Character recognition apparatus

Claim 1

A character recognition apparatus for identifying a character from data in detecting the positional movement of a stylus with respect to a tablet defining relative position with detection means in terms of X, Y and Z coordinate axes, comprising: detection circuit means for detecting the initiation and completion of the movement of said pen for writing said character by detectinq a change of the position of the pen on the Z-coordinate axis normaI to the surface of the tablet and by comparing the difference of two pen positions in the plane of the X and Y axes before and after the change of the pen position; character size normalizing circuit means for normalizing the size of written characters by processing said data according to the following equations: X'=C (X.sub.t -Xmin)÷A (1) Y'=C (Y.sub.t -Ymin)÷B (2) where A represents a maximum shift of the pen along the X-axis and B represents the maximum shift of the pen along the Y-coordinate axis, C is a desired character size after normalization, X' t , Y t are coordinates of the pen position on the X and Y axes, respectively, Xmin, Ymin are the minimum value of the position of the pen for writing one character on the X and Y axes, respectively, and X' and Y' are transformed coordinates after the normalization; calculating circuit means for calculating gradient θ and length L of a line segment of a stroke of a character by processing data on the pen position upon writing according to the following equations: A=X'.sub.t -X'.sub.t-1 ( 3) B=Y'.sub.t -Y'.sub.t-1 ( 4) Tanθ=B÷A (5) ##EQU2## where X'.sub.t, X'.sub.t-1 are transformed X-coordinates taken at the time t, and t-1, respectively, and Y'.sub.t, Y'.sub.t-1 are also transformed Y-coordinates taken at times t and t-1; determination means for extracting distinction of a stroke of a character by order of occurrence of θ and L of line segment(s) of a stroke; and character recognition circuit means for recognizing character by combination in terms of the order or occurrence of the distinctions of strokes.