LIQUID CRYSTAL DISPLAYS HAVING PIXELS WITH A CONTROL ELECTRODE TO AMPLFIY INTRINSIC FRINGE FIELDS
A vertically aligned liquid crystal display is disclosed. The liquid crystal display, which has a first substrate and a second substrate, uses pixels having a pixel electrode on the first substrate, a common electrode under the second substrate, liquid crystals between the pixel electrode and the common electrode, a switching element coupled to the pixel electrode, a control electrode above the first substrate on a first side of the pixel electrode. When the pixel is in an ON state, the control electrode is at an active control voltage, which is greater than the output voltage of the first switching element. The difference in voltage in the control electrode and the pixel electrode amplifies an intrinsic fringe field around the pixel electrode. The amplified intrinsic fringe field interacts with the pixel electrode electric field and causes the liquid crystals to tilt in the same direction.
1. Field of the Invention
The present invention relates to liquid crystal displays (LCDs). More specifically, the present invention relates to vertical alignment LCDs, with very high contrast ratios.
2. Discussion of Related Art
Liquid crystal displays (LCDs), which were first used for simple monochrome displays, such as calculators and digital watches, have become the dominant display technology. LCDs are used routinely in place of cathode ray tubes (CRTs) for both computer displays and television displays. Various drawbacks of LCDs have been overcome to improve the quality of LCDs. For example, active matrix displays, which have largely replaced passive matrix displays, reduce ghosting and improve resolution, color gradation, viewing angle, contrast ratios, and response time as compared to passive matrix displays. Vertical alignment nematic LCDs address some of the drawbacks of conventional twisted nematic LCDs, such as low contrast ratio.
For further clarity and consistency, the various components of the pixels and the displays in the figures are described from the perspective of the display being flat on a table and the reader being in front of the table. The perspective of the written description does not change whether the figures shows a slice of the display from the edge of the display such as
LCD 100 has a first polarizer 105, a first substrate 110, a first electrode 120, a first liquid crystal alignment layer 125, liquid crystals 130, a second liquid crystal alignment layer 140, a second electrode 145, a second substrate 150, and a second polarizer 155. Specifically, polarizer 105 is attached to the bottom of substrate 110, first electrode 120 is formed on top of substrate 110, and first liquid crystal alignment layer 125 is formed over first electrode 120. Liquid crystals 130 are in between first liquid crystal alignment layer 125 and second liquid crystal alignment layer 140. Common electrode 145 is above liquid crystal alignment layer 140. Common electrode 145 is formed on the bottom of second substrate 150 and second polarizer 155 is attached to the top of substrate 150. Generally, first substrate 110 and second substrate 150 are made of a transparent glass. First electrode 120 and second electrode 145 are made of a transparent conductive material such as ITO (Indium Tin Oxide). First liquid crystal alignment layer 125 and second liquid crystal alignment layer 140, which are typically made of a polyimide (PI) layer, align liquid crystals 130 near a vertical resting state, thus liquid crystals 130 have a small pre-tilt angle from the vertical alignment. In operation, a light source (not shown) sends light from below first polarizer 105, which is attached to the bottom of first substrate 110. First polarizer 105 is generally oriented with polarization axis in a first direction and second polarizer 155, which is attached to the top of second substrate 150, is oriented with polarization axis that is perpendicular to first polarizer 105. Thus, light from the light source would not pass through both first polarizer 105 and second polarizer 155 unless the light polarization were to be rotated by 90 degrees between first polarizer 105 and second polarizer 155. For clarity, very few liquid crystals are shown. In actual displays, liquid crystals are rod like molecules, which are approximately 5 angstroms in diameter and 20-25 angstroms in length. Thus, there are over 5 million liquid crystal molecules in a pixel that is 80 μm width by 240 μm length by 3 μm height. Although not shown, many liquid crystal displays (particularly active matrix LCDs) include a passivation layer on bottom of first electrode 120. The passivation layer serves as an insulating layer between the first electrode 120 and devices and conductors that may be formed on the substrate 110. The passivation layer is commonly formed using silicon nitrides.
