JPH103078A5 - - Google Patents

Description

[0002]
2. Description of the Related Art
The first priority for displays installed in portable information terminals is low power consumption. Therefore, reflective liquid crystal devices, which do not require backlighting, are ideal for this purpose. However, conventional reflective liquid crystal devices have mainly been monochrome displays, and good reflective color displays have yet to be achieved.

[0008]
[Problem to be solved by the invention]
An object of the present invention is to provide a reflective liquid crystal device capable of displaying brighter and more vivid colors than conventional devices, and to provide electronic equipment using the same.

[0026]
[Means for solving the problem]
The reflective liquid crystal device of the present invention comprises a pair of substrates arranged opposite each other, a reflective layer formed on one of the substrates, a plurality of dots formed between electrodes formed on the inner surfaces of the pair of substrates, and a plurality of color filters, each of which has a different color, corresponding to the plurality of dots. The device is characterized in that a color filter having a smaller light absorption than the color filter disposed within the dot is disposed in the area corresponding to the periphery of each dot. This configuration essentially means that no black mask or color filter overlaps are provided outside the dots. It also means that color filters are provided over some or all of the dots, rather than providing nothing outside the dots. This configuration has the advantage of enabling a bright display in a reflective color liquid crystal device. This is because, particularly in the presence of parallax, the display brightness is significantly darkened when a black mask is provided, since the brightness is proportional to approximately the square of the aperture ratio. Conversely, the absence of any color filters outside the dots significantly reduces contrast.

[0036]
Furthermore, the present invention provides an electronic device that includes the above-described reflective liquid crystal device as a display unit. By configuring the electronic device in this manner, the reflective liquid crystal device of the present invention has the advantages of low power consumption, being thin and lightweight, and having good visibility even under direct sunlight.

[0037]
The electronic device of the present invention is characterized in that the display unit is attached so as to be movable relative to the main body so as to efficiently reflect ambient light to the viewer. This configuration has the advantage of providing a bright display under any lighting conditions.

[0044]
Example 1
FIG. 1 shows the main components of the structure of a reflective liquid crystal device according to the present invention. First, the configuration will be described. Reference numeral 101 denotes an upper polarizing plate, 102 denotes a counter substrate, 103 denotes liquid crystal, 104 denotes an element substrate, 105 denotes a light scattering plate, and 106 denotes a polarization separation reflector. On the counter substrate 102, a color filter 107 and a counter electrode (scanning line) 108 are provided. On the element substrate 104, signal lines 109, pixel electrodes 110, and MIM elements 111 are provided. While 101 and 102, 104 and 105, and 105 and 106 are depicted as being separated from each other, this is for clarity; in reality, they are bonded together with glue. The counter substrate 102 and element substrate 104 are also depicted as being widely separated from each other, but this is for the same reason; in reality, the gap is only a few microns to a dozen microns. Also, since FIG. 1 shows the main parts of a reflective color liquid crystal device, only 9 dots (3 x 3) are shown, but in this embodiment, there are more dots, and in some cases there are 307,200 dots (480 x 640) or more dots.

[0052]
Example 2
FIG. 3 shows the spectral characteristics of color filters in a reflective liquid crystal device according to the present invention. The configuration of Example 2 is the same as that of Example 1 shown in FIG. 1, and also includes color filters of two colors, red and cyan. The horizontal axis of FIG. 3 represents the wavelength of light, and the vertical axis represents the transmittance, with 301 representing the spectrum of the red filter and 302 representing the spectrum of the cyan filter. Both color filters have a transmittance of 50% or more in the wavelength range of 450 nm to 660 nm. The average transmittance in the same wavelength range was 71% for the red filter and 78% for the cyan filter.

[0055]
Example 3
FIG. 1 shows the main structure of a reflective liquid crystal device according to the present invention. FIG. 2 shows the spectral characteristics of a color filter. The configuration of Example 3 is basically the same as that of the reflective liquid crystal device described in Example 1, so explanation of the various reference numerals will be omitted. However, the Δn×d of the liquid crystal 103 was set to 0.42 μm. The dot pitch was 160 μm both vertically and horizontally, and the drive area ratio was 75%.

