KR20100052594A - An optical filter and a displaying device including the optical filter - Google Patents

Abstract

PURPOSE: An optical filter and a display device including the same are provided to change beam transmittance of a filter according to brightness and to increase the contrast ratio using an optical filter which employs photoelectric effect. CONSTITUTION: A front substrate(150) comprises a transparent base. A rear substrate(110) is arranged facing the front substrate, and made of transparent material. A liquid crystal layer(130) is arranged between the front substrate and the rear substrate. The liquid crystal layer is rearranged according to voltage difference. A lower electrode(120) is interposed between the liquid crystal layer and the rear substrate. An upper electrode(140) is interposed between the liquid crystal layer and a front substrate.

Description

An optical filter and a display device including the optical filter

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical filter, and more particularly, to an optical filter capable of improving the turn function and contrast ratio of electromagnetic waves, and a display device having the optical filter.

Plasma display panels are thin, light-emitting displays that are easy to enlarge in size compared to other image displays, and are considered to have the most suitable characteristics for high-quality digital television. However, the plasma display panel has a problem in that color purity characteristics are deteriorated due to unnecessary light emission of electromagnetic waves generated by plasma light emission and circuitry and near infrared rays caused by plasma of an inert gas used for screen emission.

Therefore, a method of mounting a filter at a predetermined distance from the surface of the display panel has been used for the purpose of improving the contrast ratio and the image quality and shielding the electromagnetic waves generated in the display.

1 and 2 show perspective and stage views of optical filters generally used in PDPs.

1 and 2, the filter 100 and the PDP 110 are arranged at intervals of several mm, and the filter 100 is a glass or transparent plastic substrate 103 as a transparent substrate for attaching each film. And a structure in which an electromagnetic wave shielding layer 104, a selective absorption layer 102 for improving color, an anti-reflection layer (AR layer) 101, and the like are laminated thereon, The charge is grounded through the chassis 120 inside the PDP.

In the prior art, such an optical filter has been used a film coated with multiple layers as a method for preventing external light reflection and reducing diffuse reflection affecting the contrast ratio ratio. There was an effect to get a burn.

In the optical filter according to the prior art as described above, a method of lowering the transmittance of the optical filter by adding a specific dye to the optical filter used for the display surface as a method for improving the contrast ratio and color of the PDP.

However, in the case where the dye is added to the optical filter to lower the transmittance of the optical filter, when the dye is added in excess, the color to be expressed of the PDP causes strong absorption of the specific wavelength of the filter.

This results in breaking the optical balance of the PDP, leading to a decrease in the PDP image quality, and conversely, when the pigment is added in a small amount, the contrast ratio and the color enhancement effect are deteriorated.

In addition to the above-described prior art, various optical filters have been proposed for the purpose of turning electromagnetic waves and for improving the contrast ratio. However, it is difficult to develop an optical filter that can achieve both purposes.

The present invention proposes an optical filter that can improve not only shielding of electromagnetic waves but also an improvement in contrast ratio, thereby providing an optical filter that can be beneficial to a user and exhibit a high contrast ratio, and a display device including the optical filter. For the purpose of

Optical filter according to an embodiment of the present invention comprises a front substrate made of a transparent substrate; A rear substrate disposed to face the front substrate and formed of a transparent substrate; A liquid crystal layer disposed between the front substrate and the rear substrate and rearranged according to a voltage difference; A lower electrode disposed between the liquid crystal layer and the rear substrate; And an upper electrode disposed between the liquid crystal layer and the front substrate, wherein the lower electrode is formed with a photoelectric device for generating an amount of charge corresponding to the amount of incident light.

In addition, the display device according to the embodiment includes a front panel including a front electrode, a sustain electrode pair having a Y electrode and an X electrode formed on a rear surface of the front substrate, and a front dielectric layer covering the sustain electrode pairs; A rear substrate, an address electrode formed on the front surface of the rear substrate to cross the sustain electrode pair, a rear dielectric layer covering the address electrodes, a partition wall formed on the rear dielectric layer and partitioning the light emitting cells, and disposed in the light emitting cell A rear panel comprising phosphors; And an optical filter having a predetermined distance from the front panel, wherein the optical filter includes a front substrate made of a transparent substrate, a rear substrate disposed to face the front substrate, and a transparent substrate; And a liquid crystal layer disposed between the front substrate and the rear substrate, rearranged according to a voltage difference, a lower electrode disposed between the liquid crystal layer and the rear substrate, and an upper electrode disposed between the liquid crystal layer and the front substrate. The lower electrode is characterized in that the photoelectric device for generating a charge amount corresponding to the incident light amount is formed.

