JPH0676501A - Circuit for counting number of moving track, head speed control circuit and high-speed access control circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] In a storage / playback device that uses a rotating medium, in the access that moves the optical table with the head at high speed,
Accurate track counting is performed by using the speed control of the head and the method of softly counting moving tracks. According to a moving direction signal of a head moving direction detecting means 5 and a change amount of a primary track counter 6 for counting the number of moved tracks at a constant time, the head moving direction and the number of moved tracks can be determined. Accurate track counting is provided by providing a secondary track counter 11 that counts moving tracks by software, and by providing a correction amount calculating means 10 that corrects an erroneous count amount due to erroneous detection of a moving direction signal. In addition, according to the moving speed of the head during access, which is obtained by the moving speed detecting means 13, when the head is overspeed, the head control means 14 outputs a command for decelerating the head speed to keep the head moving speed within a certain range. As a result, it is possible to stabilize signal detection and further improve the reliability of track count during high-speed access.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a storage / reproducing apparatus equipped with a rotating disk-shaped recording medium and the like in a radial direction of a head, and an optical stand on which the head part is mounted is traversed by a traverse motor or the like. The present invention relates to a control circuit for moving a traversing track at a high speed while counting, in particular, counting the moving tracks and controlling a head during high-speed movement by software.

[0002]

2. Description of the Related Art In a recording / reproducing apparatus which has been developed in recent years and uses a disk-shaped storage medium such as an optical disk, a magnetic disk or a compact disk for recording / reproducing information, the head is accessed for a relatively long distance. In this case, a method of moving the optical table on which the head is mounted at high speed and accurately by a traverse motor is used.

In this high-speed access, the optical stand is moved while the positioning control of the head in the focal direction of the disk is carried out and the positioning control in the radial direction is not carried out. At this time, the head is moved by the target number of tracks by counting the number of tracks traversed by the lens at the time of movement by counting the zero crosses of the positional deviation signal (TE) in the radial direction.

An example of the above-mentioned conventional high-speed access will be described below with reference to the drawings.

FIG. 9 shows a time chart when a conventional high speed access is executed. In the figure, from the state of reproduction (area 1), the radial direction control (TKO) is turned off, the traverse motor is given a feed command (TVO), and high-speed access is started. During high-speed access (area 2), the position shift signal (TE) is converted into a binarized signal (TZC) by a comparator, and the rising or falling of the binarized signal (TZC) is set as the number of moving tracks, and the hardware is used. Or count with software. When the number of moving tracks reaches the target number, the feed command to the traverse motor is stopped, the radial direction positioning control (TKO) is turned on, and the reproduction state is entered (region 3).

[0006]

However, in the above-mentioned structure, since the radial positioning control is turned off, the head moves relative to the target access direction at a low speed immediately after the head access is started in a disk with large eccentricity. When moving in the opposite direction, or when vibration is applied from the outside, the head is accelerated so much that the tracks cannot be counted normally. Further, even when the head is abnormally accelerated, the position shift signal (TE) and the binarization signal (T
It is necessary to widen the signal band of the circuit in order to detect ZC), but the number of moving tracks cannot be ensured due to signal noise or the like, or the signal can easily be erroneously detected. There was a problem that it could not be counted accurately.

[0007]

In order to solve the above problems, the high-speed access control circuit of the present invention counts the moving direction of the head and the rising edge of the track cross signal in counting the number of moving tracks. Equipped with a track counter that adjusts the amount of change in the track counter at regular intervals depending on the head movement direction to eliminate erroneous counting of moving tracks due to head movement in the opposite direction, and to move the head with the correction track counter. The number of moving tracks is counted more accurately by correcting the wrong count of moving tracks due to erroneous detection of the direction signal.

Further, the relative speed / relative moving direction of the head with respect to the track is detected at regular intervals from the values of the moving direction detecting means and the track counter, and when the moving speed exceeds a certain speed, the head is moved. The head overspeed is suppressed by applying a constant value control signal for decelerating the head drive means to the head drive means, and performing on / off control to give a zero output to the head drive means when the moving speed is equal to or lower than a constant speed. , The head is controlled within a certain speed range.

Further, when the head is moved at a high speed, the above-mentioned track counting method is used for counting the number of moving tracks, and a head speed limiting circuit for limiting the moving speed of the head is provided so that the track count can be accurately detected. It is configured to be added.

