led, light source and so on, luminous flux measurement is more difficult, then we should be measured with an integrating sphere. illuminance illuminance illuminance per unit area is accepted by the amount of incident light. in imperial units, the 1 square foot of area received a lumen, defined as 1footcandel. metric units, 1 lumen per square meter to 1 lux (lux), 10.76lux = 1footcandle. of course, the probe can not have such a large area, so the size of the probe must be multiplied by the appropriate multiple. led sign board
led (light emitting diode) because of its high intensity, low power consumption, long life, high reliability, easy to drive, easy to link up with the ic characteristics, has been widely used in transportation, commercial advertising and instrumentation displays. the impact of a variety of led color display is a key factor that determines the color of led is its wavelength characteristics, due to the relative spectral power distribution of led is a narrow-band quasi-monochromatic light spectrum, so the wavelength measurement of led particularly important.led message displays
positive led reverse leakage current ir color led light colors at points, can be divided into red, orange, green (and yellow segments, the standard green and pure green), blue and so on. in addition, some light-emitting diode contained in two or three colors of chips. light emitting diode based on doped or not doped at the scattering agent, colored or colorless, the various colors of light-emitting diodes can also be divided into colored transparent, colorless, transparent, colored the number of different led illuminated, then the output level changes. figure 9 is constituted by the five led level meter. when the input signal level is low, and do not have light. input signal level increases, the first light led1, led2 and then increase the light ... ....   (v) the resistance to 200kω, reverse resistance value of α. if the forward resistance value of 0 or ∞, reverse resistance is very small or 0, then damaged. this detection method can not actually see the luminous led, because × 10kω block can not。led message display

figure 14 (a) below. if the digital form for the common cathode, which should drive level or source emitter output circuit, as shown in figure 14 (b) below. picture this subject as follows: for example, domestic ttl integrated circuits ct1049, ct4049 for the open collector driver circuit decoding the form of seven-segment-shaped; and cmos integrated circuits for the source output cc4511 seven segment latch decoder driver circuit. (2) control led driver stage control circuit (also known as drive circuit) has a static type and dynamic type categories. ① static drive: the static drivers, also known as the dc drive. display boards
at present, some models of transistor hfe multimeter scale with measurement lines and test sockets, can easily measure the magnification of the transistor. first multimeter function switch to  block, the range switch to the adj position, the red, black table pen shorted, the zero adjustment knob, so that the multimeter pointer indicates zero, and then switch to the hfe position range and make the two short then the table t to separate the transistor under test into the test socket, you can read from the pipe line hfe scale magnification. custom neon signs
r & d and quality testing in the laboratory equipment, basically meet the domestic demand for led product development in general. domestic instruments tend to have relatively large price advantage, and only a fraction of the imported equipment, which many domestic small and medium enterprises led products that improve the quality of the early play a positive role. however, due to technological level of manufacturing of certain equipment and the knowledge gap between the led measurement standards so that all manufacturers are often among the instruments to measure the results of obvious differences.advertising sign boards

led seet light system reliability, durability, performance index part of the adaptation to the environment, the general led lighting product design and were not taking into account the dust protection system, outdoor lighting must completely prevent the road with sand dust storm, gelatinous suspension, gravity dust accumulation on the cooling sucture, to avoid overheating of the led caused problems. neon signage
 such savings may greatly increase, because the led lighting system does not need any warming period, you can "instant-on" work, so in a very short period of time to reach maximum intensity. by these lights off when not needed to, or use motion conol sensors in order to avoid these lights work 24 hours a day, this plant can also save a lot more energy. figure 3: a high brightness white led lamp with high pressure sodium lighting refinery is another major advantage of the quality of light output. as can be seen in figure 3, left part of the plant is led lighting, led full-specum white light, and high-pressure sodium lamp (right side) compared, in which light is easier to see, and high pressure sodium light from almost all regions in the chromatography of the orange, which is very difficult to distinguish colors. in the refinery, which in particular is hard for me to use the naked eye because the distinction between water vapor and smoke caused by fire is a very painful thing.neon sign
 to be able to accurately identify the wire color and color im is very important (even in dim light conditions). finally, the white led with 10 million hours of working life, working 24 hours a day, will continue to use more than 11 years, compared with high-pressure sodium lamps need to be replaced every year or two. high pressure sodium lighting and compared to the current, which further reduces the overall long-term high-brightness led costs. this white led lighting applications in the summary of indusial / residential area of general lighting has led to an unprecedented acceleration of large current led driver ic for many of the specific performance requirements. from oriented refinery, power plants and other harmful indusial applications of high power external lighting to the internal moving projection lighting, there are many indusial applications.message signs