A frequency synthesizer for a WLAN transceiver is disclosed that may be used to generate 5.4 GHz and 2.4 GHz signals. The frequency synthesizer may be configured to minimize VCO pulling by using VCO operating frequencies that are not integer multiples of the RF bands. Further, the frequency synthesizer may be configured to minimize interference with other frequency bands used by existing wireless systems.

A modulator generates a baseband digital signal from an information-bearing digital signal. The baseband signal has time-varying phase and amplitude defined by a sequence of complex data words, each having an in-phase (I) component and a quadrature (Q) component. A noise-shaping modulator generates a noise-shaped digital signal from the baseband digital signal such that quantization noise in the noise-shaping modulator is attenuated by a spectral null of its noise transfer function. The spectral null is selected by a noise-shaping parameter corresponding to a selected one of a plurality of output frequencies. A signal converter generates an analog signal conveying the information of the information-bearing digital signal on an analog carrier signal having the selected output frequency.

A signal generator for a transmitter or a receiver for transmitting or receiving RF-signals according to a given communication protocol includes an oscillator and a mismatch compensator. The oscillator is configured to provide a signal generator output signal having a signal generator output frequency and comprises a fine tuning circuit for providing a fine adjustment of the signal generator output frequency based on a fine tuning signal and a coarse tuning circuit for providing a course adjustment of the signal generator output frequency based on a coarse tuning signal. The mismatch compensator is configured to receive the signal generator output signal and compensate a frequency mismatch between a desired signal generator output frequency and the signal generator output frequency generated by the oscillator by providing the fine tuning signal for changing the state of the fine tuning circuit of the oscillator and by providing the coarse tuning signal for changing a state of the coarse tuning circuit of the oscillator. The mismatch compensator provides the coarse tuning signal during a guard period defined in the given communication protocol, during which no RF-signals are transmitted by the transmitter or no RF-signals are to be received by the receiver, such that the state of the coarse tuning circuit is changed within the guard period.

A circuit includes a switched modulator stage combining an information signal with a square wave carrier to produce a first modulated signal; and a second modulation stage forming additional steps in the first modulated signal to produce a second modulated signal.

A rail-to-rail comparator including a first comparison unit connected to a first terminal and configured to compare differential input signals to differential reference voltages; a second comparison unit connected to a second terminal and configured to compare the differential input signals to the differential reference voltages; and an output unit configured to be driven in response to a clock signal and to generate a complementary output signal according to comparison results of the first and second comparison units.

An example PWM includes a driver and a two-way oscillator. The oscillator includes, a first frequency adjust current source, a second frequency adjust current source, a capacitor, a switching reference and a comparator. The capacitor integrates a frequency adjust current by charging with the first frequency adjust current source. The capacitor subsequently integrates a second frequency adjust current by discharging with the second frequency adjust current source. The switching reference outputs a first reference voltage and a second reference voltage responsive to an oscillator signal. The comparator compares the output of the switching reference with a voltage on the capacitor. The first and second frequency adjust current sources vary the first and second frequency adjust currents to vary the frequency of the PWM signal to spread energy of switching harmonics over a frequency band and to reduce EMI.

Methods and apparatus for translating duty cycle information in duty-cycle-modulated signals to higher frequencies or higher data rates. An exemplary duty cycle translator includes a duty cycle evaluator, a high-speed digital counter, and a comparator. The duty cycle evaluator generates a first digital number representing a duty cycle of a low-frequency input duty-cycle-modulated (DCM) signal. The comparator compares the first digital number to a second digital number generated by the high-speed digital counter, and generates, based on the comparison, an output DCM signal having a higher frequency or data rate than the frequency or data rate of the low-frequency input DCM signal but a duty cycle that is substantially the same as the duty cycle of the low-frequency input DCM signal.

A communications transmitter includes a baseband processor configured to generate amplitude, angle, in-phase and quadrature baseband signals and a combination modulator that is configurable to modulate in the polar domain and, alternatively, in the quadrature domain. The combination modulator includes a quadrature modulator and a separate and distinct angle modulator that is configured to serve as a local oscillator for the quadrature modulator. In one embodiment of the invention the combination modulator is configured to modulate in the quadrature domain when the transmitter is operating according to a first communications condition (e.g., first transmit power level or first modulation scheme) and is configured to modulate in the polar domain when the transmitter is operating according to a second communications condition (e.g., second transmit power level or second modulation scheme).

