1 / 55

Introduction to Quartz Watches

Introduction to Quartz Watches. Presentation. Introduction to Quartz Watches The History Ohm’s Law The Principle Components and their Function Analyzing – Trouble-Shooting Modern Quartz Watches Use of Testing Equipment Servicing Modern Quartz Watches. Components of a Quartz Watch.

blackshire
Télécharger la présentation

Introduction to Quartz Watches

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Introductionto QuartzWatches

  2. Presentation • Introduction to Quartz Watches • The History • Ohm’s Law • The Principle Components and their Function • Analyzing – Trouble-Shooting Modern Quartz Watches • Use of Testing Equipment • Servicing Modern Quartz Watches

  3. Components of a Quartz Watch Energy accumulator Accumulator, Battery, Capacitor Gear train, Frequency divider circuit Counting, transmission Electro-mechanical Transformer, Stepping motor Distribution Regulation Quartz Dial and hands, Aperture discs, Diodes, Liquid crystals Display

  4. Analog and Digital Quartz Watches • Principle design of quartz watches

  5. Identification of Components • Battery • Insulator • Positive contact • Negative contact • Printed circuit • Integrated circuit • Quartz • Trimmer 9. Coil 10. Coil protector 11. Stator 12. Rotor 13-15. Train wheel 16. Train wheel bridge 17. Setting stem

  6. Historical Background • “Pierre Curie, Marius Lavet, the transistor and the landing on the moon” • Electric clocks • Piezo-electric effect • First quartz clocks • The Lavet motor • The transistor • Introduction of electric and electronic watches • Development of the Integrated Circuit • Landing on the moon • First portable quartz watches

  7. Oscillation - Vibration Frequency - Isochronism

  8. Frequencies The higher the frequency of the oscillator the more accurate the timekeeper

  9. Ohm’s Law

  10. The Battery • The case – positive pole • The cathode – positive electrode • The pressure ring • The separator • The gasket • The absorbent material – electrolyte • The anode – negative electrode • The cover – negative pole

  11. Introduction to Electro-chemical Processes Volta’s battery Electro-chemical systems used in watch making

  12. Electro-chemical Tension Table 1,56 V

  13. Types of Batteries,Storage and Handling • Four types commonly used in watches: • Silver oxide (low drain) 1,55 V • Silver oxide (high drain) 1,55 V • Lithium 2 V (Li/CuS) • Lithium 3 V (Li/MnO2) • Storage: • Store at 20 centigrade and max. 50% humidity • Batteries 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 months • Manufacturer’s use often a production code – do not use batteries produced more than 6 to 12 ago • Batteries may leak: check gasket seat before installing into watch • Handling: • Handle batteries with insulated tweezers to avoid short circuits. Do not touch with fingers.

  14. Sample Battery Chart

  15. Theoretical Life-time and Testing of Batteries • Test batteries with a voltmeter (very high internal resistance) preferably installed on the movement • When applying test resistor follow equipment manufacturer’s recommendations • Note: There is no efficient way to determine a battery’s remaining capacity. Changing a battery is less costly than a come-back.

  16. The Quartz • The 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 specifications • They have three axes, which are set perpendicular to each other: • The piezo-electric effect was discovered in 1880 by the brothers Curie • if a quartz crystal is mechanically deformed an electrical charge results at given points • if an electrical charge is applied at certain points the quartz crystal is deformed mechanically.

  17. The Quartz as an Oscillator • Like any other oscillator (pendulum, balance wheel) quartz oscillators need to be activated • Quartz has electrical properties which resemble a traditional electrical oscillator consistent of a capacitor and a coil • Once the quartz is oscillating it maintains a very precise and stable oscillation • The quartz has a “natural” frequency and if the external oscillator’s frequency is the same the quartz vibrates “in resonance”

  18. The 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 pattern X cuts CD/DTcuts AT cuts

  19. The temperature/frequency curve

  20. Mainly two “cuts” are being used for application in watchmaking: Flexion mode in the shape of bars or tuning forks Quartzes used in Watchmaking • Shearing mode • In the shape of lenses

