AU8109887A - Computer input device - Google Patents

Description

"COMPUTER INPUT DEVICE" The present invention relates to a handheld computer input device for allowing handwritten characters to be converted into machine readable form and relates particularly, although not exclusively, to a handwriting instrument that can be coupled to the input of a computer.

In the past, handwriting recognition devices have consisted of a handheld wand or stylus which is connected to a so-called "digitizing tablet". The wand or stylus is pressed onto the tablet and the x,y posi¬ tion of the wand or stylus on the tablet is detected by its proximity or contact with horizontal and vertical multiplexed grids within the tablet. By accurately positioning a preprinted form on the tablet, the wand or stylus can be moved over the form and the desired characters drawn on the form. The sensed x,y co¬ ordinates generated by successive positions of the pen are stored and the actual handwritten characters are computed from the stored co-ordinates by suitable character recognition software. Devices of this type are shown in Australian Patent Application No. 25935/78.

The problem with these devices is that they are not really portable and the wand or stylus must be coupled to the tablet. As the tablet has limited dimensions there is a physical limit on the amount of characters that can be written on a preprinted form. Preprinted forms must often be accurately aligned with the tablet. In addition, many of the prior art digiti¬ zing tablets require characters to be written in a particular manner and/or within predefined borders.

Several solutions to these problems were described in International Patent Application No. PCT/AU86/00020 (now Australian Patent Application No. 53916/86) the contents of which are incorporated herein. In the preferred embodiments described in 53916/86 movement in eight directions was sensed and a handwritten character was decoded by computational means in response to the variations in change of direc¬ tions of the writing tip.

The present invention provides improvements to the direction sensing of the handwriting device disclosed in 53916/86. It is an object of the present invention to provide a handwriting instrument which requires no digitizing tablet for computer input.

A further object of the invention is to pro¬ vide a handwriting instrument capable of simultaneously producing handwritten copy on any suitable writing surface and storage within a computer memory device.

A still yet further object is to alleviate, to a substantial degree, the writing of characters in a particular manner. With these objects in view the present inven¬ tion may provide a computer input device for converting handwritten characters into machine readable form, said device including means for detecting or sensing direc¬ tion of movement of said device across a writing surface.

Preferably said device includes a writing tip e.g. pencil or felt tip; or alternatively a nib or ball supplied with ink from a reservoir.

In one preferred embodiment said reservoir is suspended or held such that the writing tip can move with respect to a barrel of said computer input device, said movement being detected by variation of an impe¬ dance, reactance or transducer coupled to said reser¬ voir. Preferably two variable reactances at right angles to one another respond to the movement of said reservoir with said reactances being in respective tuned circuits to allow measurement of the direction changes.

In one especially preferred embodiment said reactances are inductors having ferrite tuning slugs movable within the coil with jsaid slugs being coupled to said reservoir. The output from said tuned circuits can be fed to respective A-to-D converters for inter¬ pretation by computational means. If a self-contained device is required the device may include computational means for determining the handwritten characters from analysis of said direc¬ tions. The device may also include memory means for storing text translated by said computational means. These and other objects and aspects of the present invention will be more fully described with reference to the preferred non-limitative embodiments shown in the accompanying drawings, in which:-

Fig. 1 is a longitudinal cross-sectional view of a first embodiment of a handwriting instrument made in accordance with the invention;

Fig. 2 is a cross-sectional view along and in the direction of arrows 2-2 of Fig. 1;

Fig. 3 is a longitudinal cross-sectional view of a second embodiment of a handwriting instrument made in accordance with the invention; and

Fig. 4 is a cross-sectional view along and in the direction of arrows 4-4 of Fig. 3.

Turning to Figs. 1 and 2 there is shown a pen 10 which has a main barrel 12. At the rear of pen 10 is a plug 14 to close off the end. An ink reservoir 16 having ball point 18 is secured inside pen 10 by a plug 20. Plug 20 is formed of resilient material e.g. sil- icone rubber so that ink reservoir 16 may be deflected angularly and/or vertically. At the end of the ink reservoir opposite to ball point 18 is a housing 22 for supporting inductors 24, 26 mounted at right angles to one another. In this embodiment the inductors are secured in housing 22. Centrally located on housing 22 is a hollow tubular section 28 which restricts movement of reservoir 16 in all directions. Coupled to tubular section 28 are ferrite slugs 34, 36. Slugs 34, 36 are a loose fit within inductors 24, 26 and move in and out of the inductors with movement of ball point 18. This movement varies the inductance of the coils 30, 32 of inductors 24, 26 which can be measured by having the inductors in respective tuned circuits (not shown). By coupling the tuned circuits to respective analog-to- digital converters (not shown) the x,y co-ordinates of the reservoir 16 relative to the main barrel 12 can be computed. This type of interfacing is familiar to the man skilled in the art and requires no further explana¬ tion.

