KR102711188B1 - Control design for perceptually uniform color-tuning - Google Patents

Abstract

Various embodiments include devices and methods for controlling a device for color-tuning an array of light emitting diodes (LEDs). In one particular example, a control device for color-tuning an array of light emitting diodes (LEDs) for perceptually uniform color tuning is disclosed. The device includes a correlated color temperature (CCT) control device that is adjustable by an end user to a desired color temperature of the LED array and generates an output signal corresponding to the desired color temperature. A storage device is electrically coupled to the CCT control device to correlate a mechanical range of movement of the CCT control device to provide substantially uniform increases in perceptual CCT values from the LED array based on a set of N predetermined values. Other devices and methods are described.

Description

{CONTROL DESIGN FOR PERCEPTUALLY UNIFORM COLOR-TUNING}

claim of priority

This application claims the benefit of European Patent Application No. 19207130.6, filed Nov. 5, 2019, entitled "CONTROL DESIGN FOR PERCEPTUALLY UNIFORM COLOR-TUNING," which claims priority to U.S. Utility Patent Application No. 16/528,108, filed Jul. 31, 2019, entitled "CONTROL DESIGN FOR PERCEPTUALLY UNIFORM COLOR-TUNING," each of which is incorporated herein by reference in its entirety.

Technical field

The subject matter disclosed herein relates to color tuning of one or more light emitting diodes (LEDs) or LED arrays, including lamps operating substantially in the visible portion of the electromagnetic spectrum. More specifically, the disclosed subject matter relates to techniques that enable, for example, user-controlled design methods and devices to create a perceptually uniform color tuning experience of one or more LEDs or LED arrays.

Light-emitting diodes (LEDs) are commonly used in a variety of lighting applications. The color appearance of an object is determined in part by the spectral power density (SPD) of the light illuminating the object. For a human viewer, the SPD is the relative intensity of the light at various wavelengths within the visible light spectrum. However, other factors can also affect color appearance. Additionally, both the correlated color temperature (CCT) of the LED and the distance of the temperature of the LED along the CCT from the black-body line (also known as the black-body locus or Planckian locus) can affect the human perception of the object.

There are currently two main technologies for color tuning (e.g. white tuning) of LEDs. The first technology is based on white LEDs of two or more CCTs. The second technology is based on a combination of red/green/blue/amber colors. The first technology simply does not have the ability to tune the LEDs in the D _uv direction. In the second technology, color tuning capability is rarely provided as an available feature.

The information described in this section is provided to provide context to the subject matter disclosed below to those of ordinary skill in the art and should not be considered admitted prior art.

Figure 1 illustrates a portion of the International Commission on Illumination (CIE) chromaticity chart, including the blackbody line (BBL).
FIG. 2a illustrates a chromaticity diagram with approximate chromaticity coordinates of colors for typical red (R), green (G), and blue (B) LEDs on the diagram, including BBL;
FIG. 2b illustrates a modified version of the chromaticity diagram of FIG. 2a having approximate chromaticity coordinates for desaturated R, G, and B LEDs close to a BBL, in accordance with various embodiments of the disclosed subject matter, wherein the desaturated R, G, and B LEDs have a color rendering index (CRI) of approximately 90+ and within a defined color temperature range.
FIG. 2c illustrates a modified version of the chromaticity diagram of FIG. 2a having approximate chromaticity coordinates for desaturated R, G, and B LEDs close to the BBL, in accordance with various embodiments of the disclosed subject matter, wherein the desaturated R, G, and B LEDs have a color rendering index (CRI) of approximately 80+ within a wider defined color temperature range than the desaturated R, G, and B LEDs of FIG. 2b.
FIG. 3 illustrates a prior art color-tuning device that requires a hard-wired flux control device and a separate hard-wired CCT control device.
FIG. 4 is an exemplary embodiment of a graph showing CCT values as a function of control input values and illustrating the difference between two user-controlled designs according to various embodiments of the disclosed subject matter.
FIG. 5 illustrates an exemplary embodiment of a series of selected control points along a BBL according to various embodiments of the disclosed subject matter.
Figure 6 illustrates an exemplary method process flow diagram for determining control device points for a CCT adjustment curve.
FIG. 7 illustrates a simplified block diagram of an exemplary form of a machine in a computing system on which a set of instructions may be executed to cause the machine to perform any one or more of the methodologies and operations discussed herein (e.g., CCT next step decisions).

The disclosed subject matter will now be described in detail with reference to certain general specific embodiments thereof, as illustrated in the various drawings of the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the disclosed subject matter. However, it will be apparent to one skilled in the art that the disclosed subject matter may be practiced without some or all of these specific details. In other instances, well-known process steps or structures have not been described in detail so as not to obscure the disclosed subject matter.

Examples of different light illumination systems and/or light emitting diode (LED) implementations and means for controlling these implementations will now be more fully described with reference to the accompanying drawings. These examples are not mutually exclusive, and features found in one example may be combined with features found in one or more other examples to achieve additional implementations. Accordingly, it will be appreciated that the examples depicted in the accompanying drawings are provided for illustrative purposes only and that they are not intended to limit the present disclosure in any way. Like numbers generally refer to like elements throughout.

