Modified typewriter mechanism with standard logic components provides digital plot of output of multichannel analyzer. Unit plots irregular curves at approximately 14 channels per second, and smooth curves at over 25 channels per second, and is not subject to analog error or drift

Gray, J., Jr.

English

NASA Technical Reports Server

March 1971	 RM. 1313	 Brief 71-10049 
KSC HQS. 
,IcY co	 - 
AEC-NASA TECH BRIEF 
US	
AEC Headquarters 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield; Virginia 22151. Requests for individual copies or questions relating to the. Tech Brief program may 
be directed to the Technology. Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
High-Speed Digital Plotter 
Multiple 
Channel 
Analyzer
No. 1 
Fire 
	
_	
No. 2 
	
_	
t 
	
Steering I	 Memory
[-i_..__._ r_11 Board Board Board Board	
r'- I	 I	 No.3 
10 Point Hammer
Solenoids 
Switch
Hammer Bar Cam 
Hammer Bar Cam 
Platen	 Board	 To Memory Boards 
Advance	 Clear 
Register
	
	
Address 
Block Diagram of Digital Plotter 
The problem: 
To provide a digital plot of the output from a multi-
channel analyzer. The techniques and equipment used 
to perform this function should be capable of high-
speed and flexible operation in producing irregular 
as well as smooth curves. Prior methods require the 
use of complex and expensive equipment, and are 
generally capable of plotting only 2 to 7 channels/sec. 
Typical commercial plotters are controlled by analog 
voltages from the analyzer, and are subject to ampli-
fier drift. Log diodes in the analyzer cannot decode 
more than two significant digits. 
The solution: 
A modified typewriter mechanism 6ontrolled in both. 
axes by digital signals. Standard logic components, 
e.g., shift registers, memory elements, and adders, are 
used to provide a high-speed, flexible, and inexpensive 
means of controlling the plotter. The unit can plot 
irregular curves at approximately 14 channels/sec, and 
smooth curves at over 25 channels/sec, and is not sub-
(c,itiiiticd overleif) 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19710000049 2020-03-17T02:18:31+00:00Z
ject to analog error or drift. It is capable of decoding 
three significant digits. 
How it's done: 
The mechanical components consist of a basic type-
writer frame and platen mechanism, with the keys and 
type removed. Ten equally spaced, solenoid-operated 
hammers mounted on a movable hammer bar (trans-
lation carriages) are positioned horizontally along the 
longitudinal axis of the platen. The translation car-
riage, operated by two cam assemblies, may select any 
one of 100 discrete positions between the solenoid 
hammers. Thus point-plot information is "typed" using 
ordinary paper and typewriter ribbon in an operation 
similar to the action of a standard typewriter. The 
electronic components consist of three memory boards 
and associated logic circuitry to provide the analyzer/ 
plotter interface. 
The analyzer output for a given channel is repre-
sented in five decades, with the first decade being un-
used, i.e., having no stored iuformation. The digits of 
each decade are transmitted to the plotter over ten 
output wires connected in parallel with memory boards 
1, 2, and 3. As the analyzer sweeps through its decades, 
a pulse is produced for each decade and transmitted 
to the steering board. The selector switch is ,preset to 
extract the first four consecutive pulses from the steer-
ing board, with the remaining pulses being discarded. 
The first extracted pulse transmitted to memory board 
I is a "fire command" which instructs the memory 
board to fire, or energize, the "0" hammer solenoid, 
since the first analyzer decade contains no stored in-
formation. This step provides a reference base for 
the subsequent digits, or intervals of interest. Assume 
now that 521 is the number to be plotted. The second 
extracted pulse is stored for future use in memory 
board I, and represents the first analyzer decade 
containing the desired information, in this case the 
digit 5. The third pulse, representing the digit 2, is
transmitted to memory board 2 which actuates the 
first set of cams, and moves the hammer bar two-
tenths of the distance between the hammer solenoids. 
The fourth pulse, representing the digit 1, is trans-
mitted to memory board 3 which actuates the second 
set of cams, and moves the hammer bar one-hundredth 
of the distance between the hammer solenoids. Thus 
the hammer bar is now displaced from its normal zero 
position by 0.21 of the distance between two hammer 
solenoids. On the next sweep of the analyzer through 
its decades, the first pulse will command memory 
board I to "fire." However, the memory board now 
contains stored information, and the sixth solenoid, 
corresponding to the digit 5, energizes. Since the 5 
digit is displaced 0.21 from its normal zero position, 
the point plotted is 521. The first pulse also actuates 
the platen advance and clears the memory boards so 
that the next channel may be read out. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Division of Technical Information 
AEC Headquarters 
Washington, D.C. 20545 
Reference: B71-10049 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to: 
Technology Utilization Officer 
.Division of Technical Information 
AEC Headquarters 
Washington, D.C. 20545 
Source: James Gray, Jr.
Chemistry Division 
(A RG-9000 I) 
Brief 71-10049	 Category 02


High-speed digital plotter

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server