JPH085476A - Load cell unit - Google Patents

Abstract

PURPOSE:To prevent the breakdown of a lead wire by forming a recessed part in the outer edge of a circuit substrate near the connecting terminal, and inserting a lead wire in this recessed part. CONSTITUTION:In a load cell scale 14, when a distortion is generated in a distortion exciting part of a load cell 4 in response to the weight of a material to be measured, which is placed on a receiver 6, a resistance value of a strain gauge 7, in which a distortion is generated with the distortion exciting part, is changed. Quantity of change of the analog output of this gauge 7 is converted into the digital value by an A/D converter 11 of a circuit substrate 15. At this stage, in the scale 14, a processing circuit such as a CPU receives the digital value output from the substrate 15 and performs computing so as to electrically compute the weight of the material to be measured. In the scale 14, the gauge 7 of the load cell 4 and a connecting terminal 9 of the substrate 15 are connected by a lead wire 10, but since this lead wire 10 is inserted into a recessed part 16 of the substrate 15, the generation of breakdown of the lead wire 10 due to the collision of fingers at the time of manufacture and maintenance can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load cell unit in which a circuit board is fixed substantially parallel to the outer surface of a load cell.

[0002]

2. Description of the Related Art At present, a load cell balance for calculating the weight of an article as electric data is put into practical use. This load cell scale is one in which a strain gauge connected in a bridge is attached to the straining part of a straining body to form a load cell, and the saucer is connected to the movable end of the load cell in which the fixed end is connected to the body housing of the load cell balance. Then, the strain amount generated in the load cell due to the weight of the articles loaded on the saucer is electrically measured with a strain gauge to perform the weighing. At this time, the processing circuit for calculating the measured value is
Generally, it is provided as a part of the load cell scale, but A / DC (Analog / Digital) of such a processing circuit
In some cases, a load cell unit is formed by fixing a circuit board such as a converter or an amplifier circuit to a load cell. By integrating the load cell and the processing circuit in this manner, individual differences in the output characteristics of the load cell can be corrected by the processing circuit, which can contribute to improvement in productivity.

A conventional example of such a load cell balance will be described below with reference to FIG. First, in the load cell balance 1, the saucer 6 is formed by interposing a support frame (not shown) to the movable end 5 of one load cell 4 whose fixed end 3 is connected to the main body base 2 which is a part of the main body housing.
Are connected to each other, and four strain gauges 7 are bridge-connected to the upper surface and the lower surface of the strain generating portion of the load cell 4.
Is attached. And these strain gauges 7
Is connected by a lead wire 10 to a connection terminal 9 formed of printed wiring (not shown) near the upper edge and the lower edge of a PWB (Printed Wiring Board) 8 which is a circuit board.
The connection terminal 9 is connected by a printed wiring to the A / DC 11 which is a part of the processing circuit mounted on the PWB 8.

The PWB 8 is fixed to the outer side surface of the fixed end 3 of the load cell 4 with a bolt 13 via a spacer 12, and the PWB 8 is positioned parallel to the side surface of the load cell 4. By doing so, the load cell unit is formed by the load cell 4 and the PWB 8. In the load cell balance 1, the strain gauge 7 is protected from moisture in the atmosphere by sealing the strain gauge 7 with a moistureproof agent (not shown) applied to the upper surface of the load cell 4.

With this configuration, in the load cell balance 1, when strain occurs in the strain-flexing portion of the load cell 4 corresponding to the weight of the weighing object (not shown) loaded on the tray 6, together with this strain-flexing portion. Since the resistance value of the strain gauge 7 that causes distortion changes, the amount of change in the analog output of the strain gauge 7 is converted into a digital value by the A / DC 11 of the PWB 8. Therefore, in the load cell balance 1, as described above, P
CPU (Central Process)
ing unit) and other processing circuits receive and perform arithmetic processing and the like to electrically calculate the weight of the weighing object.
Such a PWB 8 and the load cell 4 are integrated.

[0006]

In the above-mentioned load cell balance 1, since the PWB 8 and the load cell 4 are integrated, for example, the load cell 4 is integrated with a processing circuit for correcting individual differences to improve productivity. It is possible to improve and share this as a unit with various devices.

Here, in the load cell balance 1, the strain gauge 7 of the load cell 4 and the connection terminal 9 of the PWB 8 are connected by the lead wire 10. The lead wire 10 floats in the gap between the load cell 4 and the PWB 8. Therefore, for example, fingers or the like may collide and be broken during manufacturing or maintenance.

