JP2005101853A - Optical transmitter and optical wireless device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmitter and an optical radio equipment, being safe to an eye, to realize high speed optical communication. <P>SOLUTION: The transmission part 3 of a master machine 1 is provided with an infrared ray emitting semiconductor laser radiating transmission light 8, and a visible light emitting diode radiating visible light 7 having a radiation angle that is almost equal to transmission light 8. The transmitter 5 of a slave machine 2 is provided with an infrared ray emitting semiconductor laser radiating transmission light 10, and a visible light emitting diode radiating visible light 9 which is sufficiently narrower than transmission light 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical transmission device and an optical wireless device that perform high-speed transmission and reception of information between a parent device and a child device using invisible light such as infrared rays, and in particular, have high eye safety and high-speed light. The present invention relates to an optical transmission device and an optical wireless device that enable communication.

  Optical wireless has advantages such as no need for wiring as with radio, and relatively easy high-speed communication over 100 Mbps compared to radio. It is promising as a method for connecting a mobile device such as a device or PDA (Personal Data Assistance) device and a LAN (Local Area Network).

  On the other hand, with the increase in the definition of images and the increase in moving image images, there is a demand for higher speeds in optical wireless communication. Even now, higher speeds of communication such as 100 Mbps or higher and 1 to 10 Gbps in the future are required.

As a conventional optical wireless device capable of such high-speed communication, for example, a device using an infrared-emitting semiconductor laser excellent in high-speed modulation is known (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 6-232818

  However, since the infrared rays used in conventional optical wireless devices are not visible to the human eye, various inconveniences have occurred. First, since the output direction of both the master unit and the slave unit is unknown, it is necessary for the optical transmission device with a fixed directivity angle to transmit with a wide directivity angle so that all positions where the counterpart device may exist are included. And therefore requires high power transmission.

  Secondly, the scanning optical transmission device has to scan a wide range, which causes problems such as an increase in size of the device, an expensive lens, and a long time before starting transmission / reception.

  Third, since the direction of the infrared transmission light is unknown, it is easy for others to block. In addition, since the reflection / scattering state on a desk or wall on the way is unknown, there is a risk of eavesdropping from the outside.

  On the other hand, when a visible light emitting semiconductor laser is used, the semiconductor laser includes an InGaP red laser, a GaN blue laser, and the like. However, the former has a problem of poor thermal characteristics and cannot perform high-speed modulation at 1 GHz level. is there. In the latter case, the photon energy is high at a short wavelength, and the efficiency of the Si photodetector is poor. Therefore, there is a problem that the amount of current when the unit power is incident on the receiver is small and high power transmission is required. is there. Further, since both are coherent light, there is a problem that the eye is easily damaged.

  As a means for avoiding these, there is a method using non-interfering light such as a light emitting diode, but in this case, the modulation speed is 100 MHz at most, and there is a problem that a communication speed higher than this cannot be expected.

  Accordingly, an object of the present invention is to provide an optical transmission device and an optical wireless device that have high eye safety and enable high-speed optical communication.

  In order to achieve the above object, the present invention provides a first light source that emits infrared communication light, a second light source that emits visible light, and the infrared communication light emitted from the first light source. There is provided an optical transmission device comprising: a combining optical system configured to combine the visible light emitted from the second light source so that respective optical axes coincide with each other.

  In order to achieve the above object, the present invention provides an optical wireless apparatus that transmits and receives infrared communication light between a parent device and a child device each having a transmission unit and a reception unit, and at least one of the parent device and the child device The transmitter includes: a first light source that emits the infrared communication light; and a second light source that emits visible light that matches an optical axis of the infrared communication light. A wireless device is provided.

  According to the optical transmission device and the optical wireless device of the present invention, visible light is emitted so as to coincide with the optical axis of the infrared communication light, so carelessly when non-interfering light is used as the infrared communication light. The risk of entering the eye and damaging the retina is reduced, and safety for the eye is increased. In addition, since the position of the infrared communication light can be visually recognized by visible light, the connection between the parent device and the child device can be ensured accurately. Furthermore, high-speed optical communication is possible by using a semiconductor laser capable of high-speed modulation as the first light source that emits infrared communication light.

