TW202027557A - Arbitrary-ratio analog current division circuit and method of current division - Google Patents

Abstract

In various embodiments, a device and method of dividing current among LED arrays is described. Each array has a sense resistor to sense a voltage of a current channel associated with the array. An analog or digital computational circuit with an op-amp and parallel RC circuit or microprocessor compares the voltages of the sense resistors and controls switches of the arrays accordingly. The analog circuit charges or discharges the capacitor to alter the output voltage used to control the switches. The microprocessor determines a ratio of the sensed voltages to generate the output voltage, maps a control signal to the ratio, directs input current to one or the other channel dependent on the control signal voltage and otherwise scales the input current between the channels. Other apparatuses, devices, and methods are described as well.

Description

Arbitrary ratio analog current distribution circuit and current distribution method

The present invention relates to a distribution circuit, and more specifically relates to an analog current distribution circuit.

A light emitting device (LED) or electroluminescent device (ELD) circuit that can divide a current into two or more channels of equal or unequal proportions provides specific advantages. For example, multiple LED channels of different colors can share a single-channel LED driver in a correlated color temperature (CCT) tuning system without the need for a multi-channel DC/DC converter.

Generally speaking, there are two current distribution methods. The first method is a time-sharing method. In the time-sharing method, each channel conducts the full amplitude of the input current in the allocated time slot. The second method is to divide the current by amplitude. The second method operates in the analog domain and generates multiple currents with small amplitudes. The sum of the small amplitudes is equal to the amplitude of the input current. Dividing a current by amplitude provides specific advantages, including but not limited to avoiding switching noise and maximizing LED utilization, thereby improving efficiency.

Generally speaking, parallel LED arrays are used to achieve analog current distribution among LEDs. Resistors are connected in series on each array to linearize the forward voltage. The parallel LED arrays are preferably driven by equal currents to avoid current hogging. Therefore, the current must be divided into equal proportions and the system can only handle a very limited amount of mismatch between parallel LED arrays.

It would be beneficial to provide an LED circuit capable of dividing a current into two or more channels via parallel LED arrays (where the current is divided into an arbitrary ratio) and handling a large mismatch between the parallel LED arrays.

The present invention provides a circuit and method for dividing a single current source into two or more current channels. The circuit and method of the present invention allow a single current source to be divided into any ratio and can tolerate a large mismatch between the current channels.

This application claims the priority of the U.S. Patent Application No. 16/145,053 filed on September 27, 2018 and the European Patent Application No. 18209861.6 filed on December 3, 2018. The full text of each of these cases is incorporated by reference. Incorporated into this article.

In the following description, numerous specific details such as specific structures, components, materials, dimensions, processing steps, and techniques are described to provide a thorough understanding of the embodiments of the present invention. However, those of ordinary skill will understand that the embodiments can be practiced without such specific details. In other examples, well-known structures or processing steps have not been described in detail to avoid obscuring the embodiments. It will be understood that when an element such as a layer, region, or substrate is referred to as being "on" or "over" another element, it can be directly on the other element or an intervening element may also be present. In contrast, when an element is referred to as being "directly on" or "directly" on another element, there is no intervening element. It will also be understood that when an element is referred to as being "under", "under" or "under" another element, it can be directly under or under the other element or an intervening element may be present. In contrast, when an element is referred to as being "directly under another element" or "directly under another element," there is no intervening element.

In order not to make the presentation of the embodiments in the following detailed description unclear, some processing steps or operations known in the art may have been combined for presentation and drawing purposes, and some examples may not be described in detail. . In other cases, some processing steps or operations known in the art may not be described at all. It should be understood that the following description focuses fairly on the distinguishing features or elements of the various embodiments described herein.

This article describes the use of LEDs. However, one or more types of semiconductor-based light emitting devices or optical power emitting devices can be used in the embodiments described herein. These devices may include resonant cavity light emitting diodes, vertical cavity laser diodes, edge-emitting lasers, or the like. These devices can be used in a variety of applications, including as light sources for handheld battery-powered devices (such as cameras and cellular phones) (for example, flashlights and camera flashes), automotive lighting, head-up displays (HUD) Lighting, garden lighting, street lighting, one-video flashlight, general lighting (for example, home, shop, office and studio lighting, theater/stage lighting and architectural lighting), augmented reality (AR) lighting, virtual reality ( VR) lights, as backlights for displays, and for IR spectroscopy.

In some embodiments, a single LED can provide light that is not as bright as an incandescent light source. In these embodiments, when enhanced brightness is desired or required, certain applications may use multi-junction devices or LED arrays (such as monolithic LED arrays, micro LED arrays, etc.).

The color appearance of an object is determined in part by the spectral power density (SPD) of the light that illuminates the object. For people watching an object, SPD is the relative intensity of various wavelengths in the visible spectrum. However, other factors may also affect the color appearance. The distance between a correlated color temperature (CCT) of a lamp (for example, LED) and a distance between the LED temperature on the CCT and a black body line (BBL, also known as a black body locus or Planckian locus) can affect a person Perception of an object. In particular, such as in retail and hotel lighting applications, there is a huge market demand for LED lighting solutions, in which it is desired to control both the color temperature and the brightness level of the LED.

Refer to Figure 1, which shows a chromaticity diagram representing a color space. A color space is a three-dimensional space; that is, a color is specified by a set of three numbers specifying the color and brightness of a specific uniform visual stimulus. The three numbers can be the International Commission on Illumination (CIE) coordinates X, Y, and Z, or other values such as hue, hue, and illuminance. Based on the fact that the human eye has three different types of color sensitive cones, the response of the eye is best described based on the three "tristimulus values".

A chromaticity diagram is a color projected into a two-dimensional space, ignoring brightness. For example, the standard CIE XYZ color space is directly projected to the corresponding chromaticity space specified by two chromaticity coordinates called x and y, as shown in Figure 1.

