JP3619725B2 - Optical disk playback device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disc reproducing apparatus that includes an optical pickup and reproduces and outputs information recorded on an optical disc, and more particularly to gain control of a signal based on a return light amount detected by an optical pickup.
[0002]
[Prior art]
In an apparatus for reproducing an optical disk such as a CD (Compact Disk) or a DVD (Digital Versatile Disk), information is reproduced by irradiating the optical disk with laser light and detecting its return light (reflected light). The signal intensity (magnitude) based on the amount of return light greatly depends on the reflectivity of the disc. However, the reflectivity differs between CD and DVD, and even when the recording layer is a single layer or two layers in DVD. ing. For example, the CD is 70% or more, the single-layer DVD is 45 to 85%, and the dual-layer DVD is 18 to 30%.
[0003]
In an apparatus capable of reproducing both CD and DVD, information reproduction signal processing is performed by obtaining a signal from the optical pickup with an intensity within a predetermined range regardless of the reflectivity of the disk. In order to set the signal from the optical pickup to an intensity within a predetermined range, it is necessary to adjust the gain of the amplifier that amplifies the signal from the optical pickup every time the disk is reproduced.
[0004]
The gain adjustment is performed on the focus error signal and the RF signal obtained from the signal from the optical pickup, and the gain is controlled by a voltage control type amplifier (hereinafter referred to as VCA) that amplifies the RF signal and the focus error signal. This is done by controlling the applied voltage value (control voltage). Then, the gain is determined so that the focus error signal obtained during the focus search has an intensity within a predetermined range.
[0005]
Conventionally, the gain is adjusted (determined) by giving an initial value V0 as the VCA control voltage V, and calculating whether the intensity of the focus error signal from the VCA obtained when the control voltage is V0 is within a predetermined range. If it is within the range, the control voltage is determined to be V0, and when it exceeds the predetermined range (hereinafter this state is referred to as over), Δv is added to the control voltage at that time (initially V0 of the initial value) When the voltage is lower than the predetermined range (hereinafter, this state is referred to as “under”), Δv is subtracted from the control voltage at that time (initially V0 at first) to obtain a new control voltage. The control voltage is repeatedly changed so that the intensity of the focus error signal from the VCA falls within a predetermined range. A flowchart of the above gain adjustment is shown in FIG.
[0006]
In addition, such gain adjustment is performed depending on the type of optical pickup used, for example, switching the objective lens according to each reproduction mode, focusing using the hologram lens in accordance with the reproduction disk, or switching to each reproduction mode. Accordingly, the characteristics and the optical system differ depending on what is used by switching between the two optical pickups, etc., so that it is necessary to make the intensity of the obtained signal fall within a predetermined range.
[0007]
[Problems to be solved by the invention]
However, in the above-described method, since the intensity of the focus error signal obtained while increasing / decreasing the constant value Δv from the initial value V0 as the control voltage V is calculated, the initial value V0 and the increasing / decreasing value Δv are set. Is not appropriate, there is a possibility that the number of repeated calculations and adjustment (determination) time may increase before the intensity of the focus error signal converges within a predetermined range. Then, it takes a long time from the loading of the disc to the start of reproduction.
[0008]
The present invention has been made in view of such points, and it is possible to easily determine a control voltage in which the intensity of the focus error signal from the VCA falls within a predetermined range, and it takes a long time from the loading of the disc to the start of reproduction. Therefore, an object of the present invention is to provide an optical disc reproducing apparatus capable of shortening the time until the reproduction is started.
[0009]
[Means for Solving the Problems]
An optical disk reproducing apparatus according to a first aspect of the present invention is an optical pickup that outputs a signal based on information recorded on an optical disk, and a signal that outputs an RF signal and a focus error signal based on a signal output from the optical pickup. Forming means, an amplifying means for amplifying the RF signal and focus error signal output from the signal forming means based on the control voltage, a control means for controlling the control voltage in the amplifying means, and a control voltage controlled by the control means Storage means for storing two values of the intensity of the focus error signal amplified by the amplifying means based on the value and its control voltage, and the control means is a value of the intensity of the focus error signal amplified by the amplifying means. If the control voltage is not within the predetermined range, the control voltage is changed, and the strength of the focus error signal amplified by the amplification means based on the changed control voltage is changed. When the strength of is not within the predetermined range, and changing the value of the control voltage based on the value of the intensity value or the focus error signal of the stored two control voltages in the memory means.
[0010]
According to a second aspect of the present invention, there is provided the optical disc reproducing apparatus according to the first aspect, wherein the control means is configured such that one of the intensity values of the focus error signal stored in the storage means is smaller than a predetermined range and the other is predetermined. When the value is larger than the range, the control voltage value is changed to an intermediate value between two control voltage values stored in the storage means.
