JP4689188B2 - Display device - Google Patents

Description

  The present invention relates to an active matrix display device, and more particularly to a wiring structure of an active matrix display device including a light emitting element.

  In recent years, a large electroluminescence (hereinafter abbreviated as EL) display device has been developed for the purpose of entering the television market.

  Here, when the wiring length increases with the increase in the size of the display device, there is a problem that a voltage drop occurs. When a voltage drop occurs, the voltage applied to the EL element changes from place to place, causing a problem of display unevenness.

  In order to solve the above problem, when the thickness of the wiring is increased, a great burden is imposed on processes such as film formation and etching. In addition, when the line width of the wiring is increased, the area ratio of the wiring on the substrate is increased, and it is difficult to manufacture a high-definition display device.

  In addition, when the display device is increased in size, particularly in an active matrix display device, the characteristic variation in the substrate surface of a thin film transistor (hereinafter referred to as TFT) for transmitting an electrical signal to an EL element increases. , Which causes display unevenness.

  Attempts to reduce display unevenness due to variations in TFT characteristics have been made mainly by devising a circuit configuration for driving EL elements (for example, Patent Document 1). However, by providing a circuit for compensating for the characteristic variation of the TFT, there arises a problem that the occupancy ratio of the circuit in the substrate surface increases and the aperture ratio of the pixel portion decreases.

  As described above, it is difficult to achieve both high definition of the display device and suppression of display unevenness due to voltage drop in wiring or variation in TFT characteristics.

JP 2003-5710 A

  In view of the above problems, an object of the present invention is to provide a high-definition display device that can suppress display unevenness due to a voltage drop in a wiring. It is another object of the present invention to provide a display device that suppresses display unevenness due to variations in TFT characteristics and enables high-definition display.

  The display device of the present invention includes a first wiring for transmitting a video signal and a second wiring for supplying a current to the light emitting element, and the first wiring and the second wiring Are parallel to each other, and are characterized by being formed so that at least a part thereof overlaps with an insulating film interposed therebetween. Note that the light-emitting element has a structure in which a light-emitting layer is sandwiched between a pair of electrodes.

  The first wiring may overlap so as to be an upper layer than the second wiring, or the first wiring may overlap so as to be a lower layer than the second wiring.

  The first wiring and the second wiring do not necessarily have to overlap all the regions, and only a part thereof may overlap.

  Note that the electrode of the light-emitting element may be formed in the same layer as the upper wiring of the first wiring or the second wiring. By adopting such a configuration, when forming the pixel electrode (the electrode on the side connected to the circuit for transmitting a signal to the light emitting element among the electrodes of the pair of light emitting elements), a new insulation is formed. There is no need to provide a film, and processes such as a film formation process and contact hole opening are simplified.

  With the above configuration, when the line width of the second wiring is increased to suppress the voltage drop, the upper part or the lower part of the surface occupied by the first wiring is effectively utilized. The line width can be increased. Therefore, a decrease in the aperture ratio due to the increase in the line width of the second wiring can be suppressed as low as possible. In addition, since the first wiring and the second wiring are formed using different layers, a short circuit generated between the first wiring and the second wiring can be reduced.

  The display device of the present invention includes a first wiring for transmitting a video signal, a second wiring for supplying a current to the light emitting element, and the first wiring and the second wiring in parallel. The first wiring and the second wiring are formed in the same layer, and the third wiring includes the first wiring and the second wiring. The first wiring or the second wiring is formed so as to at least partially overlap the upper layer or the lower layer of the wiring with an insulating film interposed therebetween, and the second wiring and the third wiring Is characterized by being connected.

  The first and second wirings may overlap so as to be an upper layer than the third wiring, or the first and second wirings may overlap so as to be a lower layer than the third wiring. Good.

  Note that the electrode of the light-emitting element may be formed in the same layer as the upper wiring of the first wiring or the third wiring. With such a configuration, it is not necessary to provide a new insulating film when forming the pixel electrode, and processes such as a film forming process and contact hole opening are simplified.

