JP4467661B2 - Disk unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a disk device that moves a recording head while rotating a disk of a recording medium and records / reproduces information to / from the disk by the recording head, and more particularly to a disk device having a temperature control mechanism that suppresses temperature rise.
[0002]
[Prior art]
In this type of disk device, the operation of moving the recording head to a desired position at high speed is referred to as seek, and this seek is frequently repeated. During this seek, the power consumption is extremely high compared to a normal recording / reproducing state in which the head does not move at high speed. For this reason, when seeking is performed continuously for a long time, the inside of the disk device may become hot. The main heat source during seek is the head transfer motor drive system when the disk is controlled by CAV (Constant Angular Velocity), and the head transfer motor when the disk is controlled by CLV (Constant Linear Velocity). In addition to the drive system, there is a disk motor drive system.
[0003]
The temperature rise accompanying the heat generation of the drive system at the time of the seek causes the components of the disk or the device to exceed their heat resistance temperature, so that this temperature rise has been solved.
[0004]
For example, in Japanese Patent Laid-Open No. 6-119008, a temperature sensor is provided in an optical disk device to detect the temperature of the device, and the operation of the device is limited when the temperature of the device exceeds a preset temperature. Thus, a configuration for preventing an excessive temperature rise is disclosed.
[0005]
In addition, in order to reduce the cost of parts and assembly man-hours associated with the installation of the temperature sensor, or to know the temperature of the place where it is difficult to attach the temperature sensor directly, we also propose a technique for predicting the temperature of the desired place by calculation Has been. For example, Japanese Patent Laid-Open No. 7-153208 discloses a configuration for predicting a temperature rise of a VCM by calculation from a current instruction value to a voice coil motor (VCM) that is a head transfer motor.
[0006]
FIG. 5 shows an example of a conventional disk device that predicts a temperature rise by calculation.
[0007]
In FIG. 5, 101 is a magnetic disk device, 102 is a disk enclosure (hereinafter referred to as “DE”), 103 is a disk motor, 104 is a spindle, 105 is a magnetic disk, and 106 is a voice coil motor (hereinafter referred to as “VCM”). 107 are magnetic heads. The VCM 106 positions the magnetic head 107 by moving it in the radial direction of the magnetic disk 105. Reference numeral 114 denotes a temperature detection unit that predicts the temperature of the VCM, 115 denotes a positioning control unit, 118 denotes a servo controller, 122 denotes a RAM, and 135 denotes a VCM control unit.
[0008]
The RAM 122 is updated with data such as Iv (VCM current indication value), ΔQv1 (heat amount for temperature rise), ΔQv2 (heat amount for natural heat release), Qv (heat amount of measurement object), Tv (temperature of measurement object), etc. Stored as possible. Further, a timer (soft timer) is set in the RAM 122. ROM (not shown) includes K (constant), θ (constant due to thermal resistance), Cv (heat capacity of measurement object), Te (ambient environmental temperature), tS (sampling time), a (constant), b (constant). Etc. are stored in advance.
[0009]
In the disk device configured as described above, the temperature detection unit 114 performs the prediction calculation of the VCM temperature in the following procedure.
[0010]
The VCM control unit 135 performs interrupt processing for normal seek control every sampling time ts of 66 μsec, and detects the position of the magnetic head 107 and updates the VCM current instruction value Iv. Next, the temperature detection unit 114 multiplies the square of the VCM current instruction value Iv by the coefficient K, tS and the amount of heat ΔQv1 (= Iv ² XK · tS), and calculate the heat quantity Qv of the measurement object by integrating (Qv ← Qv + ΔQv1- Thus, the temperature Tv of the measurement object is detected (Tv = Qv / Cv).
[0011]
The above processing is performed every sampling time ts, and the temperature Tv is detected and stored in the RAM 122. When seeking is performed, the temperature Tv is read from the RAM 122, and seek control is performed based on the temperature Tv.
[0012]
In this seek control, if the detected temperature Tv is larger than the reference value, the start of seek is delayed according to the temperature Tv, thereby suppressing the temperature rise.
[0013]
The delay amount D for delaying the start of seek is set as D = aTv−b as a linear function of the temperature Tv (where a and b are constants stored in the ROM). In this case, the delay amount D is set as follows according to the temperature Tv. That is, the reference value for the temperature Tv is T1, D = 0 is set in the region where Tv ≦ T1, and D = aTv−b is set in the region where Tv> T1.
[0014]
Therefore, if the temperature Tv is equal to or lower than the reference value T1, the seek is started immediately upon receiving a seek command. If the temperature Tv exceeds the reference value T1, the seek is started with a delay amount D proportional to the temperature Tv. To do. As a result, an increase in the VCM temperature is suppressed, and overheating and destruction of the VCM are prevented.
[0015]
[Problems to be solved by the invention]
However, the conventional apparatus has the following problems.
[0016]
First, there is a problem that the load on the control unit is heavy because of the large amount of calculation required for temperature prediction. That is, in order to perform the temperature prediction calculation, interrupt processing is performed at a very frequent cycle such as a sampling cycle of 66 μsec, and each time calculation for obtaining the current instruction value Iv, heat generation amount ΔQv1, heat release amount ΔQv2, and temperature Tv is performed. There was a need to do. In addition, this interrupt processing must be performed constantly regardless of whether the recording operation or the seek operation is in progress. Such frequent interrupt processing significantly increases the load on the control unit of the disk device and causes a reduction in the processing capability of the control unit.
[0017]
Second, control is performed so that the VCM temperature does not exceed the heat-resistant temperature, but it has been found that in a specific case, not the temperature itself but the temperature difference from the surroundings becomes a problem. This is a problem that the disk is warped as the disk motor generates heat. When the disc motor generates heat, the inner peripheral side of the disc near the disc motor is heated more than the outer peripheral side, and a temperature gradient is generated on the inner and outer periphery of the disc. When the entire disk is heated uniformly, the disk hardly deforms, but when there is a temperature difference in each part of the disk, the disk warps. The warp of the optical disk causes an increase in aberration of a light spot formed on the disk when a light beam is irradiated from the optical head, leading to a decrease in reliability of recording and reproduction. Conventionally, the temperature difference of each part of the disk has not been detected, and the warp of the disk has not been effectively prevented.
[0018]
Therefore, the present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a disk device that requires a small amount of calculation and a small burden on a control unit.
[0019]
It is another object of the present invention to provide a disk device that performs temperature control capable of accurately suppressing disk warpage.
[0052]
Book The disk device of the invention comprises a disk drive means for rotationally driving a disk, a head for recording or reproducing information on the disk, a head moving means for moving the head from a starting position to a target position, in front Disc The temperature of the inner circumference and the temperature of the outer circumference of the disk Temperature calculating means for calculating the difference; and control means for controlling the disk driving means or the head moving means in accordance with the temperature difference calculated by the temperature calculating means.
[0053]
In one embodiment, the control means reduces the drive current to the disk drive means when the temperature difference calculated by the temperature calculation means exceeds a preset threshold value.
[0054]
1 In the embodiment, a disk discriminating unit that discriminates the type of the disc is provided, and a temperature change calculating method by the temperature calculating unit or the disk driving by the control unit according to the disc type discriminated by the disc discriminating unit. Or the control method of the head moving means is changed.
In one embodiment, the operation of the temperature calculation unit or the control unit is permitted and prohibited according to the type of the disc determined by the disc determination unit.
In one embodiment, a rotation setting means for setting the rotation speed or rotation linear velocity of the disk is provided, and a temperature change calculation method by the temperature calculation means according to the rotation speed or rotation linear velocity set by the rotation setting means. Alternatively, the control method of the disk driving means or the head moving means by the control means is changed.
In one embodiment, the rotational speed setting means sets the rotational speed or rotational linear velocity of the disk according to whether the disk rotational system is a CAV system, a CLV system, or a ZCLV system.
