JP4380345B2 - Photodetection device, optical pickup and optical disk device - Google Patents

Description

  The present invention relates to an optical disc apparatus that records and reproduces optical signals on and from an optical recording medium, an optical pickup used in the optical disc apparatus, and a light detection device provided in the optical pickup.

As shown in FIG. 6 , an optical pickup incorporated in a CD player or a CD-ROM player is arranged in a laser light source 52 for emitting a recording / reproducing light beam, and in the light beam emitting direction of the laser light source 52. A beam splitter 54, a collimator lens 56 that converts the light beam from the laser light source 52 that has passed through the beam splitter 54 into parallel light, and a light beam that has been converted into parallel light by the collimator lens 56 to collect light. An objective lens 58 that irradiates the light beam 70; and a photodetector 60 that receives a reflected light beam from the optical recording medium 70 that is disposed opposite to the reflection direction of the beam splitter 54 and is reflected by the beam splitter 54 and converts it into an electrical signal. Is provided.

FIG. 7 shows a circuit configuration diagram of a conventional photodetector 60, and shows a circuit for one channel out of eight channels.
In FIG. 7 , a photodetector 60 includes a current-voltage conversion circuit 602 that converts a current flowing through the photosensor 601 into a voltage. The current-voltage conversion circuit 602 includes an operational amplifier OP and a resistor R1 connected in series between the inverting input terminal of the operational amplifier OP and the output terminal 603. Between the inverting input terminal of the operational amplifier OP and the ground, A photosensor 601 is connected, and the voltage Vc is supplied to the non-inverting input terminal of the operational amplifier OP.

In such a conventional optical pickup, a light beam corresponding to a recording signal is generated from the laser light source 52 when recording on the optical recording medium 70. The light beam passes through the beam splitter 54 and is incident on the collimator lens 56. The collimator lens 56 makes the collimated light incident on the objective lens 58. The objective lens 58 collects parallel light into a small spot and irradiates the optical recording medium 70. As a result, the recording film of the optical recording medium 70 is altered to record a signal on the optical recording medium 70.
On the other hand, the light beam being recorded is reflected from the optical recording medium 70, and the reflected light passes through the objective lens 58 and the collimator lens 56 and is then reflected and incident on the photosensor 601 by the beam splitter 54. The optical signal received by the photosensor 601 is converted into an electrical signal and extracted as various information signals.
Further, at the time of reproduction, a constant light beam having an intensity sufficiently weaker than that at the time of recording is generated from the laser light source 52, and this optical beam is irradiated onto the optical recording medium 70 through the same optical path as at the time of recording. Then, the reflected light beam reflected from the recording surface of the optical recording medium 70 passes through the objective lens 58 and the collimator lens 56, is reflected by the beam splitter 54 to the photosensor 601, and the optical signal incident on the photosensor 601 is It is converted into an electrical signal and extracted as various information signals such as an RF signal, a focus error signal, and a tracking error signal.
The RF signal includes an RF signal for reproduction (referred to as an RRF signal) used for detecting data of the optical recording medium at the time of reproduction, and light emitted from a light source by detecting a recording state with respect to the optical recording medium at the time of recording. There are two types of recording RF signals (referred to as WRF signals) used for controlling the beam output power.
JP 2003-223734 A

By the way, as the drive speed of CD-R and DVD-R increases, the light beam emission power at the time of recording increases with respect to the light beam emission power at the time of reproduction. The difference in signal level is widening.
The detection signal detected by the light receiving element of the optical pickup is converted from a current signal to a voltage signal and amplified by a current-voltage conversion circuit. This amplification factor is optimally set during reproduction. During recording, the amplified voltage signal is saturated. Therefore, the current-voltage conversion circuit is configured to switch the amplification factor (gain) for each channel between reproduction and recording in order to avoid saturation of the voltage signal.
On the other hand, in the optical pickup for CD-R and DVD-R, the recording power of the laser beam increases as the recording speed is increased. For example, a laser beam with higher power is required for 24 × recording than for 8 × recording. Along with this, the amount of light incident on the light receiving element constituting the optical signal detection unit also increases, resulting in the following problems.
That is, since the operational amplifier constituting the current-voltage conversion circuit has a characteristic that the output voltage becomes saturated when the output voltage becomes 4 V or more, for example, a light receiving element created for 8 × recording is used for 24 × recording. When used in an optical pickup, the output signal of the current-voltage conversion circuit is saturated, and the optical signal cannot be normally detected. For this reason, the gain of the current-voltage conversion circuit is switched in the direction of decreasing so that the output voltage of the current-voltage conversion circuit does not saturate even when the light receiving element receives 24 × speed laser light power.

  Thus, the operational amplification for adding / subtracting the gain of each current-voltage conversion circuit at the time of reproduction of CD-R or DVD-R and the gain of each current-voltage conversion circuit at the time of recording or the output signal of each current-voltage conversion circuit. As the gain of the circuit is switched by an independent control signal, or when high-speed recording is performed, the recording power increases and the system margin becomes severe, so the output level of each current-voltage conversion circuit and operational amplifier circuit is Since it becomes necessary to strictly control, the number of target circuits for switching gains increases. Accordingly, when it is attempted to increase the number of switching stages of the gain switching target circuit, or when a new output signal is to be extracted from the light detection unit, a light detection unit, a current-voltage conversion circuit, or an operational amplification circuit is formed. The number of IC chip pads and the number of pins on the substrate on which the IC chip is mounted are insufficient, and if these pads and pins are increased to match the shortage, the IC chip and the substrate become larger and can be stored in the existing package. It becomes impossible to design and manufacture a package that can accommodate an IC chip and a substrate, which increases the size and cost of the package, and also increases the size of the optical pickup on which the package is mounted. Cannot be mounted on a CD-R or DVD-R drive device. In addition, as the number of circuits such as current-voltage conversion circuits and operational amplifier circuits increases, the power consumption increases when these circuits are always in an operating state, and the IC chip including the light detection unit and various circuits is transparent. In the case of mold packaging using a resin material, there is a problem that the mold resin is softened or deformed by heat from a circuit portion or the like.

