JP3003947B2 - Optical transmitter and transceiver module - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a transmitter and a transceiver module for optical data transmission. These modules, in particular,
Suitable for use in infrared data transmission systems.

BACKGROUND OF THE INVENTION The proliferation of workstations and personal computers (e.g., desktop and handheld) in all areas of business, management, and manufacturing has made these systems flexible and easy to use. The demand for interconnection is growing. Similar requirements exist for the connection and interconnection of peripheral devices such as keyboards, computer mice, printers, plotters, scanners, and display devices. The use of wire networks and cables becomes a problem, especially when the density of systems and peripherals increases and the location of the system or the configuration of subsystems must be changed frequently. It is therefore desirable to utilize a wireless communication system to interconnect such devices and systems to eliminate the requirements of the electrical cable network.

During the last years, there has been increased interest in using optical signals to exchange information between systems and remote devices. An advantage of such a wireless optical communication system is that most of the conventional wiring is not required. Radio frequency (RF)
Regarding wireless transmission, the communication rules do not apply and PTT and F
Optical infrared (I
R) Wireless transmission is advantageous. In addition, there is no interference from electromagnetic interference or interference from other RF channels, and radiation is limited to the room, which ensures better data security than RF systems. Thus, there is no interference from similar systems operating in the adjacent room, providing a higher degree of data security than radio frequency transmission can provide. In contrast to antennas for radio frequencies, the dimensions of light emitting diodes (LEDs) and photodiodes are generally small, which is especially important for portable computer design.

The optical signal in such a system propagates directly to the optical receiver of the receiving system, or arrives indirectly at the receiver after the direction of propagation changes due to processes such as reflection and scattering at the surface. Today, the former case is implemented in a portable computer docking station that transfers data between an optical transmitter and receiver that are well aligned and close to a centimeter in distance. The latter case is impractical or even impossible to transmit optical signals directly between the transmitter and receiver several meters away from each other, because perturbations in the direct path are unavoidable. Even typical in applications in some office environments. One known approach to achieving high flexibility is to radiate an optical signal from the transmitting system to the office ceiling, where the optical signal is reflected or scattered. This spreads the radiation over a certain area around the transmitter. The dispersion of the light signal emanating from the ceiling depends on many details characteristic of the particular environment under consideration. However, what is important in this situation is mainly that the transmission coverage, ie the distance between the transmitting system and the receiving system, is limited to a certain final value. This is because the transmitted radiant energy flux decreases as the propagation distance increases, and the sensitivity of the receiver is limited by the final signal-to-noise ratio. Hereinafter, this is called a transmission effective range. Typical known systems operating at light output levels limited by light source performance and exposure safety requirements have demonstrated transmission coverage of several meters at 1 Mbps data rates.

Critical parameters of a wireless optical communication system are the data transmission rates and distances that can be achieved between systems that exchange data. In an orifice environment, data may have to be communicated over a longer distance than the transmission range of a conventional optical transmitter.

Today's wireless optical data transmission systems have several disadvantages. First, it is not suitable for use in environments such as offices and conference rooms where the effective transmission range is large, and the radiation characteristics and effective range are generally not uniform, so that the transmitter and receiver are accurately positioned. Need to be matched.

Secondly, one must take into account that in most environments, there is inevitable ambient light, such as sunlight or light from the lights, that always reaches the photodetector, unless the system is restricted to use in a dark environment. Must. Unavoidable ambient light can cause time-dependent signals, such as alternating current signals from electric lights, and in fact is often a significant and major source of optical receiver noise. Thus, ambient light affects the signal-to-noise ratio of the receiver, and thus the transmission range. The appearance of unavoidable light is often statistical and difficult to control, and its brightness can change drastically, as evidenced by flickering sunlight or flashing lights. Another realistic phenomenon that statistically affects the signal-to-noise ratio, and thus the transmission range, is the presence of optical path obstructions that affect the signal at the receiver.

The first approach to overcoming these problems would be to increase the output power of the transmitter module. This has proven impractical for several reasons. The power consumption of such transmitter modules is too high for use in portable systems such as notebook computers and palmtop computers. However, the biggest challenge facing the development of optical wireless systems is optical security. It is believed that light emission can be harmful to eyes and skin if the exposure is too intense. The degree of danger depends on the exposure level (energy or power), exposure time,
And a number of factors, including wavelength.

