JP2728746B2 - Optical disk device and track number detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to an optical disk device for recording and reproducing information using an optical disk of a sample servo system, and the number of tracks at the time of access in the optical disk device. It relates to the detection method.

(Prior Art) The optical disk of the sample servo system has a servo pattern 62 intermittently formed on a spiral or concentric track 61 as shown in FIG.
During recording and reproduction, signals necessary for clock reproduction, tracking, and track access are obtained from the detection signal corresponding to the servo pattern 62.

FIG. 7 shows a known example of the servo pattern 62.
Wobbled pits 71 and 72 arranged on the left and right with respect to the center of the track 61, a gray code section 73, and a mirror section 7
4 and a clock pit 75. Wobbled pit 71,
Numeral 72 is for obtaining a tracking signal, mirror unit 74 is for obtaining a focus error signal, and clock pit 75 is for reproducing a clock signal during recording / reproduction.

The gray code section 73 changes for each track 61 for detecting the number of tracks (the number of cross tracks) crossed by the light beam when the light beam relatively moves on the optical disc 1 for track access or the like. It is a specific pit pattern (in this case, a gray code pattern), and n types (n = 16 in this example) of patterns are set and formed over adjacent n tracks. A set of the gray code patterns formed over the n tracks is called one set. A plurality of sets of these gray codes are provided in the radial direction of the optical disc 1.

At the time of track access, a gray code pattern is read from the detection signal corresponding to the gray code section 73 at each sample timing. For example, assuming that the gray code patterns on tracks A and B of the gray code section 73 are 8 (a) and 8 (b), the detection signals obtained by the photodetector from the gray code section 73 are shown in FIGS. 8 (c) and 8 (d). And these are binarized and shaped using a clock signal,
The gray code pattern is read as shown in FIGS.

By comparing the gray code pattern read at the current sample timing with the gray code pattern read at the previous sample timing, the number of cross tracks between both sample timings is detected at each sample timing together with information on the track cross direction. be able to. For example, when there are 16 types of gray code patterns as in the example of FIG. 7, the number of cross tracks up to 8 tracks can be detected. Then, the relative movement speed of the light beam with respect to the optical disc is estimated from the number of cross tracks obtained between each sample timing, and the total number of cross tracks is obtained by adding up the number of cross tracks, or the total number of tracks being accessed or the target track can be obtained. It is possible to know the travel distance and perform control such as switching the track access speed.

As described above, the track access operation is performed based on information such as the number of cross tracks between sample timings, the relative movement direction of the light beam, the relative movement speed of the light beam, and the total number of tracks. Generally, when the distance to the target track is relatively long, the track access is initially performed at a high speed, and when approaching the target track, the speed is reduced and performed at a low speed.

By the way, at the time of track access, a detection signal is obtained although the level is low not only from above the track but also from the area between the tracks, and since the spot of the light beam has a certain size, the crosstalk from the adjacent track is reduced. An effect occurs on the detection signal from each track. Due to the influence of the detection signal from the inter-track area and the crosstalk from the adjacent track, the peak position of the detection signal from the gray code section 73 shifts during high-speed track access, or the clock signal obtained from the clock pit 75 If the phase is disturbed, the gray code pattern may be read as a pattern different from the actual one.

In such a case, the number of cross tracks between sample timings cannot be accurately detected, and the relative movement speed of the light beam estimated from the number of cross tracks between sample timings and the total number of tracks are also incorrect. Becomes In particular, since the total number of tracks is obtained by accumulating the number of cross tracks between sample timings during access, errors in the number of cross tracks are accumulated, and a large error occurs in the total number of tracks.

(Problems to be Solved by the Invention) As described above, in the conventional method, especially at the time of high-speed access, the gray level for detecting the number of cross tracks is affected by the influence of a detection signal from an inter-track area or crosstalk from an adjacent track. The code pattern may be read by mistake. For this reason, it is difficult to correctly detect the number of cross tracks between sample timings, and the relative movement speed of the light beam estimated from the number of cross tracks,
There is a high possibility that the information on the total number of tracks is erroneous, and the reliability of the track access operation is low.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical disk device and a track number detection method that can accurately detect the number of tracks at the time of track access in a sample servo type optical disk.

