CN104075806B - A kind of photoelectric integral color measurement instrument based on multiple LED light source and measuring method thereof - Google Patents

Abstract

The invention discloses a kind of photoelectric integral color measurement instrument based on multiple LED light source and measuring method thereof, wherein, the described photoelectric integral color measurement instrument based on multiple LED light source comprises: integrating sphere, be angularly arranged on the central horizontal face of integrating sphere integrating sphere inwall LED light source and be positioned at integrating sphere inwall and be the detector of 8 degree of angles with material surface normal direction.The present invention adopts LED composite light source as measurement light source, by the spectral distribution of adjustment LED composite light source, changes the spectral response of instrument.Owing to not using optical filter in the design of this photoelectric integral color measurement instrument, the color data under multiple standards light source can be measured to sample on a photoelectric integral color measurement instrument, and reduce the apparatus measures error of indication, ensure that good test repeatability, there is good popularizing application prospect.

Description

A kind of photoelectric integral color measurement instrument based on multiple LED light source and measuring method thereof

Technical field

The present invention relates to colour photometer technical field, particularly a kind of photoelectric integral color measurement instrument based on multiple LED light source and measuring method thereof.

Background technology

Colour photometer, is widely used in the color management field of the industries such as plastic cement, printing, paint, printing ink, textile garment, can measures the color data of sample.

In prior art means, the spectral response of photoelectric integral color measurement instrument depends on the relative spectral sensitivity of measurement light source spectrum, detector and the spectral transmittance of optical filter.After light source for instrument and detector have selected, the spectral response of instrument is made to meet Luther condition by the spectral transmittance of match filter.Because the angle requirement of optical filter to light realized by plated film is higher, and in color measurement instrument, optical filter needs the light measuring different directions incidence, so the method that the optical filter many employings multi-disc coloured glass in color measurement instrument mates realizes.Photoelectric integral color measurement instrument, adopts halogen tungsten lamp or xenon lamp as measurement light source more, adopts silicon detector as sensor.When adopting halogen tungsten lamp as light source in actual applications, lower in the relative spectral power distribution value of visible ray shortwave part halogen tungsten lamp, and silicon detector is also relatively low in the spectral response of shortwave part, so cause instrument when measuring the Z value in color tristimulus values, measurement result signal to noise ratio (S/N ratio) is low, affects measuring repeatability; When adopting xenon lamp as light source, because xenon lamp spectral curve is unsmooth, the spectral transmittance of required optical filter is caused also to be rough, so it is very large to carry out mating with multi-disc coloured glass the difficulty obtaining required optical filter.In addition on the one hand, because the kind of coloured glass is limited, processed complex, poor stability, when carrying out coupling correction to coloured glass, be difficult to find the good scheme of matching precision, thus cause apparatus measures to there is the larger error of indication.Carry out mating with multi-disc coloured glass and obtain required optical filter and usually need the optical filter of more than three to mate, optical filter transmitance can be caused on the low side, affect the repeatability of apparatus measures.

In view of this, prior art need to improve.

Summary of the invention

In view of above-mentioned the deficiencies in the prior art part, the object of the present invention is to provide a kind of photoelectric integral color measurement instrument based on multiple LED light source and measuring method thereof, adopt halogen tungsten lamp or xenon lamp as the large problem of the optical filter difficulty of matching existing for measurement light source to solve existing photoelectric integral color measurement instrument.

In order to achieve the above object, this invention takes following technical scheme:

A kind of photoelectric integral color measurement instrument based on multiple LED light source, wherein, comprising: integrating sphere, be angularly arranged on the central horizontal face of integrating sphere integrating sphere inwall LED light source and be positioned at integrating sphere inwall and be the detector of 8 degree of angles with material surface normal direction;

Wherein, the relative spectral power distribution of multiple LED light source is had should to meet the relation be shown below.

$L_x\left(\mathrm{\λ}\right)\mathrm{\γ}\left(\mathrm{\λ}\right)=S_D\left(\mathrm{\λ}\right){\stackrel{\‾}{x}}_{10}\left(\mathrm{\λ}\right)$

$L_y\left(\mathrm{\λ}\right)\mathrm{\γ}\left(\mathrm{\λ}\right)=S_D\left(\mathrm{\λ}\right){\stackrel{\‾}{y}}_{10}\left(\mathrm{\λ}\right)$

$L_z\left(\mathrm{\λ}\right)\mathrm{\γ}\left(\mathrm{\λ}\right)=S_D\left(\mathrm{\λ}\right){\stackrel{\‾}{z}}_{10}\left(\mathrm{\λ}\right)$

Wherein, L _x(λ), L _y(λ), L _z(λ) be the relative spectral power distribution of the LED composite light source when measuring color tristimulus values X, Y, Z respectively; The relative spectral response that γ (λ) is sensor; S _d(λ) for being standard illuminants D ₆₅relative spectral power distributions; for CIE1964 standard observer spectral response; λ is the wavelength in visible-range, from 380-780nm.

