U.S. patent number 3,789,601 [Application Number 05/162,813] was granted by the patent office on 1974-02-05 for solid state watch with magnetic setting.
This patent grant is currently assigned to Time Computer, Inc.. Invention is credited to John M. Bergey.
United States Patent |
3,789,601 |
Bergey |
February 5, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
SOLID STATE WATCH WITH MAGNETIC SETTING
Abstract
Disclosed is a solid state electronic wristwatch with no moving
parts. The watch electronics are hermetically sealed in the watch
case to be free of dust and moisture and the sealed components are
resiliently mounted for improved shock resistance. Two setting
switches and a demand switch within the casing are operated from
outside the watch by permanent magnets, the demand magnet operating
with a demand pushbutton. The setting magnet may be stored in the
watch bracelet.
Inventors: |
Bergey; John M. (Lancaster,
PA) |
Assignee: |
Time Computer, Inc. (Lancaster,
PA)
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Family
ID: |
26836312 |
Appl.
No.: |
05/162,813 |
Filed: |
July 15, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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138557 |
Apr 29, 1971 |
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Current U.S.
Class: |
368/69; 368/239;
368/287; 368/319; 968/962; 368/292; 968/914; 968/965 |
Current CPC
Class: |
G04G
9/126 (20130101); G04G 5/04 (20130101); G04G
9/12 (20130101) |
Current International
Class: |
G04G
9/00 (20060101); G04G 9/12 (20060101); G04G
5/00 (20060101); G04G 5/04 (20060101); G04b
019/30 (); G04b 027/00 () |
Field of
Search: |
;58/23R,23BA,23A,34,50,53,551,85.5,9R ;224/4 ;29/177-179 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wilkinson; Richard B.
Assistant Examiner: Jackmon; Edith Simmons
Attorney, Agent or Firm: LeBlanc & Shur
Parent Case Text
This application is a voluntary division of my copending
application Ser. No. 138,557, filed Apr. 29, 1971 for SOLID STATE
WATCH WITH MAGNETIC SETTING.
Claims
What is claimed and desired to be secured by United States Letters
Patent is:
1. A wristwatch comprising a watch case made of non-magnetic
material, timekeeping means in said case including a solid state
electronic circuit and a liquid crystal digital time display, a
pushbutton on said case, a magnetic field responsive switch in said
case for controlling said display, and a permanent magnet movable
with said pushbutton to activate said switch when said pushbutton
is in a first position and deactivate said switch when said
pushbutton is in a second position.
2. A wristwatch according to claim 1 wherein said case includes an
aperture, said pushbutton being mounted for reciprocation in said
aperture, said permanent magnet being mounted in said pushbutton,
means resiliently biasing said button and magnet in an outward
direction, and means closing off and sealing the inner end of said
aperture.
3. A wristwatch according to claim 2 wherein said switch comprises
a reed switch located in said case adjacent the closed end of said
aperture.
4. A wristwatch according to claim 1 including means resiliently
mounting said circuit and said display in said case.
5. A wristwatch according to claim 3 wherein said timekeeping means
comprises a source of constant frequency electrical signals, a
divider coupled to said source, a display actuator coupled to said
divider, and a plurality of liquid crystals coupled to said display
actuator.
Description
This invention relates to a solid state timepiece and more
particularly to an electronic wristwatch which employs no moving
parts. In the present invention, a frequency standard in the form
of a crystal oscillator acts through solid state electronic circuit
dividers and drivers to power in timed sequence the light-emitting
diodes of an electro-optic display. Low power consumption and small
size and weight are achieved through the use of complementary MOS
circuits to produce what is in essence a miniaturized fixed program
computer. In particular, the present invention is directed to a
solid state wristwatch of this type in which the active components
are completely sealed for longer life and which incorporates an
improved read switch-magnetic setting arrangement.
Battery-powered wristwatches and other small portable timekeeping
devices of various types are well known and are commercially
available. The first commercially successful battery-powered
wristwatch is of the type shown and described in assignee's U.S.
Pat. No. 26,187, reissued Apr. 4, 1967, to John A. Van Horn et al.
for ELECTRIC WATCH. Electric watches of this type employ a balance
wheel and a hairspring driven by the interaction of a
current-carrying coil and a magnetic field produced by small
permanent magnets.
