JP2670054B2 - High-speed search method for disc players - Google Patents

Description

TECHNICAL FIELD The present invention relates to a search method for searching a target address on a disc in a disc player. BACKGROUND ART In a disc player playing an information recording disc (hereinafter, simply referred to as a disc) in which information signals such as a video format signal and an audio signal are recorded in a track shape together with address data, in a disc player, a pickup for reading the information signal from the track is a disc. It is carried by a slider that can move in the radial direction, and reads address data, such as frame number, block number, chapter number, performance time required from the reference position to the track position recorded on each track, that is, position information. The target address data is searched by controlling the position of the pickup based on the result of comparison between the current address of the data block currently being played and the target address of the target data block to start playing. To play the information in the desired order All random access is possible. As a method for searching for such address data, for example, a method described in JP-A-58-62868 can be mentioned. In this conventional method, the pickup moves closer to the target address by performing a so-called scan operation while adjusting the moving speed of the slider in the disk radial direction, that is, the scanning speed, while comparing the address data obtained from the pickup with the target address data. is there. In the conventional address data search method described above, the scan speed must be less than or equal to the speed at which the address data can be sequentially read, and if the difference between the current address and the target address is large, the time required for the search becomes long and quick random access is performed. Was not always easy to say. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a high-speed search method in a disc player capable of performing quick random access. To achieve the above object, the present invention provides a coarse servo loop by a slider for displacing a pickup for reading an information signal recorded in a track on a disc in the radial direction of the disc, and an information detection point of the pickup as a track of the disc. A high-speed method for searching a target address in a disk player, which includes a tracking servo loop for following up, wherein the tracking servo loop is opened, and the slider is accelerated according to a predetermined level signal supplied to a drive unit of the slider. An acceleration / deceleration movement control mode for decelerating backward and a constant velocity movement control mode for controlling the slider at a constant velocity on the basis of the address data while obtaining the address data from the read signal from the pickup are prepared. From the current position of When the detected distance is greater than a predetermined value, the acceleration / deceleration movement control mode is executed and then the constant speed movement control mode is executed to turn on the tracking servo loop, When is smaller than the predetermined value, the tracking servo loop is turned on after executing the constant velocity movement control mode without executing the acceleration / deceleration movement control mode. EXAMPLES Hereinafter, examples of the present invention will be described. First, a disc player for executing the search method according to the present invention is firstly described.
This will be described with reference to the drawings. In FIG.
The upper track is irradiated with a light beam from the pickup 2 to form an information detection spot, and the reflected light is converted into an electric signal by a photoelectric conversion element in the pickup, and the recorded information signal is read as a so-called RF signal. The information detection spot of the pickup 2 is swingable with respect to the slider 3. The slider 3 is driven by a quick-response drive motor 14 such as a linear motor of the MC type or a rotary motor having a small moment of inertia, and thereby moves in the forward and reverse directions in the disk radial direction. The RF signal (a) is demodulated into a video format signal by the demodulation circuit 4 and supplied to the data demodulation circuit 5. The demodulation circuit 4 reads address data such as a frame number and a time code from the data portion of the video format signal and supplies it to a microprocessor (hereinafter, simply referred to as an MPU) 6. Target address data to be searched is supplied to the MPU 6 from the input means 7 such as a keyboard, and the target address data is stored in the memory 20. The pickup 2 is provided with a light receiving element for performing tracking servo in addition to the light receiving element for detecting an RF signal, and its output is supplied to a tracking control circuit 8 as a tracking error signal (b). The tracking control circuit 8 supplies a tracking unit drive signal (d) to the pickup 2 based on the tracking error signal (b) under the tracking-on signal (c) from the MPU 6 to perform so-called tracking servo. When the tracking servo is locked, a tracking block signal (e) is supplied to the MPU 6. The tracking control circuit 8 supplies the average value of the tracking error signal (b) to the motor control circuit 12 as a slider servo signal (f). The motor control circuit 12 receives a control command (g) from the MPU 6 to command the slider servo. As long as there is, the voltage generation circuit 13 is instructed to generate a voltage corresponding to the slider servo signal, and the voltage generation circuit 13 supplies the output voltage to the slider motor drive circuit 9. The control command (g) further includes an acceleration command, a deceleration command, a constant speed servo command, and a stop command. The amplitude of the tracking error signal (b) changes sinusoidally when the information reading point crosses the track.