Chroma is an objective specification of the quality of a color, and has nothing to do with its illuminance. Chroma consists of two independent parameters usually designated as hue and hue, where hue is alternatively called saturation, chroma, intensity or excitation purity. The chromaticity diagram can include all colors perceivable by the human eye. The chromaticity diagram can provide high accuracy because the parameters are based on the SPD of the light emitted from a colored object and are factored according to the sensitivity curve measured for the human eye. Any color can be accurately represented based on two color coordinates x and y.

All the colors in a specific area called a MacAdam ellipse (MAE) 102 are indistinguishable from the color at the center 104 of the ellipse for ordinary human eyes. The chromaticity diagram can have multiple MAEs. The standard deviation color matching in LED lights uses the deviation from the MAE to describe the color accuracy of a light source.

The chromaticity diagram contains Planckian locus or BBL 106. BBL 106 is a path or track that the color of an incandescent black body will occupy in a specific chromaticity space as the temperature of the black body changes. It changes from deep red at low temperatures to orange, yellow-white, white, and finally to bluish white at extremely high temperatures. Generally speaking, the human eye prefers a white color point that is not too far from the BBL 106.

In various environments where LEDs are used for lighting objects and for general lighting, in addition to the relative brightness (for example, luminous flux) of one of the lamps, it is also desirable to control the color temperature of the LED. Such environments may include, for example, retail locations and hotel locations, such as restaurants and the like. In addition to CCT, another measurement is the color rendering index (CRI) of light. CRI is defined by CIE and it provides a certain measure of the ability of any light source (including LED) to accurately present one of the colors of various objects compared with an ideal or natural light source. The highest possible CRI value is 100. Another quantitative measurement is D _uv . D _uv is defined in, for example, CIE 1960 to indicate the distance between a color point and the BBL 106. If the color point is above the BBL 106, it is a positive value, and if the color point is below the BBL 106, it is a negative value. The color point above BBL 106 is green and the color point below BBL 106 is pink.

As mentioned above, human eyes prefer the white color point that is relatively close to the BBL 106. One method of using a light emitting diode (LED) to generate white light can be to superimpose and mix red, green, and blue light. However, this method may need to accurately calculate the mixing ratio so that the resulting color point is on or close to the BBL 106. Another method may be to mix two or more phosphor-converted white LEDs with different correlated color temperatures (CCT). This method is described in additional detail below.

To produce a tunable white light engine, LEDs with two different CCTs on each end of a desired tuning range can be used. For example, a first LED may have a CCT of 2700K (which is a warm white), and a second LED may have a color temperature of 4000K (which is a neutral white). It can be obtained by simply changing the mixing ratio of the power supplied to the first LED through a first channel of a driver and the power supplied to the second LED through a second channel of the driver to obtain a value between 2700K and 4000K One temperature white.

Now refer to FIG. 2, which shows a diagram showing the relationship between different CCTs and the BBL 106. When plotting in the chromaticity diagram, mixing the achievable color points of two LEDs with different CCTs can form a first straight line 202. Assuming that the color points of 2700K and 4000K are exactly on the BBL 106, the color point in the middle of the two CCTs will be below the BBL 106. This is not a problem because the maximum distance between the point on this line and the BBL 106 can be relatively small.

方程式(1)Dividing a current sink or current source into N channels essentially generates N current sinks or N current sources. According to Kirchhoff's current laws, the sum of all currents flowing to a node must be zero. Therefore, at any node in a circuit, the sum of currents flowing into that node is equal to the sum of currents flowing out of that node. In other words, the algebraic sum of the currents in a network of conductors that meet at one point is zero. This principle can be stated as the following equation:

Equation (1)

However, in practice, it is almost impossible to generate N regulated currents whose sum is exactly equal to the divided input current. This is because generally speaking, the input current is unknown.

3, which shows a circuit diagram of a current distribution circuit 300. The current distribution circuit 300 utilizes various analog techniques, such as voltage sensing, voltage controlled current source, and negative feedback.

As described in more detail below, the current distribution circuit of the present invention can divide an input current into two or more current channels. The current distribution circuit of the present invention includes at least one regulating current channel, and the number of regulating current channels is less than one of the total number of current channels. For example, if there are a total of three current channels, there may only be two regulated current channels.

In one embodiment, the current distribution circuit can be mounted between an LED driver 301 and an LED board on a converter printed circuit board (PCB). The LED driver 301 may be a conventional LED driver known in the art. The current distribution circuit may allow the LED driver 301 to be used in applications that require each of two or more LED arrays, or one or more LEDs. For example, the LED driver 301 of the current distribution circuit 300 can be used to supply power to a first LED array 311 and a second LED array 321.

In one embodiment, the LED driver 301 is used to supply power to two LED arrays with different CCTs. In other embodiments, the two LED arrays may have different color ranges, infrared (IR) ranges and ultraviolet (UV) ranges.

Each current channel of the current distribution circuit includes a sensing resistor. For example, in an embodiment with two current channels, the current distribution circuit includes a first sense resistor (R _{s1) for} sensing a first sense voltage of the first current channel 310 at V _sense1 313 ) 312, and a second sense resistor (R _s2 ) 322 for sensing a second voltage of the second current channel 320 at V _sense2 323. The voltage at V _sense1 313 represents the current flowing through the first sensing resistor (R _s1 ) 312, and the voltage at V _sense2 323 represents the current flowing through the second sensing resistor (R _s2 ) 322.

