Forums

LCD character size

Started by Unknown March 5, 2022
We're designing a new rackmount box, basicly a fancy power supply,
with an 800x480 4.3" LCD on the front. Roughly this:

https://www.dropbox.com/s/8ubv5if7cbnsjzn/P940-8_front.jpg?raw=1

Does anyone have an estimate of how many characters X and Y we might
use? We'll try to fire it up next week and experiment, but I'd like to
start thinking about screen layouts and have no idea about what might
be reasonable. We'd want good visibility so wouldn't want anything
really tiny.

I'd prefer a fixed-size, fixed-pitch font, to keep the design simple.
We might have some characters/boxes with different background colors.

The off-screen (mechanical) pushbuttons will be page left/right and
cursor up/dn/left/right, and a spinner knob. There will be some box
overhead pages and one page per plugin board.





-- 

I yam what I yam - Popeye
On a sunny day (Sat, 05 Mar 2022 11:25:36 -0800) it happened
jlarkin@highlandsniptechnology.com wrote in
<4cd72hleqqcmvfjmkevjqqaj6isv15tah7@4ax.com>:

>We're designing a new rackmount box, basicly a fancy power supply, >with an 800x480 4.3" LCD on the front. Roughly this: > >https://www.dropbox.com/s/8ubv5if7cbnsjzn/P940-8_front.jpg?raw=1 > >Does anyone have an estimate of how many characters X and Y we might >use? We'll try to fire it up next week and experiment, but I'd like to >start thinking about screen layouts and have no idea about what might >be reasonable. We'd want good visibility so wouldn't want anything >really tiny. > >I'd prefer a fixed-size, fixed-pitch font, to keep the design simple. >We might have some characters/boxes with different background colors. > >The off-screen (mechanical) pushbuttons will be page left/right and >cursor up/dn/left/right, and a spinner knob. There will be some box >overhead pages and one page per plugin board.
If you do not need graphics then that resolution is probably overkill 128x64 LCD: http://panteltje.com/pub/gamma_soectrometer_IMG_4505.JPG 640x480 same font... http://panteltje.com/pub/xvtx-p.gif Make a drawing to size first? There are a million fonts to chose from, some are free. Some LCDs have their own character set. Does it run an OS? Linux Xwindows has many fonts
jlarkin@highlandsniptechnology.com wrote:

> We're designing a new rackmount box, basicly a fancy power supply, > with an 800x480 4.3" LCD on the front. Roughly this: > > https://www.dropbox.com/s/8ubv5if7cbnsjzn/P940-8_front.jpg?raw=1 > > Does anyone have an estimate of how many characters X and Y we might > use? We'll try to fire it up next week and experiment, but I'd like to > start thinking about screen layouts and have no idea about what might > be reasonable. We'd want good visibility so wouldn't want anything > really tiny. > > I'd prefer a fixed-size, fixed-pitch font, to keep the design simple. > We might have some characters/boxes with different background colors. > > The off-screen (mechanical) pushbuttons will be page left/right and > cursor up/dn/left/right, and a spinner knob. There will be some box > overhead pages and one page per plugin board.
Why make the screen so small? You have plenty of room - why not use it? You could show a huge amount of important information that would be very valuable to the customer. They would like it. You could increase the value and your profit. Stop and think for ten minutes what you would like to see. Voltage, current, time plots, errors, etc. It would take your programmer a day to install. The chips and ram needed are extremely cheap and don't take much space. You would own the world.
On 3/5/2022 21:25, jlarkin@highlandsniptechnology.com wrote:
> We're designing a new rackmount box, basicly a fancy power supply, > with an 800x480 4.3" LCD on the front. Roughly this: > > https://www.dropbox.com/s/8ubv5if7cbnsjzn/P940-8_front.jpg?raw=1 > > Does anyone have an estimate of how many characters X and Y we might > use? We'll try to fire it up next week and experiment, but I'd like to > start thinking about screen layouts and have no idea about what might > be reasonable. We'd want good visibility so wouldn't want anything > really tiny. > > I'd prefer a fixed-size, fixed-pitch font, to keep the design simple. > We might have some characters/boxes with different background colors. > > The off-screen (mechanical) pushbuttons will be page left/right and > cursor up/dn/left/right, and a spinner knob. There will be some box > overhead pages and one page per plugin board. > > > > >
Normally you would want a fixed character size for that sort of thing (for every sort of thing if you ask me unless you want to be artistic). I usually do 8x12 pixels, which in your case would be smallish, 0.12mm. So your best approach would be to go 4 physical pixels into one logical one and do 8x12, this would mean 25 symbols per line, 20 lines. If this is not enough you can still go for the 0.12mm pixel and get 50 symbols/40 lines but people past say 55 will need spectacles to read that. Don't fall for blurry scaling, make sure each character has the same pixel representation anywhere on the display. You can use my character set (I made it around 1985...), http://tgi-sci.com/misc/chset.gif , people don't complain about it and this won't be the first time I declare it "use for free". If you go for it let me know, I can send you the binary bitmap. ====================================================== Dimiter Popoff, TGI http://www.tgi-sci.com ====================================================== http://www.flickr.com/photos/didi_tgi/
On 3/5/2022 22:57, Dimiter_Popoff wrote:
> On 3/5/2022 21:25, jlarkin@highlandsniptechnology.com wrote: >> We're designing a new rackmount box, basicly a fancy power supply, >> with an 800x480 4.3" LCD on the front. Roughly this: >> >> https://www.dropbox.com/s/8ubv5if7cbnsjzn/P940-8_front.jpg?raw=1 >> >> Does anyone have an estimate of how many characters X and Y we might >> use? We'll try to fire it up next week and experiment, but I'd like to >> start thinking about screen layouts and have no idea about what might >> be reasonable. We'd want good visibility so wouldn't want anything >> really tiny. >> >> I'd prefer a fixed-size, fixed-pitch font, to keep the design simple. >> We might have some characters/boxes with different background colors. >> >> The off-screen (mechanical) pushbuttons will be page left/right and >> cursor up/dn/left/right, and a spinner knob. There will be some box >> overhead pages and one page per plugin board. >> >> >> >> >> > > Normally you would want a fixed character size for that sort of thing > (for every sort of thing if you ask me unless you want to be artistic). > I usually do 8x12 pixels, which in your case would be smallish, 0.12mm. > > So your best approach would be to go 4 physical pixels into one > logical one and do 8x12, this would mean 25 symbols per line, 20 lines. > If this is not enough you can still go for the 0.12mm pixel and get > 50 symbols/40 lines but people past say 55 will need spectacles > to read that. > Don't fall for blurry scaling, make sure each character has the same > pixel representation anywhere on the display. > > You can use my character set (I made it around 1985...), > http://tgi-sci.com/misc/chset.gif , people don't complain about it > and this won't be the first time I declare it "use for free". > If you go for it let me know, I can send you the binary bitmap. > > ====================================================== > Dimiter Popoff, TGI&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; http://www.tgi-sci.com > ====================================================== > http://www.flickr.com/photos/didi_tgi/ >
No need to ask for it, I must have put it there for someone years ago: http://tgi-sci.com/misc/chset12.wind . Each character starts at 12*N, where N is the ASCII code; a byte per line, obviously.
On Saturday, March 5, 2022 at 11:25:51 AM UTC-8, jla...@highlandsniptechnology.com wrote:
> We're designing a new rackmount box, basicly a fancy power supply, > with an 800x480 4.3" LCD on the front. Roughly this: > > https://www.dropbox.com/s/8ubv5if7cbnsjzn/P940-8_front.jpg?raw=1 > > Does anyone have an estimate of how many characters X and Y we might > use?
Well, ten characters per inch and five lines per vertical inch is readable. Typewriter spacing... More to the point, why do a new screen and protocol for a new box? Could you go to USB or Bluetooth for the communication, and source a display (like a tablet, or electronic picture frame, or just an app for a cellphone) that has builtin software support? Doesn't it make more sense to use a mass-produced standard software target instead of a novel build-from-sticks hardware assembly?
whit3rd <whit3rd@gmail.com> wrote:

