EP2200785B1 - Handheld electric power tool and method for operating a handheld electric power tool - Google Patents

Handheld electric power tool and method for operating a handheld electric power tool Download PDF

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Publication number
EP2200785B1
EP2200785B1 EP08774820.8A EP08774820A EP2200785B1 EP 2200785 B1 EP2200785 B1 EP 2200785B1 EP 08774820 A EP08774820 A EP 08774820A EP 2200785 B1 EP2200785 B1 EP 2200785B1
Authority
EP
European Patent Office
Prior art keywords
power tool
electric power
handheld electric
capacitive switch
switch
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Not-in-force
Application number
EP08774820.8A
Other languages
German (de)
French (fr)
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EP2200785A1 (en
Inventor
Reiner Krapf
Bjoern Haase
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP2200785A1 publication Critical patent/EP2200785A1/en
Application granted granted Critical
Publication of EP2200785B1 publication Critical patent/EP2200785B1/en
Not-in-force legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25F—COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR
    • B25F5/00—Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B23/00—Portable grinding machines, e.g. hand-guided; Accessories therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
    • H01H9/02—Bases, casings, or covers
    • H01H9/06—Casing of switch constituted by a handle serving a purpose other than the actuation of the switch, e.g. by the handle of a vacuum cleaner
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2239/00—Miscellaneous
    • H01H2239/006—Containing a capacitive switch or usable as such
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2300/00—Orthogonal indexing scheme relating to electric switches, relays, selectors or emergency protective devices covered by H01H
    • H01H2300/024—Avoid unwanted operation

Definitions

  • the invention relates to an electric power tool with a main switch and at least one safety device for releasing the function of the electric power tool according to the preamble of claim 1.
  • a machine is made EP 1 595 661 A known.
  • the invention relates to a method for operating an electric hand-held power tool, which comprises a main switch and at least one safety device for enabling the function of the electric hand-held power tool.
  • Electric hand tool machines and methods for operating these are known from the prior art.
  • the main switch of an electric handheld power tool serves for switching on and off and optionally for stepped or stepless adjustment of an operating parameter of the electric handheld power tool.
  • the rotational speed of an electric motor of the electric handheld power tool can be adjusted by means of the main switch.
  • the safety device is integrated into the electric hand tool machine in such a way that it can release or prevent the function of the electric hand tool, so that in the latter case, despite actuated main switch, the electric hand tool is not usable, since the function is not released by the safety device.
  • the safety device for example, unintentional switching on the electric hand tool machine should be prevented.
  • two-stage so-called two-stage
  • switch-on levels are necessary to turn the device on.
  • This may be two separate or spaced mechanical switches attached to the power hand tool, or a switch combining two switching functions.
  • the latter can for example be designed so that first a pressing, then turning or vice versa must be done to activate the electric hand tool.
  • Such combined switches are complicated and impractical to operate, especially when the user of the power hand tool must wear gloves at work to make it difficult to operate such a combined switch.
  • a handle assembly having a handle outer surface including a handle base body, which includes a hand inner surface support portion, wherein at least one pressure sensitive zone is formed in the region of the hand inner surface support portion for generating a signal indicative of the handle grip condition.
  • the electric hand tool machine is defined in claim 1 and has at least one capacitive switch associated with a handle of the electric hand tool. It is thus provided a non-contact safety device for the electric hand tool, which is associated with the handle of the electric hand tool and can thereby detect whether a user's hand is applied to the handle or whether a user holds the electric hand tool in the proper manner. Due to the advantageous embodiment, it does not matter whether the user wears gloves, as a direct contact with the user's hand is not necessary. The hand only has to dive into the electric field of the capacitive switch.
  • a handle of the electric hand tool machine is understood to be any area of the electric hand tool machine intended for holding and / or operating. This may be both a region of the electric hand-held power tool arranged on the housing of the electric hand-held power tool and a (grip) region projecting from the housing.
  • the handle of the EP 1 595 661 A1 is formed by a tube of electrically non-conductive material, wherein in the tube, an electromagnetic sensor is arranged, the output of which changes when touched at each position of the handle.
  • a sensor is in the EP 1 595 661 A1
  • a capacitive sensor with two electrodes proposed.
  • the inventive according to claim 1 electric hand tool has at least one of a handle of the electric hand tool machine associated capacitive switch. It is thus provided a non-contact safety device for the electric hand tool, which is associated with the handle of the electric hand tool and can thereby detect whether a user's hand is applied to the handle or whether a user holds the electric hand tool in the proper manner. Due to the advantageous embodiment, it does not matter whether the user wears gloves, as a direct contact with the user's hand is not necessary. The hand only has to dive into the electric field of the capacitive switch. If the capacitive switch is actuated or detects the capacitive switch, the hand of a user, the function of the electric power tool is released, so that the user receives the desired function upon actuation of the main switch.
  • a handle of the electric hand tool machine is understood to be any area of the electric hand tool machine intended for holding and / or operating. This may be both a region of the electric hand-held power tool arranged on the housing of the electric hand-held power tool and a (grip) region projecting from the housing.
  • the function of the electric hand-held power tool is a touch operation and / or a rest operation.
  • a touch operation is to be understood in this case the operation of the electric power tool by an active operation of the main switch by a user.
  • the latching operation can be realized for example by a mechanical engagement of the main switch, wherein the safety device releases the locking.
  • an "electrical" locking is conceivable.
  • the capacitive switch has a dielectric sensor region arranged on the handle.
  • the capacitive switch is thus designed such that it has a sensor region for detecting the dielectric.
  • the capacitive switch advantageously has a measuring capacitor whose capacitance changes between the capacitor plates by introducing a dielectric, in particular by introducing the hand of the user. The then additionally measured current serves as a measuring signal for the capacitive switch.
  • an alternating voltage is applied to the measuring capacitor and the impedance of the system is measured.
  • the dielectric sensor region which is determined by the arrangement of the measuring capacitor, is advantageously arranged on the electric hand tool or the handle of the electric hand tool that the user can operate both the capacitive switch and the main switch with one hand.
  • the capacitive switch is advantageously located at a location of the power hand tool that requires the user to hold / guide and operate the power hand tool with both hands.
  • the capacitive switch is advantageously located at a location of the power hand tool that requires the user to hold / guide and operate the power hand tool with both hands.
  • the electric hand tool one of the two arrangements mentioned may make sense. Of course, a combination of the two options is conceivable.
  • the capacitive switch has at least two spaced-apart dielectric sensor regions. These can be assigned to a handle or in each case a handle. Advantageously, they are associated with a handle, so that it can be detected or determined whether the user wraps around the handle of the electric hand-held power tool, for example with the whole hand. In this case, therefore, the user would have to completely enclose the handle by hand in order to release the function of the electric hand-held power tool or to actuate the safety device.
  • the dielectric sensor areas of the capacitive switch on the handle are substantially opposite each other.
  • the capacitive switch has an exciter electrode and at least one receiver electrode. These are designed and / or arranged such that the hand of the user or their position can be detected. Conveniently, the potential of the excitation electrode and the receiver electrode is related to the grounding potential of the electric hand tool.
  • the operating frequency of the capacitive switch is chosen to be higher than the mains frequency in order to avoid interference and to enable a safe fading electrical low-frequency noise. Furthermore, the operating frequency is advantageously chosen low enough, so that inexpensive components can be used for example for the audio frequency range.
  • the signal form of the excitation voltage is irrelevant. Both a sinusoidal signal and other signal forms, such as a rectangular signal, may be used.
  • the capacitive switch is designed as a multi-channel capacitive switch.
  • the capacitive switch has a plurality of electrode pairs and thus a plurality of dielectricity sensor regions.
  • the provision of a plurality of dielectric sensor regions has the additional advantage that, for example, when placing the electric hand tool with one side on a metallic substrate, only one measuring capacitor Dielektrizticians capableung detected, and an unintentional activation of the electric power tool or a release of the main switch is prevented.
  • the capacitive switch advantageously has a plurality of excitation electrodes operated at different frequencies. Wherein these interact with a corresponding number of receiver electrodes or advantageously with a smaller number or only one receiver electrode.
  • the multi-channel capacitive switch can be formed in a simple manner.
  • a separate measuring amplifier is required for each receiver electrode.
  • the safety device at least one of a handle of the electric hand tool machine associated capacitive switch, as described above, used.
