JP2014110323A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device comprising a low-power-consumption, thin-film transistor 46.SOLUTION: A display device comprises a thin-film transistor 46 including a gate electrode 52, a semiconductor layer 54, a drain electrode 56, and a source electrode 58. Each of the drain electrode 56 and the source electrode 58 include margins 56c, 58c in an uneven contour shape formed of projections and depressions. The depressions of the drain electrode 56 and the projections of the source electrode 58 are opposed to each other, and the projections of the drain electrode 56 and the depressions of the source electrode 58 are opposed to each other. The drain electrode 56 includes a hollow 60 on a margin 56d opposite to the margin 56c in the uneven contour shape, so as to be adjacent to the projections.

Description

  The present invention relates to a display device.

  In a panel display such as a liquid crystal display panel or an organic electroluminescence panel, an image signal is controlled (on / off) by a thin film transistor and input to a pixel electrode. A scanning signal controlled (on / off) by another thin film transistor provided in a scanning circuit (gate circuit) is input to the gate of the thin film transistor (Patent Document 1).

JP 2006-80472 A

  In recent years, low power consumption has been cited as a performance required for panel displays. A thin film transistor consumes power by charging and discharging a parasitic capacitance formed between a gate and a drain. Therefore, it is desired to suppress the power consumption.

  An object of the present invention is to provide a display device including a thin film transistor with low power consumption.

  (1) A display device according to the present invention includes a thin film transistor having a gate electrode, a semiconductor layer, a drain electrode, and a source electrode, and the drain electrode and the source electrode have concave and convex contour sides, respectively. Having an edge, the concave portion of the drain electrode and the convex portion of the source electrode are opposed, the convex portion of the drain electrode and the concave portion of the source electrode are opposed, and at least one of the drain electrode and the source electrode is The concave and convex outlines have depressions on the side edges opposite to the side edges so as to be adjacent to the projections. According to the present invention, the depression is formed in at least one of the drain electrode and the source electrode, thereby reducing the area. Thereby, since the parasitic capacitance formed between the gate electrodes can be reduced, the charge / discharge current can be reduced and the power consumption can be reduced.

  (2) In the display device described in (1), the drain electrode and the source electrode may be arranged so as to face each other with a gap therebetween.

  (3) In the display device described in (1), the first electrode which is one of the drain electrode and the source electrode is disposed so as to surround the second electrode which is the other, and the second electrode is The side edge having the concave and convex contour shape and the side edge having the depression are opposite to each other, and the first electrode faces the side edge of the concave and convex contour shape of the second electrode. It is good also as having the said side edge of the contour shape of the above-mentioned unevenness.

  (4) In the display device described in any one of (1) to (3), a direction in which the recess is recessed may be a direction in which the protrusion protrudes.

  (5) A display device according to the present invention includes a thin film transistor having a gate electrode, a semiconductor layer, a drain electrode, and a source electrode, and the drain electrode and the source electrode each have a backbone portion and a plurality of branches branched from the backbone portion. A branch portion of the drain electrode, and the backbone portions of the drain electrode and the source electrode are respectively arranged in parallel with a space therebetween, and the plurality of branch portions of the drain electrode are connected to the backbone portion of the source electrode. The plurality of branch portions of the source electrode extend in a direction approaching the backbone portion of the drain electrode, and the plurality of branch portions of the drain electrode and the plurality of branch portions of the source electrode are alternately arranged. The at least one backbone portion of the drain electrode and the source electrode is a portion where the plurality of branch portions are provided and the plurality of branch portions. Characterized in that it is in a plane shape having a recess on the other side. According to the present invention, the depression is formed in at least one of the drain electrode and the source electrode, thereby reducing the area. Thereby, since the parasitic capacitance formed between the gate electrodes can be reduced, the charge / discharge current can be reduced and the power consumption can be reduced.

  (6) In the display device described in (5), the direction in which the recess is recessed may be a direction in which the plurality of branch portions extend from the backbone portion.