  The present invention has been made to solve such a conventional problem. The gain of the current-voltage conversion amplifier circuit and the output signal of each current-voltage conversion amplifier circuit are multiplied by the number of command inputs. The gain of the operational amplifier circuit that adds and subtracts and outputs the control signal can be selected according to the recording speed or reproducing operation during recording and the type of optical recording medium during reproducing, and the number of pins required for the command input can be reduced and An object of the present invention is to provide a photodetection device capable of reducing operating current and miniaturization, an optical pickup using the photodetection device, and an optical disc device.

In order to achieve the above object, the present invention provides a light detection including a plurality of light receiving elements that receive a reflected light beam reflected by the optical recording medium when recording and / or reproducing by irradiating the optical recording medium with the light beam. A plurality of amplifying circuits provided in each of the plurality of light receiving elements, each of which converts a current signal from each of the light receiving elements into a voltage signal and outputs the voltage signal; and a voltage output from the plurality of amplifying means A plurality of operational amplifier circuits that add two or more voltage signals selected from the signals and output a control signal necessary for recording or reproducing an optical signal; and the plurality of operational amplifier circuits and the operational amplifier circuits The amplifier circuit and the operational amplifier circuit necessary for recording or reproducing the optical signal are selected and controlled to operate, and the amplifier circuit and the operational amplifier circuit other than the selected amplifier circuit and the operational amplifier circuit are not operated. A first selection control signal to be controlled, and the amplifier circuit and the operational amplifier circuit so that the output level of the selected amplifier circuit and the operational amplifier circuit becomes a value suitable for recording or reproduction of the optical signal. A selection circuit for sending a plurality of second selection control signals for separately setting and controlling the gain of the plurality of stages , wherein the selection circuit includes a plurality of command signal input terminals, and the selection circuit includes the command signals. The first and second selection control signals are generated by a combination of binary logic signals given at high / low applied to an input terminal, the light receiving element, the amplifier circuit, the operational amplifier circuit, The selection circuit and the plurality of command signal input terminals are formed on the same semiconductor substrate .

The present invention also provides a light source that emits a recording and / or reproducing light beam, an objective lens that collects the light beam emitted from the light source and irradiates the optical recording medium, and An optical pickup comprising: a light detection device including a plurality of light receiving elements that receive a reflected light beam from the optical recording medium via the objective lens, wherein the light detection device includes the plurality of light receiving elements. And a plurality of amplifier circuits that convert the current signals from the respective light receiving elements into voltage signals and output the voltage signals, and two or more selected from the voltage signals output from the plurality of amplification means A plurality of operational amplifier circuits that output the control signals necessary for recording or reproducing the optical signal by adding the voltage signals of the two, and amplification necessary for recording or reproducing the optical signal from the plurality of amplifier circuits and operational amplifier circuits Times And selecting an operational amplifier circuit to control the operational state, and sending a first selection control signal for controlling the selected amplifier circuit and operational amplifier circuit other than the selected operational amplifier circuit and the operational amplifier circuit to a non-operating state; and A plurality of amplifiers and operational amplifier circuits are set and controlled separately in a plurality of stages so that the output levels of the selected amplifier circuits and operational amplifier circuits become values suitable for optical signal recording or reproduction. A selection circuit for sending a second selection control signal , the selection circuit having a plurality of command signal input terminals, and the selection circuit is a binary signal given by high / low applied to each command signal input terminal. The first and second selection control signals are generated by a combination of logic signals, and the light receiving element, the amplification circuit, the operational amplification circuit, the selection circuit, and the plurality of selection signals Command signal input terminal is characterized in that it is formed on the same semiconductor substrate.

The present invention also provides a driving means for holding and rotating the optical recording medium, and irradiating the optical recording medium rotated and driven by the driving means with a recording and / or reproducing light beam from the optical recording medium. An optical disc apparatus having an optical pickup for detecting a reflected light beam, wherein the optical pickup condenses the light beam emitted from the recording and / or reproducing light beam and the light beam emitted from the light source. An objective lens that irradiates the optical recording medium, and a light detection device that includes a plurality of light receiving elements that receive a reflected light beam of the irradiated light beam on the optical recording medium through the objective lens, The photodetector is provided in each of the plurality of light receiving elements, converts a current signal from each of the light receiving elements into a voltage signal, and outputs the voltage signal; A plurality of operational amplifier circuits that add two or more voltage signals selected from the voltage signals output from the amplifier circuit and output a control signal necessary for recording or reproducing an optical signal; and the plurality of amplifier circuits And an amplifier circuit and an operational amplifier circuit necessary for recording or reproducing an optical signal from among the operational amplifier circuits to control the operation state, and an amplifier circuit and an operational amplifier circuit other than the selected amplifier circuit and the operational amplifier circuit Each of the amplifier circuits so that the output level of each of the selected amplifier circuits and operational amplifier circuits is a value suitable for recording or reproduction of an optical signal. and the gain of the operational amplifier circuit and a selection circuit for transmitting a plurality of second selection control signal for setting separately controlled, the selection circuit comprises a plurality of command signal input terminal, said selection circuit The first and second selection control signals are generated by a combination of high and low binary logic signals applied to the command signal input terminals, the light receiving element, the amplifier circuit, and the calculation The amplifier circuit, the selection circuit, and the plurality of command signal input terminals are formed on the same semiconductor substrate .