The current distribution circuit 300 of the present invention further includes an arithmetic device (not shown). The arithmetic device is configured to compare the first sensing voltage (V _sense1 ) 313 and the second sensing voltage (V _sense2 ) 323 to determine a set voltage (V _set ) 350. If the first sensing voltage (V _sense1 ) 313 is lower than the second sensing voltage (V _sense2 ) 323, the computing device is configured to increase V _set . If the first sensing voltage (V _sense1 ) device is greater than the second sensing voltage (V _sense2 ) 323, the computing device is configured to reduce the set voltage (V _set ) 350.

The set voltage (V _set ) 350 can be fed to a voltage-controlled current source, which can be implemented by a first operational amplifier (opamp) 330. The first opamp 330 can provide a first gate voltage (V _g1 ) 314. The first gate voltage (V _g1 ) 314 can be input to a first transistor (M1) 315 used to provide a driving current for the first LED array 311. The first transistor (M1) 315 can be a conventional metal oxide semiconductor field effect transistor (MOSFET). The first transistor M1 can be an n-channel MOSFET. It should be noted that although MOSFETs are mentioned, one or more of the transistors described herein can be other types of FETs or bipolar junction transistors (BJT). In some embodiments, other circuits may be used to provide switching of one or more of the switches.

A second transistor (M2) 325 can control the power to the second LED array 321. The second transistor (M2) 325 can be a conventional metal oxide semiconductor field effect transistor (MOSFET). The second transistor M2 can be an n-channel MOSFET. The second transistor (M2) 325 may be turned on only when the first circuit channel 310 is under adjustment. A second gate voltage (V _g2 ) 324 can flow through the second transistor (M2) 325.

The second gate voltage (V _g2 ) 324 can be fed to a REF input terminal of a shunt regulator 340. In one embodiment, the shunt regulator 340 has an internal reference voltage of 2.5V. When the voltage applied to the REF node is higher than 2.5 V, the shunt regulator 140 can sink a large current. When the voltage applied to the REF node is lower than 2.5 V, the first shunt regulator can draw a very small quiescent current.

The larger current draw can pull down the gate voltage of the second transistor (M2) 325 to a level lower than its threshold, which can turn off the second transistor (M2) 325. The shunt regulator 340 may not be able to pull its equal cathode to exceed the forward voltage (V _f ) of a diode below its equal REF node. Therefore, the second transistor (M2) 325 may have a threshold voltage higher than 2.5V. Alternatively, a shunt regulator with a lower internal reference voltage (such as 1.24 V) can be used.

Referring to FIG. 4, the computing device may be an computing circuit 400. The arithmetic circuit 400 may include a second opamp 430, a capacitor 440 between the position of the set voltage (V _set ) 350 and ground, and a resistor 450 in parallel with the capacitor 440. The first sensing voltage (V _sense1 ) 313 and the second sensing voltage (V _sense2 ) 323 are fed to the second opamp 430. The operation circuit 400 may be configured to compare the first sensing voltage (V _sense1 ) 313 with the second sensing voltage (V _sense1 ) 313 by subtracting the first sensing voltage (V _sense1 ) 313 from the second sensing voltage (V _sense2 ) 323 Voltage (V _sense2 ) 323.

When the time, the second arithmetic circuit in the opamp 430 may be adjusted 400 when the first 323 configured to sense voltage _(V sense1 in a first sense voltage _(V sense1) is smaller than a second sense voltage _(V sense2) 313 The difference between) 313 and the second sensing voltage (V _sense2 ) 323 is converted into a charging current, and the capacitor 440 is charged to increase the set voltage (V _set ) 350. The arithmetic circuit 400 can be configured to compare the first sensing voltage (V _sense1 ) 313 with the second sensing voltage (V _sense1 ) 313 when the first sensing voltage (V _sense1 ) 313 is greater than the second sensing voltage (V _sense2 ) 323 The difference between _sense2 ) 323 is converted to a discharge resistor 450 to reduce the set voltage (V _set ) 350.

方程式(2)

方程式(3)Therefore, if the first sensing voltage (V _sense1 ) 313 is higher than the second sensing voltage (V _sense2 ) 323, the arithmetic circuit 400 can reduce the set voltage (V _set ) 350, which in turn reduces the power supplied to the first The first gate voltage (V _g1 ) 314 of a current channel 310. In other words, when the second opamp 430 is being adjusted, the first sensing voltage (V _sense1 ) 313 is approximately equal to the second sensing voltage (V _sense2 ) 323. Therefore, during the steady state, the ratio of the current of the first current channel 310 to the current of the second current channel 320 is equal to the value of the second sensing resistor (R _s2 ) 322 and the first sensing resistor (R _s1 ) 312 The ratio of the value of and satisfies the following equation:

Equation (2)

Equation (3)

Therefore, when the value of the first sensing resistor (R _s1 ) 312 is equal to the value of the second sensing resistor (R _s2 ) 322, the current (I _Rs1 ) flowing through the first resistor is equal to the value flowing through the second resistor The current of the device (I _Rs2 ), and the current distribution circuit 300 divides the current into two equal parts, assuming that the current drawn by the auxiliary circuit (such as the supply voltage) is negligible.

It should be noted that the closed loop behavior and stability of the arithmetic circuit 400 should be tested and adjusted accordingly.

It should be further noted that, as those of ordinary skill will appreciate, the arithmetic circuit 400 shown in FIG. 4 is one of many possible implementations.

As previously described, the current distribution circuit 300 may be divided into three or more channels. For example, the first current channel 310 can be duplicated so that there is a first current channel, a second current channel, and a third current channel. The first current channel and the second current channel will be regulated current channels, such as the first current channel 310 of the current distribution circuit 300 shown in FIG. 3. The third current channel will not be adjusted and will be similar to the second current channel 320 of the current distribution circuit 300 shown in FIG. 3.

