JP2001202049A - Current drive type light-emitting display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a difference in light emission luminance according to the display area of a light emission place of a current drive type light self- emitting element even if light is emitted at the light emission place with the same value. SOLUTION: The current drive type light-emitting display device 100 has segments (light emission places) 21a to 21g, a unit symbol part (light emission place) 27, an odd symbol part (light emission place) 28a, and a trip symbol part (light emission place) 28b and also have those light emission places connected to constant-current circuits (current drive sources) 610a to 610g and 671 to 676. The number of the current drive sources which are connected are varied according to the display area of the light emission places so that the light emission places. are nearly equal in luminance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current-driven light-emitting display device, for example, an organic electroluminescence device (OL).
ED), fluorescent display (FLT), light emitting diode (LE)
The present invention relates to a current-driven light-emitting display device using a current-driven self-luminous element such as D).

[0002]

2. Description of the Related Art As shown in FIG. 3, an anode 2 made of a transparent conductive material such as indium oxide (ITO) is provided on a transparent substrate 1, and an organic layer comprising at least one layer (at least a single layer of an organic light emitting layer). Structure or a multilayer structure in which a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, and the like are laminated from the anode side according to the organic light emitting layer) 3 and a metal conductive material such as aluminum (Al). Cathode 4 made of material
OLED 5 having at least
No. 2307, it is possible to emit light in a desired pattern depending on the shape of the anode 2 and the cathode 4, and it is possible to display with a constant current drive from a DC power supply Vcc of several volts to several tens of volts. is there.

A light-emitting display device 1 using such an OLED 5
In the case of using the O.00 as a digital odometer of a vehicle display device, as shown in FIG. 4, the anode 2 shown in FIG.
Are divided into six groups 21 to 26, and the group 21 is divided and formed into seven segments 21a to 21g which are light emitting portions arranged in the shape of the sun and form Arabic numerals "0" to "9". Is displayed in a pseudo manner, and the other groups 22 to
The same applies to 26, which has a configuration in which a six-digit number can be displayed by arranging a plurality of groups 21 to 26 in the horizontal direction. The group 21 is located at the least significant digit, and the group 26 is located at the most significant digit.

Also, 27 is a part of the anode 2 and a unit symbol part for displaying the unit of travel distance "Km". 28a is also a part of the anode 2 and the digital odometer is a cumulative odometer. Od symbol part for displaying a symbol "ODO" indicating that the mode is in the mode, 28b is also a part of the anode 2, and displays a symbol "TRIP" for indicating that the digital odometer is in the section odometer mode. The odd sign portion 28a and the trip sign portion 28a are selectively switched by a switch (not shown) to display only one of them, and the display in the groups 21 to 26 is also switched at the same time. These unit symbol part 27 and odd symbol part 28
a, the trip symbol portion 28b is also a light emitting portion.

[0005]

When light emission is performed at the same current value at the light-emitting portion of the current-driven self-luminous element, the light-emission luminance differs depending on the display area of the light-emitting portion, and the display area is reduced. The larger the value, the lower the light emission luminance.

Therefore, in the light-emitting display device 100 shown in the prior art, the units “K” and “m” of the unit symbol portion 27 for displaying the unit of kilometer as “Km” are obtained by using a part of the anode 2. It is formed integrally electrically, and the other odd symbol part 2
8a and the trip sign part 28b are the same. For this reason,
Unit symbol 27, odd symbol 28a, trip symbol 2
8b and individual segments 21a-21g of group 21
(The same applies to groups 22 to 26) means that the display area of the former is much larger than the display area of the latter, which causes a remarkable difference in the light emission luminance, thereby deteriorating the display quality. .

In order to solve this problem, it is conceivable to provide a difference in the current value between the former and the latter so as to make the light emission luminance closer. For this purpose, a plurality of drive ICs are used or the drive circuit of the drive circuit is used. It is conceivable to prepare a drive circuit in which constants are separately set.

However, the use of a plurality of drive ICs increases the cost, and setting the constants of the drive circuits separately requires additional components such as insertion of adjustment resistors, resulting in an increase in the size of the drive circuit. Become.

[0009]

According to a first aspect of the present invention, there is provided a light-emitting display device having a plurality of light-emitting portions, wherein the light-emitting portions have a constant current. A current-driven light-emitting display device connected to the light-emitting device, wherein the number of the current-driven light sources to be connected is changed according to the display area of the light-emitting portion so that the light emission luminance at the light-emitting portion is substantially uniform. .

