Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-09-25
2003-03-11
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S074000, C349S075000, C349S076000, C349S139000, C349S097000
Reexamination Certificate
active
06532048
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a display device and an electronic device using the display device, and more particularly, to the structure of a display device using a transmitted light polarization axis changing device formed of a liquid crystal panel or the like.
2. Description of Related Art
Conventionally, liquid crystal display devices have been used in various recent electronic devices, such as portable telephones, portable music playback devices, timepieces, cameras, VTRs, microwave ovens, and telephones. Display sections of such electronic devices appropriately employ a text information display section for displaying characters, numerals, symbols, and the like by a combination of a plurality of dot regions or segment regions, and an icon display section for displaying icons, for example, predetermined patterns, such as illustrations, special symbols, and marks, by using exclusive one or more segment regions.
The text information display section adopts a dot matrix method in which various character information and the like can be freely rewritten and characters and the like are represented by a group of small dots, and a segment method, such as a seven-segment method for expressing numerals, in which characters and the like are expressed by a combination of a plurality of segments.
In contrast, the icon display section displays illustrations, symbols, words, and the like in a fixed manner, and displays information such as the settings and current situation of the electronic device and a warning to the user in a predetermined fixed form. Specific examples thereof are a display section of a portable device for displaying the remaining quantity of a battery in several stages (an illustration of a battery), a display section of a portable telephone for displaying the strength of radio waves in several stages (an illustration of a radio wave), a display section of an electronic timepiece for showing that the alarm has been set (“ALARM”), and a display section of a chronograph for showing that timing is stopped (“STOP”).
In a conventional liquid crystal display device using, for example, a known TN or STN liquid crystal display panel, two polarizers are placed on the front and back sides of a liquid crystal cell in an orientation such that the transmitted-light polarization axes thereof are orthogonal to each other, the polarization axis direction of polarized light which has passed through one of the polarizers is changed or maintained according to the presence or absence of an electric field applied to a liquid crystal layer in the liquid crystal cell, and a light blocking state and a light transmitting state of the liquid crystal display panel are switched by causing the polarized light to be blocked by the other polarizer or to be passed therethrough. Since a display surface appears dark in the light blocking state of the liquid crystal display panel and light in the light transmitting state, various information can be displayed by using the dark and light colors.
In order to form an icon display section in the above display device using the liquid crystal display panel, however, transparent electrodes, reflecting electrodes, and the like formed on the inner surface of a panel substrate of the liquid crystal display panel must be formed in the shape of the icons. For this reason, when producing liquid crystal display panels having different icon forms, liquid crystal cells must be designed and produced for each icon. Even if the other portions, for example, text information display sections, remain just the same in structure, the panel structure cannot be commonly used. In this case, in order to form icons having fine patterns and lines and complicated icons using a plurality of colors, an electrode pattern also needs to have a fine structure. This makes production significantly difficult, and is not practical.
In contrast, another method is known in which constantly visible icons are formed on a panel substrate of a liquid crystal display panel by printing or by other methods, and a display for indicating the selection state of the icons is produced by the liquid crystal display panel as required. In this case, however, the icons are constantly displayed, and therefore, visibility is low. Moreover, the indication display is also required, and this occupies a large part of the display area.
SUMMARY OF THE INVENTION
In a liquid crystal display device having both a text information display section and an icon display section, since text information and an icon display or an icon indicating display are shown in the same color on the same background, they are completely harmonized. For example, an icon for drawing the user's attention is inconspicuous, and therefore, is not noticed by the user.
In particular, in the display sections of portable devices, such as portable telephones, portable CD players, and portable MD players, since multiple abstract and small icons are displayed in a small display area, it is difficult to grasp displayed information.
The present invention aims to solve the above problems, and an object of the present invention is to realize a new display technique for a display device for reliably producing icon displays of various designs and allowing displayed information to be easily grasped, and to provide a display device which provides high visibility in an electronic device and the like.
An exemplary embodiment provided by the present invention in order to achieve the above object is a display device including a transmitted light polarization axis changing device for changing the polarization axis of transmitted light in each control region, first and second polarization separating elements placed on both sides of the transmitted light polarization axis changing device, an optical modulation layer formed or placed in a predetermined modulation pattern on the side of the second polarization separating element opposite from the transmitted light polarization axis changing device, and a light reflecting layer placed on the side of the optical modulation layer opposite from the second polarization separating element, wherein the first polarization separating element emits a linearly polarized light component, polarized in a first direction, of light entering from the side opposite from the transmitted light polarization axis changing device toward the transmitted light polarization axis changing device, and emits a linearly polarized light component, in the first direction, of light entering from the transmitted light polarization axis changing device toward the opposite side, the second polarization separating element transmits a linearly polarized light component, in a second direction, of light received from the side of the transmitted light polarization axis changing element toward the optical modulation layer, reflects a linearly polarized light component, in a third direction different from the second direction, of the light received from the side of the transmitted light polarization axis changing device toward the transmitted light polarization axis changing device, and emits a linearly polarized light component, in the second direction, of light received from the optical modulation layer toward the transmitted light polarization axis changing device, a display pattern portion is formed at a position in the modulation pattern of the optical modulation layer corresponding to the control region in a plane, and the control region completely covers a region of the display pattern portion necessary as a display portion.
According to this embodiment, when external light enters the first polarization separating elements, a linearly polarized light component thereof in the first direction is transmitted therethrough and enters the transmitted light polarization axis changing device. The linearly polarized light component is caused to appropriately change the polarization axis by the transmitted light polarization axis changing device, and then enters the second polarization separating element. T
Chung David
Parker Kenneth
Seiko Epson Corporation
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