EP0816992A1
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EP
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Coordinate input apparatus
Assignee: Sharp Corp
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Filing: 1997-06-24
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Granted: —
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Expires: 2017-06-24
Abstract
Abstract It is an object of the invention to provide a coordinate input apparatus which can eliminate an input point erroneously inputted. Values of voltage of pairs of electrodes (31, 32); (33, 34) of a tablet (24) are sampled at time t1 by A/D converter circuits (41, 42) to obtain values of X and Y coordinates of a latest input point. A coordinate predicting circuit (43) finds a predicted point of an input point of one period ahead from the coordinates of the latest input point and the input point at time t0 of one period before. The predicted point of the input point at time t1 is find in advance when the input point at time t0 is obtained. An erroneous input discriminating circuit (44) finds an error of the coordinates of the latest input point and the predicted point with respect to X- and Y-axis directions. When the error of the coordinates is less than an allowable error both in X- and Y-axis directions, the input point is determined to be valid and the coordinate of the input point is supplied to a buffer (47) as it is. When the error of the coordinates is the allowable error or more, the input point is determined to be invalid and (0, 0) is supplied to the buffer (47).
Inventors
- 👤 Takuma Joto
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 20:32
CPC Classifications
G; G06; G06F; G06F3/00; G06F3/01; G06F3/03; G06F3/041; G06F3/045; G06F3/0416; G06F3/0418; G06F3/048; G06F3/0487; G06F3/0488
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
215 words
A coordinate input apparatus (21) comprising: two-dimensional coordinate input means (24) having a
flat pointing area (31), for outputting a two-dimensional
coordinate corresponding to a point within the pointing area
which is continuously pointed, per predetermined period; coordinate predicting means (43) for defining a
predicted coordinate area (E1-E3) showing a range of a
coordinate predicted to be outputted from the two-dimensional
coordinate input means (24) in correspondence to the coordinate
outputted from the two-dimensional coordinate input means, in
accordance to a predetermined procedure per predetermined
period; erroneous input discriminating means (44, 81) for
determining that the coordinate outputted from the two-dimensional
coordinate input means (24) is valid only when the
coordinate is contained within the predicted coordinate area
defined in correspondence to the coordinate; and coordinate defining means (45a, 45b, 46a, 46b) for
defining the coordinate outputted from the two-dimensional
coordinate input means (24) as it is when the coordinate is
determined to be valid by erroneous input discriminating means
(44, 81) and for rejecting the coordinate when it is determined
to be invalid; wherein the coordinate predicting means (43)
corresponds to the output of the coordinate defining means
(45a, 45b, 46a, 46b) and defines the predicted coordinate area
by using a plurality of coordinates defined by the coordinate
defining means (45a, 45b, 46a, 46b).
Claim 2
Dependent Claim
130 words
The coordinate input apparatus (21) of claim 1, wherein the coordinate predicting means (43) comprises; displacement computing means (55, 56) for determining
a displacement (d) in coordinate to a past coordinate (X0, Y0)
defined in a latest past from a latest coordinate (X1, Y1)
defined by the coordinate defining means (45a, 45b, 46a, 46b)
and a displacement direction (36); and predicted coordinate computing means (57, 58) for
determining a predicted coordinate (Xp, Yp) which is displaced
from the latest coordinate (X1, Y1) defined by the coordinate
defining means (45a, 45b, 46a, 46b) by the displacement (d)
determined by the displacement computing means (55, 56) in the
displacement direction (36); wherein an area having the predetermined size
containing the predicted coordinate (Xp, Yp) is set as the
predicted coordinate area (E1-E3).
Claim 3
Dependent Claim
76 words
The coordinate input apparatus (21) of claim 2, wherein two coordinate axes which cross each other are
set in the pointing area, that coordinates are represented by
values of a corresponding point on the respective coordinate
axes and that the predicted coordinate area, each side
(E1a-E1d) of which the predicted coordinate area (E1) is
parallel with either of the coordinate axes and has a
predetermined length, is an area centered on the predicted
coordinate (Xp, Yp).
Claim 4
Dependent Claim
34 words
The coordinate input apparatus (21) of claim 2, wherein the predicted coordinate area (E2) is a circular
area which is centered on the predicted coordinate (Xp,Yp),
having a radius of a predetermined length (Lt).
Claim 5
Dependent Claim
72 words
The coordinate input apparatus (21) of claim 2, wherein the predicted coordinate area (E3) is a sector
area having a radius of a predetermined length (Zt) and a
central angle of a predetermined degree (Zw) and that a line
segment having both ends of the defined latest coordinate (X1,
Y1) and the predicted coordinate (Xp, Yp) passes through the
center (Zc) of an imaginary circle containing an arc of the
sector area.
Claim 6
Dependent Claim
164 words
The coordinate input apparatus (21) of claim 2, wherein the erroneous input discriminating means (44,
81) comprises; error detecting means (62, 63) for determining an error
(Xe, Ye) which is a distance between a point represented by
the coordinate outputted from the two-dimensional coordinate
input means (24) and a point represented by the predicted
coordinate (Xp, Yp) determined by the predicted coordinate
computing means (57, 58), corresponding to the coordinate; and discriminating means (66, 67, 69) for determining that
the latest coordinate (X1, Y1) is valid when the error (Xe,
Ye) determined by the error detecting means is less than a
predetermined distance between the end of the predicted
coordinate area (E1-E3) and a point represented by the
predicted coordinate (Xp, Yp) in the direction heading to a
point (P1) represented by the coordinate outputted from the
point (R1) represented by the predicted coordinate (Xp, Yp)
and for determining that the latest coordinate is invalid when
the error is the predetermined distance or more.
Claim 7
Dependent Claim
110 words
The coordinate input apparatus of (21) claim 1, wherein the two-dimensional coordinate input means (24)
outputs a status signal (Ss, Sd) indicative of that the
coordinate has been outputted every time of outputting
two-dimensional coordinate, the coordinate input apparatus
further comprising a delay circuit for delaying the status
signal by a predetermined delay time necessary for outputting
coordinates of a predetermined number of points used in
defining the predicted coordinate area (E1-E3) from the
two-dimensional coordinate input means (24) and for outputting
the status signal to the coordinate defining means, wherein the coordinate defining means (45a, 45b, 46a,
46b) defines the coordinate only when the status signal (Sd)
is supplied.
Claim 8
Dependent Claim
128 words
The coordinate input apparatus (21) of claim 7, wherein the erroneous input discriminating means (44,
81) determines whether the coordinate is valid or not only when
the status signal outputted from the delay circuit is supplied, the delay circuit is constructed so that the output from
the erroneous input discriminating means is supplied thereto,
the same number of memory elements (52, 61) with the
predetermined number are connected sequentially so that the
outputs thereof are transferred to the next memory elements
and the outputs of the previous memory elements are supplied
per predetermined period, and each memory element (52, 61) stores each status signal
(Ss, Sd) individually and erases its memory content when the
coordinate is determined to be invalid by the erroneous input
discriminating means (44, 81).
References Cited (Backward Citations)
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