CN113870751A - Method for setting blue light radiation safety boundary of brightness, color temperature and radiation accumulation - Google Patents
Method for setting blue light radiation safety boundary of brightness, color temperature and radiation accumulation Download PDFInfo
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Abstract
The invention relates to a method for setting a blue light radiation safety boundary of brightness, color temperature and radiation accumulation, which comprises the steps of sampling N sampling points N with different brightness and different color temperatures, detecting and obtaining the brightness L of each sampling point NnSum color temperature CTnCalculating a threshold exposure time t corresponding to the blue light radiation power of each sampling point n without blue light hazardnBased on the brightness L of each sampling pointnColor temperature CTnAnd an exposure time threshold tnAnd fitting to form a safety boundary curved surface or a safety boundary function of brightness, color temperature and exposure time under the condition of no blue light hazard, and judging or confirming a blue light safety zone according to the safety boundary curved surface, wherein the zone at the low value side of the boundary curved surface is a blue light safety zone, and the zone at the high value side of the boundary curved surface is a zone with blue light hazard risk.
Description
Technical Field
The invention relates to a method for setting a blue light radiation safety boundary of brightness, color temperature and radiation accumulation and application of the method in display control, which is suitable for various displays (screens) such as medical displays (screens), civil displays (screens) and near-field displays.
Background
At present, for an LED (light emitting diode) display (screen), including OLED (organic light emitting diode) display, MicroLED (micrometer light emitting diode) display, MiniLED (small-spacing light emitting diode) display, LED backlight + LCD (liquid crystal display) and other displays (screens), the method for evaluating and testing the visual health is disclosed, in particular to a method for evaluating the damage or harm of blue light radiation of the LED display (screen) to the retina of human eyes, besides knowing the physical properties (such as the size, color temperature, brightness and the like) of the display (screen) which influence the accumulated size of the blue light radiation, the distance (the viewing distance of a general desktop display is 30cm, 50cm, 80cm or other human ergonomic viewing distances) and the viewing accumulated time (generally within 1 hour) of the display (screen) which influences the blue light radiation accumulation size, the viewing distance of the general desktop display is regulated according to the human ergonomics, the smart phone and the mobile flat panel display are 20cm, 30cm or other human ergonomic viewing distances) and the viewing accumulated time is also known, or 1-2 hours and 2-3 hours, professional medical image display and interpretation for 2-3 hours, often 4-8 hours, and professional civil image display and analysis for 2-3 hours, often 4-8 hours). At present, no fitting calculation method based on a critical safety boundary curved surface and a safety region of blue light radiation hazard exemption level (called RG0 risk-free level) between the brightness, the color temperature and the radiation accumulation time of an LED display (screen) is provided, integrated or implanted, comprehensive relation evaluation analysis of the change of parameters such as the brightness, the color temperature and the like which influence the blue light radiation intensity of the LED display (screen) along with the radiation accumulation time cannot be actively realized, multi-parameter evaluation and regulation and control are more difficult to be carried out according to the safety boundary curved surface and the envelope safety region of the blue light radiation hazard exemption level RG0 which influence the display visual health, the control of the damage risk degree of the retina of the human eye is greatly influenced, and the risk is higher.
Disclosure of Invention
The present invention is directed to overcome the above-mentioned drawbacks of the prior art, and provides a method for setting a blue light radiation safety boundary of brightness, color temperature and radiation accumulation, so as to obtain a blue light radiation exemption level and a hazard risk boundary curved surface between the brightness, color temperature and radiation accumulation time of an LED display (screen), and provide a corresponding basis for the evaluation and control of the blue light radiation hazard of the display under relevant conditions.
The technical scheme of the invention is as follows: the method for setting the safety boundary of blue light radiation with different brightness, color temperature and radiation accumulation for N blue light radiationSampling is performed at sampling points N (N is 1,2,3, … …, N) of the same color temperature (which may be called luminance and color temperature sampling points), and the luminance L of each sampling point N is detectednSum color temperature CTnCalculating the exposure time threshold t without blue light hazard (blue light hazard exemption level) corresponding to the blue light radiation power of each sampling point n according to the following formulan，
PBn·tn＝EL
Based on the brightness L of each sample pointnColor temperature CTnAnd an exposure time threshold tnPerforming surface fitting of the brightness L, the color temperature CT and the exposure time t to form a functional relation (safety boundary function for short) between the brightness L and the color temperature CT under the condition of no blue light hazard and the longest exposure time under the corresponding condition or a safety boundary surface (safety boundary surface for short) or a safety boundary function between the brightness, the color temperature and the radiation accumulation time (exposure time) under the condition of no blue light hazard:
L＝LRGO＝f(CT,t)
and/or
t＝tRGO＝g(L,CT)
And/or
CT＝CTRGO＝h(t，L)
The functions all represent the same boundary surface, are equivalent, can be mutually replaced under certain precision, and can also represent the boundary surface in any one or more function forms or perform related analysis such as safe area and the like.
