JP3335406B2 - Track jumping equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus which uses an optical disk as a recording medium, and irradiates a desired track among tracks formed on or formed on the optical disk with a light beam. The present invention relates to a track jump device for moving a light beam.

[0002]

2. Description of the Related Art As a conventional track jump device,
For example, a publication "National technica published by Matsushita Electric
l report Vo.l35 No.2 Apr.1989) states that when performing a search operation to move a light beam to a target track, the moving speed control of the light beam is set to an open control immediately before the end of the search operation, and An apparatus is disclosed in which a brake pulse is applied to suppress the movement of the light beam, and the moving speed of the light beam is rapidly reduced. As described above, the brake voltage Vb applied by the brake pulse for reducing the moving speed of the light beam is a constant voltage.

[0005] The following operation of the light beam following the track will be described below with reference to FIGS. FIG. 8 is a plan view of the entire pickup. In FIG. 9, the light is condensed by the objective lens 100 and radiated to the track, and the light reflected by the track is supplied to the four-divided photodetector 102 through the objective lens 100, the prism and the like. The signals transmitted from the four photoelectric elements of the four-division photodiode 102 are added and subtracted, and the track error (T
E) It becomes a signal. The generated track error signal is appropriately amplified by the voltage amplifier 1 shown in FIG. 1, a phase compensator 2 connected to the output side of the voltage amplifier 1, and the like, and the output side of the phase compensator 2 is connected to one switching contact. Is transmitted to the track actuator 3 via the switch S1. The track actuator 3 moves so that the center of the objective lens 100 is located at the center of the amplitude of the track error signal. As a result, the center of the objective lens follows the eccentricity of the disk.

However, if the objective lens 100 follows the eccentricity of the disk, the center of the objective lens will be deviated from the center of the optical axis generated by the optical system including the laser diode 101, causing problems such as deterioration of the amount of reflected light. . In order to solve this problem, light is emitted from the LED 104 and is received by the two-segment photodiode 105 through the hole 103, so that the light is transmitted from the two-segment photodiode 105 to the center of the objective lens 100. The shift from the center of the optical axis is detected, and the pickup is moved so that the shift disappears. Thereby, the deviation between the center of the objective lens and the center of the optical axis is almost eliminated.

Next, the operation when the light beam crosses a plurality of tracks and moves to a target track will be described with reference to FIG. When the number of tracks to be traversed is instructed by the CPU 4 to the track jump sequencer 5, the track jump sequencer 5 operates the track actuator 3 so that the track actuator 3 moves the light beam by the number of tracks. Therefore, the light beam is moved by the number of tracks, and the linear motor is also moved.

[0006]

When the light beam is moved as described above, the lens 100 is held by an elastic member such as a rubber damper as shown in FIG. In such a case, when the movement of the lens 100 deviates from the neutral position indicated by the solid line of the rubber damper, a torque force is generated in the track actuator by the restoring force generated in the rubber damper, and the direction of action of the torque force is in the moving direction of the track actuator. On the other hand, when it is positive, it may be negative. Therefore, when the torque force acts on the track actuator, the deceleration in the movement of the lens 100 changes when the brake voltage Vb is constant as in the related art, and the light beam stops on the target track. Therefore, there is a problem that the movement of the track actuator may not be decelerated to a sufficient speed range, and that the light beam may not be stopped at the target track. The present invention has been made to solve such a problem, and an object of the present invention is to provide a track jump device that can perform a stable track jump even with a pickup having a mechanism for supporting an objective lens with an elastic body. Aim.

