Printing system and method using a staggered array spatial light modulator having masked mirror elements

• US 5,754,217 A
• Filed: 04/19/1995
• Issued: 05/19/1998
• Est. Priority Date: 04/19/1995
• Status: Expired due to Fees

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Allen, John B.
• Primary Examiner(s): Yockey, David F.
• Application Number:
  US08/424,917
• Time in Patent Office: 1,126 Days
• Field of Search: 347/134, 347/239, 347/255, 359/223, 359/224, 359/298, 359/290, 359/291, 359/292
• US Class Current: 347/239
• CPC Class Codes: B41J 2/465 using masks, e.g. light-switching masks
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: H04N 1/1916 using an array of elements displaced from one another in the main scan direction, e.g. a diagonally arranged array
• CPC Class Codes: H04N 1/19505 Scanning picture elements spaced apart from one another in at least one direction
• CPC Class Codes: H04N 1/1951 in one direction
• CPC Class Codes: H04N 1/19547 Apertures

Abstract

A system 10 for independently illuminating a plurality of areas on an object 26 such as a printer drum is disclosed herein. The system 10 includes a light source 12 such as an LED or a plurality of LEDs. A spatial light modulator 14, which may be a movable mirror device, for receives light from the light source 12 and reflects selected portions of the light. The spatial light modulator 14 includes at least n rows of independently modulated pixels wherein a mask prevents more than 1/nth of each the rows from receiving and reflecting light at any point in time. The light from the spatial light modulator 14 is imaged (e.g., with imaging lens 24) onto rows and columns of the object 26 to be illuminated. The object 26 is illuminated in a way that each column is illuminated by a corresponding row of pixels.

Claims

1. A system for independently illuminating a plurality of areas on an object, said system comprising:

a light source positioned on a light path, said light source for transmitting light along said light path;

a mask on said light path for blocking portions of said transmitted light and for allowing portions of said transmitted light to pass;

a spatial light modulator on said light path for receiving light passing through said mask from said light source and reflecting selected portions of said light corresponding to said areas to be illuminated on said object, said spatial light modulator comprising sets of n rows of independently modulated pixels wherein said mask prevents more than 1/nth of each said row from receiving and reflecting said light at any point in time, wherein n is an integer greater than one; and

a scanner positioned on said light path between said light source and said spatial light modulator, said scanner for imaging said light on some of said rows of independently modulated pixels;

wherein said object is illuminated by receiving said reflected light from said spatial light modulator, said areas being illuminated comprising p columns such that each of said columns on said object is illuminated by one of said n rows of said pixels.

2. The system of claim 1 wherein each of the n rows includes a plurality of independently modulated pixels which are staggered with respect to the independently modulated pixels of others of the n rows.

3. The system of claim 1 wherein the spatial light modulator is composed of several subarrays of n rows of pixels which are aligned so that a pixel can repeatedly be exposed on the object.

4. The system of claim 1 wherein said spatial light modulator comprises a movable mirror device.

5. The system of claim 4 wherein said spatial light modulator comprises:

a plurality of pixels formed in a layered structure;

said layered structure including an insulated substrate, a spacer layer on said substrate, a conductive reflecting layer on said spacer layer, and a plurality of addressing and landing electrodes;

each of said pixels including

a deflectable element formed in said reflecting layer and connected to said reflecting layer by at least one hinge formed from said reflecting layer,

a well formed in said spacer layer and extending from said deflectable element to said substrate,

an addressing electrode on said substrate at the bottom of said well and located to deflect said deflectable element by electrostatic attraction, and

a landing electrode on said substrate at the bottom of said well, said first landing electrode located both to contact said deflectable element when said deflectable element is deflected by attraction by said first addressing electrode to said substrate and to prevent said deflectable element from contacting said addressing electrode.

6. The system of claim 4 wherein said independently modulated pixels comprise mirror elements, each of said mirror elements being spaced from adjacent mirror elements in the same row.

7. The system of claim 1 wherein said light source is selected from the group consisting of a light emitting diode, a laser diode and an incandescent lamp.

8. The system of claim 1 wherein said object comprises a printing drum.

9. The system of claim 1 and further comprising light directing optics between said light source and said spatial light modulator for simultaneously illuminating all of said rows of independently modulated pixels.

10. The system of claim 1 wherein each of the independently modulated pixels includes a reflective region, only a portion of the reflective region of each of the independently modulated pixels being illuminated.

11. The system of claim 10 and further comprising a mask positioned between said light source and said spatial light modulator, said mask being spaced from said spatial light modulator.

