Driver IC and method therefor

Abstract

This driver integrated chip (IC) for driving a light emitting diode (LED) may comprise: a current supply which includes a first current source and a first switch for supplying the LED with a current from the first current source or blocking the current, and a second current source and a second switch for supplying the LED with a current from the second current source or blocking the current; and a controller which controls opening and closing of the first switch and the second switch, wherein the controller determines the amount of current required to drive the LED, determines operation configurations of the first current source and the second current source or the first switch or the second switch for achieving the determined amount of current, and generates opening and closing control signals of the first switch and the second switch according to the determined operation configurations.

Description

Driver IC and method therefor

[0001] The present invention relates to a device for driving an LED and a method therefor, and more specifically, to a driver IC (integrated circuit) capable of increasing the resolution and linearity of LED light emission and a control method therefor.

[0002] Figure 1 illustrates a conventional LED driver IC. Conventional driver ICs control the ON / OFF of the current source of each channel with one switch opening / closing control signal per channel, i.e., PWM (pulse width modulation). Once the maximum output brightness of the LED is determined, the brightness control resolution is generally determined by the clock frequency (f) of the PWM generator. CLK ) is determined by.

[0003] According to this method, in order to increase the resolution of LED brightness (luminescence), the frequency of PWM, i.e. the clock frequency (f CLK ) is essential, which has the problem of leading to an increase in power consumption of the PWM generator.

[0004] The present invention proposes a driver IC for driving an LED and a method therefor.

[0005] More specifically, we propose a device and method that can increase the LED luminescence resolution and linearity compared to conventional devices.

[0006] The problems to be solved by the present invention are not limited to the problems to be solved above, and other problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0007] A driver IC for driving an LED (light emitting diode) is proposed, the driver IC including: a current supply configured with a first current source and a first switch for supplying or cutting off current from the first current source to the LED, and a second current source and a second switch for supplying or cutting off current from the second current source to the LED; and a controller for controlling opening and closing of the first switch and the second switch, wherein the controller can determine an amount of current required for driving the LED, determine an operation configuration of the first current source and the second current source, or the first switch or the second switch, for the determined amount of current, and generate an opening and closing control signal of the first switch and the second switch according to the determined operation configuration.

[0008] A method for controlling a driver IC for driving an LED, the method being performed by the driver IC, comprising: determining an amount of current required for driving the LED; determining an operation configuration of a current source or switch for the required amount of current; and generating an opening / closing control signal of the switch according to the determined operation configuration, wherein the current source includes a first current source and a second current source for supplying current to the LED, and the switch includes a first switch for supplying or cutting off current from the first current source to the LED, and a second switch for supplying or cutting off current from the second current source to the LED.

[0009] The above problem solving methods are only some of the embodiments of the present invention, and various embodiments reflecting the technical features of the present invention can be derived and understood by a person having ordinary knowledge in the relevant technical field based on the detailed description of the present invention described below.

[0010] The present invention has the following effects.

[0011] The present invention can increase the luminance resolution without increasing the clock frequency or area of ​​the PWM generator.

[0012] In addition, since the present invention does not increase the clock frequency of the PWM generator to increase the luminance resolution, power consumption and heat generation can be suppressed compared to a method of increasing the clock frequency.

[0013] In addition, the present invention is cost-effective because it does not require the use of a fine process to increase the clock frequency of the PWM generator.

[0014] Additionally, the increased luminance resolution also applies to fine compensation (i.e. calibration) of luminance differences between LEDs (channels), which helps ensure image quality uniformity.

[0015] Additionally, when the present invention is implemented to maintain the LED resolution, there is an effect of reducing the clock frequency of the PWM generator.

[0016] The effects according to the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art to which the present invention pertains from the detailed description of the invention below.

[0017] The accompanying drawings, which are included as part of the detailed description to aid in understanding the present invention, provide embodiments of the present invention and, together with the detailed description, explain the technical idea of ​​the present invention.

[0018] Figure 1 illustrates an LED driving IC according to the prior art.

[0019] Figure 2 illustrates an LED driving IC according to the present invention.

[0020] Figure 3 illustrates an LED driving IC according to the present invention.

[0021] Figure 4 shows the operational configuration of two switches or current sources according to the present invention.

[0022] Figure 5 is a simulation result related to LED driving according to the prior art and the present invention, showing the cumulative current and cumulative current increment for confirming the luminance estimation value.

