JP2001209960A - Photodetector and optical information recording and reproducing device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize a photodetector without the deterioration of its performance and to make its function higher with a size as in the past. SOLUTION: The number of the output signals of the photodetector is decreased by computing the detection output of a prescribed region by using a subtracter, by which the downsizing is realized. Or the higher function is realized with the size kept unchanged by allocating the decreased output terminals to the higher function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus (hereinafter referred to as "optical information recording / reproducing apparatus") for reproducing a data signal recorded on an optical information recording medium (hereinafter referred to as "optical disk") or recording information on the optical disk. In particular, the present invention relates to a configuration of a photodetector that detects reflected light from an optical disc.

[0002]

2. Description of the Related Art Conventionally, an optical disk apparatus detects reflected light from an optical disk, generates a defocus signal and a tracking error signal for controlling the position of a light spot from the detection result, and performs feedback control using the signals. By stabilizing the position of the light spot, the data signal on the optical disk is reproduced stably or the data signal is recorded on the optical disk stably. However, the types of optical disks used in optical disk devices in recent years are CD-ROM, CD-R, CD-RW, and DVD-R.
OM and DVD-RAM are increasing. Since the optical disc apparatus performs a recording or reproducing operation on the plurality of discs, a photodetector capable of generating the defocus signal and the tracking error signal signal corresponding to the types of the plurality of optical discs is required. Here, a knife-edge method (foucault method), a beam size method, an astigmatism method and the like are used in the method of generating the defocus signal, and a three-spot method (CD) and a differential push-pull method are used in the method of generating the tracking error signal. Method (CD, CD-R, C
D-RW, DVD-RAM), phase difference detection method (differential phase detection method: DVD)
-ROM) are already known.

[0003]

The results of a study on the above conventional example will be described below with reference to FIG.

FIG. 8 shows an example of the configuration of a photodetector according to the above-mentioned conventional example, in which 100 is the entire photodetector, 101, 102, and 103 are light receiving areas 104, 10 and 10.
5, 106, 107, 108, 109, 110, 111
Is a current-voltage conversion amplifier.

As shown in FIG. 8, each of the light receiving areas 101, 102, and 103 is divided into four crosses each having a cross shape, and thus has a total of 12 light receiving surfaces. Light receiving area 1
The light beams 01, 102, and 103 are arranged substantially linearly, and the three light beams reflected from the optical disk are focused on the light receiving regions 101, 102, and 103. In FIG. 8, the light received on the light receiving surfaces a, b, c, and d is detected by photoelectric conversion as a current corresponding to the amount of light, and each detected current is supplied to the current-voltage conversion amplifiers 106, 107, 108, and 109. After being converted to a voltage, it is output to an output terminal. The output line of the light receiving surface e is connected to the output line of the light receiving surface i, and then connected to the current-voltage conversion amplifier 104. For this reason, the detection current detected on the light receiving surface e and the detection current detected on the light receiving surface i are added, then converted into a voltage by the current-voltage conversion amplifier 104, and output to the output terminal. Similarly, the light receiving surface f
And j, the detection current detected at each of the light receiving surfaces g and k, and the detection current detected at each of the light receiving surfaces h and l are added, and the current-voltage conversion amplifier 111, The signals are converted into voltages at 110 and 105 and output to the output terminals. (For the sake of simplicity, these voltage-converted detection signals are given the same symbols as the light-receiving surfaces on which the detection signals are detected.) Do).
Therefore, a, b, c, d, e +
Eight signals of i, f + j, g + k, and h + 1 are output. In this configuration, for example, the defocus signal is ｛(a +
c)-(b + d) {+ K1} (e + i + g + k)-(h
+ L + f + j)}, and the tracking error signal is {(a + b) −
(C + d) {+ K2} (e + i + f + j)-(h + 1 +
g + k)｝, and a, b,
It can be obtained from the phase difference between the signals c and d. The information reproduction signal is a sum signal of the zero-order light (a + b + c + d).
Can be obtained from

As described above, even in the conventional configuration, a defocus signal and a tracking error signal for various disks are detected,
It is possible to reproduce information. However, the above conventional configuration has the following problems.

[0007] Even if an attempt is made to further reduce the size, the above-described conventional configuration requires eight output terminals for signal output.
In addition, if the supply of power, ground, and midpoint potential used in the photodetector is combined, at least 11 terminals are required, and for example, a 12-pin package is required at the minimum, and further miniaturization cannot be realized. Next, when an attempt is made to increase the speed of the optical disk device, the band of the detection signal is widened, which causes a jump noise such as a clock to increase and a decrease in data reliability. Therefore, the differential output of the sum signal (a + b + c + d), that is, (a + b +
c + d) and-(a + b + c + d) output signals are desired. However, if the differential output can be output in the above-described conventional configuration, the number of output terminals is further increased by 2 pins, so that a 14-pin package is required as a photodetector, and compatibility with miniaturization cannot be realized.