[0011]
According to a third aspect of the present invention, there is provided the optical disc reproducing apparatus according to the first aspect, wherein the control means is such that one of the intensity values of the focus error signal stored in the storage means is smaller than a predetermined range and the other is predetermined. When the value is larger than the range, the control voltage value is changed to a value obtained by linear interpolation from the intensity value and control voltage value of the two focus error signals stored in the storage means.
[0012]
An optical disk reproducing apparatus according to a fourth aspect of the present invention is an optical pickup that outputs a signal based on information recorded on an optical disk, and a signal that outputs an RF signal and a focus error signal based on the signal output from the optical pickup. Forming means, an amplifying means for amplifying the RF signal and focus error signal output from the signal forming means based on the control voltage, a control means for controlling the control voltage in the amplifying means, and a control voltage controlled by the control means Storage means for storing three or more values of the intensity of the focus error signal amplified by the amplifying means based on the value and its control voltage, and the control means comprises the intensity of the focus error signal amplified by the amplifying means. When the value is not within the predetermined range, the control voltage is changed, and the focus error signal amplified by the amplification means based on the changed control voltage When the intensity is not within a predetermined range, the control voltage value is changed to a value predicted based on three or more control voltage values stored in the storage means and the intensity value of the focus error signal. It is characterized by.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic configuration diagram of an optical disk reproducing apparatus according to an embodiment of the present invention.
[0014]
1 is an optical disk on which information is recorded, 2 is a spindle motor that drives the optical disk to rotate, 3 is an optical pickup that outputs a signal based on the information recorded on the optical disk 1, and at least both CD and DVD standards are played back. It is possible. As an optical pickup capable of reproducing both CD and DVD, one that switches two lenses according to each reproduction mode, one that focuses on each of CD and DVD by a hologram lens, and liquid crystal according to each reproduction mode Various devices have been proposed, such as a device that changes the numerical aperture by blocking laser light with a shutter, or a device that switches between two optical pickups depending on the respective reproduction modes.
[0015]
4 is a signal processing circuit as a signal forming means for outputting an RF signal and a focus error signal, and further a tracking error signal based on a signal output from the optical pickup 3, and 5 is an RF signal output from the signal processing circuit 4. The signal processing circuit 4 and the amplifying circuit 5 are usually formed by a single IC, which is a VCA type amplifying circuit as an amplifying means for amplifying a focus error signal based on a control voltage supplied from a servo DSP, which will be described later.
[0016]
6 is a servo DSP that receives an RF signal, a focus error signal, and a tracking error signal from the amplifier circuit 5 or the signal processing circuit 4 and performs servo control such as focus servo, tracking servo, and sledge servo, and rotation control of the spindle motor. Is a drive circuit for driving the optical pickup 3 and the spindle motor 2 based on the control from the servo DSP.
[0017]
8 is a controller as a control means for controlling the control voltage in the amplifier circuit 5 via the servo DSP 6, and 9 is a memory as a storage means controlled by the controller 8, and at least the control voltage And a capacity capable of storing two values of the intensity of the focus error signal amplified by the amplifier circuit 5 based on the control voltage and the control voltage.
[0018]
In such an apparatus, when the optical disk 1 is mounted on the apparatus, the controller 8 controls the drive circuit 7 to rotate the spindle motor 2 to rotate the optical disk 1. Further, the optical pickup 3 is moved to a predetermined position on the optical disc to perform a focus search.
[0019]
In the focus search, the controller 8 transfers V0 to the register R of the servo DSP 6 in order to give the voltage of the initial value V0 as a control voltage in order to adjust the gain in the amplifier circuit 5. The servo DSP 6 applies the voltage V0 given to the register R to the amplifier circuit 5 as the control voltage V. A signal from the optical pickup 3 is output to the signal processing circuit 4, and an RF signal, a focus error signal, and a tracking error signal are output from the signal processing circuit 4. The RF signal and the focus error signal are output to the amplifier circuit 5, and the amplifier circuit 5 amplifies and outputs the signal with a gain based on the control voltage V0.
[0020]
The controller 8 detects the intensity of the focus error signal from the amplifier circuit 5 obtained when the control voltage is V0, and determines whether or not the intensity is within a predetermined range. The controller 8 stores the detected intensity value of the focus error signal and the control voltage value at that time (V0 at this time) in the memory 9, and when the detected intensity value of the focus error signal is within a predetermined range. At this time, V0 is determined and set as a control voltage for adjusting the gain of the amplification circuit 5 with respect to the optical disk 1 loaded. When the intensity of the detected focus error signal is not within the predetermined range, if the correction amount of the predetermined control voltage set in advance is Δv, the control voltage V is set to V0 + Δv if over, and if it is under, the control is performed The focus search is performed again by setting the voltage V to V0−Δv, and control is performed so as to obtain a focus error signal.
