Patent Application
20080106677
1. Field of the Invention
The present invention relates to a liquid crystal display technique, and more particularly, to an electrode structure used in a liquid crystal display capable of reflecting light in a specific color range and applying to a reflective liquid crystal on silicon (LCOS) panel and a projection-type displaying apparatus.
2. Description of Related Art
One of the principal characteristics of a reflective liquid crystal on silicon (LCOS) panel is that most of the driving devices are formed on a lower substrate and the liquid crystal layer is formed between the lower substrate and an upper substrate. Light rays from a light source enter from the upper substrate, travel to the lower substrate and are reflected through the reflective layer on the lower substrate. Hence, the driving devices will not block the reflected light rays and the utilization rate of the light rays is increased.
The reflective LCOS panel can be used to form a projective-type displaying apparatus.
According to a similar mechanism, the red beam 112 generates a red image 126 through a polarized beam splitter 122 and a LCOS panel 124. Again, through a similar mechanism, the blue beam 106 generates a blue image 134 through a polarized beam splitter 130 and a LCOS panel 132. Then, through a light integration mirror 136, the green image 120, the red image 126 and the blue image 134 are combined to form a color image 138. Afterward, through a projection unit 140, the color image 138 is magnified into another image 142 and projected on a screen (not shown in the figure).
In the foregoing conventional projection-type displaying apparatus, a number of dichroic mirrors 102, 110 is required to split up the red beam, the green beam and the blue beam. Furthermore, if a common beam splitter instead of a dichroic mirror is used so that three white beams are produced, then an additional filter plate has to be disposed along the optical path to obtain the required red, green and blue color lights, or according to a frequency point of view, the required red, green and blue color ranges.
The conventional projection-type displaying apparatus requires either dichroic mirrors or filter plates so that at least the production cost of the apparatus is higher and the volume of the apparatus is larger. Although most filter plates can be fabricated on the LCOS panel, the filter plates are individually added elements. In other words, the conventional LCOS panel has no provision for distinguishing the difference between color lights unless there is a filter plate.
Accordingly, the present invention provides an electrode structure belonging to a part of a driving circuit and capable of reflecting the required color ranges.
The present invention also provides an electrode structure such that three units constitute a pixel and each unit is capable of independently reflecting a specified color range, for example, directly reflecting red light, green light or blue light from white light.
The present invention also provides an electrode structure such that three units constitute a pixel and the units reflects red light, green light or blue light respectively to achieve an image displaying effect.
The present invention also provides a reflective liquid crystal on silicon (LCOS) panel that utilizes a three-in-one pixel design to achieve a single panel displaying effect.
The present invention also provides a projection-type displaying apparatus that uses single reflective LCOS panels to display image so as to reduce the cost of production, volume and complexity of a displaying apparatus.
As embodied and broadly described herein, the present invention is directed to an electrode structure comprising a substrate, an electrode structure layer and a color reflection layer. The substrate includes a circuit already formed thereon. The electrode structural layer is disposed over the substrate and electrically coupled to the circuit. The color reflection layer is disposed over the electrode structural layer. When light is incident on the color reflection layer and the electrode structural layer, the color reflection layer only reflects light of a specific color range.
The present invention is also directed to an electrode structure comprising a substrate, a plurality of electrode structure layers and a plurality of color reflection layers. The substrate includes a circuit already formed thereon. The electrode structural layers are formed on the substrate and electrically coupled to the circuit. The color reflection layers are respectively formed on the electrode structural layers. When light is incident on the color reflection layers and the electrode structural layers, each color reflection layer only reflects light of a specific color range.
The present invention is further directed to a reflective LCOS panel comprising a first substrate, a plurality of electrode structural layers, a plurality of color reflection layers, an alignment layer, a second substrate and a liquid crystal layer. The first substrate includes a first circuit already formed thereon. The electrode structural layers are formed on the first substrate and electrically coupled to the circuit. The color reflection layers are respectively formed on the electrode structural layers, wherein the foregoing color reflection layers are grouped in threes to form a pixel corresponding to red, green and blue. When light is incident on the color reflection layers and the electrode structural layers, each color reflection layer only reflects one of red light, green light and blue light. The alignment layer covers over the color reflection layers. The second substrate includes a second circuit already formed thereon. The liquid crystal layer is disposed between the first substrate and the second substrate.