[0007]

SUMMARY OF THE INVENTION The present invention provides a light beam moving means having a mechanism for moving an objective lens through which a light beam irradiated on an optical disk is transmitted while being supported by an elastic body. A cycle or frequency obtained from a track error signal in a track jump device for moving through an acceleration period, a speed control period, and a brake period for causing the light beam to reach a target track so as to move across the track. Is supplied, and second information about a target cycle or frequency corresponding to the set moving speed of the light beam is supplied, and the positive information obtained by subtracting the other from one of the first information and the second information is supplied. Or, based on the negative period or the frequency error, the light beam moving means in the speed control period A cycle or frequency voltage converting means for generating a degree control error voltage; an average value calculating means for calculating an average value of the speed control error voltage generated from the cycle or frequency voltage converting means; A brake voltage generating means for generating a brake voltage for the beam moving means, and an average value of the speed control error voltage sent from the average value calculating means and a brake sent from the brake voltage generating means during the braking period. A brake voltage generating adding means for generating an error-corrected brake voltage by adding the voltage and supplying the brake voltage to the light beam moving means, wherein the average value calculating means controls the operation of the track jump device. The number of tracks traversed by the light beam, specified by A track counter for subtracting the number of tracks stored on the basis of the above, storage means for storing 2n speed control error voltages until the number of tracks stored in the track counter becomes 0, and a storage means for storing the speed control error voltages in the storage means. And a fourth calculating means for adding all of the speed control error voltages, discarding data of the lower n bits of the added value, and obtaining an average value of the speed control error voltages. . The present invention also provides a light beam moving unit having a mechanism for moving an objective lens through which a light beam irradiated on an optical disc is transmitted while being supported by an elastic body, wherein the light beam moves across a track of the optical disc. Acceleration period, speed control period,
In a track jump apparatus for moving the light beam through a brake period for reaching a target track, first information on a cycle or frequency obtained from a track error signal and a target cycle corresponding to a set moving speed of the light beam Alternatively, second information relating to frequency is supplied, and based on a positive or negative cycle or frequency error obtained by subtracting the other from one of the first information and the second information, A period or frequency voltage converting means for generating a speed control error voltage during the speed control period; an average value calculating means for calculating an average value of the speed control error voltage generated from the period or frequency voltage converting means; A brake voltage for generating a brake voltage for the light beam moving means. Generating means for adding an average value of the speed control error voltage sent from the average value calculating means and a brake voltage sent from the brake voltage generating means in the braking period to generate an error corrected brake voltage. And a brake voltage generating adding means for supplying the light beam moving means to the light beam moving means, wherein the average value calculating means is a track specified by a system controller for controlling the operation of the track jump device, the track being traversed by the light beam. A track counter that stores the number of tracks and subtracts the number of tracks stored based on the supplied tracking error signal, and the number of tracks becomes 0 from the time when the number of tracks stored in the track counter reaches a predetermined value. The above-mentioned speed control error voltages obtained up to the above are sequentially cumulatively added by 2n pieces, and the lower n bits of the cumulative added value are added. A fifth calculating means the average value of the speed control error voltage discards the partial data, characterized by comprising a.

[0008]

With this configuration, the period or frequency voltage conversion means can control the light based on the positive or negative period or frequency error obtained by subtracting one of the first information and the second information from the other. The beam moving means generates a speed control error voltage, and the average value calculating means calculates an average value of the speed control error voltage. The brake voltage generation adding means adds the above-mentioned average value having a positive or negative value to the brake voltage sent from the brake voltage generating means to generate an error corrected brake voltage. Therefore, even if the period or frequency voltage conversion means, the average value calculation means, the brake voltage generation means, the brake voltage generation addition means is a pickup having a mechanism for supporting the objective lens with an elastic body,
It works so that a stable track jump can be performed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the track jump apparatus of the present invention will be described below with reference to the drawings. In FIG. 1, a track error (TE) signal obtained by converting reflected light of a light beam applied to a track of an optical disc into a voltage is supplied to a voltage amplifier 1 and a phase compensator 2 connected to an output side of the voltage amplifier 1. The output of the phase compensator 2 is transmitted to the track actuator 3 via the switch S1 connected to one switching contact. The track actuator 3 moves the lens 100 through which the light beam passes so as to move the light beam following the eccentricity of the disk. However, as described above, the center of the lens 100 is far away from the center of the optical axis. A position-voltage conversion circuit 14 for transmitting a PSD signal obtained by converting the position of the lens 100 into a voltage is connected to the output side of the track actuator 3 via an adder 15 so that the position-voltage conversion circuit A phase compensator 13 is connected to an output side of the voltage compensator 13, a voltage amplifier 12 is connected to an output side of the phase compensator 13, and a linear motor 11 is connected to an output side of the voltage amplifier 12. The output side of the linear motor 11 is connected to the other input terminal of the adder 15. With such a configuration, the linear motor 11 provided in the pickup having the lens 100 and the like is moved based on the PSD signal so that the center of the lens 100 and the center of the optical axis substantially coincide with each other. The above-mentioned components 1 to 3, 10
Portions 15 to 15 are also provided in a conventional track jump device.

