TWI417626B - Pixel structure - Google Patents

Description

Pixel structure

The present invention relates to a pixel structure of a liquid crystal display device, and more particularly to a pixel structure that can compensate for parasitic capacitance without reducing the aperture ratio.

A general thin film transistor liquid crystal display is mainly composed of a thin film transistor array substrate, a pair of substrates, and a liquid crystal layer sandwiched between the two substrates. The thin film transistor array substrate mainly comprises a plurality of scan lines, a plurality of data lines, a thin film transistor arranged between the scan lines and the data lines, and a pixel electrode (Pixel Electrode) arranged corresponding to each of the thin film transistors. The above thin film transistor includes a gate electrode, a semiconductor layer, a source and a drain, and is used as a switching element of a liquid crystal display unit.

The fabrication process of a thin film transistor array substrate typically involves multiple development and etching steps. In general manufacturing techniques, the gate and scan lines are the first metal layer (Metal 1), and the source, drain and data lines are the second metal layer (Metal 2). Moreover, there is at least one gate insulating layer between the first metal layer and the second metal layer. In the structure of the thin film transistor, the gate and the drain are at least partially overlapped, so that there is usually a so-called gate-drain parasitic capacitance (hereinafter referred to as Cgd) between the gate and the drain.

In the case of a liquid crystal display, there is a specific relationship between the voltage applied to the liquid crystal capacitor Clc and the light transmittance of the liquid crystal molecules. Therefore, as long as the voltage applied to the liquid crystal capacitor Clc is controlled according to the picture to be displayed, the display can be displayed in a predetermined picture. surface. However, due to the existence of the gate-drain parasitic capacitance Cgd, the voltage held on the liquid crystal capacitor Clc will change as the voltage on the scan line changes. This voltage fluctuation amount is called a feed-through voltage ΔVp, which can be expressed as a formula (1): ΔVp=[Cgd/(Clc+Cgd+Cst)](Vgon-Vgoff) (1)

Vgon-Vgoff is the voltage change on the scan line, and Cst is the storage capacitor.

In current active component array processes, the alignment step is offset due to machine movement to cause differences in the relative positions of the various components. In particular, when the overlap area of the gate and the drain is different, the gate-drain parasitic capacitance Cgd of the pixel of the same panel is different. In this way, different display pixels of the same panel have different feedthrough voltages ΔVp, thereby causing a problem of uneven display brightness during display.

In order to improve the negative effects caused by the variation of the gate-drain parasitic capacitance Cgd, Chinese Patent Publication No. CN101750826 proposes a pixel structure for improving the gate-drain parasitic capacitance Cgd. 1 is a partial top view of a Chinese patent publication CN101750826 pixel structure. Referring to FIG. 1, the pixel structure 100 includes a scan line 110, a data line 120, a gate 130, a semiconductor layer 140, and a source. The pole 150, a drain 160 and a pixel electrode 170. The scan lines 110 and the data lines 120 are staggered and electrically insulated from each other. The gate 130 is connected to the scan line 110. The semiconductor layer 140 is located above the gate 130. The source 150 and the drain 160 are at least partially located on the gate 130, and the source 150 is connected to the data line 120. In this patent, gate 130, semiconductor layer 140, source 150, and drain 160 may form a thin film transistor (not labeled). The pixel electrode 170 is electrically connected to the drain 160 to receive the data line 120 through the opening or closing of the thin film transistor. The signal transmitted on it.

The drain 160 includes a comb portion 162 surrounding the source 150 and a connecting portion 166. The comb portion 162 has a first branch 162a, a second branch 162b, and a strip-shaped bottom 162c. One end of the connecting portion 166 is connected to the strip bottom portion 162c, and the other end protrudes away from the gate 130 away from the direction d. Therefore, the connecting portion 166 partially overlaps the gate 130. The second branch 162b extends beyond the gate 130 to define a projection 164 that is external to the gate 130, and the projection 164 has the same width as the portion of the second branch 162b that does not extend beyond the gate 130. The protruding portion 164 and the connecting portion 166 are respectively located on opposite sides of the gate 130. Thus, when the machine moves to cause the alignment step to shift in a direction opposite to the d direction to reduce the overlap area of the connection portion 166 and the gate 130, the second branch 162b protrudes due to the presence of the protrusion 164. The overlap area of the branch 162b and the gate 130 is increased, and therefore, the total gate-drain overlap area does not change too much due to the offset caused by the alignment step, and thus the total gate-drain parasitic capacitance does not occur. Too large change; when the alignment step produces an offset in the d direction such that the area of overlap of the connection portion 166 with the gate 130 increases, the second branch 162b and the gate are present due to the presence of the protrusion 164 of the second branch 162b The overlap area of 130 is reduced, so that the total gate-drain overlap area does not change too much due to the offset caused by the alignment step, so the total gate-drain parasitic capacitance does not change much. . Therefore, the pixel structure 100 of the previous case can effectively compensate the gate-drain parasitic capacitance.

In general, there will be a certain distance between the gate and the data line, assuming the spacing is w. In the above-described pixel structure 100 design, due to the presence of the protrusion 164 of the second branch 162b, in order to avoid short circuit between the protrusion 164 and the data line 120, the gate is The spacing between the pole 130 and the data line 120 must be greater than w, and thus the area between the gate 130 and the data line 120 is increased. Since the gate 130 and the area between the gate 130 and the data line 120 are generally opaque, and the area between the gate 140 and the data line 120 is enlarged in the pixel structure 100, the present case is The pixel structure 100 has a reduced aperture ratio relative to a general pixel structure, and thus the display quality of the liquid crystal display device is lowered.

In order to overcome the problems in the prior art, the present invention provides a pixel structure of a liquid crystal display device.

