JP2000251300A - Optical pickup and optical disk unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To selectively use a plurality of light sources with a simple configuration by changing gain when processing a light reception result by a signal- processing circuit for processing and outputting the light reception result of a photo detector so that the output level of an output signal by different wavelength is constant. SOLUTION: When a compact disk is to be reproduced, a laser beam is emitted from a laser diode 8. On the other hand, when a DVD is to be reproduced, the laser beam is emitted from a semiconductor laser diode chip 23. In linking with the change of the laser beam by a laser-driving circuit 37, feedback resistors 34 and 35 of an operational amplification circuit 36 are changed, and the gain of a current/voltage conversion circuit is changed so that the output signal level of the operational amplification circuit 36 in the case of the reproduction of the compact disk becomes nearly equal to that in the case of the reproduction of the DVD, thus showing nearly the same change for the amount of defocus by a focus error signal using a common light reception surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup and an optical disk device, for example, a DVD (Digital Video).
o Disk) and an optical disk device for reproducing a compact disk. According to the present invention, when reproducing a data recorded on an optical recording medium by selectively emitting a laser beam of a plurality of wavelengths, a signal level of a light-receiving element output that changes according to a wavelength is corrected and output from an optical pickup. An optical pickup which can access an optical recording medium by selectively using a plurality of light sources with a simple configuration, and an optical disk apparatus using the optical pickup can be obtained.

[0002]

2. Description of the Related Art Conventionally, in a compact disk player, which is an optical disk apparatus, an optical pickup irradiates a laser beam onto an information recording surface of the compact disk and processes the result of receiving the return light to record the information on the compact disk. It reproduces various types of data.

As such an optical pickup, a type in which a light emitting element and a light receiving element are individually arranged and a type using an optical integrated element in which a light emitting element and a light receiving element are integrated have been proposed. In the latter, the overall shape can be made smaller and the reliability can be improved as compared to the former.

[0004]

When an optical integrated device is used, the overall shape can be reduced in size and simplified, so that an optical pickup using the optical integrated device can be used in an optical disk apparatus for reproducing DVDs. It would be convenient if it could be constructed. Further, it is considered that such a DVD optical disk device is convenient if a compact disk can be reproduced.

In this case, a light emitting element and a light receiving element for a DVD and a light emitting element and a light receiving element for a compact disk are integrated to form an optical integrated element, thereby forming an optical disk apparatus capable of reproducing a compact disk and a DVD. It is considered possible. In this case, these light receiving elements are
By being integrally formed in one semiconductor substrate, D
It is considered that the structure of the optical integrated device can be simplified by also using the light receiving device for the VD and the compact disk.

However, in such a light receiving element,
The sensitivity differs depending on the wavelength. In addition, the reflectivity differs between DVD and compact disc. Further, even in the optical system constituting the optical pickup, the transmittance changes depending on the wavelength. When the light-receiving elements are integrally formed on one semiconductor substrate by these, and when the light-receiving elements for DVD and compact disk are also used, the light-receiving results of these light-receiving elements become D
The difference between the case of reproducing VD and the case of reproducing a compact disc is different. If such a difference in the light receiving result is corrected by an external circuit, there is a problem that the configuration of the optical disk device becomes complicated accordingly.

The present invention has been made in consideration of the above points, and has an optical pickup which can access an optical recording medium by selectively using a plurality of light sources with a simple configuration.
An optical disk device using the optical pickup is to be proposed.

[0008]

According to the first aspect of the present invention, there is provided a signal processing circuit for processing and outputting a light receiving result of a light receiving element, which is applied to an optical pickup. The gain at the time of processing the light reception result is switched so that the signal level of the output signal does not differ.

Further, in the invention according to claim 7, applied to an optical disk device, a signal processing circuit of an optical pickup of the optical disk device processes a light receiving result so that the signal levels of output signals at different wavelengths do not differ. The gain when switching is changed.

According to the first aspect of the present invention, a signal processing circuit applied to an optical pickup for processing and outputting a light receiving result of a light receiving element is provided so that signal levels of output signals at different wavelengths do not differ. By switching the gain when processing the received light result, it is possible to omit the switching of the gain and the like accompanying the switching of the laser beam by the external circuit of the optical pickup, and to reproduce various optical recording media with a simple configuration. be able to.

According to a seventh aspect of the present invention, when applied to an optical disk device, the signal processing circuit of the optical pickup processes a light receiving result so that the signal levels of output signals at different wavelengths do not differ. By switching the gain, it is possible to omit the switching of the gain accompanying the switching of the laser beam by the external circuit of the optical pickup, and it is possible to reproduce various optical recording media with a correspondingly simple configuration.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(1) First Embodiment (1-1) Configuration of First Embodiment FIG. 2 is a sectional view showing an optical system of an optical disk device according to an embodiment of the present invention. This optical disc device 1
The data recorded on the optical disk 2A which is a VD and the data recorded on the compact disk 2B are reproduced.

Here, the compact disc 2B can reproduce recorded data by processing return light obtained by irradiating a laser beam to an information recording surface through a transparent substrate having a thickness of 1.2 [mm]. An optical disk made as described above. In contrast, DVD2A has a thickness of 0.6
This is an optical disc that can reproduce recorded data by processing return light obtained by irradiating a laser beam onto an information recording surface through a [mm] transparent substrate.

In the optical disk device 1, the optical pickup 3 is arranged so as to be movable in a radial direction of the optical disk by a predetermined thread mechanism. When reproducing the DVD 2A, the optical pickup 3 uses a wavelength of 650 [n] from the optical integrated device 4 arranged to face the DVD 2A.
m], and irradiates the DVD 2A with the laser beam via the beam splitter 5, the collimator lens 6, and the objective lens 7. Also this DVD2A
The return light obtained is received by the objective lens 7 and is incident on the optical integrated device 4 via the collimator lens 6 and the beam splitter 5 in order.