Alternatively, in general, the functional relationship of t, L, CT on the boundary surface can be expressed by:
F(t，L，CT)＝0
the blue light radiation power P of each sampling point n can be calculated according to the following formulaBn：
Wherein,
PBnfor the blue radiation power of the nth sampling point, n is 12,3, … …, N, is the blue-weighted radiation power, which can be defined according to the above equation, in common units: j.s-1；
tnBlue light radiation power P for nth sampling pointBnThe corresponding exposure time threshold without blue light hazard is in the following common unit: h (hours);
ELfor a safe threshold (set value) for blue radiation energy, the common unit: j (joules). ELCan be determined according to relevant technical specifications, standards and other documents and/or through experimental or theoretical analysis and other manners. For example, may be obtained in accordance with presently recognized or appropriate standards, e.g., in the context of the prior art, may be EL＝0.220J；
L is luminance (display luminance), common unit: cd/m2(candela/m squared);
LRGOthe luminance threshold for no blue light hazard, the luminance for satisfying a functional relationship, as a function of exposure time and color temperature, the common unit: cd/m2；
CT is color temperature (display color temperature), and the central color temperature of the display can be generally adopted, and the common unit: k (kelvin);
CTRGOthe color temperature threshold for no blue light hazard, the color temperature for satisfying a functional relationship, as a function of brightness and exposure time, the common unit: k;
t is the exposure time, common unit: h (hours) or s (seconds); s (seconds) or h (hours);
tRGOexposure time threshold for no blue light hazard, exposure time for satisfying a functional relationship, as a function of color temperature and brightness, common units: h;
Pλ(λ)nthe spectral radiant power related to the wavelength of the nth sampling point can be obtained by detection at the time of sampling or according to known knowledge, the common unit is: j.s-1·nm-1；
B (lambda) is a blue light hazard weighting coefficient related to wavelength, and is dimensionless;
λ is the wavelength, the common unit: nm (nanometers).
f (), g () andh () is used to represent the corresponding functional relationship, passing through the data L of each sample point nn、tnAnd CTnAnd (6) obtaining through fitting. F (t, L, CT) ═ 0 is an equivalent equation expression of these functions, and F () is an equivalent function in the corresponding expression.
The brightness range of the sampling point can be at the maximum calibration brightness L of the displaymaxAnd a minimum calibration luminance LminIn the meantime. Should generally contain L ═ LminAnd L ═ LmaxOr adjacent to L ═ LminAnd L ═ LmaxThe sampling points of (a).
The color temperature range of the sampling point can be at the maximum calibration color temperature CT of the displaymaxAnd minimum calibration color temperature CTminShould generally include CT ═ CTminAnd CT ═ CTmaxOr adjacent CT ═ CTminAnd CT ═ CTmaxThe sampling points of (a).
The sampling points may be substantially evenly distributed in the L-CT plane. The method can adjust or set a brightness in the brightness range of the sampling point, then adjust and set a plurality of color temperatures according to the color temperature range of the sampling point to respectively sample (relevant data detection) under the condition of keeping the brightness unchanged basically, and then adjust or set another brightness to repeat the sampling process, so that the formed sampling points are approximately uniformly distributed in a vertically and horizontally aligned arrangement on an L-CT plane. It is conceivable to increase the density of sampling points in an area where the exposure time threshold value changes greatly. The number of the sampling points can be according to the actual requirement, so that the boundary curved surface formed by fitting meets the precision requirement of analysis and control.
When other factors obviously influencing the risk of blue light harm exist, sampling can be carried out under the condition that the factors are not changed, or the influence caused by the change of the factors is eliminated from data obtained by sampling according to the grasped natural law.
The fitting of the boundary curved surface can be realized by adopting the existing polynomial fitting mode, and the existing fitting tools or platforms such as matlab and the like can be utilized.
The lower limit 380(nm) and the upper limit 700(nm) of the integral expression represent the lower limit and the upper limit of the wavelength range in which the blue light hazard should be considered, respectively, and may be appropriately adjusted according to the actual conditions and the knowledge of the blue light hazard and the display light emission characteristics, and as can be seen from fig. 3, when the wavelength is less than 380(nm) and greater than 700(nm), B (λ) may be regarded as zero.