The present invention provides a pixel structure of a liquid crystal display device, comprising: a scan line and a data line, which are staggered and electrically insulated from each other; a gate electrically connected to the scan line; and a source, at least partially located on the gate and connected to the data a drain electrode is disposed at least partially on the gate and opposite to the source; the pixel electrode includes a body portion and an extension portion, the body portion is electrically connected to the drain, and the extension portion is electrically connected to the body portion, and The extension overlaps the gate and the drain.

In an embodiment of the invention, the extension portion includes an extension electrode and an extension branch, and the extension electrode is electrically connected to the body portion and the extension branch.

In an embodiment of the invention, the extension electrode and the extension branch substantially form an "L" shape, the vertical portion is an extension electrode, the lateral portion is an extension branch, and the extension branch portion overlaps the gate and the drain portion.

In an embodiment of the invention, the drain is a comb electrode comprising: a comb portion, the comb portion being configured as a Shape, and further includes a bottom and two branches, the two branches are connected to the bottom; the connecting portion has one end connected to the bottom and the other end electrically connected to the main body of the pixel electrode.

In an embodiment of the invention, one of the branches of the comb portion overlaps the extended branch portion and is smaller than the width of the extended branch. The width of the branch of the comb is 1.4 times the width of the joint.

In an embodiment of the invention, one of the branches of the comb portion overlaps with the extended branch portion and is greater than or equal to the extended branch. The width of the extended branch is 1.4 times the width of the joint.

In an embodiment of the invention, the extension electrode and the extended branch substantially constitute " The vertical portion is an extended electrode, the lateral portion is two extended branches, and the two extended branches partially overlap the drain.

In an embodiment of the invention, the two branches overlap with the two extended branch portions, respectively. In one embodiment of the invention, the sum of the widths of the two branches is substantially 1.4 times the width of the joint.

In an embodiment of the invention, the width of one end of the extended branch connection extension electrode is smaller than the end of the extension electrode.

In an embodiment of the invention, the extending portion includes an overlapping portion and a non-overlapping portion, the overlapping portion is overlapped with the gate and the drain, and the non-overlapping portion is connected to the main body portion and the overlapping portion. In one embodiment of the invention, a portion of the non-overlapping portion extends from the overlap portion beyond the drain in one direction to improve the error caused by the alignment step.

In an embodiment of the invention, the drain is a strip electrode, one end and the extension portion The overlap is overlapped, and the other end is electrically connected to the pixel electrode, and the width of one end of the overlap is greater than the width of the other end.

In an embodiment of the invention, the pixel structure further includes a contact electrode electrically connected to the drain and partially overlapping.

According to the above, the pixel electrode of the present invention has an extension portion, and the extension portion overlaps with the drain portion in the gate, and therefore, when the machine moves to cause an offset of the alignment step, because the extension portion and the extension portion The overlap area of the pole also changes accordingly. Therefore, the gate-drain parasitic capacitance Cgd can be compensated, thereby improving the problem that the different pixel gate-drain parasitic capacitance Cgd is different, thereby improving the uneven brightness of the screen. . In addition, since the extension portion and the data line are not in the same layer and are electrically insulated, the problem of short circuit does not occur even if the two are overlapped. Therefore, the present invention does not need to increase the width between the gate and the data line relative to the previous case. Therefore, the aperture ratio of the present invention is not reduced.

The above described features and advantages of the invention will be apparent from the following description.

200, 300, 400, 500, 600, 700, 800, 900‧‧‧ pixel structure

210, 710‧‧‧ scan lines

220, 720‧‧‧ data lines

230, 730‧‧ ‧ gate

240, 740‧‧‧ semiconductor layer

250, 750‧‧‧ source

260, 360, 760, 860‧ ‧ 汲 bungee

261‧‧‧ first end

262, 362, 762, 862‧‧ ‧ combing department

First branch of 262a, 362a, 762a‧‧

Second branch of 262b, 362b, 762b‧‧

262c, 362c, 762c‧‧‧ bottom

266, 366, 766, 866‧‧‧ Connections

267‧‧‧ second end

270, 470, 570, 670, 770, 970 ‧ ‧ pixel electrodes

271, 471, 571, 671, 771, 971 ‧ ‧ main body

272, 472, 572, 672, 772, 972 ‧ ‧ extensions

272a, 472a, 572a, 672a, 772a, 972a‧‧‧ extended electrodes

272c, 472c, 572c, 672c, 772c, 972c‧‧‧ extended branches

281, 781‧‧‧ contact holes

282‧‧‧gate insulation

283‧‧‧ Passivation layer

2711‧‧‧Extension

Figure 1 is a partial top plan view of a conventional technical pixel structure.

Fig. 2 is a partial plan view showing the pixel structure of the first embodiment of the present invention.

Fig. 3 is a partial top plan view showing a pixel structure of a second embodiment of the present invention.

Figure 4 is a cross-sectional view of the third picture element structure taken along line A-A.

Fig. 5 is a partial plan view showing a pixel structure of a third embodiment of the present invention.

Figure 6 is a partial top plan view showing a pixel structure of a fourth embodiment of the present invention.

Figure 7 is a partial top plan view showing a pixel structure of a fifth embodiment of the present invention.

Figure 8 is a partial top plan view showing a pixel structure of a sixth embodiment of the present invention.

Figure 9 is a partial top plan view showing a pixel structure of a seventh embodiment of the present invention.

Fig. 10 is a partial plan view showing the pixel structure of the eighth embodiment of the present invention.

First embodiment

2 is a partial top plan view of a pixel structure according to a first embodiment of the present invention. Referring to FIG. 2, the pixel structure 200 includes a scan line 210, a data line 220, a gate 230, a semiconductor layer 240, and a pixel structure. A source 250, a drain 260, and a pixel electrode 270. Scan line 210 and data line 220 are staggered and electrically insulated from each other. The gate 230 and the scan line 210 are first metal layers, and the gate 230 is electrically connected to the scan line 210. The semiconductor layer 240 is located above the gate 230. The data line 220, the source 250 and the drain 260 are second metal layers, and the source 250 is electrically connected to the data line 220, and the source 250 and the drain 260 are at least partially located on the gate 230. In this embodiment, the gate 230, the semiconductor layer 240, the source 250, and the drain 260 may constitute a thin film transistor (not labeled). The pixel electrode 270 is electrically connected to the drain 260 to receive the signal transmitted on the data line 220 through the opening or closing of the thin film transistor.