The present invention is also directed to a projection-type displaying apparatus including a white light source, a reflective LCOS panel and a polarized beam splitter. The white light source provides a light beam. The reflective LCOS panel includes a plurality of pixels, and each one of the pixels is able to reflect a specific color range after the light beam has been received through a color reflection layer. The polarized beam splitter is disposed to correspond with the reflective LCOS panel. Through the polarized beam splitter, a polarized light beam having a polarizing direction in the light beam is incident on the reflective LCOS panel. The reflective LCOS panel corresponding to the pixels reflects their respective color ranges. Furthermore, through the control of the liquid crystal layer, the polarizing direction of the polarized light beam is changed. Afterwards, the beam enters the polarized beam splitter to project an image.
According to the foregoing electrode structure in another preferred embodiment of the present invention, the color reflection layers are surface layers on the electrode structural layers. Each surface layer includes a photon crystal structure comprising a plurality of recess areas for reflecting the corresponding lighted area.
According to the foregoing electrode structure in another preferred embodiment of the present invention, the color reflection layers are nano-structure layers fabricated from an inorganic material for reflecting the corresponding lighted areas. According to another preferred embodiment, each nano-structure layer includes, for example, a nano-particle layer, or a quantum dot layer, or a photon crystal layer.
According to one embodiment of the present invention, because the color reflection layers are directly formed on the pixel electrodes, the pixel electrodes can directly reflect red light, green light and blue light respectively. Therefore, the present invention is able to reduce the required number of filter plates or dichroic mirrors.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
To provide further improvements to the conventional reflective liquid crystal on silicon (LCOS) panel, the present invention researches on chromatic phenomenon of optics and concludes that optical interference phenomenon is related to color light.
After the observation of the foregoing optical phenomenon, a further investigation has shown that this type of optical phenomenon is also found in the R & D of material physics. Moreover, this optical phenomenon also happens on objects used in our daily life, for example, the coloring of protein rocks. Furthermore, the coloration on the surface of some insects or fish scales can be explained in part by special optical interference.
From the point of view of physics, these interference phenomena happen as a result of photon crystal structure, or the organic material of the nano-particles or quantum dots. According to the size and arrangement of the particles, light corresponding to a specific color range is reflected.
According to the result of research in the present invention, an electrode structure having a color reflection layer formed on the electrode is proposed. In tandem with the electrical operation of the electrode, a specific color is also reflected. The color reflection layer is used for reflecting out a required color range so that any material that meets this demand is suitable. However, inorganic material is preferred because inorganic material is able to withstand a higher temperature and permits the incident of high-intensity light for a longer period. In particular, when the electrode is used as a pixel electrode on a display, it is illuminated by a light source for a long period of time. In order to increase the brightness of the display, a high-intensity light source is often used. Therefore, inorganic material is more appropriate. However, this is not an essential limitation of the present invention. In the following, a few embodiments are used to explain the present invention. However, the present invention is not limited by the embodiments.
The electrode structural layer 302 is used for reflecting red light. A color reflection layer 304, for example, a gold nano-particle layer or a gold quantum dot layer capable of reflecting out light in the red range, is formed on the electrode structural layer 302. The material constituting the gold nano-particle layer includes gold nano-particles, for example. In general, this reflective phenomenon is a quantum effect. When the particle diameters are equal to or greater than the wavelength of the incident light rays, the particles will absorb and reflect the incident light. However, when the particle diameters are much smaller than the wavelength of the incident light, the particles will mainly absorb the incident light.
Gold nano-particles generate a peak resonance with light at a wavelength of about 500 nm. After the light energy has been absorbed, the free electron cloud of the gold nano-particles is polarized and vibrates according to the frequency of the light wave. In the meantime, the green light and the blue light are absorbed by the gold nano-particles. By controlling the size and shape of the gold nano-particles, its reaction to red light can be enhanced to so that the red light is effectively reflected. Hence, the electrode structural layer 302 and the color reflection layer 304 for red light can serve as a red pixel electrode.
A similar physical phenomenon occurs for other types of nano-particles, for example, green light is generated by silver nano-particles and blue light is generated by gallium nano-particles. In other words, the color reflection layer 308 for green light is, for example, a silver nano-particle layer or a silver quantum dot layer formed on the electrode structural layer 306 to constitute a green pixel electrode. Similarly, the color reflection layer 312 for blue light is, for example, a gallium nano-particle layer or a gallium quantum dot layer formed on the electrode structural layer 310 to constitute a blue pixel electrode. The nano-particles may be directly formed on the electrode so that the nano-particles can directly replace a color filter plate. In addition, there is no need to use a dichroic mirror to split the color range. For example, corresponding to the same incident white light 314, the color ranges 316, 318, 320 corresponding to the red, green and blue color ranges are reflected. When the foregoing pixel electrode structures are applied to the liquid crystal image display technique, the optical devices on the optical path are simplified and overall volume of the display is reduced. The applications of the pixel electrode structures are described in the following.
