U.S. patent application number 13/525258 was filed with the patent office on 2013-03-07 for optical touch panel system, optical apparatus and positioning method thereof.
This patent application is currently assigned to PixArt Imaging Incorporation. The applicant listed for this patent is Ming-Tsan Kao, Chi-Chieh Liao, Chih-Hsin Lin, Tzung-Min Su. Invention is credited to Ming-Tsan Kao, Chi-Chieh Liao, Chih-Hsin Lin, Tzung-Min Su.
Application Number | 20130057517 13/525258 |
Document ID | / |
Family ID | 47752774 |
Filed Date | 2013-03-07 |
United States Patent
Application |
20130057517 |
Kind Code |
A1 |
Kao; Ming-Tsan ; et
al. |
March 7, 2013 |
Optical Touch Panel System, Optical Apparatus and Positioning
Method Thereof
Abstract
The present invention discloses an optical touch panel system
and a positioning method for positioning an object in a touch
control area. The system includes: at least two reflective elements
respectively disposed on a first side and a second side of the
touch control area, wherein the sum of lengths of the first side
and the second side is larger than the sum of lengths of the two
reflective elements; two lighting elements respectively disposed on
a third side and a fourth side of the touch control area; an image
sensor forming projected images by capturing an image of the object
and at least one mirror image of the object formed by the two
reflective elements; and a processor calculating the coordinates of
the object according to geometric information of the projected
images.
Inventors: |
Kao; Ming-Tsan; (Hsin-Chu,
TW) ; Liao; Chi-Chieh; (Hsin-Chu, TW) ; Lin;
Chih-Hsin; (Hsin-Chu, TW) ; Su; Tzung-Min;
(Hsin-Chu, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kao; Ming-Tsan
Liao; Chi-Chieh
Lin; Chih-Hsin
Su; Tzung-Min |
Hsin-Chu
Hsin-Chu
Hsin-Chu
Hsin-Chu |
|
TW
TW
TW
TW |
|
|
Assignee: |
PixArt Imaging
Incorporation,
|
Family ID: |
47752774 |
Appl. No.: |
13/525258 |
Filed: |
June 15, 2012 |
Current U.S.
Class: |
345/175 |
Current CPC
Class: |
G06F 3/0428 20130101;
G06F 3/042 20130101 |
Class at
Publication: |
345/175 |
International
Class: |
G06F 3/042 20060101
G06F003/042 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 1, 2011 |
TW |
100131581 |
Claims
1. An optical touch panel system, for positioning an object in a
touch control area, the system comprising: at least two reflective
elements respectively disposed on a first side and a second side of
the touch control area, wherein the first side and the second side
are adjacent to each other, and wherein the sum of lengths of the
first side and the second side is larger than the sum of lengths of
the two reflective elements; two lighting elements respectively
disposed on a third side and a fourth side of the touch control
area, wherein the third side and the fourth side are adjacent to
each other; an image sensor capturing an image of the object to
form a projected object image and at least one mirror image of the
object formed by the two reflective elements to form at least one
projected mirror image; and a processor calculating coordinates of
the object according to geometric information of at least two of
the projected object image and the at least one projected mirror
image.
2. The optical touch panel system of claim 1, wherein the geometric
information includes centers, gravity centers, representative
positions, or borders of the projected object image and the
projected mirror image.
3. The optical touch panel system of claim 1, further comprising
two lighting elements respectively disposed on the first side and
the second side, and wherein the two reflective elements are
adjacent to each other.
4. The optical touch panel system of claim 3, wherein an included
angle between the two reflective elements is larger than
90.degree..
5. The optical touch panel system of claim 3, wherein the two
lighting elements disposed on the first side and the second side
are respectively adjacent to the two lighting elements disposed on
the third side and the fourth side.
6. The optical touch panel system of claim 1, wherein the
reflective element disposed on the first side occupies the whole
first side, and the reflective element disposed on the second side
occupies a middle portion of the second side.