The drain 260 includes a first end 261, a connecting portion 266, and a second end 267. In the present embodiment, the first end 261 is a comb portion 262 that surrounds the source 250. In a modified embodiment, the comb portion 266 may have other shapes. The comb portion 262 is completely disposed within the gate 230, and the comb portion 262 has a first branch 262a, a second branch 262b, and a strip bottom 262c. That is, the comb portion 262 is " The first branch 262a and the second branch 262b extend from both ends of the strip bottom 262c in the direction D to surround the comb portion 262 around the source 250. One end of the connecting portion 266 is connected to the strip bottom 262c, and the other end Then, the deviation direction D extends beyond the gate 230, and therefore, the connection portion 266 partially overlaps the gate 230. In the embodiment, the width of the first branch 262a is equal to the width of the second branch 262b, and is equal to the connection portion. Width of 266.

In order to improve the problem that the alignment step is shifted due to the movement of the machine in the previous case to cause different pixels to have different gate-drain parasitic capacitance Cgd, thereby generating a problem of display brightness non-uniformity, this embodiment proposes A pixel electrode 270 is designed to improve such defects, and its design concept is as follows.

The pixel electrode 270 includes a body portion 271 and an extension portion 272 which are made of the same material as the extension portion 272 and which are formed by the same mask process. The body portion 271 includes an extended end 2711. The extended end 2711 extends and opposes the extension 272 in the same direction. The extending end 2711 of the main body portion 271 is electrically connected to the second end 267 of the drain 260 through a contact hole 281, and the two ends 267 overlap the extending end 2711 in a plane and do not protrude. At the extended end 2711. The first end 261 overlaps the extension 272 in a plane and does not protrude from the extension 272. The extension portion 272 includes an extension electrode 272a and an extension branch 272c. The extension electrode 272a and the extension branch 272c substantially form an "L" shape, the vertical portion of which is the extension electrode 272a, and the lateral portion is the extension branch 272c. The extension electrode 272a is located between the main body portion 271 and the extended branch 272c and is electrically connected to the two. The extension branch 272c extends from the end of the extension electrode 272a away from the body portion 271 in a direction away from the direction D to partially overlap the first branch 262a of the gate 230 and the drain 260. Also That is, the extended branch 272a has an overlapping portion and a non-overlapping portion, and the overlapping portion is a region where the extended branch 272c overlaps with the drain 260, and the overlapping portion is located within the range formed by the gate 230; the non-overlapping portion is the overlapping portion Other than the extended branch 272c, and a portion of the non-overlapping portion extends from the overlapping portion in the D direction beyond the first branch 262a and overlaps the gate 230, and those skilled in the art should understand that the width of the portion in the D direction is greater than or equal to the machine. The range of offsets.

As can be seen from the above description, both the pixel electrode 270 and the drain 260 overlap with the gate 230, and the pixel electrode 270 and the drain 260 are electrically connected. Therefore, the gate-drain parasitic capacitance Cgd includes the comb portion 262. The parasitic capacitance generated by the overlap with the gate 230, the parasitic capacitance generated by the overlap of the connection portion 266 and the gate 230, and the parasitic capacitance caused by the overlap of the extended electrode 272a of the pixel electrode 270 and the gate 230, and the extension branch 272c overlap with the gate 230 The parasitic capacitance generated. In addition, since the overlapping portion is in the gate 230 and the first branch 262a of the drain 260 exists between the overlapping portion and the gate 230, there is no extended branch 272c and gate 230 at the overlapping portion of the extended branch 272c. The parasitic capacitance has only the parasitic capacitance of the first branch 262a and the gate 230. In other words, the parasitic capacitance of the extended branch 272c and the gate 230 has only a parasitic capacitance in which the non-overlapping portion and the gate 230 overlap. Therefore, the total gate-drain parasitic capacitance Cgd includes a parasitic capacitance in which the comb portion 262 overlaps the gate 230, a parasitic capacitance in which the connection portion 266 overlaps the gate 230, and a parasitic overlap of the extension electrode 272a and the gate 230. The parasitic capacitance generated by the overlap of the non-overlapping portion of the capacitor and the extended branch 272c and the gate 230.

When the alignment step is offset due to the movement of the machine to cause the second metal layer to be offset in the direction D, then the positional relationship of the data line 220, the source 250, and the drain 260 with respect to the gate 230 is actually As shown by the dotted line (only draws the bottom 260 as a dotted line) . That is, the data line 220, the source 250, and the drain 260 are integrally translated relative to the gate 230 toward the left side of the drawing, that is, toward the direction D. Since the connection portion 266 of the drain 260 causes an area which overlaps with the gate 230 due to the left shift, the parasitic capacitance of the connection portion 266 and the gate 230 increases. The comb portion 262 is also shifted to the left, but since it is always in the gate 230, the parasitic capacitance of the comb portion 262 and the gate 230 does not change. On the other hand, the extended branch 272c of the extension electrode 272 causes the overlapping portion area to increase due to the leftward movement of the first branch 262a of the drain 260. Therefore, the parasitic capacitance of the non-overlapping portion of the extended branch 272c and the gate 230 is reduced. Since the overlapping area of the extension electrode 272a and the gate 230 does not change, the parasitic capacitance of both does not change. Therefore, in the present embodiment, the amount of decrease in the parasitic capacitance of the extension branch 272c and the gate 230 compensates for the increase in the parasitic capacitance of the connection portion 266 and the gate 230, and thus the gate-drain parasitic capacitance Cgd is compensated. The problem that the different pixel gate-drain parasitic capacitance Cgd is different due to the offset of the alignment step caused by the movement of the machine is improved. Vice versa, the uneven brightness of the picture caused by the difference in gate-drain parasitic capacitance of different pixels is improved.

