Brightpen/pad II

Abstract

A scanning and digitizing device where the same photodetectors are used in a scanning mode and in a digitizing mode. In the scanning mode graphic information is scanned. In the digitizing mode coordinate positions of a stylus is determined. The photodetectors are used in the imaging portion of this device which imaging portion is a rangefinder in the digitizing mode.

A combination scanning and digitizing device is described in which the same photodetectors are cooperatively used to scan graphic information on paper or other planar material and also to determine the position of a stylus. Stylus position detection is by means of a rangefinder.

Description

This is a continuation in part of application Ser. No. 07/046,722 filed 5/7/87, now U.S. Pat. No. 4,949,079 patented on 8/14/90, which is a continuation in part of application Ser. No. 06/725,126, filed on 4/19/85, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to the device taught in light emitting stylus, or alternately, a light absorbing stylus such as a finger. The position is converted into binary coded electronic signals suitable for transmission to a computer or other apparatus. The configuration of the photodetectors is such that the detectors used to determine the position of the stylus can also be used to digitize graphic information contained on a sheet of paper or like surface. Alternately, the invention can be considered a device to digitize graphic information on sheets of paper planar material that is also capable of determining the coordinate position of light emitting or absorbing styli a stylus. It should be noted that this invention is related to the one in application Ser. No. 07/046,722, and that the electronic components to be incorporated in this invention are identical to those shown in that invention.

FIG. 1 shows the preferred embodiment of the device. A stylus 11 is capable of moving over a first planar surface on which it is desired to indicate X, Y coordinates. The said first surface 1 may be the video output of a computer such a LCD, CRT, plasma, or other output device although this is not necessary. Surrounding the said first flat surface 1 are light emitters 13. Also shown in FIG. 1 is a planar surface, here a sheet of paper 7 being moved by rollers 9 between guides 14 and 15. The paper 7 is being illuminated by lamp 8. FIG. 1 shows the simultaneous use of a stylus to indicate position, and a piece of paper on which graphic information is to be scanned. It should be understood that in normal operation, one but not both would be present. FIG. 19 1 shows both only to convey an understanding of the relative locations of the paper, stylus, etc., in the preferred embodiment.

FIGS. 2A and 2B show more clearly how the same photodetector 5 can be used to both determine the position of a stylus and to scan graphic information. FIG. 2A shows a light emitting stylus 11. Light from the stylus, shown here as a dash, strikes first mirrors 2 and thence passes through imaging systems 3, slits or pinholes and is reflected off second mirrors 4 to land upon photodetector 5. The two images of the stylus are represented by vertical solid lines on the photodetector. Persons versed in the art will recognize that this imaging system is in fact a range finder rangefinder. In the common use of a rangefinder, the distance of the object is determined by rotating the front mirrors until the 2 two images become superimposed. In the preferred embodiment of this invention, the distance is determined by elementary trigonometry or table lookup by the separation between the images. However, it would be possible to place first mirrors 2 upon a pivot and use means such stepper motors or piezoelectric linear actuators to rotate said first mirrors under control of the computer until a single image is formed.

In a like manner, the lateral position of the stylus is determined by well know known trigonometric formulae, although a table lookup can be used if speed is essential. The distance and lateral position of the stylus indicate the X, Y coordinates. It should be noted that the imaging system in FIG. 2A is a slit (or alternatively a pine pin hole) since the depth of field for these are essentially infinite. Lenses may be used if they have a sufficient depth of field, since all that is needed is the centroid of the images. Also, although a light emitting stylus is shown in FIG. 2A, a light absorbing stylus can be used. In this case, the image formed on the photodetector will be the shadow cast by the stylus formed by its interposition of the stylus between light emitters (not shown in this figure) and the photodetector 5 via the optical path front mirrors 2, slits 3 and second mirrors 4.

First mirrors 2 are shown as optically flat in this and other figures. It may desirable to make them convex so that they minify the view of the field 1.

FIG. 2B shows the imaging system for scanning graphic information. Here, the slit 3 and the second mirrors 4 have rotated down beneath the field, and lens 6 has swung into position. Light from the sheet of paper is focused by lens 6 is focused on photodetector 5.