[0023] Figures 6 and 7 are diagrams for explaining the necessity of configuring two switches or current sources according to the present invention.

[0024] Figure 8 shows the operational configuration of two switches or current sources according to the present invention.

[0025] Figure 9 is a simulation result related to LED driving according to the present invention, showing the cumulative current and cumulative current increment for confirming the luminance estimation value.

[0026] Figure 10 is a diagram to explain the difference in current amount due to the difference in physical characteristics of two LEDs and the need for compensation therefor.

[0027] Figure 11 is a flowchart of a control method according to the present invention.

[0028] Figure 12 is a block diagram of an LED driving IC according to the present invention.

[0029] Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Regardless of the drawing numbers, identical or similar components will be given the same reference numbers and redundant descriptions thereof will be omitted. The suffixes "module" and "part" used for components in the following description are assigned or used interchangeably only for the convenience of writing the specification, and do not in themselves have distinct meanings or roles. In addition, when describing the embodiments disclosed in this specification, if it is determined that a specific description of a related known technology may obscure the gist of the embodiments disclosed in this specification, a detailed description thereof will be omitted. In addition, the attached drawings are only intended to facilitate easy understanding of the embodiments disclosed in this specification, and the technical ideas disclosed in this specification are not limited by the attached drawings, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and technical scope of the present invention.

[0030] Terms that include ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by these terms. These terms are used solely to distinguish one component from another.

[0031] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0032] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0033] In this application, terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but should be understood not to exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0034]

[0035] Figure 1 illustrates an LED driving IC according to the prior art.

[0036] The LED driving IC may include a current source (1), a PWM switch (2), and a PWM generator (3). The current source (1) is connected to a power source (4) and supplies current to the LED. The PWM switch (2) performs an opening and closing operation to supply or block current from the current source (1) to the LED. The PWM generator (30) inputs a PWM (i.e., an opening and closing control signal) to the PWM switch (2) and controls the opening and closing operation of the PWM switch (20).

[0037] Meanwhile, in Fig. 1, the LED driving IC is illustrated as a single block that supplies current to one channel of LED, but in reality, an LED driving IC may be provided for each LED channel.

[0038] The LED driving IC according to the prior art illustrated in Fig. 1 increases the resolution of LED light emission (brightness) by increasing the clock frequency (f) of the PWM generator (30). CLK ) had to be increased. However, increasing the clock frequency requires a fine process, and this incurs the uncompromising drawback of increased heat generation and power consumption due to the increased frequency.

[0039]

[0040] Figure 2 illustrates an LED driving IC according to the present invention.

[0041] The LED driving IC may include a current source (110), a PWM switch (120), and a PWM generator (130). The current source (110) is connected to a power source (140) and supplies current to the LED. The PWM switch (120) performs an opening and closing operation to supply or block current from the current source (110) to the LED. The PWM generator (130) inputs a PWM (i.e., an opening and closing control signal) to the PWM switch (120) and controls the opening and closing operation of the PWM switch (120).

[0042] The LED driving IC of Fig. 2 is different from the LED driving IC of Fig. 1 in the part A indicated in the drawing. That is, the PWM generator (130) transmits two PWM signal outputs to the PWM switch (120). In order to increase the luminance resolution of the LED in the LED driving IC of Fig. 1, the clock frequency (f CLK ) instead of increasing the current, a configuration was added to precisely control the amount of current supplied to the LED.

[0043] According to the present invention, since there is no need to increase the clock frequency of the PWM generator (130), there is no need for a fine process, no increase in area for the circuit accordingly, and there is an advantage that an increase in heat generation or power consumption is not a major problem.

[0044] Meanwhile, in Fig. 2, the LED driving IC is illustrated as a single block that supplies current to one channel of LED, but in reality, an LED driving IC may be provided for each LED channel.

[0045] Below, the LED driving IC proposed in the present invention will be described in more detail.

[0046]

[0047] Figure 3 illustrates an LED driving IC according to the present invention.

[0048] The LED driving IC (100) includes two current sources (111, 112) and switches (121, 122) connected to each current source to supply or cut off current from the current sources to the LED (CH_OUT). In addition, although not shown, the LED driving IC (100) includes a PWM controller (or simply “controller”) that generates and supplies opening and closing control signals (PWM1, PWM2) of the two switches (121, 122).

