Technology Developed for the World's First Quartz Watch

Technology Developed for the World's First Quartz Watch

Seiko Epson (then Suwa Seikosha but referred to below as Epson) succeeded in developing the world's first commercial quartz watch. That was more than half a century ago, in 1969. Today, quartz watches account for about 96%* of all the watches manufactured globally. The technology developed for the first quartz watch continued to evolve and eventually laid the foundations for Epson's crystal device and semiconductor businesses. In addition to watches, this technology is found in application as varied as computers, digitally controlled home appliances, mobile phones, automobiles, and industrial equipment.
Read on to learn more about the technology inside the world's first quartz watch.

* The 96% figure was calculated based on a 2017 estimate of watch production quantity by the Japan Watch Association.

What are quartz watches?

Quartz crystals emit electric signals of a stable frequency under an applied voltage. Timepieces that capitalize on this feature to keep accurate time are called quartz watches or clocks.

Quartz watches first appeared in the late 1960s. They largely replaced the hand-wound and self-winding mechanical watches of the day that used a balance spring as a pendulum. Today they are by far the most popular type of watch.

Watches are not the only things that rely on quartz crystals. Quartz crystals are used widely to accurately count time or to capture changes in speed and movement, and are therefore found in everything from home appliances, PCs, and smartphones to cars and other industrial products.

Artificial crystal

Quartz watch construction

The following is a simplified explanation of the operating mechanisms in a quartz watch.
First, the crystal unit housed in the oscillator 2. oscillates at a frequency of 32,768 Hz on the electricity sent from 1. the battery. This frequency is divided by a divider circuit 3. so that it is brought down to one signal per second. Furthermore, this signal is converted to mechanical rotary motion by step motor converter 4., the indicating mechanism 5. moves the hand by one index per second, and this motion is then transmitted to the minute and hour hands.

Quartz watch construction
Quartz watch construction

Quartz clocks became popular from almost the moment they first appeared, but they were less than ideal. That was because the crystals needed to be kept at a constant temperature to maintain stable frequency output. For this reason, In 1959 early quartz clocks had a thermostatic function that made them very large(such as a locker size:1.3m x 2.1m) and increased their power consumption.

Epson thus began research and development work on technology that would reduce the size and energy consumption of quartz timepieces without sacrificing accuracy. We replaced the bulky vacuum tubes with transistors, got rid of the thermostatic chamber, and developed a temperature compensating device using a variable capacitor to realize a much smaller quartz clock. After the company was tasked with developing an official timekeeping system for the 1964 Tokyo Olympics, the speed of development accelerated. This work culminated, in 1963, with the development of a portable quartz clock, the Seiko Crystal Chronometer QC-951. Development speed picked up still further, and three years later, in 1966, Epson announced a pocket-sized quartz watch. Then, in 1969, we launched the world's first quartz wristwatch, the Seiko Quartz Astron 35SQ.

Quartz clock, Chubu Broadcast Station
(Locker size 1.3m x 2.1m)
Crystal chronometer
(Portable size)
Quartz Astron
(wrist watch size)

Three key miniaturization technologies

It was precision processing and electronics technologies that enabled Epson to reduce the size of quartz timepieces.
There were three technologies that were key.

Three key miniaturization technologies

1. Tuning fork quartz oscillator (world first)

Quartz crystals emit an oscillation frequency when a voltage is applied. This characteristic led to the development of devices called quartz oscillator units. Conventional quartz oscillator units were tubular, but we replaced these with a smaller tuning fork type that saved space and oscillated at a stable frequency. However, processing synthetic crystals into a tuning fork shape was a challenge because in volume production their fragility made them susceptible to cracking and breaking during cutting and polishing. This problem was solved with the invention of a lithographic manufacturing process in which hydrofluoric acid is used to etch away the periphery of the crystals. To provide impact resistance, we devised a method of suspending the oscillator inside a vacuum capsule, thus enabling volume production. Later, the power used by electronic circuits was progressively reduced, and the oscillation frequency rose from 8,192 Hz to 32,768 Hz. Today, this frequency is the time standard for most devices that use quartz oscillator.