Moreover, in the pixel structure 200, since the comb portion 262 is completely placed in the region of the gate 230, there is no case where the branch appearing in the front case protrudes beyond the gate, and the pixel electrode 270 and the data line 220 are not At the same layer, the skilled artisan can understand that there is a passivation layer (not shown) between the two. Therefore, even if the pixel electrode 270 and the data line 220 overlap, it does not matter. Therefore, the gate 230 of the pixel structure 200 is not included. The spacing between the data lines 220 and the data line 220 can be the same as that of the general pixel structure, that is, the pitch is w. Therefore, the pixel structure 200 of the present embodiment does not suffer from the problem of a decrease in the aperture ratio mentioned in the foregoing.

In addition, in the present embodiment, the extension branches 272c are equal in width and larger than each other. Or equal to the width of the first branch 262a, therefore, the extension electrode 272c may completely cover the first branch 262a in the region of the overlap. Of course, the embodiment is not limited thereto, and the extension electrode 272c may not completely cover the first branch 262a in the region of the overlapping portion, that is, only partially cover the first branch 262a, as long as the two overlap, the gate-dip parasite is reached. The effect of capacitance compensation. The width of the extended branch 272c is not limited to be greater than or equal to the width of the first branch 262a, and the width of the extended branch 272c may be smaller than the width of the first branch 262a.

Moreover, the width of the first branch 262a is not limited to be equal to the width of the second branch 262c, and the width of the connecting portion 266 is not limited to be equal to the width of any one of the two branches, and the implementation of the first branch 262a larger than the connecting branch 262b will be described below. example.

Second embodiment

Fig. 3 is a partial top plan view showing a pixel structure according to a second embodiment of the present invention. The pixel structure of Fig. 3 is similar to the pixel structure of Fig. 2, and therefore the same reference numerals denote the same elements. The difference between this embodiment and the first embodiment is the design of the drain 360 of the pixel structure 300.

Specifically, the difference between the drain 360 of the present embodiment and the first embodiment 260 is that the width W1 of the first branch 362a of the comb portion 362 is not equal to the width W3 of the connecting portion, and the relationship is satisfied: W1 is substantially 1.4 times W3. When the width W1 of the first branch 362a and the width W3 of the connection portion satisfy the relationship, the amount of change in the parasitic capacitance of the gate 230 and the extended branch 272c can be obtained equal to the amount of change in the parasitic capacitance of the gate 230 and the connection portion 366, and thus The pixel structure 300 can keep the gate-drain parasitic capacitance Cgd equal to our pre-designed value, so the embodiment can further improve the liquid crystal display device screen Uniformity of brightness.

The origin of the above relationship of the width W1 of the first branch 362a and the width W2 of the connecting portion 366 will be described in detail below. Figure 4 is a cross-sectional view of the third picture element structure taken along line AA. Referring to Figure 4, there is generally a gate insulating layer 282 between the gate 230 and the semiconductor layer 240, so that the drain 360 and the gate are in the region of the gate 230. There is a gate insulating layer 282 and a semiconductor layer 240 between the electrodes 230; a passivation layer 283 is generally disposed between the drain 360 and the pixel electrode 270, so that a gate insulating layer 282 is generally present between the extended branch 272c and the gate 230. Semiconductor layer 240 and passivation layer 283. In general, the thickness d1 of the gate insulating layer 282 is about 3300 A, the relative permittivity ( _r1 is about 7 F/cm; the thickness d2 of the semiconductor layer 240 is about 2000 A, and the relative permittivity ( _r2 is about 11 F/cm; the passivation layer) The thickness of 283 is d3 is 2000A, and the relative permittivity ( _r3 is about 7F/cm. In addition, the permittivity ε ₀ of air is 1F/cm. Therefore, according to the formula for calculating capacitance C: C=ε _r ε ₀ ^* A/ d, (2)

Where A is the facing area of the two metals, d is the distance between the two metals, ε _r is the relative permittivity, and ε ₀ is the permittivity of the air.

And the total capacitance C ₀ of the two series capacitors C ₀₁ and C ₀₂ is: 1/C ₀ =1/C ₀₁ +1/C ₀₂ (3)

Please refer to FIG. 3 and FIG. 4 simultaneously, when the alignment step is offset due to the movement of the machine to cause the second metal layer to generate a length offset of, for example, Δd in the direction D, the connecting portion 266 and the comb The profile 362 is also offset to the left by the length of Δd. When the connecting portion 266 is shifted to the left by the length of Δd, the overlapping area of the connecting portion 266 and the gate 230 is increased by Δd ^* W3. The comb portion 362 is shifted to the left by the length of Δd, the first branch 362a is also shifted to the left by the length of Δd, and the overlapping portion of the extended branch 272c is also increased by the length of Δd because the extended branch 272c is Since the overlapping portion area completely covers the first branch 362a, the area of the overlapping portion of the extended branch 272c is increased by Δd ^* W1, and therefore, the overlapping area of the non-overlapping portion of the extended branch 272c and the gate 230 is reduced by Δd ^* W1. Therefore, the parasitic capacitance of the connection portion 366 and the gate 230 increases, and the parasitic capacitance of the extension branch 272c and the gate 230 decreases, assuming that the increase in the parasitic capacitance of the connection portion 366 and the gate 230 is C1, the extension branch 272c and the gate The parasitic capacitance of 230 is reduced by C2. In order to keep the gate-drain parasitic capacitance Cgd constant, it is necessary to satisfy the relationship: C1 is equal to C2, according to the above formula (2) and formula (3), and given above. The conventional parameter information can be obtained by general mathematical calculation: W1 is substantially 1.4 times W3.

