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[问答]

CSD或CSX(自我或相互)方法?

你好,
有没有人知道如果使用10mm覆盖玻璃的按钮,哪种方法(CSD或CSX)是更好的选择?
非常感谢

以上来自于百度翻译


     以下为原文
  Hello,

Does anyone know which method (CSD or CSX) is the better choice if you want use buttons with 10mm overlay-glass?


thank you very much

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李洪洋

2018-9-11 15:08:44
CSD或CSX都可以。
10mm覆盖玻璃不应成为选择CSD或CSX的主要原因。
你的申请还有其他要求吗?
谢谢,
赖安

以上来自于百度翻译


     以下为原文
  Either CSD or CSX is OK.
10mm overlay-glass should not be the main reason to select CSD or CSX.
Are there any other requirements in your application?
 
Thanks,
Ryan
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张玉华

2018-9-11 15:23:53
嗨,P. Kaesar,
10mm覆盖层相当厚。我建议选择CSD。请确保将传感器垫连接到设备的痕迹是短的,因此传感器的CP不是很高。
此外,我建议允许一个选项连接周围孵化模式要么屏蔽或地面。连接周围图案到屏蔽将提供高灵敏度。您可以使用这个选项,如果连接孵化模式到地面不够敏感。
顺便问一下,你的最终申请是什么?

以上来自于百度翻译


     以下为原文
  Hi P. Kaesar,
 
10mm overlay is quite thick. I would recommend to chose CSD. Please ensure the traces that connect the sensor pad to the device are short so that the Cp of the sensors is not very high.
Also, I would recommend to allow an option to connect the surrounding hatched pattern either to shield or ground. Connecting the surrounding pattern to shield will provide high sensitivity. You can use this option if connecting the hatched pattern to ground is not sensitive enough.
By the way, what is your end application?
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张建

2018-9-11 15:36:19
引用: fbele456 发表于 2018-9-11 17:41
嗨,P. Kaesar,
10mm覆盖层相当厚。我建议选择CSD。请确保将传感器垫连接到设备的痕迹是短的,因此传感器的CP不是很高。
此外,我建议允许一个选项连接周围孵化模式要么屏蔽或地面。连接周围图案到屏蔽将提供高灵敏度。您可以使用这个选项,如果连接孵化模式到地面不够敏感。

你认为CSX测量不适用于厚覆盖玻璃+气隙(0.2mm)吗?
我已经用CSD和PCB上的9个按钮(只有单层)做了一些测试,大纲max 50x55毫米。因为按钮需要尽可能大,以获得足够的信号,我没有更多的空间来添加阴影图案/屏蔽。
附加的CSD I需要连接9个连接。
到目前为止,它的工作原理是用厚玻璃,但我也有很多干扰,意味着,如果我触摸一个按钮,我也得到一些信号从其他按钮,但信号(微分数)不那么高的触摸按钮,所以它是可检测的。
现在有了CSX,我希望能获得以下优势:
-因为TX/RX和不接地/人之间的容量被测量的干扰更小。-对环境变化的干扰更少。-只需要6个连接而不是9个连接。-更少的功耗?
最后,9个按钮将在一个带有透明金属电极(ITO)的玻璃上。在背面的玻璃,我们将有一个显示器,并在上面提到的厚覆盖玻璃,包括气隙。
非常感谢

以上来自于百度翻译


     以下为原文
  do you think CSX measuring will not work with thick overlay glass + Airgap (0.2mm)?
 
I already did some test's with CSD and 9 buttons on a PCB (only single Layer), outline max 50x55mm.
Because the buttons needs to be as big as possible to get enough signal, I have no more space to add a hatched pattern/shield.
Additional with CSD I need to wire 9 connections.
 
So far it works good with thick glass, but I also have much interferences, means if I touch a button I also get some signals from other button, but the signal (diff-counts) are not such high than the touched button, so it is detectable.
 
Now with CSX I hope to get follow advantages :
- less interferences because capacity is measured between tx/rx and not to earth/human.
- less interferences regarding environment changes.
- only need 6 connections instead of 9 connections.
- less power consumption?
 
