JPS61104471A - Retrieving method for position of guide track - Google Patents

Abstract

PURPOSE:To attain the retrieval of a target guide track despite the presence of a range where the correct reading of address information is impossible, by adding and subtracting 1 to and from the counter value to eliminate an error the count value and the number of tracks shifted in case a part where the track number is replaced during the retrieval done by a track jumping action. CONSTITUTION:In case the reading is impossible for the effective address information after a track shift is over, the number of shifted tracks is counted previously by a counter for check of address information invalid range. If a target guide track is set in a range where the reading is possible for the effective address information, the absolute value 1N-A1 of the difference of address information is stored in an address difference store counter 54. Then the value of the counter 54 is subtracted by 1 when the track number is replaced by a detection function 43 for track number replacement part while the track is advancing toward the disk inner circumferential direction with a normal reverse reproducing action by a control function 52 of a tracking control circuit 34. Thus it is possible for the guide track where the value of the counter 54 is equal to 0 to estimate and retrieve a target guide track.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for searching a guide track formed on a disc-shaped or cylindrical recording medium, and particularly relates to a method for searching a guide track formed on a disc-shaped or cylindrical recording medium, and in particular, a method for searching a guide track in which address information on a guide track cannot be read correctly. The present invention relates to a track search method suitable for when a range exists.

[Background of the invention]

A reproduction-only device and an IeQ reproduction device for a disk-shaped or cylindrical recording medium (hereinafter referred to as a disk) in which guide tracks are formed in a spiral or concentric shape and address information indicating the guide track number is written in a normal or reverse order. One of the major features of the disc is that it can search for any guide track on the disc by moving the information reading section in the radial direction of the disc. Various methods have been proposed to date as the search method. For example, JP-A-54-76104
As stated in the above issue, when the address difference between the guide track whose address information is currently being read and the guide track of the search target is greater than the threshold value lN, the reader is sent to the target guide track at high speed by the sensor control. direction, and when the address difference becomes less than the threshold value, the drive is switched from the feed sweater control to the tracking servo system-based drive, and a number of pulses corresponding to the address difference are generated to emit light. The reader is moved in the direction of the target guide track while moving the beam spot, and after the pulse output is completed, the address difference is verified again.The above operation is repeated until there is no address difference. No consideration has been given to the case where the address information cannot be read correctly due to reasons such as the above.For this reason, the information reading section does not read the address information when the original beam spot movement search is completed by the motor control or pulse output. If the information was located in a range where the information could not be read correctly, there was a possibility of malfunction due to incorrect address information.Furthermore, if the address information of the target guide track could not be read correctly, the target guide track could not be read correctly.

There was a problem with not being able to search for guide tracks.

[Purpose of the invention]

As described above, the present invention provides a search method that makes it possible to search for a specified target guide track even when there is a range in which address information indicating the guide track number formed on the disc cannot be read correctly. There is a particular thing.

[Summary of the invention]

Therefore, in the present invention, the validity of the address information read for the address difference verification is checked, and if it is invalid, the address information is read from the adjacent guide track by advancing one track in the direction of the outer circumference of the disk, and then reading the address information again from the adjacent guide track. Check the validity of address information. This continues until valid address information can be read. Of course, the moving direction of the information reading unit to search for a guide track from which the valid address information can be read is not limited to the outer circumferential direction of the disk, but may also be the inner circumferential direction of the disk, and the direction of movement may be reversed midway. I don't mind.

When it is confirmed that the target information track is located in a range where correct address information cannot be read, that is, in a range where address information is invalidated, the light beam spot is moved by normal mill playback operation or normal reverse playback operation. to make it possible to guess and search the target guide track.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram showing an example of a disk used in the present invention. As shown in the figure, in addition to the groove-shaped guide track 2, the disk 1 includes an address area 4 in which an address signal unique to each guide track is recorded and is used for recording position alignment for each guide track. Mark 5 is formed. In the figure, in order to simplify the explanation, only the spiral track 2 is shown, but it goes without saying that this may be a concentric track. In the case of this example,
The address signal has 5 BOD digits, no parity, and is recorded 5 times in each area.

