Kaleido 4 upgraded the screen found in most color e-readers, promising better contrast and faster refreshes
A new color e-paper generation
E Ink says Kaleido 4 improves on its previous color screen technology with more vivid color reproduction, stronger contrast and faster refreshes. Kaleido 3 appears in e-readers and tablets from Kobo, PocketBook and Boox; Amazon’s Kindle Colorsoft uses a customized version.
Unlike E Ink’s Gallery 3 displays, Kaleido uses a color filter over a panel with black and white pigments. This design supports faster refreshes, but colors appear at lower resolution and can look muted. The filter also makes plain text darker than on black-and-white E Ink screens.
Improvements and remaining limits
E Ink says Kaleido 4 doubles the “color gamut volume” of Kaleido 3. The new technology still produces only 4,096 colors, compared with millions on modern LCD and OLED displays, and color images remain lower-resolution than black-and-white text.
The company also reports a 15 percent increase in white reflectance and a 50 percent rise in contrast. These changes could make text look less muddy than it does on Kaleido 3 screens.
Faster refreshes, first device
Gallery 3 uses moving colored pigments to create full-color images, but its slow refresh rate has limited its use in devices. Kaleido 3 refreshes more quickly, and Kaleido 4 adds an oxide TFT backplane that raises refresh rates to as much as 18 frames per second, fast enough for video playback.
Hanvon Technology will be the first company to use Kaleido 4, in its upcoming M10C II note-taking tablet. The device, launching in China, will have micro-etched tempered glass intended to reduce glare and give note-taking a more paper-like feel with its battery-free pen. Amazon and Kobo have not announced devices featuring Kaleido 4.
Key points
- Kaleido 4 promises improved color, contrast and refresh speed over Kaleido 3.
- The technology remains limited to 4,096 colors and lower-resolution color images.
- Refresh rates can reach 18 frames per second, enabling video playback.
- Hanvon’s M10C II tablet will debut the screen in China.