A frequency modulator includes a digitally-controlled oscillator (DCO) arranged for producing a frequency deviation in response to a modulation tuning word and a phase-locked loop (PLL) tuning word. In addition, another frequency modulator includes a DCO and a DCO interface circuit. The DCO is arranged for producing a frequency deviation in response to an integer tuning word and a fractional tuning word. The DCO interface circuit is arranged for generating the integer tuning word and the fractional tuning word to the DCO, wherein the fractional tuning word is obtained through asynchronous sampling of a fixed-point tuning word.

Embodiments of digital high-speed bi-phase modulator and method for bi-phase modulation are generally described herein. In some embodiments, the digital high-speed bi-phase modulator comprises a high-speed digital divider, a high-speed digital multiplexer, and matched signal paths provided between the divider and the multiplexer. The high-speed digital divider is configured to receive a carrier signal and generate complementary output signals. The high-speed digital multiplexer is configured to switch between the complementary output signals and generate a bi-phase modulated output at a carrier frequency (fc) modulated with a bi-phase code. The bi-phase code may be provided to control inputs of the multiplexer.

A radio frequency generator includes a power control module, a frequency control module and a pulse generating module. The power control module is configured to generate a power signal indicating power levels for target states of a power amplifier. The frequency control module is configured to generate a frequency signal indicating frequencies for the target states of the power amplifier. The pulse generating module is configured to (i) supply an output signal to the power amplifier, (ii) recall at least one of a latest power level or a latest frequency for one of the target states of the power amplifier, and (iii) adjust a current power level and a current frequency of the output signal from a first state to a second state based on the power signal, the frequency signal, and at least one of the latest power level and the latest frequency of the power amplifier.

Provided is a method of generating a driving signal for driving a dual mode supply modulator for a power amplifier. The method includes obtaining an envelope of a complex baseband signal to be transmitted, comparing the envelope of the complex signal with a preset threshold value, when a current envelope of the complex signal is the preset threshold value or greater or when there is a result having the preset threshold value or greater in previous N comparisons, outputting a digital board output signal configured with a first logic level through a digital-to-analog converter; and when the current envelope of the complex signal is smaller than the preset threshold value and when there is no result having the preset threshold value or greater in the previous N comparisons, outputting a digital board output signal configured with a second logic level through the digital-to-analog converter.

An ultra-wide band frequency modulator is disclosed. The frequency modulator includes a direct modulation phase lock loop that receives a small component. The frequency modulator also includes a delay module that produces a plurality of delay lines. The frequency modulator further includes an edge selector that receives a large component and the plurality of delay lines.

The present invention provides a digitally controlled, current starved, pulse width modulator (PWM). In the PWM of the present invention, the amount of current from the voltage source to the ring oscillator is controlled by the proposed header circuit. By changing the header current, the pulse width of the switching signal generated at the output of the ring oscillator is dynamically controlled, where the duty cycle can vary between 50% and 90%. A duty cycle to voltage converter is used to ensure the accuracy of the system under process, voltage, and temperature (PVT) variations. The proposed pulse width modulator is appropriate for dynamic voltage scaling systems due to the small on-chip area and high accuracy under process, voltage, and temperature variations.

Systems and methods for operating with oscillators configured to produce an oscillating signal having an arbitrary frequency are described. The frequency of the oscillating signal may be shifted to remove its arbitrary nature by application of multiple tuning signals or values to the oscillator. Alternatively, the arbitrary frequency may be accommodated by adjusting operation one or more components of a circuit receiving the oscillating signal.

A memristor-based emulator including a memristor circuit for use in digital modulation that includes a first current feedback operational amplifier (CFOA) having multiple terminals in communication with a capacitor Cd and in further communication with a resistor Ri. A second CFOA having multiple terminals is in communication with the first CFOA and is adapted to be in further communication with a voltage vM to provide an input current iM for integration by a capacitor Ci. A nonlinear resistor is in communication with the second CFOA. A third CFOA having multiple terminals is in communication with the nonlinear resistor and is in further communication with the first CFOA and a resistor Rd. The third CFOA and the resistor Rd act as an inverting amplifier associated with the nonlinear resistor to increase a current gain to increase a difference between ON and OFF values of a resistance of a realized memristor.

A method for phase modulation of a carrier signal from a transmitter to a contactless transponder in which data is coded as consecutive symbols, each corresponding to a predefined number of carrier cycles, and in which a symbol time is at least two cycles of the carrier signal includes, at the transmitter, spreading a phase jump of a symbol in relation to a preceding symbol over a first part of the symbol time. The establishment of the phase jump is completed in the first part of the symbol time. The periods of the cycles are constant during a second part of the symbol time.

