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2016August

LED light emitting diode characteristic test (two)

From: www.szbako.com Data:07/08/2016

3 measurement results and analysis of the 3.1LED

of the volt ampere characteristic

by Figure 1 measured at room temperature 5 kinds of color LED volt ampere characteristic curve is shown in figure 6. Such critical conduction state voltage known as the threshold voltage, according to the figure 7 in the fitting formula calculate the fitting line and the horizontal axis intersection to get the normal voltage of 5 kinds of LED, for follow-up testing of normal lighting conditions to prepare. According to the formula & lambda; [(HC) /e]Ud and the data, the calculation of light emitting diode light-emitting wavelength and the theory of the main wavelength anastomosis. By Figure 6. At the start of the current led along with the change of voltage is almost constant, greater than the threshold voltage, current with voltage to the change of 104~236mA/V rate increased linearly, one of the fastest growing square red LED, and a round white led growth most slowly. The normal operating voltage, threshold voltage and luminous wavelength of 5 kinds of LED are shown in table 1. Table 1 shows that in addition to the red square of the LED, the other 4 normal voltage, threshold voltage of about 3V and 2V, respectively, the red square LED of the longest wavelength, the other 4 LED light-emitting wavelengths are around 500nm. The intensity distribution of the light intensity distribution characteristic of

3.2

is shown in Figure 8, LED LED. The light intensity distribution curve can properly reflect the spatial distribution of the energy of the light source. The luminous range of 5 kinds of LED can be determined from the spatial distribution of light intensity. The luxmeter sensor area is 3 ml, testing radius 8cm, by calculating the income data with the international standard of measurement of LED's light intensity data consistent, namely the measured light source can be approximated as point source . From the measurement results, it can be found that the square LED has more directivity, and all the LED intensity is the strongest at the center normal. Commonly used semi value angle description LED light distribution characteristics, half value angle θ smaller corresponding to the stronger (see Table 2), which can be used for the user to choose the reference.

the spectral characteristics of the

3.3 led the TCS230 color sensor spectral measurements in the camera obscura. In this paper, the color sensor is red, green, blue, transparent 4 sets of filter integration, light intensity through the photodiode, the circuit is converted to pulse output. It is applied to measure the five color LED emission spectra and the measurement results and monochromator measured results were compared, color sensor to measure the accurate condition judgment. Monochromator and color sensor measured spectral characteristic curve as shown in Figure 9 and 10, the color sensor for measuring the luminous components such as shown in Figure 11. We can see from the measurement results, the color sensor in the 480~635nm range, and the measured results are basically the same monochromator.

peak wavelength is an important parameter to describe the characteristics of the spectrum. The experimental results show that the peak wavelengths of red, blue and green LED are in the range of the main wavelength, as shown in table 3. The intensity distribution of the light intensity distribution characteristic of

3.2

is shown in Figure 8, LED LED. The light intensity distribution curve can properly reflect the spatial distribution of the energy of the light source. The luminous range of 5 kinds of LED can be determined from the spatial distribution of light intensity. The luxmeter sensor area is 3 ml, testing radius 8cm, by calculating the income data with the international standard of measurement of LED's light intensity data consistent, namely the measured light source can be approximated as point source . From the measurement results, it can be found that the square LED has more directivity, and all the LED intensity is the strongest at the center normal. Commonly used semi value angle description LED light distribution characteristics, half value angle θ smaller corresponding to the stronger (see Table 2), which can be used for the user to choose the reference.

the spectral characteristics of the

3.3 led the TCS230 color sensor spectral measurements in the camera obscura. In this paper, the color sensor is red, green, blue, transparent 4 sets of filter integration, light intensity through the photodiode, the circuit is converted to pulse output. It is applied to measure the five color LED emission spectra and the measurement results and monochromator measured results were compared, color sensor to measure the accurate condition judgment. Monochromator and color sensor measured spectral characteristic curve as shown in Figure 9 and 10, the color sensor for measuring the luminous components such as shown in Figure 11. We can see from the measurement results, the color sensor in the 480~635nm range, and the measured results are basically the same monochromator.

peak wavelength is an important parameter to describe the characteristics of the spectrum. The experimental results show that the peak wavelengths of red, blue and green LED are in the range of the main wavelength, as shown in table 3. The intensity distribution of the light intensity distribution characteristic of

