Optical digitizer and display means for providing display of indicated position

Claim 2

An optical digitizer for determining a position of a pointing object which projects a light and which is disposed on a coordinate plane, the optical digitizer comprising: detector means disposed on a periphery of the coordinate plane and having a field of view covering the coordinate plane for receiving the light projected by the pointing object and for converting the received light into a corresponding electric signal; processor means for processing the electric signal output by the detector means to compute coordinates representing the position of the pointing object on the coordinate plane; collimator means disposed to limit the field of view of the detector means below a predetermined height relative to the coordinate plane such that through the limited field of view the detector means can receive a parallel component of the light which is projected by the pointing object substantially in parallel to the coordinate plane; shield means disposed to enclose the periphery of the coordinate plane to block out noise comprising light other than the projected light from entering into the limited field of view of the detector means; and a light source for producing a varying color illumination light over the coordinate plane so that the detector means receives the light which is passively projected by the pointing object by reflection of the illumination light; wherein the detector means receives the light reflected by the pointing object, which has a particular surface color, so that the electrical signal varies in accordance with the particular surface color of the pointing object, and the processor means processes the electric signal so as to discriminate the particular surface color of the pointing object as well as to compute the position of the pointing object.

Claim 3

An optical digitizer according to claim 1, wherein the detector means comprises a pair of linear image sensors for receiving the projected light at different directions to produce electric signals representing a pair of one-dimensional images of the pointing object, so that the processor means processes the one-dimensional images to compute two-dimensional coordinates of the position of the pointing object.

Claim 4

An optical digitizer according to claim 1, wherein the collimator means comprises a collimator lens for converging only the parallel component of the projected light onto a receiving surface of the detector means.

Claim 5

An optical digitizer according to claim 3, wherein the collimator lens has a flat bottom face, a flat top face and a curved lens face between the flat bottom face and the flat top face so that an optical axis of the collimator lens aligns parallel to the coordinate plane when the flat bottom face of the collimator lens is placed in contact with the coordinate plane.

Claim 6

An optical digitizer according to claim 4; further comprising optical means having at least one of a reflector and a refractor disposed in an optical path between the collimator lens mounted on the coordinate plane and the detector means mounted above the coordinate plane for directing the light collected by the collimator lens to the detector means.

Claim 7

An optical digitizer according to claim 3, wherein the collimator lens has an optical axis vertical to the coordinate plane, and further comprising reflector means disposed on the coordinate plane for reflecting the parallel component of the projected light vertically to the collimator lens.

Claim 8

An optical digitizer according to claim 1, further comprising a light source for providing an illumination light over the coordinate plane, so that the detector means receives the light which is passively projected from the pointing object by reflection of the illumination light.

Claim 9

An optical digitizer according to claim 7, wherein the light source intermittently turns on and off to provide a flashing illumination light, and wherein the processor means processes the electric signal which is fed from the detector means in synchronization with the flashing illumination light so as to compute the position of the pointing object illuminated by the light source.

Claim 10

An optical digitizer according to claim 8, wherein the detector means comprises an image sensor composed of an accumulator for accumulating electric charges generated by the received light so as to convert the received light into the electric signal, and a shutter gate which switches between an open state and a closed state in synchronization with the flashing illumination light so as to control accumulation of the electric charges in the accumulator.

Claim 11

An optical digitizer according to claim 8, wherein the light source intermittently turns on and off to provide the flashing illumination light while cyclically changing a color of the flashing illumination light, wherein the detector means receives the light reflected by the pointing object having a particular surface color so that the electric signal cyclically varies in dependence on the particular surface color of the pointing object, and wherein the processor means processes the electric signal so as to discriminate the particular surface color of the pointing object as well as to compute the position of the pointing object.

Claim 12

An optical digitizer according to claim 7, wherein the light source provides an illumination light having a first wavelength, and wherein the detector means has an optical filter for selectively receiving the light which is projected from a fluorescent surface of the pointing object illuminated by the light source and which has a second wavelength different than the first wavelength.