A signal obtained by shaping the tracking error signal (b) from the tracking control circuit 8 is supplied to the track counter 10 as a track crossing signal (h), and the number of tracks at which the information reading points cross is integrated. Note that the envelope detection output of the RF signal can be used as a track crossing signal. The integrated value (j) of the track counter 10 is supplied to the MPU 6 and is cleared by a reset signal (k) from the MPU 6. Also, the track counter 10 can be directly set at the initial stage. The MPU 6 samples the integrated value (j) and detects the moving speed of the slider 3 from the rate of change, that is, the difference between the previous value and the current value of the sample value. The speed signal Vact representing the moving speed of the slider 3 is a motor control circuit. Supplied to 12. Note that the moving speed may be obtained from the zero-cross cycle of the tracking error signal (b). The memory 20 stores a control program for the MPU 6, signal data, deceleration data described later, and the like. A jump command signal (l) is supplied from the MPU 6 to the tracking control circuit 8. The tracking control circuit 8 performs a jump corresponding to the content of the jump command signal (l) regardless of the tracking error signal. Forcibly rock the tracking unit. The motor control circuit 12 generates positive or negative voltage output data for setting the moving direction, speed, and braking force of the slider 3 according to the content of the control command (g), and supplies the output data to the voltage generation circuit 13. The voltage generation circuit 13 converts the voltage output data into a voltage signal and supplies the voltage signal to the slider motor drive circuit 9. The slider motor drive circuit 9 supplies an operating current according to the voltage signal to a responsive drive motor 14 such as a linear motor that urges or depresses the slider 3 in the forward or reverse direction in the disk radial direction. The spindle motor 15 for rotating the disk 1 is an MPU 6
The disk rotates at a constant rotation speed for a so-called CAV disk and at a constant linear speed for a CLV disk by a spindle servo circuit 16 that operates in response to a command from the CPU. Next, the operation of the apparatus will be described with reference to the control flowchart of FIG. First, a target address at which performance is to be started by an operator from input means such as the keyboard 7 is supplied to the MPU 6 together with a search command and stored in the memory 20. In the case of a CAV disk, the frame number and the track number inserted in the address data portion of the video format signal correspond to each other, so that this frame number can be used as the address data. A tracking servo is commanded to the tracking control circuit 8 (step S21). It reads the target frame number F _TGT to be searched stored in the memory 20 (step S22), and reads the frame number F _P of the current address exists a pickup from the output of the data demodulator circuit 5 (step S23). Target frame number F _TGT and the current obtaining subtraction value D of a frame number F _P (step S24). The direction of movement of the slider is determined by the sign of the value of D. When the subtraction value | D | is 0, the process ends (step S25). If the subtraction value | D | is less than 11 and not 0, for example, a single jump is commanded to the tracking control circuit 8 (steps S26 and S27). Subtraction value | D
When | is, for example, 11 or more and less than 256, the multi-jump subroutine is executed (steps S28 and S28Y). When the subtraction value | D | is, for example, 256 or more and less than 3072, a target address search is executed by a target scan subroutine described later (steps S29 and S29Y). If the absolute value of the subtraction value D is, for example, 3072 or more, a target address search is performed by a high scan subroutine described later (steps S29 and S29N). That is, in the embodiment, for the search of the target address, as described below, 4 times according to the subtraction value, that is, the distance | D |
Step routines are provided. (1) Single jump (close-up distance) frame number difference …… 1 to 10 (search time ≤100ms) (2) Multi-jump subroutine (short distance) frame number difference …… 11 to 255 (search time ≤200ms) ( 3) Target scan subroutine (medium distance) frame number difference ... 256 to 3071 (search required time ≤ 300 ms) (4) High scan subroutine (long distance) frame number difference ... 3072 to 54000 (search required time ≤ 500 ms) The subroutine will be described. The single jump is performed only by the tracking control. When the tracking servo is locked and the frame number is read, the difference between the current frame number and the target frame number is calculated to determine the number of single jumps and the jump direction, and the tracking unit swings to detect the information detection spot. The single jump for moving to the next track is repeated at intervals of 1 [ms] by the amount corresponding to the above number difference, and the tracking servo is turned on to read the target frame number, thereby completing the process. The multi-jump subroutine will be described with reference to FIG. Each time the tracking unit of the pickup swings, a so-called multi-jump in which the information detection spot continuously crosses tracks up to, for example, 100 tracks is performed. First, clear the track counter 10,
The moving direction of the pickup 2 is set based on the sign of the subtraction value D (step S31). A multi-jump command is issued to the tracking control circuit 8 (step S32), and the tracking unit swings. When the value Nt of the track counter 10 is increased by the number of intersecting tracks and exceeds 100 (step S33), a stop of the multi-jump command is issued,
The multi jump ends (step S34). If the speed at which the information detection spot crosses the track by the multi-jump is set to 10 × 10 ³ (hereinafter referred to as 10K) [track / s], the time required for one multi-jump of the 100 tracks is about 10 [ms] ]. Upon completion of this subroutine, the process returns to step S21 in FIG. For the target scan subroutine,
This will be described with reference to the control flowchart of FIG. The target scan subroutine is in the acceleration stage (step S5
0 to S52), a constant speed stage (steps S53 to S60), and a convergence stage (corrected multi-jump, corrected single jump) not shown. First, if the HS flag described later is not 1 (step S4
1) The counter reset signal (k) is sent to the track counter 1
It is supplied to 0 to clear the integrated value (step S50), and issues a slider acceleration command to the motor control circuit 12 (step S51). In response to the acceleration command, the motor control circuit 12 supplies either positive or negative voltage level data to the voltage generating circuit 13 according to the positive or negative of the subtraction value D, for example. At this time, a predetermined acceleration voltage is supplied from the voltage generation circuit 13 to the slider motor drive circuit 9, and the acceleration of the slider 3 is started. The current speed Vact of the slider is, for example, a predetermined speed V of 9K [track / s].
