RU2494495C1 - Multielement colour radiation source - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: multielement colour radiation source includes a plurality of light-emitting diode (LED) light sources of different colours for obtaining light of a mixed colour, optically interfaced with a screen, and a device for controlling the LED light sources in accordance with differences between given values, which represent light of a mixed colour, having the required colour, and control data representing the colour of the light of mixed colour generated by said LED light sources, wherein said control data are provided by at least one colour sensor connected to the input of the control device; the LED light sources are connected to corresponding outputs of the control device, wherein the colour sensor is interfaced with the screen; the plurality of LED light sources consist of at least one cluster, having at least one LED light sources of each colour; the clusters are combined into a LED array; the number of outputs of the control device connected to the plurality of LED light sources of each colour corresponds to the number of supply groups for the given colour, and the value of supply current of a group is determined from a given relationship.

EFFECT: uniformity of power illumination of a screen with the possibility of changing the illumination colour in a wide range of colours.

5 cl, 7 dwg

Description

The invention relates to LED lighting devices, namely to multi-element color radiation sources used to solve colorimetric problems in vision devices. The main field of application of the device is optoelectronic devices and color analysis complexes for industrial use.

Known multi-color color radiation source (patent US 6799865 B2 from 07/19/2002, IPC F21V 11/00, publication date 10/05/2004) containing a set of LED UV sources distributed over the surface of the LED matrix, optically paired with the screen, while red and the green components of the mixed-color light are obtained by converting the radiation of the LED UV sources by the phosphor layers covering the LED matrix, while the device further includes blue LED sources located along iferii LED matrix for the blue color light components are mixed.

The disadvantage of this device is that the color rendering of this device is limited due to the dependence of the brightness of the red and green color channels on the radiation intensity of the same LED matrix of UV radiation sources. Another disadvantage of the device is the lack of the ability to create and control the uniformity of energy illumination of the screen.

A device is known (patent RU 2415518 C2 of 10.16.2006, IPC Н05В 33/08, publication date 03/27/2011), which is an LED lighting device (multi-element color radiation source) containing many LED light sources of various colors to produce mixed-color light, optically coupled to the screen, and a device for controlling LED light sources in accordance with the differences between the set values representing mixed-color light having the desired color and the control data representing which produce the color of light of a mixed color produced by said LED light sources, wherein said control data is provided by at least one color sensor.

This device is the closest to the claimed invention in terms of features, therefore, is selected as a prototype. The disadvantage of this device is that it only controls the color stability of the LED light sources, while the device does not have components that create and control the uniformity of the energy illumination of the screen. This problem is relevant for solving colorimetric problems in vision devices, because for solving this type of problem it is necessary to have the same color coordinates over the entire surface of the screen.

Thus, the object of the present invention is to ensure uniformity of the energy illumination of the screen with the ability to change the color of illumination in a wide range of colors.

This problem is solved due to the fact that the multi-element color radiation source (LED lighting device) contains many LED light sources of various colors to produce mixed-color light optically coupled to the screen, and a control device for LED light sources in accordance with the differences between the set values representing mixed-color light having the desired color and control data representing the color of the mixed-color light generated by using LED light sources, wherein said control data is provided by at least one color sensor connected to the input of the control device, LED light sources are connected to the corresponding outputs of the control device, while the color sensor is optically coupled to the screen, a plurality of LED light sources consists of at least one cluster containing at least one LED light source of each color, clusters are combined into an LED matrix, the number of odov control device connected to the plurality of LED light sources of each color corresponds to the number of power groups for a given color, and the magnitude of the supply current group determined from the relationship:

, $$I_m=I_0\cdot l_m=I_0\cdot \frac{E_{nom}}{\max \left({\cos }^2\left[arctg\left\{\frac{\sqrt{{(x-na)}^2+{(y-ka)}^2}}{z}\right\}\right]\right)}$$

,

where I ₀ is the minimum supply current in the group, l _m is the power factor for this m-th group, E _nom is the required screen illumination for a given color, determined using the color addition functions to create the illumination of a given color on the screen; x, y - spatial coordinates that determine the position of a point on the screen; n and k are the row and column number, which determines the location of the LED light source in the LED matrix; a - the distance between the LED light sources; z is the distance from the LED matrix to the screen. In addition, the clusters combined in an LED matrix are made in the form of a triangle or rectangle, the color sensor is made in the form of a color video camera with a multi-element radiation detector, and the control device is made in the form of a computer, one of the inputs of which is connected to the output of the color sensor, and the other with a pulse-width modulation circuit, the outputs of which are connected to the corresponding inputs of the LED light sources.

