JP2009059705A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board for a light-emitting element capable of preventing voltage drop on a common electrode and displaying bright image. <P>SOLUTION: The circuit board for a light-emitting element is suitable for forming a field light-emitting element emitting light by being supplied with current. The circuit board for a light-emitting element comprises an extraction terminal group 6 wherein extraction terminals 61 to the outside are accumulated on one side of the board, and a contact pattern 2 for electrically connecting the extraction terminals 61 at a part of the extraction terminal group 6 and the common electrode 10 between the common electrode 10 where common current flows and the extraction terminal group. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an improvement of a circuit board suitable for forming a so-called electro-luminescence element.

  As a known technique related to the substrate arrangement in a display device using an electroluminescent element, there is a technique described in Japanese Patent Application Laid-Open No. 11-24604 relating to the invention of the present applicant. This publication discloses a circuit board that surrounds a formation region of an electroluminescent element and has a drive circuit.

  Since the electroluminescent element emits light by supplying current, if the resistance of the wiring is high, the voltage drop becomes large and the luminance tends to be low. In order to cope with this, conventionally, it has been necessary to use a metal having a low resistivity as a material for the wiring layer according to the common general technical knowledge.

  However, sufficient consideration has not been given to the prevention of the overall voltage drop across the circuit board.

  In particular, the largest current flows in the cathode which is a common electrode through which currents from a plurality of electroluminescent elements flow. In this cathode pattern, if the resistivity is high, a large voltage drop is caused by a large amount of current, which may darken the entire image display.

  Therefore, an object of the present invention is to provide a circuit board for a light emitting element for reducing a voltage drop in a common electrode and enabling a bright image display, and an electronic apparatus using the board.

  The present invention relates to a circuit board for a light emitting element used for forming a light emitting element, an extraction terminal group in which extraction terminals to the outside are integrated on one side of the substrate, a region where a predetermined common electrode is disposed, and the extraction terminal A light emitting element circuit board comprising a contact pattern electrically connecting a part of the extraction terminals of the extraction terminal group and the common electrode between the groups.

  “Extraction terminal” does not necessarily mean that it is provided only on one side of the substrate. The “circuit board” is an example of an element that consumes a large amount of current, such as an electroluminescent element, and the circuit provided on the circuit board is not limited to this. The “common electrode” is provided in a later step, and is not limited to the common electrode already formed on the circuit board. It is meaningful that a contact pattern is provided corresponding to a “region” where a “common electrode” will be formed. Therefore, a mode in which circuit boards that do not have a structure related to display such as a common electrode are distributed as is possible.

  For example, the circuit board is used to form a light emitting element that emits light by supplying current, and the contact pattern includes a part of the extraction terminal group and a common electrode through which the current of the light emitting element flows in common. It is formed so as to be electrically connected.

  The light emitting element is applied to an organic electroluminescent element or the like.

  Here, the contact pattern preferably has an area of 10% or more of the area of the common electrode. “10%” is a temporary measure and is not limited to this.

  The extraction terminal group includes a series of extraction terminals having the same shape. This is because the connection terminals of the same form can be standardized and can be standardized and can be economically and easily connected.

  The formed common electrode is rectangular, and a scan driving circuit for supplying a scan signal to the scan wiring is provided in a region facing the contact pattern via the common electrode.

  Further, a region for forming a signal drive circuit and / or a peripheral circuit for supplying an image signal to the signal wiring is provided in a region other than the peripheral region of the common electrode where the contact pattern and the scanning drive circuit are provided. There is no limitation on which side the signal driving circuit and the peripheral circuit are located.

  It is preferable that alignment marks are provided at the four corners of the region where the common electrode where no circuit is provided is formed. The purpose is to effectively use the gaps of the circuits provided around the common electrode.

  The present invention is also an electronic apparatus including the circuit board for a light emitting element according to the present invention. The electronic device is not limited, but includes a portable information terminal, a viewfinder, a head mounted display, and the like.

  For example, in the case of a display device, the light-emitting element circuit board of the present invention and a plurality of light-emitting elements provided on the circuit board corresponding to each pixel are displayed, and an image is displayed by controlling the light-emitting element. Configured as follows.