[Structure of the Invention] (Means for Solving the Problems) An optical disc apparatus according to the present invention comprises: an initial pattern storage means for storing the pit pattern on an initial position track read at the time of access start; By comparing the stored pit pattern on the initial position track with the pit pattern on the current position track read during access, the predetermined number of tracks from the initial position track to the current position track are compared. A surplus track number detecting means for detecting a surplus track number less than a positive integer multiple; a cross set number counting means for counting the number of cross sets in which the light beam crosses the set during access; and Multiply the number of cross sets counted by the set number counting means by the predetermined number of tracks. By adding the number, the number of the remainder tracks has as its basic; and a track number computing means for obtaining the number of tracks from the initial position the track to the current position track.

In the present invention, more preferably, the read error determining means for determining the presence or absence of the read error of the pit pattern at each sample timing, and the read is performed at each sample timing at which the read means determines that there is no read error. Cross track number detecting means for comparing the pit pattern with the pit pattern read at the previous sample timing and detecting the number of cross tracks where the light beam crosses the track between these sample timings; A cross track number storage means for storing the number of cross tracks detected by the number detection means; and, when it is determined that there is a read error, the number of cross tracks stored in the cross track number storage means is read the number of consecutive occurrences of the error. Cross track number accumulator If, when it is determined that no reading errors outputs the calculation result of the track number computing means,
Output means for outputting a result obtained by adding the integration result of the cross track number integration means to the calculation result when it is determined that there is a reading error.

In this case, preferably, when it is determined that there is no reading error, the cross set number counting means checks whether or not the light beam crosses the set by monitoring the detection result of the surplus track number detecting means. If it is determined that the light beam crosses the set, it is checked whether or not the light beam crosses the set by monitoring the output result of the output means, and counts up each time the light beam crosses.

(Operation) In the present invention, the sum of the value obtained by multiplying the number of tracks in which one set of specific pit patterns such as a gray code is formed by the number of cross sets and the number of surplus tracks is calculated from the initial position track to the current position track. Of tracks. Here, since the number of surplus tracks is obtained for each sample timing regardless of the presence / absence of a read error at the preceding sample timing, there is no accumulation of errors due to the read error. On the other hand, the number of cross sets is a value obtained each time a light beam crosses a specific pit pattern formed over a plurality of tracks by one set, and thus the possibility of occurrence of an error is low.

If a specific pit pattern reading error occurs, the total number of tracks up to the previous sample timing is
The number of tracks from the initial position track to the current position track is obtained by adding the number of cross tracks between the past sample timings when there is no read error. There is no big mistake.

Further, when a reading error of a specific pit pattern occurs, set detection is performed from data on the number of tracks finally output, thereby preventing errors in counting the number of cross sets. The properties are further improved.

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

FIG. 1 is a block diagram showing a first embodiment of the optical disk apparatus according to the present invention, and particularly shows a configuration of a portion relating to detection of the number of cross tracks. In FIG. 1, an optical disk 1 is, for example, a sample servo type optical disk as shown in FIGS. 6 and 7, and is irradiated with a light beam by an optical head 2 during recording and reproduction, and reflected light is emitted from the optical head 2. And an electric signal (hereinafter, referred to as a detection signal) is obtained.

The detection signal output from the optical head 2 is supplied to a terminal 3
Is input to the clock recovery circuit 4 and the binarization shaping circuit 6 via The clock signal obtained by the clock recovery circuit 4 is input to the timing generation circuit 4 and the binarization shaping circuit 6. The clock reproducing circuit 4 extracts a signal corresponding to the clock pit 75 in FIG. 7 from the detection signal, shapes the waveform, and reproduces the clock signal. The timing generation circuit 5 generates various necessary timing signals in each section based on the clock signal.

