U.S. patent number 3,839,857 [Application Number 05/149,423] was granted by the patent office on 1974-10-08 for electrochromic information displays.
This patent grant is currently assigned to American Cyanamid Company. Invention is credited to Donald Joseph Berets, George Augustus Castellion, Gottfried Haacke.
United States Patent |
3,839,857 |
Berets , et al. |
October 8, 1974 |
ELECTROCHROMIC INFORMATION DISPLAYS
Abstract
Accumulating measuring devices which indicate the flow of
electric current on graduated scale. Current flow may be of any
fixed rate or value, steady or pulse, and scale may be any desired
graduations. Current flow is indicated by a persistent
electrochromic display material which changes color due to passage
of electric current through it. The entire device is electronic,
with no mechanical parts. Other accumulating functions may also be
measured with the device if they can be converted first to electric
current. One particular application is an elapsed time indicator,
e.g. a watch or clock.
Inventors: |
Berets; Donald Joseph
(Stamford, CT), Castellion; George Augustus (Stamford,
CT), Haacke; Gottfried (Stamford, CT) |
Assignee: |
American Cyanamid Company
(Stamford, CT)
|
Family
ID: |
22530206 |
Appl.
No.: |
05/149,423 |
Filed: |
June 3, 1971 |
Current U.S.
Class: |
368/82; 368/240;
968/931; 345/105; 345/49; 359/271; 968/950 |
Current CPC
Class: |
G04G
9/0035 (20130101); G04G 9/06 (20130101) |
Current International
Class: |
G04G
9/00 (20060101); G04G 9/06 (20060101); G04c
003/00 (); C04b 019/06 () |
Field of
Search: |
;58/23R,5R,127R ;324/186
;340/324R,335 ;350/16R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wilkinson; Richard B.
Assistant Examiner: Jackmon; Edith Simmons
Attorney, Agent or Firm: Fickey; Charles J.
Claims
We claim:
1. An electronic timepiece comprising means to establish a stable
frequency signal, means for dividing the frequency of said stable
frequency signal to produce a timing pulse signal, and display
control means responsive to said timing pulse signal to display an
indication of the correct time, said display control means
comprising persistent electrochromic display means and means to
provide electric current pulses solely for activating and erasing
display elements in said display means, whereby said display means
continuously displays time without continuous current to said
display.
2. An electronic timepiece comprising means to establish a stable
frequency signal, means for dividing the frequency of said stable
frequency signal to produce a timing pulse signal, and display
control means responsive to said timing pulse signal to display an
indication of the correct time, said display control means
comprising persistent electrochromic display means comprising
digital characters for displaying hours, minutes and seconds,
wherein said display control means further comprises activating
electric current pulses at the beginning of a minute to change the
display to the appropriate time, and erasing pulses preceeding said
activating pulses, whereby the time indication changes each minute;
said display control circuit further comprising means connected to
said seconds display to activate and erase said seconds display
each second, and demand switch means to make and break said
connection so as to indicate seconds on demand.
3. The timepiece of claim 1 wherein said electrochromic display
means are digital characters.
4. The timepiece of claim 1 wherein said electrochromic display
means are spaced at hour and minute positions on the face of a
conventional timepiece.
5. The timepiece of claim 1, wherein said display means shows hours
and minutes, and said activating electric current pulses are
provided at the beginning of a minute to change the display to the
appropriate time, said erasing pulses preceeding said activating
pulses, whereby the time indication changes each minute.
6. The timepiece of claim 5 including additional display means for
seconds, and means to provide activating and erasing pulses each
second to said seconds display.
7. The device of claim 1 wherein said persistent electrochromic
display means comprises tungsten oxide as an electrochromic
material.
8. The device of claim 5 wherein said electrochromic display means
comprises tungsten oxide as an electrochromic material.
Description
This invention relates to a device for measuring and indicating an
accumulating function electronically without use of moving parts.
The invention relates more particularly to a device having a
persistent electrochromic display means for measuring electric
current flow and indicating this flow on a graduated scale. More
particularly, the invention relates to an elapsed time indicator
such as a clock or a watch.