In one embodiment, when the disc rotation method is the CAV method, a fixed rotation number is set by the rotation setting unit, and the operation of the temperature calculation unit or the control unit is prohibited.
In one embodiment, when the disk rotation method is the ZCLV method and seek is performed in the same zone, a fixed rotation number is set by the rotation setting unit, and the operation of the temperature calculation unit or the control unit is performed. Is prohibited, and seek to another zone is performed, the rotation speed is changed by the rotation setting means, and the operation of the temperature calculation means or the control means is permitted.
[0055]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 is a schematic configuration diagram of an optical disc apparatus according to the first embodiment of the present invention. In the first embodiment, since the internal temperature rises due to the heat generated by the head transfer motor 7 when the seek is continuously repeated a plurality of times, the purpose is to suppress the temperature rise by temporarily prohibiting the seek. Yes.
[0056]
In FIG. 1, an optical disk apparatus 1 introduces a read-only optical disk such as a CD or DVD (Digital Versatile Disk) -ROM or a recordable / reproducing optical disk 2 such as a PD or DVD-RAM by a loading mechanism (not shown). And the information is recorded or reproduced on the optical disc 2. The introduced optical disk 2 is placed on the turntable 3 and rotated by a disk motor 4. The optical head 5 records and reproduces information on the optical disc 2. The optical head 5 is supported by a guide shaft 6 so as to be movable in the radial direction of the optical disc 2, and is reciprocated by a head transfer motor 7. The head transfer motor 7 includes a feed screw 7a and a stepping motor 7b that rotates the feed screw 7a. The head screw 7a meshes the rack 8 fixed to the optical head 5, and the stepping motor 7b rotates the feed screw 7a. As a result, the rack 8 is moved, and the optical head 5 is moved accordingly. The disk motor 4, the guide shaft 6, and the head transfer motor 7 are attached to the chassis 9. Case 10 seals each other part with chassis 9 for dust prevention.
[0057]
The circuit unit 11 includes a head signal processing circuit 12, a host controller 13, a servo controller 30, a head driver 31, a transfer motor driver 32, and a disk motor driver 33.
[0058]
The head signal processing circuit 12 inputs a signal read from the optical disk 2 by the optical head 5 and creates a servo signal and a digitized data signal from the signal. This data signal includes address information that is recording position information of the disc.
[0059]
The host controller 13 is composed of a CPU, DSP, RAM, ROM, and the like (not shown), and performs control based on programs and data stored in advance in the ROM. For example, the host controller 13 exchanges commands with the host device 23 via the SCSI interface (not shown), performs data transfer, or controls the head signal processing circuit 12 and the servo controller 30. Various controls in the included optical disk device are performed. The host controller 13 includes a temperature calculation unit 14 and a seek control unit 20.
[0060]
The temperature calculating unit 14 includes a starting position calculating unit 15, a target position calculating unit 16, a heat generation amount calculating unit 17, a time measuring unit 18, and an integrating unit 19, and predicts a temperature rise of the head transfer motor 7. The host controller 13 performs temperature prediction by the temperature calculation unit 14 immediately before the execution of the seek command issued from the host device 23, and performs control according to the temperature predicted value. That is, immediately before the nth seek command is executed from the initial state such as when the power is turned on, the temperature calculation unit 14 performs the nth temperature prediction calculation and updates the temperature prediction value. However, n is a natural number. In the following description, (n) attached to a symbol indicating an output or the like indicates an output at the time of n-th temperature prediction.
[0061]
The starting position calculation means 15 calculates the starting position rs (n) of the optical head 5 from the address information output from the head signal processing circuit 12. The starting position rs (n) represents the radius of the track currently being recorded / reproduced.
[0062]
The target position calculation means 16 calculates the target position rd (n) of the optical head 5 based on the target address information given by the seek command from the host device 23. The target position rd (n) represents the radius of the track when the seek is completed.
[0063]
In the disk apparatus according to the present embodiment, recording / reproduction with respect to a plurality of types of optical disks is possible. Therefore, for each type of optical disk, an approximate expression or a data table indicating the correspondence between address information and track radius position is stored in the ROM. Stored in advance.
[0064]
The calorific value calculation means 17 obtains the difference between the target position rd (n) and the starting position rs (n) as the head transfer distance s (n) = | rd (n) −rs (n) | Based on s (n), the heat generation amount E (n) of the head transfer motor 7 when one seek is executed is predicted. The relationship between the head transfer distance s (n) and the heat generation amount E (n) is experimentally obtained in advance and stored in the ROM as an approximate expression or a data table. In this embodiment, the relationship between the heat generation amount E (n) and the head transfer distance s (n) is given by a quadratic approximate expression shown in (Equation 6).
[0065]
E (n) =-C1 · s (n) ² + C ₂ ・ S (n) ...... (6)
However, C1 and C2 are positive constants.
[0066]
The time measuring means 18 has a time measuring function using an operation clock of the CPU, and measures and outputs an elapsed time t (n-1) from the n-1th temperature prediction time to the nth temperature prediction time. .
[0067]
The accumulating means 19 uses the n-1th predicted temperature value T (n-1), the elapsed time t (n-1), and the calorific value E, and the nth temperature according to the recurrence formula shown in (Equation 7). A predicted value T (n) is calculated. The predicted temperature value T (n) indicates the temperature difference between the controlled object and the surroundings of the controlled object, not the controlled object temperature itself. Strictly speaking, it is assumed that the ambient heat capacity is sufficiently large and that the ambient temperature change is more gradual than the controlled object temperature change.
[0068]
The first term on the right side of (Expression 7) indicates a temperature decrease due to natural heat dissipation. The second term indicates a temperature increase due to heat generation for one seek. τ and k are constants representing the time constant and heat capacity of the controlled object, respectively, and the values of these constants are obtained in advance by experiments and stored in the ROM.
[0069]
T (n) = exp {-t (n-1) / τ} .T (n-1) + k.E (n) (7)
However, τ and k are positive constants.
[0070]
The seek control means 20 compares the predicted temperature value T (n) with the allowable value Tth (n). If the predicted temperature value T (n) is less than or equal to the allowable value Tth (n), the seek control unit 20 determines the interval time ti (n). If not set (or set as interval time ti (n) = 0) and the predicted temperature value T (n) is larger than the allowable value Tth (n), the interval time ti (n) is calculated according to (Equation 8). To do.
[0071]
ti (n) = τ · k · E (n) / Tth (n) (8)
As described above, the predicted temperature value T (n) indicates not the temperature of the controlled object but the temperature difference between the controlled object and the surroundings. Therefore, the allowable value Tth (n), which means the allowable value of the temperature difference, is set as a value obtained by subtracting the ambient temperature from the heat resistance temperature of the head transfer motor 7. Specifically, the output of the thermistor 21 attached to the chassis 9 is converted into temperature data by an AD converter (not shown) to obtain the ambient temperature value Tc (n), and the value indicating the heat-resistant temperature preset in the ROM The allowable value Tth (n) is set by subtracting the ambient temperature value Tc (n).
[0072]
When the interval time ti (n) is not set (or when the interval time ti (n) = 0 is set), the seek control means 20 can immediately execute a seek in response to a seek command from the host device 23. In the same way, permission to execute the seek is given to the host controller 13.
[0073]
When the interval time ti (n) is set based on (Equation 8), the elapsed time from the n-th temperature prediction time is measured by the second time measuring means (not shown). When the elapsed time becomes larger than the interval time ti (n), the seek control means 20 grants seek execution permission to the host controller 13 so that the seek can be executed in response to the seek command from the host device 23. give. As a result, at least the interval time ti (n) is set from the nth seek instruction execution start time to the (n + 1) th seek instruction execution start time.
[0074]
The servo controller 30 controls the head driver 31, the transfer motor driver 32, and the disk motor driver 33 based on the servo signal output from the head signal processing circuit 12 and the command from the host controller 13. The head driver 31 drives the laser of the optical head 5 and drives the focus / tracking control actuator. The transfer motor driver 32 drives the head transfer motor 7, and the disk motor driver 33 drives the disk motor 4.