It will also be appreciated that the terms first, second, third, etc. may be used herein to describe various elements. However, these elements should not be limited by these terms. These terms may be used to distinguish one element from another. For example, without departing from the scope of the disclosed subject matter, a first element could be referred to as a second element and a second element could be referred to as a first element. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

When an element is said to be "connected" or "coupled" to another element, it will also be understood that it may be directly connected or coupled to the other element, and/or connected or coupled to the other element via one or more intervening elements. Conversely, when an element is said to be "directly connected" or "directly coupled" to another element, there are no intervening elements between the element and the other element. It will be understood that these terms are intended to encompass different orientations of the elements in addition to any orientation depicted in the drawings.

Relative terms, such as "below," "above," "upper," "lower," "horizontal," or "vertical," may also be used herein to describe one element, region, or area in relation to another element, region, or area, as illustrated in the drawings. One of ordinary skill in the art will appreciate that such terms are intended to encompass different orientations of the device in addition to the orientation depicted in the drawings. Furthermore, whether the LEDs, LED arrays, electrical components, and/or electronic components are housed on one, two, or more electronic device boards, or in one or multiple physical locations, may also depend on design constraints and/or the particular application.

Semiconductor-based light-emitting devices, or optical power-emitting devices, such as those that emit ultraviolet (UV) or infrared (IR) light power, are among the most efficient light sources available today. These devices may include light-emitting diodes, resonant-cavity light-emitting diodes, vertical-cavity laser diodes, edge-emitting lasers, or the like (referred to herein simply as LEDs). Because of their small size and low power requirements, LEDs can be attractive candidates for many different applications. For example, they can be used as light sources for handheld battery-powered devices such as cameras and cellular phones (e.g., flashlights and camera flashes). LEDs can also be used for, for example, automotive lighting, heads-up display (HUD) lighting, horticulture lighting, street lighting, video torches, general lighting (e.g., home, store, office and studio lighting, theater/stage lighting, and architectural lighting), augmented reality (AR) lighting, virtual reality (VR) lighting, display backlights, and IR spectroscopy. A single LED may provide less bright light than an incandescent light source, and therefore multi-junction devices or arrays of LEDs (such as monolithic LED arrays, micro LED arrays, etc.) may be used for applications where enhanced brightness is desirable or required.

In addition to illuminating objects, as well as in a variety of environments where LED-based lamps (or related lighting devices) are used for general lighting, it may be desirable to control aspects of the color temperature of the LED-based lamps (or a single LED-based lamp) in addition to the relative luminance (e.g., luminous flux) of the lamps. Such environments may include, for example, retail locations, as well as hospitality locations such as restaurants and the like. In addition to the correlated color temperature (CCT), another lamp metric is the lamp's color rendering index (CRI). The CRI is defined by the International Commission on Illumination (CIE) and provides a quantitative measure of the ability of any light source (including LEDs) to accurately represent colors on a variety of objects compared to an ideal or natural light source. The highest possible CRI value is 100. Another quantitative lamp metric is D _uv . D _uv is a metric defined, for example, in CIE 1960, to express the distance of the color point to the BBL. It is a positive value if the color point is above the BBL and a negative value if the color point is below the BBL. The color points above the BBL appear as green in color and the color points below the BBL appear as pink in color. The disclosed subject matter provides a device for controlling color temperature (CCT and D _uv ) with a smooth and visually pleasing adjustment experience. As described herein, color temperature is related to both CCT and D _uv in color adjustment applications.

As is known in the art, the forward voltage of direct color LEDs decreases with increasing dominant wavelength. These LEDs can be driven, for example, with multi-channel DC-DC converters. Advanced phosphor-converted color LEDs targeting high efficacy and CRI have been created, offering new possibilities for correlated color temperature (CCT) tuning applications. Some of the advanced color LEDs have desaturated color points and can be blended to achieve white with 90+ CRI over a wide CCT range. Other LEDs having 80+ CRI implementations, or even 70+ CRI implementations (or even lower CRI values), can also be used with the disclosed subject matter. These possibilities utilize LED circuits that realize, increase, or maximize this potential. At the same time, the control devices described herein are compatible with single-channel constant current drivers to facilitate market adoption.

An advantage of the disclosed subject matter over the prior art is that the desaturated red-green-blue (RGB) LED approach, described in detail below, can produce tunable light not only on the BBL but also off the BBL, for example on an isothermal CCT line (described below), while maintaining a high CRI. In comparison, various other prior art systems utilize a CCT approach in which the tunable color points lie on a straight line between two of the LEDs' primaries (e.g., R-G, R-B, or G-B).

Overall, color control is an essential part of human-centric lighting. Advanced LED-based systems, such as the desaturated RGB LED approach and associated control technologies, offer lighting specifiers and end users new possibilities in lighting control. In addition to CCT control over a wide range, users will be able to change the tint of the white light along the iso-CCT line as the end user deems satisfactory. For example, the Lumileds® proprietary Luxeon® Fusion system, with its wide range of adjustments on a single platform, is an ideal candidate for a variety of color-tunable applications. (Lumileds® Luxeon® Fusion systems are manufactured by Lumileds LLC, 370 West Trimble Road, San Jose, CA 95131, USA.) One aspect of human-centric lighting is the ability to simultaneously vary correlated color temperature and light intensity. The disclosed subject matter is directed to a user-controlled design paradigm that creates a perceptually uniform color control experience.