In addition, for example, differences in reflectance between various disks, or for example, CD-R, CD-RW, DVD
-If the amplification degree of the current-to-voltage conversion amplifier is to be optimized so as to correspond to the difference in reflected light intensity between recording and reproduction in a recordable disk such as a RAM, the current-voltage conversion amplifier is further required. Therefore, a terminal for controlling the degree of amplification is required, so that the size of the package needs to be further increased, so that it is impossible to achieve compatibility with miniaturization.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a configuration of a photodetector which realizes miniaturization of the photodetector or realizes high functionality without changing the package size.

[0010]

The present invention has the following features to solve the above-mentioned problems.

A first feature of the present invention is a photodetector that receives a light beam emitted from a semiconductor laser light source and reflected from an optical disk, and detects a signal based on the received light amount, and enters the photodetector. At least twelve independent light receiving surfaces are arranged at positions irradiated with the three light beams, and predetermined signal lines among signal lines transmitting photoelectric conversion signals obtained from the respective light receiving surfaces are connected. After that, the current-to-voltage conversion is performed, and a subtraction process is performed between the connected and current-to-voltage-converted predetermined signals to output the signals.

According to a second feature of the present invention, in addition to the first feature, a detection signal corresponding to the total light amount detected in one predetermined light receiving area and an inverted signal thereof, that is, a differential output are generated. One or more circuits are provided.

A third feature of the present invention is that, in addition to the first feature configuration, the amplification degree of the current-voltage conversion is changed according to a predetermined control input.

A fourth feature of the present invention is that the optical disc apparatus uses the photodetector having the above-mentioned first, second or third feature constitution, a plurality of semiconductor lasers, and a discriminating circuit for judging the type of the optical disc. An error generating circuit that generates a defocus signal and a tracking error signal of the optical spot on the optical disk by using a predetermined operation from the output of the photodetector, and determines the type of the disk determined by the determining circuit. Accordingly, one of the plurality of semiconductor lasers is selectively switched, and the calculation method in the error generation circuit is switched according to the type of the disk determined by the determination circuit.

According to a fifth feature of the present invention, an optical disc apparatus uses the photodetector of the third feature configuration, a plurality of semiconductor lasers, a discriminating circuit for judging the type of the optical disc, An error generation circuit for generating a defocus signal and a tracking error signal of a light spot on an optical disk using a predetermined operation from an output, and a control signal for generating a control signal for controlling the amplification of current-voltage conversion of the photodetector A generating circuit configured to selectively switch one of the plurality of semiconductor lasers according to the type of the disk determined by the determining circuit, and to select a type of the disk determined by the determining circuit. While switching the calculation method in the error generation circuit,
The control signal generation circuit generates a control signal for controlling the amplification degree of the current-voltage conversion of the photodetector according to the type of the disk determined by the determination circuit.

According to a sixth feature of the present invention, an optical disc apparatus uses the photodetector having the third feature configuration, a plurality of semiconductor lasers, a discriminating circuit for judging the type of the optical disc, An error generation circuit for generating a defocus signal and a tracking error signal of a light spot on an optical disk using a predetermined operation from an output, and a control signal for generating a control signal for controlling the amplification of current-voltage conversion of the photodetector A generation circuit and a controller configured to control the operation of the optical information recording / reproducing apparatus, and selectively switching one of the plurality of semiconductor lasers according to the type of the disk determined by the determination circuit; Further, the calculation method in the error generation circuit is switched according to the type of the disk determined by the determination circuit, and the discrimination time is determined. The control signal generation circuit generates a control signal for controlling the amplification degree of the current-voltage conversion of the photodetector in accordance with the disc type determined by the above and the operation information of the apparatus from the controller. .

In the first feature configuration of the present invention,
The photodetector has at least 12 independent light receiving surfaces at respective positions where three light beams incident on the photodetector are irradiated, and transmits a photoelectric conversion signal obtained from each of the light receiving surfaces. Since current-voltage conversion is performed after connecting a predetermined signal line among the signal lines, a subtraction process is performed between a plurality of connected and current-voltage converted signals, and the signal is output. For example, even in the case of a configuration having three light receiving regions divided in a cross shape at each position irradiated with three light beams as shown in the conventional example, that is, 12 independent light receiving surfaces, Output signals a, b, c, and
d, (e + i)-(h + l) and (f + j)-(g + k). At this time, the defocus signal is {(a + c)-(b + d)}.
+ K1 [{(e + i)-(h + l)}-{(f + j)-(g + k)}], and the tracking error signal is obtained by the differential push-pull method {( a + b)-(c + d)｝ + K2 [｛(e +
i)-(h + l) {+ {(f + j)-(g + k)}]. In the case of the phase difference detection method, it is obtained from the phase difference between the signals a, b, c, and d. And the information reproduction signal is a sum signal of the zero-order light (a +
b + c + d).

That is, the number of signal outputs can be reduced while maintaining the same signal detection performance as that of the related art. This makes it possible to reduce the size of the photodetector by using, for example, a package having a small number of pins. it can.