3.2

is shown in Figure 8, LED LED. The light intensity distribution curve can properly reflect the spatial distribution of the energy of the light source. The luminous range of 5 kinds of LED can be determined from the spatial distribution of light intensity. The luxmeter sensor area is 3 ml, testing radius 8cm, by calculating the income data with the international standard of measurement of LED's light intensity data consistent, namely the measured light source can be approximated as point source . From the measurement results, it can be found that the square LED has more directivity, and all the LED intensity is the strongest at the center normal. Commonly used semi value angle description LED light distribution characteristics, half value angle θ smaller corresponding to the stronger (see Table 2), which can be used for the user to choose the reference.

the spectral characteristics of the

3.3 led the TCS230 color sensor spectral measurements in the camera obscura. In this paper, the color sensor is red, green, blue, transparent 4 sets of filter integration, light intensity through the photodiode, the circuit is converted to pulse output. It is applied to measure the five color LED emission spectra and the measurement results and monochromator measured results were compared, color sensor to measure the accurate condition judgment. Monochromator and color sensor measured spectral characteristic curve as shown in Figure 9 and 10, the color sensor for measuring the luminous components such as shown in Figure 11. We can see from the measurement results, the color sensor in the 480~635nm range, and the measured results are basically the same monochromator.

peak wavelength is an important parameter to describe the characteristics of the spectrum. The experimental results show that the peak wavelengths of red, blue and green LED are in the range of the main wavelength, as shown in table 3. The intensity distribution of the light intensity distribution characteristic of

3.2

is shown in Figure 8, LED LED. The light intensity distribution curve can properly reflect the spatial distribution of the energy of the light source. The luminous range of 5 kinds of LED can be determined from the spatial distribution of light intensity. The luxmeter sensor area is 3 ml, testing radius 8cm, by calculating the income data with the international standard of measurement of LED's light intensity data consistent, namely the measured light source can be approximated as point source . From the measurement results, it can be found that the square LED has more directivity, and all the LED intensity is the strongest at the center normal. Commonly used semi value angle description LED light distribution characteristics, half value angle θ smaller corresponding to the stronger (see Table 2), which can be used for the user to choose the reference.

the spectral characteristics of the

3.3 led the TCS230 color sensor spectral measurements in the camera obscura. In this paper, the color sensor is red, green, blue, transparent 4 sets of filter integration, light intensity through the photodiode, the circuit is converted to pulse output. It is applied to measure the five color LED emission spectra and the measurement results and monochromator measured results were compared, color sensor to measure the accurate condition judgment. Monochromator and color sensor measured spectral characteristic curve as shown in Figure 9 and 10, the color sensor for measuring the luminous components such as shown in Figure 11. We can see from the measurement results, the color sensor in the 480~635nm range, and the measured results are basically the same monochromator.

peak wavelength is an important parameter to describe the characteristics of the spectrum. The experimental results show that the peak wavelengths of red, blue and green LED are in the range of the main wavelength, as shown in table 3.

3.4 LED light power and current relation

3.5 LED light-emitting efficiency and current relationship

luminous efficiency is refers to the luminous body stimulated the absorption energy conversion for solar energy, it is characterization of luminous body function of the important parameters. Experimental measurement of the light intensity of E. 5 using LED formula

calculated flux Φ. Type s is the receiver of the hemisphere area illumination table, n LED light-emitting angle and the measured illuminance table hemisphere area and illumination table receiver distance D satisfying the & PI; d2=S. 13 is calculation principle diagram and reuse & ETA; =Φ /P (P=UI) to calculate the luminous efficiency & ETA;. Finally, the relationship between the luminous efficiency and the current curve is shown in Figure 14. By Figure 14 shows white, green square, round white, red and blue light emitting efficiency decreased, their power to conversion to solar energy in order to reduce. Theoretically we can see that the luminous efficiency of these 5 kinds of LED has the trend of first increasing and then decreasing. As a result of the gradual increase of current, the probability of electron non radiative recombination of the injected light region becomes larger, so that the luminous efficiency is reduced.

4 conclusion LED using conventional experimental instruments, set up a

test system. The principle of this system is clear, and the measurement method is simple. Operable, large measurement range. Experimental measurements of five led normal light voltage 1~4V, threshold voltage 1.5~3V, light-emitting wavelength is consistent with the main wavelength; square led a more rounded direction; each with the color of the LED are non single color light, but their peak wavelength and the main wavelength consistent. Test results show that the measured results are in agreement with color sensor test spectra with monochromator; luminous flux measurement method can achieve without integrating sphere and other instruments to achieve simple measurement; in a certain range, 5 kinds of LED light power increases with the increase of the current, but their luminous efficiency decreased with the increase of current.

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