The binarization shaping circuit 6 binarizes the detection signal, which is an analog signal output from the optical head 2, and shapes the detection signal into a square wave using a clock signal. FIG. 4 is an example of the binarization shaping circuit 6, and FIG. 5 is a waveform diagram of each part in FIG. 4, the comparator 41 binarizes the detection signal a shown in FIG. 5 (a) as shown in FIG. 5 (b),
The binary signal b is output. The D-type flip-flop 42
The binary signal b is read at, for example, the rising edge of the clock signal c shown in FIG. 5C, and a signal d as shown in FIG. 5D is output from the Q terminal. The AND circuit 44 receives the output signal d of the flip-flop 52 and the delayed clock signal e obtained by delaying the clock signal c by a predetermined time by the delay circuit 43 as shown in FIG. Synchronized binarized signal f shown in FIG. 5 (f)
Is output.

The output signal of the binarization shaping circuit 6 is input to the pattern number decoder 7. The pattern number decoder 7 detects the pattern of the gray code part 73 in FIG. 7 from the output signal of the binarization / shaping circuit 6 and determines which of the 16 types of patterns shown in FIG. Then, data indicating the number of the pattern is output. This pattern number data is input to the initial pattern latch circuit 8 and the surplus track number detection unit 9. The initial pattern latch circuit 8 stores pattern number data obtained at the start of access, that is, data of a pattern number (hereinafter referred to as an initial pattern number) of a gray code portion on an initial position track of a light beam positioned at the start of access. Hold.

The surplus track number detection unit 9 obtains the initial pattern number data and the pattern number of the gray code part on the track at the current position where the light beam is located, which is obtained from the pattern number decoder 7 at each sample timing during access ( (Hereinafter referred to as the current pattern number)
Due to the difference between the two number data, of the number of tracks from the initial position track to the current position track, n tracks in which one set of gray code is formed (n = n in the example of FIG. 7)
16) Number of tracks A less than positive integer (natural number) times
(This is called the number of surplus tracks). That is, the number of surplus tracks A represents the remainder when T is the number of tracks from the initial position track to the current position track, and T is divided by the number n of tracks on which one set of gray codes is formed. In the case of n = 16, the data of the surplus track number A is represented by a 4-bit binary number. If A = 0, it is “0000”, and if A = 15, it is “1111”.

The data of the surplus track number A from the surplus track number detection unit 9 is input to the set detection unit 10. Set detector 10
Is a circuit for generating a signal each time a light beam passes through one set of gray code portions. Specifically, for example, when n = 16, data (A) of the number of surplus tracks A detected by the surplus track number detector 9 Check the place value of 2 ³ binary), when this time the inverted "L" to "H", i.e., the data of the remainder number of tracks a is changed to "1111" to "0000", 1
It is determined that the signal has passed the set, and a pulse signal is generated.
The pulse signal output from the set detection unit 10 is input to the cross set number counter 11. The cross set number counter 11 counts up each time a pulse signal is input from the set number detection unit 10, and indicates the number B of gray code sets detected by the light beam during access (this is called the number of cross sets). Output binary data.

The output data of the cross set number counter 11 is input to the track number calculation circuit 12 together with the output data from the surplus track number detection unit 9. The track number calculation circuit 12 calculates the number A of surplus tracks and the number B
Is added to a value n · B obtained by multiplying the number n of tracks on which one set of gray codes is formed, to calculate the number T of tracks from the initial position track to the current position track, and output data indicating the number of tracks. I do. If n = 16,
For n · B, the data (binary number) of the cross set number B may be bit-shifted to the upper digit by 4 bits, and the track number calculation circuit 12 is realized by a bit shifter and an adder.

T = A + n · B Here, the number of cross sets B is a value that increases by one each time the light beam crosses one set of the gray code, that is, every time the light beam crosses n tracks. Low.

On the other hand, the surplus track number A is data obtained by comparing the initial pattern number and the current pattern number by the surplus track number detection unit 9 and is related to the current pattern number obtained at the previous sample timing for each sample timing. Value that is updated without That is, even if a reading error occurs at a certain sample timing when reading the pattern of the gray code portion, if the pattern of the gray code portion is correctly read at the next sample timing,
A correct value can be obtained irrespective of the presence or absence of a read error at an earlier sample timing.

