US3540209A - Horological time display - Google Patents

Description

Nov. 17, 1970 N. c. zATsKY ETAL 3,540,209

HOROLOGICAL TIME DISPLAY I Filed June 12, 1969 3 sheets-sheet s FIG. 8

FIG. 9

FIG. IO

IN VENTORS Nov. 17, 1970 N, C, zATsKY ETAL 3,540,209

HOROLOGICAL TIME DISPLAY Filed Junelz, 1969 3 sheets-sheet 2 NVVENTORS /VRMAN C. ZATSKV EUGENE RKEELEP NOV. 17, 1970 N, Q ZATSKY ET AL 3,540,209

HOROLOGICAL TIME DISPLAY Filed June l2. 1969 3 Sheets-Sheet l d ze P7 FIGAf INVENTORS NORMAN C. ZA TSKY EUGENE l?. KEELER United States Patent O 3,540,209 HOROLOGICAL TIME DISPLAY Norman C. Zatsky, Briarcliil Manor, and Eugene R.

Keeler, Sulern, N.Y., assignors to Timex Corporation, Waterbury, Conn., a corporation of Connecticut Continuation-impart of application Ser. No. 749,607, July 31, 1968. This application June 12, 1969, Ser. No. 834,237

Int. Cl. G04b 1]/00 U.S. Cl. 58-50 15 Claims ABSTRACT OF THE DISCLOSURE An electronic watch includes, within a case, a battery, a time base such as a crystal oscillator, a series of countdown circuits, and a time display. The time display includes a transparent watch crystal, a dial plate, and a liquid electro-optical material between the crystal and the dial plate. The crystal or the dial plate, or both, have a plurality of conductive transparent lines. The lines are electrically triggered in sequence to provide a moving indication of the time which appears similar to moving hands. The time display may provide a number of the AND circuits used in decoding, in addition to displaying the time. Alternatively, the time display may utilize a ferroelectric ceramic material.

DESCRIPTION This application is a continuation-in-part of the applicants now abandoned U.S. application Ser. No. 749,007, filed July 31, 1968, and entitled Horological Time Display.

The present invention relates to horology and more particularly to the time display of an electronic watch.

Many types of electric Watches, in which a battery within the Watch case drives a motor, have been suggested and a few types have been placed in commercial production. It has been suggested that the motor simply wind up the spring of a conventional mainspring driven watch. But this type of a watch would be bulky, use a considerable amount of power and not be any more accurate than a spring-driven watch. Watches have been built in which the balance wheel acts as the armature of the motor; for example, the balance Wheel may carry a coil or a magnet. The balance wheel drives the gears of the Watch either directly or by means of a fork mechanisn. A watch in which the time base is a balance wheel inherently has limitations due to the relatively low rate of the balance Wheel oscillation and to position error.

An electronic watch has been produced using a tuning fork as its time base. Other types of vibrators have also been suggested as the time base for a watch. However, it is still necessary in those watches for the vibrator to mechanically operate an index wheel, which requires a delicate and expensive mechanism. All these types of watches utilize physically rotating hands to indicate the time. Fully electronic Watches, using a crystal or vibrator time base, have been suggested in which the time display, in place of rotating hands, would be a series of lamps or lamp-like devices, or a numerical display. In a numerical display, one oclock is shown as 1:00. However, the high power consumption and cost of lamps and lamp-like devices has made such suggestions impractical. In addition, numerical displays are not desired in a Watch by the consuming public.

It is an objective of the present invention to provide a portable watch which is wholly electronic, i.e., without any moving parts, and which uses means other than physically rotating hands to display the time.

It is a further objective of the present invention to provide an electronic time display which appears to rotate around a dial and which does not display changing numerals.

It is a further objective of the present invention to provide an electronic Watch having an electrically operated time display which is low in power consumption.

It is a further objective of the present invention to provide an electronic watch which utilizes relatively few active elements for decoding.

In accordance with the present invention, an electronic watch is provided having a crystal, a dial plate, and a time base, such as a crystal oscillator or a vibrator. A number of count-down dividing circuits re connected in tandem to the time base. A decoding system converts the binary code produced by the count-down circuits into a time display.

-In one embodiment, the time display consists of sixty conductive radial lines evenly spaced on the back of the crystal or on the face of the dial. The crystal is spaced from the dial a short distance and the space filled with a suitable liquid crystal material. The time display may be constructed with a set of such conductive lines shadowing a set of conductive segments on the opposite surface of the thin layer of liquid crystal material. The lines and segments are, in effect, two input AND circuits and may be used, in place of other active elements, in the decoding system.

