What kind of displays can I use effectively with a coin cell battery (CR2450)? The backlight or the entire display would be on only when necessary. From previous answers I know that a liquid crystal display without backlight can be used but I wanted to know if there is some kind of display with good visibility at night. Is there some kind of "ultra-low-power" display with good visibility at night?
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1\$\begingroup\$ Anything that emits light is going to consume significant energy to do so. Your options are those used by watches: fluorescent or very reflective backing, user-triggered brief backlight, e-paper (huge hassle to obtain and drive), or (for very infrequently changing displays) mechanical high-contrast segments. \$\endgroup\$– pjc50Commented Apr 23, 2014 at 15:36
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\$\begingroup\$ To be clear, you want it to constantly emit light, not light up on demand like the backlight on some digital watches? \$\endgroup\$– John UCommented Apr 23, 2014 at 15:59
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\$\begingroup\$ The backlight or the entire display would be up only on demand, there's no problem. \$\endgroup\$– Rui LimaCommented Apr 23, 2014 at 16:11
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1\$\begingroup\$ 5mA is a lot for CR2450 battery. \$\endgroup\$– KamilCommented Apr 23, 2014 at 18:32
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\$\begingroup\$ You're right. THat was bugging me because I saw a project that used a coin cell battery (the LIR2032) but, now that I take a closer look to that battery's datasheet it has a maximum discharge current of 70mA. \$\endgroup\$– Rui LimaCommented Apr 23, 2014 at 21:33
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2 Answers
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LCD display with a tritium backlight (half-life ~12 years) should be possible. The tritium emits beta particles that can excite phosphors to emit visible light. Glass is typically used to contain the tritium gas.
Watches have been made incorporating this principle, some Ball watches currently use tritium capsules for analog dial illumination, and there is at least one company claiming to offer micro-capsules.
Don't expect spectacular brightness, even nuclear-powered illumination has its limits.
answered Apr 23, 2014 at 15:58
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E-paper needs no power to maintain state, but has low refresh rate. With a LED side light it is visible even at night.
answered Apr 23, 2014 at 15:31