  • the advantageous method can be detected without contact, whether a user holds the electric power tool in a designated manner or operated. If the capacitive switch is "actuated", then the safety device releases the function of the electric hand-held power tool so that, for example, an electric motor of the electric hand-held power tool can be activated.
  • the capacitive switch or the safety device then gives the function of the electric handheld power tool when a predetermined dielectricity of at least one dielectricity sensor region of the capacitive switch is changed or exceeded.
  • a change in the dielectric for example, a measuring capacitor of the capacitive switch detected, so the function of the electric power tool is released.
  • a limit for the dielectric which must be exceeded, so that the function of the electric power tool is released.
  • the capacitive switch releases the function of the electric handheld power tool when a predetermined dielectricity of the at least one dielectric sensor region is detected.
  • the predetermined dielectricity is also to be understood as a dielectricity range.
  • the capacitive switch can be designed such that it can only be activated or actuated by the human hand of a user.
  • the safety device releases the function of the electric hand-held power tool on actuation of the capacitive switch for a certain time and / or for the duration of the actuation of the main switch.
  • the safety device releases the function of the electric machine for a certain time or as long as the main switch is operated.
  • a combination of the two options is provided, whereby, for example, the electric hand tool after a (one-time) operation of the capacitive switch for a certain period of time is usable, and after failure of an operation of the main switch within the period of time, the capacitive switch must be pressed again to the function the handheld power tool (again) release.
  • the capacitive switch releases the function of the electric power tool for the duration of its operation.
  • the electric power tool is turned off as soon as the user removes his hand from the handle having the capacitive switch. This has advantages, for example, when the user is torn out of the hand of the electric hand tool machine during operation.
  • the FIG. 1 shows in an embodiment of an electric hand tool 1, which is designed as angle grinder 2.
  • the angle grinder 2 has a housing 3, in which an electric motor 4 and a control circuit not shown here are arranged.
  • the housing 3 is substantially cylindrical.
  • a transmission housing 5 connects to the housing 3, wherein in the transmission housing 5 cooperating with the electric motor 4 transmission is arranged, which transmits the drive power of the electric motor 4 on a grinding wheel 6 of the angle grinder 2.
  • a co-operating with the control circuit main switch 7 for actuating the angle grinder 2 is further arranged.
  • the main switch 7 is designed as a mechanically operated switch, for example as a common pressure lever switch.
  • the electric hand tool 1 and the angle grinder 2 further comprises a safety device 8, which cooperates with the main switch 7 or with the electric motor 4 such that the function of the electric power tool 1 or angle grinder 2 only then is released when a capacitive switch 9 is also actuated or activated by the user. This prevents, for example, that the electric hand tool 1 is activated inadvertently.
  • the capacitive switch 9 has, in the present embodiment, two spaced-apart dielectric sensor regions 10 and 11. Each of the sensor regions 10, 11 is formed by an exciter electrode 12 and a receiver electrode 13 cooperating therewith.
  • the electrodes 12, 13 are not visible from the outside arranged in the housing 3, so that the surface of the housing 3 design can be made sophisticated design, for example by marking the sensor areas 10,11 on the outside of the housing 3.
  • the internal arrangement is the Capacitive switch beyond not susceptible to wear.
  • the sensor regions 10, 11 or the capacitive switch 9 are arranged in the region of a handle 14.
  • the measuring capacitor 15 consists of two or more conductive materials or is designed as at least one electrically conductive coating on the inside of the housing 3.
  • the control circuit which controls it.
  • a DC voltage or preferably an AC voltage can be applied to the measuring capacitor 15.
  • the impedance of the system is detected.
  • the potentials of the exciter electrode 12 and the receiver electrode 13 are related to the ground potential of the electric hand tool 1.
  • the user In operation, the user must also actuate or activate the capacitive switch 9 in addition to the main switch 7, so that the function of the electric power tool 1 is released.
  • the function of the electric hand tool machine in addition to or instead of a touch operation, as described above, may also be a latching operation.
  • the arrangement of the sensor areas 10 and 11 at substantially two opposite sides of the handle 14 assumes that the user is doing the Electric hand tool 1 by hand "completely” encloses.
  • the release of the function can be done by the main switch 7 or the electric motor 4 are released electronically or mechanically upon activation of the capacitive switch 9.
  • the capacitive switch 9 is arranged on a projecting from the housing 3 second handle, so that the user must hold the electric hand tool 1 with two hands in order to use them.
  • the FIG. 2 shows an exemplary structure of the capacitive switch 9 and the safety device 8 in a schematic representation.
  • the capacitive switch 9 is designed as a multi-channel switch, wherein two exciter electrodes 12 cooperate with a receiver electrode 13. Wherein the first excitation electrode 16 is applied to a different frequency than the second excitation electrode 17. Both exciter electrodes 12 are connected to the voltage source and coupled to the receiver electrode 13 in a variable degree.
  • the safety device 8 or the capacitive switch 9 furthermore has a frequency-selective measuring amplifier 18, which amplifies and spectrally filters the voltages or currents applied to the exciter electrodes 12.
  • the safety device 8 has a discriminator 19, which compares the amplitude at the output of the frequency-selective measuring amplifier 18 with a reference value and on the basis of the result, whether the capacitive coupling between the excitation electrodes 12 and the receiver electrode 13 increases by the encompassing of the tool by hand and the tool can be used or whether no increase in the capacitive coupling has been observed and the tool for this reason must not be put into operation.
  • the user is now the main switch 7 so verifies the safety device 8 whether the electric hand tool 1 may be used or whether the capacitive switch 9 has been actuated.
  • the operating frequency f of the exciter electrodes 12 is expediently chosen to be much higher than the mains frequency in order to avoid interference and / or to allow safe fading of low frequency electrical noise. Particularly advantageous is the frequency range of 2 kHz to 10 kHz.
  • the excitation voltage may be both a sinusoidal signal and a signal having a different signal form, such as a rectangular signal.
  • FIG. 3 shows a further exemplary, schematically illustrated construction of the safety device 8 and the capacitive switch 9. From the preceding figures known elements are also provided here with the same reference numerals.
  • an excitation electrode 12 which is fed by an AC voltage source 21 with, for example, 5V and a frequency f.
  • the signal of the receiver electrode 13 is fed to the discriminator 19 via a bandpass filter 22.
  • the discriminator 19 compares the obtained signal with a reference signal 23 and, as described above, discriminates whether the function of the electric power tool 1 should be released (step 24).
  • the (audio frequency) exciter signal is first generated at a digital output of a microcontroller and this digital output is connected to the exciter electrode 12.
  • the tapped at the receiver electrode 13 voltage level is then converted in a measuring amplifier (18) in its impedance.
  • the impedance converter hides interference signals by a suitable frequency characteristic itself.
  • the output signal of the measuring amplifier 18 is then digitized in an analog-to-digital converter and sampled frequency-synchronously to a multiple exciter frequency f.
  • a numerical value is then calculated on the basis of the digitized measured values, which corresponds to the AC voltage level at the receiver electrode 13 at the frequency f. This voltage level can then be compared with a reference value (23). Exceeds the voltage level at the receiver electrode 13, the reference value 23, a signal is activated at a digital output, which unlocks the use of the electric power tool 1.
  • the digital filtering in the microcontroller extracts from the digitized voltage levels at the receiver electrode 13 several numerical values which correspond to the voltage amplitudes at the different exciter frequencies of the excitation electrode 12 (16, 17). This can be done numerically, for example by a Fourier transformation or alternatively by suitable digital FIR or IIR filters.
  • the circuit thereby enables a plurality of comparison variables when using only a single measuring amplifier 18.
  • the narrow-band spectral filtering is realized by a multi-stage analog amplifier for this purpose.
  • FIGS. 4A and 4B show embodiments for operating the electric hand tool 1 with the safety device 8.
  • the safety device 8 serves only for unlocking the main switch 7 (or the electric motor 4) once, so that the electric hand tool 1 can continue to be used even after the capacitive switch 9 has been deactivated.
  • the capacitive switch 9 would have to be actuated again in order to use the electric hand tool 1.
  • the main switch 7 is also configured as a capacitive switch 9, for example, to further increase the ease of use for the user.
  • the shape and distribution of the dielectric sensor surfaces 10, 11 can be freely designed, but is preferably modeled on the anatomy of the human hand.
  • the sensor areas 10, 11, as in the FIG. 1 shown formed as elongated sensor areas.
  • At least one of the dielectric sensor areas can also be accommodated in a "mechanically” protected area so that it can not be easily activated or actuated. This is the case when the dielectric sensor region 10 or 11 is arranged, for example, in a recess of the housing which shields the dielectric sensor region from "direct" access.
  • the electric power tool 1 may also be designed as a drill, impact drill, saw or the like.
  • the angle grinder 2 described here represents only one possible embodiment of the electric hand tool 1.

