Coordinate sensing system, coordinate sensing method and display system
A coordinate sensing system includes a magnetic member, a direction sensor, a first magnetic sensor and a processor, wherein the processor communicates with the direction sensor and is electrically connected to the first magnetic sensor. The magnetic member has a magnetic dipole moment. The direction sensor is used for sensing a direction of the magnetic dipole moment. The first magnetic sensor is used for sensing a first magnetic field of the magnetic member. The processor is used for calculating a first distance between the magnetic member and the first magnetic sensor and calculating a direction of the first distance according to a value of the magnetic dipole moment, the direction of the magnetic dipole moment and the first magnetic field. The processor is further used for calculating a coordinate of the magnetic member according to the first distance and the direction of the first distance.
1. A device control system comprising:
a handheld device comprising:
a magnetic member having a magnetic dipole moment, a Z direction of the handheld device is parallel to a direction of the magnetic dipole moment; and
a direction sensor for sensing a direction of the magnetic dipole moment;
a magnetic sensor for sensing a magnetic field of the magnetic member; and
a processor communicating with the direction sensor and electrically connected to the magnetic sensor, the processor being used for calculating a distance between the magnetic member and the magnetic sensor and calculating a direction of the distance according to the magnetic dipole moment, the direction of the magnetic dipole moment and the magnetic field, the processor being further used for calculating a 3D coordinate of the magnetic member according to the distance and the direction of the distance relative to a line from the magnetic member to the magnetic sensor, and a display device executes a predetermined function according to the 3D coordinates of the magnetic member.
2. The system of claim 1 , wherein the direction sensor is a three-axis gyro.
3. The system of claim 1 , further comprising a communication module electrically connected to the processor and used for communicating with the display device and the direction sensor, the processor transmitting the coordinate of the magnetic member to the display device through the communication module.
4. The system of claim 3 , further comprising a casing, wherein the magnetic sensor, the processor and the communication module are disposed in the casing, an indication plane is defined on the casing, the processor transmits the direction of the magnetic dipole moment to the display device through the communication module, and the display device executes the predetermined function according to the coordinate of the magnetic member and the direction of the magnetic dipole moment.
5. The system of claim 4 , wherein when an end of the magnetic member faces the indication plane, the predetermined function is an eraser function, a palm function or a 3D drawing function.
6. The system of claim 4 , wherein when an end of the magnetic member faces the indication plane and a distance between the end and the indication plane is smaller than a first threshold, the predetermined function is a handwriting input function.
7. The system of claim 4 , wherein when an end of the magnetic member faces the indication plane and a distance between the end and the indication plane is larger than a second threshold, the predetermined function is a cursor moving function.
8. The system of claim 1 , wherein a location of the magnetic sensor is an origin of a coordinate system used to calculate the coordinate and the magnetic field of the magnetic member sensed by the magnetic sensor relative to the origin is calculated by the following equation in polar coordinates:
B
⇀
=
B
x
i
^
+
B
y
j
^
+
B
z
k
^
=
μ
0
4
π
r
3
[
3
(
m
⇀
·
r
^
)
r
^
-
m
⇀
]
=
μ
0
4
π
r
3
(
3
m
cos
θ
r
^
-
m
k
^
)
wherein {right arrow over (m)} represents the magnetic dipole moment of the magnetic member and the direction of the magnetic dipole moment {right arrow over (m)} is parallel to a coordinate axis z of the Cartesian coordinate system; {right arrow over (B)} represents a magnetic field of the magnetic member sensed by the magnetic sensor 12 relative to the origin; B x , B y and B z represent three components of the magnetic field {right arrow over (B)} relative to the coordinate axes x, y and z; r represents the distance between the magnetic member and the magnetic sensor; î, ĵ and {circumflex over (k)} represent three unit vectors of the coordinate axes x, y and z, θ represents an angle included between the distance r and the coordinate axis z, μ 0 represents a permittivity of the air, and {circumflex over (r)} represents a unit vector of the distance r in a direction from the magnetic moment to the origin.
9. The system of claim 8 , wherein a component of the magnetic field {right arrow over (B)} relative to the coordinate axis z is calculated by the following equation:
B
⇀
z
=
μ
0
4
π
r
3
[
3
m
cos
2
θ
k
^
-
m
k
^
]
=
μ
0
m
4
π
r
3
(
3
cos
2
θ
-
1
)
k
^
.
