Along with the maturity of projection technology, the projector "shadow" that appears in the hands of users is mainly liquid crystal projectors and digital projectors. However, when using such a projector, the problem of projection color cast is often encountered, resulting in a drop in projection effect. Then why is there a projection color cast fault? How do we deal with it quickly when we encounter such a fault? I believe that the content below this article will give you a satisfactory answer!
Cause of projection color cast
Under normal circumstances, the liquid crystal projector will "decompose" the strong light into red, green and blue color light through the internal optical processing system. These three color lights are respectively transmitted through the process of transmission, AD conversion, modulation, etc. On the three liquid crystal panels, the optical path control unit is used to realize the normal switching of the color light, and the last three color lights are synthesized in the projection prism to form a color image and output on the projection screen through the projection lens.
The DLP digital projector processes the color of the projected image through the color wheel technology based on red, green and blue colors. The realistic degree of the projected color is closely related to the number of projector DMD micromirrors. If processed by the projector optical system, it is output.
When one or two colors are missing from the three-color projection light, the image appearing on the screen will have a significant color cast failure. It is obvious that the most important cause of projection color cast is the internal optical processing system of the projector. After being interfered by "external force", the image color cannot be correctly processed and "expressed". Of course, the "external force" here contains many factors. Projection color cast caused by different factors needs to be solved in different ways.
Projection color cast
There is a Hitachi projector in the unit, and its "service" time is almost two and a half years. Recently, for some reason, the image image projected by the projector always has a noticeable color cast phenomenon. At first, the author also thought that it was a cold feeling, and did not put this phenomenon on the mind. However, in the future projection days, the projection color cast fault could not be eliminated. It is obvious that the projector is really onset. In desperation, the author decided to carry out a thorough inspection of the projector.
The author first checked the connection line between the projector and the computer, and found that the computer connected to the projector is a Founder desktop computer of the Celeron 733. Will it be a mixed line inside the VGA data cable connecting the projector and the computer? , causing serious crosstalk in the projection signal? First of all, first remove the interface of the VGA data cable at both ends! Take apart the interfaces on both sides of the VGA data cable, and separate each of the signal lines. After the detection, no faults such as signal line articulation, disconnection, and shorting were found.
In order to verify whether the projector or the signal line is faulty, the author uses the same VGA data cable to connect the projector to another computer. After turning on the power again, it is found that the projection screen of the projector output on the screen is not There is color cast, and the effect looks very clear. It is obvious that the projector and the VGA data cable are normal. The problem is most likely caused by the Founder computer that the projector was previously connected to.
So the author checked the Founder computer and wanted to see if the display resolution parameter of the computer was within the support of the projector. When I opened the display property setting window of the Founder computer, I found the "color" of the computer. The parameter is set to 16-color enhanced color, the "Display Resolution" parameter is set to "800x600", and the "Refresh Resolution" parameter is set to 75Hz; after comparing these parameters one by one with the projector's related specifications, It was found that the projector supports all display parameters of the Founder computer, which indicates that the projection color cast fault is not caused by the Founder computer itself!
After the above efforts, the preliminary analysis found that the VGA data line and the projector itself are normal, the Founder computer connected to the projector is also normal, and the setting of the projection display parameters is also correct. Then in addition to the above factors may cause projection failure, what other factors can cause the projector to have a color cast failure?
Will it be caused by the power socket connected to the projector's power cable? I thought of it, quickly unplug all the plugs on the socket, and use a multimeter to test the output voltage of the power outlet, but the test value shows The power outlet is stable and there is no abnormality.
But the author is not at ease with the results of the test, intend to replace the power socket with a new one, after all, through the alternative method can confirm whether the power outlet is really faulty, which can narrow the scope of troubleshooting and improve the efficiency of troubleshooting. When the author replaced the old socket with the newly purchased power socket, the miracle appeared. There was a projection color cast fault, and now the projection is very clear and there is no color cast.
Why is this happening?? I can't think of it. Can a small power outlet pick up such a big "wind wave"? After some "opening the belly" of the old socket, I found the zero line inside the socket. It turned out to be "the sin and the culprits."
