JPH0431534Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field This invention relates to a strain gauge that electrically extracts the strain that appears when an external force is applied to an object.

(b) Conventional technology In general, a strain gauge is attached to an object to be measured, a bridge circuit is constructed with this strain gauge as one side, and changes in the resistance value of the strain gauge due to strain on the object to be measured are electrically extracted. Measure. The strain gauges used here are often called foil gauges, and are made by bonding linear resistance foil in a predetermined pattern with directionality onto a resin film base, with lead wires taken out from both ends. Furthermore, when it is desired to increase the sensitivity, compensate for the temperature, or averagely measure the strain of the object to be measured, it is common to attach a plurality of strain gauges. and,
In order to meet such uses, a multi-axis type that integrates a plurality of strain gauges is also commercially available.

(c) Problems to be Solved by the Invention The strain gauge described in (b) has a resistive foil formed into a precision fine line pattern, so there is a risk of damage even if an object slightly touches the surface. Furthermore, multi-axis strain gauges have more complex patterns, which exacerbates the above problem. This multi-axis strain gauge has a shape in which multiple strain gauges are assembled in advance, so not only are the measurement directions limited, but conditions such as temperature compensation tend to be unstable. It was hot. In addition, since the resistive foil pattern is formed into a thin line, the output voltage fluctuates due to the generation of Joule heat, making it difficult to increase the input voltage and output.

(d) Means for solving the problem) An insulating base, a sheet-shaped electrical resistance structure bonded to this base, and three or more lead wire extraction terminals provided at predetermined positions on the surface of this resistance structure. A voltage detection circuit is configured by a plurality of inter-terminal resistances obtained.

(e) Effect: It is attached to the surface of the object to be measured, and the expansion and contraction of the electrical resistance structure due to the strain causes a change in the resistance value between each lead wire extraction terminal. Then, a voltage output is obtained from a voltage detection circuit which is constituted by a resistor between each lead wire drawing terminal and to which a voltage is applied in advance.

(F) Embodiment This invention will be described below with reference to an embodiment shown in FIGS. 1 to 3. In the figure, reference numeral 1 denotes an insulating base made of a square insulating resin film such as FESTER, and on the upper surface of this insulating base 1, an electrically resistive structure formed in a sheet shape, such as a square conductive resin sheet 2, is fused. They are worn together and become one. On the surface of the conductive resin sheet 2, three or more terminals for drawing out lead wires 3, 4, 5, and 6 are provided at predetermined positions, for example, near each corner. Here, the conductive resin sheet 2 has inter-terminal resistances 7, 8, 9, and 10 that exhibit the same resistance value between the lead wire extraction terminals 3-4, 4-5, 5-6, and 6-3.
is doing. As a result, a voltage detection circuit (bridge circuit) 16 shown in FIG. 3 is constructed.
That is, inter-terminal resistors 7, 8, 9, and 10 are inserted on each side of the voltage detection circuit (bridge circuit) 16. A predetermined voltage is applied between lead wire extraction terminals 3 and 5 via lead wires 11 and 12, and lead wires 13 and 14 are applied between lead wire extraction terminals 4 and 6. An indicator (not shown) is connected via the terminal. 15 is an object to be measured.

Next, the measurement conditions when using the strain gauge according to the present invention will be explained. An adhesive is applied to the lower surface of the insulating base 1 and it is attached to the surface of the object to be measured 15. Then, a predetermined voltage is applied between the lead wire extraction terminals 3-5 via the lead wires 11 and 12, and the lead wire 1 is applied between the lead wire extraction terminals 4-6.
An indicator (not shown) is connected via 3 and 14.
In this state, since the resistance values of the inter-terminal resistors 7, 8, 9, and 10 are the same, the voltage output circuit (bridge circuit) 16 is balanced and no output voltage is generated. Eventually, when the object to be measured 15 is distorted in the direction shown by the arrow in FIG.
The resistance values of 8, 9, and 10 change, and a voltage output is generated between the lead wire drawing terminals 4 and 6, which are output terminals. Then, a voltage output related to the amount of strain in the object to be measured 15, that is, the difference between the longitudinal strain and the lateral strain, is supplied to the indicator via the lead wires 13 and 14.

In the above embodiment, the electrical resistance structure is made of a conductive resin sheet, but according to this invention, the electrical resistance structure may be made of metal or semiconductor. Furthermore, the resistance between the terminals of the electric resistance structure was provided at four locations, and the four-bridge method was used. According to this idea, it is sufficient to form multiple sets of terminal resistance for drawing out the lead wires, and therefore, the resistance between the terminals can be reduced. There is no problem in configuring a bridge circuit by providing two or four or more locations. Even if the electrical resistance structure is constructed in the form of a mesh sheet, this does not deviate from the spirit of the present invention.

(g) Effects The conventional configuration of a multi-axis gauge or a configuration of a combination of multiple gauges has been changed to a single sheet-shaped electrical resistance structure by changing the position of the terminal resistance for leading wires. This can be easily achieved by simply setting (arranging the terminal for drawing out the lead wire). As a result, sensitization and temperature compensation can be carried out at low cost using a 2-gauge method, a 4-gauge method, etc., and it is also resistant to surface damage, and various conditions such as temperature compensation are stabilized. Furthermore, since a sheet-shaped electrical resistance structure is used instead of a linear resistance foil as in the past, any measurement direction line can be obtained as long as many lead wire extraction terminals are provided, and the heat dissipation effect is increased, so depending on the resistance value of the electrical resistance structure, high output can be obtained by applying a high voltage. In addition, it does not require a complicated pattern and therefore can be miniaturized very easily, which has practical effects.

[Brief explanation of the drawing]

The drawing shows an example of this invention.
FIG. 1 is a perspective view, FIG. 2 is a vertical sectional view showing the state of use, and FIG. 3 is an explanatory diagram of the voltage detection circuit. DESCRIPTION OF SYMBOLS 1... Insulating base, 2... Electric resistance structure (conductive resin sheet), 3, 4, 5, 6... Lead wire extraction terminal, 16... Voltage detection circuit (bridge circuit).

Claims (1)

[Scope of utility model registration request] It consists of an insulating base, a sheet-shaped electrical resistance structure bonded to this base, and three or more terminals for drawing out lead wires provided at predetermined positions on the surface of this resistance structure. A strain gauge characterized by comprising a voltage detection circuit.