It should also be noted that for a circuit division circuit that divides a current source into three or more current channels, the arithmetic circuit 400 shown in FIG. 4 may become complicated. Therefore, a microcontroller can be used to replace the arithmetic circuit shown in FIG. 4.

方程式(4)Referring to FIG. 5, in one embodiment, the computing device may be a microcontroller 500, which can handle complex signal processing with fewer PCB resources than analog circuits. The microcontroller 500 uses its internal ADC to digitize three analog signals: a first sensing voltage (V _sense1 ) 313, a second sensing voltage (V _sense2 ) 323, and a control signal 501. When the value of the first sensing resistor (R _s1 ) 312 and the value of the second sensing resistor (R _s2 ) 322 are known, the following equation is used to determine the total input current:

Equation (4)

Referring to FIG. 6, a ratio of the first sensing voltage (V _sense1 ) 313 to the second sensing voltage (V _sense2 ) 323 is adjusted by a control signal 501 of the microcontroller. The microcontroller calculates the ratio of the first sensing voltage (V _sense1 ) 313 to the second sensing voltage (V _sense2 ) 323. The control signal 501 is mapped to the ratio of the first sensing voltage (V _sense1 ) 313 to the second sensing voltage (V _sense2 ) 323. When the control signal 501 is less than or equal to a first predetermined voltage 601, all input currents are directed to the first current channel. When the control signal 501 is greater than or equal to a second predetermined voltage 602, all input currents are directed to the second current channel. When the control signal 501 is between the first predetermined voltage 601 and the second predetermined voltage 602, the current can be adjusted linearly and proportionally between the first current channel and the second current channel. The current can also be adjusted proportionally according to other curves and inflection points. For example, between the first predetermined voltage 601 and the second predetermined 602 threshold, the current may be stepped to provide step control.

In an embodiment, the control signal 501 has a range of 0 V to 10 V, and the first predetermined voltage is 1 V and the second predetermined voltage is 8 V. Therefore, when the 0 V to 10 V control signal is less than or equal to 1 V, all input current flows to the first current channel. When the 0 V to 10 V signal is greater than or equal to 8 V, all input current flows to the second current channel. When the 0 V to 10 V signal is between 1 V and 8 V, the current is adjusted linearly and proportionally between the two channels.

The selection of the value of the first resistor (R _s1 ) 312 and the value of the second resistor (R _s2 ) 322 is a trade-off between resolution and power consumption. For the same current, the higher the value of the first resistor (R _s1 ) 312 and the value of the second resistor (R _s2 ) 322 are, the higher the value of the first sensing voltage (V _sense1 ) 313 and the second sensing voltage (V _sense2 ) 323 is higher. A higher first sense voltage (V _sense1 ) 313 and second sense voltage (V _sense2 ) 323 allow the use of cheaper and less accurate circuits at the cost of increased power loss and reduced efficiency. If the value of the first resistor (R _s1 ) 312 is too large, it may be necessary to select a larger MOSFET to have a lower internal resistance (Rds(on)). Additionally or alternatively, if the value of the first resistor (R _s1 ) 312 is too large, it may be necessary to have a higher supply voltage (V _dd ), which makes it necessary to select signal processing that can operate at a higher voltage Circuit. This can potentially increase the cost of the circuit.

It should be noted that the well-known structures (including one or more resistors, diodes, and capacitors) and processing steps shown in FIGS. 3 and 4 are not described in detail to avoid obscuring the embodiments described herein.

Referring now to FIG. 7, it shows a flow chart of an analog circuit division method. In step 701, an input current is received from a voltage controlled current source such as an LED driver. In step 702, a first sensing voltage of a first current channel is sensed. In step 703, a second voltage of a second current channel is sensed. In step 704, the first sensing voltage and the second sensing voltage are compared to determine an output voltage. In step 705, if the first sensing voltage is lower than the second sensing voltage, the output voltage is increased. If the first sensing voltage is higher than the second sensing voltage, the output voltage decreases. In step 706, the output voltage is provided to the first current channel to power a first LED array. In step 707, the remaining current after the first LED array has obtained its share is automatically provided to the second current channel to power a second LED array.

The method shown in FIG. 7 can be executed by the current distribution circuit 300 using the arithmetic circuit 400 shown in FIG. 4. For example, in step 701, an input current can be received from the LED driver 301. In step 702, the first sensing resistor (R _s1 ) 312 can sense a first sensing voltage (V _sense1 ) 313 of the first current channel 310. In step 702, the second sensing resistor (R _s2 ) 322 can sense a second sensing voltage (V _sense ) of the second current channel 320. In step 704, the first sensing voltage (V _sense1 ) 313 and the second sensing voltage (V _sense2 ) 323 can be fed to the second op amp 430 of the arithmetic circuit 400, and the second op amp 430 is _passed from the second op amp 430 The sensing voltage (V _sense2 ) 323 subtracts the first sensing voltage (V _sense1 ) 313 to compare the first sensing voltage (V _sense1 ) 313 with the second sensing voltage (V _sense2 ) 323. In step 705, the arithmetic circuit 400 may combine the first sensing voltage (V _sense1 ) 313 with the second sensing voltage (V _sense1 ) 313 when the first sensing voltage (V _sense1 ) 313 is less than the second sensing voltage (V _sense2 ) 323 The difference between _sense2 ) 323 is converted into a charging current to charge the capacitor 440 to increase the set voltage (V _set ) 350. In particular, when the first sensing voltage (V _sense1 ) 313 is less than the second sensing voltage (V _sense2 ) 323, the voltage supplied to the MOSFET shown in FIG. 4 starts the MOSFET (that is, the MOSFET can be in an on state ), which causes the source and drain of the MOSFET to be connected and causes V _{set to} increase until reaching a steady-state ratio of the voltage divider output between the source resistor 450 and the drain resistor or the MOSFET is deactivated (at this time , The capacitor 440 is substantially discharged to the ground through the source resistor 450). In addition, when the first sensing voltage (V _sense1 ) 313 is greater than the second sensing voltage (V _sense2 ) 323, the arithmetic circuit 400 can deactivate the MOSFET as described above and allow the capacitor 440 to discharge through the resistor 450 to discharge the first The difference between a sense voltage (V _sense1 ) 313 and a second sense voltage (V _sense2 ) 323 is converted into a discharge current to reduce the set voltage (V _set ) 350. Then, the set voltage (V _set ) 350 can be supplied to the first current channel 310 to supply power to the first LED array 311. The current remaining after the first LED array 311 has obtained its share is automatically provided to the second current channel 320 to supply power to a second LED array 321.

