JP3119726B2 - Compact disc player device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reproduces a digital signal stored as pits on a compact disk (CD) as a recording medium, and in particular, in the present invention, a voltage for canceling an offset from a focal point generated in an optical system or the like . Make adjustments
The present invention relates to a compact disc player device.

[0002]

2. Description of the Related Art Conventionally, there is the following technology in such a field. FIG. 23 is a diagram showing a conventional compact disc player device. The compact disk player device shown in FIG. 1 includes a disk rotating motor 101 for rotating a compact disk 100 forming a spiral information recording track, and a digital signal from a signal surface formed as a pit on the track of the compact disk 100. Optical head 10 for reading optically
2 is provided. The optical head 102 includes an objective lens 103 for condensing a laser beam at a focal point of the signal surface, and a focus coil 104 for causing the objective lens 103 to vertically follow a surface deflection of the compact disc 100 to focus on a track. A tracking coil 105 for moving the objective lens 103 to follow the eccentricity of the compact disc 100 in a direction substantially normal to the track by a laser beam, and a mirror 1 for changing the direction of a laser beam, which will be described later.
06 and the objective lens 103 which passes 50% of the laser light
Mirror 107 that passes 50% of the return light from
And a laser diode 108 which emits laser light having a single wavelength and the same phase and emits the laser light to the half mirror 107.
And a photodiode 109 that receives reflected light of the laser beam applied to the compact disc 100 as return light from the objective lens 103 and converts the reflected light into an electric signal.

In order to drive a focus servo with respect to the surface runout, the compact disk player apparatus detects a focus error from an intensity distribution on the photodiode 109 by an astigmatism method or a Foucault method. a detector 200, and offset canceling injection voltage current adjusting unit 202 to inject a voltage for canceling offset to the focus error,
An adder 201 for adding the offset voltage of the offset canceling injection voltage / current adjusting unit 202 and the error voltage of the focus error detector 200; and an adder 201 connected to the adder 201 for preventing oscillation of a closed loop of the focus servo. The phase compensating circuit 203 includes a driving circuit 204 connected to the phase compensating circuit 203 to supply a current to the focus coil 104 and drive a focus servo.

Further, in order to drive a tracking servo with respect to the eccentricity of the compact disc 100, the compact disc player apparatus uses a three-spot method, a push-pull method, or a DPD (Differential Phase Detection) from the light quantity distribution on the photodiode 109. A tracking error detector 300 for detecting a tracking error by a method, a phase compensation circuit 301 connected to the tracking error detector 300 for preventing closed-loop oscillation of tracking servo, and a tracking compensation circuit connected to the phase compensation circuit 301. A driving circuit 302 is provided for supplying a current to the coil 105 and driving a tracking servo.

The compact disc player device has an amplifier 400 for amplifying an electric signal from the photodiode 109 and a PLL 401 (Phase locked) connected to the amplifier 400 for extracting a bit clock.
Loop) and a data demodulation unit 402 connected to the PLL 401 for detecting and demodulating a synchronization pattern using a bit clock, performing error correction and jitter absorption, and outputting data.

Further, the compact disc player apparatus drives the data demodulation section to drive a constant linear velocity (CLV) servo so that the cycle of the longest pit or the shortest pit of the signal read from the compact disc 100 becomes a specified value. A frequency-phase comparison between a frame synchronization signal 402 and a reference frequency obtained by dividing the crystal clock is performed, and the error is fed back to the disk rotation motor 101.
L500 and a phase compensation circuit 501 connected to the PLL 500 for preventing closed-loop oscillation of a constant linear velocity servo.
And a drive circuit 502 connected to the phase compensation circuit 501 and controlling the disk rotation motor 101 based on an error generated by the PLL 500.

By the way, the focusing servo used in the compact disk player apparatus thus configured has a true focusing point at a position shifted (offset) from the original focusing point due to various factors. For this reason, at the time of adjustment before shipment from the factory, the reflection signal from the standard compact disk is monitored using a standard compact disk, and for example, an offset control is performed on the focusing control circuit so that the aperture ratio of the eye pattern of the signal is maximized. In order to apply a DC voltage or a DC current for canceling, an offset canceling injection voltage / current adjusting unit 202 attached to a control circuit
The value of the semi-fixed resistor is varied.

Further, since this offset differs for each compact disk player device, it is necessary to adjust the offset for each one.

[0009]

However, in the conventional compact disc player apparatus, adjustment is performed with a standard compact disc before shipment from the factory. Therefore, the offset is canceled by an initial adjustment value by a compact disc actually used after shipment. There is a problem that may not be.

There is also a problem that the offset fluctuates due to a change in the environment during use, and the offset may not be canceled by the initial adjustment value. Further, there is a problem that the offset fluctuates due to a temporal change during use, and the offset may not be canceled by the initial adjustment value. Further, since the adjustment is performed so as to maximize the aperture of the eye pattern of the reflection signal, the adjustment is qualitative, requires skill, and may not be accurately adjusted.

