JPS5979103A - strain sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a strain sensor used in electronic scales and the like.

[Technical background of the invention and its problems] Conventionally, in strain sensors, strain gauge elements are bonded to the thin deformed portion of the beam body with adhesive, and then wired to each other using lead wires to complete the strain sensor circuit. There is. and,
When temperature compensation is required, adjustment is performed after temperature sensors are installed on the beam body and wired to each other using lead wires. However, in such a conventional method, the manufacturing process is complicated and the characteristics tend to be unstable.

There is a strain sensor in which a thin film resistor circuit is patterned on one surface of a beam body using thin film technology.

However, as shown in FIG. 1, the pattern of the strain gauge resistors R1°R21R3+R4 is formed only on the negative side of the beam body (1), so it has the disadvantage that it is difficult to obtain a highly accurate pattern. In other words, when we look at the load-output voltage characteristics when loads are applied to Wl, W2, and W3 in Figure 1, we find that Figure 2 (excellent cLI) (0
), and as a result, the linearity of load-output voltage changes depending on the load position.

[Purpose of the invention]

The present invention has been developed in view of these points, and focuses on the fact that arranging strain gauge resistors on multiple surfaces of the entire beam body is advantageous for increasing precision, and by using thin film technology. The object is to obtain a strain sensor that is easy to manufacture and easy to adjust.

[Summary of the invention]

The present invention forms all thin film resistance circuits on multiple surfaces of the beam body,
By connecting with lead wires to form the entire strain sensor circuit, it is possible to simplify and improve accuracy.At this time, since the adjustable resistance adjustment circuit is concentrated on one side of the beam body, The structure is such that adjustment work can be easily carried out.

[Embodiment of the Invention] An embodiment of the present invention will be described based on FIGS. 3 to 10. First, the beam body (2) is a metal elastic body, such as stainless steel 5US630 or high strength aluminum A221.
It is formed by machining an 8-pole, etc., and the upper and lower pattern forming surfaces (2A) (2B) are polished flat. In addition, the holes (4) (5) are connected by the groove (3).
) The beam body (2) has a thin deformed part (61 (7)
(8) (9) are formed. And the beam body (
There is a thin deformed portion (6) on the pattern forming surface (2^) of 2).
(7) Strain gauge resistor R1, R located above
A thin film resistance circuit is formed by the lead patterns 2 and all these connected lead patterns. - force, patterned surface (2
B) A thin film resistance circuit is formed also below by thin-walled deformed parts (8) and (9) the strain gauge resistors R3+R4O located below and the lead plates L that connect them. Further, on the pattern forming surface (2A), a resistance adjustment circuit is also provided using balance adjustment resistors r1+r2 for a bridge circuit constituted by a temperature compensation resistor R8 and strain gauge resistors R1 to R4 each having an adjustable structure. , according to lead pattern L! Ill are connected appropriately.

Here, the temperature compensating resistor R8 and the parallel adjusting resistor Tl+r2 are arranged outside the fixed part of the beam body (2), that is, the thin deformed parts (6) and (7). In addition, the terminal parts Tl to T4, which are connected to the external circuit part and the shoes with lead wires, are connected to the beam body (
2) is formed only on the pattern formation surface (two people) side.

Then, the circuit on the pattern forming surface (2 people) side and the circuit on the pattern forming surface (2B) side are connected to a predetermined lead notch turn L.
Connection points α, /r, c, a',
Lead wire (10 people) (Ion) (1
0o), a strain sensor circuit α as shown in FIG. 5 is formed.

In such a configuration, FIG. 6 shows how the strain sensor deforms when a load W is applied to it. That is, the strain gauge resistor R1 located in the thin deformed portion (6) (9)
, R4 undergoes tensile υ strain and its resistance value increases, and conversely, the strain gauge resistors R2, R, located in the thin-walled deformed parts (7) and (8) undergo compressive strain and their resistance value decreases. ,
The strain sensor circuit shown in Fig. 5 below 0η, strain amount, input voltage V
An output voltage VO proportional to e is generated. In this way, the strain gauge resistors R1-R4 have multiple pattern formation surfaces (
2A) and (2B), it has high precision, and its manufacture is easy using the thin film method described later. At this time, the temperature compensation resistor Rs and the balance adjustment resistor rl
, r2 are arranged outside the thin-walled deformed portions (6) and (7), so they are not affected by strain. Moreover, although the strain gauge resistors R1 to R4 are arranged on a plurality of pattern-forming surfaces (2A) (211', ) in this way, the temperature-compensating resistor Rs and the balance adjustment resistors r1+r2 are arranged on the pattern-forming surface. (2 people) are placed in the middle of the day, making adjustment work easier. That is, the terminal portions T1 to T4
While detecting the output voltage Vo by applying a probe to the temperature compensation resistor Rs and balance adjustment resistor rI+r2,
For example, the 7th part can be trimmed with a laser beam.
Figures (O) and (T) show an example of trimming of the temperature compensation resistor R8 and the balance adjustment resistor rt (t or rz). In this case, the centrally arranged temperature compensation resistor R8 and balance adjustment resistor rl t r2 can be trimmed at the same time, and the adjustment process can be greatly simplified. Further, since the terminal portions Tl to T4 are on the same surface, it is easy to apply the probe, and from this point as well, the adjustment work is further facilitated. Further, soldering of the lead wires to the terminal portions Tsu to T4 can be easily performed on the same surface.