The track error signal is binarized by a binarization circuit 9 and supplied to a pulse width measuring device 16.
The pulse width measuring device 16 outputs a positive voltage if the binarized data is large with respect to a value derived from the target frequency, and outputs a negative voltage if the binarized data is small. When the light beam moves across a plurality of tracks, as shown in FIG. 6C, first, an acceleration period in which an acceleration pulse for moving the lens 100 in the direction of the movement target track is supplied to the pickup. A settling period, which is a period until the accelerated pickup moves at substantially the same speed, a speed control period, which is a period from the acceleration period to the braking period including the settling period, and a light beam to the target track. Each period of the brake period is a period during which the moving speed of the pickup is reduced to a speed at which the truck can be turned on.

As described above, since the track error signal supplied from the binarization circuit 9 includes the effect of the torque force generated in the track actuator, it is derived from the target frequency transmitted from the pulse width measuring device 16. An error (hereinafter referred to as a frequency error) Δf between the calculated value and the value binarized by the binarization circuit 9 indicates a frequency generated by the torque force. Also, this frequency error Δ
f takes a positive or negative value as described above, and when the value derived from the target frequency is larger than the binarized track error signal, that is, a torque force is generated in the track actuator in the direction opposite to the moving direction of the pickup. When the target frequency is smaller than the binarized track error signal, that is, when the target frequency is smaller than the binarized track error signal, a torque force is generated in the track actuator in the same direction as the pickup moving direction. The value of the frequency error Δf is positive.

The output side of the pulse width measuring device 16 generates a speed control error voltage corresponding to the frequency error Δf, FV
It is connected to a period or frequency voltage conversion circuit 6, which is a converter. The speed control error voltage has a value opposite to the positive or negative value of the frequency error Δf. An output side of the cycle or frequency voltage conversion circuit 6 is connected to an average value calculation circuit 8 for calculating an average value of the plurality of supplied speed control error voltages, and is connected to one switching terminal of the switch S2. . The output side of the average value calculation circuit 8 is connected to one input terminal of the output side of the brake voltage generation circuit 7 for generating the above-described brake voltage Vb, and adds an averaged speed control error voltage to the brake voltage Vb. Connected to the other input terminal of the device 17. The output side of the adder 17 is connected to the other switching terminal of the switch S2.
The above-described cycle or frequency voltage conversion circuit 6, brake voltage generation circuit 7, average value calculation circuit 8, pulse width measurement device 16, and adder 17 make the track jump sequencer 5
To form The output side of the switch S2 is connected to the switch S1.
Connected to the other switching terminal of

With this configuration, a positive or negative speed control error voltage is generated in the cycle or frequency voltage conversion circuit 6 corresponding to the positive or negative cycle or the frequency error Δf, and the average value thereof is a predetermined value in the brake period. It is applied to the brake voltage and supplied to the track actuator. This operation will be described in detail. When the moving speed of the objective lens, that is, the frequency ft of the TZC is higher than the target frequency f0, that is, when Δf (= ft−f0) is a positive value, the moving direction of the track actuator is equal to the restoring force T by the rubber damper. It seems that he is working in the direction. The reason is that when the restoring force T by the rubber damper is neglected, the torque T0 generated by the track actuator only needs to be generated by a loss due to friction of a bearing or the like. Generally, the loss is considered to be very small, and therefore the current for generating the torque is considered to be almost zero. The relationship between the torque and the speed is obtained by integrating the angular velocity a obtained by dividing the actuator torque T0 by the inertia J of a movable portion such as an objective lens and an actuator.
If the actuator torque T0 varies with the restoring force T, the speed varies with the restoring force. That is, the restoring force can be detected by the above-mentioned Δf, and Ve obtained by converting the detected result Δf into a voltage is added to the brake pulse, whereby the torque due to the restoring force can be canceled. Therefore, during the braking period,
Since the speed control error voltage is supplied to the track actuator so that the pickup moves in the direction to cancel the torque force, the variation in the braking performance of the pickup due to the torque force can be eliminated.