Therefore, according to this embodiment, errors in detection of the number of tracks during access are not accumulated, and the number of tracks from the initial position track to the current position track can be detected without a large error. The result is obtained.

Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 2, blocks 3 to 12 are the first blocks.
It is almost the same as the figure, and a new track number latch circuit 13,
Front pattern latch circuit 14, cross track number detection unit 15,
Cross track number latch circuit 16, read error judgment unit 1
7, a cross track number integrating circuit 18, a selector 19 and an adder 20 are provided.

The track number latch circuit 13 stores and holds the number of tracks calculated by the track number calculation circuit 12 when the read error determination section 17 determines that there is no read error.

The previous pattern latch circuit 14 includes a pattern number decoder 7
Is stored until the next pattern number is output. The cross track number detecting section 15 compares the pattern number at the current sample timing output from the pattern number decoder 7 with the pattern number at the previous sample timing stored and held in the previous pattern latch circuit 14 and compares the two sample numbers. The number of cross tracks between timings is detected. The cross track number latch circuit 16 stores and holds data on the number of cross tracks detected by the cross track number detection unit 15 when the read error determination unit 17 determines that there is no read error.

The read error determination unit 17 is a circuit that determines the presence or absence of a read error of a gray code pattern in the output signal of the binarization and shaping circuit 5 at each ampoule timing, and is, for example, a gray code pattern shown in FIG. f) 16 types of pulse pair patterns as shown in f) are stored in advance, and these are compared with the detected Gray code pattern,
Alternatively, the number of cross tracks between sample timings detected by the cross track number detector 15 and the cross track number change rate and other information that is the difference between the number of cross tracks and the number of cross tracks held in the cross track number latch circuit 16 are also stored. Based on this, it is determined whether there is a reading error. For example, if the detected gray code pattern matches any of the stored gray code patterns, it is determined that there is no reading error, and if it does not match any of the stored gray code patterns, it is determined that there is a reading error.

The cross track number accumulating circuit 18 includes a reading error determination unit.
If it is determined in step 17 that there is a read error, the number of cross tracks held in the cross track number latch circuit 16 is integrated by the number of consecutive occurrences of the read error.
That is, assuming that the number of consecutive occurrences of read errors is N and the number of cross tracks is ΔT, the cross track number accumulation circuit 18 generates N · ΔT data.

The selector 19 outputs the output data of the cross track number accumulating circuit 18 when the reading error judging section 17 judges that there is no reading error, and outputs the data “0” when it judges that there is a reading error. The output data of the selector 19 is input to the adder 20, and is added to the output data from the total track number calculation circuit 13.

In this embodiment, when there is no read error of the gray code pattern, the output of the selector 19 becomes “0”, so that the data of the total track number from the total track number latch circuit 13 is passed through the adder 20 as it is. The output is the same as in the first embodiment. On the other hand, if there is a read error of the gray code pattern, since the output data of the cross track number integrating circuit 18 is output from the selector 19, the total track number up to the previous sample timing held in the total track number latch circuit 13 is output. Number of cross track number accumulation circuit 18
The data obtained by adding the number of cross tracks between past sample timings when there is no reading error output from the adder 20 is output from the adder 20. Therefore, even if there is a reading error in the gray code portion, the data of the total number of tracks to be output does not greatly erroneously.

Further, in this embodiment, when a read error of the gray code pattern occurs, the set detection is not performed by the set detection unit 10. incorrectly 2 ³ digit of the number of data, even when a becomes "H" to "L", never circle erroneous counting the cross set speed cross sets counter 11.

FIG. 3 shows a third embodiment of the present invention, which is a further improvement of the second embodiment described above. The data of the number of cross tracks output from the adder 20 is output to the set detector 10 by the set detector. The difference from the second embodiment is that the feedback is made to 10.

