CN113870750A - Method for setting blue light radiation safety boundary of color temperature and radiation accumulation - Google Patents
Method for setting blue light radiation safety boundary of 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 color temperature and radiation accumulation, under the maximum calibration brightness of a display, performing multi-point sampling between the maximum calibration color temperature and the minimum calibration color temperature of the display, detecting the central color temperature and the spectral radiant power of each sampling point, calculating the blue light radiant power of each sampling point and the exposure time threshold without the harm of blue light, and performing curve fitting on the color temperature of each sampling point and the exposure time threshold without blue light hazard to form a safety boundary curve or a safety boundary function of the color temperature and the radiation accumulation time of the display screen under the condition without blue light hazard, and judging or confirming a blue light safety region according to the safety boundary curve of the color temperature and the radiation accumulation time, wherein the region on the low value side of the boundary curve is a blue light safety region, and the region on the high value side of the boundary curve is a region with blue light hazard risk.
Description
Technical Field
The invention relates to a method for setting a blue light radiation safety boundary of 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 blue light radiation hazard exemption level (RG0 no risk level) critical safety boundary curve between the color temperature and the radiation accumulation time of an LED display (screen) and a safety region thereof is provided, integrated or implanted, the relation evaluation analysis of the change of the color temperature parameter influencing the blue light radiation intensity of the LED display (screen) along with the radiation accumulation time cannot be actively realized, the evaluation and regulation and control are more difficult to be carried out according to the blue light radiation hazard exemption level RG0 safety boundary curve influencing the visual health and the envelope safety region, the control of the damage risk degree of the retina of the human eye is greatly influenced by the blue light radiation measurement of the display (screen), 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 color temperature and radiation accumulation, so as to obtain a blue light radiation exemption level and a hazard risk boundary curve between the color temperature and the 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: a method for setting a blue light radiation safety boundary of color temperature and radiation accumulation is to sample N sampling points N (N is 1,2,3, … …, N) (which can be called color temperature sampling points) with different color temperatures, and detect each sampling pointColor temperature CT of sampling point nnCalculating the exposure time threshold 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 formula,
PBn·tn＝EL
color temperature CT for each sampling pointnAnd a corresponding exposure time threshold t without blue light hazardnPerforming curve fitting to form a relation curve or a functional relation (a functional relation of a boundary curve without blue light hazard) between the color temperature and the longest exposure time corresponding to the corresponding color temperature under the condition of no blue light hazard, or to form a safety boundary curve (a safety boundary curve or a boundary curve for short) between the color temperature (a color temperature for short) and the radiation accumulation time (or an exposure time) of a display screen or a safety boundary function (a safety boundary function or a boundary function for short) between the color temperature and the radiation accumulation time under the condition of no blue light hazard:
CT＝CTRGO＝f(t)
and/or
t＝tRGO＝g(CT)
The blue radiation power of each sample point n can be calculated according to the following formula:
wherein the content of the first and second substances,
PBnthe blue radiation power of the nth sample point, N is 1,2,3, … …, and N is the blue light weighted radiation power, which can be defined according to the above formula, and the common unit is: 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 according to currently recognized or appropriate standards, e.g., as currently practiced in the artIn the operative context, can be EL＝0.220J；
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);
CTRGOa color temperature threshold for no blue light hazard, a color temperature satisfying a functional relationship, as a function of exposure time, a 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, 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 () and g () are used to represent the corresponding functional relationships, passing the data L of each sample point nn、tnAnd (6) obtaining through fitting.
g () can be understood as the inverse function f of f ()-1() Or the inverse function f of f () may be employed-1(). However, f () and g () obtained by sample point data fitting may not be strictly inverse functions due to limitations of fitting accuracy or fitting method. However, the safety margin obtained by the above two functional relationships is equivalent with corresponding accuracy, and therefore, the curves determined by CT ═ f (t) and t ═ g (CT) can be referred to as the safety margin curve of the color temperature and the radiation accumulation time of the corresponding display (blue light safety margin curve), and can be replaced with each other.
Typically, the sampling point is located at the maximum calibrated color temperature CT of the displaymaxAnd minimum calibration color temperature CTminIn the color temperature range of (a).
In general, CT ═ CT should be included in the sampling pointsminAnd CT ═ CTmaxOr include CT ═ CTCTminAnd CT ═ CTmaxOf neighboring points of, wherein CTminFor minimum calibrated color temperature, CT, of the displaymaxThe maximum calibrated color temperature of the display.