[0011] by the above-mentioned problem, in some cases or contains noise in the playback sound can not error correction, there is a problem that you or when Tsu there playing Ru incapable of such <br/>. Further, when the focus servo gain is lowered for some reason, the canceling voltage or current that is constantly injected may have a detrimental effect on the focus servo without accurately canceling the offset. For example, depending on the compact disk used after the actual shipment, there is a case where the initial adjustment value does not cancel out, such as a case where the focus gain fluctuates due to adhesion of a fingerprint or the like. Was Tsu is impossible to name noise in and play the playback sound can not error correction in this case
There is a problem that squirrel Ru.

Accordingly, in view of the above problems, the present invention provides a simple, accurate, or variable factor for adjusting to a true focal point at the time of offset adjustment (for example, differences in optical characteristics between one compact disc to be reproduced and one compact disc to be reproduced). It is an object of the present invention to provide a compact disk player device which can be adjusted to an optimum state with respect to an offset generated by the above and an offset fluctuation due to a change with time, and in which the injected canceling voltage or current accurately cancels the offset.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention mainly reads a reflection signal of a compact disc and converts a focus error signal into a focus error signal in order to cancel an offset with respect to a focal point generated in an optical system. In a compact disc player apparatus having an offset canceling injection voltage / current adjusting unit for injecting a DC voltage or DC current corresponding to the offset amount into a control circuit to be formed, the DC voltage or DC of the offset canceling injection voltage / current adjusting unit is provided. A sine wave AC voltage or AC current generating means for superimposing a sine wave AC voltage or an AC current on the current, a zero cross timing detecting means for detecting a zero cross timing of the sine wave AC voltage or the AC current, and a reflection signal of the compact disk. A lower envelope detecting means for detecting a lower envelope; A sample-and-hold that samples and holds the envelope signal at the zero-cross timing, integrating means for integrating the output signal of the sample-and-hold, determining means for determining whether an integrated value of the integrating means is larger than a fixed value, An injection voltage / current control device that adjusts a DC voltage or a DC current to be injected by the offset canceling injection voltage / current adjusting unit so that the integrated value is minimized according to a determination result of the determination unit. . Further, the present invention provides a control circuit for forming a focus error signal by reading a reflection signal of a compact disc and canceling an offset with respect to a focal point generated in an optical system, by applying a DC voltage or a DC current corresponding to the offset amount. A compact disc player device having an injection voltage / current adjusting unit for offset canceling to be injected, an offset canceling voltage / current switching means for adjusting the level of the DC voltage or DC current to be injected, and an upper envelope of a reflection signal of the compact disk. An upper envelope detecting means for detecting whether the signal of the upper envelope is larger than a predetermined threshold value,
Signal of a predetermined level when it is larger than the threshold value of
Determining a first determination means you output, and the lower envelope detector for detecting the lower envelope of the reflected signal of the compact disc, or signal of the lower envelope is larger than a predetermined threshold value , The predetermined threshold
A second determination means you outputs a determination signal of a predetermined level when also large Ri, said predetermined les than said first determination means
A bell determination signal is output, and the second determination means is
The judgment signal of the predetermined level is output
In addition, the level of the DC voltage or DC current to be injected is reduced.
And a voltage / current switching control device for controlling the offset canceling voltage / current switching means so as to make a quick change .

[0014]

According to the compact disk player of the present invention, the sine wave AC voltage or the AC current is superimposed on the DC voltage or the DC current of the offset canceling injection voltage / current adjusting section by the sine wave AC voltage / current generating means. The zero cross timing of the sine wave AC voltage or the AC current is detected by the zero cross timing detection means, the lower envelope of the reflection signal of the compact disc is detected by the lower envelope detection means, and the sample hold The signal of the lower envelope is sampled and held at the zero cross timing, the output signal of the sample and hold is integrated by the integration means, and the determination means determines whether or not the integrated value of the integration means is larger than a fixed value. , The note above The determination means a determination result by the DC voltage or DC current to be injected in the integrated value injection voltage current adjusting unit for the offset canceller to minimize is adjusted by the voltage-current control device. Further, according to the compact disk player of the present invention, the level of the DC voltage or DC current to be injected can be adjusted by the offset canceling voltage / current switching means, and the reflected signal of the compact disk is detected by the upper envelope detecting means. the upper envelope detector, the first signal of the upper envelope by determining means is determined is greater than a predetermined threshold Rutotomoni, said predetermined Teinoshi
When it is larger than the threshold value, a judgment signal of a predetermined level is output.
It is the force, the by the lower envelope detector below the envelope of the reflected signal of a compact disc is detected, whether the signal of the lower envelope is larger than a predetermined threshold Ru determined by the second determination means
Together with the predetermined threshold when the predetermined threshold is exceeded.
Determination signal of the bell is output, it's on the injection voltage current control device <br/>, the predetermined level than the first determination means
A determination signal is output and the determination signal is output before the second determination means;
When the judgment signal of the predetermined level is output,
Change the level of DC voltage or DC current to be
The offset canceling voltage / current switching means is controlled so as to perform the switching. Therefore, the adjustment before shipment from the factory is simple and accurate, the adjustment is made to the optimum state for each disk to be used even after the shipment from the factory, and the change at the time of lapse is adjusted to the optimum state. In addition, for a decrease in the reflected signal due to a small scratch or dirt that does not affect the offset error signal,
Since the offset canceling voltage current is not changed , more appropriate adjustment of the offset canceling voltage current can be performed.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a first premise example of a compact disc player device as a premise of the present invention. Note that although the same components throughout the figures represented using the same reference numbers or symbols. By changing the voltage (current) injected into the focusing control system to cancel the offset,
Focusing on the fact that the value of the lower envelope of the reflection signal of the compact disc changes and the value of the envelope becomes minimum at the focal point,
Be different from the conventional components shown in FIG. 2 3 In the figure, a focus error detector in the adder 201 200
An adder 205 for forming a signal to be added to the focus error signal from the switch, a switch 206 connected to one of the inputs of the adder 205, and the offset canceling signal output to the adder 205 via the switch 206. A sine wave AC voltage / current generator 207 is provided for adding a sine wave AC voltage or current by adding the voltage or current of the injection voltage / current adjusting unit 202. The sine-wave AC voltage / current generator 207 is set to a frequency lower than the upper limit frequency at which the objective lens 103 of the optical head 102 can operate.
The switch 206 starts and stops the injection of the sine wave AC voltage or the AC current by the sine wave AC voltage / current generating means 207.

