TW200904239A - Method and device for driving an LED system - Google Patents

Abstract

For estimating temperatures of LED of a matrix (2), a model (100) is used. For each LED (10X, Y), the model comprises: a first node (110X, Y) representing the LED; a first capacitive component (131) connected to said first node, representing heat capacitance of the LED; a second node (103X, Y) representing a backplate portion corresponding with the LED; a second capacitive component (132) connected to said second node, representing heat capacitance of said backplate portion; a resistive component (145) between said two nodes; representing heat resistance of a thermal coupling between the LED and the backplate; resistive components (141, 142, 143, 144) between said second node (103X, Y) and adjacent second nodes, representing heat resistances of thermal couplings between the backplate portion and adjacent backplate portions; a first flow source component (153) connected to said first node, representing heat dissipation of the LED.

Description

200904239 IX. Description of the Invention: TECHNICAL FIELD OF THE INVENTION The present invention generally relates to the control of LEDs. One particular application area of LEDs is as a backlight in an LCD panel, such as in an LCD TV, and the invention will be specifically explained for this application', but it should be noted that the invention is not limited to this application. [Prior Art] A transmissive type LCD display panel needs to have a backlight, that is, a light source placed behind the LCD visible from the viewer. Only one light source can be used to implement one light system. Backlighting embodiments based on a plurality of elongated light sources (typically gas discharge lamps) oriented horizontally above each other have been developed, and such embodiments have the advantage that they may impart different amounts of light to the panel Different parts to enhance contrast differences. Instead of a gas discharge lamp, it is also possible to use a plurality of LEDs. The LEDs are typically configured as horizontal strips, and the backlight includes a plurality of such strips disposed above each other. The LEDs of a strip can be driven in parallel, but it is also possible to individually drive individual LEDs so that the light output values of the individual LEDs are individually set to enhance the contrast of the corresponding portions of the LCD panel. This device is also indicated as two-dimensional dimming/boosting and is executed based on the content of a video k-number. Since this is already known to those skilled in the art, further explanation may be omitted herein. An important feature in LED control is the desire to control the light output. For example, in the above example, if the analysis of the view signal indicates that the video content has not changed, the light output of the backlight LED should not change. However, a well-known problem is that the field drive number (LED current) is maintained at a time, and the LED light output is not 129529.doc 200904239 must be constant. Significantly, the light output of an LED depends on the temperature of its junction temperature in Vietnam, the lower its light output. In addition, the ratio at which the light output decreases as the temperature rises depends on the type of LED. For example, for a white LED, raising the temperature from 2 (TC to 7〇t: can result in a 2% reduction in light output. This is already undesirable in a single LED system, even though it may not attract the attention of most users. In a multi-LED system, the effect is more obvious because the user will see different LEDs having different light outputs where they should have the same light output. v Politics is not only a problem in the backlight field. For example, In the field of lighting, LEDs of different colors are used to create a lighting with a special color point, and the difference in light output of individual LEDs causes a serious deviation of the color points. At this point, for maintaining the light output of an LED, real measurement light has been proposed. Output or - a parameter-based solution that affects the light output. For example, US 5.783.909 describes a circuit for maintaining the luminous intensity of an LED, wherein a light sensor is used to sense the luminous intensity of the LED or A temperature sensor is used to sense the operating temperature of the LED. w〇2〇〇6/〇43232: The junction temperature of one (four) can be measured by measuring the resistance of the LED. The first technical solution is that the number of sensors required is proportional to the number of sensors, and these sensors, together with the necessary hardware and interface hardware, increase the cost and complexity of the system. Whether it is a backlight system or a lighting system, even though it may have a plurality of LEDs sharing one sensor, the cost is still high. [Invention] The object of the present invention is to eliminate or at least reduce the above mentioned problems. 