The ground wire inside the original socket is inadvertently touched with the zero wire. If the power socket is tested with a multimeter without a plug connection, the test will be normal, but once the plug is plugged in, between the neutral wire and the live wire. The power circuit will cause the ground wire of the socket to be charged. As a result, the current on the ground line will flow back to the projector and the computer through the plug, which will easily cause the projection signal to be interfered by the electrical signal, resulting in projection. Color cast failure.
When I tried to separate the ground wire and the neutral wire inside the socket and ensure that the power socket was reliably grounded, the projector and the computer were connected to the repaired old socket again for projection, and the projection color cast fault disappeared immediately.
Coping with projection color cast
In fact, there are still many factors that cause the projector to have a color cast. The projection color cast fault caused by different factors needs to be handled by different methods. In order to help the projection users to effectively and quickly eliminate the color cast failure, the author has specifically summarized some countermeasures below, hoping to help you!
1. Replace the bulb in time
As we all know, each projector's bulb has a certain service life. When projecting near the life of the bulb, the bulb often cannot display the color of the image processed by the projector vividly and clearly. Image images often give people a feeling of color cast.
To eliminate the color cast fault caused by the light bulb not shining, the only way is to replace the projector's light bulb in time to make the projected color re-bright and clearly output to the projection screen. It is worth noting that the bulb is best to use the same brand as the projector, and when installing the bulb, please do not touch the bulb directly, because the bulb surface has a special protective layer. If it is directly touched by hand, it may be The surface leaves traces that affect the projected color output.
2, correctly connect the signal line
Many people think that connecting the projection signal line is very easy, but the simpler things are often more overlooked. This is not the case. Once the signal line of the projector is not firmly fixed on the VGA port of the computer or projector, the phenomenon of poor contact may occur. The projection color cast failure caused by this phenomenon is often difficult to notice. In addition, when the signal line interface is inserted into the VGA port of the computer or projector, if the position is not correct, the force of the plugging and pulling is too strong, it is easy to bend or break the core at the signal line interface, which is easy to cause The projector has a color cast failure. There is also a VGA signal cable connecting the projector and the computer. If the length exceeds 15 meters, the projection signal will be seriously attenuated, which will inevitably lead to projection color cast failure.
In order to eliminate the projection color cast fault caused by improper signal line connection, you must do the following:
First, when connecting the signal cable to the VGA port, first align the port position, and then use the force to ensure that the needle core and the VGA port are reliably in contact with the VGA port. Never use brute force during insertion to break the needle. core;
Then carry forward the spirit of not being bothered, tighten the screws for fixing the position, and ensure that the projection signal line and the VGA port are stably and firmly connected together, and there is no slight shaking;
When selecting the projector data cable, please try to use the randomized projection signal cable instead of using the signal cable of other projectors. In addition, to prevent excessive attenuation of the projection signal, please ensure that the cable length cannot exceed 15 Meter;
Once you have a projected color cast, try connecting the projector directly to the computer with a signal cable instead of using a display splitter or signal amplifier, as color cast failures can also be caused by intermediate processing of these signals.
3, please ask someone to repair in time
During long-term use, some components inside the projector often age, or the internal components may loosen or fall off when the projector moves frequently. This may cause the projector to have a projection color cast fault. Under normal circumstances, in order to solve the projection color cast fault caused by the projector's own hardware failure, it is best to ask professional maintenance personnel to check and repair, instead of doing it yourself, freely open the projector casing, which is easy to damage the projection. machine.
4, set the projection parameters
If the color display parameters of the projector do not match the screen display parameters of the computer, or if the color display parameters inside the projector are not set correctly, it may cause the projector to have a color cast failure. In the elimination of this fault, as long as patience and meticulousness, it is sufficient to readjust the projection parameters; in addition, adjust the display parameters of the projector and computer as much as possible to ensure that they match exactly.
5, away from electromagnetic interference
Since the signal signal cable on the projector transmits a weak signal, such a signal is easily interfered by an external electric field or a magnetic field, thereby causing a color cast failure or instability of the projected picture. In order to avoid such a fault, you should not put the signal cable of the projector with the high-voltage power line or other communication cable, and do not let the signal cable pass through the door or window gap, not to have a strong magnetic signal. Place a projection presentation.
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