WO1998020684A2

WO1998020684A2 - Communication system by diffused infrared rays

Info

Publication number: WO1998020684A2
Application number: PCT/BR1997/000058
Authority: WO
Inventors: Paulo Cesar FARACO GUIMARÃES
Original assignee: H2T Handheld Technology Ltda.
Priority date: 1996-10-17
Filing date: 1997-10-17
Publication date: 1998-05-14
Also published as: AU4696397A; WO1998020684A3; BR9605275A

Abstract

Patent of invention of a 'COMMUNICATION SYSTEM BY DIFFUSED INFRARED RAYS' which uses the non-directionals infrared rays obtained through the geometry of position of infrared transmitters and receivers and their characteristics of 'design' and transmission power chosen and the conception of the electronics circuits, showing at minimum one diffuse infrared transceiver (1) which has a minimum one led with half angle of transmission of around 15 grades and a minimum one led with half angle of transmission of approximately 35 grades installed in one board (21) with angle approximated of 30 grades made in relation to the perpendicular line to board (21 - A-A') and the transversal line from the minor base (19) and a minimum one communication processor (2) has one RISC microcontroller (4), this one having internally DRAM, ROM and DMA memories controllers and asynchronous serials interfaces, with the EPROM BOOT memory (4a), FLASH memory (4b) and dynamical RAM memory (4c), interface Ethernet 10baseT kind (3a) implemented using a controller (3b) and a transformer (3c) specific to this reason.

Description

COMMUNICATION SYSTEM BY DIFFUSED INFRARED RAYS

The present invention is in respect of the domain of the data communication, through wireless equipment, to applications in an indoor environment.

The research about the communication facilities is growing up constantly in the last years, trying to get the exigency of the businesses, where the personal communication mobility is a relevant fact. In this matter, examples like the wireless telephone for domestic use, the cellular telephone, the notebooks with modules of inlaid communication, and many others that demonstrate the seek of the symbiosis mobility- communication.

The frequency-radio in its several forms has been utilized to promote such mobility to the wireless communication equipment. However, in spite of the evidence benefit brought to the current days, it also brings several problems that get worst in which the use of this technology is growing more and more.

Problems such as interference electromagnetic, high radiation, broadcast difficulties of reception and transmission in an indoor environment, such as buildings, high vulnerable about the secrecy of the information transmitted, are some of the problems found.

The present invention has as its objective to develop a system of wireless communication, basically directed to applications in an indoor environment. In view of the several applications directed to the system, it was in search of a trustful solution, robust, i.e., immune to the electromagnetic interference, and specially characterized by the mobility it makes possible to the user to move inside the environment without any limitation. The distances included must attend an indoor environment such small as large.

The solution to solve the problems about the use of radio waves is the adoption of the infrared waves, where by its inherent characteristics, the requirements of immunity to electromagnetic interference and robust are reached. However, the use of such transmission mechanism of the data has an inconvenience, the fact that the transmitter must be directed to the receiver. The adoption of such solution configures in a hard way to certain applications, for example in the Floor of Stock Exchange.

The current invention has by object a data transmission system that uses the Infrared ray, without the necessity of directs the transmitter to the receiver. The solution is based in the use of the transmission of Infrared optical signal non-directional, got through the geometry of position of Infrared transmitters and receivers, their characteristics of "design", the power of transmission and the conception of the electronics circuit.

The system can be better understood in the description, which follows, and in the draws that follows with the current descriptive report.

The system is constituted by a communication processor and a diffuse infrared transceiver, or in a complex configurations, by a "cluster" of processor and several transceivers. The communication processor is connected to a diffuse infrared transceiver, that supplies the coverage of transmission and reception in indoor environments. The processor, by one side, is connected to a network like Ethernet and it has an interface of the l ObaseT kind, using TCP/IP protocol of communication, becoming possible the communication with other equipment, like computers, work stations, etc.

In the other hand, the processor has a communication door to the diffuse infrared transceiver, through the RS-485 interface. Of this door set out the only cable up to the interface, transporting power and digital signal in a completely isolate way inside of the same mechanic set. The communication processor is responsible for all the modulated and demodulated of the signal which are sent to/or received of the diffuse infrared transceiver.