Referring now to FIG. 1 , a portion of the Commission Internationale de l'Eclairage (CIE) chromaticity chart (100) is illustrated, which includes a black body line (BBL) (101) (also known as the Planckian locus) that forms the basis for understanding various embodiments of the subject matter disclosed herein. The BBL (101) depicts chromaticity coordinates for black body radiators at various temperatures. It is generally agreed that, for most lighting situations, light sources should have chromaticity coordinates that are on or near the BBL (101). Various mathematical procedures known in the art are utilized to determine the "nearest" black body radiator. As noted above, this common lamp specification parameter is referred to as the correlated color temperature (CCT). A useful and complementary way to further describe chromaticity is provided by the D _uv value, which is an indication of the extent to which the chromaticity coordinates of a lamp lie above the BBL (101) (positive D _uv value) or below the BBL (101) (negative D _uv value).

A portion of the color chart is shown to include a number of isotherms (117). Any color point on an isotherm (117) has a constant CCT, even if each of these lines is not on the BBL (101). For example, a first isotherm (117A) has a CCT of 10,000 K, a second isotherm (117B) has a CCT of 5,000 K, a third isotherm (117C) has a CCT of 3,000 K, and a fourth isotherm (117D) has a CCT of 2,200 K.

With continued reference to FIG. 1, the CIE chromaticity chart (100) also depicts a number of ellipses representing MacAdam ellipses (MAEs) (103) centered at the BBL (101) and extending one step (105), three steps (107), five steps (109), or seven steps (111) from the BBL (101). The MAE is based on psychological research and defines a region on the CIE chromaticity diagram that includes all colors that are indistinguishable to a typical observer from the color at the center of the ellipse. Thus, each of the MAE steps (105-111) (one step to seven steps) appears to a typical observer as substantially the same color as the color at the center of each of the MAEs (103). A series of curves (115A, 115B, 115C, and 115D) represent substantially equal distances from the BBL (101) and are associated with D _uv values of, for example, +0.006, +0.003, 0, -0.003, and -0.006, respectively.

Now, referring to FIG. 2A, and still referring to FIG. 1, FIG. 2A illustrates a chromaticity diagram (200) having approximate chromaticity coordinates of colors for typical coordinate values (as indicated by the x-y scale of the chromaticity diagram (200)) for a red (R) LED at coordinate (205), a green (G) LED at coordinate (201), and a blue (B) LED at coordinate (203). FIG. 2A illustrates an example chromaticity diagram (200) for defining a wavelength spectrum of a visible light source, according to some embodiments. The chromaticity diagram (200) of FIG. 2A is only one way to define the wavelength spectrum of a visible light source, and other suitable definitions are known in the art and may also be used in various embodiments of the disclosed subject matter described herein.

A convenient way to specify a portion of the chromaticity diagram (200) is through a set of equations in the x-y plane, each of which has a locus of solutions that defines a line on the chromaticity diagram (200). The lines may intersect to designate a particular region, as described in more detail below with reference to FIG. 2b. As an alternative definition, a white light source may emit light corresponding to light from a blackbody source operating at a given color temperature.

The chromaticity diagram (200) also illustrates a BBL (101) as described above with reference to FIG. 1. Each of the three LED coordinate locations (201, 203, 205) are CCT coordinates for "fully saturated" LEDs of the respective colors green, blue, and red. However, if "white light" were produced by combining given ratios of the R, G, and B LEDs, the CRI of such a combination would be extremely low. Typically, a CRI of about 90 or greater is desirable in the aforementioned environments, such as retail or hospitality environments.

FIG. 2b illustrates a modified version of the chromaticity diagram (200) of FIG. 2a having approximate chromaticity coordinates for desaturated R, G, and B LEDs close to a BBL, in accordance with various embodiments of the disclosed subject matter, wherein the desaturated R, G, and B LEDs have a color rendering index (CRI) of approximately 90+ and within a defined color temperature range.

However, the chromaticity diagram (250) of FIG. 2b shows approximate chromaticity coordinates for desaturated (pastel) R, G, and B LEDs close to the BBL (101). Coordinate values (as indicated on the x-y scale of the chromaticity diagram (250)) are shown for a desaturated red (R) LED at coordinate (255), a desaturated green (G) LED at coordinate (253), and a desaturated blue (B) LED at coordinate (251). In various embodiments, the color temperature range of the desaturated R, G, and B LEDs can be in the range of about 1800 K to about 2500 K. In other embodiments, the desaturated R, G, and B LEDs can be in the color temperature range of, for example, about 2700 K to about 6500 K. In further embodiments, the desaturated R, G and B LEDs can have a color temperature range of from about 1800 K to about 7500 K. In further embodiments, the desaturated R, G and B LEDs can be selected to have a wide range of color temperatures. As mentioned above, the color rendering index (CRI) of a light source does not represent the apparent color of the light source; that information is given by the correlated color temperature (CCT). Thus, CRI is a quantitative measure of the ability of a light source to faithfully reveal the colors of various objects as compared to an ideal or natural light source.

In a particular exemplary embodiment, a triangle (257) formed between the coordinate values for each of the desaturated R, G, and B LEDs is also illustrated. The desaturated R, G, and B LEDs are formed (e.g., by a mixture of phosphors and/or a mixture of materials to form LEDs as known in the art) so as to have coordinate values close to the BBL (101). As a result, the coordinate locations of each of the desaturated R, G, and B LEDs have a CRI of greater than or equal to about 90, as outlined by the triangle (257), and an approximately tunable color temperature range of, for example, from about 2700K to about 6500K. Therefore, the selection of a correlated color temperature (CCT) can be selected in the color adjustment applications described herein such that all combinations of the selected CCTs all result in a lamp having a CRI of greater than or equal to 90. Each of the desaturated R, G and B LEDs can comprise a single LED or an array (or group) of LEDs, each LED in the array or group having the same or similar desaturated color as the other LEDs in the array or group. A combination of one or more desaturated R, G and B LEDs comprises a lamp.

