Tokyo Electric Co.

Kabushiki Kaisha Tec

Tohru Kitagawa

Yoshihisa Nishiyama

Seiji Suzuki

Yasuhiro Ushijima

Koichiro Sakamoto

Kohichiro Sakamoto

Sadao Ohyoshi

Hitoshi Nimura

Kazuo Watanabe

Takaharu Yamasita

Shuji Takabayashi

Takaharu Yamashita

A load cell unit in accordance with the present invention comprises a load cell and a wiring board. The load cell comprises a flexible member provided with a through hole formed between the fixed end and the moving end thereof so as to form four flexible portions, and strain gages attached to the flexible portions, respectively. The wiring board is provided with a circuit connected to the strain gages of the load cell so as to form a bridge circuit including the strain gages, and a processing circuit connected to the bridge circuit. The wiring board has a first major surface mounted with at least film capacitors among the circuit elements of the processing circuit, and a second major surface. A first shield cover is attached to the first major surface of the wiring board so as to cover the circuit elements mounted on the first major surface, and a second shield cover is attached to the second major surface of the wiring board so as to cover the circuit elements mounted on the second major surface of the wiring board. The wiring board is disposed beside the load cell with the first shield cover disposed in the through hole of the load cell. The wiring board of the load cell unit is shielded effectively and the load cell unit has a compact construction.

Load cell unit

A load cell comprises a distortion generating body including first and second arms each of which has a thickness y and which are arranged in parallel, and thin deformable portions of a thickness x, which are coupled to the two ends of each of the first and second arms and each of which has flat and curved surfaces facing each other, a height of the distortion generating body, a distance between both of the thin deformable portions coupled with both ends of each of the first and second arms, and a radius of curvature of the curved surface of the thin deformable portions being set to predetermined values H, D, and R, respectively, strain gauges insulatively formed on the flat surfaces of the thin deformable portions coupled with both ends of the first arm, and leading portions connecting the strain gauges to form a bridge circuit. The thickness y is given by a linear equation y=ax+b, and constants a and b are determined by a linear equation p=aq+b indicating the relation between thicknesses p and q with respect to a plurality of standard load cells each of which includes the distortion generating body having predetermined height H, predetermined distance D, and predetermined radius R. Each of the thin deformable portions has a thickness q and a thickness p of each of the first and second arms is set according to the thickness q to give a linear load weight-output voltage characteristic.

Load cell

A resistor-adjusting apparatus is provided for adjusting resistors of a load-cell scale which has a load cell, having a resistance bridge circuit, for generating an electrical signal corresponding to a load weight, and an A/D converting section for converting the electrical signal supplied from the load cell into a digital signal corresponding to the load weight. A thin-film resistor for adjusting temperature characteristic, which is connected to the bridge circuit, is provided on the load cell so as to be exposed. The resistor-adjusting apparatus comprises a resistor adjustor for removing part of the thin-film resistor in response to a control signal and thus adjusting a resistance thereof, and a control unit for supplying, to the resistor adjustor, a control signal corresponding to digital signals that are generated by the A/D converting section in response to a predetermined load weight at different temperatures, causing the resistor adjustor to change the resistance of the thin film resistor.

Method and apparatus for adjusting resistors in load-cell scale

A load cell type, weight-measuring device includes a load cell for generating an electrical signal corresponding to an applied weight, an analog-to-digital converting circuit for converting an output signal from the load cell to a digital data, and a data processing unit for generating weight data on the basis of output data from the A/D converting circuit. This weight-measuring device further has a memory in which data indicative of the temperature characteristic of the output signal of the load cell is stored, and a temperature sensor for detecting the temperature of the load cell and generating a corresponding output signal. The data processing unit corrects the output data from the A/D converting circuit on the basis of the output signal from the temperature sensor and the data in the memory.

Load cell type, weight-measuring device

A load cell and a method of correcting the same are provided wherein a beam member on which an insulator film is formed is prevented from being trimmed by a laser beam upon laser trimming thereof. The load cell comprises a span resistor member and a zero point resistor member both formed separately of the beam member and including a span temperature correcting thin film resistor and a zero point balance temperature correcting thin film resistor, respectively, each of which has a temperature coefficient and is formed on a substrate. The resistor members are applied to the insulator film on the beam member and the thin film resistors are connected to a bridge circuit. The thin film resistors are trimmed with a laser beam to correct the span temperature correcting thin film resistor and the zero point balance temperature correcting thin film resistor for temperature. The substrates intercept a laser beam upon laser trimming of the thin film resistors.

