JP3085395B2 - Disk unit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk device that reproduces and / or records data using a disk-shaped information recording medium, and more particularly to a disk device suitable for high-speed access. .

[Prior Art] In recent years, digital audio discs, so-called CDs (compact discs), developed for music reproduction have been rapidly spread because they have features not found in conventional analog record players. In addition, since this product records data in digital format and can reproduce it digitally, it is also used as an external storage device such as a personal computer. In such data application fields, high-speed access to external storage devices is required. But CD
Is recorded in a CLV (constant linear velocity) system, so the relationship between the data position and the number of tracks or the radial position is not clear, and is not suitable for high-speed access.

One method for solving this problem is disclosed in, for example, JP-A-62-89.
283 are disclosed. The conventional example will be described below with reference to FIG. The disk 1 is driven by a disk motor 2, and a signal recorded on the disk 1 is reproduced by a pickup 3. The reproduced signal is supplied to the RF detection circuit 5, EF
The digital data is reproduced by the M demodulation circuit 6. If the digital data is an audio signal,
The signal is converted into an analog audio signal by the D / A conversion circuit 7 and reproduced by the speaker 8.

Ancillary information called a subcode is inserted in the digital data, and address information on the disk is recorded therein. The subcode Q detection circuit 9
The sub-code Q in the address information is detected and output to the control circuit 109. The control circuit 109 controls the entire device. Specifically, the pickup feed motor 4 is a linear motor, and moves the slider including the pickup 3 at a high speed in the radial direction of the disk. The displacement meter 100 is actually composed of a speed detector and an integration circuit, and calculates a moving amount from the moving speed of the pickup 3.
The reference displacement setting circuit 102 is for setting an arbitrary moving amount, and the control circuit 109 sets a value corresponding to the moving amount of the pickup 3. The comparator 101 is a displacement meter 1
The output of 00 and the output of the reference displacement setting circuit 102 are compared, and the fact that the two signals match is output to the control circuit 109.

At the time of actual access, first, the current address is detected by the subcode Q detection circuit 9 and the movement amount is calculated by the control circuit 109 from the difference from the target address which is a command command from the host computer (not shown). Then, the reference displacement corresponding to the calculated movement amount is referred to as a reference displacement setting circuit 10.
Set to 2. Then, the pickup feed motor 4 is controlled by the disk reproduction system control circuit 103 and the servo circuit 110, and the pickup is moved until the output of the displacement meter 100 matches the output of the reference displacement setting circuit 102 and the output of the comparator 101 is inverted. Move. In this way, an access of an arbitrary moving amount is performed.

However, in a CD, track pitches and linear velocities vary, and a disk address alone cannot uniquely determine a radial position of a disk. In addition, the sensitivity of the speed detector also changes due to variations and aging. Therefore, when the disc is converted, access is actually performed, the difference between the displacement calculated from the subcode and a preset reference displacement is obtained, and the initial value of the displacement is corrected using the difference.

[Problems to be Solved by the Invention] The above-mentioned conventional technology can cope with fixed fluctuation factors such as sensitivity variation of the speed detector, deviation of track pitch and linear velocity between disks, and the like. Cannot respond.

1) Variation that occurs each time an access is made.

2) Non-linearity between displacement and address.

3) Fluctuation over time caused after initial correction at the time of disc conversion.

1) is caused by disk eccentricity or disturbance. Tracking is performed after the access is completed, and the address position is read from the subcode Q of the disk. However, variation occurs due to disk eccentricity and disturbance. Since the displacement amount is corrected from the information including the variation, the subsequent access is affected by the variation at this time, and an accurate access cannot be performed.

2) is caused by variations in the magnetic flux distribution of the speed detector, non-linearity of the detection circuit, and fluctuations in the track pitch and linear velocity in the disk. Because the CD is a CLV system, the radius position and the disk address position are not linear, but CLV
Even when the characteristics of the method are considered, the non-linearity may remain.

3) Specifically, there are a drift due to the temperature characteristic of the displacement meter, and the application of gravity due to the inclination of the device. It cannot be handled because it occurs after initial correction at the time of disk replacement.

For the reasons described above, accurate access is not possible, and there is a problem such as track jump after the access is completed.
Since a precise track position correction was required, there was a disadvantage that the access time was long.

