CA1152788A - Fibre optic scanning head - Google Patents

Abstract

FIBRE OPTIC SCANNING HEAD

ABSTRACT

This invention relates to the field of scanning graphical line data and more particularly, to an optical scanning head composed of a plurality of optical fibres that can be used in a semi-automatic mode to scan graphical data and transmit the optical data for assimilation by a digital computer. The invention is directed to an optical scanning head for scanning graphical line data comprising elongate scanning means capable of detecting at discrete points along its length variations in light intensity caused by the presence or absence of graphical line data on the graph when proximate to the scanning means. The invention is also directed to an optical scanning head for scanning graphical line data presented on an X-Y coordinate graph comprising:
a) a first scanning bar extending in the Y-ordinate direction;
b) a second scanning bar extending in the X-ordinate direction; and c) a third scanning bar extending in the X-ordinate direction;
each scanning bar being capable of detecting at discrete points along its length variations in light intensity caused by the presence or absence of graphical line data on the graph when proximate to the respective bar.

Description

FIELD OF THE INVENTION

This invention relates to the field of scanning graphical line data. More particularly, this invention relates to an optical scanning head composed of a plurality of optical fibres that can be used in a semi-automatic mode to scan graphical data and transmit the optical data for assimilation by a digital computer.

BACKGROUND OF THE INVENTION

With the use of coordinate digitizers it is known to track and convert graphical data such as well logs, maps and charts into digital form.
Present coordinate digitizers function by encoding the displacement over time of a cursor in the X and Y coordinate directions, as the cursor is tediously moved manually by an operator in a tracing or tracking manner along a line on the graph. The accuracy of the information processed by the digitizer depends directly and entirely on the degree of precision with which the operator keeps the cursor positioned on the graph line on the document as it is being traced by the operator~
The manual cursor tracing method is unsatisfactory and expensive because it is extremely time consuming, prone to inaccuracy, and is mind-numbing for the operator expecially when the line has numerous tightly spaced undulations, as occurs with well-logs .
In an attempt to deal with and overcome ~iSZ788 the forego ng difficulties, automatic methods have been developed together with equipment that auto-matically scans the graphic data. These automatic scanning machine~ function by scanning the entire document bearing the graphical data that is to be digitized. This technique necessarily results in the generation of a large volume of data, most of which is extraneous and irrelevant because it is not part of the trace line to be captured. The extraneous information, which includes such things as grid lines, other traces, and annotations, must be removed before the desired trace line can be identified and recovered. Lack of known reference points, and many heretofore unresolvable situ-ations, make this task basically impractical for complicated graphical data. As a consequence, conventional automatic line 3canners are used only for very simple tracing which thus limits their applicability because the majority of graphical data to be processed is complex.
One method of dealing with the problem of using automatic line scanners for complex graphical data has been to have an operator transcribe a simple version of the graphical data onto another document, and then scan this simpler version with the automatic scanner. This solution is somewhat self-defeating because it results in the inclusion of a manual step, and the accuracy of the method thus depends on how accurately the original trace 1~52788 is manually transcribed. A~ can be seen from the foregoing discussion, there i8 a real need for an apparatus and method of scanning graphical data that eliminates the need for an operator to trace the graph line and yet does not automatically generate unmanageable volumes of irrelevant data.

SUMMARY OF THE INVENTION

The present invention co~bines features of both the manual and the automatic methods to provide a unique apparatus and method which can quickly provide large volumes of accurate digitized data.
The invention comprises an optical scanning head formed by a specially configured plurality of optical fibres, the ends of which in one direction face the graphical line document to be scanned. To maximize scanning capacity, the array of optical fibres i8 arranged in a spread-out configuration of some suitable form such as the shape of "C", or a vertical trunk with two hori-zontal branches extending horizontally from the respective end~ of the vertical trunk. One particularly u~eful configuration for ~canning graphical data displayed on linear X and Y
coordinates is to have the optical fibres arranged .in a rectilinear "C" configuration, the open side facing the direction of tracking of the graphical data.
Parentheticall~, it should be noted in reading this disclosure that by referring to X and llSZ7~
Y coordinates, the applicant does not necessarily mean that such X and Y coordinates are rectilinear.
One or both of the x and Y coordinates may be curvilinear. The invention can accomodate such curvilinear coordinates. However, it is generally contemplated that the X and Y coordinates will be rectilinear in most applications.
The scanning head is mounted on the cursor of a digitizer and is used in association with a light source in such a way that light travelling from the source enters the facing end of the fibre array after having passed through or having been reflected from the document being scanned. Light passing through or reflected from the document at any particular point as viewed by an optical ibre varies directly according to whether there i~ a line on the document or the document i~ blank at that point.
m e various fibres in the array transmit the respective light signals received by each fibre to a remote photo-detection device which converts the light signals into corresponding electrical signals. The electrical signals 80 produced are in turn converted into corresponding digital elect-; rical signals representative of an "on" or "off"
state (e.g. if the light inten~ity transmitted by a given fibre is below a threshold value, the light input condition to the given fibre may be consid-ered "off": otherwise, it may be considered "on").

