JP5508301B2 - Luminescent display device - Google Patents

Description

  The present invention relates to a light-emitting display device, and more particularly to an active matrix light-emitting display device including a drive circuit including a capacitor and a thin film transistor and a light-emitting element.

  2. Description of the Related Art Conventionally, light-emitting display devices in which light-emitting elements whose luminance is controlled by current, such as organic electroluminescence elements (hereinafter referred to as organic EL elements), are two-dimensionally arranged have been actively developed. In particular, an active matrix light-emitting display device in which pixel circuits each having a driving circuit for driving a light-emitting element are arranged has been developed.

  The drive circuit generally includes a switching transistor that selects a pixel that emits light, a drive transistor that drives the light emitting element, and a capacitor. The drive circuit includes, for example, a holding capacitor that holds a voltage for determining the amount of current flowing through the drive transistor (see Patent Document 1).

  FIG. 1 is a diagram showing a layout of a light emitting pixel 700 included in a conventional light emitting display device disclosed in Patent Document 1. As shown in FIG. 1, a signal line 705, a scanning line 706, and a power supply line 707 are wired in the light emitting pixel 700. The light emitting pixel 700 includes a switching transistor 701, a holding capacitor 702, a driving transistor 703, and a light emitting element 704. The light emitting element 704 is formed in the light emitting region of the light emitting pixel 700, and the switching transistor 701, the holding capacitor 702, and the driving transistor 703 are formed in the driving circuit region.

JP 2006-330736 A

  However, in the above prior art, a capacitor-dedicated region is provided, and when the number of capacitors or the area of the capacitor increases, the region where other elements are arranged becomes narrow, and the degree of freedom in design decreases. There is a problem.

  For example, like the light-emitting display device described in Patent Document 1 shown in FIG. 1, the holding capacitor 702 occupies a large part of the drive circuit region. Therefore, when the holding capacitor 702 having a larger area is provided, or when other capacitors are provided, the region where the driving transistor 703 and the switching transistor 701 are arranged becomes narrow. Or a light emission area | region will become small, the current density which flows into a light emitting element will rise, and a lifetime will become short.

  Therefore, the present invention has been made to solve the above-described conventional problems, and the degree of freedom in design can be increased by providing a capacitor without providing a capacitor-dedicated region or newly increasing the capacitor. An object is to provide a light-emitting display device.

In order to achieve the above object, a light-emitting display device according to the present invention includes a substrate, a semiconductor layer provided above the substrate, including a channel region, a source region, and a drain region, and a gate provided on the semiconductor layer. A first thin film transistor including an insulating film, a gate electrode provided on the gate insulating film, and a source electrode and a drain electrode electrically connected to the source region and the drain region of the semiconductor layer, and A semiconductor layer provided above a substrate and including a channel region, a source region, and a drain region, a gate insulating film provided on the semiconductor layer, a gate electrode provided on the gate insulating film, and the semiconductor layer wherein a second thin film transistor to the source region and the drain region comprises an electrically coupled source electrode and a drain electrode, prior to An interlayer insulating film provided on the first gate electrode of the thin film transistor and the second thin film transistor of the gate electrode, and the first thin film transistor and a light-emitting element driven to emit light by a drive circuit including the second thin film transistor A first capacitor electrode disposed in a region above the gate electrode of the first thin film transistor and on the interlayer insulating film, wherein the first capacitor electrode is connected to the gate electrode of the first thin film transistor. A first capacitor is formed between them, and is not connected to a source electrode and a drain electrode of the first thin film transistor .
The light-emitting display device according to the present invention includes a substrate, a semiconductor layer provided over the substrate and including a channel region, a source region, and a drain region, a gate insulating film provided on the semiconductor layer, and the gate A first thin film transistor including a gate electrode provided over an insulating film, a source electrode and a drain electrode electrically connected to the source region and the drain region of the semiconductor layer, respectively, and a substrate over the substrate A semiconductor layer including a channel region, a source region, and a drain region, a gate insulating film provided on the semiconductor layer, a gate electrode provided on the gate insulating film, and the source region of the semiconductor layer and A second thin film transistor including a source electrode and a drain electrode respectively electrically connected to the drain region; and the first thin film transistor. An interlayer insulating film provided on the gate electrode of the star and on the gate electrode of the second thin film transistor, a light emitting element driven to emit light by a drive circuit including the first thin film transistor and the second thin film transistor, and the first And a first capacitor electrode disposed on the interlayer insulating film in a region above the gate electrode of the first thin film transistor, the first capacitor electrode being between the gate electrode of the first thin film transistor A first capacitor is formed, and is connected to one of the source electrode and the drain electrode of the second thin film transistor.

  ADVANTAGE OF THE INVENTION According to this invention, the light emission display apparatus which can raise the freedom degree of design can be provided by providing a capacitor, without installing or increasing the area | region only for a capacitor.

FIG. 1 is a diagram illustrating a layout of pixels included in a conventional light emitting display device. FIG. 2 is a block diagram illustrating an example of a configuration of the light-emitting display device according to Embodiment 1. FIG. 3 is a diagram illustrating a circuit configuration of a light emitting pixel included in the display unit according to the first embodiment. FIG. 4 is a diagram showing an example of the layout of the light emitting pixels according to the first embodiment. FIG. 5 is a cross-sectional view of the light emitting pixel according to the first embodiment. FIG. 6 is a diagram illustrating a circuit configuration of a light emitting pixel according to a modification of the first embodiment. FIG. 7 is a cross-sectional view of a light emitting pixel according to a modification of the first embodiment. FIG. 8 is a diagram illustrating a circuit configuration of a light emitting pixel according to another modification of the first embodiment. FIG. 9 is a cross-sectional view of a luminescent pixel according to another modification of the first embodiment. FIG. 10 is a diagram illustrating a circuit configuration of a light emitting pixel included in the display unit according to the second embodiment. FIG. 11 is a diagram illustrating an example of the layout of the light-emitting pixels according to the second embodiment. FIG. 12 is a cross-sectional view of the luminescent pixel according to the second embodiment. FIG. 13 is an external view of a television provided with a light-emitting display device according to the present invention. FIG. 14 is a diagram showing an example of the layout of the light emitting pixels of another modification of the light emitting display device according to the present invention.

  Embodiments of a light-emitting display device according to the present invention will be described below with reference to the drawings.

  A light-emitting display device according to the present invention includes a substrate, a semiconductor layer provided over the substrate and including a channel region, a source region, and a drain region, a gate insulating film provided on the semiconductor layer, and the gate insulating film A gate electrode provided thereon, a thin film transistor including a source electrode and a drain electrode electrically connected to the source region and the drain region of the semiconductor layer, and an interlayer insulating film provided on the gate electrode A light emitting element driven to emit light by a driving circuit configured using the thin film transistor, and a first capacitor electrode disposed on the interlayer insulating film in a region above the gate electrode, The first capacitor electrode constitutes a first capacitor with the gate electrode.

