CN103743481A - Extremely-low-lost detection-range-adjustable light intensity detection circuit - Google Patents
Extremely-low-lost detection-range-adjustable light intensity detection circuit Download PDFInfo
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- CN103743481A CN103743481A CN201310667387.1A CN201310667387A CN103743481A CN 103743481 A CN103743481 A CN 103743481A CN 201310667387 A CN201310667387 A CN 201310667387A CN 103743481 A CN103743481 A CN 103743481A
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- light intensity
- detection circuit
- npn triode
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- intensity detection
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Abstract
The invention relates to an extremely-low-lost detection-range-adjustable light intensity detection circuit which is formed by four simulators: a silicon photosensitive triode U1, an NPN triode Q1, two resistors and a one-chip microcomputer MCU with AD sampling. The silicon photosensitive triode U1 is connected in series with the load R2; the silicon photosensitive triode U1 and the load R2 which are connected in series are connected in parallel with the adjustable resistor R1; the adjustable resistor R1 is connected with the 1 pin and the 2 pin of the NPN triode Q1; the load R2 is connected with the 3 pin of the NPN triode Q1; and the 3 pin of the NPN triode Q1 is connected with the one-chip microcomputer MCU through the output end OUT of the one-chip microcomputer MCU. The beneficial effects of the light intensity detection circuit are that the light intensity detection circuit is simple and practical, low in cost, and adjustable in measurement range; and the circuit is especially suitable for areas which are not high in precision requirement, adjustable in measurement ranges and very strict in cost control.
Description
Technical field
The present invention relates to a kind of testing circuit, relate in particular to the adjustable light intensity detection circuit of a kind of very low cost sensing range.
Background technology
Tradition is by photosensitive device (photodiode to the detection method of light intensity, or photosensory assembly) sensing intensity of illumination, make light signal be converted into electric signal, then use discharge circuit to amplify weak electric signal, then by A/D conversion circuit, intensity signal is converted into numerical information.The relative reference table of these light intensity numerical informations, thus calculate light intensity.
Although the method that this light intensity detects implements also not very too complicated, if use sense optical assembly, price can be higher comparatively speaking; If use simple photodiode, the narrow and dark current in photosensitive linear zone can variation with temperature be nonlinearities change, and measuring error can be larger, and the light intensity that the most important thing is to be difficult to realize wide region detects.
Summary of the invention
The object of the invention is to overcome the deficiency that prior art exists, and provide a kind of to measurement range and measuring accuracy is considered to some extent and cost is the extremely low adjustable light intensity detection circuit of sensing range.
The object of the invention is to complete by following technical solution, described light intensity detection circuit is totally four analog devices composition, i.e. silicon phototriode U1 and NPN triode Q1 and two resistance and a single-chip microprocessor MCU with AD sampling; Described this silicon phototriode U1 is together with load R2 series connection, and silicon phototriode U1 and load R2 is together in parallel with adjustable resistance R1 in this series connection; Adjustable resistance R1 is connected with 1 pin, 2 pin of NPN triode Q1, and load R2 is connected with 3 pin of NPN triode Q1, and 3 pin of this NPN triode Q1 are connected with single-chip microprocessor MCU by the output terminal OUT in single-chip microprocessor MCU.Described silicon phototriode U1, as the sensor devices of light intensity detection circuit, is converted into electric signal by light intensity signal, directly inputs to single-chip microprocessor MCU and sample and process after NPN triode Q1 amplifying signal, obtains the light intensity in region; After to be loaded into load R2 upper, be formed for the voltage signal of actual measurement.
As preferably, the detection optical wavelength of described silicon phototriode U1 is from 150～1200nm, to spectral wavelength, from the light of 150～1200nm, can respond to, visible region 390～770nm is also included wherein, also included the ultraviolet range in 10～400nm interval, and the infrared ray subregion of the above wavelength of 760nm.
As preferably, described adjustable resistance R1 will digest the dark current of silicon phototriode U1 self on the one hand, and the electric signal on the other hand induction being obtained is offset to the linear amplification region of NPN triode Q1.
As preferably, described NPN triode Q1 makes the operating voltage of silicon phototriode U1 be held in operating voltage VCC-0.7V.
Beneficial effect of the present invention is: simple and practical, with low cost, measurement range is adjustable; In circuit, do not contain temperature drift compensation device, as realized high-precision applications, will increase warming device, and the temperature characterisitic of silicon phototriode is linear, single-chip microcomputer inside can compensate according to temperature conditions, can make like this circuit precision increase; So it is not high that circuit is particularly suitable for accuracy requirement, but the region that measurement range is adjustable and cost control is strict especially.
Accompanying drawing explanation
Fig. 1 is circuit used in the present invention.
Fig. 2 is the induction sensitivity curve of silicon phototriode to different frequency light.
Fig. 3 is the induction current curve of different temperatures under same light intensity.
Fig. 4 is induction current curve under different light intensity environment.
