Prior art

The present invention relates to a device of the type specified in the preamble of claim 1 , a method of the type specified in the preamble of claim 10 as well as a system of the type specified in the preamble of claim 1.

Modern digital input devices can be controlled via a touch-sensitive, electrically capacitively acting input interface, referred to as electrically capacitively acting touchpad or simply as touchpad hereinafter. Particularly widely used devices are capacitively acting systems, in which e.g. a grid of conductors or a grid of electrodes applied to the lower surface of the cover of the input interface has an AC voltage applied thereto.

When a finger or a pointing device of the user approaches a node of the grid, the finger or the pointing device and the conductors or the electrodes define the two plates of a capacitor and the cover of the touchpad defines the dielectric thereof.

Due to the fact that the conductors or electrodes are part of an RC element, i.e. part of a circuit comprising a resistor and a capacitor, the change of capacitance caused by the approaching finger or pointing device can be measured and the touch point can be determined in this way.

US 7 612 767 B1, for example, describes such a conventional pointing device for a touchpad, the tip of said pointing device being capable of receiving the electric charges from the AC voltage-generated, projected-capacitive sensor field of the input interface and of causing an increase of the capacitance or of the effective capacitance of the pointing device by generating a countervoltage, so that the pointing device is able to influence, via the electrical capacitive coupling to the input interface, an electric charge accumulation on the input interface in a manner that can be interpreted by the input interface of the digital input device as touch of a finger.

However, the above pointing devices and digital input devices exhibit disadvantages e.g. insofar as they are not able to differentiate whether the input interface is touched by an electronic pointing device or whether it is touched by a user's hand or finger. In addition, known pointing devices have a comparatively large contact surface of their tip and this may also be disadvantageous not least to the compactness and ergonomics of the pointing device.

Moreover, conventional electronic pointing devices cannot be used universally for all existing digital input devices having an electrically capacitively acting touchpad, but they can only be used for the subset of electrically capacitively acting touchpads whose evaluation electronics is capable of recognizing the electronic pointing device used.

Task

It is therefore the object of the present invention to improve an electronic pointing device for a digital input device, especially with respect to the versatility of use of the electronic pointing device as well as, inter alia, with respect to the compactness and ergonomics of the electronic pointing device.

Solution

According to the present invention this object is achieved by an electronic pointing device according to claim 1 , a method according to claim 10 and a system according to claim 11. Advantageous embodiments and further developments are the subject matters of the subclaims.

An electronic pointing device according to the present invention for carrying out inputs at a digital input device with an electrically capacitively acting touchpad, wherein the electronic pointing device is electrically capacitively coupled to an electrical measurement signal of the touchpad, may comprise at least one electronic circuit component configured for modulating the electrical capacitance in the tip of the electronic pointing device.

The term electronic circuit component may here comprise an electronic circuit or a plurality of electronic circuits comprising at least one electronic component.

In addition, the term electrical measurement signal is here intended to stand in particular for an electrical measurement signal that may comprise a series of electrical measurement pulses, in particular e.g. a series of alternating current pulses. The individual measurement pulses of the touchpad of the digital input device may here oscillate e.g. at a frequency of 90 to 270 kHz, and the series of measurement signal pulses, each having a pulse duration of e.g. 100 to 400 με (microseconds), may e.g. have a frequency between 40 and 240 Hz. This allows to operate, e.g. at 60 Hz, up to 41 measuring electrodes of a touchpad in succession (41 x 0.4 = 16.4 ms), whereby e.g. a spatial resolution of a touchpad having a width of 200 mm, which comprises strips of 4.8 mm width, can be realized.

The term modulation of the electrical capacitance in the tip of the electronic pointing device may in particular be understood as a sequence or as the modulation of a sequence of changes of the capacitance state or of the effective capacitance of the tip of the electronic pointing device.

The term modulation of the electrical capacitance in the tip of the electronic pointing device may additionally comprise changes of the capacitance state, in the case of which the sign of the capacitance and/or the magnitude of the capacitance value and/or the duration of the capacitance state are changed. In addition, the term modulation of the electrical capacitance in the tip of the electronic pointing device may comprise periodic or non-periodic changes of the capacitance state at specific time intervals or specific time distances.

