KR100368740B1 - Tilt Detector, Tilt Compensator, Tilt Detection Method and Tilt Compensation Method - Google Patents

Abstract

The present invention provides a tilt detection, correction device and method for providing a tilt angle detection device with high accuracy, without incurring a price increase, and a simple head structure. A sensor 7 for receiving a signal, and outputting a signal for the received light amount, a signal converter 13 for inputting a signal from the sensor, and outputting an amplitude of the input signal, a sinusoidal signal generator 18, and a sine wave. A multiplier 14 for inputting the output of the signal generator and the output of the signal converter and outputting the product of these inputs, an integrator 15 for inputting the output of the multiplier and outputting the integral value of the input, and a predetermined DC component Driven by an output of the adder 17, an adder 17 for inputting the output of the DC component output means and the output of the sine wave signal generator, and outputting the sum of these inputs; And aberration correction means 10 for correcting the aberration generated by the tilt of the light beam and the disk recording surface.

Description

Tilt Detector, Tilt Compensator, Tilt Detection Method and Tilt Correction Method {Tilt Detector, Tilt Compensator, Tilt Detection Method and Tilt Compensation Method}

The present invention relates to tilt detection and correction in a tilt servo device of an optical head such as an optical disc player.

An optical disk apparatus is a device that scans fine marks (pits) on a disk by means of light beams output small and narrowly to an objective lens, and reproduces recorded information. At this time, the disk surface is inclined with respect to the light beam from the optical head due to the bending of the disk, the shaking of the surface, and the like. In such a case, accurate reading is difficult because the light beam is incident inclined with respect to the disk surface in order to reproduce the information recorded on the optical disk.

Fig. 5 is a diagram showing a change due to the inclination (tilt) of the disk surface of the light spot formed by the light beam. In addition, the figure shown below of FIG. 5 shows the shape of a light spot, and the upper figure shows the intensity distribution of the light in such a light spot.

5B shows the shape and intensity distribution of the light spot when the light beam and the disk surface are perpendicular, and the shape of the light spot is symmetrical. 5A and 5C show the shape and intensity distribution of the light spot when the disk plane with respect to the light beam is inclined, the coma aberration occurs in the light spot on the disk, and the shape of the light spot is It is asymmetrical shape.

In order to prevent such an aberration from occurring, the optical disk device includes a tilt servo device that corrects the optical axis of the optical head to be perpendicular to the disk surface. This tilt servo apparatus is provided with the tilt detection means for detecting the inclination of the light beam and the disk surface which an optical head scans with a tilt amount.

The tilt amount can generally be detected by the tilt sensor. If the tilt detection means is configured to install the tilt sensor separately from the optical system that generates the light beam for reproducing the information recorded on the optical disk, there is a certain amount of distance between the tilt sensor and the optical head to avoid interference with the objective lens. Need distance. However, the distance between them is made as close as possible, and preferably the amount of inclination of the disk surface at the position where the light spot is projected can be obtained.

6 is a perspective view showing an example of a configuration of a head portion of a conventional optical disk apparatus. On the upper surface of the head portion 102 located below the optical disc 101, an objective lens 103 of the optical head and a tilt sensor 104 of the tilt detection means are respectively configured. The light spot 106 passes through the tilt sensor 104 by the light beam 105 scanned from the objective lens 103, and is arranged approximately on the track 107 of the disk surface. 104 detects the position of the light spot 106 and the amount of inclination of the disk surface approximately.

However, since the position of the light spot and the tilt sensor do not completely coincide with the head portion of the above configuration, the detection value by the tilt sensor cannot necessarily include an error, for example, by increasing the recording density of the disk, If tilt correction is required, there is a problem that sufficient precision is not secured.

In addition, since the optical head and the tilt detection means are separately configured, the number of parts increases, resulting in a unit cost increase and a complicated configuration of the head portion.

The present invention has been made to solve the above problems, and the present invention provides a tilt detection apparatus and method in a radial direction in which a high precision detection value is obtained and the unit cost is not increased without causing a unit cost increase, and such a tilt detection apparatus and method. An object of the present invention is to provide a tilt correction apparatus and method.

