This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 103126098 filed in Taiwan, Republic of China on Jul. 30, 2014, the entire contents of which are hereby incorporated by reference.
1. Field of Invention
The invention relates to a display panel and a display device and, in particular, to a display panel and display device having higher transmittance.
2. Related Art
With the progress of technologies, flat display devices have been widely applied to various kinds of fields. Especially, liquid crystal display (LCD) devices, having advantages such as compact structure, low power consumption, less weight and less radiation, gradually take the place of cathode ray tube (CRT) display devices, and are widely applied to various electronic products, such as mobile phones, portable multimedia devices, notebooks, LCD TVs and LCD screens.
A conventional LCD apparatus mainly includes an LCD panel and a backlight module disposed opposite to the LCD panel. The LCD panel mainly includes a thin film transistor (TFT) substrate, a color filter (CF) substrate and a liquid crystal layer disposed between the two substrates. The CF substrate, the TFT substrate and the LC layer can form a plurality of pixel units disposed in an array. The backlight module can emit the light passing through the LCD panel, and the pixel units of the LCD panel can display colors forming images accordingly.
For the same luminance, a display panel with a higher transmittance can save more energy for the display device. Therefore, the industry strives to increase the transmittance of the display panel to save more energy and enhance the product competitiveness.
An objective of the invention is to provide a display panel and a display device which can have higher transmittance so as to enhance the product competitiveness.
To achieve the above objective, a display panel according to the invention includes a first substrate, a second substrate and a pixel array. The second substrate is disposed opposite the first substrate. The pixel array is disposed on the first substrate and at least includes a pixel including a first electrode layer. The first electrode layer has an auxiliary electrode portion and a driving electrode portion connecting to the auxiliary electrode portion. The driving electrode portion has a plurality of strip electrodes spaced from each other and arranged along a first direction. The area of the auxiliary electrode portion is denoted by A1, when a light passes through the pixel, the pixel has a light-emitting zone having an area denoted by B. A1 and B satisfy the following equation: 0.11×B≦A1≦0.27×B, and the units of A1 and B are the same.
To achieve the above objective, a display device according to the invention includes a display panel. The display panel includes a first substrate, a second substrate and a pixel array. The second substrate is disposed opposite the first substrate. The pixel array is disposed on the first substrate and at least includes a pixel including a first electrode layer. The first electrode layer has an auxiliary electrode portion and a driving electrode portion connecting to the auxiliary electrode portion. The driving electrode portion has a plurality of strip electrodes spaced from each other and arranged along a first direction. The area of the auxiliary electrode portion is denoted by A1, when a light passes through the pixel, the pixel has a light-emitting zone having an area denoted by B. A1 and B satisfy the following equation: 0.11×B≦A1≦0.27×B, and the units of A1 and B are the same.
In one embodiment, A1 and B further satisfy the following inequality: 0.13×B≦A1≦0.25×B.
In one embodiment, the light-emitting zone has a first brightness curve along the first direction, and has a second brightness curve along the second direction. The area B of the light-emitting zone is the full width at half maximum (FWHM) of the first brightness curve along the first direction multiplied by the FWHM of the second brightness curve along the second direction, and the first direction is perpendicular to the second direction.
In one embodiment, the auxiliary electrode portion has at least a through hole, and the first electrode layer is electrically connected to a thin film transistor by the through hole.
In one embodiment, the driving electrode portion further includes a connecting electrode, which is disposed away from the auxiliary electrode portion and connected to the strip electrodes.
As mentioned above, in the display panel and display device of the invention, the driving electrode portion of the first electrode layer of the pixel has a plurality of strip electrodes spaced from each other along a first direction, and the area of the auxiliary electrode portion is denoted by A1. When a light passes through the pixel, the area of the light-emitting zone of the pixel is denoted by B. A1 and B satisfy the following equation: 0.11×B≦A1≦0.27×B. Thereby, when the area A1 of the auxiliary electrode portion and the area B of the light-emitting zone of the pixel satisfy the above equation, the display panel and device can meet the requirements of both the electric property and the optics, so that the transmittance of the pixel is maximized. Therefore, the display panel and device of the invention can have a higher transmittance and the product competitiveness can be enhanced.
The invention will become more fully understood from the detailed description and accompanying drawings, which are given for illustration only, and thus are not limitative of the present invention, and wherein:
The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements.