  21. The Tuning Fork Quartz • Today the most commonly used quartz resonator in watchmaking • Very stable frequency due to pre-aging quartzes during manufacturing process • Temperature does not vary too much in wrist watches • Good shock resistance (mounting crystal at the base of the tuning fork) • Good mastery of production process

  22. Determination 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

  23. 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 frequency TheCorrection of the Frequency • Today more often “Inhibition” systems are being used to correct the output signal of the divider chain (inside the integrated circuit)

  24. The 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 quartz • divide the frequency • correct the rate of the watch (inhibition system) • transmit impulses to the motor • end of life indicator (battery) • controlled motor drive (servo control circuit)

  25. The 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

  26. Inhibition System • The accuracy of the quartz watch depends largely on the frequency of the quartz • The frequency of quartzes vary due to manufacturing tolerances • These variations can be corrected outside the IC by either using a trimmer or fixed capacitor • Another system is using a special IC which corrects the frequency inside the divider chain • Watches with inhibition system will always indicate a large gain when the rate is tested using acoustical and capacitive pick-up modes • This 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 chain • These type of watches must be tested by using the motor (inductive) pick-up and preset the integration time (measurement interval) to 60 seconds

  27. The IC of a Digital Quartz Watch • This type of IC’s may contain additional functions such as: • Multiplex circuit • Segment driver circuit for LCD (64Hz) • Alarm • Chronograph

  28. Introduction 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.

  29. The Motor • Early on watch manufacturers used various designs of electro-mechanical transformers in quartz wrist watches • Balance wheel • Tuning fork • Micro motor (compact)

  30. The 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:

  31. Evolution of the Lavet Motor • Early design with open stator • Current design with closed stator • Rotor “floats” inside stator opening

  32. TheFunction of the Lavet Motor • The motor impulse • The rotor at rest • The positive motor impulse

  33. TheFunction of the Lavet Motor • The rotor at rest (after 180 degrees) • The negative motor impulse • The rotor has completed one revolution (two impulses needed)

  34. The Display • Train wheel and display of an analog quartz watch

  35. The Electronic Display • Digital quartz watches use a seven digit display matrix for numbers • In 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.

  36. The Liquid Crystal Display • Liquid crystals are organic substances that have different physical properties depending on the temperature • Liquid crystals can vary by their molecular structure (smectic, nematic, cholesteric or dichroic). Today mainly nematic substances are used for watches

  37. The Design of the LCD 2 1 3 5 4 • Design principle 7 6 9 8 9 • Side view 8 7 5 1 2 11 3 4 10 1. Upper glass 2. Upper polarization filter 3. Individual electrodes 4. Common electrode 5. Frame 6. Liquid crystals 7. Lower glass 8. Lower polarization filter 9. Reflector 10. Common electrode contact 11. Fill hole / Solder point

  38. Function of a LCD 3 4 5 1 2 7 8 9 6 1. Reflector 2. Polarization filters 3. Liquid crystal molecules in normal state 4. Incoming light 5. No contrast 6. Electrical field applied (electrodes not shown) 7. Liquid crystal molecules arranged 8. Incoming light 9. Contrast

  39. Diagnosis of Quartz Analog Watches 3 4 5 2 1 1. 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 battery 4. Checking the motor impulse 5. Checking the coil resistance 6. Checking the insulation of circuit and coil 7. Checking the consumption 8. Checking the lower working voltage

  40. Diagnosis ETA 955.112

  41. Checking the Rate(Acoustic Pick-up) Checking the rate with case closed

  42. Checking the Rate(Inductive Pick-up)

  43. Testing the Voltage(Battery Installed)

  44. Checking the Motor Impulse(Battery Installed)

  45. Coil Resistance(Battery Removed)

  46. Checking the Average Consumption(Battery removed)

  47. Checking the Base Consumption(Battery removed)

  48. Interaction between a Coil and a Permanent Magnet When moving a permanent magnet in/out of a coil a current will be “induced”

  49. Controlled Motor Drive

  50. Testing the Controlled Motor Drive

More Related