  FIG. 1 shows an optical wireless apparatus according to a first embodiment of the present invention, in which FIG. 1 (a) shows a transmission state on the parent device side, and FIG. 1 (b) shows a transmission state on the child device side. . This optical wireless device transmits and receives information between the master unit 1 and the slave unit 2. For example, the master unit 1 is attached to a fixed device such as a network terminal such as a LAN, and the slave unit 2 It is attached to fixed / semi-fixed devices such as personal computers, printers, projectors, TVs, mobile phones, and PDAs. Note that both the master unit 1 and the slave unit 2 may be attached to a fixed / semi-fixed device or a mobile device.

  The base unit 1 includes the transmission unit 3 and the reception unit 4 on the base 11, and the slave unit 2 includes the transmission unit 5 and the reception unit 6 on the base 12, similar to the base unit 1. The transmission unit 3 is different.

  As shown in FIG. 1A, the transmission unit 3 of the base unit 1 has an infrared light emitting semiconductor laser (not shown) that emits transmission light 8 as infrared communication light, and radiation substantially equal to the transmission light 8. A visible light emitting diode (not shown) that emits incoherent visible light 7 having a corner.

  As shown in FIG. 1B, the transmission unit 5 of the slave unit 2 is sufficiently more than an infrared light emitting semiconductor laser (not shown) that emits transmission light 10 as infrared communication light and the transmission light 10. And a visible light emitting diode (not shown) that emits narrow incoherent visible light 9.

  The receiving units 4 and 6 of the master unit 1 and the slave unit 2 receive a condensing lens (not shown) that condenses the transmission light 8 and 10 and the transmission light 8 and 10 collected by the condensing lens. And a light receiving element such as a photodiode that converts the signal into an electric signal.

  FIG. 2 shows the transmission unit 3 of the base unit 1. The transmitter 3 includes an infrared light emitting semiconductor laser 21 that emits infrared light, a hologram lens 22 that shapes the output light into a substantially conical shape, a visible light emitting diode 23 having a dome-shaped light extraction surface 24, and a semiconductor laser. The dichroic prism 25 as a dichroic combiner that combines the output lights 26 and 27 of the light emitting diode 21 and the light emitting diode 23 with the optical axes aligned, and a projection lens 29 that projects the combined light from the dichroic prism 25 onto the other device. Is done. The hologram lens 22 may use other beam shaping elements such as a cylindrical lens and a beam shaping prism as long as the output light is shaped into a substantially conical shape. The dichroic prism may be a dichroic mirror.

  As the infrared light emitting semiconductor laser 21, an InGaAs semiconductor laser that emits laser light having a wavelength of 1.5 μm or a GaAs semiconductor laser that emits laser light having a wavelength of 0.78 to 0.98 μm can be used. By using an InGaAs semiconductor laser, the wavelength of 1.5 μm is an eye-safe wavelength, and thus the safety for the eyes is increased. Further, by using a GaAs-based semiconductor laser, it is frequently used for CDs and the like, and is inexpensive and can be used with high efficiency and high output. Although the wavelength of this GaAs semiconductor laser is not eye-safe, the radiation position can be specified by visible light, so that it is possible to avoid the danger of reflected / scattered light entering the eye.

  As the infrared light emitting semiconductor laser 21, an edge emitting semiconductor laser or a surface emitting semiconductor laser (VCSEL) can be used. By using a surface emitting semiconductor laser (VCSEL), the output is reduced, but the efficiency is higher than that of the edge emitting laser, and it is suitable as a light source for mobile use. Both edge-emitting semiconductor lasers and surface-emitting semiconductor lasers can be modulated at 10 GHz or more, and are lasers that are frequently used in optical communications, and therefore can be obtained at a relatively low cost. An edge emitting semiconductor laser having an output distribution of an elliptical cone or a cone can be used. A surface emitting semiconductor laser having a conical output distribution can be used. When an elliptical cone is used, efficient light emission can be performed when scanning in two dimensions. In addition, when a semiconductor laser having a conical output distribution is used and the distribution of the emitted light is an elliptical cone, a beam shaping element that shapes the output light into a substantially conical shape may be combined.

