With the increasing demand for new technologies, the size of capacitive touch screens has become larger and larger in the development of touch products, making it more intuitive and convenient to use writing devices similar to paper and pen. The most common method for manufacturers to support stylus functionality is to use an active stylus or a passive stylus. Active handwriting pens use electronic components, require a power supply, and transmit signals to the host device. The use of an active stylus can support advanced features such as hovering, pressure sensing, button support, and erasing on the display screen. Passive handwriting pens use conductive materials, which are equivalent to an extension of the user's body. The capacitive coupling of the user's hand supports passive stylus to send signals when touching the screen. There is no active communication between the stylus and the host platform, so it is a challenge to distinguish between fingers and passive stylus.
In many cases, if both active and passive handwriting pens can achieve the same characteristics, there is no need to add additional costs to the system. The additional components and power requirements of an active stylus make it difficult to find a market, while the poor performance and/or bulky head of a passive stylus can result in an unnatural handwriting experience. Therefore, if the pen tip of a passive stylus is 1 to 2 millimeters, and the user can place their palm on the screen while handwriting, while maintaining sufficient speed and accuracy, and ensuring that the contact point is exactly where the ink is applied, the user experience of the passive stylus can be improved.
In order to create a practical implementation that supports both finger and passive stylus operations, multiple different usage scenarios must be considered. For example, developers should consider the switching speed between detecting finger and stylus input in the system. Similarly, they also need to define the system's response when the stylus touches the screen before, after, or simultaneously with the finger/palm. Other important factors include configuring the stylus to no longer detect signals when it is close to the hand.
The simplest and most direct method is to use the electric current inherent in the human body to interact with the touch all-in-one machine through fingers, achieving practical and convenient visual operations.