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Патент USA US3035204

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May 15, 1962
s. G. HUGHES
'
3,035,190
DIGITAL TIMERS
Filed Nov. 27. 1959
INVENTORZ
STANLEY G. HUGHESJ
BY 75. W
HTS ATTORNEY.
Unite States
r‘ice
3,035,190
Patented May 15, 1962
1
2
3,035,190
Stanley G. Hughes, Devon, Pa, assignor to General Elec
circuit to ground through the kicker arm. This second
kicker arm ground permits the current to continue to ?ow
through both the solenoids attracting a counter arm to the
counter arm solenoid which breaks a reset switch discon
necting the voltage source from the solenoids. The
DIGKTAL T§MER§
tric Company, a corporation of New York
Filed Nov. 27, 1959, Ser. No. 855,706
3 Claims. (Cl. 307-141..‘1)
counter arm motion drives a counter ratchet registering
a count by advancing its motion one tooth. Both the
arms then return to their initial position, breaking the cir
The present invention relates to a digital timing device
and more particularly to a digital timer for converting
cuit to ground through the kicker arm and closing the
10 reset switch. When the balance wheel returns to its initial
balance wheel oscillations to timed electrical pulses.
Generally, a timer is a form of clock or time keeping
position after a constant period of time determined by the
device which, like a stop watch, can be started at some
natural frequency of the balance wheel-hair spring system,
particular instant and after a prescribed time interval,
the circuit to ground through the balance wheel arm is
will cause a switch closure to be effected. Accordingly, a
recl-osed such that this cycle is repeated. The cycle re
timer consists of an energy source, a time-rate generator 15 peats itself until the counter ratchet registers a preselected
and means of recording elapsed time and to effect switch
number of counts rotating ‘a timer cam and actuating a
closure at the completion of a preset elapsed time.
switch indicating the end of one complete timing interval.
Time-rate generators ‘are generally mechanical or elec
The features of the invention which are believed to be
trical wherein the mechanical form may consist of a
novel are set forth with particularity in the appended
periodic rotation of a balance wheel and hairspring. 20 claims. The invention itself, together with further objects
The RC circuit is a typical electrical time-rate generator
and advantages, may best be understood by reference to
in which electrical charge is accumulated on a condenser
as .a function of time. A disadvantage of this is that the
the following description when taken in connection with
the accompanying drawing which illustrates a schematic
timing accuracy is dependent on the constancy of the
View of ‘a preferred embodiment of the invention.
power supply and the RC values. A crystal oscillator is 25
Referring now to the drawing, there is illustrated a
another form of an electrical time-rate generator, but the
preferred embodiment of the invention. The counter por
frequency is high and has to be divided before mechanical
tion, which is outlined in general by the dashed line 10,
counters can be effectively driven.
will be described ?rst. The counter 10' consists of a coun
The optimum means of recording elapsed time is be
terarm 11 pivoted about a support 12 to drive a counter
lieved to be based upon a relatively large digital or step 30 ratchet 13 by means of an extension 14 on counter arm 11.
motion. To understand the advantage of digital motion,
Counter ratchet 13 is mounted on an axle 15 ‘for rotation.
consider a typical non-digital elapsed time recorder which
A timing cam 16 is also mounted on axle 15 for rotation
consists of a rotating cam.
When the cam rotates;
with ratchet 13. Timer cam 16 has ‘an indentation 17 for
through a prescribed angle corresponding to a prescribed
receipt of a cam wheel 18 after the cam 16 had rotated
elapsed time, the camming surface closes a switch. With 35 through each preset timing interval. The wheel 18 is
digital motion, position changes discretely each timing
springébiased toward the cam 16 by means of a spring 19
increment. Information is not available in such a device
vwhich isbi-ased in compression against a support 2% on
one extremity and a circular plate 21 at its other extremity.
regarding the elapsed time between increments but the
sudden jump~rotation at each increment provides a precise ’ , The cam wheel 18 is connected to circular plate 21 by
means of a yoke 22 and an axle 23. This entire cam
indication of the total number of increments that have. 40
elapsed. On the other hand, with a continually moving
cam, there is always some timing error since the angle
of rotation cannot be precisely determined. Consequently,
wheel is biased by spring 19 to move along the axis of the
rod 24, such that when wheel 18 enters indentation 17 at
the end of a timing period, contacts 25 are connected by
a more efficient and highly useful timer would be a
the contact arm 26 to complete a series circuit between
unique combination of the optimum timer elements, that 45 voltage source 27 and load 28 which are connected in
is, an electrical power source, a balance wheel and a
series across contacts 25.
hair-spring, and a means for recording digital motion.
