Integrated electro-optic package for reflective spatial light modulators

• US 5,486,946 A
• Filed: 12/21/1994
• Issued: 01/23/1996
• Est. Priority Date: 12/21/1994
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Lebby, Michael S., Kelly, George R., Jachimowicz, Karen E.
• Primary Examiner(s): Ben, Loha
• Application Number:
  US08/360,505
• Time in Patent Office: 398 Days
• Field of Search: 359/245, 359/246, 359/247, 359/248, 359/251, 359/252, 359/253, 359/254, 359/261, 359/263, 359/37, 359/40, 359/69, 359/70, 257/21, 257/22, 257/184, 257/457, 257/459
• US Class Current: 359/263
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133608 including particular frames or supporting means
• CPC Class Codes: G02F 1/133616 Front illuminating devices
• CPC Class Codes: G02F 1/13452 Conductors connecting driver circuitry and terminals of panels
• CPC Class Codes: G02F 1/136277 formed on a semiconductor substrate, e.g. of silicon
• CPC Class Codes: G02F 2203/02 reflective
• CPC Class Codes: G02F 2203/12 spatial light modulator

Abstract

An array of reflective LCSLM pixels and control circuits formed on a substrate with a light polarizing layer positioned in overlying relationship to the array. A housing having the array and polarizing layer mounted therein, and defining an opening covered by an optical layer with a reflective member affixed to the optical layer. A light source mounted in the housing so that light is directed onto the reflective member and is reflected uniformly onto the polarizing layer. Electrical connections are made from the array, through leads in the housing and to external contacts. The optical layer including a diffuser forming an image plane for reflected light from the array.

Claims

1. An integrated electro-optic package for reflective spatial light modulators comprising:

an array of reflective spatial light modulator pixels formed on a substrate with each pixel including a control circuit formed in the substrate, each control circuit including control terminals adjacent an outer edge of the substrate, a mirror positioned on the substrate in overlying relationship to the control circuit, and spatial light modulator material positioned in overlying relationship to the mirror so that light passing through the spatial light modulator material is reflected back through the spatial light modulator material;

a light polarizing layer positioned in overlying relationship to the array of reflective spatial light modulator pixels;

a housing with an internal cavity formed to receive the array of reflective spatial light modulator pixels and the light polarizing layer therein, the housing defining an opening generally parallel with and spaced from the light polarizing layer and including an optical layer positioned in the opening;

an at least partially reflective member affixed to the optical layer;

a light source mounted in the housing so that light emanating from the light source is directed onto the reflective member and is reflected substantially uniformly onto the light polarizing layer; and

the optical layer including a diffuser forming an image plane for reflected light from the array of reflective spatial light modulator pixels.

2. An integrated electro-optic package for reflective spatial light modulators as claimed in claim 1 wherein the at least partially reflective member includes at least one diffractive optical element.

3. An integrated electro-optic package for reflective spatial light modulators as claimed in claim 2 wherein the housing has a temperature coefficient of expansion that is substantially similar to the array of reflective spatial light modulator pixels'"'"' temperature coefficient of expansion.

4. An integrated electro-optic package for reflective spatial light modulators as claimed in claim 1 wherein the housing is molded plastic.

5. An integrated electro-optic package for reflective spatial light modulators as claimed in claim 1 wherein the light source includes a plurality of light emitting diodes.

6. An integrated electro-optic package for reflective spatial light modulators as claimed in claim 5 wherein the plurality of light emitting diodes includes at least two diodes, each of which emit a different color of light.

7. An integrated electro-optic package for reflective spatial light modulators as claimed in claim 1 wherein the housing includes a molded plastic and the light source is a plurality of light emitting diodes embedded in the molded plastic.

8. An integrated electro-optic package for reflective spatial light modulators as claimed in claim 1 where, in the array of reflective spatial light modulator pixels, the layer of spatial light modulator material is a continuous layer across the entire array and each control circuit for each pixel formed in the substrate includes one contact, the array further including an optically clear contact positioned on an opposite side of the continuous layer with the one contact and the optically clear contact defining a pixel within the continuous layer.