First the light that LED light source sends incide on integrating sphere inwall, fully reflects at integrating sphere inwall, carries out diffuse illumination to sample, final detector receiving optical signals, and send it in corresponding disposal system and carry out data processing and obtain corresponding result.

The described photoelectric integral color measurement instrument based on multiple LED light source, wherein, the number of described LED light source is 31, by adjusting the drive current of 31 LED, obtains required spectral distribution.

The described photoelectric integral color measurement instrument based on multiple LED light source, wherein, the peak wavelength of described 31 LED light sources is respectively 400nm, 412nm, 424nm, 436nm, 448nm, 460nm, 472nm, 484nm, 496nm, 508nm, 520nm, 532nm, 544nm, 556nm, 568nm, 580nm, 592nm, 604nm, 616nm, 628nm, 640nm, 654nm, 668nm, 678nm, 692nm, 711nm, 727nm, 740nm, 752nm, 765nm, 780nm.

A measuring method for the above-mentioned photoelectric integral color measurement instrument based on multiple LED light source, wherein, said method comprising the steps of:

First the light that S1, LED light source send incide on integrating sphere inwall, carries out diffuse illumination to sample;

S2, detector receiving optical signals, and send it in corresponding disposal system and carry out data processing and obtain corresponding result.

The measuring method of the described photoelectric integral color measurement instrument based on multiple LED light source, wherein, the number of described LED light source is 31, by adjusting the drive current of 31 LED, obtains required spectral distribution.

The measuring method of the described photoelectric integral color measurement instrument based on multiple LED light source, wherein, comprising:

The mathematical model of LED composite light source Spectral beam combining is

$S\left(\mathrm{\λ}\right)=\mathrm{\Σ}{K}_i\×S_i\left(\mathrm{\λ}\right)$

Wherein, K _i(λ) be LED drive current coefficient, S _i(λ) be the spectral distribution function of LED.

Compared to prior art, the photoelectric integral color measurement instrument based on multiple LED light source provided by the invention and measuring method thereof, adopt LED composite light source as measurement light source, by the spectral distribution of adjustment LED composite light source, changes the spectral response of instrument.Owing to not using optical filter in Instrument Design, be applied on photoelectric integral color measurement instrument, reduce the apparatus measures error of indication, there is good popularizing application prospect.

Accompanying drawing explanation

Fig. 1 a is the schematic diagram of the detector spectrum response curve of prior art.

Fig. 1 b is the schematic diagram of Halogen lamp spectrum of the prior art.

Fig. 1 c is the schematic diagram of the transmitance of the halogen tungsten lamp optical filter of prior art.

Fig. 1 d is the schematic diagram of the xenon lamp spectrum of prior art.

Fig. 2 is the schematic diagram based on composite light source spectrum in the photoelectric integral color measurement instrument of multiple LED light source provided by the invention.

Fig. 3 a is the schematic diagram based on the Lx curve of spectrum in the photoelectric integral color measurement instrument of multiple LED light source provided by the invention.

Fig. 3 b is the schematic diagram based on the Ly curve of spectrum in the photoelectric integral color measurement instrument of multiple LED light source provided by the invention.

Fig. 3 c is the schematic diagram based on the Lz curve of spectrum in the photoelectric integral color measurement instrument of multiple LED light source provided by the invention.

Fig. 4 is the schematic diagram of the embodiment of the photoelectric integral color measurement instrument based on multiple LED light source provided by the invention.

Fig. 5 is the schematic diagram of the arrangement of LED composite light source in the embodiment of the photoelectric integral color measurement instrument based on multiple LED light source provided by the invention.

Fig. 6 is the process flow diagram of the measuring method of the photoelectric integral color measurement instrument based on multiple LED light source provided by the invention.

Fig. 7 a is the contrast schematic diagram of the X value test result of the photoelectric integral color measurement instrument based on multiple LED light source provided by the invention and reference instrument.

Fig. 7 b is the contrast schematic diagram of the Y value test result of the photoelectric integral color measurement instrument based on multiple LED light source provided by the invention and reference instrument.