A modulator which has a first terminal to receive a carrier signal, a second terminal to receive a first control signal to control a frequency band of the carrier signal and a third terminal to receive a second control signal to control a modulation depth of the carrier signal.

An electromagnetic actuator comprising a core moving between a latched position and an open position, a permanent magnet, a coil designed to generate a first magnetic control flux to move the core from an open position to a latched position, and a second magnetic control flux designed to facilitate movement of the moving core from the latched position to the open position. The permanent magnet is positioned on the moving core so as to be at least partly outside the fixed magnetic circuit in which the first magnetic control flux flows in the open position, and to be at least partly inside the fixed magnetic circuit used for flow of a magnetic polarization flux of the magnet in the latched position.

A method of manufacturing a power contactor from an existing contactor having a magnetic amplifier that comprises a blowout coil and a ferromagnetic core, and an arc chute for extinguishing an arc generated by opening the existing contactor under a current load is disclosed. The method includes removing a bolt assembly from the existing contactor and at least one side plate from the existing contactor. The method also includes removing the ferromagnetic core from the existing contactor.

A circuit interrupter includes, a first contact and a second contact, the second contact being moveable relative to the first contact, a drive assembly structured to move the second contact relative to the first contact, and an erosion monitoring device including a linear transducer coupled to a portion of the drive assembly. The liner transducer is structured to generate an output signal representative of an amount of linear displacement of the portion of the drive assembly, wherein the erosion monitoring device is structured to monitor a degree of erosion of at least one of the first contact and the second contact based on the output signal.

A circuit protection device is provided for use with a circuit that includes at least one pair of conductors. The protection device is configured to generate an arc. The protection device includes at least a pair of electrode assemblies electrically coupled to the at least one pair of conductors and a conductor base to support the pair of electrode assemblies. The protection device includes a cover coupled to the conductor base and defining at least one isolation chamber, wherein the electrode assemblies are disposed within the isolation chamber. The protection device includes a containment shield moveably coupled to the cover. The containment shield defines a containment chamber configured to contain charged particles produced by the arc. The containment shield is operative to move relative to the cover in response to a change in pressure produced by the arc within the containment chamber. An isolation assembly is coupled to at least one of the cover and the containment shield and configured to prevent the cover from contacting the containment shield.

Provided is a sector gear including: a drive gear having a drive part that forms a part of a circle and has a plurality of teeth and a non-drive part that forms a remaining part of the circle and provides a non-contact angle of at least approximately 90 degrees; first and second movers forming a disconnector and a grounded breaking switch, respectively; and first and second driven gears engaged with the drive gear and respectively engaged with the first and second movers and configured to make the first mover or the second mover operate in conjunction with the drive part of the drive gear according to a direction of rotation of the drive gear, wherein an intermediate angle between the first and second movers is between approximately 90-135 degrees. The present invention can reduce the size of the gas-insulated switchgear having the sector gear.

A multi-standard flash-memory-card carrier is about the same size as a thick credit card and fits into a wallet. The multi-standard flash-memory-card carrier has bays that accept flash-memory cards. Larger bays on one side receive SD cards and a Memory Stick Duo card, while micro bays on another side of the carrier receive microSD cards and Memory Stick Micro cards. A carrier spine sandwiched between top and bottom covers has openings forming the bays. Spring-clip tabs on spring-clip fingers fit into notches on the side of the flash-memory cards to secure the flash-memory cards into the multi-standard flash-memory-card carrier to prevent loss. The spring-clip fingers are movable parts of the carrier spine that are deformed during insertion of the flash-memory cards. Both micro and standard flash-memory cards can be carried in the same multi-standard flash-memory-card carrier that can be placed in plastic sleeves for credit cards in a person's wallet.

An insertion tool packaging, includes a main body that has at least one hanging region, at least one viewing region, and at least one receiving region, which is configured at least substantially to receive at least one insertion tool. The packaging further includes at least one protective element, which is configured to at least substantially protect a user against injury.

A toilet tissue roll holder is provided having a telescoping structure that is attachable to a wall surface for providing replacement toilet tissue to a dispenser and shrouding unused rolls prior to deployment. The device includes a lowermost housing having a base surface, rounded sidewalls, an interior volume, and an open front. The lowermost housing connects to a first upstanding sidewall thereabove, which in turn supports a plurality of telescoping sidewalls that form individual toilet tissue roll containers extending upward. A viewing window is provided through at least one of the device sidewalls above the lowermost housing to allow an administrator to visualize whether a minimum number of reserve toilet paper rolls are still available. The structure is expanded and contracted depending on the number of rolls therein, while the lowermost housing and first upstanding sidewall provide the base structure that is secured to a support wall.

