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LED printbars with depth of focus enhancement

Imported: 23 Feb '17 | Published: 22 Oct '02

George A. Charnitski, Thomas J. Hammond, Donald E. Wiedrich

USPTO - Utility Patents

Abstract

A printbar assembly comprised of an array of light emitters, and array of gradient index lenses, and a light control film. The light control film, which is comprised of a plurality of microlouvers, is disposed such that it limits the angle at which light from the light emitters can enter the gradient index lenses. The light control film increases the depth of focus of the gradient index lens array without significantly reducing the effective radiometric efficiency.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Other aspects of the present invention will become apparent as the following description proceeds and upon reference to the drawings, in which:

FIG. 1 illustrates a prior art lens L

1 and the relationship between that lens's aperture, focal length, and depth of focus;

FIG. 2 illustrates a prior art lens L

2 and the relationship between that lens's aperture, focal length, and depth of focus;

FIG. 3 schematically depicts a prior art LED printbar having a gradient lens array;

FIG. 4 schematically depicts an LED printbar according to the principles of the present invention;

FIG. 5 schematically depicts a section of light control film; and

FIG. 6 schematically depicts a single pass, four color electrophotographic printing machine which incorporates the principles of the present invention.

Claims

1. A printbar assembly comprised of:

2. The printbar assembly according to claim 1, wherein said light control film is disposed between said array of light emitters and said array of gradient-index lenses.

3. The printbar assembly according to claim 1, wherein said array of light emitters are substantially aligned along a first axis, and wherein said light control film is disposed such that said microlouvers are aligned substantially perpendicular to said first axis.

4. The printbar assembly according to claim 1, wherein said light emitters are light emitting diodes.

5. A printer,, comprising:

6. The printer according to claim 5, wherein said light emitting sources are light emitting diodes.

7. The printer according to claim 5, wherein said light control film is disposed between said plurality of light emitting sources and said plurality of gradient index lenses.

8. A color printer, comprising:

9. The electrophotographic printer according to claim 8, wherein said first light emitter array is comprised of light emitting diodes.

10. The electrophotographic printer according to claim 8, wherein said first light control film is disposed between said first light emitter array and said first lens array.