The electronic circuit component of the electronic pointing device may be configured to carry out a modulation of the electrical capacitance of the tip of the electronic pointing device such that a changeover between e.g. at least two capacitance states of the tip can be effected, wherein at least one capacitance state may assume a capacitance value that may lie below a predetermined capacitance value, e.g. below a capacitance detection threshold value of the touchpad of a digital input device.

The electronic circuit component of the electronic pointing device may additionally be configured to carry out a modulation of the electrical capacitance of the tip of the electronic pointing device such that a changeover between at least two capacitance states of the tip can be effected, wherein at least one capacitance state may assume a capacitance value that is equal to or higher than a predetermined capacitance value, e.g. a capacitance detection threshold value of the touchpad of a digital input device.

The electronic circuit component of the electronic pointing device may additionally also be configured to changeover selectively and/or automatically between the above mentioned modulations. In other words, the electronic circuit component may be configured to carry out a modulation of the electrical capacitance of the tip of the electronic pointing device such that a changeover between at least two capacitance states of the tip can be effected, wherein at least one capacitance state may assume a capacitance value that lies below a predetermined capacitance value, e.g. below a capacitance detection threshold value of the touchpad of a digital input device, and wherein at least one capacitance state may assume a capacitance value that is equal to or higher than a predetermined capacitance value, e.g. a capacitance detection threshold value of the touchpad of a digital input device.

The electronic pointing device according to the present invention offers numerous advantages in comparison with known electronic pointing devices.

For example, contacting of the touchpad by the electronic pointing device can advantageously be differentiated from contacting of the touchpad by the user's hand or fingers, in particular e.g. through the modulation of the electrical capacitance in the tip of the electronic pointing device according to the present invention, since the user's hand or fingers do not exhibit an electrical capacitance modulation according to the present invention.

It follows that if, for example, the modulation of the electrical capacitance in the tip of the electronic pointing device by the electronic circuit component comprises, as mentioned hereinbefore, e.g. capacitance states with capacitance values that lie below a capacitance detection threshold value of the touchpad of a digital input device, i.e. capacitance states with capacitance values at which the touchpad would neither detect nor register a touch, it can be achieved that the touchpad will alternately, i.e. according to the modulation realized, recognize and non- recognize a touch.

This can advantageously allow to differentiate between contacting of the touchpad by the tip of the pointing device and contacting of the touchpad by the user's hand or fingers because contacting by the user's hand or fingers does not exhibit such modulation, since the change in capacitance, or increase in capacitance, caused by contacts by a hand or fingers virtually always involves capacitance values that are large or high enough for being registered and recognized as a touch by the touchpad and by the evaluation electronics of the touchpad, respectively. The electronic pointing device according to the present invention, however, can cause a modulation of the electrical capacitance registered by the touchpad, or the digital input device, that is different from the modulation caused by the user's hand or fingers.

Moreover, the modulation of the electrical capacitance in the tip of the electronic pointing device according to the present invention can be used for adapting the electronic pointing device to the sensitivity of the touchpad of the digital input device, i.e. to the touchpad sensitivity with which electrically capacitive signals can be registered. if, as mentioned above, e.g. the modulation of the electrical capacitance in the tip of the electronic pointing device by the electronic circuit component comprises e.g. capacitance states with capacitance values which are equal to or higher than a predetermined capacitance value, e.g. a capacitance detection threshold value of the touchpad of a digital input device, it can advantageously be guaranteed that the touchpad of the digital input device will reliably recognize when it is being touched by the electronic pointing device.

In this way, the electronic pointing device can be operated universally with each electrically capacitively acting touchpad of a digital input device, independently of the electrically capacitive sensitivity of the touchpad.

The electronic circuit component of the electronic pointing device may also be configured to carry out a modulation of a sequence of capacitance state changes such that capacitance states are changed individually or in groups.