  (7) In the display device described in any one of (1) to (6), only one of the drain electrode and the source electrode may have the depression.

  (8) In the display device described in (7), the thin film transistor is configured such that a carrier is an electron, the carrier moves from the source electrode to the drain electrode, and the drain electrode has the depression. This may be a feature.

It is sectional drawing which shows the display apparatus which concerns on embodiment of this invention. It is a figure which shows a part of circuit of the display apparatus which concerns on this embodiment. It is sectional drawing of the display apparatus in the position which shows the thin-film transistor of a scanning circuit. It is a top view of the thin-film transistor of a scanning circuit. It is a figure which shows the modification of the display apparatus which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a display device according to an embodiment of the present invention. The display device shown in FIG. 1 is a liquid crystal display device, but the display device according to the present invention can be applied to other organic electroluminescence display devices.

  The display device includes a first substrate 10. A black matrix 12, a color filter 14, a planarizing layer 16, and a first alignment film 18 are stacked on the first substrate 10 to constitute a color filter substrate. A second alignment film 20 is disposed facing the first alignment film 18 with a cell gap. A liquid crystal material 22 is disposed between the first alignment film 18 and the second alignment film 20.

  FIG. 2 is a diagram illustrating a part of the circuit of the display device according to the present embodiment. The display device has an image display area 24 for displaying an image. The image display area 24 is provided with a thin film transistor 26 for controlling the application of voltage to the liquid crystal material 22. Specifically, a video signal applied to the signal line 32 is controlled by a scanning signal (clock signal) applied to the scanning line 30 connected to the gate electrode 28 (see FIG. 1) of the thin film transistor 26. Then, the liquid crystal material 22 is driven by the voltage of the video signal.

  As shown in FIG. 1, the gate electrode 28 of the thin film transistor 26 is formed on the second substrate 34. The thin film transistor 26 is a bottom gate type. The second substrate 34 on which the thin film transistor 26 is formed is called a TFT (Thin Film Transistor) substrate. The gate electrode 28 is formed of an element selected from aluminum, molybdenum, chromium, copper, tungsten, titanium, zirconium, tantalum, silver, and manganese, or an alloy that combines these elements. Alternatively, a laminated structure in which aluminum is laminated on titanium, or an upper layer and a lower layer of aluminum are sandwiched between titanium may be employed.

  The display device has a gate insulating film 36. The gate insulating film 36 is provided on the second substrate 34 so as to cover the gate electrode 28. The gate insulating film 36 can be formed of an insulating film such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film, and may have a structure in which these insulating films are stacked.

  A semiconductor layer 38 is provided on the gate insulating film 36. A source electrode 40 and a drain electrode 42 are provided so as to be in contact with the source region and the drain region of the semiconductor layer 38, respectively. The source electrode 40 and the drain electrode 42 are formed of a material that can be selected as the gate electrode 28 described above, and may be formed of the same material as the gate electrode 28.

  The display device has a passivation layer 44. The passivation layer 44 may be formed of an insulating film such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film, or may be formed by stacking these insulating films. The passivation layer 44 is provided on the source electrode 40 and the drain electrode 42. A second alignment film 20 is formed on the passivation layer 44.

  As shown in FIG. 2, a thin film transistor 46 for controlling (ON / OFF) a scanning signal (clock signal) applied to the scanning line 30 is provided in a peripheral region outside the pixel display region. A scanning circuit 48 is configured to have a plurality of thin film transistors 46.

  FIG. 3 is a cross-sectional view of the display device at a position showing the thin film transistor 46 of the scanning circuit 48. As shown in FIG. 2, the scanning circuit 48 is outside the image display area 24, and a sealing material 50 (see FIG. 3) for sealing the liquid crystal material 22 shown in FIG. 1 is provided in the scanning circuit 48 (see FIG. 2). It is provided so as to overlap. The sealing material 50 is provided between the first alignment film 18 and the second alignment film 20.

