# US 12,003,235 B2 · Tactile sensor formed on polyimide thin film having high total light transmittance, and switching device using same

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- Number: US 12,003,235 B2
- Document ID: US12003235B2
- Status: Granted
- Kind: B2
- Application number: 17/613,647
- Filed: 2020-06-15
- Published: 2022-07-28
- Granted: 2024-06-04
- Earliest claimed: 2019-06-19
- Assignees: Mitsui Chemicals, Inc.
- Applicants: Mitsui Chemicals, Inc.
- Inventors: Jun Okabe; Tadahiro Sunaga; Shizuo Tokito; Tomohito Sekine
- Web page: https://patentgrep.com/patent/US12003235B2

## CPC

- H03K 17/964: {Piezoelectric touch switches}
- C08G 73/1082: {wholly aromatic in the tetracarboxylic moiety}
- C08J 7/042: {with two or more layers, where at least one layer of a composition contains a polymer binder}
- C09D 179/08: Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- G01L 1/16: using properties of piezoelectric devices
- H10N 30/302: {Sensors}
- H10N 30/706: {characterised by the underlying bases, e.g. substrates}
- H10N 30/802: {Circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits}
- H10N 30/857: Macromolecular compositions
- C08J 2379/08: Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08J 2427/16: Homopolymers or copolymers of vinylidene fluoride
- C08J 2465/00: Characterised by the use of macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain (C08J2407/00 - C08J2457/00, C08J2461/00 take precedence); Derivatives of such polymers
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

A light, flexible, and tough thin film having high total light transmittance that can be formed on various three dimensional shapes, and also provides a stably driven tactile sensor, which is an electronic device having the switching function thereof, is provided. The tactile sensor is formed on a polyimide thin film having high total light transmittance, thermal resistance, and a polar component of surface free energy with a specific value, and has a switching device that emits a voltage signal which, through an electronic circuit for controlling noise, stably drives another device. This tactile sensor has a curved or flat surface and has a first electrode, a ferroelectric layer, and a second electrode formed over the polyimide thin film. The switching device as a tactile sensor can drive another device merely by a light touch with a finger, and can be manufactured at a high non-defective rate.

## Claims

### Claim 1

A tactile sensor, comprising:
a first electrode printed on a surface of a polyimide thin film having a constituent unit represented by a general formula (1) below, the polyimide thin film having a glass transition temperature of 250° C. or higher and 310° C. or lower, a tensile strength of 250 MPa or less, an elongation rate of 30% or less, a total light transmittance of 80% or more, and a polar component of surface free energy in the range of 1.5 to 10 mJ/m2:
wherein X is at least one member selected from the group consisting of the following alicyclic groups:
and
wherein Y is at least one member selected from the group consisting of the following aromatic groups:
a ferroelectric layer printed so as to cover the first electrode; and
a second electrode printed so as to be superposed with the first electrode with the ferroelectric layer therebetween.

### Claim 2 (depends on 1)

The tactile sensor according to claim 1, wherein the polyimide thin film is formed on a surface of a support having Gaussian curvature of 0 cm−2.

### Claim 3 (depends on 1)

The tactile sensor according to claim 1, wherein the polyimide thin film is formed on a surface of a support having Gaussian curvature of 0.04 cm−2 or less in absolute value.

### Claim 4 (depends on 1)

The tactile sensor according to claim 1, wherein a non-defective product rate of the tactile sensor is 99.9% or higher.

### Claim 5 (depends on 1)

The tactile sensor according to claim 1, wherein:
the X in the general formula (1) is at least one member selected from the group consisting of the following alicyclic groups:

### Claim 6 (depends on 1)

The tactile sensor according to claim 1, wherein a main component of each of the first electrode and the second electrode is silver or a polythiophene-based conductive polymer.

### Claim 7 (depends on 1)

The tactile sensor according to claim 1, wherein an area of each of the first electrode and the second electrode is in the range of 1.0×10−2 to 15 cm2.

### Claim 8 (depends on 1)

The tactile sensor according to claim 1, wherein the ferroelectric layer contains a copolymer (P(VDF-TrFE)) consisting of vinylidene fluoride (VDF) and trifluoroethylene (TrFE) with a molar ratio in the range of 80/20 to 70/30.

### Claim 9 (depends on 1)

The tactile sensor according to claim 1, wherein either the first electrode or the second electrode is used as a ground electrode, and another one is connected to an electronic circuit for controlling noise.

### Claim 10 (depends on 1)

The tactile sensor according to claim 1, wherein an electronic circuit for controlling noise is an active-type low-pass filter.

### Claim 11 (depends on 1)

The tactile sensor according to claim 1, wherein an electronic circuit for controlling noise is a comparator.

### Claim 12 (depends on 1)

A switching device, wherein an electronic circuit for controlling noise is connected to the tactile sensor according to claim 1; and the switching device enhances to drive another device.

### Claim 13 (depends on 1)

A switching device, comprising:
the tactile sensor according to claim 1;
an electronic circuit for controlling noise connected to the tactile sensor; and
a toggle-flip-flop circuit connected to the electronic circuit, wherein
an on state and an off state of a voltage are switched by deformation of the ferroelectric layer caused by pressure, and
the switching device enhances to drive another device.

### Claim 14 (depends on 12)

The switching device according to claim 12, further comprising a sensuously recognizable unit for the on-state and the off-state of voltage.