Many devices are known for measuring and displaying continuing
functions, such as the odometer, electric meter, mechanical clock
or watch, electric clock, electrolytic elapsed time indicators, and
the like. These devices are either mechanical, a combination of
electrical and mechanical means, having digital or analog registers
or dials, or electrochemical in nature. A need has existed for a
purely electronic device, for displaying an accumulating
function.
It is therefore an object of this invention to provide completely
electronic accumulating function indicator operating on electric
current.
A further object is to provide such an indicator which has a
persistent electrochromic display means.
Another object is to provide an electronic elapsed time
indicator.
A further object is to provide a completely electronic watch or
clock.
Another object is to provide an electronic watch which operates on
very low voltage and current requirement over a relatively long
period of time.
These and other objects of the invention will become apparent as
the description thereof proceeds.
SUMMARY OF THE INVENTION
The invention comprises broadly the electronics means for sensing
flow of electric current, either steady or pulse, and the display
means for indicating the accumulating flow.
The electronics can be of various types, depending on the function
to be measured and the manner in which it is to be displayed, i.e.,
as digital information, numbers, letters or the like, or as analog
information on a marked dial. It is generally necessary to provide
means for setting up a continuous, uniform flow of electric
current, whether alternating or direct, or pulse. The current may
come from a battery source, or line current. In one of the simplest
applications, current will be passed to a persistent electrochromic
display dial which colors in a continuously advancing line as a
function of the current flow. By proper regulation of the current
and appropriate graduations along the advancing line, elapsed time
can be measured. When the display means is made in a circle, the
display can function as a watch. The electronics may include logic
to measure electric flow or count pulses and to activate switching
devices to operate the visual display at desired intervals.
DETAILED DESCRIPTION OF THE INVENTION
The invention may be better understood by reference to the Figures
in which
FIG. 1 is a cross section of a simple electronic current measuring
device showing the electrochromic display means,
FIG. 2 represents a watch or a clock face display using
electrochromic dots for minutes and bars for hours,
FIG. 3 shows a watch or clock face display using bars for hour
display and an analog ring for minutes display,
FIG. 3A is a cross-sectional view of the watch of FIG. 3 taken
along the lines 3A--3A,
FIG. 4 is a block circuit of a suitable circuit for a watch, clock
or the like,
FIG. 5 shows a seven bar matrix for displaying numerical digital
information,
FIG. 6 shows the numbers "0" through "9" displayed by means of a
seven bar matrix,
FIG. 7 shows a watch face utilizing an array of four seven bar
matrices to display time,
FIG. 8 shows a cross-sectional view of a battery operated
electronic watch with an electrochromic display,
FIG. 9 shows a seven bar matrix display with elements in a colored
state to show the number "3" as displayed on the watch of FIG.
8,
FIG. 10 shows a watch similar to that of FIG. 8, with means to
light up the face,
FIG. 11 shows a seven bar matrix in reverse mode with elements
uncolored to represent a number "3" by the light shining through
the face,
FIG. 12 is a 35 dot matix display colored to show the number
"2,"
FIG. 13 is a cross-sectional view taken along the lines 13--13 of
FIG. 12 showing coloration of electrochromic elements and
counter-electrodes in different layers,
FIG. 14 shows an electrochromic display matrix having display
elements and counter-electrodes in the same plane and when displays
the number "9,"
FIG. 15 is a cross-sectional view of the matrix of FIG. 14, showing
coloration of the display elements and counter electrodes,
FIG. 16 illustrates a compact watch having electronics and face
display tailored to available commercial battery size.
Referring in greater detail to the Figures, An EC structure
suitable for simple elapsed time measure is shown schematically in
FIG. 1. The essential elements are: electrochromic (EC) layer, 1,
most suitably a layer of WO.sub.3 vacuum deposited to a thickness
of 0.5 - 1.5 .mu. on a conductive glass support 2, such as
commercially available NESA glass. Contacting the EC layer is the
electrolyte-separator layer 3, which may be 0.01 - 10 mm thick,
though generally the thinnest layer which can be prepared is
preferred. The electrolyte-separator layer should have high
protonic conductivity, which may be attained by use of inorganic
acids or mixtures of acids, sulfuric acid having been found to be
excellent in this use. To minimize cell leakage and to obtain other
desirable rheological properties for construction and operation,
mixtures of sulfuric acid with glycerine, ethylene glycol, and
similar polyhydric alcohols have been effective. It is desirable in
the electrolyte-separator layer to minimize water since water has a
deleterious effect on the long term stability of the EC film. The
counter-electrode 4 may be gold or the EC material itself,
intimately mixed with an electronically conductive material, such
as graphite, the composite powder being bound or fixed by another
component in a way so as to achieve desired electrical and
mechanical properties. One useful counter-electrode composition has
been achieved by incorporating WO.sub.3 powder and graphite in a
fibrillated polytetrafluoroethylene binder as described in
copending, commonly assigned application Ser. No. 105,882 filed
Jan. 12, 1971 which is now abandoned. Another suitable form of
electrochromic display device suitable is shown in U.S. Pat. No.