Also, as different components, the disk sensor 600 is used to detect the replacement of the compact disk 100 or the like and determine whether or not the offset canceling injection voltage / current adjusting unit 202 needs to be readjusted. Compact disk 1 obtained from optical head 102
A lower envelope detecting means 601 for detecting a lower envelope (envelope) of the signal of the information stored in 00.
Multiplication means 602 for calculating the product of the output detected by the lower envelope detection means 601 and the sine wave AC voltage or AC current of the sine wave AC voltage / current generation means 207;
Integrating means 603 for integrating the operation result of the multiplying means 602
Determining means 604 for determining whether the output of the integrating means 603 is substantially zero, positive polarity, or negative polarity; and controlling the switch 206 based on the input of the signal from the disk sensor 600, The offset canceling injection voltage / current adjusting unit 202 is adjusted based on the determination result from the above, and the adjusted offset canceling injection voltage / current adjusting unit 202 is adjusted.
And an injection voltage / current control device 605 for holding the adjusted DC voltage or DC current by turning off. Next, the waveforms of the signals of the main parts will be described.

FIG. 2 is a diagram showing an eye pattern which is an output of the amplifier 400 of FIG. FIG. 3A shows an eye pattern of a reflected signal from the compact disc 100 when there is no deviation at the time of focusing. In this figure, the opening of the eye pattern is wide, and the lower envelope is minimum. FIG. 6B shows an eye pattern when there is a shift during focusing. In this figure, the opening is narrow and the lower envelope is rising. The reason why the lower envelope rises is that the reflection from portions other than the pits increases due to a shift at the time of focusing.

[0018] FIG. 3 is a graph showing changes in eye pattern when injected sine wave AC voltage (current). In this figure, along with the injection of the sine wave signal, the time axis is smaller than that in FIG. 2 so that the sine wave signal can be observed. This figure (a)
The upper diagram shows an eye pattern in which a sine wave AC voltage is injected when there is no deviation at the time of focusing, and the lower diagram shows a waveform of the injected sine wave and an offset canceling voltage. This figure (b)
The upper diagram shows an eye pattern in which a sine wave AC voltage is injected when there is a shift at the time of focusing, and the lower diagram shows a waveform of the injected sine wave and an offset canceling voltage. If there is a shift during focusing shown in the lower diagram of FIG. 6B, the offset canceling DC voltage or DC current to be injected becomes larger by Δ than the offset canceling voltage in the case shown in the lower diagram of FIG.
As shown in this figure (a), if a DC voltage or a DC current is adjusted by superimposing a sine wave AC voltage or an AC current of a frequency not high enough to allow the focus actuator to respond to the injected DC voltage or the DC current, Adjustment is performed while changing the DC voltage or DC current to be injected in the increasing direction and the decreasing direction. When the positive and negative values are changed around the focal point, the lower envelope of the reflection signal of the compact disc 100 is focused at the focal point. If the fluctuation to the positive and negative is the same, the fluctuation of the envelope is also the same and the minimum. As shown in FIG. 3B, when the fluctuation is made without centering on the focal point, the fluctuation of the lower envelope of the reflection signal of the compact disc 100 is not positive / negative since the fluctuation from the focal point to positive / negative. Become larger. Utilizing the relationship of the above phenomena, the injected DC voltage or DC current can be adjusted while observing the relationship between the fluctuation of the lower envelope of the reflected signal of the compact disc 100 and the injected sine wave voltage or sine wave current. Become.

FIG. 4 is a diagram showing the output waveform of each main part according to this embodiment. FIG. 9A shows the output waveform of the lower envelope detecting means 601 when there is no deviation from the top when focusing, the output waveform of the sine wave AC voltage / current generating means 207, the output waveform of the multiplying means 602, and 603 of the integrating means. Are shown. Similarly, FIG. 9B shows the output waveform of the lower envelope detection means 601 when the in-focus state is shifted from the top, the output waveform of the sine wave AC voltage / current generation means 207, the output waveform of the multiplication means 602, and the integration means. The output voltage of 603 is shown. As shown in FIG. 7A, when there is no deviation during focusing, the output of the integrating means 603 is zero, and FIG.
When there is a shift during focusing as shown in FIG.
The output of 3 is a positive value.

