LCD with plurality of pixels having reflective and transmissive regions

• US 6,295,109 B1
• Filed: 12/28/1998
• Issued: 09/25/2001
• Est. Priority Date: 12/26/1997
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Shimada, Takayuki, Kubo, Masumi, Ishii, Yutaka, Ban, Atsushi, Yoshimura, Youji, Narutaki, Yozo, Maruyama, Yuko, Yamakawa, Shinya, Katayama, Mikio, Fujioka, Shogo
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): CHOWDHURY, TARIFUR RASHID
• Application Number:
  US09/220,792
• Time in Patent Office: 1,002 Days
• Field of Search: 349/117, 349/119, 349/96, 349/138, 349/144, 349/147, 349/143, 257/59
• US Class Current: 349/119
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/133557 Half-mirrors
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 1/134309 characterised by their geometrical arrangement
• CPC Class Codes: G02F 1/1362 Active matrix addressed cells G02F1/134336, G02F1/134363 take precedence
• CPC Class Codes: G02F 1/13712 the liquid crystal having negative dielectric anisotropy
• CPC Class Codes: G02F 2203/09 transflective

Abstract

A liquid crystal display device includes a first substrate; a second substrate; a liquid crystal layer interposed between the first substrate and the second substrate; a first polarizer provided on a surface of the first substrate which is on the opposite side to the liquid crystal layer; a second polarizer provided on a surface of the second substrate which is on the opposite side to the liquid crystal layer; a first phase compensation element provided between the first polarizer and the liquid crystal layer; and a second phase compensation element provided between the second polarizer and the liquid crystal layer. A plurality of pixel areas are provided for display. The first substrate includes at least one transmissive electrode, and the second substrate includes a reflective electrode region and a transmissive electrode region in correspondence with each of the plurality of pixel areas.

Claims

1. A liquid crystal display device comprising:

a first substrate;

a second substrate;

a liquid crystal layer interposed between the first substrate and the second substrate;

a first polarizer provided on a surface of the first substrate which is opposite the liquid crystal layer;

a second polarizer provided on a surface of the second substrate which is opposite the liquid crystal layer;

a first phase compensation element provided between the first polarizer and the liquid crystal layer; and

a second phase compensation element provided between the second polarizer and the liquid crystal layer,

wherein a plurality of pixel areas are provided for display,

wherein the first substrate includes at least one transmissive electrode, and the second substrate includes a reflective electrode region and a transmissive electrode region in correspondence with each of the plurality of pixel areas

wherein each of the plurality of pixel areas has a reflective region for performing display using reflected light and a transmissive region for performing display using transmitted light, and the reflective electrode region defines the reflective region and the transmissive electrode region defines the transmissive region; and

wherein the liquid crystal layer has a retardation of α

when a molecular axis of liquid crystal molecules in the liquid crystal layer is almost vertical with respect to the surface of the first and second substrates, and the first phase compensation element has a retardation which fulfills λ

/4-α

condition.

2. A liquid crystal display device according to claim 1, wherein the liquid crystal layer has a retardation of α

in the reflective region when a molecular axis of liquid molecules in the liquid crystal layer is almost vertical with respect to the surface of the first and second substrates, the first phase compensation element has a retardation which fulfills λ

/4-α

condition, and the second phase compensation element has a retardation which fulfills λ

/4-(β

-α

) condition wherein β

is retardation of the liquid crystal layer in the transmissive region.

3. A liquid crystal display device according to claim 1, wherein the first phase compensation element and the second phase compensation element are each formed of a λ

/4 wave plate, a transmission axis of the first polarizer and the first phase compensation element make an angle of about 45 degrees, and a transmission axis of the second polarizer and the second phase compensation element make an angle of about 45 degrees.

4. A liquid crystal display device according to claim 1, wherein the first polarizer and the second polarizer have transmission axes perpendicular to each other, and the first phase compensation element and the second phase compensation element have slower axes perpendicular to each other.