10. The system of claim 9 , wherein the component of the magnetic field {right arrow over (B)} relative to the coordinate axis z is calculated using
3
cos
2
θ
=
4
π
r
3
B
z
μ
0
m
+
1.
11. The system of claim 8 , wherein an axis of the magnetic field {right arrow over (B)} is calculated in polar coordinates by
B
⇀
=
μ
0
m
4
π
r
3
(
2
cos
θ
r
^
+
sin
θ
θ
^
)
.
12. The system of claim 1 , wherein the coordinate sensing system comprises only one magnetic sensor only sensing a first magnetic field of the magnetic member.
13. The system of claim 1 , wherein a component of the magnetic field relative to a coordinate axis used to calculate the 3D coordinate is in inverse proportion to the distance^3.
14. The system of claim 1 , wherein the direction of the magnetic dipole moment is parallel to one axis of the direction sensor.
15. A method of gesture control comprising:
sensing a direction of a magnetic dipole moment of a magnetic member by a direction sensor;
sensing a magnetic field of the magnetic member by a magnetic sensor;
calculating a distance between the magnetic member and the magnetic sensor and calculating a direction of the distance according to the magnetic dipole moment, the direction of the magnetic dipole moment and the magnetic field;
calculating a 3D coordinate of the magnetic member according to the distance and the direction of the distance relative to a line from the magnetic member to the magnetic sensor;
transmitting the 3D coordinate of the magnetic member and the direction of the magnetic dipole moment to a display device; and
executing a predetermined function in the display device according a gesture determined according to the 3D coordinates of the magnetic member and the directions of the magnetic dipole moment.
16. The method of claim 15 , wherein the direction sensor is a three-axis gyro.
17. The method of claim 15 , wherein when an end of the magnetic member faces the indication plane, the predetermined function is an eraser function, a palm function or a 3D drawing function.
18. The method of claim 15 , wherein when an end of the magnetic member faces the indication plane and a distance between the end and the indication plane is smaller than a first threshold, the predetermined function is a handwriting input function.
19. The method of claim 15 , wherein when an end of the magnetic member faces the indication plane and a distance between the end and the indication plane is larger than a second threshold, the predetermined function is a cursor moving function.
20. A display system comprising:
a display device for displaying an object; and
a coordinate sensing system comprising:
a handheld device comprising:
a magnetic member having a magnetic dipole moment; and
a direction sensor for sensing a direction of the magnetic dipole moment;
a coordinate sensing device comprising:
a communication module for communicating with the display device and the direction sensor;
a magnetic sensor for sensing a magnetic field of the magnetic member; and
a processor electrically connected to the communication module and the magnetic sensor, the processor being used for calculating a distance between the magnetic member and the magnetic sensor and calculating a direction of the distance according to the magnetic dipole moment, the direction of the magnetic dipole moment, and the magnetic field, the processor being further used for calculating a 3D coordinate of the magnetic member according to the distance and the direction of the distance relative to a line from the magnetic member to the magnetic sensor;
wherein the processor transmits the 3D coordinate of the magnetic member to the display device through the communication module and the display device executes a predetermined function in the display device according to the 3D coordinates of the magnetic member.
21. The display system of claim 20 , wherein the direction sensor is a three-axis gyro.
22. The display system of claim 20 , wherein the coordinate sensing device further comprises a casing, the magnetic sensor, the processor and the communication module are disposed in the casing, an indication plane is defined on the casing, the processor transmits the direction of the magnetic dipole moment to the display device through the communication module, and the display device performs the predetermined function according to the 3D coordinate of the magnetic member and the direction of the magnetic dipole moment.
23. The display system of claim 22 , wherein when an end of the magnetic member faces the indication plane, the predetermined function is an eraser function, a palm function or a 3D drawing function.
24. The display system of claim 22 , wherein when an end of the magnetic member faces the indication plane and a distance between the end and the indication plane is smaller than a first threshold, the predetermined function is a handwriting input function.
25. The display system of claim 22 , wherein when an end of the magnetic member faces the indication plane and a distance between the end and the indication plane is larger than a second threshold, the predetermined function is a cursor moving function.