According to this embodiment, in the adjustment of the voltage for canceling the offset with respect to the focal point generated in the optical system or the like, when a DC voltage or a DC current is electrically injected into the focusing control to perform the sine wave AC. Reflected signal (read signal) of a compact disk obtained by superimposing voltage or alternating current
A product of a signal obtained by detecting the lower envelope and a superimposed AC signal is calculated, and the magnitude of the correction DC voltage or DC current is adjusted so that the integrated value becomes substantially zero. Therefore,
Adjustment before factory shipment is simple and accurate, and it is adjusted to the optimum state for each compact disc used after factory shipment,
Changes over time are also canceled and adjusted to the optimum state.

FIG. 5 is a diagram showing a second premise example of the compact disc player apparatus on which the present invention is based. As shown in the figure, the components of the first premise example in FIG.
The multiplying means 602 is omitted, and instead of the judging means 604, a judging means (level comparator) 606 for judging whether the integrated value is equal to or less than a predetermined voltage is provided so that the integrated value of the integrating means 603 is minimized.

FIG. 6 is a diagram showing output waveforms of respective main parts according to the second premise example. FIG. 9A shows the output waveform of the lower envelope detecting means 601 and the output voltage of the integrating means 603 when there is no deviation during focusing from above. Similarly, FIG. 9B shows the output waveform of the lower envelope detecting means 601 and the integrating means 603 when there is a shift during focusing from above.
Are shown. When there is no displacement at the time of focusing as shown in FIG. 11A, the output of the integrating means 603 is minimum, and when there is a displacement at the time of focusing as shown in FIG. The output of 603 is a value larger than the minimum value. According to this example , in the adjustment of the voltage for canceling the offset with respect to the focal point generated in the optical system or the like, when a DC voltage or a DC current is electrically injected into the focusing control, a sine wave AC voltage or an AC The current is superimposed, and the integrated value (low-pass filtering value) of the signal that detects the lower envelope of the obtained reflected signal (read signal) is calculated, and the correction value is set so that the integrated value is minimized. The magnitude of the DC voltage or DC current can be adjusted. That is, the adjustment can be performed while observing the amount of fluctuation of the lower envelope of the reflection signal of the compact disc 100. Further, by providing the determination means 606 with a reference voltage, the configuration can be simplified as compared with the first premise.

FIG. 7 is a diagram showing a compact disc player apparatus according to a first embodiment which is a feature of the present invention.
As shown in the figure, to the components of the second premise example of FIG. 5, the zero-cross timing detector 607 detects the timing of the zero crossing of the sine wave AC signal output from the sine wave alternating voltage current generating means 207 A sample and hold circuit 608 for sampling and holding an output signal of the lower envelope detecting means 601 between the lower envelope detecting means 601 and the integrating means 603 at the zero cross timing of the zero cross timing detecting means 607, for example, a charge / discharge circuit including a capacitor Is provided.

FIG. 8 is a diagram showing the output waveform of each main part according to the first embodiment. FIG. 7A shows the output waveform of the lower envelope detecting means 601, the output waveform of the zero-cross timing detecting means 607, the output waveform of the sample-and-hold 608, the output waveform of the integrating means 6 when there is no deviation during focusing from above.
An output voltage of 03 is shown. Similarly, FIG. 9B shows the output waveform of the lower envelope detecting means 601 and the zero-cross timing detecting means 60 when there is a shift during focusing from above.
7, the output waveform of the sample hold circuit 608, and the output voltage of the integrating means 603 are shown. According to this embodiment, the offset with respect to the focal point generated in the optical system or the like is set.
In the method of adjusting the extinguishing voltage, when a DC voltage or a DC current is electrically injected into the focusing control and a sine-wave AC voltage or an AC current is superimposed on the DC voltage or the DC current, a reflection signal ( The signal which detects the lower envelope of the read signal) is sampled at the timing of the zero crossing of the sine wave AC signal, and this value is held.
The magnitude of the correction direct current (current) can be adjusted so that the integrated value of the held value is minimized. In other words, the DC voltage or DC current to be injected can be adjusted while watching the signal of the lower envelope of the reflected signal of the compact disc 100 at the timing of the zero cross of the sine wave AC signal. In this figure, the output held by the discharge of the capacitor is reduced during the zero-cross timing, but since the discharge time constant is generally large, the decrease is very small. Is held.