The invention is illustrated by drawings, where figure 1 shows a structural diagram of a multi-element color radiation source.

A multi-element color radiation source contains an LED array 1, which in turn contains at least one cluster consisting of at least one LED light source of red 2R, green 2G, and blue 2B colors. The light sources 2R, 2G, 2B are optically coupled to the screen 3, which in turn is in the field of view of the color sensor 4. In this case, the multi-element color radiation source includes a control device 5, the input of which is connected to the output of the color sensor 4. LED light sources 2R, 2G, 2B of each color (red, green and blue) are connected to the respective outputs by the control device 5.

Figure 2 illustrates the principle of organization of the LED matrix 1, where a - with the honeycomb structure of the LED matrix 1, composed on the basis of a triangular cluster, b - with the regular structure of the LED matrix 1, composed on the basis of a rectangular (linear) cluster.

Clusters in the structure of the LED matrix 1 comprise a grid connecting the nearest LED light sources 2, while the orientation and location of the clusters is determined by their type.

For a triangular cluster (figa), the color and location of each LED light source 2 in the structure of the LED matrix 1 is determined by the colors of two adjacent LED sources located in the nodes of the formed cluster.

For a rectangular (linear) cluster (Fig. 2b), the color definition of each LED source in the structure of LED matrix 1 is determined by the colors of two adjacent LED sources located at the nodes of the formed cluster and the sequence of arrangement of cluster elements in rows and columns of the LED matrix.

Figure 3 illustrates examples of the location of the LED light sources 2 of red R, green G and blue B colors on the surface of the LED matrix 1, where a - with the honeycomb structure of the LED matrix 1, b - with the regular structure of the LED matrix 1.

Figure 4 shows the distribution of the LED light sources 2 according to the power groups, where a - with the honeycomb structure of the LED matrix 1, b - with the regular structure of the LED matrix 1.

Figure 5 shows the distribution of illumination in the cross section of the screen 3 when the LED light sources 2 are supplied with a current of the same magnitude, where a is the honeycomb structure of the LED matrix, b is the regular structure of the LED matrix 1.

6 shows the distribution of illumination in the cross section of the screen 3 when the LED light sources 2 are supplied with current of different sizes in accordance with the calculated values of the supply current for different power groups, where a is the distribution of illumination in the cellular structure of the arrangement of LED light sources 2, b is the distribution of illumination at regular arrangement of LED light sources 2. The magnitude of the energy dips in the total illumination of the screen 3 does not exceed 2%. E _R is the energy illumination of the screen 3 created by the red LED sources, E _G is the energy illumination of the screen 3 created by the green LED sources, E _B is the energy illumination of the screen 3 created by the blue LED sources. E _total - total energy illumination of the screen 3, E _{total max} - maximum value of the total energy illumination of the screen 3.

7 shows a structural diagram of a control device 5, comprising a computer, one of the inputs of which is connected to the output of the color sensor 4, and the other to a pulse-width modulation circuit. The outputs of the pulse width modulation circuit are connected to the corresponding inputs of the LED light sources 2.

When operating a multi-color color radiation source, the control device 5 calculates the nominal values of each color R, G and B for the selected color point on the CIE color chart, a description of which is given in various literature, for example, Yustova E.N. Color Measurements (Colorimetry). - St. Petersburg: Publishing House of St. Petersburg University, 2000. - 399 p. Next, the control device 5 gives the command to turn on the LED light sources 2. In the General case, the number of different colors of LED light sources 2 in the cluster can be increased, for example, to six (red, green, blue, yellow, raspberry and blue), which will allow reproduce backlight colors 3 in an even wider range of colors. In order to compensate for the uneven illumination of the screen 3 by LED light sources 2, the latter are divided into power groups within each color channel (Fig. 4). The value of the supply current for each power group is determined from the ratio:

$$I_m=I_0\cdot l_m=I_0\cdot \frac{E_{nom}}{\max \left({\cos }^2\left[arctg\left\{\frac{\sqrt{{(x-na)}^2+{(y-ka)}^2}}{z}\right\}\right]\right)},(\mathrm{one})$$

where I ₀ is the minimum supply current in the group, l _m is the power factor for this group, E _nom is the required illumination of the screen 3 for a given color, determined using the color addition functions to create the illumination of a given color on the screen 3; x, y - spatial coordinates that determine the position of a point on screen 3; n and k are the row and column number defining the location of the LED light source 2 in the LED matrix 1; a - the distance between the LED light sources 2; z is the distance from the LED matrix 1 to the screen 3.