FIG. 2c illustrates a modified version of the chromaticity diagram (200) of FIG. 2a having approximate chromaticity coordinates for desaturated R, G, and B LEDs close to a BBL, in accordance with various embodiments of the disclosed subject matter, wherein the desaturated R, G, and B LEDs have a color rendering index (CRI) of approximately 80+ and are within a wider defined color temperature range than the desaturated R, G, and B LEDs of FIG. 2b.

However, the chromaticity diagram (270) of FIG. 2c shows approximate chromaticity coordinates for desaturated R, G and B LEDs arranged further from the BBL (101) than the desaturated R, G and B LEDs of FIG. 2b. Coordinate values (as indicated on the x-y scale of the chromaticity diagram (270)) are shown for a desaturated red (R) LED at coordinate (275), a desaturated green (G) LED at coordinate (273), and a desaturated blue (B) LED at coordinate (271). In various embodiments, the color temperature range of the desaturated R, G and B LEDs can be in the range of about 1800 K to about 2500 K. In other embodiments, the desaturated R, G and B LEDs can have a color temperature range of about 2700 K to about 6500 K. In still other embodiments, the desaturated R, G and B LEDs can have a color temperature range of about 1800 K to about 7500 K.

In a particular exemplary embodiment, a triangle (277) formed between the coordinate values for each of the desaturated R, G, and B LEDs is also illustrated. The desaturated R, G, and B LEDs are formed (e.g., by a mixture of phosphors and/or a mixture of materials for forming LEDs as known in the art) so as to have coordinate values close to the BBL (101). Accordingly, the coordinate locations of each of the desaturated R, G, and B LEDs have a CRI of greater than or equal to about 80, as outlined by the triangle (277), and an approximately tunable color temperature range of, for example, about 1800K to about 7500K. Since the color temperature range is greater than the range illustrated in FIG. 2B, the CRI is correspondingly reduced to greater than or equal to about 80. However, those skilled in the art will recognize that the desaturated R, G and B LEDs can be produced to have individual color temperatures anywhere within the chromaticity diagram. Therefore, the selection of correlated color temperatures (CCTs) can be selected in the color control applications described herein such that all combinations of the selected CCTs result in a lamp having a CRI greater than or equal to 80. Each of the desaturated R, G and B LEDs can comprise a single LED or an array (or group) of LEDs, each LED within the array or group having the same or similar desaturated color as the other LEDs within the array or group. A combination of one or more desaturated R, G and B LEDs comprises the lamp.

FIG. 3 illustrates a prior art color adjustment device (300) using a hard-wired flux control device (301) and a separate hard-wired CCT control device (303). The flux control device (301) is coupled to a single channel driver circuit (305) and the CCT control device (303) is coupled to a combination LED driver circuit/LED array (320). The combination LED driver circuit/LED array (320) can be a current driver circuit, a PWM driver circuit, or a hybrid current driver/PWM driver circuit. Each of the flux control device (301), the CCT control device (303), and the single channel driver circuit (305) are located at the customer facility (310), and all devices should be installed in compliance with applicable national and local codes that generally govern high voltage circuits. The combination LED-drive circuit/LED array (320) is typically located remotely (e.g., several meters to tens of meters or more) from the customer facility (310). As a result, both the initial purchase price and the installation cost can be substantial.

Consequently, in conventional color-tunable systems operating from a single-channel constant current driver, two control inputs are typically required, one for flux control (e.g., luminous flux or dimming) and one for color adjustment. The control inputs can be realized by electromechanical devices such as, for example, linear or rotary sliders, DIP switches, or standard 0 V to 10 V dimmers.

FIG. 4 is an exemplary embodiment of a graph (400) showing a CCT value as a function of a control input value and illustrating the difference between two user-controlled designs according to various embodiments of the disclosed subject matter. The results of the two user-controlled designs are shown as two graphical curves. The user-controlled device used to adjust the CCT value can be the same or similar to the CCT control device (303) of FIG. 3, with appropriate modifications for the second user-controlled design as described below.

As is well known to those skilled in the art, CCT is often used to represent the chromaticity of a white light source. However, as mentioned above, chromaticity is a two-dimensional value, and the other dimension, the distance from the BBL, is often omitted. D _uv is defined in the American National Standards Institute (ANSI) standard. Therefore, the two chromaticity coordinates (x, y) or (u', v') do not intuitively carry color information. CCT and D _uv carry complete color information.

Also, a unit step in CCT values does not result in a uniform perception of color. This is evidenced by Table 1 below, taken from ANSI C78.377 (2015). The tolerance of CCT becomes progressively larger as the CCT values increase. As a result, if a user control that represents CCT values is linearly mapped to CCT values, most of the visible changes occur during the beginning of the CCT control device range (e.g., at the beginning of the slider range) and are therefore not linear as expected.

[Table 1]

Referring again to FIG. 4, the non-uniform mapping curve (403) maps evenly spaced CCT values based on a given user control input. The user control input is associated with a desired CCT value. However, two equal intervals on the user control do not equate to approximately equal differences in the CCT space. That is, the non-uniform mapping curve (403) is based on equal steps between adjacent points on the CCT control device (e.g., from a first level of 16 units to a second level of 32 units, to a third level of 48 units, to a fourth level of 64 units, etc., where the units are arbitrary but equal intervals). However, the equal steps result in an uneven increase in the perceived CCT values.