  As described above, by providing the third wiring at least partially overlapping with the first or second wiring, the upper part or the lower part of the surface occupied by the first or second wiring is effectively used. It is possible to suppress the voltage drop of the second wiring while being utilized.

  The display device of the present invention extends in parallel with a first wiring for transmitting a video signal, a second wiring for supplying a current to the light emitting element, and the first wiring and the second wiring. A third wiring, and the first wiring and the second wiring are formed so as to overlap at least partially with an insulating film interposed therebetween, and the third wiring is insulated It is formed so that at least a part of one of the first and second wirings overlaps with the film interposed therebetween, and the second wiring and the third wiring are connected. It is a feature.

  The first wiring may overlap so as to be an upper layer than the second wiring, or the first wiring may overlap so as to be a lower layer than the second wiring.

  In addition, the first wiring and the second wiring do not necessarily have to overlap all the regions, and only a part thereof may overlap.

  The third wiring may overlap so as to be an upper layer than the first wiring, or may overlap so as to be a lower layer than the first wiring. Further, they may overlap so as to be an upper layer than the second wiring, or may overlap so as to be a lower layer than the second wiring.

  Note that the electrode of the light-emitting element may be formed in the same layer as the wiring formed in the uppermost layer of the first wiring, the second wiring, or the third wiring. With such a configuration, it is not necessary to provide a new insulating film when forming the pixel electrode, and processes such as a film forming process and contact hole opening are simplified.

  With the above configuration, a voltage drop generated in the second wiring can be further reduced.

  As described above, by applying the present invention, display unevenness due to a voltage drop in a wiring for supplying current to a light-emitting element can be suppressed, and a display device with high image quality and high definition can be manufactured.

  Another configuration of the present invention includes a light emitting element, a first transistor for determining a current value flowing through the light emitting element, a second transistor for determining light emission / non-light emission of the light emitting element according to a video signal, A third transistor that controls input of the video signal, a fourth transistor that turns off the light emitting element regardless of the video signal, and a third transistor that is connected to the third transistor to transmit the video signal A first wiring for connecting to the second transistor, a second wiring for supplying a current to the light emitting element through the first and second transistors, and the first transistor A third wiring connected to the gate electrode of the first wiring, the first wiring, the second wiring, and the third wiring extending in parallel with each other, and the first wiring and the third wiring What is the third wiring? Further, the first wiring, the third wiring, and the second wiring are formed so as to overlap at least partially with an insulating film interposed therebetween. It is a display device.

  With the above structure, display unevenness due to TFT characteristic variation can be suppressed, and display unevenness due to voltage drop of a wiring for supplying current to the light emitting element can be suppressed.

  According to the present invention, it is possible to obtain a high-quality and high-definition display device in which display unevenness due to a voltage drop in a wiring is reduced. In addition, it is possible to obtain a high-quality and high-definition display device in which both display unevenness due to voltage drop in the wiring and display unevenness due to transistor characteristic variation are reduced.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. However, the present invention can be implemented in many different modes, and those skilled in the art can easily understand that the modes and details can be variously changed without departing from the spirit and scope of the present invention. Is done. Therefore, the present invention is not construed as being limited to the description of this embodiment mode.
(Embodiment 1)
One embodiment of the present invention will be described with reference to FIG.

  FIG. 1 is a top view of a pixel portion of a display device to which the present invention is applied. FIG. 9 is a cross-sectional view taken along line A-A ′ of FIG. 1.

  In FIG. 1, source signal lines 101 (101a and 101b) are provided as wirings for transmitting video signals, and current supply lines 104 (104a and 104b) are provided as wirings for supplying current to the light emitting elements. The source signal line 101 and the current supply line 104 are formed on different layers with an insulating film interposed therebetween. They extend parallel to each other. Note that in this embodiment mode, the entire source signal line 101 and the current supply line 104 overlap, but a part of the source signal line 101 and a part of the current supply line 104 overlap. May be. In any case, the line width of the current supply line 104 can be increased by utilizing the upper part of the source signal line. In this embodiment mode, the current supply line 104 is provided in an upper layer than the source signal line 101. However, the present invention is not limited to this, and the current supply line may be provided in a lower layer than the source signal line. Good.