According to a second aspect of the present invention, there is provided a current-driven type light-emitting display device having a plurality of light-emitting portions, wherein the light-emitting portions are connected to a constant current drive source.
The number of the current driving sources to be connected is changed according to the display area of the light emitting point so that the difference in light emission luminance at the light emitting point is not visually recognized.

According to a third aspect of the present invention, there is provided a current driving type light emitting display device having a plurality of light emitting points and connecting the light emitting points to a constant current driving source.
The difference between the light emission luminance of the light emitting portion having the highest light emission luminance and the light emission luminance of the light emitting portion having the lowest light emission luminance is the former 30.
The number of the current driving sources to be connected is changed according to the display area of the light emitting portion so as to fall within the range of%.

Further, as described in claim 4, a light emitting portion constituted by a segment or a dot, another light emitting portion having a larger display area than these light emitting portions, and a constant current flowing to the light emitting portion. A driving source, and increasing the number of the current driving sources connected to the other light emitting points compared to the light emitting points so that a difference in light emission luminance at the light emitting points is not visually recognized. Things.

Further, as described in claim 5, a light emitting portion constituted by a segment or a dot, another light emitting portion having a larger display area than these light emitting portions, and a constant current flowing to the light emitting portion. A driving source, and increasing the number of the current driving sources connected to the other light emitting points compared to the light emitting points so that a difference in light emission luminance at the light emitting points is not visually recognized. Things.

Further, as described in claim 6, a light-emitting portion composed of segments or dots, another light-emitting portion having a larger display area than these light-emitting portions, and a constant current flowing to those light-emitting portions. A driving source, and a difference between the light emission luminance of the light emission part having the highest light emission luminance at the light emission part and the light emission luminance of the light emission part having the lowest light emission luminance at the other light emission part is within 30% of the former. The number of the current driving sources connected to the other light emitting points is increased as compared with the light emitting points so as to be accommodated.

In particular, as described in claim 7, claim 1
In the present invention, the plurality of current drive sources are constituted by one drive IC.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the embodiments shown in the accompanying drawings, in which the same or corresponding parts as those of the above-mentioned prior art are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 relates to a first embodiment of the present invention, and 100 denotes a light-emitting display device according to the present invention, wherein
This is a digital odometer as a vehicle display device using the LED 5 (see FIG. 3), and the specific configuration is the same as that of the above-described conventional technology.

The anode 2 (see FIG. 3) has six groups 2
1 to 26, the group 21 is divided into seven segments 21a to 21g, and the other groups 22 to 26 are the same.
By arranging a plurality of 26 in the horizontal direction, a six-digit number can be displayed.

In the vicinity of the groups 21 to 26, a unit symbol part 27 which is a part of the anode 2 and indicates a unit of the traveling distance “Km”, and a part of the anode 2 which is a digital traveling distance Od symbol portion 28a displaying symbol "ODO" indicating that the meter is in the mode of the cumulative odometer, anode 2
And a trip symbol portion 28b for displaying a symbol "TRIP" indicating that the digital odometer is in the section odometer mode is formed, and these unit symbol portion 27 and odd symbol portion 28a are formed. , Trip symbol part 28b is also a light emitting part.

Reference numeral 200 denotes a sensor that outputs a pulse signal in accordance with the number of rotations of the wheels, reference numeral 300 denotes a counter that counts the output (number of pulses) from the sensor 200, and reference numeral 400 denotes a travel distance calculated from the count number of the counter 300.
A calculation control unit including a microcomputer or the like that outputs a control signal so as to cause the digital odometer 100 to perform a display based on the calculation; 500, a power supply circuit including a vehicle-mounted battery;
610 is a constant current circuit unit for obtaining a constant current from the power supply circuit 500, and 710 is a segment 21a to 21g for displaying a predetermined number based on an instruction from the arithmetic and control unit 400.
The constant current circuits 610a to 610g of the constant current circuit section 610
Switches 710a to 710a to supply or cut off current from
A switching unit having 10 g.

Although FIG. 1 shows only the group 21 for displaying the least significant digit and omits other groups 22 to 26, the other groups 22 to 26 also include a constant current circuit section 610 and a switching section 710. (Constant current circuit units 620 to 660, switching units 720 to 76
0, both not shown) are connected, and it goes without saying that a predetermined number is displayed based on an instruction from the arithmetic control unit 400. In the following description, group 2
1 will be described, but the same applies to the corresponding portions of the other groups 22 to 26 unless otherwise specified.

