Seven Criteria for Front Projection Screen Selection
When users are faced with screen selection, they may have a lot of doubts. Da Lite company provides seven screen selection criteria for different application environments.
CRT technology: CRT projector is what we usually call three gun projector, which is composed of three projection tubes. CRT projector decomposes the input signal source onto the fluorescent screen of three CRT tubes R (red), G (green) and B (blue). Under the action of high voltage, the luminous signal is amplified and converged, and the color image is displayed on the large screen. This kind of projector has the characteristics of rich image color and high resolution, But the disadvantage is that the brightness is usually low.
LCD technology: LCD technology uses traditional light sources, usually metal halide lamps. The three primary colors of red, green and blue are completed by three separate liquid crystal panels, and the three primary colors can reach the screen for imaging almost at the same time.
DLP technology: the full English name of DLP is digital light processor, which means "digital optical path processor". This technology is a patented technology developed by Texas Instruments. It is a projection technology using DMD (digital mirror device) digital micro mirror as imaging device. Digital micro reflectors are used as light valve imaging devices. Even a single DMD is composed of many micro mirrors. The physical resolution of DLP projector is determined by the number of micro mirrors. Many small micro mirrors together form a DMD, and each micro mirror reflection picture represents a pixel.
D-ILA Technology: D-ILA is a direct drive image light source amplifier technology. The core component of its technology is reflective active matrix silicon liquid crystal panel, which is commonly known as reflective liquid crystal panel (LCOS), so this technology is called reflective liquid crystal technology in the industry. The advantage of this technology is high brightness and contrast.
LCOS Technology: this projection technology uses CMOS integrated circuit chip coated with liquid crystal silicon as the substrate of reflective LCD, uses advanced technology to grind flat and then plated with aluminum as a mirror to form CMOS substrate, and then fits the CMOS substrate with the glass substrate containing transparent electrode, and then injects it into liquid crystal packaging. LCOS places the control circuit behind the display device, which can improve the light transmittance, so as to achieve greater light output and higher resolution.
35mm slide projector: this technology is one of the most common projection methods for displaying a single image. Like other portable film projection methods, slides can be played continuously, and the output brightness of the projector is also very high (from 1000-6000 lumens), which can project very perfect picture details and rich colors.
Aerial projection
In business and educational applications, overhead projector is also a common projection method. It has the advantages of flexible installation, simple use and brightness output of up to 3000 lumens. Speakers can use it according to their hobbies. 3D projection
Three dimensional projection technology is realized by light polarization. Stereo projection has high requirements for the polarization of the screen and the gain of the screen. Some front projection screens will also affect the polarization effect. In some special video projection application environments, due to the influence of ambient light, relatively high contrast is required. Therefore, it is best to use curved projection screen in such applications.
Ambient light is one of the key links in projection application. After selecting the projector, we should make clear whether the ambient light can be ideally controlled in the projection environment. Only by controlling the light can we ensure that the light in the projection room can be adjusted according to the needs at any time, and increase or reduce the ambient light at an appropriate time, So that the projected image will not be affected by uncontrollable changes in light. Some rooms will have some uncontrollable lights, so we need to determine whether these lights will be directed to the screen and affect the projected image. In short, users should have a clear understanding of all lights in the projection environment in order to ensure that the whole projection effect is under control.
The brightness of the display device is calculated using the following formula
First, determine whether the shape of both sides of the audience's seat and the screen is narrow and long trapezoidal (Fig. 1) or rectangular (Fig. 2, the viewing angle between both sides of the seat and the center of the screen is greater than 30 ). If the shape setting of the room is the type of Fig. 2 and the viewing angle between the audience and the projection screen is greater than 30 , it is necessary to select the screen material with wide viewing angle.
Traditional video images, such images usually do not have strict requirements for details, and the resolution is not the most important factor. Continuous tone image: This is the most common of various slide film projection methods, providing the best image quality in clarity and color reproduction. Digital or pixelated data with fine details (i.e. texture information used in LCD and DLP video projection equipment) requires high resolution in order to project high-definition image characters.
6 The position of the projector and the horizontal line in the center of the screen
When the projector and the audience are on the opposite sides of the horizontal line in the center of the screen, the screen gain is required to be high, and the reflective screen shall be used (as shown in Figure 1). When the projector and the audience are located in the same direction of the horizontal line in the center of the screen (as shown in Figure 2), the gain requirement is high, and the retro reflective screen is recommended.
See if the screen surface may be soiled or damaged due to unintentional or frequent operation. Typical situations are: in places with large traffic, people may accidentally touch the screen surface; In public places or educational environments, users cannot protect the screen carefully at any time; Where there are problems with suspended particles or dust, the screen may be soiled.
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