FIG. 9 is a diagram showing a third premise example of the compact disc player apparatus on which the present invention is based. In this example, two points are focused on that the optimum offset canceling voltage depends on the loop gain of the focus servo, and that the loop gain of the focus servo that is attributable to the compact disc 100 is almost proportional to the amplitude of the reflected signal. adjusted optimally voltage counteract Oh <br/> offset in Rukoto changing the offset cancellation voltage by calculating the change in the focus gain due to the compact disc 100 by the amplitude of the reflected signal as a result. For this reason, in this figure, what differs from the conventional constituent element shown in FIG.
The adder 201 and the offset canceling injection voltage adjusting unit 2
02, an offset canceling voltage switching means 208 for varying the injection DC voltage of the offset canceling injection voltage adjusting section 202, and information of information stored in the compact disc 100 obtained from the optical head connected to the amplifier 400. Upper envelope detecting means 613 for detecting the upper envelope (envelope) of the signal, determining means 614 connected to the upper envelope detecting means 613 for determining the level of the detected envelope, and connected to the determining means 614. A voltage switching control device 615 for controlling the offset canceling voltage switching means 208 for adjusting the DC voltage injected by the offset canceling injection voltage adjusting unit 202 according to the determined level is provided.

FIG. 10 is a diagram showing the offset canceling voltage switching means of FIG. The offset canceling voltage switching means 208 shown in FIG.
The a voltage by resistors 2081 and 2082 partial pressure and also the resistance 2
081 and 2083 to form an output voltage V0 ,
It supplies the output voltage V0 to the adder 201. The selection of the partial pressure is performed by switches 2084 and 2085.
Hereinafter, the reduction of the amplitude of the reflection signal to be solved by the present embodiment will be described.

[0027] FIG. 11 is a diagram showing a decrease in the amplitude of the reflected signal of the compact disc that by the fingerprint or the like. As shown in FIG. 7A, when the offset is relatively small and the electrical cancellation is small, the amplitude of the reflected signal due to a fingerprint or the like decreases, and the focus gain decreases. As shown in FIG. 3B, when the offset is relatively large and the electrical cancellation is large, the electrical cancellation is large and cannot be canceled when the focus gain is lowered, and the degree of signal disturbance becomes severe. For this reason, error correction cannot be performed or the track is skipped. FIG. 3C shows a focus error signal from the focus error detector 200. In the normal state, the offset is canceled and the target (0) is followed. However, in the case of FIG. 3B, the focus error signal is disturbed by the injected voltage without canceling the offset when the focus gain is lowered. Adjustment of the voltage to cancel the offset according to this example against the above amplitude decrease
The adjustment is described below.

FIG. 12 is a diagram showing an output waveform of each main part of the third premise example. The output waveform of the amplifier 400, the output waveform of the upper envelope detection means 613, the two output waveforms of the determination means 614, and the output waveform of the offset canceling voltage switching means 208 are shown from the top. The output waveform of the amplifier 400 is a reflected signal of the compact disc 100,
As shown in FIG. 3A, the upper side of the reflected signal decreases due to a fingerprint or the like. As shown in FIG.
At 14, threshold voltages 1 and 2 are set, and as shown in FIGS. 6C and 6D, when the envelope level of the upper envelope detecting means 613 is smaller than the threshold value 1, the judgment output 1 is set. It becomes "H (high)", and when the envelope level is smaller than the threshold value 2, the judgment output 2 becomes "H". Switch 20 in FIG. 1 0 When this determination output 1 is "H" by the voltage switching control unit 615
When the judgment output 2 is "H", the switch 2085 is made. The two levels are provided as in the case of the judgment outputs 1 and 2 in order to match the voltage waveform to be corrected to the shape of the decrease in the amplitude of the reflected signal due to the fingerprint or the like. According to this example, in a method of adjusting a voltage for canceling an offset with respect to a focal point generated in an optical system or the like, when a DC voltage is electrically injected into a focus control (focus servo), the state of a reflected signal is monitored. Aside
If this amplitude decreases, control the injected DC voltage,
It is possible to adjust the voltage to cancel the optimal Oh <br/> offset even when the gain of the focus servo is varied. In other words, when the focus servo gain is reduced due to fingerprints on the compact disk used by the user, the playback state is maintained optimally, and the occurrence of decoding noise that disables error correction and the inability of playback such as track skipping to be avoided. it can.

FIG. 13 is a diagram showing a fourth premise example of a compact disc player apparatus as a premise example of the present invention.
Beat third precondition as well as optimal offset in this example
In order to prevent the change of the voltage for canceling the offset and to prevent the change of the voltage for canceling the offset from being made for a short change in the focus gain within a certain time in this case, the determination means is assumed to be different from the components shown in FIG. 614
The determination output continuation time determination means 616 for determining that the voltage switching control apparatus 615 outputs to the offset canceling voltage switching means 208 only when the determination output for a predetermined time or more is detected between the voltage switching control apparatus 615 and the voltage switching control apparatus 615. Is provided.

FIG. 14 is a diagram for explaining the operation of the switch of the offset canceling voltage switching means of FIG. As shown in the figure, the switch 2084 is made when the judgment output 1 is "H" for a certain period of time or longer, and the switch 2085 is made when the judgment output 2 is "H" for a certain period of time or longer. Hereinafter, the reduction of the amplitude of the reflected signal to be solved by the present example will be described.

