Are there computer monitors that don't use backlight technology?
PixelQi makes displays that can both be backlit and work with ambient light.
EDIT: However, the aforementioned domain is no longer owned by the screen manufacturer. The company is "presumed defunct" (1, 2)
I don't know if such computer monitors are availableyet. I do know that electronic paper works like this.
Impulse make transflective monitors: http://www.impulse-corp.co.uk/touchscreen-lcd-monitors/transflective-lcd-monitors/
There's a handful of similar manufacturers but they're nearly all professional, industry-specific stuff. Either outdoor display / advertising, medical, military etc. And they'll also have pricetags to accompany...
OLED would be the next logical jump, but the per-inch cost is still massive and it'll probably be usurped by LED-backlit for consumer goods. Perhaps you could investigate the few remaining SED manufacturers...
The computer monitor DASUNG's 3rd Generation E-ink Monitor-Paperlike 3 (Paperlike HD) does not use backlight
Below is the same answer as above. But with details if you're interested in those.
Product description
DASUNG's 3rd Generation E-ink Monitor-Paperlike 3 (Paperlike HD), 13.3” E-ink Screen (Carta & Flexible), 2200*1650 Retina Display. Just Like a Real Paper. Fast nearly as LCD. No Back Light. No Blue Light. No Screen Flash. You can Type, Code, Browse the Web, etc. Work well with any Equipment (HDMI). Support PC/ Mac/ iPhone/ iPad and so on.It is the best monitor to protect your eyes.
Manufacturer's video at https://youtu.be/Ah8dpfXL2LI
Review video at https://youtu.be/AeC3LIFTaho
This DASUNG's Paperlike HD monitor uses electronic paper. For those not familiar with this technology it is also sometimes called "electronic ink or electrophoretic display, are display devices that mimic the appearance of ordinary ink on paper. Unlike conventional flat panel displays that emit light, electronic paper displays reflect light like paper. This may make them more comfortable to read, and provide a wider viewing angle than most light-emitting displays. The contrast ratio in electronic displays available as of 2008 approaches newspaper, and newly (2008) developed displays are slightly better. An ideal e-paper display can be read in direct sunlight without the image appearing to fade."
Read more or order at the manufacturer's website at http://dasungtech.com