Referring now to FIG. 8, it shows a flow chart of an analog circuit division method performed by a current distribution circuit including a microcontroller. In step 801, an input current is received from a voltage controlled current source such as an LED driver. In step 802, a first sensing voltage of a first current channel is sensed. In step 803, a second voltage of a second current channel is sensed. In step 804, a ratio of the first sensing voltage to the second sensing voltage is determined. In step 805, a control signal is mapped to the ratio of the first sensing voltage to the second sensing voltage. In step 806, when the signal is less than or equal to a first predetermined voltage, all input currents are directed to the first current channel. If the signal is greater than or equal to a second predetermined voltage, all input currents are directed to the second current channel. If the signal is between the first predetermined voltage and the second predetermined voltage, the current is adjusted proportionally between the first current channel and the second current channel.

The method shown in FIG. 8 can be executed by the current distribution circuit 300 using the microcontroller 500 shown in FIG. 5. For example, in step 801, an input current can be received from the LED driver 301. In step 802, the first sensing resistor (R _s1 ) 312 can sense a first sensing voltage (V _sense1 ) 313 of the first current channel 310. In step 803, the second sensing resistor (R _s2 ) 322 can sense a second sensing voltage (V _sense ) of the second current channel 320. In step 804, the first sense voltage (V _sense1 ) 313, the second sense voltage (V _sense2 ) 323 and the control signal 501 are fed to the microcontroller 500, and the microcontroller 500 determines the first sense voltage (V _sense1 ) 313 and a ratio of the second sensing voltage (V _sense2 ) 323. In step 805, the microcontroller maps the ratio of the first sensing voltage (V _sense1 ) 313 to the second sensing voltage (V _sense2 ) 323. In step 806, the microcontroller directs all input current to the first current channel 310 when the signal is less than or equal to a first predetermined voltage 601, and when the control signal 501 is greater than or equal to a second predetermined voltage 602 The entire input current is directed to the second current channel 320, and is proportional between the first current channel 310 and the second current channel 320 when the control signal 501 is between the first predetermined voltage 601 and the second predetermined voltage 602 Adjust the current.

Therefore, the disclosed subject matter relates to controlling the luminous flux (eg, "brightness level") of the LED array to control an overall intensity level of the ELD or LED array in combination with various embodiments of the disclosed subject matter. However, in other embodiments, both the color temperature and the distance from the BBL 106 (CCT and _Duv ) are controllable. In addition to using two or more CCT white LEDs, a combination of red/green/blue/amber LEDs or a combination of red/green/blue LEDs can also be used. In the latter case, color tuning is rarely provided as a usable function; instead, users are usually provided with a color wheel based on a red-green-blue (RGB) or hue-saturation-lightness (HSL) model. However, RGB and HSL models are not designed for general lighting/white light generation, and they are more suitable for graphics or photography applications.

Color tuning (covering one or both of CCT and D _uv ) applications can be used to drive various colors of LEDs, including, for example, primary colors (red-green-blue or RGB) LEDs, or de-saturated (soft) RGB color LEDs. A high CRI and high efficiency to produce light of various color temperatures, specifically the use of phosphor-converted color LEDs to solve color mixing. The de-saturation LED has a light emission close to the BBL, as shown in FIGS. 9A to 9C, which show other chromaticity diagrams representing a color space. It should be noted that in the color mixing used to generate white light, the forward voltage of the direct color LED decreases as the dominant wavelength increases. In some embodiments, in addition to the above embodiments, a multi-channel DC-to-DC converter can also be used to drive the LED. Advanced phosphor-converted color LEDs that target high efficiency and CRI can be used. These LEDs have a saturated color point and can be mixed to achieve a white color with 90+ CRI in a wide CCT range. Other LEDs with 80+ CRI implementation or even 70+ CRI implementation (or even lower CRI value) can also be used.

As known by the ordinary artisan, since the light output of an LED is proportional to the amount of current used to drive the LED, dimming the LED can be achieved by, for example, reducing the forward current delivered to the LED. In addition to changing the amount of current used to drive each of several individual LEDs or instead of changing the amount of current used to drive each of several individual LEDs, a control unit or other types of multiplexers, switching devices, or in this technology Known similar devices can quickly switch the selected LEDs of one or more of the LEDs in the array between the "on" and "off" states to achieve proper dimming and color temperature level of the selected array.

Generally speaking, an analog driver method or a pulse width modulation (PWM) driver method can be used to form the LED driving circuit. In an analog drive method, all colors are driven at the same time. By providing a different current for each LED, each LED or LED array (hereinafter only referred to as LED) is independently driven. The analog driver causes a color shift. In a PWM driver, each color is turned on sequentially at high speed. Drive each color with substantially the same current. Control the mixed color by changing the time cycle of each color. That is, the driving time of one color can be twice that of another color to be added to the mixed color. Because human vision cannot perceive extremely rapid changes to color, light appears to have a single color. It should be noted that this can also be used to generate white light when each group of RBG LEDs is activated in the same way.