1 is an overall configuration diagram of an information reproducing apparatus according to an embodiment of the present invention;

Figure 2 is an internal configuration of the control means according to an embodiment of the present invention.

3 is a diagram showing the relationship between the amount of correction of the tilt angle by the tilt element and the RF amplitude;

4 is a diagram showing a relationship between sin (ωt), RF amplitude, multiplication result, and integration result;

5 is a view showing the change by the inclination of the disk surface of the light spot formed by the light beam,

6 is a perspective view showing an example of a head portion configuration of a conventional optical disk device.

♣ Explanation of symbols for main part of drawing ♣

1, 101: optical disc (disc) 2, 107: track

2a: feet 2b: recording surface

3: head 4: laser diode

4a, 7a: collimated lens 5: beam splitter

6, 103: objective lens 7: sensor

7a: collimated lens 8, 108: light spot

8a, 105: light beam 9: focus actuator

10: tilt element (aberration correction means) 11: optical axis

12: control means 13: signal converter

14: Multiplier 15: Integrator

16: DC component output means 17: adder

18: sine wave signal generator 19: counter

102: head 104: tilt sensor

According to an aspect of the present invention, there is provided a light emitting means for irradiating a light beam to a recording surface of a disk on which information is recorded, and a light beam irradiated by the light emitting means receives reflected light reflected on a recording surface of the disk. A sensor for outputting a signal for the amount of light, a signal converter for inputting a signal output by the sensor, and outputting a signal indicating an amplitude of the input signal, a sine wave signal generator for outputting a sine wave signal, and a sine wave signal generator A multiplier for inputting an output and an output of the signal converter, outputting a product of such an input, an integrator for inputting the output of the multiplier, outputting an integral value of the input, and a DC component output means for outputting a predetermined DC component; An adder for inputting the output of the DC component output means and the output of the sinusoidal wave signal generator and outputting the sum of the inputs; And aberration correction means which is driven by the output of the adder and corrects the aberration generated by the tilt of the light beam and the disk recording surface.

The present invention provides light emitting means for irradiating a light beam to a recording surface of a disk on which information has been recorded, receiving light reflected by the light beam irradiated by the light emitting means on a recording surface of the disk, and outputting a signal for the amount of light received. A signal converter for inputting a sensor, a signal output by the sensor, and outputting a signal indicating an amplitude of the input signal, a sine wave signal generator for outputting a sine wave signal, an output of the sine wave signal generator and an output of the signal converter A multiplier for inputting a multiplier for outputting a product of such an input, an integrator for inputting an output of the multiplier, outputting an integral value of the input, and an integral value outputted by the integrator, and outputting a predetermined DC component An output means, an output of the DC component output means and an output of the sinusoidal wave signal generator, and output the sum of these inputs And an aberration correcting means driven by an output of the adder and correcting aberrations generated by the tilt of the light beam and the disk recording surface, wherein the DC component output means is input to the DC component output means. The tilt correction apparatus is characterized by changing the value of the DC component output by the DC component output means with respect to the integral value.

According to the present invention, a light beam is irradiated onto a recording surface of a disk on which information is recorded, and the irradiated light beam receives a reflected light reflected on the recording surface of the disk to output a signal for the amount of received light. Outputs a signal representing the amplitude of the signal, outputs a sinusoidal signal, inputs the output sinusoidal signal and the sinusoidal signal, outputs a product of these inputs, inputs the output product, and outputs an integral of this input, and a predetermined direct current Outputting a component, inputting the output DC component and the sinusoidal signal to output the sum of these inputs, and correcting the aberration generated by the tilt of the light beam and the disk recording surface by the output sum. Tilt detection method.

