Spatial light modulator system

• US 5,028,939 A
• Filed: 06/26/1989
• Issued: 07/02/1991
• Est. Priority Date: 08/23/1988
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Hornbeck, Larry J., Nelson, William E.
• Primary Examiner(s): Evans, Arthur G.
• Application Number:
  US07/372,204
• Time in Patent Office: 736 Days
• Field of Search: 350/6.1, 350/6.5, 350/6.6, 350/486, 350/487, 350/355, 350/356, 350/360, 350/361, 346/160, 346/107 R, 346/108, 250/230
• US Class Current: 347/131
• CPC Class Codes: B41J 2/465 using masks, e.g. light-switching masks
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A linear spatial light modulator with two offset rows of pixels for slight overlap of images, and a printer system using such a spatial light modulator with dark field projection optics is disclosed. The pixels include electrostatically deflectable elements which all bend in the same direction to permit use of dark field projection. The addressing electrodes for the elements are beneath the reflecting surface and arranged perpendicular to the rows of pixels with half on each side of the rows. The printer uses a xerographic engine for conversion of modulated light into print, and an entire row is printed without any scanning.

Claims

1. An imager for raster-formatted signals, comprising:

(a) a light source;

(b) a first optical system to focus light from said source onto the linear optically active area of a linear spatial light modulator;

(c) said linear spatial light modulator including a plurality of pixels arranged substantially in a line in a layered structure to form said optically active area, said layered structure including a substrate, a rigid insulating spacer layer on said substrate, a conducting reflecting layer on said spacer layer, and each of said pixels including an electrostatically deflectable element formed in said reflecting layer and a well formed in said spacer layer and located between said deflectable element and said substrate;

(d) addressing circuitry on said substrate for converting said signals into deflectable element deflections;

(e) a second optical system for focussing light reflected from of said deflectable elements which have been deflected onto a photoresponsive material, said second optical system characterized by the image of said linear optically active area being a linear region on said photoresponsive material; and

(f) means for scanning said linear region to illuminate an area on said photoresponsive material.

2. The imager of claim 1, wherein:

(a) said deflectable elements form two offset rows; and

(b) said addressing circuitry includes a plurality of electrodes arranged substantially perpendicular to said line and formed into two groups, an electrode from a first of said groups extending from under one of said deflectable elements in a first of said rows in a first direction, and an electrode from the second of said groups extending from under one of said deflectable elements in the second of said rows in a direction opposite said first direction.

3. The imager of claim 1, wherein:

(a) said deflectable elements form three offset rows; and

(b) said addressing circuitry includes a plurality of electrodes arranged substantially perpendicular to said line and formed into two groups, and electrode from a first of said groups extending from partially under one of said deflectable elements in a first of said rows in a first direction and extending under one of said deflectable elements of a second of said rows, and an electrode from the second of said groups extending from partially under said one of said deflectable elements in the first of said rows in a direction opposite said first direction and extending under one of said deflectable elements of a third of said rows.

4. The imager of claim 1, wherein:

(a) said pixels each include N deflectable elements; and

(b) said circuitry includes an electrode for each of said deflectable elements, N multiplexing gates on said electrodes, and a driver connected to the N electrodes in each pixel.

5. The imager of claim 2, wherein:

(a) said pixels each include N deflectable elements; and

(b) said circuitry includes an electrode for each of said deflectable elements, 2N multiplexing gates on said electrodes with N gates on the electrodes extending in said first direction and N gates on the electrodes extending in said second direction, and a driver for each pixel and connected to the N electrodes in the pixel.

6. The imager of claim 1, wherein:

(a) said photoresponsive material is a xerographic drum.

7. An imager, comprising:

(a) a light source;

(b) a first system to focus light from said source onto a linear spatial light modulator;

(c) said linear spatial light modulator including a plurality of pixels formed in a layered structure, said layered structure including (i) a substrate, (ii) an insulating spacer layer on said substrate, and (iii) a conducting reflective layer on said spacer layer, and each of said pixels including (i) an electrostatically deflectable element formed in said reflecting layer, (ii) a well formed in said spacer layer and located between said deflectable element and said substrate, and (iii) addressing circuitry extending on said substrate under said spacer into said well;

(d) said addressing circuitry converting input signals into deflectable element deflections;

(e) a second system to focus light reflected from said deflectable elements which have been deflected onto a photoresponsive material.

8. The imager of claim 7, wherein:

(a) said second system focusses said reflected light into a linear image on said photoresponsive material and scans said linear image to illuminate an area on said photoresponsive material.

9. The imager of claim 8, wherein:

(a) said photoresponsive material is a xerographic drum; and

(b) said second system turns said drum in synchronization with said input signals which are raster-formatted.

10. The imager of claim 9, wherein:

(a) said deflectable elements form two offset rows; and

(b) said addressing circuitry includes a plurality of electrodes arranged substantially perpendicular to said rows and formed into first and second groups, an electrode from said first group extending from under one of said deflectable elements in a first of said rows in a first direction, and an electrode from said second group extending from under one of said deflectable elements in the second of said rows in a direction opposite said first direction.

11. A printer, comprising:

(a) a light source, light from said light source directed onto a linear spatial light modulator;

(b) said linear spatial light modulator including an array of hinged deflectable reflecting elements and addressing circuitry beneath each of said elements, said addressing circuitry deflecting said elements in correspondence with input signals; and

(c) a photoresponsive material, said photoresponsive material located to receive light reflected from said linear spatial light modulator.

