JP2010231870A - Gain-adjusting device, gain adjusting method, and gain adjusting program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gain-adjusting device, a gain-adjusting method, and a gain-adjusting program in which increment on current component and heat component can be prevented automatically, at low cost and with simple constitution. <P>SOLUTION: A gain-adjusting device includes a standard reference signal generating means for generating a standard reference signal of a prescribed frequency; an adding means for adding the standard reference signal to an error signal in a servo loop; a filter means for making the prescribed frequency component of the error signal to which the standard reference signal is added pass through it; a phase difference detecting means for detecting the phase difference between the phase of the standard reference signal and the phase of the error signal passed through the filter means; and a gain-adjusting means for adjusting gain, based on difference between the phase difference detected by the phase difference detecting means and a predetermined target phase value. The gain-adjusting means sets the target phase value to a value which is -90 degrees or less, and in which change quantity of phase difference for change of gain is smaller than the saturated phase value which starts to become a threshold due to the influence of disturbance-noise input to the phase-difference detecting means. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technical field such as a gain adjusting device for adjusting a gain of a servo loop of a device capable of reading information from an information recording medium such as an optical disk.

  2. Description of the Related Art Conventionally, for example, in an optical disc recording / reproducing apparatus, a technique for adjusting gain of a servo loop is known in order to perform stable servo control (for example, see Patent Document 1). However, for example, when a disturbance noise having a high frequency component with respect to the servo band is applied to the servo loop during an optical disc playback operation, the servo suppression control does not work, resulting in an increase in current components and thermal components. It was.

  As means for solving such a problem, when a current detection circuit is provided and a current of a predetermined value or more is detected, it is effective to lower the gain and reduce the current and heat generation.

Japanese Patent Laid-Open No. 5-144025

  However, the conventional method requires a separate current detection circuit and a software process for adjusting the gain according to the magnitude of the current detected thereby, resulting in a problem that costs are increased.

  Therefore, the present application has been made in view of the above points, and an example of the problem is a gain adjustment device capable of automatically preventing an increase in a current component and a heat component with a simple configuration while suppressing cost. Another object of the present invention is to provide a gain adjustment method and a gain adjustment program.

  In order to solve the above-mentioned problem, the invention described in claim 1 is a gain adjusting device for adjusting a gain of a servo loop in an apparatus capable of reading information from an information recording medium, and generates a reference reference signal having a predetermined frequency. A reference reference signal generating means; an adding means for adding the reference reference signal to an error signal in the servo loop; a filter means for passing the predetermined frequency component of the error signal to which the reference reference signal is added; and the reference reference A phase difference detecting means for detecting a phase difference between the phase of the signal and the phase of the error signal that has passed through the filter means; a difference between the phase difference detected by the phase difference detecting means and a preset target phase value; Gain adjustment means for adjusting the gain based on the gain, the gain adjustment means, the target phase value is -90 degrees or less, and The phase difference detected by the phase difference detection means, which is smaller than the saturation phase value at which the change amount of the phase difference relative to the gain change starts to become less than the threshold due to the influence of disturbance noise input to the phase difference detection means. It is characterized by setting to.

  According to a second aspect of the present invention, there is provided a gain adjustment method for adjusting a gain of a servo loop in an apparatus capable of reading information from an information recording medium, the step of generating a reference reference signal having a predetermined frequency, and an error in the servo loop. A step of adding the reference signal to the signal, a step of passing the predetermined frequency component of the error signal to which the reference signal is added, through the filter means, and an error of the phase of the reference reference signal and the filter means A phase difference detection step for detecting a phase difference from the phase of the signal, and a gain adjustment step for adjusting the gain based on a difference between the phase difference detected by the phase difference detection step and a preset target phase value And the gain adjustment step sets the target phase value to −90 degrees or less, and is the detected phase difference and changes in gain. The amount of change in phase difference against, characterized in that said set to a value smaller than the saturation phase value begins to subthreshold by the effect of disturbance noise input to the servo loop.

