JP2002351378A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device capable of correcting more simply luminance unevenness in current drive type light emitting elements. SOLUTION: In this display device, even when display areas of respective pixels are different respectively, driving currents having values corresponding to the respective areas can be supplied to the pixels by constituting a driving driver IC 14 so as to be provided with current sources 15 of a number equal to or larger than the number of pixels for segment display constituting a display panel 1 and by connecting current sources 15 of one of more to the respective pixels so that amounts of current corresponding to sizes of respective light emitting areas are supplied to the respective pixels.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device having a plurality of light emitting elements which emit light at a luminance corresponding to a driving current amount.

[0002]

2. Description of the Related Art For example, an organic EL (Electro Luminecenc)
e) The element is a light emitting element that emits light at a luminance according to the amount of drive current. In a display device including a plurality of display portions (segments) having different display areas using such a light emitting element, there is a possibility that so-called luminance unevenness in which light emission luminance differs between the display portions.

A conventional technique for solving such a problem is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-305146.
In this conventional technique, control data corresponding to a drive current of each light emitting element is stored in a memory as a reference table. Further, a drive circuit for supplying a drive current to the light emitting element includes a plurality of current sources having different output current values, and the output current value is made variable by selectively switching any one of the current sources. Is configured. Then, when a drive command is given from the outside, the controller reads control data corresponding to the light-emitting element to be caused to emit light from the reference table, and switches the current source of the drive circuit according to the control data, so that the light emission luminance of each element is adjusted. Control to an appropriate level.

[0004]

However, such a control system is complicated, and high-speed processing is required to perform control within each cycle of display switching, and the configuration of the drive circuit is also complicated. I have to be. Further, if the display patterns are different, it is necessary to configure a drive circuit in accordance with the different display patterns, which leads to an increase in costs required for development and manufacturing, and a problem that the development period is lengthened.

In the above publication, the current value output from the current source of the drive circuit is fixed, and the current output time (pulse width of the drive signal) is changed according to the display area of each light emitting element by PWM.
A controlling technique is also disclosed. For example, assuming that the display device is applied to an instrument panel of a vehicle, the panel display at night needs to be much dimmer (for example, 1/10) than at daytime. Then, as shown in FIG. 7, when the light emitting element is dimmed by the PWM control, the pulse width of the drive signal is set to be short.

That is, when the luminance unevenness is corrected by using the PWM control, the daytime light emission period shown in FIG. 7A may be shortened as shown by a broken line depending on the light emitting element. In that case, the pulse width for performing the dimming shown in FIG. 7B must be set even shorter. Therefore, it is necessary to increase the variable range of the PWM signal pulse width, and a high-precision timer circuit is required. In addition, if a plurality of gradation displays are to be performed, the pulse width must be further reduced, which makes control difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a display device capable of easily correcting uneven brightness of a current-driven light-emitting element.

[0008]

According to a first aspect of the present invention, there is provided a display device comprising a plurality of driving means equal to or more than the number of light emitting elements, and each light emitting element having a current amount corresponding to the size of the light emitting area. Is connected to one or more driving means. For example, assuming that the driving current value of the driving means for emitting light at a predetermined luminance corresponding to the unit light emitting area S of the light emitting element is I, two driving means are connected to the light emitting element having the light emitting area 2S. The driving current value is set to 2I, and the light emitting area 5S
The five light emitting elements are connected to five light emitting elements so that the driving current value becomes 5I.

With this configuration, even if the light emitting areas of the light emitting elements are different from each other, it is possible to easily supply a drive current having a value corresponding to each light emitting area, and it is extremely possible to correct uneven brightness. It can be done easily. Further, even in the case of performing gradation display after performing a predetermined amount of dimming adjustment according to the surrounding environment or the like, it is possible to easily perform dimming control. Since it is not necessary to change the configuration of the driving means in accordance with different display patterns, the development period can be shortened without increasing the cost required for development and manufacturing.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the output current amount of the driving means is made variable so that the number of wires for connecting the light emitting element and the driving means is reduced. Can be reduced.

According to the third aspect of the present invention, in addition to the configuration of the first aspect, the control means performs PWM control of the current output time by the driving means, so that the variable range of the PWM signal pulse width is set to be large. If not, for example, dimming control in the case of performing dimming display or gradation display at night can be easily performed.