12. The printer of claim 11, wherein:

(a) said deflectable reflecting elements are cantilever hinged and electrostatically deflectable.

13. The printer of claim 11, wherein:

(a) said deflectable reflecting elements are torsion hinged and electrostatically deflectable.

14. The printer of claim 11, wherein:

(a) said photoresponsive material is a xerographic drum.

15. The printer of claim 11, wherein:

(a) said deflectable reflecting elements are arranged in two offset rows.

16. A projection apparatus comprising:

(a) a light source;

(b) an element having at least two deflection means rows each comprising a plurality of deflection means for deflecting light from said light source in at least two directions and arranged in a predetermined direction;

(c) drive means for providing a signal for driving said deflection means, said deflection means deflecting said light in response to said signal; and

(d) a light-receiving member for receiving light from said deflection means, said light-receiving member being movable relative to said element in a subsidiary scan direction which traverses a main scan direction in which light dots are formed on said light-receiving member by said deflection means arranged in said predetermined direction, whereby the light from said deflection means is subsidiary-scanned on said light-receiving member;

(e) wherein the spacing between the deflection means of one row in said predetermined direction is shorter than the length of said deflection means of the other row in said predetermined direction and said one row is deviated from said the other row by about a half of the length of a deflection means arrangement pitch in said predetermined direction so that the light dots adjacent to each other in said main scan direction overlap each other on the light-receiving member; and

(f) wherein the length of the light dots formed by the deflection means in a direction corresponding to the subsidiary scan direction is longer than a subsidiary scan pitch due to the relative movement between said element and said light-receiving member in the subsidiary scan direction.

17. A projection apparatus according to claim 16, wherein the difference between said spacing and said length is such that the uniformity of the quantity-of-light distribution of a pattern formed by the superposed light dots satisfies the condition that

18. A projection apparatus according to claim 17, wherein the difference between said spacing and said length is such that patterns having about a half of the intensity of the adjacent light dots are at the same location.

19. A projection apparatus comprising:

(a) a light source;

(b) an element having at least one deflection means row comprising a plurality of deflection means capable of deflecting light from said light source in at least two directions and arranged in a predetermined direction;

(c) drive means for providing a signal for driving said deflection means, said deflection means deflecting said light in response to said signal; and

(d) a light-receiving member for receiving lights from said deflection means, said light receiving member being movable relative to said element in a subsidiary scan direction which traverses a main scan direction in which light dots are formed on said light-receiving member by said deflection means arranged in said predetermined direction, whereby the light from said deflection means is subsidiary-scanned on said light-receiving member;

(e) wherein the length of the light data formed by the deflection means in a direction corresponding to the subsidiary scan direction is longer than the length of a subsidiary scan pitch due to the relative movement between said element and said light-receiving member in the subsidiary scan direction so that the light dots adjacent to each other in said subsidiary scan direction overlap each other on said light-receiving member.

20. A projection apparatus according to claim 19, wherein said element is a light scanning optical system including an electromechanical transducer element and said deflection means is a movable mirror.

21. A projection apparatus according to claim 19, wherein the difference between said subsidiary scan pitch and said length is such that the uniformity of the quantity-of-light distribution of a pattern formed by the superposed light dots satisfies the condition that

22. A projection apparatus according to claim 21, wherein the difference between said subsidiary scan pitch and said length is such that portions having about a half of the intensity of the adjacent light dots are at the same location.

23. A projection apparatus according to claim 21, wherein said light-receiving member is a photosensitive medium.

24. A projection apparatus comprising:

(a) a light source;

(b) an element having at least two modulating means rows each comprising a plurality of light modulating means for modulating light from said light source to selectively direct the light, said modulating means rows arranged in a predetermined direction;

(c) drive means for providing a signal for driving said modulating means, said modulating means modulating said light in response to said signal; and

(d) a light-receiving member for receiving light from said modulating means, said light-receiving member being movable relative to the light from said modulating means in a subsidiary scan direction which traverses a main scan direction in which light dots are formed on said light-receiving member by said modulating means arranged in said predetermined direction, whereby the light from said modulating means is subsidiary-scanned on said light-receiving member;

(e) wherein the spacing between the modulating means of one row in said predetermined direction is shorter than the length of said modulating means of the other row in said predetermined direction and said one row is deviated from said the other row by about a half the length of a modulating means arrangement pitch in said predetermined direction so that the light dots adjacent to each other in said main scan direction overlap each other on the light-receiving member.

25. A projection apparatus comprising:

(a) a light source;

(b) an element having at least one modulating means row comprising a plurality of modulating means for modulating light from said light source to selectively direct the light and arranged in a predetermined direction;

(c) drive means for providing a signal for driving said modulating means, said modulating means modulating said light in response to said signal; and

(d) a light-receiving member for receiving light from said modulating means, said light-receiving member being movable relatively to said the light from said modulating means in a subsidiary scan direction which traverses a main scan direction in which light dots are formed on said receiving member by said modulating means arranged in said predetermined direction, whereby the light from said modulating means is subsidiary-scanned on said light-receiving member;

(e) wherein the length of the light dots formed by the modulating means in a direction corresponding to the subsidiary scan direction is longer than the length of a subsidiary scan pitch due to the relative movement between said light and said light-receiving member in the subsidiary scan direction so that the light dots adjacent to each other in said subsidiary scan direction overlap each other on said light-receiving member.