Presentation on theme: "Components of a Quartz Watch"— Presentation transcript:
1Components of a Quartz Watch Energy accumulatorAccumulator, Battery, CapacitorGear train, Frequency divider circuitCounting, transmissionElectro-mechanical Transformer, Stepping motorDistributionRegulationQuartzDial and hands, Aperture discs, Diodes, Liquid crystalsDisplay
2Analog and Digital Quartz Watches Principle design of quartz watches
4Oscillation - Vibration Frequency - Isochronism Dividing time in equal incrementsRecurring event at defined intervalsVibrationOscillationIntroduce “Hertz” as unit of measureAmplitudeIsochrononismDiscovery of Isochrononism Galileo (1583)Huygens (1656)
5FrequenciesRelationship of Precision – Frequency – Quality factorThe higher the frequency of the oscillator the more precise the timekeeper (if the frequency doubles the accuracy increases four-fold)The higher the frequency of the oscillator the more accurate the timekeeper
7The Battery The case – positive pole The cathode – positive electrode The pressure ringThe separatorThe gasketThe absorbent material – electrolyteThe anode – negative electrodeThe cover – negative pole
8Introduction to Electro-chemical Processes Volta’s batteryElectro-chemical systems used in watch making
9Types of Batteries, Storage and Handling Four types commonly used in watches:Silver oxide (low drain) 1,55 VSilver oxide (high drain) 1,55 VLithium 2 V (Li/CuS)Lithium 3 V (Li/MnO2)Storage:Store at 20 centigrade or 68 Fahrenheit and max. 50% humidityBatteries have a limited shelf life (due to self discharge, which is the result of a change in the internal resistance over time) – avoid storing batteries longer then 12 monthsManufacturer’s use often a production code – do not use batteries produced more than 6 to 12 agoBatteries may leak: check gasket seat before installing into watchHandling:Handle batteries with insulated tweezers to avoid short circuits. Do not touch with fingers.
11Theoretical Life-time and Testing of Batteries Test batteries with a voltmeter (very high internal resistance) preferably installed on the movementWhen applying test resistor follow equipment manufacturer’s recommendationsNote: There is no efficient way to determine a battery’s remaining capacity. Changing a battery is less costly than a come-back.
12The QuartzThe quartz (rock crystal) can be found in alpine regions and has the chemical formula SiO2 (silicon dioxide)They are “grown” synthetically in autoclaves and cut to the proper specificationsThey have three axes, which are set perpendicular to each other:The piezo-electric effect was discovered in 1880 by the brothers Curieis a quartz crystal mechanically deformed an electrical charge results at given pointsif an electrical charge is applied at certain points the quartz crystal is deformed mechanically.
13The Quartz as an Oscillator Like any other oscillator (pendulum, balance wheel) quartz oscillators need to be activatedQuartz has electrical properties which resemble a traditional electrical oscillator consistent of a capacitor and a coilOnce the quartz is oscillating it maintains a very precise and stable oscillationThe quartz has a “natural” frequency and if the external oscillator’s frequency is the same the quartz vibrates “in resonance”
14The Orientation of the Quartz Cuts At which angle the quartz resonator is cut from the raw material determines two critical factors:The frequency of the quartz resonator and their oscillation patternX cutsCD/DT cutsAT cuts
16Quartzes used in Watchmaking Mainly two “cuts” are being used for application in watchmaking:Flexion modein the shape of bars or tuning forksShearing modeIn the shape of lenses
17The Tuning Fork QuartzToday the most commonly used quartz resonator in watchmakingVery stable frequency due to pre-aging quartzes during manufacturing processTemperature does not vary too much in wrist watchesGood shock resistance (mounting crystal at the base of the tuning fork)Good mastery of production process
18Determination of the Frequency and the Dividing Chain The frequencies are determined by using an exponential factor of the number 2 since binary circuits are used to divide the frequency
19The Correction of the Frequency During the manufacture of quartz resonators variations occur and not all will oscillate at 32,768 Hz (32 kHz)The traditional method is to use a trimmer (an adjustable capacitor) or a fixed capacitor to make corrections to the frequencyToday more often “Inhibition” systems are being used to correct the output signal of the divider chain (inside the integrated circuit)
20The Function of the Integrated Circuit The integrated circuit is the “brain” of the quartz watch. It has many different functions:maintain the oscillation of the quartzdivide the frequencycorrect the rate of the watch (inhibition system)transmit impulses to the motorend of life indicator (battery)controlled motor drive (servo control circuit)
21The Integrated Circuit Integrated circuits in watchmaking are usually manufactured using C-MOS technology (complimentary metal oxide semiconductor)They are manufactured on silicon wafers in a step by step photo-lithographical process which requires extreme precision
22Inhibition SystemThe accuracy of the quartz watch depends largely on the frequency of the quartzThe frequency of quartzes vary due to manufacturing tolerancesThese variations can be corrected outside the IC by either using a trimmer or fixed capacitorAnother system is using a special IC which corrects the frequency inside the divider chainWatches with inhibition system will always indicate a large gain when the rate is tested using acoustical and capacitive pick-up modesThis gain is corrected every so often (commonly every 60 seconds) by eliminating a set number of impulses at the 16 kHz level of the divider chainThese type of watches must be tested by using the motor (inductive) pick-up and preset the integration time (measurement interval) to 60 seconds
23The IC of a Digital Quartz Watch This type of IC’s may contain additional functions such as:Multiplex circuitSegment driver circuit for LCD (64Hz)AlarmChronograph
24Introduction to Electro-magnetism When an electric current flows through a coil the coil becomes a magnet. By adding a soft-iron core this effect can be “directed” and increased.