129529.doc 200904239 In particular, the object of the present invention is to provide a method and apparatus for driving an LED system in which temperature dependent light output is compensated without the need for a sensor and measuring hardware. According to the present invention, Measure the temperature of the LED, and replace it with the individual power supplied to the individual LEDs. Based on one of the thermal models of the LED system, the temperature of the individual LEDs is predicted/estimated/estimated, and the individual temperatures calculated/predicted/estimated as such Based on the individual control signals applied to individual LEDs, the thermal model can be implemented with hardware, but it is convenient to implement the thermal model with software. Further advantageous details are mentioned in the claims. US 6,970.8 11 discloses a circuit for driving a signal led comprising an ambient temperature sensor and comprising a hardware model Modeling the behavior of the LED light output in response to the drive signal. However, the solution is not suitable for a system comprising a plurality of LEDs. These and other aspects, features and advantages of the present invention will be preferred by one or more of the following. The embodiments are further explained with reference to the description of the drawings, wherein like reference numerals indicate the same or similar components. FIG. 1 schematically illustrates a backlight system 1 including a mounting on the backplane 3 The rectangular matrix 2 of the backlit LED. In general, the LED will be indicated by reference numeral 1; if a specific individual LED is intended to be indicated, the subscripts X and Y will be used to indicate the horizontal and vertical position of the LED in the rectangular matrix. . The system 1 further includes a controller 3〇 that determines the amount of light that each led 10 should emit. For example, the controller 3 can have one input 3 接收 received by 129529.doc 200904239 and can be designed to determine the dimming or a increase of individual LEDs based on the video content, as in essence. A known. In order to output a control signal for LED control, the controller 3 has a corresponding number of outputs, which are collectively labeled "Output 32." For each LED, the system 丨 can include a corresponding LED driver 20 that receives a corresponding control signal from the controller 3 and generates an appropriate drive signal for the LED; in Figure 1, for simplicity The reason, this is only shown for one LED. Similarly, the power and power lines to the LEDs for the sake of simplicity are not shown. The appropriate drive signal for the LED can be a piece of led current that is properly turned on/off at the switching frequency, where the active time cycle determines the average LED current and thus determines the dimming or boost level. The control signal from the controller 30 may be an apostrophe indicating the time cycle to be applied, or itself may be a block signal, in which case the LED driver 20 refers to the block control signal. The situation simply switches the LED current on and off. Figure 2 is a diagram showing the basic problems constituting the basis of the present invention. The horizontal axis of Figure 2 represents the temperature τ (degrees Celsius), and the vertical axis of Figure 2 represents the relative light output RLO (percentage) of an LED. The f chart shows that the light output is inversely proportional to the “increase”: as the temperature increases, the light output decreases. In this figure, room temperature is taken as a reference value. Different types of LEDs can have different temperature dependencies. In the example of the figure, the light output is reduced by 1% for every increase in temperature. It is assumed that the controller 3 is intended to drive a particular LED to achieve a certain constant light output. For this purpose, assume that the controller generates a constant control letter 129529.doc 200904239. Since the system is turned on, the LED consumes some energy and its temperature is rising; therefore, its light output drops. If the Led is cycled for a higher period of time to achieve a higher light output (boost), the higher the temperature rise, the higher the relative decrease in light output. A complicating factor is that the LED also causes the temperature of adjacent LEDs to rise. Even if the adjacent LED operates at a relatively low (average) power, its temperature is determined not only by its relatively low energy consumption, but also by the heat generated by its neighbors. Now, the temperature of an LED (and therefore its relative light output) depends not only on its current power settings and its history of power settings, but also on the history of its neighbors' power settings and power settings. One way to overcome this problem is to provide an associated temperature measurement package for each LED [regardless of the system-direct temperature sensor or a sense ϋ for measuring the junction resistance. In this case, the control (4) can receive the individual 4 signals for the individual LEDs such that the (4) (4) can individually adapt their control signals to the individual LEDs to compensate for temperature effects. However, this is a very expensive solution 'although it does not work in any way: not proposed for the invention. According to the invention, the system! A model 1〇〇 is included which represents the thermal behavior of the coffee matrix 2 . This is illustrated in Figure 3. The file can be implemented with a hardware or software that receives the output signal 32 from the controller 30 as an input and generates an output signal 199 representative of the temperature of the LEDs; hereinafter, it will be explained with reference to FIG. Hardware implementation. The system further includes a memory 4 associated with the controller 30, which contains information about the photothermal behavior of 129529.doc -10-200904239 LED 10. For each LED, the thermal light system between the light output and the temperature d (then) / d (see Figure 2) is deprecated as TLC-