[Means for Solving the Problems] In the present invention, in order to solve the above-mentioned problems of the conventional technology, the nonlinear correspondence between the detected movement amount and the movement amount obtained by calculation is approximated by a linear function. Each time an access is made, the error between the linear function and the measured value is fed back to the linear function and corrected.

[Operation] By using the broken line function, it is possible to learn nonlinear characteristics. Further, every time an access is actually performed, a part of the error is fed back to the learning characteristic and corrected, so that the influence of the random error can be eliminated and the temporal variation can be followed.

Embodiment An embodiment of the present invention will be described with reference to FIGS. In FIG. 1, a disk 1, a disk motor 2,
The pickup 3, the pickup feed motor 4, the RF detection circuit 5, the EFM demodulation circuit 6, the D / A conversion circuit 7, the loudspeaker 8, and the subcode Q detection circuit 9 have the same functions as those of the conventional example shown in FIG. Is omitted. The speed detector 11 is configured to operate in conjunction with the pickup feed motor 4, and detects the moving speed of the pickup feed motor 4. The servo circuit 10 includes a focus, tracking, and spindle servo system circuit. The servo circuit 10 has almost the same function as the conventional servo circuit 110 shown in FIG. 8, but does not include an access system circuit. The servo circuit of the access system is included in the control circuit 12, and will be described below with reference to FIG.

In FIG. 2, reference numeral 12 denotes a control circuit, 13 denotes an arithmetic unit constituted by a one-chip microcomputer, and 4 denotes a linear motor for pick-up feed. The linear motor 4 is driven by the amplifier 20, and moves the pickup 3 shown in FIG. 1 in the radial direction of the disk. The linear motor 4 is provided with a speed detector 11 so as to be linked thereto, and detects the speed of the linear motor 4. The detected speed signal is amplified by the amplifier 22 and the amplifier 21
Is input to the A / D converter 23. The A / D converter 23 converts the speed signal into a digital signal and outputs the digital signal to the integration circuit 24. The integration circuit 24 integrates the speed signal and converts it into a position signal.
The variable amplifier 17 amplifies the position signal at a designated amplification factor and inputs the amplified position signal to the adder 16 via the switch 26. Arithmetic processing circuit
14 controls the control circuit 12 and reads the address on the disk at that time based on the subcode Q input from the terminal 25. In addition, while monitoring the output of the variable amplifier 17 and specifying the amplification factor, the target movement amount of the linear motor 4 is calculated and output to the target movement amount setting circuit 15.
The adder 16 is provided between the output of the target moving amount setting circuit 15 and the variable amplifier.
The difference between the outputs of 17 is calculated and output to the D / A converter 18. D / A
The converter 18 converts the digital difference signal into an analog signal, and inputs the analog signal to the adder 19. The adder 19 calculates a difference between the outputs of the D / A converter 18 and the amplifier 21 and outputs the difference to the amplifier 20.
The amplifier 20 drives the linear motor 4, and the linear motor 4 drives a slider including the pickup 3.

At the time of actual access, the arithmetic processing circuit 14 first detects the current address by the subcode Q detection circuit 9 in FIG. 1, and calculates the target movement amount of the linear motor 4 from the difference between the target address and the current address. Then, it outputs to the target movement amount setting circuit 15. The target movement amount is transmitted to the linear motor 4 via the adder 16, the D / A converter 18, the adder 19, and the amplifier 20, and the linear motor 4 drives a slider including the pickup 3. When the linear motor 4 moves, its speed is detected by the speed detector 11. The speed signal is
The signal is input to the adder 19 via the amplifier 21. This speed signal forms the speed feedback system of the linear motor 4,
It has the function of controlling speed. The speed signal of the linear motor 4 is processed by the A / D converter 23 and the integration circuit 24, and the moving distance of the linear motor 4 is obtained. The variable amplifier 17
This is for correcting variations in the sensitivity of the speed detector 11, and changes the amplification factor according to the sensitivity. The adder 16 subtracts a preset target movement amount and an actual movement distance calculated from the speed signal. When the access is started, there is almost no movement distance yet, and the target movement amount is output as it is as a signal for driving the linear motor 4. When the linear motor 4 actually starts moving, the output of the integrating circuit 24 increases and the output of the adder 16 decreases. Then, when the target movement amount and the movement distance match, the two signals balance, the output of the adder 16 becomes 0, and the access ends.