  Thus, since the gate electrode of the thin film transistor is not only used as the gate electrode but also as one of the two electrodes constituting the capacitor, the capacitor is arranged so as to overlap the thin film transistor above the thin film transistor. The pixel space can be used effectively. Therefore, a complicated driving circuit including a large number of thin film transistors and a large number of capacitors can be formed in a limited area. Note that the capacitor may be a capacitor for holding the gate voltage, or may be a capacitor for holding the threshold voltage Vth in the driver circuit.

  The light emitting display device may include a plurality of first capacitor electrodes, and the plurality of first capacitor electrodes may constitute a first capacitor between the gate electrode and each of the plurality of first capacitor electrodes.

  Further, the source electrode or the drain electrode may constitute the same layer as the first capacitor electrode, and either one of the source electrode or the drain electrode may be electrically connected to the first capacitor electrode. .

  Thereby, the other electrode of the two electrodes constituting the capacitor and the source electrode or the drain electrode can be formed in one step.

  The light emitting element is electrically connected to the source electrode or the drain electrode, the thin film transistor is a driving transistor for supplying a driving current to the light emitting element, and the first capacitor is the driving transistor. It may be a capacitor for setting the value of the current flowing through the capacitor.

  As a result, the drive circuit can be configured while effectively utilizing the pixel space for the capacitor for setting the current value of the drive current flowing through the drive transistor.

  The thin film transistor is a switching transistor that determines a timing for supplying a driving current to the light emitting element, and the first capacitor is a capacitor for initializing a capacitor for setting a current value of the driving current. It may be.

  As a result, not only the drive transistor but also the gate electrode of the switching transistor and one of the capacitor electrodes can be used. Therefore, more thin film transistors and capacitors can be arranged by effectively using a limited pixel space.

  The first capacitor electrode may not be connected to the source electrode and the drain electrode of the thin film transistor. For example, the first capacitor electrode may be connected to either the source electrode or the drain electrode of a thin film transistor other than the thin film transistor. Good. Furthermore, the other of the source electrode and the drain electrode of the thin film transistor other than the thin film transistor may be connected to one of the source electrode and the drain electrode of the thin film transistor.

  The light emitting display device may further include a second capacitor, and the second capacitor may be connected to be in parallel with the first capacitor.

  Thereby, in addition to the first capacitor, since the second capacitor is provided in parallel, the capacitance can be increased by the amount of the second capacitor.

  The second capacitor includes an upper second capacitor electrode and a lower second capacitor electrode, and one of the upper second capacitor electrode and the lower second capacitor electrode is electrically connected to the gate electrode, The other of the upper second capacitor electrode and the lower second capacitor electrode may be electrically connected to either the source electrode or the drain electrode.

  As a result, the capacitance can be increased by the amount of the second capacitor, the voltage can be stabilized even if there is a current leak, and the crosstalk can be reduced.

  The upper second capacitor electrode may constitute the same layer as any one of the source electrode and the drain electrode, the lower second capacitor electrode may constitute the same layer as the gate electrode, One capacitor electrode may be electrically connected to the upper second capacitor electrode and one of the source electrode and the drain electrode.

  Thereby, since each capacitor electrode which comprises a 1st capacitor and a 2nd capacitor can each be formed as the same layer, a manufacturing process can be reduced.

  The area of the lower surface of the first capacitor electrode constituting the first capacitor in the region above the gate electrode may be 30% to 100% of the area of the upper surface of the gate electrode.

  The semiconductor layer may be made of polysilicon.

  The light emitting element may be an organic electroluminescence element.

  The first capacitor may have a capacitance of 0.1 to 10 pF.

  The light emitting display device may be a top emission type, and the light emitting element may be formed on an upper layer of the first capacitor electrode.

  The light emitting display device may be a bottom emission type, and the thin film transistor and the first capacitor may be formed in a region other than a light emitting region in which the light emitting element is formed.

(Embodiment 1)
The light-emitting display device according to Embodiment 1 includes a drive transistor and a capacitor, and the gate electrode of the drive transistor is one of the two capacitor electrodes constituting the capacitor. Therefore, the capacitor is formed in a region including the gate electrode of the driving transistor and above the driving transistor.

  FIG. 2 is a block diagram showing an electrical configuration of the light emitting display device 10 according to the first embodiment. The light emitting display device 10 in the figure includes at least a control circuit 20, a scanning line driving circuit 40, a signal line driving circuit 50, and a display unit 60.

  FIG. 3 is a diagram illustrating a circuit configuration of the light emitting pixel 100 included in the display unit 60 according to the first embodiment. The light emitting pixel 100 in FIG. 1 includes a switching transistor 101, a capacitor 102, a driving transistor 103, an organic EL element 104, a signal line 105, a scanning line 106, a high voltage side power supply line 107, and a low voltage side power supply. Line 108.

  First, connection relationships and functions of the components shown in FIG. 2 will be described.

  The control circuit 20 has a function of controlling the scanning line driving circuit 40 and the signal line driving circuit 50. The control circuit 20 outputs a video signal input from the outside to the signal line driving circuit 50 and controls the operation timing of the scanning line driving circuit 40 in accordance with the operation of the signal line driving circuit 50.

  The scanning line driving circuit 40 is connected to the scanning line 106, and outputs a scanning signal to the scanning line 106, thereby switching the switching transistor 101 included in the light emitting pixel 100 between conduction (on state) and non-conduction (off state). It has a function to control.

  The signal line driver circuit 50 is connected to the signal line 105 and has a function of outputting a signal voltage based on the video signal to the light emitting pixels 100.

  The display unit 60 includes a plurality of light emitting pixels 100 arranged in a two-dimensional manner, and displays an image based on a video signal input to the light emitting display device 10 from the outside.

  Next, the connection relationship and functions of the components shown in FIG. 3 will be described.

  The switching transistor 101 is an example of a switching element in which the gate is connected to the scanning line 106, one of the source and the drain is connected to the signal line 105, and the other of the source and the drain is connected to the capacitor electrode 102 a of the capacitor 102. The switching transistor 101 has a function of determining the timing at which the signal voltage of the signal line 105 is applied to the capacitor electrode 102 a of the capacitor 102. The switching transistor 101 is, for example, an n-type thin film transistor (n-type TFT), but may be a p-type TFT.