continued acceleration instruction to over r ₁ (step S51~S5
2). When Vact exceeds Vr ₁ speed to (step S52), forming a constant speed servo to pull the upper limit speed Vr ₂ below V _C of the demodulated possible example 18K of the data portion of the slider speed video format signal [track / s] supplying a set signal V _S to the motor control circuit 12 (step S53). Speed setting signal V _S
Is a value obtained by multiplying the coefficient of the servo system G to the speed difference between the current speed Vact and the target speed V _C, indicated by the subtraction value between the reference speed V _C. The motor control circuit 12 instructs the relative voltage generating circuit 13 which may arise a voltage corresponding to the speed setting signal V _S. Speed servo is performed by repeating step S53. When the current speed Vact of the slider becomes V _C [track / s] (step S54), the demodulation of the frame number from the data demodulation circuit 5 is monitored (step S55). As the slider moves a certain distance, a certain percentage of the time the information detection spot scans the address data portion on the track occurs. When the frame number is read in this way, the track counter 10 that accumulates the number of intersecting tracks is read.
Is replaced with the frame number to set an accurate current address (steps S55 and S56). If the frame number (j) has not been read, the accumulation of the track counter is continued (step S55). Number of tracks from the reference position to the target track including the target address, with the integrated value Nt of the track counter as the current address (step S57)
That is, the value obtained by subtracting the integrated value Nt from N _TGT calculates the remaining distance N _D (step S58). The remaining distance N _D is a predetermined distance corresponding, for example, 200 tracks the movement distance in the convergence region N
_When it becomes less than _D1 (step S59), a slider stop command is issued to the motor control circuit 12 (step S60). Otherwise, steps S53 to S59 are repeated. Upon completion of this subroutine, the process returns to step S21 in FIG. When the HS flag is 1 in step S41, it indicates that the high scan subroutine described later has been completed and this subroutine should be executed. At this time, a constant speed servo pull-in subroutine is executed. First, for example, 54K [tra
ck / s] at a predetermined speed _VA (step S42). When Vact drops V _A (step S43), for example, it commands the constant speed servo of a predetermined velocity V _B of 36K [track / s] (step S44). When Vact drops to V _B (step S
45), and proceed to step S53. By shifting from the high scan subroutine to the target scan subroutine via the constant speed servo pull-in subroutine, the slider is settled at an early stage, and a smooth shift to the constant speed region is achieved. In this way, in the constant speed region, the address accuracy is read while moving the slider at a relatively high speed, and the correction of the integrated value of the track counter is repeated, thereby increasing the counting accuracy. Here, the description of the operations in steps S56 to S59 will be added. In a commercially available optical video disc, address data such as a frame number of video information is inserted into, for example, the 17th and 18th scanning lines of the first field. When the slider is moved, the maximum speed at which the code can be read from the disk is when the information detection spot traces for 1H (63.5 μS). Maximum number of tracks on CAV disk is 5
There are 4000 tracks, and the slider movement time T required to cross the track is T = 63.5 × 10 ⁻⁶ × 54000 = 3.4 [S]. When the slider is moved at the maximum speed at which the address data can be demodulated, the address data becomes one revolution of the disk (3
3.3 [ms]), the number of tracks traversed while reading address data is 54000 / 3.4 × 3
It becomes 3.3 x 10 ^-3 = 529 [track]. Therefore, if the search is performed only with the address data, the reading accuracy cannot be reduced to 529 tracks or less. On the other hand, when the number of tracks crossed by the information detection spot is integrated by the track counter, scratches on the disc,
When the dust, noise, hocus error, and slider speed are set to 8 kHz or less, which is affected by disk eccentricity (for example,
The maximum speed of crossing tracks due to eccentricity of the disk is 8kHz
The maximum speed at which address data can be read is approximately 18
kHz), a count error occurs. Therefore, in the search, the reading of the address data and the tracking counter are used together to periodically correct the integrated value of the track counter to an accurate value by the frame number as the address data, thereby eliminating the counting error each time. The detection accuracy of the current address increases. Further, since it is not necessary to stop the slider and lock the tracking servo and demodulate the address data as in the related art, there is an advantage that the search time is shortened. In the case of a CAV disc, address data can be demodulated while the tracking servo is turned off and the slider is moved in the disc radial direction, but in the case of a CLV disc, the recording signal of each track is recorded in synchronization with the disc radial direction. Therefore, the tracking servo is turned on intermittently or continuously and the slider is moved to oscillate the tracking unit of the pickup to trace the track for a certain period to perform data demodulation. Another control mode of the target scan subroutine will be described with reference to FIG. Step S5 in FIG.
