Principle of illuminance meter The ordinary pocket electronic illuminometer uses a photoresistor as a photoelectric conversion device, which comprises a DC power source, and is sequentially connected in series with a voltage conversion circuit, a switch, a photoresistor, a test circuit, an A/D converter, a decoder, and the like at the output end of the DC power supply. Display driver and display. The utility model avoids the use of an optical head. The DC power supply can only use a 3V battery, and the decoder, the display driver and the display are integrated on an integrated circuit card, so that the structure is simple, the volume is small, the movement is easy, and the reaction is sensitive. advantage. Illumination test principle Illuminance is the areal density of the luminous flux received on the illuminated surface. Illumination juice is an instrument used to measure the illuminance on the illuminated surface and is one of the most used instruments for illuminance measurement. The principle of the illuminometer The illuminance meter consists of a photometric head (also known as a light-receiving probe, including a receiver, a V(λ) pair filter, a cosine modifier) ​​and a reading display. An ideal pocket illuminometer should have the following conditions: · Small size and light weight The illuminance meter has a wide range of opportunities to use, and the timing of the operation is often in different places, so the portable body is small and light weight is the first prerequisite for the illuminometer. · Accuracy Whether the illuminance meter is good or not has an absolute relationship with its accuracy. Of course, it is also closely related to its price. Therefore, it is necessary to buy a higher-accuracy illuminance meter at a reasonable price. Generally, the error is not more than ±15%. · Color compensation The types of light sources are all-inclusive, some are red-type high-pressure lamps with longer wavelengths, or shorter blue-violet lights such as Daylight fluorescent lamps; there are also relatively even distributions such as incandescent bulbs. The sensitivity of the same illuminometer may be slightly different for different wavelengths. Different, so moderate compensation is necessary. · Cosine compensation As we all know, the brightness of the illuminated surface is related to the angle of incidence of the light source. For the same reason, when measuring with an illuminometer, the angle of incidence between the sensor and the source will naturally have an effect on the reading of the meter. Therefore, whether a good illuminometer has cosine compensation function can not be ignored. Illuminance meter precautions 1 Photocells use a good linear selenium (Se) photocell or silicon (Si) photocell; still maintain good stability and high sensitivity for long-term operation; high-E, use high internal resistance photocell, its sensitivity is low and linear It is not easily damaged by strong light. 2 The V(λ) correction filter is paid in, and the illumination of the heterochromatic temperature source is suitable, and the error is small. 3 Add a cosine angle compensator (opaque glass or white plastic) in front of the photocell. The reason is that the photocell deviates from the cosine rule when the incident angle is large. 4 The illuminometer should work at or near room temperature (photocell drift changes with temperature). Digital Display Test Pen ,Power Tester Pen,Voltage Pen,Digital Voltage Tester YINTE TOOLS (NINGBO) CO., LTD , https://www.yinte-tools.com