  According to a fourth aspect of the present invention, there is provided a computer including a gain adjusting device for adjusting a gain of a servo loop in a device capable of reading information from an information recording medium, a standard reference signal generating means for generating a standard reference signal having a predetermined frequency, Adding means for adding the reference signal to the error signal in the servo loop; Filter means for passing the predetermined frequency component of the error signal to which the reference signal is added; Passing the phase of the reference signal and the filter means A phase difference detecting means for detecting a phase difference from the phase of the error signal, and the gain is adjusted based on a difference between the phase difference detected by the phase difference detecting means and a preset target phase value. The gain adjusting means functions as a gain adjusting means, and the gain adjusting means sets the target phase value to −90 degrees or less and the phase difference detection. The phase difference detected by the means is set to a value smaller than the saturation phase value at which the amount of change of the phase difference with respect to the gain change starts to become below the threshold due to the influence of disturbance noise input to the phase difference detecting means. It is made to function like this.

It is a figure which shows an example of schematic structure of the optical disk recording / reproducing apparatus which concerns on this embodiment. It is a figure which shows an example of a gain determination window input / output characteristic. (A) is a figure which shows a closed loop gain characteristic, (B) is a figure which shows a closed loop phase characteristic. It is a figure which shows an example of the relationship (phase characteristic) of the phase difference detected by the phase comparator 10, and the gain in a servo loop, when there is no disturbance noise. It is a figure which shows an example of the relationship (phase characteristic) of the phase difference detected by the phase comparator 10, and the gain in a servo loop, when there exists disturbance noise. It is a figure which shows an example of the input-output waveform of the phase comparator 10 using an EXOR circuit. It is a figure which shows an example of the input-output phase characteristic of the phase comparator 10 using an EXOR circuit. It is a figure which shows an example of the relationship between a target phase value and a saturation phase value in the phase characteristic in case there exists disturbance noise. FIG. 9 is a diagram illustrating an example of a relationship between a target phase value and a saturation phase value in the phase characteristics when the amount of disturbance noise is larger than that in the case illustrated in FIG. 8. It is a figure which shows the relationship between the amount of gain correction | amendment (the amount which reduces a gain), and the amount of disturbance noise. It is a flowchart which shows an example of a target phase value setting and a gain adjustment process.

  Hereinafter, embodiments of the present application will be described in detail with reference to the drawings. The embodiment described below is an embodiment when the present application is applied to an optical disc recording / reproducing apparatus such as a CD (Compact Disc), a DVD (Digital Versatile Disc), a BD (Blu-ray Disc), and an HDDVD. It is.

  First, the configuration and function of the optical disc recording / reproducing apparatus according to the present embodiment will be described with reference to FIG.

  FIG. 1 is a diagram showing an example of a schematic configuration of an optical disc recording / reproducing apparatus according to the present embodiment. As shown in FIG. 1, an optical disc recording / reproducing apparatus S includes a driver 1, a spindle motor 2, an optical pickup 3, an RF amplifier 4, a gain variable amplifier 5, an adder 6 (an example of adding means), a phase compensation equalizer 7, and an oscillator. 8 (an example of a standard reference signal generation unit), a bandpass filter (BPF) 9 (an example of a filter unit), a phase comparator 10 (an example of a phase difference detection unit), a gain determination window 11, an audio / video signal processing memory control 12, a memory 13, a DAC (digital / analog converter) 14, a display control unit 15, a microcomputer 16, and the like. The driver 1, the optical pickup 3, the RF amplifier 4, the gain variable amplifier 5, the adder 6, and the phase compensation equalizer 7 constitute a servo loop in servo control. The gain variable amplifier 5 and the gain determination window 11 constitute a gain adjusting unit. The microcomputer 16 functions as a target phase value setting unit by performing overall control of the above-described units and executing a gain adjustment program stored in an internal memory.

  The driver 1 drives and controls the spindle motor 2 and the optical pickup 3 according to the drive signal from the phase compensation equalizer 7. The optical pickup 3 irradiates a rotating optical disk D with a light beam, reads recorded information from the optical disk D, and supplies the read signal to the RF amplifier 4.

  The RF amplifier 4 amplifies the read signal from the optical pickup 3 and then supplies it to the audio / video signal processing memory control 12 and extracts error signals such as a tracking error signal and a focus error signal based on the read signal. This is supplied to the variable gain amplifier 5 and the band pass filter 9.