llS*788 Each of the fibres in the spread-out array functions individually and separately, and can~ in effect, "sense" a line when the array is passed over the graphic data on the document. This ability of the spread-out optical fibres to cooperate together to track the line permits a strip or band of the document on both sides of the line to be scanned at once, so ~ong a~ at least some portion of the fibre array is kept over the line. Thus, the operator, by simply moving the cursor carrying the spread-out fibre array broadly in a band pattern over the line to be traced, captures a particular ribbon-like ~ection of the document including the desired line. This procedure is much faster and more efficient than the presently employed system using a target point on the cursor because with that system the operator must painstakingly and tediously track a complex wavy line with ~he target point on the cursor.
Operator lapses necessarily occur and hence with the manually operated system, the data collected manually has a certain amount of inaccuracy therein. With the present invention, the operator needs only to keep some point of the relatively broad fibre array, instead of a precise point, over the line being traced in order to track the line quickly and accurately. To assist in illustrating the method, an analogy can be dr~wn between tracing over a line with a brush rather than a pencil point.

~152788 Digital signal information captured from the optical fibre array in the manner described above may be recorded or stored in digital form for discrete positions of the cursor as the cursor is moved in relation to the document being scanned.
The stored information may then be electronically processed to remove or substantially remove extraneous information such as coordinate or grid lines, thereby leaving the re~uired graph line naXed.
me combination of a scan device, rather than a pin-point target device, with a coordinate -~ digitizer is believed to be entirely unique. The optical fibre array scanner provides a relatively simple salution to the problem of scanning a complex wavy line in compari60n to already known, ; and previously discussed fully automatic methods, for several reasons. The volume of data generated by the invention is considerably reduced, since only a relatively narrow relevant strip of the document, including the desired line, is captured for assimilation. For any given position of the cursor relative to the document being scanned, the logical state of light signal inputs to the optical fibres gives information locating a point or points on lines of the document relative to the cursor as a frame of reference. Such information, combined with X and Y coordinate positional information of the cursor relative to a selected reference point on the document being scanned gives all the 11S2~88 information necessary to locate the position or positions of the point or points on lines of the document relative to the selected reference point.
(X and Y coordinate positional information from the cursor may be obtained by various known techniques.
Usually such information will be in analog form or have an analog component. For purposes of sub-sequent analysis, it is contemplated that analog signals corresponding to X and Y coordinate positions will be converted to digital signals.) In use, information concerning fibre optic states and corresponding X and Y coordinate positional inform-ation is taken at a plurality of cursor positions relative to the document being scanned. Such information can readily be stored in digital form for sub3equent analysis enabling digital recon-struction of graph lines on the document.
In some cases, it may occur that a graph line travels directly over a coordinate or grid line for a certain distance. If information being taken from the document at such locations is processed or analyzed to remove information such as coordinate or grid lines, then the graph line itself may al~o be removed. To accomodate this situation, the cur~or may include a visible target point which is used to manually trace the area of o~erlap between the graph line and the coordinate or grid line. Information from the optical fibre array is used only as an aid in identifying grid information during the period of manual operation.