According to the characteristics of blue light hazard, any one of the arguments is fixed, and f (), g () and h () are all decreasing functions of another argument (see fig. 1 and fig. 2), and the absolute value of the derivative is also usually a decreasing function, and the tangent plane of the boundary curved surface is located on the low-value side thereof. According to practical requirements, any two variables on the safety boundary surface can be used as independent variables, and the maximum safety threshold (maximum value in the case of no blue light hazard) of the third variable under the determined values of the two independent variables is determined. It is also possible to analyze the safety (no blue light hazard) value ranges of the other two variables in the case that one of the variables is determined, for example, to adjust the brightness and color temperature to meet the viewer's needs and ensure no risk of blue light hazard in the case that the viewing time is determined.
The judgment or confirmation of the blue light safety zone can be carried out according to the safety boundary surface, and the blue light safety zone is positioned on the low-value side of the boundary surface (for any suitable two variables, the value of the third variable is smaller than the corresponding value of the boundary surface, for example, for any suitable combination of CT and L, t is less than tRGOSide) is a blue light safe region, located on the high-valued side of the bounding surface (for any suitable two of the determined values of the variables, the third having a value greater than the corresponding value on the bounding surface, e.g., for any suitable combination of CT and L values, t > tRGOSide) is an area where there is a risk of blue light hazard (unsafe area), corresponding to a risk area of RG1 or higher.
In general, the boundary surface may be regarded as or considered a safety region.
The three-dimensional coordinate system (three-dimensional Cartesian coordinate system) can be established by taking the variables t, CT and L as coordinate axes, and any variable can be taken as a dependent variable according to actual needs due to the fact that t, CT and L are related to each other, so that the three coordinate axes t, CT and L in the coordinate system are equivalent, and can be drawn into coordinate axes in the directions of the conventional X axis, Y axis and Z axis in any mode, and the coordinate axes t, CT axis and L axis can be called as t axis, CT axis and L axis.
The boundary surface is CT ═ h (t, L) or any other equivalent function, and for a particular display, CT ismin≤CT≤CTmax，Lmin≤L≤LmaxWherein, CTminFor minimum calibrated color temperature, CT, of the displaymaxFor maximum calibrated color temperature, L, of the displayminFor minimum calibrated brightness of the display, LmaxFor the maximum calibrated brightness of the display, the safety range is referred to as CT ═ h (t, L), CT ═ CTmin、CT＝CTmax、L＝Lmin、L＝LmaxAnd t is the area enclosed by 0 and is positioned on the low-value side of the boundary curved surface.
For any coordinate point (t, L, CT) (any combination of t, L, CT values), if the coordinate point is in a safe area, it is determined that there is no risk of blue light hazard, and if the coordinate point is in an unsafe area, it is determined that there is a risk of blue light hazard.
For any coordinate point (t, L, CT) located in the safety region, the adjustment margin (adjustment margin of the parameter corresponding to any coordinate axis) in the coordinate axis direction can be determined according to the distance from the coordinate point to the boundary surface in the coordinate axis (t axis, CT axis, and L axis) direction, that is, the parameter is allowed to be increased at most when other relevant parameters are not changed. For example, if the coordinate point is at a distance d from the boundary surface in the t-axis directiontIt can be judged that the exposure time (viewing time) can be prolonged by d at most on the basis of the original set time under the corresponding color temperature and brightnesstIf the time longer than the original set time exceeds dtThen there is a risk of blue light hazard. In another example, the distance d from the boundary surface in the CT axis direction according to the coordinate pointCTIt can be determined that the color temperature of the display screen can be increased by d at most on the basis of the original set color temperature under the corresponding display brightness and viewing time (exposure time)CTIf the color temperature increased from the original set color temperature exceeds dCTThen there is a risk of blue light hazard. For another example, the distance d from the boundary surface in the L-axis direction according to the coordinate pointLIt can be judged that the color temperature of the display screen can be increased by d at most on the basis of the original set brightness under the corresponding color temperature and viewing time (exposure time) of the displayLIf the brightness increased from the original set brightness exceeds dLThen there is a risk of blue light hazard.
When detecting the sampling points (brightness and color temperature sampling points), the central color temperature, brightness and other parameters (or variables) (if necessary) or data of the display screen can be detected according to the existing detection means, usually with the central position of the display as the detection point or the central point of the detection.