[0031] FIG. 15 is a diagram showing a decrease in the amplitude of the reflected signal of the compact disc fingerprints, that by the scratches. FIG. 9A shows a decrease in the amplitude of the reflected signal due to a fingerprint, a scratch, or the like, which occurs when the offset is relatively small and the electrical cancellation is small, and a decrease in the focus gain due to this. FIG. 3B shows a decrease in the amplitude of the reflected signal due to a fingerprint, a scratch, or the like, which occurs when the offset is relatively large and the electrical cancellation is large, and a decrease in the focus gain due to this. If the offset canceling voltage is large, it cannot be canceled when the focus gain is lowered, and if the degree of signal disturbance becomes severe, error correction cannot be performed or the track will skip, as in the third premise. Normally, like the focus error signal shown in FIG.
The offset has been canceled and follows the target (0).
When the time of decrease in the focus gain is short, the disturbance of the focus error is small. When the focus gain decreases, the focus error is disturbed by the injected voltage without canceling the offset. This against more amplitude reduction
An example of adjusting the voltage to cancel the offset is described below.

FIG. 16 is a diagram showing the output waveform of each main part of the fourth premise. 9A shows the output waveform of the amplifier 400, and FIG. 9B shows the upper envelope detecting means 61.
3 (c) and (d) show the output waveforms of the judgment means 6.
14 shows the output waveform of the offset canceling voltage switching means 208. FIG. As shown in the figure, the judgment output continuation time judgment means 616 cancels the offset against the scratches on the compact disc 100.
Do not change the pressure . That is, when the judgment outputs 1 and 2 continue for a certain period of time Td1, Td2 or more , an offset is given.
Ru by changing the voltage to turn off blood. According to the present example, offsets that do not affect the offset error signal, such as scratches on the compact disc 100, are canceled.
In addition to the point that the voltage is not changed , the same operation and effect as in the third premise can be obtained.

FIG. 17 is a view showing a compact disc player apparatus according to a second embodiment which is a feature of the present invention. In the present embodiment adjusts the voltage to cancel the third precondition as well as optimal offset <br/> bets, also when the fluctuation of the lower envelope of the reflected signal is below a certain value or offset canceling voltage to avoid performing the change, in the view as the different components shown in FIG. 9, the means 601 for detecting the connected lower envelope (envelope) to the amplifier 400, the detected lower A determination unit 617 for determining the level of the envelope is provided. The voltage switching control device 615 controls the value of the DC voltage to be injected in accordance with the level determined by the determining means 614 and 617. However, the offset canceling voltage switching means 208 is controlled only when the level determination output of the lower envelope is detected. Control.

FIG. 18 is a diagram for explaining the operation of the switch of the offset canceling voltage switching means of FIG. As shown in the figure, the switch 2084 is made when the judgment output 1 is “H” and the judgment output 3 is “H”, and the switch 2085 is made when the judgment output 2 is “H” and the judgment output 3 is “H”. Become. Hereinafter, a reduction in the amplitude of the reflected signal to be solved by the present embodiment will be described.

FIG. 19 shows the result of fingerprints, scratches, small scratches, dirt, etc.
That shows a decrease in the amplitude of the reflected signal of a compact disc. In this figure (a), the offset is relatively small,
This shows a decrease in the amplitude of the reflected signal due to fingerprints, scratches, small scratches, dirt, and the like that occur when the electrical cancellation is small, and a decrease in focus gain due to this. FIG. 6B shows a decrease in the amplitude of the reflected signal due to fingerprints, scratches, small scratches, stains, and the like, which occur when the offset is relatively large and the electrical cancellation is large, and a decrease in focus gain due to this. If the offset canceling voltage is large, the signal cannot be canceled when the focus gain is lowered, and if the signal is severely disturbed, the error cannot be corrected or the track will fly. In this case, the decrease in the focus gain is small and the amount of the offset that cannot be canceled is small. As in the case of the focus error signal shown in FIG. 9C, the offset is canceled in the normal state, and the target (0) is followed. When the time of decrease in the focus gain is short, the disturbance of the focus error is small. When the focus gain decreases, the focus error is disturbed by the injected voltage without canceling the offset. Off according to the present embodiment for the above amplitude reduction
The adjustment of the voltage to cancel the set will be described below.

FIG. 20 is a diagram showing the output waveform of each main part of the second embodiment. 9A shows the output waveform of the amplifier 400, and FIG. 9B shows the upper envelope detecting means 61.
3 (c) and (d) show the output waveforms of the judgment means 6.
14 (e) shows the output waveform of the lower envelope detecting means 601, FIG. 17 (f) shows the output waveform of the judging means 617, and FIG. 4 shows an output waveform of the means 208. As shown in the figure (g), a compact disc 100 fingerprint, but Ru varying the droplet Chi consumption to voltage offset against scratches, small scratches, the droplet Chi consumption to voltage offsets for dirt change
Do not let . According to the present embodiment, the compact disc 10
Small crack for 0, hit offsets for those that do not affect the offset error signal so that the dirt
It is possible to appropriately adjust the voltage to be extinguished without changing it , and to achieve the same operation and effect as the third premise. The fourth comparison with shall changing the voltage on the basis of duration as a precondition technique of, response is good early timing Ru changing the voltage.