~152788 'l'~e position of the graph line during manual operation corresponds to that of the target point.
As will be apparent to those skilled in the art, raw information from the optical fibre array and cursor may be processed by a digital computer when programmed with suitable software to extract therefrom a desired graph line.
The in~ention is directed to an optical scanning head for scanning graphical line data comprising elongate scanning means capable of detecting at discrete points along its length variations in light intensity caused by the presence or absence of graphical line data on the graph when proximate to the scanning means.
In the scanning head described, the scanning means may be comprised of a plurality of optical fibres. me scanning means may be in the ~hape of an elongated bar.
In the scanning head described, the scanning means may be constructed in the shape of two elongated bars, each extending in a different direction.
The invention is also directed to an optical scanning head for scanning graphical line data presented on an X-Y coordinate graph comprising: `
a) a first scanning bar extending in the Y-ordinate direction;
b) a second scanning bar extending in the X-ordinate direction and ~1~52'788 c) a third scanning bar extending in the X-ordinate direction;
each scanning bar being capable of detecting at discrete points along its length variations in light intensity caused by the presence or absence of graphical line data on the graph when proximate to the respective bar.
In the invention, the first, second and thixd scanning bars may be arranged in the con-figuration of a "C".
In the scanning head, the first, second ; and third scanning bars may each be composed of a plurality of optical fibres.
In the scanning head, the optical fibresmay have a diameter ranging from 1 mil to 20 mils.
In future configurations, to accomodate the trend to the metric system, it may be preferable to specify the diameter of the optical fibres in metric measurements. In a particular embodiment, each of the optical ibres in the scanning head may have a diameter of about 10 mils. Optical fibres of about 10 mils diameter are available under the trade mark CROFON from DuPont of Canada, Limited.
In the scanning head, the first scanning bar may be made up of sixteen 1~ mils diameter optical fibres arranged in a linear row, and the second and third scanning bars may each be made up of eight 10 mils diameter fibre~ arranged in a linear row, positioned at each end of the first scanning bar and extending in the same direction _ g _ 1~5278~

from the first scanning bar in a more or less :' parallel manner.
The invention i~ also directed to an optical scanning head comprising:
a) a vertical scanning bar;
b) an upper horizontal scanning bar extending horizontally from some point along said vertical scanning . bar (a); and c) a lower horizontal scanning bar opposed in position to said upper horizontal scanning bar (b) and extending horizontally from some point along said vertical scanning bar (a);
said scanning bars each comprising a plurality of optical fibres.
A method of optically scanning and as~imilating graphical data capable of being captured according to X-Y coordinate position comprising:
a) passing the ends of an array of optical fibres over the illuminated data to be scanned to capture and transmit light:
b) converting the light transmitted by each of the fibres to corresponding electrical signals:
c) converting each of the electrical signals into re~pective logic states, 1~527~3 d) tracking the X-Y position of the array and converting the position into an X/Y count and direction; and e) transmitting the data from (c) and (d) to a digital computer for processing.
DRAWINGS
In the drawings:
FIGURE 1 illustrates a perspective exploded view of the scanning head;
FIGURE 2 illustrates a perspective view of a digitizer (incorporating a digital computer) including the scanning head;
FIGURE 3 illustrates the optical fibres in the scanning head as arranged in a rectilinear "C" pattern;
FIGVRE 4 illu~trates a section of a typical well-log;
FIGURE 4A illustrate~ the raw data received from the well-log section illustrated in FIGURE 4 when scanned with the scanning head and processed by the digital computer FIGURE 4B illuQtrate~ the raw data of FIGURE 4A after the transverse grid (Y ordinates) has been removed;
FIGURE 4C illustrates the data of FIGURE
4B after the longitudinal grid (X ordinates) has been removed;

llSZ78~3 FIGURE 4D illustrates the data of FIGURE
4C after noise has been eliminated;
FIGURE 4E illustrates the data of FIGVRE
4D after curve identification and incorporation of the data obtained by manual tracing of sections of the curve with the target point;
FIGURE 5 illustrates a typical plot of the finished product from the data of FIGURE 4E:
FIGURE 6 illustrates in block diagram . 10 form the major components in the graphical line scanning and digitizing process;
FIGURE 7 illustrates in block diagram form the major components of the cursor assembly;
FIGURE 8 illustrates in block diagram form the major components of the cursor support hardware~
FIGURE 9 illustrates in block diagram form the major components of ~he interface hard-ware;
kIGURE 10 illustrates in block diagram form the major components of the interface software-operations software;
FIGURE 11 .illustrates in block diagram form the major components of the analysis software.
DETAILED DESCRIPTION OF ONE
.
EMBODIMENT OF THE INVENTION
Referring to the drawings, and FIGURE 1 first, FIGURE 1 illustrates the portion of the scanning head 5 that contains the array of optical 30 fibres arranged in a rectilinear "C" pattern, 115Z78~3 wherein upper linear hori7ontal bar 1 is made up of a plurality of optical fibres arranged in a row, vertical linear bar 2 is made up of a plurality of optical fibres arranged in a row, and lower linear horizontal bar 3 is made up of a plurality of optical fibres arranged in a row. The respective optical fibres forming the three bars are arranged around three adjoining side~ of a clear plastic panel 4 through which the document is viewed.
(FIGURE 1 illustrates the part carrying the three bars positioned to the right of base of the cursor 4a. This is for purposes of illustration only. In practice, the part with the three bars is clamped such that the vertical bar 2 is adjacent the base of the cursor 4a). The target point is located on panel 4 approximately at 4b. These four components make up the rnain elements of the scanning head 5.
Scanning head 5 is mounted on the cursor 6 of the digitizer, which i8 shown in per-spective detail in FIGURE 2. The digitizer is conventional and is constructed so that the cursor 6 rests above a lighted panel, the cursor 6 being connected to the digitizer by wiring and various connections 90 that the digitizer can keep track of the position of the cursor 6 in relation to X and Y coordinates. The document bearing the graphical line data to be scanned rests on the lighted panel 7 below the cursor 6.
Immediately abov~ ~he cursor 6 is located a small Xeypad 8 and indicators 8a. The keypad 8 115278~