In addition, in the embodiment, the width of the second branch 362b of the drain may be equal to the width of the first branch 362a of the drain or may not be equal to the width of the first branch 362a. Moreover, the width of the extended branch 272c is greater than the width W1 of the first branch 362a, and the extended branch 272c completely covers the first branch 362a in the overlap region.

Third embodiment

Fig. 5 is a partial top plan view showing a pixel structure of a third embodiment of the present invention, and the pixel structure of Fig. 5 is similar to the pixel structure of Fig. 2, and therefore the same reference numerals denote the same elements. The difference between this embodiment and the first embodiment is the design of the pixel electrode 470 of the pixel structure 400.

Specifically, the difference between the pixel electrode 470 of the present embodiment and the pixel electrode 270 of the second embodiment is that the width W4 of the extended branch 472c of the pixel electrode 470 is smaller than the width W1 of the first branch 262a, and the overlapping portion of the extended branch 472c Completely placed in the first branch 262a, ie The first branch 262a completely covers the extended branch 472c in the region of the overlap. Also, the design of the present embodiment can improve the difference in gate-drain parasitic capacitance between different pixels due to offset.

In the case of offset, in order to achieve a better gate-drain parasitic capacitance compensation effect, also according to Embodiment 2, in the present embodiment, the width W1 of the extended branch satisfies the relationship with the width W3 of the connection portion: W1 is substantially 1.4 times W3.

Fourth embodiment

In the foregoing embodiment design, since the extension portion overlaps with the gate electrode, the gate-drain parasitic capacitance Cgd in each pixel structure is larger than the conventional pixel structure. Therefore, the present embodiment mainly focuses on this problem. improve.

6 is a partial top plan view of a pixel structure according to a fourth embodiment of the present invention, and the pixel structure of FIG. 6 is similar to the pixel structure of FIG. 2, and thus the same component symbols represent the same components, and this embodiment The difference of Embodiment 1 is the design of the extended branch 572c of the pixel structure 500.

Specifically, the difference between this embodiment and the second embodiment is that the width of the extension branch 572c is not completely the same, and the width W41 of the one end of the extension branch 572c connecting the extension electrode 572a is smaller than the width W42 of the other end, and the The other end partially overlaps the first branch 262a and completely covers the first branch 562a in the overlap region. In the present embodiment, the smaller the width W41, the better, as long as the electrical property can be better transmitted to the overlapping portion.

Continuing to refer to FIG. 6, the extension branch 572c of the present embodiment is widened by the width W41 until the W42 is not a gradual process, but is mutated from W41 to W42 at one point of the non-overlapping portion. In addition In other embodiments of the present invention, it will be understood by those skilled in the art that a process in which the extension branch 572c is widened from the width W41 to W42 is a gradation, as long as the overlap of the extended branch 572c and the gate 230 can be reduced. Just fine. Moreover, in other embodiments, the object of the embodiment can also be achieved by reducing the width of the extension electrode 572a.

With such a design, since the overlapping area of the extended branch 572c and the gate 230 is smaller than that of the previous embodiment, the gate-drain parasitic capacitance Cgd in this embodiment is smaller than that of the gate-汲 in the previous embodiment. The parasitic capacitance, as well, the design of this embodiment can improve the difference in gate-drain parasitic capacitance between different pixels due to offset.

Fifth embodiment

Fig. 7 is a partial plan view showing the pixel structure of the fifth embodiment of the present invention, and the pixel structure of Fig. 7 is similar to the pixel structure of Fig. 2, and therefore the same reference numerals denote the same elements. The difference between this embodiment and the first embodiment is the design of the extension 672 of the pixel structure 600.

Specifically, in the embodiment, the extension of the pixel electrode 670 includes an extension electrode 672a, a first extension branch 672c, and a second extension branch 672d. The extension electrode 672a, the first extension branch 672c, and the second extension branch 672d substantially constitute a "" The vertical portion is an extension electrode 672a, and the two lateral portions are a first extension branch 672c and a second extension branch 672d, respectively. The extension electrode 672a is located between the main body portion 671 and the second extension branch 672d and is respectively associated with the main body portion. The first extension branch 672c and the second extension branch 672d are electrically connected. The first extension branch 672c and the second extension branch 672d respectively extend from the extension electrode 672a in a direction away from the direction D to partially overlap the gate 230 and the drain 260. And the first extended branch 672c partially overlaps the first branch 272a, and the second extended branch 672d partially overlaps with the second branch 272c. That is, the portion where the first extended branch 672c overlaps with the first branch 262a is located at the gate 230 In the range of the configuration, the portion where the second extension branch 672d overlaps with the second branch 262d is located within the range formed by the gate 230. Further, in the present embodiment, the region where the first extension electrode 672c overlaps the first branch 262a The first extension electrode 672c completely covers the first branch 262a, and the second extension electrode 672d completely covers the second branch 262b in a region where the second extension electrode 672d overlaps the second branch 262b.

In this embodiment, by providing the first extension electrode 672c and the second extension electrode 672d, and the first extension electrode 672c and the second extension electrode 672d overlap with the first branch 262a and the second branch 672b, respectively, the same can be improved because of the offset. Causes the difference in gate-drain parasitic capacitance between different pixels.

Please continue to refer to Figure 7, in order to obtain better gate-drain parasitic capacitance Cgd compensation effect, that is, keep the gate-drain parasitic capacitance Cgd equal to our pre-designed value, refer to the design of the second embodiment, the same The embodiment may design that the sum of the width W1 of the first branch 262a and the width W2 of the second branch 262b is substantially equal to 1.4 times the width W3 of the connecting portion 266, that is, W1 + W2 = 1.4 W3. In this embodiment, the width W1 of the first branch 262a may be equal to the width W2 of the second branch 262b, that is, the width W1 of the first branch 262a and the width W2 of the second branch are 0.7 of the width W3 of the connecting portion 266. Times, ie W1=W2=0.7W3. In addition, the present invention is not limited thereto. In other embodiments, the width W1 of the first branch 262a may not be equal to the width W2 of the second branch 262b as long as the width W1 of the first branch 262a and the width W2 of the second branch 262b. Total width And substantially equal to 1.4 times the width W3 of the connecting portion 266.

