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深圳市迈触电子有限公司产品有电容触摸屏,工控设备触摸屏、工业电容屏等;可根据客户的需求设计定制各种尺寸的电容触摸屏。 可用于工业设备、医疗器械、交通设..

电阻式触摸屏组成结构及工作原理

时间:2019-09-25点击次数:96

    触摸屏的组成结构和实现原理

菠萝彩论坛    HENDUOLCDMOKUAIDOUCAIYONGLEDIANZUSHICHUMOPING,ZHEIXIECHUMOPINGDENGXIAOYUJIANGWULIWEIZHIZHUANHUANWEIDAIBIAOX、YZUOBIAODEDIANYAZHIDECHUANGANQI。TONGCHANGYOU4XIAN、5XIAN、7XIANHE8XIANCHUMOPINGLAISHIXIAN,BENWENXIANGXIJIESHAOLESARJIEGOU、SIZHONGCHUMOPINGDEZUCHENGJIEGOUHESHIXIANYUANLI,YIJIJIANCECHUMODEFANGFA。

    DIANZUSHICHUMOPINGSHIYIZHONGCHUANGANQI,TAJIANGJUXINGQUYUZHONGCHUMODIAN(X,Y)DEWULIWEIZHIZHUANHUANWEIDAIBIAOXZUOBIAOHEYZUOBIAODEDIANYA。HENDUOLCDMOKUAIDOUCAIYONGLEDIANZUSHICHUMOPING,ZHEIZHONGPINGMUKEYIYONGSIXIAN、WUXIAN、QIXIANHUOBAXIANLAICHANSHENGPINGMUPIANZHIDIANYA,TONGSHIDUHUICHUMODIANDEDIANYA。

    GUOQU,WEILEJIANGDIANZUSHICHUMOPINGSHANGDECHUMODIANZUOBIAODURUWEIKONGZHIQI,XUYAOSHIYONGYIGEZHUANYONGDECHUMOPINGKONGZHIQIXINPIAN,HUOZHELIYONGYIGEFUZADEWAIBUKAIGUANWANGLUOLAILIANJIEWEIKONGZHIQIDEPIANSHANGMOSHUZHUANHUANQI(ADC)。XIAPUGONGSIDELH75400/01/10/11XILIEHELH7A404DENGWEIKONGZHIQIDOUDAIYOUYIGENEIHANCHUMOPINGPIANZHIDIANLUDEPIANSHANGADC,GAIADCCAIYONGLEYIZHONGZHUCIBIJINJICUNQI(SAR)LEIXINGDEZHUANHUANQI。CAIYONGZHEIXIEKONGZHIQIKEYISHIXIANZAICHUMOPINGCHUANGANQIHEWEIKONGZHIQIZHIJIANJINXINGZHIJIEJIEKOU,WUXUCPUJIERUDEQINGKUANGXIAKONGZHISUOYOUDECHUMOPINGPIANZHIDIANYA,BINGJILUQUANBUCELIANGJIEGUO。BENWENJIANGXIANGXIJIESHAOSIXIAN、WUXIAN、QIXIANHEBAXIANCHUMOPINGDEJIEGOUHESHIXIANYUANLI。

    SAR结构

    SARDESHIXIANFANGFAHENDUO,DANTADEJIBENJIEGOUHENJIANDAN,CANJIANTU1。


图1 SAR的基本结构
     该结构将模拟输入电压(VIN)保存在一个跟踪/保持器中,N位寄存器被设置为中间值(即100.。.0,其中最高位被设置为1),以执行二进制查找算法。因此,数模转换器(DAC)的输出(VDAC)为VREF的二分之一,这里VREF为ADC的参考电压。之后,再执行一个比较操作,以决定VIN小于还是大于VDAC:

    1. 如果VIN小于VDAC,比较器输出逻辑低,N位寄存器的最高位清0。
    2. 如果VIN大于VDAC,比较器输出逻辑高(或1),N位寄存器的最高位保持为1。
 
    其后,SAR的控制逻辑移动到下一位,将该位强制置为高,再执行下一次比较。SAR控制逻辑将重复上述顺序操作,直到最后一位。当转换完成时,寄存器中就得到了一个N位数据字。

    图2显示了一个4位转换过程的例子,图中Y轴和粗线表示DAC的输出电压。
2 4位转换过程

     在本例中:
    1. 第一次比较显示VIN小于VDAC,因此位[3]被置0。随后DAC被设置为0b0100并执行第二次比较。
    2. 在第二次比较中,VIN大于VDAC,因此位[2]保持为1。随后,DAC被设置为0b0110并执行第三次比较。
    3. 在第三次比较中,位[1]被置0。DAC随后被设置为0b0101,并执行最后一次比较。
    4. 在最后一次比较中,由于VIN大于VDAC,位[0]保持为1。