Claim 13

An optical digitizer according to claim 11, wherein the light source provides an illumination light having a first wavelength in an ultraviolet range, and wherein the detector means has an optical filter for selectively receiving the light having a second wavelength in a visible range.

Claim 14

An optical digitizer according to claim 1, wherein the detector means comprises a color image sensor for receiving the projected light specific to color information assigned to the pointing object and for converting the received light into a corresponding electric signal, and wherein the processor means processes the electric signal so as to discriminate the color information of the pointing object as well as to compute the position of the pointing object.

Claim 15

An optical digitizer for determining a position of a pointing object which projects a light and which is disposed on a coordinate plane, the optical digitizer comprising: detector means disposed around the coordinate plane and having a field of view covering the coordinate plane for receiving the light projected by the pointing object and for converting the received light into a corresponding electric signal; processor means for processing the electric signal output by the detector means to compute coordinates representing the position of the pointing object on the coordinate plane; collimator means disposed to limit the field of view of the detector means below a predetermined height relative to the coordinate plane such that through the limited field of view the detector means can receive a parallel component of the light which is projected by the pointing object substantially in parallel to the coordinate plane; and a light source for producing a varying color illumination light over the coordinate plane so that the detector means receives the light which is passively projected by the pointing object by reflection of the illumination light; wherein the detector means receives the light reflected by the pointing object, which has a particular surface color, so that the electrical signal varies in accordance with the particular surface color of the pointing object, and the processor means processes the electric signal so as to discriminate the particular surface color of the pointing object as well as to compute the position of the pointing object; wherein the detector means comprises a pair of linear image sensors for receiving the projected light at different directions to produce electric signals representing a pair of one-dimensional images of the pointing object, the processor means processes the one-dimensional images to compute two-dimensional coordinates of the position of the pointing object, the collimator means comprises a collimator lens for converging only the parallel component of the projected light onto a receiving surface of the linear image sensor, the collimator lens has a flat bottom face, a flat top face and a curved lens face between the flat bottom face and the flat top face so that an optical axis of the collimator lens aligns parallel to the coordinate plane when the flat bottom face of the collimator lens is placed in contact with the coordinate plane; and further comprising optical means having at least one of a reflector and a refractor disposed in an optical path between the collimator lens mounted on the coordinate plane and the linear image sensor mounted above the coordinate plane for directing the light collected by the collimator lens to the linear image sensor.

Claim 16

An optical digitizer for determining a position of a pointing object which projects a light and which is disposed on a coordinate plane, the optical digitizer comprising: detector means disposed around the coordinate plane and having a field of view covering the coordinate plane for receiving the light projected by the pointing object and for converting the received light into a corresponding electric signal; processor means for processing the electric signal output by the detector means to compute coordinates representing the position of the pointing object on the coordinate plane; collimator means disposed to limit the field of view of the detector means below a predetermined height relative to the coordinate plane such that through the limited field of view the detector means can receive a parallel component of the light which is projected by the pointing object substantially in parallel to the coordinate plane; and a light source for producing a varying color illumination light over the coordinate plane so that the detector means receives the light which is passively projected by the pointing object by reflection of the illumination light; wherein the detector means receives the light reflected by the pointing object, which has a particular surface color, so that the electrical signal varies in accordance with the particular surface color of the pointing object, and the processor means processes the electric signal so as to discriminate the particular surface color of the pointing object as well as to compute the position of the pointing object; wherein the detector means comprises a pair of linear image sensors for receiving the projected light at different directions to produce electric signals representing a pair of one-dimensional images of the pointing object, the processor means processes the one-dimensional images to compute two-dimensional coordinates of the position of the pointing object, the collimator means comprises a collimator lens for converging only the parallel component of the projected light onto a receiving surface of the linear image sensor, the collimator lens has a flat bottom face, a flat top face and a curved lens face between the flat bottom face and the flat top face so that an optical axis of the collimator lens aligns parallel to the coordinate plane when the flat bottom face of the collimator lens is placed in contact with the coordinate plane; and further comprising optical means having at least one of a reflector and a refractor disposed in an optical path between the collimator lens mounted on the coordinate plane and the linear image sensor mounted above the coordinate plane for directing the light collected by the collimator lens to the linear image sensor.