5. A liquid crystal display device comprising:

a first substrate;

a second substrate;

a liquid crystal layer interposed between the first substrate and the second substrate;

a first polarizer provided on a surface of the first substrate which is opposite the liquid crystal layer;

a second polarizer provided on a surface of the second substrate which is opposite the liquid crystal layer;

a first phase compensation element provided between the first polarizer and the liquid crystal layer;

a second phase compensation element provided between the second polarizer and the liquid crystal layer,

wherein a plurality of pixel areas are provided for display,

wherein the first substrate includes at least one transmissive electrode, and the second substrate includes a reflective electrode region and a transmissive electrode region in correspondence with each of the plurality of pixel areas;

wherein each of the plurality of pixel areas has a reflective region for performing display using reflected light and a transmissive region for performing display using transmitted light, and the reflective electrode region defines the reflective region and the transmissive electrode region defines the transmissive region; and

wherein the second phase compensation element is formed of a λ

/4 wave plate, and a slower optic axis of the second phase compensation element matches one of a longer axis or a shorter axis of elliptically polarized light transmitted through the liquid crystal layer and incident on the second phase compensation element so as to convert the elliptically polarized light into linearly polarized light, and a transmission axis of the second polarizer is perpendicular to a polarizing axis of the linearly polarized light.

6. A liquid crystal display device, comprising:

a first substrate including at least one transmissive electrode;

a second substrate including at least one reflective electrode region and at least one transmissive electrode region;

a liquid crystal layer interposed between the first substrate and the second substrate and including liquid crystal molecules which exhibit negative dielectric anisotropy and are aligned substantially vertically to surfaces of the first substrate and the second substrate when no voltage is applied, and wherein a plurality of pixel areas are provided for display;

a polarizer provided on a surface of the first substrate which is opposite to the liquid crystal layer;

a λ

/4 wave plate provided between the polarizer and the liquid crystal layer,

wherein a slower axis of the λ

/4 wave plate and a transmission axis of the polarizer make an angle of about 45 degrees;

wherein at least a portion of the at least one reflective electrode region includes a reflective region, and at least a portion of the at least one transmissive electrode region includes a transmissive region;

wherein the reflective region and the transmissive region are arranged so as to correspond with each of the plurality of pixel areas; and

wherein the reflective region is separate from the transmissive region.

7. A liquid crystal display device according to claim 6, further including a phase compensation element between the reflection electrode and the polarizer.

8. A liquid crystal display device, comprising:

a first substrate including at least one transmissive electrode;

a second substrate including at least one reflective electrode region and at least one transmissive electrode region;

a liquid crystal layer interposed between the first substrate and the second substrate and including liquid crystal molecules which exhibit negative dielectric anisotropy and are aligned substantially vertically to surfaces of the first substrate and the second substrate when no voltage is applied;

a first polarizer provided on a surface of the first substrate which is on the opposite side to the liquid crystal layer;

a second polarizer provided on a surface of the second substrate which is on the opposite side to the liquid crystal layer;

a first λ

/4 wave plate provided between the first polarizer and the liquid crystal layer; and

a second λ

/4 wave plate provided between the second polarizer and the liquid crystal layer;

wherein a plurality of pixel areas are provided for display,

wherein at least a portion of the at least one reflective electrode region includes a reflective region, and at least a portion of the at least one transmissive electrode region includes a transmissive region;

wherein the reflective region and the transmissive region are arranged so as to correspond with each of the plurality of pixel areas;

wherein the reflective region is separate from the transmissive region; and

wherein slower axes of the first λ

/4 wave plate and the second λ

/4 wave plate are in an identical direction and make an angle of about 45 degrees with each of transmission axes of the first polarizer and the second polarizer.

9. A liquid crystal display device according to claim 8, wherein each of the plurality of pixel areas has a reflective region for performing display using reflected light and a transmissive region for performing display using transmitted light, and the reflective electrode region defines the reflective region and the transmissive electrode region defines the transmissive region.

10. A liquid crystal display device according to claim 8, further including at least one phase compensation element between the first polarizer and the second polarizer.

11. A liquid crystal display device according to claim 8, wherein the liquid crystal layer further includes a chiral dopant.

12. A liquid crystal display device according to claim 11, wherein the liquid crystal layer has an approximately 90 degree twisted orientation.