The operation of the thus configured track jump device will be described below. The number of tracks to be traversed is instructed by the CPU 4 to the track jump sequencer 5, and the pulse width measuring device 16 outputs a positive voltage if the binary data is larger than the value derived from the target frequency, and outputs a negative voltage if the binary data is smaller. . Since the track error signal supplied from the binarization circuit 9 to the pulse width measuring device 16 is affected by the torque force generated in the track actuator, the cycle which is the subtraction result sent from the pulse width measuring device 16 is Alternatively, the frequency error Δf indicates an amount generated by the torque force. Note that when the target frequency is larger than the binarized track error signal, the period or the value of the frequency error Δf is positive, and vice versa.

The average value of the output signal of the period or frequency voltage conversion circuit 6 is calculated by the average value calculation circuit 8 and sent to the adder 17. On the other hand, a brake voltage is applied to the adder 17 during the braking period, and the adder 17 adds the averaged cycle or frequency error Δf to the brake voltage and supplies the result to the torque actuator via the switches S2 and S1. . Therefore, during the braking period, the speed control error voltage is supplied to the track actuator so that the pickup moves in the direction to cancel the torque force, so that the variation in the braking performance of the pickup due to the torque force can be eliminated.

It is to be noted that the track jump sequencer shown in FIGS. 2 to 5 can be considered. FIG.
Shows a circuit for adding the previously calculated speed control error voltage and the speed control error voltage generated this time, dividing by 2 and calculating an average value each time the speed control error voltage is generated. I have. In FIGS. 2 to 5, the output of the divider from the FV data sent from the FV converter is A.
The circuit portion until the V data is transmitted corresponds to the average value calculation circuit 8 shown in FIG. The track counter 50 receives the count value corresponding to the target frequency corresponding to the number of tracks on which the light beam moves from the CPU 4, stores the count value, and obtains the count value from the track error signal as shown in FIG. Each time one pulse of the track zero cross (TZC) signal is supplied, the stored value is decremented by one. In addition, 1
A periodic track zero cross signal corresponds to one track.

The pulse width measuring device 51 measures the time between half periods of the supplied track zero cross signal, outputs the value during the half period of the next track zero cross signal, and measures the time between the above half periods. . The output side of the pulse width measuring device 51 is connected to the FV converter 52, and converts the time information during the half cycle into FV data which is a signal before the DA conversion of the track jump signal shown in FIG. I do. The output side of the FV converter 52 is a BV for calculating the level, 1 / FV, of the brake section Tb shown in FIG.
Converter 53, selector 55, selector 56, adder 57
Is connected to the input side. The other input side of the selector 56 is connected to the output side of the latch 59, and the selector 56 outputs either the FV data or the output signal of the latch 59 according to a timing signal supplied from a timing generator 60 that generates a timing signal based on a track zero cross signal. Or choose. The output side of the selector 56 is connected to another input side of the adder 57, and the adder 57 adds the output signal of the selector 56 and the FV data. The output side of the adder 57 is connected to a divider 58 for dividing the addition result data by 2, and the output side of the divider 58 is connected to a latch 59 and a subtractor 54. As described above, the calculated average value is stored in the latch 59, and the stored value is connected to the selector 56.

The output side of the subtractor 54 is connected to the selector 55
The selector 55 selects either the FV data or the BV signal according to the count value supplied from the track counter 50. That is, the selector 55 selects the FV data until the count value reaches the predetermined value,
The BV signal is selected until the count value becomes 0 from the predetermined value. The output side of such a selector 55 is connected to a DA converter 61 for transmitting a track jump signal.

As described above, in the circuit shown in FIG. 2, since the average value of the FV data is calculated every time the FV data is generated, it is not necessary to generate complicated timing, and the circuit scale can be reduced.