  FIG. 4 is a plan view of the thin film transistor 46 of the scanning circuit 48. The thin film transistor 46 includes a gate electrode 52, a semiconductor layer 54, a drain electrode 56, and a source electrode 58.

  The drain electrode 56 and the source electrode 58 are disposed so as to face each other with a space therebetween. The drain electrode 56 has a trunk portion 56a. The source electrode 58 has a backbone 58a. The trunk portions 56a and 56b of the drain electrode 56 and the source electrode 58 are parallel to each other with a gap therebetween.

  The drain electrode 56 has a plurality of branch portions 56b branched from the backbone portion 56a. The plurality of branch portions 56 b of the drain electrode 56 extend in a direction approaching the trunk portion 58 a of the source electrode 58. The drain electrode 56 has an uneven contour side edge 56c so that the branch portion 56b is convex and the portion of the trunk portion 56a where the branch portion 56b does not exist is concave.

  The source electrode 58 has a plurality of branch portions 58b branched from the backbone portion 58a. The plurality of branch portions 58 b of the source electrode 58 extend in a direction approaching the trunk portion 56 a of the drain electrode 56. The source electrode 58 has a concave and convex contoured side edge 58c so that the branch portion 58b is convex and the portion of the trunk portion 58a where the branch portion 58b does not exist is concave.

  The plurality of branch portions 56b of the drain electrode 56 and the plurality of branch portions 58b of the source electrode 58 are alternately arranged. Therefore, the concave of the drain electrode 56 and the convex of the source electrode 58 face each other, and the convex of the drain electrode 56 and the concave of the source electrode 58 face each other.

  At least one of the drain electrode 56 and the source electrode 58 (only the drain electrode 56 in FIG. 4) is adjacent to the projection (branch portion 56b) on the side edge 56d opposite to the side edge 56c of the contoured shape of the projections and depressions. Has a recess 60 (or notch). Only one of the drain electrode 56 and the source electrode 58 has a recess 60. The direction in which the dent 60 is recessed is the direction in which the protrusion protrudes. In other words, the trunk portion 56a of at least one of the drain electrode 56 and the source electrode 58 (only the drain electrode 56 in FIG. 4) is a recess 60 on the side opposite to the plurality of branch portions 56b at a portion where the plurality of branch portions 56b are provided. Has a planar shape. The direction in which the recess 60 is recessed is a direction in which the plurality of branch portions 56b extend from the trunk portion 56a.

  According to the present embodiment, the depression 60 is formed in at least one of the drain electrode 56 and the source electrode 58, thereby reducing the area. Thereby, since the parasitic capacitance formed between the gate electrode 52 can be reduced, the charge / discharge current can be reduced and the power consumption can be reduced.

  In the present embodiment, the thin film transistor 46 is configured such that carriers moving from the source electrode 58 to the drain electrode 56 become electrons. On the contrary, the flow of current is from the drain electrode 56 to the source electrode 58, and a HIGH scanning signal (clock signal) is input to the scanning line 30.

  In the present embodiment, the drain electrode 56 has the depression 60 and the source electrode 58 does not have the depression 60. By forming the depression 60 in the drain electrode 56, the contact resistance between the drain electrode 56 and the semiconductor layer 54 increases, so that the effective voltage between the gate and the drain applied to the channel formed in the semiconductor layer 54 decreases. On the other hand, since the recess 60 is not formed in the source electrode 58, the contact resistance between the source electrode 58 and the semiconductor layer 54 does not increase (relatively small), and the effective voltage between the gate and the source applied to the channel is low. Not (relatively high). Since the effective voltage between the gate and the drain is higher than the effective voltage between the gate and the source, a current (clock signal) easily flows from the drain electrode 56 to the source electrode 58. In addition, since the effective voltage between the source and the drain can be increased, it is possible to prevent the voltage change from being reduced.