^ , , , a η β, Λ 乂 乂 乂 far. If all the LEDs are opposite each other, then all the thermo-optic coefficients ® σ ^ ^ are added to each other and the memory 40 needs to contain only one value Lc. Also, LED 10 ^ is that the memory 40 contains the individual values tlcx γ of the individual LEDs 1 〇χ γ. In the hardware model of the thermal model, an LED is represented as a node in a circuit. The system is in the

叼..., the machine is represented by a current that is turbulent in the circuit. The 埶 resistance can be ^ ^ ? "L _ θ ..., I is represented by a resistor, the 埶 capacity can be 藉 _ ',, ° ° to the heat input of an LED can be obtained by the 攸 current source The current supplied to the corresponding circuit node is indicated, and the thermal output of the LED can be represented by the current drawn from the corresponding circuit node by a snow-cooled motor source. Then, a circuit saves the voltage at the point, which represents the resulting temperature of the corresponding LED. Figure 4 is a circuit diagram showing a unit (8) of a hardware model corresponding to -LED1Gx, Y. In the unit (8), the node y represents a part of the backplane 3 corresponding to the LED 10, γ; the voltage V (103X'Y) at the node represents the temperature of the portion of the backplane 3. The heat capacity of the backplane portion is represented by a capacitor IB connecting the node 1〇3χ γ to ground. The heat exchange contact of the back plate portion with the adjacent plate portion is represented by resistors 141, 142, 143, 144 'which connects the node 1 〇 3 χ γ to the adjacent node 103X'Y-, 103 χ γ + 1 , γ, 1〇3χ+ι γ, adjacent nodes are shown in dotted lines in Figure 4, respectively. In addition to receiving heat from adjacent backplanes, the heat is released or the heat is released to the adjacent backplane. The backplane portion can release heat via light or convection, which is represented by a current source 15 ί connecting the node to ground. In the first approximation, the current drawn by the current source 1 5 1 can be considered to be L ^ you are solid. If more precision is required, this current source 151 can be a controllable current source controlled by the voltage at node 103 χ γ, which represents a heat loss 'the temperature difference between the back plate portion and its surroundings Proportion, but not shown in the figure. In the unit 101, a node 110x, Y represents the LED1〇XY; the voltage V(1i〇x, Y) at this node represents the temperature of the LEDi〇xy. The led 1 〇χ, γ heat capacity is represented by the capacitance 132 connecting the node iγ to ground. The LED 1Gx, Y has a heat exchange contact with the corresponding f-plate portion; this is represented by a resistor (4) that connects the node ι〇3χγ to the node ii〇x, Yl receives heat from the corresponding backplane portion or The heat is released to the corresponding backplane portion, which can dissipate heat via radiation or convection, which is represented by a current source 152 that connects the node 110, γ to ground. Again: in the first approximation, the current source 152 and the current drawn can be considered to be fixed. If more precision is required for the guest to touch, the current source 152 can be a - controllable current source 'controlled by the voltage on node 11Gxy, which represents a heat loss between the LED and its surroundings. The temperature difference is proportional, but is not shown in the figure. Last but not least, the LED is heated due to the energy lost from its operating current. This is represented by a current source 153 that connects this node ιι〇χγ to the supply voltage source vs. This current source 153 is a controllable current source that is controlled by control signal 32 or derives a signal from control signal 32. It should be noted that the hardware circuit representation of the model i 00 can be implemented with discrete components, but can also be implemented with an integrated circuit. However, in addition to the hard-implementation scheme, the model can be implemented in software and executed by a processor or a dedicated hardware class (e.g., microcontroller, microprocessor 4FGPA). The resistance value and the capacitor value can be stored as a fixed parameter in a memory. The voltage and current source values can be stored in a random access = memory after each calculation step and can be read from the random access memory before each calculation step. It should be further noted that the model 100 and the controller 3 can be integrated into one unit. In the hardware representation of Figure 4, the model continues to operate. In a software representation, the model operates step by step. In each step, a new voltage V(103x, Y) (ie, temperature) at node i〇hY (backplane) is calculated according to the formula V(103x, y)new~V(1〇3x, y)old+AVx,y, where AT, VR,.·, R ... P -/151 Similarly, a new voltage ν(11〇χγ) at the point ll〇XY(LED) (ie temperature) is based on The formula calculates V(1)〇χ yW which 1〇χ yWd+avl”中中中' 129529.doc -13- 200904239

