Display panel and color filter thereof

A display panel including an active device array substrate, a color filter and a display medium layer is provided. The color filter is disposed above the active device array substrate and includes a substrate and a yellowish photoresist. The yellowish photoresist is disposed between the substrate and the active device array substrate. The yellowish photoresist includes a first fluorescent material, and the optical transmittance in the optical transmitted spectrum of the yellowish photoresist corresponding to the wavelength between 600 nm and 800 nm is greater than 1. The display medium layer is disposed between the active device array substrate and the color filter.

TECHNICAL FIELD

The disclosure relates to a display panel, and more particularly to a display panel including a color filter.

BACKGROUND

A liquid crystal display apparatus has advantages including high definition, high contrast ratio, wide viewing angle and high color saturation. It has become a major application of current display technology. A typical color liquid crystal display apparatus includes a color filter, an active device array substrate and a liquid crystal layer disposed therebetween. The color filter splits light passed therethrough into several light components each having different colors. The light components can be mixed to output or directly output for achieving color displaying on the display apparatus. However, the color filter decreases brightness of images displayed on the display apparatus. Therefore, a major subject in the technology field is to improve the color saturation and the light transmittance of the color filter.

SUMMARY

Therefore, the disclosure provides a color filter for improving the color saturation and brightness of the images displayed on a display panel using the color filter.

The disclosure further provides a display panel, capable of displaying images with high color saturation and high brightness.

The disclosure provides a color filter includes a substrate and a yellowish photoresist. The yellowish photoresist is disposed on the substrate and includes a first fluorescent material. The optical transmittance in the optical transmitted spectrum of the yellowish photoresist corresponding to the wavelength between about 600 nm and about 800 nm is substantially greater than 1.

The disclosure provides a display panel including an active device array substrate, the above mentioned color filter and a display medium layer. The color filter is disposed on the active device array substrate. The display medium layer is disposed between the active device array substrate and the color filter.

The color filter adopts yellowish photoresist including fluorescent material for absorbing light of longer wavelength band, so that the optical transmittance in the optical transmitted spectrum of the yellowish photoresist corresponding to the wavelength between about 600 nm and about 800 nm is substantially greater than 1. Consequently, not only the color gamut of the display panel using the color filter is expanded, but the color saturation and the brightness of the images displayed on the display panel are improved as well.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1is a cross sectional view of a display panel according to an embodiment of the disclosure. Referring toFIG. 1, the display panel100includes an active device array substrate130, a color filter140and a display medium layer150. The display medium150is disposed between the active device array substrate130and the color filter140. The active device array substrate130includes a plurality of driving elements131(only four of them are shown inFIG. 1for illustration). The driving elements131includes, for example, thin film transistors (TFTs), pixel electrodes, scan lines and data lines (not shown). Wherein gate electrode of the TFT electrically connected to the corresponding scan line, source electrode of the TFT electrically connected to the corresponding data line, and the drain electrode of the TFT electrically connected to the corresponding pixel electrode. The display medium layer150is, for example, a liquid crystal layer, but not limited thereto. In other embodiments, the display medium layer150may be an electro-phoretic layer, an electro-wetting layer or other medium layer of which the optical transmittance can be controlled by electric field applied thereon.

Following the mentioned above, the color filter140is disposed on the active device array substrate130, and the color filter140includes a substrate141and a yellowish photoresist142disposed between the substrate141and the active device array substrate130, preferred, the yellowish photoresist142disposed on the substrate141, but not limited it. The yellowish photoresist142includes a first fluorescent material142a. More specifically, the color filter140also includes a red photoresist143, a green photoresist144and a blue photoresist145disposed on the substrate141. The photoresist having different colors are separated by black matrix147which has shading effect to light. In other words, in the color filter140of this embodiment, a pixel unit146includes at least four colors, preferred, is composed of a red photoresist143, a green photoresist144, a blue photoresist145, and a yellowish photoresist142. And the color filter140includes a plurality of pixel units146(only one pixel unit146is shown inFIG. 1for illustration).

The display panel100is, but not limited to, a reflective display panel, a transmissive display panel or a transflective display panel. No matter where the light is incident into the display panel100, the light passes through the display medium layer150and the color filter140sequentially and then exits the display panel100eventually.

In this embodiment, the display panel100is, for example, a transmissive display panel. Light needed for displaying images is provided by, for example, a backlight module110. When a light L provided by the backlight module110passes through the yellowish photoresist142, the first fluorescent material142aof the yellowish photoresist142absorbs a part of the light L of wavelength between about 600 nm and about 800 nm. That makes the optical transmittance in the optical transmitted spectrum of the yellowish photoresist142corresponding to the wavelength between about 600 nm and about 800 nm is substantially greater than 1. More specifically, the spectrum of the light L provided by the backlight module110has, for example, one peak corresponding to a wavelength between about 430 nm and about 470 nm and another one peak corresponding to a wavelength between about 530 nm and about 570 nm.

