Computer graphics processing and selective visual display system – Display peripheral interface input device – Stylus
Reexamination Certificate
2002-02-19
2004-09-07
Lao, Lun-Yi (Department: 2673)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Stylus
C345S173000, C382S181000, C382S203000
Reexamination Certificate
active
06788297
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a touch panel type pressure sensitive writing tablet for displaying characters and lines input by a user using a touch panel, a method of controlling this pressure sensitive writing tablet, a program for controlling this pressure sensitive writing tablet, and electronic paper.
2. Background of Related Art
Touch panels are widely used in machines such as automatic teller machines (ATMs) at banks, and ticket vending machines at train stations. The user touches a selected icon or item, typically with a finger, to enter a corresponding instruction to the machine.
A touch panel may be used as a medium for writing characters and pictures on electronic paper. When an icon or item is selected by touching the surface of the touch panel (hereinafter referred to as “touch surface”) with a finger, or when characters are written on a blackboard-sized touch screen, the shortest distance between adjacent touch locations that can be identified and detected on the touch panel may be relatively great. However, when the pressure sensitive writing tablet is applied to electronic paper the size of A4, for example, the shortest distance between adjacent touch locations that can be identified and detected should be greatly reduced, and it is necessary to use a writing stylus comparable to a ball-point pen or a mechanical pencil in size.
The following problems arise when inputting characters and lines on a touch panel using such a pen-like writing stylus.
(a) When inputting a line on a touch panel with a writing stylus, the pressure applied to the touch panel by the writing stylus often varies because the touch surface is relatively slippery, which would produce a number of touch locations along the input line where the stylus pressure is below the threshold value for detection, and no touch is recognized at such positions. As a result, touch locations are actually detected at intervals. If the input line is displayed with the detected touch locations only, it would differ significantly from the one that the user intended to input.
(b) When the user holds the writing stylus by hand and presses the tip of the stylus against the touch surface to write characters or lines, a portion of the hand also contacts the touch surface. The touch panel must then distinguish a touch by the writing stylus from a touch by a portion of the hand. However, if the threshold value for detecting a touch on the touch surface is lowered to overcome the problem described in (a) above, useless contact from a portion of the hand having nothing to do with the input line would also be detected as an intended touch, and the line that is actually displayed would not match the input line intended by the user.
(c) Touches and their touch locations are detected based on digital values which are obtained by converting thereto, with an analog/digital converter (ADC), voltages across pressure sensitive resistors wired in a grid form in vertical and horizontal directions of the touch surface. The number of pressure sensitive resistors in the touch surface of, for example, a 12-inch touch panel used for inputting characters may be approximately 100×100. Assuming that a drive voltage for each pressure sensitive resistor is 5 V, the voltage change across the pressure sensitive resistor due to a touch at one touch location is extremely low, that is, approximately 0.0005 V, and the ADC output is extremely low. If the touch sensitivity of the touch panel is increased in order to resolve the above problem (a), the drive voltage must be significantly increased. This significantly increases power consumption of the touch panel.
(d) The touch locations detected by the touch panel may fluctuate, and when the detected touch locations are sequentially connected in the detected order with straight lines, the displayed line may become a crooked line consisting of very small line segments, which is different from the input line intended by the user.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a pressure sensitive writing tablet capable of improving line input with a touch panel, electronic paper provided with the pressure sensitive writing tablet, a method for controlling the pressure sensitive writing tablet, and a program for making a computer execute the method.
Another object of the invention is to provide a pressure sensitive writing tablet that can faithfully display an input line without particularly increasing touch panel sensitivity, electronic paper provided with the pressure sensitive writing tablet, a method for controlling the pressure sensitive writing tablet, and a program for making a computer execute the method.
A further object of the invention is to provide a pressure sensitive writing tablet that can effectively prevent the touch locations from fluctuating, electronic paper provided with the pressure sensitive writing tablet, a method for controlling the pressure sensitive writing tablet, and a program for making a computer execute the method.
A pressure sensitive writing tablet according to a first aspect of the present invention comprises:
a touch panel for generating an output signal corresponding to a touch surface pressure distribution relating to touch locations where a writing stylus touched the touch surface;
means for generating touch data including data on a touch location and a touch time for each touch of the writing stylus to the touch surface by sampling the output signal of the touch panel, determining if there was a touch of the writing stylus to the touch surface based on the sampled data, and, if there was a touch, detecting the touch location and touch time of the touch;
means for determining, based on the touch data, whether each touch of the touch data is a touch on a contiguous line input on the touch panel;
means for generating velocity data by calculating, based on the touch data, a velocity of the writing stylus at each segment of the contiguous line input on the touch surface, the velocity data including data relating to the calculated velocities;
means for determining, based on the velocity data, a type of a line connecting the touch locations of two touches that are on the contiguous line and temporally adjacent to each other in the detection order (herein after referred to as “adjacent touches”);
means for producing a line drawing connecting the touch locations of the respective adjacent touches based on the line types determined by the line type determining means; and
a display device for displaying the line drawing produced by the line drawing producing means.
The data on the touch locations and touch times included in the touch data may be the touch locations and touch times per se, or relative values for the touch locations and touch times. The relative values for the touch locations may include corrected touch locations used in the fluctuation suppression process described later. The relative values for the touch times may include, for example, the amount of time elapsed from a predetermined reference time which is represented by using a sampling time interval as a unit of measure, or may be sequence numbers assigned to the respective sampling times starting from a predetermined reference sampling time as n=1. The contiguous line input on the touch panel may be, for example, a partial line of a character, a line for drawing, or a line of a picture.
The display is typically a monochrome display. The correspondence between a unit of detection for the touch locations on the touch surface and a pixel on the display does not need to be 1:1. The distribution density of the unit of detection for the touch locations on the touch surface may be greater than or less than the distribution density of pixels on the display. That is, there may be a one-to-plural or plural-to-one correspondence in a partial or whole area between the unit of detection for the touch locations on the touch surface and the pixels on the display. The types of the connecting line determined by the line type d
Itoh Hiroji
Mori Masaya
Tabata Toshiroh
Dillon & Yudell LLP
Lao Lun-Yi
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