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Accordingly, the present invention provides a vertically aligned liquid crystal displays with higher contrast ratios than conventional vertically aligned liquid crystal displays. Furthermore, the present invention can produce advanced LCDs with a complex multi-domain structure at a lower cost than conventional vertically aligned liquid crystal displays. The present invention uses amplified intrinsic fringe fields to control the direction of the tilting liquid crystals.
Specifically, in some embodiment of the present invention, a liquid crystal display, which has a first substrate and a second substrate, uses pixels having a pixel electrode on the first substrate, a common electrode under the second substrate, liquid crystals between the pixel electrode and the common electrode, a switching element coupled to the pixel electrode, a control electrode above the first substrate on a first side of the pixel electrode. When the pixel is in an ON state, the control electrode is at an active control voltage, which is greater than the output voltage of the first switching element. The difference in voltage in the control electrode and the pixel electrode amplifies an intrinsic fringe field around the pixel electrode. The amplified intrinsic fringe field interacts with the pixel electrode electric field and causes the liquid crystals to tilt in the same direction.
Furthermore, in some embodiments of the present invention, the pixel includes a base electrode above the first substrate. The pixel electrode is between the base electrode and the control electrode. The base electrode and the common electrode are coupled to a common voltage.
In some embodiments of the present invention, a liquid crystal display, which has a first substrate and a second substrate, uses pixels having vertical riser above the first substrate, a pixel electrode having a large gap region on the first substrate and a sidewall region over a sidewall of the vertical riser, a common electrode below the second substrate, liquid crystals between the pixel electrode and the common electrode, and a switching element coupled to the pixel electrode. A large gap distance between the large gap region of the pixel electrode and the common electrode is at least one and a fifth times as long as a sidewall gap distance between the sidewall region of the pixel electrode and the common electrode. The elevation of the sidewall region of the pixel electrode amplifies an intrinsic fringe field around the pixel electrode. The amplified intrinsic fringe field interacts with the pixel electrode electric field and causes the liquid crystals to tilt in the same direction.
Furthermore, in some embodiments of the present invention, the pixel electrode includes a small gap region which is located above the top of the vertical riser. For these embodiments the small gap distance is measured from the small gap region of the pixel electrode to the common electrode. The elevation of the small gap region of the pixel electrode further amplifies an intrinsic fringe field around the pixel electrode.
In some embodiments of the present invention segmented pixel electrodes are used in place of rectangular pixel electrodes. The segmented pixel electrodes include multiple pixel electrode segments extending in a first direction. A transverse pixel electrode segment extending in a second direction connects the pixel electrode segments extending in the first direction.
The present invention will be more fully understood in view of the following description and drawings.
As explained above, conventional vertically aligned LCDs have limited contrast ratios and advanced vertically aligned LCDs with a complex multi-domain structure are expensive to manufacture. However, vertically aligned LCDs in accordance with the principles of the present invention use amplify intrinsic fringe field to control tilting of the liquid crystals. Thus, LCDs in accordance with embodiments of the present invention have higher contrast ratios and advanced vertically aligned LCDs with a complex multi-domain structure can be manufactured less expensively as compared to conventional liquid crystal displays.
The difference in voltage on pixel electrode PE_1 and control electrode CE_1 amplifies an intrinsic fringe field around pixel electrode PE_1. In addition, the difference in voltage on control electrode CE_1 and base electrode BaE_1 may also amplify the intrinsic fringe field around pixel electrode PE_1. The amplified intrinsic fringe field interacts with the electric field between pixel electrode PE_1 and the common electrode, when pixel electrode PE_1 is turned on (i.e. transmit light). For clarity the electric field between the pixel electrode and the common electrode is hereinafter referred to as the pixel electrode electric field. The interaction of amplified intrinsic fringe field and the pixel electrode electric field causes the liquid crystals to tilt in the same direction. Liquid crystal effects are collective effects. Thus even though fringe fields are small, the induced liquid crystal effects could be very large due to the liquid crustal collective effects. In general, fringe fields are concentrated mostly on the edge of pixel electrode PE_1, however, large fringe field effects can be induced because of the non-local LC corrective orientation effects.