  The capacitor 102 is an example of a first capacitor, and includes two capacitor electrodes 102a and 102b. The capacitor electrode 102 a is connected to the gate of the driving transistor 103, and the capacitor electrode 102 b is connected to the high voltage side power supply line 107. The capacitor 102 holds electric charge corresponding to the signal voltage supplied from the signal line 105. That is, the capacitor 102 is an example of a storage capacitor element for setting the current value of the drive current supplied to the organic EL element 104. For example, the capacitor 102 has a function of supplying a drive current from the drive transistor 103 to the organic EL element 104 until the next new signal voltage is written even after the switching transistor 101 is turned off.

  The drive transistor 103 is an example of a drive element whose source is connected to the high-voltage power supply line 107 and whose drain is connected to the anode of the organic EL element 104. The driving transistor 103 converts a voltage corresponding to the signal voltage applied between the gate and the source into a source-drain current corresponding to the signal voltage. The source-drain current is supplied to the organic EL element 104 as a drive current. The drive transistor 103 is, for example, a p-type thin film transistor (p-type TFT).

  The organic EL element 104 is an example of a light-emitting element that is driven to emit light by a drive circuit configured using a thin film transistor such as the drive transistor 103. The organic EL element 104 has an anode connected to the drain of the drive transistor 103 and a cathode connected to the low-voltage power supply line 108. The organic EL element 104 emits light when a driving current flows through the driving transistor 103. The emission intensity is controlled by the magnitude of the drive current, that is, the signal voltage.

  The signal line 105 is connected to the signal line driving circuit 50, is connected to each light emitting pixel belonging to the pixel column including the light emitting pixel 100, and has a function of supplying a signal voltage for determining light emission intensity. The light emitting display device 10 includes as many signal lines 105 as the number of pixel columns.

  The scanning line 106 is connected to the scanning line driving circuit 40 and is connected to each light emitting pixel belonging to the pixel row including the light emitting pixel 100. Accordingly, the scanning line 106 has a function of supplying a timing for writing the signal voltage to each light emitting pixel belonging to the pixel row including the light emitting pixel 100. Note that the light emitting display device 10 includes the scanning lines 106 corresponding to the number of pixel rows.

  Although not shown in FIGS. 2 and 3, the high voltage side power supply line 107 and the low voltage side power supply line 108 are also connected to other light emitting pixels and connected to a voltage source. The potential difference between the voltage source VDD to which the high voltage side power supply line 107 is connected and the voltage source VEE to which the low voltage side power supply line 108 is connected allows a current sufficient to cause the organic EL element 104 to emit light. It is a big size. Note that the low-voltage power supply line 108 may be grounded.

  As shown in the above configuration, the light-emitting display device 10 according to Embodiment 1 includes the display unit 60 including a plurality of light-emitting pixels 100 arranged in a two-dimensional manner. The display unit 60 displays an image when the organic EL element 104 in the light emitting pixel 100 emits light with a light emission intensity corresponding to the signal voltage.

  Next, the positional relationship of each element included in the light emitting pixel 100 according to Embodiment 1 will be described.

  FIG. 4 is a diagram showing an example of the layout of the light emitting pixel 100 according to the first embodiment.

  As shown in FIG. 4, the light emitting pixel 100 is divided into a drive circuit region 110 and a light emitting region 120. An organic EL element 104 is formed in the light emitting region 120, and the organic EL element 104 emits light according to a signal voltage supplied from the signal line 105. Note that the light-emitting display device 10 according to Embodiment 1 is a bottom-emission light-emitting display device. That is, the light emitted from the organic EL element 104 is emitted toward the back surface of the substrate. In other words, the display surface of the display unit 60 is the back side of the substrate.

  The drive circuit region 110 is a region excluding the light emitting region 120 in the light emitting pixel 100, and is a region where a drive circuit for driving the organic EL element 104 is formed. In the drive circuit region 110, a switching transistor 101, a capacitor 102, and a drive transistor 103 are formed.

  FIG. 5 is a cross-sectional view of the light emitting pixel 100 according to the first embodiment. Specifically, FIG. 5 is a diagram schematically showing an AA cross section of the light emitting pixel 100 shown in FIG. A cross section AA is a cross section showing a positional relationship between the capacitor 102 and the driving transistor 103. For simplicity, the signal line 105 and the high-voltage power supply line 107 are not shown in FIG.

  As shown in FIG. 5, the drive transistor 103 is formed on the substrate 210. The driving transistor 103 includes a semiconductor layer 220, a gate insulating film 230, a gate electrode 103g, a source electrode 103s, and a drain electrode 103d. The capacitor 102 includes a capacitor electrode 102b, an interlayer insulating film 240, and a capacitor electrode 102a that also functions as the gate electrode 103g. Further, a planarization film 250 is formed on the capacitor 102.

  The substrate 210 is a transparent substrate having transparency, such as glass or quartz. The substrate 210 may be a flexible substrate such as plastic. In the case of a top emission type light emitting display device, the substrate 210 may be a semiconductor substrate such as a silicon substrate or a compound semiconductor substrate made of a compound semiconductor such as a nitride semiconductor.

  Note that although the driving transistor 103 is formed over the substrate 210, the driving transistor 103 may be formed over the substrate 210. For example, a buffer layer may be formed over the substrate 210, and the driving transistor 103 may be formed over the buffer layer.

  The semiconductor layer 220 is a semiconductor layer formed on the substrate 210, and includes a channel region 221, a source region 222, and a drain region 223. For example, the semiconductor layer 220 is made of an inorganic semiconductor such as polysilicon doped with impurities, microcrystalline silicon, or amorphous silicon, or an organic semiconductor.

  Note that since the driving transistor 103 is a p-type TFT, holes mainly contribute to conduction in the channel region 221. That is, according to the voltage applied to each of the source electrode 103s, the drain electrode 103d, and the gate electrode 103g, holes move from the source region 222 to the drain region 223, whereby the driving current described above flows.

  The gate insulating film 230 is an insulating film such as a silicon oxide film (SiOx), for example. In the example shown in FIG. 5, the gate insulating film 230 is formed on the entire surface of the substrate 210 so as to cover the semiconductor layer 220, and through holes are formed in regions above the source region 222 and the drain region 223. Note that the gate insulating film 230 may be formed at least over the channel region 221.

  The gate electrode 103g is a metal electrode formed on the gate insulating film 230. For example, the gate electrode 103g has a single layer structure such as a metal such as molybdenum or tungsten, molybdenum / tungsten alloy, polysilicon, or a stacked structure of polysilicon, titanium, tungsten, and the like. The gate electrode 103g is connected to the source or drain of the switching transistor 101 (not shown in FIG. 5). The point that the gate electrode 103g also functions as the capacitor electrode 102a of the capacitor 102 is the greatest feature of the present invention.