Sixth embodiment

FIG. 8 is a partial top plan view of a pixel structure according to a sixth embodiment of the present invention. Referring to FIG. 8 , the pixel structure 700 includes a scan line 710 , a data line 720 , a gate 730 , and a semiconductor layer 740 . A source 750, a drain 760, a pixel electrode 770, and a contact electrode 790. Scan line 710 and data line 720 are staggered and electrically insulated from each other. The gate 730 and the scan line 710 are the first metal layer, and the gate 730 is electrically connected to the scan line 710. The semiconductor layer 740 is located above the gate 730. The data line 720, the source 750 and the drain 760 are the second metal layer, and the source 750 is electrically connected to the data line 720, and the source 750 and the drain 760 are at least partially located on the gate 730. In the present embodiment, the gate 730, the semiconductor layer 740, the source 750, and the drain 760 may constitute a thin film transistor (not labeled). The pixel electrode 770 and the contact electrode 790 are electrically connected to the drain 760, respectively.

The drain 760 includes a comb portion 762 surrounding the source 750 and a connecting portion 766. The comb portion 762 is completely disposed within the gate 730, and the comb portion 762 has a first branch 762a, a second branch 762b, and a strip bottom 762c. That is, the comb portion 762 is " The first branch 762a and the second branch 762b extend from both ends of the strip bottom 762c in the direction D to surround the comb portion 762 around the source 750. One end of the connecting portion 766 is connected to the strip bottom 762c, and the other end Then, the deviation direction D extends beyond the gate 730, and therefore, the connection portion 766 partially overlaps the gate 730.

In order to improve the problem of the offset of the alignment step caused by the movement of the machine as described in the previous case, which causes different pixels to have different gate-drain parasitic capacitance Cgd, The problem of uneven brightness is shown. This embodiment proposes a design of a pixel electrode 770 and a contact electrode 790 for improving such defects. The design concept is as follows.

The pixel electrode 770 includes a body portion 771 and an extension portion 772. The body portion 771 is electrically connected to the drain electrode 760 through a first contact hole 781. The extension 772 includes an extension electrode 772a and an extension branch 772c. The extension electrode 772a and the extended branch 772c substantially form an "L" shape, the vertical portion of which is the extension electrode 772a, and the lateral portion is the extension branch 772c. The extension electrode 772a is located between the main body portion 771 and the extended branch 772c and is electrically connected to the two. The extension branch 772c extends from the end of the extension electrode 772a away from the body portion 771 in a direction away from the direction D to partially overlap the first branch 762a of the gate 730 and the drain 760. That is, the extended branch 772a has an overlapping portion and a non-overlapping portion, and the overlapping portion is a region where the extended branch 772c overlaps with the drain 760, and the overlapping portion is located within the range formed by the gate 230; the non-overlapping portion is overlapped An extension branch 272c other than the portion, and a portion of the non-overlapping portion extends from the overlap portion in the D direction beyond the first branch 262a and overlaps with the gate 230. It is understood by those skilled in the art that the width of the portion in the D direction is greater than or equal to The range of machine offset.

The contact electrode 790 and the pixel electrode 790 are made of the same material and are formed by the same mask process. The contact electrode 790 is electrically connected to the second branch 762b of the drain 760 through a second contact hole 784, and the second contact hole 784 is located at one end of the second branch 762b away from the strip bottom 762c. The contact electrode 790 extends from the second contact hole 784 in the direction D to the outside of the second branch 762c and outside the gate 730. Therefore, the contact electrode 790 has a portion overlapping the second branch 762b, and a portion is not overlapped with the second branch 762b but Gate 730 overlaps, and part and gate 730 does not overlap. In addition, the contact electrode 790 is a strip electrode, and the width of the contact electrode 790 is greater than or equal to the width of the second branch in the embodiment, and the contact electrode 790 is completely covered in the region where the contact electrode 790 overlaps with the second branch 762b. The second branch 762c, of course, the conventional memory should understand that the width of the contact electrode 790 is not limited thereto.

As can be seen from the above description, the pixel electrode 770, the contact electrode 790, and the drain 760 overlap with the gate 730, and the pixel electrode 770 and the contact electrode 790 are electrically connected to the drain 760, respectively. The parasitic parasitic capacitance Cgd includes a parasitic capacitance generated by the overlap of the comb portion 762 and the gate 730, a parasitic capacitance generated by the overlap of the connection portion 766 and the gate 730, and a parasitic capacitance generated by the overlap of the extension electrode 772a of the pixel electrode 770 and the gate 730. The parasitic capacitance generated by the overlap of the extension branch 772c and the gate 730 and the parasitic capacitance generated by the overlap of the contact electrode 790 and the gate 730. In addition, since the overlapping portion of the extended branch 772c is in the gate 730, and the first branch 762a of the drain 760 exists between the overlapping portion and the gate 730, there is no extended branch 772c at the overlapping portion of the extended branch 772c. With the parasitic capacitance of the gate 730, only the parasitic capacitance of the first branch 762a and the gate 730 exists. In other words, the parasitic capacitance of the extended branch 772c and the gate 730 has only a parasitic capacitance in which the non-overlapping portion overlaps with the gate 730. Also, since the second branch 762b overlaps the contact electrode 790 within the gate 730, and there is a second branch 762b between the gate 730 and the contact electrode 790 in the overlap region, there is only a second in the overlap region. The parasitic capacitance of the branch 762b and the gate 730 does not exist in the parasitic capacitance of the contact electrode 790 and the gate 730. In other words, the parasitic capacitance of the contact electrode 790 and the gate 730 exists only in addition to the second branch 762b region and the gate. 730 overlapping parasitic capacitance. Therefore, the gate-drain parasitic capacitance includes: the comb portion 762 and the gate 730 The parasitic capacitance, the parasitic capacitance of the connection portion 766 and the gate 730, the parasitic capacitance in which the extension electrode 772a overlaps the gate 230, the parasitic capacitance generated by the overlap of the non-overlapping portion of the extended branch 772c and the gate 730, and the region other than the second branch 762b The parasitic capacitance generated by the contact electrode 790 and the gate 730 overlap.

