JP2012068379A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a voltage drop caused by current flowing to power supply wiring and the resulting luminance non-uniformity in an organic EL display device.SOLUTION: The present invention relates to a display device including: a display area in which display elements including light emission layers which are held between first electrodes and second electrodes are disposed in row and column directions; first power supply wiring connected in common to the first electrodes of the display elements disposed in the column direction; first connection wiring connected to the first power supply wiring; and a first power supply terminal connected to the first connection wiring. The first connection wiring is disposed in at least the row direction and includes three or more connection points with the first power supply wiring in the row direction. The first connection wiring is connected with the first power supply terminal at a midpoint in each of regions, which are obtained by equally dividing a gap between two connection points farthest from each other among the connection points in the first connection wiring, into two or more regions less than the number of connection points in the row direction.

Description

  The present invention relates to a display device, and more particularly to an image display device suitable for reducing luminance unevenness.

  As a next-generation display device, an EL display device using an electroluminescence (hereinafter referred to as EL) element is known. The EL element is a current control element. For example, the EL element is caused to emit light by flowing a current through a power supply wiring connected to the EL element.

  There are two known configurations for supplying current to the EL element. The configuration includes a connection wiring that connects a power supply wiring and a power supply terminal arranged in the display area, and a configuration in which one power supply terminal is arranged at the center of the connection wiring (see Patent Document 1). In this configuration, two power supply terminals are arranged at both ends of the connection wiring (see Patent Document 2).

JP 2001-102169 A US Pat. No. 7,273,312

  When a current flows through the power supply wiring connected to the EL element, a voltage drop occurs due to the resistance of the power supply wiring, and the current flowing through the EL element changes at a position close to and far from the power supply terminal, resulting in luminance unevenness. There's a problem.

  In the configuration described in Patent Document 1, the distance between the position where the voltage drop due to the power supply wiring resistance is the largest and the position where the power supply terminal is the smallest is greater than in the configuration where the power supply terminals are plural. For this reason, the luminance difference between the EL elements at a position close to the power supply terminal and a position far from the power supply terminal increases, and the luminance unevenness increases. On the other hand, although the configuration described in Patent Document 2 can be expected to improve the luminance unevenness compared to the configuration described in Patent Document 1, the luminance unevenness is still large.

  Accordingly, an object of the present invention is to provide a display device in which a plurality of power supply terminals are arranged at appropriate positions in order to reduce luminance unevenness.

In order to solve the above problems, the present invention provides a display region in which display elements each including a light emitting layer sandwiched between a first electrode and a second electrode are arranged in a row direction and a column direction;
A first power supply wiring commonly connected to the first electrode of the display element arranged in the column direction;
A first connection wiring connected to the first power supply wiring;
A first power supply terminal connected to the first connection wiring;
A display device comprising:
The first connection wiring is arranged along at least the row direction, and includes three or more connection locations with the first power supply wiring along the row direction,
Among the connection points in the first connection wiring, between the two most distant connection points, the middle point of each region equally divided into two or more in the row direction and smaller than the number of the connection points The display device is characterized in that the first connection wiring and the first power supply terminal are connected.

The present invention also provides a display region in which display elements each including a light emitting layer sandwiched between a first electrode and a second electrode are arranged in a row direction and a column direction;
A first connection wiring connected to the first electrode of the display element;
A first power supply terminal connected to the first connection wiring;
A display device comprising:
The first electrode of all the display elements is a common electrode;
The first connection wiring is arranged along at least the row direction, and a connection point connected to the first electrode through a contact hole provided on the first connection wiring is defined in the row. 3 or more along the direction,
Among the connection points in the first connection wiring, between the two most distant connection points, the middle point of each region equally divided into two or more in the row direction and smaller than the number of the connection points The display device is characterized in that the first connection wiring and the first power supply terminal are connected.