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  • Auxiliary Devices For Machine Tools (AREA)

Description

Die Erfindung betrifft eine Elektrohandwerkzeugmaschine mit einem Hauptschalter und mindestens einer Sicherheitseinrichtung zum Freigeben der Funktion der Elektrohandwerkzeugmaschine gemäß dem Oberbegriffs des Anspruchs 1. Eine solche Maschine ist aus EP 1 595 661 A bekannt.The invention relates to an electric power tool with a main switch and at least one safety device for releasing the function of the electric power tool according to the preamble of claim 1. Such a machine is made EP 1 595 661 A known.

Ferner betrifft die Erfindung ein Verfahren zum Betreiben einer Elektrohandwerkzeugmaschine, die einen Hauptschalter und mindestens eine Sicherheitseinrichtung zum Freigeben der Funktion der Elektrohandwerkzeugmaschine umfasst.Furthermore, the invention relates to a method for operating an electric hand-held power tool, which comprises a main switch and at least one safety device for enabling the function of the electric hand-held power tool.

Stand der TechnikState of the art

Elektrohandwerkzeugmaschinen sowie Verfahren zum Betreiben dieser sind aus dem Stand der Technik bekannt. Der Hauptschalter einer Elektrohandwerkzeugmaschine dient dabei zum Ein- und Ausschalten und gegebenenfalls zum gestuften oder stufenlosen Einstellen eines Betriebsparameters der Elektrohandwerkzeugmaschine. Beispielsweise kann mittels des Hauptschalters die Drehzahl eines Elektromotors der Elektrohandwerkzeugmaschine eingestellt werden. Auch ist es bekannt, Elektrohandwerkzeugmaschinen mit einer Sicherheitseinrichtung zu versehen, die beispielsweise mit dem Hauptschalter zusammenwirkt, wie in der DE 102 32 934 A1 offenbart. Die Sicherheitseinrichtung ist dabei derart in die Elektrohandwerkzeugmaschine integriert, dass sie die Funktion der Elektrohandwerkzeugmaschine freigeben oder unterbinden kann, sodass im letzteren Fall trotz betätigtem Hauptschalter die Elektrohandwerkzeugmaschine nicht benutzbar ist, da die Funktion durch die Sicherheitseinrichtung nicht freigegeben ist. Durch die Sicherheitseinrichtung soll beispielsweise unbeabsichtigtes Einschalten der Elektrohandwerkzeugmaschine verhindert werden. Hierzu ist es untere Anderem bekannt, sogenannte zweistufigeElectric hand tool machines and methods for operating these are known from the prior art. The main switch of an electric handheld power tool serves for switching on and off and optionally for stepped or stepless adjustment of an operating parameter of the electric handheld power tool. For example, the rotational speed of an electric motor of the electric handheld power tool can be adjusted by means of the main switch. It is also known to provide electric hand tool machines with a safety device which cooperates, for example, with the main switch, as in the DE 102 32 934 A1 disclosed. The safety device is integrated into the electric hand tool machine in such a way that it can release or prevent the function of the electric hand tool, so that in the latter case, despite actuated main switch, the electric hand tool is not usable, since the function is not released by the safety device. By the safety device, for example, unintentional switching on the electric hand tool machine should be prevented. For this it is known lower other, so-called two-stage

Neue Beschreibungsseite 2 (Reinschrift)New description page 2 (fair copy)

mechanische Schalter zu verwenden, sodass zwei Einschaltstufen notwendig sind um das Gerät einzuschalten. Hierbei kann es sich um zwei voneinander getrennte beziehungsweise beabstandete mechanische Schalter, die an der Elektrohandwerkzeugmaschine angebracht sind, handeln, oder um einen zwei Schaltefunktionen kombinierenden Schalter. Letzterer kann beispielsweise derart konstruiert sein, dass zuerst ein Drücken, dann ein Drehen oder umgekehrt erfolgen muss, um die Elektrohandwerkzeugmaschine zu aktivieren. Derartige kombinierte Schalter sind jedoch kompliziert und unpraktisch in der Bedienung, insbesondere wenn der Benutzer der Elektrohandwerkzeugmaschine bei der Arbeit Handschuhe tragen muss, die das Betätigen eines derartigen kombinierten Schalters erschweren.To use mechanical switches, so two switch-on levels are necessary to turn the device on. This may be two separate or spaced mechanical switches attached to the power hand tool, or a switch combining two switching functions. The latter can for example be designed so that first a pressing, then turning or vice versa must be done to activate the electric hand tool. However, such combined switches are complicated and impractical to operate, especially when the user of the power hand tool must wear gloves at work to make it difficult to operate such a combined switch.

Aus DE 102 32 934 A ist Handgriffeinrichtung mit einer, einen Handgriff-Basiskörper einschließenden Handgriffaußenfläche bekannt, die einen Hand-Innenflächenauflageabschnitt umfasst, wobei im Bereich des Hand-Innenflächenauflageabschnitts wenigstens eine drucksensitive Zone ausgebildet ist, zur Generierung eines hinsichtlich des Handgriff-Greifzustands indikativen Signales.Out DE 102 32 934 A A handle assembly is known having a handle outer surface including a handle base body, which includes a hand inner surface support portion, wherein at least one pressure sensitive zone is formed in the region of the hand inner surface support portion for generating a signal indicative of the handle grip condition.

Offenbarung der ErfindungDisclosure of the invention

Die Elektrohandwerkzeugmaschine wird in Anspruch 1 definiert und weist mindestens einen einem Handgriff der Elektrohandwerkzeugmaschine zugeordneten kapazitiven Schalter auf. Es ist somit eine berührungslos arbeitende Sicherheitseinrichtung für die Elektrohandwerkzeugmaschine vorgesehen, die dem Handgriff der Elektrohandwerkzeugmaschine zugeordnet ist und dadurch erfassen kann, ob eine Hand eines Benutzers an dem Handgriff anliegt beziehungsweise ob ein Benutzer die Elektrohandwerkzeugmaschine in vorschriftsmäßiger Art und Weise hält. Aufgrund der vorteilhaften Ausbildung spielt es dabei keine Rolle, ob der Benutzer Handschuhe trägt, da ein direkter Kontakt mit der Hand des Benutzers nicht notwendig ist. Die Hand muss lediglich in das elektrische Feld des kapazitiven Schalters eintauchen. Wird der kapazitive Schalter betätigt beziehungsweise erfasst der kapazitive Schalter die Hand eines Benutzers, wird die Funktion der Elektrohandwerkzeugmaschine freigegeben, sodass der Benutzer bei Betätigen des Hauptschalters die gewünschte Funktion erhält. Unter einem Handgriff der Elektrohandwerkzeugmaschine ist hierbei jeder zum Halten und/oder Bedienen vorgesehene Bereich der Elektrohandwerkzeugmaschine zu verstehen. Dabei kann es sich sowohl um einen an dem Gehäuse der Elektrohandwerkzeugmaschine angeordneten Bereich der Elektrohandwerkzeugmaschine als auch um einen von dem Gehäuse abstehenden (Griff-) Bereich handeln.The electric hand tool machine is defined in claim 1 and has at least one capacitive switch associated with a handle of the electric hand tool. It is thus provided a non-contact safety device for the electric hand tool, which is associated with the handle of the electric hand tool and can thereby detect whether a user's hand is applied to the handle or whether a user holds the electric hand tool in the proper manner. Due to the advantageous embodiment, it does not matter whether the user wears gloves, as a direct contact with the user's hand is not necessary. The hand only has to dive into the electric field of the capacitive switch. If the capacitive switch is actuated or detects the capacitive switch, the hand of a user, the function of the electric power tool is released, so that the user receives the desired function upon actuation of the main switch. In this context, a handle of the electric hand tool machine is understood to be any area of the electric hand tool machine intended for holding and / or operating. This may be both a region of the electric hand-held power tool arranged on the housing of the electric hand-held power tool and a (grip) region projecting from the housing.

Aus der EP 1 595 661 A1 ist ein Griff mit Sicherheitsvorrichtung für ein motorangetriebens Handwerkzeug bekannt, der mit einem Schalter, vorzugsweise einem Sicherheitsschalter versehen ist, zu dessen Betätigung ein Anfassen des Griffes durch eine Bedienperson erforderlich ist. Der Griff der EP 1 595 661 A1 wird durch ein Rohr aus elektrisch nicht leitendem Material gebildet, wobei in dem Rohr ein elektromagnetischer Sensor angeordnet ist, dessen Ausgangssignal sich beim Anfassen an jeder Position des Griffes ändert. Als Sensor wird in der EP 1 595 661 A1 beispielsweise ein kapazitiver Sensor mit zwei Elektroden vorgeschlagen.From the EP 1 595 661 A1 is a handle with safety device for a motor-driven hand tool known, which is provided with a switch, preferably a safety switch, the operation of a grip of the handle by an operator is required. The handle of the EP 1 595 661 A1 is formed by a tube of electrically non-conductive material, wherein in the tube, an electromagnetic sensor is arranged, the output of which changes when touched at each position of the handle. As a sensor is in the EP 1 595 661 A1 For example, a capacitive sensor with two electrodes proposed.

Offenbarung der ErfindungDisclosure of the invention

Die erfindungsgemässe nach Anspruch 1 Elektrohandwerkzeugmaschine weist mindestens einen einem Handgriff der Elektrohandwerkzeugmaschine zugeordneten kapazitiven Schalter auf. Es ist somit eine berührungslos arbeitende Sicherheitseinrichtung für die Elektrohandwerkzeugmaschine vorgesehen, die dem Handgriff der Elektrohandwerkzeugmaschine zugeordnet ist und dadurch erfassen kann, ob eine Hand eines Benutzers an dem Handgriff anliegt beziehungsweise ob ein Benutzer die Elektrohandwerkzeugmaschine in vorschriftsmäßiger Art und Weise hält. Aufgrund der vorteilhaften Ausbildung spielt es dabei keine Rolle, ob der Benutzer Handschuhe trägt, da ein direkter Kontakt mit der Hand des Benutzers nicht notwendig ist. Die Hand muss lediglich in das elektrische Feld des kapazitiven Schalters eintauchen. Wird der kapazitive Schalter betätigt beziehungsweise erfasst der kapazitive Schalter die Hand eines Benutzers, wird die Funktion der Elektrohandwerkzeugmaschine freigegeben, sodass der Benutzer bei Betätigen des Hauptschalters die gewünschte Funktion erhält. Unter einem Handgriff der Elektrohandwerkzeugmaschine ist hierbei jeder zum Halten und/oder Bedienen vorgesehene Bereich der Elektrohandwerkzeugmaschine zu verstehen. Dabei kann es sich sowohl um einen an dem Gehäuse der Elektrohandwerkzeugmaschine angeordneten Bereich der Elektrohandwerkzeugmaschine als auch um einen von dem Gehäuse abstehenden (Griff-)Bereich handeln.The inventive according to claim 1 electric hand tool has at least one of a handle of the electric hand tool machine associated capacitive switch. It is thus provided a non-contact safety device for the electric hand tool, which is associated with the handle of the electric hand tool and can thereby detect whether a user's hand is applied to the handle or whether a user holds the electric hand tool in the proper manner. Due to the advantageous embodiment, it does not matter whether the user wears gloves, as a direct contact with the user's hand is not necessary. The hand only has to dive into the electric field of the capacitive switch. If the capacitive switch is actuated or detects the capacitive switch, the hand of a user, the function of the electric power tool is released, so that the user receives the desired function upon actuation of the main switch. In this context, a handle of the electric hand tool machine is understood to be any area of the electric hand tool machine intended for holding and / or operating. This may be both a region of the electric hand-held power tool arranged on the housing of the electric hand-held power tool and a (grip) region projecting from the housing.