Steps S0 to S54 are the same as steps S50 to S54 in FIG. 4, and a description of such parts will be omitted. First, when the constant speed servo is performed, the address data is demodulated from the data demodulation circuit 5 and supplied to the current address storage area of the memory 20 via the MPU 6 to update the current frame number F _P (step S71). ), A reset signal is issued to the track counter 10 to clear the integrated value (step S72). Memory 2
The current frame number F _P and the target frame number F _TGT are read from 0 to calculate the remaining distance D (steps S73 to 74).
Stop distance (number of stopped tracks) d corresponding to the current speed Vact
Is stored in the memory 20 in advance as a data map.
(Step S75). The stop distance d is subtracted from the remaining distance D to calculate a corrected remaining frame number Dcrt (step S76). The integrated value Nt of the track counter 10 is read (step S77) and compared with the number of remaining frames to be corrected Dcrt (step S78). When the integrated value Nt exceeds the correction remaining frame Dcrt, the constant velocity servo is ended, the slider is stopped, and this subroutine is ended (step S79). Otherwise, the process is repeated from step S71 (step S78).
When the frame number F _P is not updated in step S71 reads the accumulated value difference Nt of the track counter executes step S77, S78, to determine the termination timing of the slider. Thus, every time the correct current address _FP is demodulated, the number of remaining frames D is calculated, the integrated value of the track counter 10 is cleared, and the number of crossing tracks Nt of the information detection spot and the number of remaining frames of correction Dcrt after that are cleared. Since the stop time is determined by comparing with the above, the detection accuracy of the current address is high, and the influence of a count error caused by a scratch or dust on the disk is small. Further, since the stop distance d after the start of braking due to the inertial force of the slider is corrected in advance, it is possible to prevent overrun of a slider having a small frictional resistance, such as a slider urged by a linear motor. FIG. 6 shows an example of a change in slider speed when a search operation is performed from the target scan subroutine. The high scan subroutine will be described with reference to FIG. In the high scan subroutine, open control is performed in the acceleration stage and the deceleration stage (steps S104 to S117), and thereafter, the process proceeds to the above-described target scan subroutine. When the high scan subroutine is selected in step S29 of FIG. 2, the number of tracks N _B in the constant velocity region and the convergence region described above is subtracted from the distance D to calculate the number of tracks that the slider should cross in the acceleration region and the deceleration region. To do. For example, 3600 tracks (18K [t
rack / s] × 200 [ms ]) is information detecting spots in the acceleration region and the deceleration region the number of tracks obtained by subtracting the the acceleration and deceleration region track number N _J to be crossed (Step S102). Issues a reset command for the track counter 10 (step S10
3). A slider acceleration command is issued to the motor control circuit 12 (step S104). At this time, the voltage generation circuit 13 generates the maximum voltage, for example, and starts the movement of the slider 3. It reads the accumulated value Nt of the track counter 10, calculates the remaining number of tracks Nrmg in acceleration and deceleration regions by subtracting the Nt from N _J (step S105, S106). After estimating the frame number Fpp of the current address from Nt (step S107), a deceleration command is given to the motor control circuit 12 within the range of the frame number corresponding to the estimated frame number Fpp and the acceleration / deceleration area end track number to brake the slider 3. The deceleration K at this time is read from a deceleration data map described later (step S108). Expected remaining number of tracks that the information detection spot will cross from the start of braking until the slider stops. Ndcl = Vact
^It is calculated by ² / 2K (step S109). The derivation of this equation will be described later. When Ndcl exceeds Nrmg, the acceleration command is canceled and the deceleration command is issued to the motor control circuit 12 (steps S110 and S111). The motor control circuit 12 generates a predetermined braking voltage in the voltage generation circuit to stop the slider 3 in response to the deceleration command. When Ndcl does not exceed Nrmg,
