JP5041627B2 - EL display device, electronic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic display (electro-optical device) formed by forming an EL (electroluminescence) element on a substrate. In particular, the present invention relates to a display device using a semiconductor element (an element using a semiconductor thin film). The present invention also relates to an electronic device using an EL display device for a display portion. The present invention also relates to an inspection method for an EL display device.
[0002]
Note that in this specification, an EL element refers to both an element that uses light emission (fluorescence) from a singlet exciton and an element that uses light emission (phosphorescence) from a triplet exciton.
[0003]
[Prior art]
In recent years, a technique for forming a thin film transistor (hereinafter referred to as TFT) on a substrate has greatly advanced, and application development to an active matrix display device has been advanced. In particular, a TFT using a polysilicon film has higher field effect mobility (also referred to as mobility) than a conventional TFT using an amorphous silicon film, and thus can operate at high speed. For this reason, it is possible to control a pixel, which has been conventionally performed by a drive circuit outside the substrate, with a drive circuit formed on the same substrate as the pixel.
[0004]
Such an active matrix display device has various advantages such as a reduction in manufacturing cost, a reduction in size of the display device, an increase in yield, and a reduction in throughput by forming various circuits and elements on the same substrate. .
[0005]
In addition, active matrix EL display devices having EL elements as self-luminous elements have been actively researched. The EL display device is also called an organic EL display (OELD) or an organic light emitting diode (OLED).
[0006]
Unlike a liquid crystal display device, an EL display device is a self-luminous type. An EL element has a structure in which an EL layer is sandwiched between a pair of electrodes (anode and cathode), and the EL layer usually has a laminated structure. A typical example is a “hole transport layer / light emitting layer / electron transport layer” stacked structure proposed by Tang et al. Of Kodak Eastman Company. This structure has very high luminous efficiency, and most EL display devices currently under research and development employ this structure.
[0007]
In addition, the hole injection layer / hole transport layer / light emitting layer / electron transport layer, or hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer are laminated in this order on the anode. Structure may be sufficient. You may dope a fluorescent pigment | dye etc. with respect to a light emitting layer.
[0008]
In this specification, all layers provided between the cathode and the anode are collectively referred to as an EL layer. Therefore, the above-described hole injection layer, hole transport layer, light emitting layer, electron transport layer, electron injection layer, and the like are all included in the EL layer.
[0009]
Then, a predetermined voltage is applied to the EL layer having the above structure from the pair of electrodes, whereby recombination of carriers occurs in the light emitting layer to emit light. Note that light emission of an EL element in this specification is referred to as driving of the EL element. In this specification, a light-emitting element formed using an anode, an EL layer, and a cathode is referred to as an EL element.
[0010]
As a driving method of the EL display device, an analog driving method (analog driving) can be given. Analog driving of the EL display device will be described with reference to FIGS.
[0011]
FIG. 10 shows a structure of a pixel portion of an analog drive EL display device. Gate signal lines (G1 to Gy) for inputting selection signals from the gate signal line driver circuit are connected to the gate electrode of the switching TFT 1801 included in each pixel. One of a source region and a drain region of the switching TFT 1801 included in each pixel is a source signal line (also referred to as a data signal line) (S1 to Sx) for inputting an analog video signal, and the other is a driving included in each pixel. The TFT 1804 is connected to a gate electrode and a capacitor 1808 included in each pixel.
[0012]
One of a source region and a drain region of the driving TFT 1804 included in each pixel is connected to a power supply line (V1 to Vx), and the other is connected to an EL element 1806. The potential of the power supply lines (V1 to Vx) is called a power supply potential. The power supply lines (V1 to Vx) are connected to a capacitor 1808 included in each pixel.
[0013]
The EL element 1806 includes an anode, a cathode, and an EL layer provided between the anode and the cathode. In the case where the anode of the EL element 1806 is connected to the source region or the drain region of the driving TFT 1804, the anode of the EL element 1806 serves as a pixel electrode and the cathode serves as a counter electrode. On the other hand, in the case where the cathode of the EL element 1806 is connected to the source region or the drain region of the driving TFT 1804, the anode of the EL element 1806 is a counter electrode and the cathode is a pixel electrode.
[0014]
Note that in this specification, the potential of the counter electrode is referred to as a counter potential. A power source that applies a counter potential to the counter electrode is referred to as a counter power source. A potential difference between the potential of the pixel electrode and the potential of the counter electrode is an EL drive voltage, and this EL drive voltage is applied to the EL layer.
[0015]
FIG. 11 shows a timing chart when the EL display device shown in FIG. 10 is driven in an analog manner. A period from when one gate signal line is selected to when another gate signal line is selected next is referred to as one line period (L). A period from when one image is displayed until the next image is displayed corresponds to one frame period (F). In the EL display device of FIG. 10, since there are y gate signal lines, y line periods (L1 to Ly) are provided in one frame period.
