CN101004894A - Scanning LED display device and method for eliminating its forward hidden brightness - Google Patents

Abstract

The invention relates to a scanning type LED display device and a method for eliminating forward moving hidden brightness of the scanning type LED display device, wherein the scanning type LED display device comprises a plurality of row drivers, a column driver, a plurality of row LEDs and a discharging device, wherein the output ends of the row drivers are connected with the discharging device. The method for eliminating the forward hidden brightness comprises the following steps: 1) detecting the change of a row selection signal of the scanning type LED display device; 2) when the change of a row selection signal of the scanning type LED display device is detected, a discharge control signal is generated, so that when or before a certain row of LEDs is lightened, the electric charge on the output end of a row driver connected with the anode of the previous row of LEDs is discharged, and the hidden lightening of the previous row of LEDs when the certain row of LEDs is lightened is eliminated.

Description

Translated fromChinese

扫描型LED显示装置及消除其前行隐亮的方法Scanning LED display device and method for eliminating its forward hidden brightness

【技术领域】【Technical field】

本发明涉及一种LED显示装置，尤其涉及一种扫描型LED显示屏；此外，本发明还涉及一种消除LED显示装置前行隐亮的方法。The present invention relates to an LED display device, in particular to a scanning LED display screen; in addition, the present invention also relates to a method for eliminating the LED display device's forward dimming.

【背景技术】【Background technique】

发光二极管的英文是Light Emitting Diode(LED)，它的基本结构是一块电致发光的半导体材料，置于一个有引线的架子上，然后四周用环氧树脂密封，当它处于正向工作状态时(即两端加上正向电压)，电流从LED阳极流向阴极时，半导体材料就会发光，光的强弱与电流大小有关。多年来，LED一直在平板显示领域扮演着重要的角色，并且依靠其独特的高亮度、高强度、长寿命、可拼接使用、方便灵活等优点，使得它在大面积室内外显示，特别在体育，广告，金融、展览、交通等领域的应用相当广泛。The English of light-emitting diode is Light Emitting Diode (LED), its basic structure is a piece of electroluminescent semiconductor material, placed on a shelf with leads, and then sealed with epoxy resin around it, when it is in the forward working state (that is, a forward voltage is applied to both ends), when the current flows from the anode to the cathode of the LED, the semiconductor material will emit light, and the intensity of the light is related to the magnitude of the current. For many years, LED has been playing an important role in the field of flat panel display, and relying on its unique advantages of high brightness, high strength, long life, splicing, convenience and flexibility, it can be displayed indoors and outdoors in large areas, especially in sports , Advertising, finance, exhibition, transportation and other fields are widely used.

LED显示器根据显示控制方式可分为静态与扫描两种。静态显示就是对LED电子显示屏中的每一LED都通过硬件单独控制，整个LED显示屏所有的LED同时受控。此方式最大优点是程序设计简单，且画面无闪烁。但这种设计存在致命的缺点：电路复杂，硬件利用率低，成本巨大。LED displays can be divided into static and scanning according to the display control method. Static display means that each LED in the LED electronic display is controlled individually by hardware, and all LEDs in the entire LED display are controlled at the same time. The biggest advantage of this method is that the program design is simple and the screen does not flicker. But there are fatal shortcomings in this design: complex circuit, low hardware utilization, and huge cost.

而随着LED制造工艺的进步，LED的亮度有了明显的提高，目前LED显示屏越来越多的采用动态扫描实现显示过程，此方式是将显示屏上所有的LED分成N组，每组称为一行。若要显示一帧画面，先通过行驱动器送出第一行的数据，然后通过列驱动器选通并点亮第一行中的LED，此后送出第二行的数据，同样选通、点亮第二行LED；依次将所有行扫描完，即给出了一帧的画面，注意此处的点亮是指一行LED同时被行驱动器和列驱动器控制。因此，这种显示方法的扫描频率越高，画面就越稳定，要使人眼看上去的画面达到稳定，扫描频率至少要120赫兹，欧洲的标准为300赫兹，要使经摄象机拍摄后的画面达到稳定的效果，扫描频率则需更高。With the advancement of LED manufacturing technology, the brightness of LED has been significantly improved. At present, more and more LED display screens use dynamic scanning to realize the display process. This method is to divide all LEDs on the display screen into N groups, each group called a row. To display a frame of picture, first send the data of the first row through the row driver, then strobe and light the LED in the first row through the column driver, then send the data of the second row, similarly strobe and light the LED in the second row Row LED: After scanning all the rows in turn, a frame of picture is given. Note that the lighting here means that a row of LEDs is controlled by the row driver and the column driver at the same time. Therefore, the higher the scanning frequency of this display method, the more stable the picture will be. To make the picture look stable to the human eye, the scanning frequency must be at least 120 Hz, and the European standard is 300 Hz. To achieve a stable image, the scanning frequency needs to be higher.

图19所示一种典型的扫描型LED显示装置90，其包括接收行选择信号(HSEL)的行译码器91。该行译码器91接收控制系统(未图示)输出的行选择信号HSEL，并将该行选择信号进行译码后，输出若干行译码输出(H1A～HnA)。若干行驱动器92对应接收该若干行译码输出，然后从其输出端921，输出行信号(H1～Hn)，也即驱动电压，加载在正极连接在对应驱动输出端921的LED(请参阅图19中标号93)。该列驱动器94与LED的负极连接，主要用来接收从该控制系统输出的时钟信号Clk、加载信号Load、使能信号En和数据信号Data，来控制各列的LED是否发光以及发光时间。通过该行信号和该时钟信号Clk、加载信号Load、使能信号En和数据信号Data控制该列驱动器94和各行驱动器92，从而可控制每个LED是否发光，来显示需要的图面、文字等信息。FIG. 19 shows a typical scanning LED display device 90, which includes arow decoder 91 receiving a row selection signal (HSEL). Therow decoder 91 receives a row selection signal HSEL output from a control system (not shown), decodes the row selection signal, and outputs several row decoding outputs (H1A˜HnA). A plurality ofrow drivers 92 correspondingly receive the decoding outputs of the plurality of rows, and then output row signals (H1 to Hn) from theiroutput terminals 921, that is, driving voltages, which are loaded on the LEDs whose anodes are connected to the corresponding driving output terminals 921 (see FIG. No. 93 in 19). Thecolumn driver 94 is connected to the negative pole of the LED, and is mainly used to receive the clock signal Clk, load signal Load, enable signal En and data signal Data output from the control system to control whether the LEDs in each column emit light and when. Thecolumn driver 94 and eachrow driver 92 are controlled by the row signal, the clock signal Clk, the load signal Load, the enable signal En and the data signal Data, so as to control whether each LED emits light to display the required graphics, characters, etc. information.

但是，该扫描型LED显示装置90经常存在隐亮问题。具体来讲，如图19和图20所示，各行驱动器92一般都使用芯片FDS4953双路P沟道场效应管或其他芯片，容易产生节电容问题。以下以芯片FDS4953双路P沟道场效应管为例进行说明。在如图19所示的扫描电路中，由于使用该芯片FDS4953双路P沟道场效应管，当m行的行驱动器92被关断后，由于节电容的问题，该m行的行驱动器92的驱动输出端921上会储存有电荷，从而在m行的LED的正极产生一个虚高电压，该虚高电压一直保持到该列驱动器94的对应列打开，其存在时间为Tx。However, the scanning LED display device 90 often has the problem of hidden brightness. Specifically, as shown in FIG. 19 and FIG. 20 , eachrow driver 92 generally uses the chip FDS4953 dual-channel P-channel field effect transistor or other chips, which is prone to the problem of junction capacitance. The following takes the chip FDS4953 dual-channel P-channel field effect transistor as an example to illustrate. In the scanning circuit shown in Figure 19, due to the use of the chip FDS4953 dual-channel P-channel field effect transistor, when therow driver 92 of the m row is turned off, due to the problem of the junction capacitance, therow driver 92 of the m row is turned off. Charges will be stored on thedriving output terminal 921 , so that a false high voltage will be generated at the anodes of the LEDs in m rows, and the virtual high voltage will remain until the corresponding column of thecolumn driver 94 is turned on, and the existence time is Tx.

当m+1行被点亮时，此时列驱动器94的对应列为打开状态。由于m行的LED的正极有虚高电压，因此m行LED正极上的电荷将通过列驱动器94的对应列而释放，因此本来m行应不亮的LED，在m+1行被点亮的同时，也出现隐亮，该隐亮时间Ty为从该虚高电压到LED的临界点亮电压Vled所需要的时间。When the m+1 row is turned on, the corresponding column of thecolumn driver 94 is turned on. Since the anodes of the LEDs in the m rows have a virtual high voltage, the charge on the anodes of the LEDs in the m rows will be released through the corresponding column of thecolumn driver 94, so the LEDs that should not be bright in the m rows are lit in the m+1 row Simultaneously, dim lighting also occurs, and the dim lighting time Ty is the time required from the virtual high voltage to the critical lighting voltage Vled of the LED.