Finally the 9 buttons will be on a glass with transparent metal electrode (ITO).
On the backside from that glass we will have a Display and on the top as mentioned thick overlay-glass incl. airgap.
 
thank you very much
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张玉华

2018-9-11 15:54:21
引用: cmh11 发表于 2018-9-11 17:53
你认为CSX测量不适用于厚覆盖玻璃+气隙(0.2mm)吗?
我已经用CSD和PCB上的9个按钮(只有单层)做了一些测试,大纲max 50x55毫米。因为按钮需要尽可能大,以获得足够的信号,我没有更多的空间来添加阴影图案/屏蔽。
附加的CSD I需要连接9个连接。

CSX肯定提供更多的PIN效率,但未必会带来功耗优势。话虽如此,CSD更好地工作在非常厚的覆盖物上。10-15毫米听起来有点太高,使用CSX。
关于气隙-通常建议在按钮和覆盖层之间没有任何空气间隙。气隙趋向于从单元到单元变化,从而导致跨单元的不同灵敏度。如果有必要使用气隙,您可以调整按钮以获得最大可能的气隙,但这意味着,由于制造变化,具有较小气隙的板可能会有轻微的悬停效应。
你使用的按钮尺寸是多少,我相信一个直径为10mm的圆形按钮就足够了。如果按钮是紧密间隔的,这是在你的情况下,它预期会受到附近按钮的干扰。厚覆盖层只增加了这一点,因为场在z方向上传播得越远(如预期的那样),它在其他方向上传播得越远。
您可以尝试使用固件技术来最小化这种干扰(例如,当手指位于一个按钮的中心时,将阈值设置为高于来自附近按钮的信号)。如果用户一次触摸两个按钮,最高信号的按钮就是检测到的按钮。如果不同时触摸两个按钮,则只能使用后面的方法。
您还可以尝试更改组件设置,以驱动未使用的传感器屏蔽以获得更高的信号。
由于您的9个按钮在ITO上,我建议您不要添加额外的560欧姆串联电阻(或者使用0欧姆焊盘来允许测试),因为ITO固有地具有更高的电阻。
我有点担心显示器可能会增加按钮的噪音,最好的办法是测试它并尝试一些过滤技术(使用那些在AN92249中提到的)。如果可能的话,在显示器和按钮之间有一个屏蔽/地面阴影层会有帮助。

以上来自于百度翻译


     以下为原文
  CSX definitely gives advantage being more pin efficient but may not necessarily give power consumption advantage. Having said that, CSD works better for very thick overlays. 10-15mm sounds a little too high for using  CSX.
Regarding Airgap - it's generally recommended to not have any air-gap between buttons and overlay. Air-gap tends to vary from unit to unit leading to different sensitivities across units. If it's imperative to work with air-gap, you can tune the buttons for maximum possible airgap but that will mean that there may be slight hover effect for boards which have lesser air-gap due to manufacturing variations.
 
What is the button size you are using, a 10mm diameter round button should be sufficient I believe. If the buttons are closely spaced, which it is in your case, it is expected to have interference from nearby buttons. Thick overlay only adds to this because the farther the field spreads in z direction (as intended), the farther it will spread in other directions.
You can try using firmware techniques to minimize this interference (for example, set the thresholds higher than the signal from nearby buttons when finger is on center of one button). Ensure if user touches two buttons at a time, the button with the highest signal is the one that is detected ON. The later method can only be used if two buttons need not be touched simultaneously.
You can also try changing the component settings to drive unused sensors to shield to get higher signal.
 
Since your 9 buttons are on ITO, I would recommend you don't put the additional 560 ohm series resistance (or use a 0 ohm pad to allow testing) because ITO inherently has higher resistance. 
I'm a little concerned the display might add noise to the buttons, best way is to test it out and try out some filtereing techniques (use those mentioned in AN92239). If possible, having a shield/ground hatched layer between display and buttons would help.
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