7. The optical touch panel system of claim 6, wherein the lighting
element disposed on the fourth side occupies a portion of the
fourth side, and is adjacent to the reflective element disposed on
the first side.
8. The optical touch panel system of claim 6, further comprising
two lighting elements disposed on two ends of the second side.
9. The optical touch panel system of claim 1, wherein the processor
selects any two of the projected object image and the at least one
projected mirror image which are non-overlapping with any other or
selects an overlapping image of the projected object image and the
at least one projected mirror image according to the total number
of the projected object image and the at least one projected mirror
image, wherein an overlapping projected image counts one, and
calculates the coordinates of the object according to the geometric
information of the selected non-overlapping projected images or
selected overlapping projected image.
10. A positioning method of an optical touch panel system, wherein
an image sensor of the optical touch panel system forms projected
images including a projected object image by capturing an image of
an object in a touch control area and a plurality of projected
mirror images by capturing a plurality of mirror images of the
object formed by at least two reflective elements, the method
comprising: checking a total number of the projected images,
wherein if any two of the projected object image and the projected
mirror images overlap with each other, the overlapping projected
image counts one; selecting any two of the projected images and
obtaining coordinates of the object according to geometric
information of the two selected projected images if the number is
larger than or equal to 4; selecting two of the projected images
which are non-overlapping with any other and obtaining coordinates
of the object according to geometric information of the two
selected projected images if the number is equal to 3; and
selecting the overlapping projected image formed by the projected
object image overlapping with one or more projected mirror images
and obtaining coordinates of the object according to borders or
sides of the overlapping projected image if the number is smaller
than 3.
11. The positioning method of an optical touch panel system of
claim 10, wherein the two reflective elements are respectively
disposed on two adjacent sides of the touch control area and the
sum of lengths of the two sides is larger than the sum of lengths
of the two reflective elements.
12. The positioning method of an optical touch panel system of
claim 11, wherein an included angle between the two reflective
elements is larger than 90.degree..
13. The positioning method of an optical touch panel system of
claim 11, wherein at least one lighting element is disposed on at
least one of the two sides.
14. The positioning method of an optical touch panel system of
claim 10, wherein the geometric information includes centers,
gravity centers, or representative positions of the projected
images.
15. The positioning method of an optical touch panel system of
claim 10, wherein the brightness of the projected images is smaller
than the brightness of a background in an image-sensing window of
the image sensor.
16. An optical touch panel system, for positioning an object in a
touch control area, comprising: at least two reflective elements
respectively disposed on a first side and a second side of the
touch control area, wherein the first side and the second side are
adjacent to each other, and wherein an included angle between the
two reflective elements is larger than 90.degree.; two lighting
elements respectively disposed on a third side and a fourth side of
the touch control area, wherein the third side and the fourth side
are adjacent to each other; an image sensor capturing an image of
the object to form a projected object image and at least one mirror
image of the object formed by the at least two reflective elements
to form at least one projected mirror image; and a processor
calculating the coordinates of the object according to geometric
information of at least two of the projected object image and the
at least one projected mirror image.
17. The optical touch panel system of claim 16, wherein the
geometric information includes centers, gravity centers,
representative positions, or borders of the object image and the
mirror image.
18. The optical touch panel system of claim 16, wherein the
processor selects any two of the projected object image and the at
least one projected mirror image which are non-overlapping with any
other or selects an overlapping image of the projected object image
and the at least one projected mirror image according to the total
number of the projected object image and the at least one projected
mirror image, wherein an overlapping projected image counts one,
and calculates the coordinates of the object according to the
geometric information of the selected non-overlapping projected
images or selected overlapping projected image.