In recent years, considerable effort has been directed toward the
development of a wristwatch which does not employ an
electromechanical oscillator as the master time reference. In many
instances, these constructions have utilized a crystal-controlled
high frequency oscillator as a frequency standard in conjunction
with frequency conversion circuitry to produce a drive signal at a
suitable timekeeping rate. However, difficulties have been
encountered in arriving at an oscillator-frequency converter
combination having not only the required frequency stability but
also sufficiently low power dissipation and small size to be
practical for use in a battery-powered wristwatch.
In order to overcome these and other problems, there is disclosed
in assignee's U.S. Pat. No. 3,560,998, issued Feb. 2, 1971, a
crystal-controlled oscillator type watch construction using low
power complementary MOS circuits. The oscillator-frequency
converter combination of that patent is described as suitable for
driving conventional watch hands over a watch dial or,
alternatively, for selectively actuating the display elements of an
optical display in response to the drive signal output of the
converter.
In assignee's U.S. Pat. No. 3,576,099, issued Apr. 27, 1971, there
is disclosed an improved watch construction in which the optical
display takes the form of a plurality of light-emitting diodes
which are intermittently energized on demand at the option of the
wearer of the watch. This assures a minimum power consumption and
an increasingly long life for the watch battery. An improved watch
construction of this general type incorporating solid state
circuits and integrated circuit techniques is disclosed in
assignee's copending U.S. Pat. application Ser. No. 35,196, filed
May 6, 1970, now U.S. Pat. No. 3,672,155.
The present invention is directed to an improved watch construction
of the same general type as disclosed in the aforementioned
application and patents and one which utilizes no moving parts to
perform the timekeeping function. The watch of the present
invention consists of three major components, namely, a quartz
crystal time base, a miniature time computer module, and a power
supply or battery. These microminiature components are packaged in
a conventional size wristwatch chassis or case. A tiny quartz slab
is precisely cut to predetermined dimensions so that it vibrates at
32,768 Hz when properly stimulated by pulses from an electric
oscillator. The high frequency from the crystal time base is
divided down to 1 pulse per second by utilizing a multi-stage
integrated circuit binary counter. The time computer module counts
the pulse train, encodes it into binary form, and then decodes and
processes the result so as to provide the appropriate signals at
display stations.
Situated on the front of the watch adjacent the display is a
pushbutton demand switch which, when pressed, instantly activates
the appropriate visual display stations. Minues and hours are
programmed to display for one and one-quarter seconds, with just a
touch of the demand switch. Continued depression of this switch
causes the minute and hour data to fade and the seconds to
immediately appear. The seconds continue to count as long as the
wearer interrogates the computer module. Computation of the precise
time is continuous and completely independent of whether or not it
is displayed.
The watch display consists of a television screen-like colored
filter which passes the cold red light from gallium arsenide
phosphide (GaAsP) light-emitting diodes. Preferably a 7 segment
array forms each individual number at the appropriate moment at a
brightness determined by a specially constructed dimmer or display
intensity control circuit. This dimmer circuit utilizes one or more
photo-detectors to measure ambient lighting conditions so the
display intensity provides viewing comfort under all day or
nighttime lighting conditions.
Important features of the present invention include a magnetically
operated demand or read switch and magnetically operated "hour set"
and "minute set" switches for setting the watch to the appropriate
time. The hour-set switch rapidly advances the hours without
disturbing the accuracy of the minutes or seconds. The minute-set
switch automatically zeros the seconds while it advances the
minutes to the desired setting. The whole procedure, even though
seldom required, takes a matter of a few seconds.
Because of the magnetic setting and magnetic interrogation, active
components of the watch may be hermetically sealed to produce a
unit that is shockproof and waterproof, regardless of the
environment in which it is placed. Since there is no conventional
stem for winding or setting, the small shaft sealing problem is
eliminated and no maintenance or repair is normally necessary since
the active components are hermetically sealed and inaccessible to
influences from the outside world. All solid state electronic
components, including the light-emitting diode displays, have a
virtually unlimited life.
It is therefore one object of the present invention to provide an
improved electronic wristwatch.
Another object of the present invention is to provide a wristwatch
which utilizes no moving parts for performing the timing
function.
Another object of the present invention is to provide a solid state
watch in which the active components of the watch are hermetically
sealed.
Another object of the present invention is to provide a
magnetically operated "on demand" display system for a solid state
watch.
Another object of the present invention is to provide a solid state
wristwatch incorporating magnetic time setting.
Another object of the present invention is to provide a solid state
wristwatch having a digital optical display which is virtually
shockproof and waterproof.