Fig. 7 c is the contrast schematic diagram of the Z value test result of the photoelectric integral color measurement instrument based on multiple LED light source provided by the invention and reference instrument.

Fig. 8 a is the schematic diagram that in the measuring method of the photoelectric integral color measurement instrument based on multiple LED light source provided by the invention, blue led light source adopts single Gauss curve fitting.

Fig. 8 b is the schematic diagram that in the measuring method of the photoelectric integral color measurement instrument based on multiple LED light source provided by the invention, blue led light source adopts the right Lorentz lorentz's matching of left Gauss.

Fig. 8 c is the schematic diagram that in the measuring method of the photoelectric integral color measurement instrument based on multiple LED light source provided by the invention, blue led light source adopts the right Gauss curve fitting of left Lorentz lorentz.

Embodiment

The invention provides a kind of photoelectric integral color measurement instrument based on multiple LED light source and measuring method thereof, for making object of the present invention, technical scheme and effect clearly, clearly, developing simultaneously referring to accompanying drawing, the present invention is described in more detail for embodiment.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.

First, the principle of photoelectric integration formula color measuring is introduced.Photoelectric integration formula color measuring carries out an integral measurement to the spectral energy of tested color in whole measurement wavelength coverage.By the colour examining principle that International Commission on Illumination (CIE, International Commission on Illumination) is recommended, at D ₆₅when measuring color standard tristimulus values under standard sources, the spectrum sensitivity (the comprehensive response of light source, optical system, detector three) of instrument should meet formula (1)

$\left.\begin{array}{c}{k}_1{\∫}_{380}^{780}S\left(\mathrm{\λ}\right){\mathrm{\τ}}_x\left(\mathrm{\λ}\right)\mathrm{\γ}\left(\mathrm{\λ}\right)\mathrm{d\λ}={\∫}_{380}^{780}{S}_D\left(\mathrm{\λ}\right){\stackrel{\‾}{X}}_{10}\left(\mathrm{\λ}\right)\mathrm{d\λ}\\ k_2{\∫}_{380}^{780}S\left(\mathrm{\λ}\right){\mathrm{\τ}}_y\left(\mathrm{\λ}\right)\mathrm{\γ}\left(\mathrm{\λ}\right)\mathrm{d\λ}={\∫}_{380}^{780}{S}_D\left(\mathrm{\λ}\right){\stackrel{\‾}{z}}_{10}\left(\mathrm{\λ}\right)\mathrm{d\λ}\\ k_3{\∫}_{380}^{780}S\left(\mathrm{\λ}\right){\mathrm{\τ}}_z\left(\mathrm{\λ}\right)\mathrm{\γ}\left(\mathrm{\λ}\right)\mathrm{d\λ}={\∫}_{380}^{780}{S}_D\left(\mathrm{\λ}\right){\stackrel{\‾}{z}}_{10}\left(\mathrm{\λ}\right)\mathrm{d\λ}\end{array}\right\}---\left(1\right)$

Wherein, k ₁, k ₂, k ₃for constant; The relative spectral power distributions that S (λ) is light source for instrument; T _x(λ),

T _y(λ), T _z(λ) be the spectral transmittance of optical filter in instrument; S _d(λ) for being standard illuminants D ₆₅relative spectral power distributions; for CIE1964 standard observer spectral response; The relative spectral response that γ (λ) is sensor.

Usually the colour examining condition meeting formula (1) is called Luther condition.From formula 1, the spectral response of instrument is determined by measurement light source, detector, optical filter.Usually, after the measurement light source that have selected instrument and detector, by the spectral transmittance of match filter, instrument spectral is responded and meet Luther condition.From the relative spectral transmittance τ of formula 1, X, Y, Z tri-kinds of optical filters _x(λ), τ _y(λ), τ _z(λ) condition shown in formula 2 should be met.