According to the display device of the present invention, since a dot matrix display unit and one or more segment display units are provided, for example, one driving means is connected to each of the light emitting elements constituting the former. By performing PWM control by the control means, gray scale display becomes possible. In addition, one or more driving means corresponding to the light emitting area is connected to the light emitting element constituting the latter. In that case, if the drive current value of the drive means is variably set, the number of wires connected to the segment display unit can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, a first embodiment in which the display device of the present invention is applied to an instrument panel of a vehicle will be described with reference to FIG. FIG. 1 shows a display panel 1 which is a part of an instrument panel located in front of a driver's seat of a vehicle and mainly performs various displays related to air conditioning. The display panel 1 includes a plurality of segment display pixels (light emitting elements) each formed using an organic EL element.

For example, the temperature display section 2 is composed of 7-segment display pixels 3 for displaying the vehicle interior temperature with numerals, and dot-shaped pixels 4 for indicating a decimal point. The airflow direction display section 5 has pixels 6 for indicating airflow (defroster) to the windshield, and symbols of the occupant sitting in the driver's seat or the passenger seat (head and body).
, And arrow-shaped pixels 9 and 10 indicating airflow in the direction of the occupant's trunk and feet. Further, the air volume display unit 11 includes pixels 12 for displaying a blower fan symbol and pixels 13 for displaying the air volume in a bar graph. Display panel 1
Has a display section for the outside air temperature and a display section for the set temperature of the air conditioner.

A driving current for lighting display is supplied from the driving driver IC 14 to each pixel of the display panel 1. The driving driver IC 14 includes a plurality of current sources (driving means) 15 having the same driving current value (for example, the current value I), and each pixel of the display panel 1 has a display area (light emission). Output terminals of one or more current sources 15 are connected by wiring 16 so that a drive current corresponding to the area is supplied.

For example, only one current source 15 is connected to the dot-shaped pixel 4 in the temperature display section 2. On the other hand, two wirings 16 and two current sources 15 are connected to each segment of the 7-segment display pixel 3 having a display area approximately twice as large as the pixel 4. In FIG. 1, the current sources 15 in one segment are illustrated, and the illustration of the current sources in the remaining six segments is omitted. Thirty current sources 15 are connected to the pixel 8 for representing a symbol of an occupant whose display area is approximately 30 times that of the pixel 4. In FIG. 1, four wirings 16 and two current sources 1 are shown for convenience of space.
Only five are shown.

Further, 16 wirings 16 and 16 current sources are connected to the pixels 12 of the blow direction display section 11 having a display area approximately 16 times that of the pixels 4. In FIG. 1, only three wires 16 are shown due to space limitations, and illustration of a current source is omitted. Furthermore, 5 of the blowing direction display section 11
The pixel 13a, which represents the frame portion of the entirety of the pixels 13, has a display area approximately 20 times that of the pixel 4, and the pixel 13a is connected to 20 wirings 16 and 20 current sources. In FIG. 1, only three wires 16 are shown due to space limitations, and illustration of a current source is omitted. Each of the above wirings 16
Are connected to terminal portions (not shown) drawn from each pixel on the outer peripheral portion of the display panel 1.

The drive driver IC 14 is connected to each of the current sources 15 and a drive power supply (Vcc The respective pixels are turned on or off by opening and closing the switches 18 disposed between the pixel 17). Switch 1
Needless to say, one pixel 8 is arranged corresponding to the area ratio of each pixel. Also, as described above, the wiring 16
Represents only some of the pixels for convenience of illustration.
The above constitutes the display device 19.

That is, since the light emission luminance of the EL element is substantially proportional to the amount of drive current supplied per unit display area, by supplying a drive current according to the display area of each pixel, the light emission luminance of each pixel becomes It has been adjusted to be approximately equal.

As described above, according to the present embodiment, the drive driver IC 14 is provided with the current sources 15 of the number equal to or more than the number of the pixels for segment display constituting the display panel 1, and each pixel emits a respective light. One or more current sources 15 are connected so that a current amount corresponding to the size of the area is supplied.