  The source electrode 103s is formed on the source region 222 and has a stacked structure of a metal such as aluminum or copper, or a metal such as aluminum and molybdenum, for example. The source electrode 103s is connected to the high voltage side power supply line 107 (not shown in FIG. 5). Further, as shown in FIG. 5, the source electrode 103 s is connected to the capacitor electrode 102 b of the capacitor 102 through a through hole formed in the interlayer insulating film 240 and the gate insulating film 230.

  The drain electrode 103d is formed on the drain region 223 and has a stacked structure of a metal such as aluminum or a metal such as aluminum and molybdenum, for example. The drain electrode 103d is connected to the anode of the organic EL element 104 (not shown in FIG. 5).

  The interlayer insulating film 240 is formed on the gate electrode 103g, and is composed of, for example, a silicon nitride film (SiNx), a silicon oxide film, or the like. In the example shown in FIG. 5, the interlayer insulating film 240 is formed on the entire surface of the gate insulating film 230 so as to cover the gate electrode 103g, and through holes are formed in the information regions of the source region 222 and the drain region 223. Note that the interlayer insulating film 240 may be formed at least over the gate electrode 103g.

  The interlayer insulating film 240 has a thickness of 100 to 1000 nm.

  The capacitor electrode 102b is an example of a first capacitor electrode, and is formed above the gate electrode 103g and on the interlayer insulating film 240. That is, the capacitor electrode 102b is disposed in the region above the gate electrode 103g and on the interlayer insulating film 240. The capacitor electrode 102b constitutes the capacitor 102 together with the gate electrode 103g which is the other capacitor electrode 102a. For example, the capacitor electrode 102b is formed of a metal, such as aluminum or copper, or a stacked structure of metals such as aluminum and molybdenum. In this example, the capacitor electrode 102 b is connected to the high voltage side power supply line 107.

  The capacitor electrode 102b constitutes the same layer as the source electrode 103s and is connected to the source electrode 103s. Specifically, the capacitor electrode 102 b is connected to the source electrode 103 s through a through hole formed in the interlayer insulating film 240. The capacitor electrode 102b is preferably made of the same material as the source electrode 103s. Accordingly, the capacitor electrode 102b and the source electrode 103s can be formed in the same process, and the number of processes can be reduced.

  Note that the area of the lower surface of the capacitor electrode 102b in the region above the gate electrode 103g which is the capacitor electrode 102a is 30% to 100% of the area of the upper surface of the gate electrode 103g. Note that the capacitor electrode 102b may be larger than the gate electrode 103g. The capacitance of the capacitor 102 is 0.1 to 10 pF.

  The planarization film 250 is formed on the capacitor 102 and functions as a protective film that protects the capacitor 102 and the drive transistor 103, and also functions as a planarization film that planarizes the upper side of the capacitor 102 and the drive transistor 103. The planarization film 250 is made of, for example, a silicon oxide film (SiOx) or a silicon nitride film (SiNx).

  As shown in the above configuration, the capacitor 102 uses the gate electrode 103g as one electrode. That is, the capacitor 102 including the gate electrode 103g as the capacitor electrode 102a is formed in a region above the driving transistor 103.

  As a result, as shown in FIG. 4, the capacitor 102 can be arranged without providing a region dedicated to the capacitor 102 in the light emitting pixel 100. Therefore, the area of the capacitor 102 or the arrangement of the driving transistor 103 and the switching transistor 101 can be designed relatively freely. Alternatively, other capacitors can be added to the drive circuit region 110. Thus, according to the light emitting display device 10 according to Embodiment 1, the degree of freedom in design can be improved. Thereby, for example, since the light emitting display device 10 according to Embodiment 1 is a bottom emission type, the light emitting region 120 can be secured widely, and the current density flowing through the organic EL element 104 can be reduced. The light emission lifetime of the light emitting display device 10 can be secured longer.

  Note that as shown in this embodiment mode, the structure in which the capacitor is formed above the driving transistor 103 can be applied to other driving circuits than the circuit shown in FIG. Specifically, the configuration according to the present embodiment can be applied to a drive circuit having a circuit configuration in which the gate of the drive transistor 103 and one of two capacitor electrodes constituting the capacitor are electrically connected. it can. Hereinafter, some modifications will be described with reference to the drawings.

(Modification 1)
FIG. 6 is a diagram illustrating a circuit configuration of a light emitting pixel 300 according to a modification of the first embodiment. 6 includes a switching transistor 101, 313, 314, and 315, a driving transistor 103, capacitors 311 and 312, an organic EL element 104, a signal line 105, scanning lines 106, 316, 317, and 318, a high-voltage power supply line 107, a low-voltage power supply line 108, and a reference voltage power supply line 319. In addition, the same code | symbol is attached | subjected about the same structure as the light emitting pixel 100 shown in FIG. 3, and description is abbreviate | omitted below.

  The switching transistor 313 has a gate connected to the scanning line 316, one of the source and the drain connected to the reference voltage power supply line 319, and the other of the source and the drain connected to one of the source and the drain of the switching transistor 101. It is an example. The switching transistor 313 has a function of initializing the gate potential of the driving transistor 103, that is, setting the reference potential Vref.

  Specifically, the switching transistor 313 is turned on by a scanning signal supplied from the scanning line 316, and supplies the reference potential Vref to the second electrode of the capacitor. Note that the switching transistor 313 is, for example, an n-type TFT.

  The switching transistor 314 is an example of a switching element in which the gate is connected to the scanning line 317, one of the source and the drain is connected to the gate of the driving transistor 103, and the other of the source and the drain is connected to the drain of the driving transistor 103. . The switching transistor 314 has a function of detecting the threshold voltage of the driving transistor 103.

  Specifically, for example, the switching transistor 314 is turned on by a scanning signal supplied from the scanning line 317 and short-circuits the gate and drain of the driving transistor 103. Therefore, the threshold voltage of the drive transistor 103 is generated at the gate electrode of the drive transistor 103. The switching transistor 314 is, for example, an n-type TFT.

  The switching transistor 315 is an example of a switching element in which the gate is connected to the scanning line 318, one of the source and the drain is connected to the drain of the driving transistor 103, and the other of the source and the drain is connected to the anode of the organic EL element 104. is there. The switching transistor 315 has a function of determining timing for supplying a drive current to the organic EL element 104.

  Specifically, the switching transistor 315 is turned on by a scanning signal supplied from the scanning line 318, and a driving current is supplied to the organic EL element 104 if the driving transistor 103 is turned on during the on state. Is done. In other words, if the switching transistor 315 is off, no current is supplied to the organic EL element 104 regardless of the operation of the drive transistor 103. Note that the switching transistor 315 is, for example, an n-type TFT.