  According to the present invention, by disposing a plurality of power supply terminals, the distance between the position where the voltage drop from the power supply terminal is the largest and the position where the voltage drop from the power supply terminal is the smallest is reduced as compared with the case where there is one power supply terminal. For this reason, it is possible to reduce the luminance difference between the EL elements at positions close to and far from the power supply terminal, and to reduce luminance unevenness. Further, there are three or more connection points between the connection wiring and the power supply wiring or the electrode, and N (2 ≦ N ≦ connection point) in the row direction between two connection points farthest from each other among the connection points. The connection wiring and the power supply terminal are connected at the midpoint of each divided area. By doing so, the distance between the position where the voltage drop from the power supply terminal is the largest and the position where the voltage drop is the smallest can be further reduced, and the luminance unevenness can be further reduced.

It is a figure which shows the structure of the display apparatus of 1st Embodiment. FIG. 2 is a simplified diagram for explaining a voltage drop amount of the display device of FIG. 1. It is a pixel circuit diagram suitably used for the display device of the present invention. It is a figure which shows the structure of the display apparatus of 2nd Embodiment. FIG. 5 is a simplified diagram for explaining a voltage drop amount of the display device of FIG. 4. It is a figure which shows the structure of the display apparatus of 3rd Embodiment. It is a figure which shows the structure of the display apparatus of 4th Embodiment. It is a figure which shows the structure of the display apparatus which provided the power supply terminal in the center part of the connection wiring. FIG. 9 is a simplified diagram for explaining a voltage drop amount of the display device of FIG. 8. It is a figure which shows the structure of the display apparatus which provided the power supply terminal in the both ends of the connection wiring. FIG. 11 is a simplified diagram for explaining a voltage drop amount of the display device of FIG. 10.

  The present invention is applicable to any display device having a self-luminous display element such as an organic EL element. Preferred embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 is a display device of this embodiment, which is an organic EL display device in which a display element including a light emitting layer sandwiched between a first electrode and a second electrode is an organic EL element. In this embodiment, the first electrode is an anode electrode and the second electrode is a cathode electrode. However, the first electrode may be a cathode electrode and the second electrode may be an anode electrode.

  The display device 1 in FIG. 1 has a display area 2 in which organic EL elements are arranged in a row direction and a column direction. In addition, the first power supply wiring 8 (power supply wiring in the display area) connected in common to the first electrodes (not shown in FIG. 1) of the organic EL elements arranged in the column direction, and the first power supply wiring 8 includes a first connection wiring 3 connected to 8 and a first power supply terminal 6 connected to the first connection wiring 3. The first connection wiring 3 is arranged at least along the row direction, and has 13 connection locations with the first power supply wiring 8 along the row direction. Of the 13 connection points in the first connection line 3, the first connection line 3 and the first point are located at the midpoint of each region that is divided into two equal parts in the row direction between the two most distant connection points. The power supply terminal 6 is connected.

  Further, the display device 1 in FIG. 1 includes a second connection wiring 4 arranged outside the display area 2, a second power supply terminal 7 connected to the second connection wiring 4, and a second connection wiring. 4 and the second power supply terminal 7 is connected to the second electrode (the electrode indicated by the broken line in FIG. 1). The second electrode is a common electrode 5 commonly connected to all pixels (all organic EL elements), and the second connection wiring 4 is connected to the common electrode 5 through a contact hole.

  FIG. 3 is an example of a pixel circuit preferably used in the display device of FIG. In FIG. 3, 10 is a data line, 11 is a scanning line, and 12 is an organic EL element. M1 is a switching transistor that controls the light emission timing of the organic EL element 12, M2 is a drive transistor that controls the light emission intensity of the organic EL element 12, and C1 is a storage capacitor for holding the light emission of the organic EL element 12. These transistors and the storage capacitor constitute an element control circuit. VCC is a power supply potential, CGND is a ground potential, and A and K represent an anode electrode and a cathode electrode of the organic EL element 12, respectively. The anode electrode A of the organic EL element 12 is connected to the power supply potential VCC via the drive transistor M2, and the cathode electrode K is connected to the ground potential CGND. Light emission of the organic EL element 12 occurs when a drive current passes from the power supply potential VCC through the drive transistor M2 and the organic EL element 12 and flows to the ground potential CGND according to the gate voltage of the drive transistor M2.

