CN1909754B - Light source device and light-adjustable light-emitting diode control circuit thereof - Google Patents

本发明是有关于一种光源装置与其可调光的发光二极管控制电路。所述发光二极管控制电路，可适用于控制液晶显示器中作为光源的多组发光二极管的发光亮度。此发光二极管控制电路包括计忆体、高频时脉产生器、微处理器和多数个发光二极管直流电流供应器单元。其中，计忆体用以储存多数个设计参数及程式。高频时脉产生器用以提供操作时脉。微处理器用以依据所述操作时脉、所述参数及程式而产生对应于所述直流电源供应器且频率固定并相同的多数个控制脉波信号，其中所述控制脉波信号的工作周期是依据一亮度调节信号而在一预设范围内变化但彼此相位不同，以分别控制所述直流电流供应单元的电流供应状态。而发光二极管直流电流供应器分别供应一直流电流至对应的发光二极管。

The present invention relates to a light source device and a dimmable light emitting diode control circuit thereof. The light emitting diode control circuit can be used to control the luminous brightness of multiple groups of light emitting diodes used as light sources in a liquid crystal display. The light emitting diode control circuit includes a memory, a high-frequency clock generator, a microprocessor and a plurality of light emitting diode DC current supply units. The memory is used to store a plurality of design parameters and programs. The high-frequency clock generator is used to provide an operating clock. The microprocessor is used to generate a plurality of control pulse signals corresponding to the DC power supply and having a fixed and identical frequency according to the operating clock, the parameters and the program, wherein the working cycle of the control pulse signal varies within a preset range according to a brightness adjustment signal but has different phases from each other, so as to respectively control the current supply state of the DC current supply unit. The LED DC current supply units respectively supply a DC current to the corresponding light emitting diodes.

光源装置与其可调光的发光二极管控制电路 Light source device and its adjustable light-emitting diode control circuit

技术领域technical field

本发明是有关于一种调光控制电路，是有关于一种用于以一个以上多数个发光二极管作为光源的波束密度调光控制电路，且特别是有关于一种用于以一个以上不同颜色多数个发光二极管作为光源的波束密度调光控制电路。The present invention relates to a dimming control circuit, and relates to a beam density dimming control circuit for using more than one light-emitting diode as a light source, and especially relates to a beam density dimming control circuit for using more than one light emitting diode in different colors. A plurality of light-emitting diodes are used as a beam density dimming control circuit of a light source.

背景技术Background technique

采用发光二极管(LED)作为发光源，可以用简单的直流电流驱动电路实现液晶显示器背光或一般照明的系统需求。因为特性的关系，发光二极管的亮度与驱动直流电流并不是呈线性关系变化，而且颜色也会随驱动电流变化而有所不同，这对于以发光二极管作为液晶显示器背光或一般照明的系统，在直接利用调整发光二极管驱动直流电流的方式调光的应用上产生很大的障碍。Using a light-emitting diode (LED) as a light source, a simple DC current drive circuit can be used to realize the system requirements of LCD backlight or general lighting. Because of the characteristics, the brightness of the light-emitting diode does not change in a linear relationship with the driving DC current, and the color will also vary with the change of the driving current. There are great obstacles in the application of dimming by adjusting the direct current driven by the light-emitting diode.

为克服利用电流调光的缺点，目前的作法是不以改变发光二极管驱电流振幅大小的方式调光，而是在发光二极管电流振幅大小固定的情况下，以一预设的工作频率下变化发光二极管电流波束密度的方式进行调光，以便可以使发光二极管在最大的调光范围内呈现出所需要的稳定的颜色。In order to overcome the shortcomings of using current dimming, the current practice is not to adjust the light by changing the amplitude of the LED driving current, but to change the light emission at a preset operating frequency when the current amplitude of the LED is fixed. Dimming is carried out by means of diode current beam density, so that the light-emitting diode can display the required stable color within the maximum dimming range.

