【 Weak current College 】 projector basics---Power By 【 China power house network 】

1. the projector

(1) peak lumens
Peak lumens is screen maximum brightness point test of brightness. Peak lumens of test method, in a white window test image to scan lines are still visible, the measurement of the maximum white window illuminance (LUX) multiplied by the white window area (m2) to determine the projector light flux, peak lumens and ANSI lumens-no correspondence between the peak lumens is a projector can reach a maximum of brightness, and the international standards organization ANSI lumens brightness projector is a true embodiment of the determination of the environment are as follows: the distance between the projector and screen is 2.4 m; curtain is 60 inches; pure dark environment measurement with measurement stylus screen projection of the nine points of brightness; find the 9-point average of brightness is ANSI lumens. At present, some manufacturers of projectors the nominal peak lumens brightness, the actual brightness and no nominal value, this is when you select the projector to be aware of the problem.

(2) projector type
According to the nature of the show source, projector main can be divided into video type and data type. Video-projector for optimization for video, it features a brightness of 1000 lumens in, high contrast, projection screen aspect ratio is 16: 9, various video port complete, suitable for playing movies and high-definition television; data-projector main display computer output signals for business presentations Office and daily teaching, and low brightness according to ambient has different options, projection screen aspect ratio is 4: 3, full-featured, for images and text, and video can demonstrate that the basic of all models will have video and digital transmission.

(3) contrast ratio
Contrast to the Visual effect of the contrast is critical, as a general rule, the larger the image clearer eye-catching colors and sharper gorgeous; and contrast small, will make the entire screen is gray. High contrast for image sharpness, detail, grayscale levels are of great help. In some black and white contrast large text display, CAD display and black and white photo display, high contrast black and white contrast, product definition, integrity, and so on. In contrast, in the color level, high contrast images and not obvious. Contrast for dynamic effects to the video display larger, because the dynamic image shade into faster, higher contrast, human eyes easier it distinguish this conversion process. Contrast products in some dark scene in detail, sharpness and high speed moving objects performance advantages more obvious.

In contrast adjustment, all products are processed there are great differences, some products of contrast adjustment range is very small and adjustment process more preference to change the image brightness (increase the brightness of the highlighted region). And some products of contrast adjustable range is very large, different adjustment values for the image's contrast effect gap is relatively large, so that the user can display content according to the different adjustment contrast for optimal display performance. There are also some product contrast adjustment and brightness adjustment of differences are not large, the contrast adjustment can be aided to brightness adjustment. The contrast of the same and projector imaging devices and optical path design closely related, LCD projector, the first factor is the pixels of the LCD Panel and drag light transmittance, the greater the difference in the rate, the contrast of the projector. At present most LCD projectors of nominal contrast is 400: 1 (ANSI), and most DLP projector nominal contrast are 1500: 1 (full white/full black) above. Contrast, the higher the price the higher the projector, if only projector shows text and black and white picture is 400: 1 contrast ratio in around the projector can meet your needs, if used to demonstrate the colorful photo and video animation is the best choice for more than 1000: 1 high on degree of projector.


2. the projection lamp

Projector lamp is one of the important parts of projector, no lamp projector is like no cartridge printer as cannot be used. And the projector bulb also the cartridge as belonging to the consumables, capable of working life, in the life of the projector will encounter the purchase and replacement of the lamp, so users are needed for your projector bulb for some understanding. Common projector bulb brand Philips (model: UHP), Epson (model: UHE), OSRAM (OSRAM type: VIP), Matsushita (model: UHM), Japan-Chi Wang (USHIO model: UMPRD/UMVRD/NSH), Japan Phoenix (PHOENIX models: SHP), United States of singular (GE model: SHL), etc. From the projector bulb type generally can be divided into metal halogen bulb and super high pressure mercury lamp bulb, UHP ultra-high pressure mercury lamp bulb included, UMPRD, UHE, SHP, etc.

UHP and UMPRD bulb is an ideal cold light source, UHP lamp produces cold light, under the same power consumption can produce a large amount of light, live longer, work more than 4000 hours, and brightness falloff is small, when failure to immediately turn off. As a result of higher prices, generally being used in the high-end of the projector.

