Liquid crystal cells – elements and systems – Particular structure – Particular illumination
Reexamination Certificate
1996-01-29
2001-09-04
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Particular illumination
C362S035000
Reexamination Certificate
active
06285420
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an illuminator for illuminating a display member, a display device provided with a display member illuminator, and an appliance provided with a display device.
In recent years, a wide variety of functions are given to highly sophisticated appliances, for example, office automation appliances such as copying machine, printer, and desk-upper computer, optical appliances such as camera, audio appliances, video appliances, television sets, video game machines, and the like. In these appliances, an LCD (liquid crystal display) member has been generally used to display an operative state of the appliance in letters and figures. Also, there has been recently proposed use of PLZT (lead lanthanum zirconate titanate) as a display member for such appliances.
However, such display members do not emit light themselves. Accordingly, when a display device provided with such display member is used in dark, e.g., at night, a display image cannot be visually recognized. For this reason, there is usually provided a display member illuminator for illuminating the front or rear surface of a display member such as LCD member.
FIG. 9
shows a conventional display device. This display device includes an LCD member
30
and an LCD illuminator for illuminating the LCD member. The LCD illuminator includes an electroluminesent member
80
provided at a back of the LCD member
30
to supply light to the LCD member
30
and a drive circuit
90
for supplying a high voltage to the electroluininesent member
80
. The electroluminesent member
80
emits light to illuminate the LCD member
30
uniformly. A specified image appears and disappears on the surface of the LCD member
30
in accordance with application of a drive voltage to transparent electrodes of the LCD member.
However, the electroluminesent member
80
requires an alternating current having a high voltage to emit light, inevitably making the size of the drive circuit
90
undesirably large. Thus, it has been very difficult to mount the LCD display device provided with such electroluminesecent illuminator on highly sophisticated appliances, such as a camera, which need a compact construction.
FIG. 10
shows another conventional display device. In this display device, an LCD member
30
is placed over a light guiding member
40
made of glass having substantially the same size as the LCD member
30
. A light emitting member
50
including an LED (light emitting diode) is provided on one side end of the light guiding member
40
. Light from the light emitting member
50
incident on the light guiding member
40
is diffused in the member
40
, and is supplied to the LCD member
30
through the top surface of the member
40
. Accordingly, the LCD member
30
is uniformly illuminated by the light having passed through the member
40
. Since the LED can emit light upon a very small electric power, it is not necessary to provide a large drive circuit as in the above-mentioned LCD illuminator. Japanese Unexamined Utility Model Publication Nos. 56-52788, 4-40269, and 6-25802 disclose a display device provided with such LCD illuminator.
However, the light from the light emitting member
50
is incident only on the light guiding member
40
through its end surface, and is supplied to the LCD member
30
after being diffused in the light guiding member
40
. Accordingly, in order to obtain a large amount of illuminating light, the light guiding member
40
needs to have a large thickness. This makes the combined size of the LCD illuminator and the display device larger. Accordingly, it has been very difficult to mount the display device provided with such LCD illuminator on compact highly sophisticated appliances.
FIG. 11
shows still another conventional display device. In this display device, there is provided an illuminator including a frame
60
for supporting an LCD member
30
and a plurality of LEDs
51
arranged in an illumination chamber
60
a
of the frame
60
beneath the LCD. The inner wall surfaces
60
b
of the illumination chamber
60
a
that tapers toward the lower act as a reflector. The light emitted from the LEDs is gathered and diffused upon being reflected by the reflector
60
b
, and then is incident on the LCD member
30
. A display device of this type is disclosed in Japanese Unexamined Utility Model Publication No. 60-150585 and Japanese Unexamined Patent Publication No. 2-53040.
However, the illumination chamber
60
a
formed with the reflector
60
b
is provided below the LCD member
30
. This makes the entire size of the LCD illuminator larger. Thus, similar to the above-mentioned conventional display devices of
FIGS. 9 and 10
, it has been difficult to mount the display device provided with such illuminator on compact highly sophisticated appliances.
Further, Japanese Unexamined Patent Publication No. 2-47630 discloses a display device provided in a viewfinder of a camera. In this device, an LCD member includes an LC (liquid crystal) cell and upper and lower plates sandwiching the cell. A light emitting member is attached on one side end of the LCD member. Illuminating light is introduced from the light emitting member into the upper and lower plates to illuminate the LC cell.
This display device is used in the viewfinder of a camera that has a small viewing area. The viewing area is not larger than 1 cm
2
, which thus does not require a large amount of illuminating light. Accordingly, such LCD illuminator cannot be used for a display device having a large viewing area which requires a large amount of light.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a display member illuminator for illuminating a display member which can supply a larger amount of illuminating light to a display member in a smaller size.
It is another object of the present invention to provide a display device which is smaller in size and can produce a sufficiently bright display image.
It is still another object of the present invention to provide an appliance which is provided with a bright and compact display device.
The present invention is directed to an illuminator for illuminating a display member, comprising: a light guiding member which faces and extends in parallel with a display member; and a light source which faces both a side end of the display member and a side end of the light guiding member and supplies light to both the display member and the light guiding member by way of their respective side ends.
The display member may include a liquid crystal display. It may be appreciated to use a liquid crystal display capable of passing light therethrough. In this case, the light guiding member is preferably disposed below the display member. Also, it may be appreciated to use a liquid crystal display capable of reflecting incident light at a bottom thereof. In this case, the light guiding member is preferably disposed above the display member. Further, it may be preferable that the light guiding member forms a display window through which a display image on the display member is viewed.
Also, the present invention is directed to a display device comprising: a display member; a light guiding member which faces and extends in parallel with the display member; and a light source which faces both a side end of the display member and a side end of the light guiding member and supplies light to both the display member and the light guiding member by way of their respective side ends.
Further, the present invention is directed to an appliance comprising: a display portion; a display member provided in the display portion; a light guiding member which faces and extends in parallel with the display member; a light source which faces both a side end of the display member and a side end of the light guiding member and supplies light to both the display member and the light guiding member by way of their respective side ends, and a driver which drives the display member to produce a display image.
According to the present invention, light from the light source is incident on
Mizumo Yoshiyuki
Takahashi Makoto
Minolta Co. , Ltd.
Parker Kenneth
Sidley & Austin
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