[0021]
Therefore, the controller 8 transfers a new control voltage value (V0 + Δv or V0−Δv) to the register R of the servo DSP 6 in order to give a new control voltage (V0 + Δv or V0−Δv) as the control voltage V. The servo DSP 6 applies the voltage of the new control voltage value given to the register R to the amplifier circuit 5 as a control voltage. The signal from the optical pickup 3 is output to the signal processing circuit 4, the RF signal, the focus error signal, and the tracking error signal are output from the signal processing circuit 4, and the RF signal and the focus error signal are further controlled by the amplifier circuit 5. A signal is amplified and output with a gain based on the voltage (V0 + Δv or V0−Δv).
[0022]
Upon receiving the focus signal amplified by the amplifier circuit 5, the controller 8 detects the intensity of the focus error signal and determines whether or not the intensity is within a predetermined range. The controller 8 stores the intensity value of the detected focus error signal and the control voltage value at that time (V0 + Δv or V0−Δv at this time) in the memory 9, and the detected intensity value of the focus error signal is within a predetermined range. In this case, the current control voltage value (V0 + Δv or V0−Δv) is determined and set as a control voltage for adjusting the gain of the amplifier circuit 5 with respect to the optical disc 1 loaded at that time.
[0023]
When the intensity of the detected focus error signal is not within the predetermined range, the controller 8 is in the over state and the intensity value of the focus error signal at the control voltage V0 previously stored in the memory 9 is also over ( Therefore, the current control voltage is V0−Δv), and the control voltage is further −Δv to V0−2Δv, and the focus search is performed again to obtain the focus error signal, and the gain of the amplifier circuit 5 is adjusted. When the intensity of the focus error signal is in the over state and the intensity value of the focus error signal at the control voltage V0 previously stored in the memory 9 is under (therefore, the current control voltage is V0 + Δv), the control voltage Is set to V0 + Δv / 2, that is, an intermediate value between the two control voltages stored in the memory 9, a focus search is performed again, and control is performed so as to obtain a focus error signal in order to adjust the gain of the amplifier circuit 5.
[0024]
Alternatively, when the intensity of the detected focus error signal is not within the predetermined range, the controller 8 is in the under state and the intensity value of the focus error signal at the control voltage V0 stored in the memory 9 is also under. When the current control voltage is V0 + Δv, the control voltage is further increased by + Δv to V0 + 2Δv, and the focus search is performed again to obtain the focus error signal, thereby adjusting the gain of the amplifier circuit 5. When the intensity of the focus error signal is under and the intensity value of the focus error signal at the control voltage V0 previously stored in the memory 9 is over (thus, the current control voltage is V0−Δv), The control voltage is set to V0−Δv / 2, that is, an intermediate value between two control voltages stored in the memory 9, and a focus search is performed again to obtain a focus error signal to adjust the gain of the amplifier circuit 5. To control.
[0025]
Then, the controller 8 repeats the change of the control voltage and the detection of the intensity of the focus error signal amplified by the amplifier circuit 5 based on the changed control voltage until the intensity of the focus error signal falls within a predetermined range. Thus, when a focus error signal having an intensity within a predetermined range is obtained, the value of the control voltage at that time is determined as the gain in the amplifier circuit 5 when reading the information recorded on the optical disk mounted at that time. The control voltage is set, and thereafter, information is read / reproduced from the optical disk. The above flowchart is shown in FIG.
[0026]
In the above-described embodiment, the memory that stores the value of the control voltage and the focus error signal amplified by the amplifier circuit 5 based on the control voltage is configured separately from the controller 8, but is limited to this. For example, a memory or a register built in the controller 8 may be used.
[0027]
By the way, in the above-described embodiment, when the intensity of the focus error signal amplified by the amplifier circuit 5 does not enter the predetermined range twice in succession, the value of one intensity is smaller than the predetermined range and the intensity of the other is smaller. If the value is larger than the predetermined range, the control voltage value is changed to an intermediate value between the two control voltage values to perform gain adjustment. With this configuration, the time required for gain adjustment of the amplifier circuit can be shortened, and the time until the reproduction of information from the optical disk can be shortened. However, the control voltage value is set to two control voltages. The intensity value of the focus error signal is determined by linear interpolation from the two control voltage values stored in the memory 9 and the intensity value of the focus error signal. It is also possible to adjust the gain of the amplifying circuit 5 by calculating a control voltage that falls within the above range and performing a focus search again using that value as the control voltage.