  According to the photodetector, the optical pickup, and the optical disc apparatus according to the present invention, amplification necessary for recording or reproducing an optical signal from among a plurality of amplifier circuits and operational amplifier circuits by a first selection control signal sent from the selection circuit. Select a circuit and an operational amplifier circuit, control these circuits to an operating state, control an amplifier circuit other than the selected amplifier circuit and the operational amplifier circuit, and an operational amplifier circuit to an inoperative state, and send the selected circuit from the selected circuit. The gains of the respective amplifier circuits and the operational amplifier circuits are separately set so that the output levels of the selected amplifier circuits and the operational amplifier circuits become values suitable for recording or reproduction of the optical signal by the second selection control signal. Therefore, even if the number of bits of the command input to the selected circuit is several bits, the current-voltage conversion that doubles this command input bit number The gain of the amplifier circuit and the gain of the operational amplifier circuit can be selected according to the recording speed at the time of recording or the reproduction operation or the type of optical recording medium at the time of reproduction, and the number of pins required for command input to the selection circuit is reduced. This makes it possible to reduce the size of the optical pickup including the photodetection device, and can easily be accommodated in an existing package. Furthermore, the operating current can be reduced by controlling the amplifying circuit and the operational amplifying circuit other than the selected amplifying circuit and the operational amplifying circuit to the non-operating state, and softening or deformation can be prevented by the heat of the transparent mold package.

The light detection device, the optical pickup, and the optical disc device according to the best mode of the present invention receive a plurality of reflected light beams reflected on the recording surface of the optical recording medium by a first selection control signal sent from the selection circuit. A plurality of amplifier circuits connected to each of the light receiving elements, and two or more voltage signals selected from the voltage signals output from the amplifier circuits, and a control signal necessary for recording or reproducing an optical signal The amplifier circuit and the operational amplifier circuit necessary for recording or reproducing the optical signal are selected from the plurality of operational amplifier circuits that output the signal, and these circuits are controlled to be in an operating state and other than the selected amplifier circuit and the operational amplifier circuit. The amplifier circuit and the operational amplifier circuit are controlled in a non-operating state. Then, according to the second selection control signal sent from the selection circuit, each amplification circuit and calculation so that the output level of each of the selected amplification circuit and calculation amplification circuit becomes a value suitable for recording or reproduction of the optical signal. Set the gain of the amplifier circuit separately.
As a result, the gain of the amplifier circuit that is multiplied by the number of command inputs and the gain of the operational amplifier circuit that outputs the control signal by adding / subtracting the output signal of each amplifier circuit are recorded at the recording speed or reproducing operation and the light at the reproducing time. In addition to being able to select according to the type of recording medium, it is possible to reduce the number of pins required for command input to the selection circuit, reduce the operating current, and reduce the size.

Embodiments of a light detection device, an optical pickup, and a recording / reproduction device according to the present invention will be described below in detail with reference to the drawings.
FIG. 2 is a block diagram showing the configuration of the optical disc apparatus incorporating the photodetector and the optical pickup in Embodiment 1 of the present invention. The optical disk device shown in FIG. 2 is an example of a recording / reproducing device in which an optical pickup described below can be mounted.

  In FIG. 2, an optical disk apparatus 101 includes a spindle motor 103 as a driving means for rotationally driving an optical disk 102 as an optical recording medium such as a CD-R and a DVD-R, an optical pickup 104, and a feed motor as the driving means. 105. Here, the spindle motor 103 is configured to be driven and controlled at a predetermined rotational speed by the system controller 107 and the servo control unit 109.

The signal modulation / demodulation unit and ECC block 108 modulates and demodulates a signal output from the signal processing unit 120 and adds an ECC (error correction code). The optical pickup 104 irradiates the signal recording surface of the optical disc 102 rotating according to commands from the system controller 107 and the servo control unit 109, respectively. Recording and reproduction of an optical signal with respect to the optical disc 102 is performed by such light irradiation.
Further, the optical pickup 104 can detect various light beams as will be described later based on the reflected light beam from the signal recording surface of the optical disc 102 and can supply a signal corresponding to each light beam to the signal processing unit 120. It is configured as follows.

The signal processing unit 120 is a servo control signal based on a detection signal corresponding to each light beam, that is, a focus error signal, a tracking error signal, an RF signal, and a monitor signal (hereinafter referred to as an R-OPC signal) necessary for running OPC processing. In other words, an ATIP signal required for controlling the rotation of the optical disc during recording can be generated. Further, predetermined processing such as demodulation and error correction processing based on these signals is performed by the servo control unit 109, the signal modulation and ECC block 108, and the like according to the type of recording medium to be reproduced.
Here, if the recording signal demodulated by the signal modulation and ECC block 108 is, for example, for data storage of a computer, it is sent to the external computer 130 or the like via the interface 111. Accordingly, the external computer 130 and the like are configured to receive a signal recorded on the optical disc 102 as a reproduction signal.
The signal processing unit 120 is shown in FIG. 1 as a control signal indicating that it is in a recording mode in which information is recorded on the optical disc 102 and in a playback mode in which information recorded on the optical disc 102 is reproduced. It is comprised so that it may output to the photon detection apparatus 20 shown.