The uniform mapping curve (401) maps selected CCT values to equally spaced intervals on the user control. That is, the uniform mapping curve (401) has unequal steps between adjacent points on the CCT control device (e.g., from a first level of 3 units, to a second level of 6 units, to a third level of 10 units, to a fourth level of 13 units, etc., where the units are arbitrary but unequal intervals). However, the unequal steps result in an approximately uniform increase in the perceived CCT values.

One skilled in the art will readily recognize that most of the points of the uniform mapping curve (401) in FIG. 4 are concentrated within approximately the first quarter of the curve (e.g., between about 0 and about 340 units of control-input value). As the control input value increases, the distance between subsequent points on the uniform mapping curve (401) increases (the distance between subsequent points on the curve is greater). As a result, when an end user changes an input control device (e.g., the CCT control device of FIG. 3), the color temperature of an LED or LED array coupled to the input control changes rapidly at the lower portions of the control device, and then the color temperature of the LED or LED array changes very slowly. This non-linear situation creates a jumpy experience for the end user, where higher color temperatures become increasingly difficult to control accurately.

The non-uniform mapping curve (403) allows the end user a smooth and visually pleasing adjustment experience. For example, as the end user moves a small distance from the beginning of the linear motion of, for example, a slider including a modified version of the CCT control device (303), the color temperature of the LED increases by a given amount. As the end user moves approximately the same small distance toward the end of the linear motion of the slider, the perceived color difference in the color temperature of the LED increases by approximately the same given amount as at the beginning of the slider range.

In order to achieve a smooth and visually pleasing adjustment experience, a method for finding suitable slider increments and modified versions of the CCT control device of FIG. 3 according to the disclosed subject matter is described below. Consequently, we consider that there exist N points on the CCT adjustment-curve between two given CCT values. As schematically described below, the N points are computed in such a way that the color perception difference between two adjacent points is substantially uniform.

FIG. 5 illustrates an exemplary embodiment of a series of selected control points (500) substantially along a BBL (501), in accordance with various embodiments of the disclosed subject matter. The selected control points on the BBL (501) represent points of the CCT tuning-curve described above. For example, a portion (503) of the illustrated selected control points are in the range of about 6500 K to about 3000 K. However, the selected control points need not lie on the BBL (501). For example, in various embodiments, the selected control points may lie close to the BBL, for example, within a selected MacAdam ellipse (see FIG. 1 ) or across a selected range of MacAdam ellipses.

An end user control interface, such as a control device including, for example, a slider or a dial, has a linearly mapped range of motion to the computed N points. In one embodiment, the linearly mapped range of motion is then stored in the CCT control device (e.g., in a storage area such as memory and/or programmed by software, hardware, or firmware). In another embodiment, the linearly mapped range of motion may alternatively be stored, for example, within a remote control box or within the LED array (e.g., in a storage area such as memory and/or programmed by software, hardware, or firmware). In both embodiments, the storage device is electrically coupled internally or externally to the CCT control device to correlate the mechanical motion of the CCT control device to provide substantially uniform increases in perceptual CCT values from one or more LEDs or the LED array. In either case, the computed N CCT points may be generated, for example, in CIE 1976 space. The CIE 1976 color space is considered a perceptually uniform color space. Equal Euclidean distances in this space are considered perceptually uniform.

Referring now to FIG. 6 , an exemplary method process flow diagram (600) for determining control device points for a CCT tuning-curve is illustrated. In an exemplary embodiment, the computation begins in operation (601) by selecting a starting point of the CCT tuning-curve (e.g., a color temperature on the BBL line). In operation (603), a subsequent point of the CCT tuning-curve that is approximately equal to the desired distance d in u'v' space is considered. In operation (605), the exemplary method moves to the last determined point and again another subsequent point that is approximately equal to the desired distance d in u'v' space is determined. In operation (607), the exemplary method is repeated until N points are acquired or the tuning range is exhausted.

To find points at a fixed distance (e.g., a desired or predetermined distance), the interception point can be analytically computed between the CCT adjustment-curve and a circle of radius d in the u'v' color space (e.g., see Fig. 5). Alternatively, the CCT adjustment-curve can be transformed into u'v' coordinates with sufficiently high resolution, and then all points on the CCT adjustment-curve can be traversed.

Then, all points that match or approximately match the reference, including the first point, are put into a list as outputs to be used by the user control (e.g., the CCT control device). Consequently, after N points are acquired, the movement range of the user control is linearly mapped to the N points in operation (609). For example, if the movement range of the user control is 256 individual steps and the number of points N is 64, each interval of 4 is assigned a CCT value from the determined values of the N points.

In an exemplary embodiment, an algorithm used to make a CCT transition linear or substantially linear includes, for example, starting from an initial point, determining a next point at a specified distance. When a next point at a specified distance is found, the algorithm proceeds to the point just found and then determines a next point at a specified distance. All points matching the criteria, including the first point, are then put into a list as output.