enables the operator to enter into the digitizer mode changes (automatic to manual, or vice versa) and to enter other information that may be required while the graphical line is being traced by the operator using the cursor 6. The indicators 8a are used to display to the operator information relating to the current mode and other states of the digitizing system. The data gathered by the scanning head 5 is relayed optically through the fibre optic cable 9a to electronics module 10. The keypad 8 and indicators 8a are connected to electronics module 10 through electrical cable 9.
The X-Y encoder data gathered by the encoders 11 is connected by electrical cables 12 to the elect-ronics module 10.
FIGURE 3 illustrates an optical fibre array preferred for tracing well-log data compris-ing a plurality of optical fibres lla, in this case thirty-two optical fibres, arranged to form an upper scanning bar 1 comprising eight equi-diameter optical fibres arranged in a horizontal row, a vertical bar 2 comprising sixteen equi-diameter optical fibres arranged in a vertical row and a lower bar 3 comprising eight equi-diameter optical fibres arranged in a horizontal row. This con-figuration of optical fibres is ideally suited for the purpose of scanning an undulating graphic line that appears on X and Y coordinate graph paper such as in well-logs. The operator scans the graphic line by ensuring that at least one o the optical '. ' 3 15278~

fibres in the array of thirty-two fibres is over the graphic line at some point in time as the scan is made.
The applicant has determined that suit-able optical fibres for the applicant's inventlon are those which exhibit properties oE flexibility, durability and have a thin cladding thickness to reduce as much as possible the dead band effect between adjacent fibres. Plastic fibres such as those available under the trade mark CROFON, from DuPont of Canada Limited, despite reasonably high attenuation properties, have been found to be suitable.
FIGURE 4 illustrates a typical section of a well-log showing the trace of an undulating curve with associated l~ngitudinal and transverse grid lines.
FIGURE5 4A through to 4E illustrate in sequence the manner in which the curve appearing in the section of the well-log illustrated in FIG~RE 4 is captured by the scanning head and processed by the digital computer. FIGURE 4A illustrates the raw data, including the curve together with grid lines, that are obtained by scanning a well log using the optical fibre scanning head of the invention. This data is then processed to identify and remove the grid lines and extraneous unwanted information. FIGURE 4B illustrates the data as it appears after the transverse grid lines have been removed. FIGURE 4C illustrates the appearance of 115Z7~i38 the data after the longitudinal grid lines have been substantially removed. FIGURE 4D illustrates how the data appears after "noise" has been eliminated. FIGURE 4E illustrates the appearance of the curve data after curve identification and the incorporation of manually obtained data.
Finally, after pas~ing through these data processing procedures, the curve is plotted in the form that appears in FIGURE 5. In FIGURE 5, the transverse scale appears by means of indicator points at the bottom and top of the plot. Other salient information required by users of digital well-log information is also di~played according to present procedures.
FIGURE 6 illustrates in block diagram form the manner in which the data picked up by the cursor assembly 12, which includes scan head 5, cursor 6, indicators, keypad and encode~s, is transmitted through variou~ proce~ing procedures in order to yield the final printout product. The cursor assembly 12 i6 connected to cursor support hardware 13, which in turn is connected to inter-face hardware 14. The in~erface hardware 14 in sequence is connected to interface software 15, operations software 16, and analysis software 17 before the final product is produced.
FIGURE 7 illustrates in block diagram form the major components of the cursor assembly.
The light source 18 casts light on the document 19, the light from the document then being transmitted into the fibre optic array 20. Cursor movement, illustrated by the dotted-line block 21, i9 converted to shaft rotation by the encoder drum 22.
Shaft rotation iR coverted to quadrature ~ignals by shaft encoder 23.
FIGURE 8 illustrates in block diagram form the major components comprising the cursor support hardware. Light received by the fibre optic array 20 (see FIGURE 7) i~ tran~mitted by the fibre optic cable to a detector pre-amplifier 24, -^ which converts the light intensity into electrical signals. These electrical signals are transmitted into amplifier 25, from which the electrical signals are then transmitted to a logic switch 26 which converts the electrical qignal~ into fibre logic state~.
In turn, as seen in FIGU~E 8, the quadrature signal~ received from the shaft encoder 23 (see FIGURE 7) are tran~mitted to a quadrature detector 27, which then provides an X~Y count and direction.
FIGURE 9, by means of block diagrams, illu~trates the major components of the interface hardware, which processes the information received from the cursor support hardware, illustrated in FIGURE 8. ~he fibre logic ~tates received from logic switch 26 (see FIGURE 8) are transmitted to data registers 29. The X/Y coun~ and direction information received from the quadrature detector 27 (~ee FIGURE 8) are tran~mitted through an X