Also, if the recording signal demodulated by the signal modulation and ECC block 108 is for audio / visual use, it is digital / analog converted by the D / A conversion unit of the D / A, A / D converter 112 for audio / visual processing. Supplied to the unit 113. Audio / video signal processing is performed by the audio / visual processing unit 113 and transmitted to an external imaging / projection device via the audio / visual signal input / output unit 114.
The optical pickup 104 is connected to a feed motor 105 for moving to a predetermined recording track on the optical disc 102, for example. Control of the spindle motor 103, control of the feed motor 105, and control of the focusing direction and tracking direction of the biaxial actuator that holds the objective lens of the optical pickup 104 are performed by a servo control unit 109, respectively.
That is, the servo control unit 109 controls the spindle motor 103 based on the ATIP signal, and controls the biaxial actuator based on the focus error signal and the tracking error signal.
The laser control unit 121 controls the laser light source in the optical pickup 104. In particular, in this example, the laser control unit 121 controls the emission power of the laser light source during recording and during reproduction. In recording, the output power of the laser light source is controlled based on the R-OPC signal generated from the WRF signal.

FIG. 3 is a block diagram showing an optical system of the optical pickup according to the first embodiment of the present invention.
In FIG. 3, an optical pickup 104 includes a laser light source 1, a grating element 2, a collimator lens 3, a beam splitter 4, an objective lens 5, and a light detection device 20, and these components are mounted on a holder (not shown). Configured.
Various known methods can be used for tracking error detection and focus error detection. In this example, the tracking error signal is detected by the DPP (Differential Push-Pull) method, and the focus error signal is detected. Is detected by the astigmatism (Astigma) method.

  In the optical pickup 104, the light beam emitted from the laser light source 1 passes through the grating element 2, is separated into one main beam and two side beams, passes through the collimator lens 3 and the beam splitter 4, and is supplied to the objective lens. The reflected light beam irradiated onto the optical disk 102 through 5 and reflected by the optical disk 102 is separated by the beam splitter 4 through the objective lens 5 and guided to the light detection device 20.

FIG. 1 is a circuit diagram showing a configuration of a photodetection device according to Embodiment 1 of the present invention.
As shown in FIG. 1, the light detection device 20 includes three light detection units 221 to 223 arranged linearly on the same semiconductor substrate 21 and light detection on the same semiconductor substrate 21. Eight amplifier circuits 23A to 23H, four operational amplifier circuits 24A to 24D, and a selection circuit 25 formed apart from the units 221 to 223.

The selection circuit 25 selects the amplifier circuits 23A to 23H and the operational amplifier circuits 24A to 24D necessary for recording or reproducing the optical signal from the amplifier circuits 23A to 23H and the operational amplifier circuits 24A to 24D, and controls them to the operating state. And the first selection control signals S11 to S14 for controlling the amplifier circuits 23A to 23H and the operational amplifier circuits 24A to 24D other than the selected amplifier circuits 23A to 23H and the operational amplifier circuits 24A to 24D to be inoperative. In addition, each of the amplifier circuits 23A to 23H and the operational amplifier circuits 24A to 24D is set so that the output level of each of the selected amplifier circuits 23A to 23H and the operational amplifier circuits 24A to 24D becomes a value suitable for recording or reproduction of an optical signal. A plurality of second selection control signals S21 to S24 for setting and controlling the gains separately are transmitted. The selection circuit 25 is supplied with a multi-bit command signal from the system controller 107 for sending the first and second selection control signals.
Further, a plurality of command signal input terminals for sending first and second selection control signals are supplied from the system controller 107 to the plurality of command signal input terminals provided in the selection circuit 25. Yes.
In this embodiment, the multi-bit command signal supplied from the system controller 107 to the plurality of command signal input terminals of the selection circuit 25 is a combination of binary logic signals given high / low. Of course, it may be a combination of three or more logic signals.

In FIG. 1, the central light detection unit 221 receives the main beam B1, is formed in a rectangular shape that is divided into four in a square shape, and includes four light receiving elements 22A to 22D. .
The light detection unit 222 adjacent to one side of the light detection unit 221 receives one side beam B2 of two side beams, has a rectangular shape divided into two, and the light detection unit 221. The light receiving element 22F on the near side and the light receiving element 22E on the far side from the light detection unit 221 are configured.
The light detector 223 adjacent to the other side of the light detector 221 receives the other side beam B3 of the two side beams, has a rectangular shape divided into two, and detects light. The light receiving element 22G is close to the part 221, and the light receiving element 22 is far from the light detection part 221.
The light receiving elements 22A to 22H are configured to output a current signal corresponding to the amount of received light as a detection signal. The current signals output from the light receiving elements 22A to 22H are current signals A to H, respectively. To do.

The amplification circuits 23A to 23H are configured to current-voltage convert and amplify each of the detection signals A to H output from the light receiving elements 22A to 22H corresponding thereto.
Since each of the amplifier circuits 23A to 23H has the same configuration, only the amplifier circuit 23A will be described, and the description of the configuration of the other amplifier circuits 23B to 23H will be omitted.

The amplifier circuit 23A selectively selects one of the input terminals of the OP amplifier 231, the OP amplifier 231, the two feedback resistors 232 and 233 that determine the amplification factor of the OP amplifier 231, and the two feedback resistors 232 and 233. Switch means 234 for switching connection between the output terminal and the output terminal.
The OP amplifier 231 of the amplifying circuit 23A is controlled to be activated when it is selected by the first selection control signal S11 output from the selection circuit 25 according to the recording mode or the reproduction mode, and is not operated when not selected. It is configured to be controlled by the state.
The switch means 234 is configured to be switched to the feedback resistor 232 or 233 side by the second selection control signal S21 output from the selection circuit 25 according to the recording mode or the reproduction mode.
For example, when the feedback resistor 232 is selected by the switch means 234, the amplification factor of the amplification circuit 23A becomes the recording amplification factor Aw, and when the feedback resistor 233 is selected, the amplification factor of the amplification circuit 23A becomes the reproduction amplification factor. It is configured to have a high amplification factor Ar.
Accordingly, each of the amplifier circuits 23A to 23H amplifies the detection signals A to H output from the light receiving elements 22A to 22H by current-voltage conversion. The detection signals A to H amplified by the amplifier circuits 23A to 23H are output to the signal processing unit 120.