  The pixel circuit used in the display device of the present invention is not limited to the pixel circuit of FIG. 3, and may be another pixel circuit. For example, a pixel circuit in which the anode electrode A of the organic EL element is a common electrode may be used. The pixel circuit in FIG. 3 is a so-called voltage programming circuit, but may not be a voltage programming circuit, but may be a so-called current programming circuit.

  Next, the effect of the present invention will be described with reference to FIG. 2, which is a simplified diagram of the layout of the display device of FIG. In order to simplify the description, in FIG. 2, the number of the first power supply wires 8 is five, and the number of connection points between the first connection wires 3 and the first power supply wires 8 is five. Even when the number of connection points is five, the effect of the present invention can be obtained as in the case where the number of connection points is thirteen. In addition, among the five connection points in the first connection wiring 3, the first connection wiring 3 and the first connection wiring 3 are divided at the midpoint of each region in which the two connection points farthest from each other are equally divided in the row direction. A first power supply terminal 6 is connected. Each first power supply terminal 6 (anode terminal) is equally supplied with power from the same power source.

  In FIG. 2, when the resistance value of each connection wiring resistor 9 is R, the current value flowing through each first power supply wiring 8 is I, and the potential of the connection portion b is V0, the potential of the connection portion a is V0 + RI. The potential of the part c is V0 + (RI / 2). Therefore, the maximum value of the voltage drop from the first power supply terminal 6 in the layout of FIG. 2 is RI.

  Here, when there is one first power supply terminal 6 at the center of the first connection wiring 3 (FIG. 8), two first power supply terminals 6 are provided at both ends of the first connection wiring 3. In each case (FIG. 10), the maximum value of the voltage drop from the first power supply terminal 6 is calculated and compared with the case of FIG. This comparison is performed using FIG. 9 which is a simplified diagram of the layout of the display device of FIG. 8 and FIG. 11 which is a simplified diagram of the layout of the display device of FIG. 9 and 11, as in FIG. 2, there are five connection points between the first connection wiring 3 and the first power supply wiring 8.

  In FIG. 9, when the resistance value of each connection wiring resistor 9 is R, the current value flowing through each first power supply wiring 8 is I, and the potential of the connection portion i is V0, the potential of the connection portion g is V0 + 3RI. The potential of the part h is V0 + 2RI. Therefore, the maximum value of the voltage drop from the first power supply terminal 6 in the layout of FIG. 9 is 3RI.

  On the other hand, in FIG. 11, when the resistance value of each connection wiring resistor 9 is R, the current value flowing through each first power supply wiring 8 is I, and the potential of the connection portion j is V0, the potential of the connection portion k is V0 +. (3RI / 2), the potential of the connection portion l is V0 + 2RI. Therefore, the maximum value of the voltage drop from the first power supply terminal 6 in the layout of FIG. 11 is 2RI.

  From the above, in the case of FIG. 2, the maximum value of the voltage drop is 1/3 compared to the case of FIG. 9, and the maximum value of the voltage drop is ½ compared to the case of FIG. In an actual display device, there are cases where the number of connection points is other than five, and therefore the amount of decrease in the maximum value of the voltage drop may be slightly different from that in FIG.

  As described above, in the case of FIG. 2, the voltage drop in the first connection wiring on the first electrode side can be suppressed, so that the luminance unevenness can be reduced.

  In the present embodiment, among the connection locations in the first connection wiring 3, the first connection wiring 3 is connected to the first connection wiring 3 at the midpoint of each region that is divided into two in the row direction between the two most distant connection locations. A first power supply terminal 6 is connected. The reason for this configuration is that the voltage drop from the power supply terminal can be suppressed as described above. In addition, if the number is divided equally into the number smaller than the number of connection locations in the row direction, the voltage drop from the power supply terminal can be suppressed even when the number is equally divided into two.

