Patent Description:
In the related art, an electronic device provided with a touch panel capable of a hover operation that enables an operation at a position away from the touch panel has been known (see, for example, <CIT>). This electronic device performs a process of invalidating the coordinates detected by the indicator assuming that the indicator is located at the peripheral portion of the touch panel when the flatness of the area occupied by the indicator on a predetermined face away from the display face of the display unit by a predetermined distance is larger than a threshold value.

In the touch panel disclosed in <CIT> described above, the coordinates when the indicator is located at the peripheral portion of the touch panel are invalidated. Depending on how the display unit is used, it may be necessary to detect the position of the indicator at the peripheral portion of the display unit or the touch panel.

By using this touch panel, it is possible to detect not only the position along the X-axis direction and the Y-axis direction parallel to the display face, but also the vertical position with respect to the display face. Since part of the indicator is placed outside the edge of the touch panel when detecting the height of the indicator at the peripheral portion of the touch panel, the number of electrodes facing the indicator at the peripheral portion is smaller than the number of them at other places. Therefore, there is a problem that the detection level of the indicator is low, the height of the indicator determined based on this detection level is higher than the actual value, and the detection accuracy at the peripheral portion deteriorates.

<CIT> discloses a method of calculating position of a conductive object hovering above a plurality of mutual capacitance sensors and, in particular, how to perform a correction to positions (i.e. "X position" and "Y position) of the conductive objection which moves into the edge zone on a capacitance sensing array. <CIT> discloses improved capacitive touch and hover sensing with a sensor array. An AC ground shield positioned behind the sensor array and stimulated with signals of the same waveform as the signals driving the sensor array may concentrate the electric field extending from the sensor array and enhance hover sensing capability. The hover position and/or height of an object that is nearby, but not directly above, a touch surface of the sensor array, e.g., in the border area at the end of a touch screen, may be determined using capacitive measurements of sensors near the end of the sensor array by fitting the measurements to a model. <CIT> discloses a touch and hover sensing device that can switch between a touch mode and a hover mode. During a touch mode, the device can be switched to sense one or more objects touching the device. During a hover mode, the device can be switched to sense one or more objects hovering over the device. The device can include a panel having multiple sensors for sensing a touching object and/or a hovering object and a touch and hover control system for switching the device between the touch and hover modes.

An object of the present invention is to provide an input device capable of preventing detection accuracy in the height direction at a peripheral portion of a touch panel from deteriorating.

The invention relates to an input device according to the appended claims. Embodiments are disclosed in the dependent claims. An input device according to an aspect of the present invention includes a touch panel having a plurality of electrodes disposed side by side, a detection signal generation unit configured to generate a detection signal used to detect a height to an indicator located at a position away from a surface of the touch panel to input the generated detection signal to each of the plurality of electrodes, a position detection unit configured to detect a position of the indicator along the surface of the touch panel based on a signal component that appears on each of the electrodes when the detection signal is input to each of the plurality of electrodes, a signal measurement unit configured to measure a signal intensity proportional to a capacitance generated between the indicator and each of the electrodes based on a signal component appearing on each of the electrodes, and a height detection unit configured to detect a height of the indicator located at a position away from the surface of the touch panel based on a signal component that appears on each of the electrodes when the detection signal is input to each of the plurality of electrodes, wherein the height detection unit is configured to detect the height of the indicator by summing a signal intensity corresponding to each of a predetermined number of the electrodes centred on a position of the indicator detected by the position detection unit, wherein when detecting a height of the indicator, the height detection unit performs a correction to reduce a height of the indicator when a position of the indicator detected by the position detection unit is included in a peripheral portion of the touch panel, compared with when a position of the indicator detected by the position detection unit is included in a non-peripheral portion.

An input device according to embodiments of the present invention will now be described with reference to the drawings.

<FIG> illustrates the configuration of an input device according to an embodiment. As shown in <FIG>, an input device <NUM> of the present embodiment includes a touch panel <NUM>, a hover signal generation unit <NUM>, a signal measurement unit <NUM>, an XY position detection unit <NUM>, and a height detection unit <NUM>.