请参阅图1及图2所示，图1为习知的以直流电流源驱动发光二极管并以波束密度调光控制输出电流的示意图，图2则为图1电路的亮度控制脉波信号与发光二极管驱动直流电流信号关系示意图。在图1中，控制发光二极管120或亮或暗的亮度控制脉波信号CNTL送入发光二极管直流电流供应器110，以控制发光二极管直流电流供应器110输出驱动发光二极管120的发光二极管驱动电流信号Id，所述电流是一根据亮度需求预设电流大小的固定电流。在图2中，(a)、(b)、(c)是三种受不同脉宽控制的发光二极管驱动电流信号Id的输出波形图，图2(a)是一个亮度只有全亮时20％的状况，图2(b)是一个亮度只有全亮时的60％的例子，而图2(c)则是一个亮度为全亮时的100％的例子。Please refer to Figure 1 and Figure 2. Figure 1 is a schematic diagram of a conventional DC current source to drive a light-emitting diode and control the output current by beam density dimming. Figure 2 shows the brightness control pulse signal and light emission of the circuit in Figure 1. Schematic diagram of the relationship between the diode driving DC current signal. In FIG. 1 , the brightness control pulse signal CNTL for controlling the LED 120 to be bright or dark is sent to the LED DC current supplier 110 to control the LED DC current supplier 110 to output the LED driving current signal for driving the LED 120 Id, the current is a fixed current whose size is preset according to the brightness requirement. In Fig. 2, (a), (b), (c) are output waveform diagrams of three kinds of light-emitting diode drive current signals Id controlled by different pulse widths, and Fig. 2 (a) is a luminance of only 20% when it is fully bright Figure 2(b) is an example where the brightness is only 60% of the full brightness, while Figure 2(c) is an example where the brightness is 100% of the full brightness.

为避免因为发光二极管的时亮时暗造成人眼视觉上的干扰，通常这个亮度控制脉波信号CNTL的频率并不能太低，一般都在200Hz以上。使用够高频率的亮度控制脉波信号CNTL，依据人眼视觉暂留的效应，让人眼只感受到发光二极管亮度的变化而不会闪烁。In order to avoid visual interference caused by the light-emitting diodes being on and off, the frequency of the brightness control pulse signal CNTL should not be too low, generally above 200 Hz. Using the brightness control pulse signal CNTL with a sufficiently high frequency, according to the effect of persistence of vision of the human eye, the human eye only feels the change of the brightness of the LED without flickering.

由于前述使用的亮度控制脉波信号CNTL的频率与工作周期是随着所需的亮度而设定的，因此一旦进行调光，亮度控制脉波信号CNTL的频率在液晶显示器背光的应用中，会遭遇与视讯显示信号中的垂直、水平扫描信号产生差频干扰的问题。因为背光与视讯信号不同频率的关系造成所谓的″风扇效应″，而在画面上形成干扰的水波纹。另外，发光二极管直流电流供应器的启动与关闭也会造成供应发光二极管直流电流供应器所需功率的电源供应器的负担，而在电源供应器产生与亮度控制脉波信号CNTL同频的涟波，这个涟波也会再次影响视讯显示信号造成画面闪烁。这些因为波束密度调光所造成的干扰，在使用越多发光二极管作为光源的场合会随着发光二极管操作功率的增加而更加严重.Since the frequency and duty cycle of the brightness control pulse signal CNTL used above are set according to the required brightness, once the dimming is performed, the frequency of the brightness control pulse signal CNTL in the application of the backlight of the liquid crystal display will be different. Encountered the problem of difference frequency interference with the vertical and horizontal scanning signals in the video display signal. Because of the so-called "fan effect" caused by the relationship between the different frequencies of the backlight and the video signal, interference water ripples are formed on the screen. In addition, the startup and shutdown of the LED DC current supply will also cause a burden on the power supply for supplying the power required by the LED DC current supply, and a ripple with the same frequency as the brightness control pulse signal CNTL will be generated in the power supply. , this ripple will affect the video display signal again and cause the picture to flicker. These interferences caused by beam density dimming will become more serious as the operating power of LEDs increases when more LEDs are used as light sources.

