New low-power reflective LCD

[HarryT]

Originally Posted by pdurrant

The JBL screen has a contrast of 12:1. I couldn't find a figure on reflectance.

Is a high or a low reflectance good? A screen that reflected 100% of the light hitting it would just be a mirror, so I'm guessing that low is good?

[DrNefario]

I'd still love to see a solar-powered ereader. That way I might still be able to read them after the collapse of civilisation. Or maybe just without polluting and inefficient battery technology. I guess it's fairly unlikely that a CPU capable of handling the processing would work at solar power levels, and the file storage might also be a problem. Still, maybe solar-assisted?

[Dylrob]

Originally Posted by HarryT

Is a high or a low reflectance good? A screen that reflected 100% of the light hitting it would just be a mirror, so I'm guessing that low is good?

Well, think of it this way: bleached white paper has a significantly higher reflectance than newsprint.

[rem736]

Originally Posted by DrNefario

I'd still love to see a solar-powered ereader. That way I might still be able to read them after the collapse of civilisation. Or maybe just without polluting and inefficient battery technology. I guess it's fairly unlikely that a CPU capable of handling the processing would work at solar power levels, and the file storage might also be a problem. Still, maybe solar-assisted?

the upcoming earl eink tablet will come with solar charging.
meetearl.com

[pdurrant]

Originally Posted by HarryT

Is a high or a low reflectance good? A screen that reflected 100% of the light hitting it would just be a mirror, so I'm guessing that low is good?

High reflectance is good. A good quality Aluminium-based mirror has a reflectance of around 90%, but high quality white paper can high reflectance of 90-100%*. But white paper doesn't look like a mirror because of the way the light is reflected from the surface of the paper.

Reflective LCDs have poor reflectance because of the polarisers needed for their operation, which cut down the light by 50% immediately.

A 40% reflectance for an LCD (which is claimed for their eReader sized display) would be excellent.



*Some papers are listed as having more than 100% reflectance, because they contain optical whiteners that convert ultra-violet light falling on them into visible light.

[Sil_liS]

Originally Posted by pdurrant

*Some papers are listed as having more than 100% reflectance, because they contain optical whiteners that convert ultra-violet light falling on them into visible light.

Specifically blue light, which is why we can have white paper.

[GA Russell]

Originally Posted by pdurrant

The JBL screen has a contrast of 12:1. I couldn't find a figure on reflectance.

Thanks, Paul!

The JBL has very black text against a fairly dark background; so I guess I shouldn't be surprised that its contrast is not great.

[pdurrant]

Originally Posted by GA Russell

Thanks, Paul!

The JBL has very black text against a fairly dark background; so I guess I shouldn't be surprised that its contrast is not great.

The fairly dark background shows a low reflectance, which contributes a lot to the low contrast.

[HarryT]

Originally Posted by pdurrant

High reflectance is good. A good quality Aluminium-based mirror has a reflectance of around 90%, but high quality white paper can high reflectance of 90-100%*. But white paper doesn't look like a mirror because of the way the light is reflected from the surface of the paper.

Thanks. So reflectance is not a measure of how shiny a screen is, but how white it appears when illuminated by white light? High reflectance = a whiter background?

[pdurrant]

Originally Posted by HarryT

Thanks. So reflectance is not a measure of how shiny a screen is, but how white it appears when illuminated by white light? High reflectance = a whiter background?

In the way you're using whiteness, yes. But Whiteness is actually a separate measure.

Reflectance is a measure of how much incident light is reflected by a surface. It says nothing about how it is reflected - whether smoothly like a mirror, or randomly like a piece of paper.

Whiteness is a measure of how evenly a surface reflects light across the visible spectrum.

Gold, for example, has a very high reflectance, but very low whiteness, since it reflects blue light much less well than red light.

A display for use without a built-in light source, i.e. that relies on ambient light, should have a high reflectance, a high whiteness, and high contrast.

[HarryT]

Thank you - that's very helpful.

[mikij1]

No company has shown interest in these screens for his ereaders, am I right?

Mirasol, E Ink Triton, Bridgeston, Liquavista, Pixel Qi...

I lost faith in ink and color displays on ereaders.

[pdurrant]

Originally Posted by mikij1

No company has shown interest in these screens for his ereaders, am I right?

Mirasol, E Ink Triton, Bridgeston, Liquavista, Pixel Qi...

I lost faith in ink and color displays on ereaders.

Mirasol was used in an eReader, but unfortunately it proved to have a very poor viewing angle. It also had a front-light in a rather clunky way.

E-Ink Triton has also been used in eReaders, but is low-res and rather dark.

Bridgestone gave up on their display technology in 2012. I don't know if they sold the technology to anyone. It's a shame - they had large, flexible, colour displays.

Liquavista were bought by Amazon in May 2013. The technology was pretty far advanced, so I'm hoping that Amazon will use it in a ereader in the next year or so.

Pixel Qi have concentrated on replacement laptop and tablet displays. While the combination of hi-res reflective B&W with low-res transmissive colour is very clever, I don't think it's really suitable as an ereader display.

Liquavista still seems to be a good bet, but will almost certainly only be available in Kindles, if at all, but these new displays from Japan displays could be very good for someone. Kobo, perhaps?

[pl001]

Originally Posted by mikij1

No company has shown interest in these screens for his ereaders, am I right?

Mirasol, E Ink Triton, Bridgeston, Liquavista, Pixel Qi...

I lost faith in ink and color displays on ereaders.

Me too, I followed these for years only to be disappointed. In the meantime, LCD devices have improved dramatically. They are good enough that I simply don't have much personal need for such technology anymore and neither do most other people. I still find it interesting, but I'm not holding my breath.

[BoldlyDubious]

Actually, I think that the quality and performance of current E-ink technology is more than sufficient to enjoy (non-technical) books.
On the contrary, a cheap good-quality reflective LCD display would bring a real revolution to laptops and tablets. Such a screen would double battery life, be usable in full daylight and avoid eye strain, all at the same time. Without the limitations of E-ink (i.e., black-and-white and low frame rate). I would love to have such a display on my laptop!