AVL

Y (v(m)xy~v(n〇) r

R 145 + ’153 *~’l 52 c

J OLD

At 132 is correct, as long as the time step A t is small compared to the thermal time constant of the system. ▲In the above formula, the subscripts represent the components in the circuit of Figure 4, which should be apparent to those skilled in the art. Based on the output signal i 9 9 from the model i 该 该, the controller 3 knows the risk p bow of each individual LED 1 Οχ γ, and the moment τ χ, γ of 存 γ. Using the information in the memory 40, the controller 30 calculates the relative light output RL 〇 x'Y of each individual LED 〇 XY and adapts the control signal in a corresponding manner to compensate for the temperature effect j such as 'false 6 and based on input 3 The video intra-valley of the video signal received at i, the controller 3() calculates - the special mled1()x, y should produce 60% of its nominal light output, 杜, du ^ + ^ ^ Out. Further assume that from the model 1 〇〇 wheel out #号 1 99 for this particular LED 1 〇χ γ prediction / estimation of a momentary temperature 75 C progress false 堍 The graphical relationship represented by Figure 2 is applied to this particular I ^ ED 1〇χ γ. Gj, based on the calculation of the specific LED 10χ from the model (10) and the memory such as the received receiver, the γ has a relative light output of 8〇%, so that the controller 30 calculates the response. For this particular L^ED 1〇χ'γ produces a control output signal A y which results in a period of 75%. The resulting light output is then nominally light output 800 / 〇χ 750 / 〇 = 60% . The value of the LED is estimated to be the temperature of the LED of the matrix 2, and the present invention proposes to use the 杈 type 1 〇〇. For each LED 1 〇 xy , the model includes: - a first node ιιο χ, γ, which represents the lEd; 129529.doc 14 200904239 - a first capacitive component 131 connected to the first node, representing the thermal capacity of the LED - a second node 1 〇 3 χ γ 'which represents a portion of the backplane corresponding to the Led; - a second capacitive component 132 connected to the second node, representing the thermal capacity of the backplane portion; - one in the two a resistor assembly 丨45 between the nodes, which represents the thermal resistance of the thermal coupling between the lED and the backplane;

a resistor component 141, "2, 143, 144' between the second node 1〇3χ γ and an adjacent node, which represents thermal coupling between the backplane portion and an adjacent backplane portion Thermal resistance; brother '"丨L source component 1 5 3, presented i car 5 female Xu * αγ