The touch panel <NUM> is superimposed on the display face of a display unit <NUM> composed of a liquid crystal display (LCD) or the like, and includes a plurality of transparent electrodes <NUM> and <NUM> disposed side by side used for detecting the position of the indicator. As the indicator, for example, the fingertip of the user is assumed.

<FIG> is a diagram showing an outline of the transparent electrodes <NUM> and <NUM> included in the touch panel <NUM>. As shown in <FIG>, the touch panel <NUM> includes m transparent electrodes <NUM> disposed side by side at equal intervals along the X-axis direction (transverse direction), and n transparent electrodes <NUM> disposed side by side at equal intervals along the Y-axis direction (longitudinal direction) with them formed in a state orthogonal to each other.

In <FIG>, two types of transparent electrodes <NUM> and <NUM> are shown as simple rod-shaped electrodes, but practically, the shape may be such that rectangles as shown in <FIG> are continuously disposed, or other shapes may be applied.

Moreover, in the embodiment, the X coordinate position (X position) and the Y coordinate position (Y position) along the surface of the touch panel <NUM>, and the Z coordinate position (height) away from the surface of the indicator brought close to the touch panel <NUM> to operate the hover operation are detected using the touch panel <NUM>.

The hover signal generation unit <NUM> generates a hover signal as a detection signal used for detecting the X position, the Y position, and the height of the indicator to input the generated hover signal on one end of each of the transparent electrodes <NUM> and <NUM> included in the touch panel <NUM>. As the hover signal, for example, a sine wave signal is used.

The signal measurement unit <NUM> receives a signal component appearing at the other end of each of the transparent electrodes <NUM> and <NUM>, and measures the signal intensity proportional to the capacitance generated between the indicator and each of the transparent electrodes <NUM> and <NUM> based on this signal component. In the embodiment the self-capacity method is used. When a capacitance of a magnitude proportional to the distance when the indicator approaches between the transparent electrodes <NUM> and <NUM> is generated, the level of the signal component output from the other end of each of the transparent electrodes <NUM> and <NUM> is decreased by this amount. The signal measurement unit <NUM> outputs a signal having an intensity corresponding to this decrease as a measurement result.

<FIG> is a diagram showing an output signal of the signal measurement unit <NUM>. In <FIG>, the intensities s1 to s7 of the signals output from the other end of each of the transparent electrodes <NUM> on the one hand are shown. In the present embodiment, the signal intensities s1 to s7 of a total of seven transparent electrodes <NUM>, that is, the transparent electrode <NUM> closest to the indicator and the three transparent electrodes <NUM> on both sides thereof are measured. Among them, the position of the transparent electrode <NUM> corresponding to the highest intensity s4 is a position of the transparent electrode <NUM> where the indicator is closest to the transparent electrode <NUM> and the capacitance between the indicator and the transparent electrode <NUM> is maximized, regarded as an X position of the indicator.

The same applies to the transparent electrodes <NUM> on the other hand. The signal intensities s1 to s7 of a total of seven transparent electrodes <NUM>, that is, the transparent electrode <NUM> closest to the indicator and the three transparent electrodes <NUM> on both sides thereof are measured. Among them, the position of the transparent electrode <NUM> corresponding to the highest intensity s4 is a position of the transparent electrode <NUM> where the indicator is closest to the transparent electrode <NUM> and the capacitance between the indicator and the transparent electrode <NUM> is maximized, regarded as an Y position of the indicator. The XY position detection unit <NUM> detects the position of the set of transparent electrodes <NUM> and <NUM> whose maximum intensity s4 is measured in this way as the X position and the Y position of the indicator.

The height detection unit <NUM> detects (calculates) a height H of the indicator based on the value S obtained by summing the signal intensities s1 to s7 of a total of seven transparent electrodes <NUM> (<FIG>) centered on the X position of the indicator, and the signal intensities s1 to s7 of a total of seven transparent electrodes <NUM> centered on the Y position of the indicator. An example of the calculation formula for performing this detection is shown below. <MAT> where, the parameters included in this equation are values that are calculated or measured according to the amplitude and frequency of the hover signal used, the resistance values and shapes of the transparent electrodes <NUM> and <NUM>, etc. and as an example, Equation (<NUM>) is shown.