> On Saturday, March 5, 2022 at 11:25:51 AM UTC-8, > jla...@highlandsniptechnology.com wrote: >> We're designing a new rackmount box, basicly a fancy power supply, >> with an 800x480 4.3" LCD on the front. Roughly this: >> >> https://www.dropbox.com/s/8ubv5if7cbnsjzn/P940-8_front.jpg?raw=1 >> >> Does anyone have an estimate of how many characters X and Y we might >> use? > > Well, ten characters per inch and five lines per vertical inch is > readable. Typewriter spacing... > > More to the point, why do a new screen and protocol for a new box? > Could you go to USB or Bluetooth for the communication, and source a > display (like a tablet, or electronic picture frame, or just an app for > a cellphone) that has builtin software support? > > Doesn't it make more sense to use a mass-produced standard software > target instead of a novel build-from-sticks hardware assembly?
USB interface is a good idea. However, you need a computer which is not so useful for rack mount installations. Also, you must download and install the software on each computer that could be used. Microsoft 11 is making it very difficult to install non-approved software. You can run linux, but then you need a version of software that runs on different flavors. You could attach to a smartphone, but again you need different versions. You could use bluetooth instead of USB, but you still have to download and install software for sifferent hosts. Running software on a host computer is a very bad idea.
On Saturday, March 5, 2022 at 9:25:11 PM UTC, whit3rd wrote:
> On Saturday, March 5, 2022 at 11:25:51 AM UTC-8, jla...@highlandsniptechnology.com wrote: > > We're designing a new rackmount box, basicly a fancy power supply, > > with an 800x480 4.3" LCD on the front. Roughly this: > > > > https://www.dropbox.com/s/8ubv5if7cbnsjzn/P940-8_front.jpg?raw=1 > > > > Does anyone have an estimate of how many characters X and Y we might > > use?
short answer: get a Snellen Eye chart; Your characters size should be at least as those at the 20:20 (6:6 in EU) line For easy readability use double that (20:40) longer answer: The characters need to be large enough to be distinguishable from one another, from a stated maximum viewing distance, by your intended user. First I assume your letters & numbers use a simple block type font (sans serif). characters are high contrast (black on white background, or vice versa). that white part of the image luminance is a comfortable brightness range. the pixels constructing the characters are small, not visible at the viewing distance. the person has with 20:20 vision (6:6 in EU). (Apply formula here - to lazy to look it up) To the degree you vary from these assumptions, the size should be increased.
On Saturday, March 5, 2022 at 9:52:58 PM UTC, Rich S wrote:
> On Saturday, March 5, 2022 at 9:25:11 PM UTC, whit3rd wrote: > > On Saturday, March 5, 2022 at 11:25:51 AM UTC-8, jla...@highlandsniptechnology.com wrote: > > > We're designing a new rackmount box, basicly a fancy power supply, > > > with an 800x480 4.3" LCD on the front. Roughly this: > > > > > > https://www.dropbox.com/s/8ubv5if7cbnsjzn/P940-8_front.jpg?raw=1 > > > > > > Does anyone have an estimate of how many characters X and Y we might > > > use? > short answer: > get a Snellen Eye chart; Your characters size should be > at least as those at the 20:20 (6:6 in EU) line > For easy readability use double that (20:40) > > longer answer: > The characters need to be large enough to be distinguishable > from one another, from a stated maximum viewing distance, by > your intended user. > First I assume > your letters & numbers use a simple block type font (sans serif). > characters are high contrast (black on white background, or vice versa). > that white part of the image luminance is a comfortable brightness range. > the pixels constructing the characters are small, not visible at the viewing distance. > the person has with 20:20 vision (6:6 in EU). > (Apply formula here - to lazy to look it up) > > To the degree you vary from these assumptions, the size should be > increased.
w = 2 * d * tan (2.5 arcmin) so if d = 6 feet = 72 in., then w = 0.0175" formula from here https://en.wikipedia.org/wiki/Snellen_chart
On Saturday, March 5, 2022 at 10:04:20 PM UTC, Rich S wrote:
> On Saturday, March 5, 2022 at 9:52:58 PM UTC, Rich S wrote: > > On Saturday, March 5, 2022 at 9:25:11 PM UTC, whit3rd wrote: > > > On Saturday, March 5, 2022 at 11:25:51 AM UTC-8, jla...@highlandsniptechnology.com wrote: > > > > We're designing a new rackmount box, basicly a fancy power supply, > > > > with an 800x480 4.3" LCD on the front. Roughly this: > > > > > > > > https://www.dropbox.com/s/8ubv5if7cbnsjzn/P940-8_front.jpg?raw=1 > > > > > > > > Does anyone have an estimate of how many characters X and Y we might > > > > use? > > short answer: > > get a Snellen Eye chart; Your characters size should be > > at least as those at the 20:20 (6:6 in EU) line > > For easy readability use double that (20:40) > > > > longer answer: > > The characters need to be large enough to be distinguishable > > from one another, from a stated maximum viewing distance, by > > your intended user. > > First I assume > > your letters & numbers use a simple block type font (sans serif). > > characters are high contrast (black on white background, or vice versa). > > that white part of the image luminance is a comfortable brightness range. > > the pixels constructing the characters are small, not visible at the viewing distance. > > the person has with 20:20 vision (6:6 in EU). > > (Apply formula here - to lazy to look it up) > > > > To the degree you vary from these assumptions, the size should be > > increased. > w = 2 * d * tan (2.5 arcmin) > > so if d = 6 feet = 72 in., then w = 0.0175" > > formula from here > https://en.wikipedia.org/wiki/Snellen_chart
This is the minimum "feature" size - i.e., the pixel, your characters should be composed of. Your 800x480 4.3"-diagonal LCD has dimensions 5.375" x 3.225" and a pixel spacing (assuming square pixels) 0.00671875" So this is below w (above) the pixels will not be visible at 6 ft.