- Email: [email protected]
Permanent records using pen-type plotters
i GRAPHIC DISPLAY SYSTEMS I This is the third in the series of surveys being presented in Computer Aided Design. Dealing mainly with pen-type plotters it covers the various technical aspects of these important computer peripherals and lists U.K. manufacturers and agents for such equipment. The directory section has been compiled from information supplied by manufacturers.
Permanent records using pen-type plotters Introduction - occasions when Pen-Type Plotters are used Computer driven pen-type plotters have been available for some ten or so years, and their application has developed slowly during this period. Although they are commonly referred to as 'plotters' they should be distinguished from another type of plotter referred to in the last issue of Computer Aided Design - the microfilm plotter, which produces a photographic image of a display, or sequence of displays, on a cathode ray tube, using an optical system. (J. Halas - Computer Animation - Computer Aided Design Spring 1971 p. 29. et seq.). Pen-type plotters produce a hard-copy record, on opaque or transparent paper - when the latter is used, the output can be reproduced in an exactly similar way to a draughtsman's master drawing, using the dyeline process. Hardcopy is required when any kind of permanent drawings must be produced - e.g. for use as working drawings, for erection or fabrication; for comment and checking by one designer or by committee, or simply for record purposes. Other uses include the reduction of experimental or financial data to easy assimilable form. Further, correlations, trends and comparative relationships between designs, or performance characteristics can be plotted graphically, illustrating differences and characteristics which can be seen at a glance, rather than within minutes or hours, as is the case when masses of numerical data must be scanned. Varying types of equipment currently available enable drawings from the size of printed circuit board layouts, a few inches square, up tO full scale lines of aircraft wings to be draughted, the latter in two or three sections using a machine with a large bed, which, incidentally, can loft the lines of most automobiles in one operation.
By F. E. Taylor
being used to reduce the large mask to working size. The electromechanical positioning gear normally consists of a solenoid for lifting the pen off the paper, so as to skip undrawn areas, and motors for positioning the pen in one (drum type) or two (flat bed type) directions (see Fig. 1). Positioning must be accurate, with no overshoot, which implies driving the pen, at speed, using a critically damped servo system. The faster the movement of the pen, the more expensive the servo system. The driving motor normally drives the pen carriage via a helical screw - thus both rotational (screw) and linear (carriage) inertia must be overcome when moving the pen. In practice, these limit the maximum rate of movement in either direction to approximately four inches per second, or four hundred one-hundredth inch increments per second. Most plotters work in a 'relative' m o d e - i.e. move a given number of increments from their present position, one by one, but variants are available which use 'absolute' positions, measured from a predetermined origin, and which eliminate increments. Lead .SCr ew and guide \ 'y' motor X and~,servo ~
Pen in/out Carriage ~, movement "~
-_~--
Sprocket Oo.J~'i nhOles paper
o
o
'
o
o
(a)
a
a~n, • motor
~
'
-
Basic Hardware Basically, the plotter consists of a pen, of either the ball or normal ink-fed varieties - being effectively a fine tube in the latter case, together with electromechanical means for positioning it in two directions, on the 'platen' or paper support. In the ease of certain plotters, the pen can be replaced by a sharp stylus, and the paper by a two-layer opaque/transparent peelable material, so that, after suitable inscription or cutting by the stylus, parts of the laminate can be peeled to produce a stencil or mask. Such techniques can be used for the production of masks for the manufacture of integrated circuits, photographic reduction
SUMMBR 1971
drive link, \ \ c°.nnect!ng"~-~k\
\ / " ~ ~,
~
~ K (~ ~ 'y' motor', s.ervo
an cart,age
(b)
Fig. 1. 27
Jlil Jil / /
p
__._-
i !
.....
i
J-J
........
\
/J
\
J 7
/"
/
/
\\
Fig. 2.