A typical prior art timer .consists of a chronometrically
A drive for counter arm 11 is provided by a counter
arm solenoid 29. Counter arm d1 also has on its ex~
governed ‘DC. motor which has a shaft which rotates at
‘a uniform speed. Such a timer is unduly complicated due
tremity opposite support 12 a mechanical contact button
30 for driving arm 31 down to open the normally closed
reset switch contacts ‘32 by depressing reset switch con
tact arm 33. Contact arm 33 is kept normally closed
when not driven down by counter arm 11 by means of a
spring 34 acting against contact arm 33‘ and a support 35.
to the use of the motor and reduction gearing. Such a
timer ‘also is inaccurate when ?rst actuated due to motor
inertia. For operation at high speeds over relatively long
time intervals such a timer requires relatively large switch
closing cams.
55
A source of potential 36 for operating the timer is
An object of the present invention is the provision of a
connected between ground and the contact 32 remote
digital timer without complex motion transmission means
from solenoid 29. Thus when contact arm 33 is in its nor
which would increase the cost and reduce the e?iciency
mally closed position, source of potential 36‘ is connected
thereof, having high speed motion at critical time inter
by means of lead 37 to one side of solenoid 29. The
vals, during which time intervals information is not re 60 other side of solenoid 29', or lead 38, is connected to
quired.
Another object is to provide a compact digital timer
which can be started at a particular instant and will oper
ate for a given time period and then effect a switch closure
‘at the completion of the given interval.
In carrying out the invention in one form thereof, a
voltage source supplies a current through a counter arm
solenoid, ‘a kicker arm solenoid and a balance wheel con
one side of a kicker arm solenoid 39.
Solenoid '39 is associated with ‘a kicker arm 40 which
is pivoted to rotate about the axis of axle 41. Kicker
arm v40 is spring-biased away from solenoid 39 by means
65 of a spring 42 connected between kicker arm 40 and a
support point 43. Spring 42 biases kicker arm 40 against
stop 44.
The kicker arm 40 is electrically conducting and when
tact to ground, by closing a starter switch. The kicker
it is attracted to solenoid 39‘ it will make electrical con
arm solenoid then attracts a kicker arm which propels the 70 tact through the arm 40 and contact 45 on one end of arm
balance wheel, thus breaking the circuit through the
40 over lead 46 to ground. The other end of kicker arm
balance wheel contact to ground and making a second
40, pivoted around the axis of axle 41, contains a contact
3,035,190
3
arm 47 which is a leaf spring slightly biased against an
extension 48 on balance wheel 49. Balance wheel 49 is
mounted on an axle 50 which is also provided with a
spring 51 which together with balance wheel 49 constitutes
a balance wheel-hairspring system having a given period
of oscillation which may be utilized for timing purposes.
The extension 48, balance wheel 49 and axle 50 are all
4
magnetizing force and resultant strength of the kick im
parted to kicker arm 40. The base structure magnetic
and electrical circuits may be laminated to reduce eddy
current losses and provide a more e?icient magnet.
An isochronous spring may be employed for spring 51
to minimize variations in natural frequency of the bal
ance wheel spring system due to amplitude variations.
, While a particular embodiment of the invention has
been ‘described it will be understood of course that it is
a lead 52 to ground.
The timer may be actuated by closing a switch 53 which 10 not intended to limit the invention thereto, since many
modi?cations may be made and that it is therefore con
is connected between source of potential 36 and the con
templated by the appended claims to cover any such modi
tact 32 remote from solenoid 29. When switch 53 is
?cations as fall within the true spirit and scope of the
closed the operating cycle of the timer is initiated. This
invention.
cycle is as follows:
Upon closing switch 53, source of potential 36 is con 15 What is claimed as new and desired to be secured by
electrically conducting and are connected from axle 59 by
nected through normally closed contacts 32, solenoid 29,
solenoid 39, kicker arm 40, contact arm 47 , extension 48,
balance wheel 49 and axle 50 to ground through lead 52.
