Solid state/Consumer products

0~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The electronic watchThe electronics industry is beginning to profit from anunexpected source-a third of the world's watch market

Marce Eleccion Staff Writer

After remaining relatively unchanged for four duced worldwide each year qualify to be called "elec-centuries,* the wristwatch has undergone a drastic de- tronic."sign upheaval in only the last six years-and this is Despite the fact that circuit complexity in theproving a boon to the United States electronics indus- range of electronic watches from spring-balance totry. At the roots of the wristwatch revolution is the quartz movements increases by about three orders ofradical transition from a completely mechanical to a magnitude, there exist certain standards by which tocompletely electronic "movement," a metamorphosis evaluate all electronic-watch operation. Not the leastthat promises to severely threaten Swiss dominance of these is the fact that, since watch volume aboveof the world's watch industry. Yet, in spite of a tech- 3-4 cm3 becomes impractical, successful circuit mini-nology that has enabled the marketing of watches aturization, especially at higher complexities, makeswith purported accuracies within a minute a year at the use of ICs almost mandatory. As a result, logicprices starting at less than $100, serious questions are circuits with their superior component tolerances be-being raised regarding whether such accuracies can come preferred over more complicated analog circuit-indeed be maintained, and concerning the acceptabil- ry, even with the disadvantage of a higher componentity of the state-of-the-art digital displays required for count.completely electronic operation. Power consumption is another factor that must be

Nevertheless, growth opportunities for manufactur- considered in successfully designing an electronicing and marketing investors seem excellent, with watch. In order to obtain at least a year of continuoussales of $50-and-up watches expected to be dominated operation, a successful trade-off must be obtained be-within a few years by electronic watches offering su- tween the type of energy source (at present a battery)perior accuracies at prices brought lower and lower by that can fit within the limited volume and the cur-reduced manufacturing and labor costs. Considering rent drain of the various operational componentsthat $600 million of the 1971 worldwide watch manu- (e.g., ICs, stepping motors, displays). With the 100-facturing-sales level of almost $2 billion consisted of 200-mAh mercuric-oxide (1.3 volts) and silver-oxide$50-and-up watches, the prospects of capturing even a (1.5 volts) cells that are now commercially available,portion of this multimillion dollar market with low- current limitations are restricted to 10-20 MA.volume production ($50-and-up watches represented Other parameters affecting watch operation includeonly 6 percent of total units produced) should make temperature (the watch should perform properlyeven the most traditional watchmaker enthusiastic. within the limits of -100C and 60°C), shock (a factorIn the United States alone, the $50-and-up market that can severely limit accuracies in certain mechani-(36 percent of a total manufacturing-sales level of cal designs), and humidity. This last condition has a$485 million in 1971) could reach 50 percent of total decided effect upon watch circuitry, which should besales by the mid-70s. A U.S. national publication has relatively insensitive to such problems as currentalready estimated that by 1980, the largest segment leakage between high-impedance areas.of the 100 million quartz-crystal watches produced bythen will have been made in the United States. Spring balances and tuning forks

The., basic configuration for both contact/contact-The electronic watch less spring-balance and tuning-fork movements usual-

Electronic watches have been defined as timekeep-ing devices that possess electronically driven contact- *The watch came into being when Peter Henlein introduced his Nur-

. | s . ~~~~~~~~~~~~embergegg-shaped version in 1511.lesst spring-balance movements, tuning-fork move- tThe distinction between contactless spring-balance movements andments, or quartz-crystal-controlled movements with the older electrically driven spring-balance movements .fhould bemade clear. In both cases,t power is transmitted to the balance -wheeleither a vibrating or stepping motor or a solid-state electromagnetically. However, in an electric watch, the coil isdisphiy.' Under this definition, only about one mil- switched via electric contacts operated by the balance wheel itself;' ~~~~~~~~whereasin the electronic version the switch iS replaced by a transis-lion of the approximately 170 million watches pro- tor.