The specific processing procedure of the embodiment of the present invention will be described below. After the power is turned on, first, it is detected whether or not the disk is loaded. When the disk is not loaded, the linear motor 4 is fixed by a lock mechanism (not shown) so as not to move due to unnecessary external vibration. Become. When the disk is loaded, the sensitivity of the speed detector 11 shown in FIG. 1 and the learning of the access are performed, and then a state of waiting for an input is made. The sensitivity correction and the learning of the access will be described later.

When a disk is newly inserted, or when the disk is replaced, if the sensitivity correction has been completed, learning of the access is performed and the apparatus waits for input. If the sensitivity correction has not been completed, learning of the sensitivity correction and access is performed, and the apparatus enters a state of waiting for input.

The sensitivity correction is a process for correcting a change in the response characteristic of the servo system due to a variation in the detection sensitivity of the speed detector 11 in FIG. When an access is made, the switch 26 shown in FIG. 2 is turned on, and a servo system composed of two loops of a position loop and a speed loop is formed. The response characteristic of this system is 2
It is determined by the gain distribution of the two systems. When the gain of the speed loop is large, the suppression by the speed signal is large, the response of the system is delayed, and the access is delayed. On the other hand, when the gain of the position loop is large, the response of the system is fast but the response is oscillating, and it takes time until the system comes to a standstill, resulting in slow access. Therefore, most desirable is critical braking in which the two loop gains are balanced. Therefore, the gain of the position loop is changed in accordance with the sensitivity of the speed detector to obtain an optimal gain distribution. This operation is sensitivity correction.

 Hereinafter, a detailed processing procedure of the sensitivity correction will be described.

First, the switch 26 in FIG. 2 is set to off, and the position loop is excluded from the control loop. Next, a value for moving the slider at a low speed in the inner circumferential direction is set in the target movement amount setting circuit 15 of FIG. Since the switch 26 is set to OFF, the output of the target movement amount setting circuit 15 is directly used by the adder 16 and the D / A
The signal is input to the adder 19 via the converter 18. Therefore, the output of the target movement amount setting circuit 15 acts as a speed target for the speed control loop formed by the adder 19, the amplifier 20, the linear motor 4, the speed detector 11, the amplifier 22, and the amplifier 21. Therefore, if a value corresponding to a low speed (for example, 70 mm / sec) that is not affected by the collision of the slider is set, the linear motor 4 moves at a low speed by the action of the speed loop. The arithmetic processing circuit 14 detects that the linear motor 4 has moved to the innermost circumference by monitoring the output of the A / D converter 23, that is, the speed signal. Specifically, when the output of the A / D converter 23 becomes almost zero for a certain period of time, it is considered that the linear motor 4 has moved to the innermost circumference.

Next, the integral value of the integrating circuit 24 is reset, and the linear motor 4 is sent to the outer periphery at a low speed. The method of feeding is the same as in the case of the innermost feed, except for the polarity of the speed target value. Similarly, when it is detected that the outermost circumference has been reached, the output of the integrating circuit 24 at that time is stored in a memory (not shown), and the integrated value is reset. Thereafter, the linear motor 4 is sent to the innermost circumference in exactly the same manner, and the integrated value at that time is detected. The average speed detection sensitivity is calculated from the two integrated values in the inner circumferential direction and the outer circumferential direction detected as described above and the mechanical movable range of the linear motor 4. Further, the amplification factor of the variable amplifier 17 is increased or decreased according to the calculated detection sensitivity.

Next, an access learning operation will be described. In a CD, data is recorded by a constant linear velocity method, so that correspondence between an address on a disk and a position in a radial direction of the disk is not clear. The innermost track radius of the data area is R
[M], track pitch P [m], linear velocity L [m /
s], and the playing time from the start position (this corresponds to the address of the data) is T [s], and the track position r [m] in the radial direction is given by the first equation.