$\left.\begin{array}{c}{\mathrm{\τ}}_x\left(\mathrm{\λ}\right)=\frac{S_D\left(\mathrm{\λ}\right){\stackrel{\‾}{x}}_{10}\left(\mathrm{\λ}\right)}{S\left(\mathrm{\λ}\right)\mathrm{\γ}\left(\mathrm{\λ}\right)}\\ {\mathrm{\τ}}_y\left(\mathrm{\λ}\right)=\frac{S_D\left(\mathrm{\λ}\right){\stackrel{\‾}{y}}_{10}\left(\mathrm{\λ}\right)}{S\left(\mathrm{\λ}\right)\mathrm{\γ}\left(\mathrm{\λ}\right)}\\ {\mathrm{\τ}}_z\left(\mathrm{\λ}\right)=\frac{S_D\left(\mathrm{\λ}\right){\stackrel{\‾}{z}}_{10}\left(\mathrm{\λ}\right)}{S\left(\mathrm{\λ}\right)\mathrm{\γ}\left(\mathrm{\λ}\right)}\end{array}\right\}---\left(2\right)$

When adopting halogen tungsten lamp as light source in actual applications, lower in the relative spectral power distribution value of visible ray shortwave part halogen tungsten lamp, as shown in Figure 1a.And silicon detector is also as shown in Figure 1 b relatively low in the spectral response of shortwave part, so cause instrument when measuring the Z value in color tristimulus values, measurement result signal to noise ratio (S/N ratio) is low, affects measuring repeatability;

When adopting xenon lamp as light source, because xenon lamp spectral curve is unsmooth, as illustrated in figure 1 c.The spectral transmittance of required optical filter is caused also to be rough, as shown in Figure 1 d so to carry out mating with multi-disc coloured glass the difficulty obtaining required optical filter very large.In addition on the one hand, because the kind of coloured glass is limited, processed complex, poor stability, when carrying out coupling correction to coloured glass, be difficult to find the good scheme of matching precision, thus cause apparatus measures to there is the larger error of indication.Carry out mating with multi-disc coloured glass and obtain required optical filter and usually need the optical filter of more than three to mate, optical filter transmitance can be caused on the low side, affect the repeatability of apparatus measures.

Therefore, the invention provides a kind of photoelectric integral color measurement instrument based on multiple LED light source and measuring method thereof.Wherein, as shown in Figure 4, the described photoelectric integral color measurement instrument based on multiple LED light source comprises: integrating sphere, on the central horizontal face of integrating sphere, be angularly arranged in 31 LEDs light sources of integrating sphere inwall, as shown in Figure 5 and be positioned at integrating sphere inwall and be the detector of 8 degree of angles with material surface normal direction;

Wherein, the spectral response of LED light source and sensor is had should to meet the relation be shown below.

$L_x\left(\mathrm{\λ}\right)\mathrm{\γ}\left(\mathrm{\λ}\right)=S_D\left(\mathrm{\λ}\right){\stackrel{\‾}{x}}_{10}\left(\mathrm{\λ}\right)$

$L_y\left(\mathrm{\λ}\right)\mathrm{\γ}\left(\mathrm{\λ}\right)=S_D\left(\mathrm{\λ}\right){\stackrel{\‾}{y}}_{10}\left(\mathrm{\λ}\right)$

$L_z\left(\mathrm{\λ}\right)\mathrm{\γ}\left(\mathrm{\λ}\right)=S_D\left(\mathrm{\λ}\right){\stackrel{\‾}{z}}_{10}\left(\mathrm{\λ}\right)$

Wherein, L _x(λ), L _y(λ), L _z(λ) be the relative spectral power distribution of the LED composite light source when measuring tristimulus values X, Y, Z respectively; The relative spectral response that γ (λ) is sensor; S _d(λ) for being standard illuminants D ₆₅relative spectral power distributions; for CIE1964 standard observer spectral response;

First the light that LED light source sends incide on integrating sphere inwall, carries out diffuse illumination to sample, final detector receiving optical signals, and send it in corresponding disposal system and carry out data processing and obtain corresponding result.

In short, adopt LED composite light source as measurement light source, by the spectral distribution of adjustment LED composite light source, change the spectral response of instrument.Owing to not using optical filter in Instrument Design, so the response of instrument overall spectrum has the spectral response of LED light source and sensor to determine.Adopt relative spectral response sensor as shown in Figure 1a, calculate the composite light source spectrum L measured under d 65 illuminant needed for X, Y, Z _x, L _y, L _z, as shown in Figure 2.