  FIG. 5 is a diagram showing a modification of the display device according to the embodiment of the present invention. In this modification, the source electrode 158 is disposed so as to surround the drain electrode 156. The drain electrode 156 has a side edge 156c having a concave and convex contour shape and a side edge 156d having a depression 160 on opposite sides. The side edge 158 c of the contoured shape of the source electrode 158 faces the side edge 156 c of the contoured shape of the drain electrode 156. Also in this modification, the above-described effect is achieved by forming the depression 160. Note that the source electrode 158 and the drain electrode 156 may be interchanged so that the drain electrode surrounds the source electrode. The other details correspond to the contents described in the above-described embodiment.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the configuration described in the embodiment can be replaced with substantially the same configuration, a configuration that exhibits the same operational effects, or a configuration that can achieve the same purpose.

  10 First substrate, 12 Black matrix, 14 Color filter, 16 Planarization layer, 18 First alignment film, 20 Second alignment film, 22 Liquid crystal material, 24 Image display area, 26 Thin film transistor, 28 Gate electrode, 30 Scan line, 32 signal lines, 34 second substrate, 36 gate insulating film, 38 semiconductor layer, 40 source electrode, 42 drain electrode, 44 passivation layer, 46 thin film transistor, 48 scanning circuit, 50 sealing material, 52 gate electrode, 54 semiconductor layer, 56 Drain electrode, 56a backbone, 56b branch, 56c uneven side edge, 56d opposite side edge, 58 source electrode, 58a backbone, 58b multiple branches, 58c uneven side edge, 60 Depression, 156 Drain electrode, 156c Side edge of concave / convex contour shape, 156 d Side edge of opposite side, 158 source electrode, side edge of contoured shape of 158 c, 160 depression.

Claims (8)

A thin film transistor having a gate electrode, a semiconductor layer, a drain electrode and a source electrode;
The drain electrode and the source electrode each have a concave and convex contoured side edge that is concave and convex,
The concave portion of the drain electrode and the convex portion of the source electrode are opposed to each other,
The projection of the drain electrode and the recess of the source electrode are opposed to each other;
At least one of the drain electrode and the source electrode has a depression at a side edge opposite to the side edge of the uneven contour shape so as to be adjacent to the projection. The display device according to claim 1,
The display device, wherein the drain electrode and the source electrode are disposed so as to face each other with a space therebetween. The display device according to claim 1,
The first electrode which is one of the drain electrode and the source electrode is disposed so as to surround the second electrode which is the other,
The second electrode has the side edges of the uneven contour shape and the side edges having the depressions on opposite sides,
The display device according to claim 1, wherein the first electrode has the side edge of the concave / convex contour shape so as to face the side edge of the concave / convex contour shape of the second electrode. The display device according to any one of claims 1 to 3,
The direction in which the dent is recessed is the direction in which the protrusion protrudes. A thin film transistor having a gate electrode, a semiconductor layer, a drain electrode and a source electrode;
Each of the drain electrode and the source electrode has a backbone portion and a plurality of branch portions branching from the backbone portion,
The backbone portions of the drain electrode and the source electrode are respectively arranged in parallel with a gap therebetween,
The plurality of branch portions of the drain electrode extend in a direction approaching the backbone portion of the source electrode,
The plurality of branch portions of the source electrode extend in a direction approaching the backbone portion of the drain electrode,
The plurality of branches of the drain electrode and the plurality of branches of the source electrode are alternately arranged,
The trunk portion of at least one of the drain electrode and the source electrode has a planar shape having depressions on a side opposite to the plurality of branch portions at a portion where the plurality of branch portions are provided. Display device. The display device according to claim 5,
The direction in which the dent is recessed is a direction in which the plurality of branch parts extend from the backbone part. The display device according to any one of claims 1 to 6,
Only one of the drain electrode and the source electrode has the depression. The display device according to claim 7,
The thin film transistor is configured such that the carrier is an electron,
The carriers move from the source electrode to the drain electrode;
The display device, wherein the drain electrode has the depression.

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