DISASSEMBLY AND HEATING OF A LIQUID

CRYSTAL WATCH

Jurinus LesporisChante Sherwood

Jia Woei Liu LiuMarilyn LopezJain Dong Yu

1. What is meant by the term polarized light?

Polarized Light Light confined to one direction Travels in a particular plane

Polarized Light

Further Information on Polarized Light Light is an

electromagnetic radiation. Any electromagnetic radiation contains waves of some kind.

Normal light contains electromagnetic vibrations in all direction because is full of atoms aligned in different ways, and doing different things, which can lead to spread.

On the other hand, Polarized light is confined to one direction which means it only travel in a particular plane.

Light has 3 types of waves: a longitudinal wave and transverse waves in the X and Y direction.

Basic AnalogyYou can imagine the same would occur if you fed a jump rope

through a picket fence and wiggled it up-and-down or side-to-side.

The side-to-side waves would get blocked. 

2. Why is this unusual phase of matter called the liquid crystal phase?

Comparison of Liquid and Solid State

Liquid:•particles can move/slide past one another

Solid:•rigid - particles cannot move/slide past one another

The Liquid Crystal State Some materials exhibit some of the

behavior of being both the solid state and liquid state, but are neither.

These materials stay in the orientation (or ordered framework) as a solid and move around a container like a liquid.

Video: Liquid Crystal Phase Transition

CE8's smectic A to chiral nematic (aka cholesteric) phase transition at about 145degC followed by the cholesteric colours deepening with increasing temperature as the chiral layers twist up in 180deg increments.

3. What type of liquid crystal molecules are used in watch displays?

Twisted Nematic Phase Liquid Crystals

4. What condition causes the panel segments to turn black?

Liquid crystals are temperature sensitive and when an electric charge is applied to the liquid crystals it will cause the liquid crystal molecules to change its alignment.

When there is no voltage, twisted nematic crystals will be twisted.

The liquid crystals have a precise alignment and light is able to pass through both polarizers and reflect off the mirror and pass back through both polarizers; therefore, the panel will appear silver.

When voltage is applied, the nematic crystals will untwist and control the amount of light that passes through. The voltage is applied and the liquid crystal molecules lose its alignment.

The polarized light from the first polarizer does not rotate 90 degrees to align with the second polarizer, so the light is unable to pass through the second polarizer and causes the segment panels to appear black.

5. What color does the panel turn when the temperature of the LCD panel is above themelting point of the liquid crystal molecules?

The Screen turns Black.

WHAT COLOR DOES THE PANEL TURN WHEN THE TEMPERATURE OF THE LCD PANEL IS ABOVE THE

MELTING POINT OF THE LIQUID CRYSTAL MOLECULES?

In-line Discussion of Observations and Findings

Observation 1:The screen remain totally clear/blank/white throughout the heating process until it reached the point of about 60° Celsius.

The crystal remained relatively stable and maintained their orientation until they reached the melting point, and behaved like they were in the total liquid state.

Observation 2:When the screen was squeezed, that squeezed spot turned black.

When the screen is pressed the molecules of the liquid crytal are pushed into motion the crystal like ordering is disturbed, and it takes up the random (isotropic) order of liquid phase.

Observation 4:Moving the two powered wire connectors along the screen conductive sides caused .

The voltage supplied untwist the nematic crystal.

Observation 3:When the top polarizing film was removed and rotated 90 degrees any direction, the whole screen was black.

The light hitting this film was polarized (that is traveling in one certain direction/plane); when this light hit another polarizing filter,

(Bonus)

Video: (Sharp) How LCD Works A Brief Overview Of How LCD Function