a)。 size
B) photoelectric efficiency: luminous flux (lumen) that can be output per unit power consumption (watt)
This index is a very important index of microscopic projection. As an ordinary projector, the general brightness is a very important indicator because of the power supply. However, micro-projection takes brightness efficiency as a key index rather than pure brightness because it has to consider the system problems such as brightness, battery life and heat dissipation.
C) Resolution: the resolution of the chip, such as VGA(640*480), QVGA(320*240), etc.
D) Color purity: an indicator of color expression, which is usually measured by the color gamut range of NTSC internationally.
e)。 Contrast: an index to measure the clarity of an image (simply define the ratio of bright state to dark state displayed).
2.DLP technology
As the main promoter of mini-projector, TI has also made great efforts in mini-projector. Since 2008, DLP has also introduced its latest generation of DMD chips.
Worldwide, only Texas Instruments (TI) in the United States can provide commercial DMD chip products. Its principle is to switch the light by controlling the micromirror, so as to realize color gradient and gray scale. On a small DMD chip, there are nearly a million small mirrors thinner than hair.
3.LCoS technology
Compared with the DLP technology monopolized by TI, LCoS has more chip manufacturers, such as Himax, Displaytech(Micron) and Syndiant. In addition, LCoS technology platform is much more open than DLP and has greater development potential. As LCoS technology, its main imaging principle is similar to that of LCD. It also distorts the liquid crystal by controlling the voltage through the microcircuit, and controls the polarized light to switch the light through the liquid crystal, thus realizing the color scale and gray scale. LCoS(Liquid Crystal on Silicon) is different from liquid crystal in that it controls light through reflection, while liquid crystal controls light through transmission, so that the aperture ratio of LCoS itself is technically higher than that of liquid crystal.
Comparison between 4.4. DLP technology and LCoS technology
Speaking of the advantages and disadvantages of DLP technology and LCoS technology, in fact, DLP technology and LCoS technology are controversial in the conference room (educational) commercial projector used. Of course, as a micro-projection, although the general principle is similar, it is still somewhat different because of the slightly different implementation methods. The following will also be compared in detail from the above technical indicators.
a)。 Size:
As far as the two technologies are concerned, the final product size is basically the same, and there is not much difference. From the chip point of view, due to the vigorous development of liquid crystal industry, LCoS is mainly realized by standard liquid crystal packaging technology, and the circuit is realized by some ITO glass printing, while DLP micromirror array is realized mechanically, and each micromirror has a very complicated mechanical structure. Therefore, the reduction of pixel pitch requires very high technical improvement. This is much more difficult to implement than LCoS.
b)。 Photoelectric efficiency:
The brightness efficiency of the two technologies is almost the same, and the light output per watt is 7,8 lumens. However, from the perspective of two technologies, the signal requirements of LCoS can be directly connected through circuits, while DLP is realized by mechanical means. On the motherboard loaded with DMD chips, there are corresponding processors and memories, which are always unavoidable in the whole optical engine, and can be considered as the shortcomings of DLP technology in efficiency, especially in the whole handheld projection system. If the heat dissipation problem is considered again, the advantages of LCoS chip are more obvious. Relatively speaking, the power consumption of LCoS can be less than 0. 1W, and LCoS will have certain advantages in the long run.
c)。 Resolution:
With the same size, it is also very demanding for DLP to improve the resolution on the same size chip. It can be seen from the first generation DLP optical engine that the resolution of 320×480 has fallen behind that of 640×480 of LCoS. Although the second generation introduced 800×480 chips, it still lags behind LCoS technology. From a purely technical point of view, LCoS has a better development prospect than DLP.
D) color purity:
LCoS is realized through technical progress and color sequence types. Theoretically, the hairstyle is basically the same, so the color purity is basically the same, which is higher than that of monitors and televisions.
e)。 Contrast:
DLP is reflected by micromirrors, while LCoS is turned on and off by liquid crystal distortion. When the light is turned on completely, the liquid crystal always has the problem of dark light leakage. Similar to the traditional business projector, the advantage of DLP in contrast still exists in micro-projection. However, due to the greater influence of external light on contrast in the actual use environment, the advantages of DLP in contrast are correspondingly weakened compared with other commercial projectors. In addition, the contrast of the above-mentioned special PBS material of 3M Company can reach 250: 1, which is not much different from the 500: 1 of DLP technology even in a completely black external environment.
f)。 Industry:
DLP is a unique technology of Ti, so the industry is uncertain. Compared with LCoS, LCoS should make great achievements in the future because of its unique semiconductor industry foundation.
5.LED light source and laser light source
With the rapid development of LED light source technology, it is widely used in lighting, household appliances, IT products and industrial equipment, which not only improves the performance of products, but also contributes to energy conservation and environmental protection. For projectors, with the improvement of LED light source technology, new industrial applications will also be ushered in.
a)。 light emitting diode
LED (Light Emitting Diode) is a solid-state semiconductor device, which can directly convert electric energy into visible light. It has the advantages of easy control, low voltage DC drive, rich color performance after combination and long service life. It has been widely used in urban engineering and large-screen display systems, and has been widely used in LCD monitors and LCD TVs. Especially after LED is applied to LCD TV, with the development of LED industry in the display field, the development of LED also follows the well-known Moore's Law, geometric development, cost, efficiency, industrial chain, and so on. It is very mature, and I believe it will shine in the micro-investment field!
b)。 Laser light source
From the point of view of laser light source, its imaging effect is better than that of most projectors realized by LED light source, but there is also the problem of imaging speckle. In addition, the high cost has become the main bottleneck restricting its commercialization. Moreover, due to the safety of laser itself to human eyes, it is difficult to popularize it in the main consumer electronics market of micro-projection. On the whole, the short-term prospect of laser light source can't be compared with LED light source without a sharp drop in cost.