Source: http://www.google.com/patents/US20010052948?dq=5787449
Timestamp: 2015-11-27 16:23:07
Document Index: 220664848

Matched Legal Cases: ['Application No. 218483', 'Application No. 92885', 'Application No. 318929', 'Application No. 160878', 'Application No. 218483', 'Application No. 318929', 'Application No. 160878']

Patent US20010052948 - Liquid crystal display - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA liquid crystal display is furnished with: a liquid crystal display element having a pair of substrates, to which alignment members are provided to their respective opposing surfaces, and a liquid crystal layer sandwiched by the pair of substrates; an alignment mechanism for providing at least two different...http://www.google.com/patents/US20010052948?utm_source=gb-gplus-sharePatent US20010052948 - Liquid crystal displayAdvanced Patent SearchPublication numberUS20010052948 A1Publication typeApplicationApplication numberUS 09/887,442Publication dateDec 20, 2001Filing dateJun 25, 2001Priority dateDec 26, 1997Also published asUS6281952, US6563554, US6900863, US7050132, US7394511, US7542116, US7859620, US8427608, US20030067570, US20040160537, US20060119752, US20080170186, US20090268135, US20110102723Publication number09887442, 887442, US 2001/0052948 A1, US 2001/052948 A1, US 20010052948 A1, US 20010052948A1, US 2001052948 A1, US 2001052948A1, US-A1-20010052948, US-A1-2001052948, US2001/0052948A1, US2001/052948A1, US20010052948 A1, US20010052948A1, US2001052948 A1, US2001052948A1InventorsMasayuki Okamoto, Hajime Hiraki, Seiichi MitsuiOriginal AssigneeSharp Kabushiki KaishaExport CitationBiBTeX, EndNote, RefManReferenced by (53), Classifications (13), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetLiquid crystal display
US 20010052948 A1Abstract
A liquid crystal display is furnished with: a liquid crystal display element having a pair of substrates, to which alignment members are provided to their respective opposing surfaces, and a liquid crystal layer sandwiched by the pair of substrates; an alignment mechanism for providing at least two different director configurations simultaneously on different arbitrary regions used for display in the liquid crystal layer; and a reflection film provided to at least one of the different arbitrary regions showing different director configurations; wherein the different arbitrary regions showing different director configurations are used for a reflection display section for showing reflection display and a transmission display section for showing transmission display, respectively. Examples of the alignment mechanism include an alignment film to which the alignment treatment is applied in different orientations in the reflection display section and transmission display section, respectively, an insulation film having different film thicknesses in the reflection display section and transmission display section, and so forth. Images(32) Claims(57)
What is claimed is: 1. A liquid crystal display comprising: a liquid crystal display element having a pair of substrates, to which alignment means are provided to their respective opposing surfaces, and a liquid crystal layer sandwiched by said pair of substrates; an alignment mechanism for providing at least two different director configurations simultaneously on different arbitrary regions used for display in said liquid crystal layer; and reflecting means provided to at least one of said different arbitrary regions showing different director configurations, wherein said different arbitrary regions showing different director configurations are used for a reflection display section for showing reflection display and a transmission display section for showing transmission display, respectively. 2. The liquid crystal display of claim 1 , wherein said alignment mechanism serves as display content overwriting means for overwriting a display content with an evolution of time. 3. The liquid crystal display of claim 1 , wherein said alignment mechanism is said pair of substrates of said liquid crystal display provided with said alignment means; wherein said alignment means is provided such that, in a region of at least one of said substrates touching a region of said liquid crystal layer used for display, at least two different director directions are imparted to a director configuration of said liquid crystal layer at an interface with said region of said substrate. 4. The liquid crystal display of claim 1 , wherein an area of said reflection display section accounts for 30% or above and 90% or less of a total of areas of said reflection display section and said transmission display section. 5. The liquid crystal display of claim 1 , wherein, when said transmission display section shows light display, said reflection display section also shows light display, and when said transmission display section shows dark display, said reflection display section also shows dark display. 6. The liquid crystal display of claim 1 , wherein said liquid crystal layer is made of liquid crystal composition prepared by blending a dichroic dye with liquid crystal. 7. The liquid crystal display of claim 1 , further comprising a polarization plate provided to at least one of said pair of substrates on a surface which does not touch said liquid crystal layer. 