Data processing: measuring – calibrating – or testing – Measurement system – Dimensional determination
Reexamination Certificate
1998-11-05
2002-01-15
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Dimensional determination
C345S156000, C345S157000, C345S158000, C345S173000, C345S183000
Reexamination Certificate
active
06339748
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a coordinate input system for imparting a digitizer function, i.e., a positional coordinate input function to a transmissive screen for image display such as a rear projection display apparatus, and a display apparatus using such a coordinate input system.
2. Description of Related Art
Recent diffusion of personal computers and projecting display apparatuses using a liquid crystal, a light bulb or a CRT is bringing about a common practice of presentation of electronic image information in the form of an enlarged projected image. If a positional instructing operation can be carried out directly on an image displaying screen, the presenter could operate a computer without leaving the screen position, and it would be possible to enter handwritten characters directly onto the screen, thus permitting an effective and efficient presentation. There are therefore developed methods for positional coordinate input on a screen.
An example of such methods for positional coordinate input on a transmissive screen for image display is the one disclosed in Japanese Unexamined Patent Publication No. 60-230,228. This method has a configuration as shown in FIG.
16
. In this method, positional coordinates of a light emitting indicator 101 such as a light pen is determined by detecting an invisible ray spot such as an infrared ray spot projected from the light emitting indicator by means of a positional detector 103 such as a Position Sensitive Light Detector (PSD) provided behind a transmissive screen 102, together with a projecting tube 104 which is an image projector forming an image from an image ray onto the transmissive screen 102.
However, the light emitting indicator 101 such as a light pen must have a light emitting diode (LED) serving as a light source, a control circuit and a cell incorporated therein, leading to a larger size and a heavier weight. This method therefore has a problem in that, when an operator enters a positional instruction or handwritten characters onto the transmissive screen 102 with the light emitting indicator 101 in hand, handling is more difficult than in handling writing means such as a pen.
The present invention has therefore an object to achieve a coordinate input system easy to handle on a transmissive screen and a display apparatus provided with such a coordinate input system.
DISCLOSURE OF THE INVENTION
(1) The coordinate input system of the present invention, imparting a coordinate input function to a transmissive screen which forms an image from an image ray projected by image ray projecting means, comprising: infrared ray projecting means which projects infrared ray to a back of the transmissive screen; image sensing means which picks up the infrared ray reflected by indicating means provided with reflecting means in front of the transmissive screen, from the back of the transmissive screen; and image information processing means which determines coordinates on the transmissive screen as specified by the instructing means from an output image signal provided as an output by the image sensing means.
According to the aforementioned configuration, the instructing means is required to be provided only with a function of reflecting a ray, thus eliminating the need to incorporate a cell or electronic components. It is possible, for example, to adopt a configuration in which a reflecting member is provided at the tip of a shape similar to that of ordinary writing means such as a pen. It is thus possible to achieve a shape and a weight substantially identical with those of the ordinary writing means, and provide an advantage of easiness to use by an operator without any uncomfortable sense.
(2) In the coordinate input system of the invention as described in (1) above, a projection optical axis of the infrared projecting means does not cross the plane of the transmissive screen at right angles.
According to the configuration described above, the optical axis of the reflected ray from the back of the transmissive screen of the projected infrared ray from the infrared ray source, i.e., the maximum intensity direction has an angle with a direction at right angles to the plane of the screen. As a result, when the incident optical axis of the image sensing means is at right angles to the plane of the screen, the amount of incidence of the rear reflected infrared ray into the image sensing means becomes smaller, and this brings about an advantage of improving the S/N ratio (signal
oise ratio) of the detecting system.
(3) In the coordinate input system of the invention as described in (1) above, the optical axis of the image sensing means does not cross the plane of the transmissive screen at right angles.
According to the above-mentioned configuration, when the optical axes of the reflected ray from the screen back of the infrared ray source and the reflected ray from the screen back of the image ray for image display are at right angles to the plane of the screen, the amount of incidence of these reflected ray to the image sensing means becomes smaller, and this provides an advantage of an improved S/N ratio of the detecting system.
(4) In the coordinate input system of the invention as described in (1) above, the infrared projecting means comprises a plurality of infrared ray sources which project infrared ray to different areas of the back of the transmissive screen.
According to the aforementioned configuration, as compared with projection of an infrared ray to the back of the transmissive screen by the use of a single infrared ray source, it is possible to project the infrared ray uniformly over the entire back surface of the transmissive screen, thus providing an advantage of an improved S/N ratio of the detecting system.
(5) In the coordinate input system of the invention as described in (4) above, projection optical axes of the plurality of infrared ray sources do not cross the plane of the transmissive screen at right angles, and the angles of incidence of the projection optical axes of the plurality of infrared ray sources with the plane of the transmissive screen are different from each other.
According to the foregoing configuration, it is possible to make settings so that the incidence is diagonal as far as possible by using a different angle of incidence for each infrared ray source between the projection optical axes of the plurality of infrared ray sources and the plane of the transmissive screen. It is therefore possible to cause the maximum intensity distribution of the rear reflected ray from the transmissive screen of the ray projected from the infrared ray source to have a large angular difference to a direction at right angles to the transmissive screen. The optical axis of the image sensing means should on the other hand be at right angles in general to the plane of the transmissive screen so that the trapezoidal distortion is not generated in the sense image. As a result, the amount of incidence of the rear reflected ray on the transmissive screen of the infrared ray source can be reduced, and this results in an advantage of an improved S/N ratio of the detecting system.
(6) In the coordinate input system of the invention as described in (1) above, reflecting means of the indicating means comprises a reflective member having selectivity of infrared rays.
According to the configuration as described above, reflection of ray other than the infrared ray by the ray reflecting indicator can be inhibited. It is therefore possible to prevent reflection of image ray projected onto the transmissive screen not pertinent to the positional detection, thus permitting improvement of the S/N ratio of the detecting system.
(7) In the coordinate input system of the invention as described in (1) above, the reflecting means of the indicating means comprises an optical filter selectively allowing transmission of the infrared ray and an optical reflective member.
According to the aforementioned configuration, the advantage of inhibiting reflection of light other than the infrared ra
Hoff Marc S.
Seiko Epson Corporation
Vo Hien
LandOfFree
Coordinate input system and display apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Coordinate input system and display apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Coordinate input system and display apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2857763