If the innermost track radius R is accurate and the track pitch P and the linear velocity L do not fluctuate over the entire surface of the disk, the relationship between the track position and the disk address is the first except for random disturbance such as disk eccentricity. It can be calculated by the formula. However, in practice, the track pitch and the linear velocity also vary within the disk. Also, the speed signal from which the position in the radial direction is calculated may fluctuate depending on the position, direction, and speed of the linear motor. Therefore, the nonlinearity is learned by dividing the area into a plurality of areas according to the moving direction and the moving distance.

FIG. 3 is an explanatory diagram of an access control operation representing an integral value with respect to a pickup moving distance.

As shown in FIG. 3, the relationship between the moving distance and the corresponding integral value is learned by dividing it into, for example, four regions. Although these two quantities should be in a proportional relationship,
All variations due to disc variations, etc., are concentrated in the non-linearity between these two quantities. For example, a reference integral value S10 corresponding to a moving distance of 10 mm and a reference integral value S40 corresponding to a moving distance of 40 mm are learned. When accessing an arbitrary position based on this, the corresponding integral value is obtained by proportional calculation, and the access is performed. In the CD, the width of the recording area is about 30 mm in the radial direction, but an area up to 40 mm is prepared for a margin.

First, the linear velocity is measured from the rotational speed of the disk at the innermost position (absolute time: 0 minutes). Next, access is made to a position at an absolute time of 5 minutes (this access is performed assuming linear characteristics based on the detection sensitivity measured at the time of sensitivity correction), and the rotational speed of the disk is measured again. Then, the track pitch is calculated from the rotational speed and linear velocity of the disk measured at the innermost circumference and the newly measured rotational velocity. Then, access for learning (hereinafter, referred to as learning access) is performed at a place where the absolute time is 25 minutes. Details of the learning access will be described later. Thereby, the characteristic (S10 +) at the time of moving 10 mm from the inner circumference to the outer circumference is learned.
Next, learning access is again made to the position at an absolute time of 5 minutes. Thus, the characteristic (S10−) in the direction from the outer circumference to the inner circumference is learned. Next, learning access is performed from an absolute time of 5 minutes to an absolute time of 45 minutes, and a characteristic when the robot is moved by about 22 mm is measured. Then, the characteristic (S40 +) up to the access distance of 40 mm is determined by extrapolating from the already measured characteristic up to 10 mm. In the same manner, learning access is performed between 45 minutes and 5 minutes in absolute time,
A characteristic (S40−) in a range of 40 mm from the outer periphery to the inner periphery is obtained. In this way, a learning characteristic as shown in FIG. 3 is obtained by four accesses.

Next, details of the learning access will be described. First, the current address is read. Then, the access distance is calculated from the already calculated linear velocity, track pitch, and innermost track radius (this uses the disk specification of 25 mm as it is) using the first formula. Then, a corresponding integral value is calculated using the detection sensitivity of the speed detector 11 measured at the time of the sensitivity correction. Next, the loop setting is set to the access state. That is, tracking is turned off by the servo circuit 10, the integration circuit 24 is reset, and the switch 26 is turned on. Then, the already calculated integral value is output to the target moving amount setting circuit 15. After that, it waits for the end of the access. The integrated value output of the integrating circuit 24 and the speed signal output of the A / D converter 23 are monitored, and when the integrated value substantially matches the target value and the speed signal becomes substantially 0, it is determined that the access has been completed. .
Then, the setting of the loop is switched to the tracking state.
That is, the switch 26 is turned off, and the target movement amount set value is set to 0.
And the servo circuit 10 turns on tracking.
When tracking is turned on and data can be reproduced, the current address is read using the subcode Q detection circuit 9. The distance actually reached based on this address is the first
Calculated from the formula, the reference integral value (S10, S4
0, etc.). As shown in Fig. 4, the travel distance is 10m
In the region below m, simply calculate the reference value S10
Ask for. In the range of 10 mm to 40 mm, S40 is calculated by proportional calculation based on S10 as shown in FIG.

The normal access operation is the same as the learning access up to the point where the linear motor 4 shown in FIG. 2 is driven and the tracking is turned on, so that the description is omitted. However, the target movement amount is calculated by proportional calculation based on the characteristics shown in FIG. 3 obtained by the access learning operation. Next, turn on tracking and read the current address. Then, the difference between the target movement amount and the arrival movement amount is calculated, and only a part of the error is fed back instead of all the errors to correct the reference integral value.
As shown in FIG. 6, the reference integral value is corrected using, for example, only one eighth of the error. Since only a part of the error is used in this way, it acts as a kind of filter, random disturbances caused by eccentricity etc. are excluded and are not reflected in the reference integral value, and the time change and the error of the initial value are Will be corrected. The correction of the reference integral value is calculated based on the origin or the previous reference integral value, similarly to the processing in the learning access. When the correction of the reference integration value is completed, track jump is performed until the target address is reached in order to access the final address.

