| Electronics > Beginners |
| Multimeters why not LCD? |
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| Kleinstein:
The custom LCDs are not that expensive in reasonable quantity and not all are really custom for a single meter. The graphical LCDs also need quite some extra power, while the B&W displays with 7 seg and extra symbols can be really low power. They are also often better readable - especially the older graphical LCDs had often poor contrast. The LED displays in early bench top DMMs where often made from standard 7 segment / 15 segment digits. They are also very nice to read and long lasting compared to OLED or VFD. They are just limited in showing special symbols and letters already may look a little odd. Quite some new bench top DMMs use graphical LCDs. |
| mariush:
There are all in one multimeter chips which have build in lcd driver, so they can drive the lcd segments directly. It saves money if you don't need extra lcd driver chips to increase power consumption along with chips on the back of the lcd displays (for row/column processing and all that). Other multimeter chips have i2c or SPI or some other method of transmitting data to a microcontroller, and then a microcontroller formats data and sends it to a graphical/segment LCD display. For multimeter companies it's cheap to make these 7 segment displays because they can reuse them with multiple multimeters or versions of the same multimeter ex see Uni-T UT139 series ... |
| Tom45:
Using a pixel display rather than fixed segments would allow much greater flexibility in what could be displayed in the various modes. However, the extra cost in firmware and processing time to paint a pixel display would likely slow down display response. And would certainly result in a higher cost meter. A meter with a pixel display and open source firmware could lead to an interesting variety of new features once the experimenters got their hands on it. |
| PsychoBoy:
Got it, thanks all, so it is mix of production cost, low power consumption and easy implementation. --- Quote from: Tom45 on May 15, 2019, 05:22:42 pm ---A meter with a pixel display and open source firmware could lead to an interesting variety of new features once the experimenters got their hands on it. --- End quote --- That's what I exactly thought, seems like it isn't huge problem to install such a display but the bigger is to implement a firmware, if indeed DMMs are single chip solutions. Anyway nowadays I think it's not a problem to put powerful lot-power consumption ARM processor. Thanks everyone for answering :) |
| newbrain:
--- Quote from: PsychoBoy on May 15, 2019, 04:56:20 pm ---I mean isn't it more expensive to design your own custom LCD display rather than pick off-the-shelf LCD dot matrix module? --- End quote --- Our kind host has a number of videos on this very subject, you might be surprised at the price for a custom LCD: |
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