Infrared beam steering system using diffused infrared light and liquid crystal apertures

• US 5,528,391 A
• Filed: 06/04/1993
• Issued: 06/18/1996
• Est. Priority Date: 06/04/1993
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Elrod, Scott A.
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Duong, Tai V.
• Application Number:
  US08/071,788
• Time in Patent Office: 1,110 Days
• Field of Search: 359/36, 359/39, 359/54, 359/53, 359/48, 359/155, 359/157, 359/159, 359/172, 250/351
• US Class Current: 349/1
• CPC Class Codes: G01S 17/74 Systems using reradiation of electromagnetic waves other than radio waves, e.g. IFF, i.e. identification of friend or foe
• CPC Class Codes: H04B 10/1149 Arrangements for indoor wireless networking of information
• CPC Class Codes: H04B 10/40 Transceivers

Abstract

A system for scanning a room to find the location of target devices, and then locking onto them with stationary directed beams for two-way communication. In one embodiment, a base system in each room comprises an IR source/receiver combination plus an LCD display panel which covers the source/receiver and is addressed in such a way as to open up dynamic apertures through which IR radiation in a scanning mode can be directed toward any particular location in the room. When a device at that location senses that it is being irradiated by the base station, the targeted device responds by emitting a coded packet of IR pulses. This system takes advantage of the higher bandwidth communication that can be obtained with point-to-point communications, while still allowing for multiple devices at arbitrary locations in the same room.

Claims

1. A beam steering system comprising:

(a) a first device for generating and for receiving omni-directional optical radiation,

(b) multiple spaced second devices spaced from the first device and each comprising an optical detector and an optical emitter for establishing a communication channel with the first device,

(c) opaque means located adjacent to the first device and between the latter and all of the second devices and comprising means for selectively forming a transmissive aperture for said beam at different location in said opaque means in response to electrical signals,

(d) means connected to the first device and to the opaque means for generating electrical signals to the opaque means to cause a transmissive aperture to be opened at a position oriented such that only one of said second devices is aligned with and can communicate point-to-point via a communication channel with said first device.

2. The system of claim 1, wherein the optical radiation is infrared radiation, and the opaque means comprises an addressable LCD panel.

3. The system of claim 1, further comprising means for applying signals to said LCD to open up an aperture and to cause the aperture to scan across the LCD.

4. The system of claim 1, further comprising a omnidirectional receiver associated with the first device.

5. A beam steering system comprising:

(a) a first device for generating and for receiving a beam of infra-red optical radiation,

(b) a second device spaced from the first device and comprising an optical detector and an optical emitter,

(c) opaque means located adjacent to the first device and between the latter and the second device and comprising an addressable first LCD panel for selectively forming a transmissive aperture for said beam at different locations in said opaque means in response to electrical signals, whereby the optical beam can be caused to pass through said aperture only in certain directions oriented with said aperture, one of said locations causing the aperture to be aligned with the first and second devices,

(d) a second LCD display panel located over and covering the second device, and means for opening up an aperture in the second LCD display panel at selected locations of the panel.

6. The system of claim 5, further comprising means for applying signals to said first LCD panel to open up an aperture at a particular location.

7. The system of claim 5, further comprising means for applying signals to said first LCD panel to open up an aperture and to cause the aperture to scan across the LCD.

8. The system of claim 5, further comprising a omnidirectional receiver associated with the first device.

9. The system of claim 5, further comprising means for establishing a communication link between the first and second devices via a transmissive aperture in the opaque means.