Coding switch assembly

Apparatus for setting and displaying a numerical value to be encoded to an electronic device, including a molded plastic support structure, a printed circuit board membrane type switch assembly which is affixed to the support structure and which includes a plurality of rows of four switches, and a like plurality of molded plastic switch actuator shafts associated respectively with the rows of four switches. Each actuator shaft has a longitudinal axis extending parallel to the associated row of four switches, and is pivotally connected to the support structure for rotation about its axis. Each shaft includes a plurality of raised annular segments for opening and closing the four switches in the adjacent row. The segments are arranged so as to provide ten combinations of open and closed switches as the shaft is rotated, to provide a 4-bit binary code corresponding to one of ten numbers 0-9, depending on the rotary shaft position. Also, each shaft includes the ten numbers 0-9 disposed about the shaft axis on the front surface of a shaft flange such that the number adjacent an indicator on the support structure corresponds to the binary code setting. The numbers 0-9 carried by each actuator shaft are oriented such that the indicated numbers are readable as a discrete number in standard decimal format corresponding to the numerical value to be encoded.

BACKGROUND OF THE INVENTION 
The invention relates generally to numerical encoding devices for 
electronic circuits. More particularly, the invention relates to a coding 
switch, utilizing a printed circuit board switch assembly for setting and 
displaying a time value to be encoded to an electronic artillery fuze. 
Several types of fuzes used on artillery amunitions require the setting of 
an event time prior to firing. The fuze setting time system must be a 
rugged, compact system, in which the time value can be accurately set and 
displayed, without the use of electric power. In the past, this has often 
been done by turning the fuze nose relative to markings on the fuze body, 
for example, to adjust a timing cam of a mechanical timer or a timing 
resistor of an electrical timer. In such a system, the number of possible 
time settings is limited by the requirement that the selected time setting 
be legibly displayed on an exterior surface of the fuze. 
OBJECTS AND SUMMARY OF THE INVENTION 
It is an object of the invention to provide a simple, low cost, coding 
switch assembly for manually setting and displaying a numerical value to 
be encoded to an electronic device. 
It is a further object of the invention to provide such a coding switch 
assembly, in which the selected numerical value is displayed as a discrete 
readable number, in standard decimal format. 
It is another object of the invention to provide a coding switch assembly 
for manually setting and displaying a time value to be encoded to an 
electronic artillery fuze. 
The coding switch assembly, according to the invention, includes the 
printed circuit board membrane type switch assembly affixed to a support 
structure. The switch assembly includes a plurality of pressure actuated 
switches arranged in straight rows of at least four switches, with both 
sides of each switch being connected to terminals carried on the circuit 
board. Generally, one side of each switch will be connected to an 
individual terminal while the other side of each switch will be connected 
to an common ground terminal. 
The coding switch assembly also includes a plurality of switch actuator 
shafts, corresponding in number to the number of rows of the switch 
assembly, which are rotatably supported by the support structure so that 
each actuator shaft can be individually rotated by manual means about its 
longitudinal axis. Each actuator shaft is disposed so that its axis of 
rotation extends above and parallel to a corresponding row of switches of 
the switch assembly. Each actuator shaft includes a plurality of raised 
portions or protrusions corresponding to the switches in the adjacent row. 
Each shaft protrusion is disposed adjacent one of these switches, such 
that the shaft protrusion opens and closes the switch as the shaft is 
rotated about its axis. The protrusions of each actuator shaft are formed 
so as to provide ten different combinations of opened and closed switches 
in the adjacent row at corresponding positions of the actuator shaft as 
the shaft is rotated about its axis. The ten combinations of open and 
closed switches in each row constitute multibit codes corresponding to the 
numbers 0-9, respectively, which are encoded to the electronic device. 
Thus, when binary coding is utilized, each row of switches will include 
four switches which are actuated open or closed by the adjacent actuator 
shaft to generate binary codes corresponding to the numbers 0-9. 