[0059]
Example 4
FIG. 5 shows the spectral characteristics of color filters in a reflective liquid crystal device according to the present invention. The configuration of Example 3 is the same as that of Example 1 shown in FIG. 1, and also includes color filters of two colors, red and cyan. The horizontal axis of FIG. 5 represents the wavelength of light, and the vertical axis represents the transmittance, with 501 representing the spectrum of the red filter and 502 representing the spectrum of the cyan filter. Both color filters have a transmittance of 60% or more in the wavelength range of 450 nm to 660 nm. Furthermore, the average transmittance in the same wavelength range was 75% for the red filter and 80% for the cyan filter.

[0062]
Example 5
6 is a diagram showing the main parts of the structure of a reflective liquid crystal device according to the present invention. First, the configuration will be explained. Reference numeral 601 denotes a polarizing plate, 602 denotes an opposing substrate, 603 denotes liquid crystal, 604 denotes an element substrate, 605 denotes a light scattering plate, and 606 denotes a polarization separation reflector. On the opposing substrate 602, a color filter 607 and an opposing electrode (scanning line) 608 are provided, and on the element substrate 604, signal lines 609, pixel electrodes 610, and MIM elements 611 are provided.

[0065]
Example 6
FIG. 7 shows the spectral characteristics of color filters in a reflective liquid crystal device according to the present invention. The configuration of Example 2 is the same as that of Example 5 shown in FIG. 6, but includes color filters of two colors, green and magenta, instead of red and cyan. The horizontal axis of FIG. 7 represents the wavelength of light, and the vertical axis represents the transmittance, with 701 representing the spectrum of the green filter and 702 representing the spectrum of the magenta filter. Both color filters have a transmittance of 50% or more in the wavelength range from 450 nm to 660 nm. The average transmittance in the same wavelength range was 76% for the green filter and 78% for the magenta filter.

[0068]
Example 7
8 is a diagram showing the main parts of the structure of a reflective liquid crystal device according to the present invention. First, the configuration will be described. Reference numeral 801 denotes a polarizing plate, 802 denotes a counter substrate, 803 denotes liquid crystal, 804 denotes an element substrate, 805 denotes a light scattering plate, and 806 denotes a polarization separation reflector. A color filter 807 and a counter electrode (scanning line) 808 are provided on the counter substrate 802, and signal lines 809, pixel electrodes 810, and MIM elements 811 are provided on the element substrate 804. A weak anti-glare treatment is applied to the upper polarizing plate to reduce glare from illumination light.

[0072]
(Example 8)
10 is a diagram showing the main parts of the structure of a reflective liquid crystal device according to the present invention. First, the configuration will be explained. Reference numeral 1001 denotes a polarizing plate, 1002 denotes an element substrate, 1003 denotes liquid crystal, 1004 denotes an opposing substrate, 1005 denotes a light scattering plate, and 1006 denotes a polarization separation reflector. An opposing electrode (scanning line) 1011 and a color filter 1010 are provided on the opposing substrate 1004, and signal lines 1007, MIM elements 1008, and pixel electrodes 1009 are provided on the element substrate 1002. The color filter 1010 is a pigment dispersion type and consists of three colors: red (indicated by "R" in the figure), green (indicated by "C" in the figure), and blue (indicated by "B" in the figure).

[0075]
Example 9
FIG. 12 shows the spectral characteristics of color filters in a reflective liquid crystal device according to the present invention. The configuration of Example 9 is similar to that of Example 7 shown in FIG. 8, and also includes color filters consisting of three colors: red, green, and blue. In FIG. 12, the horizontal axis represents light wavelength, and the vertical axis represents transmittance, with 1201 representing the spectrum of the red filter, 1202 representing the spectrum of the green filter, and 1203 representing the spectrum of the blue filter. Here, only the green filter has a transmittance of 50% or more in the wavelength range from 450 nm to 660 nm. Furthermore, the minimum transmittance of the red filter for light with wavelengths from 450 nm to 660 nm is significantly lower than that of the blue and green filters. By using such a red filter, it is possible to display a vivid red, which is most appealing to the human eye. Furthermore, to compensate for the darkened red, the blue filter spectrum 1203 is made closer to cyan. This allows for the display of a bright, less colored white.

