CA2638342A1 - Radio frequency electronic whiteboard using pcb as detecting surface - Google Patents

Abstract

[Para 1] An electronic whiteboard uses parallel copper traces of a printed circuit board as the detecting surface. Each copper trace is terminated with a capacitor and resistor. The combination enables the picking up of radio frequency from the transmitter pen. With proper gain stage, the detected signal can identify the proximity of the writing pen. Since the detecting surface is made only of a printed circuit board, all the interfacing components can also be stuffed onto the same PCB. It dramatically simplifies the production of the electronic whiteboard without the intervention of human alignments, and the material cost will be reduced significantly. The idea was filed under the same name of the inventor, Lau Chun To, in China on 25th September 2007 and the China patent no. ZL 2007 2 0172112.0 was granted on 9th July 2008.

Description

Description [Para 1] The present invention relates to a method for the detection to co-ordinate a radio frequency sine wave emitting pen with the use of parallel metal traces on a printed circuit board (PCB) as the detecting surface. The radio frequency emitting pen is shielded with only the tip of the pen exposed so as to confine the emitting area.
With proper impedance at either ends of each metal trace, the detected radio signal can then be amplified and processed to give the digital equivalence for which the active detecting X-axis and Y-axis can be determined and the proximity of the pen can be identified with the use of digital logics. The accuracy of the detection can be adjusted by changing the space between the parallel traces.

[Para 2] The product is comprised of the following components:
o RF transmitter was build o Single straight copper wire was used to detect the RF
ca rri er o Amplify stages were built o Use sticky copper stripes to replace the wire o Use printed circuit board to replace the striped o Finalize the design o A demo was built [Para 3] With proper software, the detecting surface can identify the co-ordinate of the writing pen and data was sent back to the host computer. There are several approaches to implement the design of electronic whiteboard, Infra-Red detection, magnetic induction detection, video camera, etc. The basic method is to find a way to determine the X-detecting axis and the Y-detecting axis of the writing pen. The use of parallel straight metal traces on a printed circuit board to detect a radio frequency emitting pen is the most cost effective way to build electronic whiteboards.

Claims (7)

1. [Claim 1] An electronic whiteboard uses parallel copper traces of a printed circuit board as the detecting surface; each copper trace is terminated with capacitor or resistor or combination of capacitor and resistor. The combination enables the picking up of radio frequency from the transmitter pen, with proper gain stage; the detected signal can identify the proximity of the writing pen.
2. [Claim 2] A radio frequency electronic whiteboard, the writing surface being a printed circuit board with parallel metal lines.
3. [Claim 3] A radio frequency electronic whiteboard according to claim 1, in which the fundamental or harmonic frequencies of the transmitter pen determines the color of the pen.
4. [Claim 4] A radio frequency electronic whiteboard according to claim 1, in which at least one side of the writing surface is making up of parallel metal lines.
5. [Claim 5] A radio frequency electronic whiteboard according to claim 3, in which at least one side of the metal line is terminated with impedance to voltage ground.
6. [Claim 6] A radio frequency electronic whiteboard according to claim 1, in which the metal line forms part of the detecting circuit.
7. [Claim 7] A radio frequency electronic whiteboard according to claim 1, in which the printed circuit board is a layer of metal on the top of a flat panel.