8. The liquid crystal display of claim 7 , further comprising voltage applying means for applying a voltage to said liquid crystal layer in such a manner that display light on said reflecting means of said reflection display section has a phase difference of approximately 90� between the light display and the dark display, and display light going out from said liquid crystal layer in said transmission display section has a phase difference of approximately 180� between the light display and dark display. 9. The liquid crystal display of claim 7 , wherein said liquid crystal layer is aligned with a twist between said pair of substrates at a twist angle in a range between 60� and 100� inclusive. 10. The liquid crystal display of claim 7 , wherein said liquid crystal layer is aligned with a twist between said pair of substrates at a twist angle in a range between 0� and 40� inclusive. 11. The liquid crystal display of claim 1 , wherein said liquid crystal display element shows the display by changing the director configuration of said liquid crystal layer by rotating liquid crystal molecules in parallel with said pair of substrates in at least one of said reflection display section and said transmission display section. 12. The liquid crystal display of claim 11 , wherein said liquid crystal display element includes voltage applying means for generating an electric field in said liquid crystal layer along an in-plane direction of said pair of substrates in one of said reflection display section and said transmission display section. 13. The liquid crystal display of claim 1 , wherein at least one of said pair of substrates includes a vertical aligning alignment film on a surface touching said liquid crystal layer at a region corresponding to at least one of said reflection display section and said transmission display section. 14. The liquid crystal display of claim 1 , wherein, in at least one of said pair of substrates, a region corresponding to said reflection display section is thicker than a region corresponding to said transmission display section. 15. The liquid crystal display of claim 14 , wherein at least one of said pair of substrates includes an insulation film at least on the region corresponding to said reflection display section, said insulation film being thicker in the region corresponding to said reflection display section than in the region corresponding to said transmission display section. 16. The liquid crystal display of claim 1 , wherein, on one of said pair of substrates, among regions making up a display region of each pixel, at least a region corresponding to said transmission display section is provided with a color filter having a transmission color. 17. The liquid crystal display of claim 16 , wherein, among regions making up said display region, at least part of a region corresponding to said reflection display section is provided with a color filter having brightness equivalent to brightness of said color filter provided to the region of said substrate corresponding to said transmission display section. 18. The liquid crystal display of claim 16 , wherein, among regions making up said display region, at least part of a region corresponding to said reflection display section is provided with a color filter having a transmission color brighter than the transmission color of said color filter provided to the region of said substrate corresponding to said transmission display section. 19. The liquid crystal display of claim 16 , wherein a part of said reflection display section does not show color display, and an area of said part is set in accordance with luminous transmittance of the transmission color of said color filter. 20. The liquid crystal display of claim 1 , wherein, on one of said pair of substrates, among regions making up a display region of each pixel, at least a region corresponding to said reflection display section is provided with a color filter having a transmission color. 21. The liquid crystal display of claim 20 , wherein, a part of said transmission display section does not show color display, and an area of said part is set in accordance with luminous transmittance of the transmission color of said color filter. 22. The liquid crystal display of claim 20 , wherein, among regions making up said display region, at least part of a region corresponding to said transmission display section is provided with a color filter having a transmission color with chroma at least as good as chroma of the color filter provided to the region corresponding to said reflection display section. 23. The liquid crystal display of claim 1 , further comprising pressed coordinate detecting type input means, superimposed on a display surface, which, when pressed, detect a pressed coordinate position. 24. The liquid crystal display of claim 1 , further comprising a lighting device for emitting light to said liquid crystal display element from behind, said lighting device also serving as display surface luminance changing means for changing luminance on a display surface. 25. The liquid crystal display of claim 24 , wherein said lighting device changes the luminance on said display surface in response to luminance of an observer in such a manner as to attain perceived brightness ranging from 10 brils inclusive to 30 brils exclusive. 