GB2130410A

GB2130410A - Data input apparatus

Info

Publication number: GB2130410A
Application number: GB08326011A
Authority: GB
Inventors: Paul Kenyon
Original assignee: COLE ELECTRONICS Ltd
Current assignee: COLE ELECTRONICS Ltd
Priority date: 1982-09-28
Filing date: 1983-09-28
Publication date: 1984-05-31
Also published as: GB8326011D0

Abstract

Digitising apparatus which provides data relating to the position of a stylus or cursor over the surface of a tablet 10 bearing a work sheet in the form of a map, drawing or chart comprises a page reader 12 including a plurality of beam emitter/detector pairs, adapted to detect the presence or absence, according to a predetermined code, of features such as a predetermined arrangement of holes 18 or reflecting pieces formed in or on the work sheet, and to generate data signals enabling automatic recognition of a particular work sheet and, hence, further processing of the stylus or cursor related data with reference to identification, position or other information appropriate to that particular work sheet. <IMAGE>

Description

SPECIFICATION Digitising apparatus This invention relates to digitising apparatus and, more particularly though not exclusively, to a page reader for use with micro processor based digitiser tablets.

A digitiser is a piece of electronic equipment which provides information relating to the position of a stylus or cursor over the surface of a table top unit or tablet. The stylus or cursor is electronically connected to a data processor usually including a display and interacts with circuits contained within the table to produce the 'X' and 'Y' co-ordinates of the cursor on the display. In use, a work sheet such as a map, chart or drawing is placed upon the tablet and the equipment used to calculate with reference to that particular worksheet and display or to feed to an external computing system, information such as distance moved, perimeters or areas etc. For this purpose it is necessary to provide data for example, identifying the work sheet and the scale of dimensions whether it be in millimetres or miles.

One object of the present invention, is to enable such equipment to recognise automatically, the particular page, sheet or chart currently displayed.

According to this invention, we propose digitising apparatus for providing data relating to the position of a stylus or cursor or the like over the surface of a tablet on which, in use, a work sheet is placed, and incorporating a page or work sheet reader for co-operation with a work sheet bearing or otherwise including features capable of recognition by the reader, and representing in accordance with a predetermined code, identification, position or other information appropriate to that particular work sheet, the page reader comprising a plurality of sensing devices in a predetermined arrangement corresponsing to the arrangement of features of the work sheet and each responsive to the presence or absence of the features thereby to generate data signals representing the coded information pertain ing to the work sheet.

The sensing devices may be of any convenient kind appropriate to the features of the work sheet to be recognised by the reader but, in a preferred embodiment the sensing devices each comprise an emitter and a detector respectively for generating and receiving a beam of energy, and disposed relative to one another so as to detect the presence or absence of a feature of the work sheet in the path of the beam, whereby coded information pertaining to the work sheet can be represented as data signals produced by the detectors.

The work sheets which may be individual sheets or charts or the like or the pages of a book, are preferably formed with holes, the presence or abs ence of which or the presence of a blanking or reflecting piece covering the holes, according to a predetermined code can be recognised by the sensing devices.

It will be understood, that the page reader may be arranged such that the work sheet or a part thereof bearing or otherwise having the features which co-operate with the sensing devices, intervenes between the emitter and the detector. In the preferred embodiment, however, the emitter and detector are disposed both together on the tablet side of the work sheet and foil stickers are placed over selected holes according to a predetermined code, such that light from the emitter is reflected back to the detector.

Other features of the invention are set forth in the appendant claims and in the following description, by way of example of a preferred embodiment of the present invention. Reference is made to the accompanying drawings of which; Figure 1 shows a digitisertablet having a page reader and incorporating a precision binder containing pages adapted for identification by the page reader; Figure 2 is a diagram of a sensing device; and Figure 3 is a circuit diagram of the page reader.

The digitisertablet 10 has a page reader 12 along the top edge thereof and includes a row of sensing devices (not shown in Figure 1) and a precision binder which holds loose leaves or pages 16 on the tablet 10 such that a row of holes 18 along the top edge of each page is accurately in register with either a left or right hand set of sensing devices in the page read 12. When a page is turned, from right to left, the holes in it which were originally in alignment with the right hand sent of sensing devices automatically and accurately are brought into register with the left hand set of sensing devices.

Each of the sensing devices comprises an emitter 22 in the form of a light emitting diode (LED), which is disposed to direct an infra-read beam toward the hole 18 above as shown in Figure 2. Beside the emitter 22, a detector 24 in the form of a phototransistor, is mounted such that a foil sticker or other suitable reflecting piece 26 placed over the hole 18, will cause the beam of energy to be reflected onto the detector 24. Foil stickers are placed over selected holes according to a predetermined code to represent information pertaining to that particular page.