24 IEEE spectrum APRIL 1973

ly involves interaction between a coil and a magnetic stant, and hence the transducer is linear and inducedcircuit, with one element stationary and the other voltages are sinusoidal. Other types of driving circuitrymounted on a resonator.' A typical geometry for a have been proposed for spring-balance and tuning-forkspring-balance movement is shown in Fig. 1; here the movements that utilize a single coil and require com-magnetic circuit (two small permanent-magnetic plementary transistors.disks and two connecting soft-iron strips) is attachedto the balance wheel and electromagnetically inter- Quartz-crystal oscillatorsacts with a fixed flat coil (shown as Li and L2 in Fig. One of the first quartz oscillator circuits to be de-1B) as they pass each other. Specifically, voltages of signed for a commercial electronic wristwatch wasalternate polarity are induced in the pickup coil L,, used in the Beta 21 movement offered by the Centrewith positive pulses causing the transistor T to satu- Electronique Horloger (CEH) S.A. of NeuchAtel,rate and the collector current through the drive coil Switzerland. Operating at 8192 Hz, the quartz of thisL2 causing the resonator to accelerate. symmetric two-transistor negative-resistance circuit

Self-regulation comes in the form of biasing ele- (Fig. 2) oscillates close to its series resonance; hencements R and Cl, which hold the transistor below cut- frequency and stability are determined solely by theoff between induced positive pulses for low current mechanical properties of the quartz.' In order to haveconsumption, with C, providing a variable bias con- oscillation, the quartz-crystal resistance must be ex-trol at every positive charge, thus adapting the tran- ceeded by the negative resistance (-2R.) betweensistor bias to the system. Further and more crucial points Q, and Q2 (Fig. 2B) by a margin of approxi-self-regulation is provided by L2, whose induced volt- mately 3:1. Above this margin, the sensitivity of theage is proportional to the spring-balance velocity. oscillating frequency increases with respect to IC

In tuning-fork drive circuits, the higher-frequency parasitic capacitances, thus driving the circuit harderoscillations require different component values than toward its nonlinear region and causing frequency in-that for spring-balance circuits, with coils in the form stability due to circuit-dependance.of solenoids that interact with coaxial magnetic cir- Since no reactive elements are contained in thecuits mounted on the tines of a tuning fork. Obvious- type of circuit just described (successful at frequen-ly, with oscillations as small as 25 gm in distance, cies up to 32 kHz), signal phase shift becomes a neg-electromagnetic coupling remains practically con- ligible problem and frequency stability is excellent.

A-Block diagram of an electronic watch. Note that a motor-drive system is required for a me-chanical hands display, whereas a decoder-network/readout-driver system functions as the inter-face between the CMOS IC and a solid-state digital display. A typical analog display system isdescribed in B, with the addition of a quartz crystal and input capacitor all that is necessary tocomplete the oscillator circuit contained on the Si-gate CMOS chip; the two buffers on this particu-lar Motorola chip are fabricated with MOS p-channel and n-channel enhancement mode devices.

AB

Battery 0/Df i ~~~~~~~~~~~~~~~~~~~~~~~~~~Wathh= 3276 16H5z Movement

C 5t30gpF egs

C, =trimmer capacitanceCou= integrated oscillator output capacitance

20 pFRFB = integrated oscillator feedback resistance

z40 MQ

Eleccion-The electronic watch 25

Hairspring even the use of three-terminal quartz resonators.'

Balanalance One of the great problems in quartz watches is thatwheel of adjusting oscillator frequency to compensate for

Coil l ~ Soft-iron tolerances in manufacturing the quartz and of main-strips taining an accurate frequency despite the effects of

Permanent magnets aging. In the Pierce oscillator circuit, this adjustmentA is made by way of a variable capacitor such as Ci (or

C2). The real problem in obtaining frequency adjust-+v

B C'VE ment by this trimmer capacitor method, however, liesBe Conduction in the fact that although miniaturization and stabili-

Ll'2 threshold ty must be achieved there is still only a limited ad-0.5v . justment range available, in addition to a high-

C2 R C1 0.3 V impedance node existing between the quartz and trim-T mer.

\%Jyt Other approaches have been taken in solving the1ypical values frequency adjustment problem. One such proposal2

Movement R CluC involves replacing the frequency divider with a preset3-Hz spring balance 3.3Mn 2.2/AF 4.7nF counter that changes the nominal count rate of the300-Hz tuning fork 2.2 Mn 1 yF 1 nF watch to obtain the required accuracy. A desirable[1] A-Spring-balance resonator with a magnetic circuit for feature of this technique is that the frequency of theelectrodynamic Interaction with a fixed flat coil. B-Basic quartz need not be critical, since it is used solely as adrive circuit for spring-balance and tuning-fork movements. stable frequency source.C-Induced base-emitter voltage for a spring-balance move- Frequency dividers. Because the major portion ofment.' quartz-crystal hands-display watch circuitry is dedi-

cated to frequency division, whatever fabricationtechnology is chosen to accomplish this task will most