This can advantageously allow to precisely control the modulation of the electrical capacitance in the tip of the electronic pointing device and to optimize it with respect to the characteristics of the touchpad and the characteristics of the evaluation electronics of the touchpad, respectively.

The electronic circuit component may e.g. be configured as follows and allow the mode of operation described hereinafter.

When the tip of the electronic pointing device enters into contact with the touchpad, a small capacitive charge displacement current can flow between the touchpad and the tip. This displacement current taken up by the tip may e.g. flow first across a capacitor to a local ground potential of a voltage-to-current converter. The voltage-to-current converter may additionally also comprise an impedance converter and it may be provided with a plurality of outputs, e.g. a current output and optionally a voltage output.

The current at the current output of the voltage-to-current converter may here be an image of the voltage drop across said capacitor. Since the touch capacitance or contact capacitance can form a capacitive voltage divider in combination with the capacitor, the voltage at the input of the voltage-to-current converter and, consequently, the current at its current output can be in phase with the electrical measurement signal of the touchpad and the measurement voltage of the touchpad, respectively.

The current at the current output of the voltage-to-current converter can then be converted via a resistor into a voltage relative to a system ground.

This voltage can be amplified via an amplifier and fed into the local ground potential of the voltage-to-current converter. The effective amplification and the polarity of the amplification can be adjusted in a suitable manner, e.g. via a control signal of a digital control unit, e.g. a microcontroller.

Via the optional voltage output of the voltage-to-current converter or impedance converter, it is possible to supply e.g. the input voltage applied to the voltage-to-current converter / impedance converter, or an image of the voltage at the tip of the electronic pointing device, to the / an amplifier.

Depending on whether the voltage controlled by the digital control unit and fed in via the amplifier is opposite in phase to or in phase with the voltage across said capacitor, the electrical capacitance in the tip of the electronic pointing device can be increased or reduced, e.g. with respect to a reference capacitance or limit capacitance.

In particular in the case of a reduction of the electrical capacitance in the tip of the electronic pointing device via the regulation of the cooperative voltage, which reduction can be executed by the electronic circuit component, it may be of advantage to use, e.g. directly, the voltage, which is provided via a voltage output of the voltage-to-current converter, for modulating the electrical capacitance in the pointing device tip, since this can reduce the complexity of the cir- cuit, and since stabilization measures for suppressing undesired electrical oscillations can be dispensed with in this case.

The above mentioned voltage which is opposite in phase to the voltage at said capacitor of the tip may also be referred to as countervoltage, and the above mentioned voltage which is in phase with the voltage at said capacitor of the tip may also be referred to as cooperative voltage.

In the case of an operating mode in which the electronic circuit component changes, e.g. increases, the electrical capacitance or the electrically effective capacitance in the tip of the electronic pointing device by generating a countervoltage, the electronic circuit component can be regarded as a current-controlled negative impedance converter.

A countervoltage generated by the electronic circuit component, or an inverse voltage generated with respect to the touchpad, may here have an effect as if a negative capacitance were connected in series with the capacitance between the tip and the touchpad, a circumstance that can be registered by the touchpad as an increased capacitance.

According to an advantageous embodiment, the electronic circuit component may be configured to limit the magnitude of a countervoltage, generated for modulating the electrical capacitance of the tip of the electronic pointing device, to a maximum value, so as to avoid undesirable electrical oscillations of the electrically capacitive coupling between the pointing device and the touchpad.

The regulation of the countervoltage for stabilizing the function and the operation of the electronic circuit component and of the electronic pointing device, respectively, may here take place dynamically. For example, the digital control unit, e.g. a microcontroller, may continuously measure, monitor and regulate the amplitude of the countervoltage, so that, if necessary, the countervoltage can be reduced so as to avoid said undesirable electrical oscillations; it can, however, be guaranteed that a sufficiently high countervoltage can be generated, which is capable of creating in the tip of the electronic pointing device an electrical capacitance that can be detected and recognized by the touchpad.