[0075]
The operation of the disk device configured as described above will be described.
[0076]
First, the host controller 13 drives and controls the head transfer motor 7 via the servo controller 30 and the transfer motor driver 32 to move the optical head 5 to a predetermined position on the inner periphery of the optical disc 2, and then the servo controller 30 and the head. The optical head 5 is driven and controlled via the driver 31 to read a signal from the optical disk 2, detect the presence or absence of the optical disk 2 based on the output of the head signal processing circuit 12, and further drive the servo controller 30 and the disk motor driver 33. While controlling and rotating the disk motor 4, a data signal indicating the type of the disk is extracted from the output of the head signal processing circuit 12, and the type of the optical disk 2 is determined.
[0077]
The starting position calculating unit 15 and the target position calculating unit 16 select an approximate expression or a data table indicating the correspondence between the address information and the track radius position from the ROM according to the type of the optical disc 2.
[0078]
The time measuring means 18 starts measuring the elapsed time t (0) with n = 0 although no temperature prediction is performed. Further, the integrating means 19 stores the initial value T (0) = 0 of the predicted temperature value T in the RAM. The disk motor 4 rotates the optical disk 2 at a rotational speed corresponding to the disk type.
[0079]
In this way, recording / reproduction of the optical disk 2 becomes possible, and when the first seek command is issued from the host device 23 in this state, the starting position calculating means 15 calculates the starting position rs (1) and the target position calculating means. 16 calculates the target position rd (1). The calorific value calculation means 17 obtains the head transfer distance s (1) from the difference between the target position rd (1) and the starting position rs (1), and based on (Equation 6), the heat generation amount E ( 1) is predicted. The time measuring means 18 ends the measurement of the elapsed time, outputs the measurement result t (0), and newly starts measuring the next elapsed time t (1). The integrating means 19 outputs the predicted temperature value T (1) based on (Equation 7). The seek control means 20 compares the predicted temperature value T (1) with the allowable value Tth (1). If the predicted temperature value T (1) is less than or equal to the allowable value Tth (1), the seek control means 20 calculates the interval time ti (n). If not set (or set as interval time ti (n) = 0) and the predicted temperature value T (1) is larger than the allowable value Tth (1), the interval time ti (1) is calculated according to (Equation 8). To do.
[0080]
Then, the next seek execution permission flag to the host controller 13 is set to an interval so that the second seek is not executed until the interval time ti (1) elapses after the start of the seek in response to the first seek command. Only the time ti (1) is disabled. On the other hand, for the first seek command, an execution command is issued from the host controller 13 to the servo controller 30, the head transfer motor 7 is driven by the transfer motor driver 32, and the optical head 5 is transferred.
[0081]
When the second and subsequent seek instructions are issued, the same processing as the first seek instruction is performed.
[0082]
When the nth seek command is issued, the interval time ti (n) is calculated through the same process as described above, and the host controller 13 until the interval time ti (n) elapses from the start of execution of the nth seek. Controls not to execute the (n + 1) th seek instruction.
[0083]
With such control, only when a seek command is given from the host device 23 too frequently, the necessary interval time is set, and the temperature rise due to seek is suppressed to an allowable value or less.
[0084]
Normally, the temperature rise due to one seek is considerably smaller than the allowable value Tth, and the predicted temperature value T (n) is the allowable value Tth only when a seek command of the order of 1000 times is issued continuously from the host device 23. Over. Therefore, in practice, control for giving the interval time is performed only when such multiple seek commands are frequently generated. Even when the seek control means 20 prohibits the execution of the seek command for the interval time ti (n), the command other than the seek is executed, and reproduction / recording can be executed. Therefore, for example, when the amount of playback / recording data is large, the interval time ti (n) may elapse until the playback / recording operation is completed. In this case, a waiting time is substantially generated. do not do. That is, only when the time tp (n) required to actually execute the nth seek and complete recording / reproduction from the time when the nth seek command is issued is shorter than the interval time ti (n). The difference becomes a substantial waiting time.
[0085]
As described above, according to the first embodiment of the present invention, only when a seek command is issued, the temperature calculation unit 14 uses the start position rs and the target position rd of the optical head 5 to predict the temperature predicted value T. Is calculated, the seek command is issued less frequently, and only the operation is repeated at this frequency, so that the amount of operation is small and the burden on the temperature calculating means 14 can be reduced. In addition, since temperature reduction due to natural heat dissipation is taken into consideration, temperature prediction can be performed with high accuracy, and control for limiting temperature rise to the heat resistant temperature or less can be performed even for parts where direct temperature measurement is difficult. it can.
[0086]
Compared to the conventional interrupt processing such as the sampling period of 66 μsec as in the prior art, the temperature prediction is performed only when the seek command from the host device 23 is executed, so even when the seek command is issued most frequently, 10 to 100 ms. Temperature prediction may be performed at a certain cycle, and the burden on the temperature calculation unit 14 can be extremely reduced. In addition, when the seek command is not issued, the temperature prediction calculation need not be performed, so that the burden on the temperature calculation unit 14 can be further reduced.
[0087]
Further, conventionally, for example, when recording / reproducing, even when the control unit is extremely busy with data transfer, error processing, etc., it has been necessary to perform interrupt processing for temperature prediction. In this case, since the temperature prediction is substantially completed at the start of execution of the seek command, the temperature prediction calculation is performed while avoiding busy recording / reproduction. Therefore, it is possible to average the control and calculation in the entire host controller 13 and reduce the burden on the host controller 13.
[0088]
Furthermore, since the temperature calculation means 14 calculates the temperature predicted value from the head transfer distance s (n), it is not necessary to store all past information, and the information can be updated sequentially. Therefore, the storage capacity and calculation amount necessary for executing the temperature prediction can be extremely reduced, and the cost of the apparatus can be reduced. Therefore, even in a system where the time constant of the control target is larger than the seek interval and a very large number of past seek histories of the order of 1000 all affect the current predicted temperature, each seek has a completely random timing. Even in a complicated system in which the amount of heat generated per seek varies depending on, for example, the seek distance, the burden on the control unit for temperature prediction can be extremely reduced.
[0089]
In the present embodiment, the address information from the optical disk 2 is used when the starting position calculation means 15 calculates the starting position rs (n) at the n-th temperature prediction, but the n-1th temperature prediction is performed. The target position rd (n-1) may be used as the value of the starting position rs (n) at the n-th temperature prediction. In this case, it is not necessary to input the starting position rs (n) from the outside, and only the target position rd (n) needs to be given. If the seek issuance frequency is high, the error of the starting position rs (n) is On the other hand, the temperature prediction is important only when such seek frequency is high, so the practicality is sufficient.
[0090]
In the present embodiment, the accumulating unit 19 calculates the nth temperature predicted value T (n) according to (Equation 7), but the same effect can be obtained by an approximate expression substantially equivalent to this. Needless to say. In particular, (Equation 9) obtained by first-order approximation of the first term on the right side of (Equation 7) can obtain a sufficiently accurate control result with a simple calculation.
[0091]
・ When t (n-1) ≦ τ
T (n) = [1- {t (n-1) / τ}]. T (n-1) + k.E (n)
・ When t (n-1)> τ
T (n) = k · E (n) (9)
In this embodiment, the temperature calculation unit 14 performs the temperature prediction calculation every time a seek command is issued. However, the present invention is not limited to this, and the seek command is issued a predetermined number of times. It is also possible to perform a temperature prediction calculation by the temperature calculation means 14 each time.
[0092]
Furthermore, temperature prediction by the temperature calculation means 14 can be performed from all the information on the starting position and the target position of the seek performed during a predetermined time interval (for example, 1 second). Therefore, the elapsed time t, which is the output of the time measuring means 18, is not limited to being a variable.