  The capacitor 311 includes two capacitor electrodes 311a and 311b. The capacitor electrode 311 a is connected to the reference voltage power supply line 319, and the capacitor electrode 311 b is connected to one of the source and drain of the switching transistor 101. The capacitor electrode 311b is connected to the gate of the driving transistor 103 via the capacitor 312. The capacitor 311 holds charges corresponding to the signal voltage supplied from the signal line 105.

  The capacitor 312 is an example of a first capacitor, and includes two capacitor electrodes 312a and 312b. The capacitor electrode 312 a is connected to one of the source and the drain of the switching transistor 101, and the capacitor electrode 312 b is connected to the gate of the drive transistor 103. The capacitor 312 holds electric charge corresponding to the threshold voltage of the driving transistor 103.

  The scanning lines 316, 317, and 318 are connected to the scanning line driving circuit 40 and connected to each light emitting pixel belonging to the pixel column including the light emitting pixel 300. The scanning line 316 has a function of supplying a reference voltage for detecting the threshold voltage of the driving transistor 103 included in each light emitting pixel belonging to the pixel row including the light emitting pixel 300.

  The scanning line 317 has a function of supplying timing for detecting the threshold voltage of the driving transistor 103 included in each light emitting pixel belonging to the pixel row including the light emitting pixel 300. The scanning line 318 has a function of supplying a timing for supplying a driving current to the organic EL element 104 included in each light emitting pixel belonging to the pixel row including the light emitting pixels 300 and a timing for detecting a threshold voltage of the driving transistor 103.

  The light emitting display device 10 includes scanning lines 316, 317, and 318 corresponding to the number of pixel rows.

  The reference voltage power line 319 is also connected to other light emitting pixels, and is connected to a voltage source that supplies a predetermined reference voltage. As a result, the potential of the reference voltage power supply line 319 is maintained at the reference potential Vref.

  FIG. 7 is a partial cross-sectional view of a light emitting pixel 300 according to a modification of the first embodiment. Specifically, FIG. 7 shows an arrangement configuration of the capacitor 312 and the driving transistor 103. Note that the cross-sectional configuration of the drive transistor 103 is the same as the cross-sectional configuration illustrated in FIG.

  As shown in FIG. 7, the capacitor electrode 312 b of the capacitor 312 is formed on the interlayer insulating film 240. The gate electrode 103g also functions as the capacitor electrode 312a of the capacitor 312.

  The capacitor electrode 312b is an example of a first capacitor electrode, and is not connected to the source electrode 103s or the drain electrode 103d of the driving transistor 103. The capacitor electrode 312b is connected to one of the source and drain of the switching transistor 101 and the capacitor electrode 311b (not shown in FIG. 7).

  As described above, the capacitor electrode 312b of the capacitor 311 formed over the driving transistor 103 may not be connected to each electrode of the driving transistor 103. That is, as long as one of the two electrodes constituting the capacitor is connected to the gate electrode 103g of the driving transistor 103, the structure according to this embodiment can be applied.

(Modification 2)
FIG. 8 is a diagram illustrating a circuit configuration of a light emitting pixel 400 according to another modification of the first embodiment. The light emitting pixel 400 shown in FIG. 8 is different from the light emitting pixel 300 shown in FIG. 6 in that a capacitor 411 is provided instead of the capacitor 311 and a switching transistor 413 is provided instead of the switching transistor 313. Hereinafter, the same components as those of the light emitting pixel 300 illustrated in FIG. 6 are denoted by the same reference numerals, and description thereof is omitted below.

  The capacitor 411 is an example of a first capacitor, and includes two capacitor electrodes 411a and 411b. The capacitor electrode 411a is connected to the gate electrode 103g of the driving transistor 103, and the capacitor electrode 411b is connected to, for example, the high voltage side power supply line 107. The capacitor 411 holds charges corresponding to the signal voltage supplied from the signal line 105 and the threshold voltage of the driving transistor.

  The switching transistor 413 has a gate connected to the scanning line 316, one of the source and the drain connected to the high-voltage power supply line 107, the other of the source and the drain connected to one of the source and the drain of the switching transistor 101, and the capacitor of the capacitor 312. It is an example of the switching element connected to the electrode 312b. The switching transistor 413 has a function of initializing the capacitor 312 and the capacitor 411.

  Specifically, the switching transistor 413 is turned on by a scanning signal supplied from the scanning line 316, sets the potential of the capacitor electrode 312b of the capacitor 312 to VDD, and the scanning transistor 314 is supplied from the scanning line 317. By being turned on by the signal, the capacitor 312 and the capacitor 411 are initialized so that the threshold voltage of the driving transistor 103 is held. Note that the switching transistor 413 is, for example, an n-type TFT.

  FIG. 9 is a cross-sectional view of a light emitting pixel 400 according to a modification of the first embodiment. Specifically, FIG. 9 shows an arrangement configuration of the capacitor 312, the capacitor 411, and the driving transistor 103. Note that the cross-sectional configuration of the drive transistor 103 is the same as the cross-sectional configuration illustrated in FIG.

  As shown in FIG. 9, the capacitor electrode 312 b of the capacitor 312 and the capacitor electrode 411 b of the capacitor 411 are formed on the interlayer insulating film 240. The gate electrode 103g also functions as the capacitor electrode 312a of the capacitor 312 and the capacitor electrode 411a of the capacitor 411.

  The capacitor electrode 411b is an example of a first capacitor electrode, forms the same layer as the source electrode 103s of the driving transistor 103, and is connected to the source electrode 103s. Specifically, the capacitor electrode 411 b is connected to the source electrode 103 s through a through hole formed in the interlayer insulating film 240.

  Note that the capacitor electrode 312b, the capacitor electrode 411b, and the source electrode 103s are preferably made of the same material. Accordingly, the capacitor electrode 312b, the capacitor electrode 411b, and the source electrode 103s can be formed in the same process, so that the number of processes can be reduced.

  As described above, the light-emitting display device 10 according to the second modification of the first embodiment includes the plurality of first capacitor electrodes, and the plurality of first capacitor electrodes includes the first capacitor between the gate electrode 103g. It is composed. In the example shown in FIGS. 8 and 9, two first capacitor electrodes are shown, but three or more first capacitor electrodes are formed in the region above the gate electrode 103 g and on the interlayer insulating film 240. May be.

  As described above, in the light emitting display device 10 according to the first embodiment and the modification thereof, the first capacitor is formed by the gate electrode 103g of the drive transistor 103 included in the drive circuit and the first capacitor electrode formed above the gate electrode 103g. Configure. The first capacitor thus configured can be used as a storage capacitor element for setting the current value of the drive current supplied to the organic EL element 104.