  In addition to the source signal line 101 and the current supply line 104, the pixel portion includes a driving TFT 110 that determines light emission / non-light emission of the light emitting element based on a video signal, and a switching TFT 111 that controls input of the video signal. An erasing TFT 112 is provided to bring the light emitting element into a non-light emitting state regardless of the video signal.

  In this embodiment mode, the current supply line 104 is connected to the driving TFT 110 through the conductive film 120 (120a, 120b) provided in the same layer as the source signal line 101. A part of the first gate signal line 102 functions as a gate electrode of the switching TFT 111. In addition, part of the second gate signal line 103 (103a, 103b) functions as a gate electrode of the erasing TFT 112. Further, the driving TFT 110 is connected to the first electrode 130 (130a, 130b, 130c) of the light emitting element through the conductive film 121 (121a, 121b) provided in the same layer as the source signal line 101. Although not shown in FIG. 1, a partition layer provided with an opening so as to expose the first electrode 130 of the light emitting element, an electroluminescent layer, and a second electrode of the light emitting element are formed. A portion where the first electrode 130 of the light-emitting element, the electroluminescent layer, and the second electrode of the light-emitting element are stacked functions as a light-emitting element.

  In FIG. 9, 51 is a current supply line, 52 is a source signal line, 53 is a first electrode of a light emitting element, 54 is a light emitting element, 55 is a semiconductor layer, 56 is a gate electrode, 57 is a partition layer, and 58 and 59 are An insulating film, 60 is a protective film, and 61 is a second electrode of the light emitting element.

  The circuit configuration of the pixel portion described in this embodiment is as shown in the circuit diagram of FIG. In this embodiment, the driving TFT 210, the switching TFT 211, and the erasing TFT 212 are provided. However, the present invention is not limited to this, and, for example, a circuit including only the driving TFT 210 and the switching TFT 211. It is good also as a structure, and it is good also as a circuit structure which provided TFT or wiring other than the above. In any case, the circuit configuration is not limited to that shown in this embodiment.

  In this embodiment, a thin film transistor (TFT) is used. However, the present invention is not limited to this. For example, a transistor formed using a bulk silicon wafer or SOI (Silicon On Insulator) may be used. The transistor structure may be a single gate structure or a multi-gate structure including a plurality of gates. Further, a top gate type structure or a bottom gate type structure may be used.

  By applying the present invention, the line width of the current supply line can be increased and the voltage drop of the current supply line can be suppressed while effectively utilizing the upper part or the lower part of the surface occupied by the source signal line. . Therefore, particularly in a bottom emission type or a dual emission type display device, a decrease in aperture ratio due to an increase in the line width of the current supply line can be minimized. As a result, a display device capable of high-definition display with little display unevenness due to voltage drop can be manufactured. In addition, since the source signal line and the current supply line are formed using different layers, a short circuit between the source signal line and the current supply line can be reduced, and a display device with high image quality can be manufactured. In addition, the yield of display device manufacturing is improved.

(Embodiment 2)
One embodiment of the present invention is described with reference to FIGS.

  FIG. 3 is a top view of a pixel portion of a display device to which the present invention is applied. FIG. 10 is a cross-sectional view taken along line A-A ′ of FIG. 3.

