POSITION DETECTION APPARATUS

• US 20110216032A1
• Filed: 11/29/2010
• Published: 09/08/2011
• Est. Priority Date: 03/05/2010
• Status: Active Grant

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Wacom Co Limited (Wacom)
• Inventors: Oda, Yasuo, Sugiyama, Yoshihisa
• Granted Patent: US 8,395,598 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A position detection apparatus is provided, which includes a plurality of position detection systems such as an electromagnetic-type position detection system and a capacitive-type position detection system. The apparatus is configured to select a transmission conductor among a plurality of transmission conductors in a first position detection system, and to select a reception conductor among a plurality of reception conductors in a second position detection system, so as to increase the spatial distance between the selected transmission conductor in the first position detection system and the selected reception conductor in the second position detection system as much as possible, to thereby reduce interference. Further, a relationship of frequency interleave may be provided between a transmission signal to be supplied to the transmission conductor in the first position detection system and another transmission signal to be supplied to the transmission conductor in the second position detection system.

Claims

1. A position detection apparatus, comprising:

a first position detection circuit including a first sensor formed of a first set of conductors disposed in a first direction and a second set of conductors disposed in a direction different from the first direction, a first conductor selection circuit connected to said first sensor and configured to select the first set of conductors in accordance with a transmission conductor selection sequence, and an oscillation circuit configured to supply a signal to the first set of conductors through said first conductor selection circuit, the first position detection circuit being configured to detect a position pointed to by a first pointer on said first sensor;

a second position detection circuit including a second sensor formed of a third set of conductors disposed in substantially the same direction as the first direction and a fourth set of conductors disposed in a direction different from the first direction, the second sensor being disposed in a superposed relationship with said first sensor, and a second conductor selection circuit connected to said second sensor and configured to select the third set of conductors disposed in substantially the same direction as the first direction in accordance with a reception conductor selection sequence, the second position detection circuit being configured to detect a position pointed to by a second pointer on said second sensor; and

a control circuit configured to direct said first conductor selection circuit to select a transmission conductor selection position among the first set of conductors, and to direct said second conductor selection circuit to select a reception conductor selection position among the third set of conductors, such that the selected transmission conductor selection position and the selected reception conductor selection position are separated from each other by a predetermined spatial distance.

2. The position detection apparatus according to claim 1, wherein the first set of conductors disposed in the first direction are each formed of a loop coil, and the first position detection circuit further comprises a transmission/reception switching circuit configured to time-divisionally switch between supplying a signal from the oscillation circuit to the loop coil selected by said first conductor selection circuit and receiving a signal from the loop coil selected by said first conductor selection circuit.

3. The position detection apparatus according to claim 2, wherein said first position detection circuit is configured to electromagnetically detect a position pointed to by the first pointer, by transmitting a signal from any of the loop coils through said transmission/reception switching circuit to be received by a resonance circuit in the first pointer and by receiving a signal emitted from the resonance circuit with the loop coils.

4. The position detection apparatus according to claim 1, wherein the control circuit is configured to direct said second conductor selection circuit to select a reception conductor selection position separated by the predetermined spatial distance from the transmission conductor selection position that has been selected by said first conductor selection circuit.

5. The position detection apparatus according to claim 1, wherein the control circuit is configured to direct said first conductor selection circuit to select a transmission conductor selection position separated by the predetermined spatial distance from the reception conductor selection position that has been selected by said second conductor selection circuit.

6. The position detection apparatus according to claim 1, wherein the second position detection circuit further comprises a third conductor selection circuit configured to select the fourth set of conductors of said second sensor in accordance with a transmission conductor selection sequence, and a second oscillation circuit configured to supply a signal to the fourth set of conductors through said third conductor selection circuit, the second position detection circuit being configured to detect a position pointed to by the second pointer based on a variation of capacitance generated in said second sensor.

7. The position detection apparatus according to claim 6, wherein the transmission signal supplied to said first sensor through said first conductor selection circuit and the transmission signal supplied to said second sensor through said third conductor selection circuit have a relationship of frequency interleave.

8. The position detection apparatus according to claim 7, wherein the control circuit is further configured to control the frequency of the transmission signal supplied to said first sensor through said first conductor selection circuit and the frequency of the transmission signal supplied to said second sensor through said third conductor selection circuit to have the relationship of frequency interleave.

9. The position detection apparatus according to claim 1, wherein said first sensor and said second sensor are disposed in a superposed relationship with each other with a display section interposed therebetween, and the position detection apparatus is configured such that position pointing by the first and second pointers is carried out on one face of said second sensor opposite to its other face that is facing said display section.

10. The position detection apparatus according to claim 1, further comprising an output signal generation circuit configured to convert pointed position data regarding positions pointed to by the first and second pointers outputted from said first position detection circuit and said second position detection circuit into data of a predetermined transmission format, which can be separated into first data regarding the first pointer and second data regarding the second pointer.

11. The position detection apparatus according to claim 10, wherein the pointed position data regarding positions pointed to by the first and second pointers include operation data regarding the first and second pointers.

12. The position detection apparatus according to claim 11, wherein the first pointer further comprises a button switch, and the operation data comprise information regarding an operation state of the button switch.

13. A method of detecting operation of one or more pointers on a first sensor and a second sensor, which are configured to detect operation of the one or more pointers and are disposed in a superposed relationship with each other, said first sensor including a first set of conductors disposed in a predetermined direction and configured to transmit a first signal, said second sensor including a second set of conductors disposed also in the predetermined direction and configured to receive a second signal;

the method comprising;

selecting a first conductor among the first set of conductors for transmitting the first signal and selecting a second conductor among the second set of conductors for receiving the second signal in an associated relationship with each other.

14. The method of claim 13, wherein the first signal has a predetermined frequency.

15. The method of claim 13, wherein:

said first sensor and said second sensor each includes another set of conductors disposed in a direction different from the predetermined direction; and

detection of a pointer operation by the first sensor and detection of a pointer operation by the second sensor are carried out based on different methods from each other.

16. The method of claim 15, wherein the first sensor is configured to detect a pen operation based on an electromagnetic type detection method while the second sensor is configured to detect a finger operation based on a capacitive type detection method.

17. The method of claim 13, wherein pointer operation data detected by the first sensor and the second sensor are converted into data of a predetermined transmission format, which can be separated into first data detected by the first sensor and second data detected by the second sensor.

18. The method of claim 13, wherein the first sensor and the second sensor are disposed in a superposed relationship with each other with a display section interposed therebetween;

and

the first and second sensors are arranged such that the operation of one or more pointers is carried out on one face of said second sensor opposite to its other face that is facing the display section.

19. The method of claim 13, wherein selecting the first and second conductors in an associated relationship with each other comprises first selecting the first conductor and then selecting the second conductor that is separated by an interference-reducing distance from the selected first conductor.

20. The method of claim 13, wherein selecting the first and second conductors in an associated relationship with each other comprises first selecting the second conductor and then selecting the first conductor that is separated by an interference-reducing distance from the selected second conductor.