Pen 10 may include switches 38 for detecting when the pen is in the writing position. An example of using such switches is shown in Figs. 9 and 11 of Australian Patent Application No. 53916/86. If desired the switch contacts could be replaced by other suitable means e.g. magnetic or opto-sensitive devices. In use the ink reservoir 16 is free to pivot as the pen is used and this pivotting action will cause slugs 34, 36 to move in and out of inductors 24, 26 to produce varying outputs to indicate the change in di¬ rection of the pen movement. As the inductors are in tuned circuits the changes in direction will result in changes in voltage which can be measured by the analog- to-digital converters. Accordingly x,y co-ordinates can be continually sampled for monitoring by a computer (not shown). The computer may convert the co-ordinates for use with the software described in 53916/86 with reference to Figs. 12 and 13. Another suitable method is to monitor the amplitudes and period of the output from each tuned circuit and their relationship with the handwritten character. It has been found that this relationship can provide a high degree of correct recognition of characters.

Turning now to Figs. 3 and 4 there is shown a writing instrument or pen 50 which has a main outer barrel 52. Outer barrel 52 is slipped or moulded over an inner barrel 54. At the rear of pen 50 is a plug 56 to close off barrels 52 and 54. A metal ink reservoir 58 having ball point 60 is secured into plug 56 with the ink reservoir free to be deflected from its verti¬ cal position. Mounted along inner barrel 54 are four capacitor plates 62. As shown the capacitor plates 62 extend along barrel 54 and are coupled to contact pins 64 at the rear of pen 50. A pin 66 is also provided for the ink reservoir 58.

Capacitor plates 62 are equispaced about reservoir 58. Accordingly when writing with pen 50 the pivotting action of reservoir 58 will cause the capaci¬ tance of each capacitor formed by plates 62 and reser¬ voir 58 to vary. Again each capacitor would be inclu¬ ded in a tuned circuit coupled to an analog-to-digital converter. The software would be similar to that dis¬ cussed with reference to Figs. 1 and 2.

From the above it is clear that the four capacitor plates 62 can be replaced by two plates in an arrangement similar to that of inductors 24, 26 of Figs. 1 and 2. The suspension point for the writing tip of the devices can be remote from the tip (as in. Figs. 3 and 4) or adjacent the tip (as in Figs. 1 and 2). Although reactances have been described as the direction sensing elements it is clear that these could be replaced by alternative transducers. Other suitable sensors would be piezoelectric crystals and strain gauges.

The major advantage of the preferred embodi¬ ments over the embodiments shown in 53916/86 are that the movement of the writing tip can be determined regardless of the angle the device is when writing. In the previous embodiments the device had to be kept sub¬ stantially vertical.

From the above it is clear that the table entries may be personalized to an individual allowing peculiarities in writing to be accommodated. It is also possible to have several different entries for the same character. Experimentation has shown that the software can detect characters fairly accurately, once fine-tuned to an individual's writing style. The invention has particular application for oriental type scripts.

It is believed that the invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts and that changes may be made in the form, construction and arrangement of the input device described without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore descri¬ bed being merely preferred embodiments thereof.

Claims (8)

CLAIMS -7-

1. A computer input device for converting hand¬ written characters into machine readable form, said device including means for detecting or sensing direc¬ tion of movement of said device across a writing surface.

2. The computer input device of claim 1, further incuding a writing tip.

3. The computer input device of claim 1, further including a nib or ball supplied with ink from a reservoir.

4. The computer input device of claim 3, wherein said reservoir is suspended or held such that the writing tip can move with respect to a barrel of said computer input device, said movement being detected by variation of an impedance, reactance or transducer

^coupled to said reservoir.

5. The computer input device of claim 4, wherein at least two variable reactances at right angles to one another respond to the movement of said reservoir with said reactances being in respective tuned circuits to allow measurement of the direction changes.

6. The computer input device of claim 5, wherein said reactances are inductors having ferrite tuning slugs movable within the coil with said slugs being coupled to said reservoir.

7. The computer input device of claim 6, wherein said tuned circuits are coupled to respective A-to-D converters for interpretation of computational means.

8. The computer input device of claim 5, wherein said at least two variable reactances are capacitors.