Light energy control system and method of operation

• US 5,101,236 A
• Filed: 12/21/1989
• Issued: 03/31/1992
• Est. Priority Date: 12/21/1989
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Nelson, William E., Mitcham, Larry D.
• Primary Examiner(s): Gellner, Michael L.
• Assistant Examiner(s): RUTLEDGE, DELLA J
• Application Number:
  US07/454,205
• Time in Patent Office: 831 Days
• Field of Search: 355/229, 355/21, 355/71, 355/67, 355/211, 350/611, 350/360, 350/361, 350/607, 350/356, 350/268, 346/160, 346/107 R, 346/108
• US Class Current: 347/239
• CPC Class Codes: B41J 2/465 using masks, e.g. light-switching masks
• CPC Class Codes: G02B 26/0816 by means of one or more reflecting elements
• CPC Class Codes: G03G 15/04 for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material
• CPC Class Codes: G03G 15/0435 by introducing an optical element in the optical path, e.g. a filter
• CPC Class Codes: G06K 15/12 by photographic printing , e.g. by laser printers
• CPC Class Codes: G06K 15/1252 using an array of light modulators, e.g. a linear array

Abstract

There is disclosed a light energy management system for use in conjunction with, in one embodiment, the exposure unit of a xerographic reproduction system. The light management system serves to funnel the unmodulated light for proper impact on a modulating device and to maintain the dark effect of the device when in the unmodulated mode. Light baffles are used for this purpose, some of which are formed as a series of angular steps designed to eliminate unwanted light along the longitudinal axis of the modulated light path. The angular step, in one embodiment, takes the shape of a semi-circular bee thorax. The modulated light path includes a light focus lens and a pair of mirrors for sending the modulated light pulses to the reproduction process surface.

Claims

1. A printing system wherein images are created on a media in response to a series of electrical signals representative of said image, said electrical signals operative for modulating light energy into a series of modulated light patterns representative of said image to be created, said light patterns in turn operative for presentation to a photosensitive surface of said printing system, said system comprising:

a reproductive unit for accepting said light patterns and for converting said light patterns into said created image via said surface;

a light modulation unit for accepting said electrical signals and for converting unmodulated light from a light source impinging upon a spatial light modulator device within said unit into individually modulated pixels of light which are reimaged from said light modulator to said photosensitive surface in accordance with said accepted electrical signals, wherein said spatial light modulator device comprises an array of individually addressable monolithic mirror elements deflectable to at least one distinct angle in response to said electrical signals directed to said mirror elements by monolithic addressing circuitry; and

a positioning device for allowing said reproduction unit and said modulation unit to be mated together so as to effect alignment between said modulated light patterns and said surface, wherein said positioning device comprises;

a slot in said reproduction unit, said slot adjacent to said surface; and

a mating flexible member adapted for positioning in said slot and for sealing said light modulation unit to said reproduction unit, said mating flexible member being elongated in shape and defining a passage for a row of modulated light to pass from said light modulation unit to said surface of said reproduction unit.

2. The printing system set forth in claim 1, wherein said positioning device further includes a three point interlock.

3. The printing system set forth in claim 1, wherein said light modulating unit comprises:

a box having a horizontal partition dividing said box into a lower portion and an upper portion, said lower portion communicating directly with one end of said passage, said lower portion also including a controlled optic path for accepting rows of modulated light from said upper portion and for steering said accepted rows of light for presentation to said passage;

said box upper portion having a modulation device positioned at one end to reflect modulated light along an optical axis defined in said partition, said optical axis defined by a semicircular indention sloped into said partition and away from said modulating device, said indention ending in a passage through said partition; and

a light focusing device positioned within said indention for communicating said modulated light from said modulation device to said controlled optic path in said lower portion of said box.

4. The printing system set forth in claim 3, wherein said indention further includes a plurality of semicircular saw-tooth steps positioned within said indention, said steps each having a first surface for reflecting light backward along said optic axis and a second surface for reflecting light from said backward direction at an angle to said optic axis.

5. The printing system set forth in claim 3, wherein said controlled optic path is a pair of mirrors.

6. The method of controlling light energy in a printing system, wherein images are created on a media in response to a series of electrical signals representative of said image, said electrical signals operative for modulating light energy into a series of modulated light pulses representative of said image to be created, said modulated light pulses in turn operative for presentation to a surface of a xerographic system, said method comprising the steps of:

accepting, in a light modulation unit, said electrical signals;

addressing an array of individually deflectable reflective elements in said light modulation unit in response to said electrical signals;

converting, in said light modulation unit, unmodulated light from a light source into modulated light pulses in accordance with said accepted electrical signals;

passing said modulated light pulses to a reproduction unit from said modulation unit, wherein said positioning step comprises the step of inserting a flexible member of said modulation unit into a slot in said reproduction unit, said slot adjacent to said surface, and sealing said light modulation unit to said reproduction unit, such that said flexible member defines a passage for a row of modulated light to pass from said light modulation unit to said surface of said reproduction unit;

accepting, in said reproduction unit, said modulated light pulses; and

converting, in said reproduction unit, said accepted modulated light pulses into said image to be created via said surface.

7. The method of controlling light energy set forth in claim 6, wherein said light modulating unit comprises a box having a horizontal partition dividing said box into a lower portion and an upper portion, said lower portion communicating directly with one end of said flexible passage, said lower portion also including a pair of mirrors forming an optic path, said converting step further comprising the steps of:

impinging said unmodulated light onto a modulating device at one end of said upper portion of said box to reflect modulated light pulses along an optic axis defined in said partition;

passing said modulated light pulses through a semicircular indention sloped into said partition and away from said modulating device, said indention ending in a passage through said partition; and

impinging said modulated light pulses upon a light focusing device said focusing device directing said modulated light pulses from said modulation device to said pair of mirrors in said lower portion of said box, said pair of mirrors directing said modulated light pulses to said flexible passage.

8. The method of controlling light energy set forth in claim 7, wherein said method further includes the step of passing said modulated light pulses through a plurality of semicircular saw-tooth steps in the sides of said indention, said steps each having a first surface for reflecting light backward along said optic axis and a second surface for reflecting light from said backward direction at an angle to said optic axis.