为避免亮度控制脉波信号CNTL与视讯显示信号中的垂直、水平扫描信号产生差频干扰的问题，有一种作法是将亮度控制脉波信号CNTL与水平扫描信号同步倍频或除频。另外，也可以将亮度控制脉波信号CNTL的频率提高，以减少对电源供应器造成涟波所形成的干扰，但在液晶显示器逐渐大型化的驱势下，发光二极管越用越多而其所消耗的功率也越来越大，而对视觉杂讯要求却又越来越严格的状况下，低杂讯、大范围调光在实际生产上也变得日益困难。In order to avoid the problem of difference frequency interference between the brightness control pulse signal CNTL and the vertical and horizontal scanning signals in the video display signal, one method is to synchronously multiply or divide the frequency of the brightness control pulse signal CNTL and the horizontal scanning signal. In addition, the frequency of the brightness control pulse signal CNTL can also be increased to reduce the interference caused by ripples on the power supply. The power consumption is also increasing, and the visual noise requirements are becoming more and more stringent. It is becoming more and more difficult to achieve low noise and wide-range dimming in actual production.

发明内容Contents of the invention

有鉴于此，本发明的目的是提供一种应用于有一个以上多数个发光二极管作为光源的低视觉杂讯波束密度调光控制电路，特别是由不同颜色的发光二极管所构成的光源。而藉由控制每个不同发光二极管亮度控制脉波信号的相位，以改善波束密度调光所产生的视觉杂讯干扰。In view of this, the object of the present invention is to provide a low visual noise beam density dimming control circuit applied to more than one LED as a light source, especially a light source composed of LEDs of different colors. By controlling the brightness of each different LED to control the phase of the pulse signal, the visual noise interference caused by beam density dimming can be improved.

本发明提供一种低视觉杂讯波束密度的发光二极管控制电路，可适用于控制例如是液晶显示器或其它需要光源的显示器中中作为光源的多组发光二极管的发光亮度。本发明的发光二极管控制电路包括计忆体、高频时脉产生器、微处理器和多数个发光二极管直流电流供应器单元。其中，计忆体用以储存多数个设计参数及程式。高频时脉产生器用以提供操作时脉。微处理器用以依据所述操作时脉、所述参数及程式而产生对应于所述直流电源供应器且频率固定并相同的多数个控制脉波信号，其中所述控制脉波信号的工作周期是依据一亮度调节信号而在一预设范围内变化但彼此相位不同，以分别控制所述直流电流供应单元的电流供应状态。而发光二极管直流电流供应器分别供应一直流电流至对应的发光二极管。The present invention provides a light emitting diode control circuit with low visual noise beam density, which is suitable for controlling the luminance of multiple groups of light emitting diodes used as light sources in liquid crystal displays or other displays requiring light sources. The light-emitting diode control circuit of the present invention includes a memory body, a high-frequency clock generator, a microprocessor and a plurality of light-emitting diode direct current supply units. Wherein, the memory is used to store a plurality of design parameters and programs. The high frequency clock generator is used to provide the operating clock. The microprocessor is used to generate a plurality of control pulse signals corresponding to the DC power supply and having a fixed frequency and the same frequency according to the operating clock, the parameters and the program, wherein the duty cycle of the control pulse signals is According to a brightness adjustment signal, they vary within a preset range but have different phases, so as to respectively control the current supply states of the direct current supply units. The LED DC current suppliers respectively supply a DC current to the corresponding LEDs.

在一实施例中，此发光二极管控制电路的亮度控制脉波产生单元包括了三角波产生器和比较器单元。其中，三角波产生器会产生多数组频率相同但不同相位的三角波。而比较器单元中的各比较器会将亮度调节信号与这些同频率但不同相位的三角波作比较，以产生前述的同频、同工作周期但不同相位的亮度控制脉波信号。In one embodiment, the brightness control pulse generation unit of the LED control circuit includes a triangular wave generator and a comparator unit. Among them, the triangular wave generator will generate multiple sets of triangular waves with the same frequency but different phases. Each comparator in the comparator unit compares the brightness adjustment signal with these triangular waves of the same frequency but different phases to generate the aforementioned brightness control pulse signals of the same frequency and the same duty cycle but different phases.