Another object of the present invention is to provide a solid state
wristwatch with no moving parts having improved operating
characteristics and reduced cost.
These and further objects and advantages of the invention will be
more apparent upon reference to the following specification,
claims, and appended drawings, wherein:
FIG. 1 is a front view of a conventional size man's wristwatch
constructed in accordance with the present invention;
FIG. 2 is a simplified block diagram of the major components of the
solid state watch of this invention;
FIG. 3 shows a display element for the watch of the present
invention in the form of a 7 bar segment construction of
light-emitting diodes;
FIGS. 4, 4a, and 4b, taken together, are an overall block diagram
of the electrical circuit for the solid state watch of FIG. 1;
FIG. 5 shows a modified watch circuit in which substantially all of
the major electrical components of the watch are formed using
large-scale integrated circuitry;
FIG. 6 is an exploded view of the wristwatch of FIG. 1;
FIG. 7 is a cross section taken along line 6--6 of FIG. 1;
FIG. 8 is a bottom plan or rear view of the watch of FIG. 1;
FIG. 9 is a cross section perpendicular to that of FIG. 7 taken
along line 9--9 of FIG. 1;
FIG. 10 is an enlarged plan view of the demand button assembly of
the watch of FIG. 1;
FIG. 11 is a cross section through the demand button assembly taken
along line 11--11 of FIG. 10;
FIG. 12 is a cross section perpendicular to that of FIG. 11 taken
along the line 12--12 of FIG. 10; and
FIG. 13 is a plan view of the flat demand button spring before it
is formed into the curved shape shown in FIGS. 11 and 12.
Referring to the drawings, the novel watch of the present invention
is generally indicated at 10 in FIG. 1. The watch is constructed to
fit into a watch case 12 of approximately the size of a
conventional man's wristwatch. The case 12 is shown connected to a
wristwatch bracelet 14 and includes a display window 16 through
which time is displayed in digital form as indicated at 20. Mounted
on the case 12 is a demand switch pushbutton 18, by means of which
the display 20 may be actuated when the wearer of the wristwatch 10
desires to ascertain the time.
In normal operation, time is continuously being kept but is not
displayed through the window 16. That is, no time indication is
visible through the window and this is the normal condition which
prevails in order to conserve battery energy in the watch. However,
even though the time is not displayed through the window 16, it is
understood that the watch 10 continuously keeps accurate time and
is capable of accurately displaying this time at any instant. When
the wearer desires to ascertain the correct time, he depressed the
pushbutton 18 with his finger and the correct time is immediately
displayed at 20 through the window 16. The hours and minutes are
displayed through the window 16 for a predetermined length of time,
preferably 11/4 seconds, irrespective of whether or not the
pushbutton 18 remains depressed. The exact time of the display is
chosen to give the wearer adequate time to consult the display to
determine the hour and minute of time. Should the minutes change
during the time of display, this change is immediately indicated by
advancement of the minute reading to the next number as the watch
is being read. If the pushbutton 18 remains depressed, at the end
of one and one-quarter seconds, the hours and minutes of the
display are extinguished, i.e., they disappear, and simultaneously
the seconds reading is displayed through the window 16 immediately
below the hours and minutes display 20. The advancing seconds
cycling from 0 to 59 continue to be displayed through window 16
until pushbutton switch 18 is released.
FIG. 2 is a simplified block diagram of the principal components of
the watch 10 of FIG. 1. The circuit comprises a time base or
frequency standard 26 including a piezoelectric crystal to provide
a very accurate frequency such that the frequency standard or
oscillator oscillates at 32,768 Hz. This relatively high frequency
is supplied by a lead 28 to a frequency converter 30 in the form of
a divider which divides down the frequency from the standard so
that the output from the converter 30 appearing on lead 32 is at a
frequency of 1 Hz. The frequency converter 30 preferably comprises
a binary counting chain of complementary MOS transistors of the
type shown and described in assignee's U.S. Pat. No. 3,560,998, the
disclosure of which is incorporated herein by reference. The 1 Hz
signal is applied by lead 32 to a display actuator 34 which in turn
drives the displays 20 and 22 of the watch 10 by way of electrical
lead 36.