A tuning fork crystal oscillator
Tuning fork crystal oscillator used in the Quartz Astron
Later crystal oscillator that oscillates at 32,768 Hz

2. CMOS IC for quartz wristwatches

CMOS IC for quartz wristwatches

The electrical signal emitted by a quartz oscillator unit must be divided and the drive waveform shaped before it can be converted into mechanical rotational motion. Epson developed a watch IC that did just that. This hybrid IC was made possible by some outstanding craftsmen & women who manually soldered 76 transistors and 84 resistors 29 capacitors total 189 elements onto a ceramic substrate.

We continued development believing that a stable supply of C-MOS ICs would be essential for expanding and stabilizing our wristwatch business. So, we sounded out IC manufacturers. However, the answer was always that they couldn't help because there was no demand for ultra-low power devices. That being the case, we decided to pursue C-MOS IC development and manufacturing by ourselves. Ultimately, we succeeded in developing and volume-producing C-MOS ICs for ultra-low power watches, in 1971.

These C-MOS IC for watches ran on one-third to one-quarter of the power used by ordinary ICs at that time, so, over time, their use expanded beyond watches and into consumer electronics, such as home appliances, computers, and cell phones, as well as into automobiles and other devices that support a wide range of industries.

Hybrid IC (1969)
CMOS IC for quartz wristwatches (1971)

3. Ultra-compact open-type step motor (world first)

Motors are used in timepieces to convert electric signals that are precisely regulated in a once-per-second rhythm by an IC into mechanical motion that is transmitted through gears to the second, minute, and hour hands that we see on the dial. However, conventional cylindrical motors are large and difficult to mount in a wristwatch. Therefore, we took on the challenge of developing a new open-type motor, one whose parts would be separated and arranged in a dispersed layout. What Epson developed was an ultra-compact open-tape step motor consisting of a separate coil, stator, and rotor.
In addition to the mechanism changes, the new motor had an ultra-fine wire coil, a high magnetic force rotor magnet, and an optimized control method for driving the motor. These also resulted in lower power consumption.

Ultra-compact open-type step motor
Ultra-compact open-type step motor

Quartz revolutionized horology

Seiko Quartz Astron 35SQ

The Seiko Quartz Astron 35SQ drew a great deal of attention around the world. That was because whereas even the most accurate mechanical wristwatches lost or gained about 20 seconds a day, a quartz wristwatch, with a daily rate of ±0.2 seconds (and monthly rate of ±5 seconds) was 100 times more accurate. The response was such that an article about the Quartz Astron 35SQ even appeared in the New York Times. There was also a media story that called the product "a revolution" in the history of horology.

In addition to transformative technology, the Seiko Quartz Astron 35SQ made an impact and earned stellar reviews for implementing innovative ideas and for design aesthetics, including a battery cover that made battery replacement easy and an elegant appearance thanks to a round movement.

Contributing to society by publicly disclosing the technology

Epson published patents detailing its quartz watch technology. This resulted in the global spread of analog quartz watches. Currently, quartz watches account for about 96% of all watches manufactured around the world. In other words, Epson's technology gave people in every corner of the Earth access to accurate times.

Epson's quartz watch has been the subject of numerous awards, and Epson has earned recognition for both the technology and the publication of patents that were opened to the public. And today, even more than half a century since its advent, the technology continues to be revered as a beacon of Japanese technology.

  • 2002 : Corporate Innovation Recognition Award, the American Institute of Electrical and Electronics Engineers (IEEE)
  • 2004 : Milestone Award, the IEEE
  • 2014 : Mechanical Engineering Heritage registration, Japan Society of Mechanical Engineers
  • 2018 : Essential Historical Materials for Science and Technology, National Museum of Nature and Science

Epson went on to further advance key technologies to create products that are even smaller and draw less power yet deliver exceptional performance. Epson's crystal devices and semiconductor businesses both grew out of quartz watch development. Compactness and power saving were the watchwords that guided development work on the quartz watch. These words express ideals to which we still ascribe to this day and which are embodied by Epson's efficient, compact, and precision technologies.

* The statement that quartz watches account for 96% of all watches manufactured is based on a 2017 estimate of watch production quantity by the Japan Watch Association.