[0016]
As the resolution increases, the number of line periods in one frame period increases, and the drive circuit must be driven at a high frequency.
[0017]
First, the power supply lines (V1 to Vx) are kept at a constant power supply potential. The counter potential, which is the potential of the counter electrode, is also kept constant. The counter potential has a potential difference from the power supply potential to such an extent that the EL element 1806 emits light.
[0018]
In the first line period (L1), a selection signal from the gate signal line driver circuit is input to the gate signal line G1. Then, analog video signals are sequentially input to the source signal lines (S1 to Sx). Since all the switching TFTs 1801 connected to the gate signal line G1 are turned on, the analog video signal input to the source signal line is input to the gate electrode of the driving TFT 1804 via the switching TFT 1801. .
[0019]
Here, the switching TFT 1801 and the driving TFT 1804 will be described using timing charts in the case where both n-channel TFTs are used as an example. However, the switching TFT and the driving TFT may be n-channel TFTs or p-channel TFTs. But either is fine.
[0020]
Note that in this specification, when the TFT is turned on, the gate voltage of the TFT changes and the source and the drain are electrically connected.
[0021]
The amount of current flowing through the channel formation region of the driving TFT 1804 is controlled by the potential level (voltage) of the signal input to the gate electrode. Therefore, the potential applied to the pixel electrode of the EL element 1806 is determined by the height of the potential of the analog video signal input to the gate electrode of the driving TFT 1804. The EL element 1806 emits light by being controlled by the potential of the analog video signal.
[0022]
When the operation described above is repeated and the input of the analog video signal to the source signal lines (S1 to Sx) is finished, the first line period (L1) is finished. The period until the input of the analog video signal to the source signal lines (S1 to Sx) and the horizontal blanking period may be combined into one line period. Then, in the second line period (L2), a selection signal is input to the gate signal line G2. Similarly to the first line period (L1), analog video signals are sequentially input to the source signal lines (S1 to Sx).
[0023]
When selection signals are input to all the gate signal lines (G1 to Gy), all the line periods (L1 to Ly) are finished. When all the line periods (L1 to Ly) end, one frame period ends. All pixels display during one frame period, and one image is formed. All the line periods (L1 to Ly) and the vertical blanking period may be combined to form one frame period.
[0024]
As described above, the light emission amount of the EL element 1806 is controlled by the analog video signal, and gradation display is performed by controlling the light emission amount. This method is a so-called analog gradation driving method, and gradation display is performed by changing the potential of an analog video signal input to a source signal line.
[0025]
[Problems to be solved by the invention]
In the conventional EL display device, as shown in FIG. 10, the drain region of the driving TFT 1804 in the pixel portion is only connected to the EL element 1806.
[0026]
Here, pixel TFTs (switching TFTs and driving TFTs) and TFTs constituting a driving circuit (source signal line driving circuit and gate signal line driving circuit) are formed over a substrate having an insulating surface, and then EL The material is deposited, and the driving TFT and the EL element are electrically connected. In the present specification, a process before forming the EL material is referred to as a TFT process.
[0027]
Therefore, in the conventional display device, the drain region of the driving TFT is in an open state on the circuit before the EL material is deposited. Whether or not the pixel TFT operates normally can be determined only by depositing an EL material, completing a display device, and performing a lighting test. For this reason, even if a pixel TFT has an abnormality and cannot be displayed normally, it cannot be detected until the final process, and the process is wasted.
[0028]
As described above, in the conventional EL display device, the operation of the pixel TFT cannot be confirmed in the pre-process of forming the EL material, and an unnecessary manufacturing cost is generated.
[0029]
The present invention has been made in view of the above problems, and it is an object of the present invention to provide an active matrix EL display device in which operation of a pixel TFT can be confirmed before film formation of an EL material.
[0030]
[Means for Solving the Problems]
In order to solve the above problems, the inventor inspected whether there is no problem in the driving TFT and the switching TFT before forming the EL material, and the substrate having the problematic TFT. (Hereinafter, referred to as a defective product) was considered to reduce the waste of the production line by not proceeding to the EL material film forming process.
[0031]
The configuration of the EL display device of the present invention will be described below.
[0032]
According to the present invention,
In an EL display device having a plurality of source signal lines, a plurality of gate signal lines, a plurality of power supply lines, a plurality of switching thin film transistors, and a plurality of driving thin film transistors on an insulating substrate.
One end is connected to the drain region of the driving thin film transistor, and the other end is connected to the gate signal line.
An EL display device is provided in which the power supply line is drawn out of the insulating substrate through a switch.
[0033]
The switch is disposed for each of the plurality of power supply lines,
The EL display device may include a driving circuit that sequentially drives the switches on the insulating substrate.
[0034]
The EL display device may be characterized in that the driving circuit for sequentially driving the switches shares a part with the source signal line driving circuit.
[0035]
The inspection capacity may be an EL display device having a value of 0.05 pF to 1 pF.