The object of design LED composite light source is in order to the working current by each LED in adjustment LED composite light source, and the spectrum of LED composite light source is met under specific light source the requirement that standard tristimulus values is measured.The spectrum of LED composite light source should have sufficient spectral distribution in 380 to 780nm scope.In order to the working current by each LED of adjustment, match kind of the spectral distribution of three shown in Fig. 2, need to select peak wavelength to be in LED between 380 to 780nm.Selected LED quantity is more, and the interval of peak wavelength is less, and the precision of coupling is higher.But be limited by the kind restriction of cost, apparatus structure and LED, the quantity of LED can not be too many.In the present embodiment, the standard that we are about 10-15nm according to peak wavelength interval goes to select LED in existing LED kind, 31 LED are adopted to form composite light source, its arrangement mode as shown in Figure 5, by adjusting the drive current of different LED, for measuring the light source providing 3 kinds of different spectral distribution as shown in Figure 2, under different spectral distribution, measure the tristimulus values of color respectively.Selected LED is 31, and peak wavelength is spaced apart 10-15nm, and peak wavelength is respectively 400nm, 412nm, 424nm, 436nm, 448nm, 460nm, 472nm, 484nm, 496nm, 508nm, 520nm, 532nm, 544nm, 556nm, 568nm, 580nm, 592nm, 604nm, 616nm, 628nm, 640nm, 654nm, 668nm, 678nm, 692nm, 711nm, 727nm, 740nm, 752nm, 765nm, 780nm.Due to peak wavelength be the LED half-wave of 400nm wide be 20nm, so can ensure the spectral distribution at 380nm place, so do not add corresponding LED at about 380nm and about 390nm, experimental result also proves on the impact of final matching result not quite.Above-mentioned all LED application algorithms chosen are calculated its drive current.

According to spectrum superposition principle, the mathematical model of LED composite light source Spectral beam combining is

S _c(λ)=∑K _i×S _i(λ)

Wherein, S _c(λ) be the spectral distribution of composite LED, K _ifor LED drive current coefficient.

S _i(λ) for label be the spectral distribution function of LED of i.The luminescent spectrum of typical case LED is similar to Gaussian distribution, and therefore, in research, the normal mathematical model of gauss of distribution function that adopts carrys out the single LED light spectrum of matching.The gauss of distribution function that each LED is corresponding is

$S\left(\mathrm{\λ}\right)=\frac{1}{\mathrm{\σ}\sqrt{2\mathrm{\π}}}\exp {\left[\frac{-1}{2}\left(\frac{{\mathrm{\λ}-\mathrm{\λ}}_{\mathrm{peak}}}{\mathrm{\σ}}\right)\right]}^2---\left(1\right)$

Wherein, λ _peakcorrespond to the peak wavelength of LED, corresponding its halfwidth (Full width at half maximum, FWHM) of σ.

But actual LED light Spectral structure is incomplete rotational symmetry also, if directly adopt Gauss curve fitting, and there is certain deviation between actual value.For this situation, the present invention adopts asymmetric Gauss model to carry out matching: adopt Lorentz lorentz's distribution on the right of the Gaussian distribution of the left side, as the formula (2); Or left side Lorentz distribution the right Gaussian distribution, as the formula (3).

$S\left(\mathrm{\&lambda;}\right)=\left\{\begin{array}{c}\frac{1}{\mathrm{\&sigma;}\sqrt{2\mathrm{\&pi;}}}\exp {\left[\frac{-1}{2}\left(\frac{{\mathrm{\&lambda;}-\mathrm{\&lambda;}}_{\mathrm{peak}}}{\mathrm{\&sigma;}}\right)\right]}^2,\mathrm{\&lambda;}<{\mathrm{\&lambda;}}_{\mathrm{peak}}\\ \frac{1}{\mathrm{\&sigma;}\sqrt{2\mathrm{\&pi;}}}\&CenterDot;\frac{{\mathrm{\&sigma;}}^2}{4{\left({\mathrm{\&lambda;}-\mathrm{\&lambda;}}_{\mathrm{peak}}\right)}^2+{\mathrm{\&sigma;}}^2},\mathrm{\&lambda;}\&GreaterEqual;{\mathrm{\&lambda;}}_{\mathrm{peak}}\end{array}\right.---\left(2\right)$

$S\left(\mathrm{\&lambda;}\right)=\left\{\begin{array}{c}\frac{1}{\mathrm{\&sigma;}\sqrt{2\mathrm{\&pi;}}}\exp {\left[\frac{-1}{2}\left(\frac{{\mathrm{\&lambda;}-\mathrm{\&lambda;}}_{\mathrm{peak}}}{\mathrm{\&sigma;}}\right)\right]}^2,\mathrm{\&lambda;}\&GreaterEqual;{\mathrm{\&lambda;}}_{\mathrm{peak}}\\ \frac{1}{\mathrm{\&sigma;}\sqrt{2\mathrm{\&pi;}}}\&CenterDot;\frac{{\mathrm{\&sigma;}}^2}{4{\left({\mathrm{\&lambda;}-\mathrm{\&lambda;}}_{\mathrm{peak}}\right)}^2+{\mathrm{\&sigma;}}^2},\mathrm{\&lambda;}<{\mathrm{\&lambda;}}_{\mathrm{peak}}\end{array}\right.---\left(3\right)$

Wherein, λ _peakcorrespond to the peak wavelength of LED, corresponding its halfwidth (Full width at half maximum, FWHM) of σ.