The diffuse infrared transceiver, is responsible for the transformation of modulated Digital's electrical signal by the communication processor in diffuse infrared optical signals to the transmission, as well the transformation of the infrared signals caught by photodiode in eletricals signal, that will be send to the communication processor to be demodulated. The diffuse infrared transceiver is an external unit to the communication processor, offering a high flexibility in terms of the place of installation, for example in the ceiling of a room.

The figure 1 represents an example that it's not a basic limitation of

the system, where the transceiver (1) is connected to the communication processor (2), and where the interface lObaseT kind, to be connected to the network like Ethernet (3), can be visualized. The diffuse infrared communication, in the example, is made with an 850nm-wave extension, ASK modulation, bearer of 800Khz, transmission tax of 250 Kpps, half- duplex, NRZI signalizing and synchronous communication protocol orientated a bit.point-multipoint.

The communication processor can be better describe with the help of the figure 2 that represents the block diagram.

The communication processor has a RISC microcontroller (4) and has the controller and processing function. This one has internal ROM and DRAM memory controllers and asynchronous serial interfaces.

The EPROM BOOT memory (4a) is knowledge of the prior art and has the program that is executed when the processor is started. Its function is to manage the loading of new versions of application programs or even of the operational system through the network like Ethernet.

The FLASH (4b) memory has the multitasks real time operational system and also the application program. New versions can be loaded any time, without the necessity of changing the components.

The dynamical RAM memory (4c) is used to temporary storage of the data and tables used by the operational system and application programs.

The interface Ethernet lObaseT kind (3a) is implemented using a controller (3b) and a transformer (3c) specific to this reason. To become easier the test process of the communication processor (2), were used two asynchronous serials interfaces, of which are presents inside the RISC microcontroller (4). The controllers of Universal Serial Communication USC were adopted by the reason of the diffuse infrared communication to be implemented in a synchronous form and oriented to bit. In the communication processor (2) were foreseen five channels to reception and one channel to transmission, so they used 3 USCs (5a, 5b, 5c), because each one has two channels of reception/transmission. The ASK modulator (6) transforms all bits with "zero" value in a pulse train of 800 Khz. In relation to the bits with "one" value, nothing is done. The modulated signal is sent to the diffuse infrared transceiver throughout the RS-485 interface (6a).

The ASK demodulated (7) receive the modulated signal which comes from the diffused infrared transceiver throughout the RS-485 interfaces (7a) and it has an inverse function in relation to the modulator

(6), otherwise, it transforms the pulse train of 800 kHz in "zero" value and if not detect 800Khz, transforms the signal in "one" value.

The power source (8) connected to the equipment gives all the necessary tension to the circuit. To allow the concatenation between several communication processor (2), the equipment was favored of another specific RS-485 interface to this end.

The figure 3 is showing the system with several diffused infrared

trnsceiver and several interconnected communication processor. In the case showed in the figure 1 , the communication processor (2) has of a RISC microcontroller (4) of 32 bits with a clock of 16 MHz and source of 5V, with RAM memory (4c) of 2 MB and FLASH memory (4b) of 2 MB or 4 MB, five 250 KBPS synchronous interfaces in RS-485 to the reception of the data of the infrared transceiver, and one 250 KBPS synchronous interface in RS-485 to the transmission of the data to the infrared transceiver. An external asynchronous interface with 19.200 BPS and an internal asynchronous interface with 19.200 BPS used for tests. The communication interfaces to concatenation to other processor and to connect with the diffused infrared transceiver are RS-485 kind, and to network communication, the interface Ethernet kind, lObaseT. The source of 110V ac and power of 20 .

The processor is favored of indicative leds of turn on/turn off, of the infrared transmission and reception, of the network status and of thelObaseT connector polarity. The operational system of multitask real time is located in FLASH memory, with the possibility of loading of new versions of application programs and its own operational system throughout the Ethernet network kind.

The diffuse infrared transceiver (1) will be better understanding with the help of the blocks diagram showed in the figure 4.

The modulated signal that comes from the communication processor (2) through the RS-485 (9), pass through a module of power (10), that allows it to maintain infrared transmitter leds. The photodiodes (12) receive the infrared light and transform it in tension, which is amplified by the amplifier modules (13), transformed in digital signal and then sent to the communication processor (2), through RS-485 (14) where will be demodulated. The power source (15) connected gives all the tensions to the working of the circuits.