  The audio / video signal processing memory control 12 uses the memory 13 to perform demodulation and error correction of the read signal from the RF amplifier 4 to generate an audio signal and a video signal, and supply the audio signal to the DAC 14. The video signal is supplied to the display control unit 15. The DAC 14 converts an audio signal (digital signal) from the audio / video signal processing memory control 12 into an analog signal and outputs the analog signal to a speaker through an amplifier (not shown). Further, the display control unit 15 performs drawing processing on the video signal from the audio / video signal processing memory control 12 and outputs it to a display (not shown).

  On the other hand, the variable gain amplifier 5 adjusts the gain (gain) of the servo loop in accordance with the gain adjustment command from the gain determination window 11.

  The oscillator 8 generates a sine wave reference signal (also referred to as a disturbance signal) having a predetermined frequency in response to a generation command from the microcomputer 16, and supplies the reference signal to the adder 6 and the phase comparator 10. . The adder 6 adds the error signal from the gain variable amplifier 5 and the standard reference signal from the oscillator 8, that is, adds the standard reference signal to the error signal in the servo loop and supplies it to the phase compensation equalizer 7. The phase compensation equalizer 7 adjusts the phase of the signal from the adder 6 and supplies it to the driver 1 as a drive signal.

  The band-pass filter 9 passes a predetermined frequency (same frequency as the reference signal) component of the error signal, which is an error signal to which the reference signal is added by the adder 6 and has made a round of the servo loop, to pass through the phase comparator. 10 is supplied.

  The phase comparator 10 includes, for example, an EXOR circuit, and compares the phase of the standard reference signal from the oscillator 8 with the phase of the error signal that has passed through the bandpass filter 9 (that is, the signal that the standard reference signal has made a round of the servo loop). Then, those phase differences are detected and supplied to the gain determination window 11. The gain determination window 11 gives a gain adjustment command to the variable gain amplifier 5 based on the difference between the phase difference detected by the phase comparator 10 and a preset target phase value. More specifically, the gain determination window 11 outputs a gain adjustment command indicating a gain correction (change) amount (dB) according to the difference between the phase difference detected by the phase comparator 10 and the target phase value. Give to 5. As a result, the gain variable amplifier 5 performs gain adjustment (raising or lowering) by the gain correction amount (dB) indicated in the gain adjustment command.

  FIG. 2 is a diagram illustrating an example of a gain determination window input / output characteristic. As shown in FIG. 2, the gain determination window 11 can adjust the gain within the range of the change amount of the detected phase difference from −180 deg to 180 deg.

  FIG. 3A is a diagram illustrating the closed-loop gain characteristic, and FIG. 3B is a diagram illustrating the closed-loop phase characteristic. As shown in FIG. 3B, the target phase value at the time of gain adjustment is normally set in the vicinity of −φ = −90 deg.

  Here, the relationship between the phase difference detected by the phase comparator 10 and the gain in the servo loop will be described.

  FIG. 4 is a diagram showing an example of the relationship (phase characteristic) between the phase difference detected by the phase comparator 10 and the gain in the servo loop in the absence of disturbance noise, and FIG. 5 shows the presence of disturbance noise. In the case, it is a figure which shows an example of the relationship (phase characteristic) of the phase difference detected by the phase comparator 10 and the gain in a servo loop.

  As shown in FIG. 4, when there is no disturbance noise, the gain is set based on the phase difference −90 deg detected by the phase comparator 10 (that is, the error signal is delayed by 90 degrees from the reference signal). On the other hand, the linear characteristic changes linearly in the direction in which the phase difference increases and decreases.

  On the other hand, as shown in FIG. 5, when there is disturbance noise, that is, when disturbance noise is applied to the servo loop, the phase difference increases in reference to the phase difference of −90 deg detected by the phase comparator 10. The saturation phase value (saturated point) above and below (hatched portion) and the saturation phase value (saturated point) and below (shaded portion) in the direction in which the phase difference decreases (phase difference −) The characteristic of the vertical object around 90deg). This is due to the characteristics of the phase comparator 10 using the EXOR circuit. When random noise components are input to the phase comparator 10, the phase information approaches -90 deg.