[2] Example of a symmetric negative-resistance quartz oscil- probably determine the circuit design of the rest oflator circuit (A) with the negative resistance that must be the watch.* The most popular approach seems to liepresented to the quartz in order to have oscillation (B) and atypical current-voltage characteristic (C).1 in the use of a chain of binary divider stages, al-

though there still exists somewhat of a controversyA B N2R over the use of bipolar and CMOS circuits. One im-portant fact to remember concerning CMOS circuits,however, is that the length of the dividing chain can

Rc 2c 2re -2Rc be increased while the total power consumption re------- mains below twice that of the first stage.3

A binary divider stage consisting of an ac coupled\Ql Q2 flip-flop is shown in Fig. 4; here, the bistable circuitr = base-emitted junction (colored portion) is alternately switched from one to

resistance the other of its stable positions by the control circuit= kT/qI (black portion) in response to the positive slopes of

the input signal. Because this basic circuit (developedby CEH in 1967) consumed low power, the high re-

c sistances needed made integration difficult. For thisreason, CEH in 1968 realized a considerably improvedcircuit that contained more transistors and a low

QI Q2 3-MSl total resistance, and hence was easier to inte-lo > v grate. This circuit, which consumes 1 AA at 1.3 volts

& R and operates at up to 12 kHz, has been used in the820k Re e yfirst commercial IC watch since the spring of 1970

and is called Beta 21. It serves as the basic movementfor Bulova, Longines, Omega, Piaget, and others.The great applicability of CMOS circuits to micro-

power operation was recognized as early as 1963.4Furthermore, when combined with polysilicon gates,

At higher frequencies, however, there is an increase in CMOS logic circuitry dissipates 99 percent less powerphase shift resulting from parasitic capacitances, than standard MOS at low frequencies (see Fig. 5),causing oscillation to become as dependent upon ca- making it ideal not only for electronic watches, but

pacitance stability as it is on quartz shunt capacity for such applications as portable communication sys-Co. One solution to this problem (applicable to both temsandcalculatorsaswell.5low- and high-frequency operation), described by Max The basic building block in CMOS logic circuits islow-~~~ ~ ~ ~ ~ ~ ~ ~~~~h coplmntr inverterenc depictedn) in Fig. 6, whichForrer of CEH, entails the use of the single-transistor the complementary inverter depicted In Fig. 6, whichPierce oscillator circuit displayed in Fig. 3. also shows the characteristic power dissipation versus

Other circuit possibilities that have been proposed *It should be noted that in the all-electronic solid-state-displayfor high-frequency quartz operation include such de- watch the electronics associated with driving the digital display take

an even greater percentage of the overall circuitry than the frequencysign configurations as the Clapp oscillator circuit, and dividers.

26 IEEE spectrum APRIL 1973

VI HlgVI3gV,rvA

AvBC

p

) Output 4 ° [3] Phase shift at higher watch[O01 frequencies can be checked by

Quartz s ~, nJ a Pierce oscillator, which uses

channel transistors a basic three-point circuit (A)vX Ch1 C2 and a variety of current sources(trimmer) t (B); an actual Pierce oscillator

circuit appears in C.'

[4] Example of an ac coupled flip-flop binary frequency-divider stage (A), along with a current consumption vs. fre-frequency. The effects of added parasitic capacitance quency performance curve based upon a flip-flop with bi-

can be clearly seen from the fact that the discrete as- polar transistors.'sembly has a power/frequency ratio of nearly an orderof magnitude higher than the IC. Power consumptionis made up of a static part controlled by leakage cur-rents and a dynamic part needed to charge capacitor > 2.2 MC to the supply voltage VB at rate f, or Output

P = /CVB2 l|pF 5.6M

In solving the extremely difficult problems associ-ated with the low operating-voltage requirement ofCMOS circuits, companies have resorted to various T3 T1 T2techniques. At RCA, a CMOS binary divider stage 15 pFhas been realized with metal gates. Hughes also fabri- Icates with aluminum gates, adding two boron ion im- Inputplantation steps to the conventional diffusion process. AMotorola divider circuits consisting of Si-gate CMOS Bemploy binary toggle flip-flops and circular transistorgeometries with guard ring diffusion. At CEH, metal- 1000gate CMOS binary dividers were used until 1971,when silicon gates and improved circuitry gave labo-ratory performances of 1.2-nA/kHz consumption at1.3 volts and an upper frequency limit of 2 MHz. 200Prior to this, commercial CMOS binary divider stagesvaried between 20 and 50 nA/kHz at 1.3 volts and '4frequency limits between 1 and 2 MHz.' 5A typical electronic watch system using a mono-