According to the actual requirement, when detecting the sampling points (brightness and color temperature sampling points), a multi-point detection method (for example, a nine-point detection method and a twenty-five-point detection method) can be adopted to perform multi-point detection, and a plurality of points are selected as detection points (or called position detection points) on the display screen according to a detection rule to perform detection.
The nine-point detection method can be a white field nine-point test method.
After the detection by the multipoint detection method, the safety boundary curved surface is calculated based on the data of each detection point, and the safety area is confirmed (determined) based on a set criterion (for example, an accepted criterion or an appropriate criterion).
For example,
1) when the confirmation results of the detection points (the confirmation results of the detection points are the confirmation results obtained by calculation according to the detection data of the detection points) are all safe areas, the safety areas are confirmed, otherwise, the unsafe areas are confirmed, namely, when the confirmation results of at least one detection point are the unsafe areas, the unsafe areas are confirmed.
2) In the case where the safety region is confirmed when the confirmation result of at least a certain number (or a certain proportion) of the plurality of detection points (for example, more than 50% of all the detection points) is the safety region, and otherwise the unsafe region is confirmed, that is, when the confirmation result of at least a certain number (or a certain proportion) of the plurality of detection points (for example, not less than 50% of all the detection points) is not the safety region, the unsafe region is confirmed, in which case the confirmation result required to confirm the safety region is the minimum number of detection points of the safety region or the confirmation result required to confirm the unsafe region is the minimum number of detection points of the unsafe region may be divided according to actual circumstances.
3) The method comprises the steps of carrying out weighted average on each safety boundary curved surface (exposure time threshold) obtained according to data of each detection point, calculating to obtain an equivalent boundary curved surface (exposure time threshold) of the display, and confirming (judging) a safety region according to the equivalent boundary curved surface in the same way as the confirmation according to the boundary curved surface.
For example, for a nine-point test (e.g., white field nine-point test), a safety boundary curve or a safety boundary function without blue light hazard may be obtained or established by calculation in the following manner: t is tRGO＝g(L，CT)
Calculating and fitting a corresponding safety boundary curved surface according to the detection data of each detection point:
ti＝tRGOi＝gi(Li，Ti)
wherein, the subscript i represents the detected data of the detected point i or the related data parameters obtained by calculation (including fitting) according to the detected data of the detected point i. E.g. tiTime t in the safety boundary function calculated according to the detection data of the detection point i; t is tRGOiExposure time threshold t without blue light hazard calculated according to detection data of detection point iRGOThe brightness L detected for the detection point i is the exposure time on the safety boundary curved surface based on the detection data of the detection point iiSum color temperature CTiA function of (a); gi() Indicating a security boundary function calculated from detection data of a detection point i, where i is 0, 1,2,3,4, 5,6,7,8, which is the number or sequence number of the detection point, detection point 0 (detection point where i is 0) is a detection point located at the center of the display screen, detection points 1 to 4 (detection points where i is 1,2,3, 4) are respectively detection points located at the middle of the outer sides in the lateral and longitudinal directions, and detection points 5 to 8 are respectively detection points located at the four corners of the outer sidesAnd detecting points.
With exposure time threshold t obtained from detection data at each detection pointRGOiPerforming weighted average as equivalent exposure time threshold t of the displayRGOvObtaining the exposure time and the color temperature CT detected by each detection pointiCorrelated safety boundary function (safety boundary surface), or color temperature CT detected by exposure time and central area (detection point 0) of display screen0Relevant safety boundary function (safety boundary surface):
or
Wherein, tRGOvIs an equivalent exposure time threshold;
αithe ratio of the luminance detected for the other detection points than the detection point 0 to the luminance detected for the detection point 0, i.e., αi＝Li/L0. Can also be regarded as alpha0＝1。
βiThe ratio of the color temperature detected for the other detection points except the detection point 0 to the color temperature detected for the detection point 0, that is, βi＝CTi/CT0. Can also be regarded as beta0＝1。
gv() Representing the corresponding function.
αiAnd betaiCan be obtained by calculation according to actual detection data. When multiple detections are performed (e.g., multiple brightness and color temperature samples are set), the corresponding α can be calculated by arithmetic mean or weighted averageiAnd betai. For example, one convenient and feasible way is to perform brightness (or color temperature) detection at maximum, intermediate and minimum power of the display for viewing the range of interest, and obtain maximum brightness (or color temperature) corresponding to maximum, intermediate and minimum power of the display for each detection point) Minimum luminance (or color temperature) and intermediate luminance (or color temperature), the sum of the maximum luminance (or color temperature), the minimum luminance (or color temperature) and twice the intermediate luminance (or color temperature) at each detection point is divided by 4 as a value for αi(or beta)i) The average value of the calculated brightness (or color temperature) is taken as L according to the average value of the brightness (or color temperature) of the corresponding detection pointi(or CT)i) Calculating alphai(or beta)i)。
The weighted average methods basically accord with the actual conditions of the display screen, accord with the aim and the requirement of the invention under the background of the prior art, and can obtain the result which accords with the actual control precision requirement.