  Such a display device includes a transistor that controls driving of the light emitting element of the pixel corresponding to the light emitting element of each pixel.

  When the light-emitting element is a current-controlled light-emitting element, each pixel includes a control transistor and a drive transistor for the light-emitting element.

  The light-emitting element in each pixel includes a pixel electrode and a light-emitting layer made of at least an organic light-emitting material between the pixel electrode and the common electrode.

  Next, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a plan view of a circuit board for a light emitting display element according to the present embodiment. As shown in FIG. 1, the circuit board includes a display area 1, a contact pattern 2, a signal driving circuit 3, a scanning driving circuit 4, a peripheral circuit 5, an extraction terminal group 6 and an alignment mark 7.

The display area 1 is composed of a plurality of pixel areas, and a common electrode 10 through which a common current flows is formed so as to cover all the pixel areas on the upper surface (before the drawing).
Although the element formed in each pixel region is not limited, in the present embodiment, for example, an electroluminescent element 12 having a structure as shown in FIG. 2 is exemplified. The common electrode 10 is formed in a square shape in a normal display device.

  The external terminal group 6 includes a plurality of external lead terminals integrated on one side of the substrate. The extraction terminal group 6 is configured by connecting extraction terminals 61 having the same shape. If it is the extraction terminal of the same form, it can be mounted collectively by the insert machine etc. from the tape which mounted the terminal. For this reason, it is economical and easy to standardize the connection with the board by a connector or the like. Each extraction terminal 61 may be one in which a conductive terminal is mechanically retrofitted or provided by forming a conductive material in a thin film by a process such as photolithography.

  The contact pattern 2 is provided between the common electrode 10 and the extraction terminal group 6 according to the present invention, and electrically connects a part of the extraction terminals 61 and the common electrode 10 of the extraction terminal group 6 via the contact wiring 21. It is a pattern to connect to. The contact wiring 21 is patterned in the same layer with the same material as the extraction terminal 61. However, the contact pattern 2 and each extraction terminal 61 may be directly connected.

Here, the contact pattern 2 preferably has an area of 10% or more of the area of the common electrode. That is, the drive current of the electroluminescent element is about 10 mA / cm ² . On the other hand, the contact resistance of the contact pattern 2 is about 5 Ω · cm ² . When the light emitting area of all the electroluminescent elements is Acm ² and the area ratio of the contact pattern to the common electrode 10 is k, the voltage drop Vdrop [mV] generated in the contact pattern 2 is A × 10 · 5 / kA.

  Here, considering the driving voltage suitable for the electroluminescent element, the voltage drop allowed in the contact pattern is up to about 0.5 V, so k> = 0.1, and the ratio of the area of the contact pattern to the area of the pixel region is About 10% is necessary.

  The signal driving circuit 3 is a driving circuit for supplying an image signal to the signal wiring sig arranged in the display area 1. The signal driving circuit 3 is connected to some of the extraction terminals 61 by the bus wiring 31. The peripheral circuit 5 is a circuit group for supplying power to the power supply line com arranged in the display area 1 and detecting a signal of the signal line sig. The peripheral circuit 5 is connected to some of the extraction terminals 61 by the bus wiring 51. The arrangement of the signal driving circuit 3 and the peripheral circuit 5 is not limited to this, and the positions of the signal driving circuit 3 and the peripheral circuit 5 may be reversed.

  The scan drive circuit 4 is a drive circuit for supplying a scan signal to the scan lines gate arranged in the display area. The scanning drive circuit 4 is provided in a region facing the contact pattern via the common electrode. The scanning drive circuit 4 is connected to some of the extraction terminals 61 by the bus wiring 41. The scanning drive circuit 4 is provided at this position because it requires more circuits for supplying power in the signal wiring direction than the scanning wiring and the signal wiring. This is because the circuit is provided and the lead-out wiring of the common electrode 10 is arranged by the contact pattern from one side in the scanning wiring direction. For this reason, although the distance from the signal drive circuit 4 to the extraction terminal group 6 becomes long, the influence of the wiring resistance can be reduced because the scanning frequency of the scanning signal is relatively slow. In addition, since the number of bus lines 41 required for the scan driving circuit 4 is not so large, a large area is not occupied.

