JP2010010604A - Light receiver, and light receiving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light receiver capable of suppressing noise due to electromagnetic wave while suppressing a shield member from interfering reception of an optical signal. <P>SOLUTION: The light receiver 2 is formed by covering an approximately hemispherical light receiving element 21 with an electrostatic shielding coil 22. The electrostatic shielding coil 22 is a coil-shaped member formed of a metal winding wire, and is a shield member for electrostatically shielding the light receiving element 21 from the electromagnetic wave which generates the noise. The electrostatic shielding coil 22 has a coil shape, and thus has opening parts at both end parts, and one of the opening parts 23 faces to a cover side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light receiver that receives an optical signal, and relates to a light receiver that suppresses a shield member from becoming an obstacle to receiving an optical signal. The present invention also relates to a light receiving device using such a light receiver.

  In recent years, it has become common to use a light receiving device including a light receiver that receives light such as infrared rays as a light receiving device of a wireless microphone system used in loudspeaker broadcasting facilities, karaoke, and the like. This is because light rarely reaches the outside of a room partitioned by walls or the like like radio waves, so that it is possible to suppress interference that tends to occur when radio wave type wireless microphones are used simultaneously in many rooms. In this light receiving device, a light receiver using a photodiode as a light receiving element is widely used. This is because such a photodiode is inexpensive as a light receiving element and is easy to use for general purposes.

  Since the high impedance circuit for amplifying the signal received by the photodiode has low noise resistance and is easily affected by electromagnetic waves, it is necessary to provide a shield member for electrostatic shielding around the photodiode. Therefore, for example, a shield member is used in which a photodiode is covered with a box-shaped shield metal having an opening on the light receiving surface, and a metal mesh is attached to the opening. However, since this shield member covers the entire photodiode except the light receiving opening with a shield metal, only the optical signal incident from the opening can be received by the photodiode, and the incident direction of the optical signal that can be received by the photodiode Is limited, and the amount of light reaching the light receiving element in the shadow of the shield metal is reduced. In addition, a shield member in which a box-shaped shield metal having an opening is formed and a metal mesh is attached to the opening is laborious to manufacture and increases in cost.

Thus, a technique using a coil-shaped shield member provided so as to cover the photodiode has been proposed (see, for example, Patent Document 1). According to this method, since the photodiode is covered with the wire processed into a coiled coil shape, the incident angle of the optical signal is not limited, and accordingly, the light receiving area of the infrared light receiving element is expanded. .
Japanese Patent Laid-Open No. 11-118594

  However, even when the coiled shield member according to Patent Document 1 is used, if the winding of the coiled shield member is dense, the shield member itself can be an obstacle to optical signal reception. In particular, as shown in FIG. 2 described in Patent Document 1, an iron plate is attached to the upper part of the coil part to improve the shielding characteristics against electromagnetic noise from the upper part of the infrared light receiving element, or is shown in FIG. As described above, when a spiral-shaped portion is generated by a wire on the upper portion of the coiled coil-shaped portion to enhance the shielding characteristics against electromagnetic noise from the upper portion of the infrared light receiving element, it becomes a further obstacle to optical signal reception. it is conceivable that.

  The present invention has been made in view of such circumstances, and provides a light receiver capable of effectively suppressing noise due to electromagnetic waves while suppressing the shielding member from becoming an obstacle to reception of an optical signal. Objective.

  The light receiver according to the present invention includes a light receiving element that receives an optical signal and a coil-shaped metal winding covering the light receiving element, and the light receiving element from electromagnetic waves that generate noise that interferes with reception of the optical signal. It is a light receiver provided with the electrostatic shielding coil for electrostatically shielding. The opening of the electrostatic shielding coil is directed in the incident direction of the optical signal with respect to the light receiving element.

  According to the above configuration, since the opening of the electrostatic shielding coil is directed in the incident direction of the optical signal with respect to the light receiving element, there is no metal winding constituting the electrostatic shielding coil in the incident direction. Therefore, it is possible to effectively suppress noise due to electromagnetic waves while suppressing the electrostatic shielding coil from obstructing reception of the optical signal.

  In addition, since the said light receiver is a light receiver provided with the electrostatic shielding coil for electrostatically shielding a light receiving element from the electromagnetic waves which generate | occur | produce the noise which becomes obstructive in reception of an optical signal, it becomes obstructive in reception of an optical signal. There is no need to electrostatically shield all electromagnetic waves that do not generate noise.

  In the optical receiver according to the present invention, it is preferable that the maximum distance between the metal windings and the maximum diameter of the opening are not more than a size for the electromagnetic wave that generates the noise to be a cutoff frequency.

