Touch sensor using optical fiber

• US 20080047364A1
• Filed: 07/27/2007
• Published: 02/28/2008
• Est. Priority Date: 07/28/2006
• Status: Active Grant

• Current Assignee: Nitta Corporation
• Original Assignee: Nitta Corporation
• Inventors: Yoshida, Takashi, Kajimoto, Hiroyuki
• Granted Patent: US 7,444,887 B2
• Time in Patent Office: Days
• US Class Current: 73/862.51
• CPC Class Codes: G01L 1/24 by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
• CPC Class Codes: G06F 3/042 by opto-electronic means

Abstract

In a touch sensor, one ends of optical fibers are disposed at positions corresponding to respective pressure sensing points on a sensor sheet. The optical fibers in a bundled form are connected in a detection unit. The detection unit includes therein a camera that takes an image showing a change in luminance at the other ends of the optical fibers. A transmissive body is disposed to contain the other ends of the optical fibers and light sources. Upper and side faces of the transmissive body are covered with antireflection members. The transmissive body has substantially the same refractive index as the core of each optical fiber. A force applied to the sensor sheet is detected based on the change in luminance at the other ends of the optical fibers shown in the image taken by the camera.

Claims

1. A touch sensor using optical fibers, the sensor comprising:

an elastic member having thereon a plurality of pressure sensing points;

a plurality of optical fibers one ends of which are disposed at positions in the elastic member corresponding to the respective pressure sensing points, each optical fiber comprising a core and a clad surrounding the core;

a light source that emits lights toward the other ends of the plurality of optical fibers;

a transmissive body having substantially the same refractive index as the core and containing therein the other ends of the optical fibers and the light source;

an image-taking device that takes an image showing a change in luminance at the other ends of the plurality of optical fibers;

an antireflection member that prevents light reflection into the transmissive body at an end face of the transmissive body;

a light-shielding member that prevents incidence of external lights at an end face of the transmissive body; and

a force detecting system that detects a force applied to the elastic member, on the basis of the change in luminance at the other ends of the optical fibers shown in the image taken by the image-taking device.

2. The sensor according to claim 1, wherein the arrangement pattern of the other ends of the plurality of optical fibers is similar to the arrangement pattern of the plurality of pressure sensing points on the elastic member.