Custom made LCD Glass testing

A project log for NP-41 RPN Calculator

NP-41 is a hardware realization of the Nonpariel calculator simulator. It executes the original HP-41C / CV byte-codes.

Chris ChungChris Chung 10/01/2015 at 12:092 Comments

I ordered custom made LCD glass for this project. They are about the same size of the original HP-41C display. It's a 14 segment display w/ 12 digits.

The LCD glass is made w/ 6 Mux and 1/3 bias. With 1/6 duty cycle the contrast is not the best but there are so many segments and my target controller for this project does not have enough segment pins for a 4 Mux.

I have not yet make this into a PCB so I am testing drive the LCDs w/ a test rig setup of GPIO direct driving the display. Resistor arrays are used to allow for setting proper bias voltages.


Chris Chung wrote 01/14/2016 at 02:19 point

It is both expensive (for a hobbyist) and cheap (for commercial) at the same time. The design is from the old HP-41C calculator although it is not a direct clone. I specify the requirements and general layout and the factory draw it. After a few iterations / alternations it is finalized. It cost me less than a thousand US to get a dozen samples. I can get the unit cost to about $10 but I need to order batches of a few hundreds.

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jaromir.sukuba wrote 01/13/2016 at 14:47 point

Oh that display is sweet. Did you design the LCD? Where was it manufactured? How much does it cost?

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