The optical disk device 1 processes the result of receiving the return light in the optical integrated device 4 to generate a tracking error signal, a focus error signal, and a reproduction signal necessary for reproducing the DVD 2A.

When reproducing the compact disk 2A, the optical pickup 3 emits a laser beam having a wavelength of 780 [nm] from the laser diode 8, and makes this laser beam incident on the diffraction grating 9. Here, the optical pickup 3 outputs a laser beam by the diffraction of the diffraction grating 9.
After being decomposed into first-order light, zero-order light, and + 1st-order light, the light is reflected by the beam splitter 5. This enables the optical pickup 3
When reproducing the compact disk 2A, the compact disk 2A is irradiated with a laser beam emitted from the laser diode 8 in place of the laser beam emitted from the optical integrated element 4, and the resulting return light is irradiated onto the objective lens. 7, and the returned light enters the optical integrated device 4 via the collimator lens 6 and the beam splitter 5 in order.

As a result, the optical disk apparatus 1 selectively drives the two light sources to emit the laser beam to the optical disk 2A.
Alternatively, the light is radiated to 2B, and the return light obtained as a result is received by the optical integrated element 4 which is a common element.

That is, the optical integrated device 4 is formed by integrally integrating a light receiving element for a compact disk, a light emitting element for a DVD, and a light receiving element into a package. When reproducing the DVD 2A, the optical integrated device 4 emits a laser beam having a wavelength of 650 [nm] from a built-in light emitting device. The optical integrated device 4 is a compact disc 2B or DVD2.
When reproducing A, the result of receiving the return light by the light receiving element is subjected to current-voltage conversion processing and output.

On the other hand, the laser diode 8 emits a laser beam having a wavelength of 780 [nm], and the diffraction grating 9 decomposes the laser beam into -1st-order light, 0th-order light, and + 1st-order light and emits it. I do.

The beam splitter 5 reflects the laser beam emitted from the diffraction grating 9 and
While the laser beam is emitted toward B, the laser beam emitted from the optical integrated device 4 is transmitted therethrough and emitted toward the optical disks 2A and 2B. The beam splitter 5 transmits the return light obtained from the collimator lens 6 and emits it to the optical integrated device 4.

The collimator lens 6 converts the laser beam transmitted through the beam splitter 5 into a substantially parallel light beam and emits it.

The objective lens 7 is an aspherical plastic lens formed by injection molding of a transparent resin, and the DVD which is incident by substantially parallel light beams by selecting the refractive index of the transparent resin and the shape of each lens surface. The laser beams corresponding to the information recording surfaces of the corresponding optical disks 2A and 2B are focused on the laser beam for compact disk and the laser beam for compact disk. Thereby, the objective lens 7
Are designed to constitute a so-called bifocal lens corresponding to a laser beam for DVD and a laser beam for compact disc.

Further, the objective lens 7 is provided with an optical disk 2A, 2
It is configured to be movable in the radial direction of B and in the direction along the optical axis, so that it is possible to perform tracking control and focus control by driving this actuator according to a tracking error signal and a focus error signal.

The matrix operation circuit 11 performs a matrix operation on the light receiving result output from the optical integrated device 4 to obtain a tracking error signal TE whose signal level changes according to the tracking error amount and a signal according to the focus error amount. A focus error signal FE whose level changes and a reproduction signal RF whose signal level changes according to the pit row are generated.

The servo circuit 12 generates a tracking error signal T generated by the matrix operation circuit 11.
E, the drive circuit 13 is driven so that the focus error signal FE becomes a predetermined signal level.
In, the objective lens 7 is driven by driving the actuator by driving the servo circuit 12. Thereby, the optical disc device 1 forms a servo loop to perform tracking control and focus control.

FIG. 3A is a cross-sectional view showing the optical integrated device 4 taken along the circumferential tangent direction of the optical disks 2A and 2B. FIG. 3B is a sectional view of the semiconductor substrate of the optical integrated device 4. 2
1 is a plan view showing the optical disk 1 viewed from the optical disks 2A and 2B. The optical integrated device 4 includes a prism 2 on a semiconductor substrate 21.
2. An optical system 24 is formed by arranging the semiconductor laser diode chip 23, and this optical system 24 is
And wiring, and then sealed with lid glass 26 as a transparent sealing member.

Here, the semiconductor laser diode chip 2
Numeral 3 indicates that a laser beam having a wavelength of 650 [nm] corresponding to the DVD 2A is emitted toward the prism 22, and the optical integrated element 4 is set so that the direction in which the laser beam is emitted is in the circumferential tangential direction of the optical disk 2A. Is done.

The prism 22 is an optical element for separating a laser beam and return light, and is formed in a substantially rectangular shape having a slope on one side. The prism 22 reflects the laser beam emitted from the semiconductor laser diode chip 23 by the inclined surface and emits the laser beam toward the beam splitter 5. The prism 22 reversely follows the optical path of the laser beam and returns the incident light from the inclined surface. Guide inside.

The prism 22 receives the return light incident from the inclined surface on the lower surface, transmits about 50% of the light there, and reflects the remaining amount of the return light toward the upper surface. Further, the prism 14 reflects the return light toward the lower surface by approximately 100% on the upper surface, and emits the return light reflected on the upper surface from the lower surface.

For this reason, the prism 22 has a mirror surface formed on the upper surface by vapor deposition, and return light emitted from a lower slope surface (hereinafter referred to as a front side) and a side away from the slope surface (hereinafter referred to as a rear side). The beam splitter surface and the anti-reflection surface are formed on the lower surface on the front side by the same vapor deposition process so that the light amount ratio of the light source becomes approximately 1: 1.

