The Technology of Wristwatches
When buying a wristwatch, hardly anyone ever thinks about what the watch is made of and how it actually works. As the production technology of both men’s and women’s watches is similar, we can broadly distinguish between mechanical and electronic watches.
If the spring mechanism was mainly in use in earlier times, as technology evolved, quartz vibrations and electromagnetic pulses replaced the strict mechanical measurement of time.
The Mechanical Wristwatch
The heart of the mechanical watch is a type of crank called ‘handwheel’ that changes the equilibrium position of the spiral spring. In essence, the handwheel is a pendulum with harmonic motion, but the pendulum has been the cornerstone of time measurement for at least 500 years. One motion of a pendulum always takes the same amount of time, regardless of whether the pendulum makes a longer or a shorter swing. The motion of the handwheel is exactly the same thing – even if the spring thrust is running out and the motion angle of the handwheel is smaller.
The handwheel’s motion is monitored using an anchor and a gearwheel. Passing the centreline, the handwheel pushes the anchor, and its cavity moves the gearwheel by one tooth. Turning back, the handwheel pushes the anchor in the opposite direction and a cavity of the anchor makes the gearwheel move again.
The gearwheel is connected to the gear mechanism via the spring, the pressure of which only moves the wheel in one direction. The pressure cannot be released at once and uncontrollably since the gear mechanism allows the gearwheel to move only in precisely timed steps.
The gearwheels of the mechanism are connected to the hands, i.e., when a gearwheel moves, the hands on the dial also move. This way, the gear mechanism transfers the time measured by the handwheel onto the hands, and, at the same time, applies the tension spring force in order to keep the handwheel in motion. The mechanism will work until the spring runs out.
Most modern watches have been designed to function for 40 hours with a single winding, which means they must be winded every single day, but there are also watches that function for several days, whereas some models use a 192-hour spring and can be winded once a week.
Automatic watches are wristwatches with the mechanical gear mechanism, in which the spring is winded using the body movements of the watch owner. The self-winding wristwatch uses an eccentric counterweight as a rotor, which begins to rotate by inertia when the watch owner is moving, winding the spring via a gearwheel. The self-winding wristwatch can also be winded manually to keep the watch running even if it is not worn or when the wrist movements of the watch owner are not sufficient to wind the spring.
The quartz watch is based on harmonic vibrations. The piezoelectric effect of a quartz crystal is diverted through a microchip and via a stepper motor to the hands or, in the case of digital watches, to an LCD dial. Since the quartz pulley is driven only by electrical pulses and no force exerted by a strong spring, the wheels of a quartz watch can be made of plastic. The required basic electronic components are cheap. Using these, one can make a magnificent timepiece, which, at the same time, will remain an inimitable piece of art on the wrist of its owner.
Although hand and numeric wristwatches, desk clocks, alarm clocks, and wall clocks are mostly quartz watches, they are mostly called electromechanical (wrist)watches with hands.
The margin error of quartz watches is typically less than one second a day. The fundamental frequency of the quartz resonator is primarily influenced by the ambient temperature, in the case of a wristwatch, also by the duration of wearing on the wrist.
Today, quartz mechanisms are produced very cheaply and in very large quantities; typically, the cheapest of watches have a quartz mechanism. Electronic watches need electricity as a power source, usually available in the form of interchangeable batteries.
Two Mechanisms Put Together
There are two major issues with mechanical watches: the resistance that occurs due to the friction of the gear mechanism and the effect of the position of the watch (hence the position of the handwheel) on the oscillation period.
Over the past 300 years, several solutions, effective to some extent, have been found to both problems. At present, the most popular one is the coaxial gear mechanism and the tourbillon mechanism; the former reduces resistance, and the latter prevents issues related to the position.
The problem behind the resistance of the gear mechanism is as old as a clock with a handwheel. In fact, this is an issue that applies to physics as a whole: the physical phenomenon (in this case, the oscillation of the handwheel) is very difficult to measure without interfering with the phenomenon. Any contact with the handwheel results in the gear mechanism slowing down and weakening the oscillation.
An old Swiss anchor was a major step forward as compared to an earlier solution, in which the gear mechanism was always in contact with the handwheel. The anchor and the handwheel are partly in contact with each other, but friction still occurs.
The coaxial gear mechanism is a new and slick solution that should replace the anchor and eliminate frictional energy losses. English clocksmith George Daniels developed the theory and also made the first prototype.
The solution is based on an old observation that friction resistance can be released if the anchor gives the handwheel an impulse in just one direction. It has been used for higher precision in clocks or chronometers. Chronometers, however, are sensitive to shock and, therefore, cannot be used as watches. Daniels’ solution was to place two handwheels symmetrically on top of each other – that is, there was essentially one handwheel, two gearwheels, and four anchor cavities on two levels. When the precision of production was increased, the mechanism of a suitable size would operate smoothly also in wristwatches.
The French word ‘tourbillon’, or ‘whirlwind’, sparks interest in horology enthusiasts because this is a particularly valued rotating gear mechanism.
As mentioned above, the position of the watch and, therefore, the direction of gravity changing continuously is not favorable for the steady movement of the handwheel. In 1795, a Swissman Abraham-Louis Breguet discovered that if the entire mechanism of the handwheel and gear was in constant rotation, it would not be affected by gravity. Other elements of the mechanism would not move.
Theoretically, the tourbillon-powered clock is not complicated, but its production proved to be challenging. Due to the increased precision of standard clock mechanisms, the tourbillon is no longer more precise than other clock mechanism types, but collectors and passionate enthusiasts appreciate its uniqueness.
Since the gear usually performs one rotation a minute, it can be used as a second hand. All tourbillon watches have an opening in the place of the handwheel on the dial to enjoy this special feature to the maximum.
The same style has been applied to watches with the non-rotating mechanism, as it is also a good idea to watch the swaying of the standard handwheel. The back of the watch case has long been made transparent to watch the moving parts.
An emerging interest has lead to the development of the new versions of the tourbillon, such as tourbillons with two or three axes. In these, the handwheel and the gear rotate not only in relation to one, but two and even three spatial axes. This is a gorgeous and, indeed, a spectacular sight.
Solar-powered watches have the same system as the watches described above, except that they receive energy from light. The photocell on the front panel of the watch converts light into electrical energy to charge either a battery or a capacitor. The clock mechanism pulls out energy, and if such a watch is regularly exposed to a strong light source (e.g., sunlight), batteries do not need replacement. Some models even get enough energy during a few minutes in the sunlight to function for weeks.
Men`s Watch as a piece of art
Since most people tend to use a mobile phone or a computer screen to read the time, a wristwatch has lost its relevance and become an accessory and a statement. A person can have several watches – to match different clothes. Considering this, the mechanical watch got a new face: a bunch of springs and gearwheels, let alone a transparent case, which can be compared to a wearable piece art, often a man’s only accessory. Interestingly, the manufacturer does not focus on selling a timepiece, but rather on advertising a watch as a must-have item and a piece of the industry’s history to rest on a successful man’s wrist.
The technical quality and the mechanical versatility have gained added value to attract customers. Even if vanity is an obvious driving factor, it is easy to find an excuse, saying that buying a new watch is an investment in industrial design or applied art.