The sampling (detection) of each sample point should be performed under substantially the same correlation conditions. In addition to the brightness, color temperature and exposure time according to the present invention, if other factors/parameters affecting the blue light hazard change, the influence of these changes on the blue light hazard risk or the safety area should be considered when performing the correlation technique and the analysis and judgment related to the safety area, etc.
The invention has the beneficial effects that: the method can obtain the radiation accumulation time (exposure time or viewing time) corresponding to the limit value that the display (screen) reaches the blue light radiation hazard-exemption level RG0 under different brightness and color temperature of the display (screen) with a certain size at a certain viewing distance, and calculate to obtain the blue light radiation-exemption level and hazard risk boundary curved surface and a safe area based on the brightness, the color temperature and the radiation accumulation time of the display (screen) such as an LED and the like, so as to judge whether the actual or predicted viewing has the blue light hazard risk and the allowable adjustment allowance, and can be applied to the automatic and manual control of display screen display.
The invention enables display (screen) products such as various medical displays, civil displays, mobile phone display screens, near-field displays and the like to have the functions of displaying visual health, namely, the retinal exemption level and risk evaluation of the damage of blue light radiation to human eyes, provides a blue light radiation safety boundary curved surface and a safety region between the color temperature of the display (screen) and the radiation accumulation time influence factors generated through fitting calculation, is convenient for warning the color temperature performance index regulation and control operation, is convenient for users to operate and control, is mature and standard in fitting calculation, and does not increase the hardware cost.
The product has good effect in field test and blue light radiation hazard evaluation of medical and civil displays (screens) and smart phone screens.
The invention is applicable to various displays, can be applicable to medical displays, civil displays and other similar displays, and can also be applicable to near-field displays, such as various wearable displays like helmet-type displays and glasses-type displays or displays of wearable devices, such as wearable displays for AR/VR, wherein the viewing distance of the so-called near-field display can be within about 1-10 cm.
Drawings
FIG. 1 is a schematic diagram of a boundary curved surface and a safety zone under a three-dimensional coordinate system of t, CT and L;
FIG. 2 is a B (λ) graph (λ -B (λ) curve) to which the present invention relates;
FIG. 3 is a distribution diagram of detection points in the nine-point detection method according to the present invention.
Detailed Description
Referring to fig. 1-3, the present invention uses a polynomial fitting technique or other fitting techniques to fit coordinates of each discrete point of a color temperature and radiation accumulation time value corresponding to a blue light radiation hazard exemption level RG0 limit value under different brightness and color temperature, and calculates and generates a new blue light radiation safety boundary curved surface of display (screen) brightness, color temperature and radiation accumulation time, an area on a side where the blue light radiation safety boundary curved surface is less than or equal to the blue light radiation hazard exemption level limit value is a safety boundary area, and an area on a side where the blue light radiation safety boundary curved surface is greater than the blue light radiation hazard exemption level limit value is an unsafe risk boundary area.
The boundary surface may be drawn using a three-dimensional coordinate system (cartesian coordinate system) composed of a t-axis, a CT-axis, and an L-axis (see fig. 1), which may correspond to an X-axis, a Y-axis, and a Z-axis in the three-dimensional coordinate system in any manner. For the brightness L of each sampling point n obtained by sampling and calculationnColor temperature CTnAnd exposure time threshold t of the brightness and color temperaturenObtaining the functional relation of the boundary surface by fitting operation, and locating at the lower part of the boundary surfaceThe area on the value-taking side is a safe area, and the area on the high value-taking side of the boundary curved surface is an unsafe area.