In the semiconductor substrate 21, the prism 22
The front light receiving surface group 21A and the rear light receiving surface group 2 common to the DVD 2A and the compact disk 2B are respectively applied to portions where the return light from the DVD laser beam and the return light from the compact disk laser beam are incident.
1B is formed.

In FIG. 3C, these light receiving surface groups 21
As shown in a partially enlarged view of A and 21B, the optical integrated element 4 has the beam spot shape formed on the semiconductor substrate 21 by the return light transmitted through the prism 22 in the just-focused state. The semiconductor laser diode chip 23 and the laser diode 8 are formed so that the rear side has a substantially focal line shape, and the front side has an elliptical shape having a major axis in a direction orthogonal to the rear side focal line extending direction. The direction, the size of the prism 22, and the like are selected. FIG. 3C shows a state when the compact disk 2B is reproduced, and three beam spots are formed on the front and rear light receiving surfaces 21A and 21B, respectively. Thus, in the optical disk device 1, tracking control of the compact disk 2B can be performed by the three-spot method.

Each of the front light receiving surface group 21A and the rear light receiving surface group 21B has three light receiving surfaces corresponding to the beam spots formed by these three spots. In reproducing the DVD 2A, the optical integrated device 4 positions the semiconductor laser diode chip 23 so that a beam spot is formed by the semiconductor laser diode chip 23 on the central light receiving surface of the three light receiving surfaces. Is set.

The front-side light-receiving surface group 21A and the rear-side light-receiving surface group 21B are arranged side by side in the circumferential tangent direction of the optical disks 2A and 2B, and three light receiving surfaces are respectively arranged in the circumferential tangential direction of the optical disks 2A and 2B. Each is formed in a substantially rectangular shape side by side. The front-side light-receiving surface group 21A and the rear-side light-receiving surface group 21B have light-receiving surfaces on the slope side and on the side farther than the slope, respectively, so as to output the reception result of return light incident on each light-receiving surface. It is formed.

On the other hand, the central light receiving surface of the rear side light receiving surface group 21B is divided in the radial direction of the compact disc by a dividing line extending in the circumferential tangential direction of the optical discs 2A and 2B.
It is divided into two parts. The light receiving surface group 21B receives the beam spot formed on the central light receiving surface by dividing it into three in the radial direction of the compact disk in the just tracking state. It is designed to output each result.

On the other hand, the central light receiving surface of the front side light receiving surface group 21A is similarly divided into three in the radial direction of the compact disc by a dividing line extending in the circumferential tangential direction of the optical discs 2A and 2B. Further, the light receiving surface is divided into two in the circumferential tangential direction of the optical disk. As a result, the optical disc apparatus 1 can generate a focus error signal by a so-called astigmatism method.
When reproducing DVD2A, a so-called DPD
The tracking error signal can be generated by the (Differencial Phase Detection) method.

The semiconductor substrate 17 performs a current-to-voltage conversion process on the light-receiving results of each of the divided light-receiving surfaces a to m, and then performs an arithmetic process and outputs the processed result. Then, a tracking error signal, a focus error signal, and a reproduction signal are generated.

FIG. 1 is a block diagram showing a current-voltage conversion circuit and a laser drive circuit for these light receiving surfaces a to m.
The optical integrated element 4 includes a feedback voltage 30 having a feedback resistor 30 on the light receiving surfaces h and m farther from the inclined light receiving surfaces g and l and the light receiving surfaces h and m of the front light receiving surface group 21A and the rear light receiving surface group 21B. The current-voltage conversion processing is performed by the arithmetic circuit 31 having the conversion circuit configuration, and the light reception result is output.

On the other hand, with respect to the central light receiving surface of the front light receiving surface group 21A and the rear light receiving surface group 21B, the light receiving by each light receiving surface divided by the current-voltage conversion circuit configured to be able to switch the gain. The results are subjected to current-voltage conversion processing and output. That is, the divided light receiving surfaces a to f and i to k are input to an operational amplifier circuit 36 having a current-voltage conversion circuit configuration configured so that the feedback resistors 34 and 35 can be switched by the switch circuit 33,
Here, current-voltage conversion processing is performed and a light reception result is output.

Here, the light receiving surfaces a to f and i to k correspond to the case where the compact disc 2B is reproduced and the case where the DV
It is used in common with the case of reproducing D2A, and the feedback resistor 3
4 and 35, the compact disc 2
The output signal of the operational amplifier circuit 36 is fed back by the operation of the switch circuit 33 between the case of reproducing B and the case of reproducing the DVD 2A. At this time, the output signal level changes depending on the wavelength of the light receiving surfaces a to f and i to k. The value is selected so that can be corrected.

In this way, the optical integrated device 4 does not perform any processing in the matrix operation circuit 11 when the output signal of the operation amplification circuit 36 thus obtained is operated by the matrix operation circuit 11 to generate a focus error signal. Even when the DVD 2A is played back and the compact disc 2B is played back without switching, the change in the signal level of the focus error signal with respect to the amount of defocus is substantially equal.
The light receiving results of f and i to k are converted into current and voltage and output.

In the optical disk device 1, when reproducing the DVD 2A, the light receiving surfaces a to f of the front side light receiving surface group are set.
While the tracking error signal is generated by the DPD method from the light receiving result of the above, when reproducing the compact disk 2B, the tracking error signal is generated from all the light receiving results of the front light receiving surface group 21A and the rear light receiving surface group 21B. In the feedback resistor 30 of the current-to-voltage conversion circuit that generates and fixes the gain, the light receiving surfaces a to
The resistance value is selected according to the gains corresponding to f, i to k, and so that the change in the signal level of the tracking error signal with respect to the detrack amount becomes substantially equal.