In another embodiment, a thin plate of a suitable ferroelectric ceramic is used as the dial. The ferroelectric plate is normally only translucent but become transparent in selected discrete areas when electric fields are applied in those areas. The ferroelectric plate covers a colored or mirrored backing. The elds are applied by transparent conductive lines on one side or both sides of the plate. The plate becomes transparent in lines, revealing the backing material; and, as the electric iield areas change, the lines change, giving the impression of moving hands. One embodiment of ferroelectric display may also be used in the decoding system.

Other objectives of the present invention will be apparent from the description of a preferred embodiment of the invention, taken in conjunction with the accompanying drawings, in which:

FIG. l is a top plan view of the Wrist watch of the present invention with its crystal and dial partly broken away to show its internal mechanism;

FIGS. 2, 3, 4, 5, 6 and 7 are top plan views of alternative dials utilized in the wrist watch of the present invention; and

FIGS. 8 and 9 are side cross-sectional views of dial plates of ferroelectric ceramic material.

As shown in FIG. l, the watch of the present invention is shown as being a wrist watch having the external shape and approximate size of conventional spring-driven wrist Watches. The time display of the present invention is not, however, limited to such wrist watches but may be utilized in pocket watches, clocks and other horological instruments.

The wrist watch of FIG. 1 includes a one-piece case 10 having a unitary bezel portion '11. A transparent crystal |12 closes the case, which may be made waterproof. A dial plate 13 is positioned beneath the crystal 12 and spaced a short distance from it. A small electric battery cell 14, within the case 10, has one of its contacts grounded to the case. For greater power, additional cells may be utilized within the case. The second contact 15 of cell 14 is connected to a terminal of the electronic circuit 16.

The electronic circuit 16 includes a time base 17 which preferably is a piezoelectric crystal in a self-oscillatory circuit. Alternatievly, a vibrator, for example, of the type disclosed in Sparings U.S. Pat. 3,201,932, may be used as the time base. The time base 17 is connected to a series of count- down circuits 18, 19 and 20, only three of which are illustrated. A suitable count-down circuit is a lowpower consuming flip-flop counting circuit which counts down (divides) by two. The flip-flop circuits are connected in tandem as a counter to provide an electrical output at a predetermined rate. For example, to obtain output pulses at the normal rates of 1 second, 1 minute and l hour, a piezoelectric crystal of 32.768 may be used. The crystal, which is part of a self-oscillatory circuit, has a pulse output rate of 32.768 kHz. The output of the crystal oscillator is connected to fifteen binary divider circuits in tandem, yielding an output of l pulse per second. This output may be connected to ring counters to display seconds, minutes and hours. Preferably the piezoelectric crystal is small, so as to consume little power, and the flip-flops and other circuits are integrated circuits.

The rst embodiment of the time display is shown in FIG. 2. 'In this embodiment the dial plate is electrically conductive and connected to one terminal of the battery. The dial has printed thereon a set of numerals 21 or other time indicating marks. The dial has an outer ring 22 and an inner circle 23 which are preferably of a roughened or sand blasted appearance. The crystal has sixty evenly spaced thin lines which are used to indicate seconds. These lines are radially aligned and printed in conductive transparent material, such as tin oxide, on the back (inner) face of the crystal. These sixty lines, which excited by the electronic display counter one after another clockwise in sequence, cause a liquid crystal material to become reflective to light. One of these sixty lines 24 is shown as being triggered and becoming visible.

A second series of sixty evenly spaced similar transparent and conductive lines 25, on the back of the crystal, indicates minutes and hours. These lines 25 are thicker than the thin seconds lines 24. As shown in FIG. 4, each of these thicker lines 25 consists, upon close examination, of two non-connected segments. The first segment 26 is close to the inner circle 23 and the second segment 27 is close to the outer ring 22. The first segment 26 is separated by a small non-conductive gap 28 from the second segment 27. The rst segment 26 and the second segment 27 have connected leads, respectively, leads `29' and 30. As shown in FIG. 2, the minute hand 31 is formed by triggering both segments, so that the line is visible from the inner circle to the ring. The hour hand 32 is illuminated when the first segment is triggered.

The dial plate and the crystal are separated by a small uniform space, for example, .01 millimeter. The space between the dial plate and the crystal is filled with a liquid crystal which changes its optical properties when a Voltage gradient is placed across the material. For example, the liquid crystal material may be an organic thermotropic nematic molecular material which changes from a clear liquid to a liquid which scatters light when positioned between charged plates, such as 6-methoxy-2-naphthoic acid. This is a change from a clear to a frosted appearance when a voltage difference is applied to the plates between which the liquid is positioned. The liquid crystal may alternatively change color. The transparent conductive lines may be very line for example, 400 lines per inch, as the optical change in the liquid crystal has sharp boundaries.