lithic Si-gate CMOS integrated circuit is shown on 20page 25. Operation of such a system (in this case usingMotorola's MTD 160/161F IC) is as follows. Time- 10based by a 32.768-kHz quartz-crystal-controlled oscil- 0.1 0.2 0.5 1 2 5 10 20 50 100lator, the 16-stage binary divider circuit splits the f,, kHzoscillator frequency by a factor of 216 (65 536) to 0.5Hz. After wave shaping and buffering, the counteroutput drives a miniature stepping motor with two31.25-ms pulses that are 180 degrees out of phase (1 Of the first quartz watches to be marketed, Seiko'sHz total). The actual monolithic MSI chip contains 1969 "hands" watch contained a 14-stage hybrid-typethe oscillator, binary divider, and wave-shaping and frequency divider of discrete component chips, laterbuffering circuitry; measures 82 by 94 thousandths of replaced by a CMOS integrated circuit. Among thean inch; and contains 312 active devices. Except for other quartz watches that have appeared, one of thean oscillator trimming capacitor, the oscillator pas- most unusual has been an analog design by Longinessive components are also integrated. Total current that required so few components (19 resistors, 7 ca-drain (excluding the motor) is 5 uA with a 1.3-volt pacitors, and 14 transistors) that it was fabricatedbattery and 5.5 AA with a 1.5-volt battery. with discrete components. Utilizing a vibrating reso-

Eleccion-The electronic watch 27

nant motor as a secondary hands-driving oscillator,this model compared the phases of the secondary I Watching the timesoscillator (170 Hz) and the primary quartz oscillator For the last three centuries, the fundamental tech-(9350 Hz) to determine the error signal in order to nology of wristwatches has been inextricably woundsynchronize the secondary frequency. in the principle of main spring and oscillating bal-

ance wheel. Improvements in this mechanical con-Motor drivers. The sole function of the motor driv- figuration have come in such forms as jeweled wrist

er logic circuit is to interface the frequency divider movements (18th century) to improve accuracy byand the hands-driving motor by generating pulses of' reducing wear at critical friction points. Although a

duration, polarity, voltage, and current. A typ- self-winding sliding-weight arrangement was intro-proper auration, polarity, voltage, anu currem. A typ- duced as early as 1780, 1924 marks the real begin-ical driving circuit for a 256-Hz vibrating motor is one ning of the practical self-winding watch. By the mid-that delivers unipolar pulses of 1-ms duration with a 50s, mechanical winding became a thing of the past0.25 duty cycle and peak currents of' 16 juA. Compli- when the concept of a battery-driven motor became acations begin to appear when longer pulse lengths reality, increasing watch accuracy from a deviation of

5 min/month to 3-5 min/month while reducing themechanical components by 10 percent.*

Conventional watches continued to maintain theirmarket superiority, however, until Bulova guaranteedan accuracy within 1 min/month with its Accutronline in 1960. Based on the principle of tuning forkoscillation and battery-driven vibrating motor, the Ac-cutron had a price range starting at $200, which stillisolated most of the buying public.The next major stage in electronic watch develop-

ment came in 1969 with Seiko's introduction ofquartz-crystal oscillation and a complementary-MOS(CMOS) frequency divider to provide the timing for astepping motor, which in turn drove the gears of aconventional analog or "hands" display. (it is inter-esting to note that quartz crystals have been used as

_4_ ll time references since the early 1920s, when broad-casting stations employed them to control radiofrequencies; in 1940, quartz-crystal oscillators be-came practical replacements for balance-wheel andpendulum clock movements.) The iransition fromtuning fork to quartz crystal provided wristwatcheswith almost an order of magnitude improvement inaccuracy and a 50 percent reduction in mechanicalparts (a quantity of ICs were fabricated by CEH in

7; 1967 for the first IC quartz watches). Althoughprices for quartz-crystal-controlled, hands-displaywatches originally began at $395, they have beensteadily decreasing, with Bulova's Accuquartz nowretailing from $250, Timex from $125, and Benrus'

7.Xi l_| ;, nl TechniQuartz at a current low of $99.The final stage in the development of the all-elec-

tronic watch involved replacing the stepping motor,gears, and hands with a low-cost solid-state displaydriven by a quartz-crystal and decoder network,which was accomplished in the U.S. in 1972 byHMW Industries' (formerly Hamilton Watch Compa-Faceinew of Microma's all-electronic quartz watch, fea- ny) Pulsar, which sells for $275 in stainless steel to

turing Si-CMOS ICs and the first liquid-crystal display. $2100 in 18-karat gold. Featuring an LED display,

the Pulsar is being accompanied on the market by ahost of liquid-crystal-display (both dynamic scatter-