FIG. 3 shows a circuit of the type in which a plurality of generated FV data are all added and then divided by the number of additions. The same components as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. The output side of the FV converter 52 is connected to the BV converter 53 and the selector 55, and is further connected to an N-stage shift register 62 in the circuit shown in FIG. The shift register 62 stores N pieces of FV data based on a timing signal supplied from the timing generator 60. Each output side of the shift register 62 is connected to an adder 63 for adding all the FV data stored in the shift register 62, and the output side of the adder 63 outputs the addition result by N, which is the number of FV data. It is connected to a divider 64 for dividing. The output side of the divider 64 is connected to another input side of the subtractor 54.

Since the average value calculating circuit configured as described above calculates the average value after all the FV data for calculation is supplied, the error of the average value calculation result is very small. Further, since the FV data is always supplied to the shift register 62 and the finally stored data is used, there is no need to generate complicated timing.

FIG. 4 shows a circuit of the type in which a plurality of generated FV data are sequentially added and then divided by the number of additions. The same components as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. The output side of the FV converter 52 is connected to the BV converter 53 and the selector 55, and further connected to one input side of the adder 65 in the circuit shown in FIG. The output side of the adder 65 is connected to a latch 66 for storing the addition result data based on the timing signal supplied from the timing generator 60 when the count value of the track counter 50 reaches a predetermined value based on the output signal of the track counter 50. The output side of the latch 66 is connected to the other input side of the adder 65, and also connected to a divider 67 for dividing the addition result by the number of latches. The output side of the divider 67 is connected to another input side of the subtractor 54.

The circuit for calculating the average value thus constructed adds the FV data every time the count value of the track counter 50 reaches a predetermined value and supplies the FV data when the FV data is no longer supplied. Since the average value is calculated by dividing the addition result by the number of FV data, errors in the calculation result are small, and the circuit scale can be reduced as compared with the circuit shown in FIG.

FIG. 5 shows a circuit for calculating an average value of a type in which a divisor can be set in the circuit shown in FIG. still,
The same components as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. The output side of the adder 65 is connected to the latch 68, and the output side of the latch 68 is connected to the other input side of the adder 65 and to the divider 69. In the circuit shown in FIG. 4, the number of FV data added by the adder 65 is based on the output signal of the track counter 50. In the circuit shown in FIG. 5, a divisor for dividing the output data of the latch 66 is stored. The output side of the M register 69 is connected to the divider 68, and the latch 68 stores the addition result data of the adder 65 by the number set in the M register 70.

The circuit for calculating the average value configured in this manner adds the FV data only for the number set in the M register 70 each time, and divides the addition result by M when M pieces of FV data are stored. Since the average value is calculated, the error of the calculation result is small, and the circuit scale can be reduced as compared with the circuit shown in FIG.

In the circuits shown in FIGS. 2 to 5, the number of FV data added by the adders 57 and 6365 is set to 2 ⁿ , and the lower ⁿ of the 2 ⁿ addition result data By connecting a deletion device for deleting data for bits to the adder, the dividers 58, 64, 67, 6
9 need not be provided. With this configuration, it is possible to provide a track jump device with a small circuit scale.

[0027]

As described above in detail, according to the present invention, a light beam is obtained based on a positive or negative cycle or frequency error obtained by subtracting one of the first information and the second information from the other. The moving means generates a speed control error voltage for canceling the torque force generated during the speed control period, calculates an average value, and adds the above average value taking a positive or negative value to the brake voltage sent from the brake voltage generating means. Since the error-corrected brake voltage is generated, even a pickup having a mechanism for supporting the objective lens with an elastic body acts so that a stable track jump can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a track jump device of the present invention.

FIG. 2 is a block diagram showing one embodiment of a track jump sequencer shown in FIG.

FIG. 3 is a block diagram showing another embodiment of the track jump sequencer shown in FIG.

FIG. 4 is a block diagram showing another embodiment of the track jump sequencer shown in FIG. 1;

FIG. 5 is a block diagram showing another embodiment of the track jump sequencer shown in FIG. 1;

FIGS. 6A to 6D are timing charts for explaining the operation of the track jump device of the present invention.