[0093]
(Second Embodiment)
FIG. 2 is a schematic configuration diagram of an optical disc apparatus according to the second embodiment of the present invention. In the second embodiment, the internal temperature rises due to the heat generated by the disk motor 4 when the seek is continuously repeated a plurality of times. Therefore, the aim is to suppress the temperature rise by temporarily prohibiting the seek. .
[0094]
In FIG. 2, an optical disk 2, a turntable 3, a disk motor 4, an optical head 5, a guide shaft 6, a head transfer motor 7, a rack 8, a chassis 9, a case 10, a head signal processing circuit 12, a target position calculation means 16, a time count The means 18, the integrating means 19, the servo controller 30, the head driver 31, the transfer motor driver 32, and the disk motor driver 33 are the same as those in the first embodiment.
[0095]
The optical disk device 39 introduces a reproducing optical disk such as a CD and a DVD-ROM and a recording and reproducing optical disk 2 such as a PD and a DVD-RAM by a loading mechanism (not shown), discriminates the type of the optical disk 2, and Record or play back information for.
[0096]
The circuit unit 40 includes a head signal processing circuit 12, a host controller 41, a servo controller 30, a head driver 31, a transfer motor driver 32, and a disk motor driver 33.
[0097]
The host controller 41 includes a CPU, DSP, RAM, ROM, and the like (not shown), and performs control based on programs and data stored in advance in the ROM. For example, the host controller 41 exchanges commands with the host device 23 via an external interface (not shown), performs data transfer, or controls the head signal processing circuit 12 and the servo controller 30. Various controls in the optical disc apparatus including The host controller 41 includes a temperature calculation unit 42, a seek control unit 51, a disk rotation setting unit 43, and a disk determination unit 50.
[0098]
The temperature calculation means 42 comprises a target position calculation means 16, a calorific value calculation means 44, a time measurement means 18, and an integration means 19, and the difference between the temperature of the disk motor 4 itself and the ambient temperature around the disk motor 4 (the disk motor 4). A temperature predicted value T indicating the temperature difference between the inner and outer circumferences of the optical disc 2 caused by heat generation is output.
[0099]
The disk discriminating means 50 extracts a data signal indicating the disc type from the output of the head signal processing circuit 12 and discriminates the disc type. The disc rotation setting means 43 is a CAV (Constant Angular Velocity) method, a CLV (Constant Linear Velocity) method, or a ZCLV (Zone Constant Linear Velocity) as a disc rotation method in accordance with the type of disc discriminated by the disc discriminating means 50. One of the methods is selected, and the rotational speed or linear velocity of the optical disk 2 is designated.
[0100]
The disk rotation setting means 43 changes the correspondence between the target position rd and the predicted temperature value T by changing the constant value in the temperature calculation means 42 according to the type or rotation method of the disk, as will be described later. Or changing the operating state of the seek control means 51 to change the correspondence between the temperature predicted value T and the seek. This is because the temperature rise of the disk motor 4 depends on the rotation method and the rotation speed.
[0101]
When the disk rotation system is the CAV system, the temperature increase of the disk motor 4 is constant and below the allowable value regardless of the presence or absence of seek. Therefore, the disk rotation setting unit 43 prohibits the operation of the temperature calculation unit 42 and the seek control unit 51. In this case, there is no restriction on seeking.
[0102]
Further, when the disk rotation method is the CLV method or the ZCLV method, the disk rotation setting unit 43 permits the operation of the temperature calculation unit 42 and the seek control unit 51. At this time, the disk rotation setting means 43 designates the selected disk linear velocity v to the calorific value calculation means 44. In the case of the ZCLV method, the angular velocities are different for each zone, but the linear velocities of all the zones are approximated to a constant value, and this approximated linear velocity is designated as the disk linear velocity v to the heat generation amount calculation means 44. For example, when the optical disc 2 is a DVD-ROM disc, the linear velocity is 3.49 m / s at CLV 1 × speed, the linear velocity 6.98 m / s at CLV 2 × speed, and ZCLV when the DVD-RAM disc has a capacity of 2.6 GB. The approximate linear velocity of 6.16 m / s. The disk linear velocity v is data indicating these speeds.
[0103]
When the disk rotation setting unit 43 permits the operation of the temperature calculation unit 42, the host controller 41 performs temperature prediction by the temperature calculation unit 42 every time a seek command from the host device 23 is executed, Perform the appropriate control. However, the temperature is not predicted for the first seek command, and the temperature rise due to the previous seek is predicted at the start of the second seek command execution. That is, the timing at which the result of temperature prediction is obtained is delayed by one seek, and the temperature predicted value T (n) at the nth temperature prediction is obtained at the time when the n + 1th seek instruction is started. In the following description, (n) attached to a symbol indicating an output or the like indicates an output at the time of n-th temperature prediction, as in the first embodiment.
[0104]
The heat generation amount calculation unit 44 includes a target angular velocity calculation unit 45, a starting point angular velocity calculation unit 46, a target arrival time calculation unit 47, a comparison unit 48, and a disk motor heat generation amount calculation unit 49, and the target obtained by the target position calculation unit 16. The position rd (n), the disk linear velocity v obtained by the disk rotation setting means 43, and the elapsed time t from the previous temperature prediction time (substantially simultaneously with the start of seek) timed by the time measuring means 18 are input. The amount of heat E (n) of the disk motor 4 when one seek is executed is output. There are two structural features of the calorific value calculation means 44. First, the calorific value E is calculated based on the change in the angular velocity of the optical disc 2, and secondly, in order to cope with jitter-free reproduction, It is determined whether or not the next seek has been performed before the optical disk 2 reaches the target angular velocity by using the elapsed time t of the time measuring means 18 to calculate the heat generation amount E.
[0105]
The target angular velocity calculation means 45 inputs the target position rd (n) from the target position calculation means 16 and the disc linear velocity v from the disc rotation setting means 43, and the target angular velocity ωd of the optical disc 2 at the target position rd (n). (n) is calculated. In the case of the CLV method, the target angular velocity ωd (n) is calculated by (Equation 10). In the case of the ZCLV method, the radius of the track at the center of the zone to which the target position belongs is used as the target position rd (n), and the target angular velocity ωd (n) is calculated in units of zones according to (Equation 10). Therefore, the target angular velocity ωd (n) is the same in the same zone.
[0106]
ωd (n) = v / rd (n) (10)
In the disk device of this embodiment, since recording and reproduction with respect to a plurality of types of optical disks are possible, an approximate expression or a data table indicating the correspondence between address information and track radius position is stored in advance in the ROM for each type of optical disk. If the address information is known, the target position rd (n) can be obtained.
[0107]
The starting angular velocity calculating means 46 calculates the starting angular velocity ωs (n) of the optical disc 2 at the time of the nth temperature prediction calculation. The starting angular velocity ωs (n) is predicted from the energization time ts (n−1) of the disk motor 4 to the starting angular velocity ωs (n−1) at the time of the n−1th temperature prediction calculation according to (Equation 11). Calculate by adding angular velocity change. The energization time ts (n-1) is obtained by the comparison means 48 as will be described later. However, the constant C is a positive constant determined from the torque generated by the disk motor 4 and the disk inertia moment, and is experimentally obtained in advance and stored in the ROM.
[0108]
ωs (n) = ωs (n-1) + C · ts (n-1) (11)
The target arrival time calculation means 47 calculates the energization time td (n) required until the optical disk 2 reaches the target angular velocity ωd (n) from the target angular velocity ωd (n) and the starting angular velocity ωs (n) (Expression 12). ). The target arrival time td (n) takes a positive or negative value depending on the acceleration direction or the deceleration direction of the optical disc 2.
[0109]
td (n) = {ωd (n) −ωs (n)} / C (12)
The comparison means 48 compares the target arrival time td (n) with the elapsed time t (n) by the time measuring means 18 and outputs the shorter time as the actual energization time ts (n). The absolute value of the energization time ts (n) is equal to the shorter of the absolute value of the target arrival time td (n) and the elapsed time t (n), and the sign of the energization time ts (n) is the target arrival time td. It is determined to be the same as the sign of (n). This energization time ts (n) is given to the starting angular velocity calculation means 46 and the disk motor heat generation amount calculation means 49.