The sum value S included in Equation (<NUM>) is the sum value of the intensity of the signal output from each of the seven transparent electrodes <NUM> and the seven transparent electrodes <NUM>. Equation (<NUM>) cannot be applied in the place where signals cannot be obtained from these <NUM> transparent electrodes <NUM> and <NUM>.

<FIG> is a diagram showing a non-peripheral portion to which Equation (<NUM>) is applied and a peripheral portion to which Equation (<NUM>) is not applied. In <FIG>, a peripheral portion A1 of the touch panel <NUM> is the range in which the three transparent electrodes <NUM> or the three transparent electrodes <NUM> from the peripheral end are included, and a non-peripheral portion A2 is the range inside the peripheral portion A1.

When the X position and the Y position of the indicator are included in the non-peripheral portion A2, the intensities of the signals output from the seven transparent electrodes <NUM> and the seven transparent electrodes <NUM> can be summed up, and Equation (<NUM>) can be used to calculate the height of the indicator.

On the other hand, when either the X position or the Y position of the indicator is included in the peripheral portion A1, part of the seven transparent electrodes <NUM> and <NUM> for which signal measurement is desired to be performed will be outside the end of the touch panel <NUM>, and practically there is no transparent electrode corresponding to this portion, and some signals cannot be measured. In this case, since the signal intensity corresponding to this missing transparent electrode cannot be added, the sum value S of the signal intensity is smaller by this amount, and when Equation (<NUM>) is used as it is, the height H of the indicator is larger than in nature. This tendency increases as the X position and the Y position of the indicator approach the end (outer peripheral portion) of the peripheral portion A1.

Therefore, in the present embodiment, when the X position and the Y position of the indicator are included in the peripheral portion A1, the height detection unit <NUM> performs correction (adjustment) according to the position. An example of the calculation formula when correcting Equation (<NUM>) is shown below. <MAT> a/√ (x<NUM> + y<NUM>) included in this equation is the correction coefficient when the indicator is included in the peripheral portion A1. a is a constant obtained from the actual measurement. Further, x is the distance from the end of the non-peripheral portion A2 to the X coordinate of the indicator, and y is the distance from the end of the non-peripheral portion A2 to the Y coordinate of the indicator.

Since the closer the indicator is to the edge of the peripheral portion A1, the more the number of transparent electrodes <NUM> and <NUM> for which the signal intensities are summed up decreases and the smaller the sum value is, the height H will increase by the sum value decreased when Equation (<NUM>) is used. The error of height H can be corrected by performing adjustment by subtracting the height H by the correction coefficient a/√ (x<NUM> + y<NUM>) using Equation (<NUM>).

The hover signal generation unit <NUM> described above corresponds to the detection signal generation unit, the XY position detection unit <NUM> corresponds to the position detection unit, the height detection unit <NUM> corresponds to the height detection unit, and the signal measurement unit <NUM> corresponds to the signal measurement unit.

The input device <NUM> according to the present embodiment has the above configuration. Next, operation thereof will be described.

<FIG> is a flow chart showing an operation procedure of the input device <NUM> configured to detect the height of the indicator. When the detection operation in the hover operation is started, the hover signal generation unit <NUM> generates a hover signal to input the generated hover signal to one end of each of the transparent electrodes <NUM> and <NUM> (step <NUM>).

Next, the signal measurement unit <NUM> measures the signal intensity proportional to the capacitance generated between the indicator and each of the transparent electrodes <NUM> and <NUM> based on the signal component appearing at the other end of each of the transparent electrodes <NUM> and <NUM> (step <NUM>). Further, the signal measurement unit <NUM> determines whether an approaching indicator is detected based on the measured signal intensity (step <NUM>). When the indicator is not close (when the signal intensity corresponding to the indicator is not detected), a negative determination is made, and the process returns to step <NUM> to continue the signal intensity measurement.