By the way, the method for manufacturing such a strain sensor is described in Part 8.
This is shown in Figures 1 to 10. First, after polishing the pattern forming surfaces (2A) and (2B) of the beam body (2) flatly,
Clean and degrease. After the beam body (2) is completely immersed in a face-shaped polyimide resin liquid whose viscosity is adjusted to 1000 ep, it is pulled up at a pulling speed of 3 cm/lnm to uniformly coat the surface of the beam body (2) with polyimide resin. Coat the liquid. Next, after drying at 100°C for 1 hour,
A polyimide resin layer (2) with a thickness of 4 μm is formed by heating and curing at 20° C. for 1 hour. Next, the beam body (
2) Pattern formation surface (2A) (2B) NiCrSi layer (19, l/
11 layers 04) and 2μ Cu layer θ9 are sequentially laminated. Then, photoetching was performed to remove the Cu layer (11v) outside the pattern area.

The T1 layer α→ and the Nlcrsi layer (to) are etched with respective etchants to obtain a pattern f as shown in FIG. 9(cL). At this time, the polyimide resin layer vr is exposed in areas other than the pattern portion. Furthermore, the strain gauge resistor R1rR2 is
The Cu layer (l
Figure 9 (4) after etching with ewoCu etchant.
You will get a pattern like the one shown. Through this process, the Ti layer (b) is exposed at a predetermined portion of υ, and the temperature compensation resistor Rs, which is a laminate of NiCrSi/Ti, is completed.
The lead pattern L, which is a laminate of NiCrSi/Ti/Cu, and the terminal portion TI-Ta are completed. Next, the strain gauge resistors R1 and R2, and the balance adjustment resistor rl.

Figure 9 (0
) to obtain a pattern as shown. This allows NiC
A strain gauge resistor RI+R2 and a balance adjustment resistor rl J r2 made of a single layer of rSi layer (2) are completed. Further, a pattern is formed on the pattern forming surface (2B) side by a similar process. After forming such a pattern, connect points a, ne, c, tL' as shown in FIG.
, 枦, G/All lead lines (] 00 people (IOB) (100)
By soldering and connecting, the strain sensor circuit (11) is completed. Then, a temperature compensation resistor R8, a balance adjustment resistor r1. The strain sensor is completed by laser rimming so that r2 has a predetermined resistance value. Note that in order to improve reliability, these pattern parts may be further coated with polyimide resin.

〔Effect of the invention〕

In the present invention, as described above, the entire thin film resistor circuit is formed on multiple surfaces of the beam body, and the entire Φ sensor circuit is formed by reversely connecting with the lead wire. In this case, the adjustable resistance adjustment circuits are all concentrated on one side of the beam body, making it easy to adjust the resistance on the same surface.Furthermore, since the terminals are also placed on the same surface, the adjustment work is easier than ever. The soldering of the lead wires can also be made easier, and at this time, the influence of distortion can be eliminated by locating the resistance adjustment circuit and the terminal (terminal part) outside the thin deformed part. It is possible.

[Brief explanation of the drawing]

Fig. 1 is a side view showing a conventional example, Fig. 2 (tL) to (G)
3 is a perspective view showing an embodiment of the present invention, FIG. 4 is an explanatory diagram showing a developed diagram, FIG. 5 is a circuit diagram, FIG. 6 is a side view, and FIG. Figure 7 is an explanatory diagram, Figure 8 is a longitudinal side view, Figures 9 (α) to (0) are plan views showing the etching process, and Figure 10 is a cross-sectional view taken along line X-X' of Figure 9 (0). be. 2... Beam body, 2 people ~ 2B... Pattern shape 19.
m, IOA~Zoo...Lead wire, 11...Strain sensor circuit amount Applicant Tokyo Electric Co., Ltd. 6 Figure ((1')

Claims (1)

[Claims] 1 Thin film resistance circuits are formed on multiple surfaces of a beam body, adjustable resistance adjustment circuits are concentrated on one surface, and these thin film resistance circuits are connected by lead wires to form a strain sensor circuit. A strain sensor characterized by the following: 2 All thin film resistance circuits are formed on multiple surfaces of the beam body, and an adjustable resistance adjustment circuit and a terminal section for connection to an external circuit section are centrally arranged on one surface, and these thin film resistance circuits are connected by lead wires. A strain sensor characterized by forming a strain sensor circuit. 3. The strain sensor according to claim 2, wherein the resistance adjustment circuit and the terminal portion are arranged outside the thin deformed portion of the beam body.