Base electrode BaE_2 serves to prevent control electrode CE_1 from amplifying the fringe field of an adjacent pixel (not shown). However because the adjacent pixel has an equivalent base electrode BaE_1, some embodiments of the present invention omit base electrode BaE_2.
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To further enlarge and control the fringe field effects, some embodiments of the present inventions use a segmented pixel electrode rather than a solid rectangular electrode.
Segmented pixel electrode SPE_1 is located between first base electrode BaE_1 and control electrode CE_1. Specifically, base electrode BaE_1 is on a first side (i.e. the left side in
In some displays, a wider pixel may be desired.
Control electrode CE_2 is located to the left of base electrode BaE_1, and separated from base electrode BaE_1 by a horizontal control electrode spacing HCES3. Thus, base electrode BaE_1 is between control electrode CE_2 and pixel electrode PE_1. Pixel electrode PE_2 is located between base electrode BaE_3 and control electrode CE_2. Specifically, base electrode BaE_3 is on a first side (i.e. the left side in
Furthermore pixel electrodes PE_1 and PE_2 can be replaced with segmented pixel electrodes as shown in
Control electrode CE_2 is located to the left of base electrode BaE_1, and separated from base electrode BaE_1 by a horizontal control electrode spacing HCES3. Thus, base electrode BaE_1 is between control electrode CE_2 and segmented pixel electrode SPE_1. Segmented pixel electrode SPE_2 is located between base electrode BaE_3 and control electrode CE_2. Specifically, base electrode BaE_3 is on a first side (i.e. the left side in
Segmented pixel SPE_1 of pixel 600 has a plurality of horizontal pixel electrode segments HPES_01_01, HPES_01_02, . . . HPES_01_08 and a longitudinal pixel electrode segment LPES_01_01. In pixel 600, longitudinal pixel electrode segment LPES_01_01 forms the right side of segmented pixel electrode SPE_1. Horizontal pixel electrode segments HPES_01_01-HPES_01_08 extend from the left side of segmented pixel electrode SPE_1 to longitudinal pixel electrode segment LPES_01_01. Similarly, segmented pixel SPE_2 of pixel 600 has a plurality of horizontal pixel electrode segments HPES_02_01, HPES_02_02, . . . HPES_02_08 and a longitudinal pixel electrode segment LPES_02_01. In pixel 600, longitudinal pixel electrode segment LPES_02_01 forms the right side of segmented pixel electrode SPE_2. Horizontal pixel electrode segments HPES_02_01-HPES_02_08 extend from the left side of segmented pixel electrode SPE_2 to longitudinal pixel electrode segment LPES_02_01. Pixel 600 can be made deeper (i.e. longer along the longitudinal axis) by including more horizontal pixel electrode segments in segmented pixels SPE_1 and SPE_2. In addition Pixel 600 can be made wider by including an additional segmented pixel electrodes sandwiched between additional base electrodes and control electrodes.
In Pixels 200, 400, 500, and 600, the liquid crystals tilt to the right (or left when the base electrodes and control electrodes are swapped). However, for some applications having the liquid crystals tilt towards or away from (relative to a display flat on a table in front of the user) would be preferable.
Segmented pixel electrode SPE_1 is located between first base electrode BaE_1 and control electrode CE_1. Specifically, base electrode BaE_1 is on a first side (i.e. the front side in
For deeper (i.e. longer along the longitudinal axis) pixels additional pixels electrodes can be added to pixel 800.
The difference in voltage on base electrode BaE_1 and control electrode CE_1 amplifies an intrinsic fringe field around pixel electrode PE_1. Furthermore, the difference in voltage in control electrode CE_1 and pixel electrode PE_1 also amplifies the intrinsic fringe field around pixel electrode PE_1. The amplified intrinsic fringe field interacts with the pixel electrode electric field, when pixel electrode PE_1 is turned on (i.e. transmit light). The interaction of amplified intrinsic fringe field and the pixel electrode electric field causes the liquid crystals to tilt in the same direction.