19. An optical apparatus of an optical touch panel system, for
positioning an object in a touch control area, comprising: a first
reflective element disposed on a first side of the touch control
area; a second reflective element disposed on a second side of the
touch control area and occupies a middle portion thereof, wherein
the first side and the second side are adjacent to each other; a
first lighting element disposed on a third side of the touch
control area; a second lighting element disposed on a fourth side
of the touch control area and adjacent to the first side, wherein
the third side and the fourth side are adjacent to each other; and
a third lighting element and a fourth lighting element disposed on
the second side, wherein the fourth and third lighting elements are
respectively adjacent to the first side and the third side; wherein
the second reflective element is between the fourth and third
lighting elements.
20. An optical touch panel system, for positioning an object in a
touch control area, the touch control area including a first side,
a second side, a third side, and fourth side adjacent to each other
in the listed order, the system comprising: an image sensor
disposed at the corner between the third side and the fourth side;
a lighting unit disposed on the fourth side and occupies a portion
thereof which is adjacent to the first side; and a reflective unit
disposed on the second side and occupies a middle portion thereof;
wherein the image sensor captures a mirror image formed by the
reflective unit reflecting light from the lighting unit.
21. The optical touch panel system of claim 20, further comprising:
a reflective element disposed on the first side; a lighting element
disposed on the third side; and a first assistant lighting element
and a second assistant lighting element disposed on the second
side, wherein the first and second assistant lighting elements are
respectively adjacent to the first side and the third side; wherein
the reflective unit is between the first and second assistant
lighting elements.
Description
CROSS REFERENCE
[0001] The present invention claims priority to TW 100131581, filed
on Sep. 1, 2011.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] The present invention relates to an optical touch panel
system, an optical apparatus and a positioning method thereof, in
particular to such optical touch panel system and positioning
method which utilize plural reflective elements to resolve the
problem of blind zones.
[0004] 2. Description of Related Art
[0005] Touch screen is an interactive apparatus for users to
directly and intuitively operate application software on the
screen. There are various types of touch screens, one of which is
the optical touch panel.
[0006] FIG. 1 shows a prior art optical touch panel system 1, which
is disclosed by U.S. Pat. No. 4,782,328. As shown in FIG. 1, the
optical touch panel system 1 comprises two sensors 11 for capturing
images of an object 13 on a touch control area 12. A processor 14
is coupled to the two sensors 11; it analyzes the images generated
by the sensors 11 to determine the sensing paths 15 linking the
object 13 to the two sensors 11. The processor 14 calculates the
coordinate of the object 13 according to the sensing paths 15.
Because the optical touch panel system 1 requires two sensors 11,
the cost is relatively high.
[0007] FIG. 2 shows another prior art optical touch panel system 2
which is disclosed by Taiwanese Patent Publication No. 201003477
(counterpart U.S. Pat. No. 7,689,381 B2). The optical touch panel
system 2 comprises a mirror 21, two light sources 22, an image
sensor 23 and a processor 24. The mirror 21 and the two light
sources 22 are located at the periphery of a touch control area 28.
The mirror 21 reflects the object 25 to generate a mirror image 26.
The image sensor 23 captures the real image of the object 25 and
the mirror image 26. The processor 24 analyzes the sensing paths 27
passing the real image of the object 25 and the mirror image 26,
and calculates the coordinate of the object 25 according to the two
sensing paths 27. The optical touch panel system 2 only needs one
image sensor 23, so the cost is reduced.
[0008] In the optical touch panel system 2, when the two sensing
paths 27 are too close to each other, the real image of the object
25 and the mirror image 26 overlap with each other, and the
position of the object 25 cannot be obtained. As shown in FIG. 2,
when the object 25 is in the region of the touch control area 28
near the side where no light source is provided, the precise
position of the object cannot be detected because the real image of
the object and the mirror image will overlap. This region is called
the blind zone.
[0009] To resolve the problem of the blind zone, Taiwanese
Invention Patent Application No. 098131423 (FIG. 10 of U.S. Patent
Publication No. 2010/0309169 also discloses a similar apparatus)
provides an optical touch control apparatus, as shown in FIG. 3.