此外，影响隐亮程度的因素有两个方面：一方面：LED的最小点亮电流。最小点亮电流越小，隐亮越厉害。早期的LED因为亮度低，最小点亮电流较大，所以隐亮问题不明显。然而，近来随着LED亮度的提高，导致隐亮问题约来越明显。另一方面：行扫描频率。行扫描频率决定了单位时间内各行点亮的次数，行扫描频率越高，由于上述原因LED每秒隐亮的次数就越多，行隐亮问题就会越严重。In addition, there are two factors that affect the degree of hidden brightness: On the one hand: the minimum lighting current of the LED. The smaller the minimum lighting current, the stronger the hidden lighting. Early LEDs had low brightness and high minimum lighting current, so the problem of hidden lighting was not obvious. However, with the improvement of LED brightness recently, the problem of hidden brightness has become more and more obvious. On the other hand: line scan frequency. The line scanning frequency determines the number of times each line is lit per unit time. The higher the line scanning frequency is, the more times the LED is dimly lit per second due to the above reasons, and the problem of line dimming will be more serious.

另外，影响隐亮程度还与m+1中发光LED的个数有关。因为发光LED的数目越多，电流的通路就越多，每个通路流过的电流较小，而且放电的速度比较快，因此导致每个导通LED隐亮不明显；当m+1中仅仅一个LED发光时，因此发光时间比较长，从而导致该LED发光较亮，出现较强的隐亮。In addition, the influence on the hidden brightness is also related to the number of light-emitting LEDs in m+1. Because the more the number of light-emitting LEDs, the more current paths, the smaller the current flowing through each path, and the faster the discharge speed, so that each conduction LED is dimly bright; when only m+1 When an LED emits light, it takes a relatively long time to emit light, which causes the LED to emit light brighter and has a stronger hidden brightness.

当LED显示屏出现行隐亮问题时，就会使显示画面中应该亮的LED周围有不该亮的LED发亮，从而影响画面显示效果。随着LED亮度的加强和LED屏行扫描频率的提高，对画面的显示效果影响越严重。When the LED display screen has a problem of hidden lighting, it will cause the LEDs that should not be bright to light up around the LEDs that should be bright in the display screen, thereby affecting the display effect of the screen. With the enhancement of the LED brightness and the increase of the scanning frequency of the LED screen, the effect on the display effect of the picture will be more serious.

有鉴于此，提供一种克服以上缺陷的扫描型LED显示装置及其消除前行隐亮的方法成为目前急需解决的技术课题。In view of this, it is an urgent technical problem to provide a scanning LED display device that overcomes the above defects and a method for eliminating the hidden light in the forward direction.

【发明内容】【Content of invention】

本发明的一个目的在于提供可有效消除前行隐亮以提高显示效果的扫描型LED显示装置。An object of the present invention is to provide a scanning LED display device that can effectively eliminate hidden lighting in the forward direction to improve the display effect.

本发明的另一个目的在于提供可有效消除前行隐亮以提高显示效果的消除前行隐亮的方法。Another object of the present invention is to provide a method for eliminating hidden forward brightness that can effectively eliminate hidden forward brightness to improve display effect.

为实现上述目的，本发明提供一种扫描型LED显示装置，其包括：若干行驱动器、列驱动器和若干行LED，其中每个行驱动器的输出端连接对应行LED的正极，该列驱动器的输出端与连接在该行驱动器上的LED的负极对应连接，其中该扫描型LED显示装置还包括与该若干行驱动器的输出端连接的放电装置，使得某一行LED被点亮时或之前，泄放连接前一行LED正极的行驱动器的输出端上的电荷，以消除该前一行LED在该某一行LED点亮时产生隐亮。In order to achieve the above object, the present invention provides a scanning LED display device, which includes: several row drivers, column drivers and several rows of LEDs, wherein the output of each row driver is connected to the positive pole of the corresponding row of LEDs, and the output of the column driver terminal is correspondingly connected to the negative poles of the LEDs connected to the row driver, wherein the scanning LED display device also includes a discharge device connected to the output terminals of the several row drivers, so that when or before a certain row of LEDs is lit, discharge The charge on the output terminal of the row driver connected to the anode of the previous row of LEDs is used to eliminate the hidden lighting of the previous row of LEDs when the certain row of LEDs is turned on.

此外，本发明还提供一种消除扫描型LED显示装置前行隐亮的方法，其包括以下步骤：In addition, the present invention also provides a method for eliminating the forward dimming of a scanning LED display device, which includes the following steps:

1)检测扫描型LED显示装置的行选择信号的变化；1) detecting the change of the row selection signal of the scanning LED display device;

2)当检测到该扫描型LED显示装置的行选择信号的变化，产生一个放电控制信号，使得某一行LED被点亮时或之前，泄放连接前一行LED正极的行驱动器的输出端上的电荷，以消除该前一行LED在该某一行LED点亮时产生隐亮。2) When the change of the row selection signal of the scanning LED display device is detected, a discharge control signal is generated, so that when or before a certain row of LEDs is lit, the output terminal of the row driver connected to the positive pole of the previous row of LEDs is discharged. Electric charge, to eliminate the LEDs in the previous row when the LEDs in a certain row are turned on.

与现有技术相比，本发明扫描型LED显示装置的每个行驱动器的输出端连接有放电装置，从而可有效消除扫描型LED显示装置前行隐亮以提高其显示效果。Compared with the prior art, the output terminal of each row driver of the scanning LED display device of the present invention is connected with a discharge device, so that the scanning LED display device can effectively eliminate the hidden light in the forward direction and improve its display effect.

另外，与现有技术相比，本发明消除扫描型LED显示装置前行隐亮的方法包括以下特征步骤：In addition, compared with the prior art, the method of the present invention for eliminating the hidden light in the forward direction of the scanning LED display device includes the following characteristic steps:

1)检测扫描型LED显示装置的行选择信号的变化；1) detecting the change of the row selection signal of the scanning LED display device;

2)当检测到该扫描型LED显示装置的行选择信号的变化，产生一个放电控制信号，使得某一行LED被点亮时或之前，泄放连接前一行LED正极的行驱动器的输出端上的电荷，以消除该前一行LED在该某一行LED点亮时产生隐亮。2) When the change of the row selection signal of the scanning LED display device is detected, a discharge control signal is generated, so that when or before a certain row of LEDs is lit, the output terminal of the row driver connected to the positive pole of the previous row of LEDs is discharged. Electric charge, to eliminate the LEDs in the previous row when the LEDs in a certain row are turned on.

通过上述方法，可有效消除扫描型LED显示装置前行隐亮以提高其显示效果。Through the above method, the scanning LED display device can be effectively eliminated to improve its display effect.

【附图说明】【Description of drawings】

图1是本发明第一实施例扫描型LED显示装置的部分电路原理简图。FIG. 1 is a schematic diagram of some circuits of a scanning LED display device according to the first embodiment of the present invention.

图2是图1中行译码器的电路原理简图。Fig. 2 is a schematic diagram of the circuit principle of the row decoder in Fig. 1 .

图3是发明第一实施例放电装置的电路原理简图。Fig. 3 is a schematic diagram of the circuit principle of the discharge device according to the first embodiment of the invention.

图4是发明第一实施例放电装置在行驱动器输出端上的加载关闭后泄放该输出端上电荷的时序示意图。FIG. 4 is a schematic diagram of the time sequence of discharging the charge on the output terminal of the row driver after the load on the output terminal of the row driver is turned off by the discharge device according to the first embodiment of the invention.

图5是产生列隐亮的电路原理简图。Figure 5 is a simplified schematic diagram of the circuit principle for generating column brightness.

图6是发明第二实施例放电装置的电路原理简图。Fig. 6 is a schematic diagram of the circuit principle of the discharge device according to the second embodiment of the invention.

图7是发明第二实施例放电装置在行驱动器输出端上的加载关闭后泄放该输出端上电荷的时序示意图。FIG. 7 is a schematic diagram of the time sequence of discharging the charge on the output terminal of the row driver after the load on the output terminal of the row driver is turned off by the discharge device according to the second embodiment of the invention.

图8是发明第三实施例扫描型LED显示装置的部分电路原理简图。Fig. 8 is a schematic diagram of some circuits of the scanning LED display device according to the third embodiment of the invention.

图9是图8中放电控制电路的稳态触发器的电路原理简图。FIG. 9 is a schematic circuit schematic diagram of a steady-state trigger of the discharge control circuit in FIG. 8 .

图10是图8中放电控制电路的或门电路的电路原理简图。FIG. 10 is a schematic circuit schematic diagram of the OR gate circuit of the discharge control circuit in FIG. 8 .

图11是发明第三实施例放电装置的电路原理简图。Fig. 11 is a schematic diagram of the circuit principle of the discharge device according to the third embodiment of the invention.

图12是发明第三实施例扫描型LED显示装置电路的信号时序示意图。FIG. 12 is a schematic diagram of the signal sequence of the circuit of the scanning LED display device according to the third embodiment of the invention.

图13是发明第三实施例放电装置在行驱动器输出端上的加载关闭后泄放该输出端上电荷的时序示意图。FIG. 13 is a schematic diagram of the time sequence of discharging the charge on the output terminal of the row driver after the load on the output terminal of the row driver is turned off by the discharge device according to the third embodiment of the invention.

图14是发明第四实施例扫描型LED显示装置的部分电路原理简图。Fig. 14 is a schematic diagram of part of the circuit principle of the scanning LED display device according to the fourth embodiment of the invention.

图15是图14中行译码器的电路原理简图。Fig. 15 is a schematic diagram of the circuit principle of the row decoder in Fig. 14 .