[0008]

[MEANS FOR SOLVING THE PROBLEMS] A strain gauge is provided on a strain-generating portion of a strain-generating body to form a load cell, and a circuit board is fixed substantially parallel to an outer surface continuous from a fixed end to a movable end of the load cell. A connection terminal is formed on a surface of the circuit board that does not face the load cell, and in the load cell unit in which the strain gauge is connected to the connection terminal by a lead wire, a recess is formed in the outer edge portion of the circuit board in the vicinity of the connection terminal. The lead wire was inserted into the recess.

[0009]

By inserting the lead wire into the concave portion of the outer edge portion of the circuit board, it is possible to prevent the finger or the like from colliding with the lead wire connecting the load cell and the circuit board.

[0010]

An embodiment of the present invention will be described below with reference to FIG. Regarding the load cell balance 14 illustrated in the present embodiment, the same parts as those of the load cell balance 1 described above as a conventional example use the same names and reference numerals, and detailed description thereof will be omitted.

First, in the load cell balance 14, a strain gauge 7 is provided on the upper and lower surfaces of the load cell 4 in which the fixed end 3 is connected to the main body base 2 and the tray 6 is connected to the movable end 5.
Is attached to the side surface, which is the outer surface of the fixed end 3 of the load cell 4, in parallel with the bolt 1 via the spacer 12.
The PWB 15, which is a circuit board, is fixed at 3, and the PWB 15 and the load cell 4 form a load cell unit.

In the PWB 15, three connecting terminals 9 are formed by printed wiring (not shown) near the upper edge and near the lower edge, and the upper edge is located above and below the connecting terminals 9. A concave portion 16 is formed in the portion and the lower edge portion. Therefore, in the load cell balance 14, the strain gauge 7 is connected to the connection terminal 9 of the PWB 15 by the lead wire 10. The lead wire 10 is connected to the load cell 4 by the lead wire 10.
By inserting the recess 16 from the upper surface to the side surface, the strain gauge 7 communicates with the connection terminal 9 of the PWB 15.

In the load cell balance 14, the strain gauge 7 is protected from moisture in the atmosphere by sealing the strain gauge 7 with a moistureproof agent (not shown) applied to the upper surface of the load cell 4.

In the load cell scale 14 having such a structure, when strain occurs in the strain-flexing portion of the load cell 4 in accordance with the weight of a weighing object (not shown) loaded on the tray 6, the load-cell weighing scale 14 together with the strain-flexing portion. Since the resistance value of the strain gauge 7 that causes distortion changes, the amount of change in the analog output of the strain gauge 7 is converted into a digital value by the A / DC 11 of the PWB 15. Therefore, in the load cell scale 14, the processing circuit such as the CPU receives the digital value output from the PWB 15 as described above, and the arithmetic processing is performed to electrically calculate the weight of the weighing object. .. Further, in the load cell balance 14, since the PWB 15 and the load cell 4 are integrated, for example, a processing circuit for correcting individual difference is integrated into the load cell 4 to improve productivity, This can be shared by various devices as a unit.

In the load cell balance 14, the strain gauge 7 of the load cell 4 and the connection terminal 9 of the PWB 15 are connected.
And the lead wire 10 are connected.
Since it is inserted into the recess 16 of the PWB 15, breakage due to collision of fingers during manufacturing or maintenance is prevented.

[0016]

As described above, the present invention forms a load cell by providing a strain gauge in the strain generating portion of the strain generating body, and the circuit board is made substantially parallel to the outer surface continuous from the fixed end to the movable end of the load cell. In a load cell unit that is fixed and has a connection terminal formed on the surface of the circuit board that does not face the load cell, and the strain gauge is connected to the connection terminal by a lead wire, in the vicinity of the connection terminal at the outer edge of the circuit board. By forming a concave portion and inserting the lead wire into the concave portion, fingers or the like do not collide with the lead wire connecting the strain gauge of the load cell and the connection terminal of the circuit board. It has effects such as prevention.

[Brief description of drawings]

FIG. 1 is an exploded perspective view illustrating a load cell balance according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view illustrating a conventional load cell balance.

[Explanation of symbols]

 3 Fixed End 4 Load Cell 5 Movable End 7 Strain Gauge 9 Connection Terminal 10 Lead Wire 15 Circuit Board 16 Recess

Claims (1)

[Claims] 1. A strain gauge is provided at a strain-causing portion of a strain-generating body to form a load cell, and a circuit board is fixed substantially parallel to an outer surface continuous from a fixed end of the load cell to a movable end. In a load cell unit in which a connection terminal is formed on a surface not facing the load cell, and the strain gauge is connected to the connection terminal by a lead wire, a concave portion is formed in the outer edge portion of the circuit board in the vicinity of the connection terminal, and the concave portion is formed in the concave portion. A load cell unit having the lead wire inserted therethrough.