FIG. 2 is an explanatory diagram showing the configuration of the optical head 16 for recording and reproducing used in the present invention.

In the figure, a light beam from a laser diode 5 is collimated by a collimating lens 6, passes through a polarizing beam splitter 7, a 1/4 wavelength plate 8, and is converted into a light spot on a disk 1 by an objective lens 10 attached to an actuator 9 and swung. Narrowed down.

The reflected light from the disk 1 is converted into parallel light again by the objective lens 10, passes through the 1/4 wavelength plate 8, is reflected by the polarization reflecting surface of the polarizing beam splitter 7, passes through the convex lens 11, and then is converted into a light beam by the mirror 12. is divided into two parts, one of which is input through a concave lens 15 to a two-part light receiving element 14 for detecting a focus error, and the other to a two-part light receiving element 15 for detecting a tracking error.

FIG. 5 is a block diagram showing an example of an optical recording/reproducing apparatus used in the present invention. In the figure, 1 is a disk, 17 is a photo sensor for detecting recording alignment marks,
1 is a waveform shaping circuit, 19 is a disk motor, 20 is a disk motor drive circuit that controls the disk motor 19 so that one rotation of the disk 1 corresponds to one frame of the video signal, and 21 is a video signal from a TV camera, etc. source, 22
25 is a recording signal processing circuit, 25 is a laser drive circuit, 24 is a keyboard for inputting the target guide track number to be searched, etc., and 25 is! 26 is a recording control circuit; 27 is a carriage on which the optical head 16 is mounted; 28 is a carriage motor for moving the carriage 27 in the disk radial direction; 29 is a carriage motor drive circuit; 50 is a ■-■ conversion processing circuit, 51 is a reproduction signal processing circuit, 52 is a TV receiver 55 is a focus control circuit, 54 is a tracking control circuit, 55 is an address demodulation circuit, and 56 is for detecting the presence or absence of a reproduction U signal. This is a town detection circuit.

The video signal from the video signal generation source 21 is modulated by the recording signal processing circuit 22, and is input to the laser drive circuit 25 as a video signal. If the recording/reproduction switching signal l from the recording control circuit 26 is high, the laser drive circuit 25 outputs a high (
Or, if it is low, during the low level, the output light of the laser mounted on the optical head 16 is intensity modulated according to the input U signal and irradiated onto the disk 1, and information is transmitted as a change in the reflectance of the laser source from the disk 1. record. Further, during reproduction, the recording/reproducing switching signal l from the recording control circuit 26 is set to low level if it is low (or high if it is high), and the laser driving time i! 25 irradiates the disc 1 with a low-output light beam of constant intensity, the recorded information is detected via the IV conversion processing circuit 50, demodulated by the reproduction signal processing circuit 51, and then transmitted to the TV receiver. Display the reproduced image on Great Machine 52.

The I-V conversion processing circuit 50 converts the current detected by a light receiving element (not shown) provided in the optical head 16 for receiving reflected light into a voltage, and converts the detected signal into a voltage. The high frequency component is sent to the reproduced signal processing circuit 51 and the F signal detection circuit 56, and the middle frequency component α is sent to the address demodulation circuit 55.
, the low frequency components are set as C to f by the focus control circuit 55'.
P6 and the tracking control circuit 54.

FIG. 4 is a circuit diagram showing a specific example of an r-vK conversion processing circuit 50 for converting the signals detected by the two-split light receiving element 14 and +5 in the optical head 16 from current to voltage. The detection current from the two-split light receiving elements 14 and 15 for focusing error detection and tracking error detection is divided into a high frequency component and a low frequency component by a resistor R and a capacitor C, respectively, and the high frequency component is transmitted through the capacitor C. The amplifier 571 converts the output signal into a voltage, and also the LPF.
(low-pass filter) 58 to become address signal demodulation signal α. The low-frequency components are each converted into a voltage by a resistor R, and then sent to a signal C for focus control and tracking control via buffer amplifiers 59, 40, 41, and 42.
~f.

