WO2002003127A2 - Methods and apparatus for a display compatible with a wide range of liquid crystal materials - Google Patents
Methods and apparatus for a display compatible with a wide range of liquid crystal materials Download PDFInfo
- Publication number
- WO2002003127A2 WO2002003127A2 PCT/US2001/041236 US0141236W WO0203127A2 WO 2002003127 A2 WO2002003127 A2 WO 2002003127A2 US 0141236 W US0141236 W US 0141236W WO 0203127 A2 WO0203127 A2 WO 0203127A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- liquid crystal
- semiconductor device
- crystal display
- transparent plate
- charge
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/136—Liquid crystal cells structurally associated with a semi-conducting layer or substrate, e.g. cells forming part of an integrated circuit
- G02F1/1362—Active matrix addressed cells
- G02F1/136277—Active matrix addressed cells formed on a semiconductor substrate, e.g. of silicon
Definitions
- the present invention relates, generally, to display systems and, more particularly, to liquid crystal-on-silicon displays.
- a microdisplay includes a liquid crystal layer sandwiched between a transparent plate and a silicon backplane device comprising a high-resolution array of picture elements (pixels).
- Such microdisplays which can be found in projection and near-to-eye (NTE) applications, are typically less than 1.0 inch diagonal, but can offer resolutions from 1/4 VGA (78 thousand pixels) to UXGA+ (over 2 million pixels.)
- Modern high-resolution liquid crystal displays typically utilize an active matrix system. That is, referring now to FIG.
- a matrix of thin-film transistors (TFTs) 110 are arranged in a regular pattern and are addressable in the conventional fashion via row select lines 104 and column select lines 102.
- the liquid crystal material is selectively activated over pixels corresponding to the individual TFTs 110.
- the individual liquid crystal pixels 202 can be modeled as shown in FIG. 2, i.e., as a capacitor 204 in parallel with a resistor 206.
- a voltage pulse is applied across this system (nodes 208 and 210)
- the potential across the nodes rises, then decays depending upon the characteristics of capacitor 204 and resistor 206. This effect is shown graphically in FIG.
- CHR charge-hold-ratio
- the CHR corresponds generally to the ratio of area under curve 308 shown in FIG. 3 to the area under the ideal level 304.
- CHR levels of greater than or equal to 98% are desirable in order to achieve high contrast displays; however, such materials are quite expensive and have a variety of other non-optimum characteristics and properties when compared to many of the available liquid crystal materials with much lower CHRs.
- a method and apparatus in accordance with various aspects of the present invention provides a liquid crystal display suitable for use with a wide range of liquid crystal materials.
- a liquid crystal on silicon display includes a semiconductor device which is configured such that the charge associated with individual pixels is substantially maintained, allowing the use of liquid crystal materials (and other components of the display) with low charge-hold ratios (CHR).
- the semiconductor device comprises a static random access memory device (SRAM), for example, a six-transistor (6-T) SRAM.
- FIG. 1 depicts a typical active matrix display system, showing an array of thin-film transistors
- FIG. 2 depicts a simplified equivalent circuit of a typical pixel
- FIG. 3 depicts the leakage characteristics of the model shown in FIG. 2;
- FIG. 4 shows a liquid crystal structure in accordance with various aspects of the present invention.
- FIG. 5 shows a flowchart in accordance with various aspects of the present invention.
- a liquid crystal on silicon display includes a semiconductor device which is configured such that the charge associated with individual pixels is substantially maintained, allowing the use of liquid crystal materials (and other components of the display) with low charge-hold ratios (CHR).
- CHR charge-hold ratios
- the subject matter of the present invention is particularly suited for use in com ection with liquid crystal displays (LCDs) such as microdisplays or other systems using liquid crystal on silicon.
- LCDs liquid crystal displays
- the preferred exemplary embodiment of the present invention is described in that context. It should be recognized, however, that such description is not intended as a limitation on the use or applicability of the present invention, but is instead provided merely to enable a full and complete description of a preferred embodiment.
- An exemplary LCD structure comprises a reflective-mode microdisplay device 400 as shown in FIG. 4.
- a suitable microdisplay 400 comprises a liquid crystal layer 440 disposed between a transparent layer 410 and a semiconductor device 430.
- Transparent plate 410 is suitably bonded to an active surface 438 of semiconductor device 430 via an adhesive seal (not shown), which also acts to constrain liquid crystal layer 440.
- Semiconductor device 430 suitably comprises an array of pixels 436, one or more contacts (not shown), and a reflective layer 434 disposed upon and associated with pixels 436.
- the bottom surface of transparent plate 410 is preferably coated with a conductive, substantially transparent film 412.