  As the visible light-emitting diode 23, an InGaN-based light-emitting diode that emits visible radiation having a wavelength of 530 nm, an organic light-emitting diode that emits green radiation, or an InGaP-based red light-emitting diode that emits red radiation is used. it can. When an InGaN-based light emitting diode is used, visible radiation having a wavelength of 530 nm has high visibility even if the light emission output is suppressed, and thus can be sufficiently visually recognized. In addition, when an organic light emitting diode that emits green radiated light or an InGaP red light emitting diode is used, the radiated light is non-interfering light, and is incident on the eye and is focused on a minute light spot in the retina. It is never done and it is safe.

  The projection lens 29 in the transmission unit 3 of the main unit 1 narrows the output light 26 and 27 of the infrared light emitting semiconductor laser 21 and the visible light emitting diode 23 with a divergence angle of approximately 30 degrees to about 20 degrees, and the visible light 7 and the transmitted light. 8 is projected.

  FIG. 3 shows the transmission unit 5 of the handset 2. The transmitter 5 of the slave unit 2 includes the semiconductor laser 21, the light emitting diode 23, the dichroic prism 25, and the projection lens 29, as in the base unit 1, but the position of the light emitting diode 23 is set to be higher than the focal position of the projection lens 29. By arranging it sufficiently behind, the spread angle of the visible light 9 of the light emitting diode 23 is narrowed to several degrees.

  In the optical wireless device configured as described above, the transmission light 8 is transmitted from the parent device 1 toward the child device 2 and the visible light 7 is also emitted. The operator visually observes the child device within the range of the visible light 7. 2 receiving units 6 are inserted. Since the visible light 7 has a radiation angle substantially equal to that of the transmission light 8, the slave unit 2 can reliably receive the transmission light.

  According to the first embodiment, since the arrival position of the transmission light 8 can be recognized by the visible light 7, communication is possible even if the transmission light 8 is sent to a relatively narrow range, and low output and low High-speed optical communication with power consumption becomes possible. In addition, it is possible to perform communication by placing the slave unit 2 in the area of the transmission light 8 and, on the contrary, it is possible to avoid inadvertently entering the area of the transmission light 8 and hindering communication. Furthermore, since the direction of the transmission light 8 is known, the risk of eavesdropping from the outside is reduced, and the security is increased.

  FIG. 3 shows a transmission unit according to the second embodiment of the present invention. The transmitter 30 is formed by laminating an organic EL light emitting element 33 emitting green light sandwiched between transparent electrodes 32 and 34 on a surface emitting semiconductor laser (VCSEL) 31 emitting infrared light. The spread angle of the output light 35 of both the VCSEL 31 and the organic EL light emitting element 33 is approximately 20 degrees, and the projection lens 29 projects the spread angle to about 20 degrees.

  According to the second embodiment, by laminating the infrared light emitting semiconductor laser and the visible light emitting diode, it is possible to simplify the transmitter 30 and reduce the cost, such as eliminating the need for a dichroic prism. .

  In each of the above embodiments, the radiation angle of the visible light emitted from the slave unit is narrower than the radiation angle of the transmission light, but may be substantially equal to the radiation angle of the transmission light. Also good. By forming the beam, the power of coherent visible light can be reduced.

  In each of the above embodiments, the visible light emitted from the parent device is substantially equal to the radiation angle of the transmission light, but may be wider than the radiation angle of the transmission light. In this case, since a normal light emitting diode with a relatively wide directivity angle embedded with an epoxy resin having a bullet-shaped light extraction surface can be used, the price can be reduced.

  In each of the above embodiments, a visible light emitting diode that emits incoherent visible light has been described as the second light source. However, if the power is not high enough to harm the eyes, coherent visible light is emitted. A semiconductor laser may be used.

