In addition to the enabling technology of the LCD, there are several other components that are critical to making the watch function properly. First of all, there has to be a timing mechanism (after all what is a watch that doesn’t keep time worth?). There has to be a controller to tell the display what time or date to display as well as set the time and date. There has to be a power source to drive the display, timing crystal, and controller. And finale, there has to be some means of connecting all of these components together.

Timing crystal
This timing mechanism is a quartz crystal that provides a constant-frequency signal to the electronic circuit in the watch. When certain crystals, including quartz, are excited with an electric field, they vibrate at a particular frequency. This vibration can be sensed electronically to provide a means for observing the vibrational frequency of the crystal.

Controller/IC “chip”
The integrated circuit (IC) or “chip” is programmed with the frequency of the crystal and “knows” how many cycles must pass in each second. Once that number of cycles has passed, it increments the second count by one. After 60 seconds it increments the minute readout. After 60 minutes it increments the hour readout. After 24 hours it increments the date readout, etc. The IC must tell the LCD what segments need to be turned on or off in order to display the correct digits in the LCD. The IC also stores the current date and time and has a means for setting them. This is usually done by connecting two or more “pins,” or leads, from the IC chip together. Since the IC chip is so small, the pins are connected to tabs on the side of the watch that are pressed to make the contact.

Battery
A 1.5 V alkaline batter is used to supply the power to the LCD, IC chip, and timing crystal.

Printed circuit board
In order to make all of the electrical connections, a printed circuit board is used that is placed in a specific position relative to the other components in the watch. The printed circuit board consists of several conductive paths made of metal on a plastic substrate. These paths connect the pins on the IC to the battery, timing crystal, and contact pads for setting the time and date. The connection to the LCD is a little different than the others since it requires more precise alignment of the conductive paths and the LCD in order to properly address each segment in the LCD. This is accomplished with a specially designed piece of rubber.

Conductive rubber laminate
The conductive rubber laminate is a layered structure of alternating layers of electronically conductive and electronically insulating material. This arrangement allows for the conduction of electricity in one direction, but not the other.

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