26. The liquid crystal display of claim 24 , further comprising pressed coordinate detecting type input means, superimposed on said display surface, which, when pressed, detect a pressed coordinate position, wherein said lighting device changes the luminance on said display surface in association with an output signal from said pressed coordinate detecting type input means. 27. The liquid crystal display of claim 1 , further comprising pressed coordinate detecting type input means, superimposed on a display surface, which, when pressed, detected a pressed coordinate position when being pressed, wherein said alignment mechanism changes the director configuration of said liquid crystal layer in at least one of said reflection display section and said transmission display section in association with an output signal from said pressed coordinate detecting type input means. 28. The liquid crystal display of claim 1 , further comprising pressed coordinate detecting type input means, superimposed on a display surface, which, when pressed, detect a pressed coordinate position when being pressed and a polarization plate, said polarization plate, said pressed coordinate detecting type input means, and said liquid crystal display element being provided in that order. 29. The liquid crystal display of claim 1 , wherein said alignment mechanism is a plurality of voltage applying means for applying a voltage to said liquid crystal display, each of said plurality of voltage applying means being electrically isolated between said reflection display section and said transmission display section, so that a voltage is applied to each of said voltage applying means separately in said reflection display section and said transmission display section. 30. A liquid crystal display comprising a liquid crystal display element having a pair of substrates, to which alignment means are provided to their respective opposing surfaces, and a liquid crystal layer sandwiched by said pair of substrates, wherein: a region used for display in said liquid crystal layer is composed of regions having at least two different thicknesses of said liquid crystal layer; said regions having at least two different thicknesses are used for a reflection display section and a transmission display section, respectively; reflecting means is provided at least to said reflection display section; and the thickness of the liquid crystal layer is thinner in said reflection display section than in said transmission display section. 31. The liquid crystal display of claim 30 , wherein said alignment mechanism is said pair of substrates of said liquid crystal display provided with said alignment means; wherein said alignment means is provided such that, in a region of at least one of said substrates touching a region of said liquid crystal layer used for display, at least two different director directions are imparted to a director configuration of said liquid crystal layer at an interface with said region of said substrate. 32. The liquid crystal display of claim 30 , wherein an area of said reflection display section accounts for 30% or above and 90% or less of a total of areas of said reflection display section and said transmission display section. 33. The liquid crystal display of claim 30 , wherein, when said transmission display section shows light display, said reflection display section also shows light display, and when said transmission display section shows dark display, said reflection display section also shows dark display. 34. The liquid crystal display of claim 30 , wherein said liquid crystal layer is made of liquid crystal composition prepared by blending a dichroic dye with liquid crystal. 35. The liquid crystal display of claim 30 , further comprising a polarization plate provided to at least one of said pair of substrates on a surface which does not touch said liquid crystal layer. 36. The liquid crystal display of claim 35 , further comprising voltage applying means for applying a voltage to said liquid crystal layer in such a manner that display light on said reflecting means of said reflection display section has a phase difference of approximately 90� between the light display and the dark display, and display light going out from said liquid crystal layer in said transmission display section has a phase difference of approximately 180� between the light display and dark display. 37. The liquid crystal display of claim 35 , wherein said liquid crystal layer is aligned with a twist between said pair of substrates at a twist angle in a range between 60� and 100� inclusive. 38. The liquid crystal display of claim 35 , wherein said liquid crystal layer is aligned with a twist between said pair of substrates at a twist angle in a range between 0� and 40� inclusive. 39. The liquid crystal display of claim 30 , wherein said liquid crystal display element shows the display by changing the director configuration of said liquid crystal layer by rotating liquid crystal molecules in parallel with said pair of substrates in at least one of said reflection display section and said transmission display section. 40. The liquid crystal display of claim 39 , wherein said liquid crystal display element includes voltage applying means for generating an electric field in said liquid crystal layer along an in-plane direction of said pair of substrates in one of said reflection display section and said transmission display section. 