Thus, the control device 5 supplies a power supply current to each LED light source 2, the value of which sets the brightness of the LED light sources 2 in the necessary proportion to compensate for energy "dips" in the illumination of the screen 3 (Fig.5, 6). The color illumination of the screen 3 is analyzed by the color sensor 4 constantly both in terms of energy uniformity and the correspondence of the color of illumination to a given one. The color sensor 4 registers the distribution of color coordinates on the surface of the screen 3, as well as its energy illumination and transmits the received data to the control device 5. After analyzing the received data in the case of deviations of the current color coordinates of the screen 3 from the set, as well as in the case of the formation of energy “dips” in its illumination, the control device 5 automatically calculates the values of the correction factors for each power group of the light sources 2. The control device 5 changes the power supply current LED light sources 2 taking into account correction factors. This allows you to create a mixed color illumination in accordance with the specified, as well as to maintain the uniformity of the energy illumination of the screen 3 when changing the optical parameters of the LED light sources 2 in the process of their work.

An example of a specific implementation.

To create a uniform energy illumination of the screen 3 with a size of 12 × 16 cm (the magnitude of the energy “dips” on the surface of the screen 3 does not exceed 2%), spaced 10 cm from the LED matrix 1, with the possibility of changing the color of the illumination in a wide range of colors, you can use LED matrix 1 with a honeycomb structure of size 7 × 3 cm ² containing 28 LED light sources of red 2R and green 2G colors, as well as 25 LED light sources of blue 2 V colors (figa). The distance between the centers of neighboring sources 2 is 5 mm with a size of each of them 3 mm. The expressions for determining the color components of the illumination of the screen 3 for each color channel R _nom , G _nom and B _nom from the LED matrix 1 according to Grassmann's laws, taking into account the emission spectra of LED light sources, are written in the form:

$$\{\begin{array}{l}{R}_{nom}=\max [{\displaystyle \underset{380}{\overset{780}{\int }}{E}_R(x,\text{y}\text{,}\lambda \text{)}\cdot \overline{\text{r}}(\lambda )d\lambda ]}\\ G_{nom}=\max [{\displaystyle \underset{380}{\overset{780}{\int }}{E}_G(x,\text{y}\text{,}\lambda \text{)}\cdot \overline{\text{g}}(\lambda )d\lambda ],(2)}\\ B_{nom}=\max [{\displaystyle \underset{380}{\overset{780}{\int }}{E}_B(x,\text{y}\text{,}\lambda )\cdot \overline{b}(\lambda )d\lambda ]}\end{array}$$

- суммарное спектральное распределение освещенности от всех светодиодных источников света красного цвета 2R в точке с координатами (х, y) на экране 3; $$E_G(x,y,\lambda )={\displaystyle \sum _j{E}_{G_j}(x,y,\lambda )}$$

- суммарное спектральное распределение освещенности от всех светодиодных источников света зеленого цвета 2G в точке с координатами (х, y) на экране 3; $$E_B(x,y,\lambda )={\displaystyle \sum _q{E}_B{}_q(x,y,\lambda )}$$

- суммарное спектральное распределение освещенности от всех светодиодных источников света синего цвета 2В в точке с координатами (x, y) на экране 3; i, j q - количество светодиодных источников света 2 красного, зеленого и синего цвета соответственно; $$\overline{r}(\lambda )$$

, $$\overline{g}(\lambda )$$

, $$\overline{b}(\lambda )$$

- функции сложения цветов, λ - длина волны.Where $$E_R(x,y,\lambda )={\displaystyle \sum _i{E}_{R_i}(x,y,\lambda )}$$

- the total spectral distribution of illumination from all 2R red LED light sources at a point with coordinates (x, y) on screen 3; $$E_G(x,y,\lambda )={\displaystyle \sum _j{E}_{G_j}(x,y,\lambda )}$$

- the total spectral distribution of illumination from all 2G green LED light sources at a point with coordinates (x, y) on screen 3; $$E_B(x,y,\lambda )={\displaystyle \sum _q{E}_B{}_q(x,y,\lambda )}$$

- the total spectral distribution of illumination from all 2B blue LED light sources at a point with coordinates (x, y) on screen 3; i, jq - the number of LED light sources 2 red, green and blue, respectively; $$\overline{r}(\lambda )$$

, $$\overline{g}(\lambda )$$

, $$\overline{b}(\lambda )$$

are the functions of color addition, λ is the wavelength.