Basic Software The basic software required to put a plotter to work must translate the basic data representing the matter to be drawn into incremental steps, relative to each other, in sequence. If a graph is to be drawn, its axis must be drawn, and if the data does not fit the area to be plotted in such a way that it fills the area without overflow, then the dimensions must be scaled in such a way that conversion of two opposing extreme values, in any direction, generates a number of increments equal to, or nearly equal to, the available maximum. Further basic routines required are those which will draw a straight line between any two points (using increments as dimensions, after scaling) and those which draw s y m b o l s - preferably both alphabetic and numeric, for annotating the diagrams drawn. Basic software can be extended to interpret 'shorthand' or 'source program' instructions derived from the driving p r o g r a m - for example routines to draw circles, or to extrapolate between points using various conic sections can save a great deal of programmer's time. Other similar routines can perform such functions as shading or crosshatching given areas, or smoothing experimental data. The majority of such instructions are added to F O R T R A N
28
programs, and linked via a ' C A L L S U B R O U T I N E . . .' statement. Until recently, it was necessary to expand a graphics source program containing extended basic routines (such as those above) into incremental form using a pre-processing run, but recently equipment has appeared which enables the corresponding expanded code to be called from a shared on-line store, within the plotter controller, when required. This is stated to reduce the object code (numeric code) instructions representing a given drawing by a considerable factor - a factor of 30 times having been quoted.
Some Applications of Plotters The hardware and software already outlined must be integrated with suitable computing routines before useful problems can be solved. Routines have been developed over the past few years to solve a wide range of problems efficiently - being most valuable when the rapid assimilation of drawings saves considerable r e s o u r c e s - o f t e n manual effort, and sometimes computational power. The following are amongst successful plotter applications already mounted:
COMPUTER AIDED DES/GN
~ig. 4 ~.3
STAer OInECTlO~ O~ fiOTATtO~ ANO PART NO,
\ I -s/e
, 6 2 5 FRLL ]fl 2 ~ ~267~J-~0-06~5
US[ , 0 0 5 SHJ MH[N BORING
1 1 / 3 2 ORILL a S / ~ Z 01 I/2 C ecm[ s/16 oe. 2 MOLES
F1.25~10flILL ]HRU 5 / 1 6 - t s T~P TM~U 2 HOL~S t T [ H • I
Fig. 5 , ~
Fig. 6 ~ ,
................................................................................................................................................................
_L. -
-4-=-mT
Ju~
,u_ ! 968
S U M M E R 1971
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40
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The derivation of contours, representing a third dimension, from a series of random third-dimension measurements. One proprietary program for this purpose was mentioned in an earlier issue of this journal (Description of GPCP program, Computer Aided Design Winter 1970, p.52). The third dimension can represent h e i g h t - e . g , of physical terrain or a three-dimensional part, or pressure - e.g. associated with a weather map, or pressure distribution around an aerofoil or pump rotor, or temperat u r e - e.g. temperature distribution within an internal combustion engine cylinder block•
++
30
?. ~ C ~
st~ooe
TO mOll+J[ c | oN ¥(s+c+ Y - 1 0 3
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,=-+.•.-+o
i I!
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. m .w¢,
.=== • W . . m
HUMPHR£Y$
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:![ ..... olo
bridge design - see Fig. 2. preparation of drawings of the logic design of computers - using the LIDO system (Logic In, Diagrams Out) (see Fig. 3). Highway d e s i g n - based on varied input specifications. A typical example is shown in Fig. 4. Mechanical draughting of parts. Fig. 5 shows a cam draughted in this way. COMPUTER AIDED DESI6N
+
Plotting PERT (Critical Path Method) diagram. Fig. 6 shows same diagram (see also Computer Aided Design, Autumn 1969, p. 47). For checking finite element analyses before extensive computation (see Fig. 7). Chemical plant pipework layout and detailing. Fig. 8 shows a sample of output from the Humphries & Glasgow/NCC R A P I D system. Drawings of varying detail, scaled in a nonlinear fashion to 'shorten' pipe runs with little detail, can be produced at will by inserting varying numbers of pipe records, and plotting corresponding drawings. In a lighter view, for use as a relaxation by engineers. Fig. 9 shows an example!
