Data transmission method and system thereof, portable terminal, and data receiver

• US 20060062099A1
• Filed: 08/16/2005
• Published: 03/23/2006
• Est. Priority Date: 08/27/2004
• Status: Active Grant

• Current Assignee: KDDI Corporation
• Original Assignee: KDDI Corporation
• Inventors: Usami, Masashi, Yazaki, Tomonori
• Granted Patent: US 7,565,082 B2
• Time in Patent Office: Days
• US Class Current: 369/44.110
• CPC Class Codes: H04B 10/1143 Bidirectional transmission
• CPC Class Codes: H04B 10/116 Visible light communication

Abstract

In a data transmission method according to an exemplary embodiment, a data transmitter, which is capable of outputting a dummy light for judging an optical axis and a signal light having a beam spread smaller than that of the dummy light on the same optical axis, outputs the dummy light for scan so as to go across a photoreceiving part of a data receiver. When the dummy light having a predetermined optical level or more is optically received, the data receiver informs the data transmitter of reception chance and prepares for receiving the data. The data transmitter outputs the data carried by the signal light to the data receiver according to the information indicating the reception chance from the data receiver. The data receiver receives the data by optically receiving the signal light from the data transmitter.

Claims

1. A data transmission method comprising:

scanning a dummy light from a data transmitter for judging an optical axis between the data transmitter and a data receiver, so that the dummy light goes across a photoreceiving part of the data receiver, the data transmitter further capable of outputting a signal light carrying data on the same optical axis, the signal light having a beam spread smaller than the dummy light;

sending a reception chance signal from the data receiver to the data transmitter and preparing for receiving the data in the data receiver, when the data receiver optically receives the dummy light having an optical level equal to or higher than a predetermined optical level;

outputting the signal light from the data transmitter responsive to the reception chance signal from the data receiver; and

receiving the data in the data receiver by optically receiving the signal light from the data transmitter.

2. The method of claim 1 further comprising outputting from the data receiver information indicating successful data reception, after the data receiver successfully receives the data from the data transmitter.

3. The method of claim 1 wherein optical power of the signal light is larger than optical power of the dummy light.

4. A data transmission system to transmit data through open transmission, the system comprising:

a data transmitter; and

a data receiver,

wherein the data transmitter comprises;

a laser light source to generate a signal light;

a dummy light source to generate a dummy light for judging an optical axis;

an optical system to output the signal light and the dummy light on the optical axis, and causing a beam spread of the signal light smaller than a beam spread of the dummy light;

a receiving circuit to receive a reception OK signal from the data receiver; and

a driving circuit to drive the laser light source to output the signal light for carrying the data responsive to the reception OK signal,

wherein the data transmitter is capable of causing the optical axis of the signal light and the dummy light scan across a photoreceiving part of the data receiver, and

wherein the data receiver comprises;

a photodetector to optically receive the dummy light and the signal light;

a level judging apparatus to judge a level of an electrical signal output from the photodetector;

a transmitting circuit to transmit the reception OK signal to the data transmitter when the electrical signal output from the photodetector has a level equal to or greater than a predetermined level responsive to a result from the level judging apparatus;

a data demodulating circuit for demodulating the electrical signal from the photodetector when the electrical signal output from the photodetector has a level equal to or greater than the predetermined level and obtaining the data included in the electrical signal; and

a reception result indicator to inform a user regarding reception result of the data.

5. The system of claim 4 wherein optical power of the signal light is larger than optical power of the dummy light.

6. The system of claim 4 or 5 wherein the data transmitter is a portable terminal.

7. A portable terminal to transmit data to a data receiver through open transmission comprising:

a laser light source to generate a signal light;

a dummy light source to generate a dummy light for judging an optical axis;

an optical system to output the signal light and the dummy light on the optical axis and to cause a beam spread of the signal light to be smaller than a beam spread of the dummy light;

a receiving circuit to receive a reception OK signal from the data receiver; and

a driving circuit to drive the laser light source to output the signal light for carrying the data responsive to reception of the reception OK signal by the receiving circuit.

