Abstract: A path module for a linear motor system includes a controller coupled to one or more amplifiers that are operative to control associated windings in the module. The controller receives control information via a communications link. The controller controls the amplifier based on the received control information so as to selectively energize the associated windings in the module. In one aspect, a plurality of such modules may be connected together to form a path along which one or more stages are moveable according to energization of the windings in the path.

Abstract: A control circuit is described in which a single input terminal receives digital control signals and analog control signals. In accordance with the principles of the invention, the control circuit includes an automatic power down circuit to place the control circuit into a low power draw or “sleep” mode whenever predetermined conditions are present. The automatic power down circuit monitors the single input terminal and when no demand for motor operation occurs for a predetermined period of time, the automatic power down circuit operates to place the control circuit into the low power draw mode.

Abstract: A digitally controlled, integrated Sawyer motor forcer consists of a rigid mechanical housing containing one or more linear motor segments, integrated control electronics, cooling means, and optional feedback sensors. The integrated control electronics include digital processing circuits, an external host communication interface, power conditioning and supply circuits, forcer phase amplifiers, input/output circuits and optional feedback sensor circuits. The integrated controller also provides control, amplifier, input/output, and sensor circuits for additional external motor axes that may be attached to the forcer as needed for specialized machines. The forcer may be operated in an open-loop mode without feedback sensors, or in a closed-loop servo mode using integrated feedback sensors of various types. Cooling means are included in the forcer to reduce the temperature rise caused by power dissipation in the forcer coils and the integrated electronic elements.

Abstract: A method of controlling a stage comprising: acquiring a first moving speed of the stage based upon position information from a laser interferometer for measuring a position of the stage; controlling the moving speed of the stage based upon the first speed; determining a second moving speed of the stage based upon the number of rotation of a motor for moving the stage; controlling the moving speed of the stage based upon the second moving speed; and acquiring a ratio of the second moving speed to the first moving speed based upon the first moving speed.

Abstract: A low cost control apparatus of a contact mechanism resolving a disadvantage caused when a contact body is moved to make contact with a contacted body by an actuator. A synchronizing mechanism, which a coupling sleeve rotatably and integrally provided with an input shaft is pushed against a synchronizer ring disposed between the coupling sleeve and a synchronized gear, thereby synchronizing rotational speeds of both the components to engage them, is modeled as a collision between an inertia system object and an elastic system object. A computation coefficient (VPOLE, f in FIG. 9) of a switching function for sliding mode control having a deviation between an actual position of the coupling sleeve (Psc, d in FIG. 9) and a target position (Psc_cmd, e in FIG. 9) as a state variable is changed depending on the actual position (Psc), and thereby changing a control ability of the model against a disturbance.

Abstract: An improved arrangement for operating a contact roller (7) and an associated method, characterized inter alia by the following features: a linear motor drive (14) is allocated to the contact roller (7) in order to change positon; a force adjustment device (400) is provided for the linear motor drive (14); a suitable sensor is also provied in order to determine speed or acceleration.

Abstract: A motor is disclosed that uses magnetic propulsion for generating movement along a travel path in which the motor controller is mounted onboard the thrust block, thereby reducing connections the need for a remote motor controller. The motor includes a thrust rod extending along a travel path. The thrust rod includes an array of magnets arranged along the travel path arranged to create magnetic fields spaced along the travel path for generating magnetic propulsion when electrical coils on the thrust block are energized. The thrust block comprising a mounting body, electrical coils, and the onboard motor controller. The block may integrally provide a bearing surface that slides along a rail that may also provide the mounting structure and main support for the motor. A encoder mounted to the thrust block with a scale mounted directly to guide rail is also provided.

