Pointer detection apparatus and detection sensor

• US 8,749,501 B2
• Filed: 10/21/2010
• Issued: 06/10/2014
• Est. Priority Date: 03/29/2010
• Status: Active Grant

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Wacom Co Limited (Wacom)
• Inventors: Oda, Yasuo, Yamamoto, Sadao, Sugiyama, Yoshihisa
• Primary Examiner(s): Eisen, Alexander
• Assistant Examiner(s): Patel, Sanjiv D
• Application Number:
  US12/909,730
• Publication Number:
  US 20110234508A1
• Time in Patent Office: 1,328 Days
• Field of Search: 345173-178, 178 1801- 2004
• US Class Current: 345/173
• 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 2203/04108 Touchless 2D- digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface without distance measurement in the Z direction
• CPC Class Codes: G06F 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• 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 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

A pointer detection apparatus is provided, which is capable of detecting a pointed position and a pressure applied by a pointer on a detection sensor. The detection sensor includes a plurality of first conductors disposed in a first direction, a plurality of second conductors disposed in a second direction crossing with the first direction, and a pressure sensitive material disposed between the first and second conductors and having a variable resistance characteristic. When a pointer is positioned in the proximity of (but not in contact with) the detection sensor or when a pressure applied to the detection sensor by the pointer in contact with the detection sensor is equal to or lower than a threshold, detection signals corresponding to variation in electrostatic capacity between the first and second conductors are supplied. When the pressure applied to the detection sensor is higher than the threshold, detection signals corresponding to variation in resistance characteristic of the pressure sensitive material are supplied.

Claims

1. A pointer detection apparatus capable of detecting a pointed position of and a pressure applied by a pointer, comprising:

a detection sensor including a plurality of first conductors disposed in a first direction, a plurality of second conductors disposed in a second direction crossing with the first direction, and a pressure sensitive material disposed between the plurality of first conductors and the plurality of second conductors and having a variable resistance characteristic;

a signal supplying circuit configured to supply signals to the plurality of first conductors; and

a signal detection circuit configured to carry out signal detection based on reception signals received from the plurality of second conductors and based on a reference signal level defined as a reception signal level in case a pointer is not positioned in the proximity of the detection sensor, the signal detection circuit including a switch circuit configured to selectively couple the reception signals from the plurality of second conductors to the signal detection circuit operating in a capacitive touch detection mode, and to the signal detection circuit operating in a resistive touch detection mode;

wherein the switch circuit is configured to control the signal detection circuit to detect, in case the pointer is positioned in the proximity of said detection sensor or the pointer is in contact with said detection sensor, a level of the reception signal(s) received from the second conductor(s) that is decreased relative to said reference signal level to indicate variation in electrostatic capacity between the plurality of first conductors and the plurality of second conductors, and to detect, in case the pointer is pressed against said detection sensor, the level of the reception signal(s) received from the second conductor(s) that is increased, according to an amount of pressure applied by the pointer against said detection sensor, relative to said reference signal level to indicate variation in resistance characteristic between the plurality of first conductors and the plurality of second conductors.

2. The pointer detection apparatus according to claim 1, wherein:

the resistance characteristic of said pressure sensitive material varies depending upon an engagement state between said pressure sensitive material and the plurality of first conductors or the plurality of second conductors.

3. The pointer detection apparatus according to claim 2, wherein:

said pressure sensitive material has at least first and second members, and the first or second member is configured to engage with the plurality of first conductors or the plurality of second conductors in response to the pressure from the pointer.

4. The pointer detection apparatus according to claim 2, wherein:

said pressure sensitive material has at least first and second members; and

the first member and the second member are configured to engage with each other in response to the pressure from the pointer.

5. The pointer detection apparatus according to claim 1, wherein:

said pressure sensitive material includes a plurality of conductive particles, which are arranged to be coupled to each other in response to application of the pressure from the pointer to vary the resistance characteristic between the plurality of first conductors and the plurality of second conductors.

6. The pointer detection apparatus according to claim 1, wherein:

the plurality of first conductors and the plurality of second conductors are disposed on one face of a substantially flat substrate, and said pressure sensitive material is provided at least in cross point regions between the plurality of first conductors and the plurality of second conductors and is disposed as an insulating member for the insulation between the plurality of first conductors and the plurality of second conductors when no pressure is applied from the pointer.

7. The pointer detection apparatus according to claim 1, wherein:

said pressure sensitive material is formed at least along the plurality of first conductors or along the plurality of second conductors.

