POINTER DETECTION APPARATUS AND POINTER DETECTION METHOD

• US 20120146940A1
• Filed: 11/22/2011
• Published: 06/14/2012
• Est. Priority Date: 12/08/2010
• Status: Active Grant

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Wacom Co Limited (Wacom)
• Inventors: Yamamoto, Sadao, Oda, Yasuo, Sugiyama, Yoshihisa
• Granted Patent: US 9,235,288 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• 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

Abstract

A pointer detection apparatus includes a conductor pattern formed of intersecting first and second conductors. A signal supplying circuit generates transmission signals each comprised of a first code and a second code having an equal code length and having a predetermined relationship to each other, and supplies the generated transmission signals to the first conductors. A signal detection circuit is connected to the second conductors and detects reception signals, at least one of which corresponds to a variation of capacitance between the conductor pattern and a pointer. A correlation arithmetic operation circuit calculates, for each of the reception signals, first and second correlation values between the reception signal and first and second correlation value arithmetic operation signals corresponding to the first and second codes, respectively. A synthesis circuit calculates, for each pair of the first and second correlation values, a synthesis correlation value, based on which the pointer is detected.

Claims

1. A pointer detection apparatus, comprising:

a conductor pattern including a plurality of first conductors disposed in a first direction and a plurality of second conductors disposed in a second direction that crosses the first direction;

a signal supplying circuit configured to generate transmission signals each comprised of a first code and a second code, and to supply the generated transmission signals to the plurality of first conductors, wherein the first and second codes that form one transmission signal have an equal code length and have a predetermined relationship to each other;

a signal detection circuit connected to the plurality of second conductors and configured to detect reception signals, at least one of which corresponds to a variation of capacitance between said conductor pattern and a pointer;

a correlation arithmetic operation circuit configured to calculate, for each of the reception signals detected by said signal detection circuit, a first correlation value between the reception signal and a first correlation value arithmetic operation signal corresponding to the first code and a second correlation value between the reception signal and a second correlation value arithmetic operation signal corresponding to the second code; and

a synthesis circuit configured to calculate, for each pair of the first and second correlation values, a synthesis correlation value by synthesizing the pair of first and second correlation values calculated by said correlation arithmetic operation circuit;

wherein the pointer detection apparatus is configured to detect the pointer based on the synthesis correlation values calculated by said synthesis circuit.

2. The pointer detection apparatus according to claim 1, wherein said signal supplying circuit exchanges allocations of bits between the first code and the second code, each code comprising a plurality of bits, and then outputs resulting codes with their bit allocations having been exchanged.

3. The pointer detection apparatus according to claim 1, wherein said signal supplying circuit outputs the second code continuously to the first code.

4. The pointer detection apparatus according to claim 1, wherein said signal supplying circuit exchanges allocations of bits between the first code and the second code, each comprising a plurality of bits, in a unit of a predetermined number of bits, and then outputs resulting codes with their bit allocations having been exchanged.

5. The pointer detection apparatus according to claim 1, wherein the first and second codes are complimentary codes.

6. The pointer detection apparatus according to claim 1, wherein the second code is a code obtained by reversing the polarity of the first code.

7. A pointer detection method for detecting a position pointed to by a pointer on a conductor pattern formed of a plurality of first conductors disposed in a first direction and a plurality of second conductors disposed in a second direction, which crosses the first direction, the method comprising:

generating transmission signals each comprised of a first code and a second code having an equal code length and having a predetermined relationship to each other, and supplying the generated transmission signals to the plurality of first conductors;

detecting reception signals from the plurality of second conductors, at least one of the reception signals corresponding to a variation of capacitance between the conductor pattern and the pointer;

calculating, for each of the detected reception signals, a first correlation value between the detected reception signal and a first correlation value arithmetic operation signal corresponding to the first code, and a second correlation value between the detected reception signal and a second correlation value arithmetic operation signal corresponding to the second code;

calculating, for each pair of the first and second correlation values, a synthesis correlation value by synthesizing the calculated pair of first and second correlation values; and

detecting the pointer based on the calculated synthesis correlation values.