Load cell for an electrical weighing scale

• US 5,929,391 A
• Filed: 05/02/1996
• Issued: 07/27/1999
• Est. Priority Date: 05/02/1996
• Status: Expired due to Fees

• Current Assignee: Measurement Specialties Limited (TE Connectivity Limited)
• Original Assignee: Measurement Specialties, Inc. (France) (TE Connectivity Limited)
• Inventors: Germanton, Damon, Petrucelli, Steven P.
• Primary Examiner(s): Gibson, Randy W.
• Application Number:
  US08/641,624
• Time in Patent Office: 1,181 Days
• Field of Search: 73/862.627, 73/862.632, 73/862.634, 73/862.637, 73/862.639, 177/211, 177/229, 177/DIG. 9
• US Class Current: 177/211
• CPC Class Codes: G01G 19/44 for weighing persons
• CPC Class Codes: G01G 21/23 Support or suspension of weighing platforms G01G21/24 takes precedence
• CPC Class Codes: G01G 3/08 wherein the weighing element is in the form of a leaf spring
• CPC Class Codes: G01G 3/13 having piezoelectric or piezoresistive properties

Abstract

A load cell for an electronic scale, which is capable of providing both load support and load measurement in a planar member. This is accomplished by configuring the load cell as a substantially flat circular plate having an E-shaped deflectable member defined therein. The E-shaped member includes three beams, at least one of which includes a sensor arrangement that responds to a load applied to the deflectable member by generating an electrical signal that is indicative of the load applied to the E-shaped member.

Claims

1. A load cell for an electronic scale, comprising:

a substantially flat plate having at least one C-shaped aperture, said at least one C-shaped aperture defining a substantially E-shaped deflectable member having three beams which form the arms of said substantially E-shaped deflectable member; and

sensor means disposed on at least one of said three beams, for generating an electrical signal in response to an applied load to said E-shaped deflectable member of said load cell, said electrical signal being indicative of the applied load;

wherein two of said beams each include a conical-shaped projection which concentrates said applied load to said E-shaped deflectable member.

2. The load cell according to claim 1, wherein said at least one C-shaped aperture comprises first and second C-shaped apertures, said second C-shaped aperture substantially surrounding said first C-shaped aperture.

3. The load cell according to claim 2, wherein said C-shaped apertures face toward one another other.

4. The load call according to claim 1, wherein said three beams includes two outer beams and one inner beam, said two projections being defined on said outer beams.

5. The load call of claim 1, wherein said three beams includes two outer beams and one inner beam, said sensor means being disposed on said inner beam.

6. The load cell according to claim 1, wherein said sensor means includes first and second strain gauges, wherein deflection of said E-shaped deflectable member places said first strain gauge into tension and said second strain gauge into compression.

7. The load cell according to claim 1, wherein said sensor means comprises at least one half bridge structure.

9. The scale according to claim 6, wherein said at least one C-shaped aperture comprises first and second C-shaped apertures, said second C-shaped aperture substantially surrounding said first C-shaped aperture.

10. The scale according to claim 9, wherein said C-shaped apertures face toward one another other.

8. An electronic scale for displaying the weight of a load applied to said scale, comprising:

a platform;

a plurality of support members attached to said platform for elevating said platform above a supporting surface, each of said support members supporting a portion of the load, wherein each of said support members includes a load cell having a substantially flat plate including at least one C-shaped aperture, said at least one C-shaped aperture defining a substantially E-shaped deflectable member having three beams which form the arms of said substantially E-shaped deflectable member, and sensor means disposed on at least one of said three beams, for generating an electrical signal in response to a load applied to said E-shaped deflectable member of said load cell, said electrical signal being indicative of the load; and

display means for receiving said electrical signals generated by said load cells in each of said support members and displaying the weight of the applied load;

wherein two of said beams each include a conical-shaped projection which concentrates said applied load to said E-shaped deflectable member.

11. The scale according to claim 8, wherein said three beams includes two outer beams and one inner beam, said two projections being defined on said outer beams and said sensor means being defined on said inner beam.

12. The scale according to claim 8, wherein said sensor means includes first and second strain gauges, wherein deflection of said E-shaped deflectable member places said first strain gauge into tension and said second strain gauge into compression.

13. The scale according to claim 8, wherein said sensor means comprises at least one half bridge structure.

14. A load cell for an electronic scale, comprising:

a substantially flat plate having a first C-shaped aperture and a second oppositely faced C-shaped aperture substantially surrounding said first aperture, said first C-shaped aperture defined by first and second portions of uniform width in parallel alignment along their entire length and a third portion perpendicular to said first and second portions and coupled at a first end to said first portion and at a second end to said second portion, said second C-shaped aperture defined by first and second portions of uniform width in parallel alignment along their entire length and a third portion perpendicular to said first and second portions and coupled at a first end to said first portion and at a second end to said second portion, defining an E-shaped deflectable member having three beams which form the arms of said E-shaped deflectable member, said three beams comprising two outer beams, each beam having a top surface of uniform width extending the entire length of said first and second portions of said first C-shaped aperture, and an inner beam, wherein said inner beam includes a conical shaped projection formed on a top surface of said inner beam which concentrates an applied load to said E-shaped deflectable member; and

sensor means disposed on said two outer beams for generating an electrical signal in response to a load applied to said E-shaped deflectable member of said load cell, said electrical signal being indicative of the applied load.