  In FIG. 3, source signal lines 301 (301a and 301b) are provided as wirings for transmitting video signals, and current supply lines 304 (304a and 304b) are provided as wirings for supplying current to the light emitting elements. The source signal line 301 and the current supply line 304 are formed in the same layer and extend in parallel to each other. Further, a wiring 305 extending in parallel with the source signal line 301 or the current supply line 304 is formed on the source signal line 301 and the current supply line 304 with an insulating film interposed therebetween. The wiring 305 and the current supply line 304 are connected via a connection hole. Note that in this embodiment, part of the source signal line 301 and the entire current supply line 304 overlap with the wiring 305. However, the present invention is not limited to this, and a structure in which a part of the source signal line and a part of the current supply line overlap with the wiring may be used, or the entire source signal line and the entire current supply line may be connected to the wiring. The structure which overlaps with may be sufficient. In any case, by using the upper part of the current supply line 304 and providing the wiring 305 connected to the current supply line 304, the voltage drop of the current supply line 304 can be suppressed. In this embodiment mode, the wiring 305 is provided above the source signal line 301 and the current supply line 304. However, the present invention is not limited to this, and the wiring 305 is formed from the source signal line 301 and the current supply line 304. Also, a structure provided in the lower layer may be used.

  In addition to the source signal line 301 and the current supply line 304, the pixel portion includes a driving TFT 310 that determines light emission / non-light emission of the light emitting element according to a video signal, and a switching TFT 311 that controls input of the video signal. An erasing TFT 312 is provided to bring the light emitting element into a non-light emitting state regardless of the video signal.

  In FIG. 10, 30 is a current supply line, 31 is a wiring, 32 is a source signal line, 33 is a first electrode of a light emitting element, 34 is a light emitting element, 35 is a semiconductor layer, 36 is a gate electrode, 37 is a partition layer, Reference numerals 38 and 39 denote insulating films, reference numeral 40 denotes a protective film, and reference numeral 41 denotes a second electrode of the light emitting element.

  In this embodiment mode, part of the first gate signal line 102 functions as a gate electrode of the switching TFT 311. Further, part of the second gate signal line 303 functions as a gate electrode of the erasing TFT 312. Further, the driving TFT 310 is connected to the first electrode 330 (330a, 330b, 330c) of the light-emitting element through a conductive film 321 (321a, 321b) provided in the same layer as the source signal line 301. Although not shown in FIG. 1, a partition layer provided with an opening so as to expose the first electrode 330 of the light emitting element, an electroluminescent layer, and a second electrode of the light emitting element are formed. A portion where the first electrode 330 of the light emitting element, the electroluminescent layer, and the second electrode of the light emitting element are stacked functions as a light emitting element.

  The circuit configuration of the pixel portion described in this embodiment is as shown in the circuit diagram of FIG. In this embodiment, the driving TFT 210, the switching TFT 211, and the erasing TFT 212 are provided. However, the present invention is not limited to this, and, for example, a circuit including only the driving TFT 210 and the switching TFT 211. It is good also as a structure, and it is good also as a circuit structure which provided TFT or wiring other than the above. In any case, the circuit configuration is not limited to that shown in this embodiment.

  In this embodiment, a thin film transistor (TFT) is used. However, the present invention is not limited to this. For example, a transistor formed using a bulk silicon wafer or SOI (Silicon On Insulator) may be used. The transistor structure may be a single gate structure or a multi-gate structure including a plurality of gates. Further, a top gate type structure or a bottom gate type structure may be used.

  By applying the present invention, the line width of the current supply line can be increased and the voltage drop of the current supply line can be suppressed while effectively utilizing the upper part or the lower part of the surface occupied by the source signal line. . Therefore, particularly in a bottom emission type or a dual emission type display device, a decrease in aperture ratio due to an increase in the line width of the current supply line can be minimized. As a result, a display device capable of high-definition display with little display unevenness due to voltage drop can be manufactured.

(Embodiment 3)
In the display device described in Embodiment 1 or 2, the current supply line 104 or the wiring 305 and the first electrode 130 or 330 of the light-emitting element are provided in the same layer.

  However, the present invention is not limited to this, and the first electrodes 130 and 330 of the light-emitting element may be provided above the current supply line 104 or the wiring 305 with an insulating film interposed therebetween. With such a structure, particularly in a top-emission display device, the degree of freedom in designing the opening is increased and the aperture ratio is improved.