Further, in the second characteristic configuration, in addition to the first characteristic configuration, a detection signal corresponding to the total light amount detected in one predetermined light receiving region and its inverted signal, that is, a differential output is generated. By providing one or more circuits for performing the operations described above, for example, the outputs of the photodetectors a, b, c, d, (e
+ i)-(h + l), (f + j)-(g + k) and the differential output of the sum signal (a + b + c + d), that is, (a + b + c + d) and − Even when (a + b + c + d) is added, eight lines can be obtained as in the conventional case.

As a result, the margin of the reproduced data signal against noise can be improved without changing the package size of the photodetector, and a photodetector with higher data reliability can be realized.

Further, in the third characteristic configuration, in addition to the first characteristic configuration, the amplification degree of the current-to-voltage conversion is changed according to a predetermined control input, so that the current-to-current conversion in the photodetector is changed. The amplification degree of the voltage conversion amplifier is adjusted according to, for example, a difference in reflectance between various disks, or a difference in reflected light intensity between recording and reproduction on a recordable disk such as a CD-R, CD-RW, or DVD-RAM. It can be changed, and can be set optimally according to various states. Even in this case, the increase in the number of photodetector terminals due to the addition of the control input is offset by the reduction in the number of output signals, so that light can be set in an optimal state without changing the size of the package and maintaining the same size as before. A detector can be realized.

According to a fourth characteristic configuration of the present invention, in the optical disk device, the first, second, or third optical disk device is used.
A plurality of semiconductor lasers, a discriminating circuit for judging the type of the optical disc, and a defocus signal of a light spot on the optical disc by using a predetermined calculation from the output of the photodetector. An error generation circuit for generating a tracking error signal, wherein one of the plurality of semiconductor lasers is selectively switched in accordance with the type of the disk determined by the determination circuit, and the semiconductor laser is determined by the determination circuit. By switching the calculation method in the error generation circuit according to the type of the disc, a compact or highly reliable optical disc apparatus compatible with various optical discs can be realized.

According to a fifth aspect of the present invention, an optical disc apparatus uses the photodetector of the third aspect, a plurality of semiconductor lasers, a discriminating circuit for judging the type of the optical disc, An error generating circuit for generating a defocus signal and a tracking error signal of a light spot on an optical disk by using a predetermined operation from an output of the detector, and a control signal for controlling an amplification degree of current-voltage conversion of the photodetector. Comprising a control signal generation circuit,
One of the plurality of semiconductor lasers is selectively switched according to the type of the disk determined by the determination circuit, and the calculation method in the error generation circuit is determined according to the type of the disk determined by the determination circuit. In addition to the switching, the control signal generation circuit controls the current of the photodetector according to the type of the disk determined by the determination circuit.
By generating a control signal for controlling the amplification degree of the voltage conversion, it is possible to perform control such as increasing the amplification degree, for example, for a disk having a low reflectivity, thereby enabling, for example, an output level from a photodetector. Can be set to a substantially constant level regardless of the type of optical disc, thereby improving the reliability against dive noise, or stabilizing the error generation level, and improving the reliability or operating stability. An optical disk device that realizes the above can be configured.

According to a sixth aspect of the present invention, an optical disc device uses the photodetector of the third aspect, a plurality of semiconductor lasers, a discriminating circuit for judging the type of the optical disc, An error generating circuit for generating a defocus signal and a tracking error signal of a light spot on an optical disk by using a predetermined operation from an output of the detector, and a control signal for controlling an amplification degree of current-voltage conversion of the photodetector. A control signal generation circuit; and a controller for controlling an operation of the optical information recording / reproducing apparatus, wherein one of the plurality of semiconductor lasers is selectively selected according to the type of the disc determined by the determination circuit. The calculation method in the error generation circuit is switched in accordance with the type of the disk determined by the determination circuit, and The control signal generation circuit generates a control signal for controlling the amplification degree of the current-voltage conversion of the photodetector in accordance with the disc type determined by the determination circuit and the operation information of the apparatus from the controller. Thus, for example, CD-R, CD-RW, DVD-RA
The degree of amplification can be controlled in accordance with the difference in reflected light intensity between recording and reproduction on a recordable disc such as M. For example, the output level from the photodetector is almost constant irrespective of the type and operating state of the optical disc Level, etc., thereby improving the reliability against diving noise,
Alternatively, it is possible to configure an optical disk device that realizes the stability of the error generation level and the like and improves the reliability or the operation stability.

[0025]

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

FIG. 1 is a diagram showing one embodiment of the configuration of the photodetector according to the present invention. In FIG. 1, reference numeral 1 denotes the entire photodetector, and reference numerals 2, 3, and 4 denote light receiving areas, 5, 6, 7, 8, 9, and 1.
Reference numerals 0, 11, and 12 denote current-voltage conversion amplifiers, and reference numerals 13 and 14 denote subtracters. In FIG. 1, the light receiving areas 2, 3, and 4 are each divided into four crosses as shown in the figure, and thus have a total of 12 divided light receiving surfaces. The light receiving areas 2, 3, 4 are arranged substantially linearly, and the light receiving areas 2, 3,.
The + 1st-order diffracted light, the 0th-order diffracted light, and the -1st-order diffracted light reflected from the optical disk with respect to 4 are collected. In FIG. 1, the light receiving surfaces a, b,
The light received at c and d is detected by photoelectric conversion as a current corresponding to the amount of light, and each detected current is converted to a voltage by current-voltage conversion amplifiers 7, 8, 9, and 10 and then output. (For the sake of simplicity, these voltage-converted detection signals are denoted by the same symbols as the light-receiving surfaces on which the detection signals are detected). Also, the light receiving surface e
Are connected to the current-voltage conversion amplifier 5 after being connected to the output line of the light receiving surface i.

