Luminous display unit

Details Luminous display unit Luminous display unit

2001-08-24

2003-05-27

Phan, Tho (Department: 2821)

Electric lamp and discharge devices: systems

Plural power supplies

Plural cathode and/or anode load device

C315S169100, C313S497000

Reexamination Certificate

active

06570337

ABSTRACT:

TECHNICAL FIELD
This invention relates to a luminous display unit e.g., a luminous display unit using a self light emitting element such as an organic electroluminescence element (OLED), a fluorescent display tube, a light emitting diode (LED), etc.
BACKGROUND OF THE INVENTION
As shown in
FIG. 5
, an OLED
5
has at least an anode
2
constructed by a transparent electroconductive material such as indium, tin, oxide (ITO), etc., an organic layer
3
constructed by one or more layers (constructed by at least a single layer structure of an organic light emitting layer, or a multilayer structure in which a positive hole injecting layer, a positive hole transport layer, an electronic transport layer and an electronic injecting layer, etc. are laminated and formed from an anode side in accordance with the organic light emitting layer), and a cathode
4
constructed by a metallic electroconductive material such as aluminum (Al), etc. on a transparent substrate
1
. For example, this OLED
5
is known in Japanese Patent Publication No. 32307/1994. The OLED
5
can emit light in a predetermined desirable pattern by shapes of the anode
2
and the cathode
4
. Further, it is possible to perform display in constant electric current driving from a direct current power source vcc from several volts to several ten volts.
When a luminous display unit
100
using such an OLED
5
is utilized as a digital type distance recorder of a display unit for a vehicle, as shown in
FIG. 6
, the anode
2
is divided into seven segments
2
a
to
2
g
arranged in an 8-shape so that Arabic numerals “0” to “9” are artificially displayed. Numerals of plural digits can be displayed by arranging a plurality of such anodes in a transversal direction. For example, such a construction is known in Japanese Patent Laid-Open No. 106887/1997.
FIG. 6
shows an example of six-digit display able to display “000000” to “999999”.
It is known that light emitting intensity in each of the segments
2
a
to
2
g
is reduced in accordance with a light emitting time. For example, when the light emitting time is ten thousand hours, light emitting luminance is reduced to about 50% of the original light emitting luminance.
If each of the segments
2
a
to
2
g
emits light for a uniform light emitting time, the reductions in light emitting luminance are uniform. Therefore, no difference in light emitting luminance between the respective segments
2
a
to
2
g
is almost caused irrespective of the length of a using time of the luminous display unit.
However, when there is a large difference in light emitting time, the difference in light emitting luminance is increased. Accordingly, as the using time of the luminous display unit is lengthened, this difference is enlarged. When these segments
2
a
to
2
g
simultaneously emit light, there is a case in which a feeling of physical disorder is felt by the difference in light emitting luminance. In such a state, goods property is greatly damaged.
In the case of the digital type distance recorder, light emitting frequency of each of the segments
2
a
to
2
g
in the display of numerals “0” to “9” of ten kinds in each digit is provided as shown in FIG.
7
. In
FIG. 7
, the segment
2
c
has a maximum light emitting frequency of nine times, and the segment
2
e
has a minimum light emitting frequency of four times. When it is supposed that the light emitting time of each of the numerals “0” to “9” is uniform, the light emitting time of the segment
2
c
is 2.25 times the light emitting time of the segment
2
e.
Accordingly, although it is the same digit, the light emitting luminance of the segment
2
c
is rapidly reduced in comparison with the light emitting luminance of the segment
2
e
. When this difference in light emitting luminance is increased to such an extent that this difference can be recognized, a problem exists in that a user has a feeling of physical disorder. When the difference in light emitting luminance is equal to or greater than a value corresponding to 30% of a higher light emitting luminance among these light emitting luminances, it is confirmed by an experiment of the present inventors, etc. that the difference in light emitting luminance between both the segments can be recognized.
When no numeral “0” is displayed on an upper digit side, i.e., when “120” having no numerals “0” in upper three digits is displayed as a blank display instead of “000120” displaying numerals “0” in the upper three digits in display of the numeral “120” (in the case of a so-called leading zero suppress display), the light emitting time in the upper digit is shortened in comparison with a lower digit so that a problem similar to the above problem is caused.
Disclosure of the Invention
The present invention resides in a luminous display unit having plural light emitting portions by using a self light emitting element reduced in light emitting luminance in accordance with a light emitting time and having differences in light emitting time in their light emitting portions, and characterized in that, when a light emitting mode in said light emitting portions is regularly determined, said light emitting time is presumed from light emitting frequencies of said light emitting portions calculated from said light emitting mode, and the light emitting luminances are set to be different from each other from the first in a light emitting portion having a large light emitting frequency and a light emitting portion having a small light emitting frequency at a using time of said luminous display unit so as not to recognize a difference in light emitting luminance caused between both the light emitting portions at said using time. For example, each of luminous display units
100
,
110
has plural segments
21
a
to
21
g
(light emitting portions) by using an OLED (a self light emitting element) reduced in light emitting luminance in accordance with a light emitting time and has differences in light emitting time in their light emitting portions. When a light emitting mode in the segments
21
a
to
21
g
is regularly determined, the light emitting time of each of the segments
21
a
to
21
g
is presumed from light emitting frequencies of the segments
21
a
to
21
g
calculated from this light emitting mode, and the light emitting luminances are set to be different from each other from the first in a light emitting portion having a large light emitting frequency and a light emitting portion having a small light emitting frequency at a using time of each of the luminous display units
100
,
110
so as not to recognize a difference in light emitting luminance caused between both the light emitting portions at the using time. Thus, the generation of a large difference in light emitting luminance of each of the segments
21
a
to
21
g
is prevented at the using time of each of the luminous display units
100
,
110
so that goods property can be maintained.
The present invention also resides in a luminous display unit having plural light emitting portions by using a self light emitting element reduced in light emitting luminance in accordance with a light emitting time and having differences in light emitting time in their light emitting portions, and characterized in that, when a light emitting mode in said light emitting portions is regularly determined, said light emitting time is presumed from light emitting frequencies of said light emitting portions calculated from said light emitting mode, and the light emitting luminances are set to be different from each other from the first in a light emitting portion having a large light emitting frequency and a light emitting portion having a small light emitting frequency at a using time of said luminous display unit such that a difference in light emitting luminance caused between both the light emitting portions lies within 30% of a high light emitting luminance among the light emitting luminances at said using time. For example, each of luminous display units
100
,
110
has plural segments
21
a
to
21
g
(light emitting portions) by using an O

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