  According to the above configuration, since the maximum distance between the metal windings and the maximum diameter of the opening are not larger than the size required for the electromagnetic wave that generates noise to be a cutoff frequency, the electromagnetic wave that generates noise is generated inside the electrostatic shielding coil. Does not affect the operation of Therefore, it is possible to more effectively suppress the occurrence of noise due to electromagnetic waves in the light receiving element. The maximum distance between the metal windings and the maximum diameter of the opening are equal to or smaller than the size for the electromagnetic wave that generates noise to be a cut-off frequency, for example, less than or equal to 1/10 of the wavelength of the electromagnetic wave that generates noise. Is the size of

  The light receiver according to the present invention includes a plurality of the light receiving elements, and the electrostatic shielding coil covers the plurality of light receiving elements and electrostatically shields the plurality of light receiving elements from the electromagnetic wave that generates the noise. preferable.

  According to the above configuration, since the electrostatic shielding coil covers the plurality of light receiving elements and shields the plurality of light receiving elements from electromagnetic waves that generate noise, it is not necessary to provide the electrostatic shielding coil for each light receiving element. And installation space can be reduced.

The light receiver of the present invention can be suitably used for a light receiving device.
The light receiving device according to the present invention further includes a wiring board to which the light receiver is fixed and electrically connected, and the wiring board includes an electrostatic shielding plate for electrostatically shielding the light receiving element from the electromagnetic wave. It is also preferable to serve as both.

  According to the above configuration, since the wiring board also serves as an electrostatic shielding plate for electrostatically shielding the light receiving element from the electromagnetic wave, it is possible to more effectively suppress the noise caused by the electromagnetic wave from being generated in the light receiving element. it can. In addition, since an optical signal does not enter from the wiring board side, even if the wiring board also serves as an electrostatic shielding plate, there is no obstacle to optical signal reception.

  ADVANTAGE OF THE INVENTION According to this invention, the light receiver which can suppress the noise by electromagnetic waves effectively can be provided, suppressing that a shield member becomes an obstruction of optical signal reception.

(First embodiment)
An embodiment of a light receiving device embodying the present invention will be described below with reference to FIGS.
In this embodiment, the light receiving device according to the present invention is applied to a wireless microphone of a loudspeaker broadcasting system. As shown in FIG. 1, a voice 9 uttered by a user is converted into an infrared signal (optical signal) 91 having a predetermined frequency by a wireless microphone 10 and transmitted. The infrared signal 91 is received by the light receiver 2 included in the light receiving device 1, converted into an electrical signal, and transmitted to the converter 3 included in the light receiving device 1. The converter 3 modulates the electric signal into a high frequency signal and transmits it to the receiver 4 outside the light receiving device 1. The receiver 4 demodulates the received high frequency signal and outputs it to the mixer 5. As a modulation method, frequency modulation (FM), amplitude modulation (AM), or the like can be used as appropriate. On the other hand, a music signal is input from the karaoke player (not shown) to the mixer 5, mixed with the above-described audio signal, amplified by the amplifier 6, and output as sound from the speaker 7.

  A switching power supply 8 is connected to the receiver 4 to supply power to the receiver 4 and to supply power to the light receiving device 1 via the receiver 4. Although the switching power supply 8 is a power supply using a switching element, electromagnetic waves that cause noise are generated with the switching operation of the switching element.

  As shown in FIG. 2, the light receiving device 1 has a shape in which a wiring board 12 provided with a light receiver 2 and a converter 3 is sealed with a cover 11 and fixed to a metal housing 13. The housing 13 can be used by being attached to a wall or the like. Hereinafter, in the light receiving device 1, the side on which the cover 11 is attached is referred to as “cover side”, and the opposite side of the cover side is referred to as “wall side”. The cover 11 is formed of a member that transmits infrared signals.

  As shown in FIGS. 2, 3 (a), and 3 (b), the light receiver 2 has a substantially hemispherical light receiving element 21 covered with an electrostatic shielding coil 22. The electrostatic shielding coil 22 is a coil-shaped member formed of a metal winding, and is a shielding member for electrostatically shielding the light receiving element 21 from electromagnetic waves that generate noise that hinders reception of an optical signal. is there. Since the electrostatic shielding coil 22 has a coil shape, the both ends have openings, and one opening 23 faces the cover side. Since the wall side of the light receiving device 1 is attached to the wall or the like as described above, the light receiving device 1 is designed on the assumption that the main incident direction of the transmitted optical signal is the cover side. Accordingly, one opening 23 of the electrostatic shielding coil 22 is directed in the main incident direction of the transmitted infrared signal 91. Since there is no metal winding in the opening 23, the infrared signal 91 that attempts to enter the light receiving element 21 from the opening 23 is not blocked. Therefore, it is possible to suppress noise due to electromagnetic waves while suppressing the electrostatic shielding coil 22 from obstructing reception of the infrared signal 91.