    触摸屏原理

菠萝彩论坛    CHUMOPINGBAOHANSHANGXIADIEHEDELIANGGETOUMINGCENG,SIXIANHEBAXIANCHUMOPINGYOULIANGCENGJUYOUXIANGTONGBIAOMIANDIANZUDETOUMINGZUXINGCAILIAOZUCHENG,WUXIANHEQIXIANCHUMOPINGYOUYIGEZUXINGCENGHEYIGEDAODIANCENGZUCHENG,TONGCHANGHAIYAOYONGYIZHONGDANXINGCAILIAOLAIJIANGLIANGCENGGEKAI。DANGCHUMOPINGBIAOMIANSHOUDAODEYALI(RUTONGGUOBIJIANHUOSHOUZHIJINXINGANYA)ZUGOUDASHI,DINGCENGYUDICENGZHIJIANHUICHANSHENGJIECHU。SUOYOUDEDIANZUSHICHUMOPINGDOUCAIYONGFENYAQIYUANLILAICHANSHENGDAIBIAOXZUOBIAOHEYZUOBIAODEDIANYA。RUTU3SUOSHI,FENYAQISHITONGGUOJIANGLIANGGEDIANZUJINXINGCHUANLIANLAISHIXIANDE。SHANGMIANDEDIANZU(R1)LIANJIEZHENGCANKAODIANYA(VREF),XIAMIANDEDIANZU(R2)JIEDI。LIANGGEDIANZULIANJIEDIANCHUDEDIANYACELIANGZHIYUXIAMIANNEIGEDIANZUDEZUZHICHENGZHENGBI。


图3 分压器通过两个电阻进行串联实现
    为了在电阻式触摸屏上的特定方向测量一个坐标,需要对一个阻性层进行偏置:将它的一边接VREF,另一边接地。同时,将未偏置的那一层连接到一个ADC的高阻抗输入端。当触摸屏上的压力足够大,使两层之间发生接触时,电阻性表面被分隔为两个电阻。它们的阻值与触摸点到偏置边缘的距离成正比。触摸点与接地边之间的电阻相当于分压器中下面的那个电阻。因此,在未偏置层上测得的电压与触摸点到接地边之间的距离成正比。

    四线触摸屏

菠萝彩论坛    SIXIANCHUMOPINGBAOHANLIANGGEZUXINGCENG。QIZHONGYICENGZAIPINGMUDEZUOYOUBIANYUANGEYOUYITIAOCHUIZHIZONGXIAN,LINGYICENGZAIPINGMUDEDIBUHEDINGBUGEYOUYITIAOSHUIPINGZONGXIAN,JIANTU4。WEILEZAIXZHOUFANGXIANGJINXINGCELIANG,JIANGZUOCEZONGXIANPIANZHIWEI0V,YOUCEZONGXIANPIANZHIWEIVREF。JIANGDINGBUHUODIBUZONGXIANLIANJIEDAOADC,DANGDINGCENGHEDICENGXIANGJIECHUSHIJIKEZUOYICICELIANG。


图4 四线触摸屏的两个阻性层
    为了在Y轴方向进行测量,将顶部总线偏置为VREF,底部总线偏置为0V。将ADC输入端接左侧总线或右侧总线,当顶层与底层相接触时即可对电压进行测量。图5显示了四线触摸屏在两层相接触时的简化模型。对于四线触摸屏,最理想的连接方法是将偏置为VREF的总线接ADC的正参考输入端,并将设置为0V的总线接ADC的负参考输入端。

    五线触摸屏

    WUXIANCHUMOPINGSHIYONGLEYIGEZUXINGCENGHEYIGEDAODIANCENG。DAODIANCENGYOUYIGECHUDIAN,TONGCHANGZAIQIYICEDEBIANYUAN。ZUXINGCENGDESIGEJIAOSHANGGEYOUYIGECHUDIAN。WEILEZAIXZHOUFANGXIANGJINXINGCELIANG,JIANGZUOSHANGJIAOHEZUOXIAJIAOPIANZHIDAOVREF,YOUSHANGJIAOHEYOUXIAJIAOJIEDI。YOUYUZUO、YOUJIAOWEITONGYIDIANYA,QIXIAOGUOYULIANJIEZUOYOUCEDEZONGXIANCHABUDUO,LEISIYUSIXIANCHUMOPINGZHONGCAIYONGDEFANGFA。