PP Smith (Smyth) et al., “Optical Wireless: New
Enabling Transmitter Technologies ", IEEE Internat
ional Conference on Communication '93, May 2, 1993
Changes in existing eye safety standards and new forms of transmitter technology are discussed in the Technical Program, Proceedings of the Minute, Vol. 562-566, Geneva, Switzerland, March 26-26. This new type of transmitter technology is based on the concept of increasing the area of the light source to reduce the risk of retinal damage. This paper proposes, for example, using a computer-generated phase hologram to obtain multiple beams for beam shaping from a single laser diode light source.

Although this approach is the first step in the right direction, the problems of poor transmission coverage and sufficient eye safety have not yet been addressed and have not been solved.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved optical transmitter module.

Another object of the present invention is to provide an optical transmitter module having a small size and an optimal radiation pattern.

Another object of the present invention is to provide an optical transmitter module that meets safety standards (IEC825-1).

Another object of the present invention is to provide an optical transmitter module whose radiation pattern can be switched.

The above objective is accomplished by implementing an optical transmitter module as claimed below.

Description of the drawings and the notation used The invention is described in detail below with reference to the following drawings.

FIG. 1 is a schematic sectional view of an optical transmitter module according to the present invention.

FIG. 2 is a diagram showing three regularly and symmetrically different structures of the light emitting diode.

FIG. 3 is a schematic sectional view of an optical transmitter module according to the present invention.

FIG. 4 is a schematic sectional view of an optical transmitter module according to the present invention.

FIG. 5 is a schematic sectional view of an optical transmitter module according to the present invention.

 FIG. 6A is a cross-sectional view of the hemispherical housing.

 FIG. 6B is a cross-sectional view of the hemispherical housing.

FIG. 7 is a schematic sectional view of an optical transmitter module according to the present invention.

FIG. 8 is a schematic plan view of an optical transmitter module according to the present invention.

FIG. 9 is a schematic plan view of an optical transmitter module according to the present invention.

FIG. 10 is a schematic sectional view of an optical transmitter module according to the present invention.

FIG. 11 is a schematic sectional view of an optical transmitter module according to the present invention.

FIG. 12 is a schematic sectional view of an optical transmitter module capable of switching a radiation pattern according to the present invention.

FIG. 13A is a schematic plan view of the optical transmitter module in which the radiation pattern shown in FIG. 12 can be switched.

FIG. 13B is a schematic plan view of the optical transmitter module in which the radiation pattern shown in FIG. 12 is switchable.

FIG. 13C is a schematic plan view of the optical transmitter module in which the radiation pattern shown in FIG. 12 is switchable.

FIG. 14 is a schematic sectional view of an optical transceiver module according to the present invention.

FIG. 15A is a schematic sectional view of an optical transceiver module according to the present invention.

FIG. 15B is a schematic plan view of a receiver portion of the optical transceiver module shown in FIG. 15A.

FIG. 16 is a schematic sectional view of an optical transceiver module according to the present invention.

FIG. 17A is a schematic sectional view of an optical transmitter module capable of switching a radiation pattern according to the present invention.

FIG. 17B is a schematic plan view of the housing and the reflection ring of the optical transceiver module shown in FIG. 17A.

FIG. 18A is a schematic sectional view of an optical transmitter module capable of switching a radiation pattern according to the present invention.

FIG. 18B is a schematic plan view of the housing and the reflection ring of the optical transceiver module shown in FIG. 18A.

FIG. 19A is a schematic diagram of a fixture for mounting a switchable optical transmitter / receiver module according to the present invention.

FIG. 19B is a schematic diagram of the inclined position of the fixture of FIG. 19A.

FIG. 20 is a schematic sectional view of an optical transmitter module capable of switching a radiation pattern according to the present invention.

FIG. 21A is a diagram showing a notebook computer to which an optical transmitter or a transceiver module is attached.

FIG. 21B is a diagram illustrating a notebook computer including an integrated optical transmitter or transceiver module.

FIG. 22 is a schematic block diagram of an analog front end of a transceiver according to the present invention.

General Description In view of the above, it is highly desirable that a wireless optical transmitter module meet the following criteria.

1. Highest possible eye safety 2. Optimal light source radiation pattern that maximizes transmission distance with minimum dynamic range by efficiently dispersing optical signals with limited output. This is particularly advantageous when using the optical transmitter module in a normal office environment (low ceiling, diffuse propagation mode).