  The maximum interval between the windings of the electrostatic shielding coil 22 and the maximum value of the inner diameter of the opening 23 are limited by the wavelength of the electromagnetic wave that generates noise that hinders reception of the infrared signal 91. That is, the maximum interval and the inner diameter are adjusted so that the electromagnetic wave emitted from the switching power supply 8 has a cutoff frequency. More specifically, it is said that the effect of electrostatic shielding can be sufficiently obtained if the magnitude is 1/10 or less of the wavelength of the electromagnetic wave emitted from the switching power supply 8, but the amount of noise generated is measured. It is preferable to further adjust the values of the maximum interval and the inner diameter based on the actual measurement result. For example, when the electromagnetic wave frequency band emitted from the switching power supply 8 is about 100 MHz, it is necessary to electrostatically shield the electromagnetic wave in the 100 MHz band. The wavelength of the electromagnetic wave in the 100 MHz band is about 150 cm, and the effect of electrostatic shielding is sufficiently recognized if the gap is 1/10 or less of the wavelength as described above. However, if it is 15 cm or less, electromagnetic waves in the 100 MHz band can be effectively suppressed. Therefore, the maximum value of the electrostatic shielding coil 22 and the maximum value of the inner diameter of the opening 23 may be 15 cm. In this embodiment, since the inner diameter of the opening 23 of the electrostatic shielding coil 22 is 15.5 mm and the maximum gap of the electrostatic shielding coil 22 is smaller than the inner diameter of the opening 23, it is emitted from the switching power supply 8. It is considered that noise can be effectively suppressed from occurring in the 100 MHz band.

  The light receiver 2 and the converter 3 are fixed and electrically connected to the wiring board 12. Moreover, since the wiring board 12 includes a copper plate in the inner layer of the board, it also serves as an electrostatic shielding plate for electrostatically shielding the light receiver 2 from electromagnetic waves from the wall side. Since an infrared signal is not incident from the wall side, it is plate-shaped and does not interfere with reception. The wiring board 12 also serving as the electrostatic shielding plate makes it possible to electrostatically shield, for example, electromagnetic waves that have passed through the wall, and more effectively suppress noise caused by the electromagnetic waves from being generated in the light receiving element. Can do. Note that the electronic components arranged on the wall side of the wiring board 12 including the converter 3 are electrostatically shielded by a metal casing 13.

According to the light receiving device of the above embodiment, the following effects can be obtained.
(1) Since the opening 23 of the electrostatic shielding coil 22 is directed in the incident direction of the infrared signal 91 with respect to the light receiving element 21, there is no metal winding constituting the electrostatic shielding coil 22 in the incident direction. Therefore, it is possible to effectively suppress noise due to electromagnetic waves while suppressing the electrostatic shielding coil 22 from obstructing the reception of the infrared signal 91.

  (2) Since the maximum distance between the metal windings and the inner diameter of the opening 23 are adjusted so that the electromagnetic waves that generate noise (electromagnetic waves generated from the switching power supply 8) have a cutoff frequency, noise is generated. The electromagnetic wave to be generated does not affect the inside of the electrostatic shielding coil 22. Therefore, it is possible to more effectively suppress the occurrence of noise due to electromagnetic waves in the light receiving element 21.

  (3) Since the wiring board 12 includes a copper plate in the inner layer of the board, the wiring board 12 also serves as an electrostatic shielding plate for electrostatically shielding the light receiving element 21 from the electromagnetic wave. Can be more effectively suppressed. In addition, since an optical signal does not enter from the wiring board side, that is, the wall side, even if the wiring board 12 also serves as an electrostatic shielding plate, there is no obstacle to reception of the infrared signal 91.

(Second Embodiment)
Next, a second embodiment of a light receiving device embodying the present invention will be described. Since the second embodiment has a configuration in which the form of the light receiver of the first embodiment is changed, detailed description of the same parts is omitted.