13. A liquid crystal display device comprising:

a first substrate;

a second substrate;

a liquid crystal layer interposed between the first substrate and the second substrate;

a first polarizer provided on a surface of the first substrate which is opposite the liquid crystal layer;

a second polarizer provided on a surface of the second substrate which is opposite the liquid crystal layer;

a first phase compensation element provided between the first polarizer and the liquid crystal layer;

a second phase compensation element provided between the second polarizer and the liquid crystal layer,

wherein a plurality of pixel areas are provided for display,

wherein the first substrate includes at least one transmissive electrode, and the second substrate includes a reflective electrode region and a transmissive electrode region in correspondence with each of the plurality of pixel areas;

wherein the first phase compensation element converts linearly polarized light from the first polarizer into circularly polarized light, and the second phase compensation element converts linearly polarized light from the second polarizer into circularly polarized light, and the liquid crystal display further includes a third phase compensation element provided between the first polarizer and the liquid crystal layer for compensating for wavelength dependency of refractive index anisotropy of the first phase compensation element; and

wherein the third phase compensation element is a λ

/2 wave plate, and when a transmission axis of the first polarizer and a slower axis of the third phase compensation element make an angle of γ

1, the transmission axis of the first polarizer and a slower axis of the first phase compensation element make an angle of 2γ

1+45 degrees.

14. A liquid crystal display device comprising:

a first substrate;

a second substrate;

a liquid crystal layer interposed between the first substrate and the second substrate;

a first polarizer provided on a surface of the first substrate which is opposite the liquid crystal layer;

a second polarizer provided on a surface of the second substrate which is opposite the liquid crystal layer;

a first phase compensation element provided between the first polarizer and the liquid crystal layer;

a second phase compensation element provided between the second polazer and the liquid crystal layer,

wherein a plurality of pixel areas are provided for display,

wherein the first substrate includes at least one transmissive electrode, and the second substrate includes a reflective electrode region and a transmissive electrode region in correspondence with each of the plurality of pixel areas;

wherein the first phase compensation element converts linearly polarized light from the first polarizer into circularly polarized light, and the second phase compensation element converts linearly polarized light from the second polarizer into circularly polarized light, and the liquid crystal display further includes a third phase compensation element provided between the first polarizer and the liquid crystal layer for compensating for wavelength dependency of refractive index anisotropy of the first phase compensation element;

a fourth phase compensation element provided between the second polarizer and the liquid crystal layer for compensating for wavelength dependency of refractive index anisotropy of the second phase compensation element; and

wherein the fourth phase compensation element is a λ

/2 wave plate, and when a transmission axis of the second polarizer and a slower axis of the fourth phase compensation element make an angle of γ

2, the transmission axis of the second polarizer and a slower axis of the second phase compensation element make an angle of 2γ

2+45 degrees.

15. A liquid crystal display device according to claim 14, wherein the transmission axis of the first polarizer is perpendicular to the transmission axis of the second polarizer, a slower axis of the first phase compensation element is perpendicular to the slower axis of the second phase compensation element, and a slower axis of the third phase compensation element is perpendicular to the slower axis of the fourth phase compensation element.

16. A liquid crystal display device, comprising:

a first substrate;

a second substrate; and

a liquid crystal layer interposed between the first substrate and the second substrate,

wherein a plurality of pixel areas are provided for display, each of the plurality of pixel areas having a reflective region for performing display using reflected light and a transmissive region for performing display using transmitted light,

the first substrate includes a counter electrode in the vicinity of the liquid crystal layer,

the second substrate includes, in the vicinity of the liquid crystal layer, a plurality of gate lines, a plurality of source lines perpendicular to the plurality of gate lines, a plurality of switching elements provided in the vicinity of intersections of the plurality of gate lines and the plurality of source lines, a first conductive layer having a high light transmission efficiency, and a second conductive layer having a high light reflection efficiency, the first conductive layer and the second conductive layer being connected to each of the switching elements, connected to each other, and being provided in each of the pixel areas.

17. A liquid crystal display device according to claim 16, further including an insulating layer between the first conductive layer and the second conductive layer.

18. A liquid crystal display device according to claim 17, wherein the insulating layer has a wave-like surface below the second conductive layer.

19. A liquid crystal display device according to claim 16, wherein the second substrate further includes a third conductive layer, and the first conductive layer and the second conductive layer are connected to each other through the third conductive layer.

20. A liquid crystal display device according to claim 19, wherein one of the first conductive layer, the second conductive layer and the third conductive layer is formed of a material identical with one of materials forming the plurality of gate electrodes or the plurality of source electrodes.