3. There is no need to align the transmitter and receiver. 4. In environments with very low ceilings (or non-reflective) and very high ceilings (buildings with atriums, large auditoriums, outdoors), the location of the receiver module The basic concept of the transmitter module according to the invention will be explained in connection with FIG. 1 where line of sight (LOS) propagation without alignment is available. As shown in this figure, such an optical transmitter module comprises an array of light emitting diodes 11 arranged regularly and symmetrically. In order to fix the diode 11 in an appropriate position, the mounting base 10 is used. The light emitting diode array 11 is arranged in a hemispherical housing 12. In this example, the hemispherical housing 12 is a long cylindrical tube having a hemispherical end. This housing 12 is at least partially transparent. Further, there is provided a diffuser means for apparently enlarging the light source. The diffuser means can be realized in various ways. The housing 12 can be formed, for example, from a plastic material containing high refractive index suspended particles so that at least a portion of the housing functions as a diffuser. In another embodiment, scattering of the light beam emanating from the light emitting diode 11 can be performed by a housing 12 having a corrugated surface. Plexiglas housing sandblasted with glass chips (100-150 microns in size) increases half-power angle (LED uses Stanley DN305) from 7.5 degrees to 10 degrees (normal incidence at diffuser) (Light), the output on the optical axis is reduced to a quarter. Other diffuser means are described with respect to the following embodiment. Depending on the roughness of the diffuser surface, or the number and size of the particles mixed into the diffuser housing, either a full diffuser or a partial diffuser can be achieved. Utilizing such a full diffuser results in a Lambertian light source.

Various radiation patterns can be realized depending on the configuration of the light emitting diode and the symmetry of the elevation angle, the radiation angle of the diode, the shape of the housing, the diffuser means and the mutual positional relationship of the diffuser within the housing. . Second
The figures show plan views of three exemplary diode configurations. The mounting table 20 on the left side of FIG. 2 supports only three light emitting diodes 21 arranged in a triangle. The mounting base 22 supports four regularly arranged diodes 23, and
24 supports eight light emitting diodes 25. These eight diodes 25 are arranged in a ring. From these three examples, it can be seen that any kind of symmetrical and regular arrangement of light emitting diodes in relation to a suitable housing and diffuser is suitable for achieving a high degree of eye safety and an optimal light source emission pattern. Is clear.

Before describing another embodiment, the light emitting diode will be described in more detail. The light emitting diodes shown here are commercially available diodes enclosed in a regular small plastic housing. Such diodes are available in various sizes and materials in plastic housings with various radiation patterns and angles. For example, Stanley's light emitting diode DN3
05 and DN304 are suitable. Obviously, the invention is not limited to the use of individual diodes, each enclosed in a housing. In some situations, it may be advantageous to use a diode array, all enclosed or packaged in one common housing. It is further conceivable to use separate light emitting diodes or light emitting diode arrays grown on a common substrate without a housing. In this case, the hemispherical housing containing these diodes replaces the housing of the diodes themselves and serves to protect these diodes.

FIG. 3 shows another optical transmitter module according to the present invention. This module comprises a mounting base 30 on which light emitting diodes 31 are regularly and symmetrically arranged.
The mounting 30 has an inclined surface, and the diode 31 is fixed on the mounting 30 so as to face the central axis of the cylindrical housing 32. The diffuser is incorporated in the housing, for example by suspended particles.

In the next embodiment shown in FIG. 4, an appropriate beam shaping is obtained by using a phase hologram 43 generated by a computer. This hologram is located in a cylindrical housing 42 and has a light emitting diode array 41
Is covered.

FIG. 5 shows an optical transmitter module with a hemispherical housing 52. The module further comprises a mounting 50 supporting a light emitting diode array 51. A part of the housing 52 is provided with a full light diffusing surface 53 to achieve diffusion of the light beam emitted from the diode 51. A similar effect can be achieved by a checkered light scattering pattern attached to the housing. By providing the light scattering surface inside the housing 52, it is possible to prevent the light diffuser from being contaminated by oil or dust on the finger. Varying degrees of diffusion can be achieved by changing the roughness of the light scattering surface, changing the checkerboard pattern, or providing light scattering surfaces on the inside and outside of the housing. The required surface roughness can be obtained by sandblasting or etching the mold for pressing the plastic housing. In the case of a plastic housing containing suspended particles, the degree of diffusion can be altered by embedding particles of different sizes and shapes.