The switch circuit 33 switches the operation of a laser drive circuit 36 for driving the laser diode 8 and the semiconductor laser diode chip 23.
The operation is switched by C1 so that the laser diode 8 and the semiconductor laser diode chip 23 can selectively emit a laser beam.
The gain of the current-voltage conversion circuit is switched. Here, the switching signal SC1 is supplied from a system controller that controls the operation of the entire optical disk device 1 according to the loaded optical disk.

Thus, the matrix operation circuit 11
When reproducing the DVD 2A, the optical pickup 4
The phases of the light receiving results of the light receiving surfaces a and c on the slope side and both sides are compared based on the light receiving results of the light receiving surfaces a to f which are output after being converted into current and voltage, and the light receiving surfaces d and f farther from the slope are received. The results are compared in phase, and the two phase comparison results are added so that the polarities match in the diagonal direction of the light receiving surface.
To generate a tracking error signal.

The matrix operation circuit 11 adds all the current-voltage conversion results relating to the front side, the rear side, and the center light receiving surfaces a to f and i to k, thereby using the sign of the light receiving surface to obtain (a + b + c + d + e + f + i + j + k). Generates a reproduction signal RF represented by Also, the current-voltage conversion results of the front-side light receiving surfaces a, c, d, and f of the light receiving surfaces a to f at the center and the light receiving surface j at the center of the light receiving surfaces i to k at the rear side are added. Front-side, center light-receiving surfaces b, e of center-side light-receiving surfaces a-f and rear-side, center light-receiving surface i,
The current-voltage conversion results of the light receiving surfaces i and k at both ends of k are added, and the two addition results are subtracted to generate a focus error signal FE. Thus, similarly, using the sign of the light receiving surface, (a + c + d + f + j)-(b + e + i + k)
Generates a focus error signal FE represented by.

When reproducing the compact disk 2B, a focus error signal FE is generated in the same manner as when reproducing the DVD 2A.
A and the light receiving surfaces a to m of the rear side light receiving surface group 21B,
The current-voltage conversion results are selectively added, and (a + b + c + d + e + f ++ i + j +
Generate a reproduction signal RF represented by k).

On the other hand, the current-voltage conversion results of the slope-side light-receiving surface g of the front-side light-receiving surface group 21A and the light-receiving surface m of the rear-side light-receiving surface group 21B farther from the slope are added. The tracking error signal TE is generated by adding the current-voltage conversion results of the light receiving surface h farther from the slope of 21A and the slope light receiving surface 1 of the rear light receiving surface group 21B and subtracting these two light receiving results. , A tracking error signal TE represented by (g + m)-(h + 1) using the sign of the light receiving surface.

(1-2) Operation of First Embodiment In the above configuration, the optical disc apparatus 1 (FIG. 2) uses the optical pickup 3 to irradiate the optical discs 2A and 2B with a laser beam and emit the return light. The information recorded on the optical disks 2A and 2B is reproduced by receiving the light and processing the result of receiving the return light by a predetermined signal processing circuit.

That is, in the optical disk device 1, when reproducing the compact disk 2B, the optical pickup 3 emits a laser beam from the laser diode 8, and this laser beam is
After being decomposed into diffracted light of the next, 0th, and + 1st order, the optical path is bent by the beam splitter 5 and irradiated on the compact disc 2B by the collimator lens 6 and the objective lens 7. The return light is incident on the beam splitter 5 via the objective lens 7 and the collimator lens 6 in order, passes through the beam splitter 5, and is received by the optical integrated element 4.

On the other hand, when reproducing the DVD 2A, a laser beam is emitted from the optical integrated device 4, and this laser beam passes through the beam splitter 5 and has a collimator lens 6, which is common to the compact disk 2B.
The DVD 2A is irradiated by the objective lens 7. Correspondingly, in the optical integrated device 4, when reproducing the DVD 2A (FIG. 3), a laser beam is emitted from the semiconductor laser diode chip 23, and this laser beam is emitted toward the beam splitter 5. The return light is incident on the beam splitter 5 via the objective lens 7 and the collimator lens 6 in order, passes through the beam splitter 5, and is received by the optical integrated device 4.

In the optical disk device 1, a tracking error signal TE is generated from the result of receiving the return light, and the objective lens 7 is controlled by the servo circuit 12 so that the tracking error signal TE has a predetermined signal level. It is moved in the radial direction and tracking control is performed. Similarly, a focus error signal FE is generated, and the objective lens 7 is moved along the optical axis so that the focus error signal FE has a predetermined signal level, thereby performing focus control.

By processing the result of receiving the return light, the data recorded on the DVD 2A or the compact disk 2B is reproduced, whereby the optical disk device 1 can selectively use the light sources having different wavelengths arranged on the optical pickup 3. To access the DVD 2A and the compact disc 2B.

When the return light is received by the optical integrated device 4 in this manner, in the optical disk device 1, the prism 22 that reflects the laser beam emitted from the semiconductor laser diode chip 23 toward the collimator lens 6 is used.
The return light is guided to the inside of the prism 22 through the inclined surface, and is reflected by the lower surface of the prism 22 to be about 50%.
After the remaining 50 [%] of light is reflected by the upper surface, the light is emitted from the front side and the rear side of the lower surface.