For this reason, the detection current detected at the light receiving surface e and the detection current detected at the light receiving surface i are added together, and then converted into a voltage by the current-voltage conversion amplifier 5 to be added to the + of the subtractor 13.
Output to the input terminal. Similarly, the detection current detected at each of the light receiving surfaces f and j, the detection current detected at each of the light receiving surfaces g and k, and the detection current detected at each of the light receiving surfaces h and l are added together. The voltage is converted into a voltage by the voltage conversion amplifiers 12, 11 and 6, and each of the voltage is subtracted by the subtractor 1.
4, the minus terminal of the subtractor 14 and the minus terminal of the subtractor 13. The subtractors 13 and 14 subtract the signal input to the − terminal from the signal input to the + terminal and output the result. As a result, (e + i)-(h + l) is output from the subtractor 13 and (f + j)-(g + k) is output from the subtractor 14 to the output terminal. Therefore, a, b, c, d, (e + i)-(h +
l), (f + j)-(g + k) and six signals are output. Next, an optical head which is a main part of an optical disk device using the photodetector will be described with reference to FIG. Figure 2
FIG. 3 is a perspective view illustrating an example of a configuration of an optical head. In FIG. 2, 30 is a semiconductor laser light source, 31 is a diffraction grating, 32 is a cubic type beam splitter,
33 is a collimating lens, 34 is a rising mirror, 35 is an objective lens, 36 is an optical disk, 37 is a cylindrical lens, 38 is a two-dimensional actuator, 39, 40, and 41 are optical disks. The upper light spot. Note that the photodetectors are given the same numbers as in FIG. In FIG. 2, a laser beam emitted from a semiconductor laser light source 30 is incident on a diffraction grating 31, where the 0th-order light passing through the diffraction grating 31 as it is, and the + 1st-order diffracted light and-which are separated and proceed from the 0th-order light at a predetermined diffraction angle. The light is separated into at least three light beams of the first-order diffracted light. Then, these three light beams enter the collimator lens 33 via the beam splitter 32, and the collimator lens 3
After being converted into a parallel light beam by 3, it is condensed on the surface of an optical disk 36 via a rising mirror 34 and an objective lens 35,
Light spots 39, 40 and 41 are formed. Further, the optical disk 36 is reflected and follows the same optical path as the outward light, that is, the objective lens 35 and the rising mirror 3
4. Beam splitter 32 through collimating lens 33
Are reflected on the light receiving surface of the photodetector 1 via the cylindrical lens 37. On the photodetector 1, the 0-order light reflected from the optical disc 36 and the +
The position where each light beam of the first-order diffracted light and the -1st-order diffracted light is substantially at the center of the light receiving regions 3, 2, and 4, that is, the point where the vertical and horizontal divisions of the light receiving region intersect and the intensity center of the light beam almost coincides. Is collected and detected. A two-dimensional actuator 38 is attached to the objective lens 35, and the two-dimensional actuator 38 controls the objective lens 35 by a control signal based on a defocus signal and a tracking error signal generated from the output of the photodetector 1. The position is controlled so that the light spots 39, 40, and 41 are at desired positions on the optical disk 36. Here, in the arrangement of the light receiving region of the photodetector in FIG. 1, the defocus signal is expressed by ｛(a + c) − (b +
d)｝ + K1 [｛(e + i)-(h + l)｝ − ｛(f + j)-(g + k)｝], and the tracking error signal is obtained by the differential push-pull method. Case {(a + b)-(c + d)} + K2
[{(E + i)-(h + l)} + {(f + j)-(g + k)}], and in the case of the phase difference detection method, the phase difference between the signals a, b, c, and d And the reproduced signal of the information is the sum signal of the zero-order light (a +
b + c + d). In the above equation, K
1, K2 is, for example, 0 order light and +1 order light or 0 order light and-
It is a constant determined from the light intensity ratio with the primary light. Generally, in an optical disk device, it is necessary to control the light spots 39, 40, and 41 so that the light spots 39, 40, and 41 are accurately positioned at desired positions on the optical disk 36 in order to reproduce data at a desired position or record data at a desired position. For this purpose, it is necessary to accurately generate the defocus signal and the tracking error signal from the output of the photodetector 1. According to the above-described embodiment, the defocus signal is obtained by using the subtraction circuit. And the number of the conventional eight output signals is a, b, c, d, (e + i)-(h +
l), (f + j)-(g + k), which can be reduced to six, and thereby, for example, the package size can be reduced and downsizing can be realized.