FIG. 21 is a view showing a compact disc player apparatus according to a third embodiment which is a feature of the present invention. In the present embodiment, the voltage for canceling the offset is adjusted optimally in the same manner as in the fourth premise, and in this case, the change in the voltage for canceling the offset is not performed for a short change in the focus gain within a certain time. In order to prevent the change of the voltage for canceling the offset even when the fluctuation of the lower envelope of the reflection signal is equal to or less than a certain value , the components shown in FIG. It is different from the determination means 614 and the voltage switching control device 615
The determination output continuation time determination means 616 that is the same as that used in the fourth premise example is provided between them. The reduction of the amplitude of the reflected signal to be solved by this embodiment is the same as that shown in FIG.

FIG. 22 is a diagram showing the output waveform of each main part of the third embodiment. 9A shows the output waveform of the amplifier 400, and FIG. 9B shows the upper envelope detecting means 61.
3 (c) and (d) show the output waveforms of the judgment means 6.
14 (e) shows the output waveform of the lower envelope detecting means 601, FIG. 17 (f) shows the output waveform of the judging means 617, and FIG. 4 shows an output waveform of the means 208. As shown in the figure (g), but offset with respect to the fingerprint of the compact disc 100 Ru varying the droplet Chi consumption to voltage, scratches, small scratches, the droplet Chi consumption to voltage offsets for dirt change
Do not let . According to the present embodiment, the compact disc 10
For offsets that do not affect the offset error signal, such as scratches for 0, small scratches, dirt, etc.
Cancel except that so as not to change the voltage, the fourth
The same operation and effect as those of the premise example can be obtained. In particular, in this embodiment, adjustment can be made more appropriately than in the second embodiment. In addition,
In the third premise example to the third embodiment described above, the target of offset cancellation is a voltage, but the present invention is not limited to this, and may be a current.

[0039]

As described above, according to the present invention, first, the sine wave AC voltage or AC current is converted to the DC voltage or DC current of the offset canceling injection voltage current adjusting unit by the sine wave AC voltage current generating means. The zero cross timing of the sine wave AC voltage or the AC current is detected by the zero cross timing detection means, the lower envelope detection means detects the lower envelope of the reflected signal of the compact disk, and the sample hold lower side. The signal of the envelope is sampled and held at the zero-cross timing, the output signal of the sample-and-hold is integrated by the integrating means, and whether or not the integrated value by the integrating means is larger than a fixed value is determined by the determining means. Integration value according to the judgment result of the judgment means Smallest way DC voltage or DC current to be injected offset canceller for injection voltage current adjusting unit is adjusted. Further, according to the compact disk player of the present invention, second, the level of the DC voltage or DC current to be injected can be adjusted by the offset canceling voltage / current switching means, and the reflection of the compact disk by the upper envelope detecting means can be adjusted. The upper envelope of the signal is detected, and the first determining means determines whether the signal of the upper envelope is greater than a predetermined threshold.
At the same time, when it is larger than this predetermined threshold,
The lower envelope detecting means detects the lower envelope of the reflected signal of the compact disk, and the second determining means determines whether the lower envelope signal is larger than a predetermined threshold value. is Rutotomoni, when greater than the predetermined threshold
Determination signal of a predetermined level is outputted, I by the injection voltage current control device, the determination of a predetermined level than the first determination means
A signal is output and a predetermined level is output from the second determination means.
DC to be injected when the
The offset canceling voltage / current switching means is controlled to change the voltage or DC current level to a small value. Therefore, adjustment before shipment from the factory is simple and accurate, and a decrease in the focus servo gain due to a fingerprint or the like attached to a compact disc can be corrected. In addition, since the voltage or current is not changed with respect to a decrease in the reflected signal due to a small scratch or dirt that does not affect the offset error signal , the switch is more appropriately turned off.
Adjustment of the voltage or current to cancel the set can be made.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first premise example of a compact disc player device as a premise of the present invention.

FIG. 2 is a diagram showing an eye pattern which is an output of the amplifier 400 of FIG.

FIG. 3 is a diagram showing a change in an eye pattern when a sine wave AC voltage or AC current is injected.

FIG. 4 is a diagram showing output waveforms of respective main parts according to a first premise example.

FIG. 5 is a diagram showing a second premise example of the compact disc player device as a premise of the present invention.

FIG. 6 is a diagram showing output waveforms of respective main parts according to a second premise example.

FIG. 7 is a diagram showing a compact disc player device according to the first embodiment of the present invention.

FIG. 8 is a diagram showing output waveforms of respective main parts according to the first embodiment.

FIG. 9 is a diagram showing a third premise example of the compact disc player device as a premise of the present invention.

FIG. 10 is a diagram showing the offset canceling voltage switching means of FIG. 9;

11 is a diagram showing a decrease in the amplitude of the reflected signal of the compact disc that by the fingerprint or the like.

FIG. 12 is a diagram showing output waveforms of respective main parts in a third premise example.

FIG. 13 is a diagram showing a fourth premise example of the compact disc player apparatus as a premise of the present invention.

14 is a diagram showing the operation of the switch of the offset canceling voltage switching means of FIG.