Therefore, even when the display areas of the respective pixels are different from each other, it is possible to easily supply a drive current having a value corresponding to each area, and it is possible to extremely easily correct the luminance unevenness in the display panel 1. be able to. Since the configuration of the drive driver IC 14 does not need to be changed corresponding to the case where the display pattern of the display panel is different, the development period can be shortened without increasing the cost required for development and manufacturing.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. explain. In the first embodiment, one drive driver IC 14 is arranged for the display panel 1, but in the second embodiment,
A plurality of (for example, five) driver ICs 20 (A to E) are arranged on the display panel 1.

That is, a driving current is supplied from the driving driver IC 20A to the pixels 3 and 4 of the temperature display section 2, and the driving driver IC 20B is supplied to the pixels 6 to 10 of the blowing direction display section 5.
More drive current is supplied. In addition, the driving driver IC 20C
The driving current is supplied from the driving driver I to the pixel 14.
A drive current is supplied from C20E.
These drive driver ICs 20A to 20E are:
Both are configured with the same standard. The above is the display device 2
1. According to the second embodiment configured as described above, the same effects as in the first embodiment can be obtained. Further, in the second embodiment, the number of connected output terminals of the drive driver IC 20 is merely adjusted in accordance with the display area of each pixel, and the versatile drive driver ICs 20A to 20E can be used.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. explain. In the third embodiment, a display device 23 is configured by adding a PWM control unit (control means) 22 to the configuration of the first embodiment. In other words, the PWM control unit 22 is provided with a drive control signal that is directly provided to the drive driver IC 14 in the first embodiment.
A drive control signal PWM-controlled by the PWM control unit 22 is output.

Here, the ECU of the vehicle (not shown) performs the gradation for displaying the light emission luminance of the display panel 1 in gradation based on the ON / OFF state of the light switch, a sensor for detecting the brightness of the external environment, and the like. The display control signal is output to the PWM control unit 22. Then, the PWM control unit 22 performs PWM control on the drive control signal according to the gradation display control signal.

That is, by employing the configuration of the first embodiment, it is possible to supply a drive current to each pixel so that the light emission luminance is substantially uniform. By adding the PWM control unit 22, the light emission period (drive current supply period, PWM pulse width) of each pixel in the daytime as shown in FIG. 7A can be set uniformly.

Therefore, according to the third embodiment configured as described above, it is not necessary to adjust the pulse width of the drive signal in order to correct the luminance unevenness between the respective pixels.
As shown in (b), when the display units are dimmed at night or when gradation display is performed between the display units under other conditions, the adjustment range (variable range) by the PWM control is used. ) Can be secured with a margin.

(Fourth Embodiment) FIGS. 4 and 5 show a fourth embodiment of the present invention. Display device 24 of fourth embodiment
Is composed of a display panel 25 and a drive driver IC 26. The plurality of drive means 27 constituting the drive driver IC 26 are configured such that the setting of the output current value is variable. The display panel 25 includes three pixels (light emitting elements) 28, 29, and 30 having a display area ratio of 1: 3: 9, respectively.

As shown in FIG. 5, each drive means 27 is configured to use a voltage obtained by amplifying a common reference voltage VREF by an amplifier 31 as a drive power supply. Amplifier 31
Is a resistance changeover switch 3 for determining the amplification factor.
2 can be set. The changeover switch 32 is switched by, for example, a dip switch. If a setting register is provided in the drive driver IC 26 and a display control CPU or the like is provided, the CPU or the like writes the data into the register. Set by doing. Then, the output voltage of the amplifier 31 becomes the drive power supply VCC and is supplied to the current source 15 via the switch 18.

In this case, assuming that the driving current values of the driving means 27 of the driving driver IC 26 are all the same, in order to make the light emission luminances of the pixels 28 to 30 substantially the same, the pixels 28, 29, 30 The number of the wirings 16 connecting the driver driver IC and the driver driver IC is “1,
Must be 3,9 ".

However, the number of wirings can be reduced by variably setting the output current value of the driving means 27. For example, when the drive current value for the pixel 29 is set to be the reference ratio “1”, the drive current value ratio for the pixel 28 is set to “１ ／”, and the drive current value ratio for the pixel 30 is “3”. Set to "". With this setting,
The number of the wirings 16 for the pixels 28 and 29 is set to “1”, respectively.
The number of the wirings 16 for the pixel 30 can be set to “3”.

According to the fourth embodiment configured as described above, the output current amount of the driving means 27 is variably configured.
The number of wirings 16 for connecting each of the pixels 28 to 30 constituting the display panel 25 and the driving unit 27 can be reduced.

