With the continuous maturity of projection technology and falling prices, projectors have begun to appear in major public places, such as computer classrooms, meeting rooms, and other activities, learning, home theaters, and entertainment venues. At the same time, the concept of our users has also undergone great changes. Now more and more users, especially companies, are beginning to realize the importance of multimedia presentations, and abandon the original paper report method, and the projector A strong interest. At present, there are more than dozens of brands and hundreds of models of projectors in the projector market in China. This is dazzling for professionals, not to mention ordinary ordinary users?
1. Clarify the main specifications
Before purchasing a projector, we must first clarify the three most basic technical indicators of the projector:
1) Luminance international standard unit ANSI lumens (America National Standard Institute), the measurement environment is as follows: the distance between the projector and the screen: 2.4 meters; the screen is 60 inches; the pure dark environment uses a light meter to measure the brightness of 9 points of the projection screen; The average of 9 points of brightness is ANSI lumens. At present, the nominal brightness of some domestic manufacturers is the peak lumen, and the actual brightness is not as high as the nominal value, and users need to distinguish it.
2) Weight
If the main application is teaching or business, this should choose a portable model, portable: 2.1 ~ 3kg; ultra-portable: 1 ~ 2.0Kg, if it is used in industrial monitoring, it should choose a model with better heat dissipation or can be turned on for a long time. There is no need to ask for weight. Some professional high-brightness projectors weigh more than 50kg.
3) Resolution
If the displayed software is based on general teaching and word processing, the resolution is 800x600 (SVGA); if it is mainly connected to a laptop or has higher requirements, XGA (1024x768) should be selected; if the geographic display is required For complex graphics such as information or power grid, it is recommended to use SXGA (1280x1024) or UXGA (1600x1200) products. When displaying high-resolution graphics signals, you must select a digital machine with a line frequency above 60KHz
Second, the clear purpose of use
The projector is a relatively high unit price product, so it is clear that the main purpose of use and the targeted purchase of the projector can save your expenses and reduce unnecessary troubles in the future.
If it is mainly used for teaching or training, you should choose a resolution of 1024X768, choose a product with a brightness of 1500-3000 lumens according to the size of the environment and the projection area, or choose a product of about 3kg if it is not a fixed installation.
If it is mainly used in mobile office and business meetings, it should focus on the selection of lightweight products. Single-chip DLP products can be small and compact because of the simple optical path. At present, there are about 1kg of products, the size is equivalent to half a sheet of A4 paper. Because mobile offices often connect to laptops, it is recommended to choose 1024X768 resolution.
If it is mainly used in large conferences or training places, it is generally fixed installation, so there is no need to consider too much about the weight. The resolution should be 1024X768, and the brightness should be based on the projection area. In general, if the projection area is greater than 150 inches (equivalent to 3mX2m), products with more than 3000 lumens should be selected.
If it is mainly used in industrial monitoring and command, select the resolution according to the first item above, select the brightness according to the projection area and front / rear projection, and also pay attention to the selection of three DLP products according to the picture quality requirements, whether it requires a long time to start up and budget Or three LCD products. The three-piece DLP product has many advantages such as long-time booting, high image quality, and long lamp life, but it is expensive.
If it is mainly used in home theater, you can choose home products of major manufacturers. These products have a resolution of 964X544, 854X480 or other 16: 9 resolutions, and have many functions suitable for home use, but these products have low brightness, mostly less than 1000 lumens, and the projection area is not suitable for too large, so you can also choose to use commercial as The main multi-function model, the brightness can be selected from 1000-2000 lumens, and the resolution of 800X600 is enough.
3. Determine the projected area
In general, according to the 2 × 6 principle, that is, the screen height of 2 × is the distance from the first row to the screen, and the screen distance of 6 × is the furthest seat to the screen to select the projection area and the corresponding projection screen, but this Not suitable for all occasions, it should be remembered that because the brightness index of the projector is the total output of light, so the larger the projection area, the lower the brightness per unit area, the higher the corresponding brightness requirements of the projector.
If the room area is small, LCD projector is optional. When the display area is large, there is no sunlight, and the lighting is dim, you can choose a low brightness about 800-1200 ANSI projector. When the requirements for ambient light are not high, the display area is very large, and high-resolution graphic signals are displayed, the LCD projector can be selected.
4. Confirm the usage
Projector installation methods are divided into table-type front projection, table-type rear projection, and ceiling rear projection. The front projection is the projector's audience on one side; the rear projection is the same as the audience at both ends of the screen. If it is used temporarily, you can choose a table-type front projection. This method is greatly affected by ambient light and the layout is messy. For fixed use, you can choose the ceiling mode. If the space is large and there are overall arrangements during civil construction, the overall effect of choosing the rear projection method is the best. If the space is small, the method of rear projection refraction can be selected. In addition to the use of rear projections in industrial environments and high-end conference environments, it is generally sufficient to use positive projections for cost savings.
Five, on-site purchase skills
After confirming the selected model, how to identify the actual index of the projector through the projected picture under the condition of on-site power-on?
Check the horizontal scanning tracking frequency range According to the horizontal scanning frequency range given in the technical indicators, select high, medium and low frequencies from the middle to calculate the image resolution corresponding to the three frequency points. Check whether the projector can display normally under these three resolutions. If the line is out of synchronization, that is, the screen twists or shakes, etc., it means that the horizontal scanning and tracking are poor.
To check the focus performance, use the test squares generated inside the projector, or the test squares generated by the signal generator or computer, adjust the focus to the best position, change the image contrast from low to high, and observe the horizontal and vertical lines of the square Is there any defocusing phenomenon? If there is, it indicates poor focusing performance.
Check the video bandwidth. Video bandwidth directly affects the details of the video. Use a computer or a signal generator to generate the highest resolution white background graphic signal that the projector can reach, and observe whether the smallest character graphic on the screen is clear. For example, when the video bandwidth of the projector is insufficient, the horizontal lines displayed on the screen are solid, while the vertical lines are dull, and the image details are blurred.
The on-site inspection of the LCD projector produces a completely white image and observes the color uniformity. Generally speaking, the color uniformity of LCD speculation is difficult to reach a high standard. But the color uniformity of good quality projectors is relatively better. In addition, the dust-proof of the LCD projector is a problem. A small amount of dust, such as falling on the LCD panel or the lens, may be amplified very clearly. On the all-white image, adjust the optical focus from small to large. Observe that if colored spots appear on the screen, there may be dust on the LCD panel or lens. It is estimated that the machine's dustproof system is defective.
Six, pay attention to service quality
The value of the projector is higher, and the accessories and consumables (bulbs) are also more expensive and mostly special products. Therefore, you must consider certain usage costs before buying, and check the service level of the supplier in advance to understand the service content, such as engineering construction To inspect the qualifications and project experience of suppliers. At present, a large part of domestic projectors are still sold through abnormal channels. For these products, after-sales service is often difficult to ensure. Users should pay attention to whether they have the original warranty certificate when purchasing.
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