FIG. 7 shows an access control method for a short distance. In the present invention, since the linear motor is driven by the reference movement amount signal that is substantially proportional to the movement distance, when trying to access a very close position, the linear motor may not move due to frictional force. Therefore, for example, in the case of a distance of 2 mm or less, the same movement amount (integral value) as 2 mm is set as shown in FIG. 7, and when the distance reaches half the target movement amount, the original value is returned. By such a process, even at a very short distance, a sufficient driving force is provided at the beginning of the access, and once it starts moving, it is controlled by the original moving distance, so that accurate access can be made.

As described above, according to the present embodiment, the following effects can be obtained.

1) Accurate access is possible by eliminating the influence of random errors that occur each time access is made.

2) Accurate access is possible by following variations in disk characteristics and non-linearity of the speed detector.

3) Even if the characteristics change due to the temperature characteristics or the like, the characteristics automatically follow, and accurate access is enabled. 4) Even if the sensitivity of the speed detector varies, the gain of the servo system can be easily changed, and the optimum response characteristics can always be obtained.
As a result, access becomes faster.

5) Since initial sensitivity correction can be performed without using a disc, accurate learning can be performed, and it is possible to prevent a pickup from colliding.

6) Even in the case of short-distance access, accurate access is possible without being affected by frictional force.

7) Integral processing, addition / subtraction processing, speed sensitivity correction, and various controls can be performed by one chip, so that not only the circuit is simplified, but also the processing can be flexibly changed.

8) There is no need for an integrator in the analog circuit and no need for offset adjustment.

According to the present invention, a disk device with a high access speed can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a digital data reproducing apparatus according to one embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of a control circuit of FIG. 1, and FIGS. Explanatory drawing of access control operation in one embodiment, FIG.
FIG. 1 is a block diagram showing a configuration of a digital data reproducing apparatus according to the prior art. 1 ... CD (compact disk) 2 ... Disc motor 3 ... Pickup 4 ... Pickup feed motor 5 ... RF detection circuit 6 ... EFM demodulation circuit 7 ... D / A conversion circuit 8 ... Speaker 9 ... Subcode Q detection circuit 10 Servo circuit 11 Speed detector 12 Control circuit

Continuation of the front page (72) Inventor Junichi Iida 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Yokohama Plant, Hitachi, Ltd. (56) References JP-A-62-89283 (JP, A) JP-A-62-89282 (JP, A) JP-A-54-126515 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 21/08 G11B 7/085

Claims (2)

(57) [Claims] 1. A disk device capable of reproducing data by using a disk-shaped disk on which data is recorded, a pickup for detecting a signal from the disk, and detecting an address of the disk from the signal detected by the pickup. Address detecting means, a moving means for driving the pickup in a radial direction of the disk, a moving amount detecting means for detecting a moving amount of the pickup driven by the moving means, and a control means for controlling an access operation. The control means divides the movement amount into a plurality of pieces according to the magnitude of the movement amount detected by the movement amount detection means, and calculates the movement amount from the movement amount and the address detected by the address detection means. A disk device for nonlinearly learning a correspondence relationship with a moving amount to be performed. 2. A disk device for reproducing data from a disk-shaped information recording medium, comprising: a pickup for detecting a signal from the information recording medium; and an address detection for detecting an address of the information recording medium from a signal detected by the pickup. Means, a moving means for driving the pickup in a radial direction of the information recording medium, a moving amount detecting means for detecting a moving amount of the pickup driven by the moving means, and a control means for controlling an access operation. The control unit learns a correspondence relationship between a movement amount detected by the movement amount detection unit and a movement amount calculated from an address detected by the address detection unit, and based on a result of the learning. Controlling the moving means to perform an access, and using a part of the error between the target moving amount and the actual moving amount resulting from the access. Disk drive and corrects the learning result.