Claim 17

An optical digitizer for determining a position of a pointing object which projects a light and which is disposed on a coordinate plane, the optical digitizer comprising: detector means disposed around the coordinate plane and having a field of view covering the coordinate plane for receiving the light projected by the pointing object and for converting the received light into a corresponding electric signal; processor means for processing the electric signal output by the detector means to compute coordinates representing the position of the pointing object on the coordinate plane; and collimator means disposed to limit the field of view of the detector means below a predetermined height relative to the coordinate plane such that through the limited field of view the detector means can receive a parallel component of the light which is projected from the pointing object substantially in parallel to the coordinate plane; and a light source for producing a varying color illumination light over the coordinate plane so that the detector means receives the light which is passively projected by the pointing object by reflection of the illumination light; wherein the detector means receives the light reflected by the pointing object, which has a particular surface color, so that the electrical signal varies in accordance with the particular surface color of the pointing object, and the processor means processes the electric signal so as to discriminate the particular surface color of the pointing object as well as to compute the position of the pointing object; wherein the collimator means comprises a collimator lens for converging only the parallel component of the projected light onto a receiving surface of the detector means, and the collimator lens has an optical axis vertical to the coordinate plane; and further comprising reflector means disposed on the coordinate plane for reflecting the parallel component of the projected light vertically with respect to the collimator lens.

Claim 18

An optical digitizer for determining a position of a pointing object which projects a light and which is disposed on a coordinate plane, the optical digitizer comprising: detector means disposed around the coordinate plane and having a field of view covering the coordinate plane for receiving the light projected by the pointing object and for converting the received light into a corresponding electric signal; processor means for processing the electric signal output by the detector means to compute coordinates representing the position of the pointing object on the coordinate plane; and collimator means disposed to limit the field of view of the detector means below a predetermined height relative to the coordinate plane such that through the limited field of view the detector means can receive a parallel component of the light which is projected from the pointing object substantially in parallel to the coordinate plane; and a light source for producing a varying color illumination light over the coordinate plane so that the detector means receives the light which is passively projected by the pointing object by reflection of the illumination light; wherein the detector means receives the light reflected by the pointing object, which has a particular surface color, so that the electrical signal varies in accordance with the particular surface color of the pointing object, and the processor means processes the electric signal so as to discriminate the particular surface color of the pointing object as well as to compute the position of the pointing object; wherein the collimator means comprises a collimator lens for converging only the parallel component of the projected light onto a receiving surface of the detector means, and the collimator lens has an optical axis vertical to the coordinate plane; and further comprising reflector means disposed on the coordinate plane for reflecting the parallel component of the projected light vertically with respect to the collimator lens.

Claim 19

An optical digitizer according to claim 15, wherein the reflector means comprises a half-mirror, further comprising a light source disposed adjacent to the collimator lens for illuminating through the half-mirror the pointing object having a retro-reflective surface, and wherein the detector means receives through the half-mirror the light projected back from the retro-reflective surface of the pointing object illuminated by the light source.

Claim 20

An optical digitizer for determining a position of a pointing object which projects a light and which is disposed on a coordinate plane, the optical digitizer comprising: detector means disposed around the coordinate plane for receiving the light projected by the pointing object and for converting the received light into a corresponding electric signal; processor means for processing the electric signal output by the detector means to compute coordinates representing the position of the pointing object on the coordinate plane; a light source for producing a varying color illumination light over the coordinate plane so that the detector means receives the light which is passively projected by the pointing object by reflection of the illumination light; wherein the detector means receives the light reflected by the pointing object, which has a particular surface color, so that the electrical signal varies in accordance with the particular surface color of the pointing object; wherein the light source intermittently turns on and off to provide a flashing illumination light, and the processor means processes the electric signal which is output by the detector means in synchronization with the flashing illumination light so as to discriminate the particular surface color of the pointing object and to compute the position of the pointing object illuminated by the light source.