Next, a method of checking the validity of the address information demodulated by the address demodulation circuit 55 will be explained. As mentioned above, in the disk 1 of this embodiment, the address signal is BO
The same signal is recorded three times in a row in each address area 4 with D5 digits and no parity. Therefore, if the address is demodulated correctly, the 5-digit BCD address will be 5
m will be the same number. However, due to causes such as scratches on the disc and dropouts, it is not always possible to demodulate in this manner. Therefore, the system controller 725 first takes a majority vote, as shown in FIG.
Check if the group has the same address information, and if it is 5@5,
This address information is considered invalid. A BCD check is performed on address information that passes the majority check.

As mentioned above, the address information is 5 digits in BCD. Also, one digit consists of 4 bits.

Since it is a BCD, the value of 4 bits per digit is 1010. ION.

1100, lj will never be 1.1110.1111. Conversely, if even one of the five digits of the address information has such a value, it should be considered that the address information has not been demodulated correctly, and this address information is invalidated. A range check is performed on address information that has passed the majority check and BCD check. The addresses of the guide tracks recorded on the disc 1 of this embodiment are 99000-99999, 00000-16
The range is 000.

Therefore, address information exceeding this range is also invalidated. Address information that passes the above checks is considered valid.

In addition to the above methods, there is also a method of checking whether the address information is sequentially increasing or decreasing when moving to the second adjacent track, and a method of performing a parity check by adding a parity bit when recording the address signal on the disk. is possible. This sequential check and parity check can be performed even when the address information is recorded in binary format instead of BCD.

The valid address information is once stored in a register in the system controller 25, and when the original beam spot moves from the inner circumference to the outer circumference (or from the outer circumference to the inner circumference) during normal playback etc., it is output from the waveform shaping circuit 18. The recording position alignment signal K is detected, and the value of the register is added or subtracted by the number of tracks moved based on this signal to indicate the address of the guide track after movement. If valid address information is read during movement, the register is updated.

If the valid address information was read, update the address information to the valid address information that was read.

The added or subtracted value of the register is regarded as unrestricted address information (hereinafter referred to as estimated address 8), and various processing is performed using this address information. For example, start searching for current light beams.

If valid address information cannot be read on the guide track where the pot is located (hereinafter referred to as the current track), this guessed address is used.

Compare with the address of the target guide truck and start searching.

Next, the basic operation when searching for an arbitrary guide track on the disc 1, that is, the case where the address information is not invalidated, will be explained with reference to FIG.

From the keyboard 24 to the system controller 25 in FIG.
After the search target guide track position N is input, the system controller 25 first reads the address information of the current track from the address return lJ early path 55, and calculates the location according to the address difference N-view.

Perform burial. In the case of this embodiment, the absolute value of the address difference is I
If N-A@l≧500, the absolute value IN-Ael of the address difference is preset in the drive circuit 29.

If the address difference N-A@6 is positive, the moving direction signal is set to a high (al or low) level, and if the address difference N-tori is negative, the moving direction signal is set to a low (or high) level. The optical head 16 is controlled by the drive circuit 29 using the trigger pulse iVc to control the carriage Saki-Yu 28.
move toward the target guide track at high speed.

The absolute value of the address difference is 500) I N - As l
> 1, then the absolute value of the address difference IN-A@
Sera I to the counter in the system controller 25.

Then, as above, set the moving direction signal 5.

Jump pulse! approximately 21 to the tracking control circuit 54.
+1 JF a The output is output until the counter 6% is OK in the e period, and the original beam spot is moved toward the target guide track by jumping over the track. At this time, in the case of a disk in which the perfect circular track is formed in a spiral shape, it is as shown in FIG. 7.