According to the present invention, a light beam is irradiated onto a recording surface of a disk on which information is recorded, the irradiated light beam receives a reflected light reflected on the recording surface of the disk, and outputs a signal for the amount of received light. Outputs a signal indicating the amplitude of the signal, outputs a sinusoidal signal, inputs the output sinusoidal signal and the sinusoidal signal, outputs a product of such an input, inputs the output product, outputs an integral value of the input, and outputs an integrated integral Inputs a predetermined DC component, inputs the output DC component and the sine wave signal, and outputs the sum of these inputs, and corrects the aberration generated by the tilt of the light beam and the disk recording surface by the output sum, Tilt correction method comprising changing the value of the direct current component with respect to the integral value.

In one embodiment of the present invention, the overall configuration of an information reproducing apparatus such as an optical disc player will be described with reference to FIG. A head for reproducing information recorded at a position facing the surface on which the pit 2a is formed, the pit is formed, and the pit 2a is formed on the track 2 on which the information to be reproduced of the optical disc 1 is recorded. (3) is arranged.

The head 3 includes a laser diode 4 for emitting laser light, a collimating lens 4a for making the laser light emitted by the laser diode 4 into parallel light, a beam splitter 5, and parallel light Is focused on the recording surface 2b on which the pit 2a of the optical disc 1 is formed, and the objective lens 6 which makes the reflected light from the recording surface 2b again parallel light and the reflected light which became parallel light are collected. The collimating lens 7a and the sensor 7 which receive the reflected light which this collimating lens 7a collects are integrated.

The laser light generated by the laser diode 4 becomes parallel light in the collimated lens 4a, is reflected by the beam splitter 5, is collected by the objective lens 6, and becomes the light beam 8a. This light beam 8a ), The light spot 8 is projected onto the track 2 of the optical disc 1. The reflected light which is modulated by the pit 2a on the track 2 is returned to the beam splitter 5 via the objective lens 6 again, and passes through the beam splitter 5 to collimate the lens 7a. Is focused on and received by the sensor 7. The sensor 7 outputs an RF signal for received light, that is, light modulated with intensity to the pit 2a.

The objective lens 6 included in the head 3 is moved by the focus actuator 9 in a direction parallel to the optical axis 11 of the light beam 8a, that is, in the Z-axis direction, on the track 2. The focus of the light spot 8 is adjusted.

The head 3 is provided with a tilt element 10 as a kind of aberration correction means, and the tilt element 10 inclines the optical axis 11 of the light beam 8a. The tilt element 10 has an optical axis 11 in a radial direction R (hereinafter referred to as a radial direction) of the optical disc 1 and a tangential direction T (hereinafter referred to as a tangential direction) of the track 2. It is possible to tilt it.

Further, the concrete realization means of the aberration correcting means is not limited to only the means for tilting the optical axis 11 of the light beam 8a as described above, but by the tilt of the light beam 8a and the recording surface 2b of the optical disc 1. Any means for correcting the aberration generated may be sufficient. As a specific example of the aberration correction means, the entire head 3 is tilted, only the objective lens 6 in which the head 3 is built is tilted, the liquid crystal is placed in the optical path of the laser beam, and the liquid crystal is removed to remove the phase difference of the laser beam. To correct the problem.

The focus actuator 9 and the tilt element 10 are controlled by the control means 12.

Next, the internal structure of the control means 12 in this embodiment is demonstrated with reference to FIG. The control means 12 incorporates a signal converter 13, a multiplier 14, an integrator 15, a direct current component output means 16, an adder 17, a sine wave signal generator 18, and a counter 19. .

The signal converter 13 inputs an RF signal output from the sensor 7 and outputs a signal indicating an amplitude of the input RF signal, that is, an RF amplitude. The signal representing the output RF amplitude is input to the multiplier 14. The multiplier 14 is further input with a sinusoidal signal sin (ωt) output from the sinusoidal signal generator 18. The multiplier 14 multiplies such an input, that is, the signal representing the RF amplitude and the sinusoidal signal sin (ωt) and outputs a multiplication result.

The output multiplication result is input to the integrator 15, and the integrator 15 integrates the input multiplication result and outputs the integration result. The output integration result is input to the DC component output means 16, and this DC component output means 16 outputs the DC component α in response to the input.