Eight transports are connected to the younger brother, which represents the heat dissipation of the LED. of. It is preferable to consider the damage type. ..., 彳贝失' For this purpose, for each LED 10 χ, γ, the model 1 〇〇 preferably further comprises: - a second flow source component 丨 U, a basin ^ TED10 〃 connection To the first point, ιι〇χ, γ, represents the heat lost by the LED 1〇χ'γ via radiation or convection; the third flow source component 151 is connected to the second node 1〇3”, representing 兮The heat lost by radiation or convection in the back plate portion. w Although the present invention is not as depicted in the descriptions, those skilled in the art employ BB AL and 4, , , , , , The limitation "is not limited to the disclosed embodiments, and more specifically, a number of # κ ^ defined m may be within the scope of the invention as defined in the appended claims. 129529.doc 200904239 For example, if it is necessary to improve the accuracy, or if it is necessary to prevent errors from accumulating in the calculation, it is possible to add one (or some, in the appropriate strategic position of the structure (for example, in the backplane 3, the middle two) But basically only one) the actual temperature j detector. The temperature reading of this sensor should correspond to the temperature obtained from the model. If a difference occurs, it is easy to implement - the correction, in the software implementation of the model, in which case all voltage values (growth values) can be multiplied by the same correction factor to eliminate the difference. Further, the parameters of the model can be adapted to modify the calculations, such as the current sources 151, 152, 153. Example #, if the temperature of the sensor position actually increases more than the value predicted by the model, it is feasible to increase the current value of the current source 153. Further, in the above, electric dust is used to represent the temperature value. Because 4' can exist between the temperature in degrees Kelvin, the voltage in volts, the venge is ", the 4 factor, the 5 factor is not necessarily equal to - π). In particular, in the case of software calculations, it is possible to directly use the actual temperature value. This directly allows the person skilled in the art to implement the invention of the present invention and other changes to the present invention. In the request item, the "comprising" steps are not disclosed. The indefinite article: does not exclude other components or or "do not exclude plurals." A field device or other unit can achieve early processing in the request items. In the case of independent independence, the right-hand project does not indicate the combination of these methods: the pure facts of a particular method can be stored in a medium such as a storage medium or an I29529. Doc -J6 - 200904239 ~ The media is distributed in other forms along with or as part of other hardware, for example via the Internet or /, also the system. Any of the McCaw marks for the alpha or cable or the wireless channel shall not be construed as limiting the scope of the term. City 〗 〖Tongji μ seeking In the above, the present invention has been explained with reference to the block diagram. Private 昍外外# m 开,,,曰 is not very according to the functional block of the device. It should be understood that the function of this functional block can be realized by a single functional body, such as a part of the functional area, or by the use of the functional block, but it may also be used by the month. - or a plurality of such functional blocks, such that the functions of the functional blocks are implemented by one or more program modules of a computer program or a stylized device, such as a microprocessor, a microcontroller, a digital Signal processor, etc. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a backlight system; FIG. 2 is a diagram showing the relationship between the temperature of a lEd and its relative light output; FIG. 3 is a schematic diagram showing A block diagram of a model control based on one of the LED systems; FIG. 4 is a block diagram schematically showing an electronic circuit as a hardware embodiment of a portion of an LED control circuit in accordance with the present invention. [Main component symbol description]

1 Backlight System 2 Matrix 3 Backplane 1〇χ γ LED 129529.doc 200904239 20 L Ε D Driver 30 Controller 31 Input 32 Output Signal 40 Memory 100 Model 101 — Early 兀 1〇3χ, Υ Second Node 1〇3χ ), node 1 03 χ γ+ 1 node 1〇3χ., ιΥ node 103 χ+ι,γ node ΠΟχ, γ first node 131 first capacitor 132 second capacitor 141 resistor 142 resistor 143 resistor 144 Resistor 145 Resistor 151 Third Current Source 152 Dipole Current Source 153 First Current Source 199 Output Signal Vs Voltage Source 129529.doc -18

Claims (1)

