Abstract: The present invention provides a method and a device for detecting position without producing discrepancy caused by residual induction voltage of a resonant circuit, wherein it includes steps for selecting and scanning one of a multiple loop coil positioned parallel to each other towards a detecting direction to receive an electromagnetic wave (S1), and calculating coordinate values of the indicated position provided by a position indicator based upon at least two detected induction voltages (S3), a direction for selecting and scanning of the loop coils is alternatively changed (S5, 6), and the coordinate values are averaged to eliminate the residual induction voltage effect (S8).

Abstract: An angular information input system detects the inclined angle of a pointing device with a high accuracy without possible errors. This system is constituted so as to detect the induction voltage distribution in each axial direction generated by sensing coils (Ci) arranged under a display screen (16) by electromagnetic wave from a tuning circuit (34) contained in a pointing device (34). This system includes calculating means for calculating normalized values vpax, vpbx, vpay, and vpby in each axial direction by using a ratio between main peak voltage (Vp) representing the pointed coordinate by the pointing device (34) and auxiliary peak voltages (Vpa, Vpb). These normalized values are function parameters for calculating the inclined angles (.multidot..theta.x, .theta.y) in respective axial directions to input data representing the inclined angle .theta. and inclined direction of the pointing device into the associated computer.

Abstract: A coordinate detecting device and an angle information detecting method which are capable of detecting tilt angles of a stylus pen with high accuracy. A coordinate detecting device is made up of a plurality of sensor coils and a position indicator housing an electromagnetic coupling means, and detects coordinates and tilt angles of the position indicator by sensing an induced voltage developed in the sensor coil by means of electromagnetic interaction. The coordinate detecting device is also provided with an angle information detecting means. This angle information detecting means correct errors in a value of a predetermined function including main and sub-peaks, the errors arising from a difference between a main peak induced voltage distribution and a sub-peak induced voltage distribution within a detection width of one sensor coil, by converting either the main peak induced voltage distribution or the sub-peak induced voltage distribution so as to be similar to the other one.

Abstract: An electromagnetic detector having plural loop coils arranged in parallel with one another in a position detecting direction determines a position coordinate value designated by a position indicator having at least a coil. One loop coil in each of plural groups is selected simultaneously from plural loop coils of the group so not less than a predetermined number of the relative positions of these selected loop coils are not the same or are a symmetric in each group and over a plurality of groups. A loop coil on which the position indicator is positioned is determined in response to a signal amplitude pattern obtained by the loop coil selection. This makes it unnecessary to select all loop coils at the time of starting a position detecting operation, to reduce the time required to determine the coordinate value.

Abstract: A coordinate input system has a tablet composed of an X-direction loop coil assembly and a Y-direction loop coil assembly, and an input pen having a tuning circuit the tuning frequency of which is variable about a predetermined frequency. The system has a coordinate detecting function for detecting the X- and Y-coordinate values of position input by the input pen, and a phase detecting function for detecting the change in the tuning frequency of the tuning circuit as a change in the phase with respect to the phase of the predetermined tuning frequency. Information concerning the detected coordinate point, e.g., spread of the coordinate point proportional to the pressure at which the pen is pressed onto the tablet, is computed in accordance with the amount of change in the phase detected by the phase detecting function.

Abstract: The position of an implement is determined relative to a tablet including a tuned circuit with a resonant frequency including coils arranged in two coordinate directions. Coils of the tablet are sequentially excited with AC energy having approximately the same frequency as the resonant frequency. The tuned circuit interacts with the AC energy to change the AC current flowing in coils of the tablet as a function of the implement position so the greatest changes in the AC current are in coils of the tablet closest to the implement. Detected values of changes in current as a function of coil position are interpolated to indicate the implement position.

Abstract: A characteristic and the position of an implement with a tuned circuit having one of plural resonant frequencies are determined. AC energy at the plural different resonant frequencies is supplied to a two-coordinate direction coil arrangement of a position sensing tablet. The tuned circuit changes the current flowing in the coil arrangement at the implement resonant frequency. The current change is used to signal the implement position and characteristic. The implement may be an eraser for supplying a signal to an electronic display and for removing a mark from a surface of a visual display overlaying the tablet of the eraser. A housing includes a surface for erasing the marking and two tuned circuits each having a reactance positioned close to opposite edges of the erasing surface. Two switches, when activated, cause the tuned circuits to have different resonant frequencies. The switches are respectively activated when opposite eraser edges are being pushed against the display surface.

Abstract: The position on a surface of an implement including a tuned circuit with a predetermined resonant frequency is determined and displayed by an apparatus having a housing including the surface. A tablet in the housing includes coils arranged in two coordinate directions parallel to the surface. The coils are excited with AC energy having approximately the same frequency as the resonant frequency. The tuned circuit interacts with the AC energy to change the AC current flowing in the coils as a function of the implement on the tablet. An electronic two-coordinate direction display in the housing configured as a plate is superposed with and lies in a plane parallel to the tablet and the surface. The display responds to the change in AC current resulting from the interaction between the AC energy and the tuned circuit to indicate the position of the implement on the surface.

Abstract: A position detecting apparatus for detecting a position pointed by an input pen which comprises: a position detection section constituted by first and second coil groups each composed of a plurality of loop coils; an input pen having a tuning circuit having a predetermined frequency as a tuning frequency; selector means for successively selecting the loop coils of the first and second coil groups of the position detection section one by one; signal generation means for supplying an A.C. signal of the predetermined frequency to the loop coils; signal detection means for detecting the A.C. signal of the predetermined frequency from the loop coils; and controller means for identifying the position pointed by the position pointer on the basis of the A.C. signal detected by the signal detection means from among the loop coils of the first and second coil groups, whereby the position pointed by the input pen can be detected on the basis of the induced voltages obtained in the first and second coil groups.

Abstract: A position detecting apparatus for detecting a position pointed by a pointer on a system such as a digitizer has the following parts: a position detection section having a plurality of loop coils arrayed in a side-by-side fashion in the direction of position detection; a selection circuit for successively selecting the loop coils one-by-one; a transmission circuit for generating an A.C. signal of a predetermined frequency to be delivered to the selected loop coil; a receiving circuit adapted to detect an induced voltage of a frequency substantially the same as that of the A.C. signal from among various voltages induced in the selected loop coil; a connection switching circuit for connecting the selected loop coil alternately to the transmission circuit and the receiving circuit; a position pointer having a tuning circuit including a coil and a capacitor and adapted to resonate with an electric wave produced by the loop coil which is supplied with the A.C.

Abstract: A characteristic and the position of an implement with a tuned circuit having one of plural resonant frequencies are determined. AC energy at the plural different resonant frequencies is supplied to a two-coordinate direction coil arrangement of a position sensing tablet. The tuned circuit changes the current flowing in the coil arrangement at the implement resonant frequency. The current change is used to signal the implement position and characteristic. The implement may be an eraser for supplying a signal to an electronic display and for removing a mark from a surface of a visual display overlaying the tablet of the eraser. A housing includes a surface for erasing the marking and two tuned circuits each having a reactance positioned close to opposite edges of the erasing surface. Two switches, when activated, cause the tuned circuits to have different resonant frequencies. The switches are respectively activated when opposite eraser edges are being pushed against the display surface.