Claim 21

An optical digitizer for determining a position of a pointing object which projects a light and which is disposed on a coordinate plane, the optical digitizer comprising: detector means disposed around the coordinate plane for receiving the light projected by the pointing object and for converting the received light into a corresponding electric signal; processor means for processing the electric signal output by the detector means to compute coordinates representing the position of the pointing object on the coordinate plane; a light source for producing a varying color illumination light over the coordinate plane so that the detector means receives the light which is passively projected by the pointing object by reflection of the illumination light; wherein the detector means receives the light reflected by the pointing object, which has a particular surface color, so that the electrical signal varies in accordance with the particular surface color of the pointing object; wherein the light source intermittently turns on and off to provide a flashing illumination light, and the processor means processes the electric signal which is output by the detector means in synchronization with the flashing illumination light so as to discriminate the particular surface color of the pointing object and to compute the position of the pointing object illuminated by the light source.

Claim 22

An optical digitizer according to claim 17; wherein the detector means comprises an image sensor composed of an accumulator for accumulating electric charge generated in response to the received light so as to convert the received light into the electric signal, and a shutter gate which switches between an open state and a closed state in synchronization with the flashing illumination light so as to control the accumulation of the electric charge in the accumulator.

Claim 23

An optical digitizer comprising: a pointing tool projecting a light and being manipulated on a coordinate plane to perform a drawing operation and an incidental operation associated to the drawing operation; detector means disposed around the coordinate plane for receiving the light projected from the pointing tool and for converting the received light into an electric signal; and processor means for processing the electric signal fed from the detector means to compute coordinates representing the position of the pointing tool; wherein the pointing tool has modulating means responsive to the incidental operation for varying color components contained in the projected light, wherein the detector means outputs the electric signal according to the color components contained in the projected light, and wherein the processor means processes the electric signal so as to obtain information of the incidental operation as well as to compute the position of the pointing tool during the drawing operation.

Claim 24

An optical digitizer comprising: a pointing tool projecting a light and being manipulated on a coordinate plane to perform a drawing operation and an incidental operation associated to the drawing operation; detector means disposed around the coordinate plane for receiving the light projected from the pointing tool and for converting the received light into an electric signal; and processor means for processing the electric signal fed from the detector means to compute coordinates representing the position of the pointing tool; wherein the pointing tool has modulating means responsive to the incidental operation for varying color components contained in the projected light, wherein the detector means outputs the electric signal according to the color components contained in the projected light, and wherein the processor means processes the electric signal so as to obtain information of the incidental operation as well as to compute the position of the pointing tool during the drawing operation.

Claim 25

An optical digitizer comprising: a pointing tool projecting a light and being manipulated on a coordinate plane to perform a drawing operation and a thrust operation incidental to the drawing operation; detector means disposed around the coordinate plane for receiving the light projected from the pointing tool and for converting the received light into an electric signal; processor means for processing the electric signal fed from the detector means to compute coordinates representing the position of the pointing tool; and a light source for providing an illumination light over the coordinate plane so that the detector means receives the light which is passively projected from the pointing tool by reflection of the illumination light; wherein the light source intermittently turns on and off to provide a flashing illumination light while cyclically changing a color of the flashing illumination light, wherein the pointing tool has a surface color variable in response to the thrust operation, wherein the detector means receives the light reflected by the pointing tool having the variable surface color so that the electric signal cyclically varies in dependence on the variable surface color of the pointing tool, and wherein the processor means processes the electric signal so as to detect the thrust operation as well as to compute the position of the pointing tool during the drawing operation.

Claim 26

An optical digitizer comprising: a pointing tool projecting a light and being manipulated on a coordinate plane to perform a drawing operation and a thrust operation incidental to the drawing operation; detector means disposed around the coordinate plane for receiving the light projected from the pointing tool and for converting the received light into an electric signal; processor means for processing the electric signal fed from the detector means to compute coordinates representing the position of the pointing tool; and a light source for providing an illumination light over the coordinate plane so that the detector means receives the light which is passively projected from the pointing tool by reflection of the illumination light; wherein the light source intermittently turns on and off to provide a flashing illumination light while cyclically changing a color of the flashing illumination light, wherein the pointing tool has a surface color variable in response to the thrust operation, wherein the detector means receives the light reflected by the pointing tool having the variable surface color so that the electric signal cyclically varies in dependence on the variable surface color of the pointing tool, and wherein the processor means processes the electric signal so as to detect the thrust operation as well as to compute the position of the pointing tool during the drawing operation.

