Computer graphics processing and selective visual display system – Display peripheral interface input device – Touch panel
Reexamination Certificate
2000-01-20
2003-03-11
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Touch panel
C345S175000, C345S177000, C345S179000, C345S166000
Reexamination Certificate
active
06532006
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a coordinates input device, a coordinates input method with which the coordinates of a manually specified point can be input and a display board system which uses such a coordinates input device.
BACKGROUND OF THE INVENTION
Presently there is known a display board system in which a freehand information (e.g. characters, drawings etc.) written on the surface of the board (hereafter called as writing surface), which surface defines an entry area, can be input into a computer or so in real time. Such a display board system uses a coordinates input device which detects the coordinates of the position of the pen where the pen touches the writing surface and successively inputs these coordinates into a computer or the like.
In one of the methods of detecting coordinates by the coordinates input device, light is made use of. For instance, light is irradiated on the entire surface of the writing surface and the reflected light is detected. When something is written on the writing surface, the pen hinders the light and the coordinates of the position of the pen can be obtained from the detected reflected light. Such a method is disclosed in Japanese Patent Laid-Open Publication No. HEI 9-91094. In the Japanese Patent Laid-Open Publication No. HEI 9-91094 there is disclosed a configuration in which a light source is driven using a driving unit in such amanner that the light is irradiated on the entire surface of the writing surface (which may be a touch panel) and the writing surface can be scanned with the light.
There is a further simplified configuration obtained by removing a driving unit from the device described above. In this configuration, light emitted from a light source is spread in a fan shape using a lens or the like so as to cover an entire area of the writing surface.
FIG. 13
explains the principles of this method in a simple manner. The configuration shown in the figure comprises a panel
100
as a writing surface, a reflector
2
provided on the three sides of the panel
100
, and a light source R provided at the lower-right corner and a light source L provided at the lower-left corner of the panel
100
. Point P(x
p
, y
p
) on the panel
100
indicates a position of a pen tip on the panel
100
.
The light emitted from any of the light sources R and L is spread by a lens (not shown) placed on the front surface of each of the light sources R and L and becomes a light flux in a fan shape (hereafter called as fan-shaped light flux) having a central angle of 90 degrees. This fan-shaped light flux is reflected by the reflector
2
provided at the edge of the panel
100
. This reflector
2
is designed in such a way that a fan-shaped light flux is reflected along an optical axis which is identical to the one along which the light came in. Therefore, the fan-shaped light flux in reflected back towards the light sources R and L along an optical axis which is identical to the one along which the light came in. This reflected light is directed towards a not shown light receiver, for instance, using a not shown mirror provided on this optical axis and the light is detected.
When the tip of the pen tip is placed on the position of point P on the panel
100
, a light beam passing through the point P of the fan-shaped light flux is reflected by the pen tip and it does not reach the reflector
2
(in the specification, this situation will be described as “the light beam is blocked by the pen tip”) Therefore, only the reflected light of the light beam passing through the point P of the fan-shaped light flux can not resultantly be detected by the light receiver. By using, for example, a CCD line sensor as the light receiver, optical axis of the light beam which is not received can be identified from the whole reflected light beams.
Since the optical axis of the reflected light is identical to that of the emitted light and the point P exists on the optical axis of a light beam which is not detected, a angle of emission of the light beam passing through the point P can be calculated from the optical axis of the reflected light which is not detected. Therefore, angle of emissions &thgr;
L
and &thgr;
R
can be calculated from the results of reception of light by the two light receivers, and optical axes a
L
and a
R
can be calculated from those angle of emissions. Further, coordinates (x
p
, y
p
) of the point P, which is an intersection point of the optical axes a
L
and a
R
can also be calculated.
More specifically, the coordinates (x
p
, y
p
) of the point P can be calculated as described below. Namely,
x
p
=(tan &thgr;
R
·W
)/(tan &thgr;
R
+tan &thgr;
L
) (1)
&AutoLeftMatch;
y
p
=
(
tan
θ
R
·
tan
θ
L
·
W
)
/
(
tan
θ
R
+
tan
θ
L
)
=
x
p
·
tan
θ
L
(
2
)
Where W is a distance between centers of the light sources R and L.
Thus, the coordinates input device reads a locus of a pen tip by successively reading coordinates of the pen tip moving along the panel
100
and can automatically record contents written in the panel
100
.
The distance W between centers of the light sources R and L is used in equations (1) and (2) for calculating coordinates (x
p
, y
p
). However, the distance W may slightly vary depending upon the accuracy with which the light sources R and L are attached to the panel
100
. Further, the distance W may slightly vary depending upon the accuracy with which the dimensions of the panel
100
have been maintained during manufacture. If the distance W varies, the variation is also reflected into the results of the equations (1) and (2). Therefore, there is a great probability that coordinates (x
p
, y
p
) can not accurately be calculated.
In addition, the material used to manufacture the panel
100
can easily be machined and is low cost, however, it can easy get deformed (expand or shrink) depending upon the surrounding temperature. Therefore, there is great possibility that the coordinates (x
p
, y
p
) may change depending on the surrounding temperature.
In order to solve the above-described problems, i.e. to keep the value of W to be as a designed value at any time, it is required to improve accuracy of attachment of the light sources R and L to the panel
100
. Further, improve the accuracy in maintaining the dimensions of the panel
100
, and to manufacture the panel
100
with a material which does not deform much depending upon the temperature. However, most of the technologies that improve accuracy of attachment and accuracy of dimensions requires sense and experience of a skilled engineer, therefore it has been thought that the technology is generally inappropriate to be applied to products to be mass-produced. Regarding manufacturing the panel
100
with a material which does not deform much depending upon the temperature, if such material is used then the easiness of machining may be damaged or the cost of manufacturing may be increased.
SUMMARY OF THE INVENTION
The present invention has been made for solving the problems described above, and it is a first object of the present invention to provide a coordinates input device and a display board system enabling an accurate detection of an obstacle.
In addition, it is a second object of the present invention to provide a coordinates input device and a display board system enabling accurate detection of the obstacle any time no matter how much the material used for manufacturing the entry area gets deformed.
The problems described above can be solved by the means described below.
The coordinates input device according to one aspect comprises a light emitter which emits a light flux to a specified entry area; a light receiver which receives the light flux emitted from the light emitter; a coordinate calculator for calculating coordinates of an obstacle in the light flux on the entry area based on the light flux received by the light receiver and the dimensions of the entry area; an
Ito Takahiro
Ogasawara Tsutomu
Takekawa Kenichi
Dinh Duc
Hjerpe Richard
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh & Company, Ltd.
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