Electromagnetic stylus force adjustment mechanism to ensure stylus force is constant irrespective of the vertical position of the stylus.

电磁探针压力调整系统，不管探针在何垂直位置都可保证探针压力不变。

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Sony's freshly granted patent claims that a microphone can take on that job instead by listening to the sound your finger or stylus makes when it hits the screen and deducing force from that.

ENGADGET: Sony patent claims touch force detection via microphone