As illustrated in Figure 1, a group of four holes adjacent the binder, are designated for identification of the particular book. Only the front and back leaves require foil stickers for this purpose and the same holes on each are covered. By means of a binary code these four holes may be used to encode up to sixteen books.

Each page is uniquely defined by the position of a hole over which a foil sticker is placed, leaf one having a foil sticker over position one, leaf two over position two and so on up to leaf sixteen.

Since in this embodiment, a row of twenty holes is provided at the head of each page, the page reader requires forty sensing devices, each comprising an LED/phototransistor pair 22124 and these are divided as described above into a left hand and a right hand set of twenty sensing devices each.

For convenience, the sensing devices 20 are connected together in five groups of eight, of which only one group is shown in detail in Figure 3. These groups are coupled, via suitable buffer circuits 30 (not shown), to a microprocessor system 32 which is capable of energising each LED 22 and sensing photocurrent in each phototransistor 24. All of the LED/phototransistor pairs are oriented such that infra-red rays 23 emitted by the LED's 22 are reflected by foil stickers blanking-off the associated hole, onto the phototransistor.

One function of the microprocessor system 32 is to determine which of the LED-phototransistor pairs 20 are covered by foil stickers and use this knowledge to decode which pair of pages of which book is currently on view. This information may then be communicated to a central computer via a serial or parallel linkforfurther processing and more particu marly to enable automatic analysis and/or display of the cursor or stylus related data with reference to identification, position or other information pertaining to the page currently on display. Such information may be stored in the central computer for recall when required upon recognition of the page concerned.

The phototransistors 24 are likely to have residual sensitivity at optical wavelengths, so it is possible that some of them will register significant photocurrent when not covered by foil stickers due to ambient lighting. To avoid such errors the microprocessor is programmed to examine each phototransistor output over a period of 10 milliseconds with all LED's 22 off and to deduce that, any which register light at any point during that period cannot be covered with foil.

(The period of 10 milliseconds is chosen to cover any light fluctuations due to the main a.c. waveform).

The microprocessor is also programmed to check that, a) For hole locations used in book identification the right and left-hand holes are identical; b) For all other locations the right and left-hand codes are complementary and sequential.

The importance of check (b) lies in its ability to highlight errors due to pages being held vertical (or at least not laid right down) or pages not in their correct sequential position. Under these conditions the microprocessor can be programmed to send an appropriate error message to the central computer.

Claims

1. Digitising apparatus for providing data relat ing to the position of a stylus or cursor orthe like over the surface of a tablet on which, in use, a work sheet is placed and incorporating a page or work sheet reader for co-operation with a work sheet bearing or otherwise including features capable of recognition by the reader and representing, in accordance with a predetermined code, identification, position or other information appropriate to that particular work sheet, the page reader compris ing a plurality of sensing devices in a predetermined arrangement corresponding to the arrangement of features of the work sheet and each responsive to the presence or absence of the features thereby to generate data signals representing the coded infor mation pertaining to the work sheet.

2. Apparatus according to Claim 1 and compris ing means for locating the work sheet with the predetermined arrangement of features thereof accurately in register with the arrangement of sensing devices.

3. Apparatus according to Claim 2 comprising a precision binder for holding a plurality of work sheets on the tablet such that a row of holes along the top edge of each work sheet can be brought accurately into register with the arrangement of sensing devices.

4. Apparatus according to any one of Claims 1 to 3 wherein each sensing device comprises an emitter and a detector respectively for generating and receiving a beam of energy and disposed relative to one another so as to detect the presence or absence of holes formed in a work sheet in accordance with the predetermined code, or the presence or absence of blanking or reflecting pieces disposed in accordance with the code.

5. Apparatus according to Claim 2 wherein the emitter and detector are so disposed that, in use, a beam of energy from the emitter impinging upon the work sheet, is reflected to the detector.

6. Apparatus according to Claim 4 or Claim 5 wherein the page reader is attached to or incorporated in the tablet along one edge thereof to receive one edge of a work sheet along which the holes are formed, emitter and the detector of each sensing device being disposed adjacent to one another on the same side of the work sheet such that beams of energy from the emitters impinging upon the work sheet are reflected to the detectors to produce the said data signals.

7. Apparatus according to any one of Claims 1 to 6 wherein reflecting pieces are placed on the work sheet in accordance with the predetermined code, such that beams of energy from the emitters corresponding in position to reflecting pieces in the said predetermined arrangement are reflected onto the detectors to produce said data signals.

8. Apparatus according to any one of the precede ing claims and comprising a data processing system coupled with the sensing devices to receive the data signals and programmed to decode the said signals to provide information enabling automatic analysis with reference to identification, position or other information pertaining to a particularly work sheet, of the date relating to the position of the stylus or cursor or the like over the surface of the tablet on which the work sheet is displayed.

9. Digitising apparatus constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.