41. The liquid crystal display of claim 30 , wherein at least one of said pair of substrates includes a vertical aligning alignment film on a surface touching said liquid crystal layer at a region corresponding to at least one of said reflection display section and said transmission display section. 42. The liquid crystal display of claim 30 , wherein, in at least one of said pair of substrates, a region corresponding to said reflection display section is thicker than a region corresponding to said transmission display section. 43. The liquid crystal display of claim 42 , wherein at least one of said pair of substrates includes an insulation film at least on the region corresponding to said reflection display section, said insulation film being thicker in the region corresponding to said reflection display section than in the region corresponding to said transmission display section. 44. The liquid crystal display of claim 30 , wherein, on one of said pair of substrates, among regions making up a display region of each pixel, at least a region corresponding to said transmission display section is provided with a color filter having a transmission color. 45. The liquid crystal display of claim 44 , wherein, among regions making up said display region, at least part of a region corresponding to said reflection display section is provided with a color filter having brightness equivalent to brightness of said color filter provided to the region of said substrate corresponding to said transmission display section. 46. The liquid crystal display of claim 44 , wherein, among regions making up said display region, at least part of a region corresponding to said reflection display section is provided with a color filter having a transmission color brighter than the transmission color of said color filter provided to the region of said substrate corresponding to said transmission display section. 47. The liquid crystal display of claim 44 , wherein a part of said reflection display section does not show color display, and an area of said part is set in accordance with luminous transmittance of the transmission color of said color filter. 48. The liquid crystal display of claim 30 , wherein, on one of said pair of substrates, among regions making up a display region of each pixel, at least a region corresponding to said reflection display section is provided with a color filter having a transmission color. 49. The liquid crystal display of claim 48 , wherein a part of said transmission display section does not show color display, and an area of said part is set in accordance with luminous transmittance of the transmission color of said color filter. 50. The liquid crystal display of claim 48 , wherein, among regions making up said display region, at least part of a region corresponding to said transmission display section is provided with a color filter having a transmission color with chroma at least as good as chroma of the color filter provided to the region corresponding to said reflection display section. 51. The liquid crystal display of claim 30 , further comprising pressed coordinate detecting type input means, superimposed on a display surface, which, when pressed, detect a pressed coordinate position. 52. The liquid crystal display of claim 30 , further comprising a lighting device for emitting light to said liquid crystal display element from behind, said lighting device also serving as display surface luminance changing means for changing luminance on a display surface. 53. The liquid crystal display of claim 52 , wherein said lighting device changes the luminance on said display surface in response to luminance of an observer in such a manner as to attain perceived brightness ranging from 10 brils inclusive to 30 brils exclusive. 54. The liquid crystal display of claim 52 , further comprising pressed coordinate detecting type input means, superimposed on said display surface, which, when pressed, detect a pressed coordinate position, wherein said lighting device changes the luminance on said display surface in association with an output signal from said pressed coordinate detecting type input means. 55. The liquid crystal display of claim 30 , further comprising pressed coordinate detecting type input means, superimposed on a display surface, which, when pressed, detect a pressed coordinate position, and voltage applying means for applying a voltage to said liquid crystal layer, wherein: said voltage applying means applies a voltage to said liquid crystal layer in association with an output signal from said pressed coordinate detecting type input means. 56. The liquid crystal display of claim 30 , further comprising pressed coordinate detecting type input means, superimposed on a display surface, which, when pressed, detect a pressed coordinate position, and a polarization plate, said polarization plate, said pressed coordinate detecting type input means, and said liquid crystal display element being provided in that order. 57. The liquid crystal display of claim 30 , wherein said alignment mechanism is a plurality of voltage applying means for applying a voltage to said liquid crystal display, each of said plurality of voltage applying means being electrically isolated in said reflection display section and said transmission display section, so that a voltage is applied to each of said voltage applying means separately in said reflection display section and said transmission display section.