Be example to optional red, green, blue three kinds of LED, adopt single Gauss curve fitting, left Gauss right Lorentz lorentz matching, the right Gauss curve fitting of left Lorentz lorentz to carry out spectrum simulation respectively.Last error of fitting is as shown in following table 1, and error of fitting is lower, represents fitting effect better.Table 1LED spectrum simulation

As shown in Table 1, blue light and green glow are applicable to the right Lorentz lorentz's matching of left Gauss, and ruddiness is then applicable to the fit approach by the right Gauss of left Lorentz lorentz.

As shown in Fig. 8 a, 8b and 8c, it is respectively the best-fit result that blue-ray LED adopts distinct methods to draw: Fig. 8 a is single Gauss curve fitting; Fig. 8 b is the right Lorentz lorentz's matching of left Gauss; Fig. 8 c is the right Gauss curve fitting of left Lorentz lorentz: actual spectrum is indicated by the solid line, and fit-spectra is represented by dashed line.As seen from the figure: the blue-ray LED curve under the right Lorentz lorentz's matching of left Gauss distributes closer to its real spectrum power.

Above result shows, does not have a kind of fixing fit approach to be applicable to all LED light spectrums, in order to accurately carry out matching to LED light spectrum, needing to analyze the multiple fitting algorithm of each LED light spectrum application, obtaining best matching scheme.

400nm is respectively, 412nm, 424nm, 436nm, 448nm, 460nm to peak wavelength used in the present embodiment, 472nm, 484nm, 496nm, 508nm, 520nm, 532nm, 544nm, 556nm, 568nm, 580nm, 592nm, 604nm, 616nm, 628nm, 640nm, 654nm, 668nm, 678nm, 692nm, 711nm, 727nm, 740nm, 752nm, 765nm, 780nm be totally 31 kinds of LED, measures the spectral distribution of often kind of LED respectively.To measuring, each LED light Spectral structure of obtaining applies single Gauss curve fitting respectively, left Gauss right Lorentz lorentz matching, the right Gauss curve fitting of left Lorentz lorentz three kinds of schemes carry out spectrum simulation, choose a minimum scheme of error of fitting as matching determination scheme, namely the spectral distribution of each LED is [S ₁(λ), S ₂(λ), S ₃(λ) ..., S ₃₁(λ)].

When formula (5) obtains minimum value, target optical spectrum S _t(λ) with fit-spectra S _c(λ) the most close, calculate the optimum solution of now Ki.The metering method of similar relative error is adopted to evaluate result of calculation S _c(λ) with target optical spectrum S _t(λ) consistance, asks matching precision as the formula (6).

∑|S _T(λ)-S _c(λ)|=min （5）

$p=\frac{\mathrm{\&Sigma;}|S_T\left(\mathrm{\&lambda;}\right)-S_c\left(\mathrm{\&lambda;}\right)|}{\mathrm{\&Sigma;}{S}_T\left(\mathrm{\&lambda;}\right)}---\left(6\right)$

Wherein, p is matching precision.P is less, and spectrum consistance is then higher.

According to theoretical analysis, we know in any af at wavelength lambda of target optical spectrum, meet following relational expression

S _c(λ)=S ₁(λ)×K ₁+S ₂(λ)×K ₂+S ₂(λ)×K ₂+…+S _n(λ)×K _n

Wherein, n is the LED number chosen.S ₁(λ), S ₂(λ), S ₃(λ) ... S _n(λ) optical power distribution of the different LED of each peak wavelength under 20mA drive current in af at wavelength lambda is represented.K ₁, K ₂, K ₃... K _nrepresent the non-negative drive current coefficient that above-mentioned each LED is corresponding.Spectrum of use following formula then for LED composite light source calculates

S _T=S _C=S×K

Wherein, S _tfor target light source spectrum

S _T=[S _T(400)S _T(410)S _T(420)…S _T(780)] ^T

K=[K ₁K ₂K ₃…K _n] ^T

In the design of this example, target optical spectrum is the relative spectral power distribution of the LED composite light source when measuring tristimulus values X, Y, Z is respectively L _x(λ), L _y(λ), L _z(λ).Adopt multiple linear regression can obtain the optimum solution K of matrix of coefficients K to following formula _x, K _y, K _z, be respectively the corresponding drive current coefficient of each LED of structure three kinds of composite light source spectrum.When specifically solving, the instrument of application matlab numerical analysis.