Further, the return light emitted from the front side and the rear side in this manner is applied to the front light receiving surface group 21A and the rear light receiving surface group 21B formed on the semiconductor substrate 21.
, Respectively. Here, when reproducing the compact disk 2B, the diffraction grating 9 causes the −1 order, 0 order,
Three beam spots are formed on each of the front-side light receiving surface group 21A and the rear-side light receiving surface group 21B corresponding to the laser beam that is decomposed into + 1st-order diffracted light and radiated onto the compact disc 2B. The two beam spots are received by the light receiving surfaces formed on the front light receiving surface group 21A and the rear light receiving surface group 21B, respectively.

In the optical disk device 1, when reproducing the compact disk 2B, the current-voltage conversion of the light receiving surfaces a to m, which is the detection result of the total amount of return light incident on these light receiving surface groups 21A and 21B, is thereby performed. The results are added to generate a reproduction signal RF, and the light receiving surface groups 21A and 21A
B, the light receiving surfaces g, h, m,
The tracking error signal TE is obtained from the current-voltage conversion result
Are the light receiving surfaces a to 21 at the center of the light receiving surface groups 21A and 21B.
A focus error signal FE is generated from the current-voltage conversion results of f and i to k.

On the other hand, when the DVD 2A is reproduced, return light is returned to the central light receiving surface among the three light receiving surfaces formed in the front light receiving surface group 21A and the rear light receiving surface group 21B. Upon incidence, a beam spot is formed.

Thus, the central light receiving surfaces a to f, i to
A tracking error signal TE is generated by the DPD method from the front side light receiving surfaces a to f of k, and a focus error signal FE is generated in the same manner as in the case of the compact disk 2B. Further, a reproduction signal RF is generated based on the addition result on the front side and the rear side.

In these processes, the optical disk device 1
In the current / voltage conversion circuit built in the optical pickup 3 (FIG. 1), the reproduction of the compact disc 2B and the DVD
Regarding the light receiving surfaces a to f and i to k commonly used in the reproduction of 2A, the feedback resistance 3 of the operational amplifier circuit 36 is linked to the switching of the laser beam by the laser drive circuit 37.
4 and 35 are switched, whereby the gain of the current-voltage conversion circuit is switched so that the output signal level of the operational amplifier circuit 36 becomes substantially equal between the case of reproducing the compact disk 2B and the case of reproducing the DVD 2A.

Thus, the focus error signal FE using the light receiving surface common to the reproduction of the compact disk 2B and the reproduction of the DVD 2A can be obtained without correcting any signal level by the matrix operation circuit 11 and the servo circuit 12. The focus error signal FE is generated so as to exhibit almost the same change with respect to the defocus amount. Therefore, in the optical disc apparatus 1, the switching of the gain in the external circuit of the optical pickup 3 and the like can be omitted for the focus error signal FE, and the compact discs 2B and 2D have a simple structure as a whole.
VD2A can be reproduced.

On the other hand, the tracking error signal TE
In the current-voltage conversion circuit having the light receiving surfaces g, h, m, and l dedicated to the reproduction of the compact disk 2B, the gain at the time of reproducing the compact disk 2B in the current-voltage conversion circuit that switches the gain in this way is The current-voltage conversion processing is performed by the corresponding gain, whereby the tracking error signal TE is also processed by the matrix operation circuit 1.
1. Even if the signal level is not substantially corrected by the servo circuit 12, the signal is generated so as to exhibit almost the same change with respect to the detrack amount. Therefore, in the optical disk device 1,
As for the tracking error signal TE, switching of the gain and the like in the external circuit of the optical pickup 3 can be omitted as necessary, and the compact disk 2B and DVD 2A can be reproduced with a simple configuration as a whole.

(1-3) Effects of the First Embodiment According to the above configuration, by switching the gain of the current-voltage conversion circuit built in the optical pickup, the compact disk and the DVD can be respectively irradiated with laser beams of different wavelengths. In the case of reproducing an optical recording medium, it is possible to simplify switching of a gain in an external circuit for processing an output signal of the optical pickup, and to selectively use a plurality of light sources with a simple configuration as a whole. And an optical disc device using the optical pickup.

(2) Second Embodiment In an optical disk device according to this embodiment, FIG.
The gain of the current-voltage conversion circuit is switched by the switching mechanism shown in FIG. 4 instead of the switching mechanism described above. In the optical disk device according to this embodiment, the configuration shown in FIG. 4 is applied to the processing of the light receiving surfaces a to f and i to k shared by the reproduction of the compact disk 2B and the reproduction of the DVD 2A. Except for the above, the configuration is the same as that of the optical disk device according to the above-described first embodiment, and the same configuration is denoted by the corresponding reference numeral, and redundant description will be omitted.

Here, in the optical disk device 1,
The current detection conversion resistor 41 is connected in series with the semiconductor laser diode chip 23, and the drive of the semiconductor laser diode chip 23 is detected based on the potential difference between both ends of the current detection conversion resistor 41. That is, in the optical disk device 1,
In a circuit built in the optical pickup, the potential at both ends of the current detection conversion resistor 41 is input to the operational amplifier circuit 44 via the input resistors 42 and 43. Here, the operational amplifier circuit 44
A differential amplifier circuit having a ground resistor 45, a feedback resistor 46, and input resistors 42 and 43 amplifies a potential difference between both ends of the current detection conversion resistor 41 with a predetermined gain and outputs the result.

The comparison circuit 47 obtains a result of comparison between the output voltage of the operational amplifier circuit 44 and a predetermined reference voltage V1, and switches the operation of the switch circuit 33 based on the result of comparison.
Thus, in this embodiment, the gain of the current-voltage conversion circuit is switched according to the selective driving of the laser beam.

According to the configuration shown in FIG. 4, even if the gain of the current-voltage conversion circuit is switched with reference to the drive current of the laser diode, the same effect as in the first embodiment can be obtained. Further, the number of terminals of the optical integrated device can be reduced.