One end of each actuator shaft is slotted and extends through a front 
portion of the support structure so that each shaft can be individually 
rotated to a desired position by an operator using a conventional 
screwdriver. Each actuator shaft includes a flange which carries the 
numbers 0-9 on its front surface corresponding to the ten positions of the 
actuator shaft. The flange of each actuator shaft is positioned adjacent 
the front portion of the support structure, which includes an opening 
therethrough so that one of these numbers on the flange can be viewed by 
the operator to properly set the row of switches to provide a multibit 
code corresponding to that number. Since all the actuator switches are 
disposed in the common plane, the displayed numbers of these actuator 
shafts, as seen by the operator, constitute the numerical value to be 
encoded to the electronic device. To accomplish this, the numbers in each 
row of switches is appropriately weighted and added together in the 
electronic device. For example, if the least significant number of the 
numerical value, that is, the number on the right, corresponds to a time 
setting in tenths of a second, the adjacent row of numbers to the left of 
the least significant number will correspond to time settings in seconds, 
and the next adjacent row of numbers will correspond to time settings in 
tens of seconds. 
In another embodiment of the invention, the numbers 0-9 for each actuator 
shaft are disposed on the front surface of the support structure around 
the actuator shaft, which carries an arrow or other indication mark on its 
end surface which is aligned with one of the numbers 0-9 to indicate the 
number to be encoded to the electronic device. 
Also, to reduce the cost of this coding switch assembly, the support 
structure and the individual actuator shafts can be molded plastic 
elements. Such a low cost coding switch is particularly useful in 
applications where this coding switch is expendable, for example, as the 
coding switch of an electronic artillery fuze for setting and displaying a 
time value to be encoded to the fuze upon firing of the artillery 
projectile.

DESCRIPTION OF PREFERRED EMBODIMENTS 
The coding switch assembly 10 shown in FIG. 1 includes a generally U-shaped 
molded plastic support structure 12 having a front portion 14, a rear 
portion 16, and a recessed center portion 18. A 4.times.4 double-sided, 
printed circuit board membrane type switch assembly 20 is disposed on the 
center portion 18 of the support structure 12. Four identical, molded 
plastic actuator shafts 22, 24, 26, 28 are pivotally connected to the 
front and rear sections 14, 16 of the support structure 12 for rotation 
about their respective longitudinal axes A-A, B-B, C-C, and D-D, which 
extend in a plane parallel to that of the switch assembly 20. The front 
end 30 of each actuator shaft extends through the support structure front 
portion 14 and includes a slot 32 therein, into which a screwdriver may be 
inserted by an operator to manually rotate each actuator shaft about its 
axis. 
The switch assembly 20 includes sixteen pressure-actuated, membrane type 
switches arranged in rows of 4 switches directly below the actuator shaft 
axes A-A, B-B, C-C, and D-D, respectively. Each row of switches 
constitutes a four-bit binary code which is supplied to an electronic 
device. For convenience, the switches have been identified by the adjacent 
actuator shaft axis and the weight given each switch. For example, the 
four switches in the row of switches directly beneath the actuator shaft 
28 are identified as switches D1, D2, D4, and D8. A group of terminals 34, 
which are disposed on the left side of the switch assembly 20, as shown in 
FIG. 1, are connected to the 16 membrane type switches to facilitate the 
connection of the switches to the electronic device. As shown in FIG. 2, 
one side of each of these switches is brought out to an individual 
terminal, while the other side of the switches are connected to a common 
ground terminal 36. 
Each actuator shaft includes a plurality of raised annular portions or 
segments 40, 42, 44, and 46 which are respectively disposed along the 
length of the shaft adjacent the membrane switches of the switch assembly 
20, so that each segment will open and close an adjacent switch of the 
switch assembly 20 as the actuator shaft is rotated. The number and 
distribution of these annular segments is shown in FIG. 3. Thus, each 
actuator shaft includes five annular segments 40 disposed uniformly about 
the shaft axially adjacent the switch A1, B1, C1, or D1 of the adjacent 
row having the least weighted value. Similarly, each actuator shaft 
includes two annular raised segments 42 axially adjacent the switch A2, 
B2, C2 or D2 in the adjacent row of switches having a weighted value of 2. 
Each actuator shaft includes a raised segment 46 axially adjacent the 
switch A4, B4, C4, or D4 in the adjacent row of switches having a weighted 
value of 4. Finally, each actuator switch includes an annular raised 
segment 46 axially adjacent the switch A8, B8, C8, or D8 in the adjacent 
row of switches of the switch assembly 20 having a weighted value of 8. As 
seen in FIG. 3, each actuator shaft may be rotated to provide 10 binary 
codes from 0 to 9 to be provided to the electronic device. 
