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Optimization of hammers in Braille printers
2006 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Tactile print has been used since the beginning of 1800, at first not for visually impaired but as an invention (called Sonography) for the artillery to read and write in darkness and for making several copies of a document at once, though it was never used as intended because of it’s complexity with characters representing sound and not letters. Sonography characters were also to big to be covered by a single finger tip wich made reading slow. Later on Sonography was presented at a school for blind students. It was first rejected by the teachers but the students pushed on. One of the first students to encounter the Sonography was Louis Braille. He reworked the 12- dot Sonography to a six dot literal system. Over the years the Braille system has been improved and is now used for science, mathematics and also music purpose. With the possibility to connect Braille printers to personal computers even graphics can be made, making abstract tables of figures visualized by diagrams and charts. This master thesis is about optimizing hammers in Braille printers. There has been some problems with dot quality in Braille printers. The first problem is that some dots are not embossed to the same height. The problem is somewhat coupled to increased temperature in the printing head depending on low efficiency. An other problem is how to measure striking force. Dynamic laser measurement turned out to be the best method to measure the striking force. By knowing speed and mass of movement, energy can be calculated with ease. Optimization of the hammers striking force was made by static measurement and modelling using Femlab and Matlab. The Femlab static modell was verified by measurement with a force sensor at different displacement. Modifications modelled in Femlab and verified in static force measurement were then dynamically tested and measured with laser to make sure that they worked in reality. Finally hammers were tested in a printing head on different paper qualities. It turned out that the dot quality was highly dependent on the rubber shock absorbers in the hammers rather than solenoid efficency.

Place, publisher, year, edition, pages
Keyword [en]
Technology, Braille Printers, Hammers, Electromagnetics
Keyword [sv]
URN: urn:nbn:se:ltu:diva-56436ISRN: LTU-EX--06/215--SELocal ID: d3527568-cd53-48ac-ac9e-5008c44218c1OAI: diva2:1029823
Subject / course
Student thesis, at least 30 credits
Educational program
Electrical Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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