[0110]
The disk motor heat generation amount calculation means 49 calculates the heat generation amount E (n) by multiplying the constant W indicating the power consumption of the disk motor 4 by the energization time ts (n) according to (Equation 13). The constant W is experimentally obtained in advance and stored in the ROM.
[0111]
E (n) = W · ts (n) (13)
Here, in jitter-free reproduction, signals are read from the optical disk 2 even if the optical disk 2 does not reach the target angular velocity. For this reason, the seek may end before the optical disk 2 reaches the target angular velocity ωd (n), and the next seek may subsequently be started. Therefore, depending on whether the next seek is performed before the optical disc 2 reaches the target angular velocity ωd (n) or the next seek is performed after the optical disc 2 reaches the target angular velocity ωd (n), The calorific value E (n) changes.
[0112]
First, when the next seek is performed after the optical disk 2 reaches the target angular velocity ωd (n), the elapsed time t (n) by the time measuring means 18 is longer than the target arrival time td (n), 13) is equal to (Equation 14), and the heat generation amount E (n) can be expressed as a function of the difference between the target angular velocity ωd (n) and the starting angular velocity ωs (n).
[0113]
E (n) = W · (ωd (n) −ωs (n)) / C (14)
When the next seek is performed before reaching the target angular velocity ωd (n), the target arrival time td (n) is longer than the elapsed time t (n) by the time measuring means 18, and (Equation 13) is ( The calorific value E (n) can be expressed as a function of the elapsed time t by the time measuring means 18.
[0114]
E (n) = Wt (n) (15)
However, when the rotation method of the optical disk 2 is set to the ZCLV method and seek is performed in the same zone, since the rotation speed of the optical disk 2 does not change, (Equation 14) is applied and the heat generation amount E (n) is set to 0. Become.
[0115]
The seek control means 51 uses the first allowable value Tth obtained experimentally in advance and stored in the ROM, and the operation is permitted or prohibited by the disk rotation setting means 43 except for the first point. This is the same as the seek control means 20 in the embodiment. When the operation is prohibited by the disk rotation setting means 43, the seek control means 51 does not set the interval time ti.
[0116]
The operation of the disk device configured as described above will be described.
[0117]
First, the host controller 41 drives and controls the head transfer motor 7 so that the optical head 5 moves to a predetermined position rd (0) on the inner periphery of the optical disk 2, and detects the presence or absence of the optical disk 2 through the optical head 5. 4, the type of the optical disc 2 is determined based on the output of the head signal processing circuit 12. Here, it is assumed that the type of the optical disk 2 is determined to be DVD-RAM.
[0118]
Since the type of the optical disk 2 is DVD-RAM, the disk rotation setting unit 43 sets the rotation method of the disk motor 4 to the ZCLV method, permits the operation of the temperature calculation unit 42 and the seek control unit 51, and generates heat. The disk linear velocity v is output to the calculating means 44.
[0119]
The starting angular velocity calculating means 46 sets the starting angular velocity ωs (1) as an initial value according to (Equation 16). The starting angular velocity ωs (1) is data indicating the disk angular velocity when the optical head 5 is at the predetermined position rd (0).
[0120]
ωs (1) = v / rd (0) (16)
The target position calculation means 16 selects an approximate expression or a data table indicating the correspondence between the address information of the DVD-RAM disk and the target position rd from the ROM. The time measuring means 18 starts measuring the elapsed time t (0). The accumulating means 19 stores the initial value T (0) of the predicted temperature value T in the RAM as T (0) = 0.
[0121]
In this way, recording / reproduction of the optical disc 2 becomes possible, and when the first seek command is issued from the host device 23 in this state, the target position calculation means 16 calculates the target position rd (1) from the address information. The target angular velocity calculation means 45 inputs the target position rd (1) and calculates the target angular velocity ωd (1) of the optical disc 2 at the target position rd (1). The target arrival time calculation means 47 inputs the target angular velocity ωd (1) and the starting angular velocity ωs (1), and calculates the energization time td (1) necessary to reach the target angular velocity ωd (1).
[0122]
When the second seek command is issued from the host device 23, the time measuring means 18 ends the time measurement, outputs the elapsed time t (1), and newly starts measuring the next elapsed time t (2). To do. The comparison means 48 compares the target arrival time td (1) with the elapsed time t (1), and calculates the time ts (1) when the disk motor 4 is actually energized. The disk motor heat generation amount calculation means 49 inputs the energization time ts (1) and calculates the heat generation amount E (1) according to (Equation 13). The integrating means 19 outputs a predicted temperature value T (1) from the calorific value E (1). The seek control means 51 compares the predicted temperature value T (1) with the allowable value Tth (1), calculates the interval time ti (1) according to (Equation 8), and seeks in response to the second seek command. Control is performed so that the third seek instruction is not executed within the interval time ti (1) after the start of execution. Here, the allowable value Tth indicates a temperature at which the warp angle of the optical disc 2 reaches the allowable limit value, and is a fixed value experimentally obtained in advance and stored in the ROM.
[0123]
On the other hand, the starting point angular velocity calculating means 46 receives the energization time ts (1) and outputs the next starting point angular velocity ωs (2). Similarly to the first seek command, the target position calculation means 16 calculates the target position rd (2), the target angular speed calculation means 45 calculates the target angular speed ωd (2), and the target arrival time calculation means 47 The target arrival time td (2) is calculated.
[0124]
When the third and subsequent seek instructions are issued, the same processing as the second seek instruction is performed.
[0125]
When the mth seek command is issued, the interval time ti (m-1) is calculated through the same process as described above, and the upper controller 41 determines the m + 1th seek within the interval time ti (m-1). Controls not to execute the instruction. As described above, since the timing at which the temperature prediction result is obtained is delayed by one seek, the timing at which the seek is prohibited is also delayed. Normally, the temperature increase of the disk motor 4 by one seek is the allowable value Tth. It is quite small compared to, so there is virtually no problem.
[0126]
By such control, only when a seek command is given excessively frequently from the host device 23, a necessary interval time is set, and the temperature increase of the disk motor 4 due to seek is suppressed to an allowable value or less.
[0127]
As described above, according to the second embodiment of the present invention, the temperature predicted value T is calculated only when a seek command is issued, and the frequency with which the seek command is issued is low. Since only the operation is repeated, the amount of calculation is small and the burden on the temperature calculating means 42 can be reduced. In addition, since temperature reduction due to natural heat dissipation is taken into consideration, temperature prediction can be performed with high accuracy, and control for limiting temperature rise to the heat resistant temperature or less can be performed even for parts where direct temperature measurement is difficult. it can.
[0128]
Furthermore, in this embodiment, since the temperature prediction of the disk motor 4 is performed, the following effects are obtained.
[0129]
First, temperature prediction with high accuracy can be performed even in a disk device that performs jitter-free reproduction. Jitter-free reproduction is a method in which a signal is read from the optical disk 2 before the optical disk 2 reaches a target rotational speed. In the disk device using this method, when the seek is repeated frequently several times continuously, the next seek is started before the disk motor 4 reaches the target rotational speed, and the transition of the target rotational speed and the disk motor The deviation from the actual change in the rotational speed of 4 becomes large. Therefore, if the temperature target value of the disk motor 4 is calculated simply by assuming that the previous target rotational speed is equal to the next starting rotational speed, the prediction accuracy becomes extremely poor. However, according to the present embodiment, the energizing time of the disk motor 4 is obtained by the comparing means 48, and the starting angular velocity calculating means 46 calculates the starting angular velocity of the disk using the energizing time. Even when the above is frequently repeated, the predicted temperature value of the disk motor 4 can be accurately calculated.