(3) Third Embodiment In the optical disk device according to this embodiment, FIG.
The gain of the current-voltage conversion circuit is switched by the switching mechanism shown in FIG. 5 instead of the switching mechanism described above. In the optical disk device according to the present embodiment, the configuration shown in FIG. 5 is applied to the processing of the light receiving surfaces a to f and i to k shared by the reproduction of the compact disk 2B and the reproduction of the DVD 2A. Except for the above, the configuration is the same as that of the optical disk device according to the above-described first embodiment, and the same configuration is denoted by the corresponding reference numeral, and redundant description will be omitted.

In the optical disk device 1, the semiconductor laser diode 2 is monitored by the output signal of the photodiode 51 for monitoring the semiconductor laser diode 23.
3 is detected, and the operation of the switch circuit 33 is switched. That is, in this optical disk device, the result of light reception of the photodiode 51 is subjected to current-voltage conversion processing by an operational amplifier circuit 53 having a current-voltage conversion circuit configuration having a feedback resistor 52, and the output signal is input to a comparison circuit 47.

According to the configuration shown in FIG. 5, even if the light emission of the laser diode is directly detected and the gain of the current-voltage conversion circuit is switched, the same effect as in the second embodiment can be obtained.

(4) Fourth Embodiment In an optical disk device according to this embodiment, FIG.
The gain of the current / voltage conversion result is switched by the switching mechanism shown in FIG. 6 instead of the switching mechanism described above. In the optical disk device according to the present embodiment, the configuration shown in FIG. 6 is applied to the processing of the light receiving surfaces a to f and i to k shared by the reproduction of the compact disk 2B and the reproduction of the DVD 2A. In addition, the configuration is the same as that of the optical disk device according to the above-described first embodiment except that the signal polarity is switched and processed by a partial circuit corresponding to the configuration shown in FIG. The same components are denoted by the corresponding reference numerals, and duplicate description will be omitted.

That is, in this optical disk device,
In an operational amplifier circuit 61 having a current-voltage conversion circuit configuration having a feedback resistor 61, a light-receiving result is subjected to current-voltage conversion processing with a fixed gain. The subsequent operational amplifier circuit 65 is constituted by an inverting amplifier circuit having an input resistor 63 and a ground resistor 64, and its feedback resistors 66 and 67 are selected by the switch circuit 33. As a result, in this optical disk device, the gain of the separately arranged amplifier circuit is switched to switch the gain by the current-voltage conversion processing.

According to the configuration shown in FIG. 6, the same effect as in the first embodiment can be obtained even if the gain of the current-to-voltage conversion process is switched by switching the gain of an amplifier circuit separately disposed. .

(5) Fifth Embodiment In an optical disk device according to this embodiment, FIG.
As shown in (1), the function of the matrix operation circuit is built in the optical pickup. The optical disk device according to the present embodiment is the same as the optical disk device according to the above-described first embodiment except that the configuration shown in FIG. Since the configuration is the same as that of the optical disk device, the same configuration is denoted by the corresponding reference numeral, and redundant description will be omitted.

That is, the optical disc device has operational amplifier circuits 70a, 70b,..., Each having a current-voltage conversion circuit configuration having feedback resistors 71a, 71b,.
The light-receiving results of the respective light-receiving surfaces a to m are subjected to current-voltage conversion processing by 70 m, and the current-voltage conversion results are input to the arithmetic circuits 72 and 73. The arithmetic circuit 72 arithmetically processes the light-receiving result obtained by the current-voltage conversion processing, and generates a tracking error signal, a focus error signal, and a reproduction signal for DVD. The arithmetic circuit 73 performs arithmetic processing on the light receiving result subjected to the current-voltage conversion processing, and generates a tracking error signal, a focus error signal, and a reproduction signal for a compact disk.

The arithmetic circuits 72 and 73 are provided for the tracking error signal,
These light reception results are processed with a predetermined gain so that the change in the signal level of the focus error signal substantially matches the error amount. The light receiving result is also processed so that the reproduced signal is output at a substantially constant signal level. These processes are executed by the same arithmetic processing as that of the matrix arithmetic circuit described in the first embodiment.

The selection circuit 74 selectively outputs the tracking error signal TE, the focus error signal FE, and the reproduction signal RF output from the arithmetic circuits 72 and 73 according to the switching signal SC1.

According to the configuration shown in FIG. 7, an arithmetic processing circuit is incorporated in an optical pickup to generate a focus error signal, a tracking error signal, and a reproduction signal. At this time, these signal levels are increased by setting the gain. Even if they are not different, the same effect as in the first embodiment can be obtained, and the configuration of the external circuit can be simplified because the function of the matrix operation circuit is incorporated in the optical pickup.

(6) Sixth Embodiment In an optical disk device according to this embodiment, FIG.
The optical pickup is configured using the optical integrated device 84 shown in FIG. 8 instead of the optical integrated device 4 described above. The optical disk device according to this embodiment has the same configuration as that of the optical disk device according to the above-described first embodiment except that the configuration of the optical integrated device is different. Are denoted by corresponding reference numerals, and redundant description will be omitted.

In this embodiment, the optical integrated device 84
In the figure, a light receiving surface group for a compact disc and a light receiving surface group for a DVD are formed on a semiconductor substrate 81, and a semiconductor laser diode chip 85 for emitting a laser beam for a DVD is correspondingly provided. Optical disks 2A, 2A,
B are arranged to be offset by a predetermined distance in the radial direction.

The semiconductor substrate 81 has a light receiving surface group 8 on the front side and the rear side on which the return light for DVD is incident.
1AA and 81AB are formed, and light receiving surface groups 81BA and 81BB are formed on the front side and the rear side on which return light for a compact disc is incident.