Any conventional printed circuit board membrane type switch assembly may be 
used for the switch assembly 20. For example, the switch assembly 20 shown 
in FIG. 12 is similar to that described in U.S. Pat. No. 3,761,944, issued 
Sept. 12, 1973 to Shimojo. It includes a substrate 47 of rigid insulating 
material and a cover member 48 formed of a single integral sheet of 
resilient insulating material. Each of the 16 membrane switches, such as 
the switches D4 and D8 shown in FIG. 12, includes a resilient electrically 
conductive contact member 49 affixed to the cover member 48 and extending 
above the common ground terminal 36 and an adjacent one of the terminals 
34. As shown in FIG. 12, when the actuator shaft 28 is rotated so that its 
raised segment 46 is brought into contact with the cover member 48, the 
contact member 49 directly beneath the actuator shaft 28 is moved downward 
to establish contact between the ground terminal 36 and the adjacent 
terminal 34. 
Each actuator shaft 22-28 also includes a flange 50 similar to that shown 
in FIG. 9, bearing the series of ten numbers 0-9 spaced uniformly about 
its front surface. The front portion 14 of the support structure 12 
includes four openings 52, 54, 56, and 58 disposed respectively above the 
actuator shafts 22, 24, 26 and 28, so that the topmost member on the 
flange 50 of each actuator shaft may be viewed therethrough. These numbers 
are arranged on the flange 50 of each actuator shaft so that the number 
seen through the opening 52, 54, 56, or 58 associated with that shaft 
indicates the number, in binary code, to be encoded to the electronic 
device. In the electronic device, the number encoded by the second shaft 
24 is multiplied by 10, the number encoded by the third shaft 26 is 
multiplied by 100, and a number multiplied by the fourth shaft 28 is 
multiplied by 1000, and all of these multiplied numbers are added to the 
number encoded by the first actuator shaft 22. Thus, the numerical value 
to be encoded to the electronic device is displayed within the openings 
52-58 as a discrete, readable number, in standard decimal format. The 
4-shaft coding switch assembly 10 will produce and display 10,000 discrete 
settings, from 0 to 9999, using basically only six component parts. 
There are other methods of displaying the numerical value to be encoded to 
the electronic device. For example, the front end 30 of each actuator 
shaft can also constitute the front surface of the flange 50 carrying the 
numbers 0-9, as shown in FIG. 4, in which case, the support structure 
front portion 14 includes four indicator marks 59 adjacent the four 
actuator shafts, respectively, for indicating the actuator shaft settings. 
Also, the series of numbers 0-9 can be disposed on the support structure 
front portion 14 about each actuator shaft 22, 24, 26 and 28, as shown in 
FIG. 5, in which case, each actuator shaft end 30 includes an arrow 60 or 
other indication mark to position the actuator shaft at the desired 
setting. However, the display system shown in the device of FIG. 1 is 
preferred, since only the numerical value to be encoded is seen by the 
observer as a properly orientated, readable number. 
The matrix switch assembly, the actuator shafts, and the support structure 
can be assembled in various ways. For example, each actuator shaft may 
have a rear flange or collar 62 of maximum diameter, which rotates within 
openings in the rear portion 16 of the support structure 12. The actuator 
shafts are inserted through these openings in the support structure rear 
portion 16. Also, the rear portion 16 may include a groove 64 into which a 
wedge 66 is inserted to limit the end play of the actuator shafts 22, 24, 
26 and 28. The inner surfaces of the front and rear portions 14, 16 of the 
support structure may include grooves 68, 70, to guide and position the 
printed circuit board matrix switch assembly 20. Another simple way of 
assembling this device would be to form the support structure 12 as two 
elements, which are affixed to each other during assembly by epoxy, 
screws, or the like. 