Steps S105 to S110 are repeated through a wait cycle (step S112) in which the sampling interval is 0.5 [ms], for example. Reads the accumulated value Nt and acceleration and deceleration regions track number N _J to calculate the remaining number of tracks Nrmg the acceleration region (step S113, S114). When the number of remaining tracks Nrmg becomes smaller than a predetermined number, for example, 0 (step S115), or the current speed falls below a predetermined reference speed of, for example, 80K [track / s], the deceleration command is stopped (step S117). If not, steps S113 to S116 are repeated to continue deceleration. When the deceleration command is released, the HS flag is set to 1 and the process proceeds to the above-described target scan subroutine (step S120). When HS = 1, the constant velocity servo pull-in subroutine is executed in the target scan subroutine as described above. According to the search method according to the present invention described above, the difference between the target frame number F _TGT and the current frame number F _P | D | when, for example, 3072 or more mass becomes a value, the speed change of the slider 3 is Figure 8 Like that. In Figure 8, during the period from the search starting time t ₀ to time t ₁ is the slider acceleration instruction is supplied to the motor control circuit 12, the slider is accelerated by a predetermined acceleration. Time t ₁ relationship Nrmg ≦ Ndcl step S110 is satisfied in the deceleration command is issued in S111 the motor control circuit 12. Then, at the time t _2, the condition Nrmg ≦ of S116
Either 0 or Vact ≦ Vr ₃ holds, and the motor control circuit 12 is instructed to stop the deceleration command in S117. Then, in the period from time t ₂ of t _3, the S42 or S45 in constant velocity servo lead subroutine execution, at time t _3, the slider speed reaches Vr ₂ vicinity, further Vr ₂ or smaller values is constant speed control to speed V _C (step S53, S54). When N _D becomes equal to or less than N _{D1 at} time t ₄ , a slider stop command is issued and the slider stops at time t ₅ . Then, the tracking servo command is given to the tracking control circuit 8, and the tracking servo locks in at time t ₆ to obtain the frame number difference D. The magnitude of this value is determined, and if it is 11 or more and less than 256, then the multi-jump subroutine is executed at time t ₇
Executed until If the difference D is smaller than 11, the single jump is repeated from time t ₈ to t _9. Thus, in the high scan subroutine, the slider is quickly moved by the open loop control in which the timing of switching from the acceleration area to the deceleration area is appropriately controlled, and then the address data is read while moving the slider at a predetermined speed to update the track counter. Since the fine adjustment is mainly performed by swinging the tracking unit of the pickup when a predetermined remaining address is reached after repeated target scanning, a high-speed search is possible. When the slider 3 is suddenly accelerated or decelerated, the tracking unit of the pickup 2 swings due to inertial force as shown in FIG. FIG. 9 shows an example in which the countermeasures for the count error are taken in the high scan subroutine of FIG. 6, and corresponding parts are denoted by the same reference numerals and description thereof is omitted. As shown in steps S104a and S111a in FIG. 9, when the MPU 6 issues the slider acceleration (step S104) and deceleration command (step S111), the direction in which the acceleration / deceleration force acts to suppress the swing of the tracking unit. A jump command for rocking the tracking unit is issued to. This jump command gives the tracking control circuit 8 a command to swing the tracking unit according to the acceleration / deceleration force. If necessary, the magnitude of the swing of the tracking unit can be adjusted according to the acceleration / deceleration force. That is, when raising or lowering the voltage output of the voltage generation circuit 13 for accelerating or decelerating the slider 3 as shown in FIGS. 12 (A) and 12 (B), the tracking control circuit 8 preferably has the above-mentioned voltage output. A jump signal having a level or pulse width corresponding to the level is supplied to the tracking unit as a braking signal, and the tracking unit is urged in the acceleration / deceleration direction of the slider to suppress the vibration of the tracking unit. The resonance characteristic of the tracking unit is, for example, the eleventh.
As shown in the figure, when the signal has a peak at 30 Hz, it is desirable that the application time T of the jump signal be T = (1/30) / 2 ≒ 16 [ms]. Also, as shown in FIG. 12 (C), it is preferable to reduce the jump signal level with time, since the shock applied to the tracking unit is reduced. The constant velocity servo pull-in subroutine aims at early setting of the slider by appropriately setting the change characteristic of the deceleration to the next constant velocity movement stage. As shown in FIG. 13, through the acceleration region and the deceleration region, for example, V _C
If it is not suddenly shifted to the constant velocity region where the constant velocity control is performed by the velocity servo of = 18K [track / s], it takes time to settle due to the vibration of the slider. Therefore, as shown in FIG. 14, when the speed of the slider is reduced to 80K [track / s], the speed is reduced to 54K [track / s] by applying a 54K speed servo to reduce the deceleration acceleration. 18K [tr] through 36K speed servo which makes the speed of 36K [track / s]
ack / s]. This speed servo, for example, samples the integrated value Nt of the track counter 10 every 0.5 [ms] and
Is calculated, and the voltage generation circuit 13 is calculated based on the speed difference from the target speed.