[0036]
According to the present invention,
A plurality of source signal lines, a plurality of gate signal lines, a plurality of power supply lines, a plurality of switching thin film transistors, a plurality of driving thin film transistors, and a drain region of the driving thin film transistor are connected to an insulating substrate. In an inspection method for an EL display device having an inspection capacity,
A procedure for operating the driving thin film transistor and charging the inspection capacitor to a constant potential;
A procedure of setting the potential of the power supply line to a potential different from the inspection capacitance after turning off the driving thin film transistor;
There is provided an inspection method for an EL display device including a procedure for extracting charges charged in the inspection capacitor to the outside via the power supply line for each pixel and detecting a potential variation.
[0037]
A computer, a video camera, a head-mounted display, an image playback device, or a portable information terminal using the display device may be used.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
The structure of the EL display device of the present invention and the inspection method thereof will be described below.
[0039]
FIG. 1 shows a first embodiment of the present invention. FIG. 1 is a configuration diagram of a pixel portion of a display device of the present invention.
[0040]
The power supply lines V1 to Vx, source signal lines S1 to Sx, gate signal lines G1 to Gy, switching TFT 9102, driving TFT 9106, holding capacitor 9107, EL element 9105, and inspection capacitor 9108 are included.
[0041]
Note that the switching TFT 9102 has a double-gate structure; however, the switching TFT of the pixel of the display device of the present invention is not limited to the double-gate structure, and may have a single-gate structure or a multi-gate structure with a double gate or more. But it ’s okay.
[0042]
In addition, although the driving TFT 9106 has a single gate structure, the driving TFT of the pixel of the display device of the present invention may have a double gate structure or a multi-gate structure.
[0043]
Here, the drain region of the driving TFT 9106 is connected not only to the EL element 9105 but also to the inspection capacitor 9108. In this example, the inspection capacitor 9108 is inserted between the drain region of the driving TFT 9106 and the gate signal line, but the structure of the present invention is not limited to this. It may be between the drain region and another individual wiring.
[0044]
FIG. 2 is a block diagram of the display device of the present invention.
[0045]
Source signal line drive circuit 9201, gate signal line drive circuits 9202 and 9203, test drive circuit 9204, switches 9205 and 9206, source signal lines 9207 to 9209, gate signal lines 9210 to 9212, pixel portion power supply lines 9213 and 9214, A power supply line lead terminal 9215 and an external inspection circuit 9216 are included.
[0046]
In FIG. 2, a part of the source signal line, the gate signal line, the power supply line, and the switch are shown as representatives. Actually, these are formed by the amount corresponding to the pixels constituting the display device.
[0047]
Unlike the prior art, an inspection drive circuit 9204 is added. In addition, switches 9205 and 9206 controlled by the inspection drive circuit 9204 are inserted between the pixel portion power supply lines 9213 and 9214 and the power supply line lead terminal 9215 for each pixel portion power supply line. . The power supply line lead terminal is connected to the external inspection circuit 9216.
[0048]
The test drive circuit 9204 is arranged independently in FIG. 2, but when the source signal line drive circuit is of an analog type, both can be used together. (Not shown)
[0049]
Next, the inspection method used in the present invention will be described.
[0050]
In the description, reference is made to FIG. 1 and FIG.
[0051]
Here, it is assumed that the substrate is inspected at the stage before the formation of the EL material after the TFT process is completed, but the connection between the TFTs constituting the display device, capacitance (retention capacitance, inspection capacitance, etc.), resistance, etc. If is completed, it is not limited to the stage of this process.
[0052]
Here, although the EL element 9105 is shown in FIG. 1, the EL material is not yet formed and the EL element 9105 is not formed at the stage of the following inspection.
[0053]
First, as a first procedure, a voltage corresponding to a “Hi” signal, for example, 10 V, is applied to the power supply line. Next, each driver circuit (the source signal line driver circuit 9201 and the gate signal line driver circuits 9202 and 9203) is sequentially scanned, and the driving TFT 9106 is turned on in each pixel, so that the voltage 10 V of the power supply lines V1 to Vx is applied. Write to each inspection capacity 9108.
[0054]
It is assumed that the inspection capacitance takes a value of 0.05 pF to 1 pF.
[0055]
As a second procedure, the following is performed. The source signal line driver circuit 9201 and the gate signal line driver circuits 9202 and 9203 are operated to turn off all the driving TFTs 9106 in the pixel portion. Next, the potentials of the power supply lines V1 to Vx are set to a voltage corresponding to the “Lo” signal, for example, 0V. At this time, the switches 9205 and 9206 remain on.
[0056]
As a result, the power supply lines V1 to Vx of the pixel portion become 0V.
[0057]
The third procedure is as follows.
[0058]
The driving TFT 9106 for each pixel is operated at the timing as shown in FIG.