  Further, in the manufacturing process of the display device, a planarization process after forming a transparent conductive film for forming the first electrodes 130 and 330 of the light emitting element may be facilitated.

  In this embodiment, a structure and a driving method of a pixel portion of a display device to which the present invention is applied will be described.

  In FIG. 4, source signal lines 701 (701a and 701b) are provided as lines for transmitting video signals, and current supply lines 704 (704a and 704b) are provided as lines for supplying current to the light emitting elements. The source signal line 701 and the current supply line 704 are formed on different layers with an insulating film interposed therebetween. They extend parallel to each other. Further, a power supply line 705 extending in parallel with the source signal line 701 is provided in the same layer as the source signal line 701. The entire source signal line 701 and the power supply line 705 overlap with the current supply line 704. By utilizing the upper region of the source signal line 701 and the power supply line 705, the line width is sufficiently long and the voltage drop is suppressed. A current supply line 704 is formed.

  In this embodiment, the current supply line 704 is provided below the source signal line 701 and the power supply line 705. However, the present invention is not limited to this, and the structure in which the current supply line is provided above the source signal line is provided. It is good. Alternatively, the current supply line may overlap with only a part of the source signal line or the power supply line.

  In the pixel portion, in addition to the source signal line 701 and the current supply line 704, a current control TFT 711 for determining a current value flowing through the light emitting element, and a driving element for determining light emission / non-light emission of the light emitting element by a video signal. A TFT 710, a switching TFT 712 for controlling the input of the video signal, and an erasing TFT 713 for setting the light emitting element in a non-light emitting state regardless of the video signal are provided. The current control TFT 711 is designed such that its L / W (channel length / channel width) is larger than that of the driving TFT 710, and the active layer has a meandering shape.

  FIG. 11 is a cross-sectional view taken along line A-A ′ of FIG. 4. In FIG. 11, insulating films 18 and 19 are formed of organic films. A nitride film formed by sputtering is provided on the insulating film 18. The insulating films 18 and 19 may be formed using an inorganic film such as a silicon oxide film in addition to the organic film.

  The source signal line 704 is connected to the switching TFT 712 through a conductive film 720 (720a, 720b) provided in the same layer as the current supply line 701. Further, part of the first gate signal line 702 functions as a gate electrode of the switching TFT 712. Further, part of the second gate signal line 703 functions as a gate electrode of the erasing TFT 713. Further, the power supply line 705 is connected to the gate electrode of the current control TFT 711. The current control TFT 711 is connected to the first electrode 730 (730a, 730b, 730c) of the light-emitting element through a conductive film 720 provided in the same layer as the source signal line 101. The first electrode 730 and the current supply line 701 of the light emitting element are formed of the same layer. Although not shown in FIG. 4, a partition layer provided with an opening, an electroluminescent layer, and a cathode are formed so that the first electrode 730 of the light emitting element is exposed. A portion where the first electrode 730 of the light-emitting element, the electroluminescent layer, and the second electrode of the light-emitting element are stacked functions as a light-emitting element.

  In FIG. 11, 10 is a current supply line, 11 is a power supply line, 12 is a source signal line, 13 is a first electrode of a light emitting element, 14 is a light emitting element, 15 is a semiconductor layer, 16 is a gate electrode, and 17 is a partition layer. , 18 and 19 are insulating films, 20 is a protective film, and 21 is a second electrode of the light emitting element.

  The circuit configuration of the pixel portion of this embodiment is as shown in the circuit diagram of FIG.

  In FIG. 5, the driving TFT 811 and the current control TFT 810 are p-channel transistors, and the drain of the current control TFT 810 and the anode of the light emitting element 840 are connected. In this embodiment, the first electrode 730 of the light emitting element functions as an anode, and the second electrode of the light emitting element functions as a cathode. Conversely, if the driving TFT 811 and the current control TFT 810 are n-channel TFTs, the source of the current control TFT 810 and the cathode of the light emitting element 840 are connected. In this case, the first electrode 730 of the light-emitting element functions as a cathode, and the second electrode of the light-emitting element functions as an anode.