8. The portable terminal of claim 7 wherein the portable terminal is a portable telephone.

9. A data transmission method to transmit data from a data transmitter to a data receiver through open transmission the data transmitter outputting a laser light not carrying the data in a data transmission standby state and outputting a signal light carrying the data responsive to a data transmission start instruction, the signal light also being a laser light, the method comprising:

swinging the data transmitter so that the laser light output from the data transmitter goes across a photoreceiving part of the data receiver;

transmitting a reception chance signal from the data receiver to the data transmitter and preparing for receiving the data in the data receiver responsive to reception of the laser light having a level equal to or greater than a predetermined optical level by the data receiver;

outputting the signal light from the data transmitter responsive to the reception chance signal from the data receiver; and

receiving the data in the data receiver by optically receiving the signal light from the data transmitter.

10. The method of claim 9 wherein the data receiver comprises a concave mirror to condense the laser light from the data transmitter and a photodetector to convert the laser light condensed by the concave mirror into an electrical signal.

11. The method of claim 9 wherein the data receiver comprises:

a condensing optical system;

a plurality of photodetectors disposed on a predetermined plane of the condensing optical system to convert the laser light into an electrical signal; and

an adder to add the electrical signals from the plurality of photodetectors.

12. The method of claim 9 further comprising outputting information indicating successful data reception responsive to successful reception of the data from the data transmitter by the data receiver.

13. A data transmission system to transmit data through open transmission, the system comprising:

a data transmitter; and

a data receiver,

wherein the data transmitter comprises;

a laser light source to generate a laser light;

an optical system to send out the laser light;

a receiving circuit to receive a reception OK signal from the data receiver; and

a driving circuit to drive the laser light source to carry the data responsive to reception of the reception OK signal from the data receiver by the receiving circuit; and

wherein the data receiver comprises;

a photodetector to convert the laser light into an electrical signal;

a condensing optical system to condense the laser light from the data transmitter into the photodetector;

a level judging apparatus to judge a level of the electrical signal output from the photodetector;

a transmitting circuit to transmit the reception OK signal to the data transmitter when the level of the electrical signal output from the photodetector is equal to or higher than a predetermined level;

a data demodulating circuit to prepare for demodulating the electrical signal from the photodetector when the level of the electrical signal from the photodetector is equal to or higher than a predetermined level to retrieve the data included in the electrical signal from the photodetector; and

a reception result informing apparatus to inform a user of reception result of the data.

14. The system of claim 13 wherein the condensing optical system comprises a concave mirror.

15. The system of claim 13 wherein the photodetector comprises a plurality of photoelectric converters and an adder to add the electrical signals output from the plurality of photoelectric converters.

16. A data receiver to receive data carried by a laser light from a data transmitter through open transmission, the data receiver comprising:

a photodetector to convert the laser light into an electrical signal;

a condensing optical system to condense the laser light from the data transmitter into the photodetector;

a level judging apparatus to judge a level of the electrical signal output from the photodetector;

a transmitting circuit to transmit a reception OK signal to the data transmitter when the level of the electrical signal from the photodetector is equal to or higher than a predetermined level;

a data demodulating circuit to prepare for demodulating the electrical signal from the photodetector when the electrical signal from the photodetector has a level equal to or higher than a predetermined level and retrieve the data included in the electrical signal; and

a reception result informing apparatus to inform a user of reception result of the data.

17. The apparatus of claim 16 wherein the condensing optical system comprises a concave mirror.

18. The apparatus of claim 16 wherein the photodetector comprises a plurality of photoelectric converters and an adder to add the electrical signals output from the plurality of photoelectric converters.

19. A method for optical open transmission of data from a data transmitter to a data receiver, the method comprising:

transmitting a first signal light from the data transmitter toward the data receiver;

locating an optical axis of the first signal light suitable for optical open transmission between the data transmitter and the data receiver;

transmitting a reception OK signal from the data receiver to the data transmitter responsive to the first signal light;

transmitting a second signal light from the data transmitter to the data receiver responsive to the reception OK signal, the second signal light including the data; and

generating an output indicating start and stop of transmission of the data to a user.

20. The method of claim 19, further comprising:

transmitting a dummy light from the data transmitter to the data receiver, the dummy light having a same optical axis as the first signal light and a wider beam spread than the first signal light,

wherein the reception OK signal is transmitted from the data receiver to the data transmitter responsive to the dummy light.