Fig. 5 is the dark current curve of silicon phototriode under different temperatures.
Embodiment
Below in conjunction with accompanying drawing, the present invention is done to detailed introduction: as shown in Figure 1, the present invention includes a cheap silicon phototriode U1 and a most common NPN triode Q1 and two resistance and a single-chip microprocessor MCU with AD sampling and form, cost is extremely low.This light intensity detection circuit as sensor devices, is converted into electric signal by light intensity signal by silicon phototriode U1, and no matter light intensity signal is the 50HZ signal of direct current signal or picture daylight lamp, and silicon phototriode U1 can both respond to accurately.Adjustable resistance R1 in circuit, can digest on the one hand the dark current of silicon phototriode U1 self, can play on the other hand the electric signal that induction is obtained and be offset to the effect of the linear amplification region of NPN triode Q1.NPN triode Q1 is mainly the amplification playing electric signal, the current signal after amplifying is loaded into load R2 upper, can be for the voltage signal of actual measurement thereby form.The size of regulating load R2 resistance can arrange the precision that detects intensity signal, and generally we do not go to arrange this value, in calculating below, load R2 is arranged to a customization, and during this definite value, measuring accuracy is lower limit.
Described light intensity detection circuit, by the different inductions of silicon phototriode U1 senses light intensity, cause the variation of internal resistance and conveyance capacity to carry out conversion zone light intensity, PN junction pincers in the BE end of NPN triode Q1 are defended voltage makes the operating voltage of silicon phototriode U1 remain operating voltage VCC-0.7V, the electric signal that NPN triode Q1 obtains induction directly inputs to single-chip microprocessor MCU after amplifying and samples and process, thereby obtains the light intensity in region.
Fig. 1 is circuit of the present invention, and in circuit, VCC is operating voltage, and U1 is silicon phototriode, and Q1 is NPN type triode (amplification coefficient is He), and R1 is adjustable resistance, and R2 is load.Adjustable resistance R1 can remove the part electric current that phototriode stream U1 crosses, and adjustable resistance R1 both end voltage is 0.7V, and offset current is Ix=0.7V/R1, and effect is with removing dark current and regulating between detection zone.
Fig. 2 can learn that this silicon phototriode U1(product is the PT19-21C-L41-TR8 of EVERLIGHT company) to spectral wavelength, from the light of 150～1200nm, can respond to, visible region 390～770nm is also included wherein, also included the ultraviolet range in 10～400nm interval, and the infrared ray subregion of the above wavelength of 760nm.
It is a straight line to the induction sensitivity curve of temperature that Fig. 3 can obtain silicon phototriode U1, slope K, and take 25 degrees Celsius as with reference to sensitivity α=1, α=1+ (T-25 ℃) * K during other temperature T.K can obtain from figure.
Fig. 4 can obtain silicon phototriode U1, and light is turned to electric corresponding curve is a straight line, and slope is J, take 1mW light intensity as with reference to switching current as 0.6mA, during other light intensity Ee, switching current is Ie=0.6+(Ee-1mW) * J.J can obtain from figure.
The corresponding curve that Fig. 5 can obtain silicon phototriode U1 dark current under different temperatures is a straight line, and slope is L, take 25 degrees Celsius as with reference to dark current as 10
-6mA, so the dark current Ia=10 under other temperature T
-6+ (T-25 ℃) * L.L can obtain from figure.
According to above parameter and data, we can calculate the magnitude of voltage Ve changing out under certain light intensity Ee by Fig. 1, and can dark current and temperature be floated and be compensated according to temperature T.Be calculated as follows:
I1=switching current * induction sensitivity+dark current-offset current
=Ie*α+Ia-Ix
=【0.6+(Ee-1mW)*J】*【1+(T-25℃)*K】+10-6+(T-25℃)*L-0.7/R1
R1 unit is K Ω, current unit mA.
Through triode, amplify after-current
I2=I1*He
={【0.6+(Ee-1mW)*J】*【1+(T-25℃)*K】+10-6+(T-25℃)*L-0.7/R1}*He
Load terminal voltage
Ve=VCC-I2*R2
=VCC-{【0.6+(Ee-1mW)*J】*【1+(T-25℃)*K】+10-6+(T-25℃)*L-0.7/R1}*He
In above formula, only having light intensity Ee is unknown number, therefore single-chip microprocessor MCU can calculate region light intensity Ee according to the magnitude of voltage Ve measuring.
Be understandable that, for a person skilled in the art, technical scheme of the present invention and inventive concept be equal to replacement or change the protection domain that all should belong to the appended claim of the present invention.