The following steps may be used for the fitting of the safety boundary surface:
1) obtaining a judgment formula about the limit energy of the blue light radiation hazard exemption grade RG 0;
2) obtaining radiation accumulation time (exposure time threshold) corresponding to the limit value that the display (screen) reaches the blue light radiation hazard exemption level RG0 under different brightness and color temperature values of the certain display under the parameters such as a certain test distance and the like according to the judgment formula;
3) after the radiation accumulation time corresponding to the exempt level limit value is reached by the blue light hazard of the display (screen) under different color temperature values, the brightness value L of different sampling pointsn(unit: cd/m)2) Color temperature value CTn(unit: K) and corresponding radiation accumulation time value tnAnd (unit: h) forming a plurality of discrete points, and performing new mathematical fitting calculation based on the discrete coordinate points to obtain a safety boundary curved surface of the color temperature and the radiation accumulation time for blue light radiation hazard evaluation among the brightness, the color temperature and the radiation accumulation time of the display (screen).
4) And drawing a boundary curved surface, wherein an area enclosed by the boundary curved surface and the upper and lower limit planes of the corresponding parameter values is a safe area.
When the safety boundary surface is calculated or fitted according to the data of each detection point, the characteristics of the obtained safety boundary surface are similar to those of the safety boundary surface shown in the figures 1 and 2.
The formula for determining the limit energy of the blue light radiation hazard exemption grade RG0 can refer to the following deduction:
1) according to the national standard GB/T20145-2006/CIE S009/E: 2002 and the international standard CEI/IEC 62471:2006 and IEC/TR62778:2014 relating to the photobiological safety of lamps and lamp systems, the following formula is adopted to judge that no blue light hazard risk exists:
wherein L isBIs blueLight-weighted radiance (W.m)-2sr-1)，Lλ(λ) is the spectral radiance (W.m) of the light source related to the wavelength λ-2sr-1nm-1) B (λ) is a blue light hazard weighting coefficient associated with a wavelength λ, λ is the wavelength (nm, nanometers), t represents the exposure time (s, seconds), J is units of energy joules, W is units of power watts, and m is2Is the square meter and sr is the corresponding sphericity of the solid angle.
2) Compared with the illuminating lamp, the use scene of the medical and civil display (screen) has high resolution (full high definition 1K (2MP), 2K (5MP), ultra high definition 4K (8MP), 8K (32MP) or other resolutions), long time (4-8 hours), short-distance viewing (20cm, 30cm, 50cm or other viewing distances), and high brightness (300 + 800 cd/m)2Or other brightness values), high color temperature (5000K-9000K or other color temperature values), large screen area (20-30 inches, 55-120 inches or other unequal sizes on the desktop, 5-6 inches, 8-10 inches or other unequal sizes on the mobile phone and the mobile tablet), and a new formula algorithm for meeting the illumination requirements of the lighting lamp and the lamp system, and suitable for the irradiation influence of the large-area spectral power of the LED (light emitting diode) display (screen) is needed. According to the use requirement, the appropriate use time is selected, and 8 hours (h), namely 28800 seconds(s), are generally selected. The display (screen) resolution 1K is 1920x1080 pixels, 2K is 2560x2048 pixels, 4K is 4096x2160 pixels, 8K is 7680 x 4320 pixels, and MP is million pixels.
3) According to equation (1), if the time effect is considered, it is assumed that t > 104If the time effect is still true, the radiation accumulation (energy) can be improved and newly introduced as the threshold for the judgment of the radiation exemption level RG0, and the formula is:
Eexp＝P·t (2)
wherein EexpThe accumulated amount of radiation received by the eye pupil (J), and P is the radiation power (J · s)-1) And t represents an exposure time(s).
4) Spectral radiance color temperature formula:
wherein, Pλ(λ) is the spectral blue light weighted radiant power (J · s) associated with the wavelength λ-1) (ii) a A is the effective radiation source area (m) determined by 0.1rad of maximum pair corner2) (ii) a Ω is the solid angle (sr) of the pupil with respect to the light source, the size of which is related to the pupil diameter, the observation distance.
5) The application scene characteristics of the medical and civil display (screen) are applied, and the formula (1) is improved and transformed to have the following characteristics:
wherein, PBFor blue radiation power (J.s)-1)。
6) The subtended angle of the light source is a physical quantity related to the size and observation distance of the light source, and for a medical image display or other similar display screens, the subtended angle alpha of the rectangular thin light source is as follows:
wherein, a and b are respectively the length and width (mm) of the rectangular thin light source, r is the observation distance or the testing distance (mm), and rad is radian unit.
For medical image displays, the subtended angle at the viewing distance of the optical axis r (e.g., 500mm, etc.) is much greater than 0.1rad, and thus the effective radiation source area is independent of source size. If the area of the effective radiation light source is a circular plane and the radius is R (mm), the effective radiation radius formula is as follows according to the limit of 0.1rad to the corner:
from the formula (6), the effective radiation area A (unit square meter m) can be obtained2) Comprises the following steps:
A＝π*R2(7)
from the definition of solid angle, one can obtain:
wherein S is the area of human eye pupil (mm)2) When the screen is observed for a long time and the light adaptation state is achieved, it is assumed that the pupil diameter is stabilized to be 3mm and S is taken to be 7mm2(ii) a r is the observation distance or test distance (mm).