[0028]
FIG. 3 is a diagram for explaining an example of control voltage setting by linear interpolation. As can be seen from FIG. 3, when the intensity of the focus error signal amplified by the amplifier circuit 5 does not enter the predetermined range twice in succession, the value of one intensity is smaller than the predetermined range and the value of the other intensity. Is larger than the predetermined range, the focus error signal is determined by linear interpolation (a linear equation indicating a straight line) from the two control voltage values stored in the memory 9 and the intensity value of the focus error signal. A control voltage value that falls within the range (for example, a control voltage value that is a value of the intensity at the center of the predetermined range) can be obtained. By performing the focus search again with the value of the control voltage obtained by linear interpolation, it is possible to further reduce the time required for gain adjustment of the amplifier circuit.
[0029]
Further, when the intensity of the focus error signal is detected three times or more, it is stored in the memory together with the respective control voltages, and nonlinear interpolation is performed from the intensity values of these three or more focus error signals and the control voltage values. A control voltage value in which the focus error signal falls within a predetermined range (for example, a control voltage value having a central intensity value within the predetermined range) may be obtained. Then, the focus search may be performed again with the control voltage of that value to adjust the gain of the amplifier circuit 5.
[0030]
【The invention's effect】
As is apparent from the above description, when the intensity of the focus error signal amplified by the amplifier circuit does not enter the predetermined range twice in succession, the value of one intensity is smaller than the predetermined range. If the other intensity value is larger than the predetermined range, the gain is adjusted by changing the control voltage value to an intermediate value between the two control voltage values or a value obtained by linear interpolation. The intensity of the focus error signal can be quickly converged within a predetermined range, and the control voltage at which the intensity of the focus error signal falls within the predetermined range can be easily determined. Then, the time required for gain adjustment of the amplifier circuit is shortened, and it is possible to provide a playback device that has a short time from the mounting of the optical disk to the start of information playback.
[0031]
Also, when the intensity of the focus error signal is detected three or more times, the intensity of the focus error signal converges within the predetermined range by obtaining a control voltage value in which the focus error signal falls within the predetermined range by nonlinear interpolation. It can be easily performed in a short time.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an optical disk reproducing apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart of gain adjustment according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating linear interpolation for gain adjustment according to another embodiment of the present invention.
FIG. 4 is a flowchart of conventional gain adjustment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical disk 2 Spindle motor 3 Optical pick-up 4 Signal processing circuit (signal formation means)
5 Amplification circuit (amplification means)
6 Servo DSP
7 Drive circuit 8 Controller (control means)
9 Memory (memory means)

Claims (2)

An optical pickup that outputs a signal based on information recorded on an optical disc, a signal forming unit that outputs an RF signal and a focus error signal based on a signal output from the optical pickup, and an RF signal output from the signal forming unit Amplifying means for amplifying the focus error signal based on the control voltage, control means for controlling the control voltage in the amplifying means, the value of the control voltage controlled by the control means and the amplifying means based on the control voltage Detection means for detecting the value of the focus error signal, and storage means for storing the value of the focus error signal and the value of the control voltage detected by the detection means,
When the value of the focus error signal detected by the detection means is not within a predetermined range, the control means stores the value of the focus error signal and the value of the control voltage in the storage means, changes the control voltage, and changes the change The value of the focus error signal based on the control voltage is detected, and when one of the value of the focus error signal and the value of the focus error signal stored in the storage unit is smaller than the predetermined range and the other is larger than the predetermined range, An optical disk reproducing apparatus, wherein the control voltage value is changed to an intermediate value between the changed control voltage value and the control voltage value stored in the storage means. An optical pickup that outputs a signal based on information recorded on an optical disc, a signal forming unit that outputs an RF signal and a focus error signal based on a signal output from the optical pickup, and an RF signal output from the signal forming unit Amplifying means for amplifying the focus error signal based on the control voltage, control means for controlling the control voltage in the amplifying means, the value of the control voltage controlled by the control means and the amplifying means based on the control voltage Detection means for detecting the value of the focus error signal, and storage means for storing the value of the focus error signal and the value of the control voltage detected by the detection means,
The control means, when the value of the first focus error signal detected by the detection means is not within a predetermined range, the value of the first focus error signal and the first control voltage corresponding to the first focus error signal The value is stored in the storage means, the control voltage is changed, the value of the second focus error signal corresponding to the changed second control voltage value is detected, the value of the second focus error signal and the storage When one of the values of the first focus error signal stored in the means is smaller than the predetermined range and the other is larger than the predetermined range, the control voltage value is changed to the first focus error signal value and the first control voltage. And a value obtained by linearly interpolating a set of the second focus error signal value and the second control voltage value corresponding to a predetermined focus error signal value within the predetermined range. Optical disk reproducing apparatus, characterized in that to change.

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