It has already been mentioned that, when the electronic circuit component is operated such that the electrical capacitance in the tip of the electronic pointing device is reduced by regulating the cooperative voltage, such a stabilizing regulation can be dispensed with, if e.g. the voltage that can be provided via a voltage output of the voltage-to-current converter is used directly for the modulation of the electrical capacitance in the tip of the pointing device.

The electronic circuit component may additionally be configured to carry out the modulation of the electrical capacitance in the tip of the electronic pointing device in time synchronism with a measuring frequency of the digital input device at which contact position determination sensors of the touchpad, e.g. electrodes, are queried.

Such a synchronization of the modulation of the electrical capacitance in the tip with the measurement cycles of the touchpad for contact position determination can advantageously allow defining unequivocal capacitance modulations, which can be recognized by the evaluation electronics of the touchpad in a particularly simple and clear manner.

For example, modulation patterns are imaginable, according to which the tip of the electronic pointing device assumes a first capacitance state e.g. over three measurement cycles of the touchpad, followed by two measurement cycles of the touchpad, in which the tip of the electronic pointing device assumes a second capacitance state.

The recognition of a measurement cycle of the touchpad of the electronic pointing device may here take place e.g. through an amplitude measurement of the voltage taken up through the contact with the touchpad.

In addition, the modulation of the electrical capacitance in the tip of the electronic pointing device according to the present invention allows the tip of the electronic pointing device to be implemented more compact in comparison with conventional electronic pointing devices, and e.g. the area of the tip which can be brought into contact with the touchpad may have mean diameters of less than 3 mm.

Preferably, the contact area at the tip of the electronic pointing device may have mean diameters of 2 - 3 mm, e.g. for accomplishing an advantageous ergonomic design and/or a higher accuracy of inputs at the touchpad.

It follows that the modulation of the electrical capacitance in the tip of the electronic pointing device according to the present invention in comparison with conventional electronic pointing devices allows e.g. the use of thinner tips or of tips with smaller diameters, and thus also improves advantageously the accuracy with which inputs can be carried out by means of the electronic pointing device on a touchpad of a digital input device, since a higher resolution of contact positions on the touchpad can be supported.

A method according to the present invention, used for carrying out inputs at a digital input device with an electrically capacitively acting input surface, i.e. with a touchpad, by means of an electronic pointing device, may comprise e.g. the following steps: receiving an electrical measurement signal of the touchpad at the electronic pointing device, modulating the electrical capacitance in the tip of the electronic pointing device.

A system according to the present invention, used for carrying out and recording inputs at a digital input device with an electrically capacitively acting touchpad, may comprise the following components: a digital input device with an electrically capacitively acting touchpad, an electronic pointing device for carrying out inputs at said digital input device, wherein the electronic pointing device is electrically capacitively coupled to an electrical measurement signal of the touchpad, wherein the electronic pointing device is configured for receiving an electrical measurement signal of the touchpad, and wherein the electronic pointing device comprises at least one electronic circuit component, which may be configured for modulating the electrical capacitance in the tip of the electronic pointing device.

The following figures show exemplarily:

Fig. 1 : an exemplary system for digital inputs

Fig. 2: an exemplary electronic circuit component Fig. 1 shows an exemplary system 100 for carrying out and recording inputs 107 by means of an exemplary electronic pointing device 101 at a digital input device 102 with an electrically ca- pacitively acting, touch-sensitive input interface / electrically capacitively acting touchpad 108.

The electronic pointing device 101 may additionally comprise an electrically conductive rod whose tip 104 can be projected from the end part 105 that may also be configured as an electrically conductive component.

The electronic pointing device 101 may be electrically capacitively coupled to an electrical measurement signal of the touchpad 108 and may receive, e.g. via the tip 104, an electrical measurement signal of the touchpad 108 of the digital input device 102.

The tip 104 of the electronic pointing device 101 may here be part of an electronic circuit component according to the present invention or may be electrically connected to an electronic circuit component according to the present invention (not shown).

According to an advantageous embodiment (not shown), the parts of the electronic circuit component, except for e.g. a digital control unit, microcontrollers and/or a local voltage supply of the eiectronic circuit component, may be arranged as close as possible to the pointing device tip and may be electrically shielded.

