Japan Display cranks up ultra low power colour LCD panels
No backlight means power draw of just 3mW
Japanese electronics giants Sony, Toshiba and Hitachi have been showing off new low-power LCD display technology which seems to combine the best of LCD and e-ink by dispensing with the backlight and instead relying on reflected light.
The firms formed their joint venture, Japan Display, earlier this year and appear to have been pretty busy since, showing off several designs at last week’s Flat Panel Display International conference in Yokohama.
Dispensing with the backlight means the display draws just 3mW of power when displaying static images.
It is able to do this by reflecting external light off the panel to render a monochrome image which is then filtered through a Light Control Layer featuring colour filters.
In a similar way to e-ink, each pixel is able to retain its colour without requiring any more power.
"This display is a reflective type, but as it uses liquid crystal, it has electric circuits built in,” a Japan Display spokesman told DigInfo.tv.
“The circuits can retain signals. This feature is called Memory in Pixels. With a still picture, once the data has been written, it can be retained, so power consumption is extremely low."
There are two versions of the technology. The first has a reflection rate of 40 per cent but only five per cent of the NTSC colour gamut, while the second has a better colour gamut – 36 per cent – but a reflection rate of only 28 per cent, making the picture dimmer.
The first technology is said to be ready for mass production today and is likely to be seen in e-readers in the short term, until the Japan Display boffins can turn up the colour and improve the 30:1 contrast ratio that will make it suitable for other applications. ®
COMMENTS
Re: Resolution and size
Until tablets use a display technology that doesn't flicker, can be powered for days without recharging, and can be read in bright sunlight, there will be a place for e-Readers.
Something like an iPad is just about okay for flicking through a magazine, but reading anything longer on those screens is a one-way trip to a headache.
For wallcoverings, there's inkjet-printed OLED on a flexible backing. Far too expensive right now, but it will revolutionise interior lighting and design whenever the production cost drops (and cell lifetime improves, it has to be said).
Colour vs brightness
Since the colour is by a filter, inherently the better the colour the less light there is. If the filters perfect you'd lose 2/3rds of the light as the Red filter blocks all the green and blue parts of spectrum to get the red colour.
Hence if you have pastel "weak" colour the filter blocks maybe 10%.
So they can't make it much "Better". It's physics. If you are using passive filters and ambient light then maybe 50% to 60% reflection with very pale colours and no better than 28% to 33% with good colour.
Mirasol can achieve the brightest passive colour display as it's mirrors, not pigment/dye filters and LCD.
The LCD polarisers also lose light.. The LCD itself can be pretty clear.
Read this: http://www.ipctechnology.com/support/techinfo/color_gamut.htm
In this context, the NTSC colour gamut refers to more than just what the "Never The Same Colour" TV standard could achieve. By this measure, the display that achieves 36% of the NTSC gamut is about 1/2 as good as a CRT display of old (not an NTSC CRT specifically, just an RGB CRT, presumably).
How does the reflectivity and contrast numbers stack up against the first gen eInk screens that lead to the Pearl devices we are currently used to I wonder ? That would have been an interesting comparison.
Re: Resolution and size
Reflected light tires the eyes less than direct light, so even if there were no power savings this would be the preferred technology for everything if the quality was in the same ballpark and a backlight could still be used to add light where there isn't enough ambient light.
The quality would have to match that of current LCD IPS technology to start replacing displays on high end smartphones and tablets.
Resolution and size
Can't say I'd want one for an e-reader, I think they're a dead end and will be superceded by tablets with high res displays. What I would like it for would be a wall picture display, res 1920x1080 or better, screen size 24 inch upwards. Add a wireless interface so it can be accessed remotely and I'd be out to buy one straight away.