In the embodiments shown in FIGS. 6-9, a 3-shaft coding switch assembly 72 
having a 3.times.4 printed circuit board membrane type switch assembly 74 
is used to set and display a time value to be encoded to an electronic 
fuze for an artillery projectile upon firing of the projectile. The coding 
switch assembly 72 includes a molded plastic support structure 76, and 
three identical molded plastic actuator shafts 78, 80 and 82 which are 
pivotally carried by the support structure 76 for rotation about their 
longitudinal axes E-E, F-F, and G-G, respectively, which are disposed in a 
plane parallel to the plane of the printed circuit board switch assembly 
74. The actuator shafts 78, 80, 82 are functionally identical with the 
actuator shafts 22-28 of the coding switch assembly 10 shown in FIG. 1, 
and include the same number and disposition of annular raised segments 40, 
42, 44, and 46 as the actuator shafts of FIG. 1. Also, each actuator shaft 
78, 80, 82 includes a front flange 50 having 10 members 0-9 inscribed or 
printed about its front surface, and a slotted end 30 which projects 
through an opening in a front portion 84 of the support structure 76, in 
the same manner as described above for the actuator shafts 22-28 of FIG. 
1. The support structure front portion 84 includes three openings 86, 88, 
90 above the actuator shafts 78, 80, 82, respectively, through which the 
number on each front flange 50 adjacent these openings can be viewed, in 
the same manner as described above for the coding switch assembly 10. The 
coding switch assembly 72 is mounted in the housing 92 of an artillery 
electronic fuze, with the outer surface of the support structure front 
portion 84 being formed to be essentially flush with the outer surface of 
the fuze housing 92. 
The chief difference between the coding switch assembly 72 and the coding 
switch assembly 10 described above is that the axes of rotation E-E, F-F, 
G-G of the actuator shafts 78, 80 and 82, respectively, are disposed at an 
angle to each other to better conform the exposed front surface of the 
coding switch assembly 72 to the outer surface of the fuze housing 92, 
whereas, in the embodiment of FIG. 1, the axes of rotation of the four 
actuator shafts are disposed parallel to one another. Because of this 
arrangement, the support structure 76 and the printed circuit board switch 
assembly 74 are shaped so as to extend partially about the axes O-O of the 
fuze housing 92, as shown in FIGS. 6 and 8. 
The printed circuit board switch assembly 74 includes three rows of 
pressure-actuated membrane type switches disposed directly beneath the 
three actuator shafts 78, 80, 82, respectively. Each actuator shaft 78, 
80, 82 can be set by an operator using a screwdriver to provide a 4-bit 
binary code to the electronic fuze corresponding to the displayed number 
on the front flange 50. During operation of the fuze, the three encoded 
4-bit binary codes are processed by conventional circuitry to provide time 
delay corresponding to the displayed time setting, that is, a time delay 
which is equal, in time units (seconds, tenths of seconds, or the like) to 
the number visible through the opening 86 plus the number visible through 
the opening 88 times 10 plus the number visible through the opening 90 
times 100. For example, if the displayed numerical setting of the coding 
switch assemblies 72 indicates the encoded time value in tenths of a 
second, the three 4-bit binary codes can be loaded into three cascaded 
counters in a timing circuit of the fuze, which are arranged so that the 
first counter counts in 0.1 second intervals, the second counter counts in 
one second intervals, and the third counter counts in ten second 
intervals. The 4-bit code generated by the actuator shaft 78 is loaded 
into the first counter; the 4-bit code generated by the actuator shaft 80 
is loaded into the second counter, and the 4-bit code generated by the 
actuator shaft 82 is loaded into the third counter. 
FIGS. 10 and 11 show a 4-shaft coding switch assembly 94, similiar to the 
embodiment of FIG. 4, which is mounted in the housing 96 of an electronic 
artillery fuze such that the parallel axes A-A, B-B, C-C, D-D of the 
actuator shafts 22, 24, 26, 28 intersect the fuze housing axis O-O. The 
coding switch assembly 94 is used to set and display one of 10,000 
discrete time settings to be encoded to the electronic fuze, in the same 
manner as described above for the embodiment of FIGS. 6-9. 
There are many variations and modifications of the invention which would be 
obvious to one skilled in the art. For example, electronic circuits could 
be mounted on the matrix switch printed circuit board. Various means of 
coding the actuator shaft rotary positions, such as decimal, binary, 
complementary, etc. could be used, and parity codes could be used to 
detect and correct coding errors. The switch assembly could be formed as a 
flexible tape assembly, rather than as a rigid circuit board assembly. The 
front ends of the actuator shafts could be formed to receive and engage an 
Allen wrench or a Phillips screwdriver. Since there are many variations, 
modifications, and additions to the specific embodiments of the invention 
described herein which would be obvious to one skilled in the art, it is 
intended that the scope of the invention be limited only by the appended 
claims.