A carton for containing a plurality of articles. The carton comprises panels that extend at least partially around an interior of the carton. The panels comprise a top panel, a bottom panel, a first side panel, and a second side panel. The carton has a reinforced handle for grasping and carrying the carton.

Containers and components thereof for use in the medical industry and methods to manufacture the same are described. An example tab for use with a medical container includes opposing sheets sealed to define an open ended chamber into which a port is to be at least partially positioned. The port is to enable access to the medical container. The tab includes a tear seal defined by each of the opposing sheets and a first guide positioned on a first side of each of the tear seals. The tab includes a second guide positioned on a second side of each of the tear seals, wherein the first and second guides are to enable a tear to propagate substantially between the guides and adjacent the tear seals.

A multi-compartmented food storage device having a top hermetic storage compartment, a bottom hermetic storage compartment and a central hermetic storage compartment that is interposed there between. Each of the top and bottom compartments being hingedly secured to the central compartment along an upper and lower end.

A children's tray with a placement indicator includes a tray and a groove/spot formed in the tray to indicate where an eating item (including food, utensils, or dishware) is to be placed. The tray can be mounted, removably or fixedly, to a variety of child support structures, including high chairs, booster seats and bouncers and includes a wall around the periphery intended to prevent items from falling off of the tray. The groove/spot formed in the tray may be formed from of a material having a higher coefficient of friction than the material used to form the tray. The groove/spot formed in the tray may be formed from of a material having a different color than the material used to form the tray.

A storage case (100) for storing a pharmaceutical syringe unit (4) that is mounted to a pharmaceutical administering device (8) comprises a base body (1) that is open at its upper face, and a cover (2) for covering the opening in the base body (1). The base body (1) has in its interior a concave portion (5) that holds the cylindrical pharmaceutical syringe unit (4). The concave portion (5) has holders (6) that hold two ends of the pharmaceutical syringe unit (4), and a center concave portion (7) for attaching and removing the pharmaceutical syringe unit (4) and being provided in a position that corresponds to the main body portion of a stored pharmaceutical syringe unit (4). The center concave portion (7) further has a bottom part positioned lower than the holders (6), and is formed such that the pharmaceutical administering device (8) can be disposed in an upright position.

A bound system including a plurality of pages and a cover and/or divider including a bound outer edge and a plurality of free outer edges. The cover and/or divider may be bound to the plurality of pages along the bound edge. The cover and/or divider may include one or more discreet tabs extending generally outwardly relative to one of the edges. Each tab may be integrally formed from a single piece of material with the rest of the cover and/or divider. Each tab further may have an opening formed therethrough and is configured to receive at least part of a binding device therethrough to thereby couple the cover and/or divider to the binding device.

A method for producing a continuous web of printed material for use in creating mailpieces. The continuous web has a width and a length, the length comprised of a series of attached sheets. The series of attached sheets are comprising envelope sheets and rectangular content pages. The content pages are rectangular in shape and may be oriented relative to the envelope sheets in a number of different configurations. In some configurations, two sets of content pages and/or envelope sheets can be printed across the width of the web. Sheets for forming business return envelopes may be printed in series with the content pages and envelope sheets. BREs may include individualized return addresses. A control code may be printed on one or more of the sheets for a given mailpiece, providing information for controlling assembly of the mailpiece. Two sets of sheets may be printed across the width of the web by printing content pages onto the continuous web such that two end-to-end content pages are printed across the width of the web. Positioning of mail content pages and envelope sheets for a given mailpiece may be optimized based on respective processing times determined for the system.

A method and circuit arrangement for controlling the motor current in an electric motor, in particular a stepper motor, by a chopper method is provided. In the method/circuit arrangement, the motor is operated with a coil current that follows a target coil current substantially more accurately at least at the zero crossing of the coil current. The method/circuit arrangement provides a good symmetry of the sinusoidal wave shape of the coil current with respect to the zero crossing of the coil current. The method is achieved in particular by the active control of the coil current both in the direction of a predefined target coil current and opposite the direction of the predefined target coil current with respect to upper or lower desired current values and a lowering or increasing of the upper or lower desired current values.