  The alignment marks 7 are provided at the four corners of the common electrode 10 where these circuits are not provided. In the electroluminescent element, it is necessary to go through steps such as vapor deposition, sputtering, ink jet process, cathode (common electrode) vapor deposition, and sputtering after the circuit formation step. In order to accurately position the substrate, it is preferable to provide an alignment mark for improving the alignment accuracy. In the process of forming the electroluminescent element, a photolithography method is applied, and a physical mask slightly larger than the display region 1 is applied in addition to the photomask for exposure. Further, in the circuit board, circuits are provided on the four circumferences of the display area 1, but there are no circuits at the four corners. The alignment marks 7 are provided at the four corners of the display area 1 and not covered with the physical mask. By arranging in this way, the board space can be used efficiently, and it is possible to prevent the size of the board from increasing due to the marks.

  FIG. 2 is a cross-sectional view taken along the line AA in FIG. FIG. 2 is an enlarged view of one extraction terminal and a pixel region.

  As shown in FIG. 2, the layer structure of the circuit board includes a transparent substrate 100, a semiconductor layer 101, a gate insulating film 102, a first interlayer insulating film 103, a second interlayer insulating film 104, a bank layer 105, 106 is formed. A light emitting layer 107 is further formed in the display region 1. A tantalum wiring layer 201, an aluminum wiring layer 202, an ITO layer 203, and a cathode layer 204 are formed as layers involved in the wiring.

  Regarding the material, the transparent substrate 100 is formed of glass, quartz, or the like that is light transmissive and has a certain mechanical strength. The semiconductor layer 101 is formed of polysilicon that is polymerized by applying energy to patterned amorphous silicon, and impurities are doped in the source and drain regions. The gate insulating film 102, the first interlayer insulating film 103, and the second interlayer insulating film 104 are made of silicon oxide or silicon nitride. Bank layers 105 and 106 are formed of an insulating film such as silicon oxide, silicon nitride, or polyimide. The tantalum wiring layer 201 is one of the constituent materials of the contact pattern 2 besides being mainly used for gate wiring of a thin film transistor (TFT). The aluminum wiring layer 202 is mainly used for through holes and wiring. As a material of this layer, tantalum, molybdenum, titanium, tungsten, or the like can be used in addition to aluminum. The ITO electrode 203 is formed of a material having optical transparency and conductivity such as ITO. The cathode layer 204 is a layer that bears the wiring of the common electrode 10 and is formed of a material that can be used as a cathode of an electroluminescent element, aluminum or an alloy of aluminum and another element (such as lithium), calcium, or the like in terms of energy ranking. The The electroluminescent layer 107 is a material such as an organic light emitting material in which holes transported from the anode and electrons transported from the cathode are combined to generate an electroluminescent phenomenon. A layer and / or an electron transport layer may be provided. The electroluminescent layer 107 may be patterned for each pixel.

  For one pixel region 11, an electroluminescent element 12, a driving transistor 13, and a control transistor (a control transistor is not shown in FIG. 2) are provided. In order to simplify the explanation, illustration of the control transistor is omitted.

  The electroluminescent element 12 has a structure in which the electroluminescent layer 107 is sandwiched between the pixel electrode 121 and the cathode layer 204. The cathode layer 204 is formed as a continuous film common to all the pixel regions 11. The pixel electrode 121 is an anode.

  The driving transistor 13 is a thin film transistor, and includes a source electrode 131, a drain electrode 132, and a gate electrode 133 on a semiconductor layer 101 in which a source region and a drain region are formed by introducing impurities. The source electrode 131 and the drain electrode 132 are configured by forming an aluminum wiring layer 202 in the openings of the through holes 301 and 302. The gate electrode 133 is electrically connected to the drain of the control transistor 14 and is formed of a tantalum wiring layer 201.