从另一观点来看，本发明另提供一种光源装置，可适用于液晶显示器。本发明的光源装置包括计忆体、高频时脉产生器、微处理器、多数个发光二极管直流电流供应器和多数个发光二极管。其中，计忆体用以储存多数个设计参数及程式。高频时脉产生器用以提供操作时脉。微处理器用以依据所述操作时脉、所述参数及程式而产生对应于所述直流电源供应器且频率固定并相同的多数个控制脉波信号，其中所述控制脉波信号的工作周期是依据一亮度调节信号而在一预设范围内变化但彼此相位不同，以分别控制所述直流电流供应单元的电流供应状态。而发光二极管直流电流供应器分别供应一直流电流至对应的发光二极管。From another point of view, the present invention further provides a light source device applicable to liquid crystal displays. The light source device of the present invention includes a memory body, a high-frequency clock generator, a microprocessor, a plurality of LED direct current suppliers and a plurality of LEDs. Wherein, the memory is used to store a plurality of design parameters and programs. The high frequency clock generator is used to provide the operating clock. The microprocessor is used to generate a plurality of control pulse signals corresponding to the DC power supply and having a fixed frequency and the same frequency according to the operating clock, the parameters and the program, wherein the duty cycle of the control pulse signals is According to a brightness adjustment signal, they vary within a preset range but have different phases, so as to respectively control the current supply states of the direct current supply units. The LED DC current suppliers respectively supply a DC current to the corresponding LEDs.

在较佳的实施例中，此低视觉杂讯波束密度调光控制电路的亮度控制脉波产生单元是由一数位式的微处理器及其它数位电路来实现。In a preferred embodiment, the brightness control pulse generating unit of the low visual noise beam density dimming control circuit is realized by a digital microprocessor and other digital circuits.

在本发明的实施例中，上述的亮度控制脉波信号的工作周期是依据亮度调节信号而在一预设范围内变化。In an embodiment of the present invention, the duty cycle of the brightness control pulse signal is varied within a preset range according to the brightness adjustment signal.

由上述说明中可知，应用本发明所提供的一种低视觉杂讯波束密度的发光二极管控制电路，则可藉由交错多组亮度控制脉波信号的相位，来改善波束密度调光所产生的视觉杂讯干扰。From the above description, it can be seen that by applying the light-emitting diode control circuit with low visual noise beam density provided by the present invention, the phase of the pulse wave signal can be controlled by interleaving multiple groups of brightness to improve the beam density dimming. Visual noise interference.

为让本发明的上述和其他目的、特征和优点能更明显易懂，下文特举较佳实施例，并配合所附图式，作详细说明如下。In order to make the above and other objects, features and advantages of the present invention more comprehensible, preferred embodiments will be described in detail below together with the accompanying drawings.

附图说明Description of drawings

图1是一种习知的波束密度调光控制电路示意图。FIG. 1 is a schematic diagram of a conventional beam density dimming control circuit.

图2是图1电路的亮度控制脉波信号与发光二极管驱动电流信号关系示意图。FIG. 2 is a schematic diagram of the relationship between the brightness control pulse signal and the LED driving current signal of the circuit in FIG. 1 .

图3是根据本发明较佳实施例的一种低视觉杂讯波束密度调光控制电路方块示意图。FIG. 3 is a schematic block diagram of a low visual noise beam density dimming control circuit according to a preferred embodiment of the present invention.

图4是根据本发明较佳实施例的一种亮度控制脉波产生单元电路示意图。FIG. 4 is a schematic circuit diagram of a brightness control pulse generating unit according to a preferred embodiment of the present invention.

图5A和图5B是图4的亮度控制脉波产生单元产生的亮度控制脉波信号示意图。5A and 5B are schematic diagrams of brightness control pulse signals generated by the brightness control pulse generation unit in FIG. 4 .

图6是根据本发明较佳实施例的一种数位式亮度控制脉波产生单元电路示意图实施。FIG. 6 is a schematic circuit diagram implementation of a digital brightness control pulse generation unit according to a preferred embodiment of the present invention.

110、321、322、32N：发光二极管直流电流供应器110, 321, 322, 32N: LED DC current supply

120、330、331、332、33N：发光二极管120, 330, 331, 332, 33N: LED

300：低视觉杂讯波束密度调光控制电路300: Low visual noise beam density dimming control circuit

310、400：亮度控制脉波产生单元310, 400: brightness control pulse wave generation unit

410：三角波产生器410: Triangular Wave Generator

420、401、402、40N：比较器420, 401, 402, 40N: Comparators

610：数位式亮度控制脉波产生单元610: Digital brightness control pulse wave generating unit

620：微处理器620: Microprocessor

630：高频时脉产生器630: High Frequency Clock Generator

640：记忆体640: memory

具体实施方式Detailed ways

请参考图3所示，其为根据本发明较佳实施例的一种低视觉杂讯波束密度调光控制电路方块示意图，此低视觉杂讯波束密度调光控制电路300可适用于控制液晶显示器中的多组发光二极管330的发光亮度。Please refer to FIG. 3 , which is a block diagram of a low visual noise beam density dimming control circuit 300 according to a preferred embodiment of the present invention. The low visual noise beam density dimming control circuit 300 is suitable for controlling liquid crystal displays. The luminous brightness of the multiple groups of light emitting diodes 330 in.