When the alignment step is shifted due to the movement of the machine to cause the second metal layer to be offset in the direction D, then the positional relationship of the data line 720, the source 750, and the drain 760 with respect to the gate 730 is actually As shown by the dotted line (only the drain 760 is shown as a dotted line). That is, the data line 720, the source 750, and the drain 760 are integrally translated relative to the gate 730 toward the left side of the drawing, that is, toward the direction D. The connection portion 766 of the drain electrode causes an increase in the area overlapping the gate 730 due to the left shift, and therefore the parasitic capacitance of the connection portion 766 and the gate 730 increases. The comb portion 762 is also shifted to the left, but since it is always in the region of the gate 730, the parasitic capacitance of the comb portion 762 and the gate 730 does not change. However, due to the left shift of the comb portion 762, the first branch 762a is caused to move to the left, thereby causing an increase in the overlapping area of the first branch 762a and the extended branch 772c, that is, the overlapping portion is increased, and the non-overlapping portion is decreased, thereby extending The parasitic capacitance of the branch 772c and the gate 730 is reduced; likewise, the second branch 762b is also shifted to the left due to the left shift of the comb portion 762, thereby causing an increase in the overlapping area of the contact electrode 790 and the second branch 762b, that is, The area where the contact electrode 790 overlaps with the gate 730 outside the region of the second branch 762c is reduced, and therefore, the parasitic capacitance of the contact electrode 790 and the gate 730 is reduced. Therefore, the amount of decrease in the parasitic capacitance of the extension branch 772c and the gate 730 and the amount of decrease in the parasitic capacitance of the contact electrode 790 and the gate 730 compensate for the increase in the parasitic capacitance of the connection portion 766 and the gate 730, and thus the gate-drain The parasitic capacitance Cgd is compensated, which improves the offset of the alignment step caused by the movement of the machine. Different pixel gate-bungee parasitic capacitances are different. Vice versa, the uneven brightness of the picture caused by the difference in gate-drain parasitic capacitance of different pixels is also improved.

Also, in order to achieve a better gate-drain parasitic capacitance Cgd compensation effect, in the present embodiment, the sum of the width of the first branch and the width of the second branch is substantially 1.4 times the width of the joint.

Seventh embodiment

Fig. 9 is a partial plan view showing the pixel structure of the seventh embodiment of the present invention, and the pixel structure of Fig. 9 is similar to the pixel structure of Fig. 2, and therefore the same reference numerals denote the same elements. The difference between this embodiment and Embodiment 1 is the design of the drain 860 of the pixel structure 800.

Specifically, in the present embodiment, the drain 860 is a strip electrode and a portion is located inside the gate 230. The drain 860 includes a branch portion 862 and a connecting portion 866. The branch portion 862 is completely disposed within the gate 230. The connecting portion 866 extends from the branch portion 862 in a direction opposite to the direction D to the outside of the gate 230. Therefore, the connecting portion Some of the 866 are located within the gate 230 and some are located outside of the gate 230. The connecting portion 866 is electrically connected to the pixel electrode 270 through a contact hole 281. One end of the branch portion 862 away from the connecting portion 866 overlaps with the extension electrode 272c. Further, in the present embodiment, the width of the branch portion 862 is equal everywhere, the width of the connecting portion 866 is equal everywhere, and the width of the branch portion 862 is substantially 1.4 times the width of the connecting portion 866. Similarly, in the present embodiment, the overlap of the gate-drain parasitic capacitance Cgd can be achieved by the overlap of the drain 860 and the extension electrode 272c.

Eighth embodiment

Figure 10 is a partial top plan view showing the pixel structure of the eighth embodiment of the present invention. The pixel structure of Figure 10 is similar to the pixel structure of Figure 9, so that the same component symbols represent the same function and the same configuration. element. The difference between this embodiment and the seventh embodiment is the design of the pixel electrode 970 of the pixel structure 900.

Specifically, the pixel electrode 970 includes a body portion 971 and an extension portion 972 which is the same material as the extension portion 972 and which is formed by the same mask process. The main body portion 971 is electrically connected to the drain 860 through a contact hole 281. The extension portion 972 includes a first extension electrode 972a, a second extension electrode 972b, and a third extension electrode 972c. The first extension electrode 972a extends from the body portion 971 in the direction D to partially overlap the data line 220. Of course, in other embodiments, the first extension electrode 972a and the data line 220 may not overlap. The second extension electrode 972b is located between the first extension electrode 972b and the extension branch 972c and is electrically connected to the two. The extended branch 972c extends from the second extension electrode 972b in a direction opposite to the direction D to overlap the branch portion 962 and the gate 230. That is, the extended branch 972a has an overlapping portion and a non-overlapping portion, and the overlapping portion is a region where the extended branch 972c overlaps with the branch portion 862, and the overlapping portion is located within the range formed by the gate 230; the non-overlapping portion is overlapped An extension branch 972c other than the portion, and a portion of the non-overlapping portion extends from the overlap portion in the D direction beyond the first branch 862 and overlaps with the gate 230. It is understood by those skilled in the art that the width of the portion in the D direction is greater than or equal to The range of machine offset.