[0077]
Example 10
10 is a diagram showing the main parts of the structure of a reflective liquid crystal device according to the present invention. The configuration will now be described. 1001 denotes a polarizing plate, 1002 denotes an element substrate, 1003 denotes liquid crystal, 1004 denotes an opposing substrate, 1005 denotes a light scattering plate, and 1006 denotes a polarization separation reflector. An opposing electrode (scanning line) 1011 and a color filter 1010 are provided on the opposing substrate 1004, and signal lines 1007, MIM elements 1008, and pixel electrodes 1009 are provided on the element substrate 1002. The color filter 1010 is a pigment dispersion type, and consists of three colors: red (indicated by "R" in the figure), green (indicated by "C" in the figure), and blue (indicated by "B" in the figure).

[0080]
Example 11
Figure 15 shows the main parts of the structure of a reflective liquid crystal device according to the present invention. First, the configuration will be explained. Reference numeral 1501 denotes a polarizing plate, 1502 denotes an element substrate, 1503 denotes liquid crystal, 1504 denotes an opposing substrate, 1505 denotes a light scattering plate, and 1506 denotes a polarization separation reflector. Opposing electrodes (scanning lines) 1511 and color filters 1510 are provided on the opposing substrate 1504, while signal lines 1507, MIM elements 1508, and pixel electrodes 1509 are provided on the element substrate 1502. The light-modulating region within one dot is the region where the concave-shaped ITO on the element substrate overlaps with the strip-shaped ITO on the opposing substrate, and its outline is indicated by a dashed line on the ITO of the opposing substrate. (Although some of it is not visible due to overlap with the color filter, please refer to Figure 20, which shows a similar outline.)
The counter electrode 1511 and pixel electrode 1509 are made of transparent ITO, and the signal line 1507 is made of metal Ta. The MIM element has a structure in which an insulating film of Ta2O5 is sandwiched between metal Ta and metal Cr. The liquid crystal 1503 is a nematic liquid crystal twisted 90 degrees, and the Δn of the liquid crystal and the cell gap d were selected so that the Δn × d of the liquid crystal cell was 1.34 μm. The upper and lower polarizers were also positioned so that their absorption axes were parallel to the rubbing axis of the adjacent substrate. This is the brightest, least colored TN mode configuration. The color filter 1510 consists of two complementary colors, red (indicated by "R" in the figure) and cyan (indicated by "C" in the figure), but is only provided in a portion of the light-modulating area.

[0086]
Example 12
The twelfth embodiment is also a reflective liquid crystal device according to the present invention. Its structure is similar to that of the eleventh embodiment shown in Fig. 15, but the characteristics of the color filters are different.

[0091]
Example 13
20 is a diagram showing the main parts of the structure of a reflective liquid crystal device according to the present invention. The configuration will now be described. 2001 denotes a polarizing plate, 2002 denotes an element substrate, 2003 denotes liquid crystal, 2004 denotes an opposing substrate, 2005 denotes a light scattering plate, and 2006 denotes a polarization separation reflector. Opposing electrodes (scanning lines) 2011 and color filters 2010 are provided on the opposing substrate 2004, and signal lines 2007, MIM elements 2008, and pixel electrodes 2009 are provided on the element substrate 2002. The light-modulating region within one dot is the region where the concave ITO on the element substrate and the strip-shaped ITO on the opposing substrate overlap, and its outline is indicated by a dashed line on the ITO of the opposing substrate.

[0093]
Example 14
21 is a diagram showing the main parts of the structure of a reflective color liquid crystal device according to the present invention. The configuration will now be described. 2101 is a polarizing plate, 2102 is an element substrate, 2103 is liquid crystal, 2104 is an opposing substrate, 2105 is a light scattering plate, and 2106 is a polarization separation reflector. Opposing electrodes (scanning lines) 2112 and color filters 2111 are provided on the opposing substrate 2104, and signal lines 2107, MIM elements 2108, and pixel electrodes 2109 are provided on the element substrate 2102.

[0096]
Example 15
The fifth embodiment is a reflective liquid crystal device according to the present invention, but its structure is similar to that of the reflective liquid crystal device of the twelfth embodiment shown in Fig. 15, the reflective liquid crystal device of the thirteenth embodiment shown in Fig. 20, and the reflective color liquid crystal device of the fourteenth embodiment shown in Fig. 21.