9. An integrated electro-optic package for reflective spatial light modulators as claimed in claim 8 wherein the spatial light modulator material includes liquid crystal material.

10. An integrated electro-optic package for reflective spatial light modulators as claimed in claim 8 wherein the optically clear contact for each pixel is formed in a layer of indium-tin-oxide deposited in overlying relationship to the continuous layer of spatial light modulator material.

11. An integrated electro-optic package for reflective spatial light modulators as claimed in claim 8 wherein the mirror positioned on the substrate is a polished pad of metal, one for each pixel, which pad of metal also forms the one contact included in the control circuit.

13. An integrated electro-optic package for reflective spatial light modulators as claimed in claim 1 wherein the diffuser in the optical layer is removably mounted and further mounted for axial movement toward and away from the array of reflective partial light modulator pixels to provide focusing of images formed on the diffuser.

14. An integrated electro-optic package for reflective spatial light modulators as claimed in claim 1 wherein the housing include leads formed therein so as to be in electrical contact with the control terminals adjacent an outer edge of the substrate of each control circuit and the leads further extend to an external portion of the housing to form external contacts for the control circuits.

15. An integrated electro-optic package for reflective spatial light modulators as claimed in claim 14 wherein the housing is molded and the leads are a leadframe molded into the housing.

12. An integrated electro-optic package for reflective spatial light modulators as claimed in claim 12 wherein the polished pad of metal for each pixel is a polished pad of aluminum.

16. An integrated electro-optic package for reflective liquid crystal spatial light modulators comprising:

a reflective liquid crystal spatial light modulator stack including a substrate with a plurality of control circuits formed therein, each control circuit including control terminals adjacent an outer edge of the substrate and an electrical contact mirror positioned on the substrate, each electrical contact mirror defining a pixel and a first electrical contact for the pixel, a layer of liquid crystal spatial light modulator material positioned in overlying relationship to the electrical contact mirrors so that light passing through the liquid crystal spatial light modulator material is reflected back through the liquid crystal spatial light modulator material, and an electrically conductive optically transparent layer of material positioned on an opposite surface of the liquid crystal spatial light modulator material to form a second electrical contact for each pixel;

a light polarizing layer positioned in overlying relationship to the electrically conductive optically transparent layer of material;

a housing with an internal cavity formed to receive the light polarizing layer and the stack therein, the housing defining an opening generally parallel with and spaced from the light polarizing layer and including an optical layer positioned in the opening;

an at least partially reflective member affixed to the optical layer;

a light source mounted in the housing so that light emanating from the light source is directed onto the reflective member and is reflected substantially uniformly onto the light polarizing layer; and

the optical layer including a diffuser forming an image plane for reflected light from the array of reflective spatial light modulator pixels.

17. An integrated electro-optic package for reflective liquid crystal spatial light modulators as claimed in claim 16 wherein the layer of liquid crystal spatial light modulator material is contained within a closed cavity having internal opposed flat surfaces, the electrical contact mirrors are affixed to one of the internal surfaces and the electrically conductive optically transparent layer is affixed to the other of the internal surfaces.

18. An integrated electro-optic package for reflective liquid crystal spatial light modulators as claimed in claim 17 wherein the closed cavity is defined by a surface of the substrate, a tubular spacer affixed to the surface of the substrate and a glass plate affixed over the tubular spacer.