Abstract: An alignment stage apparatus including a base structure and a movable stage, which can move along a surface of the base structure so as not to be in contact with the base structure. The apparatus includes a plurality of power transmission coils buried under the surface of the base structure, a power reception coil attached to the movable stage to oppose the surface, a switch unit configured to sequentially switch, of the plurality of power transmission coils, those that are to be energized to feed power in accordance with a position of the movable stage, and a power feed unit configured to supply AC power to the power transmission coils to be energized through the switch unit. The power reception coil includes a plurality of power reception coils arrayed in a driving direction of the movable stage, and the power reception coils and power transmission coils are phase-shifted from each other by 180°/n where n is the number of power reception coils arrayed in the driving direction of the movable stage.

Abstract: An actuator control apparatus is provided, capable of causing a state value which changes according to the action of an actuator to match a prescribed target value. A synchronizing mechanism is modeled as the collision of an inertial system object and an elastic system object, and taking as a state amount the deviation between the actual position (Psc) of a coupling sleeve and the target position (Psc_cmd), a computation coefficient (VPOLE) of a switching function used in sliding mode control which takes the state amount as a variable is, in a first process until the coupling sleeve makes contact with a synchronizer ring, set according to the actual position (Psc) of the coupling sleeve, and in a process until the coupling sleeve engages a synchronized gear, is set such that the pressing force of the coupling sleeve matches a target pressing force.

Abstract: A control circuit is described in which a single input terminal receives digital control signals and analog control signals. In accordance with the principles of the invention, the control circuit includes an automatic power down circuit to place the control circuit into a low power draw or “sleep” mode whenever predetermined conditions are present. The automatic power down circuit monitors the single input terminal and when no demand for motor operation occurs for a predetermined period of time, the automatic power down circuit operates to place the control circuit into the low power draw mode.

Abstract: A high-speed and extremely large range positioning apparatus capable of producing motions in multiple dimensions with high precision and very high reliability. An ultra fast absolute position sensor providing instantaneous position readings with sub nanometer precision on full range of relative positions. A set of optical encoding schemas providing high encoding density and extremely fast decoding regardless of their planar positions.

Abstract: An exposure apparatus which exposes a substrate to a pattern. The apparatus includes a channel which causes pure water to flow as a coolant, a temperature adjustment unit which adjusts a temperature of the pure water flowing in the channel, and a coolant generation device which generates the pure water flowing in the channel as the coolant with a resistivity of not less than 1 M?·cm.

Abstract: A control system for controlling the work output delivered to a floor surface by a work tool associated with a floor maintenance machine, such as a burnisher, is provided. In one embodiment, a voltage regulator regulates the voltage provided to the motor assembly that drives the work tool. A current sensor monitors the motor current drawn by the motor assembly and provides a signal representative thereof to a controller. The controller also receives as an input a work selector signal representative of a desired level of work output. Based on the work selector signal and the sensed motor current, the controller provides a control signal to an actuator. In response to the control signal, the actuator raises or lowers the work tool relative to the floor as need to control the work output delivered to the floor.

Abstract: A stage assembly (220) for moving a device (200) includes a stage (208), an attraction-only type actuator pair (426) that moves the stage (208), and a control system (24). In one embodiment, the actuator pair (426) includes a first electromagnet (436F), a first conductor (438F) and a first target (440F) having a first target surface (442F). The actuator pair also includes a second electromagnet (436S), a second conductor (438S) and a second target (440S) having a second target surface (442S). The first electromagnet (436F) is positioned at a first angle ?1 relative to a first target surface (442F) and the second electromagnet (436S) is positioned at a second angle ?2 relative to the second target surface (442S). The control system (24) directs a first current to one or more of the electromagnets based on at least one of the angles ?1, ?2. Further, one or more electromagnets (436) can include a first measurement point and a second measurement point.

Abstract: A control circuit is described in which a single input terminal receives digital control signals and analog control signals. A circuit coupled to the single input provides a first output to indicate that a signal at said single input terminal is a digital signal and a second output indicates that a signal at said single input terminal is an analog signal.