  Here, the case where the power supply terminal is arranged at the midpoint of each region where the two farthest connection points are equally divided in the row direction by the same number as the connection points, and the first connection wiring 3 Consider a case where a power supply terminal is arranged at each connection point in FIG. Comparing the former and the latter, both have the same number of power supply terminals, but the former has a larger maximum voltage drop from the power supply terminal than the latter.

  Further, in the case where the two farthest connection points are divided into N equal parts in the row direction, the number of power supply terminals to be arranged increases as the value of N increases, so that the manufacturing process for forming the power supply terminals Will increase.

  Therefore, in consideration of suppressing a voltage drop from the power supply terminal and not increasing the manufacturing process, when N is equally divided in the row direction between two connection points farthest from each other, N is 2 or more and The number may be smaller than the number of connection locations (2 ≦ N ≦ number of connection locations−1). Further, in order to satisfy the condition N, it is necessary to provide three or more connection locations between the first connection wiring 3 and the first power supply wiring 8.

[Second Embodiment]
FIG. 4 shows the display device of this embodiment. The display device according to the present embodiment includes the first connection wiring 3 at the midpoint of each region obtained by dividing the two connection points farthest from each other into three equal parts in the row direction. 1 is the same as that shown in FIG. 1 except that the connection wiring 3 and the first power supply terminal 6 are connected. In this embodiment, as in the first embodiment, the first electrode is an anode electrode and the second electrode is a cathode electrode, but the first electrode may be a cathode electrode and the second electrode may be an anode electrode. For example, the pixel circuit of FIG. 3 is preferably used in the display device of FIG.

  Next, the effect of the present invention will be described with reference to FIG. 5 which is a simplified diagram of the layout of the display device of FIG. In order to simplify the description, in FIG. 5, the number of the first power supply wires 8 is seven, and the number of connection points between the first connection wires 3 and the first power supply wires 8 is seven. Even when the number of connection points is seven, the effect of the present invention can be obtained as in the case where the number of connection points is thirteen. In addition, among the seven connection points in the first connection wiring 3, the first connection wiring 3 A first power supply terminal 6 is connected. Each first power supply terminal 6 is equally supplied with power from the same power supply.

  In FIG. 5, assuming that the resistance value of each connection wiring resistor 9 is 2R / 3, the current value flowing through each first power supply wiring 8 is 5I / 7, and the potential of the connection portion e is V0, the potential of the connection portion d. Is V0 + (10RI / 21), and the potential of the connection portion f is V0 + (5RI / 21). Therefore, the maximum value of the voltage drop from the first power supply terminal 6 in the layout of FIG. 4 is 10 RI / 21.

  From the above, in the case of FIG. 5, the maximum value of the voltage drop is about 1/6 compared to the case of FIG. 9, and the maximum value of the voltage drop is about 1/4 compared to the case of FIG. In an actual display device, there are cases where the number of connection points is other than seven, and the amount of decrease in the maximum value of the voltage drop may be slightly different.

  As described above, in the case of FIG. 5, the voltage drop in the first connection wiring on the first electrode side can be suppressed, so that the luminance unevenness can be reduced.

  In the present embodiment, the number N for equally dividing the connection places into 13 is set to 3. However, if the number of the connection places is 3 or more and 2 ≦ N ≦ the number of connection places−1, the effect of the present invention is obtained. It is done.

[Third Embodiment]
FIG. 6 is a display device according to this embodiment, which is an organic EL display device in which a display element including a light emitting layer sandwiched between a first electrode and a second electrode is an organic EL element. In this embodiment, the first electrode is an anode electrode and the second electrode is a cathode electrode. However, the first electrode may be a cathode electrode and the second electrode may be an anode electrode. For example, the pixel circuit of FIG. 3 is preferably used in the display device of FIG.