Next, a second embodiment of the photodetector according to the present invention will be described with reference to FIG. In FIG. 3, reference numeral 15 denotes an adder having a differential output, and the same parts as those in FIG. 1 are denoted by the same reference numerals. In the operation of the photodetector shown in FIG. 3, the reflected light condensed is detected, and a, b, c, d, (e + i)-
The operation of outputting the six detection signals (h + l) and (f + j)-(g + k) is the same as that of FIG. 1 and the description is omitted. In FIG. 3, the outputs of the current-voltage conversion amplifiers 7, 8, 9, and 10 are
The adder 15 adds these signals, generates a differential output of the addition result, and outputs it to the output terminal.

Therefore, in this embodiment, a, b, c,
d, (e + i)-(h + l), (f + j)-(g + k), (a + b + c + d),-(a + b + c +
The eight signals of d) are output. It is apparent from the first embodiment that the above-described output can generate a defocus signal and a tracking error signal similar to those in the related art. Further, in the present embodiment, the output signals (a + b + c + d) and-(a + b + c + d)
Is output, for example, even if a dive noise occurs in the transmission path, for example, (a + b + c + d) and-(a + b + c + d) on the transmitted device side By taking the difference with ()), the common-mode component of the noise can be removed, and the margin for noise can be increased. Thus, a photodetector with high data reliability can be realized.

Next, a third embodiment of the photodetector according to the present invention will be described with reference to FIG. In FIG.
Reference numerals 7, 18, 19, 20, 21, 22, and 23 denote current-voltage conversion amplifiers, each of which has an amplification degree controlled by a control input input from outside the photodetector 1. The same parts as those in FIG. 1 are given the same numbers. In the operation of the photodetector shown in FIG. 3, reflected light condensed is detected, and a, b, c, d, (e + i)-(h + l), (f + j)-(g + k ) 6
The basic operation of outputting the book detection signal is the same as that of FIG. 1 and the description is omitted. It is clear from the first embodiment that the same defocus signal and tracking error signal can be generated as in the conventional configuration in FIG. Further, in this embodiment, a control signal input is provided to the photodetector 1 so that the current-
Voltage conversion amplifiers 16, 17, 18, 19, 20, 21,
Since the amplifications of the 22 and 23 can be controlled by the control input, the amplification of the current-to-voltage conversion amplifier can be optimally adjusted, for example, in response to the difference in the reflectivity of various disks while keeping the number of terminals below the conventional one. Can be set. As a result, it is possible to increase the signal output even for a disk having a low reflectance, for example, without causing an increase in the package size, thereby improving data reliability. Alternatively, CD-R, CD-RW, DVD-RA
By setting the amplification of the current-to-voltage conversion amplifier optimally in response to the difference in reflected light intensity between recording and reproduction on a recordable disc such as M, the output is not saturated during recording, that is, at high power. The operation stability or data reliability can be improved by, for example, increasing the amplification during reproduction to increase the signal output.

Next, an embodiment of an optical disk apparatus to which the photodetector of the present invention is applied will be described with reference to FIG. FIG.
Is a schematic block diagram of an optical disk device, wherein 42 is a pickup, 43 is an optical disk, 44 is a spindle motor,
Reference numeral 45 denotes a signal processing circuit, 46 denotes a controller, 47 denotes a discrimination circuit, 48 denotes an error generation circuit, 49 denotes a servo circuit, and 50 denotes an entire disk device. Pickup 42
Are provided with first and second semiconductor lasers 30a and 30b, an actuator 38, an objective lens 35, and the photodetector 1 described in the embodiment of FIG. 1, FIG. 2, or FIG. Here, for example, the semiconductor laser 30a is a DVD
-It is used for high-density disks such as RAM and DVD-ROM disks, and emits a laser beam having a wavelength of about 650 nm. The semiconductor laser 30b is a CD, CD-R, CD-RW, etc. And emits a laser beam having a wavelength of about 780 nm. Also, the optical disk 43
Although not shown, the spindle motor 44 is in close contact with, for example, a clamper using a magnet or the like, and the servo circuit 49 rotates the spindle motor 44 at a desired number of rotations using a rotation information signal supplied from the spindle motor 44.
Is rotated, the optical disk 43 is rotated at a desired rotation speed. Next, the operation of the embodiment shown in FIG. 5 will be described. First, an external interface signal is input to the controller 46 via the signal processing circuit 45. The controller 46 determines the operation of the optical disk device 50 based on the interface signal, and issues a command regarding the operation to the signal processing circuit 45 and the servo circuit 49. Signal processing circuit 4
5. The servo circuit 49 performs a circuit operation based on the operation command.

