Digital printers using multiple lasers or laser arrays with different wavelengths

• US 5,625,402 A
• Filed: 04/30/1993
• Issued: 04/29/1997
• Est. Priority Date: 04/30/1993
• Status: Expired due to Term

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Sarraf, Sanwal P.
• Primary Examiner(s): Fuller, Benjamin R.
• Assistant Examiner(s): YOCKEY, DAVID F
• Application Number:
  US08/054,486
• Time in Patent Office: 1,460 Days
• Field of Search: 346/107 R, 346/108, 347/232, 347/115, 347/241, 347/243, 347/244, 347/118
• US Class Current: 347/232
• CPC Class Codes: B41J 2/45 using light-emitting diode [LED] or laser arrays
• CPC Class Codes: B41J 2/48 melting ink on a film or melting ink granules
• CPC Class Codes: H04N 1/502 Reproducing the colour component signals dot-sequentially or simultaneously in a single or in adjacent picture-element positions

Abstract

Laser color printers include multiple laser sources formed of either diode lasers or laser diode arrays emitting light beams of different wavelengths, and an optical arrangement. The optical arrangement independently processes each of the light beams to provide a separate predetermined sized collimated light beam, and then focuses and scans the light beams over a printing media that prints separate colors for each different wavelength of light. Where different sized collimated light beams are required to match a printing media, a separate zoom lens is used is used in the optical arrangement to independently reshape each of two orthogonal cross-sectional directions of a separate one of the light beams before being properly sized at the output thereof. Where only one of the two orthogonal cross-sectional directions of the light beams has to be reshaped, the light beams are collimated and combined and pass through a beam shaper which reshapes that cross-sectional direction of the light beams before the light beams are focused and scanned over the printing media. Where laser diode arrays are used to generate separate wavelength light beams, each of the light beams from the lasers of an array are formed and focused into a linear array of spots on the printing media.

Claims

1. A laser color printer for printing a multicolor image on a light-sensitive color printing medium having a surface that is responsive to separate wavelengths of light for each different color printed thereon comprising:

a plurality of laser diode arrays, each of said laser diode arrays generating light beams of different wavelengths, each of said laser diode arrays comprising a plurality of diode lasers with each of said diode lasers of a laser diode array generating a separate diverging light beam of a predetermined substantially same wavelength; and

an optical system comprising;

a) a first optical means for shaping the light beams into beams of a predetermined cross-sectional size and directing said light beams so that said light beams intersect at a common location, said first optical means having a plurality of lenses, each of said lenses receiving the light beams from a separate one of the plurality of diode arrays; and

b) second optical means for creating a plurality of small discrete spots on the surface of the printing medium, said second optical means comprising a focusing lens receiving said light beams from the first optical means and focusing the light beams onto the surface of the printing media, said focusing lens having an entrance pupil positioned at said common location for receiving all of said shaped beams prior to impinging on said focusing lens.

2. The laser color printer of claim 1 wherein:

each of said plurality of lenses of said first optical means receiving the light beams from a separate one of the diode lasers and reducing the divergence of each of the light beams from that diode laser by a predetermined mount, and continuing the direction of the light beams towards the entrance pupil of the focusing leas; and

said first optical means further includes a plurality of a monolithic lenslet arrays, each of said lenslet arrays receiving the light beams from a separate one of the plurality of lenses and comprising a separate lenslet for each of the diode lasers of a separate one of the laser diode arrays for redirecting and focusing each of the light beams at a common area of the entrance pupil.

3. The laser color printer of claim 2 wherein small discrete spots produced for the plurality of diode lasers are aligned parallel to each other with a predetermined spacing therebetween.

4. A laser color printer for printing a multicolor image on a light-sensitive color printing medium that is responsive to different wavelengths of light for each different color printed thereon comprising:

a plurality of laser sources, each of said plurality of laser sources generating a diverging light beam characterized by a wavelength, the wavelength of said light beam being different from the wavelength of at least another light beam of said plurality of laser sources; and

an optical system comprising;

a) a plurality of collimating lenses, each of said plurality of collimating lenses receiving only the light beam from a separate one of the plurality of laser sources for collimating the received light beam into a beam of a predetermined cross-sectional size in a first direction and of a predetermined cross-sectional size in a second direction, said directions being orthogonal of the received light beam, wherein an optical path length from each of said collimating lenses to said light-sensitive printing medium is of constant length; and

b) a plurality of zoom lenses, each of said zoom lenses receiving a respective collimated light beam only from a respective separate one of the plurality of collimating lenses and independently and selectively adjusting the received collimated light beam in each of the first and second orthogonal directions to a predetermined sized collimated output light beam that matches other collimated output light beams from all others of said zoom lenses to selectively control a spot size at each of said different wavelengths on the printing medium for maximizing efficiency of image transfer of each color for said multicolor image;

a plurality of beam combiners receiving and combining the matched collimated output light beams from the plurality of zoom lenses for travel along a common path; and

a lens receiving the combined light beam from the plurality of beam combiners and focusing the light beams onto a surface of said light-sensitive printing medium.