FIG. 3 shows a display station 38 forming one of the numerals of
the hours and minutes display 20 and the seconds display 22. Each
of these display stations (with the exception of the hours tens
display as more fully described below) is preferably in the form of
a 7 bar segment array of light-emitting diodes of the type shown
and described in detail in assignee's U.S. Pat. No. 3,576,099,
issued Apr. 27, 1971, the disclosure of which is incorporated
herein by reference. FIG. 3 shows 7 bar segments of light-emitting
diodes 40, 42, 44, 46, 48, 50, and 52, all of elongated shape and
arranged so that by lighting an appropriate combination of the bars
or segments any of the numbers 0 through 9 may be displayed.
FIGS. 4, 4a, and 4b show an overall block diagram of the electrical
circuit of the watch of the present invention. Reference may be had
to assignee's copending U.S. Pat. application Ser. No. 35,196,
filed May 6, 1970 now U.S. Pat. No. 3,672,155, the disclosure of
which is incorporated herein by reference, for a detailed
description of the construction and operation of the electrical
circuit. Briefly, however, and referring to the overall block
diagram of FIGS. 4, 4a, and 4b, the watch 10 comprises an
oscillator 96 which is controlled by a crystal to produce an output
on lead 98, i.e., a pulse train on that lead having a pulse
repetition rate of 32,768 Hz. The crystal output passes through a
complementary symmetry MOS counter 100 of the type shown and
described in assignee's U.S. Pat. No. 3,560,998, which acts as a
divider, dividing the output by 2.sup.7, i.e., a 7 stage counter,
to produce an output on lead 102 having a pulse repetition rate of
256 Hz. This signal is divided by 2 in counter 104, by 2 again in
counter 106, by 8 (2.sup.3) in counter 108, and by 4 (2.sup.2) in
counter 110.
An 8 Hz output on lead 112 from counter 108 is applied to a
set-hold circuit 114 where the 8 Hz repetition rate pulse train
appears as an output on lead 116. The 8 Hz signal on lead 116 is
applied to a counter 118 where it is divided by 8 (2.sup.3) to
produce a 1 Hz output pulse train on lead 120. The 1 Hz pulse train
is divided by 10 in counter 122, divided by 6 in counter 124,
divided by 10 again in counter 126, divided by 6 in counter 124,
divided by 10 again in counter 126, divided by 6 again in counter
128, and the output of this counter is finally applied to counter
130 which divides by 12. The output of counter 122 appearing on
leads 132, 134, 136, and 138 is a binary coded decimal 1248 code
which is applied to the decoder-driver 140 which, in turn,
energizes the tens digits of the seconds display indicated at 142.
The ones digits of the seconds display indicated at 144 are
similarly actuated from counter 124 by way of seconds
decoder-driver 146. Similar decoder-drivers 148, 150, and 152
actuate the tens digits of the minutes display at 154, the ones
digits of the minutes display at 156, and the hours display at 158.
Counter 130 has five output leads to decoder-driver 152 for a
purpose more fully described below. The other decoder-drivers 146,
148, and 150 are actuated by BCD 1248 codes from their respective
counters 124, 126, and 128 in the same manner as decoder-driver 140
is actuated from counter 122.
As previously stated, in order to conserve energy, the
light-emitting diodes are only energized on demand, i.e., when the
pushbutton 18 of FIG. 1 is depressed by the wearer's finger. Even
when the button is depressed, the lights are not always
continuously lit but instead, in order to conserve power, are
intermittently lighted during less than full daylight conditions at
a frequency sufficiently high to give the appearance of continuity
due to the light retention properties of the human eye. The pulses
for intermittently lighting or pulsing the seconds display are
derived from a display control driver 160 which applies the ON-OFF
pulses by way of lead 162 to the seconds decoder-drivers 140 and
146. Similar intermittent pulses from the display control drivers
160 are applied by lead 164 to the minutes decoder-drivers 148 and
150 and by lead 166 to the hours decoder driver 152. The exact
frequency at which the displays are turned on and off while always
sufficiently high to give the impression to the human eye of
continuous light is determined by a light control circuit 168 which
supplies a light control signal over lead 170 to display control
drivers 160. The light control signal is either DC (full daylight)
or a combination of a 64 Hz signal supplied from counter 106 by way
of lead 172, a 128 Hz signal supplied by counter 104 by way of lead
174, and a 256 Hz signal supplied from the output of counter 100 by
way of lead 176. These signals are combined in the light control
circuit 168 in a manner determined by the output signal on lead 178
to the light control circuit from ambient light sensors 180. These
light sensors are in the form of three photo-transistors mounted on
the face of the watch inside the viewing window and act to produce
increased illumination from the light-emitting diodes during strong
daylight conditions and less illumination from the diodes under
nighttime or reduced light conditions. In the preferred embodiment,
light sensors 180 provide four different light levels from the
light-emitting diodes so that the watch face may be read with equal
facility and comfort under all possible lighting conditions, while
at the same time conserving energy at times when less light is
needed from the diodes to make them visible, such as is the case
when the watch is read in at least partial darkness.