图16是发明第四实施例放电装置的电路原理简图。Fig. 16 is a schematic diagram of the circuit principle of the discharge device according to the fourth embodiment of the invention.

图17是发明第四实施例扫描型LED显示装置电路的信号时序示意图。Fig. 17 is a schematic diagram of the signal sequence of the circuit of the scanning LED display device according to the fourth embodiment of the invention.

图18是发明第四实施例放电装置在行驱动器输出端上的加载关闭后泄放该输出端上电荷的时序示意图。FIG. 18 is a schematic diagram of the time sequence of discharging the charge on the output terminal of the row driver after the load on the output terminal of the row driver is turned off by the discharge device according to the fourth embodiment of the invention.

图19是现有扫描型LED显示装置的部分电路原理简图。FIG. 19 is a schematic diagram of some circuits of a conventional scanning LED display device.

图20是图19中扫描型LED显示装置的行驱动器的输出端在加载关闭或断开后该输出端上电荷释放的时序示意图。FIG. 20 is a schematic diagram of the time sequence of the discharge of charges on the output terminal of the row driver of the scanning LED display device in FIG. 19 after the load is turned off or disconnected.

【具体实施方式】【Detailed ways】

以下结合附图对本发明进行详细说明。The present invention will be described in detail below in conjunction with the accompanying drawings.

本发明扫描型LED显示装置主要用于显示各种外设(如电脑、播放器、脱机系统等)传递过来的图像、文字等信息，但并不局限于此。The scanning LED display device of the present invention is mainly used for displaying information such as images and text transmitted by various peripheral devices (such as computers, players, offline systems, etc.), but is not limited thereto.

如图1所示，本发明第一实施例扫描型LED显示装置10主要包括行译码器11、行驱动器12、若干行LED(请参阅图1中标号13)、列驱动器14、级联电路(未图示)以及放电装置16A等，以下详细说明。As shown in FIG. 1, the scanningLED display device 10 of the first embodiment of the present invention mainly includes arow decoder 11, arow driver 12, several rows of LEDs (please refer to thenumber 13 in FIG. 1), acolumn driver 14, and a cascaded circuit. (not shown), the discharge device 16A, and the like will be described in detail below.

该若干行LED可以以矩阵的方式排列，在显示屏面积比较大的情况下，该LED可布置在若干单元板(如电路板)上，然后拼成一个大的显示屏；在显示屏较小的情况下，也可直接布置在一块基板，如电路板，也可根据需要排列成各种尺寸的显示屏。为了便于说明，图1所示为部分LED的排布，因此并不局限于此。The several rows of LEDs can be arranged in a matrix. In the case of a relatively large display area, the LEDs can be arranged on several unit boards (such as circuit boards) to form a large display screen; In some cases, it can also be directly arranged on a substrate, such as a circuit board, and can also be arranged into display screens of various sizes according to needs. For ease of description, FIG. 1 shows the arrangement of some LEDs, and therefore is not limited thereto.

在本实施例中，如图3所示，为了便于说明，采用八行LED，省略了列驱动电路；该译码器11为现有74HC138芯片(如图2所示)，但并不局限于此，根据LED的行数，也可采用其他型号的译码器。该74HC138芯片通过第1脚、第2脚和第3脚来接收行选择信号HSEL0、HSEL1、HSEL2，然后对其进行译码，从第15脚、第14脚......第7脚产生行译码输出H1A、H2A......H8A，其信号时序可参阅图12，以下详细说明。In this embodiment, as shown in Figure 3, for ease of illustration, eight rows of LEDs are used, and the column drive circuit is omitted; thedecoder 11 is an existing 74HC138 chip (as shown in Figure 2), but it is not limited to Therefore, other types of decoders can also be used according to the number of rows of LEDs. The 74HC138 chip receives row selection signals HSEL0, HSEL1, and HSEL2 throughpins 1, 2, and 3, and then decodes them. Frompins 15, 14...7 The row decoding outputs H1A, H2A...H8A are generated, and its signal timing can be referred to FIG. 12 , which will be described in detail below.

如图1所示，每个行译码输出与一个对应的行驱动器12连接，该行驱动器12用来接收控制系统(未图示)输出的行选择信号HSEL0、HSEL1、HSEL2，该控制系统可为深圳市灵星雨科技开发有限公司的实像素全彩控制系统等。该74HC138芯片将对该行选择信号HSEL0、HSEL1、HSEL2进行译码，从而输出行译码输出H1A、H2A......H8A，此为现有技术，在此不必赘述。As shown in Figure 1, each row decoding output is connected to acorresponding row driver 12, and therow driver 12 is used to receive row selection signals HSEL0, HSEL1, and HSEL2 output by a control system (not shown), and the control system can It is the real-pixel full-color control system of Shenzhen Lingxingyu Technology Development Co., Ltd. The 74HC138 chip will decode the row selection signals HSEL0, HSEL1, and HSEL2, thereby outputting row decoding outputs H1A, H2A...H8A, which is a prior art, and need not be repeated here.

在本实施例中该行驱动器12为现有的FDS4953芯片(请参阅图3中标号129)，但并不局限于此，也可通过三极管或MOS管组成该行驱动器。In this embodiment, therow driver 12 is an existing FDS4953 chip (refer to reference numeral 129 in FIG. 3 ), but it is not limited thereto, and the row driver can also be composed of transistors or MOS transistors.

如图3所示，每个FDS4953芯片可控制两个行译码输出到对应的两个行驱动器12的输出端。该FDS4953芯片相当于开关，控制工作电压VCC(如5伏特或3伏特等)加载在对应行FDS4953的输出端121、122......128，从而给连接在该输出端121、122......128上的对应行LED的正极提供加载的驱动电压，也即从各输出端121、122......128输出行信号H1、H2......H8，具体输出情况请参阅下表以及图12。As shown in FIG. 3 , each FDS4953 chip can control two row decoding outputs to the output terminals of the corresponding tworow drivers 12 . The FDS4953 chip is equivalent to a switch, which controls the operating voltage VCC (such as 5 volts or 3 volts, etc.) The anodes of the corresponding rows of LEDs on .....128 provide the loaded driving voltage, that is, the row signals H1, H2...H8 are output from eachoutput terminal 121, 122...128, specifically See the table below and Figure 12 for the output.

    HSEL2 HSEL2     HSEL1 HSEL1     HSEL0 HSEL0    H1～H8的状态 Status of H1～H8     0 0     0 0     0 0    H1为高(1)，其余为低(0) H1 is high (1), the rest are low (0)     0 0     0 0     1 1    H2为高(1)，其余为低(0) H2 is high (1), the rest are low (0)     0 0     1 1     0 0    H3为高(1)，其余为低(0) H3 is high (1), the rest are low (0)     0 0     1 1     1 1    H4为高(1)，其余为低(0) H4 is high (1), the rest are low (0)     1 1     0 0     0 0    H5为高(1)，其余为低(0) H5 is high (1), the rest are low (0)

    1 1     0 0     1 1  H6为高(1)，其余为低(0) H6 is high (1), the rest are low (0)     1 1     1 1     0 0  H7为高(1)，其余为低(0) H7 is high (1), the rest are low (0)     1 1     1 1     1 1  H8为高(1)，其余为低(0) H8 is high (1), the rest are low (0)

如图1所示，连接在该行驱动器12的输出端121、122......12n上的LED的负极对应连接在列驱动器14上，该列驱动器14与该各行驱动器12共同来控制LED发光，来显示图象、文字等信息。具体来讲，该列驱动器14主要用来接收该控制系统输出的时钟信号Clk、加载信号Load、使能信号En和数据信号Data，来驱动已经被对应行驱动器12加载的一行LED，并控制其发光，以显示预期的画面。在本实施例中，该列驱动器14为MBI5026芯片，也可为北京中庆微数字设备开发有限公司的ZQ9722、ZQ9729芯片，在LED列数目较多的情况下，可级连该芯片，从而可控制较多列的LED，来控制LED的发光，并控制其发光时间的长短，从而实现更高灰度等级，此为现有技术，在此不必赘述。当然，该列驱动器14也并不局限于此。As shown in Fig. 1, the cathodes of the LEDs connected to theoutput terminals 121, 122...12n of therow driver 12 are correspondingly connected to thecolumn driver 14, and thecolumn driver 14 is jointly controlled by therow drivers 12 LEDs emit light to display information such as images and text. Specifically, thecolumn driver 14 is mainly used to receive the clock signal Clk, the load signal Load, the enable signal En and the data signal Data output by the control system to drive a row of LEDs that have been loaded by the correspondingrow driver 12, and control its Glows to show the expected screen. In this embodiment, therow driver 14 is an MBI5026 chip, or it can be the ZQ9722 and ZQ9729 chips of Beijing Zhongqing Micro Digital Equipment Development Co., Ltd. In the case of a large number of LED rows, the chips can be cascaded, so that Controlling more columns of LEDs to control the light emission of the LEDs and the length of the light emission time to achieve a higher gray scale is a prior art, so it is not necessary to repeat it here. Of course, thecolumn driver 14 is not limited thereto.

此外，在图中未画出级联电路，该级联电路一般为74HC245芯片，也并不局限于此，如74HCT245、74ACT245、74LS245。该级联电路主要用于分配各种数据、信号来控制该列驱动器14与该各行驱动器12，此为现有技术，在此不必赘述。In addition, the cascade circuit is not shown in the figure, and the cascade circuit is generally a 74HC245 chip, and is not limited thereto, such as 74HCT245, 74ACT245, and 74LS245. The cascade circuit is mainly used for distributing various data and signals to control thecolumn driver 14 and therow drivers 12 , which is a prior art and need not be repeated here.