Claim 27

A display apparatus for determining a position of a pointing object which projects a light and which is disposed on a coordinate plane and for coincidentally displaying the position of the pointing object on the coordinate plane, the display apparatus comprising: detector means disposed on a periphery of the coordinate plane and having a field of view covering the coordinate plane for receiving the light projected by the pointing object and for converting the received light into a corresponding electric signal; processor means for processing the electric signal output by the detector means to compute coordinates representing the position of the pointing object on the coordinate plane; collimator means disposed to limit a vertical width of the field of view of the detector means below a predetermined height relative to the coordinate plane such that through the limited field of view the detector means can receive a parallel component of the light which is projected from the pointing object substantially in parallel to the coordinate plane; a light source for producing a varying color illumination light over the coordinate plane, so that the detector means receives the light which is projected by the pointing object by reflection of the illumination light; wherein the detector means receives the light reflected by the pointing object, which has a particular surface color, so that the electrical signal varies in accordance with the particular surface color of the pointing object, and the processor means processes the electric signal so as to discriminate the particular surface color of the pointing object as well as to compute the position of the pointing object; shield means disposed to enclose the periphery of the coordinate plane and having a vertical width sufficient to block noise comprising light other than the projected light from entering into the limited field of view of the detector means; a display panel mounted to define a screen in superposed relation to the coordinate plane; and output means for displaying the position of the pointing object on the screen according to the computed coordinates.

Claim 28

A display apparatus for determining a position of a pointing object which projects a light and which is disposed on a coordinate plane and for coincidentally displaying the position of the pointing object on the coordinate plane, the display apparatus comprising: detector means disposed on a periphery of the coordinate plane and having a field of view covering the coordinate plane for receiving the light projected by the pointing object and for converting the received light into a corresponding electric signal; processor means for processing the electric signal output by the detector means to compute coordinates representing the position of the pointing object on the coordinate plane; collimator means disposed to limit a vertical width of the field of view of the detector means below a predetermined height relative to the coordinate plane such that through the limited field of view the detector means can receive a parallel component of the light which is projected from the pointing object substantially in parallel to the coordinate plane; a light source for producing a varying color illumination light over the coordinate plane, so that the detector means receives the light which is projected by the pointing object by reflection of the illumination light; wherein the detector means receives the light reflected by the pointing object, which has a particular surface color, so that the electrical signal varies in accordance with the particular surface color of the pointing object, and the processor means processes the electric signal so as to discriminate the particular surface color of the pointing object as well as to compute the position of the pointing object; shield means disposed to enclose the periphery of the coordinate plane and having a vertical width sufficient to block noise comprising light other than the projected light from entering into the limited field of view of the detector means; a display panel mounted to define a screen in superposed relation to the coordinate plane; and output means for displaying the position of the pointing object on the screen according to the computed coordinates.