L _x(λ)=[L _x(400)L _x(410)L _x(420)…L _x(780)] ^T=S×K _X

L _y(λ)=[L _y(400)L _y(410)L _y(420)…L _y(780)] ^T=S×K _Y

L _z(λ)=[L _z(400)L _z(410)L _z(420)…L _z(780)] ^T=S×K _Z

In short, the computing method of the drive current of 31 kinds of LED of the embodiment of the present invention are as follows:

First, 31 kinds of LED are all driven with 20mA electric current, measures its spectral distribution;

Then, to the spectral distribution of often kind of LED with applying single Gauss curve fitting respectively, left Gauss right Lorentz lorentz matching, the right Gauss curve fitting of left Lorentz lorentz three kinds of schemes carry out spectrum simulation, choose a minimum scheme of error of fitting as matching determination scheme, obtain [S ₁(λ), S ₂(λ), S ₃(λ) ..., S ₃₁(λ)];

Again following formula is solved:

L _x(λ)=[L _x(400)L _x(410)L _x(420)…L _x(780)]T=S×K _X

L _y(λ)=[L _y(400)L _y(410)L _y(420)…L _y(780)] ^T=S×K _Y

L _z(λ)=[L _z(400)L _z(410)L _z(420)…L _z(780)] ^T=S×K _Z

Obtain current coefficient K _x, K _y, K _zoptimum value;

I.e. multiple LED light source L _xin, the drive current I of often kind of LED _i=K _x[i] * 20mA

Multiple LED light source L _yin, the drive current I of often kind of LED _i=K _y[i] * 20mA

Multiple LED light source L _zin, the drive current I of often kind of LED _i=K _z[i] * 20mA.

Electric current corresponding to application drives different LED, and when reality implements the program, to the actual experiment result of three kinds of Different Light as shown in Figure 3 a, 3b and 3c as shown in, the matching precision obtained through actual measurement is as shown in the table.

The present invention is the corresponding measuring method providing a kind of described photoelectric integral color measurement instrument based on multiple LED light source also, as shown in Figure 6, said method comprising the steps of:

First the light that S1, LED light source send incide on integrating sphere inwall, carries out diffuse illumination to sample;

S2, detector receiving optical signals, and send it in corresponding disposal system and carry out data processing and obtain corresponding result.

Below by an experiment, such scheme is verified.The above-mentioned photoelectric integral color measurement instrument based on multiple LED light source and reference instrument is adopted to test sample.Reference instrument is the spectrophotometric color measurement instrument CM-700D that Konica company produces.CM-700D is D/8 test structure, adopts xenon lamp as testing light source, can measure the reflection spectrum curve of sample, can provide the tristimulus values of sample under various standard sources.Sample is 224 PATONE-C colour atlas, compares the data dependence of two kinds of instrument test gained tristimulus values.Test result is as shown in Fig. 7 a, 7b and 7c, and as can be known from the results, two kinds of instruments have all embodied good linear dependence to the test data of color tristimulus values X, Y, Z.Because in LED composite light source, the matching precision of Y is high, so the linear dependence of data in test result is better than X and Z.After the test data according to CM-700D is demarcated the measurement structure shown in figure, test BCRA Standard colour board, result is as shown in the table.According to the regulation in JJG595-2002 vertification regulation, reach the testing level of one-level colour photometer.

In sum, photoelectric integral color measurement instrument based on multiple LED light source provided by the invention and measuring method thereof, wherein, the described photoelectric integral color measurement instrument based on multiple LED light source comprises: integrating sphere, be angularly arranged on the central horizontal face of integrating sphere integrating sphere inwall LED light source and be positioned at integrating sphere inwall and be the detector of 8 degree of angles with material surface normal direction.The present invention adopts LED composite light source as measurement light source, by the spectral distribution of adjustment LED composite light source, changes the spectral response of instrument.Owing to not using optical filter in Instrument Design, be applied on photoelectric integral color measurement instrument, reduce the apparatus measures error of indication, there is good popularizing application prospect.

Be understandable that, for those of ordinary skills, can be equal to according to technical scheme of the present invention and inventive concept thereof and replace or change, and all these change or replace the protection domain that all should belong to the claim appended by the present invention.