  Thereby, the limited area | region in the light emission pixel 100 can be utilized effectively. That is, the degree of design freedom can be increased. Therefore, the light emitting display device 10 according to the present embodiment has an effect that, for example, a wide light emitting region 120 can be secured.

  Note that the light-emitting display device 10 according to Embodiment 1 may further include a second capacitor that is electrically connected to the capacitor 102 in parallel. For example, the second capacitor includes an upper second capacitor electrode and a lower second capacitor electrode. One of the upper second capacitor electrode and the lower second capacitor electrode is connected to the gate electrode 103g, and the other is electrically connected to one of the source electrode 103s and the drain electrode 103d.

  More specifically, the lower second capacitor electrode constitutes the same layer as the gate electrode 103g, and the upper second capacitor electrode is the same as one of the electrically connected source electrode 103s and drain electrode 103d. It may constitute a layer. At this time, the capacitor electrode 102a of the capacitor 102 is electrically connected to the upper second capacitor electrode.

(Embodiment 2)
The light-emitting display device according to Embodiment 2 includes a switching transistor, a driving transistor, and a capacitor, and the gate electrode of the switching transistor is one of the two capacitor electrodes that form the capacitor. Therefore, the capacitor is formed in the region above the switching transistor.

  The light emitting display device according to the second embodiment is different from the light emitting display device 10 according to the first embodiment in the circuit configuration of the light emitting pixels included in the display unit and the arrangement of the elements constituting the light emitting pixels. . That is, the electrical configuration of the light-emitting display device according to Embodiment 2 is the same as that of the light-emitting display device 10 according to Embodiment 1 shown in FIG. Therefore, in the following, description of the electrical configuration of the light-emitting display device according to Embodiment 2 will be omitted, and description will be made focusing on the circuit configuration of the light-emitting pixel and the arrangement of elements constituting the light-emitting pixel.

  FIG. 10 is a diagram illustrating a circuit configuration of the light emitting pixel 500 included in the display unit according to the second embodiment. The light-emitting pixel 500 in the figure includes switching transistors 501, 506, 507, and 508, capacitors 502 and 505, a driving transistor 503, an organic EL element 504, a signal line 509, scanning lines 510, 511, 512, and 513. A high-voltage power supply line 514, a low-voltage power supply line 515, and a reference voltage power supply line 516.

  The switching transistor 501 has a gate connected to the scanning line 510, one of the source and drain connected to the signal line 509, and the other connected to the capacitor electrode 502 a of the capacitor 502 and the gate of the driving transistor 503. It is an example of an element. The switching transistor 501 has a function of determining timing for applying the signal voltage of the signal line 509 to the capacitor electrode 502 a of the capacitor 502. The switching transistor 501 is, for example, an n-type TFT.

  The capacitor 502 is an example of a first capacitor for the driving transistor 503, and includes two capacitor electrodes 502a and 502b. The capacitor electrode 502 a is connected to the gate of the driving transistor 503, and the capacitor electrode 502 b is connected to the capacitor electrode 505 b of the capacitor 505 and the source or drain of the switching transistor 507. The capacitor 502 holds electric charge corresponding to the signal voltage supplied from the signal line 509 and the threshold voltage of the driving transistor 503. That is, the capacitor 502 is an example of a storage capacitor element for setting the current value of the drive current supplied to the organic EL element 504.

  The drive transistor 503 is an example of a drive element having a drain connected to the high-voltage power supply line 514 and a source connected to the anode of the organic EL element 504 via the switching transistor 508. The driving transistor 503 converts a voltage corresponding to the signal voltage applied between the gate and the source into a source-drain current corresponding to the signal voltage. The drive transistor 503 is, for example, an n-type TFT.

  The organic EL element 504 is an example of a light emitting element in which an anode is connected to the source of the driving transistor 503 via the switching transistor 508 and a cathode is connected to the low voltage side power supply line 515. The organic EL element 504 emits light when a driving current flows through the driving transistor 503.

  The capacitor 505 is an example of a first capacitor for the switching transistor 508, and includes two capacitor electrodes 505a and 505b. The capacitor electrode 505a is connected to the scanning line 513, and the capacitor electrode 505b is connected to one of the source and drain of the capacitor electrode 502b and the switching transistor 507. The capacitor 505 is an example of a capacitor element for adjusting the amount of voltage held by the capacitor 502 serving as a holding capacitor element for the data voltage applied from the signal line 509.

  The switching transistor 506 is an example of a switching element in which the gate is connected to the scanning line 511, one of the source and the drain is connected to the reference voltage power supply line 516, and the other of the source and the drain is connected to the gate of the driving transistor 503. . The switching transistor 506 has a function of applying a reference voltage Vref to the gate of the driving transistor 503. Note that the switching transistor 506 is, for example, an n-type TFT.

  The switching transistor 507 is an example of a switching element in which the gate is connected to the scanning line 512, one of the source and the drain is connected to the capacitor electrode 502 b of the capacitor 502, and the other of the source and the drain is connected to the source of the driving transistor 503. is there. The switching transistor 507 has a function of disconnecting the capacitor 502 and the source of the driving transistor 503 when a signal voltage is written to the capacitor 502. Note that the switching transistor 507 is, for example, an n-type TFT.

  The switching transistor 508 is an example of a switching element in which the gate is connected to the scanning line 513, one of the source and the drain is connected to the source of the driving transistor 503, and the other of the source and the drain is connected to the anode of the organic EL element 504. is there. The switching transistor 508 has a function of determining timing for supplying a drive current to the organic EL element 504. Note that the switching transistor 508 is, for example, an n-type TFT.

  The signal line 509 is connected to the signal line driver circuit, is connected to each light emitting pixel belonging to the pixel column including the light emitting pixel 500, and has a function of supplying a signal voltage for determining light emission intensity. Note that the light-emitting display device according to Embodiment 2 includes as many signal lines 509 as the number of pixel columns.

  The scanning lines 510, 511, 512, and 513 are connected to the scanning line driving circuit and are connected to each light emitting pixel belonging to the pixel row including the light emitting pixel 500. The scanning line 510 has a function of supplying timing for writing the signal voltage to each light emitting pixel belonging to the pixel row including the light emitting pixel 500.

  The scanning line 511 has a function of supplying timing for applying the reference voltage Vref to the gate of the driving transistor 503 in each light emitting pixel belonging to the pixel row including the light emitting pixel 500. The scanning line 512 has a function of supplying timing for disconnecting the capacitor 502 and the source of the driving transistor 503 in each light emitting pixel belonging to the pixel row including the light emitting pixel 500. The scanning line 513 has a function of supplying timing for supplying a driving current to the organic EL element 504 in each light emitting pixel belonging to the pixel row including the light emitting pixel 500.

