New calculator a thin wedge in Japanese sales race

As far as pocket electronic calculators are concerned, the world's largest maker has ''seen the light.'' The Japanese company Casio, now claiming 40 percent of the world market, has developed new state-of-the-art techniques to make the machines thinner, lighter, and cheaper.

It announced Tuesday an 0.8-millimeter (3/100ths of an inch) calculator, reputedly the thinnest in the world.

The device also needs no batteries, relying instead on light-activated solar power cells. The ''Sl-800,'' which is almost identical in size to most credit cards, is equipped with an eight-digit liquid crystal display with functions similar to ordinary pocket calculators. Casio officials said the company plans to put the calculator on the market in September, both in Japan and overseas. The retail price in Japan will be around $25, the company said.

This will be the shape of all calculators to come, Kazuo Kashio, executive managing director, predicts. He is one of four brothers who started making calculators in a backyard shed a quarter of a century ago.

To demonstrate his point, he opens up two tiny calculators - one of Casio's and one made by a rival company - to demonstrate the latest technological breakthrough.

The complex electronic circuits of the other company's calculator are molded onto a typical rigid board. Casio's circuits, however, are on a photographic film.

''It takes time to produce normal circuit boards,'' Mr. Kashio explains, ''but with our technique we can really achieve automated mass production, with obvious cost savings that can be passed on to the customer.''

Not wishing to give away trade secrets, he will only say that Casio uses normal photographic techniques to produce a developed film on which the circuits are printed. The most difficult aspect was to fix the LSI (large-scale integrated computer chip) onto the film, and it took company engineers considerable time to come up with a special paste that made attachment possible.

The new-style circuit is used in the new Casio calculator that is like a small note pad.

When it's opened, the solar cell is on the lefthand ''page,'' and the calculation functions are on the right. There are no raised buttons to be pressed. The numbers and symbols are printed on the surface and require only the lightest touch.

''One of the drawbacks of conventional small calculators is that the buttons have become so tiny it is difficult for people with big fingers to avoid making mistakes.'' Mr. Kashio says. ''You don't have that problem with our version because there is plenty of space for the buttons.''

The other main feature is the power unit -- a solar cell that reacts to very low levels of light.

Other systems require a light intensity of 100 to 150 lux to be able to operate, while the Casio calculator needs only 50 lux -- ''which means you can do your sums in a dimly lit restaurant, for example,'' he adds.

The Kashio brothers have built up a powerful business empire which continues to be highly profitable even in the midst of a prolonged global economic recession.

The business is now spread over six product categories -- calculators, watches (particularly digital models), musical instruments, office and personal computors, and TV sets.

The big sales battle is now in the area of personal computers, particularly hand-held models not much bigger than ordinary pocket calculators.

Casio and another major Japanese manufacturer, Sharp, are engaged in a struggle for market share, bringing out a succession of new models at ever lower prices (in Casio's case down now to a little over $55).

It is also moving into another new product area: miniature television.

In June the company will begin marketing what is claimed to be the world's smallest pocket television, costing $210 initially.

It measures 80 (3.15 inches) by 118 (4.64 inches) millimeters, is 26 millimeters (1 inch) thick, and weighs 350 grams (12.25) ounces). As far as size is concerned, it is only half that of its nearest rival, a set developed by the Sony Corporation.

The breakthrough for pocket television was the replacemet of the conventional bulky tube with a liquid crystal display like that used in calculators and digital watches.

Both systems have a major drawback: A normal television screen does not show up well in strong sunlight, while the liquid crystal doesn't operate in the dark. This latter problem was eliminated in the Casio set by development of a special 'backlight'' system.

Why was it that a maker of calculators and watches, rather than one of the major television manufacturers, came up with such a product? ''We have considerable liquid-crystal and LSI technology which was essential in developing such a product,'' Mr. Kashio says.

Whenever we want to enter a new product area we only do so when we have a revolutionary technology to attract customers and win a good market share.''