- An alignment layer 414 is provided on conductive film 412 and reflective surface 434 to facilitate operation of liquid crystal layer 440 as described further below.
- Liquid crystal layer 440 works in conjunction with pixels 436 and reflective layer 434 to form a high-resolution two-dimensional image. Specifically, in the reflective mode illustrated, incident light entering the top of transparent plate 410 passes through liquid crystal layer 440, is reflected from reflective layer 434, and passes again through transparent plate 410 for projection or direct viewing, depending on the specific external configuration. Suitable addressing circuitry is used to control pixels 436 and thereby effect the configuration of the liquid crystal layer 440. Depending upon the configuration of the liquid crystal, the polarization state of light passing through the layer is modified in a suitable manner.
- Liquid ' crystal 440 may be selected in accordance with various design parameters. While prior art systems depend upon specific liquid crystal materials (e.g., temperature range, optical birefringence, dielectric anisotropy, charge holding ratio, etc.), a display system according to various aspects of the present invention uses liquid crystal material which is less dependent on optimizing one or more of these parameters. More particularly, as described below, the use of a semiconductor device 430 which does not require refresh allows the use of liquid crystal materials which have traditionally been considered unusable for high resolution, active matrix displays. Furthermore, the liquid crystal display is more manufacturable in that the CHR value will not degrade to an unsatisfactory value during processing as is typical with high-CHR liquid crystal materials. The system is therefore robust to variations in the manufacturing process.
- specific liquid crystal materials e.g., temperature range, optical birefringence, dielectric anisotropy, charge holding ratio, etc.
- a display system uses liquid crystal material which is less dependent on optimizing one or more of these parameters. More particularly,
- Liquid crystal materials with low CHR values may be used.
- the CHR is between 30 and 85 %, e.g., about 50%.
- a variety of liquid crystal materials are suitable for this purpose; for example, the model ZLI 2293 liquid crystal material manufactured by E. Merck KGaA.
- liquid crystal layer 440 can be selected according to any appropriate criteria, for example using spacers, such as dimension-controlled rods or spheres, disposed in the gap between alignment layers 414. In an exemplary embodiment, spheres with a diameter of about 1-5 microns are used. Other spacers may also be used depending upon the desired liquid crystal 440 thickness. Spacers of suitable size or any other mechanism for maintaining the desired thickness may be used.
- Transparent plate 410 provides for transmission of light to and from liquid crystal layer 440.
- a variety of materials are suitable for use as the transparent plate 410, including, for example, silicate glasses and other substantially transparent materials, e.g., Schott AF-37 or Corning 1737F glass.
- Transparent plate 410 is preferably chosen such that its coefficient of thermal expansion (CTE) is reasonably close to that of the opposing semiconductor device 430. This tends to reduce thermally-induced stresses arising during processing and temperature cycling.
- Corning 1737 glass for example, is suitable in this regard for a silicon substrate.
- a low-purity glass such as a soda-lime glass may also be employed.
- transparent plate 410 may be chosen in accordance with various design considerations (e.g., stress conditions, etc.). In an exemplary embodiment, transparent plate 410 suitably has a thickness of about 0.9-1.3 mm, preferably about 1.1 mm. Alternatively, transparent plate 110 may consist of two or more layers of the same or different material.
- Semiconductor device 430 includes a silicon substrate 431 and an active surface 438 having an array of pixels 436, reflective layer 434, and appropriate addressing circuitry (not shown) necessary to electrically activate pixels 436 and thereby generate an image via the overlying liquid crystal layer 440, which is responsive to the activated pixels.
- Pixels 436 may be fabricated in accordance with conventional semiconductor techniques, and may consist of any number of standard device technologies, for example, CMOS cells configured and addressable in a row/column format.
- Reflective layer 434 suitably comprises a metallized array deposited on pixels 436.
- Each pixel 436 preferably has an associated reflective layer 434 consisting of, for example, aluminum metallization.
- Reflective layer 434 may comprise, however, any suitable material for reflecting incident light. That is, whereas an SRAM device is typically configured to supply an output for each individual bit, the present invention employs an SRAM wherein the output is routed to individual electrodes (pixels 436) which make up reflective layer 434.
- Semiconductor device 430 comprises a semiconductor device suitable for activating pixels 436 in a manner which does not require traditional refresh.
- semiconductor device 430 is a static random access memory (SRAM).
- SRAM static random access memory
- a variety of conventional SRAMs are suitable for this purpose, ranging from two-transistor SRAMs (2-T) to six-transistor SRAMs (6-T).
- a model OS2 SRAM manufactured by inViso is used.
- liquid crystal parameters such as charge-hold ratio are no longer critical, and a wider range of less-expensive liquid crystal materials with a wider selection of other physical parameters may be used.