[0010]

According to the present invention, the number of moving tracks within a fixed time is added / subtracted according to the moving direction of the head by the above structure,
Erroneous counting due to backward movement is eliminated, and by providing the correction track counter, erroneous counting due to erroneous detection of the moving direction signal can be reduced, and the number of head moving tracks can be accurately counted.

Further, by detecting the moving speed of the head and controlling the head so as to keep the moving speed of the head within a fixed speed, the number of tracks can be always accurately counted even under external vibration.

[0012]

【Example】

(Embodiment 1) A track count circuit according to a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a track count circuit according to the first embodiment of the present invention, FIG. 2 is a diagram showing the principle of head movement direction detection in the first embodiment of the present invention, and FIG. 6 is a flowchart showing the operation of the software counter in the first embodiment. In FIG.
Reference numeral 1 is a reproduction signal detecting means for detecting a signal recorded on a medium, and 2 is a binary signal indicating whether the head position is on the mirror portion (mirror surface portion) or the track portion (signal portion) of the medium from the reproduction signal. Mirror signal detecting means 3 for detecting, position deviation signal detecting means 3 for detecting the amount of positional deviation between the head and the track on the medium in the radial direction, and 4 binarize whether or not the head has crossed the track from the position deviation signal. Track cross signal detecting means 5 for detecting as a signal is a moving direction detecting means for detecting the moving direction of the head from the mirror signal detecting means 2 and the track cross signal detecting means 4 according to the principle shown in FIG. Is a primary track counter, 7 is a counter change amount detecting means for obtaining a change amount ΔN of the primary track counter 6 at constant time intervals T1, and 8 is a track change counter. A correction track counter for storing the count amount M of the primary track counter 6 from the time when the moving direction DIR changes from the true moving direction for correcting the count, and 9 stores the true moving direction TDIR. The moving direction storage means 10 is a correction amount calculating means for calculating a count correction amount from the moving direction storage means 9 and the correction track counter 8, and 11 is the number of tracks moved by the head in the moving direction DIR, counter change amount ΔN and correction. A secondary track counter that counts based on the amount, and 12 is a sampler for a fixed time T1.

The operation of the moving track counting circuit configured as described above will be described. Figure 2 (a)
Shows the operating principle from the reproduction signal detecting means 1 to the head moving direction detecting means 5 in FIG. 2 (b) is shown in FIG.
(A) The waveform of each part is shown. The mirror signal detection means 2 detects the dark level envelope of the output RF from the reproduction signal detection means 1, waveform-shapes it, and outputs it as a mirror signal. Further, the track cross signal detecting means 4 waveform-shapes the output TE of the position shift signal detecting means 3 to form the track cross signal T.
Output ZC. The moving direction detecting means 5 obtains the head moving direction signal DIR by latching the mirror signal at the rising edge of the track cross signal. Also, in FIG.
The next track counter 6 counts the rising edges of the track cross signal TZC to obtain the number of moving tracks. The above operations are performed by hardware.

Next, the operation of counting tracks by software will be described with reference to the flowchart of FIG.

Step 1: Initialize variables used for track counting. Here, N is a count variable of the moving track, M is a variable for storing the track count number after the movement direction signal is changed, and T is a timer variable for measuring the time after the movement direction signal is changed. .

Step 2; Wait until the predetermined time T1 is reached. Step 3: primary track counter 6 at time interval T1
At the same time as obtaining the change amount ΔN of the moving direction signal DIR, the moving direction signal DIR at the same time is checked.

Step 4; Addition / subtraction of the secondary counter is determined according to the value of the movement direction signal DIR. Here, when the movement direction signal DIR is "L", the head moves in the outer peripheral direction.
It is assumed that the head is moving in the inner circumferential direction at the time of H '. Further, the secondary track counter 11 counts up when the head moves in the outer peripheral direction and counts down when the head moves in the inner peripheral direction.

Step 5: When the outer circumference is being moved,
Count up (N = N + ΔN).

Step 6; When the inner circumference is being moved,
Count down (N = N-ΔN).

Step 7: The movement direction signal DIR is the true movement direction signal TD stored in the movement direction storage means 9.
Check if it is equivalent to IR.