Nach einer Weiterbildung der Erfindung ist die Funktion der Elektrohandwerkzeugmaschine ein Tastbetrieb und/oder ein Rastbetrieb. Unter einem Tastbetrieb ist hierbei das Betreiben der Elektrohandwerkzeugmaschine durch ein aktives Betätigen des Hauptschalters durch einen Benutzer zu verstehen. Beim Rastbetrieb reicht es aus, wenn der Benutzer den Hauptschalter einmal betätigt und einrastet beziehungsweise arretiert, wodurch die Elektrohandwerkzeugmaschine weiterläuft, auch wenn der Benutzer den Hauptschalter nicht mehr betätigt. Der Rastbetrieb kann beispielsweise durch ein mechanisches Einrasten des Hauptschalters realisiert werden, wobei die Sicherheitseinrichtung das Arretieren freigibt. Natürlich ist auch ein "elektrisches" Arretieren denkbar.According to a development of the invention, the function of the electric hand-held power tool is a touch operation and / or a rest operation. Under a touch operation is to be understood in this case the operation of the electric power tool by an active operation of the main switch by a user. When resting operation, it is sufficient if the user once operated the main switch and locks or locks, whereby the electric hand tool continues to run, even if the user does not operate the main switch. The latching operation can be realized for example by a mechanical engagement of the main switch, wherein the safety device releases the locking. Of course, an "electrical" locking is conceivable.

Der kapazitive Schalter weist einen an dem Handgriff angeordneten Dielektrizitäts-Sensorbereich auf. Der kapazitive Schalter ist also derart ausgebildet, dass er einen Sensorbereich zur Erfassung der Dielektrizität aufweist. Der kapazitive Schalter weist dazu vorteilhafterweise einen Messkondensator auf, dessen Kapazität sich zwischen den Kondensatorplatten durch Einbringen eines Dielektrikums, insbesondere durch Einbringen der Hand des Benutzers, ändert. Der dann zusätzlich gemessene Strom dient als Messsignal für den kapazitiven Schalter. Vorteilhafterweise wird an den Messkondensator eine Wechselspannung angelegt und die Impedanz des Systems gemessen. Der Dielektrizitäts-Sensorbereich, der durch die Anordnung des Messkondensators bestimmt wird, ist vorteilhafterweise derart an der Elektrohandwerkzeugmaschine beziehungsweise dem Handgriff der Elektrohandwerkzeugmaschine angeordnet, dass der Benutzer mit einer Hand sowohl den kapazitiven Schalter als auch den Hauptschalter betätigen kann. Alternativ dazu ist der kapazitive Schalter vorteilhafterweise an einer Stelle der Elektrohandwerkzeugmaschine angeordnet, die es verlangt, dass der Benutzer die Elektrohandwerkzeugmaschine mit beiden Händen halten/führen und betätigen muss. Je nach Elektrohandwerkzeugmaschine kann eine der beiden genannten Anordnungen sinnvoll sein. Natürlich ist auch eine Kombination der beiden Möglichkeiten denkbar.The capacitive switch has a dielectric sensor region arranged on the handle. The capacitive switch is thus designed such that it has a sensor region for detecting the dielectric. The capacitive switch advantageously has a measuring capacitor whose capacitance changes between the capacitor plates by introducing a dielectric, in particular by introducing the hand of the user. The then additionally measured current serves as a measuring signal for the capacitive switch. Advantageously, an alternating voltage is applied to the measuring capacitor and the impedance of the system is measured. The dielectric sensor region, which is determined by the arrangement of the measuring capacitor, is advantageously arranged on the electric hand tool or the handle of the electric hand tool that the user can operate both the capacitive switch and the main switch with one hand. Alternatively, the capacitive switch is advantageously located at a location of the power hand tool that requires the user to hold / guide and operate the power hand tool with both hands. Depending on the electric hand tool, one of the two arrangements mentioned may make sense. Of course, a combination of the two options is conceivable.

Nach einer vorteilhaften Weiterbildung der Erfindung weist der kapazitive Schalter mindestens zwei voneinander beabstandete Dielektrizitäts-Sensorbereiche auf. Diese können einem Handgriff oder jeweils einem Handgriff zugeordnet sein. Vorteilhafterweise sind sie einem Handgriff zugeordnet, sodass erfasst beziehungsweise ermittelt werden kann, ob der Benutzer den Handgriff der Elektrohandwerkzeugmaschine beispielsweise mit der ganzen Hand umschließt. Hierbei müsste also der Benutzer den Handgriff vollständig mit der Hand umschließen, um die Funktion der Elektrohandwerkzeugmaschine freizugeben beziehungsweise die Sicherheitseinrichtung zu betätigen.According to an advantageous development of the invention, the capacitive switch has at least two spaced-apart dielectric sensor regions. These can be assigned to a handle or in each case a handle. Advantageously, they are associated with a handle, so that it can be detected or determined whether the user wraps around the handle of the electric hand-held power tool, for example with the whole hand. In this case, therefore, the user would have to completely enclose the handle by hand in order to release the function of the electric hand-held power tool or to actuate the safety device.

Besonders bevorzugt liegen die Dielektrizitäts-Sensorbereiche des kapazitiven Schalters an dem Handgriff einander im Wesentlichen gegenüber.Particularly preferably, the dielectric sensor areas of the capacitive switch on the handle are substantially opposite each other.

Der kapazitive Schalter weist eine Erregerelektrode und mindestens eine Empfängerelektrode auf. Diese sind derart ausgebildet und/oder angeordnet, dass die Hand des Benutzers beziehungsweise ihre Position erfasst werden kann. Zweckmäßigerweise wird das Potential der Erregerelektrode und der Empfängerelektrode auf das Erdungspotential des Elektrohandwerkzeugs bezogen. Die Arbeitsfrequenz des kapazitiven Schalters wird dabei höher als die Netzfrequenz gewählt, um Interferenzen zu vermeiden und ein sicheres Ausblenden elektrischer Niederfrequenzstörungen zu ermöglichen. Weiterhin wird die Arbeitsfrequenz vorteilhafterweise niedrig genug gewählt, sodass preisgünstige Bauelemente zum Beispiel für den Tonfrequenzbereich zum Einsatz kommen können. Für die Funktion des kapazitiven Schalters ist die Signal-Form der Erreger-Spannung unerheblich. Es können sowohl ein sinusförmiges Signal als auch andere Signalformen, wie zum Beispiel ein rechteckförmiges Signal zum Einsatz kommen.The capacitive switch has an exciter electrode and at least one receiver electrode. These are designed and / or arranged such that the hand of the user or their position can be detected. Conveniently, the potential of the excitation electrode and the receiver electrode is related to the grounding potential of the electric hand tool. The operating frequency of the capacitive switch is chosen to be higher than the mains frequency in order to avoid interference and to enable a safe fading electrical low-frequency noise. Furthermore, the operating frequency is advantageously chosen low enough, so that inexpensive components can be used for example for the audio frequency range. For the function of the capacitive switch, the signal form of the excitation voltage is irrelevant. Both a sinusoidal signal and other signal forms, such as a rectangular signal, may be used.

Weiterhin ist vorgesehen, dass der kapazitive Schalter als mehrkanaliger kapazitiver Schalter ausgebildet ist. Hierzu weist der kapazitive Schalter mehrere Elektrodenpaare und somit mehrere Dielelektrizitäts-Sensorbereiche auf. Das Vorsehen von mehreren Dielektrizitäts-Sensorbereichen hat darüber hinaus den Vorteil, dass beispielsweise beim Ablegen der Elektrohandwerkzeugmaschine mit einer Seite auf einen metallischen Untergrund, nur ein Messkondensator eine Dielektrizitätsänderung erfasst, und ein unbeabsichtigtes Aktivieren der Elektrohandwerkzeugmaschine beziehungsweise eine Freigabe des Hauptschalters unterbunden wird.Furthermore, it is provided that the capacitive switch is designed as a multi-channel capacitive switch. For this purpose, the capacitive switch has a plurality of electrode pairs and thus a plurality of dielectricity sensor regions. The provision of a plurality of dielectric sensor regions has the additional advantage that, for example, when placing the electric hand tool with one side on a metallic substrate, only one measuring capacitor Dielektrizitätsänderung detected, and an unintentional activation of the electric power tool or a release of the main switch is prevented.