Thus, the algorithm generates points on the BBL as described above with reference to FIGS. 5 and 6. The same principle can be applied to other desirable types of curves. In one specific exemplary embodiment, the algorithm used to linearize the CCT transitions can be expressed as follows:

def getCCTbyUVprimeDist(start_CCT, end_CCT, uv_dist):

cct_list = np.arange(start_CCT, end_CCT + 1) # get all the CCT values between the given range at a step size of 1

cct_uvprime = getColorPointOnPlanckian(cct_list, colorSpace='uvprime') # get the u’v’ coordinates of these CCT values

selected_cct_list = [start_CCT] # start from the first CCT value

total_cct_num = len(cct_list)

first_cct = 0 # index of the first CCT

second_cct = 0 # index of the next CCT

while first_cct < total_cct_num - 1:

found = False

while second_cct < total_cct_num - 1:

if distance (ColorPoint('uvprime', (cct_uvprime[first_cct, :])),

ColorPoint('uvprime', (cct_uvprime[second_cct, :]))) < uv_dist:

second_cct += 1

else:

found = True

selected_cct_list.append(cct_list[second_cct])

first_cct = second_cct

Break

if not found:

Break

return selected_cct_list

Those skilled in the art, upon reading and understanding the disclosed subject matter, will recognize that additional algorithms can be utilized to provide the same or similar results. Furthermore, those skilled in the art will recognize that similar types of algorithms can be coded in software, firmware, or implemented in various types of hardware devices, such as application-specific integrated circuits (ASICs) or dedicated processors or control devices. The results from the algorithm (the output list described above) may then be added to the control device (e.g., may be added to the CCT control device as software stored within the control device to correlate the movement of the device to the desired CCT value, may be hard-coded into the control device to correlate the movement of the device to the desired CCT value, may be implemented in an ASIC within the control device to correlate the movement of the device to the desired CCT value, or may be implemented in a processor or other type of hardware (e.g., a field-programmable gate array (FPGA) within the control device, or by other means known in the art and described in more detail with reference to FIG. 7 below) to correlate the movement of the device to the desired CCT value.

Machines that have instructions to perform various operations.

FIG. 7 is a block diagram illustrating components of a machine (700) according to some embodiments that may read instructions from a machine-readable medium, e.g., a non-transitory machine-readable medium, a machine-readable storage medium, a computer-readable storage medium, or any suitable combination thereof, to perform any one or more of the methodologies discussed herein. Specifically, FIG. 7 depicts a schematic diagram of a machine (700) in the form of an exemplary computer system, within which instructions (724) (e.g., software, programs, applications, applets, apps, or other executable code) may be executed to cause the machine (700) to perform any one or more of the methodologies discussed herein (e.g., process recipes).

In alternative embodiments, the machine (700) may operate as a standalone device or may be connected (e.g., networked) to other machines. In a networked arrangement, the machine (700) may operate as a server machine or a client machine in a server-client network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. The machine (700) may be a server computer, a client computer, a personal computer (PC), a tablet computer, a laptop computer, a netbook, a set-top box (STB), a personal digital assistant (PDA), a cellular telephone, a smart phone, a web appliance, a network router, a network switch, a network bridge, or any machine capable of sequentially or otherwise executing instructions (724) specifying actions to be taken by the machine. Furthermore, while only a single machine is illustrated, the term "machine" should also be taken to include a collection of machines that individually or jointly execute instructions (724) to perform any one or more of the methodologies discussed herein.

The machine (700) includes a processor (702) (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a radio frequency integrated circuit (RFIC), or any suitable combination thereof), a main memory (704), and a static memory (706) configured to communicate with each other via a bus (708). The processor (702) may include microcircuits that are temporarily or permanently configurable by some or all of the instructions (724), such that the processor (702) is configurable to perform, in whole or in part, any one or more of the methodologies described herein. For example, a set of one or more microcircuits of the processor (702) may be configured to execute one or more modules (e.g., software modules) described herein.

The machine (700) may further include a graphical display (710) (e.g., a plasma display panel (PDP), a light emitting diode (LED) display, a liquid crystal display (LCD), a projector, or a cathode ray tube (CRT)). The machine (700) may also include an alphanumeric input device (712) (e.g., a keyboard), a cursor control device (714) (e.g., a mouse, touchpad, trackball, joystick, motion sensor, or other pointing mechanism), a storage unit (716), a signal generation device (718) (e.g., a speaker), and a network interface device (720).

The storage unit (716) includes a machine-readable medium (722) (e.g., a tangible and/or non-transitory machine-readable storage medium) on which instructions (724) implementing any one or more of the methodologies or functions described herein are stored. The instructions (724) may also reside, completely or at least partially, within the main memory (704), within the processor (702) (e.g., within a cache memory of the processor), or both, during execution thereof by the machine (700). Thus, the main memory (704) and the processor (702) may be considered machine-readable media (e.g., tangible and/or non-transitory machine-readable media). The instructions (724) may be transmitted or received over a network (726) via the network interface device (720). For example, the network interface device (720) may communicate the commands (724) using any one or more transport protocols (e.g., hypertext transfer protocol (HTTP)).

In some embodiments, the machine (700) may be a portable computing device, such as a smartphone or tablet computer, and may have one or more additional input components (e.g., sensors or gauges). Examples of such additional input components include an image input component (e.g., one or more cameras), an audio input component (e.g., a microphone), a direction input component (e.g., a compass), a location input component (e.g., a global positioning system (GPS) receiver), an orientation component (e.g., a gyroscope), a motion detection component (e.g., one or more accelerometers), an altitude detection component (e.g., an altimeter), and a gas detection component (e.g., a gas sensor). Inputs collected by any one or more of these input components may be accessible and available for use by any of the modules described herein.

