South America Series Extension Sockets Cordless Extension Socket,External Extension Socket,Socket And Extension Lead,Switchable Extension Socket Heikki Technology Co., Ltd. , https://www.heikkipower.com For the image on the screen, it is necessary to have sufficient brightness and a light source that is close to the white light to meet the visual needs of the majority of moviegoers. Therefore, in order to improve the clarity of the film image, the performance of the film projection source is the basis for determining the brightness and color of the image on the screen; the spectral characteristics of the projection source are the key to determining the true color of the image; the whiteness of the screen, the size of the screen, The position of the projection lamp, the age of the projection lamp, and the luminous efficiency are the decisive factors in determining whether the brightness and color of the image can be obtained.
From our technical inspection of film projection equipment, there are quite a few film screening units, the sound and light effects are not up to the specified technical indicators, and some of the light equipment of the Xenon film projection equipment only stays at the level of the bromine tungsten lamp, serious Affected the quality of film screening, affecting the audience's viewing effect. We analyze this, mainly in the following aspects:
First, the size of the screen area and the quality of the image
We know that when the effective luminous flux of the film projection source is constant, the light is filled over the entire screen, and the size of the screen determines the brightness of the screen. If the screen area is larger, the more scattered the light on the screen, the smaller the illumination, the lower the brightness, and the darker the picture becomes. For mobile film projection equipment, the screen area is generally 3.6 m × 2.7 m. If the screen area is arbitrarily large, that is, changing the length of the projection distance or the focal length of the projection lens, it is impossible to achieve an ideal image effect on the screen, so it is strictly enforced. Film projection technical standards can improve the sound quality of film projections.
Second, the degree of whiteness of the screen and the effect of reflection coefficient on the film picture
The brightness of the screen is proportional to the effective luminous flux of the film projection source and the reflection coefficient of the screen, and inversely proportional to the area of ​​the screen. The reflection coefficient is proportional to the brightness of the screen and inversely proportional to the illumination of the screen. In the case where the illuminance is constant, the smaller the reflection coefficient, the higher the brightness of the screen. The central brightness of the standard screen of the national standard mobile film projection equipment should reach 45±2032 square meters. If it exceeds the national standard brightness, the screen will feel glare and make the audience unable to watch. The whiteness of the screen directly affects the screening effect. During the inspection, we found that the screening units generally did not pay enough attention to the screen protection. The screen brings together the audience's attention and can directly reflect the management level and professional quality of the film team. We have found that many unit screens have become gray-black, and have not been cleaned or replaced for many years, making the screen dusty and stained; some are not as white as the walls. In particular, the screen of the landline projector unit is hung on the stage, and there is no protective curtain. In addition, some auditoriums are worn out and dusty. Even if you buy a new screen, if you don’t use protective devices, it will not be used for a long time. . The mobile film screening unit encounters rain and snow during the open air show. If it is not dried in time, it will cause the screen to become mildewed, blackened and unevenly white. The darker the screen, the worse the screening effect. In short, protecting the whiteness of the screen has a great influence on the image effect. Welcome to China Home Theater Network
Third, the effective life of the projection bulb determines the brightness of the screen
For a projection device using a xenon lamp source, the cumulative ignition time from the use of the xenon lamp to the initial value of the effective luminous flux down to 70% at the rated power is called the effective life of the xenon lamp. If the effective luminous flux drops to an initial value of 70%, the optical flow density distributed on the screen surface is smaller. The light reflected from the surface of the screen is weaker, and vice versa. In general, high-power xenon lamps have an average life of more than 800 hours, so special attention should be paid to the maintenance of xenon lamps.
Fourth, the degree of cooperation of the various components of the projection optical system on the brightness of the screen
For the optical system, each component must meet the technical requirements. After adjustment, the axis of the xenon lamp and the center of the door hole are in a straight line. When the bulb and the reflective bowl are adjusted, it should be repeated until the brightness of the screen is optimal. . If the adjustment is not optimal, the effective luminous flux of the projection will be greatly reduced. There are a few units that use the current to adjust the arc discharge to increase the brightness of the screen. The larger the current, the greater the arc power, and the higher the brightness of the screen. This method of increasing the brightness of the screen is extremely wrong. This will speed up the aging of the bulb and greatly shorten the effective life of the xenon lamp.
5. The obsolescence and dirtyness of the projection optical components cause the effective luminous flux of the projection light source to decrease.
The reflective bowl is severely stripped. The main reason for the film peeling off of the reflective bowl is that it does not pay attention to heat dissipation during the use of the projector. In particular, the mobile Xenon movie projection equipment should be cooled when the film is finished. It is not possible to turn off the switch immediately. Because the temperature of the lamp is very high, if the heat is not paid attention to, it is easy to release the reflective bowl, especially in the summer. serious. Fixed film projection equipment, the design of the exhaust pipe is unreasonable, the seal is not good, the elbow is too much, the pipe is too long, especially the two machines use one exhaust fan, the power is small, etc.; in addition, the bulb glass bulb is close to the reflective bowl. This is mainly due to improper adjustment, so that the reflective bowl is unevenly heated, causing the film layer to fall off. The shelf life of the spare reflective bowl is too long, and the quality of the reflective bowl itself is poor. Some units do not pay attention to the maintenance of film projection equipment. The surface of the reflective bowl is covered with a thick layer of dust and oil stains, which makes the temperature of the reflective bowl rise. All of the above reasons eventually lead to a decrease in the brightness of the screen, which affects the screening effect. Therefore, to protect
Keep the reflective bowl clean, remove dust and oil in time, maintain the high reflectivity of the reflective bowl and the transmission of infrared light, reduce the temperature and extend the service life of the reflective bowl.
Sixth, the projection room design does not meet the requirements, it will also cause the screen brightness to drop.
The design of the projector room is mainly designed according to the technical indicators according to the layout of the auditorium. If the projection window is too small during the design and reconstruction process, and some projectors are slightly biased toward the side of the projection window, a large part of the light emitted by the projection source will be blocked. There are also very few units that do not pay attention to technical requirements when designing and remodeling the machine room. The hole in the projection window is artificially reduced, causing excessive light loss and reduced brightness of the screen. Therefore, when designing and renovating the projector room, technically good quality can be used to present an image that satisfies the audience on the screen.