In an explanatory way, the technical specifications of the diffuse infrared transceiver can haveδ (five): 250 KBPS synchronous interfaces in RS-485 to the transmission of the modulated signal of the infrared transceiver (1) to the communication processor (2), and an 1 (one) 250 KBPS synchronous interface in RS-485 to the reception of the modulated signals coming from the communication processor (2). The power source, in 110V ac, with power of 20W, is supplied by the only cable (16) which connect the communication processor (2) to the diffuse infrared transceiver (1).

The infrared transceiver (1) has its characteristics of diffusion of the infrared light improved by the distribution and angles of the transmitter leds and infrared receivers.

The figure number 5 is showing the distribution of the transmitter and the receivers of the infrared transceiver (1).

The diffusion of the infrared communication is the result of the combination of several elements, by distribution, angles, kind of transmitter leds and infrared receivers and photodiode transmission power utilized in the infrared transceiver (1). The infrared transceiver (1) has the appropriate form of a flatten semisphere, according to the figure number 5. This form is given by the optical communication filter (17), which must have its tonality performing like a filter of the visible light, avoiding optical interference and is also a protection to the transmitter leds and to the infrared receivers photodiodes. This filter (17) is fixed to a standard circular base. Also fixed on such base, but inside the filter, is the support to the plates that contain the transmitter and the infrared receptors. This support (18) has a escale factor in a shape of a cone's trunk, with one opening on the smaller base (19) and four openings on its inclined plane (20) as showed in the figure 5. On these openings are installed plates (21) that contain 12 transmitters each one (21a) and 1 receiver (21b), as we can see in the fugure 6.

Imagining a perpendicular line crossing each plate (A-A'), we have an angle of 30 grades between the plate line localized on the smaller base and the plates localized on the cone's trunk inclined plane. When the infrared transceiver (1) be installed on an indoor enviroment ceiling, the plate localized on the smaller base of the cone's trunk (21c) will stay parallel to the ceiling.

Despising the dimensions of the infrared transceiver (1), and supposing that in each plate exist transmitters completely directional , we can say hipoteticaly, that the transmitted rays could reach 5 points in the enviroment floor. These points will be set at intervals from the central point by the distance of

h.sen ∞ where "<x" is the inclined plate angle, in this case 30 grades, and "h" is the

height where the infrared transceiver is installed.

To reach the difusion infrared rays, from the total of 12 leds used in each plate, 8 have half angle of transmitters of 15 grades (they have a less spread energy) and so we will obtain a infrareds' signals cone, with height "h" and the radius base equal as

h.sen β

where "h" is height of the satallite and "β" the inclined angle of the plates

(30 grades) added to the half transmission angles of leds (15 grades), so, "β" is 45 grades and the cone's radius base value will be 0,7h.

To increase more the diffusion of infrared rays, were installed in each plate, besides 8 leds of half transmition angle of 15 grades, more 4 leds with half tranmition angle of 35 grades (large spread energy) These leds have the objective of "spread out" more infrared rays, so the spaces out of the cone, before written, could be reached.

Also cooperate in the diffusion infrared the reflection capacity of the infrared rays in clear obstacles, for example, the indoor enviroment walls. This reflection is not perfect and a little infrared energy is absorbed by these obstacles. To these reflected rays have enough energy to be utilized, it is necessary a potency of transmition sufficiency high to do so. On the other hand, there is a limit to this potency to not damage the transmitters leds. It is advisable a potency of 200mW for each led, that attend the necessities of the reflection system. The infrared receiver (21b) localized on the plates that make part of the infrared transceiver (1) represents also a important point for a good function of the system. To be possible to catch signals with a short energy in view the long course or that have been reflected, must have high sensibility. Besides that, a large reception angle in relation to its surface is advisable. The photodiode (21b) has the capacity to identify incident infrared signals in approximately 80 grades in relation to its surface. This angle is raised up more by the use of the optical communication filter (17), that shows an effect of lens. The photodiode has a sensible area of 60mm2 in a square format. Another characteristic about the infrared receiver is the gain of internal amplification of 10.000 times to the standard photodiodes. All the sensor set (photodiode) and ampliffier is specially wrapped in a monolithic encapsulation.