The optical touch control apparatus 100a comprises a lighting
device 120, an image detection module 130, two light guide bars
(112a, 112b), and two stripe-like mirrors (114a, 114b). The light
guide bars (112a, 112b) are close to each other, and the
stripe-like mirrors (114a, 114b) are close to each other. The light
guide bars (112a, 112b) and the stripe-like mirrors (114a, 114b)
are disposed around the four sides of a rectangle. The inside area
of the rectangle is a sensing area 116. The light guide module 110a
includes two stripe-like mirrors (114a, 114b), so each point being
touched in the sensing area 116 generates three mirror images. The
image detection module 130 captures the real image of the object B
and the mirror images B1-B3, and calculates the position of the
object B according to these images. The area of the blind zone 150a
in the optical touch control apparatus 100a is reduced, but the
problem of the blind zone still exists. That is, the dark images of
B and B1 partially overlap with each other and the dark images of
B2 and B3 partially overlap with each other. In addition, infinite
reflection occurs in the neighborhood of the corner between the two
stripe-like mirrors (114a, 114b).
[0010] In view of above, the present invention overcomes the
foregoing drawbacks by providing an optical touch panel system and
a positioning method which utilize plural reflective elements to
resolve the problem of blind zones. Furthermore, the infinite
reflection does not occur.
SUMMARY OF THE INVENTION
[0011] An objective of the present invention is to provide an
optical touch panel system for resolving the problem of blind
zones.
[0012] Another objective of the present invention is to provide a
positioning method of an optical touch panel system.
[0013] To achieve the foregoing objectives, in one aspect, the
present invention provides an optical touch panel system, for
positioning an object in a touch control area, the system
comprising: at least two reflective elements respectively disposed
on a first side and a second side of the touch control area,
wherein the first side and the second side are adjacent to each
other, and wherein the sum of lengths of the first side and the
second side is larger than the sum of lengths of the two reflective
elements; two lighting elements respectively disposed on a third
side and a fourth side of the touch control area, wherein the third
side and the fourth side are adjacent to each other; an image
sensor capturing an image of the object to form a projected object
image and at least one mirror image of the object formed by the two
reflective elements to form at least one projected mirror image;
and a processor calculating coordinates of the object according to
geometric information of at least two of the projected object image
and the at least one projected mirror image.
[0014] In one embodiment, the geometric information includes
centers, gravity centers, representative positions, or borders of
the projected object image and the projected mirror image.
[0015] In one embodiment, the two reflective elements are adjacent
to each other, and the optical touch panel system further comprises
two lighting elements respectively disposed on the first side and
the second side. The two lighting elements disposed on the first
side and the second side are respectively adjacent to the two
lighting elements disposed on the third side and the fourth
side.
[0016] In one embodiment, the reflective element disposed on the
first side occupies the whole first side, and the reflective
element disposed on the second side occupies a middle portion of
the second side. The lighting element disposed on the fourth side
occupies a portion of the fourth side, and is adjacent to the
reflective element disposed on the first side.
[0017] In one embodiment, the processor selects any two of the
projected object image and the at least one projected mirror image
which are non-overlapping with any other or selects an overlapping
image of the projected object image and the at least one projected
mirror image according to the total number of the projected object
image and the at least one projected mirror image, wherein an
overlapping projected image counts one, and calculates the
coordinates of the object according to the geometric information of
the selected non-overlapping projected images or selected
overlapping projected image.
[0018] In yet another aspect, the present invention provides a
positioning method of an optical touch panel system, wherein an
image sensor of the optical touch panel system forms projected
images including a projected object image by capturing an image of
an object in a touch control area and a plurality of projected
mirror images by capturing a plurality of mirror images of the
object formed by at least two reflective elements, the method
comprising: checking a total number of the projected images,
wherein if any two of the projected object image and the projected
mirror images overlap with each other, the overlapping projected
image counts one; selecting any two of the projected images and
obtaining coordinates of the object according to geometric
information of the two selected projected images if the number is
larger than or equal to 4; selecting two of the projected images
which are non-overlapping with any other and obtaining coordinates
of the object according to geometric information of the two
selected projected images if the number is equal to 3; and
selecting the overlapping projected image formed by the projected
object image overlapping with one or more projected mirror images
and obtaining coordinates of the object according to borders or
sides of the overlapping projected image if the number is smaller
than 3.
