JP2018132531A - Strain gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an increase in sensitivity and a reduction in size in a strain gauge which has a resistor formed on a flexible base material.SOLUTION: A strain gauge includes: a flexible base material; and a resistor formed of a thin film containing at least one of Cr and CrN.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a strain gauge.

  There is known a strain gauge that is attached to a measurement object and detects the strain of the measurement object. The strain gauge includes a resistor for detecting strain, and a material containing Cr (chromium) or Ni (nickel) is used as the resistor material, for example. The resistor is formed on a base material made of an insulating resin, for example (see, for example, Patent Document 1).

JP 2006-74934 A

  However, the conventional strain gauge has insufficient sensitivity, and has not been able to be downsized, so that high sensitivity and downsizing have been demanded.

  This invention is made | formed in view of said point, and aims at implement | achieving high sensitivity and size reduction in the strain gauge which has a resistor formed on the base material which has flexibility.

  This strain gauge has a flexible substrate and a resistor formed of a thin film containing at least one of Cr and CrN.

  According to the disclosed technology, it is possible to achieve high sensitivity and downsizing in a strain gauge having a resistor formed on a flexible substrate.

It is a top view which illustrates the strain gauge which concerns on 1st Embodiment. It is sectional drawing which illustrates the strain gauge which concerns on 1st Embodiment.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

<First Embodiment>
FIG. 1 is a plan view illustrating a strain gauge according to the first embodiment. FIG. 2 is a cross-sectional view illustrating the strain gauge according to the first embodiment, and shows a cross section taken along the line AA of FIG. Referring to FIGS. 1 and 2, the strain gauge 1 includes a base material 10, a resistor 30, and a terminal portion 41.

  In the present embodiment, for the sake of convenience, in the strain gauge 1, the side of the substrate 10 on which the resistor 30 is provided is the upper side or one side, and the side on which the resistor 30 is not provided is the lower side or the other side. Let it be the side. In addition, the surface of each part where the resistor 30 is provided is referred to as one surface or upper surface, and the surface where the resistor 30 is not provided is referred to as the other surface or lower surface. However, the strain gauge 1 can be used upside down, or can be arranged at an arbitrary angle. Moreover, planar view refers to viewing the object from the normal direction of the upper surface 10a of the base material 10, and planar shape refers to the shape of the object viewed from the normal direction of the upper surface 10a of the base material 10. And

  The base material 10 is a member that becomes a base layer for forming the resistor 30, and has flexibility. There is no restriction | limiting in particular in the thickness of the base material 10, According to the objective, it can select suitably.

  The base material 10 can be formed from insulating resin films, such as PI (polyimide) resin, for example. The film refers to a member having flexibility.

  Here, “forming from an insulating resin film” does not prevent the base material 10 from containing additives, impurities, and the like in the insulating resin film.

  The resistor 30 is a thin film formed in a predetermined pattern on the upper surface 10a of the substrate 10, and is a sensitive part that undergoes strain and causes a resistance change. The resistor 30 may be directly formed on the upper surface 10a of the substrate 10 or may be formed on the upper surface 10a of the substrate 10 via another layer. The thickness of the resistor 30 is not particularly limited and can be appropriately selected depending on the purpose. In FIG. 1, for convenience, the resistor 30 is shown in a satin pattern.

  The resistor 30 can be formed from, for example, a material containing Cr (chromium). Examples of the material containing Cr include a thin film containing at least one of Cr and CrN.

  The terminal portion 41 extends from both ends of the resistor 30 and is formed wider than the resistor 30 in plan view. The terminal portion 41 is a pair of electrodes for outputting a change in the resistance value of the resistor 30 caused by strain to the outside. For example, a lead wire for external connection is joined. The resistor 30 extends, for example, in a zigzag manner from one of the terminal portions 41 and is connected to the other terminal portion 41. In addition, although the resistor 30 and the terminal part 41 are set as another code | symbol for convenience, both can be integrally formed by the same material in the same process.

  In the strain gauge 1, when PI resin is used as the material of the base material 10 and a thin film containing at least one of Cr and CrN is used as the material of the resistor 30, high sensitivity (500% or more compared to the conventional) and small size are achieved. (1/10 or less compared with the conventional technology) can be realized.

  For example, the output of the conventional strain gauge is about 0.04 mV / 2V, whereas the strain gauge 1 can obtain an output of 0.3 mV / 2V or more. In addition, the size of the conventional strain gauge (gauge length × gauge width) was about 3 mm × 3 mm, whereas the size of the strain gauge 1 (gauge length × gauge width) was 0.3 mm × 0.3 mm. It can be reduced in size.

  The strain gauge is generally used by being attached to a strain generating body (metal or the like). Since the conventional strain gauge has low sensitivity, the material selection of the strain generating body has been limited by design in order to ensure sensor characteristics.