FIG. 7 is a plan view of a pickup in which a lens through which a light beam passes is indicated by an elastic body.

FIG. 8 is a plan view showing the entire pickup.

FIG. 9 is a perspective view showing an optical system, a detection system for detecting a shift between the center of the objective lens and the center of the optical axis, and the like.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 3 ... Track actuator, 4 ... CPU, 6 ... Period or frequency voltage conversion circuit, 7 ... Brake voltage generation circuit, 8 ... Average value calculation circuit, 16 ... Pulse width measuring instrument, 17
... adders.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-127437 (JP, A) JP-A-3-245375 (JP, A) JP-A-4-205765 (JP, A) JP-A-1- 119968 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B ^7/ 08-7/09 G11B 21/08

Claims (4)

(57) [Claims] A light beam moving means having a mechanism for moving an objective lens through which a light beam applied to an optical disc passes while being supported by an elastic body, so that the light beam moves across a track of the optical disc; A track jump device for moving the light beam through an acceleration period, a speed control period, and a brake period for causing the light beam to reach a target track, wherein the first information on a cycle or frequency obtained from a track error signal and the light beam Is supplied with the second information relating to the target period or frequency corresponding to the set moving speed of the positive or negative period or frequency error obtained by subtracting the other from one of the first information and the second information. Generating a speed control error voltage during the speed control period in the light beam moving means. Cycle or frequency voltage conversion means; average value calculation means for calculating an average value of the speed control error voltage generated from the cycle or frequency voltage conversion means; and a brake voltage for the light beam moving means in the brake period. And an error correction by adding an average value of the speed control error voltage sent from the average value calculating means and a brake voltage sent from the brake voltage generating means during the braking period. And a brake voltage generation adding means for generating an already-used brake voltage and supplying the generated brake voltage to the light beam moving means, wherein the average value calculation means is controlled by the system controller for controlling the operation of the track jump device. Stores the number of tracks traversed by the beam and stores the stored tracks based on the supplied tracking error signal. A track counter for decrementing the number of tracks, storage means for storing 2n speed control error voltages until the number of tracks stored in the track counter becomes 0, and all speeds stored in the storage means. And a fourth calculating means for performing addition of the control error voltage, discarding data of the lower n bits of the added value, and obtaining an average value of the speed control error voltage. 2. The track jump device according to claim 1, wherein the average value calculating means calculates an average value of a speed control error voltage generated during a predetermined period immediately before the shift to the brake period in the speed control period. 3. An optical beam moving means having a mechanism for moving an objective lens through which a light beam irradiated on an optical disc is transmitted while being supported by an elastic body, so that the light beam moves across a track of the optical disc. A track jump device for moving the light beam through an acceleration period, a speed control period, and a brake period for causing the light beam to reach a target track, wherein the first information on a cycle or frequency obtained from a track error signal and the light beam Is supplied with the second information relating to the target period or frequency corresponding to the set moving speed of the positive or negative period or frequency error obtained by subtracting the other from one of the first information and the second information. Generating a speed control error voltage during the speed control period in the light beam moving means. Cycle or frequency voltage conversion means; average value calculation means for calculating an average value of the speed control error voltage generated from the cycle or frequency voltage conversion means; and a brake voltage for the light beam moving means in the brake period. And an error correction by adding an average value of the speed control error voltage sent from the average value calculating means and a brake voltage sent from the brake voltage generating means during the braking period. And a brake voltage generation adding means for generating an already-used brake voltage and supplying the brake voltage to the light beam moving means, wherein the average value calculation means is controlled by a system controller for controlling the operation of the track jump device. Stores the number of tracks traversed by the beam and stores the stored tracks based on the supplied tracking error signal. And a speed control error voltage obtained from the time when the number of tracks stored in the track counter reaches a predetermined value to the time when the number of tracks becomes zero is sequentially accumulated by 2n. Add
And a fifth calculating means for discarding data of lower-order n bits of the cumulative addition value to obtain an average value of the speed control error voltage. 4. The track jump device according to claim 3, wherein said average value calculating means calculates an average value of a speed control error voltage generated during a predetermined period immediately before a shift to said braking period in said speed control period.