[0019] In yet another aspect, the present invention provides an
optical touch panel system, for positioning an object in a touch
control area, comprising: at least two reflective elements
respectively disposed on a first side and a second side of the
touch control area, wherein the first side and the second side are
adjacent to each other, and wherein an included angle between the
two reflective elements is larger than 90.degree.; two lighting
elements respectively disposed on a third side and a fourth side of
the touch control area, wherein the third side and the fourth side
are adjacent to each other; an image sensor capturing an image of
the object to form a projected object image and at least one mirror
image of the object formed by the at least two reflective elements
to form at least one projected mirror image; and a processor
calculating the coordinates of the object according to geometric
information of at least two of the projected object image and the
at least one projected mirror image.
[0020] In yet another aspect, the present invention provides an
optical apparatus of an optical touch panel system, for positioning
an object in a touch control area, the optical apparatus
comprising: a first reflective element disposed on a first side of
the touch control area; a second reflective element disposed on a
second side of the touch control area and occupies a middle portion
thereof, wherein the first side and the second side are adjacent to
each other; a first lighting element disposed on a third side of
the touch control area; a second lighting element disposed on a
fourth side of the touch control area and adjacent to the first
side, wherein the third side and the fourth side are adjacent to
each other; and a third lighting element and a fourth lighting
element disposed on the second side, wherein the fourth and third
lighting elements are respectively adjacent to the first side and
the third side; wherein the second reflective element is between
the fourth and third lighting elements.
[0021] In yet another aspect, the present invention provides an
optical touch panel system for positioning an object in a touch
control area, the touch control area including a first side, a
second side, a third side, and fourth side adjacent to each other
in the listed order, the system comprising: an image sensor
disposed at the corner between the third side and the fourth side;
a lighting unit disposed on the fourth side and occupies a portion
thereof which is adjacent to the first side; and a reflective unit
disposed on the second side and occupies a middle portion thereof;
wherein the image sensor captures a mirror image formed by the
reflective unit reflecting light from the lighting unit.
[0022] The objectives, technical details, features, and effects of
the present invention will be better understood with regard to the
detailed description of the embodiments below, with reference to
the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 shows a prior art optical touch panel system.
[0024] FIG. 2 shows another prior art optical touch panel
system.
[0025] FIG. 3 shows yet another prior art optical touch panel
system.
[0026] FIG. 4 shows a schematic diagram illustrating an embodiment
of an optical touch panel system of the present invention.
[0027] FIG. 5 shows that the optical touch panel system of FIG. 4
captures a picture through the sensing paths passing the
object.
[0028] FIG. 6 shows a schematic diagram of the image-sensing window
of the image sensor in FIG. 5.
[0029] FIG. 7 shows a schematic diagram illustrating another
embodiment of an optical touch panel system of the present
invention.
[0030] FIG. 8 shows that the optical touch panel system of FIG. 7
captures a picture through the sensing paths passing the
object.
[0031] FIG. 9 shows a schematic diagram of the image-sensing window
of the image sensor in FIG. 8.
[0032] FIG. 10 shows a schematic diagram illustrating another
embodiment of an optical touch panel system of the present
invention.
[0033] FIG. 11 shows a flow chart illustrating a positioning method
of the optical touch panel system of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0034] FIG. 4 shows a schematic diagram illustrating an embodiment
of an optical touch panel system of the present invention. When an
object 45 (e.g. a finger or a stylus pen) touches the touch control
areas 48 of an optical touch panel system 4, the system is able to
calculate the coordinate of the object 45, that is, to position it.