15] Comparison of the various logic families in terms of power ing and field effect) or LCD watches, among whichdissipation and operating frequency.5 are Gruen's field-effect Teletime ($150), a dynamic-1 0 0 _ _ _ _ S _ -- scattering model by Microma Inc. ($150) and Swiss-

based Waltham ($185), and various soon-to-be-marketed versions by Japan's Seiko and Switzerland'sOmega. Accuracies of the new line of all-electronic

c watches fall within the 1-1 0-s/month range.a @_In short, the quick evolution from all-mechanical

m ~~~~~~~~~~~~~~~~toall-electronic watches has created a new field forZ5 1 ~~~~~~~~~~~~~~thesemiconductor electronics industry with an accu-

CL 1_rate, reliable, and inexpensive product that morer_ ~~~~~~~~~~~~~~thanfavorably competes with Swiss-made mechani-

cal movements (the Swiss firm Ebauches made 68mi 0.1- percent of the world's movements in 1971), With more

accurate quartz crystals and more efficient displays.domination of the $2/3 billion worldwide $50-and-up

0 watch market should not be too difficult!

*13oth Timex and Hamilton claim to have initiated the concept of acontact battery system. although it is reputed by 'old-timers" in thewatch business that Eigin had experimented with such a system as

0.001 0.01 0.1 1 10 100 far back as 1942.

Operating frequency, MHz

28 IREE spectrum APRIL 1973

+VB ( 1.5V)

In~~~~

A

10.2co

One of the three LED electronic watches on the market, 0.1Hamilton's Pulsar is the only watch that features reflow 1 10 102 103 104soldering of leadless inverted packages and a photocell to Frequency, kHzcorrect display brightness under various ambient lighting 6AsceaioftebiculdnbokofCOlgcconditions. Under normal conditions, the user sees either ablank dark-red crystal face (watch off) or a bright-editl cincutera-tionoverdsrteri assembl can eAsilbhe seentge ofrotime readout through the crystal; the reader, however, is itgainoe iceeasml a aiyb enfo

treated here to a photographer's flashlamp view of 'the the power dissipation results of B.5turned-oft LED display, the solid-state photosensor (underthe minutes digits), and various component packagesmounted on the single internal plastic module-all takendirectly through the normally opaque crystal.

into by practically every watch company with aquartz-crystal-controlled movement-with the upshotthat most have opted to remain with the conventional

with shorter duty cycles become necessary, thus re- hands display until many of the problems of digitalquiring a peak currents as high as 1 mA and prohibi- displays have been solved. There seem to be no com-tive demands on the MOS technology. The problem plaints from the handful of companies who have cho-may be solved, however, by using a bipolar pulse sen a digital format, however, a sure indication thatdriver with a capacitor charge and discharge circuit, these problems are indeed solvable.6Miniature motors. Motor systems for hands-driv- To date, light-emitting diodes and nematic liquid

ing electronic watches can be broadly classified under cr~ystals in either the dynamic-scattering or field-ef-two types: stepping-motor systems and phase-locked fect (twisted-nematic) mode have been the two pri-systems. Essentially nonresonant devices, stepping mary display technologies to appear in a marketedmotors are usually of' the rotary, unidirectional type, electronic watch, although there has been consider-rotating 180 degrees each second and coming to a rest able interest in rotatable dipole solutions, which ap-after each rotation. Maximum current consumption is pear to have surmounted the stability problems that8.3 MA at 1.3 volts and 9.5 uA at 1.5 volts. Phase- have plagued past performance.7 Of these displays,locked systems, on the other hand, operate similarly LEDs consume the most amount of power, a problemto the vibrating Longines system described and are that the three major marketers of this type of watchrepresented by movements that include the 1B6ta-21 (HMW Industries', Elgin, and Croton) alleviated by256-Hz mechanically resonating motor, the Timex using such techniques as reduced duty cycles and a3-Hz balance wheel, and Bulova's Accuquartz. wearer-addressable command button. (Reducing active

areas and emission angles are other possible ways.)Digital displays In HMW Industries Pulsar watch, the four-digit dis-The least developed component of the all-electronic play is .3 mm high with a maximum real-time duty

watch, the solid-state digital display has been looked cycle of 25 percent; when addressed, the display gives

Eleccion-The electronic watch 29

hours and minutes for 11/4 seconds, with seconds thenappearing continuously if the command button iskept depressed. One of the unique features of the Pul-sar is a photocell (under the minutes digits) that au-tomatically adjusts LED brightness (depending uponambient lighting) by varying the duty cycle from 3 to99 percent of' maximum; power consumption over thisbrightness range extends from 3 mA minimum to 100mA maximum. Not only has Pulsar reduced somepower drain by multiplexing, but the interconnectionsleading to the seven-segment digits have been cut byalmost a factor of three (from 29 to 11).

