How Do I Choose the Best Portable Digital Projector?
A projector, also known as a projector, is a device that can project images or videos onto a curtain. It can be connected to a computer, VCD, DVD, BD, game console, DV, etc. through different interfaces to play corresponding video signals.
- I. Classification by application environment
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- The technical solutions adopted by the mainstream projectors currently on the market are basically divided into digital light processing (DLP) technology and 3LCD technology.
- The light sources used by the projector include traditional high-intensity gas discharge light sources (such as ultra-high pressure mercury lamps, short-arc xenon lamps, metal halide lamps) and new light sources represented by LED light sources and laser light sources. Conventional light source projectors usually make the projected image darker and yellower (such as brightness attenuation, reduced color saturation contrast, etc.) with the attenuation of the light emitted by the light source after a period of use. In applications where higher image quality is required Even if the bulb is still glowing, you have to replace it. Therefore, light attenuation has become a major obstacle that cannot be surpassed by projectors using traditional light sources. With the development of semiconductor lighting technology and laser technology, LED light sources and laser light sources have been rapidly developed not only in the lighting field, but also in a wide range of applications in the display field. LED is the earliest product used in projectors among new light sources. Because LEDs can make the imaging structure of projectors simpler, they are smaller, easy to carry, and simple to use. Projector products have brought teaching, business, and personal entertainment. Great convenience. At the same time, the emergence of laser as a new type of projection light source has solved the defects in brightness attenuation, color and power consumption of projectors using traditional light sources. At the same time, because it is a cold light source, it has an on-off Features, fundamentally eliminate the need to wait for the use of traditional light sources and stable lighting. [2]
- The performance indicators of the projector are the signs that distinguish the level of the projector, and there are mainly the following indicators:
- Light output
- Refers to the light energy output by the projector in units of "lumens" (lm). A physical quantity related to light output is brightness, which refers to the ratio of the light energy emitted by the screen surface to the area of the screen. The commonly used unit of brightness is "lux" (lx, 1lx = 1lm / m2). When the light output by the projector passes a certain amount, the larger the projection area, the lower the brightness, and vice versa. The factors that determine the light output of a projector include the area of the projection and screen, performance, and lens performance. Generally, the screen area is large and the light output is large. With liquid
- First, the projection environment light can not be strong, preferably low light
- The quality of a projector's projection is not only related to the brightness of the projection lamp, but also to the impact of the projection environment. Light from the projector's working environment
- projector
- Second, pay attention to the order of power switches
- Correctly turning on and off the power of the projector has a great impact on the service life of the projection lamp and internal accessories of the projector. If the power of the projector is turned off arbitrarily, the power of the projection lamp and the circuit part of the projector may be turned off together, and the cooling fan inside the projector will stop working due to power failure, which will cause the projection lamp and the projector to generate power during operation. A large amount of heat cannot be discharged through the cooling fan in a timely manner. This situation is likely to cause the projection lamp to explode, damage the internal circuit board, and prevent the projector from working properly. The correct operation sequence for switching the projector power on and off is: first turn on the power when turning on, and then continue to press and hold the indicator button on the projector control panel until it blinks; you can also use the power-on button on the remote control to issue a power-on instruction, The projector is turned on according to a preset startup procedure. When shutting down, you must not directly cut off the power supply of the projector. You should first press and hold the power off button until the light does not flash. (At this time, the cooling fan inside the projector continues to run for cooling, and it stops rotating after about 5 minutes); you can also issue a shutdown command through the shutdown button on the remote control. At this time, the CPU inside the projector will instruct the cooling fan to cool at full speed. At the same time, the CPU should detect the internal temperature of the projector. If it is above 40 ° C, it will issue a command to keep the cooling fan running. If it is below 40 ° C, it will issue a command to stop the cooling fan, and notify it by means of the indicator. Power off, and then cut off the power supply of the projector.