[0049] The first current source (111) and the second current source (112) are configured to divide and supply a predetermined amount of current, ICH, supplied to the LED (or LED channel), and are configured to supply current at a ratio of (N-1) / N to 1 / N, respectively. Here, N is a positive integer greater than or equal to 2, and preferably, N=2. k , and k is an integer greater than or equal to 2.

[0050] The LED driving IC (100) determines the amount of current (or current value) supplied to the LED according to the sum of PWM1 and PWM2 or the opening and closing of the switch accordingly, and therefore the configuration of PWM1 and PWM2 will vary according to the amount of current required for driving the LED.

[0051] Meanwhile, in FIG. 3, the current source and switch are illustrated as two pairs, but a greater number of current source and switch pairs may be included in the LED driving IC (100) according to the present invention.

[0052] Below, we will examine in detail the configuration of the opening / closing control signal (PWM1, PWM2).

[0053]

[0054] Figure 4 shows the configuration of two switches or current sources according to the present invention.

[0055] Fig. 4 (a) shows a first configuration according to the present invention, and Fig. 4 (b) shows a second configuration according to the present invention. In addition, Fig. 4 shows an LED driving IC (100) described in Fig. 3, where N = 2. k =2 2 =4(i.e. k=2) is shown. This is 2 bits, i.e. 4(2) compared to the case where one current source (1.00*ICH) is used. k , k=2) can achieve a resolution increase of 2 times. On the other hand, thinking conversely, if the LED driving IC according to the present invention is used, the clock frequency (f) for the PMW generator can be increased in order to maintain the resolution of the LED brightness according to the prior art. CLK ) can be reduced by 1 / N times. That is, even if there is no increase in the resolution of LED brightness, a decrease in clock frequency is possible, so a decrease in heat generation or power consumption is expected.

[0056] In Fig. 4, the amount of current supplied to the LED channel during multiple clocks (GCLK) is 3.00*ICH to 4.00*ICH in 0.25*ICH unit intervals, and the configuration of PWM1 and PWM2 for each amount of current is shown.

[0057] In addition, as shown in Fig. 4, a plurality of clocks (GCLK) constituting each current amount (3.00*ICH to 4.00*ICH, increasing by 0.25*ICH) can be referred to as one “clock unit.” A “clock unit” can be composed of at least one clock.

[0058] PWM1 is an on / off control signal for the first current source (111), i.e., the current source supplying 3 / 4*ICH or the first switch (121) connected thereto, and PWM2 represents an on / off control signal for the second current source (112), i.e., the current source supplying 1 / 4*ICH or the second switch (122) connected thereto. In the drawing, 3 / 4*ICH is simply indicated as “3 / 4” and 1 / 4*ICH is simply indicated as “1 / 4”. In addition, the bold marks shown in the drawing are only marks to make it easier to visually recognize the difference.

[0059] Due to the characteristics of the LED, a steep slope of the voltage (Vd) initially applied across the LED is advantageous for the light emission (luminance) characteristics. Since the voltage (Vd) applied across the LED is equal to or proportional to I / C (C is the parasitic capacitance of the LED), a larger initial current is advantageous. Accordingly, the sum of the initial currents of each configuration shown in (a) and (b) of Fig. 4 is 1 (1*ICH), so that the first and second switches are both closed, and the current from the first current source and the second current source is supplied to the LED channel.

[0060] Additionally, for a current amount corresponding to a positive integer multiple of ICH, both the first and second switches are closed, and accordingly, current from the first current source and the second current source is configured to be supplied to the LED channel.

[0061] For convenience of explanation, the method will be explained by increasing the current supplied to the LED by 0.25*ICH increments based on 3.00*ICH. However, it should be clarified that this does not mean that control is performed solely in the direction of increasing the current supplied to the LED. In other words, changes in the current supplied to the LED over time do not limit the scope of the present invention.

[0062] In Fig. 4 (a), in order to increase the current amount by 0.25*ICH, an opening / closing control signal for the second current source (112) supplying 1 / 4*ICH or the second switch (122) connected thereto is configured using an additional clock. In the case of 3.25*ICH, PWM2 is added at the 4th clock, in the case of 3.50*ICH, PWM2 is added at the 4th and 5th clocks, and in the case of 3.75*ICH, PWM2 is added at the 4th, 5th, and 6th clocks. In the case of 4.00*ICH, PWM2 is removed at the 5th and 6th clocks, and instead, PWM1 is added at the 4th clock.