The second embodiment of the present invention is shown in FIG. 3. As in the previous embodiment, the entire dial is conductive and connected to a battery terminal. The dial has a series, of number 33 printed on its face, indicating time. The dial has three separating rings-an outside ring 34, a rst inner ring 35, a second inner ring 36 and a central portion 37, all of which may be colored or patterned for decorative purposes. The crystal has three thin rings, each of which is formed of 60 short segments of transparent conductive material on the inner (back) side of the crystal. The outer ring 38 represents minutes, the center ring 39 represents hours, and the inner ring 40 represents seconds. The dial plate directly under each of the rings 38, 39 and 40 is black. The segments of all of the rings 38, 39 and 40 are electrically excited, except for one segment in each ring. The one untriggered segment in each ring is clear (not opaque) and permits the black marks 41, 42 and 43 to show through, indicating time. All the other segments are triggered and cause the liquid crystal material directly beneath the segment to be opaque and to hide the black marks.

The consumption is directly proportional to the area charged. Consequently, the narrow bands utilize relatively little power, although 59/ 60 of the bands are always charged.

To help distinguish the seconds indication from the other time indications, the second indication may be liashed with on-off periods at a visible rate, such as ten cycles per second. As another example of a possible modiication, in the embodiment of FIG. 2 the liquid crystal material need only occupy a closed space, considered in the plan view, formed between the inner circle and the outer ring. As still another example of a modification, the transparent conductive lines may be printed 0n a separate clear sheet positioned behind the crystal and above the dial, the liquid crystal material being positioned between the dial and the clear sheet.

Another embodiment of the invention is shown in FIG. S. The dial 12 or the crystal 13 carries permanent markings in the form of numerals and/ or lines in the zone of an outer ring 45, similar to the embodiment of FIG. 2. This zone `45 has a roughened or sandblasted appearance. The annular zone between the outer ring 45 and the center circle 23 is used for the display of time which appears to move. There are sixty evenly spaced lines 46 which are used to indicate both minutes and seconds. Any particular one of the lines y46 remains energized for one minute. At the end of one minute, the next line 46 of the sequence is energized for a minute. During the one-minute interval, successive lines of the sixty lines are flashed for a small fraction of a second at one-second intervals, giving the impression of a sweep second hand.

As shown in FIG. 5, a set of twenty-four evenly spaced lines 47 are somewhat shorter and heavier than the rst set of lines 46. Every other one of these lines 47, such as line 47a, is closely adjacent to a line 46 of the first set which coincides with the position of the hour hand of a conventional watch at the full hour. The remaining twelve lines 4711 occupy the position of the hour hand of a conventional watch at the half hour. Each of these twentyfour lines `47 is energized for one-half hour, after which the next line of the set 47 is energized in clockwise sequence. The iirst mentioned twelve lines 47a are energized (one at a time) from 15 minutes before the full hour to l5 minutes after the full hour, the second group 4711 is energized from l5 minutes after the hour to l5 minutes before the next hour. This arrangement resolves any ambiguity which might occur if only twelve lines were used for the hour display, such as mistaking an indication of 12:58 for 11:58.

'In the embodiments of FIGS. 6 and 7, the number of necessary active elements, such as transistors, is reduced by using the time display to perform two functions. The time display is used for its normal function of indicating time. In addition, the display elements are used as double input gate AND circuits to decode the output of the countdown circuits.

The seconds display counter described in connection with FIGS. 6 and 7 of this invention has sixty separate and distinct output states Iwhich must be decoded from a 6-bit binary code to a one out of 60 code to drive the 60 seconds indicators. A binary code may use a 0 or l in each position so that a six-bit binary code may be 010011. The combinations of zero and one using six bits are 26 or 64. The binary code is produced by the tandum series of count-down circuits. The decoding is accomplished, using digital techniques, by utilizing a series of logical gates. The required conversion could be done using 60 six-input AND gates, but this is wasteful of circuitry requiring 360 (6x60) active devices.

'Each of the sixty AND gates would have six inputs. The AND gate would operate only when pulsed with the particular binary code for that gate. For example, the six-bit code 010011 will operate the one out of the sixty AND gates which is pre-cooled to produce an output when that code appeared in that order and simultaneously at its six input gates.