The sampling points may be distributed substantially uniformly in terms of color temperature or in terms of radiant power.
The number of sampling points is usually not less than 3, for example, about 7.
The sampling of each sample point (detection of the correlation data) should be performed at the same brightness to avoid the influence of brightness variation. For example, it is preferable to perform the calibration at the maximum calibration luminance of the display or the display luminance set according to the actual situation, and the set display luminance for sampling may be determined by considering the luminance in the normal situation and considering the maximum calibration luminance according to the actual situation, for example, taking the average value of the normal luminance and the maximum calibration luminance.
Generally, sampling (detection) of each sample point is performed at the same luminance.
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.
F () and/or g () can be obtained using a polynomial function in a least squares method or other suitable fitting method, i.e. obtaining a safe boundary curve of color temperature versus radiation accumulation time.
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, f () and g () are both decreasing functions (see fig. 1 and fig. 2), and the absolute value of the derivative is usually also decreasing function. According to actual needs, the maximum exposure time without blue light hazard at the color temperature can be determined by taking the color temperature on the safety boundary curve as an independent variable, and the maximum color temperature without blue light hazard at the exposure time can also be determined by taking the exposure time on the safety boundary curve as an independent variable.
Either of the above analysis and determination may be performed by using one of the above two functional equations, for example, according to CT ═ f (t), the maximum color temperature (or referred to as a safe color temperature threshold) without blue light hazard at a certain exposure time may be determined, or the maximum exposure time (or referred to as a safe exposure time threshold) without blue light hazard at a certain color temperature may be determined.
The judgment or confirmation of the blue light safety region can be carried out according to the safety boundary curve of the color temperature and the radiation accumulation time, and the blue light safety region is positioned at the low value side of the boundary curve (when t is fixed, CT is less than CTRGOSide, or, CT, at a timing, t < tRGOSide) is a blue light safety region (region without blue light hazard, or RG0 region), and is located on the high-value side of the boundary curve (where t is constant, CT > CTRGOSide, or, CT, at a timing, t > tRGOSide) is an area where there is a risk of blue light hazard (unsafe area), corresponding to an area of RG1 or higher risk.
In general, a boundary curve (when t is constant, CT ═ CT) may be usedRGOOr, CT is a fixed time, t is t ═ tRGO) As or as a secure area.
For example, the safety margin curve CT ═ f (t) (that is, CT ═ CT may be drawn in a rectangular coordinate system with t as the horizontal axis and CT as the vertical axisRGOCurve), for a particular display, CTmin≤CT≤CTmaxWherein CTminFor minimum calibrated color temperature, CT, of the displaymaxFor the maximum calibrated color temperature of the display, the safety range is called CT ═ f (t), CT ═ CTmin、CT＝CTmaxAnd a region surrounded by t ═ 0 and located on the left side of the boundary curve, and the coordinates of the four corners of the region are (0, CT) respectivelymin)、(0，CTmax)、(tmin，CTmax) And (t)max，CTmin) Wherein t isminBy CTmax＝f(tmin) Determining, i.e. when CT is equal to CTmaxMaximum exposure time without blue light hazard in case ofmaxBy CTmin＝f(tmax) Determining, i.e. when CT is equal to CTminMaximum exposure time without blue light hazard in the case.
For example, the safety margin curve t may be plotted in rectangular coordinates with CT as the horizontal axis and t as the vertical axis (or equivalently, t ═ f)-1(CT)) (i.e., t-t ═ t)RGOCurve), for a particular display, CTmin≤CT≤CTmaxWherein CTminFor minimum calibrated color temperature, CT, of the displaymaxFor the maximum calibrated color temperature of the display, the safety range is referred to as t ═ g (ct) (or t ═ f)-1(CT))、CT＝CTmin、CT＝CTmaxAnd a region surrounded by t ═ 0 and located below the boundary curve, and the coordinates of the four corners of the region are (CT)min，0)、(CTmin，tmax)、(CTmax0) and (CT)max，tmin) Wherein t isminFrom tmin＝g(CTmax) (or t)min＝f-1(CTmax) Is determined, i.e. at CT ═ CTmaxMaximum exposure time without blue light hazard in case ofmaxFrom tmax＝g(CTmin) (or t)max＝f-1(CTmin) Is determined, i.e. at CT ═ CTminMaximum exposure time without blue light hazard in the case.
