A tilt filter type colorimetric measurement device and measurement method integrating spectral measurement
By using a tilted theoretical three-primary-color filter, a non-parallel imaging unit, and a spectrometer conjugate setting, spectral measurements are integrated into the XYZ three measurements, solving the problems of stray light and state inconsistency, and improving the accuracy and efficiency of colorimetric measurements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WUHAN GATLING OPTICAL INSTR CO LTD
- Filing Date
- 2023-03-07
- Publication Date
- 2026-07-07
AI Technical Summary
In the existing technology, filter colorimeters with integrated spectral measurement have problems such as high stray light, low colorimetric measurement accuracy due to independent spectral measurement process, and long measurement time.
The theoretical three primary color filters are set at an angle and are not parallel to the imaging unit. The spectrometer and the imaging unit are optically symmetrically conjugate. The spectral measurement is integrated into the XYZ three measurements. The theoretical three primary color filters are used to directly reflect light to the spectrometer for measurement. At the same time, the center point chromaticity value is calibrated.
It improves measurement accuracy, reduces stray light effects, shortens measurement time, increases measurement efficiency, and overcomes measurement errors caused by inconsistent states under different filter modes.
Smart Images
Figure CN116337233B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of industrial imaging and inspection technology, and more specifically, to a tilting filter-type colorimetric measurement device and method integrating spectral measurement. Background Technology
[0002] With the advancement of technology, the evaluation of the characteristics of display panels or light emitters is becoming increasingly important for guiding product development. Common light emitters and their display products include different types such as LEDs, microLEDs, miniLEDs, and LDs, and the products composed of them include various consumer electronics products (such as mobile phone screens, television displays, etc.).
[0003] For these display products, evaluating their luminescence characteristics is particularly important for assessing their quality, and colorimetry is a crucial aspect of this. Using an imaging colorimeter, colorimetric or luminance values can be obtained at various points on the display product, allowing for the evaluation of colorimetric uniformity and mura characteristics, among other things. Imaging colorimeters are currently based on two main structures: filter-type colorimeters and filter-type colorimeters that integrate spectral measurement.
[0004] By setting a filter wheel in front of the light sensor, different filters can be added to the wheel, generally filters that conform to or are close to the CIE 1931 response curve. The typical operating mode is as follows: the light sensor acquires one image under the X filter wheel, another image under the Y filter wheel, and yet another image under the Z filter wheel. Then, the three images (X, Y, and Z) are calibrated and calculated to obtain the true X, Y, and Z values.
[0005] If the spectrometer center point measurement is also integrated, the light is reflected to the spectrometer by a beam splitter installed in front of the filter wheel. The spectrometer collects the light once and obtains measurement data. Then, the data results measured by the spectrometer are used for calibration calculation to obtain the XYZ data values of the entire screen.
[0006] like Figure 1 As shown, the characteristic of traditional integrated spectral measurement filter-based colorimetric measurement schemes is that the XYZ filter is parallel to the imaging chip, and the filter is generally an interference filter. This type of filter can transmit light of a specific spectrum (X / Y / Z in this case), while the light that does not pass through is all reflected back into the converging lens. Part of it forms stray light inside the converging lens and eventually illuminates the imaging chip, while the other part is reflected onto the surface of the sample to be measured, and then imaged onto the imaging chip through the converging lens. This image is then received by the imaging chip along with the light emitted by the sample itself, thus causing a certain measurement error.
[0007] Furthermore, the spectral measurement process is independent of the XYZ measurement process. Generally, the brightness of the sample under test will fluctuate to some extent. This means that the product is not in the same state during XYZ colorimetry measurement and spectrometer measurement, but rather there will be brightness fluctuations. Therefore, the final calculated XYZ colorimetry values will have a certain deviation. Moreover, one round of measurement requires four operations: X filter imaging + Y filter imaging + Z filter imaging + spectrometer measurement, which is time-consuming. Summary of the Invention
[0008] In response to at least one defect or improvement requirement in the prior art mentioned in the background section, the present invention provides an integrated spectral measurement tilting filter type colorimetric measurement device and method to solve the technical problems of low colorimetric measurement accuracy and long measurement time caused by excessive stray light and independent spectral measurement process.