Other hemispherical housings 60 and 61 are schematically illustrated in FIGS. 6A and 6B.

The optical transmitter module shown in FIG. 7 includes a flat mounting base 70 on which a normal light emitting diode 71 is disposed. The pins of these diodes are bent such that the diodes emit light toward a central axis 74 of the hemispherical housing 72. This structure is advantageous in applications where space is limited and the overall transmitter module must be small. Diode tilt angle, i.e. hemispherical housing 72
Plane perpendicular to the central axis 74 of the diode and the central axis of the radiation cone of the diode
The angle formed by 75 is preferably 5 to 80 degrees, particularly preferably 20 to 40 degrees. The optimal angle between the central axis of the LED and the mounting is about 25 degrees as far as the use of the modules described and claimed herein is concerned. An angle of 25 degrees provides the maximum light scattering range in offices with low ceilings (2.5-3.5m).

FIG. 8 shows another configuration. In this embodiment, eight light emitting diodes each having a housing
81 are regularly arranged in a ring on the mounting base 80 so that light emerges radially with respect to the central axis 83 of the module. A narrow beam light emitting diode having an elevation angle of about 25 degrees is suitable for use in this embodiment.

FIG. 9 shows a similar star configuration with eight diodes. In this embodiment, a diode 91 supported by a mounting 90 faces the central axis of the housing. On the left side of the figure, a housing with a full light scattering surface 93 is shown. Full diffuser means that the corrugated surface covers the entire cross section of the beam. The diffuser can be strong (creating a Lambertian light source) or weak (creating additional scattering of the beam to increase eye safety). This fully diffused surface is formed on the inner surface of the hemispherical housing. Next to this is the relevant radiation pattern realized by the diffuser means 93. On the right, a schematic diagram of a hemispherical housing with a checkered light scattering pattern 92 functioning as a light diffuser is shown. The radiation pattern is shown next to this diagram.
As shown schematically, a portion of the light passes through the diffuser with little or no obstruction, and the remaining light beam is scattered. Such a checkered pattern can be achieved, for example, by drilling holes in the housing or by using a suitable mask when polishing with a sandblaster.

FIG. 10 shows a hemispherical housing 102 and diffuser means 103
And an optical transmitter module having an additional annular prism portion integral with the housing 104. The prism ring 104 deflects the portion indicated by Δ of the beam output in the horizontal direction (downward), as indicated by the broken line. The rest exits directly through the diffuser 103. Prism ring 1
04 improves line-of-sight communication.

FIG. 11 shows still another embodiment of the present invention. The module shown in this figure is a light emitting diode array 111
Is provided on the mounting table 110. These diodes 111 are inclined with respect to the mount 110 and emit light radially. The hemispherical housing 112 includes a reflective ring 114 and diffuser means 113 on the inner surface. This reflecting ring reflects at least a portion of the beam emanating from the diode 111 upward before the beam passes through the diffuser 113.

FIG. 12 shows a cross-sectional view of another embodiment. This figure shows an optical module that can switch the beam pattern as shown in FIGS. 13A to 13C. The purpose of beam switching is to maximize the omnidirectional coverage (see FIGS. 13A and 13B) or
C) is to have a radiation pattern (eg, 25 degrees) that gives the maximum effective range. The switchable module comprises a mounting 120 on which a diode array 121 is fixed. A diode comprising diffuser means 123;
Reflector means 124 and upper deflection prism 1 both having a rough surface
25 and a lower deflecting prism 126 are disposed in a hemispherical housing 122. The mode of operation of this switchable module will be described with reference to FIGS. 13A to 13C. In these figures, a plan view of the module is shown. Thirteenth
As shown in FIG. A, the housing 122 includes a series of reflector means 124 and deflecting prisms 125, 126 along an inner surface 130 thereof. The reflector means 124 is shown in bold for clarity. The switching of the beam pattern can be performed because the housing with the reflector 124 and the deflecting prisms 125, 126 can rotate about its central axis with respect to the light emitting diode array 121. Deflection angle (horizontal plane)
Determines the direction of the desired reflected beam. The position of the arrow marker 132 (on the rotating housing 122) relative to the (fixed) symbol 134 indicates the selected beam pattern. If the marker 132 points to the symbol of “white circle”,
The module emits light in all directions at an elevation angle α of about 25 degrees, ie, in this mode of operation, the module functions as an omni-directional antenna with maximum transmission coverage and is suitable for ambient light or dark. This position repeats every 45 degrees.