Putting control electrode CE_1 and base electrode BaE_2 on vertical riser V_R_1 allows a lower voltage to be used for control voltage V_ctrl as compared to pixel 200. For example, the active voltage of control voltage V_ctrl can be the same as the pixel ON voltage V_p_on for pixel electrode PE_1. Thus, in many embodiments of the present invention control electrode CE_1 is coupled to switching element SE_1, which is also connected to pixel electrode PE_1. Generally, the vertical distance between pixel electrode PE_1 and common electrode 1045 (i.e. the large gap distance)should be at least 1.2 times the vertical distance between control electrode CE_1 on vertical riser V_R_1 and common electrode 1045 (i.e. the small gap distance). Thus, the large gap distance should be at least one and a fifth times the small gap distance. In a particular embodiment of the present invention, the large gap is 3 micrometers and the small gap is 2 micrometer. Thus, in this embodiment, the large gap distance is 1.5 times the small gap distance. However, in another embodiment of the present invention, the small gap is only 1 micrometer.
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Just as with pixel 200, pixel 1000P can be modified by replacing pixel electrode PE_1 with a segmented pixel electrode. Similarly, pixels 500, 600, 700, 800 and 900 can be modified to include vertical risers to lift the control electrodes and appropriate base electrodes. As explained above, when the control electrode is on a vertical riser the control electrode can be coupled to the same switching element that controls the pixel electrode. Therefore, in some embodiments of the present invention, rather than forming separate pixel electrodes and control electrodes, the control electrode is eliminated and the pixel electrode is extended to be formed over the substrate and part of the vertical riser.
When pixel 1100P is in the pixel ON state, i.e. switching element SE_1 is driving pixel electrode to pixel ON voltage V_p_on, both small gap region SGR of pixel electrode PE_1 and sidewall region SWR of pixel electrode PE_1 amplifies the intrinsic fringe field around pixel electrode PE_1. The amplified intrinsic fringe field interacts with the pixel electrode electric field. The interaction of amplified intrinsic fringe field and the pixel electrode electric field causes the liquid crystals to tilt in the same direction. Generally, the vertical distance between large gap region LGR of pixel electrode PE_1 and common electrode 1045 (i.e. the large gap distance)should be at least 1.2 times the vertical distance between small gap region SGR of pixel electrode PE_1 on vertical riser V_R_1 and common electrode 1045 (i.e. the small gap distance). Thus, the large gap distance should be at least one and a fifth times the small gap distance. In a particular embodiment of the present invention, the large gap distance is 3 micrometers and the small gap distance is 2 micrometer. Thus, in this embodiment, the large gap distance is 1.5 times the small gap distance. In another embodiment of the present invention, the small gap distance is 0.75 micrometers. Thus, in this embodiment, the large gap distance is four times the small gap distance. Generally, when the large gap distance gets higher than six times the small gap distance, the fringe field amplification may be less effective.
In many embodiments of the present invention, all regions of pixel electrode PE_1 are formed together using the same material, typically a transparent conducting material such as indium tin oxide (ITO) is used. Generally, the surfaces of pixel electrode PE_1 including the small gap regions are smooth. In most embodiment of the present invention, the large gap region of pixel electrode PE_1 is used to transmit light through the display, while the sidewall region and small gap region mainly provide fringe field amplification. Thus, the large gap region is larger than the sidewall region and small gap region. Generally, the large gap region is at least twice as large as the small gap region. For example, in many embodiments of the present invention, the horizontal width of the large gap region is 20 to 80 micrometers, the horizontal width of the sidewall region is 2 to 10 micrometers, and the horizontal width of the small gap region is 2 to 10 micrometers. In a specific embodiment of the present invention the horizontal width of the large gap region is 40 micrometers, the horizontal width of the sidewall region is 2 micrometers, and the horizontal width of the small gap region 5 micrometers. Because in many embodiments of the present invention, the sidewall region and small gap regions of pixel electrode PE_1 are used to amplify fringe fields rather than for light transmission, these embodiments may use a black matrix or other non-transparent material to prevent light leakage through the sidewall region and/or small gap regions.
In some embodiments of the present invention, sidewall region SWR of pixel electrode PE_1, provides enough amplification of the intrinsic fringe field, that small gap region SGR of pixel electrode PE_1 can be omitted.