When a coordinate point (coordinate values on a CT axis and a t axis are respectively the coordinate point of the corresponding color temperature and the coordinate point of the corresponding exposure time) formed by the color temperature and the exposure time (viewing time) of the display screen is located in a safe area, the risk of blue light hazard is judged to be absent, and when the coordinate point formed by the color temperature and the exposure time of the display screen falls into the unsafe area, the risk of blue light hazard is judged to be present.
When the coordinate point is in the safety region, or in other words, for the coordinate point (the coordinate point formed by the color temperature of the display screen and the apparent exposure time, or the coordinate point formed by the color temperature and the exposure time) in the safety region, the adjustment allowance (the adjustment allowance of the parameter corresponding to any coordinate axis) in the coordinate axis direction can be judged according to the distance between the coordinate point and the boundary curve in any coordinate axis direction, that is, under the condition that other relevant parameters are not changed, the parameter is allowed to be increased at most. For exampleAccording to the distance d between the coordinate point and the boundary curve in the t coordinate axis directiontIt can be judged that at the corresponding color temperature, the exposure time (viewing time) can be prolonged by d at most on the basis of the original set timetIf the time longer than the original set time exceeds dtThen there is a risk of blue light hazard. For another example, the distance d from the boundary curve in the direction of the CT coordinate axis is determined according to the coordinate pointsCTIt 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 in the corresponding 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.
When detecting a sampling point (color temperature sampling point), the central color temperature of the display screen and other parameters (or variables) (if necessary) or data 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 actual needs, a multi-point detection method (for example, a nine-point detection method and a twenty-five-point detection method) can be adopted for multi-point detection, and a plurality of points are selected as detection points (or called position detection points) on the display screen according to detection rules for detection.
After the detection by the multipoint detection method, a safety boundary curve is calculated based on data at each detection point, and the safety region 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 this case, the number of detection points required to confirm as the safe area or the number of detection points required to confirm as the unsafe area may be divided into the minimum number of detection points for the safe area or the minimum number of detection points for the unsafe area according to the actual situation, when the confirmation results 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) are the safe area, the safe area is confirmed, otherwise, the unsafe area is confirmed.
3) The method comprises the steps of carrying out weighted average on each safety boundary curve (exposure time threshold) obtained according to data of each detection point, calculating and obtaining an equivalent boundary curve (exposure time threshold) of the display, and confirming (judging) a safety region according to the equivalent boundary curve in the same way as the confirmation according to the boundary curve.
For example, for a nine-point test (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:
calculating and fitting a corresponding safety boundary curve according to the detection data of each detection point:
ti＝tRGOi＝gi(CTi)
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 exposure time on the safety boundary curve according to the detection data of the detection point i, and the color temperature CT detected for the detection point iiA function of (a); gi() A security boundary function calculated from detection data of a detection point i is shown, where i is 0,1,2,3,4,5,6,7, and 8, which is the number or sequence number of the detection point, detection point 0(i is 0) is a detection point located at the center of the display screen, detection points 1 to 4(i is 1,2,3, and 4) are respectively detection points at the middle of the outer sides in the lateral direction and the longitudinal direction, and detection points 5 to 8 are respectively detection points at the four corners of the outer sides.
According to each examinationExposure time threshold t obtained by detection data of measuring 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 margin function (safety margin curve), or color temperature CT detected by exposure time and central region (detection point 0) of display screen0Relevant safety margin function (safety margin curve):
or
Wherein, tRGOvIs an equivalent exposure time threshold;
αithe 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, i.e., αi＝CTi/CT0. Can also be regarded as alpha0＝1。
gv() Representing the corresponding function.
αiCan be obtained by calculation according to actual detection data. When multiple detections are performed (e.g., multiple color temperature samples are set), α can be calculated by arithmetic mean or weighted averagei. For example, one convenient and feasible way is to perform color temperature detection at maximum, intermediate and minimum powers of the display for viewing the range of interest, obtain maximum, minimum and intermediate color temperatures for each detection point corresponding to the maximum, intermediate and minimum powers of the display, divide the sum of the maximum, minimum and intermediate color temperatures for each detection point by 4 as the value for αiCalculated color temperature average value as CT according to the color temperature average value of corresponding detection pointiCalculating alphai。
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 done at the same brightness (e.g., maximum calibrated brightness of the display) and other relevant conditions. In addition to the 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 risk of the blue light hazard 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 of the blue light radiation damage exemption level RG0 of the display (screen) with a certain size under a certain viewing distance and certain brightness and different color temperatures, calculate the blue light radiation exemption level and the damage risk boundary curve and the safety region between the color temperature and the radiation accumulation time of the display (screen) based on LEDs and the like, judge whether the actual or predicted viewing has the blue light damage risk and the allowed adjustment allowance, and can be applied to 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 curve and a safety region between the display (screen) color temperature and radiation accumulation time influence factors generated through fitting calculation, is convenient for warning 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 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 curve and safety zone in a coordinate mode;
FIG. 2 is a schematic diagram of a boundary curve and a safety zone in another coordinate system;
FIG. 3 is a B (λ) graph (λ -B (λ) curve) to which the present invention relates;
fig. 4 is a distribution diagram of detection points in the nine-point detection method according to the present invention.