[0130]
Secondly, it is possible to provide a predicted temperature value having a high correlation with the warp angle of the optical disc 2, and to accurately suppress the warp angle to an allowable value or less. As described above, it has been found that the warpage of the optical disc 2 is caused not by the temperature of the entire optical disc 2 but by the temperature difference of each part of the optical disc 2, particularly the temperature difference between the inner periphery and the outer periphery of the optical disc 2. Since the predicted temperature value T obtained by the temperature calculating means 42 represents the temperature difference between the inner and outer circumferences of the optical disc 2, the predicted temperature value T and the warp angle of the optical disc 2 have a high correlation. Therefore, if the allowable value Tth is experimentally obtained in advance as the temperature that gives the allowable limit value of the warp angle of the optical disk 2 and set in the ROM, the temperature predicted value T can be suppressed to the allowable value Tth or less. The warp angle can be suppressed to an allowable value or less with high accuracy.
[0131]
Third, it is easy to cope with various disk rotation methods and rotation speeds. In a disk device that performs recording / reproduction of a plurality of types of optical disks, or a disk device that selects a disk rotation speed from a plurality of rotation speeds set in advance, the disk motor 4 at the time of seek depends on the rotation method and rotation speed of the optical disk. The amount of heat generated differs, and the temperature prediction tends to be complicated, and the accuracy of temperature prediction tends to decrease. In this embodiment, the disc discriminating unit 50 discriminates the type of disc, and the disc rotation setting unit 43 prohibits or permits the operation of the temperature calculating unit 42 and seek control unit 51 according to the discrimination result, Since the calculating means 42 performs temperature prediction using the disk linear velocity v, highly practical control can be performed for various disk rotation methods and rotation speeds.
[0132]
In this embodiment, the target position calculation means 16 calculates the target position rd (n) of the optical head 5 based on the target address information given by the seek command from the host device 23, and the target angular velocity calculation means 45 The target angular velocity ωd (n) at the target position rd (n) is calculated using the target position rd (n) and the disk linear velocity v. The target angular velocity calculation means 45 receives target address information from the host device 23. The target angular velocity ωd (n) may be directly calculated based on the above. Further, the temperature calculation means 42 is not limited to the target address information as long as the information indicates the target position, and may be any information such as the target zone.
[0133]
Further, the disc discriminating unit 50 may discriminate the disc diameter of the optical disc 2 and change the constant C of the temperature calculating unit 42 corresponding to the inertia moments of various optical discs. In this case, it is possible to reliably prevent warping of the various optical disks having different diameters.
[0134]
In the present embodiment, the predicted temperature value T represents the temperature difference between the inner circumference and the outer circumference of the optical disc 2. As shown in FIG. 2, for example, the first temperature measuring element 21 and the second temperature measuring element 22 such as a thermistor are used. Two places are installed near the inner periphery and the outer periphery of the optical disc 2, and the detection outputs of the temperature measuring elements 21, 22 are input to the temperature calculating means 42, and the temperature calculating means 42 uses the temperature measuring means 42. The difference between the detection outputs of the elements 21 and 22, that is, the temperature difference between the inner circumference and the outer circumference of the optical disk 2 may be obtained. If an interval time during which a seek command is not executed is set according to this temperature difference, the warp of the optical disk 2 Can be prevented. The second temperature measuring element 22 is not limited to the outer peripheral portion of the optical disc 2 and may detect the temperature at any position as long as it is separated from the inner peripheral portion of the optical disc 2.
[0135]
Of course, the first embodiment and the second embodiment can be parallel.
[0136]
(Embodiment 3)
FIG. 3 is a schematic configuration diagram of an optical disc apparatus according to the third embodiment of the present invention. In the third embodiment, the internal temperature rises due to heat generated by the disk motor 4 when the seek is continuously repeated a plurality of times. Therefore, the temperature rise is suppressed by temporarily reducing the drive current of the disk motor 4. The purpose is that.
[0137]
In FIG. 3, the optical disk 2, the turntable 3, the disk motor 4, the optical head 5, the guide shaft 6, the head transfer motor 7, the rack 8, the chassis 9, the case 10, the head signal processing circuit 12, the target position calculation means 16, the time measurement The means 18, the integrating means 19, the head driver 31, the transfer motor driver 32, the disk motor driver 33, the disk rotation setting means 43, the target angular velocity calculation means 45, the comparison means 48, and the disk discrimination means 50 are the same as in the second embodiment. is there.
[0138]
The optical disk device 59 introduces a reproducing optical disk such as a CD and a DVD-ROM and a recording and reproducing optical disk such as a PD and a DVD-RAM by a loading mechanism (not shown), discriminates the type of the disk, and information on the optical disk 2 Record or play back.
[0139]
The circuit unit 60 includes a head signal processing circuit 12, a head driver 31, a transfer motor driver 32, a disk motor driver 33, a host controller 61, and a servo controller 70.
[0140]
The host controller 61 is constituted by a CPU, DSP, RAM, ROM, and the like (not shown), and performs control based on programs and data stored in advance in the ROM. For example, the host controller 61 exchanges commands with the host device 23 via an external interface (not shown), performs data transfer, or controls the head signal processing circuit 12 and the servo controller 70. Various controls in the optical disk apparatus including The host controller 61 includes a disk rotation setting unit 43, a disk determination unit 50, a temperature calculation unit 62, and a seek control unit 63.
[0141]
The temperature calculation unit 62 includes a target position calculation unit 16, a time measurement unit 18, an integration unit 19, and a heat generation amount calculation unit 64, and the disk rotation setting unit 43 permits the operation of the temperature calculation unit 62 as in the second embodiment. Only when the host controller 61 executes a seek command from the host device 23, the temperature predicted value T (n) is output. This predicted temperature value T (n) indicates the temperature difference between the inner periphery and the outer periphery of the optical disc 2 due to the heat generated by the disc motor 4.
[0142]
The seek control means 63 compares the allowable value Tth stored in advance in the ROM with the predicted temperature value T (n) each time the host controller 61 executes a seek command from the host device 23, and calculates the predicted temperature value T (n ) Is less than or equal to a predetermined value Tth, flag 0 is output to the servo controller 70, and if it exceeds the predetermined value Tth, flag 1 is output to the servo controller 70.
[0143]
The heat generation amount calculation unit 64 includes a target angular velocity calculation unit 45, a comparison unit 48, a starting angular velocity calculation unit 66, a target arrival time calculation unit 67, and a disk motor heat generation amount calculation unit 69.
[0144]
The starting angular velocity calculating means 66 calculates the starting angular velocity ωs (n) at the nth temperature prediction time. The starting angular velocity ωs (n) is calculated according to (Equation 11) when the predicted temperature value T (n) is less than or equal to the allowable value Tth, and when the predicted temperature value T (n) exceeds the allowable value Tth (Equation 17). ). (Equation 17) is obtained by replacing the constant C in (Equation 11) with a constant C ′ having another value. As will be described later, when T (n)> Tth, the drive current to the disk motor 4 is limited to reduce the motor torque. Therefore, the angular velocity prediction is performed according to the state where the drive current is not limited and the state where the drive current is limited. Is to do. The constant C ′ is a positive constant determined in advance from the torque generated by the disk motor 4 and the moment of inertia of the optical disk 2 in a state where the drive current is limited, and is smaller than the constant C in (Equation 11). The constant C ′ is experimentally obtained in advance and stored in the ROM.
[0145]
ωs (n) = ωs (n-1) + C '· ts (n-1) (17)
The target arrival time calculation means 67 calculates the energization time td (n) required until the optical disc 2 reaches the target angular velocity ωd (n) from the target angular velocity ωd (n) and the starting angular velocity ωs (n). It is. Again, as will be described later, when T (n)> Tth, the drive current to the disk motor 4 is limited to reduce the motor torque. Therefore, the temperature predicted value T (n) is compared with the allowable value Tth to determine the temperature. When the predicted value T (n) is less than or equal to the allowable value Tth, the target arrival time td (n) is calculated according to (Equation 12), and when the temperature predicted value T (n) exceeds the allowable value Tth, The target arrival time td (n) is calculated according to Equation 18). (Equation 18) is obtained by replacing the constant C in (Equation 12) with the above-described constant C ′.
