Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2003-01-10
2004-07-20
Ton, Toan (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S111000, C349S113000, C349S114000
Reexamination Certificate
active
06765639
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a liquid crystal display device and electronic equipment. More specifically, the present invention relates to a reflective or semitransmissive reflective liquid crystal display device having a reflective layer or a semitransmissive reflective layer and to electronic equipment using the liquid crystal display device.
2. Description of Related Art
Recently, reflective or semitransmissive reflective liquid crystal display devices have been proposed. These devices have a reflective layer which uses, for example, a metal thin film or a semitransmissive reflective layer which uses a material, such as a cholesteric liquid crystal. For example, Al and Ag having a high reflectivity are used as the metal thin film. In such a device, incident extraneous light, such as sunlight and luminous light, is reflected through a liquid crystal layer, and the liquid crystal layer is driven so as to create a reflective display.
The cholesteric liquid crystal can include liquid crystal molecules structurally arrayed as a periodic helix with a constant pitch, selectively reflects light with a wavelength corresponding to the pitch of the helix and transmits the other light. Such a device using a reflector plate having the cholesteric liquid crystal selectively reflects light with a specific wavelength and transmits the other light to create a semitransmissive reflective display.
These types of reflective or semitransmissive reflective liquid crystal display devices can each include a plurality of dot display domains separated by black matrices, and either one of the dot display domains is capable of displaying one of the light's three primary colors. A trio of red, green and blue dots display domains forms a pixel. Each black matrix separating the dot display domains serves to create a black display in the formation zone and uses, for example, a resin shielding film containing a pigment.
When such a resin shielding film is used as the black matrix, the resin shielding film might transmit trace light, although it absorbs light. If the shielding film transmits the light, it may cause light leakage to thereby reduce contrast.
SUMMARY OF THE INVENTION
The present invention has been accomplished to solve the above problems, and an object of the present invention is to provide a liquid crystal display device that can reliably avoid color mixing between dot display domains at the boundary therebetween and can prevent or suppress decrease in contrast. Another object of the present invention is to provide electronic equipment using the liquid crystal display device.
To achieve the above objects, the present invention can provide a liquid crystal display device having a liquid crystal cell, the liquid crystal cell including a pair of substrates facing each other and a liquid crystal layer disposed between the pair of substrates. The liquid crystal display device can include a plurality of dot display domains separated by a boundary domain and disposed in a plane, a specific circularly polarized light introducing device that is capable of introducing circularly polarized light having a predetermined rotational direction between the pair of substrates, and a reflecting device that is capable of at least reflecting circularly polarized light, the reflecting device including a rotational direction controlling device that is capable of controlling the rotational direction of the circularly polarized light reflected in the dot display domains to differ from that reflected in the boundary domain.
In this device, when circularly polarized light having a predetermined rotational direction enters between the pair of substrates from the specific circularly polarized light introducing device and is reflected by the reflecting device, the circularly polarized light reflected in the dot display domains can have a rotational direction different from that reflected in the boundary domain. Accordingly, the circularly polarized light reflected in the dot display domains can exit from the specific circularly polarized light introducing device, and the circularly polarized light reflected in the boundary domain cannot exit from the specific circularly polarized light introducing device.
Specifically, the specific circularly polarized light introducing device can allow the circularly polarized light reflected in a dot display domain to exit to thereby create a bright display in the dot display domain and can allow the circularly polarized light reflected in the boundary domain not to exit to thereby create a dark display in the boundary domain. Accordingly, the device can use the domain capable of at least producing a bright display as a display domain (pixel domain) that contributes to display, and the domain capable of producing a dark display as a non-display domain that does not contribute to display, i.e., a black matrix. The rotational direction of the incident circularly polarized light in a dot display domain can be changed based on the orientation mode of the liquid crystal layer. By this configuration, a bright or dark display can freely be created in the dot display domain.
This configuration can be easily formed and is resistant to transmittance in the black matrix to prevent or suppress decrease in contrast due to light leakage. The contrast decreases due to transmittance in the black matrix in the following manner. In reflective display, for example, light transmitting the black matrix is reflected and contributes to a bright display. In semitransmissive reflective display, for example, light passing through the black matrix in transmissive display contributes to a bright display. Thus, the present invention can achieve a configuration that yields less decrease in contrast than a configuration using a resin shielding film as a black matrix in a liquid crystal display device which creates at least a reflective display. The term circularly polarized light as used herein also includes elliptically polarized light
More specifically, the reflecting device may include a first reflective layer capable of reflecting at least a part of circularly polarized light having a predetermined rotational direction and capable of allowing the circularly polarized light after reflection to have the same rotational direction as that before reflection, and a second reflective layer capable of at least reflecting circularly polarized light and capable of allowing the circularly polarized light after reflection to have a different rotational direction from that before reflection, in which the first reflective layer and the second reflective layer are disposed in either of the dot display domains and the boundary domain, respectively.
In this device, the first reflective layer is capable of allowing the circularly polarized light after reflection to have the same rotational direction as that before reflection and the second reflective layer is capable of allowing the circularly polarized light after reflection to have a different rotational direction from that before reflection. Thus, a dark display as a black matrix can reliably be created in the boundary domain. When the first reflective layer structurally reflects a part of and transmits the other part of circularly polarized light having a predetermined rotational direction, the first reflective layer serves as a semitransmissive reflective layer. For example, by allowing the rotational direction of incident circularly polarized light in a domain where the first reflective layer is disposed to vary depending on the orientation mode of the liquid crystal layer, a reflective or transmissive display can be optionally created in the dot display domain. In this case, the second reflective layer plays a role as a black matrix in reflective display as above. In contrast, a transmissive display can be created by allowing the first reflective layer to transmit light from a light source (hereinafter referred to as internal light) that can enter in a direction different from that in the reflective display. The se
Schechter Andrew
Ton Toan
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