The operational amplifier circuit 24A selectively adds one of the adders 241, the two feedback resistors 242, 243 for determining the amplification factor of the adder 241, and the two feedback resistors 242, 243. The switch means 244 is connected to be switched between the input terminal and the output terminal, and two input resistors 245A for inputting the detection signals A and D of the amplifier circuits 23A and 23D, respectively.
The operational amplifier circuit 24B has the same configuration as the operational amplifier circuit 24A. The operational amplifier circuit 24A is different from the operational amplifier circuit 24A in that the signals added by the adder of the operational amplifier circuit 24B are the signals of the amplifier circuits 23B and 23C. Detection signals B and C.
The operational amplifier circuit 24A is controlled to be activated when selected by the first selection control signal S13 output from the selection circuit 25 according to the recording mode or the reproduction mode, and is not activated when not selected. It is comprised so that it may be controlled.
The switch means 244 is configured to be switched to the feedback resistor 242 or 243 side by the second selection control signal S23 output from the selection circuit 25 according to the recording mode or the reproduction mode.
For example, when the feedback resistor 242 is selected by the switch means 244, the amplification factor of the operational amplifier circuit 24A is the recording amplification factor Asw, and when the feedback resistor 243 is selected, the amplification factor of the operational amplifier circuit 24A is the reproduction factor. It is configured to have a high amplification factor Asr.
Thereby, the operational amplifier circuit 24A adds and amplifies the detection signals A and D of the amplifier circuits 23A and 23D, and inputs the amplified signal as a WPP1 signal to the signal processing unit 120. The operational amplifier circuit 24B The detection signals B and C of 23C are added and amplified and input to the signal processing unit 120 as a WPP2 signal. In the signal processing unit 120, the difference between the WPP1 signal and the WPP2 signal is calculated and output to the servo control unit 109 as an ATIP signal.

The operational amplifier circuit 24C is for taking out a recording WRF signal. The adder 245, two feedback resistors 246 and 247 for determining the amplification factor of the adder 245, and these two feedback resistors 246 and 247. Is selectively switched between one input terminal and the output terminal of the adder 245, and four input resistors 249 for inputting the detection signals A to D of the amplifier circuits 23A to 23D, respectively. And is configured.
The operational amplifier circuit 24C is controlled to be activated when it is selected by the first selection control signal S13 output from the selection circuit 25 according to the recording mode or the reproduction mode, and is not activated when not selected. It is comprised so that it may be controlled.
The switch means 248 is configured to be switched to the feedback resistor 246 or 247 side by the second selection control signal S23 output from the selection circuit 25 according to the recording mode or the reproduction mode.
For example, when the feedback resistor 246 is selected by the switch means 248, the amplification factor of the operational amplifier circuit 24A is the recording amplification factor Asw, and when the feedback resistor 247 is selected, the amplification factor of the operational amplifier circuit 24A is the reproduction factor. It is configured to have a high amplification factor Asr.
The operational amplifier circuit 24D is for extracting an RRF signal for reproduction, and has the same configuration as the operational amplifier circuit 24C. The operational amplifier circuit 24C differs from the operational amplifier circuit 24C in that it is an adder. Is a differential type. This is because the gain of the operational amplifier circuit 24D can be kept low, so that it is easily affected by the intrusion noise, and this intrusion noise component is removed.
Accordingly, the operational amplifier circuit 24C adds and amplifies the detection signals A to D of the amplifier circuits 23A to 23D, and outputs the result as a WRF signal to the signal processing unit 120. The operational amplifier circuit 24D also outputs the amplifier circuits 23A to 24A. 23D detection signals A to D are added and amplified, and output to the signal processing unit 120 as an RRF signal.

FIG. 4 is a plan view showing a state in which the photodetector 20 having the circuit configuration shown in FIG. 1 is packaged, and FIG. 5 is a side view thereof.
4 and 5, the light detection device 20 is mounted in a package 30, and the outer periphery of the light detection device 20 is molded and packaged with a transparent resin material 31. Thereby, the reflected light beam reflected by the optical disk 102 shown in FIG. 3 and separated by the beam splitter 4 is incident on the light receiving elements 22A to 22H through the transparent resin material 31.
Further, a plurality of pins 33 for extracting output signals of the amplifier circuits 23A to 23H and a plurality of pins for extracting output signals of the operational amplifier circuits 24A to 24D are provided on the periphery of the substrate 32 constituting the package 30. 34 and a plurality of pins 35 for inputting a command signal to the selection circuit 25 are provided.

Next, the operation of the first embodiment will be described.
First, a command signal of a plurality of bits, for example, 3 bits, is supplied from the system controller 107 to the selection circuit 25 of the photodetector 20 through the three pins 35. Accordingly, the selection circuit 25 generates and transmits nine types of selection control signals corresponding to several times, for example, three times, 3 bits corresponding to the permutation combination of the bit command signals. Here, among the nine types of selection control signals, the first to fourth selection control signals are used as the first selection control signals S11 to S14, and the fifth to ninth selection control signals are used as the first selection control signals S11 to S14. 2 Used as selection control signals S21 to S25.

