JP2005062720A - Light emitting display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct the luminance unevenness between light emitting display devices during use without adversely affecting images with the light emitting display device having a display element 1 equipped with a number of light emitting elements emitting the display light on the basis of a data signal and test light emitting elements 2 for inspecting the characteristics of the display light emitting elements. <P>SOLUTION: The test light 11 is emitted to a direction parting from an opposite direction with respect to the display light 7 emitted from the display light emitting elements of the display part 1 from the test light emitting elements of the test light light emitting section 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light-emitting display device for displaying information in a light-emitting manner, and particularly to a light-emitting display device using a light-emitting element such as an organic electroluminescence element.

  Development of a light-emitting display device in which light-emitting elements are arranged in a matrix to form a display surface has been widely promoted. As a light-emitting element used in such a light-emitting display device, for example, there is an electroluminescence element (hereinafter referred to as an organic EL element) using an organic light-emitting material as a light-emitting layer. As a light-emitting display device using organic EL elements, a simple matrix light-emitting display device in which organic EL elements are simply arranged in a matrix form, and an active element in which a driving element made of a transistor is added to each of the organic EL elements arranged in a matrix form. There is a matrix type light emitting display device.

  In driving a simple matrix light emitting display device, the light emission luminance is controlled by the magnitude of the drive current or drive voltage for driving the organic EL element. In driving an active matrix light-emitting display device, light emission luminance is controlled by amplitude modulation or time modulation (so-called subfield method) while controlling on / off of light emission by switching drive elements. The subfield method is a method of adjusting the instantaneous luminance of the organic EL element by controlling the drive current (or drive voltage) while keeping the light emission time constant.

  However, in any driving, the characteristics such as the light emission efficiency of the organic EL element tend to vary from one light emitting display device to another, so that there is a problem that the light emission luminance tends to vary among the light emitting display devices. In addition, as a method for realizing full color display, there are a method using a white organic EL element and a color filter and a method of separately applying organic light emitting materials of three colors of red, blue and green. In the latter case, the organic EL for each color is used. Since the characteristics of the elements are likely to vary from one light emitting display device to another, there is a problem that the white balance differs from one light emitting display device to another. Furthermore, when used for a long time, there is a problem in that the characteristics of the organic EL element change and image quality deteriorates.

  Since these causes are caused by variations in the characteristics of the light emitting elements, the characteristics of the display light emitting elements other than the display unit including a number of display light emitting elements that emit display light based on video signals are It is known to provide a test light-emitting element for inspection and control the driving of the display light-emitting element from the state of the test light-emitting element to suppress the variation. Specifically, it is known that the drive voltage, which is the voltage across the test light emitting element provided adjacent to the display unit, is measured as a detection signal, and the drive power of the display light emitting element is controlled according to this detection signal. (For example, refer to Patent Document 1).

  In addition, as a method for making the characteristics of the light emitting device uniform during manufacturing, a test light emitting device is formed together with the light emitting device as a product, and the luminance change of the test light emitting device is measured in the aging process to measure the luminance of the test light emitting device. Is known to perform an aging process so as to decrease to a predetermined target luminance (see, for example, Patent Document 2).

JP 2001-236040 A JP 2002-198172 A

  However, the test light emitting element of Patent Document 1 is provided adjacent to the display unit, and the display light generated from the light emitting element of the display unit is not particularly taken into consideration for the processing of the test light generated from the test light emitting element. This test light overlaps, and there is a problem of adverse effects such as partial color change and luminance unevenness.

  Further, the above-mentioned Patent Document 2 has a problem that it can only be applied at the time of manufacturing a light emitting element and cannot be applied to a change in characteristics due to the passage of usage time.

  The present invention has been made in view of the above-described conventional problems, and includes a display unit including a large number of display light emitting elements that emit display light based on data signals, and a characteristic for inspecting the characteristics of the display light emitting elements. An object of the present invention is to make it possible to correct luminance unevenness between light emitting display devices in use without adversely affecting an image in a light emitting display device having a test light emitting unit including a test light emitting element.

  For the above purpose, the present invention provides a display unit including a number of display light emitting elements that emit display light based on a data signal, and a test light emission including a test light emitting element for inspecting characteristics of the light emitting elements. The test light emitting unit emits test light from the test light emitting element in a second light emitting direction that is different from the first light emitting direction that is the light emitting direction of the display light. A light-emitting display device characterized by the above is provided.

