LCD classification: According to the difference of British display technology, it can be divided into five main types: O0LED, TFT-LD, TFD-LCD, SIN-LCD, GF-LCD, etc. According to the technical characteristics of the backlight, LCD can also be divided into reflective LCD and transmissive LCD.
The transmissive LCD display is more dependent on the backlight source, and its power consumption is relatively large, but the reflective LCD does not need the backlight source, it relies on the sub-ambient light to display, and the power consumption is also low, suitable for mobile phones , IPDA and other portable electronic products, so people have been researching reflective LCDs for a long time. Early reflective LCDs adopted the QO'TN mode and used two German newspapers. Later, a reflective hybrid chess TN, reflective VA and other chess patterns using one German insert were proposed. The disadvantage of reflective LCD is that the contrast ratio is only 5:1-30:1 due to the ambient light reflected on the panel. Since reflective LCDs are mainly used in e-books and other products, they must reach the reflectivity of ordinary paper, that is, 70%-90%.
—、Reflected to LCD
1. The relationship between reflection and display performance
If the ambient light is to be reflected on the LCD panel, then a reflective plate needs to be added to the structure of the LCD. The simplest structure is that the reflector is attached to the outside of the LCD liquid crystal cell, but when the distance between the images is small, the emitted light will interfere with the adjacent pixels, so that a double image will be observed. Insert the fuselage in the liquid crystal cell. The surface reflector can completely solve the problem of the double image, but the image of the light source or the reflected image of the double observer can be observed from the displayed screen. The regular uneven surface makes the incident light become diffused light. structure. In this—of the structure
Among them, the irregularities on the surface cause the incident white light to produce a dispersion effect. When the reflector is formed with an irregular irregular surface structure, the wavelength dependence of the reflected light disappears. When incident light hits the irregular reflector, the reflected light includes normal reflected light and diffused light. The ratio of the diffused light of the normal reflected light has a greater impact on the reflected display characteristics of the product. The above is for the case where the incident light is parallel light. For example, when the incident light is non-parallel light, in order to make the reflective LCD display a good image, it is necessary to design and control the surface of the reflector according to the use purpose and the size of the screen. For example, the incident light in the air is composed of the parallel light irradiated by the fluorescent lamp and the diffused light formed after being reflected on the wall, and the ratio of the parallel light and the diffused light is 1:1.
2 color display
The reflective LCD in color mode has the following two structures, the color film structure and the Dengyun structure. The structure of the color film is the same as the color film structure of Transbo LCD, but it is different in color purity and brightness control. The color purity of the transmissive LCD is determined by the color film and the backlight. The brightness can be changed by increasing the intensity of the backlight. However, in the reflective LCD, the light depends on the ambient light and passes through the color film twice, so it is necessary Design special color film.
2. Semi-reflective and semi-transparent mode
Reflective LCD screens rely on ambient light, so the most deadly weakness is that they cannot be used in dark environments. Semi-inverted LCD is abbreviated as TR-LCD, which is a combination of projection and reflection. In the TR-LCD structure, since the reflected light passes through the liquid crystal cloud twice, the optical path difference between the reflected light and the transmitted light area is twice.
The disadvantage of TR-LCD is that when the ambient light is not too dark and the backlight is turned on, the images in the transmission area and the reflection area will be frosted at the same time, which reduces the sharpness of the picture quality. In addition, in the reflection area, the light passes through the color film cloud twice, and the image in the reflection area and the transmission area has a color difference. Aiming at the problem of color, Canying has developed a TR-LCD structure with the color desert thickness of the reflective area reduced by 1/2. The manufacturing process of the reflective area and the selective area of different thicknesses in the liquid crystal cell is relatively nitrogenous, and the selective area Different from the driving characteristics of the reflective area, it brings many difficulties in actual production and application.
