CN201069386Y - LED optical pass testing device - Google Patents

Abstract

The utility model belongs to the technical field of light source measurement, specifically a LED light flux measurement device. The device comprises a reflection cup, a clamp, a light-flux meter and a power supply, wherein the clamp fixes a LED at the bottom of the reflection cup, the LED emits light towards the opening of the reflection cup, the light-flux meter is tightly fixed at the opening of the reflection cup to receive optical signals, the power supply is a constant-current power supply for driving the LED. The total light flux of the LED is focused by the reflection cup and then collected and measured by the light-flux meter, and finally the light-flux meter displays the value of total light flux. The utility model has the advantages of simple structure and high measurement accuracy.

Description

LED Luminous Flux Test Device

technical field

The utility model belongs to the technical field of light source measurement, in particular to an LED luminous flux testing device.

technical background

After the semiconductor technology triggered the microelectronics revolution, it is gestating a new industrial revolution---lighting revolution. The characteristics of light-emitting diodes (LEDs) make them widely used in the fields of display and special lighting. However, the theoretically high luminous efficiency of LEDs makes it a huge potential application prospect in the general lighting market. In various LED applications, external quantum efficiency is an important indicator of LEDs, that is, the ratio of outgoing luminous flux to injected electrical energy.

The difficulty in testing LED external quantum efficiency lies in the testing of luminous flux. Due to the characteristics of LED, there is no internationally recognized simple test method that can be similar to the traditional light source luminous flux test method.

The problems existing in the existing LED luminous flux testing methods include:

(1) When using traditional methods such as placing light sources and shielding screens in the integrating sphere, since the luminous flux sphere of the test LED is generally small, even with a diameter of only 5cm, the integrating sphere theory will not be satisfied, resulting in a fundamental error in the test;

(2) If it is placed on the surface, conventional standard lamps that emit light in all directions cannot be used, and the use of LED standard lamps has the problem that spectral calibration cannot be achieved.

These problems have caused differences in the test of LED luminous flux, which has also affected the judgment of LED performance, which is not conducive to the development of the LED industry.

Contents of the invention

The purpose of the utility model is to provide a device with simple structure and accurate measurement of LED luminous flux.

The device for measuring LED luminous flux proposed by the utility model is composed of a power supply 1, a fixture 2, a reflective cup 4 and a luminous flux meter 5, wherein the fixture 2 fixes the LED to be tested on the bottom of the reflective cup 4, and the LED light-emitting direction points to the opening of the reflective cup , the luminous flux meter is fixed at the opening of the reflector to receive the light signal; the power supply adopts a constant current power supply to drive the LED.

In this utility model,

1. Fixtures of different structures can be used to cooperate with visible light LEDs in different packages to ensure that the luminous center of the visible light LED is positioned near the bottom of the reflector cup.

2 The reflective cup is used as the luminous flux collection device of the measured visible light LED, and the reflectivity of the evaporated reflective film on the inner wall of the reflective cup is 99%.

3 The luminous flux meter uses silicon photocells as the probe material, and a cosine corrector and V(λ) filter are installed on the light-receiving surface of the probe. The V(λ) filter is used to realize the matching response between the probe and the visual function of the human eye, and the cosine corrector is used to correct the optical signal response in different directions. The probe fits tightly to the light outlet of the reflector to ensure that the emitted light falls completely within the detection range of the photocell. The structure of the luminous flux meter is shown in Figure 2.

Description of drawings

Figure 1 is a schematic diagram of the LED total luminous flux testing system.

Fig. 2 is a schematic structural diagram of a silicon photocell luminous flux meter.

Labels in the figure: 1 constant current power supply, 2 LED fixture, 3 LED to be tested, 4 reflector cup, 5 luminous flux meter, 6 cosine corrector, 7V (λ) filter, 8 silicon photocell detector, 9 current-voltage conversion circuit, 10 operational amplifiers, 11 monitors.