For example, in the case of signal reproduction, the signal processing circuit 45
Then, data reproduction processing and the like are performed from the output of the photodetector 1. Here, the discrimination circuit 47 discriminates the type of the disc from information such as a difference in disc reflectivity and the shape of the disc cartridge, and outputs a discrimination signal to the signal processing circuit 45 and the servo circuit 49. The signal processing circuit 45 controls the semiconductor laser 30 based on the determination signal in addition to the reproduction operation.
a, 30b, and generates a control signal, for example, DVD-
For a high-density disc such as a RAM or a DVD-ROM disc, control is performed so that the semiconductor laser 30a emits light and the semiconductor laser 30b does not emit light. Further, for example, a control is performed so that the semiconductor laser 30b emits light to a disk such as a CD, CD-R, and CD-RW, and the semiconductor laser 30a does not emit light. Although not shown in detail, a light beam emitted from either of these semiconductor lasers is incident on the objective lens 35 by light path synthesis, is condensed, forms a light spot on the optical disk 43, and is reflected. Although not shown in detail, the reflected light is converged on the photodetector 1, detected and output from the pickup 42 as shown in the embodiment of FIG. 1, FIG. 2, or FIG. The detection signal is processed by the signal processing circuit 45 and the error
8 is supplied. The error generation circuit 48 generates a defocus signal of the light spot and a tracking error signal from the detection signal based on the determination signal supplied from the determination circuit 47. Specifically, for example, the defocus signal is an astigmatism method,
The tracking error signal is calculated using a phase difference detection method in the case of a DVD-ROM disc, and using a differential push-pull method or the like for other discs.
9 is output. The servo circuit 49 controls the rotation of the spindle motor 44 and controls the actuator 38 based on the defocus signal of the light spot obtained from the error generation circuit 48 and the tracking error signal.
As a result, the light spot can always be located at a desired position, and desired data can be reproduced. As described above, the optical disk device of the present configuration can support various disks by switching the operation method for generating the semiconductor laser and the error signal by discriminating the disk.
Further, since the optical detector shown in the embodiment of FIG. 1, FIG. 2, or FIG. 3 is used in the pickup, the pickup can be reduced in size or performance, and the optical disk device can be reduced in size or performance. Can be realized.

Next, a second embodiment of the optical disk apparatus to which the photodetector of the present invention is applied will be described with reference to FIG. In FIG. 6, reference numeral 51 denotes a control generation circuit for generating a control signal for controlling the degree of amplification in the photodetector 1, and other circuit blocks identical to those in FIG. Here, the photodetector 1 mounted on the pickup 42 is the photodetector described with reference to FIG. The basic operation of each circuit block in the optical disk device of FIG. 6 is the same as that of FIG. Hereinafter, the characteristic operation in FIG. 6 will be described.
In FIG. 6, the discrimination signal generated by the discrimination circuit 47 is also input to the control generation circuit 51 together with the signal processing circuit 45 and the error generation circuit 48. The error generation circuit 51 generates a control signal based on the input discrimination signal and supplies the control signal to the photodetector 1 mounted on the pickup 42. The photodetector 1 changes the amplification degree in the current-voltage conversion according to the input control signal. In the above configuration, not only can various types of disks be supported as in the embodiment of FIG.
VD-RAM, DVD-ROM dual-layer disc, CD-
Control such as increasing the degree of amplification can be realized for a disk such as a RW having a low reflectance, that is, a detection signal level is low. As a result, it is possible to prevent the level of the detection signal output from the pickup from largely changing depending on the type of the disc. For example, it is possible to improve the reliability against the dive noise and to stabilize the error signal level. An optical disk device with improved performance and operational stability can be realized.

Next, a description will be given of a third embodiment of an optical disk apparatus to which the photodetector of the present invention is applied, with reference to FIG. 7, the same circuit blocks as those in FIG. 6 are denoted by the same reference numerals. Here, the photodetector 1 mounted on the pickup 42 is the photodetector described with reference to FIG. The basic operation of each circuit block in the optical disk device of FIG. 6 is the same as that of FIG. Hereinafter, the characteristic operation in FIG. 7 will be described. In FIG. 7, the discrimination signal generated by the discrimination circuit 47 is also input to the control generation circuit 51 together with the signal processing circuit 45 and the error generation circuit 48. An operation information signal indicating the operation state of the optical disk device is also input from the controller 46 to the control generation circuit 51. Here, the operation information signal is a signal indicating, for example, a recording operation and a reproducing operation. The error generation circuit 51 generates a control signal based on the input discrimination signal and operation information signal, and
The light is supplied to the photodetector 1 mounted on the photodetector 2. Photodetector 1
Changes the degree of amplification in current-voltage conversion according to the input control signal. In the above-described configuration, not only can the disk be compatible with various disks as in the embodiment of FIG. 5, but also a control signal is generated based on device operation information.
It is possible to set the degree of amplification to be small during a recording operation on a recording type disc such as M, CD-R, CD-RW or the like. When information is recorded on a recordable disc, the light intensity at the light spot on the optical disc is required to be ten times or more as compared with that at the time of reproduction. As the light intensity increases, the reflected light intensity, that is, detection by the photodetector, is performed. Although the signal level increases, in this configuration, control such as lowering the amplification degree can be realized in such a case. As a result, it is possible to prevent the level of the detection signal output from the pickup from being saturated or greatly changed depending on the operation state. For example, an error signal can be generated accurately and the error signal level can be stabilized. An optical disk device with improved reliability and operation stability can be realized.