The output DC component α is input to the adder 17. On the other hand, the sinusoidal signal sin (ωt) output from the sinusoidal wave signal generator 18 is also input to the counter 19, and outputs h · sin (ωt) multiplied by the coefficient h by the input sinusoidal signal sin (ωt). The adder 17 adds two inputs, i.e., h * sin (ωt) and the direct current component α, and outputs α + h · sin (ωt) as the addition result. This output is applied to the tilt element 10.

Next, the operation of the present embodiment will be described. The sinusoidal signal sin (ωt) outputted by the sinusoidal wave signal generator 18 becomes h · sin (ωt) after passing through the counter 19. This h · sin (ωt) and the DC component α outputted by the DC component output means 16 are added by the adder 17, and the addition result α + h · sin (ωt) is applied to the tilt element 10. do. The tilt element 10 changes the tilt angle of the head 3 in response to the applied signal.

3 shows the change in the tilt angle of the head 3, i.e., the amount of correction (horizontal axis in the drawing), and the amplitude of the RF signal output by the sensor 7 at this tilt angle, that is, the RF amplitude in the tilt element 10. Fig. Shows the relationship between the vertical axis in the drawing.

When? + H.sin (? T) output from the adder 17 is applied to the tilt element 10, the tilt angle (correction amount by the tilt element) changes by an amount proportional to the applied value. Here, α and h are set as α >> h · sin (ωt). Therefore, the tilt angle is a value at which a small vibration h · sin (ωt) overlaps the normal value determined by the DC component α.

In Fig. 3, if? =? 1, the amount of correction by the tilt element is? 1 + h · sin (? T), and the RF amplitude at this time is a waveform indicated by the solid line on the right side of the drawing. If α = αtop, the correction amount is αtop + h · sin (ωt), and if α = α2, the correction amount is α2 + h · sin (ωt).

In addition to the relationship between sin (ωt) and RF amplitude, Fig. 4 is a diagram showing the relationship between the multiplication result outputted by the signal and the multiplier 14 and the integration result outputted by the integrator 15. The waveform on the left in Fig. 4 is a relationship in the case of alpha = alpha top, the waveform in the center is a relationship in the case of alpha = alpha 1, and the waveform on the right is a relationship in the case of alpha = alpha 2.

According to the waveform on the left side of Fig. 4, when α = αtop, the sign of the RF amplitude is always-, and the result of multiplication of the RF signal is the sign of sin (ωt) being reversed, but it is also a signal which repeats + and-. do. The integral result of smoothing this signal with the integrator 15 is zero level.

According to the waveform in the center of Fig. 4, when alpha = alpha 1, the sign of the RF amplitude is always equal to sin (ωt). Therefore, the result of the multiplication of sin (ωt) and the RF signal always becomes +. The integral result of smoothing this signal with the integrator 15 has a sign of +.

According to the waveform on the right side of Fig. 4, when? =? 2, the sign of the RF amplitude is always inverse to sin (ωt). Therefore, the result of the multiplication of sin (ωt) and the RF signal always becomes-. The integral result of smoothing this signal with the integrator 15 has a sign of-.

Therefore, it is possible to detect in which direction the correction amount, i.e., the tilt angle, is tilted by the tilt element from the sign of the integration result output from the integrator 15.

In addition, this integration result is input to the DC component output means 16, and this DC component output means 16 outputs the DC component α in response to the input integration result. In other words, the DC component output means 16 does not change the output α when the input is at zero level, increases the output α when the sign of the input is at +, and decreases the output α when the sign of the input is at −.

For example, in Fig. 3, when? =? 1, the sign of the integral result becomes +, so that the output? 1 of the DC component output means 16 increases. As a result, the transition finally takes place in the form of α = αtop. When α = αtop, the integration result is at zero level, and the output αtop of the DC component output means 16 is fixed.

In addition, if? =? 2, the sign of the integral result becomes-, so that the output? 2 of the DC component output means 16 decreases. As a result, finally, the transition also takes place in the form of α = αtop. When α = αtop, the integration result is at zero level, and the output αtop of the DC component output means 16 is fixed.