使用时，该译码器11依次让行驱动器12的输出端121、122......12n加载。当每一行LED的正极被加载后，对应的列驱动器将控制该行LED中那些LED发光，那些不发光，通过该逐行扫描的方式来显示预定的图象、文字等信息。因此，该若干行LED在扫描过程中是依次被点亮。需要注意的是，所述点亮是指某一行LED对应的行驱动器12的输出端被加载同时被列驱动器14控制。In use, thedecoder 11 loads theoutput terminals 121 , 122 . . . 12n of therow driver 12 in sequence. When the anode of each row of LEDs is loaded, the corresponding column driver will control which LEDs in the row of LEDs to emit light, and which LEDs do not emit light, and display predetermined images, texts and other information through the progressive scanning method. Therefore, the rows of LEDs are turned on sequentially during the scanning process. It should be noted that the lighting up means that the output terminal of therow driver 12 corresponding to a certain row of LEDs is loaded and controlled by thecolumn driver 14 at the same time.

在该第一实施例中，如图1所示，该放电装置16A包括分别与对应行驱动器12的输出端121、122......12n连接的若干第一放电电路161。In the first embodiment, as shown in FIG. 1 , the discharge device 16A includes a plurality offirst discharge circuits 161 respectively connected to theoutput terminals 121 , 122 . . . 12n of thecorresponding row drivers 12 .

如图1和图3所示，该第一放电电路161包括第一电阻1611，该第一电阻1611一端连接在对应的行驱动器12的输出端，另一端接地。因此，当某一行(如k行)LED被点亮时，其前一行LED(如k-1行，也就是相邻上一次被点亮的一行LED)对应的行驱动器12的输出端上的加载被关闭(或这该行驱动器12的输出端的行信号关闭)。但是由于该行驱动器12本身节电容的原因，从而在k-1行LED上的加载被关掉后，在k-1行LED对应的行驱动器12的输出端有一些电荷。由于k-1行LED对应的行驱动器12的输出端连接有该第一电阻1611，而且该第一电阻1611与地直接连接，从而可迅速将该k-1行LED对应的行驱动器12的输出端因节电容产生的电荷很快被泄放(以下详细说明)，因此当k行LED被点亮时，避免了k-1行LED产生隐亮的弊端，从而提高LED显示屏的显示效果。As shown in FIG. 1 and FIG. 3 , thefirst discharge circuit 161 includes afirst resistor 1611 , one end of thefirst resistor 1611 is connected to the output end of thecorresponding row driver 12 , and the other end of thefirst resistor 1611 is grounded. Therefore, when a certain row (such as row k) of LEDs is lit, the output terminal of therow driver 12 corresponding to its previous row of LEDs (such as row k-1, which is adjacent to the row of LEDs that were lit last time) The load is turned off (or the row signal at the output of therow driver 12 is turned off). However, due to the node capacitance of therow driver 12 itself, after the load on the LEDs in row k-1 is turned off, there is some charge at the output end of therow driver 12 corresponding to the LEDs in row k-1. Since the output terminal of therow driver 12 corresponding to the k-1 rows of LEDs is connected to thefirst resistor 1611, and thefirst resistor 1611 is directly connected to the ground, the output of therow driver 12 corresponding to the k-1 row of LEDs can be quickly The charge generated by the terminal capacitor is quickly discharged (detailed below), so when the k row of LEDs is lit, it avoids the disadvantage of the k-1 row of LEDs being dimly lit, thereby improving the display effect of the LED display.

由于当k行LED被点亮过程中，一般是k行LED对应的行驱动器12的驱动输出端121先加载，然后列驱动器14才开始驱动对应列的LED。而且在该加载和列驱动开始之间的时间间隔比较短。如图4所示，该第一电阻1611的放电时间Th要比该时间间隔小。其中该Th表示通过该第一电阻1611泄放该电荷，从而使得该行驱动器12的输出端的电压从Vh(也即加载电压Vcc)降到LED临界驱动最小电压Vled(Vled是指该各色LED的最小临界启动电压中最小的一个，以下详细说明)所用的时间。通过调节第一电阻1611的电阻值从而可容易让该Th小于该时间间隔。Because when the k rows of LEDs are turned on, generally the drivingoutput terminal 121 of therow driver 12 corresponding to the k rows of LEDs is loaded first, and then thecolumn driver 14 starts to drive the corresponding row of LEDs. Also the time interval between this loading and the start of the column drive is relatively short. As shown in FIG. 4 , the discharge time Th of thefirst resistor 1611 is shorter than the time interval. Wherein, Th means that the charge is discharged through thefirst resistor 1611, so that the voltage at the output terminal of therow driver 12 drops from Vh (that is, the loading voltage Vcc) to the LED critical driving minimum voltage Vled (Vled refers to the LED of each color. The smallest one of the minimum critical start-up voltages, detailed below). By adjusting the resistance value of thefirst resistor 1611 , it is easy to make the Th smaller than the time interval.

尽管第一实施例中的放电装置16A可达到较好的消除前行隐亮的效果，但其存在一定缺陷：由于增加第一电阻1611，从而增加显示系统的功耗。如图5所示，另外，当k行LED中的一个LED(图5中标号为131)因其他因素而被击穿而反向导通时，从而导致该反向导通的LED所在列(如p列)的LED容易产生列隐亮。具体来讲，当k+1行LED对应的行驱动器12的输出端被加载后，此时k行LED对应的行驱动器12的输出端的加载被关闭，如果该列驱动器14得到的信号本来不让处于k+1行和p列的LED(图5中标号为132)发光，但是由于标号为131的LED反向导通，并经过该第一电阻1611而形成电流回路(参阅图5中虚线以及电流流向的箭头)，从而使得标号为132的LED发光，造成列隐亮的产生。该列隐亮的产生主要由于：有反向导通的LED存在；同时加载电压与反向导通LED所在行对应的行驱动器12的输出端上的电压之间的差值大于Vled。Although the discharge device 16A in the first embodiment can achieve a better effect of eliminating the darkening in front, it has certain defects: the power consumption of the display system is increased due to the addition of thefirst resistor 1611 . As shown in Fig. 5, in addition, when an LED (labeled 131 in Fig. 5) in row k of LEDs is broken down due to other factors and conducts in reverse, the column (such as p column) LEDs are prone to column hidden bright. Specifically, when the output terminal of therow driver 12 corresponding to the k+1 row of LEDs is loaded, the loading of the output terminal of therow driver 12 corresponding to the k row of LEDs is turned off. If the signal obtained by thecolumn driver 14 does not allow The LED (labeled 132 in FIG. 5 ) in the k+1 row and p column emits light, but because the LED labeled 131 conducts in reverse, and forms a current loop through the first resistor 1611 (see dotted line and current in FIG. 5 flow direction), so that the LED labeled 132 emits light, resulting in the generation of column brightness. The reason why the row is dimly lit is mainly due to: there is a reverse conduction LED; at the same time, the difference between the applied voltage and the voltage on the output terminal of therow driver 12 corresponding to the row where the reverse conduction LED is located is greater than Vled.

图6和图7所示本发明第二实施例，其中第二实施例与第一实施例不同在于放电装置，因此省略其他元件，第二实施例中与第一实施例中相同的元件使用相同的标号，在此不必赘述。Figure 6 and Figure 7 show the second embodiment of the present invention, wherein the second embodiment is different from the first embodiment in the discharge device, so other elements are omitted, and the same elements in the second embodiment and the first embodiment use the same labels, need not be repeated here.

如图1和图6所示，在该第二实施例中，放电装置16B包括分别与对应行驱动器12的输出端121、122......12n连接的第二放电电路(未标号)，该第二放电电路包括串联的第二电阻1612和第一稳压装置，该第二电阻1612的一端与对应行驱动器12的输出端连接，另一端与该第一稳压装置连接；该第一稳压装置的另一端接地。As shown in FIGS. 1 and 6 , in this second embodiment, thedischarge device 16B includes a second discharge circuit (not labeled) connected to theoutput terminals 121, 122...12n of thecorresponding row driver 12, respectively. , the second discharge circuit includes asecond resistor 1612 and a first voltage stabilizing device connected in series, one end of thesecond resistor 1612 is connected to the output end of thecorresponding row driver 12, and the other end is connected to the first voltage stabilizing device; The other end of a voltage stabilizing device is grounded.

在本实施例中该第一稳压装置为第一稳压二极管1613，其中该第二电阻1612的的另一端是与该第一稳压二极管1613的正极连接；该第一稳压二极管1613的负极接地。In this embodiment, the first voltage stabilizing device is a firstvoltage stabilizing diode 1613, wherein the other end of thesecond resistor 1612 is connected to the anode of the firstvoltage stabilizing diode 1613; Negative ground.