8. The pointer detection apparatus according to claim 1, wherein:

said detection sensor has a substantially flat substrate having transparency and said pressure sensitive material has transparency;

the plurality of first conductors disposed in the first direction, the plurality of second conductors disposed in the second direction, and said pressure sensitive material are provided on the substrate; and

said detection sensor further includes a member having transparency disposed in an opening region formed by the plurality of first conductors disposed in the first direction and the plurality of second conductors disposed in the second direction.

9. The pointer detection apparatus according to claim 8, wherein:

the member having transparency is formed of the same material as that of said pressure sensitive material.

10. The pointer detection apparatus according to claim 1, wherein:

the signals supplied from said signal supplying circuit to the plurality of first conductors are supplied as voltage signals while signals from the plurality of second conductors are detected as a current variation, and said signal detection circuit includes a current/voltage conversion circuit for converting the current variation into a voltage.

11. The pointer detection apparatus according to claim 10, wherein:

said current/voltage conversion circuit includes a first detection mode for obtaining a signal corresponding to variation in electrostatic capacity between the plurality of first conductors and the plurality of second conductors, and a second detection mode for obtaining a signal corresponding to variation in resistance characteristic between the plurality of first conductors and the plurality of second conductors.

12. The pointer detection apparatus according to claim 11, wherein:

said current/voltage conversion circuit is configured from a resistor, a capacitor, and the switch circuit configured to selectively switch between said resistor and said capacitor; and

said switch circuit is further configured to connect said detection sensor to said capacitor in the first detection mode and to connect said detection sensor to said resistor in the second detection mode.

13. The pointer detection apparatus according to claim 1, wherein:

the signals supplied from said signal supplying circuit to the plurality of first conductors are signals which can be discriminated from each other.

14. The pointer detection apparatus according to claim 13, wherein:

said signals supplied from said signal supplying circuit to the plurality of first conductors are codes that are orthogonal to each other.

15. The pointer detection apparatus according to claim 14, wherein:

said signal supplying circuit is configured to supply a calibration signal directly to said signal detection circuit.

16. The pointer detection apparatus according to claim 15, wherein:

the codes supplied from said signal supplying circuit to the plurality of first conductors are Hadamard codes; and

in an Hadamard matrix of the Hadamard codes, nth chips which are all “

1s”

in the matrix are used as the calibration signal for carrying out correction of the signals in said signal detection circuit.

17. A detection sensor for obtaining a signal corresponding to a pointed position of and a pressure applied by a pointer on the detection sensor, comprising:

a plurality of first conductors disposed in a first direction and configured to receive signals;

a plurality of second conductors disposed in a second direction crossing with the first direction; and

a pressure sensitive material disposed between said plurality of first conductors and said plurality of second conductors and having a variable resistance characteristic;

wherein the detection sensor is configured to output from said plurality of second conductors, when a pointer is positioned in the proximity of said detection sensor or the pointer is in contact with said detection sensor, signals whose level is decreased relative to a reference signal level defined as a detection signal level in case the pointer is not positioned in the proximity of the detection sensor, the decreased signal level corresponding to variation in electrostatic capacity between the plurality of first conductors and the plurality of second conductors,

whereas said detection sensor is further configured to output from said plurality of second conductors, when the pointer is pressed against said detection sensor, signals whose level is increased according to an amount of pressure applied by the pointer against said detection sensor relative to said reference signal level, the increased signal level corresponding to variation in resistance characteristic between the plurality of first conductors and the plurality of second conductors.

18. A method of detecting a pointed position of and a pressure applied by a pointer on a detection sensor, wherein the detection sensor includes a plurality of first conductors disposed in a first direction, a plurality of second conductors disposed in a second direction crossing with the first direction, and a pressure sensitive material disposed between said plurality of first conductors and said plurality of second conductors and having a variable resistance characteristic, the method comprising:

supplying signals to the plurality of first conductors;

detecting signals corresponding to variation in electrostatic capacity from said plurality of second conductors when a pointer is positioned in the proximity of said detection sensor or the pointer is in contact with said detection sensor, wherein a level of the detected signals is decreased relative to a reference signal level defined as a detected signal level in case the pointer is not positioned in the proximity of said detection sensor; and

detecting signals corresponding to variation in resistance characteristic from said plurality of second conductors when the pointer is pressed against said detection sensor, wherein the level of the detected signals is increased according to an amount of pressure applied by the pointer against said detection sensor relative to said reference signal level.

19. The method of claim 18, wherein the signals corresponding to variation in electrostatic capacity and the signals corresponding to variation in resistance characteristic are concurrently detected.

20. The method of claim 18, wherein the signals corresponding to variation in electrostatic capacity and the signals corresponding to variation in resistance characteristic are time-divisionally detected.