Overview of HTPS LCD Panel Technology

Overview of HTPS LCD Panel Technology

With the popularity of DVD laser video disc players and digital broadcasting systems, the number of high-resolution image sources is gradually increasing. The market for front projectors, large-screen HDTV LCD projection televisions, and other home projector markets has driven the continued expansion of the digital projector market. This growth has also stimulated the consumer demand for three-chip LCD projectors. This article will analyze the HTPS LCD panel in the three-chip LCD projector for readers and introduce its features.

With the increasing demand for business presentations and the recent increase in projector applications in the education market, the demand for HTPS panels for commercial projectors has continued to rise. At the same time, the popularity of DVD players and digital broadcasting has also stimulated the rapid growth of customer demand for home front projectors and large-screen LCD projection TVs.

HTPS LCD technology has long been leading the three-chip LCD projection system into the projector market, and among manufacturers of liquid-crystal light valves, three-chip LCD projection systems based on HTPS LCD technology also have a global market share of nearly 55%. This is because more advanced liquid crystal and high aperture ratio technology can provide low-power HTPS products with good light efficiency, high brightness performance, rich color reproduction, and no harm to the eyes or the environment.

What is HTPS?
HTPS is the abbreviation of High Temperature Poly-Silicon, which means "high temperature polycrystalline silicon" in Chinese. It is commonly known as high temperature glass. It is a branch of the LCD display family and belongs to the active matrix LCD (Active Matrix LCD). Therefore, HTPS is also a type of TFT (Thin Film Transistor).

HTPS LCD is one of the process technologies for polysilicon TFT LCD. It is called high temperature glass because there is a Laser Anneal process in the manufacturing process of the panel, and its temperature exceeds 1000 degrees Celsius. In the early stage of the development of the polysilicon process, in order to transform the amorphous silicon structure of the glass substrate into a polycrystalline silicon structure, a high temperature oxidation technology of more than 1000 degrees Celsius must be used to transform the amorphous silicon structure characteristics into a polycrystalline silicon structure. Since ordinary glass cannot be processed at such a high temperature, only quartz glass can be processed in this way. Its price is more expensive and its size is smaller. Therefore, in the early stage of the development of the polysilicon process, manufacturers took the amorphous silicon route based on cost considerations.

In addition, there is another type of LTPS LCD (Low Temperature Poly-Silicon) that also belongs to TFT LCD. The reason why LTPS LCD is called low temperature is that its process temperature is not that high, only about 500 to 600 degrees Celsius, and it varies slightly depending on the process of each manufacturer. The low-temperature polysilicon process uses excimer laser as a heat source. After the laser light passes through the projection system, it will produce a laser beam with uniform energy distribution, which is projected on the glass substrate of amorphous silicon structure. When the amorphous silicon structure glass substrate absorbs the energy of the excimer laser, it will be transformed into a polysilicon structure. Because the entire processing process is completed below 600 degrees Celsius, general glass substrates can be applied. The main feature of low-temperature polysilicon technology is to change the liquid crystal structure to improve the performance of traditional amorphous silicon liquid crystal technology and reduce manufacturing costs. Since LTPS technology can increase the electron mobility by 200 (cm2/V-sec), it is conducive to the miniaturization of TFT components and increase the panel opening rate, so that the display brightness increases and the power consumption rate is reduced. In addition, the low-temperature process is conducive to the use of glass substrates, which can greatly reduce production costs. The main uses of HTPS and LTPS are different.

HTPS LCD application areas
HTPS is usually used as a magnified display product. For example, LCD projectors, rear projection TVs, etc. Generally speaking, the LCD screens of mobile phones or computers are direct-view types, which means that users can directly view the screen and read information. Although HTPS is also a type of TFT, it cannot be directly used for mobile phones or computer screens.

The applications of HTPS LCD can be roughly divided into the following three types: OHD (Over Head Display), Helmet and LV (Light Valve).

Its main uses are introduced as follows:

OHD: Head-up display, which projects images onto the windshield (or transparent glass), is used in cars or airplanes and can be seen in many air combat movies;

Helmet: Here refers to the display used in the virtual reality helmet;
LV: can be translated as light valve. When HTPS is working in the LCD projector, since all light will pass through HTPS and the degree of light penetration is determined by HTPS, it is called the "light valve".

HTPS LCD panel features
HTPS LCD has the advantages of small size, high resolution, high penetration, etc., so it is particularly suitable for use as a three-chip transmissive LCD projector. The three-chip transmissive LCD projector using HTPS LCD has three features that can provide viewers with a bright, soft and color-correct and natural visual experience.

Natural Images
The three-chip LCD projection system can accurately control the three colors of R, G, and B and the pixels that make up the image, making the picture more natural and vivid.

Comfortable vision (Gentle on the Eyes)
Fast moving pictures and images will not show color separation phenomena, such as rainbow effect.

Bright Images

Since HTPS LCD uses three-color light for full-time projection, its light efficiency is very high, and users can enjoy bright and clear images.
Currently, there are two manufacturers producing HTPS LCD, Epson and Sony. Among them, Epson has the largest production capacity. Since it started production in 1987, it has produced a total of 20 million units by July 2004. Currently, Epson has three HTPS factories and is the world's largest HTPS LCD manufacturer.

Conclusion
With the popularity of DVD laser video disc players and digital broadcasting systems, the number of high-resolution image sources is gradually increasing, and the market for front projectors, large-screen HDTV LCD projection televisions, and other home projectors is also expanding rapidly. The market for digital projectors continues to expand, and the increase in demand for business presentations and the demand for classroom computerization are stimulating market growth. This growth also stimulates consumer demand for home front projectors and large-screen HDTV LCD projection televisions featuring three-chip LCD design technology, which allow users to enjoy digital information content with large-screen picture quality.

Manufacturers developing HTPS LCD will also be committed to producing panel products with higher aperture ratio, higher contrast ratio, brighter and smaller size, so as to design brighter, smaller and more space-saving front projectors and large-screen HDTV LCD projection TVs, while being price competitive. Now there are HTPS TFT LCD panels developed for home theater projectors, such as 1.8cm 720p wide screen format products and 1.4cm 480p wide screen products. Judging from the fact that manufacturers are putting all their efforts into the research and development of new panel products, the competition in the projection market will be more intense in the future, and the more beautiful visual feast will make the picky consumers the biggest winners.