  Note that the light-emitting display device according to Embodiment 2 includes scan lines 510, 511, 512, and 513 corresponding to the number of pixel rows.

  Although not shown in FIG. 10, the high voltage side power supply line 514, the low voltage side power supply line 515, and the reference voltage power supply line 516 are also connected to other light emitting pixels and connected to the voltage source. ing. The potential difference between the voltage source to which the high voltage side power supply line 514 is connected and the voltage source to which the low voltage side power supply line 515 is connected is large enough to allow a current sufficient to cause the organic EL element 504 to emit light. That's it. Note that the low voltage side power supply line 515 may be grounded.

  FIG. 11 is a diagram showing an example of the layout of the light emitting pixel 500 according to the second embodiment. The light-emitting display device according to Embodiment 2 is a top emission type light-emitting display device. That is, the light emitted from the organic EL element 504 is emitted toward the surface of the substrate. In other words, the display surface of the display unit is the surface side of the substrate.

  In the light emitting pixel 500, the light emitting region in which the organic EL element 504 is formed and the drive circuit region are the same. That is, a light emitting region is formed above the drive circuit region.

  As shown in FIG. 11, the drive transistor 503 and the capacitor 502 are formed to overlap the same region in the plane, and the switching transistor 508 and the capacitor 505 are formed to overlap the same region in the plane. . As described above, the structure according to this embodiment can be applied to any circuit structure in which the gate of the thin film transistor such as the driving transistor 503 or the switching transistor 508 is electrically connected to the capacitor electrode of the capacitor. .

  FIG. 12 is a cross-sectional view of the light-emitting pixel 500 according to the second embodiment. Specifically, FIG. 12 shows an arrangement configuration of the switching transistor 508, the capacitor 505, and the organic EL element 504.

  Note that the configuration of the switching transistor 508 is the same as that of the driving transistor 103 illustrated in FIG. That is, the substrate 610, the semiconductor layer 620, the gate insulating film 630, the interlayer insulating film 640, the gate electrode 508g, the source electrode 508s, and the drain electrode 508d shown in FIG. 12 are respectively the substrate 210, the semiconductor layer 220, and the gate insulating film shown in FIG. It corresponds to the film 230, the interlayer insulating film 240, the gate electrode 103g, the source electrode 103s, and the drain electrode 103d. Further, the channel region 621, the source region 622, and the drain region 623 included in the semiconductor layer 620 correspond to the channel region 221, the source region 222, and the drain region 223 included in the semiconductor layer 220, respectively.

  As shown in FIG. 12, the capacitor electrode 505b of the capacitor 505 is an example of a first capacitor electrode, forms the same layer as the source electrode 508s, and is electrically connected to the source electrode 508s. Note that the capacitor electrode 505b may be electrically connected to the drain electrode 508d instead of the source electrode 508s.

  Since the light-emitting display device according to Embodiment 2 is a top emission type light-emitting display device, the organic EL element 504 is formed in an upper layer of the capacitor 505. Specifically, as shown in FIG. 12, an organic EL element 504 is formed through a planarizing film 650 formed on the capacitor 505. The organic EL element 504 includes an anode 504a, a light emitting layer 504b, and a transparent cathode 504c.

  The planarizing film 650 is made of, for example, a silicon nitride film.

  The anode 504a is an electrode having light reflectivity, and is made of, for example, a metal such as aluminum. The anode 504a has a function of reflecting light emitted from the light emitting layer 504b. The anode 504a is an anode electrode of the organic EL element 504, and is connected to the source of the driving transistor 503 via the switching transistor 508 as shown in FIG.

  The light emitting layer 504b is a light emitting layer that is formed between the anode 504a and the transparent or translucent transparent cathode 504c and emits light by recombination of holes and electrons injected from the anode 504a and the transparent cathode 504c. Note that the light-emitting layer 504b may include a hole transport layer, a hole injection layer, an electron transport layer, an electron injection layer, and the like.

  The transparent cathode 504c is an electrode having optical transparency, and is made of a transparent oxide conductive film such as indium tin oxide (ITO), for example. The transparent cathode 504c is a cathode electrode of the organic EL element 504, and is connected to the low voltage side power supply line 515 as shown in FIG.

  As described above, in the light-emitting display device according to Embodiment 2, the capacitor 505 includes the gate electrode 508g of the switching transistor 508 included in the driver circuit and the capacitor electrode 505b formed above the gate electrode 508g. The capacitor 505 configured as described above initializes a storage capacitor element for setting a current value of a drive current supplied to the organic EL element 504, for example, and the storage capacitor has a data voltage applied from the signal line 509. Of these, it can be used as a capacitive element for adjusting the amount of voltage to be held.

  Therefore, the configuration of the present embodiment can be applied to any drive circuit having a circuit configuration in which the gate electrode of the switching transistor and one of the capacitor electrodes of the capacitor are electrically connected. As a result, the area dedicated to the capacitor can be reduced, and the degree of freedom in designing the drive circuit can be increased.

  Although the light-emitting display device according to the present invention has been described based on the embodiments, the present invention is not limited to these embodiments. Unless it deviates from the meaning of this invention, the form which carried out the various deformation | transformation which those skilled in the art can think to the said embodiment, and the form constructed | assembled combining the component in different embodiment is also contained in the scope of the present invention. .

  For example, the present invention can be applied to a circuit having a circuit configuration in which a gate of a thin film transistor included in a driver circuit and one of electrodes of a capacitor are connected. In the above-described embodiment, the configuration in which the gate of the driving transistor or the switching transistor and one of the electrodes of the capacitor are connected is described.

  In the above-described embodiment, the n-type transistor that is turned on when a positive voltage is applied to the gate of the switching transistor has been described. Even if the video display device has the polarity reversed, the same effects as those of the above-described embodiments can be obtained. In the above description, the lower electrode is an anode and the upper electrode is a cathode. However, the lower electrode may be a cathode and the upper electrode may be an anode.

  Further, for example, the light emitting display device according to the present invention is built in a television as shown in FIG. By incorporating the light emitting display device according to the present invention, a television capable of displaying images with high accuracy reflecting a video signal is realized.

  In addition, the light emitting display device according to the present invention may include a second capacitor that is electrically connected in parallel with the first capacitor including the gate electrode of the thin film transistor as described above as a lower electrode.

  FIG. 14 is a diagram showing an example of the layout of the light emitting pixels of another modification of the light emitting display device according to the present invention. In FIG. 14, the same components as those of the conventional light emitting display device shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted below.

