Pen state detection circuit and method, and input system

1. A pen state detection circuit for detecting a state of an electronic pen based on a signal distribution detected by a touch sensor including a plurality of sensor electrodes arranged in a plane shape, the electronic pen including a plurality of pen electrodes, the pen state detection circuit comprising:

a processor; and

a memory storing instructions which, when executed by the processor, cause the pen state detection circuit to:

acquire, from the touch sensor, a two-dimensional signal distribution or a two-dimensional feature distribution, indicating a change in capacitance with approach of the pen electrodes, wherein the two-dimensional signal distribution or the two-dimensional feature distribution includes image signals with a plurality of color channels corresponding to the pen electrodes; and

estimate, using an input and output model, a position indicated by the electronic pen or a posture of the electronic pen from the two-dimensional signal distribution or two-dimensional feature distribution.

2. The pen state detection circuit according to claim 1 , wherein the electronic pen includes at least a tip electrode that is symmetrical about an axis of the electronic pen and is disposed at a distal end of the electronic pen and an upper electrode that is symmetrical about the axis of the electronic pen and is disposed closer to a proximal end of the electronic pen than the tip electrode.

3. The pen state detection circuit according to claim 1 , further comprising a first signal distribution along a first direction on the touch sensor and a second signal distribution along a second direction intersecting the first direction, each of the first signal distribution and the second signal distribution being a one-dimensional signal distribution indicating a change in capacitance with approach of the pen electrodes, and

generate a two-dimensional signal distribution by synthesizing the first signal distribution and second signal distribution, or generates a two-dimensional feature distribution by synthesizing a first feature distribution relating to a shape of the first signal distribution and a second feature distribution relating to a shape of the second signal distribution.

4. The pen state detection circuit according to claim 3 , wherein, in the synthesizing, the pen state detection circuit generates the two-dimensional signal distribution by multiplying a first corresponding value corresponding to a position in the first direction in the first signal distribution by a second corresponding value corresponding to a position in the second direction in the second signal distribution, or generates the two-dimensional feature distribution by multiplying a first corresponding value corresponding to a position in the first direction in the first feature distribution by a second corresponding value corresponding to a position in the second direction in the second feature distribution.

5. The pen state detection circuit according to claim 3 , wherein the input and output model is a machine learning model including a convolutional neural network which, in operation, receives, as an input, the two-dimensional signal distribution or the two-dimensional feature distribution and outputs coordinate values indicating the position indicated by the electronic pen.

6. The pen state detection circuit according to claim 3 , wherein the input and output model is a machine learning model including a convolutional neural network which, in operation, receives, as an input, the two-dimensional signal distribution or the two-dimensional feature distribution and outputs at least one of a tilt angle or rotation angle indicating the posture of the electronic pen.

7. A method for detecting a state of an electronic pen based on a signal distribution detected by a touch sensor including a plurality of sensor electrodes arranged in a plane shape, the electronic pen including a plurality of pen electrodes, the method comprising:

acquiring, by a pen state detection circuit, from the touch sensor, a two-dimensional signal distribution or a two-dimensional feature distribution, indicating a change in capacitance with approach the pen electrodes, wherein the two-dimensional signal distribution or the two-dimensional feature distribution includes image signals with a plurality of color channels corresponding to the pen electrodes; and

estimating, by the pen state detection circuit, using an input and output model, a position indicated by the electronic pen or a posture of the electronic pen from the two-dimensional signal distribution or two-dimensional feature distribution.

8. A system, comprising:

an electronic pen including a plurality of pen electrodes;

an electronic device including a pen state detection circuit that, in operation, detects a state of the electronic pen based on a signal distribution detected by a touch sensor including a plurality of sensor electrodes arranged in a plane shape, the pen state detection circuit comprising:

a processor; and

a memory storing instructions which, when executed by the processor, cause the pen state detection circuit to:

acquire, from the touch sensor, a two-dimensional signal distribution or a two-dimensional feature distribution, indicating a change in capacitance with approach of the pen electrodes, wherein the two-dimensional signal distribution or the two-dimensional feature distribution includes image signals with a plurality of color channels corresponding to the pen electrodes; and

estimate, using an input and output model, a position indicated by the electronic pen or a posture of the electronic pen from the two-dimensional signal distribution or two-dimensional feature distribution.