As previously stated, the watch face is ordinarily not illuminated.
The hours and minutes diodes only light up when the demand switch
is depressed. Actuation of the demand button by the wearer causes
the read switch 184 in FIG. 4 to close, causing the positive side
of the power supply to be connected by way of leads 186 and 188 to
the display control drivers 160. Energization of these drivers
permits passage through them of the signal from the light control
circuit 168 which is passed on to the decoder-drivers causing the
minutes and hours displays to be illuminated. No output from the
display control diodes 160 appears on lead 162 at this time and the
seconds displays are not illuminated. Closure of the read switch
184 also applies B+ by way of lead 190 to set-hold circuit 114
which immediately resets a display timer 192 by way of lead 194.
Display timer 192 is a divide by 10 counter and has applied to its
input the 8 Hz pulse train on lead 112. This timer divides the 8 Hz
pulse by 10 and after 11/4 seconds produces an output pulse on lead
196 which is applied to display control driver 160. This pulse
causes the display control driver to change state, removing the
output from leads 164 and 166 and causing the minutes and hours
display to be extinguished. At the same time, the output is
switched to lead 162 causing the seconds display to be illuminated
simultaneous with the extinguishment of the hours and minutes
display.
An important feature of the watch of the present invention lies in
the fact that the hours may be set independently of the minutes and
seconds and at a very rapid rate. Closure of hours-set switch
switch 198 grounds one input of an hours-set circuit 200 by way of
leads 202 and 204. Hours-set circuit 200 receives a 2 Hz pulse
train from counter 110 by way of lead 206 and actuation of the
hours-set circuit by closure of hours-set switch 198 causes the
hours-set circuit 200 to pass the 2 Hz signal on lead 206 to
counter 130 by way of lead 208. Hours-set switch 198 is also
connected to the display control drivers 160 to cause an output to
appear on leads 164 and 166 assuring that the hours and minutes are
displayed when the hours are being reset during closure of switch
198. A minute-set switch 212 is connected by leads 214 and 216 to a
minute-set circuit 218. As before, actuation of this circuit causes
it to pass a 2 Hz pulse train on lead 220 from counter 110 by way
of lead 222 to the divide by 10 counter 126 driving the minutes
display. Minute-set switch 212 is likewise connected by lead 224 to
display control drivers 160, again to insure an output on leads 164
and 166 during resetting.
In the watch of the present invention, actuation of the minute-set
switch 212 automatically zeros the seconds display. The reason for
this is that most time signals, such as those given over the radio
and the like, are given on the hour or on the minute and in order
to start the watch in synchronism with the correct time as given by
such a signal, it is necessary that the seconds display be at zero
at the time the radio tone or other time signal is heard. In order
to accomplish this, the minute-set switch 212 is connected by leads
214 and 216 and a further lead 226 to set-hold circuit 114.
Energization of this circuit from lead 226 produces an output pulse
on output lead 228 which is applied to the reset terminals of
counters 118, 122, and 124 by way of leads 229, 231, and 233,
resetting these counters to zero and causing the seconds display to
be automatically zeroed. Depressing read switch 184 unlocks the set
time and begins the real time counting sequence.
FIG. 5 shows a modified embodiment of the solid state watch of the
present invention, generally indicated at 230. In FIG. 5, like
parts bear like reference numerals, and the overall construction of
the watch in FIG. 5 is generally similar to the embodiment
previously described. The principal modification incorporated in
the embodiment of FIG. 5 is that the vast majority of the
electrical components are formed from one or more large-scale
integrated circuits, as indicated by the large integrated circuit
block 232 in FIG. 5. Reference may be had to assignee's copending
U.S. Pat. application Ser. No. 138,547, filed Apr. 29, 1971 now
Pat. No. 3,714,867, and entitled SOLID STATE WATCH INCORPORATING
LARGE-SCALE INTEGRATED CIRCUITS, in the name of Bruno M. Dargent,
for a detailed description of the large-scale integrated circuit
232, the disclosure of that copending application being
incorporated herein by reference.