[0009] To achieve the above objectives, in a first aspect, the present invention provides an integrated spectral measurement tilting filter type colorimetric measurement device, comprising: an imaging unit, a theoretical three primary color filter, a spectrometer, and a converging lens;
[0010] The mirror surface of the theoretical three primary color filter is not parallel to the imaging surface of the imaging unit;
[0011] The imaging unit and the spectrometer are optically symmetrically conjugate with respect to the mirror surface of the theoretical three primary color filter;
[0012] The light source from the external sample to be tested is focused by the converging lens and can pass through the theoretical three primary color filter to form an image in the imaging unit; and the light source, after being focused by the converging lens, can be reflected by the theoretical three primary color filter to the spectrometer for spectral measurement.
[0013] To achieve the above objectives, in a second aspect, the present invention provides a colorimetric measurement method based on the above-described colorimetric measurement device, comprising:
[0014] In the measurement mode of each of the theoretical primary color filters, the center point chromaticity value and center point spectral value of the sample under test are measured simultaneously in the corresponding measurement mode.
[0015] The measurement results of one of the theoretical primary color filters are randomly selected, and the center point chromaticity values of the three theoretical primary color filters are calibrated respectively to obtain the center point calibrated chromaticity values of the three theoretical primary color filters in the measurement modes.
[0016] Based on the calibrated chromaticity value at the center point, a calibration coefficient is obtained. This calibration coefficient is then applied to the full-frame image of the sample under test to obtain the calibrated full-frame chromaticity value.
[0017] Furthermore, the formula for calibrating the center point chromaticity values under the measurement modes of any one of the theoretical primary color filters, and obtaining the center point calibration chromaticity values under the measurement modes of the three theoretical primary color filters respectively, specifically includes:
[0018] X center '= X center * f2(λ) / f1(λ);
[0019] Z center '= Z center * f2(λ) / f3(λ);
[0020] Y center '= Y center ;
[0021] Where * represents the multiplication sign; Y center X center and Z center f1(λ), f2(λ), and f3(λ) represent the center point chromaticity values of the sample under the measurement modes of one and two other theoretical primary color filters, respectively; f2(λ), f1(λ), and f3(λ) represent the center point spectral values of the sample under the measurement modes of one and two other theoretical primary color filters, respectively; Y center '、X center 'and Z center 'These represent the center-point calibration chromaticity values under the measurement modes of one selected theoretical primary color filter and two other theoretical primary color filters, respectively.
[0022] Furthermore, the formulas for f1(λ), f2(λ), and f3(λ) specifically include:
[0023] f1(λ)= f X (λ) / (1-X(λ));
[0024] f2(λ) = f Y (λ) / (1-Y(λ));
[0025] f3(λ) = f Z (λ) / (1-Z(λ));
[0026] Among them, f X (λ), f Y (λ) and f Z (λ) represent the reflected light spectrum measured by the spectrometer in the measurement mode of the corresponding theoretical primary color filter; 1-X(λ), 1-Y(λ) and 1-Z(λ) represent the reflectance spectrum measured in the measurement mode of the corresponding theoretical primary color filter.
[0027] To achieve the above objectives, in a third aspect, the present invention provides an integrated spectral measurement tilting filter type colorimetric measurement device, comprising: an imaging unit, a theoretical three primary color filter, a spectrometer, a beam splitter, and a converging lens;
[0028] The mirror surface of the theoretical three primary color filter is not parallel to the imaging surface of the imaging unit;
[0029] The light source from the external sample to be tested is focused by the focusing lens and can pass through the theoretical three primary color filter and be imaged in the imaging unit; and the light source, after being focused by the focusing lens, can be reflected by the beam splitter to the spectrometer for spectral measurement.
[0030] To achieve the above objectives, in a fourth aspect, the present invention provides a colorimetric measurement method based on the above-described colorimetric measurement device, comprising:
[0031] In the measurement mode of each of the theoretical primary color filters, the full-frame image of the sample to be tested in the corresponding measurement mode is acquired, and the three full-frame images are calibrated and calculated to obtain the full-screen colorimetric value of the sample to be tested.
[0032] After the above steps, the light reflected by the beam splitter is collected and measured, and the measurement data of the spectrometer is used for calibration calculation to obtain the corresponding spectral measurement results.