The light beam spot records the alignment mark 5.

If you cross the address area 4 on the side where you are located, you will move.

Look at the direction signal, jump pulse! 1 point regardless of.

It goes towards the outer circumference of the rack disk. Therefore,
The light beam spot is f! From the recording alignment signal KK detected when crossing the address area 4 on the side where the alignment mark 5 is located, the disk is detected.

When moving in the outer circumferential direction, the counter is decremented by 1, and the counter is decremented by 1.

When moving toward the intra-station area, adding 1 to the counter allows more accurate movement of the original beam spot.

The absolute value of the address difference is 1. If N-A41 = 1.

It moves by 1 degree track in the same way as during normal playback, and reaches the target guide track. , 5. After the drive circuit 29 and the tracking control circuit 54 finish moving the original beam spot (hereinafter simply referred to as "after one move"), the address information of the current track is read by the address demodulation circuit 55 and the address difference is verified again. , until the address difference becomes 0, the tracking control circuit 54
Alternatively, the target guide track is reached by repeating the search by moving one track. FIG. 9 shows a timing chart of the movement of the original beam spot and each signal during this period. In the figure, the period t.about.t1 is during high-speed movement by the drive circuit 29, t, .about.1t and t, .about.t4 are periods during which address difference verification is performed, and t and .about.t are periods during which the tracking control circuit 29 is moving at high speed.
When the light beam spot moves by track skipping K using 4, t4 to t1 is when moving by one track in normal mode (in the case of the same figure, because it moves toward the outer circumference of the disk,
The jump pulse l for skipping tracks is not output).

Next, the correct address information cannot be read on disk 1.
In other words, a case where a guide track exists that is invalidated in the validity check of the address information will be explained using an example of the software function block diagram shown in FIG. 10 and the flowchart shown in FIG. 6.

In FIG. 10, 45 is a function for detecting a portion where the track number is updated by the recording position alignment signal K output from the waveform shaping circuit 18, and 44 is an address demodulation circuit 55.
A function to read address information from 45, a function to check the validity of the read address information, 6 a register to store the address information determined to be valid by the check, and 47 search by input from the keyboard 24. A function for setting a target guide track number; 48 is a register for storing the set target guide track number; 49
50 is a function to compare the value of the target guide track number storage register 48 and the value of the valid address storage register 46, 50 is a function to control the search process according to the validity of address information, address difference, etc., and 51 is a movement direction. The function of controlling the drive circuit 29 by the signal signal and trigger pulse iK, 52 is the moving direction signal and jump pulse! This is a function to control the tracking control circuit 54 by.

After the movement is completed (if the address information read by the address information reading function 44 is determined to be invalid by the address information checker @45, the search control function 50 uses the tracking control circuit 54 control function to read the address information shown in FIG. When 6'4.g! becomes invalid, as shown in !, move track by track to find a guide track where valid address information can be read, and when valid address information 6'4.g! is obtained, it is stored in the valid address storage register 46. The address comparison function 49 compares the value of the target guide track number storage register 48 with the value of the effective address storage register 46.
Continue searching. Because valid address information could not be read after the 11th projection movement was completed, the
This is an example in which the address difference is verified while advancing track by track and valid address information is read, and the target guide track is reached. Of course, it is also possible to search for a guide track from which valid address information can be read while moving track by track toward the inner circumference of the disk. In addition, as shown in Fig. 12, we initially searched for a guide track from which valid address information could be read by advancing one track at a time in the direction of the disk's outer circumference, but if we could not find it even after advancing to a certain extent,
) I'll go rack by rack and look for it. It doesn't matter if it's 5K. By repeating these, even if there is a range in which valid address information cannot be read after the end of movement, it is possible to search if the target guide track is located outside this range.

However, if the target guide track is located in a range where valid address information cannot be read using only this method, it is conceivable that the same operation will be repeated without notice as shown in FIG. 15. A method that takes this into consideration will be explained using an example of the software function block in FIG. 14 and the 718+- chart in FIG.