  FIG. 6 is a diagram illustrating an example of input / output waveforms of the phase comparator 10 using the EXOR circuit. In the example shown in FIG. 6, A indicates a standard reference signal waveform, B indicates an error signal waveform that has passed through the bandpass filter 9, and C indicates an output signal waveform corresponding to the phase difference between A and B. In the phase comparator 10, the standard reference signal waveform and the error signal waveform are shaped into a square wave and then input to the EXOR circuit. In the example shown in FIG. 6, when the logics of A and B are different, the logic of C becomes high level. For example, when the phase difference between A and B is 0 deg, the duty of C is 0%, when C is -90 deg, the duty of C is 50%, and when C is -180 deg, the duty of C is 100%. . However, when noise is superimposed on A, the duty of C is offset in a direction approaching 50%.

  FIG. 7 is a diagram illustrating an example of input / output phase characteristics of the phase comparator 10 using the EXOR circuit. In the example shown in FIG. 7, the input phase difference (true value) indicates the true (calculated) phase difference between A and B, and the output phase difference is obtained when A and B are input to the phase comparator 10. The detected phase difference (corresponding to C) is shown. As shown in FIG. 7, the output phase difference is offset in a direction approaching −90 deg, with the duty approaching 50% from the input phase difference (true value) according to the amount of noise.

  As a result, as shown in FIG. 5, the saturation phase value of the phase difference detected by the phase comparator 10 approaches −90 deg as the amount of disturbance noise increases (in the direction of the arrow in the figure), and the phase characteristic becomes the linear characteristic. The range becomes narrower. Therefore, in order to make it less susceptible to disturbance noise, that is, to use a range in which the phase characteristic is linear even when disturbance noise is input, conventionally, the target phase value set in the gain determination window 11 is The center frequency (phase value) of the band-pass filter 9 is set so that the phase difference between the reference signal and the error signal that has passed through the band-pass filter 9 is in the vicinity of −90 deg with an arbitrary fixed gain value. It was set. However, even in this case, when disturbance noise having a high frequency component is applied to the servo loop, there is a problem that the gain becomes too large and the current component and the heat component increase.

  Therefore, in the present embodiment, the gain determination window 11 has the target phase value equal to or less than −90 deg, and the amount of change in the phase difference (phase difference detected by the phase comparator 10) with respect to the gain change. The value is set to a value smaller than the saturation phase value (saturation start phase value) that starts to become below the threshold value due to the influence of disturbance noise input to the phase comparator 10 (that is, the gain vs. phase characteristic starts to become non-linear characteristics). In accordance with this, the band-pass filter 9 adjusts the center frequency (set phase) so that the phase difference between the reference signal and the error signal that has passed through the band-pass filter 9 becomes the saturation phase value with an arbitrary fixed gain value. Value). This is because, for example, the center frequency of the bandpass filter 9 needs to be determined to a value such that the servo loop has an appropriate gain according to the shift amount of the target phase value. For example, when the appropriate target phase value for gain adjustment when the bandpass filter 9 is not shifted is φdeg, and the target phase value is set to φ−45deg, the shift amount of the bandpass filter 9 needs to be 0deg−45deg. .

  These saturation phase values are set by the microcomputer 16 giving a setting command to the gain determination window 11 and the bandpass filter 9 to the bandpass filter 9.

  FIG. 8 is a diagram illustrating an example of the relationship between the target phase value and the saturation phase value in the phase characteristics when there is disturbance noise. As shown in FIG. 8, when there is disturbance noise and the phase difference detected by the phase comparator 10 is the saturation phase value α, the gain determination window 11 adjusts the gain so that the target phase value is obtained (gain adjustment). Since adjustment is performed by giving a command to the variable gain amplifier 5, it is lower than the appropriate gain (the gain is appropriately corrected). That is, by setting the phase target value to −90 deg or less and a value that is intentionally smaller than the saturation phase value α of the disturbance noise whose gain is to be decreased, the gain is reduced when the saturation phase value is equal to or more than α, and any disturbance noise is generated. Even if the normal target phase value is entered and the gain increases too much and the current increases, the present embodiment automatically adjusts the gain to prevent the increase in current because the gain is automatically decreased. Further, the amount by which the gain is reduced can be changed depending on the method (size) of the target phase value.