As used herein, the term "memory" refers to a machine-readable medium capable of temporarily or permanently storing data, including but not limited to random-access memory (RAM), read-only memory (ROM), buffer memory, flash memory, and cache memory. Although the machine-readable medium (722) is illustrated in the embodiments as being a single medium, the term "machine-readable medium" should be considered to include a single medium or multiple media (e.g., a centralized or distributed database, or associated caches and servers) capable of storing instructions. The term "machine-readable medium" should also be considered to include any medium or combination of multiple media capable of storing instructions for execution by a machine (e.g., machine (700)) such that the instructions, when executed by one or more processors (e.g., processor (702)) of the machine, cause the machine to perform any one or more of the methodologies described herein. Accordingly, the term "machine-readable medium" refers not only to a single storage device or device, but also to "cloud-based" storage systems or storage networks that include multiple storage devices or devices. Accordingly, the term "machine-readable medium" should be considered to include, but is not limited to, one or more types of (e.g., non-transitory) data storage in the form of solid-state memory, optical media, magnetic media, or any suitable combination thereof.

Additionally, a machine-readable medium is non-transitory in that it does not embody a propagating signal. However, labeling a tangible machine-readable medium as "non-transitory" should not be construed to imply that the medium is immovable - the medium should be considered to be capable of being moved from one physical location to another. Additionally, because a machine-readable medium is tangible, the medium can be considered a machine-readable device.

The instructions (724) may further be transmitted or received over a network (726) (e.g., a communications network) using a transmission medium via the network interface device (720) and any of a number of well-known transmission protocols (e.g., HTTP). Examples of communications networks include a local area network (LAN), a wide area network (WAN), the Internet, mobile telephone networks, POTS networks, and wireless data networks (e.g., WiFi and WiMAX networks). The term "transmission medium" shall be taken to include any intangible medium, including a digital or analog communications signal or other intangible medium that can store, encode, or carry instructions for execution by a machine, and that facilitates the transfer of such software.

In some exemplary embodiments, the hardware modules may be implemented, for example, mechanically or electronically, or any suitable combination thereof. For example, the hardware modules may include dedicated circuitry or logic that is permanently configured to perform certain operations. The hardware modules may be or include special-purpose processors, such as field-programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs). The hardware modules may also include programmable logic or circuitry that is temporarily configured by software to perform certain operations. For example, the hardware modules may include software embedded within a central processing unit (CPU) or other programmable processor. It will be appreciated that the decision to implement a hardware module mechanically, electrically, as dedicated and permanently configured circuitry, or as temporarily configured circuitry (e.g., configured by software) may be driven by cost and time considerations.

In various embodiments, many of the components described may include one or more modules configured to implement the functions disclosed herein. In some embodiments, the modules may comprise software modules (e.g., code stored or otherwise embodied on a machine-readable medium or transmission medium), hardware modules, or any suitable combination thereof. A "hardware module" is a tangible (e.g., non-transitory) physical component (e.g., a set of one or more microprocessors or other hardware-based devices) that performs certain operations and interprets certain signals. One or more of the modules may be configured or arranged in a given physical manner. In various embodiments, one or more of the microprocessors or one or more of the hardware modules thereof may be configured by software (e.g., an application or a portion thereof) as a hardware module that operates to perform the operations described herein for that module.

In some exemplary embodiments, the hardware module may be implemented, for example, mechanically or electronically, or any suitable combination thereof. For example, the hardware module may include dedicated circuitry or logic that is permanently configured to perform certain operations. As described above, the hardware module may involve or include a special purpose processor, such as an FPGA or an ASIC. The hardware module may also include programmable logic or circuitry that is temporarily configured by software to perform certain operations, such as linearly mapping a range of motion to the calculated N points on the color-coordinated device (e.g., see FIGS. 5 and 6 ).

The above description includes illustrative examples, devices, systems, and methods implementing the disclosed subject matter. In the description, for purposes of explanation, numerous specific details have been set forth in order to provide an understanding of various embodiments of the disclosed subject matter. However, it will be apparent to those skilled in the art that various embodiments of the subject matter may be practiced without these specific details. In addition, well-known structures, materials, and techniques have not been shown in detail so as not to obscure the various illustrated embodiments.

As used herein, the term "or" may be interpreted in an inclusive or exclusive sense. Additionally, other embodiments will be understood by those skilled in the art upon reading and understanding the disclosure provided. Additionally, upon reading and understanding the disclosure provided herein, those skilled in the art will readily understand that various combinations of the techniques and examples provided herein can all be applied in various combinations.

While various embodiments are discussed separately, these separate embodiments are not intended to be considered as independent techniques or designs. As discussed above, each of the various parts may be interrelated, and each may be used individually or in conjunction with other types of electrical control devices, such as dimmers and related devices. Consequently, while various embodiments of methods, operations, and processes have been described, these methods, operations, and processes may be used individually or in various combinations.

Consequently, many modifications and variations can be made, as will be apparent to those skilled in the art upon reading and understanding the disclosure provided herein. In addition to those listed herein, functionally equivalent methods and devices within the scope of the present disclosure will be apparent to those skilled in the art from the foregoing description. Portions and features of some embodiments may be incorporated into, or substituted for, those of other embodiments. Such modifications and variations are intended to fall within the scope of the appended claims. Accordingly, the present disclosure should be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

The Abstract of this disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. The Abstract is submitted with the understanding that it will not be used to interpret or limit the claims. Additionally, in the foregoing Detailed Description, it will be appreciated that various features may be grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure should not be construed as limiting the claims. Accordingly, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.