Der kapazitive Schalter weist vorteilhafterweise mehrere mit unterschiedlicher Frequenz betriebene Erregerelektroden auf. Wobei diese mit einer entsprechenden Anzahl von Empfängerelektroden oder auch vorteilhafterweise mit einer geringeren Anzahl oder nur einer Empfängerelektrode zusammenwirken. Hierdurch kann auf einfache Art und Weise der mehrkanalige kapazitive Schalter gebildet werden. Natürlich ist es auch denkbar, mehrere Empfängerelektroden und eine geringere Anzahl an Erregerelektroden, beispielsweise nur eine einzige, vorzusehen. Dabei ist jedoch für jede Empfängerelektrode ein eigener Messverstärker erforderlich.The capacitive switch advantageously has a plurality of excitation electrodes operated at different frequencies. Wherein these interact with a corresponding number of receiver electrodes or advantageously with a smaller number or only one receiver electrode. As a result, the multi-channel capacitive switch can be formed in a simple manner. Of course, it is also conceivable to provide a plurality of receiver electrodes and a smaller number of exciter electrodes, for example only a single one. However, a separate measuring amplifier is required for each receiver electrode.

Bei dem erfindungsgemäßen Verfahren gemäß Anspruch 6 für die Sicherheitseinrichtung mindestens ein einem Handgriff der Elektrohandwerkzeugmaschine zugeordneter kapazitiver Schalter, wie er oben beschrieben wurde, verwendet. Durch das vorteilhafte Verfahren kann berührungslos erfasst werden, ob ein Benutzer die Elektrohandwerkzeugmaschine in einer vorgesehenen Art und Weise hält beziehungsweise bedient. Wird der kapazitive Schalter "betätigt", so gibt die Sicherheitseinrichtung die Funktion der Elektrohandwerkzeugmaschine frei, sodass sich beispielsweise ein Elektromotor der Elektrohandwerkzeugmaschine ansteuern lässt.In the inventive method according to claim 6 for the safety device at least one of a handle of the electric hand tool machine associated capacitive switch, as described above, used. By the advantageous method can be detected without contact, whether a user holds the electric power tool in a designated manner or operated. If the capacitive switch is "actuated", then the safety device releases the function of the electric hand-held power tool so that, for example, an electric motor of the electric hand-held power tool can be activated.

Vorteilhafterweise werden als Funktion ein Tastbetrieb und/oder ein Rastbetrieb, wie oben beschrieben, durch die Sicherheitseinrichtung als Funktion der Elektrohandwerkzeugmaschine freigegeben.Advantageously, as a function of a touch operation and / or a latching operation, as described above, released by the safety device as a function of the electric power tool.

Zweckmäßigerweise gibt der kapazitive Schalter beziehungsweise die Sicherheitseinrichtung die Funktion der Elektrohandwerkzeugmaschine dann fei, wenn eine vorbestimmte Dielektrizität zumindest eines Dielektrizität-Sensorbereichs des kapazitiven Schalters verändert oder überschritten wird. Wird also eine Änderung der Dielektrizität, beispielsweise eines Messkondensators des kapazitiven Schalters, erfasst, so wird die Funktion der Elektrohandwerkzeugmaschine freigegeben. Alternativ oder zusätzlich dazu wird ein Grenzwert für die Dielektrizität vorgegeben, der überschritten werden muss, damit die Funktion der Elektrohandwerkzeugmaschine freigegeben wird.Expediently, the capacitive switch or the safety device then gives the function of the electric handheld power tool when a predetermined dielectricity of at least one dielectricity sensor region of the capacitive switch is changed or exceeded. Thus, if a change in the dielectric, for example, a measuring capacitor of the capacitive switch detected, so the function of the electric power tool is released. Alternatively or additionally specified a limit for the dielectric, which must be exceeded, so that the function of the electric power tool is released.

Nach einer Weiterbildung der Erfindung gibt der kapazitive Schalter die Funktion der Elektrohandwerkzeugmaschine frei, wenn eine vorbestimmte Dielektrizität des zumindest einen Dielektrizitäts-Sensorsbereichs erfasst wird. Unter der vorbestimmten Dielektrizität ist hierbei auch ein Dielektrizitäts-Bereich zu verstehen. Hierdurch kann der kapazitive Schalter derart ausgebildet werden, dass er lediglich durch die menschliche Hand eines Benutzers aktiviert beziehungsweise betätigt werden kann.According to a development of the invention, the capacitive switch releases the function of the electric handheld power tool when a predetermined dielectricity of the at least one dielectric sensor region is detected. In this case, the predetermined dielectricity is also to be understood as a dielectricity range. As a result, the capacitive switch can be designed such that it can only be activated or actuated by the human hand of a user.

Weiterhin ist vorgesehen, dass die Sicherheitseinrichtung die Funktion der Elektrohandwerkzeugmaschine bei Betätigung des kapazitiven Schalters für eine bestimmte Zeit und/oder für die Dauer der Betätigung des Hauptschalters freigibt. Mit anderen Worten gibt die Sicherheitseinrichtung nach einmaliger Aktivierung die Funktion die Elektromaschine für eine bestimmte Zeit oder solange der Hauptschalter betätigt wird, frei. Oder eine Kombination der beiden Möglichkeiten ist vorgesehen, wodurch beispielsweise die Elektrohandwerkzeugmaschine nach dem (einmaligen) Betätigen des kapazitiven Schalters für eine bestimmte Zeitdauer benutzbar ist, wobei nach Ausbleiben einer Betätigung des Hauptschalters innerhalb der Zeitdauer der kapazitive Schalter erneut betätigt werden muss, um die Funktion der Elektrohandwerkzeugmaschine (erneut) freizugeben.Furthermore, it is provided that the safety device releases the function of the electric hand-held power tool on actuation of the capacitive switch for a certain time and / or for the duration of the actuation of the main switch. In other words, after a single activation, the safety device releases the function of the electric machine for a certain time or as long as the main switch is operated. Or a combination of the two options is provided, whereby, for example, the electric hand tool after a (one-time) operation of the capacitive switch for a certain period of time is usable, and after failure of an operation of the main switch within the period of time, the capacitive switch must be pressed again to the function the handheld power tool (again) release.

Schließlich ist vorgesehen, dass der kapazitive Schalter die Funktion der Elektrohandwerkzeugmaschine für die Dauer seiner Betätigung freigibt. In diesem Fall wird die Elektrohandwerkzeugmaschine abgeschaltet, sobald der Benutzer die Hand von dem den kapazitiven Schalter aufweisenden Handgriff entfernt. Dies hat beispielsweise Vorteile, wenn dem Benutzer im Betrieb die Elektrohandwerkzeugmaschine aus der Hand gerissen wird.Finally, it is provided that the capacitive switch releases the function of the electric power tool for the duration of its operation. In this case, the electric power tool is turned off as soon as the user removes his hand from the handle having the capacitive switch. This has advantages, for example, when the user is torn out of the hand of the electric hand tool machine during operation.

Kurze Beschreibung der ZeichnungenBrief description of the drawings

Im Folgenden soll die Erfindung anhand einiger Figuren näher erläutert werden. Dazu zeigen

Figur 1
ein Ausführungsbeispiel einer vorteilhaften Elektrohandwerkzeugmaschine,
Figur 2
ein Ausführungsbeispiel einer möglichen Verschaltung eines kapazitiven Schalters,
Figur 3
den schematischen Aufbau eines vorteilhaften kapazitiven Schalters und
Figuren 4A und 4B
Ausführungsbeispiele von vorteilhaften Verfahren zum Betreiben der Elektrohandwerkzeugmaschine.
In the following, the invention will be explained in more detail with reference to some figures. Show this
FIG. 1
an embodiment of an advantageous electric hand tool machine,
FIG. 2
an embodiment of a possible interconnection of a capacitive switch,
FIG. 3
the schematic structure of an advantageous capacitive switch and
FIGS. 4A and 4B
Embodiments of advantageous methods for operating the electric hand tool.

Ausführungsform(en) der ErfindungEmbodiment (s) of the invention

Die Figur 1 zeigt in einem Ausführungsbeispiel eine Elektrohandwerkzeugmaschine 1, die als Winkelschleifer 2 ausgebildet ist. Der Winkelschleifer 2 weist ein Gehäuse 3 auf, in dem ein Elektromotor 4 sowie eine hier nicht näher dargestellte Steuerschaltung angeordnet sind. Das Gehäuse 3 ist im Wesentlichen zylinderförmig ausgebildet. An einer Stirnseite schließt sich ein Getriebegehäuse 5 an das Gehäuse 3 an, wobei in dem Getriebegehäuse 5 ein mit dem Elektromotor 4 zusammenwirkendes Getriebe angeordnet ist, welches die Antriebsleistung des Elektromotors 4 auf eine Schleifscheibe 6 des Winkelschleifers 2 überträgt. An dem Gehäuse 3 ist weiterhin ein mit der Steuerschaltung zusammenwirkender Hauptschalter 7 zum Betätigen des Winkelschleifers 2 angeordnet. Mittels des Hauptschalters 7 kann ein Benutzer den Winkelschleifer 2 ein- und ausschalten und gegebenenfalls die Drehzahl der Schleifscheibe 6 beziehungsweise des Elektromotors 4 einstellen. Der Hauptschalter 7 ist dabei als mechanisch zu betätigender Schalter, beispielsweise als gängiger Druck-Hebel-Schalter, ausgebildet.The FIG. 1 shows in an embodiment of an electric hand tool 1, which is designed as angle grinder 2. The angle grinder 2 has a housing 3, in which an electric motor 4 and a control circuit not shown here are arranged. The housing 3 is substantially cylindrical. On a front side, a transmission housing 5 connects to the housing 3, wherein in the transmission housing 5 cooperating with the electric motor 4 transmission is arranged, which transmits the drive power of the electric motor 4 on a grinding wheel 6 of the angle grinder 2. On the housing 3, a co-operating with the control circuit main switch 7 for actuating the angle grinder 2 is further arranged. By means of the main switch 7, a user can turn on and off the angle grinder 2 and optionally set the speed of the grinding wheel 6 and the electric motor 4. The main switch 7 is designed as a mechanically operated switch, for example as a common pressure lever switch.