Load cell and temperature correction of the same

A load cell weighing apparatus includes a load cell having one end secured to a base, a receiving member secured to the other end of the load cell, and a load supporting member movable with respect to the base and receiving member, wherein a load to be weighed is applied to the load supporting member. Springs are provided between the load supporting member and receiving member for transmitting the load applied to the load supporting member to the receiving member, and a stopper cooperates with the base to define the full stroke of movement of the load supporting member.

Load cell weighing apparatus

A multi-range load cell weighing scale includes a load receiving pan provided at the top of a casing, a high-range load cell disposed in the casing for a high range of weight determination, and a low-range load cell disposed in the casing for a low range of weight determination in a substantially horizontally juxtaposed relation to the high-range load cell. The low-range load cell has one end connected to one end of the high-range load cell. The other end of the high-range load cell is supported on the bottom of the casing, while the other end of the low-range load cell defines a load support on which the pan is supported. The load to be weighed bears on the two load cells simultaneously. The scale enables a wide range of highly accurate weight determination, despite its use of inexpensive load cells.

Multi-range load cell weighing scale

A load cell has a span resistor hole for enclosing a span resistor that is provided on the beam body, so that the span resistor may be free from the influence of environmental factors such as temperature and moisture and thus can be satisfactorily protected. The span resistor hole is located in a deformation-proof portion of the beam body, whereby the span resistor is not exposed to external mechanical force.

A load cell has strain gage resistors, lead portions for connecting them in a bridge and compensating portions for the compensation of the bridge balance, span or the like, which are laminated as metal thin films by means of the thin film technique. A protection film is formed over the metal thin films and trimmed by laser beams, and the protection film is made of a pigmented protection film made of synthetic resin for easy and accurate trimming.

Load cell and method of compensating the same

A load cell has four strain gauge resistors formed through an insulation layer on the beam body having a strain generating section, a conductive pattern for forming a bridge circuit by coupling the strain gauge resistors compensation resistance sections for compensating the bridge balance and span of the bridge circuit is provided. A section of the conductive pattern except the section coupled to the strain gauge resistors is disposed at a position sufficiently isolated from the strain gauge resistors.

A load-cell balance having a parallelogram load cell body constituted by a stationary column, movable column and two arms connected between these columns, each arm having thin-walled flexible portions to which adhered are strain gauges. Each strain gauge is coated and sealed by a coating made of a material of butyl rubber group so as to be protected against moisture. The coating permits a free deflection of deflectable parts of the balance, even when the load is small, while maintaining a good moisture proof nature, so that the reliability of the balance is much enhanced.

Load-cell balance

A load-cell balance in which strain gauges are mounted on a recess portion of the flexible arms of the balance. The circuitry for the strain gauges is mounted on a printed circuit board which is fixed to the stationary portion of the balance and extends along the length of the flexible beams. An electrically shielding cover may be provided for the load balance, as well as compensating resistances.

A weighing scale with a load cell is disclosed. The load cell is integrally formed by casting and transmits only vertical motions to the strain gauges so tht moment forces induced by off center loads will not cause inaccurate readings. A stopper limits the movement of the load transmission section to prevent excessive beam movements and to prevent the pivot shaft from falling out of the cell. The gauge circuitry includes a temperature compensation circuit and is attached to one surface of the load cell. Blank or runner ribs are formed in the load cell during casting and are later removed by machining.

Weighing scale with load cell

An electronic weight measuring device comprises a load cell to produce a voltage signal corresponding to the weight of load applied, an amplifier circuit for amplifying the output signal of the load cell, an A/D converter circuit for converting the output signal of the amplifier circuit into a digital signal, a counter for counting the number of clock pulses corresponding to the output signal of the A/D converter circuit, a microcomputer for deriving a weight indicating signal from the count output signal of the counter, and a display unit for displaying the weight indicating signal from the microcomputer. The electronic weight measuring device further includes a bias circuit to apply a bias voltage to the amplifier circuit so as to reduce to a zero level the output signal produced from the amplifier circuit when it has received from the load cell an output signal corresponding to 1/2 of the rated weight, and the A/D converter circuit produces a digital output signal corresponding to the absolute value of a positive or negative output signal from the amplifier circuit.

Growing community of inventors

Mishima, Japan

Tohru Kitagawa