I
only' facilities are needed. It is worthy to note that a c.r.t. display and a plotter can share the same display f i l e - the former scanning the file ten times each second (typically), whilst the latter scans the file once only for each copy drawn, though at a much lower scanning rate, in terms of scan time per drawing element (line, circle, axis, etc.). The other alternative, electrostatic plotters, offer low quality output on a short timescale, but their basic principle of synthesising pictures from discontinuous dots prevents them from competing with pen type plotters when draughted drawings of high quality are required. They are best regarded as a 'quick look' or 'quick record' hard copy device, when speed is important, and accuracy less so. Summarising, pen type plotters enable high quality drawings to be prepared, as an alternative to handdraughted drawings. Considerable economic benefits ensue when the plotter is used on the final output peripheral, following design calculations by computer, since it eliminates the costly alternative line printer -~ numeric table ~ draughtsman ~ drawing interface.
Dr. F. E. Taylor is responsible for Technical Field Support for the Membership and Advice Division of the National Computing Centre, previously occupying posts with that body as Development Officer, and Head of its Interactive Computing Department.
F~O. 9 Plotters compared w i t h other Graphic Devices Cathode ray t u b e - based display systems were dealt with in detail in two articles and a survey in the previous issue of Computer Aided Design (Spring 1971), and in the preceding issue (Winter 1971) mention was made (on p. 32) of electrostatic terminals, capable of producing graphical data. Pen type plotters have the advantage that hardcopy of good quality, using varying pen widths and colours where needed, can be produced, though on a longer timescale than is the case with the other two devices. C.r.t. displays are irreplaceable for interactive working within a timescale of minutes, and when 'quick-look' and 'softcopy
U.K. Remote multi-access systems for the engineer This important survey, which appeared in the Winter 1971 issue of 'Computer Aided Design', is now available as a separate booklet. All the information you need on time-sharing and remote batch processing from the design engineers view-point is contained in this booklet, Supplies are limited, order yours now at the special Datafair price of 75p (postage 5p) while stocks last (normal price is £1.25), from The Editor, Computer Aided Design, Dorset House, Stamford Street, London, S.E.1. SUMMER 1971
A~bove is our CORAD,OMAT 21 c0mpu,ter-controlled drafting machine. The working area of this machine is 63 in. x 51 in. and the accuracy of the electronic positioning system is of the order of one-thousandth of an inch. This machine has been sold to many customers throughout the world for applications in map-making and drawing, microelectronics, printed circuit design, and general engineering drawing. The machine is now in full production at our
Haddin~ton factory.
The OORA,DOIMAT 21 is only one of a range of high-accuracy measuring and drafting systems manufactured by Faul-Coradi ('Scotland) Limited and we have already achieved w o r l d - w i d e recognition for our work in the field of astronomy with such machines as GA,DAXY.
Faul-coradm EV~I~IDE,H A D ~
EASTL01-11~SCOT1.N~Ul~
Telephone Haddington 2621
31
Permanent records using pen-type plotters Introduction - occasions when Pen-Type Plotters are used Computer driven pen-type plotters have been available for some ten or so years, and their application has developed slowly during this period. Although they are commonly referred to as 'plotters' they should be distinguished from another type of plotter referred to in the last issue of Computer Aided Design - the microfilm plotter, which produces a photographic image of a display, or sequence of displays, on a cathode ray tube, using an optical system. (J. Halas - Computer Animation - Computer Aided Design Spring 1971 p. 29. et seq.). Pen-type plotters produce a hard-copy record, on opaque or transparent paper - when the latter is used, the output can be reproduced in an exactly similar way to a draughtsman's master drawing, using the dyeline process. Hardcopy is required when any kind of permanent drawings must be produced - e.g. for use as working drawings, for erection or fabrication; for comment and checking by one designer or by committee, or simply for record purposes. Other uses include the reduction of experimental or financial data to easy assimilable form. Further, correlations, trends and comparative relationships between designs, or performance characteristics can be plotted graphically, illustrating differences and characteristics which can be seen at a glance, rather than within minutes or hours, as is the case when masses of numerical data must be scanned. Varying types of equipment currently available enable drawings from the size of printed circuit board layouts, a few inches square, up tO full scale lines of aircraft wings to be draughted, the latter in two or three sections using a machine with a large bed, which, incidentally, can loft the lines of most automobiles in one operation.