Another method of decoding, which is more economical from a point of View of hardware, uses what is known as two-level gating. In two-level gating the six-bit binary code is split in half. The three most significant bits are decoded to a one out of eight code using eight AND gate circuits each having three inputs and the three least significant bits are also decoded to a one out of eight code. The outputs of each of the first group of eight gates with the outputs of the second group of eight gates, via 46.0 AND circuits, each having two inputs, yield the required 1 out of 60 format. This method uses only 168 (2X60-l-3X8-l-3X8) active devices.

It is possible to lower the count of active devices required for decoding by using the display element as part of the decoding matrix as shown in FIG. 6. For this approach the sixty transparent and conductive lines are deposited on the back face of the transparent watch crystal 12 as before. The dial 1%` has a pattern of eight annular segments S057 formed of a conductive material which may also be transparent. Seven of the segments 50-56 each mask 8 lines of the top plate, the eighth segment 56 masking four lines. The sixty top radially aligned lines 60 are electrically connected in the following manner, counting each of the sixty lines in sequence:

The dash between the numbered lines, above, indicates an electrical connection between them. As in two level gating, the -6Lbit counter is split in half and the three most significant bits are decoded yusing eight AND circuits each having three inputs. The outputs of these circuits are designated A11, A2, A3, A4, A5, A6, A7, A8. The least significant bits are decoded in like manner and the outputs of their circuits are designated B1, B2, B3, B4, B5, B6, B7, BS. A1 is connected to a switch which, when activated, connects a voltage source V1 to the first annular segment 50. A2 through A3 drive the remaining annular segments 51-56 in like manner. B1 is connected to a switch which, when activated, connects a voltage source V2 to line segment 1. B2 through B18 drive line segments 2 through 8 in similar fashtion.

With the counter in position zero, A1 and B1 are both ON and line segment 1 is activated. After one second, B1 turns OFF and B2 turns ON, activating line segment 2. After eight seconds, B8 turns OFF, recycling the decoder to B1 while A1 turns OFF and A2 turns ON This combination energizes line segment 9. In this manner all 60 line segments are activated sequentially with only 48 (3X8-i-3X8) active decoding elements. The liquid crystal is optically affected only when a voltage is placed across it, i.e., when there is a Voltage difference between a segment and a line. In effect, the liquid crystal, segments and lines act as two-input AND circuits. In a two-input AND circuit, both gates must be activated simultaneously for there to be an output. The segment may be considered one input and the line, the other input and the optical response the output.

This method becomes even more attractive if the back watch plate comprises two concentric segmented rings 70 and 71, as shown in FIG. 7. Herein data from the hours counter is presented to the 60 line segments on pulsed basis at a 50% duty cycle. When the hours date is being displayed, only the inner concentric ring is energized, so that the display is a short line segment. During the other half of the time, data from the minutes counter is displayed with both rings energized. This displays a longer line segment.

If the information is pulsed rapidly (greater than 30 times per second) the human eye tends to integrate the flickering so that the display appears not to blink.

An alternative construction to the liquid crystal cell is a solid ferroelectric electro-optically active ceramic plate. This material is a polycrylstalline ferroelectric ceramic. A preferred material is a hot pressed rhombohedral lead zirconate-lead titanate ceramic. The ceramic is pressed into a thin plate and polished.

As a specific example, the material may tbe a solid solution containing about 64% lead zirconate, 34% lead titanate, and 2% bismuth oxide. The solution is pressed for one hour at 3000 p.s.i. and at 1300 C.

Preferably, as shown in FIG. 8, the dial plate of a `watch consists of a thin ferroelectric ceramic plate 8'1, for example, a thickness in the range of .1 mm. to .01 mm., mounted on a non-conductive colored or mirrored backing material 82, for example, of a compatible ceramic material. A thin transpartent layer of conductive material 83, having the desired pattern, is sandwiched between the ferroelectric ceramic and the backing material. A second thin transparent conductive layer 84a and 84b, which may or may not have a pattern, is adhered to the top surface of the ferroelectric ceramic. As shown in FIG. 8, a voltage field is applied across 8417 and 83, switching the area between them to a uniform parallel polarization and causing it to 'become transparent. That area, which may, for example, be a seconds indication, will become transparent and permit the color or mirror of the backing material 82 to be seen.