Set detection unit 10 in a case where a gray code reading error occurs, instead of 2 ^3-position of the data of the number of surplus tracks output from the remainder track number detection unit 9, an adder 20 outputs the data of the 2 ³ Check the place. When setting detector 10 in which two ^3-position of the output data of the adder 20 by the generation of a continuous read error has changed from "H" to "L", the light beam is one set of gray code portion It is determined that there is a cross, and one pulse signal is sent to the cross set number counter 11 to count up the counter 11. According to the present embodiment, the number of cross sets can be correctly counted even when the reading error of the gray code pattern continues over a plurality of sample timings.

That is, one or successive When proceeding light beam 8 or more tracks between the several reading error, much is 2 ^3-position of the data of the remainder number of tracks outputted from the remainder track number detection unit 9 "H "L" remains, and after a certain set is detected, even if the track advances 16 tracks or more, the set detection is not performed, and the count value of the number of cross sets may be incorrect. In such a case, in the present embodiment, by utilizing the fact that the output data of the adder 20 increases due to the integration of the number of cross tracks, the set detection is performed by the set detection unit 10 so that the counting of the number of sets is not mistaken. Therefore, the reliability of track number detection can be further improved.

[Effects of the Invention] As described above, according to the present invention, the number of cross sets indicating how many sets of a specific pit pattern such as a gray light beam crosses on an optical disk, the pit pattern at the start of access, and the like. Since the number of tracks being accessed is detected based on the number of surplus tracks less than the number of tracks in one set determined by comparison with the current pit pattern, a reading error of a specific pit pattern occurs at a sample timing during access. However, if the reading is performed correctly at the next sample timing, the correct number of tracks can be obtained, so that there is no accumulation of errors in the number of cross tracks as in the prior art, and the number of sets can be roughly calculated. And the occurrence of counting errors is small. Therefore, the number of tracks from the initial position track being accessed to the current position track can be obtained without a large error, and a highly reliable access operation can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of an optical disk apparatus according to the present invention, FIG. 2 is a block diagram showing a second embodiment, and FIG. 3 is a block diagram showing a third embodiment. 4, FIG. 4 is a diagram showing a specific example of a binarization shaping circuit, FIG. 5 is a timing diagram for explaining the operation of FIG. 4, FIG. 6 is a plan view schematically showing an optical disk of a sample servo system, FIG. 7 is a diagram showing an example of a servo pattern on an optical disk of a conventional sample servo system. FIG. 8 is a diagram showing a gray code pattern on two adjacent tracks of FIG. It is a figure showing a binarization shaping waveform. DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Optical head, 4 ... Clock reproduction circuit, 5 ... Timing generation circuit, 6 ... Binarization shaping circuit, 7
... pattern number decoder, 8 ... initial pattern latch circuit, 9 ... surplus track number detection unit, 10 ... set detection unit, 11
… Cross set number counter, 12… Track number calculation circuit,
13: total track number latch circuit, 14: previous pattern latch circuit, 15: cross track number detection section, 16-cross track number latch circuit, 17: read error determination section, 18: cross track number integration circuit, 19: selector, 20: adder, 61: track, 62: servo pattern, 71, 72: wooled pit, 73: gray code section, 74: mirror section, 75: clock pit.

Claims (6)