[0146]
td (n) = {ωd (n) −ωs (n)} / C ′ (18)
The disk motor heat generation amount calculation means 69 calculates a heat generation amount E (n) by multiplying a constant indicating the power consumption of the disk motor 4 by the energization time ts (n). Again, as will be described later, when T (n)> Tth, the drive current to the disk motor 4 is limited to reduce the motor torque. Therefore, the temperature predicted value T (n) is compared with the allowable value Tth to determine the temperature. When the predicted value T (n) is less than or equal to the allowable value Tth, the calorific value E (n) is calculated according to (Equation 13), and when the predicted temperature value T (n) exceeds the allowable value Tth, 19), the calorific value E (n) is calculated. (Equation 19) is obtained by replacing the constant W in (Equation 13) with a constant W ′ having another value. The constant W ′ is a value smaller than the constant W in (Equation 13) and is determined so as to satisfy the condition of (Equation 20), and this value is stored in the ROM in advance.
[0147]
E (n) = W '· ts (n) (19)
W ′ ≦ Tth / (τ · k) (20)
The servo controller 70 controls the head driver 31, the transfer motor driver 32, and the disk motor driver 33 based on the servo signal output from the head signal processing circuit 12 and the command from the host controller 61. The servo controller 70 is configured by a DSP or the like. For example, when the disk motor 4 is controlled based on the ZCLV rotation method, the servo controller 70 is based on the FG signal (rotation speed detection signal) input from the disk motor driver 33 and the target rotation speed. A current command value to the disk motor driver 33 is generated so that the disk motor 4 rotates at the target rotational speed. The servo controller 70 is provided with current command value limiting means 71. The current command value limiting means 71 is programmed to change its operation according to the flag from the seek control means 63. When the flag from the seek control means 63 is 0 (temperature predicted value T (n) is equal to or less than the allowable value Tth), the current command value generated by the servo controller 70 is output as it is, but the flag from the seek control means 63 is In the case of 1 (temperature predicted value T (n) exceeds the allowable value Tth), the current command value generated by the servo controller 70 is limited to a preset limit value Xlim or less and output. This limit value Xlim is stored in advance in the ROM. The output (current command value or limit value Xlim) of the current command value limiting means 71 is D / A converted and then supplied to the disk motor driver 33, and a drive current corresponding to the output is supplied to the disk motor 4. .
[0148]
FIG. 4 is a graph showing the relationship between the output of the current command value limiting means 71 and the drive current to the disk motor 4. In the graph of FIG. 4, the horizontal axis represents the output X of the current command value limiting means 71, and the vertical axis represents the drive current I to the disk motor 4. The output X is 8 bits and indicates a value in the range of −127 to 127. The output X and the drive current I to the disk motor 4 are approximately proportional to each other, but a dead zone where I = 0 is provided in the vicinity of X = 0, and in the vicinity of the maximum and minimum values (± Xmax) of X, I is Saturated value (± Imax). Here, the sign of the drive current I represents the direction of the current, where I> 0 represents energization in the motor acceleration direction and I <0 represents energization in the motor deceleration direction.
[0149]
Since the current command value limiting means 71 outputs the current command value generated by the servo controller 70 as it is if the predicted temperature value T (n) is equal to or less than the allowable value Tth, the current command value in the range of −Xmax to Xmax is set. In response to this, a drive current in the range of −Imax to Imax is supplied to the disk motor 4 in accordance with this. Thereafter, when comparing the magnitudes of the values, it is assumed that the comparison is based on an absolute value, and positive / negative due to directionality is not considered.
[0150]
When the predicted temperature value T (n) exceeds the allowable value Tth, the current command value limiting means 71 limits the current command value to the limit value Xlim or less. Here, the limit value Xlim is a value smaller than the maximum current command value Xmax, and a drive current Ilim smaller than the maximum drive current Imax is generated for this limit value Xlim. That is, if the current command value generated by the servo controller 70 is larger than Xlim, the limit value Xlim is output from the current command value limiting means 71, and the drive current Ilim is supplied to the disk motor 4. If the current command value generated by the servo controller 70 is less than or equal to the limit value Xlim, the current command value limiting means 71 outputs the current command value as it is, and the drive current in the range of −Ilim to Ilim is supplied to the disk motor 4. Supplied.
[0151]
As a result, when T (n)> Tth, the drive current to the disk motor 4 is limited to Ilim. The value of Ilim is experimentally determined so that the power consumption W ′ of the disk motor after the current limit matches the value set according to (Equation 20). In such a state where the drive current of the disk motor 4 is limited, the predicted temperature value T (n) can be suppressed to the allowable value Tth or less even if the seek is continuously performed without interruption.
[0152]
There are several factors for the power consumption W ′, such as heat generation due to the coil resistance of the disk motor 4 and mechanical loss of the motor, but most of the loss during seek is heat generation due to the coil resistance. Then, the relationship of (Equation 21) is approximately established.
[0153]
W '= R ・ Ilim ² (21)
With reference to FIG. 3 again, the operation of the disk device configured as described above will be described assuming that the type of the optical disk 2 is a DVD-RAM, for example.
[0154]
When the predicted temperature value T (n) is less than or equal to the allowable value Tth, the operation of the host controller 61 from the determination of the presence / absence of the optical disc 2 to the calculation operation of the predicted temperature value T (n) by the temperature calculation means 62 is as follows. The operation is substantially the same as that of the host controller 41 in the second embodiment. The temperature calculation means 62 calculates the nth predicted temperature value T (n) according to the following procedure when the (n + 1) th seek command is issued from the host device 23.
[0155]
First, the target position calculation means 16 calculates the target position rd (n) from the target address information of the nth seek, and the target angular speed calculation means 45 calculates the target angular speed ωd (n) of the disk according to (Equation 10). . The target arrival time calculation means 67 calculates the energization time td (n) required to reach the target angular velocity ωd (n) according to (Equation 12) from the target angular velocity ωd (n) and the starting angular velocity ωs (n). . The time measuring means 18 outputs the elapsed time t (n) from the time point when the nth seek command is issued, and the comparing means 48 compares the target arrival time td (n) with the elapsed time t (n) to actually measure the disk motor. 4 calculates the time ts (n) when the energization is performed.
[0156]
The disk motor heat generation amount calculation means 69 calculates the heat generation amount E (n) from the energization time ts (n) according to (Equation 13). The integrating means 19 outputs the predicted temperature value T (n) according to (Equation 9) from the calorific value E (n).
[0157]
The seek control means 63 determines that the predicted temperature value T (n) is less than or equal to the allowable value Tth, and outputs a flag 0 to the servo controller 70. The starting point angular velocity calculating means 66 outputs the next starting point angular velocity ωs (n + 1) according to (Equation 11) from the energization time ts (n). When the servo controller 70 inputs the flag 0 from the seek control means 63, the current command value limiting means 71 is deactivated. As a result, a maximum Imax drive current is supplied from the disk motor driver 33 to the disk motor 4 during seeking.
[0158]
On the other hand, when the predicted temperature value T (n) is larger than the allowable value Tth, the seek control means 63 outputs to the servo controller 70 a flag 1 indicating that the predicted temperature value T (n) is larger than the allowable value Tth. To do.
[0159]
The servo controller 70 operates the current command value limiting means 71 to limit the current command value to the limit value Xlim or less, thereby limiting the drive current supplied from the disk motor driver 33 to the disk motor 4 to Ilim or less. The host controller 61 changes the constants C and W used in the starting point angular velocity calculation unit 66, the target arrival time calculation unit 67, and the disk motor heat generation amount calculation unit 69 to the constants C ′ and W ′.