FIELD OF THE INVENTION [0001] The present invention relates to liquid crystal displays used for information systems, such as word processors and notebook-type personal computers, video equipment of various kinds, video game machines, portable VCRs, digital cameras, etc. More particularly, the present invention relates to liquid crystal displays used indoors and outdoors, or in automobiles, air-planes, marine vessels, etc. where a variety of ambient light conditions occurs. BACKGROUND OF THE INVENTION [0002] Conventionally, CRTs (Cathode Ray Tubes), EL (Electroluminescence) elements, PDPs (Plasma Display Panels), etc. have been put into practical use as displays of the light emissive type in which display contents can be overwritten electrically. [0003] However, since this type of displays emit display light and use the same directly for the display, there arises a problem that their power consumption is quite large. Further since a light-emitting surface of the displays of this type serves as a display surface having high reflectance, if the displays of this type are used under the circumstances where ambient light is brighter than the luminance, for example, in direct sunlight, there always occurs a phenomenon known as “wash-out” in which the display light can not be observed. [0004] On the other hand, liquid crystal displays have been put into practical use as color displays which display characters and/or images not by emitting the display light, but by adjusting an amount of transmitted light from a particular light source. These liquid crystal displays include a transmission type and a reflection type. [0005] Of the two types, particularly popular are the liquid crystal displays of the transmission type which employ a light source called “back light” at the back side, namely, behind the liquid crystal cell. Since the liquid crystal displays of the transmission type are advantageous in thinness and lightness, they have been used in diversified fields. On the other hand, the liquid crystal displays of the transmission type consume a large amount of power to keep the back light turned ON. Thus, regardless of the advantage that only a small amount of power is consumed to adjust transmittance of the liquid crystal, a relatively large amount of power is consumed as a whole. [0006] However, the liquid crystal displays of the transmission type (that is, color liquid crystal displays of the transmission type) wash out less frequently compared with the displays of the light emissive type. This is because, in the color liquid crystal displays of the transmission type, the reflectance on the display surface of a color filter layer is reduced by the reflectance reducing technique using a black matrix. [0007] Nevertheless, it becomes too difficult to observe the display light on the color liquid crystal displays of the transmission type when they are used under the circumstances where the ambient light is very strong and the display light is relatively weak. This problem can be eliminated by using brighter back light, but this solution raises another problem that the power consumption is further increased. [0008] Unlike the displays of the light emissive type and liquid crystal displays of the transmission type, the liquid crystal displays of the reflection type show the display using the ambient light, thereby obtaining display light proportional to an amount of the ambient light. Thus, the liquid crystal displays of the reflection type are advantageous in a principle that they do not wash out, and when used in a very bright place in direct sunlight, for example, the display can be observed all the more sharply. Further, the liquid crystal displays of the reflection type do not use the back light for the display, and therefore, have another advantage that the power for keeping the back light turned ON can be saved. For the above reasons, the liquid crystal displays of the reflection type are particularly suitable as the devices for the outdoor use, such as portable information terminals, digital cameras, and portable video cameras. [0009] However, since these conventional liquid crystal displays of the reflection type use the ambient light for the display, the display luminance largely depends on the surrounding environment, and when used under the circumstances where the ambient light is weak, there arises a problem that the display content can not be observed. Particularly, in case that a color filter is used for realizing the color display, the color filter absorbs the light and the display becomes darker. Thus, when used under these circumstances, the above problem becomes more apparent. [0010] To eliminate the above problem, a lighting device called “front light” has been developed as an auxiliary light, so that the liquid crystal displays of the reflection type can be used under the circumstances where the ambient light is weak. Since the liquid crystal displays of the reflection type have a reflection layer behind the liquid crystal layer, they can not use the back light as do the liquid crystal displays of the transmission type. For this reason, the lighting device (front light) lights the liquid crystal displays of the reflection type from the front side, that is, from the