The optical touch panel system 4 comprises first and second
reflective elements (411 and 412), first to fourth lighting
elements (421-424), an image sensor 43 and a processor 44. The
first reflective element 411 and the second reflective element 412
are respectively disposed on the first side 481 and the second side
482 of the touch control area 48, wherein the first and second
sides 481 and 482 are adjacent to each other. The first and second
lighting elements (421 and 422) are respectively disposed on the
third side 483 and the fourth side 484 of the touch control area
48, wherein the third and fourth sides 483 and 484 are adjacent to
each other. The reflective element 411 and the second reflective
element 412 may each be, but not limited to, a plane mirror. The
first to fourth lighting elements 421-424 may each be a linear
light source capable of emitting invisible light. The image sensor
43 includes an image-sensing window and preferably a filter.
[0035] In this embodiment, the third lighting element 423 is
disposed between the first reflective element 411 and the second
lighting element 422, whereby the image sensor 43 can obtain the
sole image of the object 45. This avoids the overlap between the
object real image and the mirror image in FIG. 2 and FIG. 3 of the
prior art; more details will be described below with reference to
FIG. 5. The fourth lighting element 424 is disposed between the
second reflective element 412 and the first lighting element 421,
whereby similar overlap situations are also avoided when the object
45 is in the neighborhood of the fourth lighting element 424. In
addition, the included angle between the first reflective element
411 and the second reflective element 412 may be larger than
90.degree. so as to resolve the problem of the infinite reflection;
a preferred range is between 90.degree. (not included) and
96.degree. (included). As shown in FIG. 4, the first reflective
element 411 does not cover the whole first side 481, and the second
reflective element 412 also does not cover the whole second side
482. That is, the sum of the lengths of the first side 481 and the
second side 482 is larger than the sum of the lengths of the two
reflective elements (411 and 412). In this embodiment, a
non-reflective region is provided adjacent each reflective element,
i.e., adjacent the side which is closer to the image sensor, so
that the overlap between the real image and the virtual image of
the object occurs less often. In the non-reflective region,
preferably, a lighting element is disposed to increase the accuracy
of recognizing the real image.
[0036] FIG. 5 shows that the optical touch panel system of FIG. 4
captures a picture through the sensing paths passing the object.
FIG. 6 shows a schematic diagram of the image-sensing window of the
image sensor in FIG. 5. When the object 45 is in or close to the
neighborhood of the third lighting element 423, the second lighting
element 422 and the third lighting element 423 can emit light to
form a bright zone 61 with higher brightness in the image-sensing
window 60 captured by the image sensor 43. Because the object 45
shields a portion of light from the third lighting element 423, a
narrow and dark object image 62 is formed, as shown in FIG. 6. This
sensed object image 62 is also referred to as the optical
information of the object, or projected image of the object
(projected object image). Compared with FIG. 3 of the prior art,
the projected object image 62 obtained in this embodiment is
isolated, so the overlap between the mirror image and the real
image (i.e., between the projected mirror image and the projected
object image which are formed on the picture sensed by the image
sensor 43) does not occur. A first mirror image 491 is formed by
reflecting the object 45 through the second reflective element 412,
and a second mirror image 492 is formed by reflecting the first
mirror 491 through the first reflective element 411. A first
projected mirror image 631 and a second projected mirror image 632
(or named as the optical information of the first mirror image and
the second mirror image) are respectively formed on the
image-sensing window 60 by the first mirror image 491 and the
second mirror image 492. In this embodiment, the projected object
image 62 maybe a shielded image with lower brightness in comparison
with the background (bright zone 61) of the image-sensing window
60.
