access end signal t is output.

Next, the operation of this embodiment will be described with reference to FIG. 2 and FIG.

FIG. 2 shows a clock pit 62 located at the track center 61.
Are shown, and signals of respective parts when the light beam spot 65 moves as shown by the arrows in the servo area where the first and second wobbled pits 63 and 64 are arranged by being distributed to the left and right of the track center 61. It is. The signal obtained by comparing the reflected light signal a with a predetermined DC reference value Vref by the level comparator 22 becomes like b, and this signal b is detected by the flip-flop 23 at the timing of the rising edge of the timing signal c. Thus, the clock pit detection signal d is generated.

This clock pit detection signal d is a light beam spot.
In the case of FIG. 2A in which 65 passes over the track center 61, the level becomes high, indicating that the light beam spot 65 is on the track center 61, and the light beam spot 65 passes between the tracks. In the case of FIG. 2B, the level becomes low, indicating that the light beam spot 65 has deviated from the track center 61.

FIG. 3 shows that the trajectory of the light beam spot 65 is relatively moved from the inner peripheral side to the outer peripheral side of the disk 1 as shown by an arrow 66 due to the eccentricity of the track on the optical disk 1 and then conversely from the outer peripheral side. The signal waveform of each part when returning to the peripheral side is shown. The state as shown in FIG. 3 is, for example, when the optical disc 1 is eccentric and the track access and tracking are performed on the eccentric optical disc 1. This appears when the speed of the linear motor in the actuator for moving the optical disk 1 in the radial direction is substantially the same. The present invention is particularly effective when performing track access in such a situation.

A rising edge detection pulse and a falling edge detection pulse (first and second monostable multi-pulses) for the signal f obtained by binarizing the track following error signal e generated by the track following error signal generating circuit 17 by the waveform shaper 21 The outputs of the vibrators 24 and 26) are like g and h, respectively. By the AND circuits 27 and 28, these pulses g and h
By taking the logical product of the clock pit detection signal d and
A first pulse train i generated every time the light beam crosses the track from the inner circumference side to the outer circumference side on the optical disc 1 and a second pulse train j is generated every time the light beam crosses the track from the outer circumference side to the inner circumference side. can get.

In the example of FIG. 3, the microprocessor 29 is used to move the light beam from the outer peripheral side to the inner peripheral side of the optical disk.
Output a high-level signal as a moving direction command signal k, thereby extracting the first pulse train i as a same-direction pulse train p in the same direction as the direction in which the light beam should move, and outputting the second pulse train j in the light beam As a reverse pulse train q in the direction opposite to the moving direction of the
Has given to. The counter 37 counts down by the same-direction pulse train p as described above, and the reverse-direction pulse train q
To count up. Thus, when the light beam moves in the direction specified by the movement direction command signal k from the microprocessor 29 across the number of tracks specified by the track number data r to be moved set as the initial value, the counter is set. 37, the count output s becomes 0, and the track access end signal t is output via the digital comparator 24.

FIG. 4 shows a track access control circuit according to another embodiment of the present invention. The microprocessor 29 outputs the moving direction command signal k and the data r of the number of tracks that the light beam should cross on the optical disk, as in the previous embodiment. Data r of the number of tracks to be crossed is stored in the memory 39. The microprocessor 29 has a counter 37
Is set to 0 as an initial value u.

In this embodiment, the counter 37 counts up with the same-direction pulse train p corresponding to the direction in which the light beam should move, and counts down with the reverse-direction pulse train q corresponding to the opposite direction. The digital comparator 40 compares the data r stored in the memory 39 with the output data of the counter 37, that is, the data v of the number of tracks on which the light beam has crossed in the direction specified by the moving direction command data k. When they match, a track access end signal w is output.

Note that the present invention is not limited to the above embodiment, and can be implemented with various modifications. For example, in the embodiment, the clock pit detection signal generating means is replaced with the level comparator 22.
And the flip-flop 23, but may be constituted by a sample-and-hold circuit that samples and holds the reflected signal 7 by the timing signal 16 (c) and a waveform shaper that shapes the output of the reflected signal 7 into a binary signal waveform.