[0059]
The timing chart of FIG. 3 shows the case where the switching TFT is an n-channel TFT and the driving TFT is a p-channel TFT. However, the switching TFT and the driving TFT are both n-channel TFTs and n-channel TFTs. Either channel TFT may be used.
[0060]
The source signal lines S1 to Sx are sequentially operated. Here, the operations for the two source signal lines S1 and S2 are shown and described as representatives, but the same operations are performed for all the source signal lines S1 to Sx.
[0061]
In the pixel in which the “Lo” signal is input to the source signal line, when the “Hi” signal is sequentially input to the gate signal lines G1 to Gy, the driving TFT 9106 is turned on.
[0062]
Further, if all the power supply lines V1 to Vx are connected, the wiring capacity is too large and it becomes difficult to detect the voltage. Therefore, a switch connected to the power supply line is necessary for checking the operation of the pixel TFT individually for each pixel column.
[0063]
Here, one pixel column means a pixel having a switching TFT connected to the same source signal line.
[0064]
While the source signal line S1 is selected, the switch connected to the power supply line V1 that supplies power to the pixel having the switching TFT whose source region is connected to the source signal line S1 is turned on. Note that all the switches connected to the power supply lines V2 to Vx corresponding to the other pixels are in an off state.
[0065]
Next, while the source signal line S2 is selected, the switch connected to the power supply line V2 for supplying power to the pixel having the switching TFT whose source region is connected to the source signal line S2 is in the ON state. It becomes. Note that all the switches connected to the power supply lines V1, V3 to Vx corresponding to the other pixels are in an off state.
[0066]
Here, in FIG. 3, T1 and T2 indicate signals for turning on or off the switch connected to the power supply line V1 and the switch connected to the power supply line V2, respectively.
[0067]
In this embodiment, when a “Hi” signal is input to T1 and T2, a switch connected to the power supply line is turned on, and when a “Lo” signal is input, the switch Indicates a case of being turned off.
[0068]
In the pixel, when the driving TFT 9106 is turned on, the charges held in the inspection capacitor 9108 are discharged to the power supply lines V1 to Vx. Due to this discharge, a voltage is generated in the power supply lines V1 to Vx.
[0069]
This voltage is given as follows. Assuming that the wiring capacity value of the power supply line of the pixel portion is C1, the capacity up to the power supply line lead terminal 9215 is C2, and the inspection capacity is C3, the generated voltage _Vout is given by Equation 1.
[0070]
[Formula 1]
V _out = 10 × C3 / (C1 + C2 + C3)
[0071]
If C1 = C2 = 10 pF and C3 = 0.1 pF, the voltage _Vout is 0.05V.
[0072]
Since this voltage V _out is small, detection is performed by attaching an external inspection circuit 9216 to the power supply line lead-out terminal 9215.
[0073]
If there is a defect in the pixel TFT, charging or discharging cannot be performed, and thus the voltage V _out is not generated.
[0074]
In the timing chart shown in FIG. 3, the voltage V _out is generated at the power supply line lead terminal 9215 every time a pixel is selected. However, if there is an abnormality in the pixel TFT, a voltage signal is missing as in 9301. It can be seen that a defect has occurred.
[0075]
In this way, the pixel TFT can be inspected by sequentially selecting all the pixels.
[0076]
【Example】
Examples of the present invention will be described below.
[0077]
Example 1
In this embodiment, a configuration example of a test drive circuit for a display device of the present invention is shown.
[0078]
In FIG. 4, the test drive circuit is composed of a shift register 9402 composed of DFF 9401, NAND circuits 9403, 9404, 9405, and buffer circuits 9406, 9407, 9408 composed of inverters.
[0079]
In FIG. 4, only the portion corresponding to the three power supply lines of the test drive circuit is shown, but in reality, the test drive circuit is configured by circuits corresponding to all the power supply lines. I'm.
[0080]
The switches 9205, 9206, and the like shown in FIG. 2 are connected to the outputs 9409, 9410, and 9411 of the buffer circuit paths 9406, 9407, and 9408 to connect the pixel portion power supply line and the power supply line lead terminal.
[0081]
If a voltage of “Hi” is input to the input terminal 9400 of the shift register 9402, all the outputs of the terminals 9409 to 9411 become signals corresponding to “Hi”, and all the switches can be turned on.
[0082]
(Example 2)
In this embodiment, a configuration example of an external inspection circuit of the display device of the present invention is shown.
[0083]
In FIG. 5, the external inspection circuit 9501 includes a switch 9502 for switching connection, an amplifier 9505 for performing signal detection, a voltage source 9503, a resistor 9504, and the like.
[0084]
The switch 9502 has three inputs: a voltage corresponding to the “Hi” signal, a 10 V voltage source 9503, a voltage corresponding to the “Lo” signal, a 0 V voltage source 9508, or an amplifier 9505 that amplifies the signal. Terminal connection is selected.
[0085]
Note that the voltages of the voltage sources 9503 and 9508 are not limited to the above values, and can be optimized as necessary.