  The display device of FIG. 6 has a display area in which organic EL elements are arranged in a row direction and a column direction. Moreover, it has the 2nd connection wiring 4 connected to the 2nd electrode of an organic EL element, and the 2nd power supply terminal 7 connected to the 2nd connection wiring 4. FIG. The second electrode is made of a transparent conductive material, and is a common electrode 5 commonly connected to all pixels. The second connection wiring 4 is arranged at least along the row direction, and a connection portion connected to the second electrode via the contact hole 13 provided on the second connection wiring 4 is arranged along the row direction 11. There are places. Of the eleven connection points in the second connection wiring 4, the second connection wiring 4 and the second connection point at the midpoint of each region obtained by equally dividing the two connection points farthest from each other in the row direction. The power supply terminal 7 is connected.

  Further, the display device of FIG. 6 includes a first power supply wiring 8 commonly connected to first electrodes (not shown in FIG. 6) of organic EL elements arranged in the column direction, and a first power supply wiring 8. And a first power supply terminal 6 connected to the first connection wiring 3.

  On the first electrode side, the first power supply wiring is not provided, and the first electrode, the first connection wiring, and the first power supply terminal are connected to the second electrode, the second connection wiring, and the first power supply terminal in FIG. You may make it the same structure as 2 power supply terminals. In the case of the above configuration on the first electrode side, a second power supply wiring is provided on the second electrode side, and the second electrode, the second power supply wiring, the second connection wiring, and the second power supply terminal are provided. Are configured in the same manner as the first electrode, the first power supply wiring, the first connection wiring, and the first power supply terminal in FIG.

  In this way, in the case of FIG. 6, the lead line is branched from the middle point and connected to the second power supply terminal 7. By doing so, it is possible to suppress the potential increase at the connection portion between the second connection wiring 4 and the lead-out line, that is, the ground potential CGND to the contact hole 13, and to reduce the luminance unevenness.

  In the present embodiment, the number N of equally dividing the connection places is 11, and the number N is set to 2. However, if the number of connection places is 3 or more and 2 ≦ N ≦ number of connection places−1, the effect of the present invention is obtained. It is done.

[Fourth Embodiment]
FIG. 7 is a display device according to this embodiment, and is an organic EL display device in which a display element including a light emitting layer sandwiched between a first electrode and a second electrode is an organic EL element. In this embodiment, the first electrode is an anode electrode and the second electrode is a cathode electrode. However, the first electrode may be a cathode electrode and the second electrode may be an anode electrode. For example, the pixel circuit of FIG. 3 is preferably used in the display device of FIG.

  The display device of FIG. 7 has a display area in which organic EL elements are arranged in a row direction and a column direction. Further, the first power supply wiring 8 connected in common to the first electrodes (not shown in FIG. 7) of the organic EL elements arranged in the column direction, and the first power supply wiring 8 connected to the first power supply wiring 8. Connection wiring 3 and a first power supply terminal 6 connected to the first connection wiring 3. The first connection wiring 3 is arranged at least along the row direction, and has nine connection locations with the first power supply wiring 8 along the row direction. Among the nine connection points in the first connection line 3, the first connection line 3 and the first point are located at the midpoint of each region obtained by dividing the two connection points farthest apart from each other in the row direction. The power supply terminal 6 is connected.

  Further, the display device of FIG. 7 includes a second connection wiring 4 connected to the second electrode of the organic EL element, and a second power supply terminal 7 connected to the second connection wiring. The second electrode is a common electrode 5 commonly connected to all pixels. The second connection wiring 4 is arranged along at least the row direction, and the connection points connected to the second electrode via the contact holes 13 provided on the second connection wiring 4 are arranged along the row direction. There are places. Of the four connection points in the second connection wiring, the second connection wiring and the second power source at the midpoint of each region obtained by dividing the two connection points farthest from each other into two equal parts in the row direction The supply terminal is connected.