200904239 X. Patent application scope: 1. A method for driving a lighting system (1), the system comprising a matrix (2) of LEDs (10) mounted on a backboard (3), the method comprising the following Steps: a) Provide information (40) 'which represents the relationship between the relative light output (RLO) and temperature (T) of each LED (10); b) Provide a model (1〇〇) that represents the matrix (2) thermal behavior; c) determining the required light output level of one of the LEDs; d) when using the model (1〇〇) provided in step b), calculate an estimate of the temperature of the individual LEDs of the matrix; e) when using the information (4〇) provided in step a) And calculating the relative light output (R1〇) of the individual LEDs of the matrix based on the temperature estimate calculated in step d); f) generating a control signal (32) for the one of the LEDs, compensating The resulting relative light output (RLO) is calculated in step e) to affect the desired light output level determined in step c). 2. If you are asking for it! a method in which the action time cycle for a ud-control signal 匕 (32) in step f) is calculated as the corresponding desired light output level divided by the relative light wheel calculated in step e) The desired light output level of the output (LO) 4 is expressed as a percentage of the nominal light output bit. Thousands of the model 3. The method of claim 1 (U) includes: where for each LED (l〇x, Y) first - lang (11 〇 x, Y), which represents the LED (10X Y); 129529.doc 200904239 - a first capacitor component (131) connected to the first node (11 〇χ, γ) 'represents one of the LED (10X, Y) heat capacity; - a first lang point (1 〇 3χ, γ) 'which represents a portion of the back panel (3) corresponding to the LED (10X, Y); a second capacitor component (132) connected to the second node (1 03χ, γ) 'representing one of the heat capacity of the back plate portion; - a resistance component (145) between the two nodes (11 〇χ γ; 1 〇 3 χ γ), which represents between the LED (10 〇 XY) and the back plate a thermal coupling < a thermal resistance; - between the second node (l〇3X Y) and the adjacent second node (1〇3χ γ ι, 1〇3χ, γ+1, 1〇3χ_〗, γ a resistor component (141, 142, 143, 144) between l〇3x + 1Y), which represents the LED corresponding to the LED (the portion of the backplane (3) corresponding to the respective adjacent led (1〇xy 1, Μ, ΙΟχιυ, 10χ+1, γ) Thermal coupling between the thermal resistance of the portion; a first flow source component (153) connected to the first node (103χ, γ)' represents heat dissipation of the LED (l〇x γ). The use of a model (100) represents the thermal behavior of a matrix (2) of LEDs (IO) mounted on a backplane (3) to estimate the temperature of individual LEDs of the matrix and to calculate the compensated drive signal (32) such that they produce a desired light output. 5. For the purpose of claim 4 '# for each led (d, the model (100) includes: 'the first point (110χ, γ), which represents the LED (10X Y); 129529.doc 200904239 - a first capacitor component (131) connected to the first node (11〇χ, γ), representing a heat capacity of the LED (10〇XY); _ a second node (1〇3χ, γ), Representing a portion of the backplane (3) corresponding to the LED (10X, Y); a second capacitor component (132) connected to the second node (1〇3χ, γ)' representing the backplane portion a heat capacity; - a resistance component between the two nodes (110 χ γ; 1 〇 3 χ γ) ^ (145) 'which represents a thermal coupling between the LED (10X, Y) and the backplane One of the thermal resistances; - the resistance between the second node (103χ, γ) and the adjacent second node (1〇3χ γ ι, 103χ, γ+丨, 103η γ, ι〇3χ+ γ) The component (141, 142, 143, 144) 'which represents the portion of the backplane (3) corresponding to the LED (10X, Y) and corresponds to the respective adjacent led (1〇XsY.i, 1〇χ, γ+ι, 1 Ox-ly, 10χ+1, γ) adjacent to each other The thermal coupling between the thermal couplings; j _ a first current source component (153) connected to the first node (103χ, γ) 'represents the LED (1〇x 散热 heat dissipation. 