[0099]
Example 16
23A and 23B are diagrams showing the structure of a color filter substrate of a reflective liquid crystal device according to the present invention. (a) is a front view, and (b) is a cross-sectional view. First, the configuration will be explained. A rectangular area 2304 surrounded by a dashed line in (a) represents one dot. 2309 is a glass substrate, 2301 is a red filter, 2303 is a green filter, 2302 is a blue filter, 2305 is a gap between dots, 2308 is acrylic, 2307 is a protective film, and 2306 is an ITO transparent electrode.

[0105]
(Example 17)
28A and 28B are diagrams showing the structure of a color filter substrate of a reflective liquid crystal device according to the present invention. (a) is a front view, and (b) is a cross-sectional view. First, the configuration will be explained. A rectangular area 2804 surrounded by a dashed line in (a) represents one dot. 2808 is a glass substrate, 2807 is an ITO electrode, 2801 is a red color filter, 2803 is a green color filter, 2802 is a blue color filter, and the hatched area 2806 is acrylic.

[0116]
(Example 21)
33 is a diagram showing the main parts of the structure of a reflective liquid crystal device according to the present invention. The configuration will now be described. 3301 is an upper polarizing plate, 3302 is an element substrate, 3303 is liquid crystal, 3304 is an opposing substrate, 3305 is a light scattering plate, and 3306 is a polarization separation reflector. Opposing electrodes (scanning lines) 3311 and color filters 3310 are provided on the opposing substrate 3304, and signal lines 3307, MIM elements 3308, and pixel electrodes 3309 are provided on the element substrate 3302.

[0122]
Example 22
Figure 37 shows an outline of the structure of a reflective liquid crystal device according to the present invention, with (a) being a front view and (b) being a cross-sectional view. The structure will now be described. Reference numeral 3701 denotes a frame case, 3702 a polarizing plate, 3703 an upper substrate, 3704 a hatched area a color filter, 3705 a lower substrate, and 3706 a polarization separation reflector with a light scattering plate attached. Transparent electrodes, nonlinear elements, signal lines, alignment films, etc. have been omitted to avoid cluttering the drawing. Reference numeral 3711 denotes a driving display area, 3712 an effective display area, and 3713 an area where a color filter is provided. (b) is a horizontal cross-sectional view, but the vertical cross-sectional view is similar to (b). The terms "driving display area" and "effective display area" are defined in ED-2511A of the Electronic Industries Association of Japan (EIAJ) standard as "an area having a display function in a liquid crystal display device" and "a driving display area and the area following it that is effective as a screen," respectively. In other words, the drive display area is the area where a voltage can be applied to the liquid crystal, and the effective display area is the entire liquid crystal panel area that is not hidden by the frame case.

[0124]
(Example 23)
In transmissive color LCD devices, a black mask is typically provided outside the dots. However, providing a black mask in a reflective LCD device results in high contrast but results in an extremely dark display. In LCD modes, such as TN and STN modes, where parallax is unavoidable, light is absorbed twice by the black mask—once upon entry and once upon exit—leading to brightness being proportional to the square of the aperture ratio. Therefore, a black mask cannot be provided in a reflective LCD device. However, providing no light absorber outside the dots at all would significantly reduce contrast, making this undesirable. Therefore, in this invention, a black mask is not provided outside the dots, but instead, color filters with absorption comparable to or less than that of the dot regions are provided. Figure 38 shows the color filter arrangement of a reflective LCD device according to the present invention. The basic configuration and spectral characteristics of the color filters are similar to those of Figures 6 and 6 of Example 5, but the color filter arrangement in the area outside the dots is innovative. In Figure 38, the "horizontally convex" area indicated by 3801 is where the counter electrode and pixel electrode overlap, applying an electric field to the liquid crystal. This corresponds to the dot in claim 11. An area 3802 with diagonal hatching from the upper right to the lower left is a cyan filter, and an area 3803 with cross hatching is a red filter.