As shown in FIG. 9, a dial plate consists of a thin normally transparent ferroelectric ceramic plate 91 mounted on a colored or mirrored rigid non-conductive backing material 92. The plate is poled, in its course of manufacture, in a D.C. field and, after removal of that field, still retains its polarization. A thin transparent conductive line pattern 94a and 94b, having the desired pattern, is adhered to the top surface of the ferroelectric ceramic. As shown in FIG. 9, a voltage field is applied between lines 94a and 94h, switching the area between them to a different polarization and causing that area to scatter incident light. That area is an indication of time, for example, an hour hand position. The area `93 between the conductive lines 94a and r94b, when it becomes frosted (scatters light) does not permit the backing material to show through.

The decoding pattern described in connection with FIG. 6 may be used with the ceramic structure of FIG. 8. The other patterns of FIGS. 2, 3, 4, 5 and 7 may be used with the ceramic structure of either FIG. 8 or FIG. 9. The pattern may be placed on the front face or the rear face of the ceramic plate, or on both of its faces.

It is desirable, in the structure of FIG. 9, that the space between the conductive lines be as narrow as possible so that lower voltages may be used. As shown in the top plan View of FIG. l0, the conductive line lies in an interdigital pattern with the conductive line 101 forming a small gap 102 between them. The gap 102 becomes transparent with a voltage is applied between lines 100 and 101. The gap 102 is preferably only a few mils wide. A line appears, when the gap is viewed from a little distance, which appears to be almost a solid line running in the direction of arrow 103'.

We claim:

1. An electronic horological device including a case, a source of electrical power, a time base, an electronic circuit, a dial plate, a crystal, and a. time display, wherein the time display includes a liquid crystal material behind the face of the crystal, a plurality of conductive transparent lines on said crystal and a plurality of conductive arcas on said dial, said lines and said areas ibeing positioned to create a voltage gradient across the liquid crystal material and triggered in sequence by said electronic circuit, said lines being radially aligned relative to the center of said dial.

2. A horological device as in claim 1 wherein the horological device is a wrist watch and the source of electrical power is a battery cell iwithin said case.

3. A horological device as in -claim 1 wherein the time base is a crystal oscillatory circuit and the electronic circuit includes a series of count-down dividing circuits.

4. A horological device as in claim 1 wherein the liquid crystal is an organic mematic material.

5. A horological device as in claim 1 wherein the said lines are formed into a rst group of sixty evenly spaced and radial lines and a second group of sixty evenly spaced radial lines.

6. A horological device as in claim 5 wherein each of the lines constituting the said second group of lines consists of a rst segment, a second segment, and a gap between the segments, and wherein the said segments each have separate connection lines.

7. A horological device as in claim 1 wherein the transparent lines form three concentric rings, with each ring consisting of sixty segments separated by gaps, each segment having an independent connecting lead.

'8. A horological device as in claim 1 wherein the said transparent lines are on the underside of the watch crystal and the liquid crystal material is positioned between the crystal and the dial.

9. A horological device as in claim 1 wherein the time display comprises a set of conductive lines and a set of conductive segments which shadow the said lines, the said lines and segments constituting two-input gate circuits utilized for decoding.

10. An electronic horological device including a case, a source of electrical power, a time base, an electronic circuit, a system, a dial plate, a crystal and an electro-optic material, wherein the crystal and dial plate constitute iirst and second display substrates, one of the said substrates having a plurality of conductive lines and the other having a plurality of conductive areas, the electro-optic material being positioned between the said lines and the said areas, and the lines and areas being positioned to create a voltage gradient in the electro-optic material.

11. An electronic horological device including a case, a source of electrical power, a time base, an electronic circuit, a dial plate, a crystal, and a time display, wherein the time display includes an electro-optical ferroelectric ceramic material behind the face of the crystal and visible through said crystal, a plurality of conductive transparent lines positioned on said crystal and a plurality of conductive areas positioned on said dial to create a voltage gradient in the ceramic material and triggered in sequence by said electronic circuit, said lines being radially aligned relative to the center of said dial.

12. A horological device as in claim 11 wherein the horological device is a wrist watch and the source of electrical power is a battery cell within said case.

13. A horological device as in claim 12 wherein the time base is a crystal oscillatory circuit andthe electronic circuit includes a series of count-down dividing circuits.

14. A horological device as in clai-m 12 wherein the ceramic material is a hot pressed lead zirconate titanate solid mixture in the form of the plate in the order of one mil thick.

15. A horological device as in claim 12 wherein the ceramic material is a thin polished plate in the order of one mil thick mounted on a colored or mirrored rigid backing plate.

References Cited UNITED STATES PATENTS 4/1969 French 340-173 l2/1969 Langley 1 58-50 X U.S. Cl. X.R. 340--

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