如图所示，此低视觉杂讯波束密度调光控制电路300包括：亮度控制脉波(脉冲)产生单元310，发光二极管直流电流供应器单元320以及发光二极管330。其中，亮度控制脉波产生单元310用以接收亮度调节信号BTNS，并依据亮度调节信号BTNS来产生多组亮度控制脉波信号CNTL1、CNTL2、...、CNTLN。As shown in the figure, the low visual noise beam density dimming control circuit 300 includes: a brightness control pulse (pulse) generating unit 310 , an LED DC current supply unit 320 and an LED 330 . Wherein, the brightness control pulse generating unit 310 is used for receiving the brightness adjustment signal BTNS, and generating multiple groups of brightness control pulse signals CNTL1, CNTL2, . . . , CNTLN according to the brightness adjustment signal BTNS.

其中，发光二极管直流电流供应器单元320中的每一个直流电流供应器321、322、...、32N分别供应不同组发光二极管331、332、...、33N不同组电流Id1、Id2、...、IdN。这些驱动电流Id1、Id2、...、IdN在发光二极管331、332、...、33N的颜色相同时，可以是根据亮度需求而设定相同电流大小的预定值。当发光二极管331、332、...、33N的颜色不同时，例如红，蓝，绿三色，也可以是根据亮度及混光后的颜色，例如白色，而设定彼此电流大小不相等的电流值。Wherein, each of the direct current suppliers 321, 322, . . . . IdN. These driving currents Id1, Id2, . When the colors of the light emitting diodes 331, 332, ..., 33N are different, such as red, blue, and green, they can also be set to have unequal currents according to the brightness and the color after light mixing, such as white. current value.

这些依据亮度控制脉波产生单元310产生的亮度控制脉波信号CNTL1、CNTL2、...、CNTLN，会分别对应控制发光二极管直流电流供应器单元320中的每一个直流电流供应器321、322、...、32N，以决定每一组发光二极管331、332、...、33N的导通电流Id1、Id2、...、IdN的导通或截止状态。These brightness control pulse signals CNTL1, CNTL2, . . . . , 32N, to determine the on or off state of the conduction current Id1, Id2, . . . , IdN of each group of LEDs 331, 332, .

在本发明中，为了改善波束密度调光所产生的视觉杂讯干扰，故将这多组亮度控制脉波信号CNTL1、CNTL2、...、CNTLN的相位交错控制，以降低不同组发光二极管331、332、...、33N在任一时间点上只有其中一组因为调光而改变截止或导通的状况。In the present invention, in order to improve the visual noise interference caused by beam density dimming, the phase interleaving control of the multiple groups of brightness control pulse signals CNTL1, CNTL2, ..., CNTLN is performed to reduce the number of different groups of light emitting diodes 331. , 332 , .

由于发光二极管不是同时因为调光而一起改变截止或导通状态，因此可以大幅降低由发光二极管改变导通状态所产生的电源功率杂讯。这些电源功率杂讯在发光二极管作为液晶显示器光源时与视讯显示信号中的垂直、水平扫描信号产生差频干扰，造成所谓的″风扇效应″，而在画面上形成干扰的水波纹。Since the light emitting diodes do not change the off state or the on state at the same time due to the dimming, the power supply noise generated by the light emitting diodes changing the on state can be greatly reduced. When these power supply noises are used as the light source of the liquid crystal display, the light-emitting diodes generate frequency interference with the vertical and horizontal scanning signals in the video display signal, causing the so-called "fan effect", and forming disturbing water ripples on the screen.