3,521,941.
The component parts 1, 2, 3, and 4 may be cut to desired size
before assembly. Electrical wire contacts are made to 2 and 4, care
being taken not to contaminate the EC layer or electrolyte with
solder components, which might be injurious to EC performance. The
entire assembly should then be hermetically encapsulated in a
plastic, glass, or metal container capable of being sealed so that
short circuitry is avoided, corrosion of the case by the acid
electrolyte is avoided, and a clear view by an observer may be
obtained of the EC film. Glass, epoxy, and silicone combinations
have been employed. It is important to avoid leakage of the
electrolyte, even though it may be quite viscous, over a wide
temperature range of operation, and it is also important to avoid
excessive contamination of the components by air or water vapor
after the assembly has been sealed.
It is evident that many geometrical arrangements of the components
are possible, as shown in FIGS. 2, 3, 5, 7 and 13. In general,
higher speeds of switching from the colorless to the colored EC
state are attained by utilizing the most conductive glass 2 and
maintaining the smallest separation between the counter-electrode 4
and the EC film 1.
To enhance contrast between the colored and uncolored states a
pigment may be added to the electrolyte-separator 3. White
TiO.sub.2 pigment is suitable. An especially striking contrast is
achieved by employing a yellow titanate pigment such as Sun Yellow
C.
To actuate devices of this type, voltages of from 0.5 to 1.5 are
desirable, with the coloring mode attained by making the EC film
negative. To bleach the colored state, the voltage is reversed. The
voltage from a mercury cell, 1.35 volts, is especially
suitable.
The actuating voltage need only be applied long enough to pass
through the device from 10 to 30 millicoulombs per cm.sup.2 of EC
film area. Such current passage will produce a deep blue color,
with a reflectance for white light in the 5-20 percent range.
More complex information displays are made up by use of multiple
components. For example, as shown in FIG. 2, an analog display of
time, such as might be desirable for an electronic wrist watch 5,
can be accomplished by utilizing an array of EC dots 6 or bars 7 to
delineate the minutes and hours. Each EC element is separately
connected to the circuitry via conducting paths etched in the
conductive glass, the EC elements themselves having been deposited
in register through a mask. The electrolyte-separator and
counter-electrode elements are as in FIG. 1 and may be paried with
corresponding EC elements or with appropriate design, they may be
common to all EC elements.
FIG. 2 shows one arrangement of EC elements for analog display of
time. 60 dots 6 around the perimeter show the minutes, each one
coloring as that minute passes. 12 bars 7 interior to the dots show
the hours, only one at a time being in the colored state. At the
end of each hour, all dots will have been colored and are then
bleached; the hour bar is also bleached and the succeeding one
colored. The time shown is 5 minutes after 1 o'clock.
For the design of FIG. 2, in each hour all the dots and one bar are
required to be put through a color-bleach cycle. A typical total
area of EC display will be approximately 1 cm.sup.2. The required
20 mC at 1.4 volts represents energy usage of less than 30 mA secs.
This is an average power consumption of less than 10 uW. This does
not include power required for the electronic circuitry of an
electronic watch. Such a watch display will operate continuously
and will not require either a "demand" switch for displaying the
time or an exceptionally large battery. The battery can be from 0.7
to 1 V e.m.f., which can provide ample power for the entire watch
for more than 1 year.
Another type of EC analog time read out is shown in FIGS. 3 and 3A.