By F. E. Taylor
being used to reduce the large mask to working size. The electromechanical positioning gear normally consists of a solenoid for lifting the pen off the paper, so as to skip undrawn areas, and motors for positioning the pen in one (drum type) or two (flat bed type) directions (see Fig. 1). Positioning must be accurate, with no overshoot, which implies driving the pen, at speed, using a critically damped servo system. The faster the movement of the pen, the more expensive the servo system. The driving motor normally drives the pen carriage via a helical screw - thus both rotational (screw) and linear (carriage) inertia must be overcome when moving the pen. In practice, these limit the maximum rate of movement in either direction to approximately four inches per second, or four hundred one-hundredth inch increments per second. Most plotters work in a 'relative' m o d e - i.e. move a given number of increments from their present position, one by one, but variants are available which use 'absolute' positions, measured from a predetermined origin, and which eliminate increments. Lead .SCr ew and guide \ 'y' motor X and~,servo ~
Pen in/out Carriage ~, movement "~
-_~--
Sprocket Oo.J~'i nhOles paper
o
o
'
o
o
(a)
a
a~n, • motor
~
'
-
Basic Hardware Basically, the plotter consists of a pen, of either the ball or normal ink-fed varieties - being effectively a fine tube in the latter case, together with electromechanical means for positioning it in two directions, on the 'platen' or paper support. In the ease of certain plotters, the pen can be replaced by a sharp stylus, and the paper by a two-layer opaque/transparent peelable material, so that, after suitable inscription or cutting by the stylus, parts of the laminate can be peeled to produce a stencil or mask. Such techniques can be used for the production of masks for the manufacture of integrated circuits, photographic reduction
SUMMBR 1971
drive link, \ \ c°.nnect!ng"~-~k\
\ / " ~ ~,
~
~ K (~ ~ 'y' motor', s.ervo
an cart,age
(b)
Fig. 1. 27
Jlil Jil / /
p
__._-
i !
.....
i
J-J
........
\
/J
\
J 7
/"
/
/
\\
Fig. 2.
Basic Software The basic software required to put a plotter to work must translate the basic data representing the matter to be drawn into incremental steps, relative to each other, in sequence. If a graph is to be drawn, its axis must be drawn, and if the data does not fit the area to be plotted in such a way that it fills the area without overflow, then the dimensions must be scaled in such a way that conversion of two opposing extreme values, in any direction, generates a number of increments equal to, or nearly equal to, the available maximum. Further basic routines required are those which will draw a straight line between any two points (using increments as dimensions, after scaling) and those which draw s y m b o l s - preferably both alphabetic and numeric, for annotating the diagrams drawn. Basic software can be extended to interpret 'shorthand' or 'source program' instructions derived from the driving p r o g r a m - for example routines to draw circles, or to extrapolate between points using various conic sections can save a great deal of programmer's time. Other similar routines can perform such functions as shading or crosshatching given areas, or smoothing experimental data. The majority of such instructions are added to F O R T R A N
28
programs, and linked via a ' C A L L S U B R O U T I N E . . .' statement. Until recently, it was necessary to expand a graphics source program containing extended basic routines (such as those above) into incremental form using a pre-processing run, but recently equipment has appeared which enables the corresponding expanded code to be called from a shared on-line store, within the plotter controller, when required. This is stated to reduce the object code (numeric code) instructions representing a given drawing by a considerable factor - a factor of 30 times having been quoted.