7) The judgment formula (RG0) of safe threshold value or exemption level RG0 limit energy of blue light radiation can be obtained after improvement and sorting:
the corresponding safety thresholds are:
PBL·t＝EL＝0.220J (10)
the invention aims at the display application scenes of various displays (screens) such as long-time, short-distance, high-color-temperature viewing, large-size screen area and the like, so that the blue light spectral power of various displays (screens) for medical use, civil use and the like is judged more suitably by the above formula.
8) The P is judged by calculating according to the above formula (9)BT is related to 0.220J (RG0), and if it is less than or equal to 0.220J, it indicates that the display (screen) blue radiation value is within the safety threshold or exempt grade RG0 value for the specified usage time, and does not cause substantial blue light damage to the retina of the human eye. If PBT is greater than 0.220J, it causes unrecoverable blue light damage to the retina of the human eye for the prescribed period of use. In case that the safety threshold of the blue light radiation energy is different from 0.220J, the analysis judgment can be carried out according to the corresponding threshold.
For other scenes, E can be calculated according to the same or similar calculation processL。
Depending on the energy characteristics, under the background of the prior art and recognized or appropriate evaluation criteria for the risk of blue light hazard, it can be considered that the above equation (10) is applicable to various displays to which the present invention relates.
E can be calculated according to the same or similar calculation process according to the recognized or specified new or other more suitable blue light safety control standards and/or the new cognition of people to the related natural lawsL。
Corresponding spectral radiant power data can be obtained using a spectroradiometer test.
For the display screen with a rectangular or approximately rectangular display area, nine detection points (position detection points) are arranged in total for the detection points of the named nine-point detection method, the detection points are arranged in a vertically and horizontally aligned mode in 3 rows and 3 columns, each column and each row are provided with 3 detection points, vertical and horizontal connecting lines are in a rectangular grid shape, the distance between the outermost point in the horizontal direction and the corresponding side edge of the display screen can be w/9-w/10, the distance between the outermost point in the longitudinal direction and the corresponding side edge of the display screen can be h/9-h/10 (according to the actual situation, other distances can also be adopted, for example, the distance between the outermost point in the horizontal direction and the corresponding side edge of the display screen is w/3-w/4, the distance between the outermost point in the longitudinal direction and the corresponding side edge of the display screen is h/3-h/4, and the like), wherein w is the width of the display screen (display area), h is the height of the display screen (display area).
According to actual needs, a 25-point detection method or other detection point numbers can be adopted. The positions of the detection points can be determined in a manner of vertically and horizontally aligning in a rectangular grid shape, and other point selection manners in an adaptive manner can also be adopted, so that the conditions of the detection points can basically reflect the conditions of the display screen. For example, the detection points are aligned in rows and columns (for example, 25 points of the 25-point detection method are divided into 5 rows and 5 columns), one point is usually located at the midpoint of the display screen (the number of rows and the number of columns are both singular), the distances between adjacent points in the transverse direction are equal, the distances between adjacent points in the longitudinal direction are equal, the distances are usually left between the outermost points in the transverse direction and the longitudinal direction and the corresponding side edges of the display screen, and the distances can be the corresponding distances of the aforementioned nine-point detection method, and can also be set according to actual needs or specifications.
Aiming at a display (screen), on the basis of relevant test data and on the basis of certain viewing distance of human eyes or human ergonomics viewing distance, fitting the coordinates of each discrete point of color temperature and radiation accumulated time values corresponding to the limit value of blue light radiation hazard exemption grade RG0 under different color temperatures by adopting a polynomial fitting technology or other fitting technologies, and calculating to generate a new blue light radiation safety boundary curved surface of the color temperature and the radiation accumulated time of the display (screen). The area which is positioned on the blue light radiation safety boundary curved surface and is relative to the safety boundary curved surface and is smaller than the blue light radiation hazard exemption level limit value side is a safety region; and the area which is larger than the side of the blue light radiation hazard exemption level limit value and is relative to the safety boundary curved surface is an unsafe risk area.
In the case of display screen display or blue light radiation only, the display is not substantially different from the display screen, and the terms display (screen), display and display screen can all refer to various displays and display screens which are generally referred to and displayed by adopting related display modes, including independent displays, display screens, displays and display screens integrated or installed on other devices, and the like.