[0160]
When the next (n + 2) th seek command is issued and the (n + 1) th temperature predicted value T (n + 1) is calculated, the target position calculating means 16 uses the target position rd ( n + 1) is calculated, and the target angular velocity calculation means 45 calculates the target angular velocity ωd (n + 1) of the disk according to (Equation 10). The starting angular velocity calculating means 66 outputs the next starting angular velocity ωs (n + 1) according to (Equation 17) from the energization time ts (n). The target arrival time calculating means 67 calculates the target arrival time td (n + 1) according to (Equation 18) from the target angular velocity ωd (n + 1) and the starting angular velocity ωs (n + 1). The timing means 18 outputs the elapsed time t (n + 1) from the time point when the n + 1th seek command is issued, and the comparison means 48 compares the target arrival time td (n + 1) with the elapsed time t (n + 1). Then, the time ts (n + 1) when the disk motor 4 is actually energized is calculated. The disk motor heat generation amount calculation means 69 calculates the heat generation amount E (n + 1) according to (Equation 19) from the energization time ts (n + 1). The integrating means 19 outputs a predicted temperature value T (n + 1) according to (Equation 9) from the calorific value E (n + 1).
[0161]
In this way, each time a seek command is issued from the host device 23, the temperature calculation means 62 calculates the temperature predicted value T (n), compares it with the allowable value Tth by the seek control means 63, and calculates the temperature predicted value. When T (n) exceeds the allowable value Tth, the current command value limiting means 71 is operated to limit the drive current to the disk motor 4, and the constants used by the temperature calculating means 62 are C ′ and W ′. Set. If the predicted temperature value T (n) is less than or equal to the allowable value Tth, the current command value limiting means 71 is deactivated, the restriction of the drive current to the disk motor 4 is released, and each constant used by the temperature calculation means 62 is used. Is set to C and W.
[0162]
In the third embodiment described above, not only the same effects as those described in the second embodiment can be obtained, but also the following effects can be obtained.
[0163]
First, it is possible to reduce the increase in the average seek time of the disk device due to seek control. Regarding this average seek time, the method of inserting the interval time described in the second embodiment and the method of reducing the motor drive current described in the present embodiment are compared with the same heat generation amount of the motor.
[0164]
In the method of inserting the interval time according to the second embodiment, for example, if it is attempted to reduce the average heat generation amount of the motor by half, it is necessary to insert an interval time that is substantially the same as the drive time. Therefore, the average seek time is doubled.
[0165]
On the other hand, in the method of reducing the drive current according to the present embodiment, if the drive current is multiplied by 0.71 (= square root of 1/2) as shown in (Expression 21), the average heat generation amount of the motor is halved. On the other hand, since the average seek time is inversely proportional to the motor torque and the motor torque is proportional to the drive current, the average seek time is only increased by about 1.4 times. Accordingly, it is possible to suppress an increase in the average seek time.
[0166]
Secondly, in the disk device that performs jitter-free reproduction, it is possible to significantly suppress the increase in the average seek time. In general, when performing jitter-free reproduction, it is possible to read information before the disk rotation speed reaches the target rotation speed and shift to the next seek.
[0167]
However, in the method of inserting the interval time as in the second embodiment, the interval time is inserted after the drive current to the disk motor 4 is sufficiently reduced after waiting for the disk to reach the target rotational speed. When the interval time is inserted, jitter-free reproduction is not practically effective, and therefore the average seek time is particularly long when the interval time is inserted.
[0168]
On the other hand, in the method of reducing the motor drive current according to the present embodiment, the calorific value per unit time itself is reduced, so that it is not necessary to insert an interval time, and it can easily cope with jitter-free reproduction. Is possible. For this reason, according to the present embodiment, it is possible to suppress an increase in the average seek time particularly remarkably in a disk device that performs jitter-free reproduction.
[0169]
In the present embodiment, as the drive current of the disk motor 4 is reduced, the drive current is limited only by replacing the constants C and W used in the temperature calculation means 62 with smaller constants C ′ and W ′. Therefore, the temperature of the disk motor 4 can be predicted with high accuracy.
[0170]
In this embodiment, the current command value limiting means 71 limits the drive current to the disk motor 4, but in exactly the same manner, by limiting the current command value to the transfer motor driver 32, the head The drive current to the transfer motor 7 can also be limited.
[0171]
Of course, it is possible to parallel the first embodiment and the third embodiment.
[0172]
【The invention's effect】
As described above, according to the disk device of the present invention, the predicted temperature value is calculated using the target position of the head only when a seek command is issued. The temperature predicted value can be calculated with high accuracy simply by performing the calculation at a low frequency, and the burden on the apparatus necessary for performing the temperature prediction can be extremely reduced.
[0173]
Further, according to the disk device of the present invention, the warp angle of the disk can be accurately predicted based on the temperature difference of each part of the disk, and the operation of the disk driving means or the head moving means can be performed according to the output of the temperature calculating means. Therefore, the warpage of the disk can be effectively suppressed, and the reliability at the time of recording / reproducing by the head can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of an optical disc apparatus according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing a schematic configuration of an optical disc apparatus according to a second embodiment of the present invention.
FIG. 3 is a block diagram showing a schematic configuration of an optical disc apparatus according to a third embodiment of the present invention.
FIG. 4 is a graph showing the relationship between the output of current command value limiting means and the drive current to the disk motor in the third embodiment.
FIG. 5 is a block diagram showing an example of a conventional disk device.
[Explanation of symbols]
1,39,59 Optical disc apparatus
2 Optical disc
4 Disc motor
5 Optical head
7 Head transfer motor
11, 40, 60 Circuit part
12 Head signal processing circuit
13, 41, 61 Host controller
14, 42, 62 Temperature calculation means
15 Starting position calculation means
16 Target position calculation means
17, 44, 64 Calorific value calculation means
18 Timekeeping
19 Accumulation means
20, 51, 63 Seek control means
30, 70 Servo controller
71 Current command value limiting means
31 Head driver
32 Transfer motor driver
33 Disc motor driver

Claims (8)

Disk drive means for rotating the disk;
A head for recording or reproducing information on the disk;
Head moving means for moving the head from a starting position to a target position;
Temperature calculating means for calculating a difference between the temperature of the inner periphery of the disk and the temperature of the outer periphery of the disk ;
A disk device comprising: control means for controlling the disk drive means or the head moving means in accordance with the temperature difference calculated by the temperature calculation means.   2. The disk device according to claim 1, wherein the control means reduces the drive current to the disk drive means when the temperature difference calculated by the temperature calculation means exceeds a preset threshold value. A disc discriminating means for discriminating the disc type;
The method according to claim 1, wherein a method of calculating a temperature change by the temperature calculating unit or a method of controlling the disk driving unit or the head moving unit by the control unit is changed according to the type of the disc determined by the disc determining unit. The disk device described. 4. The disk device according to claim 3 , wherein the operation of the temperature calculation means or the control means is permitted and prohibited according to the type of disk determined by the disk determination means. Equipped with a rotation setting means for setting the number of rotations or the linear velocity of the disk,
A method for calculating a temperature change by the temperature calculating unit or a method for controlling the disk driving unit or the head moving unit by the control unit is changed in accordance with the number of rotations or the rotation linear velocity set by the rotation setting unit. Item 2. The disk device according to Item 1. 6. The disk apparatus according to claim 5 , wherein the rotational speed setting means sets the rotational speed or rotational linear velocity of the disk according to whether the disk rotation system is a CAV system, a CLV system, or a ZCLV system. 7. The disk device according to claim 6 , wherein when the disk rotation system is a CAV system, a constant rotation speed is set by the rotation setting unit, and operation of the temperature calculation unit or the control unit is prohibited. When the disk rotation method is the ZCLV method and seek is performed in the same zone, a fixed rotation number is set by the rotation setting unit, and the operation of the temperature calculation unit or the control unit is prohibited,
7. The disk device according to claim 6 , wherein when seek to another zone is performed, the rotation number is changed by the rotation setting unit, and the operation of the temperature calculation unit or the control unit is permitted.

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