The display panel 1 includes a first substrate 11, a second substrate 12 and a liquid crystal layer 13. The first substrate 11 and the second substrate 12 are disposed oppositely and the liquid crystal layer 13 is disposed between the first substrate 11 and the second substrate 12. The first substrate 11 and the second substrate 12 are made by transparent material, for example but not limited to a glass substrate, a quartz substrate or a plastic substrate. The display panel 1 further includes a pixel array disposed on the first substrate 11. The pixel array includes at least a pixel (or called a sub-pixel) P, and there are a plurality of pixels P in the display panel 1 of this embodiment. The pixels P are disposed between the first substrate 11 and the second substrate 12 and arranged in a matrix. Moreover, the display panel 1 of this embodiment can further include a plurality of scan lines (not shown) and a plurality of data lines D. The scan lines and the data lines D cross each other and are perpendicular to each other to form the region of the pixel array.
The pixel P includes a first electrode layer 141, an insulating layer 142 and a second electrode layer 143. In this embodiment, the second electrode layer 143, the insulating layer 142 and the first electrode layer 141 are sequentially disposed on the side of the first substrate 11. The data line D is disposed on the first substrate 11. The pixel P can further include another insulating layer 145 covering the data line D, and the second electrode layer 143 is disposed on the another insulating layer 145. The insulating layer 142 covers the second electrode layer 143 and the first electrode layer 141 is disposed on the insulating layer 142. Therefore, the second electrode layer 143 is disposed between the insulating layer 142 and the another insulating layer 145, and the second electrode layer 143, the data line D and the first electrode layer 141 won't be short-circuited to each other. The material of the insulating layer 142 and another insulating layer 145 can include SiOx, SiNx or other insulating materials for example, but this invention is not limited thereto. Moreover, the first electrode layer 141 and the second electrode layer 143 are a transparent conductive layer, and the material thereof is, for example but not limited to, indium-tin oxide (ITO) or indium-zinc oxide (IZO). In this embodiment, the first electrode layer 141 connects electrically to the data line D for being a pixel electrode, and the second electrode layer 143 is a common electrode. However, in other embodiments, the first electrode layer 141 can be a common electrode while the second electrode layer 143 is a pixel electrode.
The display panel 1 can further include a black matrix BM and a color filter layer (not shown). The black matrix BM is disposed on the first substrate 11 or second substrate 12 and corresponding to the data lines D. The black matrix BM is made by opaque material, such as metal (e.g. Cr, chromium oxide, or Cr—O—N compound) or resin. In this embodiment, the black matrix BM is disposed on the second substrate 12 and faces the first substrate 11 to over the data line D along the third direction Z. Accordingly, the black matrix BM covers the data lines D in a top view of the display panel 1. The color filter layer (not shown) is disposed on the second substrate 12 and black matrix BM, or the color filter layer is disposed on the first substrate 11 in another embodiment. Since the black matrix BM is opaque, a corresponding opaque area can be formed on the second substrate 12 and a transparent area can be thus defined. The black matrix BM includes a plurality of light-blocking segments disposed between two adjacent color filter portions of the color filter layer. In this embodiment, the black matrix BM and the color filter layer are both disposed on the second substrate 12. In other embodiments, however, the black matrix BM or the color filter layer can be disposed on the first substrate 11 for making a BOA (BM on array) substrate or a COA (color filter on array) substrate. To be noted, the above-mentioned structure of the substrate is just for the illustrative purpose but not for limiting the scope of the invention. Moreover, the display panel 1 can further include a protection layer (e.g. an over-coating layer, not shown), which can cover the black matrix BM and the color filter layer. The protection layer can include photoresist material, resin material or inorganic material (e.g. SiOx/SiNx). The protection layer protects the black matrix BM and the color filter layer from being damaged by the subsequent processes, and forms a smooth surface on the second substrate 12.
As shown in
The driving electrode portion 1412 includes a plurality of strip electrodes which are spaced from each other along the first direction X and connect to the auxiliary electrode portion 1411. In this embodiment, as shown in
As shown in
Accordingly, when the scan lines receive the scan signals, the corresponding thin film transistors of the pixels P are turned on and the corresponding data signals can be transmitted to the corresponding pixel electrodes through the data lines D and the display panel 1 can thus display images. In this embodiment, the gray-level voltages can be transmitted to the first electrode layers 141 (pixel electrodes) of the pixels P through the data lines D, so that an electric field is formed between the first electrode layer 141 and the second electrode layer 143 to drive the liquid crystal molecules of the liquid crystal layer 13 to rotate on the plane of the first and second directions X and Y, and therefore the light can be modulated and the display panel 1 can display images accordingly.