- Substrate 430 suitably comprises conventional semiconductor material, for example silicon.
- suitable materials for semiconductor device 430 include, for example, group IV semiconductors (i.e., Si, Ge, and SiGe), group III-V semiconductors (i.e., GaAs, InAs, and AlGaAs), and other unconventional materials such as SiC, diamond, and sapphire.
- Substrate 431 may comprise single crystal material, or may comprise one or more polycrystalline or amorphous epitaxial layer formed on a suitable base material. In the illustrated exemplary embodiment, single-crystal silicon is used.
- a substantially transparent and electrically conductive film 412 is suitably deposited on the bottom surface of transparent plate 410.
- Suitable materials for film 412 include, for example, indium tin oxide (ITO) deposited to a thickness of approximately 25 nm and having a sheet resistance of about 100 Ohms/square.
- ITO indium tin oxide
- the conductive film 412 is suitably connected to a reference potential (not shown) to facilitate the formation of electromagnetic fields in conjunction with the pixels 436 across the liquid crystal layer 440.
- An alignment layer 414 is also suitably provided on conductive film 412 and reflective surface 434.
- the alignment layers 414 suitably comprise conventional alignment layers for aligning the liquid crystal material 440.
- layer 414 preferably exhibits a high transparency.
- Materials suitable for this purpose include, for example, polyimide having undergone any suitable conventional rubbing or alternate aligning process.
- the thickness of the polyimide preferably ranges from 200 to 400 Angstroms, although other thickness dimensions are also appropriate.
- an alignment layer 414 comprises a material with a low CHR, e.g., any of the various polyimides used in connection with passive matrix displays.
- Transparent plate 410 suitably includes a bottom surface 411 upon which a conductive film 412 has been deposited, and semiconductor device 430 includes an active surface 438 which is used to form the two-dimensional image as described above.
- alignment layers 414 are suitably formed on conductive film
- Alignment layers 414 are formed in any convenient manner.
- a suitable polyamide material is dispensed onto surface 438 and conductive film 412 then rubbed in accordance with conventional techniques to produce the desired aligning properties.
- a suitable adhesive is provided on the active surface of semiconductor device 430 and/or transparent plate 410.
- the adhesive is dispensed on transparent plate 410 in an array of rectangles slightly larger than the size of the semiconductor device's pixel array.
- Various conventional adhesive materials e.g., epoxies and the like
- Spacers such as spheres or rods, may be incorporated into the adhesive in order to help maintain the uniformity of liquid crystal layer 440.
- transparent plate 410 and semiconductor device 430 are suitably bonded.
- the adhesive dispensed on active surface 438 of semiconductor device 430 is brought into contact with transparent plate 410.
- the resulting assembly is then processed as appropriate; e.g., the adhesive may require a cure step and/or a particular compressive force may be required to affect bonding.
- a gap between transparent plate 410 and semiconductor device 430 is suitably formed to received the liquid crystal material.
- liquid crystal material 440 is injected or otherwise inserted into the gap formed between transparent plate 410 and semiconductor device 430.
- the display and the desired liquid crystal are placed into a filling machine.
- the filling machine is then suitably evacuated (i.e., the pressure is reduced) and the displays are lowered into the liquid crystal material.
- the liquid crystal material flows, via capillary action, through a gap that has been left in the adhesive seal.
- the pressure is then returned to atmospheric pressure by allowing nitrogen to enter the filling machine, thereby accelerating the injecting step 512.
- the gap is closed via a suitable adhesive in accordance with any convenient technique.