When the optical disk device is operated for reproducing the optical signal of the optical disk 102, the laser control unit 121 controls the light beam emitted from the laser light source 1 to be reproduced and to have a light intensity suitable for the type of the optical disk 102. . Then, the first selection control signal S11 sent from the selection circuit 25 is inputted to the amplifier circuits 23A to 23D to hold the amplifier circuits 23A to 23D in the operating state and the first selection sent from the selection circuit 25. The control signal S12 is input to the amplifier circuits 23E to 23H, and the amplifier circuits 23E to 23H are held in the operating state. Similarly, the first selection control signal S13 sent from the selection circuit 25 is input to the operational amplifier circuits 24A, 24B, and 24C, and these operational amplifier circuits 24A, 24B, and 24C are held in a non-operating state. The first selection control signal S14 sent from the selection circuit 25 is input to the operational amplifier circuit 24D, and the operational amplifier circuit 24D is held in the operating state.
In such a state, the second selection control signal S21 sent from the selection circuit 25 is input to the switch means 234 of the amplifier circuits 23A to 23D, and the switch means 234 is switched and connected to the feedback resistor 233, thereby the amplifier circuits 23A to 23D. Is set to a high gain for reproduction. Further, the second selection control signal S22 sent from the selection circuit 25 is inputted to the switch means 234 of the amplifier circuits 23E to 23H, and the switch means 234 is switched and connected to the feedback resistor 232, thereby amplifying the amplifier circuits 23E to 23H. Set the rate to a low gain gain. Further, the second selection control signal S24 sent from the selection circuit 25 is input to the switch means 244 of the operational amplifier circuit 24D, and the switch means 244 is switched and connected to the feedback resistor 243, thereby increasing the amplification factor of the operational amplifier circuit 24D. Set to a high gain for playback.

  Therefore, at the time of reproduction, the RF signal (A + B + C + D) output from the operational amplifier circuit 24D is input to the signal control unit 120 as an RRF signal, generated as a control signal necessary for servo control, and output to the servo control unit 109. The Further, the signal is input to the signal modulation and ECC block 108 through the signal control unit 120, equalized by the signal modulation and ECC block 108, binarized, and output as a demodulated signal.

When the optical disk apparatus is operated for recording an optical signal on the optical disk 102, the laser control unit 121 controls the light beam emitted from the laser light source 1 so that the light intensity is adapted to the type of recording and optical disk 102. To do. Then, the first selection control signal S11 sent from the selection circuit 25 is inputted to the amplifier circuits 23A to 23D to hold the amplifier circuits 23A to 23D in the operating state and the first selection sent from the selection circuit 25. The control signal S12 is input to the amplifier circuits 23E to 23H, and the amplifier circuits 23E to 23H are held in the operating state. Similarly, the first selection control signal S13 sent from the selection circuit 25 is input to the operational amplifier circuits 24A, 24B, and 24C, and these operational amplifier circuits 24A, 24B, and 24C are held in an operating state, and further selected. The first selection control signal S14 sent from the circuit 25 is input to the operational amplifier circuit 24D, and the operational amplifier circuit 24D is held in a non-operating state.
In this state, the second selection control signal S21 sent from the selection circuit 25 is input to the switch means 234 of the amplifier circuits 23A to 23D, and the switch means 234 is switched and connected to the feedback resistor 232 to thereby connect the amplifier circuits 23A to 23D. Is set to a low gain. Further, the second selection control signal S22 sent from the selection circuit 25 is inputted to the switch means 234 of the amplifier circuits 23E to 23H, and the switch means 234 is switched and connected to the feedback resistor 232, thereby amplifying the amplifier circuits 23E to 23H. Set the gain to a low gain without saturating the rate. Further, the second selection control signal S23 sent from the selection circuit 25 is inputted to the switch means 244 of the operational amplifier circuits 24A, 24B and 24C, and the switch means 244 is switched and connected to the feedback resistor 242 to thereby make the operational amplifier circuit 24A. , 24B and 24C are set to gains of low gain that do not saturate.

  Therefore, at the time of recording, the RF signal (A + B + C + D) output from the operational amplifier circuit 24C is input to the signal control unit 120 as a WRF signal, generated as a control signal necessary for servo control, and output to the servo control unit 109. The Further, the signal is input to the signal modulation and ECC block 108 through the signal control unit 120, and the R-OPC signal is generated by sampling the level at the pit level by the signal modulation and ECC block 108, and this is output to the laser control unit 121. Is done. Thereby, the emission power of the laser light source 1 during recording is controlled.

At the time of recording, the difference between the sum signal (A + D) of the detection signals A and D and the sum signal (B + C) of the detection signals B and C and the two sum signals is obtained and output as an ATIP signal. The ATIP signal is a wobbling detection signal having a fixed period formed by a pre-groove formed in an unrecorded CD-R, and is input to the servo control unit 109. The servo control unit 109 controls the rotation of the spindle motor 103 so that the ATIP signal has a predetermined period.
During recording and reproduction, a difference signal (A + C) − (B + D) between the sum signal of the detection signals A and C and the sum signal of the detection signals B and D is input to the servo control unit 109 as a focus error signal. The This is due to the astigmatism method.
At the time of recording and reproduction, “the difference signal (main push-pull signal) between the sum signal of the detection signals A and D and the sum signal of the detection signals B and C” is (A + D) − (B + C), When the difference signal (side push-pull signal) between the sum signal of the detection signals E and G and the sum signal of the detection signals F and H is (E + G) − (F + H), (A + D) − (B + C) -K ((E + G)-(F + H)) is input to the servo control unit 109 as a tracking error signal. This is due to the DPP method.

According to the first embodiment configured as described above, each of the light receiving elements 22 </ b> A to 22 </ b> H that receives the reflected light beam reflected by the recording surface of the optical disc 102 by the first selection control signal transmitted from the selection circuit 25. Two or more voltage signals selected from the voltage signals output from the amplifier circuits 23A to 23H and the amplifier circuits 23A to 23H connected to each other are added to output a control signal necessary for recording or reproducing the optical signal An amplifier circuit and an operational amplifier circuit necessary for recording or reproducing an optical signal are selected from the operational amplifier circuits 24A to 24D to be controlled, and these circuits are controlled to be in an operating state and other than the selected amplifier circuit and the operational amplifier circuit. The amplifier circuit and the operational amplifier circuit are controlled in a non-operating state, and each amplifier circuit and operational amplifier selected by the second selection control signal sent from the selection circuit 25 is used. Since the gain of each amplifier circuit and the operational amplifier circuit is separately set and controlled so that the output level of the path becomes a value suitable for recording or reproduction of the optical signal, the number of bits of the command input to the selection circuit 25 , The gains of the amplifier circuits 23A to 23H and the gains of the operational amplifier circuits 24A to 24D, which are multiplied by the command input bit number, can be set to the recording speed at the time of recording or the reproducing operation or the type of the optical disk 102 at the time of reproducing The number of pins required for command input to the selection circuit 25 can be reduced, and the optical pickup including the photodetection device can be miniaturized and accommodated in an existing package. Can be easily performed.
In addition, according to the first embodiment, since the amplifier circuit and the operational amplifier circuit other than the selected amplifier circuit and the operational amplifier circuit are controlled to be in the non-operating state, the operating current to the photodetector is reduced. Accordingly, it is possible to prevent the transparent mold package for packaging the photodetector from being softened or deformed by heat.

In the first embodiment, among the voltage signals output from the amplifier circuits 23A to 23H and the amplifier circuits 23A to 23H connected to the light receiving elements 22A to 22H that receive the reflected light beam reflected by the optical disc 102, respectively. In the above description, the gains of the operational amplifier circuits 24A to 24D that add two or more voltage signals selected from the above and output the control signal are separately set and controlled. However, the present invention is not limited to this, and the laser is not limited to this. A light receiving element that monitors the light amount of the light source 1 and an amplifier circuit that converts a current signal from the light receiving element into a voltage signal and outputs the voltage signal are provided, and the gain of the amplifier circuit is set by a selection control signal sent from the selection circuit 25 Can be controlled.
Further, the number of command input bits to the selection circuit 25 and the number of selection control signals sent from the selection circuit 25 are not limited to those shown in the first embodiment, and may be larger than that.

It is a circuit diagram which shows the structure of the photon detection apparatus in Example 1 of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating a configuration of an optical disc device incorporating a light detection device and an optical pickup in Embodiment 1 of the present invention. It is a block diagram which shows the optical system of the optical pick-up by Example 1 of this invention. It is a top view which shows the state which packaged the photodetector with the circuit structure shown in Example 1 of this invention. FIG. 5 is a side view of FIG. 4. It is a whole block diagram of the conventional optical pickup. It is a circuit block diagram of the conventional photodetector.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Laser light source, 5 ... Objective lens, 20 ... Photodetection device, 22A-22H ... Light receiving element, 23A-23H ... Amplifier circuit, 24A-24D ... Operational amplifier circuit, 25 ... Selection circuit, 101... Optical disk device, 102... Optical disk, 104.

Claims (12)

A light detection device including a plurality of light receiving elements that receive reflected light beams reflected by the optical recording medium when recording and / or reproducing by irradiating the optical recording medium with a light beam,
A plurality of amplifier circuits provided in each of the plurality of light receiving elements, each of which converts a current signal from each of the light receiving elements into a voltage signal and outputs the voltage signal;
A plurality of operational amplifier circuits for adding two or more voltage signals selected from the voltage signals output from the plurality of amplifying means and outputting a control signal necessary for recording or reproducing an optical signal;
The amplifier circuit and the operational amplifier circuit necessary for recording or reproducing the optical signal are selected from the plurality of amplifier circuits and the operational amplifier circuit to control the operation state, and amplification other than the selected amplifier circuit and the operational amplifier circuit is performed. A first selection control signal for controlling the circuit and the operational amplifier circuit to be in a non-operating state, and the output level of each of the selected amplifier circuit and the operational amplifier circuit becomes a value suitable for recording or reproduction of an optical signal. And a selection circuit for sending a plurality of second selection control signals for separately setting and controlling the gains of the respective amplification circuits and operational amplification circuits in a plurality of stages ,
The selection circuit includes a plurality of command signal input terminals,
The selection circuit is configured to generate the first and second selection control signals by a combination of binary logic signals given at high / low applied to the command signal input terminals,
The light receiving element, the amplifier circuit, the operational amplifier circuit, the selection circuit, and the plurality of command signal input terminals are formed on the same semiconductor substrate.
An optical detection device characterized by that.   A light receiving element that monitors the light amount of the light source that emits the light beam; and an amplification circuit that converts a current signal from the light receiving element into a voltage signal and outputs the voltage signal, and the gain of the amplification circuit is sent from the selection circuit. The photodetection device according to claim 1, wherein the photodetection device is configured to be set by a selection control signal.   The photodetection device according to claim 1, wherein the control signal includes at least one of a tracking error signal and a focus error signal.   The light receiving elements include a first light receiving element group including four light receiving elements arranged in a square shape, and second and third light receiving elements disposed so as to sandwich the first light receiving element group. And each of the second and third light receiving element groups includes a light receiving element located on a side closer to the first light receiving element group, and a light receiving element located on a side far from the first light receiving element group. The light detection device according to claim 1, comprising: two light receiving elements. A light source that emits a light beam for recording and / or reproduction; an objective lens that collects the light beam emitted from the light source and irradiates the optical recording medium; and An optical pickup comprising a light detection device including a plurality of light receiving elements that receive a reflected light beam through the objective lens,
The photodetector is
A plurality of amplifier circuits provided in each of the plurality of light receiving elements, each of which converts a current signal from each of the light receiving elements into a voltage signal and outputs the voltage signal;
A plurality of operational amplifier circuits for adding two or more voltage signals selected from the voltage signals output from the plurality of amplifying means and outputting a control signal necessary for recording or reproducing an optical signal;
The amplifier circuit and the operational amplifier circuit necessary for recording or reproducing the optical signal are selected from the plurality of amplifier circuits and the operational amplifier circuit to control the operation state, and amplification other than the selected amplifier circuit and the operational amplifier circuit is performed. A first selection control signal for controlling the circuit and the operational amplifier circuit to be in a non-operating state, and the output level of each of the selected amplifier circuit and the operational amplifier circuit becomes a value suitable for recording or reproduction of an optical signal. And a selection circuit for sending a plurality of second selection control signals for separately setting and controlling the gains of the respective amplification circuits and operational amplification circuits in a plurality of stages ,
The selection circuit includes a plurality of command signal input terminals,
The selection circuit is configured to generate the first and second selection control signals by a combination of binary logic signals given at high / low applied to the command signal input terminals,
The light receiving element, the amplifier circuit, the operational amplifier circuit, the selection circuit, and the plurality of command signal input terminals are formed on the same semiconductor substrate.
An optical pickup characterized by that. A light receiving element that monitors the light amount of a light source that emits the recording and / or reproducing light beam, and an amplifier circuit that converts a current signal from the light receiving element into a voltage signal and outputs the voltage signal, and the gain of the amplifier circuit is 6. The optical pickup according to claim 5 , wherein the optical pickup is configured to be set by a selection control signal sent from the selection circuit. 6. The optical pickup according to claim 5 , wherein the control signal includes at least one of a tracking error signal and a focus error signal. The light receiving elements include a first light receiving element group including four light receiving elements arranged in a square shape, and second and third light receiving elements disposed so as to sandwich the first light receiving element group. And each of the second and third light receiving element groups includes a light receiving element located on a side closer to the first light receiving element group, and a light receiving element located on a side far from the first light receiving element group. The optical pickup according to claim 5 , comprising: two light receiving elements. Driving means for holding and rotating the optical recording medium;
An optical disc apparatus comprising: an optical pickup that irradiates a recording and / or reproducing light beam to an optical recording medium that is rotationally driven by the driving means, and detects a reflected light beam from the optical recording medium;
The optical pickup is
A light source for emitting the recording and / or reproducing light beam;
An objective lens that condenses the light beam emitted from the light source and irradiates the optical recording medium;
A light detection device comprising a plurality of light receiving elements for receiving the reflected light beam of the irradiated light beam on the optical recording medium via the objective lens;
The photodetector is
A plurality of amplifier circuits provided in each of the plurality of light receiving elements, each of which converts a current signal from each of the light receiving elements into a voltage signal and outputs the voltage signal;
A plurality of operational amplifier circuits for adding two or more voltage signals selected from the voltage signals output from the plurality of amplifying means and outputting a control signal necessary for recording or reproducing an optical signal;
The amplifier circuit and the operational amplifier circuit necessary for recording or reproducing the optical signal are selected from the plurality of amplifier circuits and the operational amplifier circuit to control the operation state, and amplification other than the selected amplifier circuit and the operational amplifier circuit is performed. A first selection control signal for controlling the circuit and the operational amplifier circuit to be in a non-operating state, and the output level of each of the selected amplifier circuit and the operational amplifier circuit becomes a value suitable for recording or reproduction of an optical signal. And a selection circuit for sending a plurality of second selection control signals for separately setting and controlling the gains of the respective amplification circuits and operational amplification circuits ,
The selection circuit includes a plurality of command signal input terminals,
The selection circuit is configured to generate the first and second selection control signals by a combination of binary logic signals given at high / low applied to the command signal input terminals,
The light receiving element, the amplifier circuit, the operational amplifier circuit, the selection circuit, and the plurality of command signal input terminals are formed on the same semiconductor substrate.
An optical disc device characterized by the above. A light receiving element that monitors the light quantity of a light source that emits a light beam for recording and reproducing an optical signal to and from the optical recording medium, and an amplifier circuit that converts a current signal from the light receiving element into a voltage signal and outputs the voltage signal 10. The optical disc apparatus according to claim 9, wherein the gain of the amplifier circuit is set by a selection control signal sent from the selection circuit. 10. The optical disc apparatus according to claim 9 , wherein the control signal includes at least one of a tracking error signal and a focus error signal. The light receiving elements include a first light receiving element group including four light receiving elements arranged in a square shape, and second and third light receiving elements disposed so as to sandwich the first light receiving element group. And each of the second and third light receiving element groups includes a light receiving element located on a side closer to the first light receiving element group, and a light receiving element located on a side far from the first light receiving element group. 10. The optical disk device according to claim 9 , wherein the optical disk device is configured by two light receiving elements.

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