Handwriting detection sheet and handwriting system

A handwriting detection sheet comprising:

• a handwriting layer on which a handwriting can be written that can display the handwriting;
• a code layer placed on a rear-face side of the handwriting layer, the code layer comprising a plurality of code images arranged in a matrix manner, wherein the code images in which position codes are encoded are formed with a light absorption material that absorbs infrared light;
• and
• an optical layer placed on a rear-face side of the code layer, the optical layer that reflects infrared light and allows visible light to pass through, wherein
• the position codes have a rotation code part, a X-coordinate code part, and a Y-coordinate code part,
• the rotation code part has a first side edge and a second side edge, and is located in a region defined by at least the first side edge and the second side edge, the first side edge being substantially perpendicular to the second side edge,
• the X-coordinate code part has a third side edge and a fourth side edge, and is located in a region defined by at least the third side edge and the fourth side edge, the third side edge being substantially perpendicular to the fourth side edge, and the third side edge being adjacent to the first side edge of the rotation code part,
• the Y-coordinate code part has a fifth side edge and a sixth side edge, and is located in a region defined by at least the fifth side edge and the sixth side edge, the fifth side edge being substantially perpendicular to the sixth side edge, and the fifth side edge being adjacent to the second side edge of the rotation code part.

A handwriting detection sheet comprising:

• a handwriting layer on which a handwriting can be written that can display the handwriting;
• a code layer placed on a rear-face side of the handwriting layer, the code layer comprising a plurality of code images arranged in a matrix manner, wherein the code images in which position codes are encoded are formed with a light absorption material that absorbs infrared light;
• and
• an optical layer placed on a rear-face side of the code layer, the optical layer that reflects infrared light and allows visible light to pass through,
• wherein the handwriting layer serves as a protective layer for separating the handwriting and the code layer placed on the rear-face side of the handwriting layer.