Coincidentally, the remaining two LED watchmanufacturers (Elgin and Croton) are supplied theirentire internal module by the same source-Uranus One of the smallest electronic watches available, Bulova'sElectronics. The Uranus LED display differs from the miniature Accutron uses no discrete components (unlike thelarger men's Accutron) and features a redesigned tuningPulsar in that it maintains a constant brightness fork that accommodates a power cell at its center and an ICwhenever the button is depressed; hence the unit is chip attached to the crown side of the movement (adjacentalways on 100 percent maximum duty cycle. Such an to the top of the tuning fork). Measuring only 3/4" in diameter,arrangement does not draw as much current as the this watch was designed to vibrate 480 times a second (asopposed to 360 Hz for the larger version) to adjust for thePulsar at maximum since Elgin's display is only 2.5 change in accuracy resulting from the smaller tuning-forkmm high; however, Pulsar's minimum current con- design.sumption is well below Elgin's constant value.Although multiplexing techniques have aided the

design of LEDs considerably, cost and the inherentthreshold and illumination characteristics of LCDshave prevented watch developers from using this difficult to see at certain angles (and impossible totechnique successfully in driving LCD displays. The see in the dark) but the lifetime of these devices hasprospects of success look encouraging, however (other yet to be demonstrated over extended periods ofusers have successfully multiplexed LCDs); a short time.8 At least one of' these problems has been solvedtime ago the idea of multiplexing LCDs was discounted by the use of' field-effect LCDs, which although theycompletely. When a breakthrough does occur, the ad- have a narrower viewing angle provide a substantiallyvantages will probably derive more from the reduc- higher contrast ratio (40 to 1), hence are extremelytion in leads than from any other factor; at present, the easy to read. In general, field-effect displays requirefour seven-segment digits require 29 connections. one tenth the current and can be operated at lower volt-When dealing with dynamic-scattering LCDs, there ages than dynamic-scattering devices, and can be pur-

are other problems besides excessive numbers of leads chased at prices that are just as competitive (contraryto contend with. Not only is the mirror-like display to reports indicating higher costs). Of the LCD watches

Story of a watchThe story of one company's success in developing Packaging. The packaging systems of the submit-

an all-electronic watch is representative of the types ted units did not allow for ease of assembly or ofof problems that have confronted the whole watch service; also, some systems required two batteries,industry. Prior to their entry in the market of a totally which Gruen considered a serious inconvenience andin-house-designed field-effect LCD watch, Gruen had expense for the consumer.expended a considerable amount of time working Setting. Switch-type time-setting techniques thatwith possible watch-movement suppliers so that were offered presented some difficulties. They usedcomplete LCD watches could be purchased that sa- either magnetic reed switches, which meant the usertisfied Gruen's demands for readability, reliability, had to have a permanent magnet available to set theserviceability, and cost. On the whole, the designs watch, or push pins on the side of the watchcasethat were submitted had many drawbacks, which that would strike contacts on the assembly within thePhilip J. Dunleavey, division manager, described as case. This latter approach makes the casing morethe following: difficult to construct since the additional openings in-

Display. All possible sources used dynamic-scat- crease the problem of waterproofing.tering LCDs, which required significant power and Because of these shortcomings, Gruen decided tohad the added disadvantage of requiring a mirrored design their own watch system, in which the biggestsurface behind the characters of the display that re- single factor toward simplification involved the dis-duced the readability at certain viewing angles and play. To offset the problems inherent in dynamic-under some lighting conditions. scattering LCDs, a field-effect display was chosen,

Power. Due to the power requirement of an LCD requiring only 5 percent of the power needed for a(15 s1W or 1 p1A/15 volts), it became apparent that, dynamic-scattering LCD at one half the voltage. Notwith a continuous display, losses in the upconverter only did this simplify the voltage upconverter and(to provide the 15 volts), and the power required to allow the use of a physically smaller battery withrun the time base, the system could not be guaran- lower capacity, but the system could still function forteed to operate for a 12-month minimum on a single a minimum of one year on a single battery. In addi-battery of the type used in electronic watches. tion, the field-effect display did not pick up objec-