The constant current circuit 6 of the constant current circuit section 670
71 to 673 are a unit symbol part 27, an odd symbol part 28a,
These are connected to the trip symbol portions 28b, respectively, and will be described later in detail.

Further, switches 780a and 780b for switching between the odd symbol portion 28a and the trip symbol portion 28b.
Is located between the constant current circuit section 670 and the odd symbol section 28a and the trip symbol section 28b, and these are switched by the arithmetic and control section 400.

When the constant current circuit sections 610 to 670 are constituted by one drive IC, constant current circuits 610a to 610g,...
In order to connect g and 671 to 673, a drive IC having a total of 45 outputs is required. In this embodiment, a drive IC having more outputs than the number of light emitting points is used.

Then, constant current circuits 674 to 676 connected to extra outputs are connected in parallel with the constant current circuits 671 to 673 to the unit symbol portion 27, the odd symbol portion 28a, and the trip symbol portion 28b, respectively. That is, the unit symbol part 27
, The constant current circuits 672 and 675 are supplied to the odd symbol part 28a, and the constant current circuits 673 and 676 are supplied to the trip symbol part 28b by a constant current circuit 673 and 676. Configuration.

According to this configuration, the unit symbol portion 27, the odd symbol portion 28a, the trip symbol portion 28b, and the individual segments 21a to 21g of the group 21 (similarly for the groups 22 to 26) have the former display area of the latter. It becomes extremely large compared to the area, and usually causes a remarkable difference in the light emission luminance between them. By increasing the current value of the former compared to the latter, the light emission luminance can be increased, and the light emission of both lights can be increased. The difference in luminance can be suppressed.

In order to adjust the difference between the two light emission luminances so that the difference is not visually recognized, the unit symbol part 27, the odd symbol part 28a, and the trip symbol part 28b are configured to connect three or more outputs. It is also possible.

FIG. 2 shows a second embodiment of the present invention, in which the same or corresponding parts as those in the above-described conventional technique or the first embodiment are denoted by the same reference numerals and detailed description thereof is given. Omit description.

The anode 2 and the cathode 4 are formed in a strip shape, and a dot matrix display area A in which a dot portion where the two electrodes 2 and 4 intersect is a light emitting portion, a unit symbol portion 27, an odd symbol portion 28a, and a trip symbol This is a light emitting display device 101 in which an anode 2 is formed in a shape having a special design, such as a portion 28 (both shown in FIG. 1), and a character display area B having the anode 2 as a light emitting portion coexists.

In the dot matrix display area A, a constant current circuit 600A1 to 60 as a current driving source similar to that of the first embodiment is connected to the anode 2 via a column driver 800.
Constant current driving section 600A having 0An (n is an arbitrary number)
The row driver 900 is connected to the cathode 4, and these drivers 800 and 900 are controlled by the arithmetic and control unit 400.

On the other hand, in the character display area B, the anode 2 is connected to the anode 2 via the switching unit 700 similar to the first embodiment or directly to the constant current driving unit similar to the first embodiment. The constant current driver 600B has a plurality of constant current circuits 600B1 to 600Bn (n is an arbitrary number) as current driving sources, and the constant current driver 600B has more constant current circuits than the display positions in the dot matrix display area A. The current is supplied.

With this configuration, the light-emitting portion of the character display area B and the light-emitting portion of the dot matrix display region A have an extremely large display area in comparison with the latter display area. However, by increasing the former current value compared to the latter, the light emission luminance can be increased, and the difference between the two light emission luminances can be suppressed.

The number of outputs of the constant current driver 600B connected to the character display area B is appropriately selected in order to adjust the difference between the two light emission luminances so as not to be visually recognized. The same is true.

In each of the above embodiments, the light-emitting display device using the OLED has been described. However, the present invention can be applied to any current-driven self-luminous element, for example, a fluorescent display tube (FLT). ) And light emitting diodes (L
ED).

However, the organic electroluminescent element has a remarkable effect on the light emission luminance depending on the light emitting area, and the present invention is suitable for a light emitting display device using such an organic electroluminescent element as a self light emitting element.