The optical wireless apparatus which concerns on the 1st Embodiment of this invention is shown, (a) shows the transmission state by the side of a main | base station, (b) is a figure which shows the transmission state by the side of a subunit | mobile_unit. It is a figure which shows the transmission part of the main | base station which concerns on the 1st Embodiment of this invention. It is a figure which shows the transmission part of the subunit | mobile_unit which concerns on the 1st Embodiment of this invention. It is a figure which shows the transmission part which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main | base station 2 Subunit 3 Transmitter 4 Receiver 5 Transmitter 6 Receiver 7 Visible light 8 Transmitted light 9 Visible projection light 10 Transmitted light 11 and 12 Base 21 Infrared light emitting semiconductor laser 22 Hologram lens 23 Visible light emitting diode 24 Light Extraction surface 25 Dichroic prisms 26 and 27 Output light 28 Projection lens 30 Transmitter 31 Surface-emitting semiconductor laser (VCSEL)
32, 24 Transparent electrode 33 Organic EL light emitting diode 35 Output light

Claims (19)

A first light source that emits infrared communication light;
A second light source that emits visible light;
And a synthesis optical system that synthesizes the infrared communication light emitted from the first light source and the visible light emitted from the second light source so that their optical axes coincide with each other. Optical transmitter.   The combining optical system includes a dichroic combiner that combines the infrared communication light emitted from the first light source and the visible light emitted from the second light source, and light combined by the dichroic combiner. The optical transmission device according to claim 1, further comprising: a projection lens that projects the light toward the other device.   The optical transmitter according to claim 1, wherein the first light source is an infrared light emitting semiconductor laser.   4. The optical transmission device according to claim 3, wherein the infrared light emitting semiconductor laser is an edge emitting semiconductor laser, and an output distribution thereof is an elliptical cone shape.   4. The infrared light emitting semiconductor laser is an edge emitting semiconductor laser, and includes a beam shaping element that shapes an output distribution of the edge emitting semiconductor laser in a substantially conical shape in front thereof. Optical transmitter.   4. The optical transmission device according to claim 3, wherein the infrared light emitting semiconductor laser is a surface emitting semiconductor laser and its output distribution is conical.   4. The optical transmitter according to claim 3, wherein the infrared light emitting semiconductor laser is an InGaAs semiconductor laser that emits the infrared light having a wavelength of about 1550 nm.   4. The optical transmitter according to claim 3, wherein the infrared light emitting semiconductor laser is a GaAs semiconductor laser that emits the infrared light having a wavelength of 780 to 980 nm.   The optical transmitter according to claim 1, wherein the second light source emits the incoherent visible light.   The optical transmission device according to claim 1, wherein the second light source is a light emitting diode.   The optical transmission device according to claim 1, wherein the second light source is an organic EL light emitting element.   The optical transmission device according to claim 1, wherein the second light source is stacked on the first light source.   The optical transmission device according to claim 1, wherein the second light source has an emission angle of the visible light substantially equal to an emission angle of the infrared communication light.   The optical transmission device according to claim 1, wherein the second light source has an emission angle of the visible light wider than an emission angle of the infrared communication light.   The optical transmission device according to claim 1, wherein the second light source has an emission angle of the visible light narrower than an emission angle of the infrared communication light. In an optical wireless device that transmits and receives infrared communication light between a parent device and a child device each having a transmitter and a receiver,
The transmission unit of at least one of the parent device and the child device includes a first light source that emits the infrared communication light, and a second light source that emits visible light that matches the optical axis of the infrared communication light. An optical wireless device comprising:   The optical wireless according to claim 16, wherein the second light source of the transmission unit of both the parent device and the child device emits the visible light that coincides with an optical axis of the infrared communication light. apparatus.   One of the transmission units of the master unit and the slave unit emits the visible light having a radiation angle substantially equal to a radiation angle of the infrared communication light, and the other transmission unit transmits the infrared communication light. The optical wireless device according to claim 17, wherein the visible light having a radiation angle narrower than a radiation angle is emitted. The base unit is attached to a fixed device such as a network terminal,
17. The optical wireless apparatus according to claim 16, wherein the slave unit is attached to a semi-fixed device or a mobile device such as a personal computer, a printer, a projector, a TV, a mobile phone, or a PDA.

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