display surface side. [0011] On the other hand, liquid crystal displays, employing a transflective film which transmits a part of incident light and reflects the rest, have been put into practical use as the liquid crystal displays which can be used under the circumstances where the ambient light is weak while maintaining the advantages of the liquid crystal displays of the reflection type. The liquid crystal displays using both the transmitted light and reflected light are generally referred to as the liquid crystal displays of the transflective type. [0012] For example, Japanese Laid-open Patent Application No. 218483/1984 (Tokukaisho No. 59-21843) (Japanese Patent Application No. 92885/1983 (Tokugansho No. 58-92885)) discloses a liquid crystal display of the transflective type which modulates the brightness by the TN (Twisted Nematic) mode, STN (Super-Twisted Nematic) mode, etc., which are known as the liquid crystal display modes for modulating the luminance of the transmitted light. Also, Japanese Laid-open Patent Application No. 318929/1995 (Tokukaihei No. 7-318929) discloses a liquid crystal display of the transflective type, in which a transflective film is provided in close proximity to the liquid crystal layer. Further, Japanese Laid-open Patent Application No. 160878/1994 (Tokukaihei No. 6-160878) (U.S. Pat. Nos. 5,598,285 and 5,737,051) discloses a liquid crystal display of the transmission type adopting the in-plane switching method as a technique for realizing a wider range of viewing angles. However, since the liquid crystal display of the transflective type disclosed in Japanese Patent Application No. 218483/1984 (Tokukaisho No. 59-218483) has the transflective film behind the liquid crystal cell seen from the viewer's side, there occur the following problems (1) and (2). [0013] (1) It is very difficult to set the brightness which affects a visibility of the display device. More specifically, when the brightness of the liquid crystal display of the transflective type is set adequately for the reflection display, the brightness is set high, so that it can be used under the circumstances where the ambient light is insufficient. However, if the brightness is set high by using a polarization plate having high transmittance in the TN method, for example, a contrast ratio, which is defined as a quotient obtained by dividing the brightness in the light display by the brightness in the dark display, becomes too low for the transmission display, thereby deteriorating the visibility. Conversely, when the brightness of the liquid crystal display of the transflective type is set adequately for the transmission display, it is preferable to set the brightness in such a manner as to raise the contrast ratio. However, in this case, the brightness becomes too low for the reflection display, thereby deteriorating the visibility as well. [0014] (2) In the reflection display, since the display is observed by reflecting the light having passed through the liquid crystal layer sandwiched by the two substrates by the reflection film provided behind the liquid crystal cell, there occurs parallax (double image) and the resolution deteriorates, thereby making high-resolution display very difficult. [0015] Also, in the liquid crystal display of the transflective type disclosed in Japanese Laid-open Patent Application No. 318929/1995 (Tokukaihei No. 7-318929), since the transflective film is used as the reflection film, there arises another problem that there is no optical design such that can be suitable for both the reflection display section and transmission display section. [0016] Further, although the in-plane switching method disclosed in Japanese Laid-open Patent Application No. 160878/1994 (Tokukaihei No. 6-160878) is employed in the liquid crystal displays of the transmission type, the director configuration of the liquid crystal on the comb-shaped electrode does not contribute to the display. This is not because, in most cases, the electrode lines are made of metal that does not transmit light, but because the director configuration of the liquid crystal is not changed sufficiently for the transmission display. SUMMARY OF THE INVENTION [0017] Thus, to eliminate the above problems, the inventors of the present invention tried to apply the display method capable of eliminating the parallax and employed in the liquid crystal displays of the reflection type to the liquid crystal displays of the transflective type. More specifically, the inventors conducted an assiduous study by applying the two following methods to the transflective display: [0018] (a) the GH (Guest-Host) method for filling liquid crystal composition blended with a dichroic dye into the liquid crystal layer; and [0019] (b) the reflection type liquid crystal display method using a single polarization plate (hereinafter, referred to as the single polarization plate method). [0020] To apply the above two display methods (a) and (b) which eliminate the parallax to the liquid crystal displays of the transflective type, the reflection layer is provided to touch or almost touch the liquid crystal layer, and a transmission opening is made through the reflection layer to use the transmitted light for the display in