[0126]
(Example 24)
Figure 39 shows the color filter arrangement of a reflective liquid crystal device according to the present invention. The basic configuration and spectral characteristics of the color filters are the same as those of Example 9 shown in Figures 8 and 12, but an ingenious approach has been taken with the arrangement of the color filters in the areas outside the dots. In Figure 39, the "horizontally convex" area shown as 3901 is the area where the counter electrode and pixel electrode overlap and where an electric field is applied to the liquid crystal, and corresponds to the dot in claim 11. Area 3902, hatched diagonally from the upper left to the lower right, is a blue filter, area 3903, hatched diagonally from the upper right to the lower left, is a green filter, and area 3904, hatched crosswise, is a red filter.

[0128]
Example 25
Figure 40 is a diagram showing the main components of a reflective liquid crystal device according to the present invention. First, the configuration will be described. Reference numeral 4001 denotes an upper polarizing plate, 4002 denotes a counter substrate, 4003 denotes liquid crystal, 4004 denotes an element substrate, 4005 denotes a light scattering plate, and 4006 denotes a polarization separation reflector. A color filter 4007 and a counter electrode (scanning line) 4008 are provided on the counter substrate 4002, and a signal line 4009, a pixel electrode 4010, and an MIM element 4011 are provided on the element substrate 4004. The color filter has a stripe arrangement that is common in data displays such as PCs. The spectral characteristics of the color filter are the same as those in Figure 12 of Example 9.

[0129]
Figure 41 shows the color filter arrangement of a reflective liquid crystal device according to the present invention. In Figure 41, the "horizontally convex" region indicated by 4101 is the region where the counter electrode and pixel electrode overlap and where an electric field is applied to the liquid crystal, and corresponds to a dot. Furthermore, region 4102 hatched diagonally from the upper left to the lower right is a blue filter, region 4103 hatched diagonally from the upper right to the lower left is a green filter, and region 4104 hatched in a cross pattern is a red filter.

[0134]
(Example 27)
Example 27 is a reflective liquid crystal device according to the present invention, and its structure is similar to that shown in FIG. 1 of Example 1, FIG. 6 of Example 6, and FIG. 8 of Example 7. Its distinctive feature is that MIM elements 111, 611, and 811 are provided on the substrates 104, 604, and 804 located on the reflector side. This arrangement reduces unwanted surface reflection and provides higher contrast than the reverse configuration, i.e., when MIM elements are provided on the substrates 102, 602, and 802. There are three reasons for this. First, reflections from the signal lines 109, 609, and 809 and the MIM elements are partially absorbed by the color filters 107, 607, and 807. Second, the signal lines themselves are constructed by layering metal chromium on metal tantalum, and chromium has a lower reflectivity than tantalum. Third, reflected light passes through the liquid crystal layers 103, 603, and 803, causing absorption due to birefringence interference.

[0135]
(Example 28)
The twenty-eighth embodiment is a reflective color liquid crystal device according to the present invention, and its overall structure is the same as that of the seventh embodiment shown in Fig. 8. Its distinctive feature is the wiring method for the MIM elements.

[0140]
(Example 29)
Figure 45 shows the characteristics of a reflective liquid crystal device according to the present invention. Using a configuration similar to that of Example 2, the graph shows the relationship between the drive area ratio and contrast, as well as the drive area ratio and reflectance when the drive area ratio is changed from 50% to 100%. Here, the drive area ratio is defined as the ratio of the area in which the liquid crystal is driven to the area excluding opaque portions such as metal wiring and MIM elements within a pixel. The horizontal axis represents the drive area ratio, and the vertical axis represents contrast and reflectance. 4501 represents the contrast of this example, 4502 the contrast of the comparative example, 4503 the reflectance of this example when displaying cyan, and 4504 the reflectance of the comparative example when displaying cyan.