Detailed ways

The used elements of the utility model are as follows:

LED3: LED light source under test;

Reflective cup 4: A reflective cup used to gather LED luminous flux. The basic principle is that the inner surface of the cup is evaporated with a reflective film with a high reflectivity of 99% to form a reflective surface. The surface reflects the incident light to the direction of the large opening to achieve light collection. . The specific shape of the cup body can be a cone, a rotationally symmetrical body with a parabola as its generatrix, etc., which can realize the light gathering function.

Power supply 1: constant current power supply;

Luminous flux meter 5: a luminous flux meter with a silicon photocell as a detector;

Instrument assembly process:

Assemble according to Fig. 1, and the LED 3 to be tested is fixed at the bottom of the reflective cup 2 by a clamp. The detection surface of the silicon photocell of the luminous flux meter 5 is installed close to the light outlet of the reflective cup.

The luminous flux meter is a conventional device, consisting of a cosine corrector 6, a V(λ) filter 7, a photodetector 8, and subsequent circuits including a current-voltage conversion circuit 9, an operational amplifier 10, and a display 11.

The following is a specific embodiment of the present invention for testing the luminous flux of a visible light LED.

The main devices required for a test:

1. LED fixtures, in line with the current packaging forms of mainstream visible light LEDs, different package types and different package sizes with different fixtures to position the luminous center of visible light LEDs at the bottom of the reflective cup.

2. Reflective cup, the inner wall of the cup is evaporated with a reflective film, and the reflectivity of the film layer is 99%.

3. Luminous flux meter, the probe of the luminous flux meter adopts silicon photocell, and uses cosine corrector and V(λ) filter to correct it.

Two test process

Test with the device shown in Figure 1, the ambient temperature is 25°C, the LED model to be tested is CREE XR-E, driven by a constant current of 80mA.

The test starts after the LED has warmed up for 15 minutes. The output of the luminous flux meter is obtained as 1.631m.

In order to verify the accuracy of the experimental results, the same LED was measured twice with a small goniophotometer. The test environment temperature is the same as 25°C, the driving current is 80mA, and the LED is preheated for 15 minutes to start the test.

The goniophotometer used is the LED626 goniophotometer produced by Hangzhou Yuanfang Information Co., Ltd. The test accuracy of the instrument is:

Forward current test accuracy ±0.2%F.S. Forward voltage test accuracy ±0.2%F.S. Reverse voltage test accuracy ±0.2%F.S. Reverse Leakage Current Test Accuracy ±0.2%F.S.

The test results are as follows: the total luminous flux of the tested LED is 1.7181m

Since the method of measuring the total luminous flux of the light source by the goniophotometer is an absolute measurement method of luminous flux, the measurement accuracy is very high. Comparing the measurement results obtained by the two methods, we can see:

Test results of the present invention (1m) Goniophotometer test results (1m) 1.63 1.718

Compared with the test result of the goniophotometer, the measured result of the new type has only 5% difference, which is more advantageous in accuracy than the nearly 10% error of the method of measuring LED luminous flux with an integrating sphere.

Claims (4)

1. LED luminous flux proving installation, it is characterized in that forming by power supply (1), anchor clamps (2), reflector (4) and lumen meter (5), wherein, anchor clamps (2) are fixed on LED to be measured the bottom of reflector (4), the LED light emission direction points to the reflector opening, lumen meter is fixed on the opening part of reflector, in order to receiving optical signals; Power supply adopts constant-current supply, driving LED.

2. LED luminous flux proving installation according to claim 1, the inwall reflectivity that it is characterized in that described reflector (4) is more than 99%.

3. LED luminous flux proving installation according to claim 1 is characterized in that described reflector (4) is the taper or the paraboloid of revolution.

4. LED luminous flux proving installation according to claim 1 is characterized in that described lumen meter (5) is connected to form successively by cosine corrector (6), V (λ) optical filter (7), photodetector (8), current-to-voltage converting circuit (9), operational amplifier (10), display (11).

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