Some Applications of Plotters The hardware and software already outlined must be integrated with suitable computing routines before useful problems can be solved. Routines have been developed over the past few years to solve a wide range of problems efficiently - being most valuable when the rapid assimilation of drawings saves considerable r e s o u r c e s - o f t e n manual effort, and sometimes computational power. The following are amongst successful plotter applications already mounted:
COMPUTER AIDED DES/GN
~ig. 4 ~.3
STAer OInECTlO~ O~ fiOTATtO~ ANO PART NO,
\ I -s/e
, 6 2 5 FRLL ]fl 2 ~ ~267~J-~0-06~5
US[ , 0 0 5 SHJ MH[N BORING
1 1 / 3 2 ORILL a S / ~ Z 01 I/2 C ecm[ s/16 oe. 2 MOLES
F1.25~10flILL ]HRU 5 / 1 6 - t s T~P TM~U 2 HOL~S t T [ H • I
Fig. 5 , ~
Fig. 6 ~ ,
................................................................................................................................................................
_L. -
-4-=-mT
Ju~
,u_ ! 968
S U M M E R 1971
i ......................................................................................................
_~--,~ ~--
AUG
~r
~ , ~T;
~v
~c
I
.e~
yea
~
~ ~9 6 9
~T ':
29
Fig. 7 \ co-o++Iw*+¢l
l,+,
++ m / l molTm + I,OO ) ~ l ~ • t l ?
£+,o i
• l,Oo
)3@•*17
[t|T wE[i+t 11o•ooo I;?*Ggl Itl.lll lot,~
+ +•o° 1• l . o o t~ I,OO tq 1.oo EO i,OO l + =,oo P+ o.++
1++•*+~ see•M? a'u.•lI l++,ll? i++.ll? +S+•+I7 ++h~+~
:I+,*+I lo?•,~o |~.too lo*,lls lll*IW lO?.,++ =ix.v)=
I+ r , ? fT
* v* 5, r, * r? P t P
so=.~ol tOl•lll tOl,l$l lOl.lll iO S * l$ + I Q + . l+ + ~a+.l+o
3; l+OO l+?.qt? 3T leO0 ) + p I I t Y
++5.1~ t3+*lll lOS*tO0 %3&*?1+
+, +.oo l++,+tl
I+P*tO© 1 ; + . ? ] 1
~+
rrt~= ~,~r*l+~
No,err P-n¢*tatoK-+*
raNIm*CT N~.
= riot
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~1~ a.*. ,*(=
: sr=oo~
~.=o o.~s i,oo
r.l.,.~-t•er¢-*o r;J.s,.=.,r¢,,° ,.)-°*~*~*~rc
tssv~ OAT, s~n(ss onto,
, o , t.-¢*=,** : ~o
*,oo
,,.c~c.=.~r.ss
r~ui~
: s~t,,
,:++~
..,(.,=,-.
. . . .
,o..+.+'. . . . . . . . . . . . . 0~.
,~.
,,
I I
1
r.I •lw*~,lr¢*~o
t
•c ' o ~
;:,+~
. . . .*
40
:+:+
+-,I
1¢~
The derivation of contours, representing a third dimension, from a series of random third-dimension measurements. One proprietary program for this purpose was mentioned in an earlier issue of this journal (Description of GPCP program, Computer Aided Design Winter 1970, p.52). The third dimension can represent h e i g h t - e . g , of physical terrain or a three-dimensional part, or pressure - e.g. associated with a weather map, or pressure distribution around an aerofoil or pump rotor, or temperat u r e - e.g. temperature distribution within an internal combustion engine cylinder block•
++
30
?. ~ C ~
st~ooe
TO mOll+J[ c | oN ¥(s+c+ Y - 1 0 3
IIOI-E+i-I-IS~
.m+.w,
+1,=
=•-c•r.t/%&*]~
.~ • Ill
..............
.. . . . . .
.II • II'
se-u~-~,
. m - lP
.P.l. w"
. m • *~* .m • w, a m . W*
. m ~1 am . ~ , *
,. . . . . . . . .
.,
o.
Ii
wo,ts
* • co~+• ~ | + - + * s l , ' ~ l <
~m.ll.
~m. P
+.• ~ +.•..
.
:i:+ i
FiV.
J+l. I*
~¢•s,.=-~:
,=-+.•.-+o
i I!