For an advantageous ergonomic weight distribution, a digital control unit, microcontrollers and/or a local voltage supply may, however, be arranged more remote from the pointing device tip.

In addition, the digital input device 102 may optionally be configured for transmitting a control signal to the electronic pointing device 101. Said control signal may comprise information on the signal strength of an electrical measurement signal triggered by the electronic pointing device on the touchpad 108, so as to determine a position on the touchpad 108.

To this end, the digital input device 102 may comprise e.g. at least one speaker 109 that is capable of transmitting control signals to the electronic pointing device 101 by sound, e.g. by ultrasound. For receiving the control signals transmitted by the digital input device 102, the electronic pointing device 101 may include at least one microphone 103.

The microphone 103 used for receiving the control signals may e.g. be accommodated below a gripping section 106 in an end part 105 of the electronic pointing device 101.

It is e.g. also imaginable to accommodate the microphone used for receiving the control signals at the end of the electronic pointing device 101 located opposite the tip 104, so as to be able to advantageously prevent the microphone from being covered by the user's writing hand.

Optionally, the electronic pointing device 101 may modulate the electrical capacitance of the tip 104 of the electronic pointing device 101 depending on the received control signal, so as to determine the position of a contact point on the touchpad 108,

Other wireless communication connections between the digital input device 102 and the electronic pointing device 101 for transmitting control signals from the digital input device 102 to the electronic pointing device 101 , e.g. via Bluetooth, Bluetooth Low Energy / Bluetooth Smart or WLAN, are, however, imaginable as well.

Thus, it is possible to adapt e.g. the capacitance behavior of the electronic pointing device 101 even better to the capacitance behavior and the capacitance sensitivity of the touchpad 108.

Fig 2 shows exemplarily a possible embodiment of an electronic circuit component 200, or of an electronic circuit, which is intended to be used in an electronic pointing device, e.g. the pointing device 101 , and which may be configured and operated as described hereinafter.

The touchpad of a digital input device (not shown) may, as mentioned above, generate an electrical measurement signal, e.g. a sequence of alternating current pulses.

If, for example, the tip 201 of an electronic pointing device is placed on the touchpad, a small capacitive displacement current can flow via an electrically capacitive coupling between the touchpad and the tip.

This displacement current can flow via an optional (first) capacitor 202, which can serve as protection against direct current voltage components when the tip comes into contact with the touchpad, and, optionally, via an additional capacitor 203 to a local ground potential of an input component, e.g. to a local ground potential 211 of a voltage-to-current converter 204.

The voltage-to-current converter 204 may be provided with an independent local voltage supply and a local voltage source, respectively.

The voltage-to-current converter 204 may additionally also comprise an impedance converter as well as a plurality of outputs, e.g. a current output and optionally a voltage output.

The current at an output, e.g. at the current output, of the voltage-to-current converter 204 may be regarded as an image of the voltage drop across the capacitor 203. Since the capacitance, which exists when the tip and the touchpad touch one another and which is e.g. referred to as touch capacitance, can form a capacitive voltage divider in combination with the capacitor 203, the voltage at the input of the voltage-to-current converter 204 and, consequently, the current at its current output can be in phase with the electrical measurement signal of the touchpad and in phase with a measurement voltage of the touchpad, respectively.

The current at the current output of the voltage-to-current converter 204 can be converted via the resistor 205 into a voltage relative to the system ground 210. This voltage can be amplified via the amplifier 207 and fed into the local ground potential 21 1 of the voltage-to-current converter 204. in so doing, the effective amplification and the polarity of the amplification can be adjusted and regulated in a suitable manner, e.g. via a control signal 213 from a digital control unit, e.g. the microcontroller 208.

This exemplary design of an electronic circuit component 200 of an electronic pointing device allows e.g. the operating possibilities following hereinafter.

The amplification of the amplifier 207 can be adjusted by the microcontroller 208 via the control signal 213 such that the voltage at the local ground 211 is opposite in phase to the voltage across the capacitor 203.