FIGS. 3A and 3B show more clearly how the elements described are situated and operate. In FIG. 3A a finger 16 represents a light absorbing stylus. Lamp 8 is on, illuminating paper guides 14 and 15, which are typically to be white, and hence reflective. Light is reflected from the guides 14 and 15 onto mirror 10 and thence toward mirrors 2 (not shown). Sail Said light is intercepted by finger 16. If It should be understood that for the apparatus to work with a light absorbing stylus, illumination must be present on three sides of the field 1. In patent application 07/046,722 U.S. Pat. No. 4,949,079, this was achieved in the preferred embodiment by the presence of lamps on three sides. Here, the paper guides in conjunction with the lamp 8 used for scanning and the mirror 10 used for scanning, can perform this function for one side. It is also possible, of course, to use a third, retractable, lamp if so desired. FIGS. 3A and 3B show how the lens 6 and the mirrors 4 (not shown) and optical slits 3 can rotate around pivot 12. In FIG. 3B the lens 6 is in a position to image one line of graphic material found on paper 7. Paper, 7, is illuminated by lamp 8, while being transported by rollers 9. Practitioners versed in the art will understand that as the rollers 9 transport paper 7 laterally, successive rows of pixels on said paper 7 will be digitized. As in patent application Ser. No. 07/046,722 U.S. Pat. No 4,949,079, the rollers can be rotated by stepper motors under the control of the computer, or manually by the user. If the latter system is used, timing tracks on the rollers will suffice to indicate relative motion of the paper. Both techniques are well known to practitioners in the art.

The rotation of the lens 6 and mirrors 4 around pivot 12 can be effected by the computer via control of a stepper motor, or they can be rotated manually by the user.

Although the preferred embodiment shown here has the lens 6 and mirrors 4 located at substantially the same distance from the photodetectors 5 this is not necessary for proper operation of the apparatus. All that is necessary is means to provide alternative optical paths to the photodetector 5 depending on the desired mode of the apparatus.

The photodetectors 5 shown in this disclosure are well known to practitioners in the art and are readily available as components of scanners and facsimile devices. They incorporate the appropriate circuitry (typically analog to digital circuits) to prepare a signal suitable for input into computers and the like. This application teaches that any such photo responsive component capable of resolving an image and of generating a signal which can be input into a computer can be used for the dual purpose of scanning graphic material on planar surfaces and also to determine the position of a stylus. All that is needed is appropriate methods of imaging both on the said photo responsive signal generator.

Claims

1. An apparatus for digitizing graphic information on sheets of paper planar material comprising photodetectors and in an imaging systems capable of imaging graphic information on said sheets of paper planar material, and which said photodetectors are also cooperatively used to digitize the coordinate position of a light emitting stylus or light absorbing stylus by rangefinding means of converting analog signals from said photodetectors to digital for imaging said stylus on said photodetectors and means for generating signals from said photodetectors suitable for input into a computer or the like.

2. An apparatus according to claim 1 in which said photodetectors are capable of digitizing the coordinate position of the stylus by means of systems capable of forming images of the stylus on the said photodetectors and the means of imaging graphic information on said sheets of paper planar material is by means of for imaging successive lines of information on said sheets of paper planar material by means of transporting said sheets of paper.

3. An apparatus according to claim 2 in which the means for forming said images of stylus indicating X, Y, coordinate

position of said stylus consists of a rangefinder.4. An apparatus according to claim 3 1 consists of in which said rangefinding means for imaging said stylus on said photodetectors comprises means for acquiring separate views of said stylus, means for forming images of said separate views, and means

for projecting said images upon said photodetectors. 5. An apparatus according to claim 4 in which means for acquiring separate views consists

of mirrors. 6. An apparatus according to claim 4 in which means for

forming said images are slits. 7. An apparatus according to claim 4 in

which means for forming said images are pinholes. 8. An apparatus according to claim 1 in which the photodetector consists of a CCD detector

array. 9. An apparatus according to claim 1 in which the photodetector

consists of a vidicon tube. 10. An apparatus according to claim 1 in which the photodetector consists of an array of photoelectric cells.