  On the second electrode side, a second power supply wiring is provided, and the second electrode, the second power supply wiring, the second connection wiring, and the second power supply terminal are connected to the first electrode, the first power supply in FIG. The power supply wiring, the first connection wiring, and the first power supply terminal may have the same configuration. In the case of the above configuration on the second electrode side, the first power supply wiring is not provided on the first electrode side, and the first electrode, the first connection wiring, and the first power supply terminal are connected as shown in FIG. The second electrode, the second connection wiring, and the second power supply terminal may have the same configuration. In the case of the above configuration on the second electrode side, the first electrode, the first power supply wiring, the first connection wiring, and the first power supply terminal are the same as those in FIG. 7 on the first electrode side. It may be configured.

  As described above, in the case of FIG. 7, it is possible to suppress a voltage drop in the first connection wiring on the first electrode side and to suppress a voltage increase in the second connection wiring on the second electrode side. Therefore, luminance unevenness can be further reduced.

  In the present embodiment, the number N for dividing the connection portion into nine places on the first electrode side is set to 2, and the number N for dividing the connection portion into four places on the second electrode side is set to two. The effect of the present invention can be obtained if there are three or more connection locations and 2 ≦ N ≦ number of connection locations−1.

  1: display device, 2: display area, 3: first connection wiring, 4: second connection wiring, 5: common electrode, 6: first power supply terminal, 7: second power supply terminal, 8 : First power supply wiring, 12: Organic EL element, 13: Contact hole

Claims (4)

A display region in which display elements each including a light emitting layer sandwiched between a first electrode and a second electrode are arranged in a row direction and a column direction;
A first power supply wiring commonly connected to the first electrode of the display element arranged in the column direction;
A first connection wiring connected to the first power supply wiring;
A first power supply terminal connected to the first connection wiring;
A display device comprising:
The first connection wiring is arranged along at least the row direction, and includes three or more connection locations with the first power supply wiring along the row direction,
Among the connection points in the first connection wiring, between the two most distant connection points, the middle point of each region equally divided into two or more in the row direction and smaller than the number of the connection points The display device is characterized in that the first connection wiring and the first power supply terminal are connected. A display region in which display elements each including a light emitting layer sandwiched between a first electrode and a second electrode are arranged in a row direction and a column direction;
A first connection wiring connected to the first electrode of the display element;
A first power supply terminal connected to the first connection wiring;
A display device comprising:
The first electrode of all the display elements is a common electrode;
The first connection wiring is arranged along at least the row direction, and a connection point connected to the first electrode through a contact hole provided on the first connection wiring is defined in the row. 3 or more along the direction,
Among the connection points in the first connection wiring, between the two most distant connection points, the middle point of each region equally divided into two or more in the row direction and smaller than the number of the connection points The display device is characterized in that the first connection wiring and the first power supply terminal are connected. A second power supply wiring commonly connected to the second electrode of the display element arranged in the column direction;
A second connection wiring connected to the second power supply wiring;
A second power supply terminal connected to the second connection wiring,
The second connection wiring is arranged along at least the row direction, and has three or more connection locations along the row direction with the second power supply wiring,
Among the connection locations in the second connection wiring, at the midpoint of each region that equally divides between two connection locations farthest apart from each other into two or more in the row direction and smaller than the number of the connection locations. The display device according to claim 1, wherein the second connection wiring and the second power supply terminal are connected. A second connection wiring connected to the second electrode of the display element;
A second power supply terminal connected to the second connection wiring,
The second electrode of all the display elements is a common electrode;
The second connection wiring is disposed along at least the row direction, and a connection point connected to the second electrode through a contact hole provided on the second connection wiring is defined in the row. 3 or more along the direction,
Among the connection locations in the second connection wiring, at the midpoint of each region that equally divides between two connection locations farthest apart from each other into two or more in the row direction and smaller than the number of the connection locations. The display device according to claim 1, wherein the second connection wiring and the second power supply terminal are connected.

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