This has e.g. the effect that a displacement current into the pointing device tip 201 leads to a decrease in the voltage at the local ground 211, whereby the displacement current is amplified. This leads e.g. to a rise in the current at the output of the voltage-to-current converter 204, i.e. the electronic circuit component 200 is cooperatively coupled.

The local ground 21 1 can here be independent of the system ground 210. The voltage-to- current converter 204 may therefore have a voltage supply 209 of its own.

The effect which the rise in the displacement current has on the touchpad corresponds to that of an increased capacitance.

The countervoltage may here preferably be adjusted to a sufficiently high value for the touchpad to recognize a sufficiently high capacitance so that touching of the touchpad through the tip of the pointing device can be recognized.

The degree of cooperative coupling may here depend on the touch capacitance between the touchpad and the tip 201.

The cooperative coupling may here increase to such an extent that the electrically capacitively coupled system starts oscillating.

Hence, the microcontroller 208 is able to measure and monitor the countervoltage, e.g. through an amplitude measurement 206 carried out e.g. between the diode 215 and the capacitor 216.

The microcontroller 208 is capable of adjusting the amplification via a control signal 213 such that, on the one hand, a sufficiently high countervoltage can be generated, whereas, on the other hand, undesired electrical oscillation can be avoided.

The level of the displacement current may depend on the effective capacitance, i.e. on the touch area of the tip 201. A higher capacitance may lead to an increase in the displacement current.

Since also the countervoltage may increase the displacement current, the circuit may start oscillating in the case of an excessively high amplification.

The countervoltage should, however, be as high as possible so that a good function can be guaranteed. In order to allow e.g. a permanently reliable operation, the amplification should preferably be adjusted and corrected in a suitable manner during operation.

These functions should preferably be fulfilled by the microcontroller 208. It is able to measure the countervoltage and to adjust it to e.g. the maximum admissible value at which oscillations will not yet occur.

In addition, the microcontroller 208 is able to measure the maximum and the minimum countervoltage.

During operation, a countervoltage will, e.g. in the case of a correct adjustment, be created only if the touchpad is just carrying a voltage. In the possible measurement voltage pauses of the touchpad, no countervoltage will be created. The microcontroller 208 can evaluate this and adjust the amplification such that the maximum countervoltage reaches a value at which significant distortions will not yet occur. In addition, the microcontroller 208 can ensure that no voltage and thus no oscillations will occur in the pauses.

Via a control signal 212 for controlling and regulating the modulation of the electrical capacitance or of the electrically effective capacitance in the tip of the electronic pointing device, and optionally e.g. by the use of a switch 214, the microcontroller is able to modulate and e.g. block the creation of the countervoltage.

Blocking may e.g. lead to a decrease in capacitance below the detection threshold of the touch- pad.

Thus, it can e.g. be achieved that a touch will alternately be recognized and not be recognized by the touchpad. This allows to differentiate in an advantageous manner between the pointing device tip and the user's hand.

Since the microcontroller 208 is able to detect, e.g. through the amplitude measurement 206, the measurement times of the touchpad, it is here additionally possible to carry out the modulation of the countervoltage, or the modulation of the electrical capacitance or of the electrically effective capacitance in the tip of the electronic pointing device, synchronously with the measurement cycles of the touchpad. This ai!ows e.g. unequivocal patterns, e.g. three measurement cycles active, two measurement cycles inactive, which can be recognized by the evaluation electronics of the digital input device in a particularly clear manner.

In this mode of operation, e.g. the electronic circuit component 200 represents a current- controlled negative impedance converter, in which a positive current at the tip 201 leads to a negative voltage at the tip 201 and vice versa.

This voltage variation may lead to an increase in the current flowing into the tip 201.

Hence, the effective capacitance between the touchpad and the tip can increase in accordance with the voltage amplification of the circuit 200. Thus, it can be guaranteed that even very thin pointing device tips, having e.g. a mean diameter of less than 3 mm, can be recognized by the touchpad.