The photodetector in the above embodiment has a configuration in which 12 light-receiving surfaces are independently provided by arranging three light-receiving regions divided into four in a cross-shaped manner. The present invention is not limited to this. Even when a configuration having 12 or more independent light receiving surfaces is used, a subtractor is provided for the output of the current-voltage converter so as to satisfy the calculation method for generating the defocus signal and the tracking error signal. The number of output lines may be reduced by using such an arrangement, and it is apparent that the same effect as in the above-described embodiments can be obtained.

In the above embodiment, the subtractor is 2
However, the present invention is not limited to this. For example, in FIGS. 1, 3, and 4, the subtractor 14 may be eliminated or the subtractor 13 may be eliminated. Even in these configurations, two outputs (e + i) and (h + l) are output to (e + i)-(h + l) or two outputs (f + j) and (g + k). Are aggregated to (f + j)-(g + k), the number of output signals can be reduced, and the same effect as in the embodiment of FIGS. 1, 3, and 4 can be obtained. It is obvious.

[0037]

As described above, in the first characteristic configuration of the present invention, for example, by providing two subtraction processing circuits, output signals a, b, c, d, (e + i)- (h + l),
(f + j)-(g + k). At this time, the defocus signal is {(a + c)-(b + d)} + K1 [{(e + i)-(h
+ l) {− {(f + j)-(g + k)}], and the tracking error signal is obtained by the differential push-pull method {(a +
b)-(c + d)｝ + K2 [｛(e + i)-(h + 1)｝ + ｛(f + j)
-(g + k)｝], and a, b,
It can be obtained from the phase difference between the signals c and d, and the information reproduction signal can be obtained from (a + b + c + d) which is the sum signal of the zero-order light.

Accordingly, it is possible to reduce the number of signal outputs while maintaining the same signal detection performance as in the prior art, thereby realizing the miniaturization of the photodetector by using a package having a small number of pins, for example. it can.

Further, in the second characteristic configuration, in addition to the above-mentioned first characteristic configuration, by providing an adder having a differential output, a conventional arrangement is provided despite having a differential output of a sum signal. Of eight. As a result, it is possible to improve the margin for the dive noise of the reproduced data signal without changing the package size of the photodetector, and to realize a photodetector with higher data reliability.

Further, in the third characteristic configuration, in addition to the first characteristic configuration, the amplification degree of the current-voltage conversion is changed according to a predetermined control input, so that the current-voltage in the photodetector is changed. The amplification degree of the voltage conversion amplifier is adjusted according to, for example, a difference in reflectance between various disks, or a difference in reflected light intensity between recording and reproduction on a recordable disk such as a CD-R, CD-RW, or DVD-RAM. It can be changed, and can be set optimally according to various states. Even in this case, the increase in the number of photodetector terminals due to the addition of the control input is offset by the reduction in the number of output signals. Can be realized.

According to a fourth characteristic configuration of the present invention, in the optical disk device, the first, second, or third optical disk device is used.
And selectively switching one of the plurality of semiconductor lasers according to the disc type determined by the discriminating circuit, and according to the disc type determined by the discriminating circuit. By switching between the calculation methods of the defocus signal and the tracking error signal in the error generation circuit, a compact or highly reliable optical disk device compatible with various optical disks can be realized.

According to a fifth aspect of the present invention, an optical disk apparatus uses the photodetector of the third aspect and uses one of a plurality of semiconductor lasers according to the type of the optical disk determined by the determination circuit. Switch selectively,
The method of calculating the defocus signal and the tracking error signal in the error generation circuit is switched according to the type of the optical disc determined by the discrimination circuit, and the control signal generation circuit is controlled by the disc type determined by the discrimination circuit. By generating a control signal for controlling the amplification degree of the current-voltage conversion of the photodetector, for example, it is possible to perform control such as increasing the amplification degree for a disk having a low reflectivity. The output level from the detector can be made almost constant irrespective of the type of the optical disk, thereby improving the reliability against the dive noise or stabilizing the error generation level, thereby improving the reliability. Alternatively, it is possible to configure an optical disk device that realizes improvement in operation stability.

According to a sixth aspect of the present invention, an optical disk apparatus uses the photodetector of the third aspect and uses one of a plurality of semiconductor lasers according to the type of the optical disk determined by the determination circuit. Switch selectively,
The method of calculating the defocus signal and the tracking error signal in the error generation circuit is switched according to the type of the optical disk determined by the determination circuit, and the type of the disk determined by the determination circuit and the device from the controller. The control signal generation circuit generates a control signal for controlling the amplification degree of the current-to-voltage conversion of the photodetector in accordance with the operation information.
R, CD-RW, DVD-RAM, etc., the degree of amplification can be controlled in accordance with the difference in reflected light intensity between recording and reproduction during recording and reproduction. For example, the output level from the photodetector can be controlled by the type of optical disc. , Which can be almost constant regardless of the operating state, thereby improving the reliability against diving noise, stabilizing the error generation level, etc., and improving the reliability or operating stability The optical disk device can be configured.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a photodetector according to the present invention.

FIG. 2 is a diagram showing an embodiment of an optical pickup using the present invention.

FIG. 3 is a block diagram showing a second embodiment of the photodetector of the present invention.