该第二放电电路的放电原理与第一放电电路161基本相同，只是此时Th的时间需要根据该第二电阻1612和第一稳压装置来确定，其他相同，在此不必赘述。因此第二放电电路同样也可以迅速将对应行驱动器12的输出端因节电容产生的电荷很快被泄放，避免了该前一行LED产生隐亮的弊端。而且由于第二放电电路中包括第一稳压二极管1613，因此当泄放完成后，该第一稳压二极管1613因其特性而在正极维持一个稳定预定电压Vp。The discharge principle of the second discharge circuit is basically the same as that of thefirst discharge circuit 161, except that the time of Th needs to be determined according to thesecond resistor 1612 and the first voltage stabilizing device. Therefore, the second discharge circuit can also quickly discharge the charge generated by the junction capacitor at the output end of thecorresponding row driver 12, avoiding the disadvantage of the LEDs in the previous row being dimly lit. Moreover, since the second discharge circuit includes thefirst zener diode 1613, after the discharge is completed, thefirst zener diode 1613 maintains a stable predetermined voltage Vp at the anode due to its characteristics.

如图7所示，该预定电压Vp小于该LED的最小临界启动电压Vled，并大于工作电压Vh与所述LED的最小临界启动电压Vled之差。当扫描型LED显示装置采用多色LED时，由于每种颜色(如红色、绿色、蓝色等)LED的最小临界启动电压不同，此处Vled是指该各色LED的最小临界启动电压中最小的一个。As shown in FIG. 7 , the predetermined voltage Vp is less than the minimum critical start-up voltage Vled of the LED, and greater than the difference between the operating voltage Vh and the minimum critical start-up voltage Vled of the LED. When the scanning LED display device adopts multi-color LEDs, since the minimum critical starting voltage of LEDs of each color (such as red, green, blue, etc.) is different, Vled here refers to the minimum critical starting voltage of the LEDs of each color. one.

由于该预定电压小于最小临界启动电压Vled，因此当k行LED对应的行驱动器12的输出端上的电荷泄放后，此时该行驱动器12的输出端的电压维持在预定电压Vp，该Vp不足以驱动k行LED中的任一个LED，从而可有效避免在k+1行点亮时该k行LED产生隐亮。另外，由于该预定电压大于工作电压Vcc与所述LED的最小临界启动电压Vled之差，即使有反向导通LED的存在，加载电压与反向导通LED所在行对应的行驱动器12的输出端上的电压之间的差值小于Vled，从而可有效避免列隐亮的产生，从而进一步提高LED显示屏的显示效果。Since the predetermined voltage is less than the minimum critical start-up voltage Vled, after the charge on the output terminal of therow driver 12 corresponding to the k rows of LEDs is discharged, the voltage at the output terminal of therow driver 12 is maintained at the predetermined voltage Vp, which is insufficient for Vp. Any one of the LEDs in the k rows can be driven to effectively prevent the LEDs in the k rows from being dimly lit when the k+1 rows are lit. In addition, because the predetermined voltage is greater than the difference between the operating voltage Vcc and the minimum critical start-up voltage Vled of the LED, even if there is a reverse conduction LED, the voltage applied to the output terminal of therow driver 12 corresponding to the row where the reverse conduction LED is located The difference between the voltages is smaller than Vled, which can effectively avoid the occurrence of LED display brightness, thereby further improving the display effect of the LED display.

图8至图13所示本发明第三实施例，其中第三实施例与第一、第二实施例不同在于放电装置，第三实施例中与前两实施例中相同的元件使用相同的标号，在此不必赘述。Figures 8 to 13 show the third embodiment of the present invention, wherein the third embodiment is different from the first and second embodiments in the discharge device, and the same components in the third embodiment and the first two embodiments use the same symbols , need not be repeated here.

在本实施例中，该放电装置16C接收该行选择信号HSEL的变化，并根据该行选择信号的变化，确保某一行LED被点亮时或之前，泄放连接前一行LED正极的行驱动器12的输出端上的电荷，以消除该前一行LED在该某一行LED点亮时产生隐亮，以下详细说明。In this embodiment, thedischarge device 16C receives the change of the row selection signal HSEL, and according to the change of the row selection signal, ensures that when or before a certain row of LEDs is lit, therow driver 12 connected to the anode of the previous row of LEDs is discharged. The charge on the output terminal of the LED is used to eliminate the hidden light generated by the previous row of LEDs when the certain row of LEDs is turned on, which will be described in detail below.

作为优选方式，放电装置16C是接收所述行选择信号中频率最高的行选择信号HSEL0的上升和下降的变化。在本实施例中，该放电装置16C包括放电控制电路15和第三放电电路163。其中该放电控制电路163接收该行选择信号中频率最高的行选择信号HSEL0的上升和下降的变化，输出放电控制信号CLOUTX，来控制该第三放电电路163放电，以下详细说明。As a preferred manner, thedischarge device 16C receives the rising and falling changes of the row selection signal HSEL0 with the highest frequency among the row selection signals. In this embodiment, thedischarge device 16C includes adischarge control circuit 15 and athird discharge circuit 163 . Thedischarge control circuit 163 receives the rising and falling changes of the row selection signal HSEL0 with the highest frequency among the row selection signals, and outputs the discharge control signal CLOUTX to control thethird discharge circuit 163 to discharge, which will be described in detail below.

在本实施例中，该放电控制电路15包括稳态触发器151、或门电路152和计时电路。其中该稳态触发器151在本实施例中为现有的单稳态触发器74HC123芯片，当然并不局限于此，如双稳态触发器等或74HCT123、74ACT123、74LS2123。该稳态触发器151主要用于检测该行选择信号HSEL的变化。在本实施例中，该稳态触发器151的第2脚、第9脚连接到HSEL0，也即频率最高的行选择信号HSEL0。In this embodiment, thedischarge control circuit 15 includes a steady-state trigger 151 , an OR gate circuit 152 and a timing circuit. The flip-flop 151 in this embodiment is the existing monostable flip-flop 74HC123 chip, of course it is not limited to this, such as bistable flip-flops or 74HCT123, 74ACT123, 74LS2123. The steady-state flip-flop 151 is mainly used to detect the change of the row selection signal HSEL. In this embodiment, the second pin and the ninth pin of the steady-state flip-flop 151 are connected to HSEL0, that is, the row selection signal HSEL0 with the highest frequency.

如图9至图12所示，当HSEL0由低变高时，从稳态触发器151的第5脚产生一个高电平脉冲CLUP；当HSEL0由高变低时，从稳态触发器151的第13脚产生一个高电平脉冲CLDOWN。从该稳态触发器151的第5脚和第13脚出来的高电平脉冲CLUP、CLDOWN，输送到该或门电路152，进行或运算，以下详细说明。As shown in Figures 9 to 12, when HSEL0 changes from low to high, a high-level pulse CLUP is generated from the fifth pin of the steady-state flip-flop 151; The 13th foot produces a high level pulse CLDOWN. The high-level pulses CLUP and CLDOWN from the fifth pin and the thirteenth pin of the steady-state flip-flop 151 are sent to the OR gate circuit 152 for OR operation, which will be described in detail below.

该或门电路152在本实施例中为现有的74HC32芯片，其第13脚和第12脚分别用来接收该稳态触发器151的第5脚和第13脚出来的高电平脉冲CLUP、CLDOWN，然后进行或运算，将运算后叠加的高电平脉冲CLOUTX，作为放电控制信号，通过第11脚传递到第三放电电路，控制其放电，下面将详细说明。当然，该或门电路152并不局限该74HC32芯片，也可为其他实现或运算的电路来实现。The OR gate circuit 152 is an existing 74HC32 chip in this embodiment, and its 13th and 12th pins are respectively used to receive the high-level pulse CLUP from the 5th pin and the 13th pin of the steady-state trigger 151 , CLDOWN, and then perform an OR operation, and use the superimposed high-level pulse CLOUTX after the operation as a discharge control signal, and transmit it to the third discharge circuit through the 11th pin to control its discharge, which will be described in detail below. Of course, the OR gate circuit 152 is not limited to the 74HC32 chip, and can also be realized by other circuits for realization or operation.

如图9所示，为了控制该第三放电电路163放电的时间，该放电控制电路15配设有计时电路。在本实施例中，该计时电路包括第三电阻1614和电容C1、C2，该第三电阻1614的一端与工作电压连接，另一端分别与所述稳态触发器15的第15脚、第7脚，同时该另一端还与和电容C1、C2连接，该电容C1、C2的另一端接地。在实施例中，可以通过调节第三电阻1614的阻值和电容C1、C2的容值来控制放电时间。具体来讲，放电时间Tcloutx＝0.64×Cx×Rx(其中Tcloutx为放电时间；Cx为电容C1、C2的容值；Rx为第三电阻1614的阻值)。As shown in FIG. 9 , in order to control the discharge time of thethird discharge circuit 163 , thedischarge control circuit 15 is equipped with a timing circuit. In this embodiment, the timing circuit includes a third resistor 1614 and capacitors C1 and C2. One end of the third resistor 1614 is connected to the operating voltage, and the other end is connected to the 15th pin and the 7th pin of the steady-state trigger 15 respectively. pin, and at the same time, the other end is also connected with capacitors C1 and C2, and the other ends of the capacitors C1 and C2 are grounded. In an embodiment, the discharge time can be controlled by adjusting the resistance of the third resistor 1614 and the capacitance of the capacitors C1 and C2. Specifically, the discharge time Tcloutx=0.64×Cx×Rx (where Tcloutx is the discharge time; Cx is the capacitance of the capacitors C1 and C2 ; Rx is the resistance of the third resistor 1614 ).

