Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-10-26
2001-11-06
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C349S072000
Reexamination Certificate
active
06313821
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to image display devices, and more particularly to an image display device suitable for a personal computer, a word processor, or the like which uses a liquid crystal display as a display unit.
2. Description of the Related Art
Recently personal computers, word processors, and the like have been progressively miniaturized. Accordingly, image display devices employing liquid crystal displays (hereinafter referred to as a LCD) as a display unit, such as in miniaturized and light-weight notebook-sized personal computers, are often used outdoors.
A conventional image display device is described below with reference to
FIGS. 6 and 7
.
FIG. 6
shows a block diagram of the conventional image display device. The image display device includes a manually adjusting operation unit
31
, a contrast adjusting unit
32
, and a display unit
33
.
The manually adjusting operation unit
31
, which includes push button switches
31
a
and
31
b
, manually adjusts a contrast of the image display device. This operation unit
31
is connected to the contrast adjusting unit
32
.
The contrast adjusting unit
32
supplies a control voltage for determining the contrast to the display unit
33
. This unit
32
includes a variable resistor and the like (not shown). For example, by operating push button switches
31
a
and
31
b
in the manually adjusting operation unit
31
, the resistance of the variable resistor in the contrast adjusting unit
32
varies, which as a result causes the contrast of the display unit
33
to vary.
The display unit
33
displays an image signal from, for example, a personal computer (not shown). In addition to the image signal from the personal computer, the control voltage and the like are input from the contrast adjusting unit
32
to the display unit
33
.
For example, the relationship between temperature of the display unit
33
and contrast, when using the LCD as the display unit
33
, is shown in FIG.
7
. When a constant control voltage is supplied to the LCD, the contrast decreases in accordance with an increase in the temperature; when the temperature of the display unit
33
is constant, the contrast decreases in accordance with a decrease in the control voltage.
When the temperature decreases from T
1
to T
2
under the constant control voltage V
1
, the contrast increases from C
1
(corresponding to a point P
1
) to C
2
(corresponding to a point P
2
). To obtain a contrast C
1
at temperature T
2
, a control voltage V
2
, which is lower than the control voltage V
1
, must be supplied to the display unit
33
.
Accordingly, by operating the push button switch
31
b
in the manually adjusting operation unit
31
so as to decrease the control voltage to the control voltage V
2
, a standard contrast C
1
(corresponding to a point P
3
) is obtained.
On the other hand, when the contrast C
1
(corresponding to the point P
3
) is obtained at temperature T
2
under the constant control voltage V
2
, the contrast decreases to C
3
(corresponding to a point P
4
) in accordance with an increase in the temperature to T
1
. In this case, by operating the push button switch
31
a
in the manually adjusting operation unit
31
so as to increase the control voltage to the control voltage V
1
, a standard contrast C
1
(corresponding to the point P
1
) is obtained.
As describe above, a change in the temperature under the constant control voltage affects the contrast due to the LCD temperature characteristics. Therefore, whenever the temperature changes, a user is inconvenienced since the user must manually adjust the contrast so that the contrast of the image displayed on the display unit
33
has the most preferable level.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an image display device for solving the problems discussed above.
To this end, according to one aspect of the present invention, the image display device includes a temperature sensor, a controller to which detected temperatures obtained by the temperature sensor are input, and controls an input time interval of the detected temperatures while it adjusts a contrast of an image displayed on a display unit and a storage unit. The storage unit stores data representing the relationships between control voltages and the temperatures of the display unit under the control voltages for optimizing the contrast of the image. The controller acquires the detected temperatures from the temperature sensor at each first time interval for a predetermined period of time subsequent to the start of supplying power to the display unit, and supplies the display unit with the control voltages corresponding to temperatures which are equivalent to the acquired temperatures, and which are represented by the data stored in the storage unit. After the predetermined period of time, the detected temperatures are acquired at each second time interval longer than each first time interval. It is an object of the present invention to provide an image display device with the above arrangement. By doing this, the image display device with its ability of displaying the image with the best contrast can be used right after the power is supplied to the display unit.
In an image display device according to a first aspect of the present invention, a predetermined standard temperature difference may be stored in the storage unit. When the detected temperatures are input from the temperature sensor to the controller at each second time interval, and a temperature difference between a presently detected temperature at each input time and the temperature detected just before the presently detected temperature is greater than the standard temperature difference, the detected temperature may be immediately input to the controller at each first time interval for the predetermined period of time. It is another object of the present invention to provide an image display device with the above arrangement. By doing this, the image display device with its ability of displaying the image with the best contrast can be used regardless of a rapid temperature change in the display unit which a change of its operating environment may bring.
In an image display device according to a first aspect of the present invention, the controller may include a manually adjusting operation unit for manually adjusting the contrast of the image. The manually adjusting operation unit may modify data representing the relationships between the control voltages and the temperatures of the display unit under the control voltages for optimizing the contrast of the image, thereby supplying the display unit with the control voltages corresponding to temperatures which are equivalent to the acquired temperatures and which are represented by the modified data stored in the storage unit which represents the relationships between the control voltages and the temperatures of the display unit under the control voltages for optimizing the contrast of the image. It is a further object of the present invention to provide an image display device with the above arrangement. By doing this, even though a user adjusts the contrast of the image to his or her preference, the image display device with its ability of automatically adjusting to the best contrast can be used.
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Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Piziali Jeff
Shalwala Bipin
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