addition to the reflected light. [0021] Then, the study revealed the following problems. In case of (a) GH method, when a concentration of the dichroic dye blended with the liquid crystal composition is adjusted adequately for the reflection display, the brightness is sufficiently high but the contrast ratio becomes too low in the transmission display section, thereby failing to obtain satisfactory display. On the other hand, when a concentration of the dichroic dye blended with the liquid crystal composition is adjusted adequately for the transmission display, the contrast ratio is sufficiently high in the transmission display section, but the brightness becomes too low in the reflection display section, thereby failing to obtain satisfactory display. [0022] Also, in case of (b) single polarization plate method, the director configuration of the liquid crystal and a thickness of the liquid crystal layer which determine the optical characteristics, a voltage applied to the liquid crystal for driving the same, etc. are set adequately for either the reflection display section or the transmission display realized by additionally providing a polarization plate or the like behind the display surface (double polarization plate method). [0023] Firstly, the display in the transmission display section when the thickness of the liquid crystal layer is set adequately for the reflection display will be explained. In this case, an amount of change in the polarization state caused when the director configuration of the liquid crystal layer is changed by an external field, such as an electric field, is about a strength such that can realize a satisfactory contrast ratio when incident light from the front, that is, from the display surface side, passes through the liquid crystal layer and exits to the display surface side by passing through the liquid crystal layer again. However, when set in this manner, an amount of the change of the polarization state of the light having passed through the liquid crystal layer is not sufficient in the transmission display section. Thus, even if the polarization plate used for the transmission display alone is provided behind the liquid crystal cell seen from the viewer's side in addition to the polarization plate used for the reflection display and provided to the viewer's side of the liquid crystal cell, that is, the display surface side, the display in the transmission display section is not satisfactory. In other words, when the director configurations (thickness of the liquid crystal layer, director configuration of the liquid crystal, etc.) of the liquid crystal layer are set to be suitable for the reflection display, in the transmission display section, either the brightness is not sufficient or even if the brightness is sufficient, the transmittance does not decrease in the dark display, thereby failing to attain a sufficient contrast ratio for the display. [0024] To be more specific, in case of the reflection display, the director configuration of the liquid crystal in the liquid crystal layer is controlled by means of a voltage applied to the liquid crystal layer to impart a phase difference of about � wavelength to the light passing through the liquid crystal layer only once. When the transmission display is shown with the voltage modulation such that imparts a � wavelength phase modulation to the light passing through the liquid crystal layer set in such a manner as to impart the above-specified phase difference to the light passing through the same, if the transmittance of the transmission display section for the dark display is lowered sufficiently, about half the luminance of the light is absorbed by the polarization plate at the light outgoing side when the transmission display section shows the light display, thereby failing to obtain satisfactory light display. If optical elements, such as a polarization plate and a phase difference compensation plate, are provided to increase the brightness in the light display in the transmission display section, the brightness in the dark display in the transmission display section is increased to about half the brightness in the light display, and the resulting contrast ratio is not satisfactory for the display. [0025] Next, the display in the reflection display section, in case that the director configurations of the liquid crystal layer are set to be suitable for the transmission display, will be explained. In case that the reflection display is shown when the liquid crystal layer is set adequately for the transmission display, the director configuration of the liquid crystal must be controlled by the voltage modulation in such a manner that the polarization state of the light passing through the liquid crystal layer only once is modulated between the two polarization states which are orthogonal each other. The two orthogonal polarization states include two linearly polarized light beams having oscillation planes intersecting at right angles, two circularly polarized light beams of right and left circularly polarization, or two elliptically polarized light beams having the same ellipticity whose major axis orientations intersect at right angles, thereby having opposite rotation directions in their re