Referring to FIG. 13B, when the marker 132 points to the symbol “black circle”, the omnidirectional power density increases in the vicinity of the module in an environment in which the ambient light angle is approximately 30 degrees to 40 degrees and the ambient light is bright. . This position repeats every 45 degrees. In the example shown in FIG. 13C, the pointer 132 points to the symbol “arrow”. This indicates that the directional coverage increases in the selected beam direction. The beams in the housing are indicated by dashed arrows. Eight different radiation directions can be selected in 45 degree increments.

14 to 16 show an optical transceiver module according to the present invention. The embodiment shown in FIG. 14 is based on the module shown in FIG. This module comprises a receiver in addition to a transmitter part. The receiver has four photodiodes 143 located below the mounting 140. These photodiodes are tilted and oriented in different directions to receive light from all directions around the module. The orientation and configuration of these photodiodes depends on the field of view of each diode, as well as the shape and location within the housing. The photodiode is protected by a thin wire mesh 145 that acts as a Faraday box to reduce electromagnetic interference. In this embodiment, the wire mesh
The 145 is incorporated in a hemispherical housing 142. This module includes a substrate 144 for electronic circuits by SMD technology.
Is below the photodiode 143. This board 144
Can support preamplifiers, LED drivers, or complete analog chips if space permits.

In the next embodiment shown in FIG. 15, the receiver part is above the transmitter part, ie above the light emitting diodes supported by the mounting 150. The receiver comprises an array of five photodiodes 153, all of which are arranged to receive light from all directions. These photodiodes are protected by a wire mesh 155 incorporated at the hemispherical end of the housing 152. Below these photodiodes 153,
There is a substrate 154 with electronic circuits. The receiver portion is separated from the transmitter by a reflector 156. FIG. 15B shows a schematic plan view of the receiver portion.

FIG. 16 shows another optical transceiver module.
This module is based on the transmitter module shown in FIG. 7, except that the receiver is incorporated in the same housing 162. The receiver includes a photodiode array 161 mounted on a base plate 160.
Is provided. The receiver is arranged such that the beam emanating from the light emitting diode passes through the housing and the diffuser almost without interruption. To use in this embodiment,
A narrow beam light emitting diode with an elevation angle of about 25 degrees is suitable.
Modules with a star array of 3 to 6 photodiodes at 30 to 45 degrees elevation have shown good results.

17A and 17B show another embodiment of the present invention. 2A and 2B show a cross-sectional view and a plan view of a module whose beam pattern can be switched. Light emitting diode array 201
Is on the mounting table 203. The light emitting diodes 201 are symmetrically arranged below the hemispherical light scattering housing 200. When the housing is in position 1 with respect to light emitting diode 201 (right side in FIGS. 17A and 17B), light exits vertically from housing 200. Depending on whether this part of the housing is implemented as a diffuser, the beam pattern will converge or diverge. The housing 200 includes a reflection ring 202. Housing 200 or reflector ring 202
Is rotated relative to the diode 201 (position 2 on the left in FIGS. 17A and 17B), the light beam exiting the diode is reflected toward the transverse facet of the housing 200. This transverse facet usually comprises diffuser means for achieving beam expansion. FIG. 17B shows that the reflective ring 202 can be implemented as a ring with several “tongues”. Reflective ring 202 can be made using embossed or punched thin metal. In the example shown in FIGS. 17A and 17B, it is possible to switch from position 1 to position 2 by rotating 22.5 degrees.

18A and 18B show another concept of an optical transmitter module capable of switching a beam pattern. This module comprises an array of light emitting diodes 211 arranged in via holes or depressions in the mounting 213. The diode 211 is covered by a hemispherical diffuser housing 210. The housing 210 incorporates a reflection ring 212. This ring 212 comprises a tongue or cantilever bent so that the light beam emerging from the diode is reflected toward the side wall of the diffuser housing 210 (18A).
(See position 2 on the left side of the figure and FIG. 18B). When the housing with the reflective ring is rotated so that the diode 211 is no longer under the reflective tongue or cantilever of the ring 212, the light beam exits perpendicular to the mounting 213 (FIGS. 18A and 18B). (See position 1 on the right side of FIG. 18B).