15 is a diagram showing a fingerprint, a decrease in the amplitude of the reflected signal of the compact disc that due to scratches.

FIG. 16 is a diagram showing an output waveform of each main part of the fourth premise example.

FIG. 17 is a diagram showing a compact disc player device according to a second embodiment of the present invention.

18 is a diagram showing the operation of the switch of the offset canceling voltage switching means of FIG.

19 fingerprints, scratches, shows a decrease in the amplitude of a small crack, that by the dirt compact <br/> preparative disc reflected signal.

FIG. 20 is a diagram showing output waveforms of respective main parts of the second embodiment.

FIG. 21 is a diagram showing a compact disc player device according to a third embodiment of the present invention.

FIG. 22 is a diagram showing an output waveform of each main part of the third embodiment.

FIG. 23 is a diagram showing a conventional compact disc player device.

[Explanation of symbols]

 100: compact disk 207: sine wave AC voltage / current generating means 601: lower envelope detecting means 602: multiplying means 603 ... integrating means 604, 606, 614, 617 ... determining means 605 ... injection voltage / current control device 607 ... zero cross timing detection Means 608, 611, 612 Sample hold 609 Positive peak detecting means 610 Negative peak detecting means 613 Upper envelope detecting means 616 ... Determination output duration determining means

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-56-7249 (JP, A) JP-A-64-39638 (JP, A) JP-A-3-35432 (JP, A) JP-A-59-1979 28254 (JP, A) JP-A-4-307429 (JP, A) JP-A-60-247831 (JP, A) JP-A-59-116940 (JP, A) JP-A-4-251444 (JP, A) SHIKAWA 59-145726 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7/085 G11B 7/09 G11B 7/095

Claims (3)

(57) [Claims] 1. A direct-current voltage or direct-current corresponding to the offset amount is injected into a control circuit for forming a focus error signal in order to read a reflected signal of a compact disk and cancel an offset with respect to a focal point generated in an optical system. A compact disc player device having an offset canceling injection voltage / current adjusting unit, comprising: a sine wave AC voltage or a sine wave AC for superimposing a sine wave AC voltage or an AC current on the DC voltage or the DC current of the offset canceling injection voltage / current adjusting unit. Voltage / current generating means; zero-cross timing detecting means for detecting zero-cross timing of the sine wave AC voltage or the AC current; lower envelope detecting means for detecting a lower envelope of the reflected signal of the compact disc; and the lower envelope At the zero-cross timing A sample and hold for sampling and holding; an integration means for integrating an output signal of the sample and hold; a determination means for determining whether an integrated value of the integration means is larger than a fixed value; and a determination result by the determination means. A compact disk player device comprising: an injection voltage / current controller for adjusting a DC voltage or a DC current to be injected by the offset cancellation injection voltage / current adjusting unit so that an integral value is minimized. 2. A DC voltage or a DC current corresponding to the offset amount is injected into a control circuit for forming a focus error signal in order to read a reflection signal of a compact disk and cancel an offset with respect to a focal point generated in an optical system. A compact disc player apparatus having an offset canceling injection voltage / current adjusting unit for adjusting the level of the DC voltage or DC current to be injected, and an upper envelope of a reflection signal of the compact disc. Upper envelope detecting means for detecting whether the signal of the upper envelope is larger than a predetermined threshold value , and when the signal of the upper envelope is larger than the predetermined threshold value,
A first determination means that to output the determination signal of a predetermined level, and a lower envelope detector for detecting the lower envelope of the reflected signal of the compact disc, the signal of the lower envelope than the predetermined threshold Is determined to be greater than the predetermined threshold value.
A second determination means you outputs a determination signal of a predetermined level, said predetermined level of the determination signal from the first determining means
Output from the second determination means.
If the bell judgment signal is output,
The DC voltage or DC current level
And a voltage / current switching control device for controlling the offset canceling voltage / current switching means. Reading a reflected signal from a compact disc;
Offsets the focal point generated by the optical system.
Control circuit to generate focus error signal to turn off
The DC voltage or DC current corresponding to the offset amount
Injection voltage / current adjustment unit for offset canceling
Compact disc player device, wherein the level of the DC voltage or DC current to be injected is adjusted.
Offset canceling voltage / current switching means, and an upper envelope of a reflected signal of the compact disk
Upper envelope detecting means for detecting a signal of the upper envelope, the signal of the upper envelope being larger than a predetermined threshold value.
Judgment is made, and when it is larger than the predetermined threshold
First determination means for outputting a determination signal of a predetermined level, and a lower envelope of a reflection signal of the compact disk
Lower envelope detecting means for detecting a signal of the lower envelope, the signal of the lower envelope being larger than a predetermined threshold value.
To determine the Kiika, when greater than said predetermined certain threshold
A second determination unit that outputs a determination signal of a predetermined level; and the determination signal of the predetermined level is output from the first determination unit.
Output for a predetermined time or more, and the second determination
Means for outputting the judgment signal of the predetermined level.
The level of the DC voltage or DC current to be injected,
And a voltage / current switching control device for controlling the offset canceling voltage / current switching means so as to reduce the voltage.
A compact disc player device characterized by the following: