JP2006134387A - Photodetecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photodetecting device inexpensively by decreasing the number of output signal lines from a photodetecting element and an electric converting circuit, such as an I/V converting circuit, provided in a movable portion. <P>SOLUTION: The photodetecting device is provided with a plurality of sets of photodetecting elements 117 and I/V converting circuits 118, each converting light detected by a photodetecting element into an electric signal and outputting it, in the movable portion according to lights mutually different in wavelength bands. The photodetecting device is characterized in that outputs da, db, and dc of the electric converting circuits of the plurality of sets are put together into one wiring line and the device is equipped with a control portion 109 which places output sides of I/V converting circuits of sets except one set in a high-impedance state when the I/V converting circuit 118 of the one set converts light detected by the photodetecting element into an electric signal and outputs it. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  According to the present invention, a plurality of sets of light detection elements and electric conversion circuits that convert the light detected by the light detection elements into electric signals and output the light signals are provided in the movable portion corresponding to light in different wavelength ranges. The present invention relates to a light detection device.

  In recent years, various digital recording media have been developed. Among the digital recording media, the optical disc recording / reproducing apparatus using the optical disc is currently attracting the most attention and has been rapidly spread for household music, video recording, viewing and the like. The optical disk device reflects the light emitted from the light source of the semiconductor laser to the optical disk medium, and the reflected light is received by the photodetector, thereby detecting the reflectance change and phase difference change of the information pits recorded on the optical disk. To do. The amount of information recorded on the optical disc becomes larger as the information pit becomes smaller. Therefore, for high-density recording, it is most effective to make the wavelength of the semiconductor laser shorter. For example, an infrared semiconductor laser having a wavelength near 780 nm is used for CD recording / reproduction. For DVD recording / reproduction with a further improved recording density, a red semiconductor laser of around 650 nm is used. Further, in a BD (Bru-Ray Disc) having a higher recording density than a DVD, use of a blue-violet semiconductor laser having a wavelength of about 400 nm is planned.

As described above, although the capacity of the optical disk has been increased with the shortening of the wavelength of the semiconductor laser, the demand for a low-capacity CD or DVD will not be lost even if a larger capacity optical disk apparatus appears. . Therefore, a user desires an optical disc apparatus that can record and reproduce a plurality of optical discs such as a CD, a DVD, and a BD by a single unit. Conventionally, Patent Document 1 discloses a configuration of an optical pickup having a detection light receiving element for both CD and DVD.
JP-A-8-55363

  By the way, in the optical disk apparatus, the photodetector outputs a current corresponding to the light intensity by receiving the reflected light from the optical disk medium, and converts it into a voltage signal using an electric conversion circuit such as an I / V conversion circuit. To do. The light-current conversion efficiency of the photodetector varies depending on the wavelength of the light source. For example, in a specific photodetector, the conversion efficiency for a wavelength of 780 nm is 0.5 A / W, the conversion efficiency for a wavelength of 650 nm is 0.4 A / W, and the conversion efficiency for a wavelength of 400 nm is 0.3 A / W. Is called spectral sensitivity. Therefore, in consideration of more efficiently converting light into a voltage signal, it is desirable to dedicate a photodetector with optimized sensitivity for each light source.

  It is also difficult to receive the reflected light from the optical disc with a photo detector having a common configuration and a common arrangement. From the viewpoint of optical design, it is desirable to receive reflected light with a photodetector optimally arranged for each light source.

  However, in the optical disc apparatus, the photodetector and the I / V conversion circuit are arranged on an optical pickup which is a movable part. In recent years, the photodetector and the I / V conversion circuit are often integrated (monolithic) due to restrictions on the signal S / N and frequency characteristics. On the other hand, a reproduction signal processing circuit that performs reproduction signal processing such as waveform equalization and AD conversion of a reproduction signal is generally large and difficult to mount on an optical pickup. Is arranged.

  Therefore, an FPC (flexible cable) or the like is used for transmission of the voltage signal from the optical pickup which is a movable part to the reproduction signal processing circuit. When a plurality of sets of photodetectors and I / V conversion circuits are provided corresponding to a plurality of light sources, the number of FPC signal lines for transmitting the voltage output of each I / V conversion circuit to the reproduction signal processing circuit increases. There is a problem. Furthermore, since the reproduction signal processing circuit has recently been composed of a one-chip LSI, the number of LSI input terminals also increases by the number of light sources, leading to an increase in the cost of the entire apparatus.

  In view of the above problems, the present invention provides a light detection device at a low cost by reducing the number of output signal lines from a light detection element provided in a movable part and an electrical conversion circuit such as an I / V conversion circuit. The purpose is to do.

  In order to solve the above-described problems, a light detection device according to the present invention includes a light detection element and an electric conversion circuit that converts light detected by the light detection element into an electric signal and outputs the electric signal. A plurality of sets of light detection devices provided in the movable portion corresponding to light, wherein outputs of the plurality of sets of electrical conversion circuits are combined into one wiring, and the light detection element is included in one set of the plurality of sets. When the electrical conversion circuit converts the detected light into an electrical signal and outputs the electrical signal, the controller includes a control unit that puts the output side of the electrical conversion circuit in the plurality of sets other than the set into a high impedance state. To do.

  According to the present invention, it is possible to provide a light detection device at a low cost by reducing the number of light detection elements provided in the movable portion and the number of output signal lines from the electrical conversion circuit.

  In the photodetecting device according to the present invention, the photodetecting element and the electrical conversion circuit that converts the light detected by the photodetecting element into an electrical signal and outputs the electrical signal are provided in the movable part corresponding to light in different wavelength ranges. A plurality of sets of light detection devices, wherein outputs of the plurality of sets of electrical conversion circuits are combined into one wiring, and light detected by the light detection element in one set of the plurality of sets is converted into the electrical conversion circuit. Is configured to include a control unit that puts the output side of the electrical conversion circuit in the group other than the set in a high impedance state when the signal is converted into an electrical signal and output.

  As a result, a plurality of sets of light detection elements and output signal lines from the electric conversion circuit provided in the movable part are combined into one wiring, so that the number of output signal lines from the movable part can be reduced, and low A photodetection device can be provided at low cost. In addition, when the electrical conversion circuit converts the light detected by the light detection element in one set of the plurality of sets into an electrical signal and outputs the electrical signal, the output side of all the electrical conversion circuits other than the electrical conversion circuit is output. By setting the high impedance state, it is possible to individually detect light in different wavelength ranges.

  Examples of the light detection element include a light detection element that receives infrared light, a light detection element that receives red light, and a light detection element that receives blue light or blue-violet light. Here, infrared light refers to light having a wavelength of 700 nm to 800 nm. Red light refers to light having a wavelength of 600 nm to 700 nm. Furthermore, blue light or blue-violet light refers to light having a wavelength of 400 nm to 550 nm.

  Further, in the light detection device according to the above configuration, the movable part is an optical pickup, and the optical pickup includes a plurality of light emitting elements that emit light in different wavelength ranges, and the plurality of sets of light detection elements It is preferable to further include an optical system for guiding light emitted from any one of the plurality of light emitting elements and reflected by the optical disc. Furthermore, a light intensity detection circuit that receives direct light or reflected light from each of the plurality of light emitting elements in the optical pickup, detects the intensity of light emitted from the light emitting elements, and outputs a light intensity detection signal. A plurality of the light intensity detection circuits are integrated into one wiring, and when the control unit outputs the light intensity detection signal when one of the plurality of light intensity detection circuits outputs the light intensity detection circuit, It is preferable to set the output side of all the light intensity detection circuits to a high impedance state.

Hereinafter, more specific embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
A photodetecting device according to a first exemplary embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a block diagram showing a configuration of a light detection device (optical disc device) according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing an internal configuration of the optical pickup 103 of FIG. 1 according to the present embodiment. FIG. 3 is a block diagram showing an internal configuration of the reproduction signal detector 105a of FIG. 2 according to the present embodiment.

  As shown in FIG. 1, the light detection device according to the present embodiment includes a spindle motor 102 and an optical pickup 103. The light detection apparatus further includes a laser power control unit 110, a focus tracking servo unit 106, an address detection unit 107, a data reproduction unit 108, and a control unit 109.

  The spindle motor 102 rotates the optical disc 101. The optical pickup 103 includes a laser driver 104, a reproduction signal detector 105, and a laser power photodetector 111, in addition to an optical part such as an objective lens and a hologram. Based on the driver control signal a, the optical pickup 103 causes the semiconductor laser 112 to emit light by the semiconductor laser driving current supplied from the laser driver 104 and irradiates the optical disc 101. The emitted light of the semiconductor laser 112 is received by the laser power photodetector 111 and returned to the laser power control unit 110 as a laser power detection signal b. The laser power control unit 110 controls the driver control signal a based on the laser power detection signal b so that the emission power of the semiconductor laser 112 becomes constant. The photodetector control signal c controls the state of the reproduction signal detector 105 and the laser power photodetector 111.

  The optical pickup 103 irradiates the optical disc 101 with weak reproduction power, detects reflected light that changes based on the pit information recorded on the optical disc 101, and outputs it as a reproduction signal d. To do. The reproduction signal d is supplied to the focus tracking servo unit 106 and calculated as servo information f by the control unit 109 to control the focus and tracking state of the optical pickup 103. The reproduction signal d is also sent to the address detection unit 107 and the data reproduction unit 108. The address detection unit 107 detects the address information g on the optical disc 101 and supplies it to the control unit 109. The data reproducing unit 108 detects user data information h recorded on the optical disc 101 and supplies it to the control unit 109.

  Since the optical pickup 103 needs to move in the radial direction of the optical disc 101, the optical pickup 103 is configured as a movable body movable with respect to the drive housing. On the other hand, the laser power control unit 110, the focus tracking servo unit 106, the address detection unit 107, the data reproduction unit 108, the control unit 109, and the like are created by, for example, an LSI and are fixed to the drive housing. A flexible cable (not shown) or the like is bent between the optical pickup 103, which is a movable body, and the control unit 109 and the like fixed to the drive housing in order to exchange signals a to d between them. Possible cables are routed.

  Although not shown in FIG. 1, the optical pickup 103 further includes an objective lens 114 and a reflection element group 113 as shown in FIG. Similarly, as shown in FIG. 2, in the optical pickup 103, as the semiconductor laser 112, three semiconductor lasers 112 a, 112 b, and 112 c that emit laser beams having different wavelength ranges are provided. The laser driver 104 causes these semiconductor lasers 112a, 112b, and 112c to emit light. In the optical pickup 103, three reproduction signal detectors 105 (reproduction signal detectors 105a, 105b, and 105c) are provided as shown in FIG. The reflection element group 113 includes an incident-side reflection element group 113a that reflects the light emitted from the semiconductor lasers 112a, 112b, and 112c toward the optical disc 101, and a return signal from the optical disc 101 as reproduction signal detectors 105a, 105b, And an exit-side reflecting element group 113b that reflects toward 105c.

  As shown in FIG. 2, the reproduction signal detector 105a includes a photodetector (light detection element) 117a and an I / V conversion circuit 118a that converts the detected current from the photodetector 117a into a voltage. Although not shown in FIG. 2, the reproduction signal detector 105a includes a plurality of I / V conversion circuits 118a depending on the number of divisions of the light receiving surface in the photodetector 117a. Similarly, the reproduction signal detector 105b includes a plurality of I / V conversion circuits 118b according to the number of divisions of the light receiving surface in the photodetector 117b, and the reproduction signal detector 105c determines the number of divisions of the light reception surface in the photodetector 117c. Accordingly, a plurality of sets of I / V conversion circuits 118c are provided. The outputs (reproduction signals da, db, dc) of the I / V conversion circuits 118a, 118b, 118c are collected into one wiring.

  In this embodiment, as an example, the semiconductor laser 112a has a wavelength of about 780 nm for CD recording / reproduction, the semiconductor laser 112b has a wavelength of about 650 nm for DVD recording / reproduction, and the semiconductor laser 112c has a wavelength for BD recording / reproduction. Are irradiated with laser light of around 400 nm. The light emitting device according to the present invention is not limited to a semiconductor laser.

  By turning on and off the drive currents to the three semiconductor lasers 112a, 112b, and 112c by the laser driver 104, the semiconductor lasers 112a, 112b, and 112c can selectively emit light. Laser light emitted from each semiconductor laser is focused on the surface of the optical disk 101 by the incident-side reflecting element group 113a and the objective lens 114, and reflected from the optical disk 101. At this time, the reflectance difference and phase difference information of the pit information recorded on the optical disc 101 is reflected in the reflected light. The reflected light passes through the objective lens 114 and is guided to one of the reproduction signal detectors 105a, 105b, and 105c according to the wavelength by the exit-side reflecting element group 113b that reflects light in a predetermined wavelength range, Light is received by the photodetector.

  The photo detector control signal c is supplied from the control unit 109 to each of the reproduction signal detectors 105a to 105c as a CD photo detector control signal ca, a DVD photo detector control signal cb, and a BD photo detector control signal cc. The operation / non-operation state of each reproduction signal detector is controlled. Here, the operating state indicates a state in which reflected light from the optical disc 101 is detected and output as a voltage signal, and the non-operating state means that the output is not output even if the reflected light is received, and the output is electrically open. To do.

  For example, when reproducing a CD, the laser driver 104 drives a semiconductor laser 112a that emits light with a wavelength near 780 nm for CD, and emits light with a wavelength near 650 nm for DVD. The driving of the semiconductor laser 112c that emits light having a wavelength near 400 nm is stopped. At this time, the control unit 109 instructs the reproduction state detector 105a for CD among the photodetector control signal c to operate in the CD reproduction signal detector 105a, and the DVD photodetector control signal cb, The BD photodetector control signal cc is set so as to instruct the DVD and BD reproduction signal detectors 105b and 105c to be in a non-operating state (that is, an electrically open output state). As a result, the reproduction signals da, db, and dc are in a short state on the wiring, but only the reproduction signal output from the reproduction signal detector 105a for CD is transmitted to the subsequent circuit during CD recording / reproduction. Become.

  Similarly, when reproducing a DVD, the laser driver 104 drives the semiconductor laser 112b that emits light having a wavelength near 650 nm for DVD, and stops driving the semiconductor lasers 112a and 112c for CD and BD. To do. Furthermore, among the photodetector control signals c, the DVD photodetector control signal cb instructs the DVD reproduction signal detector 105b to operate, and the CD and BD reproduction signal detectors 105a. , 105c, a non-operation state is commanded.

  When reproducing the BD, the laser driver 104 drives the BD semiconductor laser 112c, and stops driving the CD and DVD semiconductor lasers 112a and 112b. Further, of the photodetector control signal c, the BD photodetector control signal cc instructs the BD reproduction signal detector 105c to operate, and the CD and DVD reproduction signal detectors 105a. , 105b, a non-operating state is commanded.

  In FIG. 2, for simplicity of explanation, each of the reproduction signal detectors for CD, DVD, and BD is shown as a one-channel detector, but an actual reproduction signal detector is composed of a plurality of channels. is there. Here, the configuration of the reproduction signal detector 105 will be described in more detail with reference to FIG. FIG. 3 shows the configuration of the reproduction signal detector 105a of the reproduction signal detector 105, but the configurations of the reproduction signal detectors 105b and 105c are the same as this.

As shown in FIG. 3, the reproduction signal detector 105a includes a plurality of sets of photo detectors 117a and I / V conversion circuits 118a, that is, photo detectors 117a _{1 to} 117a ₆ and I / V conversion circuits 118a _{1 to} 118a ₆ and an addition circuit. 119, a polarity inversion buffer circuit 120, and a positive polarity buffer circuit 121, and outputs 8-channel signals da _{1 to} da ₈ . Further, the reproduction signal detector 105a includes an analog switch 116 immediately before the output of each of the signals da _{1 to} da ₈ . The short / open of the analog switch 116 is controlled by the CD photodetector control signal ca.

  Thus, for example, during CD reproduction, the control unit 109 causes the reproduction signal detector 105a to be in an operating state by shorting the analog switch 116 of the reproduction signal detector 105a with the CD photodetector control signal ca. At the same time, the control unit 109 opens the analog switches of the reproduction signal detectors 105b and 105c with the DVD photodetector control signal cb and the BD photodetector control signal cc, thereby opening the reproduction signal detectors 105b and 105c. Is inactive.

  Further, at the time of reproducing a DVD or BD, the control unit 109 opens the analog switch 116 of the reproduction signal detector 105a with the CD photodetector control signal ca, so that the reproduction signal detector 105a becomes inoperative. .

  In the present embodiment, the analog switch 116 is exemplified as the circuit element for controlling the operation / non-operation of the reproduction signal detectors 105a, 105b, and 105c. However, other circuit elements may be used.

  The reproduction signal output from the reproduction signal detector 105 as described above is sent to the focus tracking servo unit 106 (see FIG. 1). The focus tracking servo unit 106 obtains focus information by performing, for example, the calculation shown in Expression (1).

(Da ₁ + da ₃ ) − (da ₂ + da ₄ ) Formula (1)
Further, the focus tracking servo unit 106 obtains tracking information by performing a calculation shown in, for example, Expression (2). In Equation (2), K is a coefficient.

(Da ₃ + da ₄ ) − (da ₁ + da ₂ ) −K (da ₅ + da ₆ ) Formula (2)
The obtained focus information and tracking information are sent to the control unit 109 as servo information f. The control unit 109 outputs a photodetector control signal c based on the servo information f, and controls the states of the reproduction signal detector 105 and the laser power photodetector 111.

The data reproducing unit 108 (see FIG. 1) acquires the signals da ₇ and da ₈ and performs the calculation shown in, for example, Expression (3) to acquire the user data information h. Signals da ₇ and da ₈ are addition signals of detection signals da ₁ , da ₂ , da ₃ , and da ₄ , and only the polarity is inverted. The user data information h is used for reproducing user data.

da ₇ -da ₈ formula (3)
The address detector 107 (see FIG. 1) also acquires the signals da ₇ and da ₈ and uses them to detect the address information g. For example, the address information g can also be detected by the calculation shown in Expression (4). The address information g is output to the control unit 109 and used for control.

(Da ₃ + da ₄ ) − (da ₁ + da ₂ ) Formula (4)
Note that the arithmetic expressions for acquiring focus information, tracking information, servo information, address information, and user data information are not limited to the above-described example.

As described above, in this example, _eight detection signal outputs da _{1 to} da ₈ are necessary for detecting a reproduction signal for CD. A similar detection function is required for DVD and BD. Therefore, the output of the reproduction detection signal d transmitted from the optical pickup 103, which is a movable part, to a fixed unit such as the focus tracking servo unit 106, the address detection unit 107, and the data reproduction unit 108 is 24 in total. However, in this embodiment, as shown in FIG. 4, since the outputs of the reproduction signal detectors 105a, 105b, and 105c are combined into one wiring, the number of signal lines output from the optical pickup 103 is da ₁ to. The total number of da ₈ is 8.

  As described above, according to the configuration of the present embodiment, the output signal lines of the reproduction signal detectors 105a to 105c for detecting the reproduction signal from the optical disc 101 are coupled to each other on the wiring, so that the light that is the movable part The number of signal lines from the pickup 103 to the housing can be reduced. Furthermore, when the focus tracking servo unit 106, the address detection unit 107, the data reproduction unit 108, and the like are configured by LSI, the number of reproduction signal input pins can be reduced.

  In the present embodiment, the configuration in which the reproduction signal detector is provided for each of the CD, the DVD, and the BD has been described. However, the present invention is not limited to this example. For example, a configuration is possible in which CD and DVD are detected by one reproduction signal detector and only BD is received by another reproduction signal detector.

In the present embodiment, an example in which the number of reproduction signals output from the reproduction signal detector is eight has been described, but the number of reproduction signals is arbitrary.
(Embodiment 2)
In the first embodiment described above, the output signal lines of the reproduction signal detectors 105a to 105c for detecting the reproduction signal from the optical disc 101 are coupled to each other on the wiring, but the optical disc apparatus according to the present embodiment is In this configuration, output signal lines of a laser power photodetector 111 for detecting the power of light emitted from the semiconductor laser 112 are coupled to each other on the wiring. In the optical disk apparatus according to the present embodiment, the reproduction signal detector 105 preferably has a configuration in which output signal lines are coupled to each other on the wiring as shown in FIGS. 2 to 4 in the first embodiment. .

  FIG. 5 shows a schematic configuration of a laser power detection system of the light detection apparatus (optical disk apparatus) according to the present embodiment. The optical pickup 103 of this embodiment includes a CD photodetector 111a, a DVD photodetector 111b, and a BD photodetector 111c as the laser power photodetector 111. Light emitted from the semiconductor lasers 112a, 112b, and 112c is reflected by the reflecting elements 115a, 115b, and 115c provided in the optical pickup 103, and is incident on the laser power photodetectors 111a, 111b, and 111c.

  The laser power photodetectors 111a, 111b, and 111c include photodetectors 123a, 123b, and 123c, and I / V conversion circuits 124a, 124b, and 124c that convert detected currents from these photodetectors into a voltage. Thus, the laser power photodetectors 111a, 111b, and 111c output laser power detection signals ba, bb, and bc having a voltage proportional to the power of the received laser beam to the laser power control unit 110.

  The laser power photodetectors 111a, 111b, and 111c include analog switches 122a, 122b, and 122c, respectively, immediately before the outputs of the signals ba, bb, and bc. Then, the control unit 109 switches between short / open of the analog switches 122a, 122b, and 122c by the CD photodetector control signal cd, the DVD photodetector control signal ce, and the BD photodetector control signal cf. The operation / non-operation of the laser power photodetectors 111a, 111b, and 111c is controlled. For example, when playback or recording on a CD is selected, the control unit 109 causes the analog switch 122a to be short-circuited by the CD photodetector control signal cd, and controls the DVD photodetector control signal ce and the BD photodetector. By opening the analog switches 122b and 122c with the signal cf, only the CD laser power detector 111a is brought into an operating state, and the DVD and BD laser power detectors 111b and 111c are brought into a non-operating state.

  The laser power control unit 110 controls the laser driver 104 with the driver control signal a so that the laser power detection signal b becomes a predetermined voltage. The laser power applied to the optical disk 101 can be optimized by the laser driver 104 controlling the light emission power of the semiconductor laser 112 in accordance with the driver control signal a.

  As described above, according to the configuration of the present embodiment, the output signal lines of the laser power photodetector 111 for detecting the power of the emitted light from the semiconductor laser 112 are coupled to each other on the wiring, so that the movable portion The number of signal lines from a certain optical pickup 103 to the housing can be reduced. Furthermore, when the laser power control unit 110 is configured by an LSI, the number of pins for inputting a laser power detection signal can be reduced.

  In each of the above-described embodiments, the optical disk apparatus corresponding to CD, DVD, and BD is exemplified. However, the present invention can also be applied to optical disk apparatuses corresponding to other disks. Further, the semiconductor laser is not limited to the wavelength range shown in the present embodiment, and for example, an ultraviolet light source can be used. Further, although the configuration using the analog switch as the circuit element for controlling the operation / non-operation in FIGS. 3 and 5 has been described, the present invention can be applied to any circuit provided with a function for switching operation / non-operation.

  The present invention is useful as a light detection device for detecting signals from a plurality of types of optical discs using a plurality of types of light sources.

It is a block diagram which shows the structure of the photon detection apparatus concerning the 1st and 2nd embodiment of this invention. 1 is a block diagram showing a configuration of an optical pickup according to a first embodiment of the present invention. It is a block diagram which shows the structure of the reproduction | regeneration signal photodetector concerning the 1st Embodiment of this invention. It is explanatory drawing showing transmission of the reproduction signal concerning the 1st Embodiment of this invention. It is a block diagram which shows the structure of the optical pick-up concerning the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Optical disk 102 Spindle motor 103 Optical pick-up 104 Laser driver 105 Reproduction signal detector 106 Focus tracking servo part 107 Address detection part 108 Data reproduction part 109 Control part 110 Laser power control part 111 Laser power photodetector 112 Semiconductor laser 113 Reflective element 114 Objective lens 116 Analog switch 117 Photo detector 118 I / V conversion circuit 119 Adder circuit 119
120 polarity inversion buffer circuit 121 positive polarity buffer circuit

Claims (6)

A photodetecting device in which a plurality of sets of photodetecting elements and electric conversion circuits that convert the light detected by the photodetecting elements into electric signals and output the signals are provided in the movable part corresponding to light in different wavelength ranges. There,
The outputs of the plurality of sets of electrical conversion circuits are combined into one wiring,
When the electric conversion circuit converts the light detected by the light detection element in one of the plurality of sets into an electric signal and outputs the electric signal, the output side of the electric conversion circuit in the other sets other than the set is set to high. A photodetection device comprising a control unit for setting an impedance state. The light detection device according to claim 1, wherein one set of the light detection elements among the plurality of sets receives infrared light. The light detection device according to claim 1, wherein one set of the light detection elements among the plurality of sets receives red light. The light detection device according to claim 1, wherein one set of the light detection elements among the plurality of sets receives blue light or blue-violet light. The movable part is an optical pickup;
The optical pickup includes a plurality of light emitting elements that emit light in different wavelength ranges,
5. The optical system according to claim 1, further comprising an optical system that guides light emitted from any one of the plurality of light emitting elements and reflected by the optical disc, to each of the plurality of sets of light detecting elements. The light detection device according to one item. The optical pickup includes a plurality of light intensity detection circuits that receive direct light or reflected light from each of the plurality of light emitting elements, detect the intensity of light emitted from the light emitting elements, and output a light intensity detection signal. ,
The output of the light intensity detection circuit is combined into one wiring,
The control unit sets the output side of all the light intensity detection circuits other than the light intensity detection circuit to a high impedance state when one of the plurality of light intensity detection circuits outputs the light intensity detection signal. Item 6. The light detection device according to Item 5.

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