In FIG. 14, the same functions as those in FIG. 10 are indicated by the same symbols and their explanations will be omitted. In Figure 14, 55
is an address information invalid range check counter 54 that counts the number of tracks moved in order to read valid address information after movement is completed; and a valid address storage register 46.
This kakunta is stored with the absolute value of the difference between the value of the target guide track number storage register 4B and the value of the target guide track number storage register 4B as an initial value.

If valid address information cannot be read after the movement is completed, a guide track from which valid address information can be read is searched for, as in the previous example, but at this time, if the atsys information in Figure 6 becomes invalid, as shown in IK. The address information invalid range check counter counts the number of tracks moved to read valid address information. For example, the 15th r.
! As shown in 1, after the movement is completed, move toward the outer circumference of the disk (BJ') and proceed to the rack to obtain valid address information Afk:R, and the address difference N-A is negative and the absolute value of the address difference is lN.
-Al≦IB! In the case of 1, it can be seen that the target guide track is located in a range where valid address information cannot be read. If the target guide track is located in a range where valid address information cannot be read, the absolute value I of the address difference is
N-Person 1 is stored in the address difference storage unit 54, and the track number is updated by the track number update portion detection function 45 while the tracking control circuit 54 control function 52 advances toward the inner circumference of the disc in normal reverse playback operation. The value of the address difference storage counter 55 is subtracted by 1.

In this way, the value of the address difference storage counter 55 becomes 0.
The target guide track can be estimated and searched for. Also, when the track number is updated, instead of decrementing the value of the address difference storage counter 55 by 1, the value of the effective address storage register 46 is decremented by 1, and the guide track that has the same value as the target guide track number storage register 48 is the target guide track. If you guess that it's a guide truck, you can search for it even if you try. If it is determined that the target guide track is not located in a range where valid address information cannot be read, the address information invalid range check counter 55
is cleared and the processing when the address information is valid is performed as shown in FIG. Also, as shown in Fig. 16, in order to search for a guide track from which valid address information can be read after the movement is completed, the BF track first moves toward the outer circumference of the disk, but since it is not found, the track is turned back. Even if the address difference N-A is positive and the absolute value of the address difference is lN-Al≦IBJil, the target information track is in a range where no valid address information can be read. It is determined that the location is located. In this case, the tracking control circuit 54 control function 52 causes the normal playback operation to proceed toward the outer circumference of the disc, and as described above, the address difference storage counter 54 is decremented by 1 or the effective address storage register 46 is decremented by 1 at the portion where the track number is updated. The target guide track is searched by adding up and ending the search at the guide track where the value of the address difference storage counter 54 becomes O or the value of the effective address storage register 46 becomes equal to the value of the target guide track number storage register 48. It would be possible to guess and search