In FIG. 5, the crystal oscillator 96 is of the type previously
described and includes a piezoelectric crystal 234, a variable
trimming capacitor 236, and a bias resistor 238. The active
components of the oscillator are a pair of complementary MOS
transistors connected to form an inverter and they are incorporated
in the large-scale integrated circuit 232. As in the previous
embodiment, the oscillator preferably operates at a frequency of
32,768 Hz. The entire watch is powered from a conventional watch
battery or power supply, indicated at 240, and the demand switch
184, the minute-set switch 212, and the hour-set switch 198 are all
connected from the positive side of the battery 240 to the other or
grounded side of the battery through the respective resistors 242,
244, and 246.
The modified embodiment in FIG. 5 includes a modified dimmer or
display intensity control circuit comprising a capacitor 248, a
resistor 250, a light sensitive resistor 252, a second resistor
254, and a second capacitor 256. These components in effect form a
multivibrator which is triggered at a frequency of 64 Hz, which
trigger signal is derived from an intermediate stage of the divider
or frequency converter 30 incorporated in the large-scale
integrated circuit 232. The pulse width of the multivibrator and
therefore the duty cycle of the output from the multivibrator
depends primarily on the value of fixed capacitor 256 and the value
of the variable light sensitive resistor 252. For decreasing
amounts of ambient light impinging upon resistor 252, as indicated
by the arrow 258, the duty cycle of the multivibrator output is
reduced and this output signal is applied to the displays 20 and 22
so as to vary their intensity with the amount of ambient light,
i.e., the intensity is increased when the ambient light is great
and the intensity of the light-emitting diodes is reduced when
ambient light decreases.
The displays are controlled from the large-scale integrated circuit
232 by a pair of bipolar switches 260 and 262, labeled S.sub.1 and
S.sub.2, respectively. These transistors connect the cathodes of
the light-emitting diodes of the display to the negative side of
the battery 240, i.e., to ground, so that the circuit to the
light-emitting diodes is completed when the transistors 260 and 262
are in conduction. These transistors have their bases connected to
the large-scale integrated circuit 232 through respective resistors
264 and 266. It is understood that when one of the switches S.sub.1
or S.sub.2 is turned on, the other is off and vice versa so that
all displays are not simultaneously on. When switch S.sub.1 (260)
is turned on, this completes the circuit to the hours and minutes
display diodes 20. If the demand button remains depressed, after
11/4 seconds switch 260 is turned off by the large-scale integrated
circuit 232 and switch 262 is simultaneously turned on so that the
hours and minutes display 20 disappears and the seconds display 22
immediately comes on. These displays receive timing signals from
the large-scale integrated circuit 232 through the connecting leads
generally indicated at 268.
FIG. 6 is an exploded view of the watch and FIG. 7 is a cross
section through the watch of the present invention taken along line
7--7 of FIG. 1. The watch case 12 comprises a front plate 270, an
inner cover 272, and a removable back plate 274. These three plates
are preferably made from a non-magnetic metal material, such as
that sold under the trade name "Havar". Between inner cover 272 and
back plate 274 is the power supply in the form of a pair of 1.5
volt dry cells 276 and 278. The cells are preferably silver oxide
batteries and are connected in series to produce an operating
voltage of about 2.5 to about 3.2 volts DC. Back plate 274 carries
a plurality of mounting springs 280 with projections 282 which snap
into corresponding recesses in the front plate 270 for ready
attachment and removal of the back plate so that access may be
gained to the battery cells 276 and 278. The back plate is sealed
by an annular rubber O-ring 284.
FIG. 8 is a bottom plan or rear view of the watch of FIG. 1 with
portions shown in dashed lines and FIG. 9 is a cross section at
right angles to the cross section of FIG. 7 taken along line 9--9
of FIG. 1. FIG. 10 is an enlarged plan view of the assembly for
demand button 18. The battery cells are separated from back plate
274 by annular insulating washers 284 but have their negative side
connected to the back plate and therefore grounded to the case by
an electrically conductive cell connector 286. A similar cell
connector 288 (FIG. 9) connected to the positive side of the power
supply is electrically connected to a positive cell lead 290 which
passes through a suitable glass seal 292 to establish electrical
connection to the electronic circuit indicated generally at 294
mounted on circuit substrate 296. Trimming capacitor 236 and the
piezoelectric crystal 234 are also mounted on the substrate 296.