25The MotorEarly on watch manufacturers used various designs of electro-mechanical transformers in quartz wrist watchesBalance wheelTuning forkMicro motor (compact)
26The Lavet Motor Today most commonly used in quartz analog watches Introduced during the second part of the 1970’s due to the availability of small and very powerful magnets (samarium kobalt alloy)Principle components:
27Evolution of the Lavet Motor Early design with open statorCurrent design with closed statorRotor “floats” inside stator opening
28The Function of the Lavet Motor The motor impulseThe rotor at restThe positive motor impulse
29The Function of the Lavet Motor The rotor at rest (after 180 degrees)The negative motor impulseThe rotor has completed one revolution (two impulses needed)
30The DisplayTrain wheel and display of an analog quartz watch
31The Electronic Display Digital quartz watches use a seven digit display matrix for numbersIn LED quartz watches each segment is made out of several light emitting diodes (gallium arsenide or gallium phosphate). These displays required a lot of energy and two hands to read the time.
32The Liquid Crystal Display Liquid crystals are organic substances that have different physical properties depending on the temperatureLiquid crystals can vary by their molecular structure (smectic, nematic, cholesteric or dichroic). Today mainly nematic substances are used for watches
33The Design of the LCD Design principle Side view 2 1 3 5 4 6 7 8 9 9 8 1134101. Upper glass2. Upper polarization filter3. Individual electrodes4. Common electrode5. Frame6. Liquid crystals7. Lower glass8. Lower polarization filter9. Reflector10. Common electrode contact11. Fill hole / Solder point
34Function of a LCD 1 3 4 5 2 7 8 9 6 1. Reflector 2. Polarization filters3. Liquid crystal molecules in normal state4. Incoming light5. No contrast6. Electrical field applied (electrodes not shown)7. Liquid crystal molecules arranged8. Incoming light9. Contrast
35Diagnosis of Quartz Analog Watches 345211. Checking the rate (quartz frequency)Acoustic or capacitive pick-up (Inhibition system)2. Checking the rate (magnetic field of motor during impulse)Inductive pick-up (Inhibition system)3. Testing the battery4. Checking the motor impulse5. Checking the coil resistance6. Checking the insulation of circuit and coil7. Checking the consumption8. Checking the lower working voltage
46End of Life Indication (Battery removed) Certain movements with seconds hand have an indicator to signal the need for a battery replacementThis function is activated when the battery voltage drops below 1,4 VWhen replacing the battery the movement may continue to operate in the EOL mode for up to one minutePulling out and pushing back in the stem will reset the EOL function
48Lower Working Voltage (Battery Removed – Fast Action Mode)
49The Thermo-compensation System (ETA 255.511/561) In the mid-1980’s the first quartz watches with thermo-compensation systems were introduced in the quest for high-precision watches (deviation of +/- 10sec/year) as alternative to utilizing mega-hertz quartzes.The design is based on using a twin-quartz solution where the temperature variance of a standard 32 kHz quartz is electronically stabilized by comparing its accuracy to a 262 kHz quartz and (with the help of a sophisticated electronic circuit) introduce a correction every eight minutes via an inhibition system.To make corrections to the regulation a specified procedure needs to be followed and a timing machine with a 480 seconds integration time is required.
50Thermo-compensation circuit and Temperature-Frequency Curve Rate in sec/dayThermo-compensated quartzRegular quartzTemperature-Frequency Coefficients