Claims (4)
1. the light intensity detection circuit that very low cost sensing range is adjustable, it is characterized in that: described light intensity detection circuit is totally four analog devices composition, i.e. silicon phototriode U1 and NPN triode Q1 and two resistance and a single-chip microprocessor MCU with AD sampling; Described this silicon phototriode U1 is together with load R2 series connection, and silicon phototriode U1 and load R2 is together in parallel with adjustable resistance R1 in this series connection; Adjustable resistance R1 is connected with 1 pin, 2 pin of NPN triode Q1, and load R2 is connected with 3 pin of NPN triode Q1, and 3 pin of this NPN triode Q1 are connected with single-chip microprocessor MCU by the output terminal OUT in single-chip microprocessor MCU; Described silicon phototriode U1, as the sensor devices of light intensity detection circuit, is converted into electric signal by light intensity signal, directly inputs to single-chip microprocessor MCU and sample and process after NPN triode Q1 amplifying signal, obtains the light intensity in region; After to be loaded into load R2 upper, be formed for the voltage signal of actual measurement.
2. the adjustable light intensity detection circuit of very low cost sensing range according to claim 1, it is characterized in that: the detection optical wavelength of described silicon phototriode U1 is from 150～1200nm, to spectral wavelength, from the light of 150～1200nm, can respond to, visible region 390～770nm is also included wherein, also included the ultraviolet range in 10～400nm interval, and the infrared ray subregion of the above wavelength of 760nm.
3. the adjustable light intensity detection circuit of very low cost sensing range according to claim 1, it is characterized in that: described adjustable resistance R1 will digest the dark current of silicon phototriode U1 self on the one hand, and the electric signal on the other hand induction being obtained is offset to the linear amplification region of NPN triode Q1.
4. the adjustable light intensity detection circuit of very low cost sensing range according to claim 1, is characterized in that: described NPN triode Q1 makes the operating voltage of silicon phototriode U1 be held in operating voltage VCC-0.7V.
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| CN201310667387.1A CN103743481B (en) | 2014-02-20 | 2014-02-20 | A kind of adjustable light intensity detection circuit of very low cost detection range |
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| CN103743481B CN103743481B (en) | 2017-03-15 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106066397A (en) * | 2016-07-05 | 2016-11-02 | 深圳普门科技有限公司 | A kind of compensation system, method and immunity analysis instrument being applicable to current-output type photomultiplier tube |
| CN113884154A (en) * | 2020-07-03 | 2022-01-04 | 成都秦川物联网科技股份有限公司 | MCU-based double-path photoelectric sampling method for Internet of things intelligent gas meter |
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| US5043587A (en) * | 1989-01-17 | 1991-08-27 | Fuji Electric Co., Ltd. | Photocoupler circuit having DC power source in series with detection and switching means |
| JP2009097870A (en) * | 2007-10-12 | 2009-05-07 | Sony Corp | Optical-electrical signal conversion circuit and light detection device |
| CN102062810A (en) * | 2010-12-14 | 2011-05-18 | 江苏大学 | Detection circuit and method for zero crossing point of alternating current power supply |
| CN103376157A (en) * | 2012-04-20 | 2013-10-30 | 海洋王（东莞）照明科技有限公司 | Lamp luminance detecting device |
| CN203745081U (en) * | 2014-02-20 | 2014-07-30 | 三维通信股份有限公司 | Extremely-low-lost adjustable-detection-range light intensity detection circuit |
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2014
- 2014-02-20 CN CN201310667387.1A patent/CN103743481B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| US3870418A (en) * | 1971-06-25 | 1975-03-11 | Canon Kk | Exposure meter |
| US3813539A (en) * | 1973-01-31 | 1974-05-28 | Rohm & Haas | Electro-optical coupler unit |
| US5043587A (en) * | 1989-01-17 | 1991-08-27 | Fuji Electric Co., Ltd. | Photocoupler circuit having DC power source in series with detection and switching means |
| JP2009097870A (en) * | 2007-10-12 | 2009-05-07 | Sony Corp | Optical-electrical signal conversion circuit and light detection device |
| CN102062810A (en) * | 2010-12-14 | 2011-05-18 | 江苏大学 | Detection circuit and method for zero crossing point of alternating current power supply |
| CN103376157A (en) * | 2012-04-20 | 2013-10-30 | 海洋王（东莞）照明科技有限公司 | Lamp luminance detecting device |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106066397A (en) * | 2016-07-05 | 2016-11-02 | 深圳普门科技有限公司 | A kind of compensation system, method and immunity analysis instrument being applicable to current-output type photomultiplier tube |
| CN106066397B (en) * | 2016-07-05 | 2019-10-18 | 深圳普门科技股份有限公司 | A kind of compensation system, method and immunity analysis instrument suitable for current-output type photomultiplier tube |
| CN113884154A (en) * | 2020-07-03 | 2022-01-04 | 成都秦川物联网科技股份有限公司 | MCU-based double-path photoelectric sampling method for Internet of things intelligent gas meter |
| CN113884154B (en) * | 2020-07-03 | 2023-10-31 | 成都秦川物联网科技股份有限公司 | MCU-based double-path photoelectric sampling method for intelligent gas meter of Internet of things |
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| CN103743481B (en) | 2017-03-15 |
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