This is done by controlling the output of Alternatively, stepwise speed control may be performed by sequentially switching n with time, current speed Vact, track count value, or the like, with the target speed being _VA = _VA− n · Δ. Thus, for example, through the stepwise speed servo, it is possible to smoothly shift from the deceleration region where the maximum braking force is applied to the constant speed region. Next, the deceleration data map will be described. In the above-described high scan subroutine, in the acceleration region and the deceleration region portion in order to quickly move the slider 3 to the vicinity of the target address, for example, the speed is increased by maximum acceleration of the slider, while the maximum braking force is applied from a predetermined switching point to decelerate. Control is adopted to shorten the search time. In order to perform this open control, it is desirable that the operating characteristics of the entire drive system such as the slider in the acceleration region and the deceleration region are constant characteristics, but when a linear motor is used,
The generated power depends on the magnetic field or the like of the drive coil.
This magnetic field is not uniform, and when the position of the drive coil is sequentially changed, the change in the generated driving force or braking force is generally non-linear, and they change over time. In addition, sliders using linear motors generally have low frictional force,
Unless braking is actively applied, the vehicle will not stop at the target position due to inertial force. Therefore, it is preferable to improve the control accuracy in the open control using the deceleration data map. Hereinafter, description will be made with reference to FIG. In Figure 15, the slider 3 starts to accelerate from point O of the frame number F, A _X time after speed through the point A of the A _Y, the maximum braking force is applied, the speed B _Y in elapsed time B _X first reaches the measurement point B, and further, the speed of the elapsed time C _X deceleration is continued is assumed to reach the second measurement point C was reduced to C _Y. Where the area
OABB _X corresponds to the number of tracks T _B crossed from the point A to the point B. The area OABCC _X corresponds to the number of tracks T _C crossed from the point A to the point C. Area BCC _X B _X is B
This corresponds to the number of tracks TBC crossed before moving from the point to the point C. TBC = a T _C -T _B. The frame number F _{n at} the midpoint between the points B and C is F _n =
_{F + T B + (TBC /} 2), also, the deceleration K _n in the frame number _{F n, K n = | (} C Y -B Y) / (C X -B X) | [track /
s ² ]. The reason why the point A is not the first measurement point and the point B is the first measurement point is that the swing of the pickup or its tracking unit when the slider is suddenly braked is taken into consideration. By repeating the same measurement and calculation of the acceleration time Ax by sequentially changing from the small to the large, graph deceleration K _n of the slider in the frame number F _n and the frame number are obtained. The deceleration of the slider between the frame number _Fn and the frame number _{Fn + 1} is, for example, linearly approximated. This processing is performed in two directions, ie, the forward direction and the reverse direction of the slider movement direction. FIG. 13 shows an example of a graph of the deceleration data thus obtained. This graph is stored in the memory 20 as a deceleration data map that can be searched by, for example, a frame number. The timing of creating the deceleration data map is automatically performed, for example, when a disc is placed after the power is turned on. It is also possible to store the data map in the memory 20 in advance based on the design specifications and eliminate the need to actually create the data map for each player. The values in these data maps are
It is desirable that the deceleration is measured and updated each time a deceleration operation is performed in the high scan subroutine by the learning function. By doing so, it is possible to cope with a temporal change in the braking force and individual differences in the braking force in each frame number. A method of determining the timing of switching from the acceleration region to the deceleration region using the deceleration data map will be described. In the acceleration area and the deceleration area up to the point D, the total number of target crossing tracks is T _M , and the total number of crossing tracks at the point _A is T _A.
When the remaining number of tracks T ₀ at point A, because T ₀ = T _M -T _A T ₀ is equivalent to approximately _{ΔADAx, T 0 ≒ A Y ·} (Dx-Ax) / 2 , where the point A intermediate frame number of dominant deceleration e.g. a point K _n as the estimated deceleration and the point D between the point D
When reading from the data map by specifying F _n , K _n ≈A _Y / (Dx−Ax), so if this is substituted for T ₀ above, T ₀ = A _Y ² / 2K _n , A _Y ² = 2K _n T ₀ is obtained. Therefore, when the difference T _D between the intersection track the total number T _M and the intersection track the total number T _A to the current position in the acceleration and deceleration region becomes T _D ≧ T _0, or current speed A _Y of the slider, , It is possible to converge to the target frame number in the acceleration / deceleration area by shifting to the deceleration area. Next, another embodiment of the high scan subroutine will be described in the seventeenth embodiment.