[0142]
(Example 30)
In reflective LCD devices, the characteristics of the polarization separating reflector significantly affect brightness, contrast, and viewing angle. The polarization separating reflector has specular reflection characteristics. For reflective LCD devices, a light scattering plate with low scattering properties is desirable, emphasizing brightness and contrast. However, if more than 95% of the incident light is reflected within a 30-degree cone, the viewing angle becomes significantly narrower and unusable. Therefore, in the present invention, a light scattering plate with specific scattering properties is provided between the polarization separating reflector and the LCD panel. Figures 46 and 47 show the characteristics of the layer consisting of the polarization separating reflector and light scattering plate in the reflective LCD device of the present invention. In Figure 46, 4604 denotes the layer in which the light scattering plate is attached to the polarization separating reflector, 4601 denotes light incident at a 45° angle on the scattering reflector surface, 4602 denotes the specularly reflected light, and 4603 denotes a 30-degree cone centered on the specular reflection. In Figure 47, the horizontal axis represents the angle of acceptance of the reflected light, and the vertical axis represents the relative reflection intensity. The reflector of Example 30 has the property that approximately 95% of incident light is reflected within the 30° cone shown in Figure 46. If this is less than 80%, a contrast ratio of 1:10 or more cannot be obtained under normal indoor conditions.

[0147]
(Example 32)
Example 32 relates to a reflective liquid crystal device according to the present invention, but the basic configuration and the spectral characteristics of the color filters are the same as those of Example 5 shown in Figures 6 and 3. The feature is that the TN mode cell conditions are optimized for a reflective liquid crystal device.

[0150]
(Example 33)
Example 33 relates to a reflective liquid crystal device according to the present invention, and its basic configuration is the same as that of Example 2 shown in Fig. 1. Its feature is that the TN mode cell conditions are further optimized for reflective liquid crystal devices.

[0158]
(Example 34)
Figure 52 is a diagram showing the main components of a reflective liquid crystal device according to the present invention. First, the configuration will be described. 5201 is an upper polarizing plate, 5202 is a retardation film, 5203 is an upper substrate, 5204 is liquid crystal, 5205 is a lower substrate, 5206 is a light scattering plate, and 5207 is a polarization separation reflector. A color filter 5208 and a scanning electrode 5209 are provided on the upper substrate 5203, and a signal electrode 5210 is provided on the lower substrate 5205. The retardation film 5202 is a uniaxially stretched polycarbonate film and exhibits a positive retardation. The color filter has the same spectral characteristics as those shown in Figure 3 of Example 2.

[0161]
(Example 35)
Figure 55 is a diagram showing the main parts of the structure of a reflective liquid crystal device according to the present invention. First, the configuration will be explained. 5501 is a polarizing plate, 5502 is a retardation film, 5503 is an upper substrate, 5504 is liquid crystal, 5505 is a lower substrate, 5506 is light scattering, and 5507 is a polarization separation reflector. A color filter 5508 and a scanning electrode 5509 are provided on the upper substrate 5503, and a signal electrode 5510 is provided on the lower substrate 5505. The retardation film 5502 is a uniaxially stretched polycarbonate film and has a positive retardation of 587 nm. The product Δn×d of the Δn of the liquid crystal and the cell gap is 0.85 μm.

[0169]
While the above examples use MIM elements, TFT elements can also be used instead. Figure 58 shows the essential parts of the structure of a reflective color liquid crystal device according to the present invention, fabricated using TFT elements. First, the structure will be described. Reference numeral 5801 denotes an upper polarizing plate, 5802 denotes a counter substrate, 5803 denotes liquid crystal, and 5804 denotes an element substrate. A color filter 5805 and a counter electrode (common electrode) 5806 are provided on the counter substrate 5802, and gate signal lines 5807, source signal lines 5808, TFT elements 5809, and pixel electrodes 5810, which also serve as scattering reflectors, are provided on the element substrate 5804. While the metal wiring in the MIM elements runs only vertically, the metal wiring in the TFT elements runs vertically and horizontally, resulting in a reduced aperture ratio. Fortunately, Example 37 does not require a lower polarizing plate. Therefore, when using TFT elements, it is preferable to provide an insulating film on the layer of elements and signal lines, and then provide a reflector on top of that that also serves as a pixel electrode, and connect the two through contact holes.

[0204]
Figure 69 shows the main parts of a reflective color liquid crystal device according to the present invention. 6901 denotes a scattering plate, 6902 denotes an upper polarizing plate, 6903 denotes a retardation plate, 6904 denotes an upper substrate, 6905 denotes liquid crystal, 6906 denotes a lower substrate, 6907 denotes an opposing electrode (scanning line), 6908 denotes signal lines, 6909 denotes a pixel electrode/mirror reflector, 6910 denotes an MIM element, and 6911 denotes a color filter. The spacing between pixels is 160 μm in both directions perpendicular and parallel to the signal lines, the width of the signal lines is 10 μm, the gap between the signal lines and pixel electrodes is 10 μm, and the spacing between adjacent pixel electrodes is 10 μm.