请参考图4所示，这是根据本发明较佳实施例的一种亮度控制脉波产生单元电路示意图，此亮度控制脉波产生单元400包括了三角波产生器410和比较器单元420。其中，三角波产生器410产生一组以上频率相同而且不同相位的三角波Tri1、Tri2、...、TriN，而比较器单元420中的各比较器401、402、...、40N将亮度调节信号BTNS与这些同频率不同相位的三角波Tri1、Tri2、...、TriN作比较，产生前述的同频、同工作周期但不同相位的亮度控制脉波信号CNTL1、CNTL2、...、CNTLN。Please refer to FIG. 4 , which is a schematic circuit diagram of a brightness control pulse generation unit according to a preferred embodiment of the present invention. The brightness control pulse generation unit 400 includes a triangular wave generator 410 and a comparator unit 420 . Among them, the triangular wave generator 410 generates more than one set of triangular waves Tri1, Tri2, ..., TriN with the same frequency and different phases, and each comparator 401, 402, ..., 40N in the comparator unit 420 converts the brightness adjustment signal BTNS is compared with these triangular waves Tri1, Tri2, .

为更清楚说明本发明的精神，因此当本实施例所控制的是三组发光二极管时，其各控制信号的时序关系图可如图5A和图5B所示，其中图5A所示的是当所控制的亮度是发光二极管全亮时的2/3，即66.67％时的时序图，而图5B则绘示当所控制的亮度是发光二极管全亮时的1/3，即33.33％时的时序图。In order to illustrate the spirit of the present invention more clearly, when three groups of light-emitting diodes are controlled in this embodiment, the timing diagrams of the control signals can be shown in Figure 5A and Figure 5B, where Figure 5A shows when the three groups of light-emitting diodes are controlled. The controlled brightness is 2/3 of when the light-emitting diodes are fully bright, that is, the timing diagram at 66.67%, and Figure 5B shows the timing diagram when the controlled brightness is 1/3 of when the light-emitting diodes are fully bright, that is, 33.33%. .

当本实施例中三组三角波信号Tri1、Tri2以及Tri3的相位差相差60°时，在与亮度调节信号BTNS比较后也会产生不同相位的亮度控制脉波信号CNTL1、CNTL2以及CNTL3。以这样的信号控制发光二极管，可以使三组发光二极管不同时改变导通或截止状态，使整个电源线上在任一时间上永远只有一组发光二极管改变导通或截止状态。相较于三组同时变换导通状况的控制方式，本发明可以将电源线上的涟波降到1/3。When the phase difference of the three sets of triangular wave signals Tri1, Tri2 and Tri3 in this embodiment is 60°, the brightness control pulse signals CNTL1, CNTL2 and CNTL3 with different phases will be generated after comparing with the brightness adjustment signal BTNS. Controlling the light-emitting diodes with such a signal can make the three groups of light-emitting diodes not change the on or off state at the same time, so that only one group of light-emitting diodes will always change the on or off state on the entire power line at any time. Compared with the control mode in which three groups change the conduction status at the same time, the present invention can reduce the ripple on the power line to 1/3.

虽然上述仅提供三组发光二极管的控制方式，然而熟习此技艺者可以依照本发明的精神，而任意衍生至更多组的发光二极管控制电路。Although the above only provides three groups of LED control methods, those skilled in the art can arbitrarily derive more groups of LED control circuits according to the spirit of the present invention.

当发光二极管组数不断增加时，以数位电路来实施本发明可以更精准的控制更多组发光二极管。图6即是一个利用数位的微处理器(MCU)以及其它数位电路构成的实施例。When the number of groups of light-emitting diodes increases continuously, implementing the present invention with a digital circuit can control more groups of light-emitting diodes more precisely. Fig. 6 promptly is an embodiment that utilizes digital microprocessor (MCU) and other digital circuits to form.