Claim 29

A display apparatus for determining a position of a pointing object which projects a light and which is disposed on a coordinate plane and for coincidentally displaying the position of the pointing object on the coordinate plane, the display apparatus comprising: detector means disposed around the coordinate plane and having a field of view covering the coordinate plane for receiving the light projected by the pointing object and for converting the received light into a corresponding electric signal; processor means for processing the electric signal output by the detector means to compute coordinates representing the position of the pointing object on the coordinate plane; a display panel mounted to define a screen in superposed relation to the coordinate plane; output means for displaying the position of the pointing object on the screen according to the computed coordinates; collimator means disposed to limit the field of view of the detector means below a predetermined height relative to the coordinate plane such that through the limited field of view the detector means can receive only a parallel component of the light which is projected from the pointing object substantially in parallel to the coordinate plane; and a light source for producing a varying color illumination light over the coordinate plane so that the detector means receives the light which is projected by the pointing object by reflection of the illumination light; wherein the detector means receives the light reflected by the pointing object, which has a particular surface color, so that the electrical signal varies in accordance with the particular surface color of the pointing object, and the processor means processes the electric signal so as to discriminate the particular surface color of the pointing object as well as to compute the position of the pointing object; wherein the detector means comprises a pair of linear image sensors for receiving the projected light at different directions to produce electric signals representing a pair of one-dimensional images of the pointing object; wherein the processor means processes the one-dimensional images to compute two-dimensional coordinates of the position of the pointing object; wherein the collimator means comprises a collimator lens for converging only the parallel component of the projected light onto a receiving surface of the linear image sensor; wherein the collimator lens has a flat bottom face, a flat top face and a curved lens face between the flat bottom face and the flat top face so that an optical axis of the collimator lens aligns parallel to the coordinate plane when the flat bottom face of the collimator lens is placed in contact with the coordinate plane; and further comprising optical means having at least one of a reflector and a refractor disposed in an optical path between the collimator lens mounted on the coordinate plane and the linear image sensor mounted above the coordinate plane for directing the light collected by the collimator lens to the linear image sensor.

Claim 30

A display apparatus for determining a position of a pointing object which projects a light and which is disposed on a coordinate plane and for coincidentally displaying the position of the pointing object on the coordinate plane, the display apparatus comprising: detector means disposed around the coordinate plane and having a field of view covering the coordinate plane for receiving the light projected by the pointing object and for converting the received light into a corresponding electric signal; processor means for processing the electric signal output by the detector means to compute coordinates representing the position of the pointing object on the coordinate plane; a display panel mounted to define a screen in superposed relation to the coordinate plane; output means for displaying the position of the pointing object on the screen according to the computed coordinates; collimator means disposed to limit the field of view of the detector means below a predetermined height relative to the coordinate plane such that through the limited field of view the detector means can receive only a parallel component of the light which is projected from the pointing object substantially in parallel to the coordinate plane; and a light source for producing a varying color illumination light over the coordinate plane so that the detector means receives the light which is projected by the pointing object by reflection of the illumination light; wherein the detector means receives the light reflected by the pointing object, which has a particular surface color, so that the electrical signal varies in accordance with the particular surface color of the pointing object, and the processor means processes the electric signal so as to discriminate the particular surface color of the pointing object as well as to compute the position of the pointing object; wherein the detector means comprises a pair of linear image sensors for receiving the projected light at different directions to produce electric signals representing a pair of one-dimensional images of the pointing object; wherein the processor means processes the one-dimensional images to compute two-dimensional coordinates of the position of the pointing object; wherein the collimator means comprises a collimator lens for converging only the parallel component of the projected light onto a receiving surface of the linear image sensor; wherein the collimator lens has a flat bottom face, a flat top face and a curved lens face between the flat bottom face and the flat top face so that an optical axis of the collimator lens aligns parallel to the coordinate plane when the flat bottom face of the collimator lens is placed in contact with the coordinate plane; and further comprising optical means having at least one of a reflector and a refractor disposed in an optical path between the collimator lens mounted on the coordinate plane and the linear image sensor mounted above the coordinate plane for directing the light collected by the collimator lens to the linear image sensor.

Claim 31

A display apparatus for determining a position of a pointing object which projects a light and which is disposed on a coordinate plane and for coincidentally displaying the position of the pointing object on the coordinate plane, the display apparatus comprising: detector means disposed around the coordinate plane and having a field of view covering the coordinate plane for receiving the light projected by the pointing object and for converting the received light into an electric signal; processor means for processing the electric signal output by the detector means to compute coordinates representing the position of the pointing object on the coordinate plane; a display panel mounted to define a screen in superposed relation to the coordinate plane; output means for displaying the position of the pointing object on the screen according to the computed coordinates; and collimator means disposed to limit the field of view of the detector means below a predetermined height relative to the coordinate plane such that through the limited field of view the detector means can receive a parallel component of the light which is projected by the pointing object substantially in parallel to the coordinate plane; and a light source for producing a varying color illumination light over the coordinate plane so that the detector means receives the light which is projected by the pointing object by reflection of the illumination light; wherein the detector means receives the light reflected by the pointing object, which has a particular surface color, so that the electrical signal varies in accordance with the particular surface color of the pointing object, and the processor means processes the electric signal so as to discriminate the particular surface color of the pointing object as well as to compute the position of the pointing object; wherein the collimator means comprises a collimator lens for converging only the parallel component of the projected light onto a receiving surface of the detector means; wherein the collimator lens has an optical axis vertical with respect to the coordinate plane; and further comprising reflector means disposed on the coordinate plane for reflecting the parallel component of the projected light vertically with respect to the collimator lens.