  FIG. 9 is a diagram showing an example of the relationship between the target phase value and the saturation phase value in the phase characteristics when the amount of disturbance noise is larger than that shown in FIG. In the example shown in FIG. 9, since the amount of disturbance noise is larger than that in the example shown in FIG. 8, the range in which the phase characteristic becomes a linear characteristic is narrowed, and the saturation phase value β is the saturation phase value in the case shown in FIG. It is closer to -90 deg than α. In this case, when the phase difference detected by the phase comparator 10 is the saturation phase value β, the gain determination window 11 adjusts the gain so as to be the target phase value, and the case shown in FIG. Will further reduce the gain. That is, the gain correction amount automatically changes depending on the amount of disturbance noise, and the gain can be greatly reduced as the disturbance noise increases, thereby preventing the current from increasing beyond a certain value. In addition, by changing the target phase value, it is possible to set a threshold value for how much the noise starts to decrease over which disturbance noise.

  FIG. 10 is a diagram illustrating the relationship between the gain correction amount (amount to decrease the gain) and the amount of disturbance noise. As shown in FIG. 10, the gain correction amount increases as the target phase value decreases.

  Next, target phase value setting and gain adjustment processing of the optical disc recording / reproducing apparatus S will be described with reference to FIG.

  FIG. 11 is a flowchart illustrating an example of target phase value setting and gain adjustment processing.

  When the process shown in FIG. 11 is started, first, the microcomputer 16 determines the target phase value to be a value smaller than the saturation phase value of −90 deg or less and a value corresponding to the correction amount to reduce the gain. A setting command for setting the target phase value is given to the gain determination window 11 (step S1). Thus, the target phase value is set in the gain determination window 11.

  Next, the microcomputer 16 determines a center frequency at which the phase difference between the standard reference signal and the error signal that has passed through the bandpass filter 9 becomes the saturation phase value with an arbitrary fixed gain value, and sets the center frequency. Is given to the bandpass filter 9 (step S2). As a result, the bandpass filter 9 sets the center frequency, and the phase comparator 10 detects the phase difference between the error signal passing through the bandpass filter 9 with the center frequency set and the reference reference signal. .

  By simultaneously changing the two settings of steps S1 and S2, the gain correction amount due to disturbance noise can be made variable.

  Next, the microcomputer 16 gives a generation command to the oscillator 8 to generate the standard reference signal, thereby injecting disturbance into the servo loop (step S3).

  Next, the gain determination window 11 compares the set target phase value with the phase difference detected by the phase comparator 10 (step S4), and whether or not the phase difference falls within a predetermined range including the target phase value. Is determined (step S5). When it is determined that the phase difference is not within the predetermined range including the target phase value (step S5: NO), the gain determination window 11 performs gain correction according to the difference between the phase difference and the target phase value. A gain adjustment command indicating the amount is given to the variable gain amplifier 5 (step S6), and the process returns to step S3. On the other hand, when it is determined that the phase difference is within a predetermined range including the target phase value (step S5: YES), the process is terminated.

  As described above, according to the above-described embodiment, the target phase value in the gain determination window 11 is −90 deg or less, and the change amount of the phase difference with respect to the gain change is input to the phase comparator 10. Since it is configured to be set to a value smaller than the saturation phase value that starts to fall below the threshold due to the influence of disturbance noise, it is automatic only by setting the target phase value at the time of adjustment to an appropriate value in gain adjustment using phase information Since the gain is lowered, the existing gain adjustment circuit and sequence (generally used in LSIs, etc.) are used, and new software processing is not added and the cost is reduced and it is automatically configured with a simple configuration. An increase in current component and thermal component can be prevented. Since the variable gain amplifier 5, the bandpass filter 9, the phase difference detector 10, and the gain determination window 11 can all use the existing circuit configuration, they can be realized without adding a new configuration.

  In addition, by changing the target phase value, it is possible to set a threshold value for how much the noise starts to decrease over which disturbance noise.

  Further, the gain correction amount can be automatically changed according to the amount of disturbance noise.

  Further, since the disturbance noise detection gain can be adjusted even when information is being read from the optical disk D without affecting the servo operation, the disturbance noise detection gain can be adjusted at any position or all around the optical disk D.

  In addition, since the gain correction amount for disturbance noise can be varied according to the target phase value, the setting can be changed in real time as necessary depending on the optical pickup performance, ambient temperature, vibration, warpage of the optical disc D, and the like. That is, the target phase value is set so that the difference between the saturation phase value and the target phase value is increased according to the magnitude of the detected ambient temperature, vibration to the apparatus, or warp of the optical disc D. .