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a disk, FIG. 2 is an explanatory diagram showing the configuration of an optical head, and FIG. 3 is a block diagram showing an example of an optical recording/playback device which is an example of the object of the present invention. 4 is a circuit diagram showing a specific example of the IV conversion circuit 50 in FIG. 5, and FIG. 5 is a circuit diagram showing a specific example of checking the validity of address information demodulated by the address demodulation circuit 55. FIG. 6 is a flowchart showing an example of the search method of the present invention, FIGS. 7 and 8 are explanatory diagrams showing the movement of the original beam spot by the tracking control circuit, and FIG. 9 is a flowchart showing the movement of the original beam spot by the tracking control circuit. FIGS. 10 and 14 are functional block diagrams of the search method of the present invention, and FIGS. 11 and 12 are examples of timing charts of the movement of the original spot and the corresponding signals of each part when the number is 8. FIG. 15, FIG. 15, and FIG. 16 are explanatory diagrams showing an example of the operation of an embodiment of the present invention. 1... Disc, 2... Guide track, S... Recording position alignment! - 4... Address area of guide track, 5... Laser diode, 6... Collimating lens, 7... Polarizing beam splitter, 8... Wave plate, 9... Actuator, 10 ...Objective lens, 11...Convex lens, 12...Mirror, 15...
Concave lens, 14.15...2-split light receiving element, 17...
・7 sensors for recording position alignment mark detection, 18...
Waveform shaping circuit, 19... Disk motor, 20... Disk motor drive circuit, 25... System controller, 2nd... Carriage motor, 29... Drive circuit, 54... Tracking control circuit, 25 ... Laser drive circuit, 16... Optical head, 50... I-V conversion processing circuit, 55-... Address demodulation circuit, 58...
LPF, 59-42...Buffer amplifier, 45-
...Track number update portion detection function, 44...Address information reading function, 45...Address information check function, 46...Valid address storage register, 48...
Target guide track number storage register, 49...Address comparison function, 54...Address difference storage counter, 50
...Search control function. Figure 1 12 Zugyo + Zuken 5 Figure 7th Day 8 Kiatsu / Figure 1 Atsushi / 2 Notebook Ia Figure 8A Koto (Trajectory ν1 TolF, Ri

Claims (3)

[Claims] (1) A means for reproducing address information from a disc-shaped or cylindrical recording medium in which guide tracks are formed in a straight line and address information indicating guide track numbers is recorded in forward or reverse order, and the reproduced address information. It has a means for comparing the address of the designated guide track, sets the absolute value of the address difference in a counter, outputs pulses until the counter reaches 0, and moves the information reading unit to the target guide track by track jumping operation. In a device that searches for a target guide track by moving the disc in a direction, the device is provided with means for detecting a portion where the track number is updated, and when a portion where the track number is updated during the search by track jumping operation is detected, the device moves in the search direction of the disk. A guide track position retrieval method characterized in that 1 is added or subtracted from a counter depending on the number of tracks moved, thereby eliminating an error between the counter and the number of moved tracks. (2) A means for reproducing address information from a disk-shaped or cylindrical recording medium in which guide tracks are formed in a straight line or concentrically, and address information indicating guide track numbers is recorded in forward or reverse order. If the address information is set up so that majority vote can be taken, then by majority vote, if it is BCD, by checking whether there is a digit with a value other than 0 to 9, or if a parity bit is added. A parity check is used to check the validity of the reproduced address information by checking whether the reproduced address information has an unrecorded value, and by combining these methods. If the reproduced address information is determined to be valid in a device having means for comparing the address information and the address of the designated guide track and means for moving the information reading unit in the disk radial direction, the valid address A register for storing information and a means for detecting the part where the track number is updated are provided, and the track number is updated when the information reading section is moved from the inner circumference of the disc to the outer circumference (or from the outer circumference to the inner circumference) during normal playback etc. part is detected, and the value of the register is added or subtracted by the number of tracks moved based on this to indicate the address of the guide track after movement, and the address information reproduced at the start of the search is invalidated. If a valid address information cannot be read during the search, the information reading section is moved until a guide track from which valid address information can be read is found. A guide track position retrieval method characterized in that a function is provided to compare addresses when valid address information is read. (3) In the device recited in claim 2, the number of guide tracks whose address information is invalidated is counted when the information reading unit is moved to find a guide track from which valid address information can be read. If the absolute value of the address difference is smaller than the absolute value of the counter and there is a guide track area in which the address information is invalid in the direction in which the target guide track is located, the target guide track receives valid address information. determine that the address is located in an unreadable range, set the absolute value of the address difference in a counter, and decrement the counter by 1 every time it moves one track in the direction of the target address until the counter reaches 0, or When moving in the direction of the target address during normal playback, etc., and detecting a portion where the track number is updated, the register storing the valid address information is subtracted or added by 1, and the value of this register becomes the target guide track number. A guide track position retrieval method characterized in that a target guide track can be estimated and searched by moving until a match is made.