[0228]
Figure 59 is a cross-sectional view of reflective liquid crystal devices No. 1 and No. 2 according to the present invention. First, the structure will be described. Reference numeral 5901 denotes a scattering plate, 5902 denotes an upper polarizing plate, 5903 denotes an upper substrate, 5904 denotes an upper electrode, 5905 denotes liquid crystal, 5906 denotes a lower electrode, 5907 denotes a lower substrate, 5908 denotes a lower polarizing plate, and 5909 denotes a specular reflector. The liquid crystal 5905 is twisted 90 degrees within the cell, and No. 1 is a TN mode device in which the absorption axes of polarizing plates 5902 and 5908 coincide with the slow axis of the liquid crystal 5905 at the adjacent interface, while No. 2 is a TN mode device in which the absorption axes of polarizing plate 5902 and 5908 each coincide with the slow axis of the liquid crystal 5905 at the adjacent interface. The product Δn × d of the thickness d and birefringence Δn of the liquid crystal 5905 is 0.48 μm.

[0230]
73 is a diagram showing the voltage-transmittance characteristics of a reflective liquid crystal device according to the present invention. Here, 7301 shows the change in transmittance with respect to voltage for No. 1, and 7302 shows the change in transmittance with respect to voltage for No. 2. No. 1 is a normally white display, and No. 2 is a normally black display.

[0235]
Example 40 is a reflective liquid crystal device according to the present invention, characterized in that one dot constitutes one pixel. A pixel is the smallest unit capable of realizing the functions required for display, and in a typical color liquid crystal device, one pixel is composed of one dot each of red, green, and blue, for a total of three dots. Therefore, to display a 480 x 640 pixel VGA, 480 x 640 x 3 dots are required. When using a two-color filter of cyan and red, 480 x 640 x 2 dots are required. However, Example 40, despite being a color liquid crystal device, is capable of displaying a VGA with 480 x 640 pixels.

[0239]
Figure 75 shows an example of an electronic device according to the present invention. This is a so-called PDA (Personal Digital Assistant), a type of portable information terminal. Reference numeral 7501 denotes a reflective liquid crystal device, with a tablet attached to its front for pen input. Conventional PDA displays have used reflective monochrome liquid crystal devices or transmissive liquid crystal devices. Replacing these with reflective color liquid crystal devices offers the advantages of dramatically increasing the amount of information displayed by color displays compared to the former, as well as the advantages of longer battery life and smaller size and lighter weight compared to the latter.

[0240]
Figure 76 shows an example of an electronic device according to the present invention. This is a so-called digital still camera. Reference numeral 7601 denotes a reflective LCD device, mounted so that its angle can be adjusted relative to the main body. Although not shown, a lens is located behind the mounting portion of the reflective color LCD device. Conventionally, transmissive color LCD devices have been used for displays in digital still cameras. By replacing these with reflective color LCD devices, not only have battery life and size been extended, but visibility under direct sunlight has also been significantly improved. This is because, while transmissive color LCD devices have limited backlight brightness and become difficult to see when surface reflection increases in direct sunlight, reflective color LCD devices display brighter as ambient light increases. To effectively utilize this ambient light, it is effective to mount the LCD device so that its angle can be adjusted.

Claims (3)

A reflective liquid crystal device comprising a pair of substrates arranged opposite to each other, a reflective layer formed on one of the pair of substrates, a plurality of dots formed between electrodes formed on the inner surfaces of the pair of substrates, and a plurality of color filters each having a different color corresponding to the plurality of dots,
A reflective liquid crystal device characterized in that a color filter having a smaller light absorption than the color filter provided in the area within the dot is provided in the area corresponding to the outer periphery of each dot. 10. An electronic device comprising the reflective liquid crystal device according to claim 1. 3. The electronic device according to claim 2,
The electronic device is characterized in that the reflective liquid crystal device is movable relative to the main body of the electronic device.