Alps Electric Co., Ltd.

Rohm Co., Ltd.

Brinks Hofer Gilson & Lione

Kinya Inoue

Shinichi Higuchi

Shinji Hirano

Yoshihisa Endo

Mitsuharu Iwasaki

Mikio Matsumoto

Hiroshi Shigetaka

Kouichi Ogino

Motoharu Ishigaki

Tadashi Manome

Mikio Matsumoto, Deceased

Akitoshi Watanabe

Yasuhiro Niwa

The improved small current detector circuit and locator device each include a first and a second capacitor, a pulse drive circuit which drives one terminal of each capacitor by a pulse signal and charges and discharges the capacitors in synchronism with the rise and fall of the applied pulse so as to generate a first and a second detection signal at the other terminal of each capacitor. A current generator circuit receives the first and second detection signals and generates a current representing the difference between the levels of said signals. An integrator circuit integrates the output current from the current generator circuit. At least one of the first capacitor or second capacitor is provided in a detection portion of the detector circuit or locator device.

Small current detector circuit and locator device using the same

There is provided a coordinate input device in which when a coordinate input object is moved on a tablet while being in contact with the tablet, and this state is displayed with cursor movement, fine movement or delay movement of the cursor does not occur. The coordinate input device is constituted by a tablet operated by a coordinate input object and a coordinate data generation section for generating coordinate data representing a coordinate position on the tablet operated by the coordinate input object, and the coordinate data generation section comprises a moving speed detection section for detecting a contact moving speed of the coordinate input object on the tablet and a fine movement removing filter for removing an unnecessary frequency component included in the coordinate data, so that a cutoff frequency of the fine movement removing filter is switched in accordance with the moving speed detected by the moving speed detection section.

Coordinate input device depending on input speeds

A liquid crystal display device with a tablet reduced in apparatus thickness and enhanced in display visibility. The liquid crystal display device mainly composed of a liquid crystal display upper glass plate, a liquid crystal, and a liquid crystal display lower glass plate is connected with a tablet on the upper glass plate, the tablet being mainly composed of a film having a first transparent electrode. A second transparent electrode arranged on the upper glass plate is made function as both an electrostatic capacity detecting electrode and a display electrode. Namely, display is made by the second transparent electrode and a third transparent electrode and a coordinate on the tablet is detected by the first transparent electrode and the second transparent electrode.

Liquid crystal display device with tablet

A coordinate input apparatus capable of preventing inaccurate detection of a position caused by chattering or a disturbed timing, thereby ensuring accurate detection of a position. Open check for determining whether the resistance of contact between a first resistive film and a second resistive film exceeds a preset value for a predetermined time is carried out before and after obtaining a signal of an X-coordinate position and also before and after obtaining a signal of a Y-coordinate position. In addition, there is provided a processing circuit, which detects the signals from tablet electrodes for multiple times within a predetermined time to obtain the position signals, converts them into digital values, calculates the difference between the values, and performs arithmetic processing and output only if the difference is a reference value or less.

Coordinate input apparatus

There is provided a coordinate input device in which when the coordinate position of a contact portion on a tablet by a coordinate input object is to be detected, influence of external noise is minimized to improve the reliability of detection of the coordinate position. The coordinate input device comprises a tablet scanned by one scan signal selected from a plurality of scan signals having different frequencies, and a coordinate data generation section for generating coordinate data representing a coordinate position of a contact portion when a coordinate input object is brought into contact with the tablet, wherein when the tablet is to be scanned with a scan signal, the coordinate data formation section sequentially selects the plurality of scan signals at least once a selecting operation, measures levels of noise included in data output from the tablet each time the selecting operation is performed, and then uses a scan signal representing a minimum noise level of the measured noise levels to scan the tablet.

Coordinate input device

A coordinate input apparatus which performs an input operation with high precision by use of either an operator's finger or an input pen. The input apparatus includes a tablet having a plurality of X electrodes and Y electrodes arranged in the form of a matrix on the respective top and bottom surfaces of a glass substrate. The input apparatus also has a first oscillation circuit connected to the X electrodes through an analog switch. It is further provided with an input pen containing a second oscillation circuit. When the pen is used to perform the input operation through use of coordinates, the following method of determining the coordinates designated by the pen is employed. A voltage oscillating from the pen is applied to each electrode through capacitance, and the resulting output voltage varies depending on the distance from each electrode to the pen. Based on the varied output voltages, a predetermined computation process is executed to determine the coordinates designated by the pen. On the other hand, when the operator's finger is used to perform the input operation, the analog switch is switched to the first oscillation circuit. Then, a voltage at a predetermined frequency is sequentially applied to each of the X electrodes from the first oscillation circuit, and the voltage applied across the X and Y electrodes is changed due to a decrease in the capacitance therebetween caused by the touching of the finger. Based on this change, coordinates designated by the finger is detected.

Coordinate input apparatus with pen and finger input detection

Improved small current detector circuit and locator device each comprise a first and a second element in both of which a small current output occurs, a first and a second constant current generator circuit each generating a specified constant current, a first current mirror circuit which is supplied at the input with said output current occurring in said first element and said specified constant current generated from said first constant current generator circuit, and a second current mirror circuit which is supplied at the input with said output current occurring in said second element and said specified constant current generated from said second constant current generator circuit, and wherein either one of said first and second elements is disposed in a detecting portion and a current equal to the current from the output of either one of said first and second current mirror circuits is flowed to the output of the other current mirror circuit such that a detection output corresponding to the difference between said output currents from said first and second elements is drawn from said other current mirror circuit.

Growing community of inventors

Fukushima-ken, Japan

Kinya Inoue