19. An integrated electro-optic package for reflective liquid crystal spatial light modulators comprising:

a reflective liquid crystal spatial light modulator stack including

a substrate with a plurality of control circuits formed therein, each control circuit including control terminals adjacent an outer edge of the substrate and an electrical contact minor positioned on the substrate, each electrical contact minor defining a pixel and a first electrical contact for the pixel,

a layer of liquid crystal spatial light modulator material positioned in overlying relationship to the electrical contact minors so that light passing through the liquid crystal spatial light modulator material is reflected back through the liquid crystal spatial light modulator material, and

an electrically conductive optically transparent layer of material positioned on an opposite surface of the liquid crystal spatial light modulator material to form a second electrical contact for each pixel;

a housing with an internal cavity formed to receive the stack therein and the stack being positioned in the internal cavity;

a light polarizing layer positioned in the internal cavity of the housing in overlying relationship to the electrically conductive optically transparent layer of material, the housing defining an opening in the internal cavity generally parallel with and spaced from the light polarizing layer and including an optical layer positioned in the opening so as to receive polarized reflected light from the electrical contact minors on the substrate of the stack;

an at least partially reflective member affixed to the optical layer of the housing;

a light source mounted in the housing so that light emanating from the light source is directed onto the reflective member and is reflected substantially uniformly through the light polarizing layer and onto the stack; and

the optical layer of the housing including a diffuser forming an image plane for reflected light from the stack.

20. An integrated electro-optic package for reflective liquid crystal spatial light modulators as claimed in claim 19 where, in the reflective liquid crystal spatial light modulator stack, the layer of liquid crystal spatial light modulator material is contained within a closed cavity having internal opposed flat surfaces and defined by a surface of the substrate, a spacer affixed to the surface of the substrate and a glass plate affixed over the spacer with the electrical contact mirrors affixed to one of the internal surfaces and the electrically conductive optically transparent layer affixed to the other of the internal surfaces.

21. A method of fabricating an integrated electro-optic package for reflective spatial light modulators comprising the steps of:

providing a stack including a plurality of reflective spatial light modulators formed in a two dimensional array on a semiconductor substrate with drive electronics formed in the substrate for each spatial light modulator of the array of spatial light modulators and control terminals for the drive electronics positioned adjacent outer edges of the substrate, the stack further including a light transparent surface defining a light input and light output for each of the spatial light modulators in the two dimensional array of reflective spatial light modulators;

forming a housing with an internal cavity constructed to receive the stack therein and positioning the stack in the cavity;

forming a light polarizing layer and positioning the light polarizing layer in the internal cavity of the housing in overlying relationship to the stack, the housing defining an opening in the internal cavity generally parallel with and spaced from the light polarizing layer;

forming an optical layer and positioning the optical layer in the opening of the housing so as to receive polarized light from the stack;

forming an at least partially reflective member and affixing the partially reflective member to the optical layer of the housing;

providing a light source and mounting the light source in the housing so that light emanating from the light source is directed onto the reflective member and is reflected substantially uniformly through the light polarizing layer and onto the stack; and

diffusing light reflected from the stack to form an image.

22. A method of fabricating an integrated electro-optic package for reflective spatial light modulators as claimed in claim 21 wherein the step of diffusing light reflected from the stack includes a step of forming the optical layer of the housing so as to include a diffuser constructed to form an image plane for reflected light from the stack.

23. A method of fabricating an integrated electro-optic package for reflective spatial light modulators as claimed in claim 21 wherein the step of forming a housing further includes the step of forming the housing to include a plurality of electrical leads each positioned therein so as to provide a first contact in the cavity and a second, electrically coupled contact at an external surface of the housing.

24. A method of fabricating an integrated electro-optic package for reflective spatial light modulators as claimed in claim 23 wherein the step of forming a housing includes molding the housing from plastic.

25. A method of fabricating an integrated electro-optic package for reflective spatial light modulators as claimed in claim 24 wherein the step of molding the housing from plastic includes a step of molding a leadframe into the plastic to form the plurality of electrical leads.

26. A method of fabricating an integrated electro-optic package for reflective spatial light modulators as claimed in claim 24 wherein the step of molding the housing from plastic and the step of mounting the light source in the housing include forming the housing with at least one alcove in communication with the cavity and adjacent the stack, and positioning at least one light emitting diode in the alcove.