Mini Projector Technical classification:
Handheld projectors can be categorized in two ways:
1. From the perspective of light sources, micro-projections can be divided into LEDs and laser sources.
2. From the perspective of the display chip, it can be divided into LCoS technology and DLP technology. The implementation of color by LCoS is divided into two modes: color sequential and color filtering.
Handheld projectors are classified into two categories according to multimedia video decoding and memory device functions:
Divided into multimedia: multimedia is the machine's own memory storage space can even be extended, and can automatically decode audio and video files.
Non-multimedia: Non-multimedia is similar to a traditional machine, and must be linked to a computer to serve.
Mini Projector Technology Introduction:
a).Mini Projector Size
b). Photoelectric efficiency: luminous flux (lumen) that can be output per unit of power consumption (per watt)
This indicator is an important indicator of micro-projection. As an ordinary projector, due to the power supply, general brightness is a very important indicator, and micro-projection, because of the need to balance the brightness, battery life, heat dissipation and other system problems, therefore, not simple Brightness is used as a key indicator of brightness efficiency.
c). Resolution: The resolution of the chip, such as VGA (640 * 480), QVGA (320 * 240) and so on.
d). Color purity: an indicator of color expression, usually measured internationally by the color gamut of NTSC
e). Contrast: an indicator for measuring the resolution of an image (simplified definition of the brightness state of the dark state)
2. DLP Mini Projector technology
As the main promoter of the mini-projector, TI has also made great efforts in the pico-projector. Since 2008, DLP has also launched its latest generation of DMD chips.
In the world, only Texas Instruments (TI) can provide commercial DMD chip products. The principle is mainly to control the micro-mirrors to switch the light to achieve the color gradation and gray scale. On the small DMD chip, there are nearly a million small mirrors that are smaller than the hair.
3. Mini Projector LCoS technology
Compared with DLP Mini Projector technology monopolized by a TI company, LCoS chip vendors are relatively more, such as Himax, Displaytech (Micron), Syndiant and so on. In addition, the LCoS technology platform is much more open than DLP, and the development potential is relatively large. As the LCoS technology, its main imaging principle is similar to that of a liquid crystal LCD. It also controls the voltage through a microcircuit to make the liquid crystal to be twisted. Through the control of the polarized light by the liquid crystal, the light is switched to achieve the color gradation and the gray scale. LCoS (Liquid Crystal on Silicon) differs from liquid crystal in that it is reflected for light control, and liquid crystal is transmitted light control, so that LCoS itself theoretically has an aperture ratio larger than that of liquid crystal.
4. Comparison of DLP Mini Projector technology and LCoS technology
Speaking of the advantages and disadvantages of DLP technology and LCoS technology, in fact, in the use of conference room (education) commercial projectors, there is a dispute about DLP technology and LCoS technology, of course, as a miniature projection, although the general principle is similar, but due to the realization The method is slightly different, but it is still different. The following will also make a detailed comparison from the above several technical indicators.
a). Mini Projector Size:
In terms of terms, the final dimensions of the two technologies are basically the same, and there is not much difference. From a chip point of view, due to the booming development of the liquid crystal industry, the realization of LCoS is mainly a standard liquid crystal packaging process, which is realized by some ITO glass printing, and the implementation of DLP micro-mirror array is realized by mechanical, each micro-reflection There are very complicated mechanical structures under the mirror pixels, so the reduction in pixel pitch is very demanding for process improvement. The difficulty is relatively much larger than the LCoS implementation.
b). Photoelectric efficiency:
The brightness efficiency achieved by the two technologies is roughly the same, with 7 or 8 lumens per watt of light output. However, from the two technologies themselves, the signal requirements of LCoS can be directly connected by the circuit, and DLP is realized by mechanical means. On the motherboard carrying the DMD chip, there is a corresponding processor and memory. (Memory), this part of the power consumption can never be avoided in the overall light engine, can be considered as a disadvantage of DLP technology efficiency, especially in the handheld projection overall system, if you consider the heat dissipation problem, LCoS chip advantage is more obvious . Relatively speaking, LCoS can achieve less than 0.1W power consumption. In the long run, LCoS will also have certain advantages.
As with the same size, DLP needs to achieve higher resolution on the same size chip. It is also very demanding on the process. From the first generation of DLP light engine, 320×480 resolution has fallen behind with LCoS 640. ×480, although the second generation launched 800 × 480 chips, but still behind the LCoS technology, purely technical, the development prospects LCoS is better than DLP.
d). Color purity:
LCoS has achieved progress through technological advancement through color-sequence type, and the theoretical implementation of the hair-type has been basically the same, so the color purity has been basically the same, and has been higher than the display and television.
DLP is reflected by micro-mirrors, while LCoS realizes optical switch by liquid crystal torsion. In the complete opening of the liquid crystal, there is always a dark state light leakage problem. Similar to the traditional business projector, the advantage of DLP in contrast is on the micro projection. It still exists, but because in the actual use environment, due to the influence of external light on contrast, the micro-projection is larger, so the advantage of DLP in contrast is also weakened compared with its business projector. In addition, the aforementioned 3M company's special PBS material, the contrast can also be achieved 250:1, and DLP technology 500:1 even in the all-black environment, it should be said that the gap is not big.
Because DLP is a unique technology of Ti company, the industry is uncertain. Compared with LCoS, LCoS will have a lot of achievements in the future due to its unique semiconductor industry foundation.
5.LED light source and laser light source
LED light source technology has developed rapidly and is used more and more in lighting, home appliances, IT products, and industrial equipment. It not only improves the performance of products, but also contributes to energy saving and environmental protection. For the projector, with the improvement of LED light source technology, it will usher in a new industrial application.
a).LED light source
LED (Light Emitting Diode), a light-emitting diode (LED), is a solid-state semiconductor device that can directly convert electrical energy into visible light. It has the advantages of easy control, low-voltage DC drive, rich color performance after combination, long service life, etc. It has been widely used in urban engineering and large-screen display systems in the past, and has been widely used in liquid crystal displays and LCD TVs. Especially after the LED enters the LCD TV application, as the LED industry grows in the display field, the development of LED also follows the well-known Moore's Law, into geometric development, cost, efficiency, industrial chain, and so on. , already very mature, I believe that in the micro-projection industry, it will also shine!
b). Laser source
From the perspective of the laser source, the overall imaging feel is better than most projectors realized by the LED light source method, but it also has the problem of imaging speckle. In addition, high costs have become a major bottleneck restricting its commercialization. Furthermore, due to the safety of the laser itself to the human eye, the difficulty of promotion in the main consumer electronics market of micro-projection can be imagined. On the whole, the short-term prospects of the laser source cannot be significantly reduced compared to the LED source without a significant drop in cost.