[0063] In order to increase the current amount by 0.25*ICH in (b) of Fig. 4, an opening / closing control signal for the second current source (112) supplying 1 / 4*ICH or the second switch (122) connected thereto is configured using an additional clock. In the case of 3.25*ICH, it is configured by adding PWM1 in the 4th clock and removing PWM2 in the 2nd and 3rd clocks, in the case of 3.50*ICH, it is configured by adding PWM2 in the 2nd clock, and in the case of 3.75*ICH, it is configured by adding PWM2 in the 3rd clock. In the case of 4.00*ICH, it is configured by adding PWM2 in the 4th clock.

[0064] The differences between the configuration of Fig. 4(a) and the configuration of Fig. 4(b) will be examined below.

[0065]

[0066] Figure 5 is a simulation result related to LED driving according to the prior art and the present invention, showing the cumulative current and cumulative current increment for confirming the luminance estimation value.

[0067] Figures 5a to 5c illustrate simulation results according to current supply to an RGB LED, and show simulation results for a case where the last clock among multiple clocks for each current amount ends with PWM2, i.e., 0.25*ICH, as in the configuration of Figure 4 (a).

[0068] Figures 5d to 5f illustrate simulation results according to current supply to the RGB LED, and show simulation results for a case where the last clock among multiple clocks for each current amount ends with PWM1, i.e., 0.75*ICH, as in the configuration of Figure 4 (b).

[0069] Meanwhile, in both cases, for current amounts that are integer multiples of 1 or more of ICH, all clocks are configured to use PWM1 and PWM2 so that 1.0*ICH is supplied.

[0070] Looking at FIGS. 5a to 5c, the x-axis represents the amount of current supplied to the LED channel (i.e., the required current or “driving current”), and each data is distributed at 0.25(*ICH) intervals. The solid line represents the value of the left y-axis and represents the cumulative current flowing to the LED (i.e., I1 in FIG. 6). The dotted line represents the value of the right y-axis and represents the increment of the cumulative current flowing to the LED, indicating that the increment of the current is not flat as the x-axis value increases. Ideally, the increment of the cumulative current should be flat. In particular, in the case of G and B, there are cases where the increment corresponds to a negative value, which is expected to cause a problem in the LED light emission (luminance).

[0071] To explain in more detail, referring to FIG. 5b or FIG. 5c, the incremental amount of the accumulated current has a negative value, which means that although the amount of current supplied to the LED channel increases, the amount of current actually expected to flow to the LED actually decreases, so this is a simulation result that predicts that a reversal phenomenon of LED light emission (luminance) will occur.

[0072] In FIGS. 5d to 5f, the meaning of each axis, solid line, and dotted line of the graph is the same as in FIGS. 5a to 5c. However, unlike FIGS. 5a to 5c, the accumulated current amount (solid line) supplied to the LED channel is generally flat. With regard to LED light emission (luminance), it is expected that better results can be obtained compared to the case of FIG. 4(a) shown in FIGS. 5a to 5c. In the graphs shown in FIGS. 5d to 5f, at least there is no case where the incremental amount of current is negative, so it is expected that there will be no LED light emission (luminance) reversal phenomenon. In conclusion, according to the LED driver IC or the LED driving control method using the same according to the present invention, the reversal phenomenon of the LED brightness due to the increase in the amount of current supplied to the LED (i.e., the driving current amount) is alleviated.

[0073] Below, the configuration of Fig. 4(b) and the technical basis for which the simulation results thereof, Figs. 5d to 5f, are expected to exhibit excellent LED luminance (brightness) characteristics will be explained.

[0074]

[0075] Figures 6 and 7 are diagrams for explaining the necessity of configuring two switches or current sources according to the present invention.