  Next, a method for driving the pixel shown in FIG. 5 will be described. The operation of the pixel illustrated in FIG. 5 can be described by being divided into a writing period and a holding period. First, when the first gate signal line 802 is selected in the writing period, the switching TFT 812 whose gate is connected to the first gate signal line 802 is turned on. Then, the video signal input to the source signal line 801 is input to the gate of the driving TFT 811 via the switching TFT 812. Note that the current control TFT 810 is always on because the gate is connected to the power supply line 805.

  When the driving TFT 811 is turned on by the video signal, a current is supplied to the light emitting element 840 through the current supply line 804. At this time, the driving TFT 811 operates in the linear region, but the current flowing through the light emitting element 840 is determined by the voltage-current characteristics of the current control TFT 810 operating in the saturation region and the light emitting element 840. The light emitting element 840 emits light with a luminance corresponding to the supplied current.

  In addition, when the current control TFT 810 is turned off by the video signal, current is not supplied to the light emitting element 840 and the light emitting element 840 does not emit light.

  In the holding period, the switching TFT 812 is turned off by controlling the potential of the first gate signal line 802, and the potential of the video signal written in the writing period is held. When the driving TFT 811 is turned on in the writing period, the potential of the video signal is held by the capacitor 814, so that supply of current to the light-emitting element 840 is maintained. On the other hand, when the driving TFT 811 is turned off in the writing period, no current is supplied to the light-emitting element 840. Note that although a circuit including the capacitor 814 is provided in this embodiment, it may not be provided.

  In the erasing period, the second gate signal line 803 is selected, the erasing TFT 813 is turned on, and the potential of the current supply line 804 is applied to the gate of the driving TFT 811 through the erasing TFT 813. Accordingly, since the driving TFT 811 is turned off, a state where no current is forcibly supplied to the light-emitting element 840 can be created.

  With the above structure, the driving TFT 811 operates in a saturation region. Therefore, the fluctuation of the drain current with respect to the source-drain voltage (Vds) of the current control TFT 810 is small, and the slight fluctuation of the gate-source voltage (Vgs) of the driving TFT 811 does not affect the current flowing through the light emitting element 840. . The current flowing through the light emitting element 840 is determined by the current supply TFT 810 operating in the saturation region. Therefore, the current flowing through the light-emitting element 840 is not affected even if the capacity of the capacitor 814 provided between the gate and source of the current control TFT 810 is increased or the off-state current of the switching TFT 812 is not reduced. Further, it is not affected by the parasitic capacitance attached to the gate of the driving TFT 811. For this reason, luminance variations due to TFT characteristic variations and the like are reduced, and display unevenness can be reduced.

  In this embodiment, in the light-emitting element 840, the first electrode 730 of the light-emitting element and the second electrode of the light-emitting element are formed of a transparent conductive film. Therefore, light can be taken from both sides of the upper and lower surfaces (the side on which the TFT is formed with the electroluminescent layer as the center is referred to as the lower surface and the opposite side as the upper surface). However, the present invention is not limited to this, and a display device having a structure capable of collecting light only from the upper surface or only from the lower surface may be used.

  By applying the present invention, the line width of the current supply line can be increased while effectively utilizing the lower part of the surface occupied by the source signal line and the power supply line, and the voltage drop of the current supply line can be suppressed. . Therefore, as in this embodiment, in a display device that takes light from the lower surface side, a decrease in aperture ratio due to an increase in the line width of the current supply line can be minimized. As a result, a display device capable of high-definition display with little display unevenness due to voltage drop can be manufactured. Furthermore, by having the circuit configuration as shown in this embodiment, display unevenness due to TFT characteristic variation can be reduced, and a display image with very high image quality can be obtained.