In addition, the present invention includes a correction unit that changes the driving power of the display light emitting element based on light reception data obtained by receiving the test light.
The second light emitting direction is a direction away from the first light emitting direction in a lateral direction or a direction away from the opposite direction;
The display unit is provided on one side of the glass substrate, and the test light emitting unit is provided on the other side of the glass substrate;
Is included as a preferred embodiment thereof.

  According to the present invention, the test light emission unit can be operated without affecting the display of the display screen of the display unit, and a stable and good image can be realized not only at the time of manufacture but also at the time of use after manufacture. It can be inspected and controlled.

  A first example of the light emitting display device according to the present invention will be described with reference to FIGS.

  1 is a schematic cross-sectional view of a light-emitting display device according to a first example of the present invention, FIG. 2 is a rear view of the light-emitting display device shown in FIG. 1, and FIG. 3 is a view of the light-emitting display device shown in FIGS. 4 is a circuit configuration diagram corresponding to one sub-pixel, and FIG. 4 is an explanatory diagram of a method of monitoring and correcting the test light of the test light emitting unit shown in FIGS.

  The light emitting display device of this example uses an organic EL element as both the display light emitting element and the test light emitting element, and is roughly composed of a display unit 1 and a test light emitting unit 2.

  The display unit 1 has a driving circuit (not shown) on the surface side of a transparent plate-like glass substrate 3 (a circuit configuration of each subpixel will be described later) and a metal electrode 4 that is a metal electrode as a cathode. A light emitting layer 5 made of an organic light emitting material is placed thereon, and an ITO electrode 6 is sequentially stacked thereon as an anode. From the display unit 1, display light 7 indicated by an arrow in FIG. 1 is extracted to the front side.

  The test light emitting unit 2 has a laminated structure similar to that of the display unit 1 and has a structure in which a light emitting layer 9 made of an organic light emitting material and an ITO electrode 10 are sequentially laminated on the back side of the glass substrate 3. It has become. The metal electrode 8, the light emitting layer 9, and the ITO electrode 10 are configured using the same characteristics as those of the metal electrode 4, the light emitting layer 5, and the ITO electrode 6 of the display unit 1, respectively. Test light 11 indicated by an arrow in FIG. 1 is extracted from the test light emitting unit 2 in a direction away from the display light 7. Further, the metal electrode 8 has a sufficient light shielding property so that the test light 11 does not leak to the front side from which the display light 7 is extracted, and the metal electrode 8 also serves as a light shielding layer.

  As shown in FIG. 2, the test light emitting unit 2 includes a red organic EL element 12R, a green organic EL element 12G, and a blue organic EL element 12B as a set at four corners on the back side of the glass substrate 3, respectively. These can be individually emitted by individual wirings (not shown).

  On the other hand, the display unit 1 is also omitted in the drawing, but the red organic EL element, the green organic EL element, and the blue organic EL element are arranged. The sub-pixel including the sub-pixel including the green organic EL element, and the sub-pixel including the blue organic EL element constitute one pixel.

  An example of the circuit configuration of each sub-pixel will be described with reference to FIG.

  In FIG. 3, reference numeral 13 denotes the sub-pixel, and the gate G of an FET (Field Effect Transistor) 14 (address selection transistor) is connected to an address scanning electrode line (address line) Ai for supplying an address signal. The source S of the FET 14 is connected to a data electrode line (data line) Bj that supplies a data signal. The drain D of the FET 14 is connected to the gate G of the FET 15 (driving transistor) and is grounded through the capacitor 16. The source S of the FET 15 is grounded, and the drain D is connected to the cathode (metal electrode 4) of the organic EL element (red organic EL element, green organic EL element or blue organic EL element provided in the display unit 1) 17. The organic EL element 17 is connected to a power source through the anode (ITO electrode 6).

  The light emission control operation of this circuit will be described. First, in FIG. 3, when the ON voltage is supplied to the gate G of the FET 14, the data voltage is supplied to the drain 14 of the FET 14. When the gate G of the FET 14 is at an off voltage, the FET 14 is so-called cutoff, and the drain D of the FET 14 is in an open state. Therefore, during the period when the gate G of the FET 14 is on-voltage, the voltage of the source S is charged in the capacitor 16 and the voltage is supplied to the gate G of the FET 15, and the FET 15 receives a current based on the gate voltage and the source voltage. The organic EL element 17 flows from the drain D to the source S through the organic EL element 17 to cause the organic EL element 17 to emit light. Further, when the gate G of the FET 14 is turned off, the FET 14 is in an open state, and the FET 15 is held at the voltage of the gate G by the charge accumulated in the capacitor 16, and the driving current is maintained until the next scanning. Luminescence is also maintained. Since a gate input capacitance exists between the gate G and the source S of the FET 15, the same operation as described above can be performed without providing the capacitor 16.