Pixel 1100P can be easily modified to use segmented pixel electrodes. In general, segmented pixel electrodes have a plurality of pixel electrode segments in a first direction and a transverse pixel electrode segment in a second direction that connects the plurality of pixel electrode segments. For example, in
Pixel electrodes PE_1 and PE_2 are coupled to switching element SE_1 (not shown in
As explained above, Conventional vertically aligned LCDS having pixels with multiple liquid crystal domains are expensive and complicated to because the liquid crystals in different domains have to have pre-tilt angles in different directions. However, using the principles of the present invention, LCDs with pixels having multiple liquid crystal domains can made more cheaply because no pre-tilt angle is required for the pixels of the present invention.
Segmented pixel SPE_1 of pixel 1400 has a plurality of horizontal pixel electrode segments HPES_01_01, HPES_01_02, . . . HPES_01_08 and a longitudinal pixel electrode segment LPES_01_01. In pixel 1400, longitudinal pixel electrode segment LPES_01_01 forms the right side of segmented pixel electrode SPE_1. Horizontal pixel electrode segments HPES_01_01-HPES_01_08 extend from the left side of segmented pixel electrode SPE_1 to longitudinal pixel electrode segment LPES_01_01. Similarly, segmented pixel SPE_2 of pixel 1400 has a plurality of horizontal pixel electrode segments HPES_02_01, HPES_02_02, . . . HPES_02_08 and a longitudinal pixel electrode segment LPES_02_01. However, in pixel 1400, longitudinal pixel electrode segment LPES_02_01 forms the left side of segmented pixel electrode SPE_2. Horizontal pixel electrode segments HPES_02_01-HPES_02_08 extend from the right side of segmented pixel electrode SPE_2 to longitudinal pixel electrode segment LPES_02_01. Pixel 1400 can be made longer by including more horizontal pixel electrode segments in segmented pixels SPE_1 and SPE_2.
Control electrodes CE_01 of pixel 1400 is on the right side of segmented pixel electrode SPE_1. Consequently, the difference in voltage between control electrode CE_1 and segmented pixel electrode SPE_1 amplifies the intrinsic fringe fields of horizontal pixel electrode segments HPES_01_01 to HPES_01_08. The amplified intrinsic fringe field interacts with the pixel electrode electric field of segmented pixel electrode SPE_1 and cause the liquid crystals above segmented pixel electrode SPE_1 to tilt to the right. Conversely, Control electrodes CE_02 of pixel 1400 is on the left side of segmented pixel electrode SPE_2. Consequently, the difference in voltage between control electrode CE_1 and segmented pixel electrode SPE_2 amplifies the intrinsic fringe fields of horizontal pixel electrode segments HPES_02_01 to HPES_02_08. The amplified intrinsic fringe field interacts with the pixel electrode electric field of segmented pixel electrode SPE_2 and cause the liquid crystals above segmented pixel electrode SPE_2 to tilt to the left. Thus pixel 1400 has two liquid crystal domains.
Base electrode BaE_1 is formed on top of vertical riser V_R_1. Pixel electrode PE_1 is formed on substrate 1510, the sidewall of vertical riser V_R_1, and the top of vertical riser V_R_1. For clarity, pixel electrode PE_1 of pixel 1500P is described as having a large gap region LGR, a sidewall region SWR, and a small gap region SGR. These regions while not labeled in
Pixel electrodes PE_1 and PE_2 are coupled to switching element SE_1 (not shown in
Segmented pixel electrode SPE_1 is located in the back left corner of pixel 1600. Segmented electrode, SPE_1 has four longitudinal pixel electrode segments LPES_01_01, LPES_01_02, LPES_01_03 and LPES_01_04 and a horizontal pixel electrode segment HPES_01_01 that connects longitudinal pixel electrode segments LPES_01_01, LPES_01_02, LPES_01_03 and LPES_01_04. Control electrode CE_01 is located in front of segmented pixel electrode SPE_1. Base electrode BaE_01 is located in front of control electrode CE_01 and in back of (i.e. behind) segmented pixel electrode SPE_3. When pixel 1600 is in the ON state, the voltage difference on control electrode CE_01 and segmented pixel electrode SPE_1 amplifies the intrinsic fringe field of segmented pixel electrode SPE_1. The interaction of the fringe field and the pixel electrode electric field of segmented pixel electrode SPE_1 cause the liquid crystals over segmented pixel electrode SPE_1 to tilt towards the front edge of the display, thus forming a first liquid crystal domain. Base electrode BaE_01 serves to isolate the electric fields of segmented pixel electrode SPE_3 from control electrode CE_01.
