Sensing system

• US 7,689,381 B2
• Filed: 10/10/2008
• Issued: 03/30/2010
• Est. Priority Date: 07/10/2008
• Status: Active Grant

• Current Assignee: PixArt Imaging Incorporated
• Original Assignee: PixArt Imaging Incorporated
• Inventors: Lin, Cho-Yi, Cheng, Hsin-Chi
• Primary Examiner(s): Bui; Bryan
• Application Number:
  US12/249,222
• Publication Number:
  US 20100010773A1
• Time in Patent Office: 536 Days
• Field of Search: 702150-153, 345/157, 345/158, 345/173, 382/312, 178/18.09
• US Class Current: 702/151
• CPC Class Codes: G06F 3/0428 by sensing at the edges of the touch surface the interruption of optical paths, e.g. an illumination plane, parallel to the touch surface which may be virtual sensing beam interruptions in a planar beam grid of an optical touch-screen G06F3/0421

Abstract

A sensing system is adapted to sense a pointer and calculate a location of the pointer. The sensing system includes a panel, a reflective element, an image sensor and a processor connected to the image sensor. The panel has a first plane and a first area located at the first plane. The first area is quadrangular and has a first boundary, a second boundary, a third boundary and a fourth boundary connected in order. The reflective element is disposed at the first boundary and located on the first plane. A second plane of the reflective element which is a reflective plane is substantially perpendicular to the first plane and mirrors the first area to form a second area. The image sensor sensing the first and the second areas is disposed at a corner at which the third boundary and the fourth boundary intersects and located on the first plane.

Claims

1. A sensing system adapted to sense a pointer and calculate a location of the pointer, comprising:

a panel having a first plane and a first area located at the first plane, the first area being quadrangular and having a first boundary, a second boundary, a third boundary and a fourth boundary which are connected in order;

a reflective element disposed at the first boundary and located on the first plane, the reflective element having a second plane substantially perpendicular to the first plane, the second plane being a reflective plane and mirroring the first area to form a second area;

an image sensor disposed at a corner at which the third boundary and the fourth boundary intersects and located on the first plane, a sensing range of the image sensor covering the first area and the second area; and

a processor electrically connected to the image sensor;

wherein when the pointer approaches the first area and the pointer is mirrored by the reflective element to form a first mirror image such that the pointer and the first mirror image is in the sensing range of the image sensor and when a portion of the pointer adjacent to the first area, a portion of the first mirror image adjacent to the second area and the image sensor are not colinear, the image sensor senses the pointer and the first mirror image and the processor calculates the location of the pointer.

2. The sensing system as claimed in claim 1, wherein the image sensor senses the pointer along a first sensing path and senses the first mirror image along a second sensing path, and the processor calculates the location of the pointer according to the first sensing path and the second sensing path.

3. The sensing system as claimed in claim 2, wherein the first area is a rectangle.

4. The sensing system as claimed in claim 3, wherein the processor has information about a first distance “

D1”

from the first boundary to the third boundary, and the processor calculates the location of the pointer by the steps of;

determining a first angle “

A1”

between the first sensing path and the third boundary;

determining a second angle “

A2”

between the second sensing path and the third boundary; and

calculating a second distance “

D2”

from the pointer to the fourth boundary by means of dividing the double of D1 by the sum of tan A1 and tan A2.

5. The sensing system as claimed in claim 3, further comprising:

a first linear light source disposed at the second boundary and located on the first plane, the first linear light source being mirrored by the reflective element to form a second mirror image; and

a second linear light source disposed at the third boundary and located on the first plane, the second linear light source being mirrored by the reflective element to form a third mirror image, the fourth boundary being mirrored by the reflective element to form a fourth mirror image;

the reflective element, the first linear light source, the second linear light source and the fourth boundary surrounding the first area;

the reflective element, the second mirror image, the third mirror image and the fourth mirror image surrounding the second area; and

the first linear light source, the second mirror image and the third mirror image being in the sensing range of the image sensor.

6. The sensing system as claimed in claim 2, wherein the first area is quadrangular and not a rectangle.

7. The sensing system as claimed in claim 6, wherein the processor has information about a first distance “

D3”

from the first boundary to a first imaginary line passing through the corner and being parallel to the first boundary, and the processor calculates the location of the pointer by the steps of;

determining a first angle “

A3”

between the first sensing path and the first imaginary line;

determining a second angle “

A4”

between the second sensing path and the first imaginary line; and

calculating a second distance “

D4”

from the pointer to a second imaginary line passing through the corner and being perpendicular to the first boundary by means of dividing the double of D3 by the sum of tan A3 and tan A4.

8. The sensing system as claimed in claim 6, further comprising:

a first linear light source disposed at the second boundary and located on the first plane, the first linear light source being mirrored by the reflective element to form a second mirror image;

a second linear light source disposed at the third boundary and located on the first plane, the second linear light source being mirrored by the reflective element to form a third mirror image; and

a third linear light source disposed at the fourth boundary and located on the first plane, the third linear light source being mirrored by the reflective element to form a fourth mirror image;

the reflective element, the first linear light source, the second linear light source and the third linear light source surrounding the first area;

the reflective element, the second mirror image, the third mirror image and the fourth mirror image surrounding the second area; and

the first linear light source, the second mirror image, the third mirror image and the fourth mirror image being in the sensing range of the image sensor.

9. The sensing system as claimed in claim 1, wherein when the pointer approaches the first area and the pointer is mirrored by the reflective element to form the first mirror image such that the pointer and the first mirror image are in the sensing range of the image sensor and when a portion of the pointer adjacent to the first area, a portion of the first mirror image adjacent to the second area and the image sensor are colinear, the image sensor senses a size of pointer along a third sensing path, the processor has information about a relationship between the size of the pointer at the third sensing path and a length of a third distance “

D5”

from the pointer to the corner and the processor calculates the location of the pointer based on the size of the pointer.

10. The sensing system as claimed in claim 1, further comprising a first light source located above the first plane and outside the first area, the first light source being mirrored by the reflective element to form a second mirror image, the first light source and the second mirror image being located outside the sensing range of the image sensor, the pointer having a reflective surface, the first light source being adapted to emit invisible light, the first mirror image being formed by means of the first light source illumining the reflective surface of the pointer.

11. The sensing system as claimed in claim 1, wherein the pointer has a light emitting device, and the first mirror image is formed by means of light emitted from the light emitting device.