- Third, there should be a certain time interval after turning off and on again
- When the projector is switched from the on state to the off state, the cooling time should be at least 5 minutes. Because the projector's power supply uses the switching power supply method to step down and stabilize the mains power, and stabilize the power, the high-power switch tubes and transformers used by the projector's power supply work during frequent startup and shutdown switching operations. At higher frequencies, the switching tube will generate considerable power consumption during frequent switching. These lost power will be transferred into heat to be emitted, which will cause the temperature inside the projector to rise; coupled with the light bulb itself emits The heat is concentrated in a small space inside the projector, and sudden changes in temperature can easily cause the projection bulb to explode. In addition, if the projector's power is frequently turned on and off, it will also cause a large current impact on the projection bulb, which can easily cause the projection bulb. Damage; may also damage components in the circuit.
- Fourth, the power supply voltage used should be stable
- The stability of the power supply means that the projector and its signal source (that is, the computer connected to the projector and providing a projection signal to the projector) should be connected to the same high-quality power socket. The projector and its signal source use the same high-quality power socket, which can avoid the phenomenon of fire between the sockets when plugging in and unplugging the power supply, damage the power supply circuit inside the projector, and prevent possible power mismatch. Problems to ensure that the projector works properly. In order to prevent the explosion of the projection lamp and the mismatch of the working power of the projector, the power supply specifications used by the projector have strict regulations. When the user connects the projector to a power outlet. When the user plugs in or unplugs the signal cable or other circuits while under power, it will cause a fire between the plug and socket, damage the signal input circuit, prevent the projection lamp from working properly, seriously damage the projector, and even cause a fire accident. Therefore, you must use the power cord that comes with the projector. Sometimes because you need an extension cord, use a high-quality copper core for the power extension cord, and the wire diameter should not be too thin. At the same time, ensure that the power outlet connected to the power cord must be reliably grounded. .
- Five, can not work continuously for more than four hours
- If the projection lamp is continuously operated for more than four hours, the accumulation of heat from the imaging system inside the projector will cause the temperature inside the projector to rise rapidly, because the quartz on the inner wall of the projection lamp will devitrify at high temperatures. Phenomenon, white spots appear on the shell of the projection lamp, a large amount of devitrification will block the light from exiting, and the temperature of the local area of the projection lamp shell will rise abnormally, which will further expand the devitrification area, and rapidly reduce the brightness of the projection lamp. Can easily cause a light bulb to explode. Therefore, timely stopping the projector and cooling down is necessary to extend the service life of the projector and the projection lamp. Do not avoid: the duration of each projector's work cannot exceed four hours.
- 6. Abnormal shutdown and sudden power failure are strictly prohibited
- Most current projectors use cold light source systems. The electrical and light conversion efficiency of projection bulbs is high, and the heat generated is greatly reduced compared to the original metal halide bulbs. However, the current projectors are generally small in size and are locally It is easy to form accumulated temperature, and it is necessary to rely on the exhaust air channel to quickly dissipate heat. This requires that the cooling fan must continue to be powered on for a period of time after the power is turned off, so that the accumulated temperature inside the projector is released in time. Because of this, the projector is turned on and off. Switching operations must be performed strictly in accordance with the normal on and off sequence. Abnormal shutdown is a kind of erroneous operation that seriously violates the on and off procedures. This kind of misoperation can reduce the effective life of the projection lamp by 200 hours or more at a time, which is costly and must be avoided. Sudden power failure causes more serious damage to the projector than abnormal shutdown, because the sudden power failure makes the internal temperature of the projector too high, which may cause the chipset on the motherboard to malfunction, resulting in yellowing of the image and no signal output. .
- Seven, regular dust removal
- In the process of using the projector, it is often necessary to install a ceiling box to suspend it in the sky. This environment is easy to accumulate a large amount of dust, which easily leads to overheating protection for the projector when it is turned on for half an hour and cannot be turned on. In high temperature and humid seasons or regions, humidity will cause the dust accumulated on the projection lamp shell to form a cement-like film layer, which will cause the projection lamp to locally overheat, expand, contract, and burst during the working process. Therefore, regularly ask professionals to clean up the dust and prolong the service life. Based on the above reasons, the life of the bulb is to first shut down safely and fully dissipate heat. Secondly, keep the environment clean and tidy. Using it in too humid places will shorten the life of the bulb. However, at present, many projector products are equipped with good heat dissipation design and other means to improve the light source utilization rate, so that the life of the bulb has been extended. [3]