Letters Patent of the United States is:
l. A digital timer comprising a digital electromechan
ical counter means, a balance wheel-spring oscillatory sys
tem having a balance wheel with a given natural fre
The resulting current serves to attract both kicker arm
40 ‘and counter arm 11 to their respective solenoids 39 20 quency, a kicker arm system having a kicker arm, said
kicker arm contacting said balance wheel to supply it with
and 29. The motion of kicker arm 40, transmitted
the necessary energy for oscillation, and means electri
through contact arm 47 and extension 48, serves to ro
cally connecting said kicker arm system between said
tate balance wheel 49 so as to carry extension 48 away
counter means and said oscillatory system for controlling
from the arm 47 breaking thecontact between it and
25 the counting rate of said counter means by said natural
extension 48.
frequency.
7
This interruption in the circuit previously described
2. A digital timer comprising a digital electromechan
would normally cause the current through the solenoids
ical counter means, a balance wheel-spring oscillatory sys
29 and 39 to cease ?owing. However, the motion of the
tem having a balance wheel and an isochronous spring
kicker arm also makes contact 45 through the kicker arm
40 to ground over lead 46 permitting the current through 30 mounted on a common axle and having a given natural
frequency, ‘a kicker arm system having a kicker arm,
the solenoids 29 and 39 to continue ?owing.
said kicker arm contacting said balance Wheel to supply
The current will then continue ?owing until counter
it with the necessary energy for oscillation, and means
arm 11 depresses and rotates counter ratchet 13 one
electrically connecting said kicker arm system between
tooth by means of extension 14. When the counter
ratchet ‘13 is rotated, counter arm 11 also breaks the 35 said counter means and said oscillatory system for con
trolling the counting rate of said counter means by said
circuit across terminals32 by depressing rod 31 by means
of contact 30, depressing contact arm 33 and breaking the
reset switch contact. The current path from potential
source 36 to ground through solenoids 29 and 39 is then
natural frequency.
‘
3. A digital timer comprising a base, a magnetic count
er arm pivotally mounted on said base, a counter arm
broken and both counter arm 11 and kicker arm 40 are 40 solenoid mounted on said base and positioned to attract
said counter arm, a normally closed reset switch cooper
atively associated with said counter arm to open said
switch when said counter arm is attracted by said counter
The time constants of these mechanically moving parts
arm solenoid, a mechanical digital counter having a
are so designed that counter arm 11 and kicker arm 40
will have returned to their initial positions before balance 45 counter ratchet driven by said counter arm, a magnetic
allowed to return to their initial position reclosing reset
switch contacts 32.
wheel 49 has rotated through one half period of the
natural frequency of the balance wheel 49 and spring
51 combination, and recontacted arm 47 by means of
extension 48. When this recontact is made, the initial
conditions prevail and the cycle will repeat itself. This
repetition will continue until counter ratchet 13 has ro
tated sufficiently to carry timing cam 16 around so that
' cam wheel 18 will snap into indentation 17 making con
tact across contacts 25 by means of contact arm 26 and
indicating a completion of the timing interval. The length
of the timing interval can be controlled by the initial
setting of ratchet 13 and timer cam 16 with respect to
indentation 17.
Supports 12, 20, 35 and 43, axles 15, 41 and 50, sole
and electrically conducting kicker arm pivotally mounted
on said base, a kicker arm solenoid mounted on said base
and positioned to attract said kicker arm, a normally
open kicker arm ground contact cooperatively associated
with said kicker arm to close when said kicker arm is
attracted by said kicker arm solenoid, an electrically con
ductive balance wheel mounted on an electrically con
ductive and grounded axle, a spring cooperating with said
axle to form a balance wheel-spring oscillatory system,
said kicker arm being biased against said balance wheel
to cause it to oscillate and break contact with said kicker
arm when said kicker arm is attracted by said kicker
arm solenoid and a source of potential and a switch con
nected in series from ground through said reset switch,
noids 29 and 39 and stop 44 are ‘all parts of or are
said counter solenoid and said kicker solenoid to said
mounted on a base (not illustrated). The magnetic cir
cuits are completed through the base structure. The
kicker arm.
kicker arm 40 may be made of a soft iron to be both
magnetic and electrically conductive. A material with
‘a squarer hysteresis loop may be employed to minimize 65
the effect of current variations above saturation on the -
References Qited in the ?le of this patent
UNITED STATES PATENTS
1,702,411
Olsem __________ _..____ Feb. 19, 1929
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