Placed in the viewing window over the light-emitting diodes is a
light filter 298. The filter is fabricated from a ruby to insure
relative scratch and break resistance. A solderable metal material
is deposited along the edge of the filter to aid in the
solder-sealing of the filter to the front plate 270 as indicated at
300 in FIG. 9. The pink ruby is preferably coated with a red dyed
clear epoxy paint on its inside surface to provide a deep red color
which transmits most of the 6,500 Angstrom wavelength light from
the light-emitting diodes carried by the electronic substrate 296.
Inner cover 272 is solder-sealed to front plate 270 around its
edge, as indicated at 302 in FIG. 9, and this inner cover carries
four mounting posts, two of which are illustrated at 304 in FIG. 9.
These posts or studs are welded to inner cover 272 and the
substrate 296 is held against these shoulder studs by means of
screws 306. Both sides of the substrate rest against a resilient
shock absorbent material 308 and 310 to provide maximum protection
against severe shocks encountered when dropping the watch. The
crystal can 234 and trimming capacitor 236 are all similarly
protected by soft potting compound between the substrate and their
assembled position as indicated at 312 and 314, respectively.
As can be seen, the electronics 294 is hermetically sealed all the
way around between inner cover 272 and front plate 270. This
hermetic seal acts as protection to the electronics and also
prevents condensation of water vapor on the filter 298. The
hermetically sealed cavity is provided by solder-sealing the filter
to the front plate and solder-sealing the inner cover to this
plate. The battery compartment is outside this cavity and is
protected from the outside world by the case back or back plate 274
and the O-ring gasket 284. Electrical connections of the battery to
the electronics are provided by glass-to-metal sealed feedthrough
connectors as indicated at 292.
An important feature of the present invention resides in the fact
that the read or demand switch 184, the minute-set switch 212, and
the hour-set switch 198 are all magnetically operated in such a way
that the electronics 294 remains hermetically sealed. These three
switches are shown in dashed lines in FIG. 8 and are preferably in
the form of reed switches. There are several significant advantages
in utilizing a permanent magnet operated reed switch to perform the
hours, minutes and demand readout functions in the watch. First,
the miniature switches are glass encapsulated, hermetically sealed
devices which have a proven history of high reliability in this
type of application. Secondly, no through-holes are required in the
watch case so true hermetic sealing is simplified. Also, actuation
of the switches requires a deliberate activity on the part of the
wearer so that inadvertent operation is minimized. These switches
are positioned in the watch as illustrated in FIG. 8 and attached
to the substrate 296 by a soft potting compound, as illustrated,
for example, at 316 in FIG. 9 for the hours-set switch 198. These
switches are preferably of the type identified as MINI-2 switches
manufactured by Hamlin, Inc. of Lake Wills, Wis., or equivalent. A
switch pull sensitivity of between 15 and 20 ampereturns is
desirable for the demand switch, while 35 to 40 ampereturns is
desirable for both the hour and minutes set switches.
As best seen in FIG. 8, the front plate 270 of the watch case is
provided with a first elongated setting slot 318 adjacent hour-set
switch 198 and a second setting slot 320 adjacent the minute-set
switch 212. A portion of the setting slot 318 is illustrated in
solid lines in FIG. 9. It is understood that the minute-set switch
slot or recess 320 is of similar construction. These two recesses
or slots, one adjacent the hour-set switch and the other adjacent
the minute-set switch are dimensioned so that a long cylindrical or
square magnet can be placed into this recess when a change in
setting time is desired. In the preferred embodiment, the setting
magnet takes the form of a permanent magnet made from Alinco V
material with dimensions of 0.500 inch long by 0.062 inch square.
This produces a field of about 700 gauss.
As best seen in FIG. 7, the demand switch 184 is supported from the
substrate 296 in a manner similar to the other switches, i.e., by a
soft potting compound as illustrated at 322. FIG. 10 is a plan view
of the pushbutton assembly 18, FIG. 11 is a cross section through
the push-button assembly taken along line 11--11 in FIG. 10, FIG.
12 is a cross section at right angles to that of FIG. 11 taken
along line 12--12 of FIG. 10, and FIG. 13 shows the flat pushbutton
spring before it is formed into a curved spring shape.