6. A lighting system (1 ), comprising: - a matrix (2) of lED (10) mounted on a backplane (3); - a controller (3 〇) designed to generate one of the controls for the lEd Signal (32); - a memory (40) containing information representative of the relationship between relative light output (RLO) and temperature (τ) of each LEE) (i); • a model (100), It represents the thermal behavior of the matrix (2); 129529.doc 200904239 wherein the model receives the control signals (32) generated by the controller (3 作为) as input signals; and wherein the controller (30) receives An output signal (199) of the model, the output signal (199) indicating an estimate of the temperature of the individual LEDs of the matrix. 7. The system of claim 6, wherein the controller (3) is designed to determine The desired light output level of one of the LEDs; wherein the controller (30) is designed to use information from the memory (4〇) And calculating a relative light output (rl〇) of the individual LEDs of the matrix based on the output signals from the model (丨99); and wherein the controller (30) is designed to generate the LEd for the LED The control signals (32) 'compensate the calculated relative light output (RLO) of the individual LEDs. 8. The system of claim 6 wherein the controller (3〇) is designed to determine a desired light output level for one of the LEDs as a percentage of a nominal light output level; wherein the control The device (30) is designed to generate an active time cycle control signal (32) for the LEDs having an active time cycle equal to the respective desired light output level; wherein the "Hai controller (30) is designed to be used Information from the memory (40) and based on the output signals (199) from the model, calculating the relative light output (RLO) of individual LEDs such as the matrix; and wherein the controller (30) is The control is applied to the LEDs of the LEDs (32) to compensate for the calculated relative light output (RL〇), which is maintained at 129529.doc 200904239. 9. 10. The system of Requirement 8 of the Requirement 8 is designed to adjust the controls applicable to the LEDs for the lack of currency. It is (32)' that the cycle of the action time of the control ί» (32) for -LEC is calculated as the corresponding relative light output (RLO) divided by the corresponding desired light output level. The system of claim 6 wherein the model (10) is implemented in the software of the controller. 11. The system of claim 6 is applied to where the model (100) is implemented by hardware. The system of claim 6 is as follows: TCMW 1 Λ, 斗” 丫 for the mother-LED (10x, y), the model (1〇〇) includes: '- a first node (ιι〇χγ), which represents the lED (1〇xy); a first capacitive component (131) connected to the first a node (ΙΙΟχ, γ) representing a heat capacity of the LED (10〇XY); a first point (103χ, γ) representing the backplane (3) corresponding to the LED (10X, Y) a portion; a second capacitor component (132) connected to the second node (1〇3χ, γ), representing a heat capacity of the backplane portion; at the two nodes (110χγ; 1〇3χγ) a resistor assembly (145), which represents a thermal resistance of a thermal coupling between the LED (丨〇χ γ) and the backplane; - at the second node of δ hai (ι〇3χ, γ) and phase a resistance component (141, 142, 143, 144) between the adjacent second node (1〇3χ n, 1〇3χ, γ+丨, 1〇3Χ-1γ, l〇3x + I γ), the representative of which corresponds to The led (1〇xy:^ the backplane 129529.doc 20090423 Thermal coupling between this portion of 9 and the respective adjacent backplane portions corresponding to their respective adjacent LEDs (1〇x, yi, 1〇χ, γ + 1, 1〇x-uy, 10χ+1, γ) a thermal resistance; a first current source component (153) connected to the first node (ι〇3χ γ), representing heat dissipation of the LED (10X, Y). 13. The system of claim 12, wherein The first source component is a controllable component. 14. The use of claim 12, wherein for each gamma, the model (100) further comprises: - a second stream component (丨 52) Connected to the first node (χ'γ), representing heat lost by the LED (10x, Y) via radiation or convection; a third flow source component (151) connected to the second node (103x, y) 'Represents the heat lost by the light or convection of the backplane portion. 15' A backlight system for a (four) panel comprising - the illumination system of any one of claims 6 to 14. 129529.doc