FIG. 4 is a block diagram showing a third embodiment of the photodetector of the present invention.

FIG. 5 is a diagram showing a first embodiment of an optical disk device using the photodetector of the present invention.

FIG. 6 is a diagram showing a second embodiment of the optical disk device using the photodetector of the present invention.

FIG. 7 is a diagram showing a third embodiment of the optical disk device using the photodetector of the present invention.

FIG. 8 is a diagram showing a configuration of a conventional photodetector.

[Explanation of symbols]

1: photodetector, 2, 3, 4 ... light receiving area, 5, 6, 7, 8
・ 9 ・ 10 ・ 11 ・ 12 ・ 16 ・ 17 ・ 18 ・ 19 ・ 2
0.21, 22.23 ... current-voltage conversion amplifier, 13.
14 subtractor, 15 adder, 30a / 30b semiconductor laser, 42 pickup, 43 optical disk, 45
... Signal processing circuit, 46 ... Controller, 47 ... Discrimination circuit, 48 ... Error generation circuit, 50 ... Optical disk device.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Kuniichi Onishi, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Digital Media Development Division, Hitachi, Ltd. (72) Katsuhiko Izumi, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa 292 F-term (reference), Digital Media Development Division, Hitachi, Ltd. 5D118 AA04 AA26 BA01 BB01 BB02 BF02 BF03 CA02 CA13 CD02 CD03 CD08 CF06 CF16 CG04 DA03 DA35 5D119 AA06 AA41 BA01 DA01 DA05 EA02 EA03 EC45 EC47 FA05 KA03 HA02 KA43 5F073 BA04 BA05 BA06 GA37 GA38

Claims (6)

[Claims] 1. A light beam emitted from a semiconductor laser and condensed to form a respective light spot at a predetermined position on an optical information recording medium and reflected by a plurality of light receiving surfaces for receiving the respective light beams. A photodetector for detecting a signal based on the amount of light received on each light receiving surface by converting the photoelectric conversion signal into a current-voltage signal, and having at least twelve independent light receiving surfaces. The current-to-voltage conversion is performed after a predetermined signal line among the signal lines transmitting the photoelectric conversion signal obtained from each of the independent light receiving surfaces is connected, and the connection is made to the current-to-voltage conversion. A photodetector characterized in that a subtraction process is performed between predetermined signals and output. 2. The photodetector according to claim 1, wherein a detection signal corresponding to a total light amount detected in a predetermined light receiving region and an inverted signal thereof are also output. Light detector. 3. The photodetector according to claim 1, further comprising a control input terminal, wherein the amplification degree of the current-voltage conversion is changed according to a control input input from the control input terminal. A photodetector characterized by: 4. The method according to claim 1, 2 or 3.
An optical information recording / reproducing apparatus equipped with the photodetector according to the above, comprising a plurality of semiconductor lasers, a discriminating circuit for judging the type of the optical information recording medium, and a predetermined circuit based on the output of the photodetector. An error generating circuit that generates a defocus signal and a tracking error signal of a light spot on the optical information recording medium by using an arithmetic operation, wherein the plurality of semiconductor lasers are provided in accordance with the type of the disk determined by the determining circuit. An optical information recording / reproducing apparatus characterized in that one of them is selectively switched, and the calculation method in the error generation circuit is switched according to the type of the disc determined by the determination circuit. 5. An optical information recording / reproducing apparatus equipped with the photodetector according to claim 3, comprising: a plurality of semiconductor lasers; a discriminating circuit for judging a type of the optical information recording medium; An error generation circuit that generates a defocus signal and a tracking error signal of a light spot on an optical information recording medium by using a predetermined operation from the output of the photodetector, and controls the amplification of the current-voltage conversion of the photodetector. A control signal generating circuit for generating a control signal for performing the switching operation, selectively switching one of the plurality of semiconductor lasers according to the type of the disk determined by the determination circuit, and determining the one by the determination circuit. The operation method in the error generation circuit is switched according to the type of the disk, and the control signal generation circuit switches the current of the photodetector according to the type of the disk determined by the determination circuit. The optical information recording and reproducing apparatus characterized by being configured to generate a control signal for controlling the amplification degree of the voltage conversion. 6. An optical information recording / reproducing apparatus equipped with the photodetector according to claim 3, comprising: a plurality of semiconductor lasers; a determination circuit for determining a type of the optical information recording medium; An error generation circuit that generates a defocus signal and a tracking error signal of a light spot on an optical information recording medium by using a predetermined operation from the output of the photodetector, and controls the amplification of the current-voltage conversion of the photodetector. A control signal generation circuit for generating a control signal to be performed, and a controller for controlling the operation of the optical information recording / reproducing apparatus, wherein one of the plurality of semiconductor lasers is selected according to the type of the disk determined by the determination circuit. And the calculation method in the error generation circuit is switched according to the type of the disk determined by the determination circuit, and the determination method is determined by the determination circuit. The control signal generation circuit is configured to generate a control signal for controlling the amplification degree of current-voltage conversion of the photodetector according to the type of the disc and the operation information of the apparatus from the controller. Optical information recording / reproducing device.