According to an embodiment of the present invention, by using an optical filter using an optoelectronic effect, the light transmittance of the filter is actively changed for each position according to the luminance high and low, and the dark image can be expressed more darkly, thereby increasing the contrast ratio. There is an advantage.

In addition, since the effect of EMI shielding is exhibited by the optical filter, a thickness of the EMI shielding layer is not provided.

Hereinafter, with reference to the accompanying drawings for the present embodiment will be described in detail. However, the scope of the idea of the present invention may be determined from the matters disclosed by the present embodiment, and the idea of the invention of the present embodiment may be performed by adding, deleting, or modifying components to the proposed embodiment. It will be said to include variations.

And, in the following description, the word 'comprising' does not exclude the presence of other components than those listed.

3 is a view showing a cross-sectional configuration of an optical filter according to an embodiment of the present invention, Figure 4 is an exploded perspective view of an optical filter according to an embodiment of the present invention, Figure 5 is an optical filter according to an embodiment of the present invention FIG. 1 shows an example of a provided display device. FIG.

First, referring to FIGS. 3 and 4, an optical filter 100 according to an exemplary embodiment of the present invention may include a front substrate 150 formed on a front surface when viewed from a user side, and a rear substrate formed of a glass substrate as a transparent substrate. A liquid crystal layer 130 that is twisted according to a voltage difference between the front substrate 150 and the rear substrate 110, and a lower electrode disposed between the liquid crystal layer 130 and the rear substrate 110. And a top electrode 140 as a common electrode disposed between the liquid crystal layer 130 and the front substrate 150.

The rear substrate 110 and the front substrate 150 are made of a substrate of a transparent substrate, and as the transparent substrate, in addition to glass, a polyethylene lephthalate film, a tri-acetyl-cellulose (TAC), and a polyvinyl alcohol (PVA) Transparent substrates such as polyethylene (PE) and the like may be used.

In addition, the lower electrode 120 disposed on the rear substrate 110 includes an optoelectronic device 121 that generates negative charge of incident light, and the optoelectronic device 121 has an amount of light emitted from the panel. As a result, a corresponding amount of charge is generated. This will be discussed in more detail below.

The lower electrode 120 serves as a pixel electrode, and the lower electrode 120 faces the upper electrode 140 with the liquid crystal layer 130 interposed therebetween. As a result, the liquid crystal layer 130 may vary according to a difference between a predetermined voltage maintained by the upper electrode 140 and a voltage resulting from the charge amount generated by the photoelectric device 121 of the lower electrode 120 being charged. Liquid crystals in the rear panel are rearranged.

That is, the optoelectronic device 121 formed in the lower electrode 120 may be formed to correspond to each pixel of the front panel (to be described later), and to the amount of light (or signal leve) emitted from each pixel of the front panel. As a result, a difference occurs in the amount of charges charged, and thus, an upper and lower voltage difference of the corresponding liquid crystal is generated in the liquid crystal layer 130, and the liquid crystal is rearranged.

In particular, the larger the voltage level generated by the lower electrode, the larger the pixel opening due to the twist of the liquid crystal. The larger the luminance signal of the light emitted from the front panel is, the larger the opening of the liquid crystal is. The opening of the liquid crystal is made small for pixels having a small luminance signal, so that the overall contrast ratio of the display device is further improved.

Referring to FIG. 5, an example of a display device including the optical filter 100 is described. The optical filter 100 includes a front panel 200 and a front panel of the plasma display device having a rear panel 300. The panel 200 may be disposed at a predetermined distance in front of the panel 200. Here, although the display device as an example of the present invention is implemented as a plasma display device, it may be applied to other types of flat panel display devices according to variations of the application examples.

The front panel 200 includes a front substrate 211, a sustain electrode pair having a Y electrode and an X electrode formed on the rear surface of the front substrate 211, a front dielectric layer 215a covering the sustain electrode pairs, and the front dielectric layer. The protective film 216 covering 215a is provided. Each of the Y electrode and the X electrode includes transparent electrodes 213a and 213b formed of ITO or the like and a bus electrode 214 made of metal having excellent conductivity.