Claim 32

A display apparatus for determining a position of a pointing object which projects a light and which is disposed on a coordinate plane and for coincidentally displaying the position of the pointing object on the coordinate plane, the display apparatus comprising: detector means disposed around the coordinate plane and having a field of view covering the coordinate plane for receiving the light projected by the pointing object and for converting the received light into an electric signal; processor means for processing the electric signal output by the detector means to compute coordinates representing the position of the pointing object on the coordinate plane; a display panel mounted to define a screen in superposed relation to the coordinate plane; output means for displaying the position of the pointing object on the screen according to the computed coordinates; and collimator means disposed to limit the field of view of the detector means below a predetermined height relative to the coordinate plane such that through the limited field of view the detector means can receive a parallel component of the light which is projected by the pointing object substantially in parallel to the coordinate plane; and a light source for producing a varying color illumination light over the coordinate plane so that the detector means receives the light which is projected by the pointing object by reflection of the illumination light; wherein the detector means receives the light reflected by the pointing object, which has a particular surface color, so that the electrical signal varies in accordance with the particular surface color of the pointing object, and the processor means processes the electric signal so as to discriminate the particular surface color of the pointing object as well as to compute the position of the pointing object; wherein the collimator means comprises a collimator lens for converging only the parallel component of the projected light onto a receiving surface of the detector means; wherein the collimator lens has an optical axis vertical with respect to the coordinate plane; and further comprising reflector means disposed on the coordinate plane for reflecting the parallel component of the projected light vertically with respect to the collimator lens.

Claim 33

A display apparatus for determining a position of a pointing object which projects a light and which is disposed on a coordinate plane and for coincidentally displaying the position of the pointing object on the coordinate plane, the display apparatus comprising: detector means disposed around the coordinate plane for receiving the light projected by the pointing object and for converting the received light into an electric signal; processor means for processing the electric signal output by the detector means to compute coordinates representing the position of the pointing object; a display panel mounted to define a screen in superposed relation to the coordinate plane; output means for displaying the position of the pointing object on the screen according to the computed coordinates; and a light source for producing a varying color illumination light over the coordinate plane so that the detector means receives the light which is passively projected by the pointing object by reflection of the illumination light; wherein the detector means receives the light reflected by the pointing object, which has a particular surface color, so that the electrical signal varies in accordance with the particular surface color of the pointing object; wherein the light source intermittently turns on and off to provide a flashing illumination light, and the processor means processes the electric signal which is output by the detector means in synchronization with the flashing illumination light so as to discriminate the particular surface color of the pointing object and to compute the position of the pointing object illuminated by the light source.

Claim 34

A display apparatus for determining a position of a pointing object which projects a light and which is disposed on a coordinate plane and for coincidentally displaying the position of the pointing object on the coordinate plane, the display apparatus comprising: detector means disposed around the coordinate plane for receiving the light projected by the pointing object and for converting the received light into an electric signal; processor means for processing the electric signal output by the detector means to compute coordinates representing the position of the pointing object; a display panel mounted to define a screen in superposed relation to the coordinate plane; output means for displaying the position of the pointing object on the screen according to the computed coordinates; and a light source for producing a varying color illumination light over the coordinate plane so that the detector means receives the light which is passively projected by the pointing object by reflection of the illumination light; wherein the detector means receives the light reflected by the pointing object, which has a particular surface color, so that the electrical signal varies in accordance with the particular surface color of the pointing object; wherein the light source intermittently turns on and off to provide a flashing illumination light, and the processor means processes the electric signal which is output by the detector means in synchronization with the flashing illumination light so as to discriminate the particular surface color of the pointing object and to compute the position of the pointing object illuminated by the light source.