For example, a first LED (of a first color) is periodically driven with a current for a predetermined amount of time, and then a first LED (of a second color) is periodically driven with the same current for a predetermined amount of time. Two LEDs, and then a third LED (of a third color) is periodically driven with current for a predetermined amount of time. Each of the three predetermined amounts of time may be the same amount of time or different amounts of time. Therefore, the mixed color can be controlled by changing the time cycle of each color. For example, if we have an RGB LED and expect a specific output, based on the perception of the human eye, we can drive red in one part of the cycle, green in a different part of the cycle, and blue in another part of the cycle . Instead of driving the red LED with a lower current, the red LED is driven with substantially the same current in a shorter time.

It should be noted that the desaturation RGB method can generate tunable light above and below the BBL and on the BBL (for example, an isothermal CCT line (described below)) while maintaining a high CRI. In contrast, various other systems utilize a CCT method in which the tunable color point falls on one of the straight lines between the two primary colors of the LED (for example, R-G, R-B, or G-B). Referring back to Figure 2, any color point on an isotherm of the BBL 106 has a constant CCT.

As above, referring to FIG. 1, each ellipse of the CIE color map represents a MAE 102 centered on the BBL 106 and extends from the BBL 106 by one or more distance steps. Because MAE 102 contains all colors that are indistinguishable from one of the colors at the center of the ellipse for a typical observer, each of the MAE steps is considered to be at the center of each of the MAEs for a typical observer One of the colors is essentially the same color. Therefore, the isotherm of the BBL 106 represents a substantially equal distance from the BBL 106 and is related to the value of D _uv (for example, +0.006, +0.003, 0, -0.003, and -0.006).

The chromaticity diagram 900 shown in FIG. 9A has approximate chromaticity coordinates of colors with typical coordinate values (as shown on the xy scale of the chromaticity diagram). For a red (R) LED, at x = about 0.69 and y = At about 0.29 (coordinate 901), for a green (G) LED, at x = about 0.12 and y = about 0.73 (coordinates 903), and for a blue (B) LED, at x = about 0.13 and y = About 0.1 (coordinate 905). Although FIG. 1 shows an example of a chromaticity diagram that defines the wavelength spectrum of a visible light source, other suitable definitions are known in the art and can also be used with various embodiments of the disclosed subject matter described herein.

A convenient way to specify a part of the chromaticity diagram is through a set of equations on the x-y plane, where each formula has a solution trajectory that defines a line on the chromaticity diagram. Lines can intersect to specify a specific area. As an alternative definition, a white light source may emit light corresponding to light from a black body source operating at a given color temperature.

The chromaticity diagram also shows BBL 906 as described above with respect to FIG. 2. Each of the above-mentioned three R, G, and B LED coordinate positions is the CCT coordinate of the "fully saturated" LED of the respective colors green, blue and red. However, if a "white light" is generated by combining R, G, and B LEDs in a specific ratio, the CRI of this combination will be extremely low. Generally, in the environments described above, such as retail or hotel environments, a CRI of about 90 or higher is desired.

A revised version of the chromaticity diagram shown in Figure 9B and Figure 9C can be used with the approximate chromaticity coordinates of the desaturated R, G and B LEDs close to BBL 906 (indicated by isotherm 917c). The R, G, and B LEDs have a CRI of approximately 90+ and are within a defined color temperature range. However, the coordinate values can be shifted to a reduced saturation red (R) LED, at x = about 0.61 and y = about 0.36 (coordinates 955), a reduced saturation green (G) LED, at x = about 0.4 and y = At about 0.54 (coordinates 953), and a desaturated blue (B) LED, at x = about 0.21 and y = about 0.21 (coordinates 951), or after reading and understanding the disclosed subject matter Understandable other expected value sets. In various embodiments, for example, one of the color temperature ranges of desaturation R, G, and B LEDs may be in a range from about 1800K to about 2500K, about 2700K to about 6500K, or about 1800K to 7500K.

In a specific exemplary embodiment, it is also shown that a triangle 257 is formed between each of the coordinate values of the desaturated R, G, and B LEDs. Desaturation R, G, and B LEDs are formed (for example, by mixing one of phosphors and/or mixing one of materials to form an LED, as known in the art) to have coordinate values close to BBL 706. Therefore, the coordinate positions of the respective desaturated R, G, and B LEDs (and as summarized by triangle 957) have a CRI of about 90 or greater and an approximate tunable color temperature range of, for example, about 2700K to about 6500K. Therefore, a correlated color temperature (CCT) option can be selected in the color tuning application described herein, so that all the selected CCT combinations result in a lamp with a CRI of 90 or greater. Each of the desaturated R, G, and B LEDs can include a single LED or an LED array (or group), where each LED in the array or group has the same or similar to other LEDs in the array or group One drop of saturated colors. One or more desaturation R, G, and B LEDs are combined to form a lamp.

Another revised version of the chromaticity diagram shown in FIG. 9C may have different coordinates close to the desaturated R, G, and B LEDs of BBL 906. These desaturated R, G, and B LEDs have a CRI of approximately 80+ and are It is within a wider defined color temperature range than the aforementioned desaturation R, G, and B LEDs. In this case, the approximate chromaticity coordinates of the desaturated R, G, and B LEDs are arranged farther away from the BBL 106 than the desaturated R, G, and B LEDs indicated above. The coordinate value (as shown on the xy scale of the chromaticity diagram) can be shifted to a desaturated red (R) LED. At x = about 0.61 and y = about 0.32 (coordinates 975), a desaturated green (G ) LED at x = about 0.39 and y = about 0.58 (coordinates 973), and a desaturated blue (B) LED at x = about 0.19 and y = about 0.2 (coordinates 971).

