Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2000-10-11
2003-04-22
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S088000, C345S098000, C345S102000, C345S205000, C345S100000
Reexamination Certificate
active
06552711
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
The present invention claims priority from Japanese Patent Application No. 11-290518 filed Oct. 13, 1999, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a display device capable of displaying a color image and an information terminal using the same display device and, particularly, to a display device for displaying an image by using liquid crystal and an information terminal such as portable telephone set in which the same display device is incorporated to display an information.
2. Description of Related Art
With the development of the digital technology and the communication technology, the multi-media industries handling data containing moving picture and voice have been expanding at high rate. For example, most of electronic devices such as portable telephone sets and mobile personal computers can be connected to other electronic devices or servers through cables or radio wave to take in or transmit various information. In the following description, not only the portable telephone set or PHS (Personal Handy-phone System) but also all of electronic devices functioning as terminals will be defined as information terminals and the term “information terminal” will be used in the above meaning.
Most of the information terminals include displays as devices for displaying information visually. Although a CRT (Cathode Ray Tube) has been used mainly for that purpose, there is a problem that the CRT is large in not only space occupation but also power consumption. In view of this fact, a liquid crystal display has been used in a portable information terminal driven by a battery. The liquid crystal display is featured by that it is possible to substantially reduce power consumption compared with the CRT.
Among the liquid crystal displays, a monochromatic liquid crystal display is advantageous compared with a color liquid crystal display in that the power consumption can be reduced substantially. The reason for this is that a drive circuit for a monochromatic display is simple enough to display a monochromatic image and, when a fine gradation of image is not required, the drive circuit can be further simplified. Further, it may be possible to eliminate a back-light for enabling a display even in a dark area.
On the contrary, in a display for displaying a color image, the image is displayed by using three primary colors RGB (Red, Green and Blue). Therefore, drive circuits corresponding to these primary colors are required, whose circuit constructions become complicated and consume power correspondingly when many tones are to be displayed. Further, in order to display an image with natural color including many color tones, it is necessary to always light a back-light for illuminating a rear side of liquid crystal with enough brightness thereof. In view of this fact, it is usual to use the monochromatic liquid crystal display in a device such as portable telephone set which is small in size and whose battery capacity is small.
FIG. 7
shows an example of a construction of a color liquid crystal display for use in a portable telephone set as a conventional information terminal capable of receiving multi-media, which is disclosed in JP-A 6-301032, color liquid display
100
is constructed with color light radiation source
101
, liquid crystal display panel
102
and liquid crystal shutter
103
arranged between color light sources
101
and liquid crystal display panel
102
. Color light radiation source
101
is constructed with color light sources
101
R,
101
G and
101
B such as fluorescent lamps, tungsten lamps or CFL tubes corresponding to the three primary colors. In a case where these light sources are candescent light sources, three primary color filters are provided in front of these light sources, respectively. When color light sources
101
R,
101
G and
101
B are ON/OFF controlled frequently corresponding to colors of an image, there is a problem that the life of color light radiation source
101
composed of fluorescent lamps, etc., is shortened. When the color light radiation source
101
is composed of tungsten lamps, there is a problem that the response to a color change is degraded.
In view of these problems, liquid crystal shutters
103
R,
103
G and
103
B are arranged correspondingly to respective color light sources
101
R,
101
G and
101
B and ON/OFF controlled. Lights selectively passed through liquid crystal shutters
103
R,
103
G and
103
B radiate liquid crystal display panel
102
and a desired color image is displayed by synthesis of these three primary colors.
As mentioned above, in conventional color liquid crystal display
100
, all of color light sources
101
R,
101
G and
101
B corresponding to the respective three primary colors are lit when a color display is performed. This is also true when a monochromatic display is performed. Therefore, there is a problem that the power consumption of color liquid crystal display
100
is substantially increased compared with the display, which can display only monochromatic image.
FIG. 8
shows a construction of a display portion of an information terminal having reduced power consumption. Display portion
120
, which is disclosed in JP-A 10-63196, is constructed with color liquid crystal portion
121
and monochromatic liquid crystal portion
122
. Color liquid crystal portion
121
displays only moving image with color and monochromatic liquid crystal portion
122
displays other images. Therefore, when other information such as text information than a moving image information is displayed, monochromatic liquid crystal portion
122
is used and light sources of color liquid crystal portion
121
are turned OFF to reduce the power consumption.
FIG. 9
is a perspective view of another example of an information terminal having reduced power consumption, showing an outer configuration thereof and
FIG. 10
is a side view of the same information terminal. In these figures, information terminal
131
includes main body portion
133
on a surface of which keyboard
132
is provided and cover portion
134
. As shown in
FIG. 10
, cover portion
134
is hinged about rotary joint portion
135
such that either one of surfaces thereof can be looked from the side of keyboard
132
. Color liquid crystal portion
136
is incorporated in one of the surfaces of cover portion
134
and monochromatic liquid crystal portion
137
is incorporated in the other surface. A display drive portion, which is not shown, provided within main body portion
133
performs a display control such that only one of the liquid crystal portions, which faces to the side of keyboard
132
, is activated. Therefore, a user of information terminal
131
wishes a color image display, he turns cover portion
134
to provide color liquid crystal portion
136
on the side of keyboard
132
. When the user wishes to see a monochromatic image in order to reduce power consumption or for other reasons, he turns the cover portion to provide monochromatic liquid crystal portion
137
on the keyboard side.
As described, since, in the case of color liquid crystal display
100
shown in
FIG. 7
, it is impossible to reduce power consumption even when the monochromatic display is performed, it has been usual to reduce power consumption by providing the color liquid crystal display portion and the monochromatic liquid crystal display portion as shown in
FIG. 8
or FIG.
10
. With such construction, it becomes unnecessary to light all of the light sources for the three primary colors for the monochromatic display to thereby make a use of one kind of light source such as candescent light source possible. However, since either one of the prior art information terminals has to equip with two kinds of liquid crystal displays, there is a problem that the manufacturing cost of the information terminal is substantially increased.
Further, in the information terminal shown in
FIG. 8
, it is necessary to arrange color liquid crystal por
Hjerpe Richard
NEC Corporation
Sughrue & Mion, PLLC
Zamani Ali
LandOfFree
Display device and information terminal does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Display device and information terminal, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Display device and information terminal will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3009006