Pressure sensitive element and a stylus pen with pressure sensitive function

• US 5,633,471 A
• Filed: 02/22/1995
• Issued: 05/27/1997
• Est. Priority Date: 01/13/1995
• Status: Expired due to Term

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Wacom Co Limited (Wacom)
• Inventors: Fukushima, Yasuyuki
• Primary Examiner(s): Dougherty, Elizabeth L.
• Assistant Examiner(s): BIEGEL, RONALD L
• Application Number:
  US08/392,307
• Time in Patent Office: 825 Days
• Field of Search: 73/862.041, 73/862.541, 73/865.4, 364/709.11
• US Class Current: 73/865.4
• CPC Class Codes: G01L 1/20 by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids of piezo-resistive materials G01L1/18; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
• CPC Class Codes: G06F 3/03545 Pens or stylus

Abstract

A pressure sensitive element is arranged around a core unit along the longitudinal axis of a stylus pen (10) to detect the pressure applied to the core unit. The pressure sensitive element comprises a pressure transmittable member (30b), in an annular plate shape, for transmitting the pressure applied in the axial direction of the pressure sensitive element, a pressure sensitive member (28), in an annular plate shape, arranged coaxially in parallel to the pressure transmittable member, and a support member (18b) for supporting the pressure sensitive member between the support member against the applied pressure, arranged coaxially in parallel to the pressure transmittable member. The core unit is a push and thrust type writing unit (14).

Claims

1. A pressure sensitive element formed substantially in a disk shape comprising:

a pressure sensitive member, in an annular plate shape,

a pressure transmitting member, in an annular plate shape, for transmitting pressure applied in the axial direction of the pressure sensitive element;

the pressure sensitive member being arranged coaxially with the pressure transmitting member along the axial direction; and

a support member for supporting the pressure sensitive member, the pressure sensitive member being between the support member and the pressure transmitting member, and being arranged coaxially with the pressure transmittable member along the axial direction,

the electrode having an annular plate shape,

the variable resistor being made of pressure sensitive conductive rubber,

the pressure sensitive conductive rubber including non-conductive elastomer, fine carbon spherical particles having a diameter of 1 to 20 μ

m and hollow elastic microspheres having a diameter of 10 to 150 μ

m, which particles and microspheres are both dispersed in the elastomer.

2. The pressure sensitive element as set forth in claim 1, wherein the above described non-conductive elastomer is composed of liquid silicone rubber and silicone adhesive consisting of silicone crude rubber and silicone varnish, or consisting mainly of silicone crude rubber and silicone varnish.

3. The pressure sensitive element as set forth in claim 1, wherein the hollow elastic microspheres include shells made of copolymer of vinylidene chloride and acrylonitrile.

4. An stylus pen comprising:

a pen holder having a substantially cylindrical shape;

a core unit arranged in the axial direction of the pen holder; and

a pressure sensitive element for detecting the pressure applied to the point of the core unit in the longitudinal axial direction of the core unit, which includes a pressure transmitting member, in an annular plate shape to surround the core unit, for transmitting applied pressure;

a pressure sensitive member, in an annular plate shape to surround the core unit, arranged coaxially with the pressure transmitting member along the axial direction; and

a support member in an annular plate shape to surround the core unit, for supporting the pressure sensitive member, the pressure sensitive member being between the support member and the pressure transmitting member and being arranged coaxially with the pressure transmittable member along the axial direction,

the pressure sensitive disk being a variable resistor,

the variable resistor being a pressure sensitive conductive rubber,

the pressure sensitive conductive rubber including non-conductive elastomer, fine carbon spherical particles having a diameter of 1 to 20 μ

m and hollow elastic microspheres having a diameter of 10 to 150 μ

m, which particles and microspheres are both dispersed in the elastomer.

5. The stylus pen as set forth in claim 4, wherein the above described non-conductive elastomer is composed of liquid silicone rubber and silicone adhesive consisting of silicone crude rubber and silicone varnish, or consisting mainly of silicone crude rubber and silicone varnish.

6. The stylus pen as set forth in claim 4, wherein the hollow elastic microsphere includes shells made of copolymer of vinylidene chloride and acrylonitrile.

7. A stylus pen comprising:

a pen holder having a substantially cylindrical shape;

a push and thrust type writing unit, arranged in the axial direction of the pen holder so as to penetrate the holder;

a support member for supporting the writing unit against the push pressure applied by a knock motion through the rear end of the writing unit; and

a pressure sensitive element for detecting the pressure applied to the point of the writing unit in the longitudinal axial direction of the writing unit, which includes;

a pressure transmitting member, in an annular plate shape to surround the writing unit, for transmitting applied pressure;

a pressure sensitive member, in an annular plate shape to surround the writing unit, arranged coaxially with the pressure transmitting member along the axial direction; and

a support member in an annular plate shape to surround the writing unit, for supporting the pressure sensitive member, he pressure sensitive member being between the support member and the pressure transmitting member and being arranged coaxially with the pressure transmittable member along the axial direction,

the pressure sensitive disk being a variable resistor,

the variable resistor being a pressure sensitive conductive rubber,

the pressure sensitive conductive rubber including non-conductive elastomer, fine carbon spherical particles having a diameter of 1 to 20 μ

m and hollow elastic microspheres having a diameter of 10 to 150 μ

m, which particles and microspheres are both dispersed in the elastomer.

8. The stylus pen as set forth in claim 7, wherein the above described non-conductive elastomer is composed of liquid silicone rubber and silicone adhesive consisting of silicone crude rubber and silicone varnish, or consisting mainly of silicone crude rubber and silicone varnish.

9. The stylus pen as set forth in claim 7, wherein the hollow elastic microsphere include shells made of copolymer of vinylidene chloride and acrylonitrile.