Analysis of the relationship between LCD display image quality and power consumption

Central topics:

Characteristics of Illuminance Sensing Element

Function of the illuminance sensor

Development Trends of Illuminance Sensor Components

Solution:

Detects the amount of light in the surrounding environment and automatically adjusts the lighting status of the backlight module

Direct connection with LSI, short start-up time and easy operation

With the rapid increase in the number of mobile phones and LCD TVs, how to reduce the power consumption of LCD displays and improve image quality, especially when the screen is too bright at night, which can easily cause eye fatigue and dark halo phenomenon in dark indoor pictures, has become a problem that relevant companies must overcome. Fortunately, in recent years (Figure 1), the technology of illumination sensor devices has advanced, and the use of illumination sensor devices with spectral characteristics close to the visual sensitivity of the human eye can effectively solve the above problems.

According to statistics from foreign industry insiders, the global potential market for illuminance sensing components exceeds 1 billion, of which mobile phones, with an annual demand of 600 million units, are currently the main market. In addition, LCD TVs, whose shipments are forecast to exceed 30 million units in 2008, as well as automotive instruments, displays, and lighting fixtures are all applicable objects. In view of this, this article will explore in depth the application and development of illuminance sensing components.

Characteristics of Illuminance Sensing Element

As shown in Figure 2, the illuminance sensor has the characteristics of sensing the outdoor brightness at night (Lux; unit of illuminance) or even the outdoor brightness on a sunny day. In other words, if the above characteristics can be fully utilized and precisely controlled, the problem of poor image quality caused by light sources in various electronic devices can be completely solved in theory. For example, the illuminance sensor can detect the amount of light in the surrounding environment at any time, automatically adjust the lighting status of the backlight module, and effectively reduce the battery power consumption (power consumption) of portable electronic products, while extending the call and standby time and battery life (Figure 3 (a)).

Regarding the application of LCD TV, the longer the LCD display is lit, the more power it consumes. The heat dissipation and noise of the cooling fan become very difficult problems. In particular, the brightness of large LCD TVs currently exceeds 400nm. In bright rooms, the picture is very bright, but in dark rooms, there will be ripples. Moreover, the picture is too bright and it is easy to cause eye fatigue. The black floating phenomenon of dark images is very obvious, and the image contrast is greatly reduced. Since ordinary LCD TVs adjust the light of the backlight module according to the liquid crystal transmittance of each pixel to achieve the purpose of grayscale display, however, too much backlight module light may leak light. If the brightness of the LCD TV audio-visual environment is detected by the illumination sensor element, the brightness of the backlight module is adjusted accordingly. In addition to the black floating of the image, the dynamic range of the brightness can be reduced under the same grayscale number, thereby improving the black image performance (Figure 3 (b)), and reducing the maximum brightness can eliminate the problem of too bright images . This means that when watching LCD TVs, consumers will not be affected by the audio-visual environment and can get delicate images at any time.