Claims (7)

1. the photoelectric integral color measurement instrument based on multiple LED light source, it is characterized in that, comprising: integrating sphere, be angularly arranged on the central horizontal face of integrating sphere integrating sphere inwall LED light source and be positioned at integrating sphere inwall and be the detector of 8 degree of angles with material surface normal direction;

Wherein, the spectral distribution of LED light source and the spectral response of sensor should meet the relation be shown below:

Wherein , , for the relative spectral power distribution of LED composite light source when measuring tristimulus values X, Y, Z respectively; for the relative spectral response of sensor; for the relative spectral power distributions of standard illuminants; , , for CIE 1964 standard observer spectral response;

First the light that LED light source sends incide on integrating sphere inwall, carries out diffuse illumination to sample, final detector receiving optical signals, and send it in corresponding disposal system and carry out data processing and obtain corresponding result.

2. the photoelectric integral color measurement instrument based on multiple LED light source according to claim 1, is characterized in that, the number of described LED light source is 31, by adjusting the drive current of 31 LED, obtains required spectral distribution.

3. the photoelectric integral color measurement instrument based on multiple LED light source according to claim 1, is characterized in that, the peak wavelength of described 31 LED light sources is respectively 400nm, 412nm, 424nm, 436nm, 448nm, 460nm, 472nm, 484nm, 496nm, 508nm, 520nm, 532nm, 544nm, 556nm, 568nm, 580nm, 592nm, 604nm, 616nm, 628nm, 640nm, 654nm, 668nm, 678nm, 692nm, 711nm, 727nm, 740nm, 752nm, 765nm, 780nm.

4. the measuring method of the photoelectric integral color measurement instrument based on multiple LED light source according to claim 1, is characterized in that, said method comprising the steps of:

First the light that S1, LED light source send incide on integrating sphere inwall, carries out diffuse illumination to sample;

S2, detector receiving optical signals, and send it in corresponding disposal system and carry out data processing and obtain corresponding result;

The mathematical model of LED composite light source Spectral beam combining is

Wherein, Ki is LED drive current coefficient, the spectral distribution function that Si (λ) is LED.

5. the measuring method of the photoelectric integral color measurement instrument based on multiple LED light source according to claim 4, it is characterized in that, adopt asymmetric Gauss model to carry out the single LED light spectrum of matching: to adopt Lorentz lorentz's distribution on the right of the Gaussian distribution of the left side, be shown below:

；

Or left side Lorentz distribution the right Gaussian distribution, as follows:

；

Wherein, λ _peakcorrespond to the peak wavelength of LED, σ its halfwidth corresponding.

6. the measuring method of the photoelectric integral color measurement instrument based on multiple LED light source according to claim 5, is characterized in that, also comprise:

To measuring, each LED light Spectral structure of obtaining applies single Gauss curve fitting respectively, left Gauss right Lorentz lorentz matching, the right Gauss curve fitting of left Lorentz lorentz three kinds of schemes carry out spectrum simulation, chooses a minimum scheme of error of fitting as matching determination scheme,

Namely the spectral distribution of each LED is ;

When when obtaining minimum value, target optical spectrum with fit-spectra the most close, calculate now K _ioptimum solution;

The metering method of similar relative error is adopted to evaluate fit-spectra and target optical spectrum consistance, ask shown in matching precision following formula:

Wherein, p is matching precision, and p is less, and spectrum consistance is then higher.

7. the measuring method of the photoelectric integral color measurement instrument based on multiple LED light source according to claim 4, is characterized in that, when the number of described LED light source is 31, the computing method of the drive current of LED are as follows:

First, 31 kinds of LED are all driven with 20mA electric current, measures its spectral distribution;

Then, single Gauss curve fitting is applied respectively to the spectral distribution of often kind of LED, left Gauss right Lorentz lorentz matching, the right Gauss curve fitting of left Lorentz lorentz three kinds of schemes carry out spectrum simulation, choose a minimum scheme of error of fitting as matching determination scheme, obtain ;

Again following formula is solved:

Obtain current coefficient , , optimum value;

I.e. multiple LED light source in, the drive current I of often kind of LED _i= * 20mA;

Multiple LED light source in, the drive current I of often kind of LED _i= * 20mA;

Multiple LED light source in, the drive current I of often kind of LED _i= * 20mA;

Described ;

Described , with be drive current I _icorresponding current coefficient , , optimum value.