[0033] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:
[0034] (1) Compared with the prior art, the colorimetric measurement device of the present invention eliminates the beam splitter. By using the non-parallel arrangement of the theoretical three primary color filters and the imaging unit, and the optically symmetrical conjugate arrangement of the spectrometer and the imaging unit relative to the mirror surface of the theoretical three primary color filters, the light is directly reflected to the spectrometer for measurement using the theoretical three primary color filters. This avoids the stray light problem caused by reflected light when incident perpendicularly, thus improving the measurement accuracy. Moreover, compared with the prior art which requires four measurements (X filter imaging + Y filter imaging + Z filter imaging + spectrometer measurement), this solution integrates the spectral measurement into three measurements (X, Y, and Z), thus shortening the measurement time and improving the measurement efficiency.
[0035] (2) By arbitrarily selecting the measurement results of one of the theoretical primary color filters in the measurement mode, the present invention calibrates the center point chromaticity values of the three theoretical primary color filters in the measurement mode respectively, thereby overcoming the measurement error caused by the inconsistency of the state of the sample under different filter measurement modes and further improving the measurement accuracy. Attached Figure Description
[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0037] Figure 1 A schematic diagram of the optical path and structure of a filter-type colorimetric measurement device that integrates an independent spectral measurement process, provided for existing technologies;
[0038] Figure 2 A schematic diagram of the optical path and structure of a filter-type colorimetric measurement device that integrates a combined spectral measurement process, provided for an embodiment of the present invention. Detailed Implementation
[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.
[0040] The terms "first," "second," or "third," etc., used in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a particular order. Furthermore, the terms "comprising" or "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.
[0041] According to the Yang-Helmholtz theory of primary colors, color perception is the result of the combined stimulation of three primary colors of light. In the red, green, and blue primary color system, the stimulation levels of red, green, and blue are represented by R, G, and B, respectively. Since the red, green, and blue primary colors selected from the actual spectrum cannot be used to mix all colors existing in nature, negative stimulation values appear when the "standard colorimeter" is used to calibrate spectral colors, making calculation inconvenient and difficult to understand. Therefore, in 1931, the CIE theoretically hypothesized three primary colors that do not exist in nature, namely the theoretical three primary colors, represented by X, Y, and Z, in order to theoretically mix all colors, thus forming the XYZ colorimetric system. The theoretical X primary color is equivalent to a reddish-purple with a saturation higher than spectral red; the theoretical Y primary color is equivalent to a green with a saturation higher than spectral green at 520 nanometers; and the theoretical Z primary color is equivalent to a blue with a saturation higher than spectral blue at 477 nanometers. The stimulus levels of these three theoretical primary colors are represented by X, Y, and Z, which are the so-called tristimulus values or chromaticity values.
[0042] Given the technical problems mentioned in the background section regarding the low colorimetric measurement accuracy and long measurement time of existing filter-type colorimetric measurement devices or methods that integrate independent spectral measurement processes due to excessive stray light and independent spectral measurement processes, such as... Figure 2 As shown, Embodiment 1 provides a filter-type colorimetric measurement device integrating a combined spectral measurement process. Unlike traditional XYZ filters (theoretical tri-color filters), the XYZ filter here is placed at a certain angle to the imaging surface of the imaging chip within the filter wheel. For ease of industrial design, a 45° angle is preferred for illustration, but it is not limited to a 45° angle. Since the filter's response curve changes with the incident angle, this filter differs from the transmittance spectrum of conventional perpendicularly incident light. Therefore, when designing the filter transmittance film system, it is necessary to consider that the transmittance spectrum of incident light at a 45° angle conforms to the CIE 1931 response curve, rather than at 0°.
[0043] A spectrometer receiving probe is set on the reflective conjugate surface, typically an optical fiber; the position of this optical fiber relative to the mirror surface of the XYZ filter is optically conjugate symmetrical with respect to the imaging surface of the area array camera.
[0044] The light source from the external sample is focused by the converging lens and can pass through the theoretical three primary color filters to form an image in the imaging unit; and the light source, after being focused by the converging lens, can be reflected by the theoretical three primary color filters to the spectrometer for spectral measurement.
[0045] A colorimetric measurement method based on the filter-type colorimetric measurement device integrating a combined spectral measurement process provided in Embodiment 1 above mainly includes the following steps:
[0046] Step 1: In the measurement mode of each of the theoretical primary color filters, simultaneously measure and obtain the center point chromaticity value and center point spectral value of the sample under the corresponding measurement mode.
[0047] More specifically, we first measure the reflectance spectrum of the actual XYZ filter under 45° incident light conditions. We can then determine that if the transmittance spectra of the XYZ filter are X(λ), Y(λ), and Z(λ), the reflectance spectra of the three filters are R... X = 1-X(λ)R Y =1-Y(λ)and R Z = 1-Z(λ).