Step 8: As a result, if the values are not the same, it cannot be determined whether the moving direction has changed or the moving direction signal DIR has been erroneously detected. Therefore, the timer starts counting the time T after the movement direction signal DIR changes.

Step 9: It is checked whether or not the time T is longer than the constant time T3. Step 10: If it is shorter, the correction track counter is operated and the number of moving tracks during this period is successively stored.

Step 11: On the contrary, if it is long, it is judged that the moving direction of the head has changed, the current moving direction signal DIR is stored in the moving direction storage means 9 and the correction counter 8 is reset (M = 0) The number of moving tracks up to time T3 is accurately counted in steps 5 and 6.

Step 12: If the moving direction signal DIR and the true moving direction signal TDIR have the same value, check whether the time T is 0 or not. Step 13: If the time T is not 0, the moving direction signal DIR changes. It is necessary to determine that the movement direction signal DIR has changed again in less than the time T3, that is, to erroneously detect the movement direction signal DIR, and correct the erroneous count of the number of moving tracks due to the erroneous detection. Therefore, the value of the true movement direction signal TDIR is checked. Step 14; if the true movement direction signal TDIR is'L ', the head is erroneously detected while the head is moving to the outer circumference, and the track count N is M count. However, since the count is reversed, the count correction (N = N + 2M) is performed with the 2M count as the correction amount.

Step 15; If TDIR is'H ', step 15 is reversed to perform count correction. (N
= N-2M) Step 16; After the correction of the erroneous count amount due to the erroneous detection of the movement direction signal DIR is completed, the correction track counter M and the time T are reset.

FIG. 4 shows a time chart of an example of the track counting method of the present invention. Here, T3 = 3. Even when the moving direction signal DIR is erroneously detected, the erroneous count amount is corrected in the next cycle. Further, even when the moving direction is reversed, the countdown can be accurately performed and the number of moving tracks can be accurately counted.

By adopting the above operation during high speed access, it is possible to accurately count the number of moving tracks without erroneous counting when the head moves in the direction opposite to the target moving direction. Further, even when the moving direction signal DIR is erroneously detected due to a defect of the medium or the like, the track correction can be performed more accurately by providing the count correction function.

(Embodiment 2) A head speed control circuit according to a second embodiment of the present invention will be described with reference to the drawings.

FIG. 5 is a block diagram of a head speed control circuit according to the second embodiment of the present invention. 1,
Reference numerals 2, 3, 4, 5 and 6 are the same as those in the first embodiment, and 13 is a moving speed detecting means for detecting the moving direction and moving speed of the head from the primary track counter 6 and the moving direction detecting means 5,
Reference numeral 14 is a head control means for deciding a control output to the head according to the head moving speed obtained by the moving speed detecting means,
Reference numeral 5 is a head driving means for driving the head according to the control output, and 16 is a sampler for a fixed time T2.

The operation of the head speed control circuit configured as described above will be described with reference to the flowchart of FIG.

Step 21: Wait until the predetermined time T2 is reached. Step 22: The moving speed detecting means 13 determines the moving speed V of the head from the change amount of the primary track counter 6 during the time T2 and the moving direction detecting means 5.

Step 23: Check whether the head moving speed V is faster or slower than the speed limit V _LM . Step 24: As a result, if the moving speed is slow, the head control output is not output. (E = 0).

Step 25: If the moving speed is fast,
A constant value of size E ₀ is output in the direction of decelerating the head (E = −E ₀ · sgn (V)).

FIG. 7 shows a time chart of high speed access when the head speed control circuit is operated. When the moving speed becomes faster (when the frequency of the track cross signal becomes faster), the head moving speed can be decelerated by giving a pulsed head control output (TKO).

By performing the above operation during high-speed access, it is possible to easily suppress the head from being unnecessarily accelerated due to external vibration or the like, and it is possible to accurately detect the head moving direction signal and the track cross signal. You can

(Embodiment 3) A high speed access control circuit according to a third embodiment of the present invention will be described with reference to the drawings.

FIG. 8 is a block diagram of a high speed access control circuit according to the third embodiment of the present invention. 1,
2, 3, 4, 5, and 6 are the same as those in the first and second embodiments, and 7, 8, 9, 10, 11, and 12 are 13, 14, 15, and 16 as in the first embodiment. Is the same as in the second embodiment. During high-speed access, the moving track counting circuit of the first embodiment counts the moving tracks, and the head speed control circuit of the second embodiment allows the head moving signal and the track cross signal to be accurately detected. By suppressing the speed, the target track movement can be accurately realized even when vibration is applied from the outside.

