Method of pulsing light emitting diodes for reading fluorescent indicia, data reader, and system

• US 6,184,534 B1
• Filed: 08/04/1998
• Issued: 02/06/2001
• Est. Priority Date: 08/04/1998
• Status: Expired due to Term

• Current Assignee: Eapeiron Solutions Inc. (OEP Technologie BV)
• Original Assignee: Eastman Kodak Company
• Inventors: Bernardi, Bryan D., Nelson, David J., Stephany, Thomas M., Bryant, Robert C.
• Primary Examiner(s): Hannaher, Constantine
• Assistant Examiner(s): Gabor, Otilia
• Application Number:
  US09/128,881
• Time in Patent Office: 917 Days
• Field of Search: 250/458.1, 250/459.1
• US Class Current: 250/459.1
• CPC Class Codes: G06K 7/10584 Source control
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/12 using a selected wavelength, e.g. to sense red marks and ignore blue marks

Abstract

A system includes a data reader and media bearing fluorescent indicia. A method includes the steps of: pulsing a light emitting diode at a forward current level above continuous use operating limits to produce pulsed radiation within an absorption spectrum of the fluorescent material and at a flux density sufficient to induce a fluorescent emission from the indicia; illuminating the indicia with the pulsed radiation to produce the fluorescent emission; and imaging the indicia on a radiation image sensor sensitive to radiation within an emission spectrum of the fluorescence.

Claims

1. Method for reading an indicia of fluorescent material, said method comprising the steps of:

pulsing a light emitting diode at a forward current level above continuous use operating limits to produce pulsed radiation, said radiation being within an absorption spectrum of said fluorescent material and at a flux density sufficient to induce a fluorescent emission from said indicia;

illuminating said indicia with said pulsed radiation to produce said fluorescent emission; and

imaging said indicia on a radiation image sensor sensitive to radiation within an emission spectrum of said fluorescence.

2. The method of claim 1 wherein said pulsing further comprises pulsing a plurality of light emitting diodes at a forward current level above continuous use operating limits for each of said light emitting diodes to produce said pulsed radiation.

3. The method of claim 1 wherein said fluorescent emission is invisible.

4. The method of claim 1 wherein said fluorescent emission is infrared radiation.

5. The method of claim 1 wherein said pulsed radiation has a duty cycle of about 1 percent.

6. A data reader for reading indicia of fluorescent material, said data reader comprising:

a body;

an image sensor held by said body, said image sensor being sensitive to said indicia radiation images;

a light emitting diode held by said body;

a power unit disposed in said body, said power up it driving said light emitting diodes with a pulsed forward current at a level above continuous use operating limits for said light emitting diode.

7. The data reader of claim 6 further comprising t plurality of light emitting diodes and wherein said power unit drives each of said light emitting diodes with a pulsed forward current at a level above continuous use operating limits for said light emitting diodes.

8. The data reader of claim 6 further comprising an optical system imaging on said image sensor.

9. The data reader of claim 6 wherein said image sensor is sensitive to a band of invisible radiation.

10. The data reader of claim 6 wherein said image sensor is sensitive to a band of infrared radiation.

11. The data reader of claim 6 wherein said body has a handle.

12. A system comprising a combination of the data reader of claim 6 and media bearing indicia of fluorescent material, wherein said image sensor is sensitive to radiation within a fluorescence emission spectrum of said fluorescent material.