    WEILEYANYZHOUFANGXIANGJINXINGCELIANG,JIANGZUOSHANGJIAOHEYOUSHANGJIAOPIANZHIWEIVREF,ZUOXIAJIAOHEYOUXIAJIAOPIANZHIWEI0V。YOUYUSHANG、XIAJIAOFENBIEWEITONGYIDIANYA,QIXIAOGUOYULIANJIEDINGBUHEDIBUBIANYUANDEZONGXIANDAZHIXIANGTONG,LEISIYUZAISIXIANCHUMOPINGZHONGCAIYONGDEFANGFA。ZHEIZHONGCELIANGSUANFADEYOUDIANZAIYUTASHIZUOSHANGJIAOHEYOUXIAJIAODEDIANYABAOCHIBUBIAN;DANRUGUOCAIYONGZHAGEZUOBIAO,XZHOUHEYZHOUXUYAOFANXIANG。DUIYUWUXIANCHUMOPING,YOUXIUDELIANJIEFANGFASHIJIANGZUOSHANGJIAO(PIANZHIWEIVREF)JIEADCDEZHENGCANKAOSHURUDUAN,JIANGZUOXIAJIAO(PIANZHIWEI0V)JIEADCDEFUCANKAOSHURUDUAN。

    七线触摸屏

    QIXIANCHUMOPINGDESHIXIANFANGFACHULEZAIZUOSHANGJIAOHEYOUXIAJIAOGEZENGJIAYIGENXIANZHIWAI,YUWUXIANCHUMOPINGXIANGTONG。ZHIXINGPINGMUCELIANGSHI,JIANGZUOSHANGJIAODEYIGENXIANLIANDAOVREF,LINGYIGENXIANJIESAR ADCDEZHENGCANKAODUAN。TONGSHI,YOUXIAJIAODEYIGENXIANJIE0V,LINGYIGENXIANLIANJIESAR ADCDEFUCANKAODUAN。DAODIANCENGRENGYONGLAICELIANGFENYAQIDEDIANYA。

    八线触摸屏

菠萝彩论坛    CHULEZAIMEITIAOZONGXIANSHANGGEZENGJIAYIGENXIANZHIWAI,BAXIANCHUMOPINGDESHIXIANFANGFAYUSIXIANCHUMOPINGXIANGTONG。DUIYUVREFZONGXIAN,JIANGYIGENXIANYONGLAILIANJIEVREF,LINGYIGENXIANZUOWEISAR ADCDESHUMOZHUANHUANQIDEZHENGCANKAOSHURU。DUIYU0VZONGXIAN,JIANGYIGENXIANYONGLAILIANJIE0V,LINGYIGENXIANZUOWEISAR ADCDESHUMOZHUANHUANQIDEFUCANKAOSHURU。WEIPIANZHICENGSHANGDESIGENXIANZHONG,RENHEYIGENDOUKEYONGLAICELIANGFENYAQIDEDIANYA。

    检测有无接触

菠萝彩论坛    SUOYOUDECHUMOPINGDOUNENGJIANCEDAOSHIFOUYOUCHUMOFASHENG,QIFANGFASHIYONGYIGERUOSHANGLADIANZUJIANGQIZHONGYICENGSHANGLA,ERYONGYIGEQIANGXIALADIANZULAIJIANGLINGYICENGXIALA。RUGUOSHANGLACENGDECELIANGDIANYADAYUMOUGELUOJIYUZHI,JIUBIAOMINGMEIYOUCHUMO,FANZHIZEYOUCHUMO。ZHEIZHONGFANGFACUNZAIDEWENTIZAIYUCHUMOPINGSHIYIGEJUDADEDIANRONGQI,CIWAIHAIKENENGXUYAOZENGJIACHUMOPINGYINXIANDEDIANRONG,YIBIANLVCHULCDYINRUDEZAOSHENG。RUOSHANGLADIANZUYUDADIANRONGQIXIANGLIANHUISHISHANGSHENGSHIJIANBIANZHANG,KENENGDAOZHIJIANCEDAOXUJIADECHUMO。

    SIXIANHEBAXIANCHUMOPINGKEYICELIANGCHUJIECHUDIANZU,JITU5ZHONGDERTOUCH。RTOUCHYUCHUMOYALIJINSICHENGZHENGBI。YAOCELIANGCHUMOYALI,XUYAOZHIDAOCHUMOPINGZHONGYICENGHUOLIANGCENGDEDIANZU。TU6ZHONGDEGONGSHIJICHULEJISUANFANGFA。XUYAOZHUYIDESHI,RUGUOZ1DECELIANGZHIJIEJINHUODENGYU0(ZAICELIANGGUOCHENGZHONGDANGCHUMODIANKAOJINJIEDIDEXZONGXIANSHI),JISUANJIANGCHUXIANYIXIEWENTI,TONGGUOCAIYONGRUOSHANGLAFANGFAKEYIYOUXIAOGAISHANZHEIGEWENTI。


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