30 IEEE spectruIIl AI'KIL 1973

At the center and bottom ofthis breakdown of Gruen'sLCD Teletime electronic watchis the two-piece primary-boardassembly, which contains thevoltage converter, oscillatorsubassembly (with quartz andflat trimmer capacitor), andslots for both setting switch(right) and battery (top). Thetimekeeping module (left)consists of the LCD (hidden)directly connected to two 1500-transistor lCs performing theoscillator, countdown, and de-coder/driver functions, leavingonly eight coil-spring connec-tions to be made between thetimekeeping module and theprimary-board assembly.

now on the market, Microma and Waltham have a At the present time, the goal of the watch firms is todynamic-scattering display and Gruen has a field-ef- drive selling prices as low as possible while still main-fect display (see box, pp. 30-31). taining an acceptable degree of quality. One way of

doing this is by reducing the cost of relatively expensiveThe present market components such as the quartz crystals, which atBy this writer's count, there are at least a dozen-and- $3-5 each must be hand ground and polished and made

a-half companies with a quartz electronic watch on the to vibrate in the x-y flex mode. Increasing crystal fre-market. Starting at a basic price of $99, most of these quency to 1-2 MHz, however, reduces both quartz sizewatches are of the hands-driven type, although prac- (hence watchcasing size) and cost (to under $1); un-tically all companies have examined the prospects of fortunately, a higher frequency causes an increase inmarketing what many consider the ultimate time- power consumption, which in turn necessitates resort-piece-the all-electronic digital watch. ing to such measures as increasing battery life, rede-

signing oscillator circuits, or changing to silicon-on-sapphire ICs, which have a power consumption fivetimes lower than average but are expensive.

Because of the degree of independence it affordstionable reflections, and hence increased readability. them, some manufacturers can be expected to develop

In terms of packaging, Gruen decided to use a their own crystal-manufacturing capability; however,modular approach to facilitate both production of the most will continue to rely upon such independent sup-system and servicing. As indicated in the photograph pliers as CTS Knights, Motorola, Electronic Researchon this page, the watch consists of two main parts- pliers asrtS KnigsMroLa,Eenesearcthe primary-board assembly and the timekeeping Corp., Northern Engieering Labs, Reeves-Hoffman,module-which are assembled in the watch module and Statek Corp.carrier and are easily removed by three screws. The Obviously, the trend toward higher-frequency quartztimekeeping module itself contains the LCD and an oscillators will require more complex frequency di-IC circuit package directly connected to the display.Since this takes care of most of the interconnec- viders, a problem that Intersil Corp., one of the largesttions, there remain only eight additional connections suppliers of CMOS watch circuits (to Seiko, Bulova,to be made between the primary board and time- and Omega, among others), is solving by fabricating akeeping module. Concerning the ICs themselves (two 20-stage divider chip; charge-coupling techniques alsoare used), one contains a 32-kHz oscillator andcountdown circuit that operates at the battery volt- provide a solution to the high-frequency problem. Atage of 1.5 volts, and the other (driven by the count- present, there are several semiconductor manufac-down) performs the decoder/driver function for the turers besides Intersil that offer integrated devices,display. The primary-board assembly carries the bal- with RCA supplying HMW Industries (formerly Hamil-ance of the watch components, which consist of the ton Watch Co.), and Motorola (Girard Perregaux, Ben-voltage converter, the oscillator subassembly, the rus), Solid State Scientific (Gruen, General Time),switch, and the battery.

Considering the results that this writer has seen in Texas Instruments (Longines), Hughes (Timex), Microstrictly consumer terms-accuracy, readability, and Power Systems (whose high-density CMOS technologyattractiveness-there is no doubt that Gruen's presi- compares with PMOS densities), and others competingdent Mitchell Teeman has a marketable item. for the rest of the market, which has already been pre-

