Symbol reading device including optics for uniformly illuminating symbology

• US 6,105,869 A
• Filed: 10/31/1997
• Issued: 08/22/2000
• Est. Priority Date: 10/31/1997
• Status: Expired due to Term

• Current Assignee: Microscan Systems Inc (Omron Corporation)
• Original Assignee: Microscan Systems Inc (Omron Corporation)
• Inventors: Scharf, Bruce R., Fisher, Donald S.
• Primary Examiner(s): Le, Thien M.
• Assistant Examiner(s): St. Cyr, Daniel
• Application Number:
  US08/961,581
• Time in Patent Office: 1,026 Days
• Field of Search: 235/454, 235/436, 235/455, 235/459, 235/471, 235/473
• US Class Current: 235/454
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10742 including a diffuser for diffusing the light from the light source to create substantially uniform illumination of the target record carrier

Abstract

A device and method for uniformly illuminating bar codes and two dimensional symbologies. An illumination source is mounted within the device to flood an area congruent with the field of view of the imaging optics with light to be reflected off of a code symbol. The imaging optics collects the reflected illumination received back through the window and images the same on a detector focal plane. An array of solid state light-emitting diodes are disposed adjacent to the imaging optics and a diffuser is placed between the emitters and the device window for illumination source. The emitters and diffusers are spatially arranged so as to cause homogenous distribution of light energy beyond the window and congruent with the field of view of the imaging optics.

Claims

1. A device for reading optical code symbols, comprising:

a device casing having an open front end;

a charge coupled device image sensor having a focal plane and mounted within the device casing, the charge coupled device image sensor operable to sense optical energy reflected from the optical code symbol and provide data signals responsive to the sensed optical energy;

an imaging lens optics assembly positioned and mounted within the device casing so as to form an image on the focal plane of the charge coupled device image sensor;

a plurality of light emitting diodes mounted circumferentially to the imaging lens optics;

a plurality of collimators, each collimator positioned adjacent a respective one of the light emitting diodes and operable to provide collimated optical energy responsive to optical energy received from the adjacent light emitting diode; and

a plurality of light diffusers, each light diffuser positioned adjacent a respective one of the collimators and operable to provide diffused optical energy responsive to collimated optical energy received from the adjacent collimator, the diffusers collectively operable to illuminate with diffused optical energy respective optical code symbols moving at high speeds relative to the device casing, the diffused optical energy having sufficient power to enable the image sensor to sense optical energy reflected from the optical code symbol and provide data signals containing information about the sensed optical code symbol.

2. The device of claim 1, wherein each diffuser is integral with the corresponding collimator.

3. The device of claim 1, further comprising a plurality of polarizers, each polarizer disposed adjacent a respective light emitting diode so as to polarize the light emitted by right emitting diode.

4. The device of claim 3, wherein each polarizer is integral to the corresponding collimator.

5. The device of claim 1, wherein each collimator is integrally formed with the corresponding light emitting diode.

6. The device of claim 1 wherein the high speed of the optical code symbols results in respective code symbols having exposure times within the range of 0.1 milliseconds to 125 milliseconds.

8. The device of claim 2, wherein said plurality of collimating lenses are diffractive lenses.

9. The device of claim 2, wherein said plurality of collimating lenses are refractive lenses.

10. The device of claim 2 wherein the light diffuser comprises a plurality of diffusers, each diffuser positioned adjacent a respective one of the collimators to diffuse light received from the adjacent collimator.

11. The device of claim 10 wherein each diffuser is integrally formed with the corresponding collimator.

7. A device for reading and decoding optical code symbols comprising:

device casing having an open front end;

charge coupled device image sensor having a focal plane and mounted within said device casing;

imaging lens optics positioned and mounted within said device casing so as to form an image on the focal plane of said charge coupled device image sensor;

plurality of light emitting diodes mounted circumferentially to said imaging lens optic;

collimator positioned relative to said light emitting diodes wherein said collimator has a plurality of collimating lenses so as to produce a field of illumination substantially congruent to the field of view of said imaging lens optics; and

light diffuser positioned between said light emitting open front end of said device casing.

12. A device for reading optical code symbols comprising:

an image sensor;

an imaging lens optics assembly positioned so as form an image on said image sensor;

a plurality of illumination sources mounted circumferentially to said imaging lens optics; and

a plurality collimators, each collimator positioned adjacent a respective one of the illumination sources and operable to provide collimated optical energy responsive to optical energy received from the adjacent illumination source, the collimators collectively operable to illuminate with collimated optical energy respective optical code symbols moving at high speeds relative to the image sensor, the collimated optical energy having sufficient power to enable the image sensor to sense optical energy reflected from the optical code symbol without blur and provide data signals containing information about the sensed optical code symbol.

13. The device of claim 12 wherein the image sensor comprises a charge-coupled device.

14. The device of claim 12 wherein each of the illumination sources comprises a light emitting diode.

15. The device of claim 12 wherein each of the collimators comprises a Fresnel lens.

16. A method for reading an optical code symbol moving at a high speed relative to a fixed reference point, comprising:

receiving a plurality of optical energy groups, each optical energy group including light rays from a corresponding illumination source;

respectively collimating light from each of the optical energy groups to provide a plurality of collimated light groups;

respectively diffusing the collimated light groups to provide a plurality of diffused light groups;

applying light from each of the diffused light groups to the optical code symbol, the light from each diffused light group illuminating a portion of the optical code symbol;

sensing optical energy reflected from the optical code symbol responsive to the applied light from the diffused light groups; and

detecting information contained in the optical code symbol from the sensed optical energy.

17. The method of claim 16 wherein light in each diffused light groups is polarized before being applied to the corresponding portion the optical code symbol.

18. The method of claim 16 wherein respectively collimating light from each of the optical energy groups to provide a plurality of collimated light groups comprises respectively refracting optical energy in the optical energy groups to thereby respectively collimate light in each of the optical energy groups.