[0086]
The power supply line lead terminal of the substrate of the display device to be inspected is connected to the input 9507, and the inspection is performed according to the procedure shown in the embodiment mode. The determination of the inspection is performed by monitoring the output 9506 of the amplifier 9505.
[0087]
The amplifier 9505 used here has a voltage gain of about 10 to 1000 times, and amplifies and detects a detection signal generated in the power supply line. The gain of the amplifier is preferably about 100 times.
[0088]
This embodiment can be implemented by freely combining with the first embodiment.
[0089]
(Example 3)
In the present invention, the driving TFT 108 can be either an n-channel TFT or a p-channel TFT. However, when the anode of the EL element 110 is a pixel electrode and the cathode is a counter electrode, the driving TFT 108 is a p-channel TFT. A type TFT is preferable. Conversely, when the anode of the EL element 110 is a counter electrode and the cathode is a pixel electrode, the driving TFT 108 is preferably an n-channel TFT.
[0090]
This embodiment can be implemented by freely combining with any of Embodiments 1 and 2.
[0091]
Example 4
In this embodiment, an example in which an EL display device is manufactured using the present invention will be described.
[0092]
FIG. 6A is a top view of an EL display device using the present invention. 6A, reference numeral 4010 denotes a substrate, 4011 denotes a pixel portion, 4012 denotes a source signal line driver circuit, 4013a and 4013b denote gate signal line driver circuits, and each driver circuit includes wirings 4014a, 4014b, 4015, and 4016. Then, it reaches the FPC 4017 and is connected to an external device.
[0093]
Note that in this embodiment, an example in which the test drive circuit is shared by the source signal line drive circuit 4012 is shown, but the present invention is not limited to this configuration. A test drive circuit may be provided separately from the source signal line drive circuit.
[0094]
Here, a cover material 6000, a sealing material (also referred to as a housing material) 7000, and a sealing material (second sealing material) 7001 are provided so as to surround at least the pixel portion, preferably the drive circuit and the pixel portion.
[0095]
FIG. 6B shows a cross-sectional structure of the EL display device of this embodiment. A driver circuit TFT (here, an n-channel TFT and a p-channel TFT are provided over a substrate 4010 and a base film 4021. A combined CMOS circuit is shown.) 4022 and a pixel portion TFT 4023 (however, only a driving TFT for controlling a current to an EL element is shown here) are formed. These TFTs may have a known structure (top gate structure or bottom gate structure).
[0096]
In FIG. 6B, the inspection capacitor connected to the drain electrode of the driving TFT is not shown.
[0097]
When the driving circuit TFT 4022 and the pixel portion TFT 4023 are completed, a pixel electrode 4027 made of a transparent conductive film electrically connected to the drain of the pixel portion TFT 4023 is formed on an interlayer insulating film (planarization film) 4026 made of a resin material. Form. As the transparent conductive film, a compound of indium oxide and tin oxide (referred to as ITO) or a compound of indium oxide and zinc oxide can be used. Then, after the pixel electrode 4027 is formed, an insulating film 4028 is formed, and an opening is formed over the pixel electrode 4027.
[0098]
Next, an EL layer 4029 is formed. The EL layer 4029 may have a stacked structure or a single-layer structure by freely combining known EL materials (a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, or an electron injection layer). A known technique may be used to determine the structure. The EL material includes a low molecular material and a high molecular (polymer) material. When a low molecular material is used, a vapor deposition method is used. When a high molecular material is used, a simple method such as a spin coating method, a printing method, or an ink jet method can be used.
[0099]
In this embodiment, the EL layer 4029 is formed by a vapor deposition method using a shadow mask. Color display is possible by forming a light emitting layer (a red light emitting layer, a green light emitting layer, and a blue light emitting layer) capable of emitting light having different wavelengths for each pixel using a shadow mask. In addition, there are a method in which a color conversion layer (CCM) and a color filter are combined, and a method in which a white light emitting layer and a color filter are combined, but either method may be used. Needless to say, an EL display device emitting monochromatic light can also be used.
[0100]
After the EL layer 4029 is formed, a cathode 4030 is formed thereon. It is desirable to remove moisture and oxygen present at the interface between the cathode 4030 and the EL layer 4029 as much as possible. Therefore, it is necessary to devise such that the EL layer 4029 and the cathode 4030 are continuously formed in a vacuum, or the EL layer 4029 is formed in an inert atmosphere and the cathode 4030 is formed without being released to the atmosphere. In this embodiment, the above-described film formation is possible by using a multi-chamber type (cluster tool type) film formation apparatus.