在图6的实施例中，数位式亮度控制脉波产生单元610包括了微处理器620、高频时脉产生器630以及用来储存所有设计参数及程式的计忆体640。高频时脉产生器630除了提供微处理器620所需的操作时脉CLK之外，微处理器利用此高频时脉配合其内部的除法器及计数器(未绘示)，并根据输入的亮度调节信号BTNS可以产生出具有预设频率及工作周期的亮度脉波信号CNTL1、CNTL2、...、CMTLN。而存于记忆体(存储设备)640中的所有设计参数及程式正是用来决定微处理器620计算所产生出这许多组亮度脉波信号CNTL1、CNTL2、...、CNTLN其工作频率，以及各亮度脉波信号彼此之间的相位关系。In the embodiment of FIG. 6 , the digital brightness control pulse generation unit 610 includes a microprocessor 620 , a high-frequency clock generator 630 and a memory 640 for storing all design parameters and programs. In addition to providing the operating clock CLK required by the microprocessor 620, the high-frequency clock generator 630 uses the high-frequency clock to cooperate with its internal divider and counter (not shown), and according to the input The brightness adjustment signal BTNS can generate brightness pulse signals CNTL1 , CNTL2 , . . . , CMTLN with preset frequencies and duty cycles. All the design parameters and programs stored in the memory (storage device) 640 are used to determine the operating frequencies of the many groups of brightness pulse signals CNTL1, CNTL2, ..., CNTLN generated by the calculation of the microprocessor 620, And the phase relationship between each brightness pulse signal.

由于亮度脉波信号CNTL1、CNTL2、...、CMTLN的工作周期，是根据输入的亮度调节信号BTNS，并且利用数位计数器对高频时脉产生器630所产生的时脉CLK计数。因此，每一组亮度脉波信号CNTL1、CNTL2、...、CNTLN之间几乎没有任何误差(Offset)。回顾图4的实施例，因为各比较器401、402、...、40N间的误差并不相同，而这些误差电压又有其各自独立的温度系数。因此，图6这样的数位信号产生方式在相较于图4的实施例之下有极佳的操作稳定度。因此很适合更多组复杂而又需要精准调光的控制电路。特别是当发光二极管的白色光是由各种不同色光发光二极管加以混合而成的场合。因为这样的系统中，一但不同颜色光发光二极管的发光工作周期比例发生改变例如：CNTL1的工作周期≠CNTL2工作周期≠...、≠工作周期CNTLN，其混光的结果就会改变，其颜色就会随之而变。如此，这些发光二极管便可根据需要变化出任意的色彩，而在图6实施例中的记忆体则可以根据需要储存决定各种不同颜色，亮度的内容产生每一组亮度脉波信号CNTL1、CNTL2、...、CNTLN。The duty cycles of the brightness pulse signals CNTL1, CNTL2, . Therefore, there is almost no error (offset) among each group of brightness pulse signals CNTL1 , CNTL2 , . . . , CNTLN. Referring back to the embodiment of FIG. 4 , because the errors among the comparators 401 , 402 , . . . , 40N are not the same, and these error voltages have their own independent temperature coefficients. Therefore, compared with the embodiment in FIG. 4 , the digital signal generation method shown in FIG. 6 has excellent operational stability. Therefore, it is very suitable for more complex control circuits that require precise dimming. Especially when the white light of the light-emitting diode is mixed by various light-emitting diodes of different colors. Because in such a system, once the light-emitting duty cycle ratio of light-emitting diodes of different colors changes, for example: the duty cycle of CNTL1≠CNTL2 duty cycle≠..., ≠ duty cycle CNTLN, the result of light mixing will change, and its The color will change accordingly. In this way, these light-emitting diodes can change any color according to the needs, and the memory in the embodiment of FIG. , ..., CNTLN.

在图6实施例中，为了使系统在作为液晶显示器光源应用时所产生的视觉杂讯更进一步得到降低，还可以利用由液晶显示器所产生的时脉信号DCLK，当作为高频时脉产生器630的输入信号来产生高频时脉CLK，以避免因为”差频干扰”造成的水波纹出现在显示器上。In the embodiment in Figure 6, in order to further reduce the visual noise generated by the system when it is used as a light source for a liquid crystal display, the clock signal DCLK generated by the liquid crystal display can also be used as a high-frequency clock generator 630 input signal to generate high-frequency clock pulse CLK to avoid water ripples on the display caused by "beat frequency interference".

虽然本发明已以较佳实施例揭露如上，然其并非用以限定本发明，任何熟习此技术的人员，在不脱离本发明的精神和范围内，当可作些许的更动与润饰，因此本发明的保护范围当视后附的权利要求所界定的为准。Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore The protection scope of the present invention shall prevail as defined by the appended claims.