(57) [Claims] A light beam is applied to an optical disc in which a plurality of sets each formed by forming a specific pit pattern different for each track or a plurality of tracks over a predetermined number of adjacent tracks are irradiated with a light beam, and the pit pattern is changed. In an optical disc apparatus for recording and reproducing information while reading at a predetermined sample timing, an initial pattern storage means for storing the pit pattern on an initial position track read at the time of access start; The pit pattern on the current position track and the pit pattern on the current position track read during access are compared, and a positive integer of the predetermined number of tracks from the number of tracks from the initial position track to the current position track is compared. Detect the number of surplus tracks less than double Surplus track number detecting means, cross set number counting means for counting the number of cross sets in which the light beam crosses the set during access, and the number of cross sets counted by the cross set number counting means from the start of the access. A number of tracks from the initial position track to the current position track by adding the number obtained by multiplying the number of tracks by the predetermined number of tracks and the number of surplus tracks; apparatus. 2. A light beam is applied to an optical disc in which a plurality of sets each formed by forming a specific pit pattern different for each track or a plurality of tracks over a predetermined number of adjacent tracks are formed in a radial direction, and the pit pattern is changed. In an optical disc apparatus for recording and reproducing information while reading at a predetermined sample timing, an initial pattern storage means for storing the pit pattern on an initial position track read at the time of access start; The pit pattern on the current position track and the pit pattern on the current position track read during access are compared, and a positive integer of the predetermined number of tracks from the number of tracks from the initial position track to the current position track is compared. Detect the number of surplus tracks less than double Surplus track number detecting means, cross set number counting means for counting the number of cross sets in which the light beam crosses the set during access, and the number of cross sets counted by the cross set number counting means from the start of the access. Track number calculating means for calculating the number of tracks from the initial position track to the current position track by adding the number obtained by multiplying the number of tracks by the predetermined track number and the number of surplus tracks; A read error determining unit that determines the read error at each sample timing, and compares the read pit pattern with the pit pattern read at the previous sample timing at each sample timing when the read unit determines that there is no read error. Between the two sample timings. A cross track number detecting means for detecting the number of cross tracks crossing the recording track; a cross track number storing means for storing the number of cross tracks detected by the cross track number detecting means; and a reading error determined by the determining means When done
A cross-track number accumulating means for accumulating the number of cross tracks stored in the cross-track number storage means by the number of consecutive occurrences of read errors; and a cross-track number calculating means when the judgment means judges that there is no read error. An optical disk device comprising: an output unit that outputs a calculation result and, when it is determined that there is a reading error, outputs a result obtained by adding the integration result of the cross track number integration unit to the calculation result. 3. The cross set number counting means checks whether the light beam crosses the set by monitoring a detection result of the surplus track number detection means,
3. The optical disc apparatus according to claim 1, wherein the count is incremented each time the cross is made. 4. The cross set number counting means monitors whether the light beam crosses the set by monitoring the detection result of the surplus track number detection means when the reading means determines that there is no reading error. Check if
When the determination unit determines that there is a reading error, it monitors whether the light beam crosses the set by monitoring the output result of the output unit, and counts up each time the light beam crosses. Claim 2
An optical disk device as described in the above. 5. An optical disk in which a plurality of sets each formed by forming a specific pit pattern different for each track or a plurality of tracks over a predetermined number of adjacent tracks is irradiated in a radial direction with a light beam, and the pit pattern is changed. A method for detecting the number of tracks from an initial position track read at the start of access to a current position track read during access at the time of access of an optical disk device that performs recording and reproduction of information while reading at a predetermined sample timing, Among the number of tracks, the number of surplus tracks less than a positive integer multiple of the predetermined number of tracks and the number of cross sets in which the light beam crosses the set during access are obtained.
A method for detecting the number of tracks in an optical disc device, wherein the number of tracks is obtained by adding the number obtained by multiplying the number of cross sets by the predetermined number of tracks and the number of remaining tracks. 6. An optical disk in which a plurality of sets each formed by forming a specific pit pattern which is different for each track or a plurality of tracks over a predetermined number of adjacent tracks is formed in a radial direction, is irradiated with a light beam, and the pit pattern is changed. A method for detecting the number of tracks from an initial position track read at the start of access to a current position track read during access at the time of access of an optical disk device that performs recording and reproduction of information while reading at a predetermined sample timing, Among the number of tracks, the number of surplus tracks less than a positive integer multiple of the predetermined number of tracks and the number of cross sets in which the light beam crosses the set during access are obtained.
A number obtained by multiplying the number of cross sets by the predetermined number of tracks and the number of surplus tracks are added to be a candidate for the number of tracks. The number of cross tracks where the light beam crosses the track between these sample timings is detected by comparing the pit pattern read at each sample timing with the pit pattern read at the previous sample timing. The stored number of cross tracks is integrated by the number of consecutive occurrences of read errors, and when it is determined that there is no read error, the candidate for the number of tracks is output as the number of tracks as it is, When it is determined that there is a read error, the read error is Track number detecting method in an optical disk apparatus and outputs the number of consecutive occurrences only integration is a result of said adding the number of cross tracks as the number of tracks.