Electronics > Projects, Designs, and Technical Stuff
LCD design, is this good enough?
gearedbyby:
it's a old boy,good luck ;D
TERRA Operative:
Interesting thread. Maybe someone can follow in your footsteps to get new LCD's for all the old HP benchtop multimeters. :D
robertbaruch:
Supplier B sent back detailed drawings, 5 pages.
First page: Overall dimensions, pin pitches, pin positions, and electrical/optical data. There is an inset box asking for the best display angle. Where 90 degrees is vertical (i.e. looking straight down at the display), they give a choice between 80, 60, and 40 degrees. My angle would be 60 degrees.
I note that there is also a bump of some kind on the left side for what appears to be sealing. The original LCD also has a hard black bump, but on the right side. I don't think this should make much of a difference, but I am going to ask that it be moved to the other side anyway.
Second page: Segment designators, and dimensions for 5x7 matrices.
Third page: Two diagrams, the first showing segment connections to pins, the second showing common connections to pins.
Fourth page: A matrix showing COM0-COM7 on the Y axis, and pins 1-144 on the X axis.
Fifth page: "The Display Effect", showing an overall drawing.
All is correct, with the exception of the bump on the side. Also, the lettering on the indicators is not great. They did specify the indicator height correctly, but appear to have ignored the table I included for where their left sides are and how long they are. I gave them that feedback, asking them to use the table, and also I gave them a TTF font file they can use (it's DejaVu Sans, so it's free). That and any vector editor should get them to the right look.
I'm attaching the PDF they sent me -- if you're interested, just download it. Don't want to go through the bother of converting to images :)
robertbaruch:
Supplier B (may as well call them DDX Electronics) sent back new drawings (attached). This seems to solve the font problem, moves the bump to the right side (yay!) and also shows the viewing angle at 60 degrees.
However, the lettering is in the wrong place. They are approximate, but not according to spec. I suspect the engineer just eyeballed it. It's important to get this right, because retro restoration.
I sent back an email explaining this, and showing an example of the SHFT indicator, with calculations showing that the left edge must be 0.2 mm left of the left edge of segment 2AH, where the diagram they sent shows it on the right of 2AH. I also sent a drawing with a table. Hopefully this makes it easier for them.
*edited to use attachment as inline image
Benta:
I'm immensely impressed with the efforts you've put into this project and the results achieved so far.
Please keep us updated.
All the best.
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