When the output of the DC component output means 16 becomes αtop, and therefore the output of the addition means 17 for inputting this αtop becomes αtop + h · sin (ωt), the tilt element 10 driven by this output ) Is also proportional to αtop + h · sin (ωt). According to Fig. 3, the RF amplitude becomes maximum at this time, which means that the tilt angle of the optical axis 11 of the head 3 and the recording surface 2b of the optical disc 1 is perpendicular. Therefore, the tilt angle is vertically corrected by the above operation.

According to the present invention, since the means for projecting the light spot and the means for detecting the tilt angle are common, it is possible to completely match the position at which the light spot is projected with the position for detecting the tilt angle. It is possible to get a value.

In addition, it is possible to correct the tilt angle with high accuracy by using the detection value of the high precision tilt angle obtained as described above.

Further, since the means for projecting the light spot and the means for detecting the tilt angle can be made common, it is possible to save cost and increase the configuration of the head portion without increasing the number of parts.

Claims (4)

Light emitting means for irradiating a light beam to the recording surface of the disk on which the information is recorded; A sensor for receiving the reflected light reflected by the light beam irradiated by the light emitting means on the recording surface of the disk, and outputting a signal for the amount of received light; A signal converter configured to input a signal output from the sensor and output a signal representing an amplitude of the input signal; A sine wave signal generator for outputting a sine wave signal, A multiplier for inputting the output of the sinusoidal wave signal generator and the output of the signal converter and outputting a product of these inputs; An integrator that inputs an output of the multiplier and outputs an integral value of the input; DC component output means for outputting a predetermined DC component, An adder for inputting the output of the DC component output means and the output of the sinusoidal wave signal generator, and outputting a sum of these inputs, and And aberration correction means which is driven by the output of the adder and corrects aberration generated by the tilt of the light beam and the disk recording surface. Light emitting means for irradiating a light beam to the recording surface of the disk on which the information is recorded; A sensor for receiving the reflected light reflected by the light beam irradiated by the light emitting means on the recording surface of the disk, and outputting a signal for the received light amount; A signal converter configured to input a signal output from the sensor and output a signal representing an amplitude of the input signal; A sine wave signal generator for outputting a sine wave signal, A multiplier for inputting the output of the sinusoidal wave signal generator and the output of the signal converter and outputting a product of these inputs; An integrator that inputs an output of the multiplier and outputs an integral value of the input; A DC component output means for inputting an integral value output by the integrator and outputting a predetermined DC component; An adder for inputting the output of the DC component output means and the output of the sinusoidal wave signal generator, and outputting a sum of these inputs, and Aberration correction means which is driven by the output of the adder and corrects aberration generated by the tilt of the light beam and the disc recording surface, And the DC component output means changes the value of the DC component output by the DC component output means with respect to the integral value input to the DC component output means. Irradiates a light beam onto the recording surface of the disc on which information is recorded, The irradiated light beam receives the reflected light reflected on the recording surface of the disk and outputs a signal for the received light amount, Input the output signal and output the signal representing the amplitude of the input signal, Output sine wave signal, Inputting the output sinusoidal wave signal and the sinusoidal wave signal and outputting the product of these inputs, Enter the output product to output the integral of this input. Outputs a predetermined DC component, Inputting the output DC component and the sine wave signal to output the sum of these inputs, And correcting the aberration generated by the tilt of the light beam and the disk recording surface by the output sum. Irradiates a light beam onto the recording surface of the disc on which information is recorded, The irradiated light beam receives the reflected light reflected on the recording surface of the disk and outputs a signal for the received light amount, Inputs the output signal to output a signal representing the amplitude of the input signal, Output sine wave signal, Inputting the output sinusoidal wave signal and the sinusoidal wave signal and outputting the product of these inputs, Input the output product to output the integral of the input. Input the output integral value to output a predetermined DC component, Inputting the output DC component and the sine wave signal to output the sum of these inputs, The aberration generated by the tilt of the light beam and the disk recording surface is corrected by the output sum, And changing the value of the direct current component with respect to the integral value.