(Fifth Embodiment) FIG. 6 shows a fifth embodiment of the present invention. The display panel 33 of the fifth embodiment has a different display area from the dot matrix display section 35 in which minute dot-shaped pixels (light emitting elements) 34 are arranged in a matrix, similarly to the display panel 1 of the first embodiment. Segment display section 37 composed of a set of a plurality of pixels (light emitting elements) 36
And

The display of the display panel 33 is controlled using the drive driver IC 26 of the third embodiment and the display control section 38. In this case, for the segment display section 37 which merely switches on and off, the output current of the driving means 27 is adjusted and the wiring 16 is connected according to the display area of each pixel 36 as in the third embodiment.

On the other hand, for the dot matrix display section 35, each pixel 34 and the driving means 27 are connected one to one.
When the display control unit 38 causes the dot matrix display unit 35 to perform gradation display according to a display signal supplied from the outside, the register is dynamically set in the register of the corresponding driving unit 27 as described in the fourth embodiment. To adjust the output current value.

According to the fifth embodiment constructed as described above, the dot matrix display section 35 and the segment display section 3
7, it is possible to efficiently perform the gradation display control in the former and the reduction of the number of wirings in the latter.

The present invention is not limited to the embodiment described above and shown in the drawings, and the following modifications or extensions are possible. For example, in the pixel 13a of FIG. 1, the output units from the 20 current sources may be connected to one terminal unit, and the one terminal unit and the pixel 13a may be connected by a single wiring. The light emitting element is not limited to the organic EL element, and may be any element that emits light at a luminance according to the amount of drive current. The present invention is not limited to the application to the instrument panel of the vehicle, but may be applied to any display device including the above light emitting element.

[Brief description of the drawings]

FIG. 1 is a first embodiment in which a display device of the present invention is applied to an instrument panel of a vehicle, and shows a display panel and a driver IC.

FIG. 2 is a view corresponding to FIG. 1, showing a second embodiment of the present invention;

FIG. 3 is a view corresponding to FIG. 1, showing a third embodiment of the present invention;

FIG. 4 is a view corresponding to FIG. 1, showing a fourth embodiment of the present invention;

FIG. 5 is a diagram showing a detailed electric configuration of a drive driver IC.

FIG. 6 is a view corresponding to FIG. 1 showing a fifth embodiment of the present invention.

FIGS. 7A and 7B are timing charts of driving signals when dimming control of a display panel is performed by PWM control in the related art, where FIG. 7A illustrates a case of daytime and FIG. 7B illustrates a case of nighttime.

[Explanation of symbols]

1 is a display panel, 3, 4, 6 to 10, 12 and 13 are pixels (light emitting elements), 14 is a drive driver IC, 15 is a current source (drive means), 16 is a wiring, 19 is a display device, and 20 is drive A driver IC, 21 a display device, 22 a PWM control unit (control means), 24 a display device, 25 a display panel,
26 is a drive driver IC, 27 is drive means, 28 to 30
Denotes a pixel (light emitting element), 33 denotes a display panel, 34 denotes a pixel (light emitting element), 35 denotes a dot matrix display section, 36 denotes a pixel (light emitting element), 37 denotes a segment display section, and 38 denotes a display control section.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H05B 33/14 H05B 33/14 A F-term (Reference) 3K007 AB02 AB17 BA06 DA01 DB03 EB00 GA02 GA04 5C080 AA06 BB01 BB05 DD03 EE28 JJ02 JJ03 JJ04

Claims (4)

[Claims] 1. A display device comprising a plurality of light-emitting elements that emit light at a luminance corresponding to the amount of drive current, the drive device supplying a drive current to the light-emitting elements, and comprising a driving means having a number of light-emitting elements or more. A display device comprising one or more driving means connected so that a current amount corresponding to the size of each light emitting area is supplied to each light emitting element. 2. The display device according to claim 1, wherein the driving means is configured to change an output current amount. 3. The display device according to claim 2, wherein the driving unit has a variable current output time, and further includes a control unit that performs PWM control on the current output time of the driving unit. 4. A dot matrix display section in which a plurality of light emitting elements having the same light emitting area are arranged, and a light emitting element having different light emitting areas.
4. The display device according to claim 3, comprising at least one segment display unit.