  As shown in FIG. 14, the light emitting pixel 700 includes a first capacitor 708 and a holding capacitor 702 that is a second capacitor. The first capacitor 708 is formed on the driving transistor 703 and includes an upper electrode and a lower electrode. The lower electrode of the first capacitor 708 also functions as the gate electrode of the driving transistor 703. The holding capacitor 702 as the second capacitor includes an upper second capacitor electrode and a lower second capacitor electrode.

  The upper electrode of the first capacitor 708 is electrically connected to the upper second capacitor electrode of the holding capacitor 702. Specifically, as shown in FIG. 14, the upper electrode of the first capacitor 708 is the same as the upper second capacitor electrode of the holding capacitor 702, the power supply line 707, and one of the source electrode and the drain electrode of the driving transistor 703. And is electrically connected to one of the layers.

  As described above, the lower electrode of the first capacitor 708 functions as the gate electrode of the driving transistor 703 and is electrically connected to the lower second capacitor electrode of the holding capacitor 702. Specifically, as shown in FIG. 14, the gate electrode which is the lower electrode of the first capacitor 708 forms the same layer as the lower second capacitor electrode of the holding capacitor 702 and is electrically connected.

  With the above configuration, the region above the driving transistor 703 can be used effectively, and the capacitance of the holding capacitor 702 can be increased.

  The light emitting display device according to the present invention can be used for all display devices such as a television, a personal computer, and a mobile phone.

DESCRIPTION OF SYMBOLS 10 Light emitting display apparatus 20 Control circuit 40 Scan line drive circuit 50 Signal line drive circuit 60 Display part 100,300,400,500,700 Light emission pixel 101,313,314,315,413,501,506,507,508,701 Switching transistors 102, 311, 312, 411, 502, 505 Capacitors 102a, 102b, 311a, 311b, 312a, 312b, 411a, 411b, 502a, 502b, 505a, 505b Capacitor electrodes 103, 503, 703 Driving transistors 103d, 508d Drain Electrodes 103g, 508g Gate electrodes 103s, 508s Source electrodes 104, 504 Organic EL elements 105, 509, 705 Signal lines 106, 316, 317, 318, 510, 511, 512, 513, 70 Scan line 107, 514 High voltage side power supply line 108, 515 Low voltage side power supply line 110 Drive circuit region 120 Light emitting region 210, 610 Substrate 220, 620 Semiconductor layer 221, 621 Channel region 222, 622 Source region 223, 623 Drain region 230 , 630 Gate insulating film 240, 640 Interlayer insulating film 250, 650 Planarization film 319, 516 Reference voltage power line 504a Anode 504b Light emitting layer 504c Transparent cathode 702 Holding capacitor 704 Light emitting element 707 Power line 708 First capacitor

Claims (14)

A substrate,
A semiconductor layer provided over the substrate and including a channel region, a source region, and a drain region, a gate insulating film provided on the semiconductor layer, a gate electrode provided on the gate insulating film, and the semiconductor A first thin film transistor including a source electrode and a drain electrode respectively electrically connected to the source region and the drain region of a layer;
A semiconductor layer provided over the substrate and including a channel region, a source region, and a drain region, a gate insulating film provided on the semiconductor layer, a gate electrode provided on the gate insulating film, and the semiconductor A second thin film transistor including a source electrode and a drain electrode respectively electrically connected to the source region and the drain region of a layer;
An interlayer insulating film provided on the gate electrode of the first thin film transistor and on the gate electrode of the second thin film transistor ;
A light emitting element driven to emit light by a driving circuit including the first thin film transistor and the second thin film transistor ;
A first capacitor electrode disposed in a region above the gate electrode of the first thin film transistor and on the interlayer insulating film;
The light emitting display device, wherein the first capacitor electrode forms a first capacitor with the gate electrode of the first thin film transistor, and is not connected to the source electrode and the drain electrode of the first thin film transistor .   A substrate,
  A semiconductor layer provided over the substrate and including a channel region, a source region, and a drain region, a gate insulating film provided on the semiconductor layer, a gate electrode provided on the gate insulating film, and the semiconductor A first thin film transistor including a source electrode and a drain electrode respectively electrically connected to the source region and the drain region of a layer;
  A semiconductor layer provided over the substrate and including a channel region, a source region, and a drain region, a gate insulating film provided on the semiconductor layer, a gate electrode provided on the gate insulating film, and the semiconductor A second thin film transistor including a source electrode and a drain electrode respectively electrically connected to the source region and the drain region of a layer;
  An interlayer insulating film provided on the gate electrode of the first thin film transistor and on the gate electrode of the second thin film transistor;
  A light emitting element driven to emit light by a driving circuit including the first thin film transistor and the second thin film transistor;
  A first capacitor electrode disposed in a region above the gate electrode of the first thin film transistor and on the interlayer insulating film;
  The first capacitor electrode forms a first capacitor with the gate electrode of the first thin film transistor, and is connected to either the source electrode or the drain electrode of the second thin film transistor.
  Luminescent display device. 3. The light-emitting display device according to claim 2 , wherein either one of the source electrode and the drain electrode of the second thin film transistor is connected to one of the source electrode and the drain electrode of the first thin film transistor. The first thin film transistor is a driving transistor that supplies a driving current to the light emitting element.
  The light emitting display device according to claim 1. The first thin film transistor is a switching transistor that determines timing for supplying a driving current to the light emitting element.
  The light emitting display device according to claim 1. The first capacitor is a capacitor for setting a current value flowing through the driving transistor.
  The light emitting display device according to claim 4. The first capacitor is a capacitor for initializing a capacitor for setting a current value of the driving current.
  The light emitting display device according to claim 5. The light emitting element is an organic electroluminescence element including a lower electrode, an organic light emitting layer, and an upper electrode,
The lower electrode is formed above a planarization film provided on the first capacitor electrode.
The light-emitting display device according to claim 1. The light emitting display device includes a plurality of the first capacitor electrodes,
The light emitting display device according to claim 1, wherein the plurality of first capacitor electrodes constitute a first capacitor with the gate electrode. The light emitting display device according to claim 1, wherein an area of the lower surface of the first capacitor electrode constituting the first capacitor in an upper region of the gate electrode is 30% to 100% of an area of the upper surface of the gate electrode. The light emitting display device according to claim 1, wherein the semiconductor layer is made of polysilicon. The light emitting display device according to claim 1, wherein the first capacitor has a capacitance of 0.1 to 10 pF. The light emitting display device is a top emission type,
The light emitting display device according to claim 1, wherein the light emitting element is formed on an upper layer of the first capacitor electrode. The light emitting display device is a bottom emission type,
The light emitting display device according to claim 1, wherein the thin film transistor and the first capacitor are formed in a region other than a light emitting region in which the light emitting element is formed.

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