However, also the following mode of operation of the electronic circuit component 200 is imaginable:

For example, by applying a cooperative voltage, the capacitance of the tip can be reduced, so that a modulation of the capacitance is possible also in this case.

This allows to differentiate between hand and tip even for touchpads that are so sensitive that no increase in the capacitance of the tip of the pointing device is necessary, since the intrinsic initial capacitance of the tip already suffices to trigger a touch signal.

Via the optional voltage output of the voltage-to-current converter 204 or impedance converter, it is possible to supply e.g. the input voltage applied to the voltage-to-current converter / impedance converter, or an image of the voltage at the tip of the electronic pointing device, directly, e.g. via a connection 217, to the amplifier 207.

This can reduce the complexity of the circuit, and stabilization measures for suppressing unde- sired electrical oscillations can here be dispensed with. Other than in the case of the above described method, the voltage fed by the amplifier 207 may thus be in phase with the voltage across the capacitor 203 or in phase with the voltage at the voltage output of the voltage-to- current converter 204 or e.g. in phase with the input voltage.

A current that flows into the tip 201 can then lead to a voltage rise at the local ground 21 1. This can lead to a reduction of the capacitance of the pointing device tip. With a sufficiently high gain, the capacitance of the tip may then fall below the detection threshold of the touchpad.

For example, a system amplification of slightly less than 1 may already allow a sufficient reduction of the capacitance of the pointing device tip.

In addition, also a high, non-inverting amplification may be chosen e.g. via the control 213 of the amplification 213.

For an advantageous universal use of the electronic pointing device such that said use is virtually independent of the capacitive sensitivity with which a touchpad can register touches, the electronic circuit component is able to switch between the described operating possibilities, i.e. it can selectively and automatically change between a modulation with increased capacitance in comparison with a predetermined capacitance value (use case 1) and a modulation with reduced capacitance in comparison with a predetermined capacitance value (use case 2),

Comparatively insensitive touchpads according to use case 1 are able to reliably recognize e.g. the capacitance increased through the countervoltage. Although the capacitance reduced by a cooperative voltage would not be necessary, it would certainly be recognized as "not touched".

Comparatively sensitive touchpads according to use case 2 would e.g. already recognize a normal touch without any countervoltage, but the capacitance increased by the countervoltage does not disturb. The case "not touched" could, however, be recognized through the capacitance reduced by means of the cooperative voltage.

The above is followed by two sheets with two figures.

The reference numerals identify the following: system for carrying out and recording inputs at a digital input device with an electrically capacitively acting, touch-sensitive input interface / electrically capacitively acting touch- pad

electronic pointing device

digital input device

microphone

tip of the electronic pointing device

end part of the electronic pointing device

gripping section of the electronic pointing device

input at the input interface / touchpad

electrically capacitively acting touchpad

speaker

electronic circuit component / electronic circuit

tip of the electronic pointing device

(first) capacitor, used e.g. as a protection capacitor against direct current voltage components when the tip of the electronic pointing device enters into contact with the touch- pad

(second) capacitor

input component, voltage-to-current converter, may optionally also comprise an additional impedance converter

(first) resistor

amplitude measurement

amplifier

digital control unit, e.g. microcontroller

(local) voltage source

system ground

local ground modulation / connection of the digital control unit, e.g. microcontroller, to the amplifier, or e.g. connection of the digital control unit to a switch, for controlling and regulating the modulation of the electrical capacitance or of the electrically effective capacitance in the tip of the electronic pointing device / control signal for controlling and regulating the modulation of the electrical capacitance or of the electrically effective capacitance in the tip of the electronic pointing device

amplification / connection of the digital control unit, e.g. microcontroller, to the amplifier for controlling and regulating the amplifier / control signal for controlling and regulating the amplifier

switch, e.g. controlled by the digital control unit, e.g. microcontroller, for controlling and regulating the modulation of the electrical capacitance or of the electrically effective capacitance in the tip of the electronic pointing device

diode / rectifier

(third) capacitor

connection between component 204 and switch 214