As mentioned before, the formation of nano-particles is not the only method for fabricating the color reflection layer. In the following, the same effect can be achieved through an embodiment involving photon crystals. In general, most observable reactions of the photon crystals with regard to the color ranges include, for example, a multi-layered optical film. Because the cyclically arranged multi-layered dielectric film may lead to a one-dimensional photon gap, photons within a certain waveband can hardly penetrate so as to attain higher reflection efficiency. Those having cyclically arranged two- or three-dimensional structure are the so-called photon crystals, which can have a number of applications. In the present invention, the photon crystals are used together with the electrode structural layer to produce a pixel electrode structure capable of reflecting color in a specified color range and hence find applications in displaying images.
The color reflection layers in the foregoing embodiment are films on the electrode structural layers. However, according to the characteristics of the photon crystals, the color reflection layers may be directly formed on surface layers of the electrode structures.
Next, according to foregoing pixel electrodes with different color ranges, three electrodes including a red, a green and a blue electrode can be grouped together to form a pixel. The pixel can be applied to a reflective LCOS panel.
The lower substrate 600 includes a circuit, for example, a driving circuit, already formed thereon and the circuit is electrically coupled to the electrode structural layers 602r, 602g and 602b. Here, only the three electrode structural layers 602r, 602g, 602b of a pixel corresponding to the red, green and blue sub-pixels are shown. The color reflection layers 604r, 604g, 604b are formed on the electrode structural layers 602r, 602g and 602b respectively. Three of the color reflection layers 604r, 604g, 604b that correspond to red, green and blue constitute a pixel. When white light is incident on these color reflection layers and the electrode structural layers, the color reflection layers 604r, 604g, 604b only reflect one of red light, green light and blue light respectively.
In general, an alignment layer 606 is disposed on the surface in contact with the liquid crystal layer 608 to control the rotation of liquid crystal so that the liquid crystal molecules can have a better initial direction of arrangement. If the planarity of the alignment layer 606 is increased, the result of the alignment will even be better. The alignment layer 606 in the embodiment of the present covers the color reflection layers 604r, 604g and 604b. Since the color reflection layers in the present invention are allowed a certain degree of planarity, the planarity of the alignment layer 606 is ensured.
The upper substrate 614 is disposed above the lower substrate 600 and the liquid crystal layer 608 is disposed between the upper substrate 614 and the lower substrate 600. In general, anyone familiar with the technology should understand that the lower substrate 600 and the upper substrate 614 might further include other structures and circuits. For example, the upper substrate 614 may further comprise a transparent electrode layer 612, for example, an indium-tin-oxide (ITO) layer, serving as another electrode. Furthermore, the interface with the upper substrate 614 and the liquid crystal layer 608 may further include another alignment layer 610, for example.
Inside the reflective LCOS panel according to the embodiment of the present invention, color reflection layers with different color ranges are formed on the electrode structural layers of the pixel electrode structure. Therefore, when white light is incident on the sub-pixels each having a different color range, color lights such as red, green and blue light are reflected out.
The foregoing reflective LCOS panel is designed according to a single panel mechanism. Therefore, each pixel comprises sub-pixels of three colors. If a three-panel mechanism is deployed, three reflective LCOS panels in three color ranges can be relied on to process images belonging to different color ranges before the images are combined to form an actual image.
In the following, a projective-type displaying apparatus having three reflective LCOS panels is used as an example for the description.
On the other hand, if a single reflective LCOS panel design is deployed, the configuration shown in
In other words, the projection-type displaying apparatus in the present invention may include a white light source, a reflective LCOS panel and a polarized beam splitter. The white light source provides a light beam. The reflective LCOS panel includes a plurality of pixels, and each pixel is able to reflect a specific color range after the light beam has been received through a color reflection layer. The polarized beam splitter is disposed to correspond with the reflective LCOS panel. Through the polarized beam splitter, a polarized light beam having a polarizing direction in the light beam is incident on the reflective LCOS panel. The reflective LCOS panel corresponding to the pixels reflects their respective color ranges. Furthermore, through the control of the liquid crystal layer, the polarizing direction of the polarized light beam is changed. Afterwards, the beam enters the polarized beam splitter to project an image.
Because the color reflection layers are directly formed on the pixel electrodes in the present invention, the pixel electrodes can directly reflect red light, green light and blue light respectively. Therefore, the present invention is able to reduce the required number of filter plates or dichroic mirrors. Furthermore, because the color reflection layers are formed from inorganic material, the color reflection layers can withstand a bright light source. Additionally, because the color reflection layers are provided with a high degree of planarity, the planarity of the alignment layer is superior so that a better liquid crystal alignment effect is obtained.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.
