The Research On New-Type Portable Electronic Scales

The development of the modern society has put forward higher request on weighing technology. The desk-top electronic scales have been great application in commercial trade, but they have many shortcomings such as large volume, high cost, AC supply power and not covenience to carry, so they are restricted to use. The usual portable scales are lever scales which are mostly used by residents, and spring balance which measure through compression or drawing of spring. They are being rejected for their big measuring errors. People have been expecting cheap portable electronic scales which can measure accurately and be carried conveniently for many years.This thesis designs new-type portable electronic scales. It discusses the instrumental working principle, and introduces its error sources and how to distribute the error. And, the instrumental circuit, software-flow-chart and engineering designing technology are presented. Because capacitance weighing sensor is of bad non-linearity, the author put forward and set up a maths model to revise non-linearity, which establishes the theory basis for the instrument to measure accurately and be low-cost.The portable electronic scales consist of power, weighing sensor, microchip, keyboard/switch, LCD and etc. Its technical indictors include 10kg maximal measuring range, 10g division value, III precision, 1.5V work voltage. Its technical indictors refer to the indictors of the electriconic measuring tools of most popularity in the markets and of large output at home and board, so the instrument is strengthened the competitive power after putting on markets. It possesses many intelligent functions, such as shelling, lack-of-power display, overload alarm, unit price enactement, accumulation computation, self-calibrating and etc. It can "sleep" automatically in five minutes if it is not measuring.New-type portable electronic scales can measure mass rapidly and accurately and communicate value. Furthermore, it is small, simply structured, easy to operate and convenient to carry. The instrument is able to meet the needs of commercial trade and residents, so its application has a bright future.