Die Elektrohandwerkzeugmaschine 1 beziehungsweise der Winkelschleifer 2 weist weiterhin eine Sicherheitseinrichtung 8 auf, die mit dem Hauptschalter 7 oder mit dem Elektromotor 4 derart zusammenwirkt, dass die Funktion der Elektrohandwerkzeugmaschine 1 beziehungsweise Winkelschleifers 2 nur dann freigegeben ist, wenn ein kapazitiver Schalter 9 von dem Benutzer ebenfalls betätigt beziehungsweise aktiviert ist. Hierdurch wird beispielsweise verhindert, dass die Elektrohandwerkzeugmaschine 1 unbeabsichtigt aktiviert wird. Der kapazitive Schalter 9 weist in dem vorliegenden Ausführungsbeispiel zwei voneinander beabstandete Dielektrizitäts-Sensorbereiche 10 und 11 auf. Jeder der Sensorbereiche 10, 11 wird von einer Erregerelektrode 12 und einer damit zusammenwirkenden Empfängerelektrode 13 gebildet. Wobei die Elektroden 12, 13 von außen nicht sichtbar in dem Gehäuse 3 angeordnet sind, sodass die Oberfläche des Gehäuses 3 designtechnisch anspruchsvoll gestaltet werden kann, beispielsweise durch Markierung der Sensorbereiche 10,11 auf der Außenseite des Gehäuses 3. Durch die interne Anordnung ist der kapazitive Schalter darüber hinaus nicht verschleißanfällig. Die Sensorbereiche 10, 11 beziehungsweise der kapazitive Schalter 9 sind dabei im Bereich eines Handgriffes 14 angeordnet. Ein Elektrodenpaar bestehend aus Erregerelektrode 12 und Empfängerelektrode 13 bildet dabei einen Messkondensator 15 dessen Kapazität zwischen den Kondensatorplatten durch Einbringen eines Dielektrikums, wie zum Beispiel die Hand des Benutzers, die aus dielektrisch gut nachzuweisenden Wasser (DK=81) besteht, verändert wird. Der Messkondensator 15 besteht aus zwei oder mehreren leitfähigen Materialien oder ist als mindestens eine elektrisch leitfähige Beschichtung auf der Innenseite des Gehäuses 3 ausgeführt. Er ist mit einer elektronischen Schaltung, bevorzugt der Steuerschaltung, verbunden, die ihn ansteuert. Dabei kann an den Messkondensator 15 eine Gleichspannung oder bevorzugt eine Wechselspannung angelegt werden. Wobei beim Anlegen einer Wechselspannung die Impedanz des Systems erfasst wird. Vorteilhafterweise werden die Potentiale der Erreger-Elektrode 12 und der Empfängerelektrode 13 auf das Erdungspotential des Elektrohandwerkzeugs 1 bezogen.The electric hand tool 1 and the angle grinder 2 further comprises a safety device 8, which cooperates with the main switch 7 or with the electric motor 4 such that the function of the electric power tool 1 or angle grinder 2 only then is released when a capacitive switch 9 is also actuated or activated by the user. This prevents, for example, that the electric hand tool 1 is activated inadvertently. The capacitive switch 9 has, in the present embodiment, two spaced-apart dielectric sensor regions 10 and 11. Each of the sensor regions 10, 11 is formed by an exciter electrode 12 and a receiver electrode 13 cooperating therewith. Wherein the electrodes 12, 13 are not visible from the outside arranged in the housing 3, so that the surface of the housing 3 design can be made sophisticated design, for example by marking the sensor areas 10,11 on the outside of the housing 3. The internal arrangement is the Capacitive switch beyond not susceptible to wear. The sensor regions 10, 11 or the capacitive switch 9 are arranged in the region of a handle 14. A pair of electrodes consisting of exciter electrode 12 and receiver electrode 13 forms a measuring capacitor 15 whose capacitance between the capacitor plates by introducing a dielectric, such as the hand of the user, which consists of dielectrically good water to be detected (DK = 81) is changed. The measuring capacitor 15 consists of two or more conductive materials or is designed as at least one electrically conductive coating on the inside of the housing 3. It is connected to an electronic circuit, preferably the control circuit, which controls it. In this case, a DC voltage or preferably an AC voltage can be applied to the measuring capacitor 15. Where, when an AC voltage is applied, the impedance of the system is detected. Advantageously, the potentials of the exciter electrode 12 and the receiver electrode 13 are related to the ground potential of the electric hand tool 1.

Im Betrieb muss der Benutzer neben dem Hauptschalter 7 auch den kapazitiven Schalter 9 betätigen beziehungsweise aktivieren, sodass die Funktion der Elektrohandwerkzeugmaschine 1 freigegeben wird. Wobei die Funktion der Elektrohandwerkzeugmaschine zusätzlich oder an Stelle eines Tastbetriebs, wie oben beschrieben, auch ein Rastbetrieb sein kann. Durch die Anordnung der Sensorbereiche 10 und 11 an im Wesentlichen zwei gegenüberliegenden Seiten des Handgriffes 14 wird vorausgesetzt, dass der Benutzer das Elektrohandwerkzeug 1 mit der Hand "vollständig" umschließt. Das Freigeben der Funktion kann dadurch geschehen, dass der Hauptschalter 7 oder der Elektromotor 4 elektronisch oder mechanisch bei Aktivierung des kapazitiven Schalters 9 freigegeben werden.In operation, the user must also actuate or activate the capacitive switch 9 in addition to the main switch 7, so that the function of the electric power tool 1 is released. Wherein the function of the electric hand tool machine in addition to or instead of a touch operation, as described above, may also be a latching operation. The arrangement of the sensor areas 10 and 11 at substantially two opposite sides of the handle 14 assumes that the user is doing the Electric hand tool 1 by hand "completely" encloses. The release of the function can be done by the main switch 7 or the electric motor 4 are released electronically or mechanically upon activation of the capacitive switch 9.

In einem anderen, hier nicht dargestellten Ausführungsbeispiel, ist der kapazitive Schalter 9 an einem von dem Gehäuse 3 abstehenden zweiten Handgriff angeordnet, sodass der Benutzer die Elektrohandwerkzeugmaschine 1 mit zwei Händen halten muss, um sie benutzen zu können.In another embodiment, not shown here, the capacitive switch 9 is arranged on a projecting from the housing 3 second handle, so that the user must hold the electric hand tool 1 with two hands in order to use them.

Die Figur 2 zeigt einen beispielhaften Aufbau des kapazitiven Schalters 9 beziehungsweise der Sicherheitseinrichtung 8 in einer schematischen Darstellung. Im dargestellten Ausführungsbeispiel ist der kapazitive Schalter 9 als mehrkanaliger Schalter ausgebildet, wobei zwei Erregerelektroden 12 mit einer Empfängerelektrode 13 zusammenwirken. Wobei die erste Erregerelektrode 16 mit einer anderen Frequenz beaufschlagt wird als die zweite Erregerelektrode 17. Beide Erregerelektroden 12 sind an die Spannungsquelle angeschlossen und mit der Empfängerelektrode 13 in variablem Maß gekoppelt. Die Sicherheitseinrichtung 8 beziehungsweise der kapazitive Schalter 9 weist weiterhin einen frequenzselektiven Messverstärker 18 auf, der die an den Erregerelektroden 12 anliegenden Spannungen oder Ströme verstärkt und spektral filtert. Weiterhin weist die Sicherheitseinrichtung 8 einen Diskriminator 19 auf, der die Amplitude am Ausgang des frequenzselektiven Messverstärkers 18 mit einem Referenzwert vergleicht und auf der Basis des Ergebnisses unterscheidet, ob die kapazitive Kopplung zwischen Erregerelektroden 12 und Empfängerelektrode 13 durch die Umgreifung des Werkzeugs mit der Hand vergrößert wurde und das Werkzeug genutzt werden kann oder ob keine Vergrößerung der kapazitiven Kopplung beobachtet wurde und das Werkzeug aus diesem Grund nicht in Betrieb genommen werden darf. Die den Diskriminator 19 aufweisende Steuereinheit 20 erhält als Eingangssignal ein Signal des Hauptschalters 7. Betätigt der Benutzer nunmehr den Hauptschalter 7 so überprüft die Sicherheitseinrichtung 8 ob die Elektrohandwerkzeugmaschine 1 benutzt werden darf beziehungsweise ob der kapazitive Schalter 9 betätigt wurde. Die Arbeitsfrequenz f der Erregerelektroden 12 wird zweckmäßigerweise wesentlich höher als die Netzfrequenz gewählt, um Interferenzen zu vermeiden und/oder ein sicheres Ausblenden elektrischer Niederfrequenzstörungen zu ermöglichen. Besonders vorteilhaft ist dabei der Frequenzbereich von 2 kHz bis 10 kHz. Die Erregerspannung kann sowohl ein sinusförmiges Signal als auch ein/eine andere Signalform aufweisendes Signal, wie zum Beispiel ein rechteckförmiges Signal, sein.The FIG. 2 shows an exemplary structure of the capacitive switch 9 and the safety device 8 in a schematic representation. In the illustrated embodiment, the capacitive switch 9 is designed as a multi-channel switch, wherein two exciter electrodes 12 cooperate with a receiver electrode 13. Wherein the first excitation electrode 16 is applied to a different frequency than the second excitation electrode 17. Both exciter electrodes 12 are connected to the voltage source and coupled to the receiver electrode 13 in a variable degree. The safety device 8 or the capacitive switch 9 furthermore has a frequency-selective measuring amplifier 18, which amplifies and spectrally filters the voltages or currents applied to the exciter electrodes 12. Furthermore, the safety device 8 has a discriminator 19, which compares the amplitude at the output of the frequency-selective measuring amplifier 18 with a reference value and on the basis of the result, whether the capacitive coupling between the excitation electrodes 12 and the receiver electrode 13 increases by the encompassing of the tool by hand and the tool can be used or whether no increase in the capacitive coupling has been observed and the tool for this reason must not be put into operation. The user is now the main switch 7 so verifies the safety device 8 whether the electric hand tool 1 may be used or whether the capacitive switch 9 has been actuated. The operating frequency f of the exciter electrodes 12 is expediently chosen to be much higher than the mains frequency in order to avoid interference and / or to allow safe fading of low frequency electrical noise. Particularly advantageous is the frequency range of 2 kHz to 10 kHz. The excitation voltage may be both a sinusoidal signal and a signal having a different signal form, such as a rectangular signal.