The characteristics of the first fluorescent material are detailed described below.FIG. 2is a spectrum diagram of the first fluorescent material according to an embodiment of the disclosure. Referring toFIG. 1andFIG. 2, the first fluorescent material142ais adapted to absorb light of wavelength between about 400 nm and about 550 nm, and emitting light of wavelength between about 600 nm and about 800 nm through energy transformation. The optical transmittance in the optical transmitted spectrum of the yellowish photoresist142corresponding to the wavelength between about 600 nm and about 800 nm is increased to be substantially greater than 1. In this embodiment, the luminescence spectrum b(λ) of the first fluorescent material142asatisfies a polynomial equation of the form:
b(λ)=Aλ6+Bλ5+Cλ4+Dλ3+Eλ2+Fλ+G,

FIG. 3is a spectrum showing optical transmittances of different photoresists according to an embodiment of the disclosure. The optical transmittance R of the red photoresist, the optical transmittance G of the green photoresist and the optical transmittance B of the blue photoresist are all smaller than 1 within the wavelength range from about 400 nm to about 700 nm. Only the optical transmittance Y of the yellowish photoresist is substantially greater than 1 within the wavelength is substantially greater than 600 nm.

Below, the optical transmittance R of the red photoresist is compared with the optical transmittance Y of the yellowish photoresist.FIG. 4is a spectrum showing the optical transmittance R of red photoresist inFIG. 3. As can be seen, the optical transmittance R of the red photoresist is in the range from about 0.85 to about 0.99 within the wavelength range between about 600 nm to about 650 nm.FIG. 5is a spectrum showing the optical transmittance Y of red photoresist inFIG. 3. As can be seen, the optical transmittance Y of the yellowish photoresist is in the range from about 1 to about 1.5 within the wavelength range from about 600 nm to about 650 nm.FIG. 6is a ratio spectrum showing the ratio of the optical transmittance Y of yellowish photoresist to the optical transmittance R of the red photoresist. As can be seen, the ratio Q of the optical transmittance Y of yellowish photoresist to the optical transmittance R of the red photoresist is in the range from about 1.1 to about 2 within the wavelength range from about 600 nm to about 650 nm.

Numerical data are listed below for further demonstrating the chromaticity of the light passing through the color filter140of the embodiment. It should be noted that the numerical data listed below is not intended to limit the disclosure.

In this embodiment, the color of the light passing through the red photoresist143of the color filter140is represented as an x-coordinate value (Rx) and a y-coordinate value (Ry) in chromaticity diagram published by International Commission on Illumination (CIE) in 1931 satisfying in equations: 0.625<Rx<0.655 and 0.315<Ry<0.335, respectively. The color of the light passing through the green photoresist144is represented as an x-coordinate value (Gx) and a y-coordinate value (Gy) in the mentioned chromaticity diagram satisfying inequations: 0.285<Gx<0.295 and 0.597<Gy<0.599, respectively. The color of the light passing through the blue photoresist145is represented as an x-coordinate value (Bx) and a y-coordinate value (By) in the mentioned chromaticity diagram satisfying inequations: 0.145<Bx<0.155 and 0.055<By<0.065, respectively. The color of the light passing through the yellowish photoresist142is represented as an x-coordinate value (Yx) and a y-coordinate value (Yy) in the mentioned chromaticity diagram satisfying inequations: 0.410<Yx<0.420 and 0.420<Yy<0.430, respectively. And the color of a white light mixed by the lights with different colors passing through the color filter140is represented as an x-coordinate value (Wx) and a y-coordinate value (Wy) in the mentioned chromaticity diagram satisfying inequations: 0.285<Wx<0.295 and 0.290<Wy<0.300, respectively. In comparison to the conventional color filter without using fluorescent material, the optical transmittance of the color filter140in this embodiment is increased by 8 percents.

In other embodiment, the composition of the first fluorescent material142aof the color filter140can be slightly different from that of the above embodiment, and the luminescence spectrum b(λ) of the first fluorescent material142ais slightly different from the polynomial equation of the above embodiment. More specifically, if a photoresist including a second fluorescent material is defined as a reference photoresist, and the luminescence spectrum a(λ) of the second fluorescent material satisfies a polynomial equation of the form:
a(λ)=Aλ6+Bλ5+Cλ4+Dλ3+Eλ2+Fλ+G,

Further, the optical transmittance spectrum A(λ) of the reference photoresist is calculated by: A(λ)=∫0∞a(λ)c(λ)dλ, the optical transmittance spectrum B(λ) of the yellowish photoresist142is calculated by: B(λ)=∫0∞b(λ)c(λ)dλ, and the c(λ) is the luminescence spectrum of the standard illuminant published by International Commission on Illumination (CIE) in 1931, therefore the ratio of the B(λ) to the A(λ) is greater than about 75%. That is, the optical transmittance spectrum B(λ) of the yellowish photoresist142has an upper tolerance limitation of about 25%.

At least one of the red photoresist143, the green photoresist144and the blue photoresist145may include a third fluorescent material having similar capabilities as the first fluorescent material142a. The difference is that the third fluorescent material has a composition different from that of the first fluorescent material142aand thus has different light absorption band and light emission band. In other words, the person having ordinary skill in the art can select the composition of the third fluorescent material according to practical requirements, which makes the third fluorescent material have a proper light absorption band and a light emission band.

In conclusion, the color filter of the disclosure adopts the yellowish photoresist including fluorescent material for absorbing light of longer wavelength band, so that the optical transmittance in the optical transmitted spectrum of the yellowish photoresist corresponding to the wavelength between about 600 nm and about 800 nm is substantially greater than 1. Consequently, not only the color gamut of the display panel using the color filter is expanded, the color saturation and the brightness of the images displayed by the display panel are improved as well.