On face 9, hours are displayed by bars 10 which consist of WO.sub.3
on NESA glass 12. Counterelectrodes 11 for the hour bars 10 are
electrodes of WO.sub.3. Minutes are displayed by a minute ring 13
also NESA glass 12. This open ring consists of a continuous
WO.sub.3 film and works like a timer. Two electrodes 14 and 15 are
deposited at the ring ends near numerical 12 (printed or etched on
NESA glass 12 and are insulated from each other (no electrolyte
between electrodes). By applying a voltage between .crclbar. 14 and
.sym. 15 electrode, coloration starts at .crclbar. and slowly moves
towards .sym.. By use of an electrolyte 16 a resistance match
between the WO.sub.3 ring and electrolyte is achieved so that low
voltages can be used. The components are adjusted so that
resistance and available voltage provide coloration of the complete
ring in exactly 1 hour. The speed of coloration is also made
constant over this period of time.
Under the above conditions, bleaching of the completely colored
ring 13 may be accomplished by applying a proper voltage pulse
between colored WO.sub.3 ring 13 and the counter-electrode 17 as
shown in drawing. The counter-electrode cannot be a full ring or
else bleaching will start at .sym. and .crclbar. electrodes and
prevent the rest of WO.sub.3 from bleaching. It, therefore, should
consist only of a short length located close to 6. All
counter-electrodes are deposited on a NESA glass 18, such as gallic
acid for use in certain electrochromic display device
applications.
In addition to the gelled electrolytes described, acid or salt
electrolytes may also be employed. Acids and salts compatible with
the electrochromic material and counter-electrode are used. Such
materials are described copending, commonly assigned application
Ser. No. 41,154, filed May 25, 1970. The acids include for
example:
1. Aqueous sulfuric acid solutions ranging from 0.1 to 12.0
molar.
2. Sulfuric acids solutions of propylene carbonate, acetonitrile,
dimethyl formamide and other organic solvents compatible with
sulfuric acid.
3. Strong organic acids, such as 2-toluene sulfonic acid, in
propylene carbonate and other organic solvents.
4. Alkali metal or alkaline earth metals or rare earth metal salts,
such as lithium perchlorate, nitrate, chloride, sulfate, etc., in
organic solvents, such as acetonitrile and propylene carbonate.
A distinct advantage of the above-mentioned solvents is their
dielectric and solubility properties leading to high conductivity
and high capacity.
Counter Electrode
The counter electrode is one selected from a group of materials
compatible with the electrolyte, as previously discussed, such as
tungsten oxide or molybdenum oxide. It is advantageous to use the
same material for both electrodes, although not necessary. In a
preferred embodiment of the present invention tungsten oxide is
employed for display and the same material as counter electrode is
employed in contact with the electrolyte.
Electrodes shown to be useful in sulfuric acid are described in the
article entitled "Reference Electrodes in Sulfuric Acid,"
Electrochemical Technology, May-June 1966, pp. 275-276.
A specific example of a counter electrode compatible with sulfuric
acid and useful in the present invention consists of a porous lead
metal plate.
Other electrodes which can be used in sulfuric acid are shown in
Table I:
TABLE I ______________________________________ Mercury - Mercury
(II) sulfate Gold - Gold (I) oxide Platinum - Platinum (II) oxide
Rhodium - Rhodium (III) oxide Tungsten Chromium (II) carbide
Zirconium - Zirconium (II) oxide Platinum Molybdenum Tungsten (II)
carbide Tantalum (II) boride Niobium Palladium Silicon - Silicon
(II) carbide Tantalum Tantalum - Tantalum (V) oxide Niobium -
Niobium (V) oxide Niobium (II) carbide Hafnium (II) carbide
______________________________________
EC is also utilizable in digital displays. Either matrix type (7
.times. 5 dot matrix) or segment type (7 segments in figure "8"
pattern) can be employed as shown in FIGS. 5 to 7, and 12 to 15.
These displays are similar to EC configuration to the analog
displays, but they require switching many elements as each minute
changes; hence they involve greater current drains. A demand switch
may be required which would actuate the EC display only when the
display of time is actually desired. FIG. 4 shows a block diagram
for an electronic watch having a crystal oscillator 19, divider 20,
logic 21, driver 22 and display elements 23, battery 24, demand
switch 25, and set and reset button 26. The elements of the
electronic watch circuit may vary somewhat, and the precise circuit
design is not a part of this invention. Typical circuits are shown
for example in U.S. Pat. Nos. 3,194,003; 3,258,906; 3,276,200;
3,485,033; or 3,505,804. A design as shown in FIG. 4 may be for
example as follows:
The oscillator comprises a quartz oscillator operating at 32,768 Hz
vibrations. These 32,768-Hz vibrations are first divided down to 1
Hz at 20 and then are fed into logic-pulse counting circuitry
21.
