Horology: time measuring systems or devices – Displays or display device details – Optical
Patent
1998-08-24
2000-11-14
Miska, Vit
Horology: time measuring systems or devices
Displays or display device details
Optical
349 96, 349 97, 349113, G04C 1700, G02F 11333, G02F 11335
Patent
active
061479373
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a display device and, more particularly, to a transflective display device having a multi-color display capability. The present invention also relates to an electronic watch such as a wristwatch or stopwatch for counting and presenting time. More particularly, the present invention relates to an electronic watch having a transflective multi-color display capability.
2. Description of Related Art
Conventionally known as a display device is a transflective liquid-crystal display device constructed of a liquid crystal. The liquid-crystal display device is constructed of a polarization axis varying optical device varying its polarization axis, such as a TN (Twisted Nematic) liquid, an STN (Super-Twisted Nematic) liquid crystal and the like. More particularly, the polarization axis varying optical device is interposed between two polarizers, and a semi-transmissive reflector and a light source are respectively arranged on the viewer's side and the opposite side of the liquid-crystal display device. The liquid-crystal display device is used as a reflective display device for example, in outdoor environments where the external light is available, and is used as a transmissive display device with the light source lit where no sufficient external light is available.
The transflective liquid-crystal display device thus constructed suffers dark display during reflective displaying, compared with a reflective liquid-crystal display device without transmissive function. The reason for this is that a reflector used in the conventional transflective liquid-crystal display device is manufactured of a very thin Al (aluminum) or is provided with an opening to assure light transmittance at the expense of brightness during reflective displaying. The conventional transflective liquid-crystal display device has difficulty in presenting a multi-color display both in a reflective display and a transmissive display.
SUMMARY OF INVENTION
The present invention has been developed in view of the above problem, and it is an object of the present invention to provide a very bright display during the reflective displaying in a transflective display device while assuring a multi-color display both in the reflective and the transmissive display.
(1) To achieve the above object, the display device of the present invention comprises:
(a) polarization axis varying means for varying a polarization axis,
(b1, b2) first polarizing splitter means and second polarizing splitter means respectively arranged on the front and rear sides of the polarization axis varying means with the polarization axis varying means interposed therebetween; and
(c) a light source arranged on the side of the second polarizing splitter means opposed to the polarization axis varying means with the second polarizing splitter means interposed therebetween;
(d) wherein the first polarizing splitter means has the function of transmitting all wavelengths, in the visible light region, of a light ray component linearly polarized in a first direction, and transmitting a specific wavelength, in the visible light region, of a light ray component linearly polarized in a second direction perpendicular to the first direction with the remaining wavelength component not transmitted therethrough.
(e) the second polarizing splitter means has the function of transmitting a light ray component linearly polarized in a third direction while reflecting a light ray component linearly polarized in a direction perpendicular to the third direction; and
(f) the light source emits a colored light ray.
The display device thus constructed presents two display states in connection with a light ray coming in from outside the first polarizing splitter means: a first display state that is presented by a light ray which is reflected from the second polarizing splitter means depending on the state of the polarization axis of the polarization axis varying means and a second display state that is presented by a light ray of
REFERENCES:
patent: 5341231 (1994-08-01), Yamamoto et al.
patent: 5361151 (1994-11-01), Sonehara et al.
patent: 5663777 (1997-09-01), Aoyama
patent: 5805252 (1998-09-01), Shimada et al.
Arikawa Yasuo
Maeda Tsuyoshi
Miyazawa Eiichi
Miska Vit
Seiko Epson Corporation
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