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP01951101A EP1295168A2 (en) | 2000-06-30 | 2001-06-29 | Charge maintaining semiconductor device for liquid crystal display |
AU2001272030A AU2001272030A1 (en) | 2000-06-30 | 2001-06-29 | Methods and apparatus for a display compatible with a wide range of liquid crystal materials |
KR1020027002830A KR20020070959A (en) | 2000-06-30 | 2001-06-29 | Methods and apparatus for a display compatible with a wide range of liquid crystal materials |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US60768100A | 2000-06-30 | 2000-06-30 | |
US09/607,681 | 2000-06-30 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2002003127A2 true WO2002003127A2 (en) | 2002-01-10 |
WO2002003127A3 WO2002003127A3 (en) | 2002-05-30 |
Family
ID=24433259
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2001/041236 WO2002003127A2 (en) | 2000-06-30 | 2001-06-29 | Methods and apparatus for a display compatible with a wide range of liquid crystal materials |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1295168A2 (en) |
KR (1) | KR20020070959A (en) |
AU (1) | AU2001272030A1 (en) |
WO (1) | WO2002003127A2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2413417A (en) * | 2002-12-08 | 2005-10-26 | Immersion Corp | Using haptic effects to enhance information content in communications |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5471225A (en) * | 1993-04-28 | 1995-11-28 | Dell Usa, L.P. | Liquid crystal display with integrated frame buffer |
WO2001002902A1 (en) * | 1999-07-02 | 2001-01-11 | Three-Five Systems, Inc. | Methods and apparatus for a display compatible with a wide range of liquid crystal materials |
-
2001
- 2001-06-29 KR KR1020027002830A patent/KR20020070959A/en not_active Application Discontinuation
- 2001-06-29 EP EP01951101A patent/EP1295168A2/en not_active Withdrawn
- 2001-06-29 AU AU2001272030A patent/AU2001272030A1/en not_active Abandoned
- 2001-06-29 WO PCT/US2001/041236 patent/WO2002003127A2/en not_active Application Discontinuation
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5471225A (en) * | 1993-04-28 | 1995-11-28 | Dell Usa, L.P. | Liquid crystal display with integrated frame buffer |
WO2001002902A1 (en) * | 1999-07-02 | 2001-01-11 | Three-Five Systems, Inc. | Methods and apparatus for a display compatible with a wide range of liquid crystal materials |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2413417A (en) * | 2002-12-08 | 2005-10-26 | Immersion Corp | Using haptic effects to enhance information content in communications |
GB2413417B (en) * | 2002-12-08 | 2007-01-10 | Immersion Corp | Using haptic effects to enhance information content in communications |
Also Published As
Publication number | Publication date |
---|---|
AU2001272030A1 (en) | 2002-01-14 |
KR20020070959A (en) | 2002-09-11 |
WO2002003127A3 (en) | 2002-05-30 |
EP1295168A2 (en) | 2003-03-26 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JPH06214244A (en) | Active matrix type liquid crystal display device | |
US20050219442A1 (en) | Color filter on array mode liquid crystal display and method for making the same | |
KR100260465B1 (en) | Liquid crystal display device | |
KR100811640B1 (en) | liquid crystal display devices | |
JP2782020B2 (en) | Liquid crystal electro-optical device and manufacturing method thereof | |
US6320635B1 (en) | Liquid crystal element and manufacture thereof | |
JP2001527225A (en) | Multipolar liquid crystal display device having alignment layer | |
US5847793A (en) | Liquid crystal display apparatus and fabrication process thereof | |
US5748268A (en) | Quasi-tiled active matrix display | |
JP2940287B2 (en) | Antiferroelectric liquid crystal display device | |
US5852486A (en) | Liquid crystal display with alternative electrode structure | |
KR100978951B1 (en) | Liquid Crystal Panel using for Liquid Crystal Display Device | |
TWI291066B (en) | Liquid crystal display module | |
WO2002003127A2 (en) | Methods and apparatus for a display compatible with a wide range of liquid crystal materials | |
EP1204897A1 (en) | Methods and apparatus for a display compatible with a wide range of liquid crystal materials | |
Morozumi | Materials and assembling process of LCDs | |
JP3301381B2 (en) | Liquid crystal display device | |
JP3039170B2 (en) | Driving method of ferroelectric liquid crystal display device | |
US7369197B2 (en) | Polarizer, panel for a liquid crystal display, and liquid crystal display, including a scattering layer | |
KR100477132B1 (en) | Method for manufacturing liquid crystal display of using feroelectric liquid crystal material | |
KR980010485A (en) | Reduced size spatial light modulator and assembly method thereof | |
JPH11249174A (en) | Liquid crystal display device | |
JP3319562B2 (en) | Liquid crystal display | |
KR100437822B1 (en) | Liquid crystal display device and method of forming the same | |
JPS60262135A (en) | Driving method of liquid-crystal element |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A2 Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZW |
|
AL | Designated countries for regional patents |
Kind code of ref document: A2 Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG |
|
WWE | Wipo information: entry into national phase |
Ref document number: 1020027002830 Country of ref document: KR |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
WWE | Wipo information: entry into national phase |
Ref document number: 2001951101 Country of ref document: EP |
|
AK | Designated states |
Kind code of ref document: A3 Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZW |
|
AL | Designated countries for regional patents |
Kind code of ref document: A3 Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG |
|
WWP | Wipo information: published in national office |
Ref document number: 1020027002830 Country of ref document: KR |
|
REG | Reference to national code |
Ref country code: DE Ref legal event code: 8642 |
|
WWP | Wipo information: published in national office |
Ref document number: 2001951101 Country of ref document: EP |
|
WWW | Wipo information: withdrawn in national office |
Ref document number: 2001951101 Country of ref document: EP |
|
NENP | Non-entry into the national phase |
Ref country code: JP |