counter, Y counter, fibre diameter counter 28 before being transmitted to the data registers 29.
The data from the data registers 29 is transmitted to command registers 30. Command registers 30 receive information from keypad 8, and provide information to the indicators which are followed by the operator. Information from the command registers 30 is then`transmitted to PDP~
computer registers 31. A specialized interface has been designed by the applicant to connect a digitizer to a PDP-ll~ computer. As mentioned previously, the applicant's digitizer consists of a standard X-Y encoder digitizer which has been retrofitted with a scanning device including an optical fibre array to provide additional information for the computer. The interface provides support for the X-Y encoders, scanning device, keypad and various indicators used for operator interaction. The applicant's interface is designed using conventional methods employed by many PDP-ll~ interfaces. The applicant's interface registers consist of six registers which are organized sequentially in address space. The first two registers are control registers while the next four are data registers. The six interface registers 31 are as follows: command/status register 32, operator action register 33, X
register 34, Y register 35, vertical scan register 36 and horizontal scan register 37.

115Z78~

Command/status register 32 is the main interface control register. It iB used to imple-ment interface commands and to indicate movement of the cursor 6.
Operator action register 33 i9 concerned with providing additional operator interaction facilities. This register controls the keypad 8 and indicators 8a.
The X register 34 contains the X value of the cursor 6 position. The value is stored as a sixteen bit binary number.
The Y register 35 contains the Y value of the cursor 6 position. This value i~ also stored as a sixteen bit binary number.
The vertical scan register 36 contains the scan information from the vertical part of the scan bar 2. The bits are arranged such that bit 0 corresponds to the topmost fibre of the vertical bar 2 and bit 15 corresponds to the bottommost fibre of vertical bar 2.
The horizontal scan register 37 contains the scan information received from the horizontal fibres making up the upper bar l and the lower bar 3. The bits are arranged such that bits 0 and 8 correspond respectively to the rightmost fibres in the upper and lower bars and bits 7 and 15 cor-respond respectively to the leftmost fibres in the upper and lower bars.
FIGURE 10 illustrates how the PDP-ll registers 31 are lin~ed with the interface software -ll~Z7~8 38 and operation software 39 of the applicant' 8 computer.
FIGURE 11 illustrates by means of sequential block diagrams the major components of the analysis software, whereby the mapped data received from the operations software 39 is processed to remove the transverse grid (block 40), the longitudinal grid (block 41), noise (block 42), identify the curve, (curve identification block 43) and finally convert the data into the final product as represented by data conversion block 44.
FIGURES 4 through 4E, discu~sed previously, illustrate the results obtained when this procedure is followed.
The specific details as to the operation of the interface depend upon associated programming used in the PDP~ computer. The applicant's interface is configured to resemble the type of operation which i9 commonly used by many PDP-11 peripherals.
As will be apparent to those skilled in the art, in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in :, accordance with the substance defined by the following claims.