  As shown in FIG. 4, the light receiver 2 has a shape in which two light receiving elements 21 having a substantially hemispherical shape are covered with an electrostatic shielding coil 22. The electrostatic shielding coil 22 is a coil-shaped member formed of a metal winding, and is a shielding member for electrostatically shielding the light receiving element 21 from electromagnetic waves that generate noise that hinders reception of an optical signal. is there. Since the electrostatic shielding coil 22 has a coil shape, the both ends have openings, and one opening 23 faces the cover side. As described above, since the wall side of the light receiving device 1 is attached to the wall or the like via the housing 13, the light receiving device 1 is designed on the assumption that the main incident direction of the transmitted optical signal is the cover side. Yes. Accordingly, one opening 23 of the electrostatic shielding coil 22 is directed in the main incident direction of the transmitted infrared signal 91. Since there is no metal winding in the opening 23, the infrared signal 91 that attempts to enter the light receiving element 21 from the opening 23 is not blocked. Therefore, it is possible to suppress noise due to electromagnetic waves while suppressing the electrostatic shielding coil 22 from obstructing reception of the infrared signal 91.

  The maximum interval between the windings of the electrostatic shielding coil 22 and the maximum value of the inner diameter of the opening 23 are limited by the wavelength of electromagnetic waves that generate noise that hinders reception of the infrared signal 91. That is, the values of the maximum interval and the inner diameter are adjusted so that the electromagnetic wave emitted from the switching power supply 8 has a cutoff frequency. More specifically, it is said that the effect of electrostatic shielding can be sufficiently obtained if the magnitude is 1/10 or less of the wavelength of the electromagnetic wave emitted from the switching power supply 8, but the amount of noise generated is measured. It is preferable to further adjust the values of the maximum interval and the inner diameter based on the actual measurement result. For example, when the electromagnetic wave frequency band emitted from the switching power supply 8 is about 100 MHz, it is necessary to electrostatically shield the electromagnetic wave in the 100 MHz band. The wavelength of the electromagnetic wave in the 100 MHz band is about 150 cm, and the effect of electrostatic shielding is sufficiently recognized if the gap is 1/10 or less of the wavelength as described above. However, if it is 15 cm or less, electromagnetic waves in the 100 MHz band can be effectively suppressed. Therefore, the maximum value of the electrostatic shielding coil 22 and the maximum value of the inner diameter of the opening 23 may be 15 cm. In the present embodiment, the inner diameter of the opening of the electrostatic shielding coil 22 is 50 mm, and the maximum gap of the electrostatic shielding coil 22 is smaller than the inner diameter of the opening. Generation of noise can be effectively suppressed. In addition, since the two light receiving elements 21 are covered with one electrostatic shielding coil 22, the inner diameter of the opening 23 is larger than that in the first embodiment, but the light receiving element 21 has a 100 MHz band as described above. Electromagnetic waves that generate noise can be electrostatically shielded.

  The light receiver 2 and the converter 3 are fixed and electrically connected to the wiring board 12. Moreover, since the wiring board 12 includes a copper plate in the inner layer of the board, it also serves as an electrostatic shielding plate for electrostatically shielding the light receiver 2 from electromagnetic waves from the wall side. Since no optical signal is incident from the wall side, it is plate-shaped and has no particular problem. The wiring board 12 also serving as the electrostatic shielding plate can electrostatically shield an electromagnetic wave that has passed through a wall, for example, and can further prevent noise caused by the electromagnetic wave from being generated in the light receiving element. Note that the electronic components arranged on the wall side of the wiring board 12 including the converter 3 are electrostatically shielded by a metal casing 13.

Therefore, according to the second embodiment, in addition to the effects described in the first embodiment, the following effects can be obtained.
(1) According to the second embodiment, the electrostatic shielding coil 22 covers the plurality of light receiving elements 21 and electrostatically shields the plurality of light receiving elements 21 from electromagnetic waves that generate noise. There is no need to provide each light receiving element 21, and the cost and installation space can be reduced.

In addition, you may change the said embodiment as follows.
-In 1st Embodiment or 2nd Embodiment, the generation source of the electromagnetic wave used as noise is made into the switching power supply 8, and the inner diameter of the opening part 23 and the coil-shaped part are based on the wavelength of the electromagnetic wave generated from the switching power supply 8. Although the maximum interval has been determined, the present invention is not limited to this. For example, when the electromagnetic wave generation source that causes noise is in another electronic component or device, the inner diameter of the opening 23 and the maximum distance between the coiled portions are set based on the wavelength of the electromagnetic wave emitted from the electronic component or device. It goes without saying that it is decided.

  In the second embodiment, the two light receiving elements 21 are covered with one electrostatic shielding coil 22, but the present invention is not limited to this. If possible, three or more light receiving elements 21 may be covered with one electrostatic shielding coil 22. As described above, when the electromagnetic wave in the 100 MHz band is a source of electromagnetic waves that become noise, the wavelength of the electromagnetic wave is about 150 cm, and therefore the inner diameter of the opening 23 may be 15 cm or less, which is 1/10 of that. Therefore, if it is a light receiving element provided in a normal light receiving device, it is possible to electrostatically shield three or more by covering them with one electrostatic shielding coil 22.