Die Figur 3 zeigt einen weiteren beispielhaften, schematisch dargestellten Aufbau der Sicherheitseinrichtung 8 beziehungsweise des kapazitiven Schalters 9. Aus den vorhergehenden Figuren bekannte Elemente sind auch hier mit den gleichen Bezugszeichen versehen. dargestellt ist eine Erregerelektrode 12 die von einer Wechselspannungsquelle 21 mit beispielsweise 5V und einer Frequenz f gespeist wird. Das Signal der Empfängerelektrode 13 wird über einen Bandpass 22 dem Diskriminator 19 zugeführt. Der Diskriminator 19 vergleicht das erhaltene Signal mit einem Referenzsignal 23 und unterscheidet, wie oben beschrieben, ob die Funktion der Elektrohandwerkzeugmaschine 1 freigegeben werden soll (Schritt 24).The FIG. 3 shows a further exemplary, schematically illustrated construction of the safety device 8 and the capacitive switch 9. From the preceding figures known elements are also provided here with the same reference numerals. shown is an excitation electrode 12 which is fed by an AC voltage source 21 with, for example, 5V and a frequency f. The signal of the receiver electrode 13 is fed to the discriminator 19 via a bandpass filter 22. The discriminator 19 compares the obtained signal with a reference signal 23 and, as described above, discriminates whether the function of the electric power tool 1 should be released (step 24).

Nach einer vorteilhaften Ausgestaltung wird das (Tonfrequenz-) Erregersignal zunächst an einem Digital-Ausgang eines Mikrocontrollers erzeugt und dieser Digital-Ausgang an die Erregerelektrode 12 angeschlossen. Der an der Empfängerelektrode 13 abgegriffene Spannungspegel wird dann in einem Messverstärker (18) in seiner Impedanz gewandelt. Vorteilhafterweise blendet der Impedanzwandler Störsignale durch eine geeignete Frequenzcharakteristik selbst aus. Das Ausgangssignal des Messverstärkers 18 wird anschließend in einem Analog-Digital-Wandler digitalisiert und frequenzsynchron zu einer vielfachen Erregerfrequenz f abgetastet. So ist ein schmalbandiges digitales Filter bei geringen Bauelementkosten und ohne Anforderungen an die Bauelementtoleranz realisierbar. Im Mikrocontroller wird dann auf der Basis der digitalisierten Messwerte ein Zahlenwert errechnet, welcher dem Wechselspannungspegel an der Empfängerelektrode 13 bei der Frequenz f entspricht. Dieser Spannungspegel kann dann mit einem Referenzwert (23) verglichen werden. Überschreitet der Spannungspegel an der Empfängerelektrode 13 den Referenzwert 23, wird an einem digitalen Ausgang ein Signal aktiviert, welches die Benutzung der Elektrohandwerkzeugmaschine 1 freischaltet.According to an advantageous embodiment, the (audio frequency) exciter signal is first generated at a digital output of a microcontroller and this digital output is connected to the exciter electrode 12. The tapped at the receiver electrode 13 voltage level is then converted in a measuring amplifier (18) in its impedance. Advantageously, the impedance converter hides interference signals by a suitable frequency characteristic itself. The output signal of the measuring amplifier 18 is then digitized in an analog-to-digital converter and sampled frequency-synchronously to a multiple exciter frequency f. Thus, a narrow-band digital filter with low component costs and without requirements for the component tolerance can be realized. In the microcontroller, a numerical value is then calculated on the basis of the digitized measured values, which corresponds to the AC voltage level at the receiver electrode 13 at the frequency f. This voltage level can then be compared with a reference value (23). Exceeds the voltage level at the receiver electrode 13, the reference value 23, a signal is activated at a digital output, which unlocks the use of the electric power tool 1.

Durch ein mehrkanaliges Konzept, wie zum Beispiel in der Figur 2 dargestellt, ist es möglich eine Information über die Orientierung der Hand des Benutzers zu gewinnen, beispielsweise um herauszufinden, ob die Hand des Benutzers das Elektrohandwerkzeug 1 beziehungsweise den Handgriff 14 vollständig umschließt.Through a multi-channel concept, such as in the FIG. 2 shown, it is possible to gain information about the orientation of the user's hand, for example, to find out whether the user's hand, the electric hand tool 1 and the handle 14 completely encloses.

Zur Bestimmung eines oder mehrerer Referenz-Schwellwerte erscheint es zielführend, eine kontinuierliche Bestimmung der auf den Empfängerelektroden 13 eingekoppelten Spannung durchzuführen. Das für die Bewertung der Messsignale verwendete Kriterium würde dann so aussehen, dass der jeweils aktuelle Spannungswert an der Empfängerelektrode 13 den während des Betriebes der Elektrohandwerkzeugmaschine 1 beobachteten Minimalwert um einen gewissen Betrag überschreiten muss. Auf diese Art und Weise können Fehlerfälle behandelt werden, die beispielsweise durch das Aufbringen metallischer Markierungen, wie zum Beispiel Inventarnummern im Bereich des Sensorbereichs (10, 11), entstehen können, wodurch eine permanente Vergrößerung der kapazitiven Kopplung folgen würde, ohne dass eine korrekte Haltung des Elektrohandwerkzeugs 1 durch den Bediener stattfindet.To determine one or more reference threshold values, it seems expedient to carry out a continuous determination of the voltage coupled to the receiver electrodes 13. The criterion used for the evaluation of the measurement signals would then be such that the respective current voltage value at the receiver electrode 13 must exceed the minimum value observed during operation of the electric power tool 1 by a certain amount. In this way, it is possible to deal with error cases that may arise, for example, by the application of metallic markings, such as inventory numbers in the region of the sensor area (10, 11), which would result in a permanent increase in the capacitive coupling without a correct posture of the electric hand tool 1 by the operator takes place.

Die Verwendung mehrerer Erregerelektroden 12, wie in der Figur 2 dargestellt, die mit leicht unterschiedlicher Frequenz beaufschlagt sind, führt zu einer kostengünstigen Lösung. Dabei extrahiert die digitale Filterung im Mikrocontroller aus den digitalisierten Spannungspegeln an der Empfängerelektrode 13 mehrere Zahlenwerte, welche den Spannungsamplituden bei den verschiedenen Erregerfrequenzen der Erregerelektrode 12 (16, 17) entspricht. Dies kann numerisch beispielsweise durch eine Fouriertransformation erfolgen oder alternativ durch geeignete digitale FIR- oder IIR-Filter. Die Schaltung ermöglicht dadurch mehrere Vergleichsgrößen bei Verwendung nur eines einzelnen Messverstärkers 18.The use of multiple excitation electrodes 12, as in FIG. 2 shown, which are subjected to slightly different frequency, leads to a cost-effective solution. The digital filtering in the microcontroller extracts from the digitized voltage levels at the receiver electrode 13 several numerical values which correspond to the voltage amplitudes at the different exciter frequencies of the excitation electrode 12 (16, 17). This can be done numerically, for example by a Fourier transformation or alternatively by suitable digital FIR or IIR filters. The circuit thereby enables a plurality of comparison variables when using only a single measuring amplifier 18.

Alternativ zu einer digitalisierten Auswerteschaltung ist auch eine rein analoge Umsetzung denkbar. In einer weiteren Ausführungsform wird dazu die schmalbandige spektrale Filterung durch einen mehrstufigen analogen Verstärker realisiert.As an alternative to a digitized evaluation circuit, a purely analog implementation is conceivable. In a further embodiment, the narrow-band spectral filtering is realized by a multi-stage analog amplifier for this purpose.