[0076] Fig. 6 is for explaining the transient period of LED driving. At the initial stage of LED driving, there is a transient period in which the channel current is used to charge the capacitor of the LED. That is, in order to light up the LED, the parasitic capacitors across the LED must be charged so that the voltage (Vd) across the LED reaches VF. In the initial stage of charging ((1) of Fig. 6(a)), no current flows through the LED (i.e., I1=0), and the voltage across the LED is determined by ICH=C*dVd / dt (C is the parasitic capacitance across the LED). As the voltage across the LED is gradually charged as Vd shown in Fig. 6(a), current also flows through the LED at a specific Vd ((2) of Fig. 6(a)), and the charging speed of the parasitic capacitors across the LED slows down by the amount of the current flowing into the LED (i.e., ICH-I1=C*dVd / dt). After the parasitic capacitors at both ends of the LED are fully charged, the current I2 flowing into the capacitor becomes 0 (i.e., no more current flows into the capacitor and it becomes electrically open), and the current ICH supplied from the current source (10) flows entirely into the LED, at which time the voltage across the LED becomes Vd=VF.

[0077] In conclusion, the length of the transient section (1) of LED driving should be short, that is, the slope of the slope of Vd should be large, so that the time to enter the LED driving section (3) becomes faster, which means that the point of (maximum) luminescence of the LED becomes earlier. As explained above, the slope of the slope of the slope of Vd is ICH / C, so ICH should be large from the initial point in time to improve the LED luminescence (brightness) characteristics. Therefore, it is desirable to control the first clock for each current supply so that, if possible, all of ICH can be supplied.

[0078]

[0079] Figure 7 shows a transient section when the current is supplied as 1.00*ICH at the first clock and as m*ICH at the second clock (m is a rational number less than 1), considering the clock unit. When the current is 1.00*ICH, if Vd=VF1, and when the current is m*ICH, if Vd=VF2, the LED must discharge a charge equal to VF1-VF2.

[0080] For example, assuming that VF1 for 1.00*ICH=2.4V, VF2 for 0.25*ICH=2.1V, and VF3 for 0.75*ICH=2.3V, when the current changes from driving at 1.00*ICH in the first clock to 0.25*ICH in the second clock to increase the resolution, ΔV=VF1-VF2=2.4V-2.1V=0.3V. On the other hand, when the current changes from driving at 1.00*ICH to 0.75*ICH, ΔV=VF1-VF3=2.4V-2.3V=0.1V, so the amount of charge to be naturally discharged is reduced by three times. That is, this means that the driving method in which the current amount switches from 1.00*ICH to 0.75*ICH between clocks has a response that is three times faster than the driving method in which the current amount switches from 1.00*ICH to 0.25*ICH between clocks. Since the response speed is fast, it means that the intended current also changes quickly, and it means that the control over the change in the current size is good. In addition to these examples, the corresponding phenomenon (increase in the amount of charge to be charged) also occurs in cases where the driving current increases over time, such as when driving at 0.25xICH on the first clock and then driving at 1.00*ICH on the second clock, and when driving at 0.75*ICH on the first clock and then driving at 1.00*ICH on the second clock.

[0081] Therefore, it is desirable to configure the current amount in two consecutive clocks so that the difference can be minimized as much as possible. To this end, it is desirable to configure it so that PWM1 can be used rather than PWM2, which has a relatively small current supply. Therefore, N-1=2 k - It can be configured so that one PWM2 can be replaced by one PWM1.

[0082]

[0083] The control method for the driver IC for configuring the current source using PWM1 and PWM2 described above is summarized as follows.

[0084] A) Basically, PWM2 is used cumulatively according to the clock to achieve the required current amount,

[0085] B) By increasing the number of PWM2 according to A), PWM2 is “2 k -1” to avoid using more than “2” k -Use 1 PWM1 instead of 1 PWM2,

[0086] C) For unit current (1.00*ICH) or more, always use PWM1 and PWM2 in the first clock.

[0087] D) For integer multiples of the unit current (N*ICH, e.g., 1.00*ICH, 2.00*ICH, …, 5.00*ICH, etc.), always use PWM1 and PWM2 for all clocks. That is, for integer (N) multiples of the unit current, the corresponding integer (N) number of clocks are used.

[0088] Above, B) can be seen as a proposed rule for the reasons explained with reference to Fig. 7, and C) and D) can be seen as proposed rules for the reasons explained with reference to Fig. 6.

[0089]

[0090] Fig. 8 shows the operational configuration of two switches or current sources according to the present invention. Fig. 8 is a current source configuration for supplying current to an LED using the driver IC of Fig. 3, where N = 2. 3 =8. It represents a configuration for supplying current (7.00*ICH to 8.00*ICH, increasing by 0.125*ICH) during the clock unit. This can achieve a resolution increase of 3 bits, or 8 times, compared to the case where one current source (1.00*ICH) is used.