12. The system of claim 11 wherein said mask is positioned less than 10 microns from said spatial light modulator.

13. The system of claim 10 wherein only a square portion of each of independently modulated pixels can be illuminated.

14. A system for independently illuminating a plurality of areas on an object, said system comprising:

a light source positioned on a light path, said light source for transmitting light along said light path;

a mask on said light path for blocking portions of said transmitted light and for allowing portions of said transmitted light to pass;

a movable mirror device on said light path for receiving light passing through said mask from said light source and reflecting selected portions of said light corresponding to said areas to be illuminated on said object, said movable mirror device comprising sets of n rows of independently modulated pixels wherein said mask prevents more than 1/nth of each said row from receiving and reflecting said light at any point in time, wherein n is an integer greater than one; and

a scanner positioned on said light path between said light source and said movable mirror device, said scanner for imaging said light on some of said rows of independently modulated pixels;

wherein said object is illuminated by receiving said reflected light from said movable mirror device, said areas being illuminated comprising p columns such that each of said columns on said object is illuminated by one of said n rows of said pixels; and

wherein said movable mirror device comprises a plurality of pixels, each of said pixels including a deflectable beam, an address electrode adjacent said beam, and a landing electrode adjacent said beam, such that a voltage applied between said beam and said address electrode deflects said beam toward said address electrode, and said landing electrode is located to contact said beam deflected toward said address electrode and prevent said deflected beam from contacting said address electrode.

15. A system for independently illuminating a plurality of areas on an object, said system comprising:

a light source positioned on a light path, said light source for transmitting light along said light path;

a mask on said light path for blocking portions of said transmitted light and for allowing portions of said transmitted light to pass; and

a spatial light modulator on said light path for receiving light from said light source passing through said mask and reflecting selected portions of said light corresponding to said areas to be illuminated on said object, said spatial light modulator comprising at least one set of three rows of independently modulated pixels wherein said mask prevents more than one third of each said row from receiving and reflecting said light at any point in time;

wherein said object is illuminated by receiving said reflected light from said spatial light modulator, said areas being illuminated comprising p columns such that each of said columns on said object is illuminated by one of said n rows of said pixels.

16. A printing system comprising:

a light source located on a light path, said light source for producing a beam of light along said light path;

a first lens on said light path for receiving light from said light source;

a scanner on said light path for receiving light from said first lens;

a second lens on said light p for receiving light from said scanner;

a mask on said light path for blocking portions of said transmitted light and for allowing portions of said transmitted light to pass; and

a spatial light modulator on said light path for receiving light from said second lens and reflecting selected portions to an imaging lens, said spatial light modulator comprising at least n rows of independently modulated pixels wherein said mask allows only 1/nth of each said rows to receive and reflect said light at any point in time; and

a printing drum on said light path for receiving said reflected light from said imaging lens, said printing drum including areas for being selectively and independently illuminated, said areas comprising p rows such that each of said columns on said object is illuminated by a corresponding row of said pixels.

17. The system of claim 16 wherein said spatial light modulator comprises a movable mirror device.

18. The system of claim 16 wherein said light source is selected from the group consisting of a light emitting diode or laser diode or an incandescent lamp.

19. The system of claim 16 wherein said printing drum comprises a rotating cylindrical printing drum.

20. The system of claim 16 and further comprising a mask positioned between said light source and said spatial light modulator, wherein the mask is spaced from both the spatial light modulator and the light source.

21. The system of claim 20 when said mask is positioned such that only a portion of each of said independently modulated pixels is illuminated.

22. The system of claim 21 wherein said mask is positioned such that only a center portion of each of said independently modulated pixels is illuminated.

23. A method independently illuminating a plurality of areas on an object, said method comprising the steps of:

transmitting light through a mask to a spatial light modulator, said mask being spaced from said spatial light modulator;

receiving said light at said spatial light modulator, said spatial light modulator comprising at least one set of n rows of independently modulated pixels wherein only 1/nth of each said rows is allowed to receive and reflect said light at any point in time, wherein n is an integer greater than one;

reflecting a modulated version of said light from said spatial light modulator toward an object to be illuminated; and

receiving said reflected light from said spatial light modulator at object to be illuminated, said areas being illuminated comprising p columns such that each column on said object is illuminated by a corresponding row of said pixels.

24. A system for independently illuminating a plurality of areas on an object, said system comprising:

a light source positioned on a light path, said light source for transmitting light along said light path;

a mask on said light path for blocking portions of said transmitted light and for allowing portions of said transmitted light to pass; and

a spatial light modulator on said light path for receiving light from said light source and reflecting selected portions of said light corresponding to said areas to be illuminated on said object, said spatial light modulator comprising sets of n rows of independently modulated pixels, each of the independently modulated pixels including a reflective region, wherein said mask allows illumination of only a portion of the reflective region of each of the independently modulated pixels by the light from the light source;

wherein said object is illuminated by receiving said reflected light from said spatial light modulator.

25. The system of claim 24 and further comprising a scanner positioned between said light source and said spatial light modulator, said scanner for imaging said light on some of said rows of independently modulated pixels.

26. The system of claim 24 wherein each of the n rows includes a plurality of independently modulated pixels which are staggered with respect to the independently modulated pixels of others of the n rows.

27. The system of claim 24 wherein said spatial light modulator comprises a movable mirror device.

28. The system of claim 24 and further comprising light directing optics between said light source and said spatial light modulator for simultaneously illuminating all of said rows of independently modulated pixels.