High resolution offset electronic weighing devices and methods

A high resolution enhanced capacity direct load electronic balance comprising:

• a frame having a permanent magnet and a fixed portion of a null sensor attached thereto, a first vertical guide channel defined at said frame;
• upper and lower support members articulatably connected with said frame;
• an armature structure connected with said upper and lower support members and including a pan mount, a movable portion of said null sensor, and a coil located adjacent to said permanent magnet, said armature structure including a first vertical spacer connected between said upper and lower support members, said spacer having a securement thereat;
• a push-pull servo system connected with said null sensor and said coil for selective adjustment of current to said coil responsive to signals from said null sensor;
• at least a first tension adjustable spring connected between said securement of said first vertical spacer of said armature structure and said frame to provide selective counterbalancing at said armature structure equivalent to about weight of said armature structure plus a portion of load capacity receivable at said pan mount of said armature structure, said spring having a substantially constant selected spring distension maintained during use by operation of said push-pull servo system;
• and
• a first spring tension adjuster having said spring connected therewith and including a guide slidable in said channel at said frame and releasably securable thereat.

A method for adapting a high resolution direct load electronic balance having a frame supporting a permanent magnet, a movable load displaceable support system carrying a coil articulatably connected with said frame, and a push-pull servo system connected with said coil and a null sensor, said adapting method to provide counterbalancing of up to about one-half of the balance's rated capacity to improve balance system performance, said method comprising the steps of:

• connecting at least one elastic member between the frame and the support system;
• selecting tension of said elastic member to provide counterbalancing at said support system equivalent to about weight of the movable support system plus a portion of load capacity receivable at said support system;
• and
• maintaining substantially constant selected elastic member distension during use by operation of said push-pull-servo system.

A method for enhancing weight measurement accuracy by a high resolution direct load electronic balance system having a frame with a load displaceable support system articulatably connected therewith, said method comprising the steps of:

• elastically associating the frame and the support system utilizing a spring;
• adjusting tension between the frame and the support system to provide a selected offset to balance system capacity equivalent to weight of said support system and up to about onehalf of load capacity receivable at said support system by selectively locating one end of said spring relative to a guide channel at the frame;
• and
• maintaining substantially constant spring distension during use by operation of a push-pull servo system including a coil at the load displaceable support system and a sensor.