  On the other hand, the strain gauge 1 is more sensitive than the conventional strain gauge, so the design restrictions as in the case of using the conventional strain gauge can be greatly relaxed, and the material selection of the strain generating body can be made. Can be improved.

  Further, since the strain gauge 1 is smaller than the conventional strain gauge, the strain gauge 1 can be installed at a fine measurement location that could not be used until now.

  Further, since the strain gauge 1 is a flexible film type gauge, it can be produced and supplied not only in a small size but also in various sizes.

  In addition, the strain gauge 1 is light in weight and can be affixed to a location where measurement is desired. Compared to MEMS (Micro Electro Mechanical Systems) sensors that require mounting on an electronic board for similar measurements, There is an advantage that you can directly measure the place you want to measure.

  Further, since the strain gauge 1 is very small and the mass can be ignored, there is no influence of inertia, and the strain gauge 1 is excellent in sensitivity, stability, and fatigue life.

  In addition, the strain gauge 1 can also be self-temperature compensated. In this case, the strain gauge 1 can be used for any object to be measured having various thermal expansion coefficients regardless of metal or plastic.

  Moreover, since the strain gauge 1 has high sensitivity and can detect a small displacement, it can also be used for an object to be measured having high rigidity.

<Second Embodiment>
In the second embodiment, an example of a sensor using a strain gauge is shown. In the second embodiment, description of the same components as those of the already described embodiments may be omitted.

  Since the strain gauge 1 has various features such as high sensitivity and downsizing as shown in the first embodiment, it can be used for various sensors. The application examples of the strain gauge 1 are listed below. However, the following is an example of a sensor to which the strain gauge 1 is applied, and is not limited to these.

  The strain gauge 1 can be used for a mobile wearable product, for example. By using the strain gauge 1 for mobile wearable products, it is possible to contribute to the realization of mobile wearable products that are smaller and save space. Specifically, the strain gauge 1 can be applied to, for example, a switch capable of multi-step sensing depending on the strength of the touched force. By mounting this switch on, for example, mobile wearable products that are becoming smaller and more multifunctional, it is possible to switch between multiple functions with a single switch. Further, the strain gauge 1 can be applied to a sensor for detecting biological information by being attached to, for example, a belt part or a back cover part of a watch.

  In addition, the strain gauge 1 is a touch sensor that senses a fine force like a fingertip or a delicate hand movement like a craftsman's skill in robotics, and realizes a smooth movement close to human movement. It can be applied to. For example, when the strain gauge 1 is attached to a joint, arm, finger, or the like of a robot to detect torque, a touch sensor with little displacement, quick movement, and high sensitivity can be realized.

  Further, the strain gauge 1 can flexibly cope with in-vehicle use and the like. For example, the present invention can be applied to a sensor that detects a force applied to a brake pedal or a brake pad by attaching the strain gauge 1 to a brake pedal or a brake pad. The strain gauge 1 can be applied to a car navigation switch, a console switch, a steering switch, and the like. Further, it is possible to realize a haptic device (such as a car navigation system) including the strain gauge 1, the display, and the vibration motor. The strain gauge 1 can be applied to a sensor that is attached to a crank or pedal of a bicycle and detects a force applied to the crank or pedal.

  Further, the strain gauge 1 can be applied to a wide range of other areas and can contribute to sensing in the IoT era. For example, the strain gauge 1 can be applied to displacement detection of an input device (touch pad, pointing device, mouse, etc.). The strain gauge 1 is mounted on a pen (for example, a stylus pen) and can be applied to a writing pressure sensor. The strain gauge 1 can also be mounted on a smartphone. For example, the present invention can be applied to a touch sensor attached to the inside of a liquid crystal of a smartphone or a grip sensor attached to both sides of a smartphone.

  The preferred embodiments and the like have been described in detail above, but the present invention is not limited to the above-described embodiments and the like, and various modifications can be made to the above-described embodiments and the like without departing from the scope described in the claims. Variations and substitutions can be added.

1 strain gauge, 10 base material, 10a top surface, 30 resistor, 41 terminal

Claims (9)

A flexible substrate;
And a resistor formed from a thin film containing at least one of Cr and CrN.   A mobile wearable product comprising the strain gauge according to claim 1.   A switch comprising the strain gauge according to claim 1.   A biological information detection sensor comprising the strain gauge according to claim 1.   A robot comprising the strain gauge according to claim 1.   A vehicle-mounted force detection sensor comprising the strain gauge according to claim 1.   An input device comprising the strain gauge according to claim 1.   A pen comprising the strain gauge according to claim 1.   A smartphone provided with the strain gauge according to claim 1.

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