Segmented pixel electrode SPE_2 is located in the back right corner of pixel 1600. Segmented electrode, SPE_2 has four horizontal pixel electrode segments HPES_02_01, HPES_02_02, HPES_02_03 and HPES_02_04 and a longitudinal pixel electrode segment LPES_02_01 that connects horizontal pixel electrode segments HPES_02_01, HPES_02_02, HPES_02_03 and HPES_02_04. Control electrode CE_02 is located to the left of segmented pixel electrode SPE_2. Base electrode BaE_02 is located to the left of control electrode CE_02 and to the right of segmented pixel electrode SPE_1. When pixel 1600 is in the ON state, the voltage difference on control electrode CE_02 and segmented pixel electrode SPE_2 amplifies the intrinsic fringe field of segmented pixel electrode SPE_2. The interaction of the fringe field and the pixel electrode electric field of segmented pixel electrode SPE_2 cause the liquid crystals over segmented pixel electrode SPE_2 to tilt to the left, thus forming a second liquid crystal domain. Base electrode BaE_02 serves to isolate the electric fields of segmented pixel electrode SPE_1 from control electrode CE_02.
Segmented pixel electrode SPE_3 is located in the front left corner of pixel 1600. Segmented electrode, SPE_3 has four horizontal pixel electrode segments HPES_03_01, HPES_03_02, HPES_03_03 and HPES_03_04 and a longitudinal pixel electrode segment LPES_03_01 that connects horizontal pixel electrode segments HPES_03_01, HPES_03_02, HPES_03_03 and HPES_03_04. Control electrode CE_03 is located to the right of segmented pixel electrode SPE_3. Base electrode BaE_03 is located to the right of control electrode CE_03 and to the left of segmented pixel electrode SPE_4. When pixel 1600 is in the ON state, the voltage difference on control electrode CE_03 and segmented pixel electrode SPE_3 amplifies the intrinsic fringe field of segmented pixel electrode SPE_3. The interaction of the fringe field and the pixel electrode electric field of segmented pixel electrode SPE_3 cause the liquid crystals over segmented pixel electrode SPE_3 to tilt to the right, thus forming a third liquid crystal domain. Base electrode BaE_03 serves to isolate the electric fields of segmented pixel electrode SPE_4 from control electrode CE_03.
Segmented pixel electrode SPE_4 is located in the front right corner of pixel 1600. Segmented electrode, SPE_4 has four longitudinal pixel electrode segments LPES_04_01, LPES_04_02, LPES_04_03 and LPES_04_04 and a horizontal pixel electrode segment HPES_04_01 that connects longitudinal pixel electrode segments LPES_04_01, LPES_04_02, LPES_04_03 and LPES_04_04. Control electrode CE_04 is located in back of (i.e. behind) segmented pixel electrode SPE_4. Base electrode BaE_04 is located in back of control electrode CE_04 and in front of segmented pixel electrode SPE_2. When pixel 1600 is in the ON state, the voltage difference on control electrode CE_04 and segmented pixel electrode SPE_4 amplifies the intrinsic fringe field of segmented pixel electrode SPE_4. The interaction of the fringe field and the pixel electrode electric field of segmented pixel electrode SPE_4 cause the liquid crystals over segmented pixel electrode SPE_4 to tilt upwards (with respect to
In addition to creating pixels with multiple liquid crystal domains, the present invention can be used to create multi-sector displays. In a multi-sector display, the display is divided into multiple sectors, with each sector having pixels with the same liquid crystal domain. But different sectors are able to have different liquid crystal domains.