_____________________ _____________ dicted at 1-10 million quartz-crystal watches by 1973.

Eleccion--The electronic watch 31

A glance at both the back (above) and front (see cover) ofPulsar's neat-looking plastic carrier reveals why today'swatch industry is proving a boon to electjonics manufactur-ers. With Pulsar's demand for component units almost twicewhat primary sources are capable of supplying, second-source suppliers are now being given a crack at the busi-ness. The above shot shows a quartz crystal made by eitherReeves Hoffman or Motorola, a tubular multiturn trimmer In addition to the extreme accuracy of an electronic watch,capacitor by Johanson, and two wells to accommodate Ray- In Titio n Electreme accuracy I stop watch ,u-Vac silver-oxide batteries; on the cover, one can see the a Time andElctroni split a stopwat readousquare 1300-transistor LSI circuit by RCA, a ceramic sub- has a unique gas-discharge display with a six-digit readoutstrate by TRW, 11 LID drive transistors by Amperex, a measuring 1/100 of a second in a 'split-time" mode thatClairex photocell, and a GaAs solid-state display by Mon- records both total and periodic elapsed time.santo. In addition, Hamlin reed relays are mounted in thePulsar to adjust the timing when magnetically activated by atimeset bar enclosed in the watchband.

ing, it was reported that General Electric and SolidState Scientific were entering the market with an LCD

If this prediction proves true, it may turn out to be a CMOS watch, that Ebauches S.A. had bought Swisswindfall for many others in the electronics business. Longines and intended to produce its own LCD elec-On the component level, such firms as Johanson Manu- tronic watch, that a major patent-infringement suit byfacturing (precision trimmer capacitors), Hamlin (reed one LED watch manufacturer against another was inswitches), Amperex (discrete transistors), Monsanto litigation, and that one electronic watchmaker was(LEDs), and Clairex (photocells) have begun to receive dropping out of the business.substantial orders from the watch people. Some com-panies, such as Motorola (ICs, quartz crystals, andstepping motors), are even supplying more than one es-sential item. REFERENC ESPerhapsthe greatest profits will be made by those 1. Forrer, M. P.. "Survey of circuitry for wristwatches," Proc. IEEE,Perhaps th raetpoiswl emd ytoe vol. 60, pp. 1047i 10.54. Sept. 1972.companies who manufacture complete units to be 2. Vittoz, E., et al., "Logic circuit for wrist watch," presented at theplaced within brand-name watchcasings. Such firms EUROCON Conf., L.ausanne, Switzerland, Oct. 197r1.

'3. Vittoz, E., et al., "Silicon-gate CMOS frequency divider for theare spared the marketing costs that are incurred by electronic wrist watch," IEEE J. Solid-State Circuits (Special issuethose who attempt to produce a completely new brand on micropower electronics). vol. SC-7. pp. 100-104, Apr. 1972.

4. Wanlass, F. M., and Sah, c. T., "Nanowatt logic using field-effectwatch (such as Microma Inc., recently purchased by metal oxide semiconductor triodes," in 1963 ISSfC' Digest tech. Pa-Intel Corp.), and yet can rely on set-volume orders pers. pp.3:2-33.

in advane.Compnies preently spplying 5. Burgess, R. R., and D)aniels, R. G., -CM05 unites with siliconplaced in advance. Companies presently supplying gate to yield micropower technology,"E'lectronics, vol. 44. pp. i8-4:,complete watch packages include Optel Corp. (Wal- Aug. 30, 1971.tham, Omega, Jules Jurgensen), CEH (Beta 21 move- 6. Juirgen, R. K., et al., "Information displays: innovation is therule,"' IEEE Spectrum, vol. 9, pp. 18 -32, Nov. 1972.ment for Bulova, Longines, Piaget, and Omega), and 7. Taylor, G. W., and Letkowitz, I., "Improved electronic watches,"Uranus Electronics (Elgin, Croton), all of whom are Proc. IEEE (Letters), vol. 61, pp. 487-489, Apr. 197:3.

thecmponnt peple or pats(.g., 8. McDermott, .J., "How good are the new watches'? Electronicdependent upon the component people for parts (e.g., claims split industry," Electron. Design, vol. 20, pp. 30-32, Sept. 28,TI ships to Ebauches, Hughes supplies Uranus). 1972.Although it can be said with confidence that the

overall potential of the electronic watch industry looksgood, there is nothing predictable about what will Reprints of this article (No. X73-042) are available atoccur within the industry itself. It's anybody's guess $1.50 for the first copy and $0.50 for each additional copy.why one company loses over $1 million while another Please send remittance and request, stating article num-

ber, to IEEE, 345 E. 47 St., New York, N. Y. 10017, Att:can't find enough suppliers to fill back orders-and the SPSU. (Reprints are available up to 12 months from date ofprofit picture is not inviolate. At the time of this writ- publication.)

32 Eleccion-rhe electronic watch