Coordinate input/detection device detecting installation position of light-receiving device used for detecting coordinates

A device by which information is written on a drawing board comprising:

• a writing surface providing a coordinate input area;
• and
• a coordinate input/detection device attached to the coordinate input area, including:
• a plurality of retro reflectors provided around the coordinate input area;
• a first light-emitting unit;
• a second light-emitting unit;
• a first light-receiving unit that corresponds to a first position, and is installed at one of first and second positions, at which said first light-receiving unit receives light emitted from said first light-emitting unit to the plurality of retro reflectors and reflected by the plurality of retro reflectors;
• a second light-receiving unit that corresponds to the second position, and is installed at the other position among the first and second positions, at which said second light-receiving unit receives the light emitted from said second light-emitting unit to the plurality of retro reflectors and reflected by the plurality of retro reflectors;
• a position recognition unit recognizing whether each of said first and second light-receiving units is installed at the first position or the second position based on an output signal of each of said first and second light-receiving units;
• and
• a coordinate detection unit detecting coordinates of a pointing unit inserted to the coordinate input area based on output signals of said first and second light-receiving units,
• wherein a ratio of a height to a width of two adjacent retro reflectors among the plurality of retro reflectors is variable, and said position recognition unit recognizes whether each of said first and second light-receiving units is installed at the first position or the second position, in a condition in which said ratio is not one to one, if a shape of the coordinate input area is a square.

A method of detecting installation positions of first and second light-receiving units respectively corresponding to first and second positions, in a coordinate input/detection device including a pair of light-emitting units, and a plurality of retro reflectors around a coordinate input area, said method comprising the steps of:

• emitting light to the plurality of retro reflectors by use of said pair of light-emitting units;
• receiving the light emitted from one of the first and second light-emitting units and reflected by the plurality of retro reflectors, by use of the first light-receiving unit installed at one of the first and second positions;
• receiving the light emitted from the other light-emitting unit and reflected by the plurality of retro reflectors, by use of the second light-receiving unit installed at the other position among the first and second positions;
• and
• recognizing whether each of said first and second light-receiving units is installed at the first position or the second position, based on an output signal of each of said first and second light-receiving units,
• wherein a ratio of a height to a width of two adjacent retro reflectors among the plurality of retro reflectors is variable, and said position recognition step recognizes whether each of said first and second light-receiving units is installed at the first position or the second position, in a condition in which said ratio is not one to one, if a shape of the coordinate input area is a square.

A recording medium readable by a machine, tangibly embodying a program of instructions executable by the machine to control a coordinate input/detection device provided with a coordinate input area, said coordinate input/detection device comprising:

• a plurality of retro reflectors provided around the coordinate input area;
• a first light-emitting unit;
• a second light-emitting unit;
• a first light-receiving unit that corresponds to a first position, and is installed at one of first and second positions, at which said first light receiving unit receives light emitted from said first light-emitting unit to the plurality of retro reflectors and reflected by the plurality of retro reflectors;
• a second light-receiving unit that corresponds to the second position, and is installed at the other position among the first and second positions, at which said second light-receiving unit receives the light emitted from said second light-emitting unit to the plurality of retro reflectors and reflected by the plurality of retro reflectors;
• and
• a coordinate detection unit detecting coordinates of a pointing unit inserted to the coordinate input area based on output signals of said first and second light-receiving units,
• wherein said program is executed by the machine to perform a position recognition function to recognize whether each of said first and second light-receiving units is installed at the first position or the second position, based on an output signal of each of said first and second light-receiving units, and
• wherein a ratio of a height to a width of two adjacent retro reflectors among the plurality of retro reflectors is variable, and said position recognition function recognizes whether each of said first and second light-receiving units is installed at the first position or the second position, in a condition in which said ratio is not one to one, if a shape of the coordinate input area is a square.