[Effects of the Invention] As described above, the present invention detects a difference in intensity of reflected light from the first and second wobbled pits to generate a track following error signal, and generates a track following error signal. A clock pit detection signal is generated by detecting a change in intensity. From these signals, first and second light beams are generated each time a light beam crosses a track on the optical disc from the inner side to the outer side and from the outer side to the inner side. A second pulse train is generated, and from these first and second pulse trains, it is discriminated and extracted from the same pulse train corresponding to the same direction as the direction in which the light beam should move and the reverse pulse train corresponding to the opposite direction, and reduced. The counting is performed in the direction and the increasing direction, and when it is detected that the number of tracks traversed by the light beam reaches the designated number of tracks, the movement of the light beam is stopped. Therefore, according to the present invention, it is possible to perform track access using only a signal obtained from an optical disk, which was impossible in the related art when an optical disk of a sample servo format method is used.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a main part of an optical disk device according to an embodiment of the present invention, FIGS. 2 and 3 are timing charts for explaining the operation of the embodiment, and FIG. FIG. 5 is a block diagram showing a configuration of a track access control circuit according to another embodiment of the invention, FIG. 5 is a diagram showing an example of an optical disk of a sample servo format system, and FIG. 6 is a diagram showing a part of FIG. It is. 1 ... optical disk of sample servo format method, 2
... Laser light source, 6 ... Photodetector, 7 ... Optical head, 10 ...
Track access control circuit, 17: track following error signal generation circuit, 21: waveform shaper, 22, 23: level comparator and flip-flop constituting clock pit detection signal generation means, 24, 26 and 27, 28 ... first And a monostable multivibrator constituting second pulse train generating means, and
AND circuit, 31 to 34 and 35, 36... AND circuit and OR circuit constituting pulse train discriminating means, 37... Counter (counting means), 38
... Comparator, 39 ... Memory (storage means), 40 ... Comparator, 51 ...
Track, 52: data area, 53: servo area, 61: track center, 62: clock pit, 63, 64: first and second
Wobbled pit, 65 ... light beam spot, 66 ... light beam spot trajectory.

Claims (2)

(57) [Claims] 1. A clock pit arranged at the center of a track on a concentric or spiral track, and first and second wobbled pits arranged on the left and right sides of the track. In an optical disc device for recording and reproducing information by irradiating a light beam to an optical disc in which a pattern is formed intermittently along a track direction, the intensity difference of reflected light from the first and second wobbled pits is determined. Means for detecting and generating a track following error signal indicating a following error of the light beam with respect to the track; detecting a change in intensity of reflected light from the clock pit and generating a clock pit detection signal corresponding to the change in intensity; Means, and a clock pit detection signal generated by the means
From the clock pit detection signal binarized by the means and the track following error signal, the light beam moves the track on the optical disk from the inner side to the outer side and the inner side from the outer side. A pulse train generating means for generating a first and a second pulse train each time the light beam crosses, and the first and second pulse trains generated by the means are the same as the direction in which the light beam should move on the optical disk. Pulse train discriminating means for discriminating between a co-directional pulse train corresponding to a direction and a reverse-direction pulse train corresponding to a reverse direction; the number of tracks on which the light beam should cross on the optical disc is set as an initial value; Counting means for counting the direction pulse trains in the decreasing direction and increasing direction, respectively; and when the content of the counting means becomes zero, the light beam is moved. Means for stopping, wherein the pulse generating means outputs the track following error signal by 2
Means for converting the value, means for detecting the rising and falling edges of the track following error signal binarized by this means to obtain a rising edge detection pulse and a falling edge detection pulse, and the rising edge obtained by this means An optical disk apparatus comprising: means for obtaining an AND of an edge detection pulse, a falling edge detection pulse, and the binarized clock pit detection signal to obtain the first and second pulse trains. . 2. A clock pit arranged at the center of a track on a concentric or spiral track, and first and second wobbled pits arranged on the left and right sides of the track. In an optical disc device for recording and reproducing information by irradiating a light beam to an optical disc in which a pattern is formed intermittently along a track direction, the intensity difference of reflected light from the first and second wobbled pits is determined. Means for detecting and generating a track following error signal indicating a following error of the light beam with respect to the track; detecting a change in intensity of reflected light from the clock pit and generating a clock pit detection signal corresponding to the change in intensity; Means, and a clock pit detection signal generated by the means
From the clock pit detection signal binarized by the means and the track following error signal, the light beam moves the track on the optical disk from the inner side to the outer side and the inner side from the outer side. A pulse train generating means for generating a first and a second pulse train each time the light beam crosses, and the first and second pulse trains generated by the means are the same as the direction in which the light beam should move on the optical disk. Pulse train discriminating means for discriminating between a same-direction pulse train corresponding to a direction and a backward-direction pulse train corresponding to a reverse direction; storage means for storing the number of tracks on which the light beam should cross on the optical disk; Counting means for counting the direction pulse train in the decreasing direction and increasing direction, respectively; and determining that the content of the counting means matches the content of the storage means. And means allowed to stop the movement of the light beam, the pulse generating means, 2 the track following error signal
Means for converting the value, means for detecting the rising and falling edges of the track following error signal binarized by this means to obtain a rising edge detection pulse and a falling edge detection pulse, and the rising edge obtained by this means An optical disk apparatus comprising: means for obtaining an AND of an edge detection pulse, a falling edge detection pulse, and the binarized clock pit detection signal to obtain the first and second pulse trains. .