Rohm Co., Ltd.

Naoki Tada

Shinichi Abe

Koichi Saito

Hirotoshi Usui

Kazunori Hisa

Yuji Shimada

Hiroshi Yamashita

A control circuit controls a two-wire resistive touch panel. The two-wire resistive touch panel includes a first region and a second region which are adjacent to each other in a coordinate axis direction (X direction), and the first region has resistance per unit length lower than resistance per unit length of the second region. A measurement unit measures an electric signal having a correlation with impedance between two wires which are lead out from the resistive touch panel. A processing unit (i) determines that the first region is touched when the electric signal or the impedance obtained from the electric signal is included in a predetermined first range, (ii) determines that the second region is touched when the electric signal or the impedance obtained from the electric signal is included in a predetermined second range, and generates a touched coordinate.

Control circuit of resistive touch panel

A touch detection circuit has a first terminal and a second terminal which are respectively coupled to a first electrode and a second electrode located adjacent to each other. The capacitance sensing circuit (i) senses first electrostatic capacitance formed by the first electrode in a space with a periphery including the second electrode, and (ii) senses, by a self-capacitance method, second electrostatic capacitance formed by the first electrode in a space with a periphery in a state where voltage of the second terminal is made to follow voltage of the first terminal. A signal processor detects water over the first electrode and the second electrode on the basis of a difference between the first electrostatic capacitance and the second electrostatic capacitance.

Touch detection circuit with detection of water

A control circuit of a touch panel is disclosed. The touch panel includes first and second terminals drawn from a first resistive film; and third and fourth terminals drawn from a second resistive film. The control circuit includes a coordinate detection circuit configured to generate an impedance detection signal for an impedance of the touch panel and a voltage detection signal for at least one of voltages of the first to fourth terminals, which are used for generating a coordinate touched by a user. The control circuit further includes a memory configured to store initial data corresponding to an initial state impedance of at least one predetermined path of the touch panel. A calibration circuit of the control circuit acquires an operation state impedance of the path and calibrate the coordinate detection circuit based on detection data corresponding to the operation state impedance and the initial state impedance.

Control circuit and control method of touch panel, and touch panel input device and electronic device using the same

A first resistive film is arranged such that one edge thereof is connected to a first terminal, and an edge that is opposite to the aforementioned edge is connected to a second terminal. A second resistive film is arranged with a gap between it and the first resistive film such that one edge thereof is connected to a third terminal. A voltage generating unit applies a predetermined first bias voltage and a predetermined second bias voltage to the first terminal and the second terminal, respectively. A voltage detection unit detects a panel voltage that occurs at the third terminal. A current detection unit detects a panel current that flows through a path including the first terminal, the first resistive film, and the second terminal. A computation unit determines the coordinates touched by the user, based upon the values of the panel voltage and the panel current.

Control circuit and control method for touch panel to determine coordinates touched by user

Control circuit and control method for touch panel

A coordinate generating unit provisionally determines the X-coordinate of a point touched by the user based upon a first panel current and at least one of first and second panel voltages in a first state, and provisionally determines the Y-coordinate of the point touched by the user based upon at least a third panel voltage and a second panel current. When the user touches the two points, i.e., the first and second points, at the same time, the coordinate generating unit determines the coordinates of the first and second points by combining the two provisionally determined X-coordinates and the two provisionally determined Y-coordinates, based upon the magnitude relation between the first and second panel voltages.

Growing community of inventors

Kyoto, Japan

Naoki Tada