  The contact pattern 2 is a structure in which the cathode layer 204 and the contact wiring 21 are electrically connected to each other by the ITO layer 203, the aluminum wiring layer 202, and the tantalum wiring layer 201 through the through holes 303 in terms of the layer structure. is there. The ITO layer 203 is a pixel electrode 121 of the electroluminescent element on the display region 1 side, the aluminum wiring layer 202 is a layer made of the same material as the source electrode 131 and the drain electrode 132, and the tantalum wiring layer 201 is the same material as the gate electrode 133. When the electrodes are patterned, they are simultaneously patterned. Since all the conductive layers are used for the connection between the cathode layer 204 and the contact wiring 21, it is possible to make an electrical connection with extremely low resistance. Further, any one of the ITO layer 203, the aluminum wiring layer 202, and the tantalum wiring layer 201 may not exist. The end of the contact wiring 21 opposite to the display area 1 side has a structure in which an ITO layer 203, an aluminum wiring layer 202, and a tantalum wiring layer 201 are laminated in a through hole 304, and is connected to an extraction terminal 61 mounting tape. Yes.

  FIG. 3 shows an overall circuit diagram of an electroluminescence display element which is a set of the pixel regions 11.

  In the electroluminescent display device, the signal line sig is connected to the signal drive circuit 3 and supplies an image signal to the signal line sig via the bus line 31. The power supply line com is connected to the peripheral circuit 5 and supplies a current to the power supply line at a constant voltage. The scan line gate is connected to the scan drive circuit 4 and supplies a scan signal to the scan line gate via the bus line 41. In the signal drive circuit 3 and the scan drive circuit 4, a complementary transistor circuit is formed by an N-type transistor and a P-type transistor. Complementary transistors constitute basic circuits such as a shift register, level shifter, analog switch, and latch for functioning as a drive circuit.

  The pixel region 11 is surrounded by the signal wiring sig, the scanning wiring gate, and the power supply wiring com, and each includes an electroluminescence element 12, a driving transistor 13, a control transistor 14, and a storage capacitor cap as an equivalent circuit. I have.

  In the above configuration, when the scanning signal is supplied to the gate of the control transistor 14 through the scanning wiring gate, the control transistor 14 is turned on, and the potential of the image signal is supplied to the drain through the signal wiring sig. Is done. This potential is held in the holding capacitor cap. When a potential for lighting the pixel is supplied as an image signal, the driving transistor 13 is turned on, and a power supply current is supplied to the pixel electrode 121 through the source. In the electroluminescent element 12, in the electroluminescent layer 107, holes transported from the pixel electrode 121 and electrons transported from the common electrode 10 combine to generate an electroluminescent phenomenon and emit light. Light from the electroluminescent layer 107 is emitted from the transparent substrate 100 through the pixel electrode 121 which is a transparent electrode.

  According to the above configuration, the cathode of the electroluminescent element 12 serves as the common electrode 10 and is connected to a certain number of extraction terminals 61 via the contact pattern 2. The descent can be reduced and a bright image can be displayed. By reducing the resistance value, power consumption is reduced and heat generation can be suppressed.

  The cathode pattern is drawn from one side in the scanning direction with a small number of circuits, the scanning drive circuit is placed on the opposite side, and the other circuits are placed on the remaining side. Wiring is possible, and the above-described effects are exhibited. In addition, since the wiring length to the peripheral circuit providing the power supply wiring can be made relatively short, the voltage drop can be minimized.

  Moreover, since the extraction terminal is formed in the same shape, it is possible to facilitate manufacture and make it economical. Since the extraction terminal is arranged on one side of the substrate, connection with another substrate can be facilitated.

  Furthermore, alignment marks are provided at the four corners of the display area corresponding to the outside of the physical mask, which is a gap in the circuit, so that appropriate alignment can be provided by effectively utilizing the gap in the circuit without increasing the panel size. And efficient use of space can be achieved.

Note that the light emitting element circuit board as described above can be formed through a known thin film process. That is, it is manufactured by repeating the steps of forming oxide films by a CVD method, applying photolithography to open through holes, forming a conductive film by a sputtering method, and patterning.
(Other variations)
The present invention is not limited to the above-described embodiment, and can be variously modified and applied.