Alternativ zur Verwendung des Ausgangs der Wechselspannungsquelle 21 mit einer einzelnen Nominalfrequenz f als Erregersignal, ist es ebenso denkbar, eine beliebige Signalform auf die Erregerelektrode 12 aufzuschalten. In diesem Fall ist es vorteilhaft die Bandpasscharakteristik auf der Empfangseite durch einen Korrelationsfilter, insbesondere einen digitalen Korrelationsfilter zu ersetzen. Durch Verwendung eines im mathematischen Kontext als "Entfaltungs-Verfahren" beschriebenen Algorithmus ist erneut ein Rückschluss auf den Betrag der kapazitiven Verkopplung zwischen der jeweiligen Erregerelektrode 12 und Empfängerelektrode 13 möglich. Auch hier sind durch verschiedene Signalformen auf den Erregerelektroden 12 und entsprechend passenden Entfaltungs-Filter mehrkanalige Schaltungen realisierbar.As an alternative to using the output of the AC voltage source 21 with a single nominal frequency f as the excitation signal, it is also conceivable to connect an arbitrary waveform to the excitation electrode 12. In this case, it is advantageous to replace the bandpass characteristic on the receiving side by a correlation filter, in particular a digital correlation filter. By using an algorithm described in the mathematical context as a "deconvolution method", a conclusion on the amount of capacitive coupling between the respective exciter electrode 12 and receiver electrode 13 is possible again. Here, too, multi-channel circuits can be realized by means of various signal forms on the exciter electrodes 12 and correspondingly matching deconvolution filters.

Die Figuren 4A und 4B zeigen Ausführungsbeispiele zum Betreiben der Elektrohandwerkzeugmaschine 1 mit der Sicherheitseinrichtung 8. In dem in der Figur 4A dargestellten Verfahren dient die Sicherheitseinrichtung 8 lediglich zum einmaligen Entriegeln des Hauptschalters 7 (oder des Elektromotors 4), sodass auch nachdem der kapazitive Schalter 9 deaktiviert ist, die Elektrohandwerkzeugmaschine 1 weiter verwendet werden kann. Dazu wird der Hauptschalter 7 freigegeben sobald der kapazitive Schalter 9 betätigt wird (j = ja). Sobald der Hauptschalter entriegelt ist, kann der Benutzer die Elektromaschine 4 verwenden, bis er den Hauptschalter 7 deaktiviert. Dann müsste erneut der kapazitive Schalter 9 betätigt werden, um die Elektrohandwerkzeugmaschine 1 benutzen zu können.The FIGS. 4A and 4B show embodiments for operating the electric hand tool 1 with the safety device 8. In the in the FIG. 4A As shown, the safety device 8 serves only for unlocking the main switch 7 (or the electric motor 4) once, so that the electric hand tool 1 can continue to be used even after the capacitive switch 9 has been deactivated. For this purpose, the main switch 7 is released as soon as the capacitive switch 9 is actuated (j = yes). Once the main switch is unlocked, the user can use the electric machine 4 until he deactivates the main switch 7. Then, the capacitive switch 9 would have to be actuated again in order to use the electric hand tool 1.

Im Gegensatz dazu ist in dem zweiten, in der Figur 4B schematisch dargestellten Verfahren vorgesehen, dass die Sicherheitseinrichtung 8 beziehungsweise der kapazitive Schalter 9 permanent betätigt sein muss um die Elektrohandwerkzeugmaschine 1 beziehungsweise den Elektromotor 4 aktivieren zu können. Das bedeutet, dass sobald der kapazitive Schalter 9 durch Entfernen der Hand von den Dielektrizitäts-Sensorbereichen 10, 11 deaktiviert wird (n = nein), die Elektromaschine 4 ebenfalls ausgeschaltet wird, obwohl der Benutzer den Hauptschalter 7 betätigt.In contrast, in the second, in the FIG. 4B schematically illustrated method provided that the safety device 8 and the capacitive switch 9 must be permanently actuated in order to activate the electric hand tool 1 and the electric motor 4 can. That is, as soon as the capacitive switch 9 is deactivated by removing the hand from the dielectric sensor portions 10, 11 (n = no), the electric machine 4 is also turned off even though the user operates the main switch 7.

In einer vorteilhaften Weiterbildung der Elektrohandwerkzeugmaschine, ist der Hauptschalter 7 ebenfalls als kapazitiver Schalter 9 ausgestaltet, um beispielsweise den Benutzungskomfort für den Benutzer weiter zu erhöhen.In an advantageous development of the electric hand tool, the main switch 7 is also configured as a capacitive switch 9, for example, to further increase the ease of use for the user.

Die Form und Verteilung der Dielektrizitäts-Sensorflächen 10, 11 ist frei gestaltbar, ist bevorzugt aber der Anatomie der menschlichen Hand nachempfunden. Vorteilhafterweise sind die Sensorbereiche 10, 11, wie in der Figur 1 dargestellt, als längliche Sensorbereiche ausgebildet. Mindestens einer der Dielektrizitäts-Sensorbereiche kann auch in einem "mechanisch" geschützten Bereich untergebracht sein, sodass er nicht ohne Weiteres aktiviert beziehungsweise betätigt werden kann. Dies ist der Fall, wenn der Dielektrizitäts-Sensorbereich 10 oder 11 beispielsweise in einer Mulde des Gehäuses angeordnet ist, die den Dielektrizitäts-Sensorbereich vor einem "direkten" Zugriff abschirmt.The shape and distribution of the dielectric sensor surfaces 10, 11 can be freely designed, but is preferably modeled on the anatomy of the human hand. Advantageously, the sensor areas 10, 11, as in the FIG. 1 shown formed as elongated sensor areas. At least one of the dielectric sensor areas can also be accommodated in a "mechanically" protected area so that it can not be easily activated or actuated. This is the case when the dielectric sensor region 10 or 11 is arranged, for example, in a recess of the housing which shields the dielectric sensor region from "direct" access.

Natürlich kann die Elektrohandwerkzeugmaschine 1 auch als Bohrmaschine, Schlag-Bohr-Maschine, Säge oder ähnliches ausgebildet sein. Der hier beschriebene Winkelschleifer 2 stellt lediglich eine mögliche Ausführungsform der Elektrohandwerkzeugmaschine 1 dar.Of course, the electric power tool 1 may also be designed as a drill, impact drill, saw or the like. The angle grinder 2 described here represents only one possible embodiment of the electric hand tool 1.

Claims (10)

  1. Handheld electric power tool with a main switch for enabling the function of the handheld electric power tool and at least one safety device for enabling the main switch, the safety device (8) having at least one capacitive switch (9) assigned to a handle (14) of the handheld electric power tool (1), characterized in that the capacitive switch (9) has at least one exciter electrode (12) and at least one receiver electrode (13) and also at least one dielectric sensor area (10, 11), arranged on the handle (14), the operating frequency f of the exciter electrode (12) lying in a frequency range greater than the power-line frequency of the handheld electric power tool, and in particular in a frequency range from 2 kHz to 10 kHz.
  2. Handheld electric power tool according to Claim 1, characterized in that the capacitive switch (9) has at least two dielectric sensor areas (10, 11) spaced apart from one another.
  3. Handheld electric power tool according to one of the preceding claims, characterized in that the dielectric sensor areas (10, 11) lie substantially opposite one another on the handle (14).
  4. Handheld electric power tool according to one of the preceding claims, characterized in that the capacitive switch (9) is formed as a multichannel capacitive switch.
  5. Handheld electric power tool according to one of the preceding claims, characterized in that the capacitive switch (9) has a number of exciter electrodes (16, 17) operated at different frequencies.
  6. Method for operating a handheld electric power tool according to one or more of the preceding claims, the handheld electric power tool having a main switch for enabling its function and at least one safety device for enabling the main switch, characterized in that at least one capacitive switch which is assigned to a handle of the handheld electric power tool, comprises at least one exciter electrode (12) and at least one receiver electrode (13) and has at least one dielectric sensor area (10, 11) arranged on the handle (14) is used for the safety device, a signal f in the frequency range greater than the power-line frequency of the handheld electric power tool, and in particular in a frequency range from 2 kHz to 10 kHz, being applied to the exciter electrode (12).
  7. Method according to Claim 6, characterized in that the capacitive switch enables the function of the handheld electric power tool when a predetermined dielectricity of at least one dielectric sensor area of the capacitive switch changes and/or is exceeded.
  8. Method according to either of the preceding Claims 6 and 7, characterized in that the capacitive switch enables the function of the handheld electric power tool when a predetermined dielectricity of the at least one dielectric sensor area is recorded.
  9. Method according to one of the preceding Claims 6 to 8, characterized in that the safety device enables the function of the handheld electric power tool when the capacitive switch is actuated for a certain time and/or for the duration of the actuation of the main switch.
  10. Method according to one of the preceding Claims 6 to 9, characterized in that the safety device enables the function of the handheld electric power tool when the capacitive switch is actuated for the duration of its actuation.
EP08774820.8A 2007-09-05 2008-07-07 Handheld electric power tool and method for operating a handheld electric power tool Not-in-force EP2200785B1 (en)

Applications Claiming Priority (2)

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DE102007042221A DE102007042221A1 (en) 2007-09-05 2007-09-05 Electric hand tool and method for operating an electric hand tool
PCT/EP2008/058746 WO2009030541A1 (en) 2007-09-05 2008-07-07 Handheld electric power tool and method for operating a handheld electric power tool

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DE102009057935B4 (en) * 2009-12-11 2015-07-09 Ident Technology Ag Device and method for detecting gripping of a handheld device by a hand
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DE102010043519B4 (en) * 2010-11-05 2012-10-18 Ident Technology Ag Method and sensor device for detecting a grasping of a hand-held device
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