[0091] Fig. 8(a) corresponds to Fig. 4(a) and shows a configuration in which PWM2 is added one by one each time 0.125*ICH increases. Fig. 8(b) corresponds to Fig. 4(b) and shows a configuration according to the rules A) to D) described above. Descriptions of each configuration are omitted.

[0092]

[0093] Meanwhile, let's compare Fig. 4(b) and Fig. 8(b), which are improved configurations according to the present proposal, with the existing Fig. 4(a) and Fig. 8(a). Referring to the drawings, Fig. 4(b), unlike Fig. 4(a), has a configuration in which, in a current amount configuration that is not an integer multiple of ICH, the last clock in each configuration (clock unit) closes the current source that supplies the larger current (i.e., 0.75*ICH) among the two current sources or the switch corresponding thereto. This is related to the physical characteristics explained with reference to Fig. 6 and Fig. 7 described above.

[0094] In addition, Fig. 8(b) has a configuration in which, unlike Fig. 8(a), the current amount configuration is not an integer multiple of ICH, and in each configuration (clock unit), the last clock closes the current source (i.e., 0.875*ICH) that supplies the larger current among the two current sources or the corresponding switch. This is related to the physical characteristics described with reference to Figs. 6 and 7 described above.

[0095]

[0096] Figure 9 is a simulation result related to LED driving according to the present invention, showing the cumulative current and cumulative current increment for confirming the luminance estimation value.

[0097] The dotted and solid lines represent the same as those in Figure 5, so please refer to the explanation in Figure 5. The increment of accumulated current (dotted line) is generally flat. This suggests that the LED is expected to have good luminance characteristics (i.e., linearity).

[0098]

[0099] Figure 10 is a diagram to explain the difference in current amount due to the difference in physical characteristics of two LEDs and the need for compensation therefor.

[0100] Fig. 10 is a graph showing the voltage (Vd1, Vd2) and current (I1, I-2) across the LEDs of two LED channels. The LEDs of each channel have different parasitic capacitance values, which is a difficult problem to eliminate. Therefore, as shown in Fig. 10, depending on the difference in parasitic capacitance of the two LEDs, the slopes of Vd1 and Vd2 become different, resulting in a difference (ΔI) in the amount of current supplied to each LED. This difference in the amount of supplied current causes a deviation in the LED light emission (brightness). To eliminate this, a calibration process is performed to measure this deviation and reflect a value that compensates for the deviation to each LED channel.

[0101] In this calibration process, it is expected that more precise compensation will be possible by using an LED driver IC using at least two current sources according to the proposal of the present invention or an LED driving control method using the same, since the resolution of LED light emission (luminance) is improved compared to the conventional technology.

[0102]

[0103] Figure 11 is a flowchart of a control method according to the present invention. This control method can be performed by an LED driver IC. More specifically, it can be performed by a controller included in the LED driver IC. In the following, it will be briefly described that the "driver IC (100)" performs this control method.

[0104] The driver IC (100) can determine the amount of current required to drive the LED (S1110).

[0105] The driver IC (100) can determine the operation configuration of the current source (111, 112) or the switch (121, 122) for the required current amount (S1120). Here, the operation configuration means the configuration of PWM1 and PWM2 (i.e., the switch opening / closing control signal) in a clock unit composed of at least one clock, such as that shown in FIG. 4(b) or FIG. 8(b), or the supply of a current source corresponding to PWM1 and PWM2 or the open / close state of the switch.

[0106] The driver IC (100) can generate an opening / closing control signal of the switch (121, 122) according to the determined operation configuration (S1130).

[0107] The driver IC (100) can control the opening and closing of the switch (121, 122) using the generated opening and closing control signal, so that current can be supplied to the LED according to the required amount of current and the operation configuration therefor.

[0108] The driver IC (100) can determine the operation configuration of the current source (111, 112) or the switch (121, 122) to compensate for the brightness difference between multiple LED channels. Then, the driver IC (100) can generate an opening / closing control signal of the switch (121, 122) according to the determined operation configuration.

[0109] In addition to the operation illustrated in FIG. 11, the driver IC (100) can perform the operation described above with reference to FIGS. 2 to 10, and a detailed description thereof will be omitted to avoid duplication of explanation.