  For example, although the display element is an electroluminescent element, the present invention is not limited to this, and the present invention can be applied to circuit arrangements of all elements that consume a relatively large current.

Moreover, the circuit board for light emitting elements of this invention is applicable to all electronic devices.
The electronic device is not limited, but includes a small display device, a viewfinder, a head mounted display, and the like.

  According to the circuit board for a light emitting element of the present invention, since the contact pattern is provided between the common electrode and the extraction terminal, the voltage drop can be minimized and a bright image display including a plurality of light emitting elements is provided. It can be used as a substrate of a display device.

The top view of the circuit board for light emitting elements of an embodiment. Sectional drawing of the circuit board for light emitting elements of embodiment. 1 is an overall circuit diagram of a display device using an electroluminescent element.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Pixel region, 2 ... Contact pattern, 3 ... Signal drive circuit, 4 ... Scan drive circuit, 5 ... Peripheral circuit, 6 ... Extraction terminal group, 61 ... Extraction terminal, 10 ... Common electrode, 11 ... Electroluminescent element, 12 Thin film transistor 101 Semiconductor layer (p-Si) 102 Gate insulating film 103 104 Interlayer insulating film 105 106 Bank layer 107 Electroluminescent layer (electron / hole transport layer as required 121 ... pixel electrode, 131 ... source electrode, 132 ... drain electrode, 133 ... gate electrode, 201 ... tantalum wiring layer (Ta), 202 ... aluminum wiring layer (Al), 203 ... ITO layer, 204 ... cathode layer , 301 to 304: contact holes.

Claims (13)

In the circuit board for the light emitting element used for forming the light emitting element,
A group of extraction terminals in which extraction terminals to the outside are integrated on one side of the substrate;
A contact pattern for electrically connecting a part of the extraction terminals of the extraction terminal group and the common electrode between a region where the predetermined common electrode is disposed and the extraction terminal group. A circuit board for a light-emitting element.   The contact pattern is used to form a light emitting element that emits light by supplying a current, and electrically connects a part of the extraction terminal group and a common electrode through which the current of the light emitting element flows in common. The circuit board for light emitting elements of Claim 1 formed.   The circuit board for a light emitting element according to claim 2, wherein the light emitting element is an organic electroluminescent element. The contact pattern is
The circuit board for light emitting elements as described in any one of Claims 1 thru | or 3 provided with the area of 10% or more of the area of the said common electrode. The extraction terminal group is:
The circuit board for light emitting elements as described in any one of Claims 1 thru | or 3 with which the extraction terminal provided with the same shape is provided continuously. The common electrode that is formed is square,
4. The light-emitting element according to claim 1, further comprising: a scan driving circuit for supplying a scan signal to a scan wiring in a region facing the contact pattern via the common electrode. Circuit board.   7. A region for forming a signal driving circuit and / or a peripheral circuit for supplying an image signal to a signal wiring is provided in a region other than the peripheral region of the common electrode provided with the contact pattern and the scanning driving circuit. The circuit board for light emitting elements as described in 2.   6. The circuit board for a light-emitting element according to claim 5, wherein alignment marks are provided at four corners of a region where the common electrode where no circuit is provided is formed.   An electronic apparatus comprising the light-emitting element circuit board according to claim 1. A circuit board for a light emitting element according to any one of claims 1 to 8,
A plurality of light emitting elements provided corresponding to each pixel on the circuit board,
A display device that displays an image by controlling the light emitting element.   The display device according to claim 10, further comprising a transistor that controls driving of the light emitting element of the pixel corresponding to the light emitting element of the pixel.   The display device according to claim 11, wherein the light emitting element is a current control type light emitting element, and each pixel includes a control transistor and a driving transistor of the light emitting element.   The display device according to claim 11, wherein the light emitting element in each pixel includes a pixel electrode and a light emitting layer made of at least an organic light emitting material between the pixel electrode and the common electrode.

Images