The safety zone/safety without blue light hazard risk or other similar expressions are limited to the safety of blue light hazard to human eyes relative to blue light radiation of a display during observation, and do not relate to the safety relative to other hazard modes or other hazard factors, and meanwhile, the safety evaluation is established on the existing research results or cognition of related hazards to common people, and does not relate to the possible hazard to specific individuals caused by individual difference and other factors.
The technical means disclosed by the invention can be combined arbitrarily to form a plurality of different technical schemes except for special description and the further limitation that one technical means is another technical means.
Claims (10)
1. A method for setting the safety boundary of blue light radiation with brightness, color temperature and radiation accumulation features that N sampling points N with different brightness and color temperature are sampled and the brightness L of each sampling point N is detectednSum color temperature CTnCalculating the blue-light-free danger of the blue light radiation power corresponding to each sampling point n according to the following formulaThreshold value t of harmful exposure timen，
PBn·tn＝EL
Based on the brightness L of each sample pointnColor temperature CTnAnd an exposure time threshold tnPerforming surface fitting of brightness L, color temperature CT and exposure time t to form a safe boundary surface or a safe boundary function of brightness, color temperature and exposure time under the condition of no blue light hazard:
L＝LRGO＝f(CT，t)
and/or
t＝tRGO＝g(L，CT)
And/or
CT＝CTRGO＝h(t，L)
Wherein, PBnThe blue light radiation power of the nth sampling point is N ═ 1,2, 3. t is tnBlue light radiation power P for nth sampling pointBnA corresponding exposure time threshold value without blue light hazard; eLA safety threshold for blue radiation energy; l is the brightness; CT is color temperature; and t is the exposure time.
2. The method as claimed in claim 1, wherein the blue light radiation safety margin is calculated according to the following formulaBn：
Wherein, Pλ(λ)nThe spectral radiant power related to the wavelength of the nth sampling point; b (lambda) is a blue light hazard weighting coefficient related to wavelength; λ is the wavelength.
3. The method of claim 1 wherein E is a threshold for the safe boundary setting of blue light radiation with integrated brightness, color temperature and radiationL＝0.220J。
4. The method as claimed in claim 1,2 or 3, wherein the blue light safety margin is determined or confirmed according to the safety margin curved surface, the area at the low value side of the boundary curved surface is a blue light safety margin, and the area at the high value side of the boundary curved surface is an area with risk of blue light damage.
5. The method as claimed in claim 1,2 or 3, wherein a three-dimensional coordinate system is established with the variables t, CT and L as coordinate axes, and a safety boundary curved surface CT-h (t, L) is drawn, and the safety region is located at the low-value side of the boundary curved surface, i.e. CT-h (t, L) and CT-CTmin、CT＝CTmax、L＝Lmin、L＝LmaxAnd t is 0, wherein LminFor minimum calibrated brightness of the display, LmaxFor maximum calibrated brightness of the display, CTminFor minimum calibrated color temperature, CT, of the displaymaxThe maximum calibrated color temperature of the display.
6. The method according to claim 5, wherein for any coordinate point (t, L, CT) determined as being in safe region, it is determined that there is no risk of blue light hazard, and if the coordinate point is in unsafe region, it is determined that there is a risk of blue light hazard.
7. The method according to claim 5, wherein the adjustment margin in any coordinate axis direction is determined according to the distance of the coordinate point from the boundary surface in any coordinate axis direction for any coordinate point (t, L, CT) located in the safety region.
8. The method as set forth in claim 1,2 or 3, wherein the central position of the display is used as the detecting point or the detecting center point when detecting the sampling point.
9. The method of claim 1,2 or 3, wherein the multi-point detection is performed by using a multi-point detection method when detecting the sampling points.
10. The method of claim 9, wherein after the detection by the multi-point detection method, the calculation of the safety boundary curved surface is performed according to the data of each detection point, and the confirmation of the safety region is performed according to any one of the following methods:
1) when the confirmation results of all the detection points are safe regions, confirming the detection points as safe regions, otherwise, confirming the detection points as unsafe regions;
2) when the confirmation results of at least a certain number of detection points are safe areas, confirming the detection points as safe areas, otherwise, confirming the detection points as unsafe areas;
3) and carrying out weighted average on each safety boundary curved surface obtained according to the data of each detection point, calculating to obtain an equivalent boundary curved surface of the display, and confirming the safety region according to the equivalent boundary curved surface.
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