* Projection Currently projector display technology in three principal, namely, CRT projection technology, LCD projection technology, and developed in recent years the DLP projection technology. CRT (Cathode Ray Tube) is the cathode ray tube. That is widely used as a display technology. CRT projector decomposition of the input signal source to the R (red), G (green) B (blue) of three CRT tube screen, in the light signal amplification under high pressure, convergence, on the big screen shows color images. LCD (Liquid Crystal Display) projector into the projector and LCD panel liquid crystal light valve projector types. LCD is the range between liquid and solid substances, in itself does not shine, the nature of much affected by temperature, its operating temperature of-55oC ~ +77 oC. LCD projector using the photoelectric effect, that the arrangement of liquid crystal molecules changes in the electric field, affecting the LCD unit transmittance or reflectance, and thus affect its optical properties, resulting in a different gray level and color images. DLP projector technology is a digital reflection-type projection. The first is characterized by digital edge. Adoption of digital technology to enhance the image gray level, image noise disappears, the picture quality is stable, very precise digital images. Followed by the reflective edge. The application of reflective DMD device, so that the total optical imaging device efficiency is greatly improved, the contrast is very good brightness uniformity. High definition DLP projector, screen uniformity, color sharp, three machines can reach very high brightness, and are free to zoom, very easy to adjust.
* Brightness Projector main performance index, a unit of measurement for the brightness of the U.S. National Bureau of Standards, the number of display devices with standard lumen, thus out of a standard measurement usually ANSI Lumens brightness, said. In general, the larger the number the more light lumens, then the more high-end projector. Projected image on the screen brightness measurement method: the one square meter of the image were divided into nine, measuring the light value of each center, and then calculated the average of nine.
* Standard Resolution Composition of an image pixel (or point) number, the more the number of pixels The higher the resolution, displayed on the delicate smooth. Allow high-resolution display more information. VGA = 640x480, SVGA = 800x600, 1024x768, 1280x1024. Resolution is: Addressable resolution, RGB resolution, video resolution of three. On the CRT projector, the addressable resolution is the highest resolution projection tube and pixels, it is mainly focused performance by the projection tubes are determined quality indicators are CRT is an important parameter. Addressable resolution should be higher than the RGB resolution. RGB resolution is the resolution of the projector receiving the RGB video signal can be had to the maximum pixel, such as a resolution of 1024 × 768, that is 1024 horizontal resolution, vertical resolution 768, RGB and horizontal scanning frequency resolution vertical scanning frequency and video bandwidth are related. video resolution refers to the projector displayed the highest resolution composite video.
* Projection distance Projection screen projector from the effective distance.
* Screen aspect ratio An image or the screen width and height than the general projector aspect ratio of 4:3, the basic model is also compatible with 16:9.
* Color Is the projection screen can reflect the richness of color. The greater value that the projector can provide richer colors, now almost all the number of colors the projector to achieve 16.7 million colors. This figure is coming from a RGB triple color combinations, that is, 256 * 256 * 256 = 16,777,216.
* Projection method There are positive projection, rear projection, hanging cast. Front projection: From the view of the ipsilateral projection to the screen or wall.
* Adjust function Often the screen image because of the location and projector screen is not correct perspective distortion, refers to a certain extent in this way distortion compensation were adjusted to achieve the most harmonious of the projection screen. There are digital keystone correction and two types of optical keystone correction, projector range can provide greater correction is the better the performance.
* Effective scanning frequency Divided into horizontal scanning frequency (line frequency) and vertical scanning frequency (field frequency). Horizontal scanning frequency: E on the screen from left to right movement called the horizontal scan, also known as line scanning. Scan times per second is called the horizontal scan frequency, the level of the video projector scan frequency is fixed for 15.625KHz (PAL system) or 15.725KHz (NTSC system) data and graphics projectors, scanning frequency is not without a frequency band; in The band, the projector can automatically track the input signal line frequency, the PLL circuit with the input signal line frequency of complete synchronization. Distinguish between horizontal scan frequency is an important indicator of grade projector. 15kHz-60kHz frequency range is usually called a data projector projector. Maximum frequency over 60kHz is usually called a graphics projector. Vertical Scanning Frequency: horizontal scanning electron beam in the same time, and from top-down movement, a process called vertical scan. The formation of an image for each scan time, the number of scans per second is called the vertical scanning frequency, vertical scan frequency is also called refresh rate, it said the number of times this image refreshes per second. Vertical scanning frequency is not lower than 50Hz, otherwise the image will be of light flashes.
* Input Terminal Projector to the input signal interface. RCA Connector: RCA connectors: for the majority of stereo equipment and video recorders, audio and video input jack. BNC connector: coaxial cable typically used to connect workstations and connectors. BNC cable with five connectors for receiving red, green, blue, horizontal sync and vertical sync signals.
* Nominal value of brightness uniformity Namely: Uniformity. Refers to the brightest projector image and the darkest part of the difference in value, generally speaking, where the projector is the brightest part of the picture, where the most dark edge of the screen; so when the higher uniformity of the screen Central to the edge the higher the consistency, uniformity when the lower screen brightness varies in range and more severe.
* Video signal method The world's leading standard for the PAL and NTSC. NTSC: National Television Systems Committee (National Television Systems Committee). North America, Japan, South America TV standards in some countries. NTSC has 525 lines of resolution and 60Hz refresh rate. NTSC refers to a video or television signals. PAL: Phase Alternate Line (phase alternating line). Western Europe, Asia, Australia, Africa and South America TV standards in some countries. PAL has 625 lines of resolution and 50Hz refresh rate. PAL refers to a video or television signals.