Claim 35

A display apparatus comprising: a pointing tool projecting a light and being manipulated along a coordinate plane to perform a drawing operation and an incidental operation associated to the drawing operation; detector means disposed around the coordinate plane for receiving the light projected from the pointing tool and for converting the received light into an electric signal; processor means for processing the electric signal fed from the detector means to compute coordinates representing the position of the pointing tool; a display panel mounted to define a screen in superposed relation to the coordinate plane; and output means for displaying the position of the pointing tool on the screen according to the computed coordinates; wherein the pointing tool has modulating means responsive to the incidental operation for varying color components contained in the projected light, wherein the detector means outputs the electric signal according to the color components contained in the projected light, and wherein the processor means processes the electric signal so as to obtain information of the incidental operation as well as to compute the position of the pointing tool during the drawing operation.

Claim 36

A display apparatus comprising: a pointing tool projecting a light and being manipulated along a coordinate plane to perform a drawing operation and an incidental operation associated to the drawing operation; detector means disposed around the coordinate plane for receiving the light projected from the pointing tool and for converting the received light into an electric signal; processor means for processing the electric signal fed from the detector means to compute coordinates representing the position of the pointing tool; a display panel mounted to define a screen in superposed relation to the coordinate plane; and output means for displaying the position of the pointing tool on the screen according to the computed coordinates; wherein the pointing tool has modulating means responsive to the incidental operation for varying color components contained in the projected light, wherein the detector means outputs the electric signal according to the color components contained in the projected light, and wherein the processor means processes the electric signal so as to obtain information of the incidental operation as well as to compute the position of the pointing tool during the drawing operation.

Claim 37

A display apparatus comprising: a pointing tool projecting a light and being manipulated on a coordinate plane to perform a drawing operation and a thrust operation incidental to the drawing operation; detector means disposed around the coordinate plane for receiving the light projected from the pointing tool and for converting the received light into an electric signal; processor means for processing the electric signal fed from the detector means to compute coordinates representing the position of the pointing tool; a display panel mounted to define a screen in superposed relation to the coordinate plane; output means for displaying the position of the pointing tool on the screen according to the computed coordinates; and a light source for providing an illumination light over the coordinate plane so that the detector means receives the light which is passively projected from the pointing tool by reflection of the illumination light; wherein the light source intermittently turns on and off to provide a flashing illumination light while cyclically changing a color of the flashing illumination light, wherein the pointing tool has a surface color variable in response to the thrust operation, wherein the detector means receives the light reflected by the pointing tool having the variable surface color so that the electric signal cyclically varies in dependence on the variable surface color of the pointing tool, and wherein the processor means processes the electric signal so as to detect the thrust operation as well as to compute the position of the pointing tool during the drawing operation.

Claim 38

A display apparatus comprising: a pointing tool projecting a light and being manipulated on a coordinate plane to perform a drawing operation and a thrust operation incidental to the drawing operation; detector means disposed around the coordinate plane for receiving the light projected from the pointing tool and for converting the received light into an electric signal; processor means for processing the electric signal fed from the detector means to compute coordinates representing the position of the pointing tool; a display panel mounted to define a screen in superposed relation to the coordinate plane; output means for displaying the position of the pointing tool on the screen according to the computed coordinates; and a light source for providing an illumination light over the coordinate plane so that the detector means receives the light which is passively projected from the pointing tool by reflection of the illumination light; wherein the light source intermittently turns on and off to provide a flashing illumination light while cyclically changing a color of the flashing illumination light, wherein the pointing tool has a surface color variable in response to the thrust operation, wherein the detector means receives the light reflected by the pointing tool having the variable surface color so that the electric signal cyclically varies in dependence on the variable surface color of the pointing tool, and wherein the processor means processes the electric signal so as to detect the thrust operation as well as to compute the position of the pointing tool during the drawing operation.