A constant current circuit 610a as a current drive source
610g, ..., 660a-660g, 671-6
76, 600A1 to 600An, 600B1 to 600B
It is desirable that the respective output current values of n be the same (the same current value), but the actual drive IC may have a slight (± several%) variation. There is no problem in realizing each embodiment. That is, even if a difference occurs in the output current of the driving IC within a width of about several percent, the difference in the light emission luminance due to the difference is small and cannot be visually recognized.

In the present invention, it is desirable to change the number of the current driving sources connected according to the display area of the light emitting point so that the light emission luminance at the light emitting point is substantially uniform. It is sufficient that the difference between the light emission luminances is not visually recognized. Specifically, according to an experiment conducted by the present inventors, the light emission luminance at the light emission point having the highest light emission luminance and the light emission luminance at the lowest light emission luminance are obtained. It has been confirmed that this can be achieved by changing the number of the current driving sources connected according to the display area of the light emitting portion so that the difference from the light emitting luminance of the light emitting portion is within 30% of the former.

[0038]

According to the present invention, even when light emission is performed at the same current value at the light-emitting portion of the current-driven self-luminous element, a difference in light-emitting luminance occurs depending on the display area of the light-emitting portion. And display quality can be kept high.

[Brief description of the drawings]

FIG. 1 is a circuit diagram according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a structure of an organic electroluminescence element.

FIG. 4 is a front view of a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 21-26 Group 21a-21g Segment (light emitting part) 27 Unit symbol part (light emitting part) 28a Od symbol part (light emitting part) 28b Trip sign part (light emitting part) 3 Organic layer 4 Cathode 5 Organic electroluminescence Element (self-luminous element) 100, 101 Light-emitting display device 610-670 Constant current drive section 600A, 600B Constant current drive section 610a-610g, ..., 660a-660g, 6
71 to 676 Constant current circuit (current drive source) 600A1 to 600An, 600B1 to 600Bn Constant current circuit (current drive source)

Claims (7)

[Claims] 1. A current-driven light-emitting display device having a plurality of light-emitting portions and connected to a constant-current current drive source, wherein the light-emitting portions have substantially uniform light emission luminance. Wherein the number of said current driving sources to be connected is changed according to the display area of said light emitting portion. 2. A current-driven light-emitting display device having a plurality of light-emitting portions and connecting the light-emitting portions to a constant-current current drive source, wherein a difference in light-emitting luminance at the light-emitting portions is visually determined. A current-driven light-emitting display device, wherein the number of the current-driven sources connected is changed according to the display area of the light-emitting portion so as not to be recognized. 3. A current-driven light-emitting display device having a plurality of light-emitting portions and connecting the light-emitting portions to a constant-current current drive source, wherein the light-emitting portion having the highest light-emitting luminance has the highest light-emitting luminance. The current drive type wherein the number of the current drive sources connected according to the display area of the light emitting portion is changed so that the difference between the light emitting brightness of the light emitting portion and the light emitting brightness of the low light emitting portion is within 30% of the former. Light-emitting display device. 4. A light-emitting device comprising: a light-emitting portion composed of segments or dots; another light-emitting portion having a larger display area than these light-emitting portions; and a current drive source for supplying a constant current to the light-emitting portion. A current driving type light emitting device, wherein the number of the current driving sources connected to the other light emitting points is increased as compared with the light emitting points so that a difference in light emission luminance at the points is not visually recognized. Display device. 5. A light-emitting device comprising: a light-emitting portion constituted by segments or dots; another light-emitting portion having a larger display area than these light-emitting portions; and a current drive source for supplying a constant current to the light-emitting portion. A current driving type light emitting device, wherein the number of the current driving sources connected to the other light emitting points is increased as compared with the light emitting points so that a difference in light emission luminance at the points is not visually recognized. Display device. 6. A light-emitting portion comprising: a light-emitting portion formed by a segment or a dot; another light-emitting portion having a larger display area than these light-emitting portions; and a current drive source for supplying a constant current to the light-emitting portion. The difference between the light emission luminance of the light emission point having the highest light emission luminance at the light emission point and the light emission luminance of the light emission point having the lowest light emission luminance at the other light emission point is within 30% of the former. A current-driven light-emitting display device, wherein the number of the current-driven sources connected to the other light-emitting portions is increased. 7. The current-driven light-emitting display device according to claim 1, wherein a plurality of current-drive sources are constituted by one drive IC. apparatus.