[0039]

As described above, according to the present invention, the number of moving tracks required for high speed access is configured by the up / down counter according to the moving direction of the head, and
A secondary track counter equipped with a count correction function at the time of erroneous detection of the moving direction signal is provided in order to eliminate erroneous detection due to erroneous detection of the head moving direction signal, and the moving speed of the head is suppressed to suppress erroneous detection of these signals. By controlling the head so that the signal is accurately detected within a range where signals can be accurately detected, the number of moving tracks can be accurately counted when the access is performed by the high-speed movement of the optical table.

[Brief description of drawings]

FIG. 1 is a block diagram of a moving track counting circuit according to a first embodiment of the present invention.

2A is a block diagram showing the principle of head movement direction detection in the embodiment of the present invention. FIG. 2B is a signal waveform diagram of each part in FIG. 2A.

FIG. 3 is a flowchart showing the operation of the moving track counting circuit in the first embodiment of the present invention.

FIG. 4 is a time chart showing the operation of the moving track counting circuit in the first embodiment of the present invention.

FIG. 5 is a block diagram of a head speed control circuit according to a second embodiment of the present invention.

FIG. 6 is a flowchart showing the operation of the head speed control circuit according to the second embodiment of the present invention.

FIG. 7 is a time chart showing the operation of the head speed control circuit according to the second embodiment of the present invention.

FIG. 8 is a block diagram of a high speed access control circuit according to a third embodiment of the present invention.

FIG. 9 is a time chart of a high-speed access operation of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 reproduction signal detection means 2 mirror signal detection means 3 position shift signal detection means 4 track cross signal detection means 5 moving direction detection means 6 primary track counter 7 counter change amount detection means 8 correction track counter 9 moving direction storage means 10 correction Quantity calculating means 11 Secondary track counter 12, 16 Sampler 13 Moving speed detecting means 14 Head controlling means 15 Head driving means

Claims (3)

[Claims] 1. A moving direction detecting means for detecting a moving direction of a head, a means for sampling an output of the moving direction detecting means for a short time, and outputting an instantaneous moving direction in this period, and a number of times the head has crossed a track. Of the primary track counter, a counter change amount detecting means for sampling the value of the primary track counter for a short time, and detecting a change amount of the count value during the period, and a movement for storing the head moving direction. A direction storage means, a correction track counter for summing the values of the counter change amount detection means when the instantaneous movement direction of the head differs from the contents of the movement direction storage means, the movement direction storage means and the correction track A correction amount calculation means for calculating a correction amount from a counter, an output of the counter change amount detection means and a correction amount calculation means. Moving track counting circuit and a secondary track counter for subtracting by considering the previous term instantaneous movement direction force. 2. A moving direction detecting means for detecting a moving direction of the head, a means for sampling an output of the moving direction detecting means for a short time and outputting an instantaneous moving direction in this period, and a number of times the head has crossed a track. Of the primary track counter, a sampler for sampling the value of the primary track counter for a short time, and a relative moving direction and movement between the head and the medium by the instantaneous moving direction and the value of the primary track counter. A moving speed detecting means for detecting the speed, a head control means for limiting the speed of the head when the moving speed is a predetermined value or more, and a head driving means for driving the head by the output of the head controlling means are provided. Head speed control circuit. 3. A reproduction signal detecting means for detecting a signal recorded on a medium, a mirror signal detecting means for detecting whether the signal is a signal from a mirror portion or a signal from a track portion, and a position for detecting a positional deviation. A shift signal detecting means, a track cross detecting means for generating a binary signal of the position shift signal, a means for detecting a moving direction of the head from the previous mirror signal and the track cross signal, and a head from the track cross signal. 2. A moving track counting circuit according to claim 1, wherein a primary track counter for counting the number of times of crossing a track, a moving track counting circuit for counting the number of moving tracks from the outputs of said moving direction detecting means and said primary track counter.
3. A high speed access control circuit comprising the head speed control circuit according to claim 2, wherein the head speed is limited within a fixed range based on the output of the moving direction detecting means and the output of the primary track counter.