[0037] Referring to FIG. 6, the processor 44 can select any two of
the optical information of the projected object image 62, the first
projected mirror image 631, and the second projected mirror image
632. The coordinates of the object 45 are obtained according to the
geometric information such as the centers, gravity centers, or
representative positions of the selected optical information. The
coordinates can be calculated by any method typically used and well
known by a person ordinarily skilled in the art. For more
reference, please refer to US 2011/0061950 also filed by the same
applicant. Because the second projected mirror image 632 is a
mirror image formed by secondary reflection, the light path is long
and thus the optical information may be unclear or insufficient;
for example, the brightness of the second projected mirror image
632 may be close to its background. In this case, the processor 44
can select the object image 62 and the first projected mirror image
631 for calculating the coordinates of the object 45. And when the
object 45 is close to the neighborhood of the fourth lighting
element 424, because the present embodiment provides the fourth
lighting element 424 instead of a mirror, the image overlapping
problem can be resolved.
[0038] FIG. 7 shows a schematic diagram illustrating another
embodiment of an optical touch panel system of the present
invention. The optical touch panel system 7 comprises first and
second reflective elements (711 and 712), first to fourth lighting
elements (721-724), an image sensor 43 and a processor 44. The
first reflective element 711 and the second reflective element 712
are respectively disposed on the first side 481 and the second side
482 of the touch control area 48, wherein the first and second
sides 481 and 482 are adjacent to each other. The first and second
lighting elements (721 and 722) are respectively disposed on the
third side 483 and the fourth side 484 of the touch control area
48, wherein the third and fourth sides 483 and 484 are adjacent to
each other. The lighting elements (721, 723, and 724) disposed on
the second side 482 and the third side 483 illuminate the touch
control area 48 to assist the formation of the real image of the
object 45 and a virtual mirror image reflected by the first
reflective element 711. In this embodiment, the first reflective
element 711 occupies the whole first side. The second reflective
element 712 is disposed on the middle region of the second side
482. The second lighting element 722 occupies only a portion of the
fourth side 484, and is disposed close to an edge of the fourth
side 484 adjacent to the first side 481. When the object 45 is
close to the corner between the first side 481 and the fourth side
484 such that the real image of the object 45 and the mirror image
reflected by the first reflective element 711 overlap each other,
the second reflective element 712 reflects the object 45 to
generate another mirror image which can be utilized to obtain the
coordinates of the object 45.
[0039] The second reflective element 712 is for taking care of the
upper-left blind zone, so it only has to occupy the middle portion
of the second side 482, such that the coordinates of the object can
be obtained from the mirror image reflected by the second
reflective element 712 when the object 45 stays in the upper-left
blind zone. The second lighting element 722 is optional, and it is
used to enhance the formation of the mirror image of the object 45
by the second reflective element 712. Preferably, the second
lighting element 722 does not extend to reach the image sensor 43,
such that when the object 45 is close to the image sensor 43, there
is not too much light directly reflected by the surface of the
object 45 toward the image sensor 43 to affect the picture captured
by the image sensor 43. The lengths of the second reflective
element 712 and the second reflective element 722 can be adjusted
as desired, as long as they resolve or alleviate the problem of the
upper-left blind zone.
[0040] FIG. 8 shows that the optical touch panel system of FIG. 7
captures a picture through the sensing paths passing the object.
FIG. 9 shows a schematic diagram of the image-sensing window of the
image sensor 43 in FIG. 8. The lighting elements (721, 722, 723 and
724) emit light to form a bright zone 91 with higher brightness in
the image-sensing window 90 captured by the image sensor 43. When
the object 45 is in or close to the neighborhood of the second
lighting element 722, because the object 45 shields a portion of
light emitted from the first lighting element 721 and reflected by
the first reflective element 711, a narrow and dark overlapping
image 92 of the object real image and a first mirror image 791 is
formed in the image-sensing window 90, (that is, the projected
object image and the first projected mirror image overlap with each
other), as shown in FIG. 9. A second mirror image 792 is formed by
reflecting the object 45 through the second reflective element 712,
and a third mirror image 793 is formed by reflecting the second
mirror image 792 through the first reflective element 711. The
second projected mirror image 931 and the third projected mirror
image 932 (the optical information of the second mirror image 792
and the third mirror image 793) are respectively formed on the
image-sensing window 90 by the second mirror image 792 and the
third mirror image 793.