Some embodiments of the present invention use optical compensation films to increase the viewing angle of the display. For example, some embodiments of the present invention use negative birefringence optical compensation films with a vertical oriented optical axis on the top or bottom substrate or both top and bottom substrates to increase viewing angle. Other embodiments may use uniaxial optical compensation films or biaxial optical compensation films with a negative birefringence. In some embodiments, optical compensation films with a parallel optical axis orientation can add to the negative birefringence film with a vertical optical axis orientation. Furthermore, multiple films that include all combinations could be used. Other embodiments may use a circular polarizer to improve the optical transmission and viewing angle. Other embodiments may use a circular polarizer with the optical compensation films to further improve the optical transmission and viewing angle. Furthermore, some embodiments of the present invention use black matrix (BM) or non-transparent materials to cover the control voltage region or side wall region to prevent light leakage in the optical black state and make the control voltage or side wall region regions opaque. Use of the black matrix or non-transparent material improves the contrast ratio of the display and may provide better viewing angle and color performance.
In the various embodiments of the present invention, novel structures and methods have been described for creating a multi-domain vertical alignment liquid crystal display without the use of physical features on the substrate. The various embodiments of the structures and methods of this invention that are described above are illustrative only of the principles of this invention and are not intended to limit the scope of the invention to the particular embodiment described. For example, in view of this disclosure those skilled in the art can define other pixel definitions, pixel electrodes, control electrodes, base electrodes, large gap regions, small gap regions, vertical risers, side wall regions, segmented pixel electrodes, fringe fields, electrodes, substrates, display sectors, liquid crystal domains, films, and so forth, and use these alternative features to create a method or system according to the principles of this invention. Thus, the invention is limited only by the following claims.
Claims
1. A pixel of a display having a first substrate and a second substrate, the pixel comprising:
- a first pixel electrode above the first substrate;
- a common electrode below the second substrate;
- a plurality of liquid crystal between the common electrode and the pixel electrode;
- a switching element coupled to the pixel electrode;
- a first control electrode above the first substrate and on a first side of the first pixel electrode;
- wherein the first control electrode is configured to be at an active control voltage when the pixel is in an ON state and wherein the active control voltage is greater than an output voltage of the first switching element.
2. The pixel of claim 1, wherein the active control voltage is more than twice the output voltage of the first switching element.
3. The pixel of claim 1, wherein the first pixel electrode is a first segmented pixel electrode comprising a first plurality of pixel electrode segments extending in a first direction, wherein the first plurality of pixel electrode segments are electrically coupled.
4. The pixel of claim 3, wherein the first segmented pixel electrode further comprises a transverse pixel electrode segment extending in a second direction connecting the first plurality of pixel electrode segments.
5. The pixel of claim 1, further comprising, a first base electrode above the first substrate, wherein the first pixel electrode is between the first base electrode and the first control electrode and wherein the base electrode and the common electrode are coupled to a common voltage.
6. The pixel of claim 5, further comprising a second base electrode coupled to the common voltage, wherein the first control electrode is between the first pixel electrode and the second base electrode.
7. The pixel of claim 6, further comprising:
- a second control electrode coupled to the first control electrode, wherein the first base electrode is between the second control electrode and the first pixel electrode; and
- a second pixel electrode coupled to the first switching element, wherein the second control electrode is between the second pixel electrode and first base electrode.
8. The pixel of claim 7,
- wherein the first pixel electrode is a first segmented pixel electrode comprising a first plurality of first-pixel pixel electrode segments extending in a first direction, wherein the first plurality of first-pixel pixel electrode segments are electrically coupled; and
- wherein the second pixel electrode is a second segmented pixel electrode comprising a first plurality of second-pixel pixel electrode segments extending in the first direction, wherein the first plurality of second-pixel pixel electrode segments are electrically coupled
9. The pixel of claim 8, wherein the first segmented pixel electrode further comprises a first-pixel transverse pixel electrode segment extending in a second direction and connecting the first plurality of first-pixel pixel electrode segments; and
- wherein the second segmented pixel electrode further comprises a second-pixel transverse pixel electrode segment extending in the second direction and connecting the first plurality of second-pixel pixel electrode segments.