[0048] Theoretically, assuming the spectrometer receives the reflected light spectrum through the X-filter (hypothetical first primary color filter or theoretical first primary color filter) is f X If f(λ), then the actual emission spectrum of the sample to be tested is f(λ) = f(λ). X (λ) / (1-X(λ)).
[0049] Similarly, when measured under Y filter (hypothetical second primary color filter or theoretical second primary color filter) and Z filter (hypothetical third primary color filter or theoretical third primary color filter) modes respectively, the actual emission spectrum of the sample to be measured can be derived as f(λ) = f Y (λ) / (1-Y(λ)), f(λ) = f Z (λ) / (1-Z(λ)).
[0050] In practical work, measurements are first taken under an X-filter to obtain an image of the sample under the X-filter acquired by the light sensor. The chromaticity value measured at the center point is represented as X. center Meanwhile, the spectral value of the center point of the sample measured by the spectrometer is f1(λ) = f X (λ) / (1-X(λ)). Similarly, the chromaticity value obtained by measuring the center point under the Y filter is expressed as Y. center And at this time, the spectral value of the center point of the sample to be tested measured by the spectrometer is f2(λ) = f Y (λ) / (1-Y(λ)). Similarly, Z is obtained by measuring under the Z filter. center and f3(λ) = f Z (λ) / (1-Z(λ)).
[0051] Step 2: Select any one of the theoretical primary color filters and calibrate the center point chromaticity values under the measurement modes of the three theoretical primary color filters respectively, so as to obtain the center point calibrated chromaticity values under the measurement modes of the three theoretical primary color filters respectively.
[0052] More specifically, since f1(λ), f2(λ), and f3(λ) are the center point spectra or spectral values of the sample measured at three different times, they respectively correspond to the X values of the sample measured in three states. center ,Y center and Z center Value. At this point, a calibration process can be performed on the three states. The measurement result under the X, Y, or Z filter can be used as the standard. In this embodiment, the brightness measured under the Y filter is used as the standard, so the calibrated X value... center ' = X center * f2(λ) / f1(λ); Z center =Z center * f2(λ) / f3(λ); * indicates multiplication; Y center ' = Y center That is, after considering the instability of product brightness or color at different times, the calibrated center point color values measured through the XYZ filter are X... center ',Y center 'and Z center '.
[0053] Step 3: Obtain calibration coefficients based on the center point calibration chromaticity values, and extend the application of the calibration coefficients to the full-frame image of the sample under test to obtain the calibrated full-frame calibration chromaticity values.
[0054] More specifically, in step 2, the XYZ chromaticity values of the center point are corrected using the spectral values measured at the center point. Applying the corresponding calibration coefficients to the full-frame XYZ image yields the calibrated X', Y', and Z' chromaticity values of the entire image of the sample under test.
[0055] At this point, the X'Y'Z' chromaticity values and the center point spectral values of the entire image can be obtained, thus completing the entire measurement process.
[0056] The colorimetric measurement device in this embodiment eliminates the beam splitter compared to existing technologies. By employing a non-parallel arrangement of the theoretical three primary color filters and the imaging unit, and an optically symmetrical conjugate arrangement of the spectrometer and the imaging unit relative to the mirror surfaces of the theoretical three primary color filters, light is directly reflected to the spectrometer for measurement using the emitting surface of the theoretical three primary color filters. This avoids the problem of excessive stray light caused by reflected light during perpendicular incidence, thus improving measurement accuracy. Furthermore, compared to the existing technology requiring four measurements (X filter imaging + Y filter imaging + Z filter imaging + spectrometer measurement), this embodiment integrates spectral measurement into three measurements (X, Y, and Z), thereby shortening the measurement time and improving measurement efficiency. This embodiment further improves measurement accuracy by calibrating the center point colorimetric values of the three theoretical primary color filters using the measurement results from any one of the theoretical primary color filter measurement modes. This overcomes measurement errors caused by inconsistent states of the sample under different filter measurement modes, further enhancing measurement accuracy.
[0057] In Embodiment 2, this application provides a filter-type colorimetric measurement device that integrates an independent spectral measurement process, which mainly includes: an imaging unit, theoretical three primary color filters, a spectrometer, a beam splitter, and a converging lens.
[0058] The light source from the external sample to be tested is focused by the converging lens and can pass through the theoretical three primary color filters to form an image in the imaging unit; and the light source, after being focused by the converging lens, can be reflected by the beam splitter to the spectrometer for spectral measurement.