Here, the light receiving surface group 8 on the compact disk side
1BA and 81BB are optical disc 2A on the front side,
The light receiving surface group 2 of the optical integrated device 4 described in the first embodiment except that the light receiving surface group 2 is not divided in the radial direction of FIG.
1A and 21B. On the other hand, DVD
The light receiving surface groups 81AA and 81AB on the side are each divided in the radial direction of the optical disks 2A and 2B by a dividing line having a rectangular light receiving surface extending in the circumferential tangential direction of the optical disks 2A and 2B, thereby achieving a just tracking state. ,
The beam spot is divided into four in the radial direction of the optical discs 2A and 2B by the divided light receiving surfaces to receive light. Further, on the front side, each of the light receiving surfaces divided in the radial direction of the optical disks 2A and 2B is divided in the circumferential tangential direction of the optical disks 2A and 2B.

Thus, in the optical disk device, a tracking error signal can be generated by a method suitable for a compact disk and a DVD, respectively.

FIG. 9 is a block diagram showing a current-voltage conversion circuit and a laser drive circuit 37 built in the optical pickup according to this optical disk device. In this optical disk device, among the light receiving surfaces used for generating the focus error signal, the rear side for the compact disk, the light receiving surfaces F and H at both ends, the corresponding rear side for the DVD, and the light receiving surfaces i and l at both ends are common. The light-receiving result is subjected to current-voltage conversion processing by the current-voltage conversion circuit. That is, in the optical pickup, the corresponding light receiving surfaces F and i, H and l are connected in parallel, and the feedback resistance 86 or 8 is connected by the switch circuit 33.
7 is input to an operational amplifier circuit 89 having a current-voltage conversion circuit configuration connected so as to be selectable. Thereby, the optical pickup switches the gain of the current-voltage conversion circuit so as to correspond to the selective irradiation of the laser beam.

In the optical pickup, the remaining light receiving surface is subjected to current-voltage conversion processing by an operational amplifier circuit 84 with a fixed gain by a feedback resistor 83, and then output. The optical disk device according to this embodiment processes a light reception result for a compact disk in the same manner as in the first embodiment by a matrix operation circuit to generate a tracking error signal, a focus error signal, and a reproduction signal.

On the other hand, with respect to the DVD, front, rear, and center light receiving surfaces b, c, f, g, j, and k, the corresponding light receiving results are added to generate a focus error signal. . Also, the light receiving surfaces a and b on the inner peripheral side on the front side and the slope side, the light receiving surfaces c and d on the outer peripheral side, the light receiving surfaces e and f on the inner peripheral side farther from the front side and the slope, and the light receiving surface g on the outer peripheral side. , H, and the phases of the addition result are compared on the slope side and on the slope side and the far side.
Further, the result of the phase comparison is added so that the polarities match in the diagonal direction, thereby generating a tracking error signal by the DPD method. Also, the light receiving results are added for all the light receiving surfaces, thereby generating a reproduced signal.

According to the configuration shown in FIG. 8, the same effects as in the first embodiment can be obtained even when a dedicated light receiving surface is formed for each laser beam.

(7) Seventh Embodiment In an optical disk device according to this embodiment, FIG.
The configuration shown in FIG. 10 is applied instead of the configuration of the current-voltage conversion circuit described above. That is, the optical pickup has feedback resistors 91a to 91l and 91A to 9A, respectively.
Operational amplifier circuit 92 having current-voltage conversion circuit configuration having 1J
a to 92l, 92A to 92J, light receiving surfaces a to l, A
To J are subjected to current-to-voltage conversion processing, and the light reception results are subjected to current-to-voltage conversion processing with a fixed gain.

In the optical pickup, the gain of each of the current-voltage conversion circuits is set so that the gain does not need to be switched in the matrix operation circuit and the servo circuit in the subsequent stage. The optical pickup switches and outputs the current / voltage conversion result with respect to the light receiving result of the corresponding light receiving surface via the switch circuit 33 that switches the operation by the switching signal SC1.

According to the configuration shown in FIG. 10, even if current-voltage conversion circuits having different gains are arranged on each light receiving surface,
The same effect as in the first embodiment can be obtained.

(8) Eighth Embodiment In an optical disk device according to this embodiment, FIG.
The function of the matrix operation circuit is built in the optical pickup having the optical integrated device 84 described above. FIG.
FIG. 12 is a block diagram showing the configuration of the optical pickup, and FIG. 12 shows this from the input / output terminals of the optical pickup.

In this embodiment, the light receiving results of the respective light receiving surfaces are respectively subjected to current-voltage conversion processing, and then input to arithmetic circuits 101 and 102 for DVD and compact disk, respectively, where the tracking error signal TE and the focus error A signal FE and a reproduction signal RF are generated. At this time, the arithmetic circuits 101 and 102 change the signal level of each of the error signals TE and FE with respect to the error amount substantially in the DVD
These light reception results are processed so as to match those for the compact disk. Similarly, the reproduction signal is also processed so that the signal levels substantially coincide with each other.

The optical pickup switches and outputs these two systems of the tracking error signal TE, the focus error signal FE, and the reproduction signal RF in accordance with the switching signal SC1.

According to the configuration shown in FIG. 11, the same effect as in the first embodiment can be obtained even if the arithmetic circuit is built in the optical pickup and the gain is corrected by this arithmetic circuit.

(9) Other Embodiments In the above embodiment, the case where a compact disc and a DVD are reproduced has been described. However, the present invention is not limited to this. It can be widely applied to access.

In the above-described embodiment, the case of accessing two types of optical disks has been described. However, the present invention is not limited to this, and can be widely applied to the case of accessing a plurality of types of optical disks.

