Postscript Encoder Disk

This Postscript code will produce an encoder disk sutable for a rotational motion sensor when used with a photodetector.

Areas in the code can be changed to modify the characteristics of the disk that is generated. Look for the comments starting with "%".

Also:

• /techref/member/D-Mot-l1/index.htm Modified to provide A and B disks for Quadrature Encoding.+

%!PS-Adobe-2.0
%%Title: Encoder Disk  
%%Creator: (C) Ricardo Seixas - rseixas@pobox.com 
%%CreationDate: May 12 2000
%%EndComments
% You can freely distribute and use this file as long as you maintain the original copyright 
% This file is provided as is and there's NO WARRANTY
% Use it at your own risk

/mm {2.8346 mul} def   
/pi 3.1415926536 def   

%
%
%Here you can change the encoder characteristics

/slots 45 def
/external_diameter 50 mm def

/internal_diameter external_diameter 10 mm sub def
%/internal_diameter 45 mm def   
/text ( Ricardo Seixas 2000 - rseixas@pobox.com - Encoder Disc ) def 	% don't remove the parentheses when you change text!!!  
/text_diameter internal_diameter 2 mm sub def
%/text_diameter 43 mm def
/font_size external_diameter 20 div def 
%/font_size 6 def
/font_type (Courier) def
%/internal_circle 38 mm def
/internal_circle internal_diameter font_size mm sub def
%
%
%
%Look at the end of the file for positioning


/angle {360 slots div} def
/trace_width {internal_diameter pi mul slots div 2 div} def
/center_hole {

	%Cross
	-11 mm 0 moveto 22 mm 0 rlineto 0.2 setlinewidth stroke
	0 -11 mm moveto 0 22 mm rlineto 0.2 setlinewidth stroke

	%Bulls Eye 6 mm
	0 0 6 mm 2 div
	0 360 arc .2 setlinewidth stroke  
	%Bulls Eye 8 mm
	0 0 8 mm 2 div
	0 360 arc .2 setlinewidth stroke  
	%Bulls Eye 10 mm
	0 0 10 mm 2 div
	0 360 arc .2 setlinewidth stroke  
	%Bulls Eye 20 mm
	0 0 20 mm 2 div
	0 360 arc .2 setlinewidth stroke 
	
	%Draw internal circle
	%Comment the two lines below if you don't want internal circle before font  	

	0 0 internal_circle 2 div
	0 360 arc .05 setlinewidth stroke 
	 
	%Draw internal_diameter circle
	%Comment the two lines below if you don't want internal circle after font  	

	0 0 internal_diameter 2 div
	0 360 arc .05 setlinewidth stroke 

	%Draw External Circle
	%Comment the two lines below if you don't want external line  	

	0 0 external_diameter 2 div
	0 360 arc .05 mm setlinewidth stroke 
	
	
	} def
%Don't mess around here unless you know what you're doing
/Draw_Disc {
		0 0 moveto  
		gsave
		angle 2 div rotate
		
		0 angle 360
		 	{
			gsave 
			rotate
			internal_diameter 2 div 0 rmoveto
			external_diameter internal_diameter sub 2 div 0 rlineto
			trace_width setlinewidth
			stroke
			grestore
			} for
		grestore
		center_hole
		} def



% Text routine borrowed from Adobe Blue Book Program 10, on page 167
/insidecircletext
  { circtextdict begin
	  /radius exch def  /centerangle exch def
	  /ptsize exch def  /str exch def
	  
	  /xradius radius ptsize 3 div sub def
	  gsave
	    centerangle str findhalfangle sub rotate
	    str
		  { /charcode exch def
		    ( ) dup 0 charcode put insideplacechar
		  } forall
	  grestore
	end
  } def
  
/circtextdict 16 dict def
circtextdict begin
/findhalfangle
	{ stringwidth pop 2 div
	  2 xradius mul pi mul div 360 mul
	} def
	
/insideplacechar
  { /char exch def
	/halfangle char findhalfangle def
	gsave
	  halfangle rotate
	  radius 0 translate
	  90 rotate
	  char stringwidth pop 2 div neg 0 moveto
	  char show
	grestore
	halfangle 2 mul rotate
  } def
  
end


/font_type findfont font_size scalefont setfont
/Encoder_Text {
		text 18 -90 text_diameter 2 div insidecircletext
	       } def	

/Draw_Encoder {
	  Draw_Disc
	  %Comment next line to remove text
	  Encoder_Text
	  } def

%Here you can change where you want to put the disk on the sheet
%TODO automagicaly fill a A4 or A3 sheet

%automatic placement
external_diameter 2 div 15 mm add external_diameter 2 div 15 mm add translate Draw_Encoder

%manual placement, you can put more than one encoder on the same sheet				
%30 mm 30 mm translate Draw_Encoder
%52 mm 0 mm translate Draw_Encoder

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