Optical encoding and readout system using a liquid crystal modulator to encode light with an object's identification code and related sensor data

• US 5,532,470 A
• Filed: 10/18/1994
• Issued: 07/02/1996
• Est. Priority Date: 10/18/1994
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Frank, David A.
• Primary Examiner(s): Hajec, Donald T.
• Assistant Examiner(s): Wigmore, Steven
• Application Number:
  US08/325,000
• Time in Patent Office: 623 Days
• Field of Search: 235/454, 235/491, 235/492
• US Class Current: 235/491
• CPC Class Codes: G06K 7/10831 Arrangement of optical elements, e.g. lenses, mirrors, prisms optical elements per se G02B

Abstract

An optical data encoding and readout system for identifying an object and providing sensor data related to the condition of the object includes a liquid crystal cell for receiving a polarized readout beam. A control circuit reads identification and sensor data codes stored in a predetermined format in memory, and modulates the liquid crystal cell in accordance with the codes which in turn modulates the polarization of the readout beam.

Claims

1. An optical data encoding and readout system for identifying an object, comprising:

a memory for storing a unique object identification code in a multi-bit binary bar code format;

a liquid crystal cell for receiving a polarized readout beam; and

a control circuit for reading out the identification code stored in said memory and modulating the orientation of the liquid crystals in said cell between binary orientations in accordance with the state of each successive bit in the identification code, said liquid crystal cell in turn modulating the polarization of said readout beam with said code, a light source that projects said polarized readout beam onto said liquid crystal cell within an approximately stationary orientation with respect to said liquid crystal cell.

2. The system of claim 1, wherein the polarization modulated readout beam is transmitted through a polarizer, which modulates the readout beam'"'"'s intensity in accordance with said identification code.

3. The system of claim 1, further comprising:

a sensor for providing object related data to said memory for storage in the memory as data codes in said binary bar code format, and said control circuit reading out said stored data to modulate the liquid crystals between binary orientations in accordance with the state of each successive data code bit.

4. The system of claim 1, wherein said source is a bar code wand reader.

5. The system of claim 1, further comprising a light source that illuminates the entire liquid crystal cell with said polarized readout beam.

6. An optical data encoding system for use with a bar code wand reader to identify an object, wherein the wand reader projects a readout beam which is modulated by the system, and decodes the intensity modulated beam, comprising:

a memory for storing a unique object identification code in a format that corresponds to a multi-bit binary bar code;

a liquid crystal cell for receiving the readout light beam;

a polarizer for polarizing the readout beam; and

a control circuit for reading out the identification code stored in said memory and modulating the liquid crystals in said cell between binary orientations in accordance with the state of each successive bit in the identification code, said liquid crystal cell in turn modulating the polarization of said readout beam with said code, and said polarizer modulating the beam'"'"'s intensity in accordance with the beam'"'"'s modulated polarization.

7. The system of claim 6, further comprising:

a sensor for providing object related data to said memory for storage in the memory as data codes in said binary bar code format, and said control circuit reading out said stored data to modulate the liquid crystals in accordance with the state of each successive data code bit.

8. The system of claim 6, wherein said wand reader projects a readout beam as a narrow beam that illuminates only a small portion of a front surface of said liquid crystal cell, said entire cell being modulated one bit at a time so that it can receive said narrow readout beam at different positions on its front surface and with different motions along said front surface while maintaining the modulation of said readout beam.

9. A long range data encoding and scanning system for identifying a plurality of objects, comprising:

a directable light source having a polarizer for selectively projecting a polarized readout beam;

a plurality of encoding units, each unit including a memory for storing a unique object identification code and object related data in a multi-bit binary bar code format, a liquid crystal cell for receiving the readout light beam, and a control circuit for reading out the identification code and the object related data stored in said memory and modulating the orientations of the liquid crystals in said cell in accordance with the state of each successive bit in the identification code and the object related data, said liquid crystal cell in turn modulating the polarization of said readout beam with said code and said data; and

a detector for receiving and decoding the modulated readout beam to identify the selected object and download said data.

10. The long range scanner of claim 9, wherein the projected readout beam follows a first path, further comprising:

a single corner reflector positioned behind said liquid crystal cell for reflecting the polarization modulated readout beam back through said cell on a second path parallel to the first path in order to accurately return the beam to the detector.

11. The long range scanner of claim 10, further comprising:

a polarizer for polarizing the projected readout beam; and

a mirror for directing the polarized readout beam on the first path to a selected one of the units, and for reflecting the modulated beam on the second path through the polarizer to the detector, and said polarizer modulating the beam'"'"'s intensity in accordance with the beam'"'"'s modulated polarization.

12. The system of claim 9, wherein said directable light source projects said polarized readout beam so that it illuminates the entire liquid crystal cell.

13. A method for reading out an identification code from an encoding unit that includes a memory for storing the unique object identification code in a multi-bit binary bar code format, a liquid crystal cell,and a control circuit for reading out the identification code stored in said memory and modulating the orientations of the liquid crystals, comprising:

holding a bar code wand reader up to the liquid crystal in an approximately stationary position to project a readout beam through the liquid crystal cell;

activating said control circuit so that it reads out the identification code and modulates the orientations of all of the liquid crystals in said cell in accordance with the state of each successive bit in the identification code, said liquid crystal cell in turn modulating the polarization of said readout beam with said code; and

reflecting said modulated readout beam off of a reflector back through said cell and into said bar code wand reader.

14. A method for reading out a plurality of identification codes from remote encoding units that each include a memory for storing a unique object identification code in a multi-bit binary bar code format, a liquid crystal cell,and a control circuit for reading out the identification code stored in said memory and modulating the orientations of the liquid crystals, comprising:

selectively projecting a polarized readout beam to illuminate the entire liquid crystal cell in successive ones of said encoding units; and

activating the control circuit associated with the illuminated cell so that the control circuit reads out the identification code and modulates the orientations of all of the liquid crystals in said illuminated cell in accordance with the state of each successive bit in the identification code, said liquid crystal cell in turn modulating the polarization of said readout beam with said code.