When the alignment step is offset due to the movement of the machine to cause the second metal layer to be offset in the direction D, the data line 220, the source 250, and the drain 860 are opposite to the gate. The positional relationship of the pole 230 is actually as shown by the dashed line (only the bungee 860 is shown). Therefore, the overlapping area of the connection portion 866 and the gate 230 is increased, and the overlapping area of the branch portion 862 and the gate 230 is constant. Since the branch portion 862 is shifted in the direction D, the overlapping area of the branch portion 862 and the extension electrode 972c is increased, and thus the parasitic capacitance of the extension electrode 972c and the gate 230 is reduced. Therefore, the amount of parasitic capacitance reduction of the extension electrode 972c and the gate 230 compensates for the increase in the parasitic capacitance of the branch portion 862 and the gate 230. Therefore, the gate-drain parasitic capacitance Cgd is compensated, and the movement due to the machine is improved. This causes the alignment step to shift to cause different pixel gate-drain parasitic capacitance differences. Vice versa, the uneven brightness of the picture caused by the difference in gate-drain parasitic capacitance of different pixels is also improved.

In summary, the pixel electrode of the present invention has an extension portion, and the extension portion overlaps with the drain portion in the gate, and therefore, when the machine moves to cause an offset of the alignment step, because the extension portion and the defect portion The overlap area of the pole also changes, and the parasitic capacitance of the extension and the gate also changes. Therefore, the gate-drain parasitic capacitance Cgd can be compensated, thus improving the different pixel gate-drain parasitic capacitance. Cgd has different problems, thus improving the brightness of the screen. In addition, since the extension portion and the data line are not in the same layer and are electrically insulated, the problem of short circuit does not occur even if the two are overlapped. Therefore, the present invention does not need to increase the width between the gate and the data line relative to the previous case. Therefore, the aperture ratio of the present invention is not reduced.

It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not limited thereto; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that Modify the technical solutions described in the foregoing embodiments, or replace some of the technical features The modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

200‧‧‧ pixel structure

210‧‧‧ scan line

220‧‧‧data line

230‧‧‧ gate

240‧‧‧Semiconductor layer

250‧‧‧ source

260‧‧‧汲polar

262‧‧‧ combing department

262a‧‧‧ first branch

262b‧‧‧Second branch

262c‧‧‧ bottom

266‧‧‧Connecting Department

270‧‧‧ pixel electrodes

271‧‧‧ Main body

272‧‧‧Extension

272a‧‧‧Extended electrode

272c‧‧‧Extension branch

281‧‧‧Contact hole

261‧‧‧ first end

267‧‧‧ second end

2711‧‧‧Extension

Claims (17)

A pixel structure includes: a scan line and a data line, staggered and electrically insulated from each other; a gate electrically connected to the scan line; a source at least partially located on the gate and connected to the data line; a drain, at least partially located on the gate and disposed opposite the source, wherein the drain includes a first end, a connecting portion and a second end, the connecting portion electrically connecting the first end and the first a second pixel; a pixel electrode, the pixel electrode includes a body portion and an extension portion, the body portion includes an extended end, the extension end and the extension portion extend in opposite directions, the second end and the extension The second end is electrically connected to the extending end and does not protrude from the extending end. The extending portion is electrically connected to the main body portion, the extending portion and the gate and the bungee Partially overlapping, the first end overlaps the extension in a plane and does not protrude from the extension. The pixel structure of claim 1, wherein the extension portion comprises an extension electrode and an extension branch, and the extension electrode is electrically connected to the body portion and the extension branch. The pixel structure of claim 2, wherein the extension electrode and the extension branch substantially form an "L" shape, the vertical portion is the extension electrode, the lateral portion is the extension branch, and the extension The branching system partially overlaps the gate and the drain. The pixel structure of claim 3, wherein the first end is a comb portion, and the comb portion is configured as a "Shape, and it further includes a bottom and two branches, the two branches being connected to the bottom. The pixel structure of claim 4, wherein one of the branches of the comb portion overlaps the extended branch portion and is smaller than a width of the extended branch. The pixel structure of claim 5, wherein the width of the branch of the comb portion is substantially 1.4 times the width of the connecting portion. The pixel structure of claim 4, wherein one of the branches of the comb portion overlaps with the extended branch portion and is greater than or equal to the extended branch. The pixel structure of claim 7, wherein the width of the extended branch is substantially 1.4 times the width of the connecting portion. The pixel structure of claim 2, wherein the extended electrode and the extended branch substantially constitute a " The shape has a vertical portion which is the extended electrode, a lateral portion is the two extended branches, and the two extended branches partially overlap the drain respectively. The pixel structure of claim 9, wherein the first end is a comb portion, and the comb portion is configured as a The shape of the comb portion includes a bottom portion and two branches, the two branches being connected to the bottom portion. The pixel structure of claim 10, wherein the two branches overlap with the two extended branch portions, respectively. The pixel structure of claim 11, wherein the sum of the widths of the two branches is substantially 1.4 times the width of the joint. The pixel structure of claim 12, wherein the extension branch connects the width of one end of the extension electrode to be smaller than an end away from the extension electrode. The pixel structure of claim 1, wherein the extending portion comprises an overlapping portion and a non-overlapping portion, the overlapping portion is overlapped with the gate and the drain, non-overlapping The portion is connected to the main body portion and the overlapping portion. The pixel structure of claim 14, wherein the non-overlapping portion has a portion extending from the overlapping portion to the drain in one direction to improve an error caused by the alignment step. The pixel structure of claim 1, wherein the drain is a strip electrode, one end partially overlaps the extension portion, and the other end is electrically connected to the pixel electrode, and the width of the overlapped end is greater than The width of the other end. The pixel structure of claim 1, wherein the pixel structure further comprises a contact electrode electrically connected to the drain and partially overlapping.