通过调整Cx和Rx，使得Tcloutx大于行驱动器12的输出端电压下降到Vled的时间Th，从而确保在Tcloutx时间内，将k行LED正极上的电压降到Vled或以下，避免当k+1行点亮时，也即列驱动器14的对应列打开时，k行LED发出隐亮，以下详细说明。其中该Th的值可通过以下公式计算：By adjusting Cx and Rx, Tcloutx is greater than the time Th when the voltage at the output terminal of therow driver 12 drops to Vled, so as to ensure that the voltage on the positive electrode of the k row of LEDs is dropped to Vled or below within the time of Tcloutx, avoiding when row k+1 When it is turned on, that is, when the corresponding column of thecolumn driver 14 is turned on, the k-row LEDs are dimly lit, which will be described in detail below. Wherein the value of this Th can be calculated by the following formula:

Th≈(2×(Vh-Vled)×Cp×R)/(Vh+Vled)Th≈(2×(Vh-Vled)×Cp×R)/(Vh+Vled)

如图8和图13所示，在该公式中：Vh为行驱动器12的输出端加载时的电压；如前所述，Vled是指该各色LED的最小临界启动电压中最小的一个；Cp为行驱动器12的节电容；R为第三电阻1614的电阻值。As shown in Fig. 8 and Fig. 13, in this formula: Vh is the voltage when the output terminal ofrow driver 12 is loaded; As mentioned above, Vled refers to the smallest one in the minimum critical start-up voltage of this various color LED; Cp is The node capacitance of therow driver 12; R is the resistance value of the third resistor 1614.

如图11所示，所有第三放电电路163的构造相同，以下仅对其中一个进行详细说明。该第三放电电路163是连接在对应的行驱动器12的输出端，用于释放电荷。图11中最上方的第三放电电路163包括三极管Q1和第四电阻1615，其中该三极管Q1的基极a与该或门电路152的第11脚连接，来获取高电平脉冲信号CLOUTX；该三极管Q1的发射极e接地；该三极管Q1的集电极b通过第四电阻1615连接至对应行驱动器12的输出端。As shown in FIG. 11 , allthird discharge circuits 163 have the same structure, and only one of them will be described in detail below. Thethird discharge circuit 163 is connected to the output end of thecorresponding row driver 12 for discharging the charge. The uppermostthird discharge circuit 163 in FIG. 11 includes a triode Q1 and afourth resistor 1615, wherein the base a of the triode Q1 is connected to the 11th pin of the OR circuit 152 to obtain a high-level pulse signal CLOUTX; The emitter e of the transistor Q1 is grounded; the collector b of the transistor Q1 is connected to the output end of thecorresponding row driver 12 through thefourth resistor 1615 .

通过该构造，当a基极接收到该或门电路152的第11脚连接传来的高电平脉冲信号CLOUTX(也即放电控制信号)时，所有三极管Q1、Q2......Q8将导通，所有的行驱动器12的输出端处于放电状态，从而可释放未被加载的输出端上(也即LED正极上)由于节电容产生的多余电荷，也包括对前行LED对应的驱动器12的输出端放电。Through this structure, when a base receives the high-level pulse signal CLOUTX (that is, the discharge control signal) transmitted from the 11th pin of the OR circuit 152, all transistors Q1, Q2...Q8 will be turned on, and the output terminals of all therow drivers 12 are in the discharge state, so that the excess charge generated by the junction capacitance on the unloaded output terminals (that is, on the positive pole of the LED) can be released, including the corresponding driver for the previous row of LEDs The output terminal of 12 discharges.

由于被加载的行LED的正极有工作电压Vcc，当列驱动器14的对应列打开时，该行LED上预定发光的LED将正常发光，而前行LED对应的行驱动器12的输出端由于被放电而不会出现隐亮，从而大大提高画面质量。Since the anode of the loaded row LED has an operating voltage Vcc, when the corresponding column of thecolumn driver 14 is turned on, the LEDs scheduled to emit light on the row of LEDs will normally emit light, while the output terminal of therow driver 12 corresponding to the previous row of LEDs is discharged. And there will be no hidden brightness, thus greatly improving the picture quality.

需要注意的是，该第四电阻1615是可选择的，在没有该第四电阻1615时，仅通过三极管Q1、Q2......Q8同样可实现以上放电功能。增加该第四电阻1615可控制放电速度，通过以上Th的计算公式可知。It should be noted that thefourth resistor 1615 is optional, and without thefourth resistor 1615, the above discharge function can also be realized only through the transistors Q1, Q2...Q8. Adding thefourth resistor 1615 can control the discharge rate, which can be known from the calculation formula of Th above.

如图8至图13所示，现以第k行LED为例说明通过放电装置16C来到消除前一行LED隐亮的原理：当译码器11通过译码产生的行译码输出，来关掉第k行LED对应的行驱动器12，由于节电容的原因，在第k行LED对应的行驱动器12的输出端由于节电容原因而会产生有虚高电压(如图13所示的Vh)。由于在关掉k行LED对应的行驱动器12的同时，该放电控制电路15也检测到行选择信号的变化，也即检测到频率最高的行选择信号HSEL0上升或下降的变化，从而产生高电平脉冲CLUP、CLDOWN。该高电平脉冲CLUP、CLDOWN通过或门电路152产生由高电平脉冲CLUP、CLDOWN叠加产生的高电平脉冲CLOUTX，作为放电控制信号。该高电平脉冲CLOUTX将传递到三极管Q1、Q2......Q8的基极a，从而让三极管Q1、Q2......Q8导通，让第k行LED对应的行驱动器12的输出端上的电荷释放。通过调节该Cx和Rx，使得Tcloutx大于k行LED对应的行驱动器12的输出端电压下降到Vled的时间Th，从而使得三极管Q1、Q2......Q8的放电时间大于将虚高电压Vh放到Vled的时间。因此，当k+1行点亮时，k行LED的正极上没有电荷，或小于让k行LED点亮的临界电荷量，从而避免k行LED隐亮。As shown in Figures 8 to 13, now take the k-th row of LEDs as an example to illustrate the principle of eliminating the hidden lighting of the previous row of LEDs through thedischarge device 16C: when thedecoder 11 generates row decoding output through decoding, it turns off If therow driver 12 corresponding to the k-th row of LEDs is removed, due to the junction capacitance, the output terminal of therow driver 12 corresponding to the k-th row of LEDs will generate a virtual high voltage (Vh as shown in FIG. 13 ) due to the junction capacitance. . Since thedischarge control circuit 15 also detects the change of the row selection signal while turning off therow driver 12 corresponding to the k row of LEDs, that is, the rise or fall of the row selection signal HSEL0 with the highest frequency is detected, thereby generating a high voltage Flat pulse CLUP, CLDOWN. The high-level pulses CLUP and CLDOWN pass through the OR circuit 152 to generate a high-level pulse CLOUTX generated by superimposing the high-level pulses CLUP and CLDOWN as a discharge control signal. The high-level pulse CLOUTX will be transmitted to the base a of the transistors Q1, Q2...Q8, so that the transistors Q1, Q2...Q8 are turned on, and the row driver corresponding to the k-th row of LEDs The charge on the output of 12 is released. By adjusting the Cx and Rx, Tcloutx is greater than the time Th for the output terminal voltage of therow driver 12 corresponding to the k rows of LEDs to drop to Vled, so that the discharge time of the transistors Q1, Q2...Q8 is longer than the virtual high voltage The time when Vh is put into Vled. Therefore, when row k+1 is lit, there is no charge on the anode of the LEDs of row k, or less than the critical charge amount for the LEDs of row k to be lit, thereby avoiding the LEDs of row k from being dimly lit.

因此，通过该放电装置16C，本发明扫描型LED显示装置也可完全消除前行隐亮的干扰，提供显示画面显示质量。但是本发明第三实施例与第一实施也存在同样的缺陷，在此不必赘述。Therefore, by using thedischarge device 16C, the scanning LED display device of the present invention can also completely eliminate the interference of the forward-moving hidden light, and improve the display quality of the display screen. However, the third embodiment of the present invention also has the same defects as the first embodiment, which need not be repeated here.

图14至图18所示本发明第四实施例，其中第四实施例与第三实施例相似，但提供另一种第三放电电路，第四实施例中与前三实施例中相同的元件使用相同的标号，在此不必赘述。Figure 14 to Figure 18 show the fourth embodiment of the present invention, wherein the fourth embodiment is similar to the third embodiment, but provides another third discharge circuit, the same elements in the fourth embodiment and the first three embodiments The same reference numerals are used and need not be repeated here.

在本实施例中，放电装置16D包括该另一种第三放电电路163’和放电控制电路15，其中该放电控制电路15与第三实施例相同，在此不必赘述。In this embodiment, thedischarge device 16D includes the other third discharge circuit 163' and adischarge control circuit 15, wherein thedischarge control circuit 15 is the same as that of the third embodiment, which need not be repeated here.

本实施例中的第三放电电路163’包括放电选择装置和若干第二稳压装置，该第二稳压装置与第二实施例中的第一稳压装置相同，为第二稳压二极管18，其工作原理与第一稳压二极管1613相同，在此不必赘述。The third discharge circuit 163' in this embodiment includes a discharge selection device and several second voltage stabilizing devices, the second voltage stabilizing device is the same as the first voltage stabilizing device in the second embodiment, which is a secondvoltage stabilizing diode 18 , the working principle of which is the same as that of thefirst Zener diode 1613, which need not be repeated here.