  Further, the correction of the display unit 1 using the test light emitting unit 2 can be performed as shown in FIG.

  That is, as shown in FIG. 4, the organic EL element 12 provided in the test light emitting unit 2 described in FIGS. 1 and 2 (the red organic EL element 12R and the green organic EL element provided in the test light emitting unit 2) A constant current source 18 is connected to both ends of the 12G or blue organic EL element 12B), and a predetermined current can be supplied to the organic EL element 12 so that the test light 11 having a constant luminance can be held. Yes. The correction unit 19 includes a light receiving element 20 at a position where the test light 11 can be received, and current measuring means 21 is connected to both ends of the output of the light receiving element 20. Thus, the test light 11 is received by the light receiving element 20, the generated light receiving current is measured by the current measuring means 21, taken out as light receiving data to the outside, and a preset set value is compared with the light receiving data. Then, when there is a difference between the two, the drive of the display unit 1 is controlled in a direction to correct the difference. This drive control can be performed, for example, by adjusting the data voltage supplied from the data line Bj shown in FIG. Specifically, when the received light data is lower than the set value, the data voltage is increased, and conversely, when the received light data is higher than the set value, the data voltage is decreased to make correction, and the brightness of the display unit 1 is kept constant. Can keep. As shown in FIG. 2 of this example, when four test light emitting units are provided, the average luminance at four locations is obtained for each color, and red (R), green (G), By adjusting the balance of blue (B), the color balance of the display unit can be adjusted. Further, regarding the correction of the in-plane luminance variation of the display unit, the luminance variation of the display unit is estimated from the luminance of the test light emitting unit at the four corners for each color (for example, the in-plane luminance gradient is estimated by linear approximation). It is also possible to create a correction table for the display unit and perform correction for the display unit.

  In this example, the current generated from the light receiving element 20 is measured and used as a detection signal. However, this detection signal may be a voltage or luminance obtained by the light receiving element 20. Further, the adjustment based on the received light data can be performed not only for adjusting the data voltage supplied from the data line Bj shown in FIG. 3 but also for adjusting the driving power of the organic EL element 17 of the display unit 1.

  As described above, since the test light emitting unit 2 of this example is provided separately from the display unit 1, the driving of the test light emitting unit 12 may adversely affect the driving of the organic EL elements on the display screen itself. Absent. In addition, the test light emitting unit 2 is provided on the back side of the glass substrate 3 on the side opposite to the display unit 1, and is away from the test light emitting unit 2 in a direction away from the display light 7 from the display unit 1. Since the test light 11 is emitted, the test light 11 of the test light emitting unit 2 leaks in the direction of the display light 7 of the display unit 1 and mixes with the display light 7, thereby causing partial discoloration or uneven brightness on the display screen. Can be prevented. Therefore, a test using the test light emitting unit 2 can be performed regardless of whether the display unit 1 is driven or not. Therefore, adjustment using the test light emitting unit 2 can be easily performed not only at the time of manufacture but also at the time of use. Since the light from the test light emitting unit does not affect the display unit, the test light emitting unit estimates and corrects the luminance deterioration of the display unit by applying an average constant current to the test light emitting unit when the display unit is turned on. It is also possible. Note that the average constant current applied here is a current for generating an average in-plane luminance when a general image taken with a digital camera or the like is displayed on the display unit. Naturally, although it differs depending on the display image, it is considered that about 1/3 of the maximum display luminance is appropriate. Accordingly, it is possible to cope with a decrease in luminance due to driving of the display unit, and it is possible to always realize stable display.

  When the test light emitting unit 2 is provided on the back side of the glass substrate 3 opposite to the display unit 1 as in this example, the test light emitting unit 2 can be provided at a free position without increasing the glass substrate 3. Thus, the light emitting display device can be downsized.

  In this example, the test light emitting units 2 are provided at the four corners on the back side of the glass substrate 3, but the test light emitting units 2 are not limited to these four locations, and may be 1 to 3 locations or 5 locations or more. it can. For example, it can also be provided at the center of the back side of the glass substrate 3, or at the four corners and the center. In particular, if it is provided at a plurality of locations, it is possible to adjust the luminance unevenness due to the difference in position.