Detailed Description
Referring to fig. 1-4, the present invention uses polynomial fitting technology or other fitting technology to fit the coordinates of each discrete point of the color temperature and radiation accumulation time value corresponding to the limit value of the blue light radiation hazard exemption level RG0 under different color temperatures, and calculates and generates a new blue light radiation safety boundary curve (see fig. 1 and fig. 2) of the color temperature and radiation accumulation time of the display (screen), which is located on the blue light radiation safety boundary curve and below or on the left side of the curve, and is a safety boundary region (the shaded region in fig. 1 and fig. 2) of each point of the numerical region less than or equal to the limit value of the blue light radiation hazard exemption level; and the numerical value area of each point which is positioned above or on the right side of the blue light radiation safety boundary curve and is greater than the blue light radiation hazard exemption level limit value is an unsafe risk boundary area.
The coordinate system used may be as shown in fig. 1, and includes Color Temperature on abscissa (CT, unit: K) and radiation accumulation Time on ordinate (t, unit: h). In the graph shown in FIG. 1, CT1、CTNRespectively the minimum and maximum calibrated color temperature values of the display; t is t1、tNWhen the color temperature values are respectively calibrated to the maximum and minimum of the display, the minimum and maximum values of the radiation accumulation time values corresponding to the boundary curve, that is, the threshold value of the accumulation time at the corresponding color temperature, and the radiation accumulation time value at the origin of the coordinate system is 0(t ═ t-00). The lower part of the boundary curve is composed of a boundary Curve and (CT)1,t0)、(CTN,t0)、(CTN,t1)、(CT1,tN) The enclosed area is a safe area (a shaded area in the figure); above the curve is a dangerous area (an area at risk of blue light hazard, or unsafe area).
The coordinate system used can also be as shown in fig. 2, comprising the abscissa t and the ordinate color temperature CT. In the graph shown in FIG. 2, CT1、CTNRespectively the minimum and maximum calibrated color temperature values of the display; t is t1、tNWhen the color temperature values are respectively the maximum and minimum calibration color temperature values of the display, the radiation accumulation time value of the origin of the coordinate system is 0(t is t) and the radiation accumulation time value of the corresponding radiation accumulation time value on the curve is the minimum and maximum values00). The left side of the curve is composed of a boundary curve, (t)0,CT1)、(tN,CT1)、(t1,CTN)、(t0,CTN) The enclosed area (the shaded area in the figure) is a safe area; above the curve is the danger zone.
As can be seen from a comparison between fig. 1 and fig. 2, the curves in the two coordinate modes are gradually descending concave curves, and the physical meaning of any point on the curves is the coordinate of each discrete point of the color temperature and radiation accumulation time value corresponding to the limit value of the blue light radiation hazard-exemption level RG0 reached by the display (screen).
The fitting of the safety margin curve can be performed using the following steps:
1) obtaining a judgment formula about the limit energy of the blue light radiation hazard exemption grade RG 0;
2) obtaining radiation accumulation time corresponding to the limit value of the display (screen) reaching the blue light radiation hazard exemption level RG0 under different color temperature values under the condition that the certain display has parameters such as a certain test distance, certain brightness and the like according to the judgment formula;
3) after the radiation accumulation time corresponding to the exempt level limit value of the blue light hazard of the display (screen) under different color temperature values is obtained, CT is carried out on the different color temperature valuesn(unit: K) and corresponding radiation accumulation time value tnDiscrete points of (unit: h), i.e. (CT)1,tN)、(CT2,tN-1)……(CTN,t1) (N-1, 2, … …, N), a new mathematical fit calculation is performed, i.e.A safety boundary curve of color temperature versus radiation accumulation time for blue radiation hazard assessment between different color temperature values and radiation accumulation times for the display (screen) can be obtained.