21. A method for producing a liquid crystal display device, including

a first substrate;

a second substrate; and

a liquid crystal layer interposed between the first substrate and the second substrate,

wherein a plurality of pixel areas are provided for display, each of the plurality of pixel areas having a reflective region for performing display using reflected light and a transmissive region for performing display using transmitted light,

the first substrate includes a counter electrode in the vicinity of the liquid crystal layer,

the second substrate includes, in the vicinity of the liquid crystal layer, a plurality of gate lines, a plurality of source lines perpendicular to the plurality of gate lines, a plurality of switching elements provided in the vicinity of intersections of the plurality of gate lines and the plurality of source lines, a first conductive layer having a high light transmission efficiency, a second conductive layer having a high light reflection efficiency, the first conductive layer and the second conductive layer being connected to each of the switching elements, connected to each other, and being provided in each of the pixel areas, and an insulating layer provided between the first conductive layer and the second conductive layer, the method comprising the steps of;

forming the first conductive layer on a plate;

forming the insulating layer at least on the first conductive layer;

forming the second conductive layer on the insulating layer; and

partially removing the second conductive layer formed on the first conductive layer.

22. A method for producing a liquid crystal display device according to claim 21, further including the steps of:

forming a third conductive layer on a connection area, on at least the first conductive layer, for connecting the first conductive layer and the second conductive layer so as to connect the first conductive layer and the second conductive layer to each other through the third conductive layer;

forming the insulating layer; and

partially removing the insulating layer at least on the connection area for connecting the first conductive layer and the second conductive layer.

23. A method for producing a liquid crystal display device according to claim 21, wherein the step of partially removing the insulating layer includes the step of removing the insulating layer on an area of the first conductive layer.

24. A liquid crystal display device, comprising:

a first substrate;

a second substrate;

a liquid crystal layer interposed between the first substrate and the second substrate;

a first polarizer provided on a surface of the first substrate which is opposite the liquid crystal layer;

a second polarizer provided on a surface of the second substrate which is opposite the liquid crystal layer;

a first phase compensation element provided between the first polarizer and the liquid crystal layer;

a second phase compensation element provided between the second polarizer and the liquid crystal layer,

wherein a plurality of pixel areas are provided for display, and

wherein the first substrate includes at least one transmissive electrode, and the second substrate includes a reflective electrode region including a reflective pixel electrode and a transmissive electrode region including a transmissive pixel electrode in correspondence with each of the plurality of pixel areas, wherein in at least one pixel area said reflective pixel electrode and said transmissive pixel electrode of said second substrate least partially overlap one another.

25. A liquid crystal display device comprising:

a first substrate including at least one transmissive electrode;

a second substrate including at least one reflective electrode region and at least one transmissive electrode region;

a liquid crystal layer interposed between the first substrate and the second substrate;

a first polarizer provided on a surface of the first substrate which is opposite the liquid crystal layer;

a second polarizer provided on a surface of the second substrate which is opposite the liquid crystal layer;

a first phase compensation element provided between the first polarizer and the liquid crystal layer; and

a second phase compensation element provided between the second polarizer and the liquid crystal layer,

wherein a plurality of pixel areas are provided for display,

wherein at least a portion of the at least one reflective electrode region includes a reflective region, and at least a portion of the at least one transmissive electrode region includes a transmissive region;

wherein the reflective region and the transmissive region are arranged so as to correspond with each of the plurality of pixel areas;

wherein the reflective region is independent from the transmissive region.

26. The display of claim 25, wherein each of the plurality of pixel areas has the reflective region for performing display using reflected light and the transmissive region for performing display using transmissive light, and the reflective electrode region defines the reflective region and the transmissive electrode region defines the transmissive region.

27. A liquid crystal display device, comprising:

a liquid crystal layer;

a polarization modulating element and a phase difference compensating element respectively provided on both sides of the liquid crystal layer;

a plurality of pixel regions for providing a display;

wherein a reflection electrode region and a transmissive electrode region are provided on a first side of the liquid crystal layer at each of the plurality of pixel regions; and

wherein, in a first liquid crystal area facing the reflective electrode region and a second liquid crystal area facing the transmissive electrode region, when a retardation in the direction of an observer is substantially zero the polarization direction of light from the first and second liquid crystal areas proceeding toward an observer crosses at a right angle to the transmissive axis of the polarization modulating element at the side of the observer.