[0059] The only difference from existing technology is that the mirror surface of the theoretical three-primary-color filter is not parallel to the imaging surface of the imaging unit. That is, in Figure 1 In this process, the XYZ filter, which was originally parallel to the imaging chip, is adjusted to a tilted and non-parallel position. This avoids stray light problems caused by reflected light when incident vertically, and can improve measurement accuracy to some extent.
[0060] A colorimetric measurement method based on the filter-type colorimetric measurement device integrating an independent spectral measurement process provided in Embodiment 2 above mainly includes the following steps:
[0061] In the measurement mode of each of the theoretical primary color filters, the full-frame image of the sample under test is acquired in the corresponding measurement mode. The three full-frame images are then calibrated and calculated to obtain the full-screen chromaticity value of the sample under test.
[0062] After the above steps, the spectrometer collects and measures the light reflected by the beam splitter, and uses the spectrometer's measurement data for calibration calculations to further obtain the corresponding spectral measurement results.
[0063] The foregoing description is merely an exemplary embodiment of this disclosure and should not be construed as limiting the scope of this disclosure. Any equivalent changes and modifications made in accordance with the teachings of this disclosure shall still fall within the scope of this disclosure. Other embodiments of this disclosure will be readily apparent to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This invention is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not described herein. The specification and embodiments are to be considered exemplary only, and the scope and spirit of this disclosure are defined by the claims.
[0064] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0065] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A tilting filter-type colorimetric measurement device integrating spectral measurement, characterized in that, include: Imaging unit, theoretical three-color filters, spectrometer, and converging lens; The mirror surface of the theoretical three primary color filter is not parallel to the imaging surface of the imaging unit; The imaging unit and the spectrometer are optically symmetrically conjugate with respect to the mirror surface of the theoretical three primary color filter; The light source from the external sample to be tested is focused by the converging lens and can pass through the theoretical three primary color filter to form an image in the imaging unit; and the light source, after being focused by the converging lens, can be reflected by the theoretical three primary color filter to the spectrometer for spectral measurement.
2. A colorimetric measurement method based on the colorimetric measuring device of claim 1, characterized in that, include: In the measurement mode of each of the theoretical primary color filters, the center point chromaticity value and center point spectral value of the sample under test are measured simultaneously in the corresponding measurement mode. The measurement results of one of the theoretical primary color filters are randomly selected, and the center point chromaticity values of the three theoretical primary color filters are calibrated respectively to obtain the center point calibrated chromaticity values of the three theoretical primary color filters in the measurement modes. Based on the calibrated chromaticity value at the center point, a calibration coefficient is obtained. This calibration coefficient is then applied to the full-frame image of the sample under test to obtain the calibrated full-frame chromaticity value.
3. The colorimetric measurement method as described in claim 2, characterized in that, The formulas for calibrating the center point chromaticity values under the measurement modes of any one of the theoretical primary color filters, and obtaining the center point calibrated chromaticity values under the measurement modes of the three theoretical primary color filters respectively, specifically include: X center ’ = X center * f2(λ) / f1(λ); Z center ’ = Z center * f2(λ) / f3(λ); AND center ' = Y center ; Where * represents the multiplication sign; Y center X center and Z center f1(λ), f2(λ), and f3(λ) represent the center point chromaticity values of the sample under the measurement modes of one and two other theoretical primary color filters, respectively; f2(λ), f1(λ), and f3(λ) represent the center point spectral values of the sample under the measurement modes of one and two other theoretical primary color filters, respectively; Y center '、X center 'and Z center 'These represent the center-point calibration chromaticity values under the measurement modes of one selected theoretical primary color filter and two other theoretical primary color filters, respectively.
4. The colorimetric measurement method as described in claim 3, characterized in that, The formulas for f1(λ), f2(λ), and f3(λ) specifically include: f1(λ)= f X (λ) / (1-X(λ)); f2(λ) = f Y (λ) / (1-Y(λ)); f3 (λ) = f Z (λ) / (1-Z(λ)); Among them, f X (λ), f Y (λ) and f Z (λ) represent the reflected light spectrum measured by the spectrometer in the measurement mode of the corresponding theoretical primary color filter; 1-X(λ), 1-Y(λ) and 1-Z(λ) represent the reflectance spectrum measured in the measurement mode of the corresponding theoretical primary color filter.