28-06-2012, 03:32 PM
PROPELLER LED DISPLAY
PROPELLER LED DISPLAY.docx (Size: 1.55 MB / Downloads: 312)
ABSTRACT
This project is a special kind of circular LED display. With the help some mechanical assembly, LED count, hardware requirement, and hence overall cost is cut to very affordable price. Also, maintenance and repairing of the display is so easy, that anyone having a little electronics knowledge, can take care of this. All the synchronizing can be implemented through software.
First of its kind, made using the 20-pin 8051 series microcontroller, this project use the principle of Space Multiplexing. This propeller display is mechanically scanned and displays the characters in digital format. Made from scrap it can be used anywhere and everywhere and the most amazing fact about this display is it’s crystal clear display. This display consists of just 8 bright LEDs which are rotated to show the display.
For building this project, requirement is just a small 20 pin microcontroller, a position encoder, and LEDs. This display can show the messages, which will require a whopping 525 LEDs. So hardware and cost minimization is achieved.
LITERATURE SURVEY
This project was started with a simple principle which is frequently encountered in our everyday life, which is Persistence of Vision. This phenomenon makes one feel fast moving/changing objects to appear continuous. A television is a common example, in which image is re-scanned every 25 times, thereby appear continuous.
Further, a glowing object if rotated in a circle at fast speed, it shows a continuous circle. By modifying this basic idea, 8 LEDs can be rotated in a circle, showing 8 concentric circles. But if these LEDs are switched at precise intervals, a steady display pattern can be shown.
Existing Systems:
Existing systems do employ POV principle, but for displaying each pixel, individual LED is used. This results in a huge number of LEDs even for small sized displays. By using a propeller type display, LED count can be kept to a bare minimum. Even 8 LEDs can perform a task of over 525 LEDs.
Applications:
Applications can find their way into cost effective solutions for large public displays, information systems. It can directly replace Railway station information displays, bus stands and many more places.
What is PROPELLER LED DISPLAY?
PROPELLER:
Propeller is a term associated with a circular rotating object. As this project needs to rotate whole circuit assembly, there must be some prime mover attached to it. So, the term ‘Propeller’.
LED DISPLAY:
This project using bright light emitting diodes for displaying the characters and symbols on its assembly.
That’s why this project is named as ‘PROPELLER LED DISPLAY’
Basic principle behind this project:
POV (Persistance Of Vision):
This is the phenomenon which is related to vision capability of human eye by which an after- image is thought to persist for approximately 1/25th of a second.
So, if someone is observing the images at a rate of 25 images per second, then they appear to be continuous. The best example of this property is the red circle we observe when we rotate the firecracker or incense stick in circle.