សិល្បៈ
សម្រស់ និង សុខុមាលភាព
សិប្បកម្ម
វប្បធម៌ និង ប្រវត្តិសាស្ត្រ
ការកម្សាន្ត
បរិស្ថាន
ម្ហូប និង ភេសជ្ជៈ
វិស្វកម្មបញ្ច្រាស
វិទ្យាសាស្ត្រ
កីឡា
បច្ចេកវិទ្យា
ប្រដាប់ដែលស្លៀក
The Twisted Nematic LCD
Schadt and Helfrich, 1970. Every other display in this batch makes light; the LCD is a valve in front of a backlight. Rod-shaped molecules line up with a rubbed surface and twist a quarter-turn between two plates, carrying polarised light round with them — the cell is clear. A few volts stand the molecules up, the twist vanishes, the light is blocked. A valve costs power only to switch, which is why the LCD won. You will build a working cell.
កម្រិតខ្ពស់
6 hours
ការណែនាំ
1
1
The molecule whose shape is the whole device
The molecule whose shape is the whole device
5CB — 4-cyano-4'-pentylbiphenyl — is the first room-temperature liquid crystal (Gray, 1972), and almost every early LCD uses it or a relative. Its shape is the device: a rigid biphenyl rod so the molecules line up (the nematic phase), a floppy pentyl tail so it stays liquid, and a polar cyano end that is the handle the electric field grabs to switch it. Rigid enough to align, floppy enough to flow, polar enough to steer.
Tools needed:
Notebook and Pencil2
2
The twist, and why it needs two polarisers
The twist, and why it needs two polarisers
A liquid-crystal cell does nothing visible without a polariser each side — it rotates polarisation, which the eye cannot see. The plates are rubbed at 90 degrees, so the molecules form a quarter-turn helix that guides polarised light round to pass the crossed rear polariser: bright. A few volts stand the molecules up, the helix dies, the light is blocked: dark. Read the embedded polariser blueprint first.
Tools needed:
Notebook and Pencil3
3
Build a working cell and rub the alignment layer
Build a working cell and rub the alignment layer
A real build. Two ITO-coated glass plates (find the conductive side with a meter, ~hundreds of ohms). Wipe a thin PVA or polyimide film on each and RUB firmly one way — the grooves align the molecules. Assemble conductive faces in, rubbing directions at 90 degrees, ~10 um spacers, three edges sealed. Draw in 5CB by capillary action (warm it above ~35 C so it flows), seal the last edge. Add a polariser each side, axes crossed.
Test: crossed polarisers, no volts = bright; touch 3-5 V AC to the two ITO faces and the lit area goes dark. Use AC, not DC — DC electrolyses and kills the cell in minutes.
Materials for this step:
ITO-Coated Glass Slide2 ដុំ
5CB Liquid Crystal1 មល
Polarising Filter Sheet2 សន្លឹកTools needed:
Digital Multimeter (Lab Grade)
Bench Power Supply (30V/5A)
Precision Tweezers Set4
4
Measure the threshold voltage
Measure the threshold voltage
Loading Jupyter Notebook...
Tools needed:
Desktop Computerសម្ភារៈ
3- កន្លែងទុក
- កន្លែងទុក
- 2 សន្លឹកកន្លែងទុក
ឧបករណ៍ចាំបាច់
5- កន្លែងទុក
- កន្លែងទុក
- កន្លែងទុក
- កន្លែងទុក
- កន្លែងទុក
ប្លង់ពាក់ព័ន្ធ
ប្លង់ទាំងនេះចែករំលែកចំណេះដឹង — បច្ចេកទេស សម្ភារៈ ឬគោលការណ៍
CC0 សាធារណៈ
ប្លង់នេះត្រូវបានចេញផ្សាយក្រោម CC0។ អ្នកមានសិទ្ធិចម្លង កែប្រែ ចែកចាយ និងប្រើប្រាស់ដោយមិនចាំបាច់សុំអនុញ្ញាត។
គាំទ្រអ្នកបង្កើតដោយទិញផលិតផលតាមរយៈប្លង់របស់ពួកគេ ដែលពួកគេទទួលបាន កម្រៃជើងសារអ្នកបង្កើត កំណត់ដោយអ្នកលក់ ឬបង្កើតកំណែថ្មីនៃប្លង់នេះ ហើយបញ្ចូលជាការតភ្ជាប់ក្នុងប្លង់របស់អ្នកដើម្បីចែករំលែកចំណូល។