[0041] When the second projected mirror image 931 and the third
projected mirror image 932 are clear or carry sufficient optical
information in comparison with the background bight zone 91, the
coordinates of the object 45 can be obtained according to their
geometric information such as the centers, gravity centers, or
representative positions. However, as previously mentioned, the
light path of the third projected mirror image 932 is long and the
optical information may be unclear or insufficient. In this case,
the geometric information of the overlapping image 92, such as the
two sides or the border of the overlapping image 92, can be
utilized to calculate the the coordinates of the object 45.
[0042] FIG. 10 shows a schematic diagram illustrating another
embodiment of an optical touch panel system of the present
invention. The optical touch panel system 110 comprises first and
second reflective elements (1111 and 1112), first and second
lighting elements (421 and 422), an image sensor 43 and a processor
44. The first reflective element 1111 and the second reflective
element 1112 are respectively disposed on the first side 481 and
the second side 482 of the touch control area 48, wherein the first
and second sides 481 and 482 are adjacent to each other. The first
and second lighting elements (421 and 422) are respectively
disposed on the third side 483 and the fourth side 484 of the touch
control area 48, wherein the third and fourth sides 483 and 484 are
adjacent to each other. The included angle between the first
reflective element 1111 and the second reflective element 1112
maybe larger than 90.degree. so as to resolve the problem of the
infinite reflection; a preferred range is between 90.degree. (not
included) and 96.degree. (included). In this embodiment, the
coordinates of the object 45 can be calculated by a way similar to
those described in the previous embodiments. The details are
omitted here.
[0043] FIG. 11 shows a flow chart illustrating a positioning method
of the optical touch panel system of the present invention. In Step
S121, the image sensor of the optical touch panel system captures
the real image of the object and its plural mirror images formed by
the two reflective elements. It is possible that the projected
object image and a closest projected mirror image overlap in the
image-sensing window, such as the overlapping image 92 in FIG. 9,
but it is less likely for such overlapping image to occur in the
embodiments in FIGS. 5 and 6. In the next Step 122, the system
checks whether the number of the projected images (the total number
of the projected object image and the projected mirror images) is
smaller than 4, wherein an overlapping image counts 1. If the
projected images overlap with one another or the optical
information of a certain image is unclear, the number of the
projected images maybe smaller than 4. If the number is equal to 4
(or larger), any two projected images can be selected, and the
coordinates of the object are obtained by the geometric information
of the two projected images, such as the gravity centers, centers,
or the like, as shown in Step S123. If the number is smaller than
4, the system further checks whether the number of the projected
images is smaller than 3, as shown in Step S124. If the number is
equal to 3, the overlapping image is excluded and the two other
isolated projected images are selected. The coordinates of the
object are obtained by the geometric information of the two
projected images, such as the gravity centers, centers, or the
like, as shown in Step S125. If the number is smaller than 3, the
overlapping image formed by the object image overlapping the mirror
image is selected. The coordinates of the object are obtained
according to the borders or sides of the overlapping image, as
shown in Step S126, by analyzing the borders or sides of the
overlapping image to obtain the gravity centers or centers of the
projected object image and the projected mirror image included in
the overlapping image.
[0044] The present invention has been described in considerable
detail with reference to certain preferred embodiments thereof. It
should be understood that the description is for illustrative
purpose, not for limiting the scope of the present invention. Those
skilled in this art can readily conceive variations and
modifications within the spirit of the present invention. For
example, the positions and the number of the lighting elements can
be different from the foregoing embodiments. For another example,
two or more reflective elements can be provided on each of the
first side and the second side as long as sufficient optical
information can be obtained. Thus, the present invention should
cover all such and other modifications and variations, which should
be interpreted to fall within the scope of the following claims and
their equivalents.
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