如图16所示，该放电选择装置为138译码器，通过芯片74HC156(图16中标号为17)来实现，其工作原理为：该芯片74HC156第13脚、3脚和1脚分别接收行选择信号HSEL0、HSEL1、HSEL2，然后对其进行译码，从第4脚、第5脚......第12脚产生行译码输出端，每个行译码输出端通过第二稳压二极管18与对应行驱动器12的输出端连接，其中芯片74HC156的行译码输出端与所述74HC138芯片的行译码输出端错开一位，也即当所述74HC138芯片的行译码输出端选种k行LED对应的行驱动器12的输出端时，该芯片74HC156的行译码输出端则选种前k-1行LED对应的行驱动器12的输出端，以便于实现对前行LED对应的行驱动器12的输出端上的电荷进行放电，以下详细说明。其中Th的长短须根据该放电选择装置本身性能来确定。As shown in Figure 16, the discharge selection device is a 138 decoder, which is realized by the chip 74HC156 (labeled 17 in Figure 16), and its working principle is: the 13th pin, 3rd pin and 1st pin of the chip 74HC156 respectively receive row Select the signal HSEL0, HSEL1, HSEL2, and then decode it, generate a line decoding output terminal from the 4th pin, 5th pin...12th pin, and each row decoding output terminal passes through the second stable Thevoltage diode 18 is connected to the output end of thecorresponding row driver 12, wherein the row decoding output end of the chip 74HC156 is staggered by one bit from the row decoding output end of the 74HC138 chip, that is, when the row decoding output end of the 74HC138 chip When selecting the output end of therow driver 12 corresponding to k rows of LEDs, the row decoding output end of the chip 74HC156 selects the output end of therow driver 12 corresponding to the previous k-1 rows of LEDs, so as to realize the corresponding The charge on the output terminal of therow driver 12 is discharged, which will be described in detail below. The length of Th must be determined according to the performance of the discharge selection device itself.

该放电控制电路15产生的放电控制信号CLOUTX通过第2脚和14脚传给芯片74HC156，作为其使能信号，从而可控制该芯片74HC156进行放电。The discharge control signal CLOUTX generated by thedischarge control circuit 15 is transmitted to the chip 74HC156 throughpins 2 and 14 as its enabling signal, thereby controlling the chip 74HC156 to discharge.

同样以第k行LED为例说明通过放电装置16D来到消除前一行LED隐亮的原理：当所述74HC138芯片通过对行选择信号HSEL0、HSEL1、HSEL2译码产生的行译码输出，加载k+1行LED对应的行驱动器12的输出端，并关掉第k行LED对应的行驱动器12的输出端上的加载，由于节电容的原因，在第k行LED对应的行驱动器12的输出端由于节电容原因而会产生有虚高电压。同时该芯片74HC156也对行选择信号HSEL0、HSEL1、HSEL2译码产生的行译码输出，来选择k行LED对应的行驱动器12的输出端；而且在关掉k行LED对应的行驱动器12的同时，如第三实施例所述，该放电控制电路15产生CLOUTX作为放电控制信号，来控制该k行LED对应的行驱动器12的输出端的电荷通过该芯片74HC156的对应行译码输出端，从第8脚引入接地。因此，当k+1行点亮时，k行LED的正极上没有电荷，或小于让k行LED点亮的临界电荷量，从而避免k行LED隐亮。Also take the kth row of LEDs as an example to illustrate the principle of eliminating the hidden brightness of the previous row of LEDs through thedischarge device 16D: when the 74HC138 chip generates the row decoding output by decoding the row selection signals HSEL0, HSEL1, and HSEL2, load k The output terminal of therow driver 12 corresponding to the +1 row of LEDs, and turn off the loading on the output terminal of therow driver 12 corresponding to the kth row of LEDs. Due to the reason of the section capacitor, the output of therow driver 12 corresponding to the kth row of LEDs There will be a virtual high voltage at the terminal due to the junction capacitance. Simultaneously, this chip 74HC156 also outputs the row decoding output generated by decoding the row selection signals HSEL0, HSEL1, and HSEL2 to select the output terminal of therow driver 12 corresponding to the k rows of LEDs; At the same time, as described in the third embodiment, thedischarge control circuit 15 generates CLOUTX as a discharge control signal to control the charge at the output terminal of therow driver 12 corresponding to the k rows of LEDs to pass through the corresponding row decoding output terminal of the chip 74HC156, fromPin 8 is connected to ground. Therefore, when row k+1 is lit, there is no charge on the anode of the LEDs of row k, or less than the critical charge amount for the LEDs of row k to be lit, thereby avoiding the LEDs of row k from being dimly lit.

为了维持k行LED对应的行驱动器12的输出端在泄放后维持一定电压，来消除因损坏LED反向导通而引起的列隐亮，与该k行LED对应的行驱动器12的输出端连接的第二稳压二极管18，该第二稳压二极管18与第二实施例中第一稳压二极管18的原理相同(参阅图18)，在此不必赘述。In order to maintain the output terminal of therow driver 12 corresponding to the k row of LEDs to maintain a certain voltage after discharge, to eliminate the column hidden light caused by the reverse conduction of the damaged LED, it is connected to the output terminal of therow driver 12 corresponding to the k row of LEDs Thesecond Zener diode 18, the principle of thesecond Zener diode 18 is the same as that of thefirst Zener diode 18 in the second embodiment (refer to FIG. 18 ), which need not be repeated here.

如图14和图15所示，为了确保进一步有效消除列隐亮的问题，该放电控制信号CLOUTX也作为74HC138(图15中标号为11’)的使能信号，从而将行输出行信号延迟Tcloutx后再加载(如图17和图18)，也就是在该使能信号处于使能状态时禁止该行译码输出，从而进一步缩小加载的驱动器12的输出端与反向导通LED所在行对应的驱动器12的输出端之间的压差，从而进一步抑制列隐亮的产生，提高显示质量。而且该方法也可用于以上第三个实施例。As shown in Figure 14 and Figure 15, in order to further effectively eliminate the problem of column brightness, the discharge control signal CLOUTX is also used as the enable signal of 74HC138 (labeled 11' in Figure 15), thereby delaying the row output row signal by Tcloutx Reloading (as shown in Figure 17 and Figure 18), that is, when the enable signal is in the enabled state, the row's decoding output is prohibited, thereby further reducing the output terminal of the loadeddriver 12 and the row corresponding to the reverse conduction LED. The voltage difference between the output terminals of thedriver 12 can further suppress the occurrence of column brightness and improve the display quality. And this method can also be used in the above third embodiment.

根据以上第三、第四实施的扫描型LED显示装置10的构造，本发明消除扫描型LED显示装置10前行隐亮的方法主要包括以下几个步骤：According to the structure of the scanningLED display device 10 in the third and fourth implementations above, the method for eliminating the hidden brightness of the scanningLED display device 10 in the present invention mainly includes the following steps:

1)检测扫描型LED显示装置的行选择信号HSEL的变化；1) Detecting changes in the row selection signal HSEL of the scanning LED display device;

2)当检测到该扫描型LED显示装置的行选择信号HSEL的变化，产生一个放电控制信号CLOUTX，使得某一行LED被点亮时或之前，泄放连接前一行LED正极的行驱动器12的输出端上的电荷，以消除该前一行LED在该某一行LED点亮时产生隐亮。2) When the change of the row selection signal HSEL of the scanning LED display device is detected, a discharge control signal CLOUTX is generated, so that when or before a certain row of LEDs is lit, the output of therow driver 12 connected to the anode of the previous row of LEDs is discharged The electric charge on the end, to eliminate the hidden light of the previous row of LEDs when the LEDs of a certain row are lit.

作为优选方式，该行选择信号HSEL的变化为频率最高的行选择信号HSEL0的上升和下降变化。As a preferred manner, the change of the row selection signal HSEL is the rising and falling change of the row selection signal HSEL0 with the highest frequency.

另外，在步骤2中，该放电控制信号CLOUTX是这样产生的：当检测到该扫描型LED显示装置的行选择信号HSEL有变化时，产生上升脉冲CLUP和下降脉冲CLDOW，该上升脉冲CLUP和下降脉冲CLDOW通过或运算后的叠加脉冲信号作为该放电控制信号CLOUTX。In addition, instep 2, the discharge control signal CLOUTX is generated as follows: when a change is detected in the row selection signal HSEL of the scanning LED display device, a rising pulse CLUP and a falling pulse CLDOW are generated, and the rising pulse CLUP and falling pulse The superimposed pulse signal after the pulse CLDOW is ORed is used as the discharge control signal CLOUTX.

而且，步骤2)还包括控制所述上升脉冲CLUP和下降脉冲CLDOW输出时间长短的步骤。Moreover, step 2) also includes the step of controlling the output time of the rising pulse CLUP and the falling pulse CLDOW.

作为优选方式，该放电控制信号CLOUTX作为行选择信号输出的使能信号，来延迟行译码输出Tcloutx长时间，也就是在该使能信号处于使能状态时禁止该行译码输出。As a preferred manner, the discharge control signal CLOUTX is used as an enable signal output by the row selection signal to delay the row decoding output Tcloutx for a long time, that is, the row decoding output is disabled when the enable signal is in an enabled state.

