Defects, flexoelectricity and RF communications: the ZBD story

ABSTRACT

The zenithal bistable display (ZBD) was the first liquid crystal device mode to be commercialised that uses nematic disclinations in a constructive fashion, to use the flexoelectric effect inherent to all liquid crystals but at the time was considered too weak an effect to be useful, and to transfer nano-replication methods to the LCD manufacturing environment. The genesis of the invention and spin-out company ZBD Displays Limited will be described, and the evolution of that company from licensing model, through fabless manufacturer to display provider and finally to a system provider for the retail sector. The story may be useful not just to those interested in the science behind a rather unusual LCD, but also those involved in taking technology from laboratory to manufacturing, from idea to commercial success.

Graphical Abstract

KEYWORDS:

• Nematic LCD
• bistability
• grating
• topological defects
• flexoelectricity
• manufacturing
• business models
• RF communications
• low power displays
• retail displays
• electronic-shelf-edge labels

Acknowledgments

The author wishes to thank all of the collaborators at the ZBD Suppliers (notably Varitronix, Solomon, GoWorld and our unnamed film and nickel suppliers); competitors at Nemoptic (notably Ivan Dozov, Jacque Angele, Thierry Laboureux and François Leblanc), E-Ink (notably Karl Amundsen, Rob Zehner and Paul Drzaic), Kent Displays (notably Asad Khan) and Gamma Dynamics (John Rudolph and Ken Dean); our investors (notably Nick Darby, Paul Morris, Clennell Collingwood, David Connell, Steven Lake, Richard Marsh and Jim Stoffel), the management (Chairmen Colin Garrett and Howard Ford; CEOs Henri-Luc Martin, Clive Mayne, Shaun Gray and Andrew Dark; CFOs Richard Scanlon, John Dernie, Carl Plucknett and John Varney) and the key operations personnel (particularly John McEachran and David Dix). Most of all, thanks are due to the technical team, especially Rich Amos, Dave Walker, Emma Wood and Steve Beldon. Above all, this article is dedicated to the two friends I owe most to making this a story of success: Guy Bryan-Brown and Bob Hook.

Disclosure statement

No potential conflict of interest was reported by the author.

Notes

1. Although invited, I did not believe that I was an inventor of VCT, since I had subsequently found an earlier paper that used homeotropic gratings: M. Nakamura and M. Ura (1981) J. Appl. Phys., 52 (1), pp 210–218.

2. Bryan-Brown states that the effect was actually a discovery rather than through a designed experiment. Whilst studying the homeotropic grating in an STN configuration, he found that he could only induce the high tilt state by applying electrical pulses. Despite the effect being restricted to just a tiny fraction of the cell he was observant enough to realise its importance.

3. Tenting refers to the deformation of the shim around the particle. A rigid shim would deform only slightly, bending around the particle to touch the glass surface at a large distance from the particle. A flexible shim, such as film, deforms elastically either side of the particle, touching the surrounding surface much closer to the particle. The size of the region of offset around the particle is directly related to both the size of the particle and the rigidity of the shim.

Additional information

Funding

This work was supported by the EPSRC under Grant [EP/L015188/1].