An input receiver circuit including a single-to-differential amplifier and a semiconductor device including the input receiver circuit are disclosed. The input receiver circuit includes a first stage amplifier unit and a second stage amplifier unit. The first stage amplifier unit amplifies a single input signal in a single-to-differential mode to generate a differential output signal, without using a reference voltage. The second stage amplifier unit amplifies the differential output signal in a differential-to-single mode to generate a single output signal.

A microwave semiconductor amplifier includes a semiconductor amplifier element, an input matching circuit and an output matching circuit. The semiconductor amplifying element includes an input electrode and an output electrode and has a capacitive output impedance. The input matching circuit is connected to the input electrode. The output matching circuit includes a bonding wire and a first transmission line. The bonding wire includes first and second end portions. The first end portion is connected to the output electrode. The second end portion is connected to one end portion of the first transmission line. A fundamental impedance and a second harmonic impedance seen toward the external load change toward the one end portion. The second harmonic impedance at the one end portion has an inductive reactance. The output matching circuit matches the capacitive output impedance of the semiconductor amplifying element to the fundamental impedance of the external load.

A semiconductor package device comprises a radio frequency power transistor having an output port operably coupled to a single de-coupling capacitance located within the semiconductor package device. The single de-coupling capacitance is arranged to provide both high frequency decoupling and low frequency decoupling of signals output from the radio frequency power transistor.

A radio frequency system includes a power amplifier that outputs a radio frequency signal to a matching network via a transmission line between the power amplifier and the matching network. A sensor monitors the radio frequency signal and generates first sensor signals based on the radio frequency signal. A distortion module determines a first distortion value according to at least one of (i) a sinusoidal function of the first sensor signals and (ii) a cross-correlation function of the first sensor signals. A first correction circuit (i) generates a first impedance tuning value based on the first distortion value and a first predetermined value, and (ii) provides feedforward control of impedance matching performed within the matching network including outputting the first impedance tuning value to one of the power amplifier and the matching network.

An automatic antenna impedance matching method for a radiofrequency transmission circuit. An impedance matching network is inserted between an amplifier and an antenna. The output current and voltage of the amplifier and their phase difference are measured by a variable measurement impedance, and the complex load impedance of the amplifier is deduced from this; the impedance of the antenna is calculated as a function of this complex impedance and as a function of the known current values of the impedances of the matching network. Starting from the value found for the impedance of the antenna, new values of the matching network are calculated that allow the load to be matched to the nominal impedance of the amplifier. The measurement impedance has a value controllable by the calculation processor according to the application and notably as a function of the operating frequency and of the nominal impedance of the amplifier.

A voltage converter can be switched among two or more modes to produce an output voltage tracking a reference voltage that can be of an intermediate level between discrete levels corresponding to the modes. One or more voltages generated from a power supply voltage, such as a battery voltage, can be compared with the reference voltage to determine whether to adjust the mode. The reference voltage can be independent of the power supply voltage.

An automatic gain control device includes: a variable gain adjusting unit, for adjusting an input signal by a variable gain and outputting an adjustment result; an analog-digital converting unit, for performing analog-digital conversion on the adjustment result to obtain an analog-digital conversion result; and a gain determining unit, for determining a distribution status over a predetermined period of time of a maximum or a minimum of the analog-digital conversion result, comparing the distribution status with a first distribution condition, and if the distribution status meets the first distribution condition, then keeping the variable gain unchanged, otherwise changing the variable gain and determining newly a distribution status until the newly determined distribution status meets a second distribution condition which is at least as strict as the first distribution condition.

A damping tool holder, such as a boring head, a chuck, or a milling cutting arbor, integrates a damping device (2), in the form of an elongated body. The damping device (2) is housed in a mounting body (3), connected by one end to the tool-holder body (1) and having at its other end an end fitting (4) for mounting a tool, whereby the mounting body (3) is equipped with at least one lubricant feed pipe (32), emptying at its front end into the end fitting (4) for mounting a tool and connected at its other end to a circular groove (102) for distributing lubricant that is provided on the front surface of the tool holder (1).

An accessory for coupling to an attachment mechanism of an oscillating power tool includes a working end, an opposite rear end, and a fitment portion adjacent the rear end portion. The fitment portion includes a generally U-shaped opening having a central portion and a rearward portion open to the rear end, and configured to receive a post of a tool clamping mechanism. The fitment portion further includes a first plurality of openings in communication with and extending radially outward from the central portion, a second plurality of openings not in communication with and positioned radially outward from the central portion. The central portion, the first plurality of openings, and the second plurality of openings are configured to couple the fitment portion to a plurality of different configurations of attachment mechanisms for oscillating power tools.