[0110]

[0111] Fig. 12 is a block diagram of a driver IC (100) according to the present invention.

[0112] The driver IC (100) includes a current source (110) including a first current source and a second current source. In addition, the driver IC (100) includes a switch (120) including a first switch for supplying or blocking current from the first current source to an LED, and a second switch for supplying or blocking current from the second current source to the LED. The current source (110) and the switch (120) may be integrated into one and referred to as a current supply.

[0113] In addition, the driver IC (100) includes a controller (130) that controls the opening and closing of the first switch and the second switch. The controller (130) corresponds to the PWM generator (130) illustrated in FIG. 2, and may include not only the PWM generator but also other functional blocks or circuits.

[0114] The controller (130) can determine the amount of current required to drive the LED and determine the operation configuration of the first current source and the second current source, or the first switch or the second switch, for the determined amount of current. In addition, the controller (130) can generate an opening / closing control signal for the first switch and the second switch according to the determined operation configuration.

[0115] The first current source and the second current source are set to supply a current amount in the ratio of 1 / N to (N-1) / N, where N is 2 k , and k may be an integer greater than or equal to 1, and preferably an integer greater than or equal to 2.

[0116] The controller (130) generates an opening / closing control signal of the switch (120) to supply the amount of current required for driving the LED through a clock unit composed of at least one clock, and can control the current of the first current source to be sequentially supplied to the LED from at least one clock to supply the required amount of current. In addition, the controller (130) can control the first current source to be sequentially supplied to the LED by two k -2 consecutive clocks so that the LEDs are not supplied at 1 clock k - It is possible to control the supply of current to the LED through a second current source of one clock instead of a first current source of one clock.

[0117] Additionally, the controller (130) can control current from the first current source and the second current source to be supplied to the LED simultaneously in the first clock of at least one clock when the required current amount is equal to the sum of the supply current amounts of the first current source and the second current source.

[0118] Additionally, the controller (130) can control current from the first current source and the second current source to be supplied to the LED simultaneously in all clocks of at least one clock when the required current amount is equal to an integer multiple of the sum of the supply current amounts of the first current source and the second current source.

[0119] Additionally, the controller (130) can compensate for the brightness difference between the plurality of LED channels by controlling at least one of the first current source and the second current source, or at least one of the first switch and the second switch.

[0120] In addition to the functions, operations, and control performance described with reference to FIG. 12, the controller (130) can also perform the functions, operations, and control performance described with reference to FIGS. 2 to 10, and detailed descriptions are omitted to avoid duplication of explanations.

[0121]

[0122] In addition, as another aspect of the present invention, the operation of the proposal or invention described above may be implemented, performed or executed by a “computer” (a comprehensive concept including a system on chip (SoC) or a (micro) processor, etc.), or may be provided as a code or a computer-readable storage medium storing or including the code or a computer program product, and the scope of the present invention may be extended to the code or the computer-readable storage medium storing or including the code or the computer program product.

[0123]

[0124] The detailed description of the preferred embodiments of the present invention disclosed above has been provided to enable those skilled in the art to implement and practice the present invention. While the above description has been made with reference to preferred embodiments of the present invention, those skilled in the art will appreciate that various modifications and variations of the present invention, as defined by the following claims, are possible. Accordingly, the present invention is not intended to be limited to the embodiments disclosed herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. As a driver IC (integrated chip) for driving LED (light emitting diode), A current supply comprising a first current source and a first switch for supplying or cutting off current from the first current source to the LED, and a second current source and a second switch for supplying or cutting off current from the second current source to the LED; and It includes a controller that controls the opening and closing of the first switch and the second switch, A driver IC wherein the controller determines the amount of current required to drive the LED, determines the operation configuration of the first current source and the second current source, or the first switch or the second switch, for the determined amount of current, and generates an opening / closing control signal of the first switch and the second switch according to the determined operation configuration.

2. In paragraph 1, The first current source and the second current source are set to supply a current amount in the ratio of 1 / N to (N-1) / N, where N is 2. k , and k is an integer greater than or equal to 2. , driver IC.