UHE lamp is also a cold light source, is the mid-range projectors that are widely used in the ideal light source. And the price is moderate, brightness and stability, in the use of 2000 hours ago almost no decay.

The advantages of metal halogen bulb is cheap, the disadvantage is that metal halogen lamp produces warm light, more power to obtain the same luminosity UHP lamp, half-life shorter, the general use of 1000 hour brightness decreases to about half of the original, and high calorific value, on projector thermal system requirements are high, it is not advisable to do long projection.

Due to the high pressure mercury lamp bulbs generally have higher brightness, heat, long life and othercharacteristics, as mainstream projection lamps are widely used.We recommend that users choose to use cold light source for projector that will more effectively protect your projector use effect while saving your investment. In addition, different brands of different models of projector lamp models used are also different, generally cannot be used interchangeably, so that users purchase bulbs should be chosen with the brand with the models of projectors bulb, so as to avoid unnecessary trouble.

Finally to introduce a future promising source-Xenon lamp. Xenon lamp is used between two electrodes placed electrical arcing glow a light source, currently applied in high-end projectors. Because of the Xenon lamp spectral closest to natural light, and as such can provide better color. Xenon lamp UHP lamp also compared may at any time switch feature, usually UHP lamp from light to clearly show the need for about two minutes of warm-up time, Xenon light from light to get clear display elapsed time is less than 60 seconds, and Xenon lamp off immediately starts again, UHP lamp is on this point.


3. the term of the projector

(1) lumens:
ANSI lumens is a United States National Institute of measurement of luminous flux size of a special unit. Luminous flux is the unit of time through an area of energy flow.
(2) resolution:
For the resolution of the image signal into digital images, and simulation images.
Digital image resolution refers to reflect the entire image frame vertical and horizontal direction multiplied by the number of pixels.
Analog image resolution is a reflection of the entire screen up to the number of scan lines.
For the resolution of the display device is also divided into digital and analog. Only
Digital image resolution refers to the hardware infrastructure itself can reflect vertical and horizontal pixels and product.
Analog image resolution refers to the hardware itself can achieve the maximum number of scan lines.
(3) gain meaning:
For projection screen, the gain is the reflection of light luminous flux to the incident light flux ratio; for rear projection screen, the gain is the transmission light luminous flux to the incident light flux ratio.
(4) CRT tube focus on performance:
CRT projector to the input source signal decomposition to R (red), G (green), B (blue) three CRT tube screens, at high pressure through emitting, signal amplification and convergence, in large screen displays a color image. CRT tube focus into static focused, magnetic focus and electromagnetic three composite focused, electromagnetic more common composite application focused, it has the advantage of focus focused good performance, high precision, you can partition the focus and corner focus, let the projection screen is clear.


4. the principle of the projector

(1) CRT projector works
CRT projector and three guns projector, it mainly consists of three CRT tube. CRT (Cathode Ray Tube) is a cathode ray tube, mainly by the electron gun, deflection coil and tube Panel. In order to make the CRT tubes in the image information is displayed on the screen, the CRT projector to the input signal source decomposition to R (red), G (green), B (blue) three CRT tube screens, in the high voltage field emission signal amplification, gathered in large screen displays a color image.
CRT projector according to the CRT tube diameter different can also be divided into three grades, namely 7 inch tube projectors, 8-inch tube projectors, projector 9-inch pipe. CRT projector repair displayed image rich colors, restore good, has a wealth of geometric distortion adjustment capacity; the disadvantage is the low brightness, manipulate complex, bulky, environmental requirements for the installation. CRT projector of two specific performance indicators: convergence performance
Convergence is the red-green-blue three colors on the screen.
For a CRT projector, convergence control appearsespecially important, because it has an RGB three CRT tube, the parallel installation in brackets, in order to achieve the image fully convergent, you must have the image of various distortion correction. Machine location changes, convergence has to resize, convergence, one is a full-featured, easy and fast. Convergent converging have static and dynamic convergence, including dynamic convergence with tilt, bow, amplitude, linear, trapezoid, Pincushion, and other functions, each of these features are available in horizontal and vertical two directions. In addition, may also conduct nonlinear balanced Pincushion trapezoidal balance, balance. Focus on performance
We know that the graphics of the smallest unit of pixels. The smaller the pixel, the higher the resolution graphics. In a CRT tube, a minimum pixel is determined by focusing on performance, the so-called addressable resolution, which is the minimum number of pixels.
CRT tube focus mechanism of electrostatic focused, magnetic focus and electromagnetic three composite focused, with more advanced electromagnetic composite focus, its advantages are focused performance (but high-luminance conditions would defocus), and focus on high precision, you can make the regional focus, focus, focus on the four corners on the edge, so you can do every point on the screen is very clear.