This will be described with reference to the drawings. In this control method, the deceleration in the deceleration section is controlled so as to be the ideal deceleration, so that the transition from the deceleration section to the constant speed area is smoothly performed, and the time required for setting the slider is not reduced. . In FIG. 17, it is possible to shorten the search time by shortening the time t ₂ of time t ₁ and the deceleration section of the acceleration section. To do so, it is necessary to increase the acceleration a ₁ and a ₂ to increase the driving force and the braking force of the slider also increases the incidence angle alpha ₂ of concomitantly to the target frame number. Here, as shown in FIG. 18, the incident angle α ₂
When is small, the search time increases. When the incident angle α ₂ is large, the slider moving direction is reversed in the vicinity of the target frame number, and the vibration state as shown in FIG. 13 occurs, which lowers the slider arrival position accuracy and increases the settling time. Bring Therefore, in this control method, as shown in FIG. 19, open control is performed to make the most of the driving force of the slider motor 14 in the acceleration region, while the speed of the slider 3 is adjusted and reduced in the deceleration region. It is desirable to control the speed so as to maintain the maximum ideal deceleration such that the moving speed of the slider does not change vibrationally. Next, the control procedure will be described with reference to FIG. First, the ideal deceleration K ₀ is stored in the memory 20 in consideration of the dynamic characteristics of the slider drive system. When the high scan subroutine is selected in step S29 in FIG. 2, an open control subroutine using this deceleration table is executed. From the distance D by subtracting the number of tracks N _B in the constant speed area and the convergence area described above in the acceleration region and the deceleration region to calculate the number of tracks to the slider crosses (step S13
1). For example, 3600 tracks (18K [tr
The number of tracks obtained by subtracting (ack / s] × 200 [ms]) is set as the number of acceleration / deceleration area tracks N _{J at} which the information detection spots should intersect in the acceleration area and the deceleration area (step S9). A reset command for the track counter 10 is issued (step S132).
A slider acceleration command is issued to the motor control circuit 12 (step S133). The motor control circuit 13 generates the maximum output, for example, and starts the movement of the slider 3. Truck counter
The integrated value Nt of 10 is read, Nt is subtracted from N _J, and the remaining track Nrmg in the acceleration / deceleration area (steps S134 and S135). The number of remaining tracks Nrmg, the integrated value Nt of the counter, and the stored deceleration K ₀ are determined by the above-described discriminant. To calculate the switching time speed V (step S13).
6). It is determined whether the current speed Vact has exceeded the switching speed V (step S137). If not exceeded, steps S134 to S137 are repeated via a wait cycle (step S138) with a sampling interval of, for example, 0.5 [ms]. When it exceeds, the acceleration command is released and the deceleration command is issued (step S139), and the integrated value Nt and the acceleration / deceleration area track number
Reading the N _J to calculate the remaining number of tracks Nrmg the acceleration and deceleration region (step S140, S141). When the number of remaining tracks Nrmg becomes, for example, 0 or a negative value (step S142), the deceleration command is stopped, this subroutine is terminated, and the target scan subroutine described above is entered (step S14).
6). Otherwise, the remaining track Nrmg and deceleration K ₀
The corresponding ideal current speed V ₀ is calculated from (step S14
3). Set the target speed V _TGT of the speed servo to V _TGT = V ₀ − (Vact
Calculate as -V ₀ ) * G. Here, the gain of the speed servo circuit is G. A speed setting signal corresponding to this target speed V _TGT is supplied to the motor control circuit 12 to control the speed of the slider 3 (step S144). For example, through a wait cycle of 0.5 [ms] (step S145), steps S141 to S1 are performed.
45 performs variable value control by repeating the deceleration of the deceleration region forms a speed control so as to follow the ideal deceleration K _0. According to this control method, there is an advantage that the slider can be settled quickly because the control moves to the constant velocity stage with an appropriate ideal deceleration without going through the constant velocity servo pull-in subroutine. In this case, the ideal deceleration K ₀ is set as a function of the number of remaining tracks, and the larger Nrmg is, the larger K ₀ is, so that the constant velocity servo pull-in can be performed only in the small region of Nrmg.