3. In paragraph 2, The above controller: Generating the opening / closing control signal to supply the required amount of current through a clock unit consisting of at least one clock, In order to supply the required amount of current, the current of the first current source is controlled to be supplied to the LED sequentially from at least one clock, and the first current source is supplied to the LED sequentially from two k - The above consecutive 2 are not supplied to the above LED at 1 clock. k -Controlling the supply of current to the LED by replacing the first current source of one clock with the second current source of one clock. , driver IC.

4. In paragraph 3, The above controller: When the required current amount is equal to the sum of the supply current amounts of the first current source and the second current source, the current from the first current source and the second current source is controlled to be supplied to the LED simultaneously in the first clock of the at least one clock. , driver IC.

5. In paragraph 3, The above controller: When the required current amount is equal to a positive integer multiple of the sum of the supply current amounts of the first current source and the second current source, the current from the first current source and the second current source is controlled to be supplied to the LED simultaneously in all clocks of the at least one clock. , driver IC.

6. In paragraph 2, The above controller: If the required current amount is not a positive integer multiple of the sum of the supply current amounts of the first current source and the second current source, the control is to supply only the current from the second current source to the LED in the last clock among the clock units consisting of at least one clock. , driver IC.

7. In paragraph 2, In order to maintain the brightness resolution of the above LED, The above controller reduces the clock frequency for generating the above open / close control signal by 1 / 2. k Set to double , driver IC.

8. In paragraph 1, The above controller: Compensating for the difference in brightness between the plurality of LED channels by controlling at least one of the first current source and the second current source, or at least one of the first switch and the second switch. , driver IC.

9. In paragraph 1, According to the opening and closing control of the first switch and the second switch, the phenomenon of the brightness of the LED being reversed due to an increase in the amount of current supplied to the LED is alleviated. , driver IC.

10. A method for controlling a driver IC (integrated chip) for driving an LED (light emitting diode), wherein the method is performed by the driver IC, A step for determining the amount of current required to drive the LED; a step of determining the operational configuration of a current source or switch for the required current amount; and A step of generating an opening / closing control signal of the switch according to the above-determined operation configuration is included, The above current source includes a first current source and a second current source that supply current to the LED, The switch includes a first switch for supplying or cutting off current from the first current source to the LED and a second switch for supplying or cutting off current from the second current source to the LED. , control method.

11. In paragraph 10, The first current source and the second current source are set to supply a current size in the ratio of 1 / N to (N-1) / N, where N is 2. k , and k is an integer greater than or equal to 2. , control method.

12. In the 11th paragraph, the step of generating the opening / closing control signal comprises: A step of generating the opening / closing control signal to supply the required amount of current through a clock unit comprising at least one clock, The above open / close control signal is: In order to supply the required amount of current, a signal is included to sequentially supply current from the first current source to the LED at least in one clock, and the first current source is connected to two consecutive k - The above consecutive 2 are not supplied to the above LED at 1 clock. k - A signal for supplying current to the LED by replacing the first current source of one clock with the second current source of one clock. , control method.

13. In paragraph 12, The above open / close control signal is: Including a signal for causing current from the first current source and the second current source to be supplied to the LED simultaneously at the first clock of the at least one clock, when the required current amount is equal to the sum of the supply current amounts of the first current source and the second current source. , control method.

14. In paragraph 12, The above open / close control signal is: A signal that causes current from the first current source and the second current source to be supplied to the LED simultaneously in all clocks of the at least one clock, when the required current amount is equal to an integer multiple of the sum of the supply current amounts of the first current source and the second current source. , control method.

15. In paragraph 11, The above open / close control signal is: If the required current amount is not a positive integer multiple of the sum of the supply current amounts of the first current source and the second current source, a signal is included to supply only the current from the second current source to the LED in the last clock among the clock units consisting of at least one clock. , control method.

16. In paragraph 11, In order to maintain the brightness resolution of the LED, the clock frequency for generating the open / close control signal is halved. k Including the steps to set it to double , control method.

17. In paragraph 10, A step of determining an operation configuration of the current source or the switch for compensating for a difference in brightness between multiple LED channels, and generating an opening / closing control signal of the switch according to the determined operation configuration. , control method.

18. In paragraph 10, According to the opening and closing control of the first switch and the second switch, the phenomenon of the brightness of the LED being reversed due to an increase in the amount of current supplied to the LED is alleviated. , control method.

19. A nonvolatile computer-readable medium storing a computer program configured to perform a method according to any one of claims 10 to 18.

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