IEEE Trans Haptics. 2019 Oct-Dec;12(4):571-580. doi: 10.1109/TOH.2019.2897768. Epub 2019 Feb 6.
Electrovibration has become one of the promising approaches for adding tactile feedback on touchscreen. Previous studies revealed that the normal force applied on the touchscreen by the finger affects significantly the electrostatic force. It is obvious that the normal force affects the electrostatic force if it changes the contact area between the finger and the touchscreen. However, it is unclear whether the normal force affects the electrostatic force when the apparent contact area is constant. In this paper, we estimated the electrostatic force via measuring the tangential force of the finger sliding on a 3M touchscreen at different normal forces under the constant apparent contact area. We found that the electrostatic force increases significantly as the normal force increases from 0.5 to 4.5N. We explained the experimental results using the most recently proposed electrostatic force model, which considers the effect of air gap. We estimated the averaged air gap thickness using the electrostatic force model. The results showed that the relationship between the air gap thickness and the normal force follows a power function. Our experiment suggests that the normal force has a significant effect on the air gap thickness, thus require consideration in the design of tactile feedback.
电振动已成为为触摸屏添加触觉反馈的一种很有前途的方法。先前的研究表明，手指对触摸屏施加的法向力会显著影响静电力。显然，如果手指和触摸屏之间的接触面积发生变化，法向力会影响静电力。但是，当表观接触面积保持不变时，法向力是否会影响静电力尚不清楚。在本文中，我们通过测量在恒定表观接触面积下，手指在 3M 触摸屏上以不同法向力滑动时的切向力，来估算静电力。我们发现，当法向力从 0.5N 增加到 4.5N 时，静电力显著增加。我们使用最近提出的考虑气隙影响的静电力量模型来解释实验结果。我们使用静电力量模型来估计平均气隙厚度。结果表明，气隙厚度与法向力之间的关系符合幂函数关系。我们的实验表明，法向力对气隙厚度有显著影响，因此在设计触觉反馈时需要考虑。
