Writing and locating method of active pen

Abstract

The invention provides a writing and locating method of an active pen. In the method, firstly, when the active pen touches a screen, an image acquisition unit shoots and acquires an image on that the active pen touches the screen; secondly, an image binary processing unit carries out binarization processing on the image obtained in the first step, and related coordinates of the image are extracted; thirdly, an image edge processing unit extracts the image edge outline of the image which is processed in the second step; fourthly, a curvature processing module calculates the curvature of each point of the image edge outline which is obtained in the third step; fifthly, the curvature processing module works out the coordinates of the starting position of the active pen according to the curvature obtained in the fourth step; and sixthly, the coordinates obtained in the fifth step are displayed through a display device of a control computer. In the invention, different methods for finding the center of gravity are selected through judging the magnitude of the difference value of the curvature among all the points, and no matter whether the plane in which a user holds the pen is vertical to a writing plane or not, a display position can be automatically corrected to be the position that the user starts from to write with the pen.

Description

technical field [0001] The invention relates to electronic writing technology, in particular to a writing positioning method of an active pen. Background technique [0002] Large-size screen interactive touch products are more and more popular with many users, and have broad application prospects in teaching multimedia and other fields. At present, most of the large-size screen touch products are based on optical camera positioning technology, and there are two methods of camera surface positioning and camera rear positioning. Some of these two methods use an auxiliary infrared laser source to write with fingers or a passive pen; the other does not have an auxiliary infrared laser source and uses an active pen to write directly. The active pen is squeezed when it touches the screen and emits red light. , the red light is captured by the camera sensor, sent to the image acquisition card for processing, and the starting position of the writing pen is determined through image ...

AI Technical Summary

Problems solved by technology

like figure 2 As shown, when the hand-held pen is not perpendicular to the touch surface but tilted, the luminescence of the active pen is partially blocked, and the curvature of the edge of the collected image varies in a large range, and the binarized image is similar to a fan. The center of gravity of the obtained image is 3 is not the starting position of the pen. 2. The starting position of the pen is at the sharper part of the graphic edge. In this way, the pen-down position is different from the writing display position, and the writing effect is very unnatural. Especially when drawing lines with a ruler, the pen is generally Inclined to the touch surface, the display is even more inconvenient

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