[0101]
In this embodiment, a stacked structure of a LiF (lithium fluoride) film and an Al (aluminum) film is used as the cathode 4030. Specifically, a 1 nm-thick LiF (lithium fluoride) film is formed on the EL layer 4029 by evaporation, and a 300 nm-thick aluminum film is formed thereon. Of course, you may use the MgAg electrode which is a well-known cathode material. The cathode 4030 is connected to the wiring 4016 in the region indicated by 4031. A wiring 4016 is a power supply line for applying a predetermined voltage to the cathode 4030 and is connected to the FPC 4017 through a conductive paste material 4032.
[0102]
In order to electrically connect the cathode 4030 and the wiring 4016 in the region indicated by 4031, it is necessary to form contact holes in the interlayer insulating film 4026 and the insulating film 4028. These may be formed when the interlayer insulating film 4026 is etched (when the pixel electrode contact hole is formed) or when the insulating film 4028 is etched (when the opening before the EL layer is formed). In addition, when the insulating film 4028 is etched, the interlayer insulating film 4026 may be etched all at once. In this case, if the interlayer insulating film 4026 and the insulating film 4028 are the same resin material, the shape of the contact hole can be improved.
[0103]
A passivation film 6003, a filler 6004, and a cover material 6000 are formed so as to cover the surface of the EL element thus formed.
[0104]
Further, a sealing material 7000 is provided inside the cover material 6000 and the substrate 4010 so as to surround the EL element portion, and a sealing material (second sealing material) 7001 is formed outside the sealing material 7000.
[0105]
At this time, the filler 6004 also functions as an adhesive for bonding the cover material 6000. As the filler 6004, PVC (polyvinyl chloride), epoxy resin, silicone resin, PVB (polyvinyl butyral) or EVA (ethylene vinyl acetate) can be used. It is preferable to provide a desiccant inside the filler 6004 because the moisture absorption effect can be maintained.
[0106]
In addition, a spacer may be included in the filler 6004. At this time, the spacer may be a granular material made of BaO or the like, and the spacer itself may be hygroscopic.
[0107]
In the case where a spacer is provided, the passivation film 6003 can relieve the spacer pressure. In addition to the passivation film 6003, a resin film for relaxing the spacer pressure may be provided.
[0108]
As the cover material 6000, a glass plate, an aluminum plate, a stainless steel plate, an FRP (Fiberglass-Reinforced Plastics) plate, a PVF (polyvinyl fluoride) film, a mylar film, a polyester film, or an acrylic film can be used. Note that when PVB or EVA is used as the filler 6004, it is preferable to use a sheet having a structure in which an aluminum foil of several tens of μm is sandwiched between PVF films or Mylar films.
[0109]
However, the cover material 6000 needs to have translucency depending on the light emission direction (light emission direction) from the EL element.
[0110]
The wiring 4016 is electrically connected to the FPC 4017 through a gap between the sealing material 7000 and the sealing material 7001 and the substrate 4010. Note that although the wiring 4016 has been described here, the other wirings 4014a, 4014b, and 4015 are also electrically connected to the FPC 4017 through the gap between the sealing material 7000 and the sealing material 7001 and the substrate 4010.
[0111]
In this embodiment, the filler material 6004 is provided and then the cover material 6000 is bonded, and the sealing material 7000 is attached so as to cover the side surface (exposed surface) of the filler material 6004. However, the cover material 6000 and the sealing material 7000 are attached. The filler 6004 may be provided after the attachment. In this case, a filler inlet that leads to a gap formed by the substrate 4010, the cover material 6000, and the sealing material 7000 is provided. Then, the space is evacuated (10 ⁻² Torr or less), the inlet is immersed in a water tank containing the filler, and the pressure outside the space is made higher than the pressure in the space, Fill in the void.
[0112]
This embodiment can be implemented by freely combining with any of Embodiments 1 to 3.
[0113]
(Example 5)
In the present embodiment, the configuration of the source signal side driver circuit when the driving is not the analog gradation described in the conventional example but the digital time gradation will be described.
[0114]
FIG. 7 is a circuit diagram showing an example of a source signal side driving circuit used in this embodiment.
[0115]
In the present invention, the driving method can be applied to any of analog gradation, digital time gradation, digital area gradation, and the like. Further, a method combining these gradation methods is also possible.
[0116]
In FIG. 7, a shift register 801, latches (A) (802), and latches (B) (803) are arranged as shown.
[0117]
In this embodiment, one set of latches (A) (802) and one set of latches (B) (803) correspond to outputs to the four source signal lines S_a to S_d. Therefore, there are four input lines VD for digital video signals input from the outside, and signals input to the source signal lines S_a to S_d are respectively input.
[0118]
In this embodiment, the level shifter for changing the amplitude range of the voltage of the signal is not provided. However, the designer may appropriately provide it.
[0119]
The clock signal CLKB, the clock signal CLKB in which the polarity of the CLK is inverted, the start pulse signal SP, and the drive direction switching signal SL / R are input to the shift register 801 from the wirings shown in the drawing, respectively. The digital data signal VD input from the outside is input to the latch (A) (802) from the wiring shown in the figure. The signals S_LATb in which the polarities of the latch signals S_LAT and S_LAT are inverted are respectively input to the latches (B) (803) from the wirings shown in the drawing.