  In the first embodiment or the second embodiment, the electronic components arranged on the wall side of the wiring board 12 including the converter 3 are configured to be electrostatically shielded by the metal housing 13. However, other configurations may be used. For example, if it is set as the structure which covers the electronic component arrange | positioned at the wall side of the wiring board 12 with a special shield case, the housing | casing 13 is not limited to metal.

  -In 1st Embodiment or 2nd Embodiment, although the light-receiving device 1 is attached and used for a wall surface, another structure may be sufficient. That is, it is sufficient that the opening 23 of the electrostatic shielding coil 22 is used in a mode in which the light signal is mainly incident. For example, a table placed on a ceiling or a room provided with a loudspeaker broadcasting system. It may be placed on top.

  In the first embodiment or the second embodiment, the light receiver 2 is used in the light receiving device 1 for a wireless microphone, but may be used for other purposes. For example, the present invention can be widely applied to devices that use optical signals as communication means and light receiving devices in equipment such as infrared conference systems, simultaneous interpretation systems, remote controllers (remote controllers), wireless headphones, and IrDA (Infrared Data Association).

  -In 1st Embodiment or 2nd Embodiment, although the light-receiving device 1 is used for the loud sound broadcasting system, another structure may be sufficient. For example, karaoke, a conference hall, a public facility, a learning facility, a game hall, and the like can be widely used.

  In addition, the light receiving device 1 may not be configured to receive the optical signal transmitted from the wireless microphone 10. For example, the present invention can also be applied to a case where an optical signal transmitted by a device having a function of transmitting an optical signal, such as a wireless headset, a remote controller, a mobile phone, a PDA (Personal Digital Assistant), or a notebook personal computer is received.

  The present invention relates to a photoreceiver that receives an optical signal, and is an invention related to a photoreceiver in which a shield member is suppressed from becoming an obstacle to optical signal reception, and thus can be widely used industrially.

BRIEF DESCRIPTION OF THE DRAWINGS It is drawing explaining one Embodiment of the light-receiving device concerning this invention, Comprising: It is a block diagram of a loud sound broadcasting system in which a light-receiving device is used. BRIEF DESCRIPTION OF THE DRAWINGS It is drawing explaining one Embodiment of the light-receiving device concerning this invention, Comprising: It is a schematic diagram which shows the state with which the light-receiving device was attached to the wall surface. BRIEF DESCRIPTION OF THE DRAWINGS It is drawing explaining one Embodiment of the light-receiving device concerning this invention, Comprising: (a) is a top view of a light receiver, (b) is a front view of a light receiver. It is drawing explaining 2nd Embodiment of the light-receiving device concerning this invention, Comprising: It is a schematic diagram which shows the state with which the light-receiving device was attached to the wall surface.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Light receiving device, 2 ... Light receiver, 3 ... Converter, 4 ... Receiver, 5 ... Mixer, 6 ... Amplifier, 7 ... Speaker, 8 ... Switching power supply, 9 ... Audio | voice, 10 ... Microphone, 11 ... Cover, 12 DESCRIPTION OF SYMBOLS ... Wiring board, 13 ... Housing | casing, 21 ... Light receiving element, 22 ... Electrostatic shielding coil, 23 ... Opening part, 91 ... Infrared signal.

Claims (5)

A light receiving element for receiving an optical signal;
The light receiver includes a coil-shaped metal winding that covers the light receiving element and an electrostatic shielding coil for electrostatically shielding the light receiving element from electromagnetic waves that generate noise that interferes with reception of the optical signal. And
An opening of the electrostatic shielding coil is directed in an incident direction of the optical signal with respect to the light receiving element.   The light receiver according to claim 1, wherein a maximum interval between the metal windings and a maximum diameter of the opening are equal to or less than a size for the electromagnetic wave that generates the noise to become a cutoff frequency. A plurality of light receiving elements;
The light receiving device according to claim 1, wherein the electrostatic shielding coil covers the plurality of light receiving elements and electrostatically shields the plurality of light receiving elements from the electromagnetic wave that generates the noise.   A light receiving device comprising the light receiver according to claim 1. Further comprising a wiring board to which the light receiver is fixed and electrically connected,
The light receiving device according to claim 4, wherein the wiring board also serves as an electrostatic shielding plate for electrostatically shielding the light receiving element from the electromagnetic wave.

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