The pushbutton assembly is constructed so as to retain the hermetic
seal about the electronic components of the watch. The pushbutton
assembly comprises an elongated pushbutton proper 324 slidably
received through a suitable aperture 326 in the front plate 270 of
the watch case. Press fit into a circular recess in the center of
the pushbutton 324 is a permanent magnet 328 formed in the shape of
a right circular cylinder. Recess 326 is stepped to form a shoulder
330 which cooperates with an annular flange 332 on the lower end of
pushbutton 324 to limit the upward or outward movement of the
pushbutton. The plate shoulder 330 and annular flange 332 are
preferably separated by an annular gasket 334 made of silicone.
The inner end of aperture 326 is closed off by a flat rectangular
plate 336 made of brass or other suitable non-magnetic material.
Brass plate 336 is soldered for a hermetic seal all the way around
its edge to the inner surface 338 of front plate 270 as indicated
at 340 in FIGS. 11 and 12. In this way, the pushbutton 324 and
magnet 328, while mounted on the front plate, are sealed externally
of the chamber carrying the watch electronics. Resting on top of
brass plate 336 is a substantially rectangular arched or curved
spring 342 which urges the pushbutton 324 and the magnet 328
carried by it upwardly or outwardly in the direction of the arrow
344 in FIG. 11. Spring 342 is preferably made of Havar or other
suitable non-magnetic metallic material and, while its ends 346 and
348 rest on top of brass plate 336, it is symmetrically curved or
arched about the centerline 350 of the pushbutton assembly so that
its center is spaced approximately 0.030 inch from the top of brass
plate 336. FIG. 13 shows the Havar spring 342 in plan view while it
is flat and before it is formed into the arched or curved
configuration illustrated in FIGS. 11 and 12. By way of example
only, the spring may have a thickness of approximately 0.0024 inch.
The demand magnet 328 which is press fit into the recess in
pushbutton 324 is about 0.070 inch long and about 0.090 inch in
diameter and utilizes cobalt platinum (CoPt) to produce a field of
about 1,300 gauss.
It is apparent from the above that the present invention provides
an improved timepiece construction and particularly a timepiece
having sufficiently small size, weight and power consumption for
use as a conventional man's wristwatch. Important features of the
present invention include a resilient shock-free mounting
arrangement, a completely hermetically sealed assembly so that the
electronics, display and other major components are completely
sealed from atmospheric effects, a magnetically operated demand or
read switch, and a pair of magnetically operated setting switches
for setting the watch time. The setting permanent magnet may
conveniently be stored in a suitable recess in the watch bracelet
when not in use or may otherwise be carried on or adjacent the
watch or in a suitable recess provided in the watch case. If
desired, it is possible to paint the substrate and light reflecting
materials in the vicinity of the light-emitting diodes a dark flat
black. This improves readout visibility by providing maximum
contrast ratio between the light-emitting diodes and their
background. The piezoelectric crystal for the oscillator is
preferably contained in its own hermetically sealed vacuum can to
reduce its series resistance, improve its activity for any given
drive current, and to minimize the natural aging effects of the
crystal. In the preferred embodiment, the power supply is formed of
two silver oxide cells in a standard size container operating at a
nominal voltage of about 3 volts, but it is understood that any
conventional wristwatch power supply may be utilized. As
illustrated in FIG. 7, the electrical cells 276 and 278 are
preferably mounted in a cell holder 352 mounted on the outside or
backside of inner cover 272.
While the preferred embodiment and certain especially significant
operating conditions have been set forth in detail, it should be
understood that various modifications are readily apparent. In the
preferred embodiment, the light-emitting diodes take the form of
gallium arsenide phosphide LED's of the type more fully shown and
described in assignee's U.S. Pat. No. 3,576,099, issued Apr. 27,
1971, the disclosure of which is incorporated herein by reference.
However, it is understood that the display can assume any one of
several forms. For example, the optical display may be formed using
such well known devices as miniature incandescent bulbs, other
types of light-emitting diodes, or the well known liquid crystals,
as well as lesser known devices, such as ferro-electric crystals or
electro-luminescent displays and others. If desired, the electrical
signals may be connected through a suitable electromechanical
transducer or motor to drive conventional watch hands.
The invention may be embodied in other specific forms without
departing from the spirit or essential characteristics thereof. The
present embodiments are therefore to be considered in all respects
as illustrative and not restrictive, the scope of the invention
being indicated by the appended claims rather than by the foregoing
description, and all changes which come within the meaning and
range of equivalency of the claims are therefore intended to be
embraced therein.
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