[0120]
A detailed configuration of the latches (A) and (802) will be described using a part 804 of the latches (A) and (802) corresponding to the source signal line S_a as an example. A part 804 of the latch (A) (802) includes two clocked inverters and two inverters.
[0121]
A top view of a portion 804 of the latch (A) (802) is shown in FIG. Reference numerals 831a and 831b denote active layers of TFTs forming one of the inverters included in a part 804 of the latch (A) (802), respectively. Reference numeral 836 denotes a common gate electrode of the TFTs forming one of the inverters. is there. 832a and 832b are active layers of TFTs forming another inverter included in a part 804 of the latch (A) (802), and 837a and 837b are gates provided on the active layers 832a and 832b, respectively. Electrode. Note that the gate electrodes 837a and 837b are electrically connected.
[0122]
Reference numerals 833a and 833b denote active layers of TFTs that form one of the clocked inverters included in the part 804 of the latch (A) (802). Gate electrodes 838a and 838b are provided on the active layer 833a to form a double gate structure. Gate electrodes 838b and 839 are provided on the active layer 833b to form a double gate structure.
[0123]
Reference numerals 834a and 834b denote active layers of TFTs that form another clocked inverter included in the portion 804 of the latch (A) (802). Gate electrodes 839 and 840 are provided on the active layer 834a to form a double gate structure. Further, gate electrodes 840 and 841 are provided on the active layer 834b to form a double gate structure.
[0124]
This embodiment can be implemented in combination with any of Embodiments 1 to 4.
[0125]
(Example 6)
In the EL display device of the present invention, the material used for the EL layer of the EL element is not limited to the organic EL material, and the present invention can also be implemented using an inorganic EL material. However, since the current inorganic EL material has a very high driving voltage, a TFT having a withstand voltage characteristic that can withstand such a driving voltage must be used.
[0126]
Alternatively, if an inorganic EL material with a lower driving voltage is developed in the future, it can be applied to the present invention.
[0127]
This embodiment can be implemented by freely combining with any of Embodiments 1 to 5.
[0128]
(Example 7)
An electronic display formed using the present invention, particularly an EL display device, can be used for various electronic devices. Hereinafter, an electronic device incorporating an electronic display formed using the present invention as a display medium will be described.
[0129]
Such electronic devices include video cameras, television receivers, digital cameras, head mounted displays (goggles type displays), game consoles, telephones, car navigation systems, personal computers, image playback devices, and portable information terminals (mobile computers, mobile phones). Phone or electronic book). An example of them is shown in FIG.
[0130]
FIG. 9A illustrates a personal computer, which includes a main body 2001, a housing 2002, a display portion 2003, a keyboard 2004, and the like. The EL display device of the present invention can be used for the display portion 2003 of a personal computer.
[0131]
FIG. 9B shows a video camera, which includes a main body 2101, a display portion 2102, an audio input portion 2103, operation switches 2104, a battery 2105, an image receiving portion 2106, and the like. The EL display device of the present invention can be used for the display portion 2102 of the video camera.
[0132]
FIG. 9C illustrates a part (right side) of the head mounted display, which includes a main body 2301, a signal cable 2302, a head fixing band 2303, a display monitor 2304, an optical system 2305, a display unit 2306, and the like. The EL display device of the present invention can be used for the display unit 2306 of the head mounted display.
[0133]
FIG. 9D shows an image reproducing device (specifically, a DVD reproducing device) provided with a recording medium, which includes a main body 2401, a recording medium (CD, LD, DVD, etc.) 2402, an operation switch 2403, and a display unit (a). 2404, a display portion (b) 2405, and the like. The display unit (a) mainly displays image information, and the display unit (b) mainly displays character information. The EL display device of the present invention is a display unit (a), ( It can be used for b). Note that the present invention can be used for a CD playback device, a game machine, or the like as an image playback device including a recording medium.
[0134]
FIG. 9E illustrates a portable (mobile) computer, which includes a main body 2501, a camera portion 2502, an image receiving portion 2503, operation switches 2504, a display portion 2505, and the like. The EL display device of the present invention can be used for the display portion 2505 of a portable (mobile) computer.
[0135]
Further, if the emission luminance of the EL material is increased in the future, it can be used for a front type or rear type projector.
[0136]
The electronic apparatus according to the present embodiment can be realized by using a configuration including any combination of the first to sixth embodiments.
[0137]
(Example 8)
FIG. 12 shows an example in which an EL display device is used in a mobile phone.
[0138]
The cellular phone includes a housing A 1201, a housing B 1202, and an antenna 1205. A display portion 1200 and a microphone 1209 are formed on a surface A 1203 of the housing A 1201, and a speaker 1206 is formed on a surface B 1204 of the housing B 1202. An operation key 1207, a power switch 1208, and the like are formed.