As described above, one of the color temperature ranges of the desaturated R, G, and B LEDs shown in FIG. 9C may be in a range from about 1800K to about 2500K, about 2700K to about 6500K, or about 1800K to about 7500K. This results in the coordinate positions of the respective desaturated R, G, and B LEDs having a CRI of about 80 or greater and an approximate tunable color temperature range of, for example, about 1800K to about 7500K. Since the color temperature range is larger than the above range, the CRI is correspondingly reduced to about 80 or more. However, ordinary skilled artisans will recognize that desaturation R, G, and B LEDs can be generated to have individual color temperatures anywhere in the chromaticity diagram. Therefore, a CCT option can be selected in the color tuning application described herein, so that all the selected CCT combinations result in a lamp with a CRI of 80 or greater. Each of the desaturated R, G, and B LEDs can include a single LED or an LED array (or group), where each LED in the array or group has the same or similar to other LEDs in the array or group One drop of saturated colors. One or more desaturation R, G, and B LEDs are combined to form a lamp.

Although the features and elements are described above in specific combinations, those skilled in the art will appreciate that each feature or element can be used alone or in any combination with other features and elements. In addition, the method described herein can be implemented in a computer program, software, or firmware incorporated in a computer-readable medium to be executed by a computer or a processor. Examples of computer-readable media include electronic signals (transmitted via wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read-only memory (ROM), a random access memory (RAM), a register, a cache memory, a semiconductor memory device, magnetic media (such as built-in Hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM discs and digital versatile discs (DVD)).

Having described the present invention in detail, those skilled in the art will understand that in view of the present invention, the present invention can be modified without departing from the disclosed subject matter described herein. Therefore, the scope of the present invention is not intended to be limited to the specific embodiments shown and described.

102: McAdam ellipse (MAE) 104: Center 106: Black body line (BBL) 202: First straight line 300: Current distribution circuit 301: Light-emitting device (LED) driver 310: First current channel / First circuit channel 311: First Light emitting device (LED) array 312: first sense resistor (R _s1 ) 313: first sense voltage (V _sense1 ) 314: first gate voltage (V _g1 ) 315: first transistor (M1) 320 : Second current channel 321: second light emitting device (LED) array 322: second sense resistor (R _s2 ) 323: second sense voltage (V _sense2 ) 324: second gate voltage (V _g2 ) 325 : Second transistor (M2) 330: First operational amplifier (opamp) 340: Shunt regulator 350: Setting voltage (V _set ) 400: Operation circuit 430: Second operational amplifier (opamp) 440: Capacitor 450: Resistance Device 500: Microcontroller 501: Control signal 601: First predetermined voltage 602: Second predetermined voltage 701: Step 702: Step 703: Step 704: Step 705: Step 706: Step 707: Step 801: Step 802: Step 803 : Step 804: Step 805: Step 806: Step 900: Chromaticity Diagram 901: Coordinates 903: Coordinates 905: Coordinates 906: Black Body Line (BBL) 917c: Isotherm 951: Coordinates 953: Coordinates 955: Coordinates 957: Triangle 971 : Coordinates 973: Coordinates 975: Coordinates

Figure 1 shows a chromaticity diagram of a color space.

FIG. 2 is a diagram showing the relationship between different correlated color temperatures (CCT) and the black body line (BBL) on the chromaticity diagram.

Fig. 3 is a circuit diagram of a current distribution circuit of the present invention.

FIG. 4 is a circuit diagram of an arithmetic circuit that can be used with the analog current distribution circuit of FIG. 3.

Figure 5 is a microcontroller that can be used with the current distribution circuit of Figure 3.

FIG. 6 is a graph of a control signal fed to the microcontroller of FIG. 5.

Figure 7 shows a flow chart of an analog circuit division method.

Figure 8 shows a flowchart of another analog circuit division method.

Fig. 9A shows another chromaticity diagram of a color space.

Fig. 9B shows another chromaticity diagram of a color space.

Fig. 9C shows another chromaticity diagram of a color space.

300: Current distribution circuit

301: Light-emitting device (LED) driver

310: The first current channel / the first circuit channel

311: The first light emitting device (LED) array

312: The first sense resistor (R _s1 )

313: First sense voltage (V _sense1 )

314: First gate voltage (V _g1 )

315: The first transistor (M1)

320: second current channel

321: second light emitting device (LED) array

322: second sensing resistor (R _s2 )

323: The second sense voltage (V _sense2 )

324: second gate voltage (V _g2 )

325: second transistor (M2)

330: The first operational amplifier (opamp)

340: Shunt regulator

350: set voltage (V _set )

Claims (22)

