INTRODUCTION Fax machines became popular around the world in the 1980s. In order to reduce paper consumption we use paperless fax machine. In this paperless fax machine single-touch panel is used as input and output device.
Transmitted and received fax documents are stored in memory. A pressure sensitive stylus is used to write on the touch panel. Handwriting reconstruction algorithm is used.
The modem module for sending and receiving faxes. The touch panel displays the fax documents and accepts the handwriting signatures. The tip of the pressure sensitive stylus is connected to a pressure sensor through a spring coil. During a signing act, the pressure at the tip is measured, digitalized by an ADC, and finally sent to MCU for subsequent processing.
OPERATING PROCEDURES The touch panel fax machine can operate in one of the three modes: 1. Fax receiving mode 2. Browsing and handwriting mode 3. Fax transmitting mode
HANDWRITING RECONSTRUCTION The handwriting reconstruction algorithm, turn an user’s signing act into a digital signature as close to the original as possible. During the signing act, the data from the pressure sensitive stylus and the touch panel are sampled by using timer interrupts in MCU.
The sampled analog values are then converted into digital values by ADCs and buffered in two FIFO queues in order as shown in figure.
Some issues that are considered in data collection and processing. 1. Resolution of touch panel 2. Signal synchronization 3. Pressure and Strokes 4. Handwriting Reconstruction
Resolution of touch panels: A single-touch panel is composed of two major parts, an LCD screen for displaying and a thin touch layer for inputs. The resolution of an LCD screen is specified explicitly by enumerating the number of pixels both in width and height. The resolution of the touch panel is determined by the number of bits used in the ADCs adopted.
Signal synchronization: Single-touch panels can response exact one location that is being touched at a time. Timer interrupt intervals are made set to be constant. According to changes in the pressure data measured, handwriting reconstruction algorithm can generate the strokes with different thickness.
Pressure and Strokes: A simple two-step calibration procedure for the stylus is performed before writing. First, press the pen tip all the way down and record the pressure reading as PF . Next, let the tip off the touch panel and record the pressure again as PE. For any pressure P, the pressure ratio(PR) is calculated as PR=(P-PE)/(PF-PE)
Handwriting reconstruction: There are two types of methods to generate thickness of the stroke 1. line extension 2. circular extension
Circular extension is used in handwritingreconstruction.
CONCLUSION By using handwriting reconstruction algorithm the signature can be exactly reproduced. Consumption of paper can be reduced.
REFERENCES• http://ieee.ieeexplore.org/• ITU-T.37: Procedures for the Transfer of Facsimile Data via Store-and forward on the Internet, 1998.• ITU-T.38: Procedures for Real-time Group 3 Facsimile Communication over IP Networks, Amendment 1, 1999.• Handwriting Recognition Group, <hwr.nici.kun.nl>, May, 2008.