To distribute LED light sources 2 by power groups, first calculate the value of the power factor for each LED source 2 according to the formula (1), for E _nom = R _nom for red, E _nom = G _nom for green and E _nom = B _nom for blue colors respectively. LED light sources 2 having close values of power factors are combined into one group (Fig. 4). The deviation of the values of power factors for LED light sources 2 of one power group should not exceed 0.1% (to ensure uniformity of energy illumination in each color channel). With this configuration of the LED matrix 1 (Fig. 3a), the solution of equation (1) determines the need to use 24 power groups (8 for red, 8 for green, and 8 for blue color channels) (Fig. 4a). At the same time, LED sources with similar technical characteristics should be combined into one power group. The values of power factors in this case will be as follows:

R ₁ = 1, G ₁ = 1, B ₁ = 1, R ₂ = 1.03, G ₂ = 1.09, B ₂ = 1.003, R ₃ = 1.06, G ₃ = 1.19, B ₃ = 1.03, R ₄ = 1.11, G ₄ = 1.29, B ₄ = 1.07, R ₅ = 1.16, G ₅ = 1.59, B ₅ = 1.13, R ₆ = 1.19, G ₆ = 1.64, B ₆ = 1.35, R ₇ = 1.23, G ₇ = 1.7, B ₇ = 1.46, R ₈ = 1.44, G ₈ = 2.11, B ₈ = 1.59.

The specified methodology for calculating power factors allows you to fill the energy "gaps" in the resulting illumination of the screen 3. Thus, it is possible to learn the uniform distribution of color coordinates on the surface of the screen 3 (the deviation is not more than 2%) (Fig.6).

The color sensor 4 is made in the form of a colorimetrically certified color video camera with a multi-element radiation detector.

The control device 5 (Fig.7) is made in the form of a computer with a pulse-width modulation circuit connected to it. This allows the control device 5 to calculate the nominal values of each color R, G and B for the selected color point on the CIE color chart, give a command to turn on the LED light sources 2, change the brightness of the LED light sources 2 in the necessary proportion to compensate for the energy "gaps" in the backlight Screen 3 in automatic mode.

Thus, the claimed combination of features ensures uniformity of energy illumination of the screen 3 with the ability to change the color of illumination in a wide range of colors. The device allows you to create a given distribution of chromaticity coordinates by the spatial coordinates of the screen 3, which is often more important for technical vision compared to ensuring the stability of the color characteristics of LED light sources 2. Such cases of technical vision include all cases of measuring the parameters of an object moving against a certain background whose color characteristics must be set with high accuracy (for example, the allowable deviation of the chromaticity coordinates on the surface 3 wound no more than 2% of the target color coordinates). Using the present invention, it is possible to create a uniform color illumination of the screen 3 without energy “dips” at any point.

Claims (5)

1. A multi-element color radiation source comprising a plurality of LED light sources of various colors for producing mixed-color light optically coupled to a screen and an LED light source control device in accordance with differences between set values representing mixed-color light having the desired color and controlling data representing the color of the light of the mixed color generated by the specified LED light sources, while the specified control data are printed using at least one color sensor connected to the input of the control device, and LED light sources are connected to the corresponding outputs of the control device, characterized in that the color sensor is optically coupled to the screen, and a plurality of LED light sources consists of at least one cluster containing at least one LED light source of each color, while the clusters are combined into an LED matrix, the number of outputs of the control device connected to the quality of LED light sources of each color, corresponds to the number of power groups for a given color, and the value of the power supply current of the group is determined from the ratio
$$I_m=I_0\cdot l_m=I_0\cdot \frac{E_{nom}}{\max \left({\cos }^2\left[arctg\left\{\frac{\sqrt{{(x-na)}^2+{(y-ka)}^2}}{z}\right\}\right]\right)},$$

where I ₀ is the minimum supply current in the group, l _m is the power factor for this m-th group, E _nom is the required screen illumination for a given color, determined using the color addition functions to create a given color illumination on the screen; x, y - spatial coordinates that determine the position of a point on the screen; n and k are the row and column number, which determines the location of the LED light source in the LED matrix; a - the distance between the LED light sources; z is the distance from the LED matrix to the screen. 2. A multi-element color radiation source according to claim 1, characterized in that the clusters combined in an LED matrix are made in the form of a triangle. 3. A multi-element color radiation source according to claim 1, characterized in that the clusters combined in an LED matrix are made in the form of a rectangle. 4. A multi-element color radiation source according to claim 1, characterized in that the color sensor is made in the form of a color video camera with a multi-element radiation receiver. 5. The multi-element color radiation source according to claim 1, characterized in that the control device is made in the form of a computer, one of the inputs of which is connected to the output of the color sensor, and the other to a pulse-width modulation circuit, the outputs of which are connected to the corresponding inputs of the LED sources Sveta.

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