19A and 19B show a fixture for mounting a module 220 with a switchable beam pattern. In FIG. 19A, the housing and the reflector ring are in position 2, ie the light beam is emitted in all directions and the transmitter emits as indicated by the arrow. In FIG.19B, module 220
And the fixture 211 is open, the module is in position 1, ie the module emits light perpendicular to the mounting of the diode. This fixture 221 allows direct line-of-sight communication when the module is in position 1 and faces the remote receiver.

FIG. 20 shows another configuration of the switchable transmitter module. In this embodiment, the center axis of the diode 221 is inclined about 25 degrees with respect to the mount 223. When the hemispherical housing 220 is in position 1 (see right side of FIG. 20), the light beam passes through the housing as shown. In position 2, the reflector 222 is placed in front of the light emitting diode 221 and the light beam is reflected upward (see the left side of FIG. 20). In this example, the reflection plate 222 is a thin metal plate having an inclination angle of about 58 degrees. The reflector may be supported by a metal ring incorporated into or fixed within the housing 220.

The reflecting rings shown in FIGS. 17, 18 and 20 can be replaced by prism rings. The ring can be made of plastic and supports a series of shaped and arranged prisms so that different beam emission patterns are obtained depending on the position of the prism ring with respect to the light emitting diodes. This prism ring
It may be an integral part of a hemispherical housing. Various approaches are conceivable, such as rotating the housing supporting the prism or reflecting ring with respect to the position of the diode, rotating the ring itself with respect to the housing and the diode, or rotating the diode itself.

The reflector in FIGS. 11 and 12 can also be replaced with a "ring" or metal ring supporting the cantilever as described in connection with FIGS. 17, 18, and 20. In this case, the only difference to the switchable module is that the metal ring is fixed (not to rotate).

FIGS. 21A and 21B show two different mounting or mounting schemes of the transmitter module and transceiver module of the present invention for a notebook computer.
The optical transmitter or transceiver module described herein must not be obstructed in near field by the computer housing or display panel to which it is mounted or incorporated. FIG. 21A shows a notebook computer 170 with a removable optical transmitter / receiver module 171. This module 171 is attached to the computer 170 with a magnet or Velcro clip 172. Module 171, cable
At 173, it is interconnected with an interface card plugged into one of the computer slots. In FIG. 21B,
Shown is a computer 174 with a built-in module 175. This module is integrated into the display device, and the electrical interconnects and their interface circuits are located inside the computer. This module 175 can be extendable.

FIG. 22 shows a block diagram of a specially designed analog front-end circuit. This circuit comprises a preamplifier 180 coupled to each photodiode of the photodiode array 181 as a receiver. The switches 182, together with the switch control unit 183, help select the signal received at each photodiode. All or part of the received signal is forwarded to post-amplifier 184,
Next, it is sent to the comparator 186 via the filter 185. This block diagram includes a proximity detection unit. For proximity detection, the photodiode 1
Observe the echo signal received at 81. When the echo signal exceeds a predetermined level, the power of the light emitting diode 187 is automatically turned off. This active safety interlock is achieved by a peak signal detector 188 coupled to the output of preamplifier 180 by a bus consisting of n parallel lines. The control circuit 190 analyzes the received signal and detects a strong echo signal. Then the driver will not emit any more light
Switch 191 immediately. The control circuit 190, together with the DC photocurrent detector 189 and the switch control unit 183, allows for automatic selection and / or combination of signals.
This choice takes into account the actual signal strength of the photodiode 181 and / or direct current (a measure of shot noise received from a directional ambient light source such as sunlight or a table lamp).

The entire analog front end is
Microprocessor via unit 192 (PCMCIA)
Connected to bus 193.

The optical transmitter modules and transceiver modules presented herein are optical systems that are eye safe and have several other advantages. These modules are compact and suitable for incorporation into computers and other devices. The module of the present invention can be easily attached to any notebook computer. This module features optimal and substantially uniform annular radiation characteristics and can be switched in some embodiments. This module allows for efficient distribution and reception of optical signals with limited power in order to obtain the maximum transmission distance. An analog front end as shown in FIG. 18 can suppress strong directional ambient light. The module of the present invention differs from conventional transmitters in that the total shot noise generated is small, thereby improving the signal to noise ratio and transmission coverage.
Further, there is no need to align the transceiver module. One particular embodiment of the present invention facilitates two transmission modes: spreading and / or line-of-sight communication.