~[.h.X.•z
•
. m .w¢,
.=== • W . . m
HUMPHR£Y$
• m.
:![ ..... olo
bridge design - see Fig. 2. preparation of drawings of the logic design of computers - using the LIDO system (Logic In, Diagrams Out) (see Fig. 3). Highway d e s i g n - based on varied input specifications. A typical example is shown in Fig. 4. Mechanical draughting of parts. Fig. 5 shows a cam draughted in this way. COMPUTER AIDED DESI6N
+
Plotting PERT (Critical Path Method) diagram. Fig. 6 shows same diagram (see also Computer Aided Design, Autumn 1969, p. 47). For checking finite element analyses before extensive computation (see Fig. 7). Chemical plant pipework layout and detailing. Fig. 8 shows a sample of output from the Humphries & Glasgow/NCC R A P I D system. Drawings of varying detail, scaled in a nonlinear fashion to 'shorten' pipe runs with little detail, can be produced at will by inserting varying numbers of pipe records, and plotting corresponding drawings. In a lighter view, for use as a relaxation by engineers. Fig. 9 shows an example!
I
only' facilities are needed. It is worthy to note that a c.r.t. display and a plotter can share the same display f i l e - the former scanning the file ten times each second (typically), whilst the latter scans the file once only for each copy drawn, though at a much lower scanning rate, in terms of scan time per drawing element (line, circle, axis, etc.). The other alternative, electrostatic plotters, offer low quality output on a short timescale, but their basic principle of synthesising pictures from discontinuous dots prevents them from competing with pen type plotters when draughted drawings of high quality are required. They are best regarded as a 'quick look' or 'quick record' hard copy device, when speed is important, and accuracy less so. Summarising, pen type plotters enable high quality drawings to be prepared, as an alternative to handdraughted drawings. Considerable economic benefits ensue when the plotter is used on the final output peripheral, following design calculations by computer, since it eliminates the costly alternative line printer -~ numeric table ~ draughtsman ~ drawing interface.
Dr. F. E. Taylor is responsible for Technical Field Support for the Membership and Advice Division of the National Computing Centre, previously occupying posts with that body as Development Officer, and Head of its Interactive Computing Department.
F~O. 9 Plotters compared w i t h other Graphic Devices Cathode ray t u b e - based display systems were dealt with in detail in two articles and a survey in the previous issue of Computer Aided Design (Spring 1971), and in the preceding issue (Winter 1971) mention was made (on p. 32) of electrostatic terminals, capable of producing graphical data. Pen type plotters have the advantage that hardcopy of good quality, using varying pen widths and colours where needed, can be produced, though on a longer timescale than is the case with the other two devices. C.r.t. displays are irreplaceable for interactive working within a timescale of minutes, and when 'quick-look' and 'softcopy
U.K. Remote multi-access systems for the engineer This important survey, which appeared in the Winter 1971 issue of 'Computer Aided Design', is now available as a separate booklet. All the information you need on time-sharing and remote batch processing from the design engineers view-point is contained in this booklet, Supplies are limited, order yours now at the special Datafair price of 75p (postage 5p) while stocks last (normal price is £1.25), from The Editor, Computer Aided Design, Dorset House, Stamford Street, London, S.E.1. SUMMER 1971
A~bove is our CORAD,OMAT 21 c0mpu,ter-controlled drafting machine. The working area of this machine is 63 in. x 51 in. and the accuracy of the electronic positioning system is of the order of one-thousandth of an inch. This machine has been sold to many customers throughout the world for applications in map-making and drawing, microelectronics, printed circuit design, and general engineering drawing. The machine is now in full production at our
Haddin~ton factory.
The OORA,DOIMAT 21 is only one of a range of high-accuracy measuring and drafting systems manufactured by Faul-Coradi ('Scotland) Limited and we have already achieved w o r l d - w i d e recognition for our work in the field of astronomy with such machines as GA,DAXY.
Faul-coradm EV~I~IDE,H A D ~
EASTL01-11~SCOT1.N~Ul~
Telephone Haddington 2621
31