An internal adapter for use in torque-limiting handles for interchangeable orthopedic tools contains a slidable collar component, house component, retaining ring, spring, driver component, cover and cam which engages a torque-limiting mechanism. A plurality of securing ball mechanisms releasably secure an orthopedic tool in the adapter, while a configuration of chamfered surfaces centrally stabilize the tool. A plurality of guiding chamfers located in a driver component rotationally secures the orthopedic tool.

An attachment apparatus for a reciprocating tool provides a tool holder having an angled bracket and a guide rod extending from the angled bracket. The guide rod can engage a travel slot on the reciprocating tool. An instrument such as a saw blade can be attached to the angled bracket or guide rod. The guide rod stabilizes the instrument during use. The travel slot can be defined integrally on the reciprocating tool or on an attachment to the tool. In some embodiments, a neck mount assembly is attached to the neck on the reciprocating tool. The neck mount assembly can include a frame and a guide plate. The guide plate can include a travel slot shaped for receiving the guide rod.

An interface between a receptacle body and an insert designed, in particular, as a tool or workpiece insert, comprises a receptacle body (2) having a cylindrical receiving bore (4), which is circumscribed by a first plane surface (6) extending at a right angle to the bore axis and in which a first cone surface (9) is arranged, said first cone surface being coaxial with the bore axis and being arranged so that its tapered end faces toward the plane surface. The insert (3) has a pin (15) that is disposed to be plugged into the receiving bore (4) and is circumscribed by a second plane surface (22). At an axial distance from the second plane surface (22), said pin has a second cone surface (22), the tapered end of said second cone surface being arranged so as to face toward the second plane surface. With the pin (15) inserted in the receiving bore (4), the two plane surfaces are in superimposed contact while the two cone surfaces (9, 22) can be biased relative to each other by limited twisting of the insert relative to the receptacle body.

A clamp arrangement for releasably securing an accessory to an oscillating power tool can include a tool body including a motor that drives an output member. A clamp assembly can include a first clamp member that moves relative to the accessory between a closed position wherein the clamp assembly retains the accessory and an open position wherein the first clamp member of the clamp assembly is offset from the accessory permitting removal of the accessory from the clamp assembly. A lever can have a user engagement portion and a pivot portion including a pivot axle. The lever can be pivotally coupled to the tool body about the pivot axle between a first position, wherein the clamp assembly is in the closed position and a second position wherein movement of the user engagement portion of the lever causes the clamp assembly to be moved to the open position.

A fastener holder includes a driving tool stem having a number of orifices, a driving tool shank engaged in the stem for engaging with a tool element and having a number of depressions formed in the shank, a number of bearing members engaged in the orifices of the stem for engaging with the depressions of the shank and for selectively anchoring the shank to the stem, and a barrel includes a relatively smaller segment for selectively engaging with the bearing members and for forcing the bearing members to engage into the depressions of the shank and to anchor and lock the driving shank to the stem and for allowing the driving shank and the tool element to be selectively rotated and driven by the stem.

The present invention discloses a kind of universal mounting hole means for different tool heads of electric tools, which are disposed on a mounting portion of the tool head, comprising a central hole and a plurality of long and narrow limiting holes which orient radially surrounding the central hole and disposed in distance with each other. Compared with the prior art, the present invention is applicable to various kinds of structures of the mounting seat on electrical tool and is more universal. It takes much convenience to people when changing different tool heads of electric tools, and it is benefit for storing.

The invention relates to a workholder (10) for holding a workpiece to be processed in a machine tool, which workholder (10) is in the form of a annular body (12) having a central through hole (14), said annular body (12) having at least one weakened area (18, 20; 34, 36, 38, 40; 50, 52, 54, 56) obtained by material removal, as well as at least one pressure chamber (22; 42, 44; 58, 60) assigned to said at least one weakened area (18, 20; 34, 36, 38, 40; 50, 52, 54, 56) that can be charged with a pressurized fluid. Said at least one weakened area (18, 20; 34, 36, 38, 40; 50, 52, 54, 56) is dimensioned and arranged so as to cause said annular body (12) to be elastically deformable in an axial and/or a radial direction (a, r). As a result, with pressure acting on said pressure chamber (22; 42, 44; 58, 60), said annular body (12) can then be deformed elastically in a well-defined manner in an axial and/or a radial direction (a, r).