Further, when the indicator is close (when the signal intensity corresponding to the indicator is detected), a positive determination is made in the determination in step <NUM>. Next, the XY position detection unit <NUM> detects the X position and the Y position of the indicator based on the intensity of the signal measured by the signal measurement unit <NUM> (step <NUM>).

Next, the height detection unit <NUM> determines whether the indicator is included in the peripheral portion A1 (<FIG>) based on the X position and the Y position of the indicator (step <NUM>). When it is not included (if the indicator is included in the non-peripheral portion A2), a negative determination is made. In this case, the height detection unit <NUM> calculates the height H using Equation (<NUM>) without correction based on the sum value of the signal intensities corresponding to a total of <NUM> transparent electrodes <NUM> and <NUM> in total centered on the X position and the Y position of the indicator (step <NUM>).

On the other hand, when the indicator is included in the peripheral portion A1, a positive determination is made in the determination in step <NUM>. In this case, the height detection unit <NUM> calculates the height H using Equation (<NUM>) with correction based on the sum value of the signal intensities corresponding to less than <NUM> transparent electrodes <NUM> and <NUM> centered on the X position and the Y position of the indicator (step <NUM>).

In this way, since the input device <NUM> of the embodiment, performs the correction to reduce the height position by this amount even when the indicator is located at peripheral portion A1 of the touch panel <NUM> and the number of transparent electrodes required for height detection is insufficient (less than <NUM> in total), so that it is possible to prevent detection accuracy in the height direction due to the position of the indicator from deteriorating.

Further, in this correction, the amount of increase in the height correction is increased as it approaches the end (outer peripheral portion) of the peripheral portion A1, and it will be possible to improve the detection accuracy in the height direction that deteriorates as the position of the indicator approaches the outer peripheral portion.

Specifically, when the height is detected by summing the signal intensity corresponding to each of a predetermined number (<NUM> in each of the X-axis direction and the Y-axis direction) of transparent electrodes <NUM> and <NUM>, the decrease, in the sum value, that occurs when the number of transparent electrodes to be detected in the peripheral portion A1 is less than the predetermined number can be compensated for by correction, so that it is possible to reliably prevent the detection accuracy in the height direction in the peripheral portion A1 from deteriorating.

The present invention is not limited to the above-described embodiment, and various kinds of modifications can be made within the scope of the appended claims. For example, in the above-described embodiment, the X position, the Y position, and the height of the indicator are detected by the self-capacity method, but the present invention also includes a case where the position and the height of the indicator are detected by the mutual capacitance method.

Claim 1:
An input device (<NUM>) comprising:
a touch panel (<NUM>) having a plurality of electrodes disposed side by side;
a detection signal generation unit configured to generate a detection signal used to detect a height to an indicator located at a position away from a surface of the touch panel (<NUM>) to input the generated detection signal to each of the plurality of electrodes;
a position detection unit (<NUM>) configured to detect a position of the indicator along the surface of the touch panel (<NUM>) based on a signal component that appears on each of the electrodes when the detection signal is input to each of the plurality of electrodes; and
a signal measurement unit (<NUM>) configured to measure a signal intensity proportional to a capacitance generated between the indicator and each of the electrodes based on a signal component appearing on each of the electrodes,
characterised by
a height detection unit (<NUM>) configured to detect a height of the indicator located at a position away from the surface of the touch panel (<NUM>) based on a signal component that appears on each of the electrodes when the detection signal is input to each of the plurality of electrodes, wherein the height detection unit (<NUM>) is configured to detect the height of the indicator by summing a signal intensity corresponding to each of a predetermined number of the electrodes centered on a position of the indicator detected by the position detection unit (<NUM>),
wherein when detecting the height of the indicator, the height detection unit (<NUM>) is configured to perform a correction to reduce the height of the indicator when a position of the indicator detected by the position detection unit (<NUM>) is included in a peripheral portion (A1) of the touch panel (<NUM>), compared with when a position of the indicator detected by the position detection unit (<NUM>) is included in a non-peripheral portion (A2).