[0139]
The EL display device of the present invention can be used for a display portion 1200 of a mobile phone.
[0140]
Note that the speaker 1206, the operation key 1207, the display portion 1200, the microphone 1209, and the power switch 1208 are not limited to the above arrangement, and can be formed in any portion of the housing A 1201 and the housing B 1202.
[0141]
In FIG. 12, the mobile phone is composed of two housing parts (housing A 1201 and housing B 1202), and one side thereof is connected by a hinge (not shown). By closing the hinge, the surface A1203 of the housing A1201 and the surface B1204 of the housing B1202 can overlap each other. Note that the surface A1203 of the housing A1201 and the surface B1204 of the housing B1202 are overlapped.
[0142]
Further, in this example of the mobile phone, the usage as shown in FIG. 13 is possible. That is, the speaker 1206 and the microphone 1209 are arranged in different housing parts, and the speaker 1206 is placed near the ear 1211 and the microphone 1209 is placed in the mouth 1212 by changing the angle between the surface A1203 and the surface B1204. Is possible. With such a configuration, there is an advantage that another person cannot see the mouth 1212 during a call. In addition, since the mouth 1212 and the microphone 1209 are close to each other, there is an effect that the influence of noise is reduced, a good call can be made, and noise filters in the telephone can be reduced. Further, if the number of operation keys 1207 is increased, it can be used as a portable information terminal.
[0143]
As described above, the application range of the present invention is extremely wide and can be applied to electronic devices in various fields. Moreover, the electronic device of a present Example is realizable even if it uses the structure which consists of what combination of Examples 1-6.
[0144]
【Effect of the invention】
With the above structure, a display device capable of inspecting the pixel portion TFT before forming the EL layer can be provided. Thereby, defective products can be removed before film formation of the EL material, and the manufacturing cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a circuit configuration of a pixel portion of a display device of the present invention.
FIG. 2 is a block diagram of a display device of the present invention.
FIG. 3 is a timing chart showing a method for driving a display device of the present invention.
FIG. 4 is a diagram showing an embodiment of a test drive circuit for a display device of the present invention.
FIG. 5 is a diagram showing an embodiment of an external inspection circuit for a display device of the present invention.
6A and 6B are a top view and a cross-sectional view of a display device of the present invention.
FIG. 7 is a circuit diagram of a source signal side driver circuit of a display device according to the present invention.
FIG. 8 is a top view of a latch of a display device according to the present invention.
FIG 9 is a diagram showing an electronic device using the display device of the invention.
FIG. 10 is a circuit diagram of a pixel portion of a conventional display device.
FIG. 11 is a timing chart showing an analog driving method of a display device.
FIG. 12 is a diagram showing a mobile phone using the present invention.
FIG. 13 is a diagram showing a method of using a cellular phone using the present invention.

Claims (6)

Each pixel has a pixel electrode included in the first transistor, the second transistor , the first capacitor, and the EL element .
In the first transistor , the gate is electrically connected to the gate line, one of the source and the drain is electrically connected to the source line, and the other of the source and the drain is electrically connected to the gate of the second transistor. Connected,
In the second transistor , one of a source and a drain is electrically connected to the pixel electrode and one end of the first capacitor, and the other of the source and the drain is electrically connected to a power supply line.
The other end of the first volume, EL display devices, characterized in that it is electrically connected to the wiring. Each pixel has a pixel electrode included in the first transistor, the second transistor, the first capacitor, and the EL element.
In the first transistor, the gate is electrically connected to the gate line, one of the source and the drain is electrically connected to the source line, and the other of the source and the drain is electrically connected to the gate of the second transistor. Connected,
In the second transistor, one of a source and a drain is electrically connected to the pixel electrode and one end of the first capacitor, and the other of the source and the drain is electrically connected to a power supply line.
The other end of the first capacitor is electrically connected to the wiring;
The EL display device is characterized in that the first transistor has a double gate structure. Each pixel has a pixel electrode included in the first transistor, the second transistor, the first capacitor, and the EL element.
In the first transistor, the gate is electrically connected to the gate line, one of the source and the drain is electrically connected to the source line, and the other of the source and the drain is electrically connected to the gate of the second transistor. Connected,
In the second transistor, one of a source and a drain is electrically connected to the pixel electrode and one end of the first capacitor, and the other of the source and the drain is electrically connected to a power supply line.
The other end of the first capacitor is electrically connected to the wiring;
The EL display device is characterized in that the first transistor has a multi-gate structure. In any one of Claims 1 thru | or 3,
The EL display device, wherein the first transistor is an n-channel TFT and the second transistor is a p-channel TFT. In any one of Claims 1 thru | or 3,
2. The EL display device according to claim 1, wherein the first transistor is an n-channel TFT, and the second transistor is an n-channel TFT. An electronic apparatus using the EL display device according to any one of claims 1 to 5 .

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