  In the above embodiment, the case where the gain adjusting apparatus of the present application is applied to the optical disc recording / reproducing apparatus has been described. However, the present invention can also be applied to other information recording / reproducing apparatuses constituting a servo loop. The present application is particularly effective as a means for suppressing current consumption and temperature rise in an apparatus that is expected to perform high-speed recording / reproduction.

  In the above embodiment, the gain variable amplifier 5, the phase difference detector 10, the gain determination window 11 and the like are configured by hardware, but may be configured by software. In this case, the computer is caused to function as a reference reference signal generating unit, an adding unit, a filter unit, a phase difference detecting unit, and a gain adjusting unit in accordance with the gain adjusting program according to the present application.

DESCRIPTION OF SYMBOLS 1 Driver 2 Spindle motor 3 Optical pick-up 4 RF amplifier 5 Gain variable amplifier 6 Adder 7 Phase compensation equalizer 8 Oscillator 9 Band pass filter 10 Phase comparator 11 Gain judgment window 12 Audio / video signal processing memory control 13 Memory 14 DAC
15 Display Control Unit 16 Microcomputer S Optical Disk Recording / Reproducing Device

Claims (4)

A gain adjusting device for adjusting a gain of a servo loop in a device capable of reading information from an information recording medium,
A reference reference signal generating means for generating a reference reference signal of a predetermined frequency;
Adding means for adding the standard reference signal to an error signal in the servo loop;
Filter means for passing the predetermined frequency component of the error signal to which the standard reference signal is added;
Phase difference detecting means for detecting a phase difference between the phase of the reference signal and the phase of the error signal that has passed through the filter means;
Gain adjusting means for adjusting the gain based on the difference between the phase difference detected by the phase difference detecting means and a preset target phase value;
With
The gain adjusting means has the target phase value of −90 degrees or less and the phase difference detected by the phase difference detecting means, and the amount of change in the phase difference with respect to the gain change is detected as the phase difference. A gain adjusting apparatus, characterized in that the gain is set to a value smaller than a saturation phase value that starts to become a threshold value or less due to the influence of disturbance noise input to the means. The gain adjusting device according to claim 1,
The filter means sets the center frequency so that a phase difference between the phase of the reference signal and the phase of the error signal that has passed through the filter means becomes the saturation phase value with an arbitrary fixed gain value. Gain adjustment device. A gain adjustment method for adjusting a gain of a servo loop in an apparatus capable of reading information from an information recording medium,
Generating a reference signal of a predetermined frequency;
Adding the reference signal to an error signal in the servo loop;
Passing the predetermined frequency component of the error signal to which the standard reference signal is added, through a filter means;
A phase difference detection step of detecting a phase difference between the phase of the reference signal and the phase of the error signal that has passed through the filter means;
A gain adjustment step of adjusting the gain based on a difference between the phase difference detected by the phase difference detection step and a preset target phase value;
With
In the gain adjustment step, the target phase value is −90 degrees or less, and the detected phase difference and the amount of change in phase difference with respect to gain change is input to the servo loop as disturbance noise. The gain adjustment method is characterized in that it is set to a value smaller than a saturation phase value that starts to become lower than the threshold value due to the influence of the above. A computer including a gain adjusting device for adjusting a gain of a servo loop in a device capable of reading information from an information recording medium,
A standard reference signal generating means for generating a standard reference signal of a predetermined frequency;
Adding means for adding the reference signal to an error signal in the servo loop;
Filter means for passing the predetermined frequency component of the error signal to which the reference signal is added;
Phase difference detection means for detecting a phase difference between the phase of the reference signal and the phase of the error signal that has passed through the filter means; and
Function as a gain adjusting means for adjusting the gain based on a difference between the phase difference detected by the phase difference detecting means and a preset target phase value;
The gain adjusting means has the target phase value of −90 degrees or less and the phase difference detected by the phase difference detecting means, and the amount of change in the phase difference with respect to the gain change is detected as the phase difference. A gain adjustment program that functions to set a value smaller than a saturation phase value that starts to become lower than a threshold value due to the influence of disturbance noise input to the means.

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