There are five counters in series, able to divide by six, 10, and
12 units for second, minute, and hour counting. The last counter
covers 12 hr. Each of the counters triggers the next sequence.
A part of the logic circuitry is a decoder, which takes the binary
representation of a number and converts and encodes it for a 35-dot
matrix display of each numeral. (FIG. 13). For example, "five" is
represented by binary 1 and binary 4, and the decoder indicates
that this is a five. When the demand switch 25 is activated, the
driver 22 is activated and feeds power to the selected display
elements at 23.
Logic circuitry consists of a number of individual hybrid
substrates, which include integrated circuits:
The oscillator and countdown circuit divides the oscillator
frequency down by a factor of two to a usable frequency. Five
frequencies are provided by the 14-stage divider. An 8-Hz
frequency, for example, is used by the seconds-counter circuit,
while other higher and lower frequencies are fed to other
circuits.
Operational control circuit controls the 11/4 seconds that hours
and minutes are displayed on the watch face plus display of seconds
beyond the basic interval. Another function is controlling setting
of minutes, which also automatically resets seconds.
Seconds counter circuit is another logic substrate that counts the
seconds that are displayed on command, and it also generates a
signal to make the minutes display change from "59" to "00."
Minutes counter circuit counts the minutes and generates a signal
to make the hours display change from "12" to "1."
Hours counter circuit counts the hours from "1" to "12."
Power switching circuit supplies power to six display decoders. The
decoders-one for each digit-convert binary coded decimal
information from the counter circuits into numbers. Each matrix has
35 dots, composed of electrochromic material.
As there is no conventional stem for winding and setting, time is
reset by depressing a switch 26. There may be one switch to reset
hours; and another, minutes and seconds.
The watch of FIG. 4 has a digital display of time as shown in FIG.
7, except using the dot matrix numerals of FIG. 12. It will be
obvious that the bar matrix of FIGS. 5 to 7 or 14 can be used by
use of appropriate switching means in logic unit 21.
As shown in FIGS. 8 through 11, the electronics may be a single
integrated circuit package 27, fitting in case 28, with a battery
24. The display unit and crystal may be an integrated unit 29
fitting into case 28. Appropriate plug connections, not shown but
which will be within the skill of the art, are provided to connect
battery 24, electronics 27 and display 29. In FIG. 9, a bar matrix
has been colored to show a number "3" in the normal manner.
The display unit 29A of FIG. 10 varies somewhat from that of FIG.
8, in that it includes an illumination means 30. By use of a
transparent electrolyte the numerals can be displayed in reverse
mode, as shown in FIG. 11, in an illuminated manner. For this
variation, the display area surrounding the matrix will also have
to be opaque. Moreover, a change of location of the counter
electrodes 31 is made as shown in FIG. 14, so that they are in the
same plane as display bars 32. In this application, all segments
when not displaying time will be colored, and bleached to display
time. This is possible in the present invention since the
electrochromic material is persistent and requires no current to
remain in the colored state.
In FIG. 12, a 35 dot matrix is shown with the number "2" colored.
FIG. 13 shows a coloration of the dots 32 on the farthest right
vertical line and the coloration of opposing counter electrodes 33
when both are of similar material such as tungsten oxide. Electric
connections from one set of dots are represented symbolically at
34.
In FIG. 16 is shown an extremely compact timing device. The device
is designed based on any small battery 35 to have the electronics
36 deposited on one side and the display 37 on the other and to fit
in a case 38. Such a device could be extremely compact and useful
where small size and light weight are desirable. Case 38 could be
an encapsulating plastic material.
It will be obvious that numerous variations could be made by
persons skilled in the art within the scope of the foregoing
description. Other circuits could be employed for an electronic
watch. A wall clock operable from line voltage is also possible
with the proper logic. The invention is intended to include any
combination of an elapsed electric current accumulator and means
for its display.
* * * * *