  In particular, when the display unit 1 is a three-color color display, the test light emitting unit 2 includes a red organic EL element 12R, a green organic EL element 12G, and a blue organic EL element 12B as in this example. If the adjustment is performed based on the test light 11 generated from each set as provided as a set, it is possible to easily adjust the white balance disturbance due to the variation for each color. Further, as in the present example, the inspection result by the test light 11 from the test light emitting unit 2 is linked to the data voltage of the display unit 1, so that it is possible to cope with a change in the characteristics of the organic EL element when used for a long time. .

  Next, a second example of the present invention will be described with reference to FIG.

  FIG. 5 is a schematic cross-sectional view of a light emitting display device according to a second example of the present invention. The difference from FIG. 5 in the first example is that the test light emitting unit 2 is the same as the surface of the glass substrate 3 as the display unit 1. The test light 11 is emitted in a direction away from the display light 7 in the lateral direction.

  As in the above example, the display unit 11 is formed by sequentially laminating the metal electrode 4, the light emitting layer 5, and the ITO electrode 6 on the glass substrate 3. The test light emitting unit 2 includes the metal electrode 8, the light emitting layer 9, and the like. The ITO electrode 10 is sequentially laminated, and further, a light shielding layer 22 for blocking the test light 11 from being emitted in the direction overlapping the display light 7 is further stacked thereon. Further, the metal electrode 4, the light emitting layer 5, and the ITO electrode 6 of the display unit 1, and the metal electrode 8, the light emitting layer 9, and the ITO electrode 10 of the test light emitting unit 2 are configured using the same characteristics.

  With this configuration, the display light 7 from the display unit 1 emits light in the front direction (upward in the drawing), while the test light 11 of the test light emitting unit 2 emits in a direction away from the display light 7 in the lateral direction. To do. Therefore, it is possible to prevent the display light 7 from being adversely affected by the test light 11 being mixed with the display light 7, and the test light 11 can be accurately received by the light receiving element 20 described with reference to FIG.

  This example is suitable when there is no space for providing the test light emitting unit 2 on the back side of the display unit 1. Further, it can be formed simultaneously with the formation of the test light emitting unit 2 and the display unit 1, and there is an advantage that it is easy to manufacture.

  In the first example, the test light 11 is emitted in a direction away from the display light 7 in the opposite direction. However, the test light 11 in the first example is different from the second example. Similarly, light can be emitted in a direction away from the display light 7 in the lateral direction. In this way, the test light emitting unit 2 and the correcting unit 19 can be arranged in parallel on the back surface of the glass substrate 3, and the thickness of the light emitting display device can be reduced.

  In addition, the present invention is not limited to organic EL elements, and may be any display light-emitting element. For example, the present invention can be applied to inorganic EL elements, and can be applied to both simple matrix light-emitting display devices and active matrix light-emitting display devices. Applicable.

1 is a schematic cross-sectional view of a light-emitting display device according to a first example of the present invention. FIG. 2 is a rear view of the light emitting display device shown in FIG. 1. FIG. 3 is a circuit configuration diagram corresponding to one sub-pixel of the light-emitting display device illustrated in FIGS. 1 and 2. It is explanatory drawing of the method to monitor and correct | amend the test light of the test light emission part shown by FIG.1 and FIG.2. It is the cross-sectional schematic of the light emission display apparatus which concerns on the 2nd example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display part 2 Test light emission part 3 Glass substrate 4 Metal electrode 5 Light emitting layer 6 ITO electrode 7 Display light 8 Metal electrode 9 Light emitting layer 10 ITO electrode 11 Test light 12 Organic EL element (Test light emitting element 12R Red organic EL element 12G Green Organic EL element 12B Blue organic EL element 13 Subpixel 14 FET
15 FET
16 capacitor 17 organic EL element (display light emitting element)
18 constant current source 19 correction unit 20 light receiving element 21 current measuring means 22 light shielding layer

Claims (4)

In a light-emitting display device having a display unit including a number of display light-emitting elements that emit display light based on a data signal and a test light-emitting unit including a test light-emitting element for inspecting characteristics of the light-emitting elements.
The light emitting display characterized in that the test light emitting section emits test light from a test light emitting element in a second light emitting direction that is different from the first light emitting direction that is the light emitting direction of the display light. apparatus. The light-emitting display device according to claim 1, further comprising: a correction unit that changes driving power of the display light-emitting element based on light reception data obtained by receiving the test light. 3. The light emitting display device according to claim 1, wherein the second light emitting direction is a direction away from the first light emitting direction in a lateral direction or a direction away from the opposite direction. The light emitting display according to any one of claims 1 to 3, wherein the display unit is provided on one side of a glass substrate, and the test light emitting unit is provided on the other side of the glass substrate. apparatus.

Images