The figures 6 and 7 are showing, in a perpective view, the characteristics of infrared transceiver (1).

To attend large areas, more complex configurations formed by a processors "cluster" and several tranceivers can be done.

The figure 3 is showing a synchronized architeture, built from the concatenation of several communication processors (2) mounted subrack in 19 inches standard. The amount of diffuse infrared transceivers (1) will be proportional to the quantity of communication processors (2), in the reason from one to another. The concatenation of the communication processors is done through the RS-485 interface (Fig 2,22) been the others technical identical specifications. The synchronized architecture is based on the election of a communications processors as been the transmission master, making all the transceivers (1) send at the same time the information, allowing the total mobility of the user in dislocating inside the indoor enviornment served by a series of diffuse infrareds transceivers.

The modulated concept about the product gives a large flexibility of applications, with a large variety of possible configurations, been possible deslocate the diffuse infrared transceiver (1) to separate indoor enviornment. By this reason, the exemples given in this descriptive report are not limited, and are only to show one of the possible ways and architecture of the communication system by diffuse infrared ray.

Claims

1. "COMMUNICATION SYSTEM BY DIFFUSED INFRARED

RAYS" characterized by use of non-directional infrared ray.

2. "COMMUNICATION SYSTEM BY DIFFUSED INFRARED RAYS" according to the claim 1., characterized by diffusion to be obtained through the geometry of position of infrared transmitters and receivers and their characteristics of "design" and power.

3. "COMMUNICATION SYSTEM BY DIFFUSED INFRARED RAYS" according to the claim 1 , characterized by a minimum of one infrared ray transmission led (21) and a minimum one photodiode (21a) of reception, booth non-directionals.

4. "COMMUNICATION SYSTEM BY DIFFUSED INFRARED RAYS" according to the claim 1 , characterized by a minimum of one diffuse infrared transceiver (1) and a minimum one communication processor (2).

5. "COMMUNICATION SYSTEM BY DIFFUSED INFRARED

RAYS" according to the claim 2, characterized by the diffuse infrared transceiver (1) to own a minimum one led with half angle of transmission of approximately 15 grades and a minimum one led with half angle of transmission of approximately 35 grades installed in one board (21) with an angle approximated of 30 grades made in relation to the perpendicular line to board (21 - A-A) and the transversal line from the minor base (19).

6. "COMMUNICATION SYSTEM BY DIFFUSED INFRARED

RAYS" according to the claim 2, characterized by diffuse infrared transceiver (1) to own the shape like a flatten semisphere given by the optical communication filter (17) which is fixed to a one circular base where it was also found fixed, but internally to the filter, the boards supports (18) with a shape of scaled factor in a shape of cone's trunk, with one opening at minor base (19) and four openings in your inclined plan (20), where the boards are installed (21 and 21c) which each one contain 12 transmissors (21a) and 1 receiver (21b).

7. "COMMUNICATION SYSTEM BY DIFFUSED INFRARED

RAYS" according to the claim 2, characterized by the communication processor (2) has one RISC microcontroller (4), this one having internally DRAM, ROM and DMA memories controllers and asynchronous serials interfaces, with the EPROM BOOT memory (4a), FLASH memory (4b) and dynamical RAM memory (4c), interface Ethernet lObaseT kind (3a) implemented using a controller (3b) and a transformer (3c) specific to this reason.

8. "COMMUNICATION SYSTEM BY DIFFUSED INFRARED RAYS" according to the claim 7, characterized by the ASK modulator (6) transform all bits with "zero" in pulse train of 800 khz and send it to the diffuse infrared transceiver through the RS-485 interface (6a), and anything to do with the bits with "one" value.

9. "COMMUNICATION SYSTEM BY DIFFUSED INFRARED

RAYS" according to the claim 7, characterized by the ASK demodulator (7) received the modulated signals which came from of diffuse infrared transceiver (2) through of RS-485 interfaces (7a) and transform the pulse train of 800khz in a "zero" value and if don't detect 800khz, transform it in "one" value.