Claims (17)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An optical scanning apparatus for developing information signals representative of line data on a graph-ical chart comprising:
a light source for illuminating the chart;
a frame for maintaining the chart in a fixed position relative thereto;
an optical scanning head in proximity with the chart and having a plurality of discrete scanning means generally arranged in an elongated pattern, each of said scanning means producing an intensity signal in response to variations in light intensity caused by the presence or absence of the line data on the chart when proximate said scanning means;
means for coupling said scanning head to said frame such that said scanning head can be manually moved relative said frame and the chart;
means connected to said coupling means for pro-ducing position signals representative of the position of said scanning head relative said frame; and circuit means receiving said intensity signals and said position signals for developing the information signals representative of the line data on the graphical chart in response to said scanning head being manually traced along the line data.

2. An optical scanning apparatus according to Claim 1 wherein said plurality of scanning means are optical fibres.

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3. An optical scanning apparatus according to Claim 1 or 2 wherein said plurality of discrete scanning means are shaped as an elongated bar.

4. An optical scanning apparatus according to Claim 1 or 2 wherein said plurality of discrete scanning means are shaped as two elongated bars, each extending in a different direction.

5. An optical scanning apparatus according to Claim 1 or 2 wherein said plurality of scanning means are arranged generally in a configuration of a "C".

6. An optical scanning apparatus according to Claim 2 wherein said optical fibres have a diameter ranging from about 1 mm to 20 mm,

7. An optical scanning apparatus according to Claim 1 wherein said plurality of scanning means are arranged into a vertical scanning bar, a first horizontal scanning bar extending from said vertical bar proximate an upper end thereof, and a second horizontal scanning bar extending from said vertical bar proximate a lower end thereof.

8. An optical scanning apparatus according to Claim 7 wherein said vertical scanning bar comprises sixteen 10 mm diameter optical fibres arranged in a linear row, and said first and said second horizontal scanning bars each comprises eight 10 mm diameter optical fibres arranged in a linear row.

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9. An optical scanning apparatus for producing information signals representative of line data on a well-log chart having a reference grid pattern, the line data being characterized by discontinuities, intermingled or multiple lines, comprising:
a light source for illuminating the chart;
a frame for maintaining the chart in fixed position relative thereto;
an optical scanning head in proximity with the chart and having a plurality of discrete scanning means generally arranged in an elongated pattern, each of said scanning means producing an intensity signal in response to variations in light intensity caused by the presence or absence of the line data on the chart when proximate said scanning means;
means for coupling said scanning head to said frame such that said scanning head can be manually moved relative said frame and the chart;
means connected to said coupling means for pro-ducing position signals representative of the position of said scanning head relative said frame;
first circuit means for producing status signals representative of movement of said scanning head over the chart in response to discontinuities in the line data; and second circuit means receiving said intensity signals, said position signals and said status signals for developing the information signals representative of the line data on the chart as said scanning head is manually traced along the line data.

10. An optical scanning apparatus according to Claim 9 wherein said plurality of scanning means are optical fibres.

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11. An optical scanning apparatus according to Claim 9 or 10 wherein said plurality of discrete scanning means are shaped as an elongated bar.

12. An optical scanning apparatus according to Claim 9 or 10 wherein said plurality of discrete scanning means are shaped as two elongated bars, each extending in a dif-ferent direction.

13. An optical scanning apparatus according to Claim 9 or 10 wherein said plurality of scanning means are arranged generally in a configuration of a "C".

14. An optical scanning apparatus according to Claim 10 wherein said optical fibres have a diameter ranging from about 1 mm to 20 mm.

15. An optical scanning apparatus according to Claim 9 wherein said plurality of scanning means are arranged into a vertical scanning bar, a first horizontal scanning bar extending from said vertical bar proximate an upper end thereof, and a second horizontal scanning bar extending from said vertical bar proximate a lower end thereof.

16. An optical scanning apparatus according to Claim 15 wherein said vertical scanning bar comprises sixteen 10 mm diameter optical fibres arranged in a linear row, and said first and said second horizontal scanning bars each comprises eight 10 mm diameter optical fibres arranged in a linear row.

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17. A method of developing information signals representative of line data on a graphical chart, compris-ing the steps of:
maintaining the chart in a fixed position relative a source of light and a frame;
manually tracing an array of optical fibres over the chart in accordance with the line data to develop a plurality of first data signals corresponding to the intensity of light detected by each optical fibre;
producing second data signals representative of movement of said array of optical fibres relative said frame; and transmitting said first data signals and said second data signals to a digital computer for subsequent processing.

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