4) Drawing boundary curve and four discrete points (CT)1,t0)、(CTN,t0)、(CTN,t1)、(CT1,tN) (shown in FIG. 1), or four discrete points (t)0,CT1)、(t0,CTN)、(t1,CTN)、(tN,CT1) (shown in fig. 2) a safety area (shaded area in the figure).
When the safety curve is calculated or fitted according to the data of each detection point, the characteristics of the obtained safety curve are similar to those of fig. 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-:
wherein L isBWeighting radiance (W.m) for blue light-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) The use scene of medical and civil displays (screens) 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), high height compared with the illuminating lampLuminance (300-2Or 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 are arranged in total by the nine-point detection method, the detection points are arranged in 3 rows and 3 columns in a vertically and horizontally aligned mode, each column and each row have 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), where w is the width of the display screen (display area) and 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 certain viewing distance of human eyes or human ergonomics viewing distance and relevant test data, fitting the coordinates of each discrete point of a color temperature and radiation accumulated time value corresponding to the limit value of the blue light radiation hazard-exemption grade RG0 under different color temperatures by adopting a polynomial fitting technology or other fitting technologies according to the test data, and calculating to generate a new blue light radiation safety boundary curve of the color temperature and the radiation accumulated time of the display (screen) (shown in figures 1 and 2). The numerical value area of each point which is positioned on and below the curve line of the blue light radiation safety boundary or is smaller than the blue light radiation hazard exemption level limit value is a safety area; and the numerical area of each point which is positioned above the blue light radiation safety boundary curve or is greater than the blue light radiation hazard exemption level limit value is an unsafe risk area. The safety region (as shown by the hatched region in the figure) formed by four dots is shown in fig. 2.
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 blue light radiation safety boundary of color temperature and radiation accumulation is characterized in that N sampling points N with different color temperatures are sampled, and color temperature CT of each sampling point N is detectednCalculating the exposure time threshold without blue light hazard corresponding to the blue light radiation power of each sampling point n according to the following formula,
PBn·tn＝EL
color temperature CT for each sampling point nnAnd a corresponding exposure time threshold t without blue light hazardnPerforming curve fitting to form a safety boundary curve or a safety boundary function of the color temperature and the radiation accumulation time of the display screen under the condition of no blue light hazard:
CT＝f(t)
and/or
t＝g(CT)
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; CT is color temperature; and t is the exposure time.
2. The method of claim 1, wherein the blue light radiation power of each sample point n is calculated according to the following formula:
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 the color temperature and radiation accumulation blue light radiation safety marginL＝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 a safety margin curve of color temperature and radiation accumulation time, the region at the low value side of the margin curve is a blue light safety margin, and the region at the high value side of the margin curve is a region at risk of blue light damage.
5. The method of claim 4, wherein a safety margin curve CT (f (t)) is plotted in a rectangular coordinate system with t as the horizontal axis and CT as the vertical axis, and the safety margin is located at the left side of the margin curve and is represented by CT (f (t)) and CT (CT) respectivelymin、CT＝CTmaxAnd t ═ 0, where CTminFor minimum calibrated color temperature, CT, of the displaymaxThe maximum calibrated color temperature of the display.
6. The method of claim 4, wherein a safety margin curve t g (L) is plotted in a rectangular coordinate with CT as horizontal axis and t as vertical axis, and the safety margin is located below the safety margin curve and is t g (CT) or CTmin、CT＝CTmaxAnd t ═ 0, where CTminFor minimum calibrated color temperature, CT, of the displaymaxThe maximum calibrated color temperature of the display.
7. The method of claim 4, wherein the risk of blue light damage is determined to be absent when the coordinate point of the color temperature and the exposure time of the display screen is located in the safe area, and the risk of blue light damage is determined to be present when the coordinate point of the color temperature and the exposure time of the display screen is located in the unsafe area.
8. The method of claim 4, wherein for a coordinate point in the safety region, the adjustment margin of the parameter corresponding to any coordinate axis is determined according to the distance of the coordinate point from the boundary curve in any coordinate axis direction.
9. The method of claim 1,2 or 3, wherein the central position of the display is used as a detection point or a center point of the detection, or the multi-point detection is used for multi-point detection.
10. The method of claim 9, wherein after the detection by the multi-point detection method, the safety margin curve is calculated according to the data of each detection point, and the safety region is confirmed 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 curve obtained according to the data of each detection point, calculating to obtain an equivalent boundary curve of the display, and confirming the safety region according to the equivalent boundary curve.
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