  In this embodiment, the structure and driving of an active matrix display device having the pixel portion shown in Embodiment 1 will be described.

  FIG. 6 shows a block diagram of the external circuit and a schematic diagram of the panel.

  As shown in FIG. 6, the active matrix display device to which the present invention is applied includes an external circuit 3004 and a panel 3010. The external circuit 3004 includes an A / D conversion unit 3001, a power supply unit 3002, and a signal generation unit 3003. The A / D converter 3001 converts a video data signal input as an analog signal into a digital signal and supplies the digital signal to the signal line driver circuit 3006. The power supply unit 3002 generates power having a desired voltage value from power supplied from a battery or an outlet, and supplies the power to the signal line driver circuit 3006, the scan line driver circuit 3007, the OLED element 3011, the signal generator 3003, and the like. The signal generation unit 3003 receives a power source, a video signal, a synchronization signal, and the like, converts various signals, and generates a clock signal and the like for driving the signal line driver circuit 3006 and the scan line driver circuit 3007.

  A signal and power from the external circuit 3004 are input to an internal circuit or the like from an FPC connection unit 3005 in the panel 3010 through the FPC.

  In addition, the panel 3010 includes an FPC connection portion 3005 and an internal circuit on a glass substrate 3008 and has an OLED element 3011. The internal circuit includes a signal line driver circuit 3006, a scanning line driver circuit 3007, and a pixel portion 3009. In FIG. 6, the pixel described in Embodiment 1 is used as an example, but any of the pixel configurations described in the embodiment of the present invention can be used in the pixel portion 3009.

  A pixel portion 3009 is disposed at the center of the substrate, and a signal line driver circuit 3006 and a scanning line driver circuit 3007 are disposed around the pixel portion 3009. The OLED element 3011 and the counter electrode of the light emitting element are formed on the entire surface of the pixel portion 3009.

  More specifically, FIG. 7 shows a block diagram of the signal line driver circuit 3006.

  The signal line driver circuit 3006 includes a shift register 4002 using a plurality of stages of D flip-flops 4001, a data latch circuit 4003, a latch circuit 4004, a level shifter 4005, a buffer 4006, and the like.

  Input signals are a clock signal line (S-CK), an inverted clock signal line (S-CKB), a start pulse (S-SP), a digital video signal (DATA), and a latch pulse (LatchPulse).

  First, sampling pulses are sequentially output from the shift register 4002 in accordance with the timing of the clock signal, the clock inversion signal, and the start pulse. The sampling pulse is input to the data latch circuit 4003, and the digital video signal is captured and held at that timing. This operation is performed in order from the first row.

  When the holding of the digital video signal is completed in the data latch circuit 4003 in the final stage, a latch pulse is input during the horizontal blanking period, and the digital video signals held in the data latch circuit 4003 are transferred to the latch circuit 4004 all at once. Is done. Thereafter, the level shifter 4005 shifts the level, the buffer 4006 shapes the signal, and the signals are simultaneously output from the signal lines S1 to Sn. At that time, the H level and the L level are input to the pixels in the row selected by the scanning line driving circuit 3007, and the light emission and non-light emission of the OLED element 3011 are controlled.

  In the active matrix display device shown in this embodiment, the panel 3010 and the external circuit 3004 are independent, but they may be formed integrally on the same substrate. The display device uses an OLED as an example, but may be a light emitting device using a light emitting element other than the OLED. Further, the level shifter 4005 and the buffer 4006 may not be provided in the signal line driver circuit 3006.

  In this embodiment, an electronic device to which the present invention is applied will be described. A display device to which the present invention is applied can be mounted on various electronic devices to obtain a high-quality and high-definition display. Further, it can be mounted not only on a large display device such as a television but also on a small electronic device such as a cellular phone.

  FIG. 8A illustrates a display device, which includes a housing 5501, a support base 5502, and a display portion 5503. The present invention can be applied to a display device having the display portion 5503.