The rear panel 300 is formed on the rear substrate 312, the address electrodes 313c formed on the front surface of the rear substrate to intersect the pair of sustain electrodes, the rear dielectric layer 316b covering the address electrodes, and the rear dielectric layer. And a partition wall 317 partitioning the light emitting cells and a phosphor 318 disposed in the light emitting cell.

The optical filter 100 includes a photoelectric element 121 for generating a charge amount according to the light received through the front panel 200, and check the outline of the photoelectric element 121 see.

First, a visible ray generated in the pixel portion of the front panel 200 is incident to the photo detector of the photoelectric device 212. The material of the photo detector may be an n-type semiconductor device.

In addition, (-) charges are generated in the photo detector due to the incident visible ray. For this, reference may be made to the graph shown in FIG. 6, and the amount of charge generated is proportionally increased to Eo, but the charge is higher than Eo. The amount generated is segmented. The generated negative charge moves to the p-tpye semiconductor device that is in contact with the liquid crystal layer.

Thus, the liquid crystal is rearranged as the upper and lower electrodes of the optical filter are charged on the principle of a capacitor. In particular, the arrangement of the liquid crystals is proportional to the amount of charge charged.

7 illustrates a graph comparing light transmittance according to signal levels input to the front panel, and FIG. 7A illustrates light transmittance of an existing filter according to signal levels input to the front panel. It is. 7B shows the light transmittance of the optical filter of this embodiment according to the signal level input to the front panel.

In the case of the optical filter of this embodiment, the light transmittance is similar in the middle and high positions of the signal level input to the front panel, but in the case of the low level, the light transmittance is proportional to the level of the signal input to the front panel. Since the black image is further enhanced, the contrast ratio is excellent.

In addition, since the upper electrode, which is a transparent electrode, is formed on the front portion of the optical filter of the present embodiment, and has an EMI shielding effect, an additional EMI shielding layer is not necessary.

According to the embodiment of the present invention as described above, by using the optical filter using the optoelectronic effect, the light transmittance of the filter is actively changed for each position according to the high and low brightness, and the dark image can be expressed more darkly. There is an advantage to increase.

In addition, since the effect of EMI shielding is exhibited by the optical filter, a thickness of the EMI shielding layer is not provided.

1 and 2 are perspective and cross-sectional views of optical filters generally used in PDPs.

3 is a view showing a cross-sectional configuration of an optical filter according to an embodiment of the present invention.

4 is an exploded perspective view of an optical filter according to an embodiment of the present invention.

5 is a view showing an example of a display device with an optical filter according to an embodiment of the present invention.

6 is a graph showing the generated charge amount according to the light energy and the generated charge amount according to the light intensity.

7 is a graph comparing light transmittance according to a signal level input to a front panel.

Claims (3)

A front substrate made of a transparent substrate; A rear substrate disposed to face the front substrate and formed of a transparent substrate; A liquid crystal layer disposed between the front substrate and the rear substrate and rearranged according to a voltage difference; A lower electrode disposed between the liquid crystal layer and the rear substrate; And An upper electrode disposed between the liquid crystal layer and the front substrate; And an optoelectronic device for generating a charge amount corresponding to the incident light amount on the lower electrode. The method of claim 1, The upper electrode maintains a preset voltage, And the liquid crystal in the liquid crystal layer is rearranged according to a voltage level at which the amount of charge generated by the photoelectric element of the lower electrode is charged. A front panel comprising a front substrate, a sustain electrode pair having a Y electrode and an X electrode formed on a rear surface of the front substrate, and a front dielectric layer covering the sustain electrode pairs; A rear substrate, an address electrode formed on the front surface of the rear substrate to cross the sustain electrode pair, a rear dielectric layer covering the address electrodes, a partition wall formed on the rear dielectric layer and partitioning the light emitting cells, and disposed in the light emitting cell A rear panel comprising phosphors; And And an optical filter having a predetermined distance from the front panel. The optical filter includes a front substrate made of a transparent substrate, a rear substrate made of a transparent substrate, a liquid crystal layer disposed between the front substrate and the rear substrate, and rearranged according to a voltage difference; And a lower electrode disposed between the liquid crystal layer and the rear substrate, and an upper electrode disposed between the liquid crystal layer and the front substrate, wherein the lower electrode is provided with a photoelectric device for generating an amount of charge corresponding to the amount of incident light. Display device, characterized in that.

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