(2) LCD projector works
LCD projector is passive glow to Imaging, the core components for the LCD Panel. Right into the LCD Panel of the projector and the liquid crystal light valve projector. LCD-Chang is between liquid and solid substances, between the light of the nature of the work is greatly influenced by temperature, its working temperature is-55 ° c to + 77 ° c. Projector repair using the photoelectric effect, i.e., LCD liquid crystal molecules are arranged in the electric field changes, affecting its LCD unit of transmittance or reflectivity, thus affecting its optical properties, generated with different grayscale and color images. LCD Panel projector
Imaging device for LCD panels, is a passive way of projection. Using external light source metal halide lamps and UHP (cold light). According to the number of LCD panels, LCD projector can also be divided into three processor and microcontroller.
Three LCD panels projector repair principle is the optical system to light the formation by spectroscopic RGB 3 beam of light, transmissionA three-colour LCD Panel RGB; signal source after AD conversion, modulation to the LCD Board, through the control panel unit for opening and closing, and thereby control the on/off light path, RGB light finally brought together in the Prism, the projection lens projection on screen color image formation. Currently, three plate projectors are the main types of LCD projectors.
LCD veneer projector small size, light weight, easy to operate, extremely portable, less expensive. But his short life of light source, color is not uniform, the lower the resolution. At present the projector maintenance models of veneer is very small. Liquid crystal light valve projector
Use CRT tube and liquid crystal light valve as an imaging device, is a CRT projector and flat panel in combination with light valve. In order to address the image resolution and a brightness of contradiction, it uses the external light source, also known as passive projection mode. General light valve mainly consists of three parts: opto-electrical converter, mirrors, optical modulator, it is a controlled switch. By CRT output of optical radiation to the opto-electrical converter, turn signal is converted to electrical signals of the continuous changes; external light source produces a beam of light, projected onto the light valve, the internal mirror reflection, through light modulator, change its optical properties with light valve of polarized filters will filter out other direction of light, but only allows its optical gap direction consistent light through the optical signal with CRTcombined, projected onto the screen. It is by far the highest brightness, resolution of the projector repair, brightness up to a resolution of 6000ANSI lumens 2500 × 2000, applies to ambient light and strong, the audience more occasions, such as VISI's command center, Conference Center and large-scale entertainment, but its price is high, the bulky, light valve is not easy to repair. On the pursuit of high resolution, high brightness, wide screen users, liquid crystal light valve projector is their preferred.

(3) DLP/DMD projectors working principle
DLP (Digital Lighting Processing) is the data-processing.
The core parts of DLP projectors as a DMD (Digital Micromirror Device) that is, data micromirror devices, other parts are: Xenon bulb, optical Prism and projection lens. Its working principle is: when the light through a Prism into R, G, B color DMD chip after the projection. DMD chip has many tiny lenses (if the resolution is 800 x 600, DMD chip 48 000 small lenses), each small lenses available + 10 ° and-10 ° free rotation and positioning by electromagnetic.　　　Signal input, after it is processed in DMD chip to control the opening and deflection of lenses. Incidence of light through the lens of DMD reflection after the projection lens projection image. DLP projector according to the base number of DMD chip is divided into single, double and three-chip DMD projectors.
DLP projector is a secondary LCD projector developed projection display technology, some of its notable features are: as a reflection of the way, the optical imaging of utilization is very high, so you can achieve maximum brightness. Other DLP projector color and brightness uniformity is also good. In the resolution, part of the model reached 1280 × 1024. It can be said DLP projector is in a continuous development and improvement of the process.