The transmitter module and the transceiver module of the present invention comply with IEC 825-1 rules. This can be achieved by an apparently sufficiently large light source and / or by an active safety interlock if the person's head gets too close to the light emitter.
As described above, this interlock mechanism detects a strong reflected echo signal generated by a nearby object with the photodiode of the light emitting / receiving transceiver module (proximity detection).

The invention is designed to optimize the transmission range for a given data rate (from table lamps, windows, direct sunlight).
Strong effectiveness Provides automatic mechanism to block ambient light. This function can be implemented by selectively combining (sectoring) individual photodiodes pointing in different spatial directions and selecting the largest possible signal-to-noise ratio.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Weiss, Beat Mühlestrasse, Etribach, Switzerland 35 (56) References JP-A-59-180582 (JP, A) JP-A-6-169288 (JP, A) Japanese Utility Model No. 5-82149 (JP, U) Japanese Utility Model No. 5-25753 (JP, U) Japanese Utility Model No. 2-54107 (JP, U) Japanese Utility Model No. 63-12037 (JP, U) Japanese Utility Model No. 63-40048 (JP, U) JP-A 63-64142 (JP, U) JP-A 62-88639 (JP, U) WO 94/2873 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , (DB name) H04B 10/00-10/28 H04J 14/00-14/08 H01L 33/00

Claims (15)

(57) [Claims] 1. An optical data transmission module comprising an array of a plurality of infrared light emitting diodes symmetrically arranged in a cavity formed by a hemispherical housing with diffuser means, said hemispherical housing. Comprises a series of reflectors arranged annularly on the inner surface of the housing, and a deflecting prism, wherein the hemispherical housing is rotatable relative to the array, and the light emission for the reflectors and prisms A module, wherein the radiation pattern of the module can be switched according to a relative position with respect to the diode array. 2. The module according to claim 1, wherein the light emitting diodes are arranged so as to be radially outward with respect to a central axis of the hemispherical housing. 3. The module according to claim 1, wherein said hemispherical housing comprises high-refractive-index suspended particles functioning as diffuser means. . 4. A method according to claim 1, wherein said hemispherical housing has a corrugated surface on its inner surface and / or outer surface which functions as a diffuser means. A module according to. 5. The module of claim 4, wherein said corrugated surface has a roughness such that it matches the wavelength emitted by the light emitting diodes of the module. 6. The method of claim 1, wherein said hemispherical housing has a checkerboard pattern on its inner surface and / or outer surface that functions as a diffuser means. Module according to the section. 7. The module according to claim 1, wherein said hemispherical housing is rotatable stepwise with respect to said light emitting diode array. . 8. The module according to claim 1, further comprising a receiver having an array of photodiodes inclined with respect to a central axis of the housing. 9. The module according to claim 8, wherein said photodiode is located below said light emitting diode array in the same housing. 10. The module according to claim 8, wherein said photodiode is located above said light emitting diode array in the same housing. 11. A computer comprising: the optical transmitter module according to claim 1; and an interface means for coupling the module to a bus of the computer. 12. The computer according to claim 11, wherein said module is attached to a display panel of the computer by a clip and connected to said interface means by a cable. 13. The computer according to claim 11, wherein said module is fixedly or extendably incorporated into a display panel of the computer. 14. A photodiode array; b) an amplifier for amplifying signals received by the photodiode array; and c) information carried in the signals received by the photodiode array. Means for detecting; d) driver means for driving the infrared light emitting diode array of the module; e) means for actively selecting and separately combining the signals received by each photodiode of the photodiode array; f) means for determining the strength of the echo signal and performing proximity detection by disconnecting the infrared light emitting diode array of the module if the echo signal exceeds a predetermined limit. Item 10. A transceiver for wireless data communication used with a module according to any one of Items 10 to 10. 15. An amplifier for amplifying signals received by the photodiode array of the module; and b) means for detecting information carried in the signals received by the photodiode array of the module. C) driver means for driving the infrared light emitting diode array of the module; d) means for actively selecting and individually combining the signals received by each photodiode of the photodiode array of the module; e). Means for determining the strength of the echo signal and performing proximity detection by disconnecting the infrared light emitting diode array of the module if the echo signal exceeds a predetermined limit. Item 11. A transceiver for wireless data communication used with a module according to Item 10.