10. The pixel of claim 7, further comprising a third base electrode coupled to common voltage, wherein the second pixel electrode is between the second control electrode and the third base electrode.
11. The pixel of claim 10, further comprising:
- a third control electrode coupled to the second control electrode, wherein the second base electrode is between the second pixel electrode and the third control electrode; and
- a third pixel electrode coupled to the first switching element, wherein the third control electrode is between the third pixel electrode and the second base electrode.
12. The pixel of claim 5, further comprising: 7
- a second pixel electrode coupled to the first switching element, wherein the first base electrode is between the second pixel electrode and first pixel electrode.
- a second control electrode coupled to the first control electrode, wherein the second pixel electrode is between the second control electrode and first base electrode; and
13. The pixel of claim 12,
- wherein the first pixel electrode is a first segmented pixel electrode comprising a first plurality of first-pixel pixel electrode segments extending in a first direction, wherein the first plurality of first-pixel pixel electrode segments are electrically coupled; and
- wherein the second pixel electrode is a second segmented pixel electrode comprising a first plurality of second-pixel pixel electrode segments extending in the first direction, wherein the first plurality of second-pixel pixel electrode segments are electrically coupled
14. The pixel of claim 1 further comprising, a first base electrode above the first substrate, wherein the first control electrode is between the first base electrode and the first pixel electrode and wherein the base electrode and the common electrode are coupled to a common voltage.
15. The pixel of claim 14 further comprising a second pixel electrode coupled to the first switching element, wherein the first base electrode is between the first control electrode and the second pixel electrode and wherein the base electrode and the common electrode are coupled to a common voltage.
16. The pixel of claim 15,
- wherein the first pixel electrode is a first segmented pixel electrode comprising a first plurality of first-pixel pixel electrode segments extending in a first direction, wherein the first plurality of first-pixel pixel electrode segments are electrically coupled; and
- wherein the second pixel electrode is a second segmented pixel electrode comprising a first plurality of second-pixel pixel electrode segments extending in a second direction, wherein the first plurality of second-pixel pixel electrode segments are electrically coupled
17. The pixel of claim 14, further comprising a second control electrode on a first side of the second pixel electrode, wherein the first base electrode is on a second side of the second pixel electrode and wherein the first side of the second pixel electrode extends along a first direction and the second side of the second pixel electrode extends along a second direction; and wherein the second control electrode is coupled to the first control electrode.
18. The pixel in claim 17, further comprising:
- a second base electrode coupled to the common voltage, wherein the second control electrode is between the second pixel electrode and the second base electrode; and
- a third pixel electrode coupled to the first switching element, wherein the second base electrode is between the second control electrode and the third pixel electrode.
19. The pixel of claim 18, further comprising a third control electrode, on a first side of the third pixel electrode, wherein the second base electrode is on a second side of the second pixel electrode and wherein the first side of the third pixel electrode extends along the second direction and the second side of the third pixel electrode extends along the first direction; and wherein the third control electrode is coupled to the first control electrode.
20. The pixel in claim 19, further comprising:
- a third base electrode coupled to the common voltage, wherein the third control electrode is between the third pixel electrode and the third base electrode; and
- a fourth pixel electrode coupled to the first switching element, wherein the third base electrode is between the third control electrode and the fourth pixel electrode.
21. The pixel of claim 20, further comprising a fourth control electrode on a first side of the fourth pixel electrode, wherein the third base electrode is on a second side of the fourth pixel electrode and wherein the first side of the fourth pixel electrode extends along the first direction and the second side of the fourth pixel electrode extends along the second direction, and wherein the fourth control electrode is coupled to the first control electrode.
22. The pixel of claim 1, further comprising a first vertical riser over the first substrate and wherein the first control electrode is formed over the top of the first vertical riser.
Type: Application
Filed: Jan 6, 2015
Publication Date: Jul 7, 2016
Inventors: Hiap L. Ong (Warren, NJ), Juishu Chou (Taipei City)
Application Number: 14/590,973