  FIG. 8B illustrates a video camera, which includes a main body 5511, a display portion 5512, an audio input 5513, operation switches 5514, a battery 5515, an image receiving portion 5516, and the like.

  FIG. 8C illustrates a computer manufactured by applying the present invention, which includes a main body 5501, a housing 5502, a display portion 5503, a keyboard 5504, and the like.

  FIG. 8D illustrates a personal digital assistant (PDA) manufactured by applying the present invention. A main body 5531 is provided with a display portion 5532, an external interface 5535, operation buttons 5534, and the like. There is a stylus 5532 as an accessory for operation.

  FIG. 8E illustrates a digital camera which includes a main body 5551, a display portion (A) 5552, an eyepiece portion 5553, an operation switch 5554, a display portion (B) 5555, a battery 5556, and the like.

  FIG. 8F illustrates a cellular phone manufactured by applying the present invention. A main body 5561 is provided with a display portion 5564, an audio output portion 5562 operation switch 5565, an antenna 5566, and the like.

4A and 4B illustrate one embodiment of the present invention. FIG. 9 illustrates a circuit of a pixel portion. 4A and 4B illustrate one embodiment of the present invention. FIG. 9 illustrates a circuit of a pixel portion. 4A and 4B illustrate one embodiment of the present invention. The figure which shows the outline | summary of an external circuit and a panel. FIG. 10 illustrates a configuration example of a signal line driver circuit. FIG. 11 illustrates an example of an electronic device to which the present invention is applied. 4A and 4B illustrate one embodiment of the present invention. 4A and 4B illustrate one embodiment of the present invention. 4A and 4B illustrate one embodiment of the present invention.

Claims (6)

A first insulating film on the switching transistor and the driving transistor;
A first wiring on the first insulating film;
A second insulating film on the first wiring;
A second wiring and a pixel electrode of a light emitting element on the second insulating film;
The first wiring and the second wiring extend in parallel with each other and overlap each other,
The gate of the driving transistor overlaps the first wiring and the second wiring,
The first wiring is a wiring for transmitting a video signal to the gate of the driving transistor through the switching transistor,
The display device, wherein the second wiring is a wiring for supplying a current to the light emitting element through the driving transistor. A first insulating film on the switching transistor and the driving transistor;
A first wiring on the first insulating film;
A second insulating film on the first wiring;
A second wiring and a pixel electrode of a light emitting element on the second insulating film;
The first wiring and the second wiring extend in parallel with each other and overlap each other,
A gate of the driving transistor overlaps the first wiring and the second wiring;
The first wiring is a wiring for transmitting a video signal to the gate of the driving transistor through the switching transistor,
The second wiring is an auxiliary wiring electrically connected to the third wiring;
A wiring for supplying current to the light emitting element through the driving transistor as the third wiring is formed in the same layer as the first wiring, and overlaps with the second wiring. A display device. A first insulating film on the switching transistor, the current control transistor, and the driving transistor;
A first wiring on the first insulating film;
A second insulating film on the first wiring;
A second wiring and a pixel electrode of a light emitting element on the second insulating film;
The first wiring and the second wiring extend in parallel with each other and overlap each other,
A gate of the driving transistor overlaps the first wiring and the second wiring;
The second wiring is a wiring for transmitting a video signal to the gate of the driving transistor through the switching transistor,
The first wiring is a wiring for supplying a current to the light emitting element through the driving transistor and the current control transistor,
A power supply line electrically connected to the gate of the current control transistor as a third wiring is formed in parallel with the same layer as the second wiring, and overlaps the first wiring. Display device. In claim 1 or claim 2 ,
The display device, wherein the driving transistor has an active layer having a meandering shape. In claim 3 ,
The display device, wherein the current control transistor has an active layer having a meandering shape. In any one of Claims 1 thru | or 5 ,
The display device, wherein the second wiring and the pixel electrode are formed in the same layer.

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