Dr Brian Iddon, from Salford University, claimed in a recent lecture that 'by the year 2000 electronic photography will have completely replaced current photographic techniques'. And it is British chemists who have scored another first by inventing the special dyes needed for the printing end of the process.
'The new technology will give very sharp colours and extremely precise pictures,' said Dr Iddon, demonstrating the invention by taking a picture of his audience with a charged-up 'filmless' camera. A reusable magnetic disc cassette replaces the usual silver halide film, avoiding all that fiddly winding on. Dr Iddon placed the cassette into a printer looking much like a video recorder and linked to a television screen. Within a few seconds he showed the picture on the screen.
This means that you do not need to develop and print all exposures on a film, only to find that half are worthless. If landscapes are over-exposed or portraits have granny's head missing, you can spot this on the television image before developing and printing. Waste and expense can be avoided. You can even rewind the electronic tape and take the shot again, or alter the colours or contrast on the screen.
To turn a passable screen image into a colour print, a heat- based technology - 'dye diffusion thermal transfer', or D2T2 - is used. This is a hi-tech version of the iron-on system used to print motifs on T-shirts, in which the heat transfers a pattern of dyes from thin paper on to the cloth.
According to Dr Iddon, D2T2 needs a much higher transfer temperature - about 400C - than that produced by a household iron, so conventional dyes were unsatisfactory. 'Out of over a million known dyestuffs, none was found to be stable enough,' he said. ICI's Colours and Fine Chemicals business in Manchester came up with dyes to fit the demanding bill for stability, colour quality and fastness.
In D2T2, a colour ribbon and the print receiver paper are pressed together under an array of 'thermal heads' in a printer resembling a mangle. The ribbon holds panels of yellow, magenta and cyan dyes which are transferred in the required pattern - programmed by an electronic message - to the print. The finished print paper feels similar to normal photographs.
Dr Iddon also stressed the environmental advantages of electronic photography: it is a clean and dry process with no used developing or printing solutions to be poured away.Reuse content