Further, in the above-described embodiment, the case where the optical pickup is constituted by the optical integrated device in which the light emitting element and the light receiving element are integrated has been described. However, the present invention is not limited to this, and the light emitting element and the light receiving element are not limited thereto. The present invention can also be widely applied to a case where the and are arranged separately.

[0097]

As described above, according to the present invention, when a laser beam having a plurality of wavelengths is selectively emitted to reproduce data recorded on an optical recording medium, the signal level of the light-receiving element output that varies with wavelength is reproduced. And an optical pickup that can access an optical recording medium by selectively using a plurality of light sources with a simple configuration, and an optical disc device using the optical pickup. It can be so.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining processing of a light reception result for an optical pickup applied to an optical disk device according to a first embodiment of the present invention;

FIG. 2 is a sectional view showing the optical disc device according to the first embodiment.

FIG. 3 is a cross-sectional view and a plan view showing the optical integrated device of FIG. 2;

FIG. 4 is a block diagram for explaining processing of a light reception result for an optical pickup applied to an optical disk device according to a second embodiment of the present invention;

FIG. 5 is a block diagram for explaining a process of a light receiving result of an optical pickup applied to an optical disc device according to a third embodiment of the present invention.

FIG. 6 is a block diagram for explaining processing of a light reception result of an optical pickup applied to an optical disc device according to a fourth embodiment of the present invention.

FIG. 7 is a block diagram for explaining processing of a light reception result for an optical pickup applied to an optical disk device according to a fifth embodiment of the present invention.

FIG. 8 is a sectional view and a plan view showing an optical integrated device of an optical pickup applied to an optical disk device according to a sixth embodiment of the present invention.

FIG. 9 is a block diagram for explaining processing of a light reception result of an optical pickup applied to an optical disc device according to a sixth embodiment of the present invention.

FIG. 10 is a block diagram for explaining processing of a light reception result for an optical pickup applied to an optical disc device according to a seventh embodiment of the present invention;

FIG. 11 is a block diagram for explaining a process of a light receiving result of an optical pickup applied to an optical disc device according to an eighth embodiment of the present invention.

FIG. 12 is a block diagram showing input and output of the optical pickup of FIG. 11;

[Explanation of symbols]

1 ... optical disk device, 2A, 2B ... optical disk, 3
…… Optical pickup, 4 ………… Optical integrated device

Claims (12)

[Claims] An optical pickup for irradiating an optical recording medium with a laser beam and receiving a return light obtained from the optical recording medium and outputting a light receiving result. A second light source; a light receiving element for receiving return light obtained from the optical recording medium; a signal processing circuit for processing and outputting a light receiving result of the light receiving element; emitted from the first and second light sources An optical system for condensing the laser beam on the optical recording medium and guiding return light obtained from the optical recording medium to the light receiving element, wherein the signal processing circuit outputs a signal of an output signal by the different wavelength. An optical pickup characterized in that a gain at the time of processing the light reception result is switched so that the levels do not differ. 2. The signal processing circuit according to claim 1, wherein the gain at the time of processing the light reception result is switched by switching a gain of a current-voltage conversion circuit that performs current-voltage conversion processing of the light reception result. Optical pickup as described. 3. The optical pickup according to claim 1, wherein said first and second light sources and said light receiving element are integrally housed in one package. 4. The optical pickup according to claim 1, wherein the gain is switched in conjunction with the selective driving of the first and second light sources. 5. The light-receiving element receives the return light with a plurality of light-receiving surfaces, and shares all or a part of the plurality of light-receiving surfaces for receiving the return light with the laser beams having different wavelengths. The optical pickup according to claim 1, wherein 6. The signal processing circuit processes the light reception result, and a tracking error signal whose signal level changes according to a tracking error amount, a focus error signal whose signal level changes according to a focus error amount, or 2. The optical pickup according to claim 1, wherein a reproduction signal whose signal level changes according to a pit row or a mark row formed on the optical recording medium is generated. 7. An optical recording medium is irradiated with a laser beam from an optical pickup, and return light obtained from the optical recording medium is received by the optical pickup to process the light reception result, thereby recording the optical recording medium. An optical disc device that reproduces the read data, wherein the optical pickup comprises: first and second light sources that emit the laser beams having different wavelengths; a light receiving element that receives return light obtained from the optical recording medium; A signal processing circuit that processes and outputs a result of light reception of the light receiving element; and a laser beam emitted from the first and second light sources is focused on the optical recording medium and is obtained from the optical recording medium. An optical system for guiding return light to the light receiving element, wherein the signal processing circuit does not differ in signal level of an output signal depending on the different wavelength. An optical disc apparatus characterized in that the gain at the time of processing the light reception result is switched. 8. The signal processing circuit according to claim 7, wherein the gain at the time of processing the light reception result is switched by switching the gain of a current-voltage conversion circuit that performs current-voltage conversion processing of the light reception result. An optical disk device as described in the above. 9. The optical disk device according to claim 7, wherein said first and second light sources and said light receiving element are housed integrally in one package. 10. The optical disk device according to claim 7, wherein said gain is switched in conjunction with selective driving of said first and second light sources. 11. The light-receiving element receives the return light by a plurality of light-receiving surfaces, and shares all or a part of the plurality of light-receiving surfaces for receiving the return light by the laser beams having the different wavelengths. The optical disk device according to claim 7, wherein 12. The signal processing circuit processes the light reception result, and a tracking error signal whose signal level changes according to a tracking error amount, a focus error signal whose signal level changes according to a focus error amount, or 8. The optical disk apparatus according to claim 7, wherein a reproduction signal whose signal level changes according to a pit row or a mark row formed on the optical recording medium is generated and output.