作为优选方式，该放电控制信号CLOUTX仅选择并控制行译码器11所选择要加载的一行LED的前一行LED对应的行驱动器12的输出端进行泄放。As a preferred manner, the discharge control signal CLOUTX only selects and controls the output terminal of therow driver 12 corresponding to the row of LEDs before the row of LEDs selected by therow decoder 11 to discharge.

作为优选方式，连接前一行LED的行驱动器12的输出端的电压在泄放后维持在预定电压，该预定电压小于所述LED的最小临界启动电压Vled，并大于工作电压Vcc(或Vh)与所述LED的最小临界启动电压Vled之差。As a preferred mode, the voltage at the output terminal of therow driver 12 connected to the previous row of LEDs is maintained at a predetermined voltage after being discharged, and the predetermined voltage is less than the minimum critical start-up voltage Vled of the LEDs, and greater than the operating voltage Vcc (or Vh) and the specified voltage. The difference between the minimum critical start-up voltage Vled of the above-mentioned LEDs.

尽管通过以上实施例对本发明进行了揭示，但是本发明的范围并不局限于此，在不偏离本发明构思的条件下，以上各元件可用所属技术领域人员了解的相似或等同元件来替换。Although the present invention has been disclosed through the above embodiments, the scope of the present invention is not limited thereto. Without departing from the concept of the present invention, the above elements can be replaced by similar or equivalent elements understood by those skilled in the art.

Claims (26)

1. scan type LED display unit, it comprises the several rows driver, row driver and several rows LED, wherein the output terminal of each line driver connects the positive pole of corresponding row LED, the output terminal of this row driver be connected this line driver on the corresponding connection of negative pole of LED, it is characterized in that: this scan type LED display unit also comprises the electric discharge device that is connected with this several rows output end of driver, make when certain LED of delegation is lighted or before, release electric charge on the output terminal of the line driver that connects previous row LED positive pole, with eliminate this previous row LED when this certain LED of delegation lights, produces conceal bright.

2. scan type LED display unit as claimed in claim 1, it is characterized in that: described electric discharge device comprises some first discharge circuits that are connected with the corresponding row output end of driver respectively, each first discharge circuit comprises first resistance, one end of this first resistance is connected with the corresponding row output end of driver, other end ground connection.

3. scan type LED display unit as claimed in claim 1, it is characterized in that: described electric discharge device comprises some second discharge circuits that are connected with the corresponding row output end of driver respectively, each second discharge circuit comprises second resistance and the stable-pressure device of series connection, this second resistance, one end connects with the output terminal of corresponding line driver, the other end is connected with this stable-pressure device, the other end ground connection of this stable-pressure device, and this stable-pressure device is kept predetermined voltage after this is released, this predetermined voltage is less than the minimum critical trigger voltage of described LED, and poor greater than the minimum critical trigger voltage that loads operating voltage and described LED.

4. scan type LED display unit as claimed in claim 3 is characterized in that: described stable-pressure device is first voltage stabilizing diode, the minus earth of this first voltage stabilizing diode, and the other end of anodal and described second resistance is connected.

5. scan type LED display unit as claimed in claim 1, it is characterized in that: also comprise line decoder, this line decoder is deciphered row selection signal, and forms several rows decoding output, and this several rows decoding output terminal connects with the input end of corresponding line driver respectively; Described electric discharge device also receives the variation of this row selection signal, and according to the variation of this row selection signal, when guaranteeing that certain LED of delegation is lighted or before, release electric charge on the output terminal of the line driver that connects previous row LED positive pole, with eliminate this previous row LED when this certain LED of delegation lights, produces conceal bright.

6. scan type LED display unit as claimed in claim 5 is characterized in that: described electric discharge device is to receive the rising of the highest row selection signal of described row selection signal medium frequency and the variation of decline.

7. scan type LED display unit as claimed in claim 6, it is characterized in that: described electric discharge device comprises charge/discharge control circuit and the 3rd discharge circuit, this charge/discharge control circuit receives the rising of the highest row selection signal of described row selection signal medium frequency and the variation of decline, the output discharge control signal is controlled the discharge of the 3rd discharge circuit.

8. scan type LED display unit as claimed in claim 7, it is characterized in that: described the 3rd discharge circuit comprises the some triodes that are connected with the corresponding row output end of driver respectively, the base stage of each triode receives described discharge control signal, grounded emitter, collector connects the corresponding row output end of driver.

9. scan type LED display unit as claimed in claim 8 is characterized in that: the collector of described triode is connected to described corresponding row output end of driver by the 4th resistance.

10. scan type LED display unit as claimed in claim 7, it is characterized in that: described the 3rd discharge circuit comprises the discharge selecting arrangement, this discharge selecting arrangement has some discharges control output end, this this discharge control output end connects with the output terminal of corresponding line driver respectively, this discharge selecting arrangement is deciphered described row selection signal, brings in the output of the line driver of the previous row LED correspondence of selecting the selected LED of delegation that will load of described line decoder and discharges; This discharge selecting arrangement receives described discharge control signal simultaneously, and the electric charge of controlling on the output terminal of this selecteed line driver discharges.

11. scan type LED display unit as claimed in claim 10, it is characterized in that: described discharge control output end is connected to the output terminal of corresponding line driver respectively by stable-pressure device, this stable-pressure device will maintain predetermined voltage to the voltage on should output end of driver after releasing, this predetermined voltage is less than the minimum critical voltage of described LED, and poor greater than the minimum critical voltage of operating voltage and described LED.

12. scan type LED display unit as claimed in claim 10 is characterized in that: described discharge selecting arrangement is 74HC156.

13. scan type LED display unit as claimed in claim 11, it is characterized in that: described stable-pressure device is second voltage stabilizing diode, the positive pole of this second voltage stabilizing diode connects with the output terminal of corresponding line driver, negative pole and corresponding discharge control output end connection.

14. as each described scan type LED display unit in the claim 7 to 13, it is characterized in that: described control signal is also controlled described line decoder as enable signal, forbids described row decoding output when this enable signal is in enabled state.

15. as each described scan type LED display unit in the claim 7 to 13, it is characterized in that: described charge/discharge control circuit comprises steady state trigger, timing circuit and OR circuit; This steady state trigger detects the rising of the highest row selection signal of described row selection signal medium frequency and descend to change, and output rising pulse and falling pulse are to this OR circuit; This OR circuit should the rising pulse and falling pulse carry out passing to described second discharge circuit as this discharge control signal behind the exclusive disjunction; This timing circuit is connected with this steady state trigger, and controls the time of this rising pulse and falling pulse respectively.

16. scan type LED display unit as claimed in claim 15 is characterized in that: described steady state trigger comprises monostalbe trigger 74HC123,74HCT123,74ACT123 or 74LS123 chip.

17. want 15 described scan type LED display units as right, it is characterized in that: described timing circuit comprises second resistance and electric capacity, one end of this second resistance is connected with operating voltage, and another point is connected the other end ground connection of this electric capacity respectively with electric capacity with described monostalbe trigger.

18. scan type LED display unit as claimed in claim 15 is characterized in that: described OR circuit comprises 74HC32,74HCT32,74ACT32 or 74LS32 chip.

19. a method of eliminating the scan type LED display unit forward moving hidden brightness is characterized in that: may further comprise the steps:

1) variation of the row selection signal of detection scan type LED display unit;

2) when the variation of the row selection signal that detects this scan type LED display unit, produce a discharge control signal, make when certain LED of delegation is lighted or before, release electric charge on the output terminal of the line driver that connects previous row LED positive pole, with eliminate this previous row LED when this certain LED of delegation lights, produces conceal bright.

20. the method for elimination scan type LED display unit forward moving hidden brightness as claimed in claim 19 is characterized in that: the rising that is changed to the highest row selection signal of frequency of described row selection signal and the variation that descends.

21. the method for elimination scan type LED display unit forward moving hidden brightness as claimed in claim 20, it is characterized in that: in step 2, this discharge control signal is to produce like this: when the row selection signal that detects this scan type LED display unit changes, produce rising pulse and falling pulse, this rising pulse and falling pulse by the superimposed pulse signal behind the exclusive disjunction as this discharge control signal.

22. the method for elimination scan type LED display unit forward moving hidden brightness as claimed in claim 21 is characterized in that: step 2) also comprise the step of control described rising pulse and falling pulse output time length.

23. method as each described elimination scan type LED display unit forward moving hidden brightness in the claim 19 to 22, it is characterized in that: described discharge control signal is forbidden described row decoding output as the enable signal of row selection signal output when this enable signal is in enabled state.

24. the method as each described elimination scan type LED display unit forward moving hidden brightness in the claim 19 to 22 is characterized in that: described discharge control signal is only selected and the output terminal of line driver of controlling the previous row LED correspondence of the selected LED of delegation that will load of line decoder is released.

25. the method as each described elimination scan type LED display unit forward moving hidden brightness in the claim 19 to 22 is characterized in that: described discharge control signal is controlled the output terminal of the line driver of all row LED correspondences simultaneously and is released.

26. method as each described elimination scan type LED display unit forward moving hidden brightness in the claim 19 to 22, it is characterized in that: the voltage of the output terminal of the line driver of described connection previous row LED maintains predetermined voltage after releasing, this predetermined voltage is less than the minimum critical trigger voltage of described LED, and poor greater than the minimum critical trigger voltage of operating voltage and described LED.

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