As shown in
In general, the actual charging voltage of the pixel is about equal to the gray-level voltage inputting from the data line D minus the charging error Ve and minus the capacitive coupling voltage (can be called the feed through voltage) VFT (i.e. the actual charging voltage=gray-level voltage−Ve−VFT). Accordingly, in order to make the actual charging voltage of the pixel P approach the gray-level voltage to obtain a better display quality, the sum of the charging error Ve and the capacitive coupling voltage VFT will be the smaller the better. The equations of the charging error Ve and capacitive coupling voltage VFT can be as follows:
C denotes the total capacitance of the pixel P (i.e. the sum of the storage capacitance, the parasitic capacitance and the liquid crystal capacitance), Cgd denotes the parasitic capacitance between the gate and drain of the thin film transistor, R denotes the resistance of the thin film transistor, and VgH and VgL denote the control voltage to the thin film transistor.
Then, by using the direct proportion relationship between the capacitance and the electrode area, the charging error Ve and the capacitive coupling voltage VFT can be derived as follows:
Because the area A2 of the driving electrode portion 1412 and the area B of the light-emitting zone will be designed approximately with a direct proportion, A2 is set as (B/a), and “a” is about 0.76 in an embodiment. Therefore, the equation can be obtained as follows:
Besides,
Next, the sum of Ve and VFT can be represented by a function manner as follows:
It is better when the function f has the minimum value, it means the actual charging voltage of the pixel P approaches the gray-level voltage. However the differentiation of the function f is really complicated, it is not directly solved by differentiation in this invention but solved with a numerical solution. In the numerical solution, some data (Cgd, R, C, VgH, CgL) of the pixel P are substituted into the equations 1, 2. Accordingly, the data of different pixel embodiment can result in the different values of (Ve+VFT) in
For obtaining the minimum of (Ve+VFT), the above equation is differentiated to derive the extreme value as follows:
According to the results above-mentioned, when the ratio of the area A1 of the auxiliary electrode portion 1411 to the area B of the light-emitting zone is 0.19, the sum of the charging error Ve and the capacitive coupling voltage VFT is the smallest, so that the bias between the actual charging voltage of the pixel electrode and the gray-level voltage is minimized. Besides, the charging efficiency can improve so that the transmittance of the pixel P can be maximized. Therefore, the display panel 1 can be configured with a higher transmittance to enhance the product competitiveness.
However, in consideration of the variation of the process, the display panel 1 can have a better transmittance in this embodiment when A1 and B satisfy the following inequality: 0.11×B≦A1≦0.27×B, wherein A1 and B have the unit of μm2. Favorably, the display panel 1 can have a much better transmittance in this embodiment when A1 and B satisfy the following inequality: 0.13×B≦A1≦0.25×B.
As shown in
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As shown in
Other technical features of the first electrode layers 141a-141d can be comprehended by referring to the same elements of the first electrode layer 141, and therefore their descriptions are omitted here for conciseness.
The display device 2 includes a display panel 3 and a backlight module 4 disposed opposite the display panel 3. The display panel 3 can be the above-mentioned display panel 1, and the first electrode layer of the pixel of the display panel 1 can be the above-mentioned first electrode layer 141, 141a, 141b, 141c or 141d or their variations. The related structure and details can be comprehended by referring to the above embodiments and therefore are omitted here for conciseness. When the backlight module 4 emits the light passing through the display panel 3, the pixels of the display panel 3 can display colors forming images.
Summarily, in the display panel and display device of the invention, the driving electrode portion of the first electrode layer of the pixel has a plurality of strip electrodes spaced from each other along a first direction, and the area of the auxiliary electrode portion is denoted by A1. When a light passes through the pixel, the area of the light-emitting zone of the pixel is denoted by B. A1 and B satisfy the following equation: 0.11×B≦A1≦0.27×B. Thereby, when the area A1 of the auxiliary electrode portion and the area B of the light-emitting zone of the pixel satisfy the above equation, the display panel and device can meet the requirements of both the electric property and the optics, so that the transmittance of the pixel is maximized. Therefore, the display panel and device of the invention can have a higher transmittance and the product competitiveness can be enhanced.
Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the invention.
Number | Date | Country | Kind |
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103126098 | Jul 2014 | TW | national |