It is possible to use K ₀ . In the CAV disc, the frame number of the address data corresponds to the track number, but in the CLV disc, since the reproduction time from the start point to the current address is recorded as the time data as the address data, the number of tracks is calculated from the time code. This calculation method is disclosed in
59-157873, the innermost track radius
r ₀ , the number of revolutions at this radius is No, the track pitch is P, the distance of the reproduction track at time t is r, and the distance r of the current track position from the disk center is: The distance D _R from the current address to the target address is given assuming that the respective time codes are t ₀ and t ₁ . The track D _P from the current address to the target address is
It can be calculated as D _P = D _P / P. The track pitch P is obtained, for example, by the MPU executing a track pitch measurement program. In this way, if it is determined that the disc is a CLV disc at the beginning of the performance, a program for calculating the number of tracks, the track number, etc. from the address data is executed as appropriate.
The present invention is implemented. The functions of the demodulation circuit 5, the track counter 10, and the motor control circuit 12 may be performed by the MPU.
In the embodiment, the electromagnetic braking is performed, but the mechanical braking may be performed. The detection of the speed of the slider is calculated based on the change in the integrated value of the track counter 10. However, the present invention is not limited to this. For example, a magnetic marker provided in the passage of the slider 3 may be detected by a pickup coil. Alternatively, the speed of the slider may be detected by reading an optical marker provided in the passage by an optical sensor. It is also conceivable to use an acceleration sensor. As described above, in the high speed search method for the disc player of the present invention, the acceleration / deceleration movement control mode and the constant velocity movement control mode of the slider are selected and executed according to the distance from the current address to the target address. Therefore, it is preferable that an appropriate search operation according to the distance to the target address is performed and quick random access is possible while eliminating the form of reading address data from the disk as much as possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention, FIG. 2 is a flow chart showing a procedure for selecting an optimum search subroutine according to a distance, and FIG. Is a flow chart showing a control procedure of a multi-jump subroutine, FIG. 4 is a flow chart showing a control procedure of a target scan subroutine, FIG. 5 is a flow chart showing a control procedure of another target scan subroutine example, and FIG. FIG. 7 is an explanatory diagram for explaining an example of the slider speed change when the search is started from the target scan subroutine, FIG. 7 is a flowchart showing the control procedure of the high scan subroutine, and FIG. 8 is the search started from the high scan subroutine. FIG. 9 is an explanatory diagram for explaining an example of a change in slider speed in the case of FIG. 10 is a flowchart showing a control procedure for suppressing the vibration of the tracking unit, FIG. 10 is an explanatory view for explaining the swing of the tracking unit, FIG. 11 is a view showing the self-resonance characteristic of the tracking unit, and FIG. FIGS. 13A and 13B are explanatory views for explaining the relationship between the output voltage of the voltage generation circuit 13 and the jump signal, FIGS. 13 and 14 are explanatory views for explaining the slider settling, FIGS. 15 and 16 The figure is an explanatory diagram for explaining the deceleration data map used for open control,
17 to 19 are explanatory diagrams for explaining another example of a high scan subroutine, and FIG. 20 is a flowchart showing a control procedure of another example of a high scan subroutine. Explanation of symbols of main parts 2 ... Pickup 3 ... Slider 5 ... Data demodulation circuit 6 ... MPU 8 ... Tracking control circuit 9 ... Slider motor drive circuit 10 ... Track counter 12 ... Motor control circuit 13 ... … Voltage generator 14 …… Drive motor

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Haruyasu Sakata               Pie, 4-2610 Hanazono, Tokorozawa-shi, Saitama               Onia Corporation Tokorozawa Plant                (56) Reference JP-A-58-62868 (JP, A)                 JP-A-61-229276 (JP, A)

Claims (1)

(57) [Claims] A disk including a coarse adjustment servo loop by a slider for displacing a pickup for reading an information signal recorded in a track shape on the disk in the radial direction of the disk, and a tracking servo loop for causing an information detection point of the pickup to follow the track of the disk. A high-speed search method for a target address in a player, wherein an acceleration / deceleration movement control mode in which the tracking servo loop is opened, and the slider is accelerated and then decelerated according to a predetermined level signal supplied to a drive unit of the slider,
A constant-velocity movement control mode in which the slider is controlled to move at a constant velocity based on the address data while obtaining address data from the read signal from the pickup is prepared, and the distance from the current position of the pickup to the target address is set. When the detected distance is larger than a predetermined value, the acceleration / deceleration movement control mode is executed and then the constant speed movement control mode is executed to turn on the tracking servo loop, and the detection distance is set to the predetermined value. When it is smaller, the high speed search method in the disc player is characterized in that the tracking servo loop is turned on after executing the constant speed movement control mode without executing the acceleration / deceleration movement control mode. 2. 2. The disk according to claim 1, wherein the level set in the level signal when the slider is accelerated in the acceleration / deceleration movement control mode corresponds to a maximum drive level of the drive unit with respect to the slider. A high-speed search method in a player.