Gemscale 50 - A Scale and its Technology

(June 1995)

Gemscale 50 is a compact, portable, self calibrating, digital carat scale. It is small enough to fit into a pocket and capable of accurately measuring up to 50.50 carats in .01 increments. The scale is designed for one handed operation. One button turns the scale on, calibrates, tares and turns the scale off.

The research, development and the fundamental technological innovations which have gone into this scale since its conception are responsible for the success of Gemscale 50.

The technologies in all other existing digital carat scales require a parallelogram linkage to correct for off-center loading. Force motor and strain gauge technologies present major obstacles to reducing the size and weight of existing portable scales. The patented capacitance ceramic sensor and The Self Adjusting Technology developed by John Borchard at Dendritics has eliminated the need for a parallelogram linkage. Off center loading errors, non level surfaces and ambient temperature changes are electronically corrected in this technology by the custom microprocessor. This technology allows scales to be made thinner, lighter and less expensively than existing scales. We believe that this technology will replace strain gauge as the dominant technology in digital consumer scales. The Self Adjusting Technology developed at Dendritics is the only new basic weighing technology to be developed in many years.

The Self Adjusting Technology is also accurate. This scale measures to 0.0015 carats and then rounds off for the displayed reading. This weighing system utilizes an air gap between two plates to provide nearly optimum vibration damping, allowing the weight to settle in milliseconds. If for any reason the data has been corrupted or the battery is low the scale will not progress to a bad reading. Resolutions to 1:20,000 are possible. Scales with 100 carat capacity and scales with 0.001 resolution are on the drawing board.

The load cell utilized in this Self Adjusting Technology is low power. Battery longevity was greatly improved by the elimination of nearly all analog circuitry, reducing power consumption from 1200 mW to 17 mW, a factor of 70.The scale will operate for 200 hours on a standard 9V Heavy Duty battery and 300 hours on a 9V Alkaline. The scale is equipped with an automatic shut off which enables the battery to be saved. There is no need for an AC adaptor making it most suitable for portable use.

Ease of operation, reading stability, portability and battery longevity. The technological innovations in these areas add up to the smallest digital gem scale in the world: fits in a pocket, takes 10 seconds from pocket to first reading is self contained, and has a standard battery lasting 300 operating hours. This is the way a portable instrument should be.