Claims (23)

A device for color-adjusting a light-emitting diode (LED) array for perceptually uniform color adjustment,
A storage device electrically coupled to receive a signal from a correlated color temperature (CCT) control device, the storage device configured to store and control a correlation between a mechanical range of travel of the CCT control device to provide substantially uniform increases in a plurality of perceptual CCT values from the LED array based on a set of N predetermined values, the set of N predetermined values being based on a number of discrete steps within the mechanical range of travel of the CCT control device and being calculated to produce a color perceptual difference to a human, wherein the color perceptual difference between two adjacent values of the set of N predetermined values is substantially uniform and linear for incremental CCT increases, the storage device further configured to map selected CCT values to substantially evenly spaced intervals on the CCT control device to produce a substantially uniform mapping curve having unequal step distances between adjacent values of the N predetermined values.
A device comprising: In the first aspect, the set of N predetermined values is determined as points on a CCT adjustment-curve between two given CCT values, the set of N predetermined values is calculated such that a perceptual difference in color between two adjacent points is substantially uniform, and the unequal step distances are selected to reduce an unequal change in the perceptual CCT values as the level of the CCT control device changes. A device in the first aspect, wherein the set of N predetermined values is determined to lie substantially along a black-body line (BBL). A device in accordance with claim 1, wherein the set of N predetermined values is determined to be substantially located near a black body line (BBL). A device in accordance with claim 1, wherein the set of N predetermined values is determined to lie substantially near a black body line (BBL) and within a selected Macadam Ellipse. A device in accordance with claim 1, wherein the set of N predetermined values is determined to lie substantially near the black body line (BBL) and within a selected range of MacAdam ellipses. In the first aspect, the device comprises at least one LED for each of three selected colors of light in the visible portion of the spectrum. In the first aspect, the device is a multi-color array including a plurality of LEDs of different colors in the visible portion of the spectrum. In the 8th paragraph, the device, wherein the colors of the LEDs of the multi-color array include at least one red LED, at least one green LED, and at least one blue LED. A device in accordance with claim 8, wherein the multicolor array comprises at least one desaturated red LED, at least one desaturated green LED, and at least one desaturated blue LED. As a controllable lighting device,
An LED array having at least one desaturated red LED, at least one desaturated green LED, and at least one desaturated blue LED; and
A storage device electrically coupled to receive a signal from a correlated color temperature (CCT) control device, and configured to store and control a correlation between a range of mechanical movement of the CCT control device to provide substantially uniform increases in perceptual CCT values from the LED array based on a set of N predetermined values, wherein the set of N predetermined values is calculated to produce a color perceptual difference to a human, wherein the color perceptual difference between two adjacent values of the set of N predetermined values is substantially uniform and linear for incremental CCT increases, and the storage device is further configured to map selected CCT values to substantially evenly spaced intervals on the CCT control device to produce a substantially uniform mapping curve having unequal step distances between adjacent values of the N predetermined values.
A controllable lighting device comprising: A controllable lighting device in accordance with claim 11, wherein the set of N predetermined values is determined as points on a CCT adjustment-curve between two given CCT values, the set of N predetermined values is calculated such that a perceptual difference in color between two adjacent points is substantially uniform, and the unequal step distances are selected to reduce an unequal change in the perceptual CCT values as the level of the CCT control device changes. A controllable lighting device in claim 11, wherein the LED array having the at least one desaturated red LED, the at least one desaturated green LED, and the at least one desaturated blue LED is configured to have a color temperature range of 2700K to 6500K. A controllable lighting device in claim 11, wherein the set of N predetermined values is determined to lie substantially along a black-body line (BBL). A controllable lighting device in accordance with claim 11, wherein the set of N predetermined values is determined to lie substantially near a black body line (BBL) and within a selected range of MacAdam ellipses. A method for determining control device points for a correlated color temperature (CCT) adjustment curve,
A step of determining a set of N predetermined values, wherein the N predetermined values are calculated to produce a color perceptual difference for a human, wherein the color perceptual difference between two adjacent points among the N points is substantially uniform and linear for incremental CCT increases, and the set of N predetermined values is further determined to map the selected CCT values to substantially evenly spaced intervals on the CCT control device, thereby producing a substantially uniform mapping curve having unequal step distances between adjacent values among the N predetermined values.
A method for determining control device points for a CCT adjustment-curve, comprising: A method for determining control device points for a CCT tuning-curve, wherein the starting point for the CCT tuning-curve is selected to be on a black body line (BBL) in the 16th paragraph. In claim 16, a method for determining control device points for a CCT tuning-curve, wherein the starting point is selected to be substantially close to a blackbody line (BBL) and within a selected MacAdam ellipse. A method for determining control device points for a CCT adjustment-curve, further comprising the step of repeating the determining steps until at least one stop point including stop points is obtained, the step of obtaining a set of N predetermined values and the step of exhausting an adjustment range of the CCT control device in the 16th paragraph. In the 16th paragraph, the method
A step of determining a point at a predetermined distance d in the u'v' space from a selected starting point, wherein the step of determining the point at the predetermined distance d comprises a step of analytically computing an interception point between the CCT adjustment-curve and a circle of radius r in the u'v' color space.
A method for determining control device points for a CCT adjustment-curve, comprising: A method for determining control device points for a CCT adjustment-curve, wherein the step of determining a point at a predetermined distance d in the 20th paragraph further comprises the steps of: converting the CCT adjustment-curve into u'v' coordinates; and subsequently traversing all points on the CCT adjustment-curve. A method for determining control device points for a CCT adjustment-curve, further comprising the step of storing all determined points including the first selected starting point in a list as outputs to be used by the CCT control device in the 20th paragraph. A method for determining control device points for a CCT adjustment-curve, further comprising the step of linearly mapping the range of movement of the CCT control device to all of the determined points in clause 22.

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