A device comprising: A first sensing resistor for sensing a first sensing voltage of a first current channel; A second sensing resistor for sensing a second sensing voltage of a second current channel; An arithmetic circuit, which includes: An operational amplifier, and An RC circuit, which is arranged between an output terminal of the operational amplifier and the ground. The RC circuit includes a capacitor and a resistor connected in parallel with the capacitor, The operational amplifier is configured to: When the first sensing voltage is less than the second sensing voltage, a charging current is provided to charge the capacitor to increase an output voltage of the arithmetic circuit, and Allowing the capacitor to discharge through the resistor to reduce the output voltage when the first sensing voltage is greater than the second sensing voltage; A first voltage control switch for supplying power to a first LED array based on the output voltage of the arithmetic circuit; and A second voltage control switch is used to supply power to a second LED array based on the output voltage of the arithmetic circuit. The device of claim 1, further comprising a second operational amplifier coupled to the output voltage of the operational circuit and the first voltage control switch. The device of claim 2, wherein an output terminal of the second operational amplifier is coupled to a gate of the first voltage control switch. The device of claim 3, which further includes a gate/shunt regulator coupled to the second voltage control switch, and the output terminal of the second operational amplifier is coupled to the shunt regulator through a voltage divider A reference node such that when a voltage applied to the reference node is greater than a predetermined shunt voltage, the shunt regulator is configured to draw enough power to pull the gate of the second voltage control switch to low At a predetermined threshold and turn off a current of the second voltage control switch, and when the voltage applied to the reference node is less than the predetermined shunt voltage, the shunt regulator is configured to draw a current The quiescent current makes a voltage at the gate of the second voltage control switch higher than the predetermined threshold and turns on the second voltage control switch. Such as the device of any one or more of claims 1 to 4, wherein the arithmetic circuit further includes an arithmetic circuit switch, the arithmetic circuit switch has a gate coupled to the output terminal of the operational amplifier and a gate coupled to the RC circuit A source allows the arithmetic circuit switch to be turned on when the first sensing voltage is less than the second sensing voltage, and to be turned off when the first sensing voltage is greater than the second sensing voltage. For example, the device of any one or more of claims 1 to 4, which further includes a plurality of regulating current channels one less than the total number of one of the current channels, the first current channel being one of the regulating current channels, and the first current channel The two current channels are one unregulated current channel. Such as the device of any one or more of claims 1 to 4, wherein the first LED array has a correlated color temperature (CCT) in a first tunable range, and the second LED array has a second tunable range One of CCT. The device of claim 7, wherein the first and second LED arrays have CCTs at opposite ends of a desired tuning range. Such as the device of claim 8, wherein the first and second LED arrays respectively have a CCT of 2700K and 4000K. The device of claim 7, wherein the first and second LED arrays have a CCT such that the emission from the first and second LED arrays is within a predetermined distance from a black body line of a chromaticity diagram. A device comprising: A voltage controlled current source; A first sensing resistor for sensing a first sensing voltage of a first current channel; A second sensing resistor for sensing a second sensing voltage of a second current channel; A microcontroller configured to: Determining a ratio of the first sensing voltage to the second sensing voltage to generate an output voltage, Map a control signal to this ratio, Guiding the input current to the first current channel when the control signal is at most a first predetermined voltage; Guiding the input current to the second current channel when the control signal is at least a second predetermined voltage; and Adjusting the input current proportionally between the first current channel and the second current channel when the control signal is between the first predetermined voltage and the second predetermined voltage; A first voltage control switch for supplying power to a first LED array; A second voltage control switch for supplying power to a second LED array, The output voltage is supplied to the first voltage control switch. The device of claim 11, which further includes an operational amplifier coupled to the output voltage and the first voltage control switch. The device of claim 12, wherein an output terminal of the operational amplifier is coupled to a gate of the first voltage control switch. The device of claim 13, further comprising a gate/shunt regulator coupled to the second voltage control switch, and the output terminal of the operational amplifier is coupled to one of the shunt regulators through a voltage divider The reference node, such that when a voltage applied to the reference node is greater than a predetermined shunt voltage, the shunt regulator draws enough power to pull the gate of the second voltage control switch below a predetermined threshold Value and turn off a current of the second voltage control switch, and when the voltage applied to the reference node is less than the predetermined shunt voltage, the shunt regulator will draw a quiescent current so that the second voltage control A voltage at the gate of the switch is higher than the predetermined threshold and the second voltage control switch is turned on. Such as the device of any one or more of claim items 11 to 14, wherein the microcontroller is configured to connect the first current channel to the first current channel when the control signal is between the first predetermined voltage and the second predetermined voltage The input current is adjusted linearly and proportionally between the second current channels. Such as the device of any one or more of claim items 11 to 14, wherein the microcontroller is configured to connect the first current channel to the first current channel when the control signal is between the first predetermined voltage and the second predetermined voltage The input current is adjusted proportionally between the second current channels in a stepwise manner. Such as the device of any one or more of claim items 11 to 14, wherein the first LED array has a correlated color temperature (CCT) in a first tunable range, and the second LED array has a second tunable range One of CCT. A method including: Receiving an input current from a voltage control current source; Sensing a first sensing voltage from a first current channel; Sensing a second sensing voltage from one of a second current channel; Calculating a ratio of the first sensing voltage to the second sensing voltage to determine an output voltage; Map a control signal to the ratio; Guiding the input current to the first current channel when the control signal is at most a first predetermined voltage; Guiding the input current to the second current channel when the control signal is at least a second predetermined voltage; Adjust the input current linearly and proportionally between the first current channel and the second current channel when the control signal is between the first predetermined voltage and the second predetermined voltage; and The output voltage is supplied to the first current channel to supply power to a first LED array. The method of claim 18, further comprising increasing the output voltage when the first sensing voltage is less than the second sensing voltage, and reducing the output voltage when the first sensing voltage is greater than the second sensing voltage The output voltage. Such as the method of claim 18 or 19, which further includes: By applying a voltage greater than a predetermined shunt voltage to a reference node of a shunt regulator, the drain is sufficient to pull a gate of a second voltage control switch below a predetermined threshold and turn off Interrupting a current of the second voltage control switch, the second voltage control switch being used to supply power to a second LED array; and When the voltage applied to the reference node is less than the predetermined shunt voltage, a quiescent current is drawn so that a voltage at the gate of the second voltage control switch is higher than the predetermined threshold and turns on the second Voltage control switch. Such as the method of claim 18 or 19, further comprising controlling the control signal to adjust the input current linearly and proportionally between the first current channel and the second current channel and mixing the input current from the first LED array and a second current channel. One of the two LED arrays outputs to obtain a white color having a temperature between about 2700K and about 4000K, and the first LED array and the second LED array have different correlated color temperatures. Such as the method of claim 21, which further comprises controlling the control signal so that the output from the first and second LED arrays are mixed to obtain a value close to a black body line on a chromaticity diagram between about 2700K and about 4000K Between the color points.

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