Abstract: A linear motor apparatus which drives a mover of a linear motor in a stable manner, by using only information on change of relative position, without using an absolute value sensor. The apparatus has a coil array of plural phases of coils and a magnet relatively movable to the coil array, plural drivers, at least one of which being provided for each phase, to feed a current to all the same phase coils of the coil array, a sensor for measuring a change of relative position of the magnet moved by the current to the coil array, and a controller to determine the polarity of the current applied to the same phase coils based on the change of the relative position measured by the sensor, and apply a drive current to drive the magnet in a desired direction to the same phase coils.

Abstract: A movable table for supporting a work piece is allowed to move on the same plane in arbitrary directions through a table holding mechanism. Also, a feed within the same plane is supplied to the movable table by the electromagnetic driving means. Further, the movable table is stopped by an electromagnetic braking mechanism at an arbitrary position within the same plane. The electromagnetic driving means generates a feed to the movable table by a mutual magnetic effect between driven magnets and driving coils. The electromagnetic braking mechanism includes braking magnets and a nonmagnetic and conductive braking plate. A pair of the braking magnets and braking plate generates braking force by a magnetic effect between a magnetic force by an eddy current generated in the braking plate in accordance with the movement of the movable table and a magnetic force of the braking magnets.

Abstract: A linear motor apparatus which drives a mover of a linear motor in a stable manner, by using only information on change of relative position, without using an absolute value sensor. The apparatus has a coil array of plural phases of coils and a magnet relatively movable to the coil array, plural drivers, at least one of which being provided for each phase, to feed a current to all the same phase coils of the coil array, a sensor for measuring a change of relative position of the magnet moved by the current to the coil array, and a controller to determine the polarity of the current applied to the same phase coils based on the change of the relative position measured by the sensor, and apply a drive current to drive the magnet in a desired direction to the same phase coils.

Abstract: A path module for a linear motor system includes a controller coupled to one or more amplifiers that are operative to control associated windings in the module. The controller receives control information via a communications link. The controller controls the amplifier based on the received control information so as to selectively energize the associated windings in the module. In one aspect, a plurality of such modules may be connected together to form a path along which one or more stages are moveable according to energization of the windings in the path.

Abstract: A pre-compensator is provided based on a definition of abase vibration model having a motor transfer function 1 for generating motor displacement 12 from an input that is the sum of input torque and a table propelling force 10 multiplied with a reducer and Cartesian-to-polar coordinate transformation constant 14, a table transfer function 14 for multiplying a deviation 11 between an output that is the motor displacement multiplied with a reducer and polar-to-Cartesian coordinate transformation constant 2 and table displacement with a table-displacement-to-force conversion spring constant 3 to generate the table propelling force 10 and to output table displacement 7, and a base driving transfer function 5 for generating base displacement by multiplying base displacement 9 with a base-displacement-to-force conversion spring coefficient 6 and inputting the same with the table propelling force, table displacement 8 being generated from a difference between the table displacement and the base displacement.

Abstract: A coil system whose coil arrangement comprises a plurality of coaxially sequentially placed individual coil, whose wire ends are fixed on a board strip extending along the coil arrangement with a simultaneous making of contact with an electrical circuit formed thereon. Furthermore, a method for the manufacture of such a coil system and an electrodynamic linear drive fitted therewith are provided.

Abstract: A measure system for linear planar stepping motor which form with the magnetic sensor and the stable device. The characteristic of the measure system for linear planar stepping motor was that the stable device can change the residual magnetic field in the stator from random to order.

Abstract: A wireless encoder system facilitates operation and control of a motor, such as linear motor. The system includes an encoder sensor moveable with a first part of the motor. The encoder sensor is operative to sense movement of the first part relative the second part and provide an encoder signal having an electrical characteristic indicative of the sensed movement. A transmitter, which is associated with the encoder sensor, is operative to transmit a wireless transmitter signal based on the encoder signal. A remote receiver that receives the wireless transmitter signal thus may determine position and/or movement of the first part of the motor relative to a second part of the motor.

Abstract: A driving apparatus of a linear motor which reciprocally drives a movable element supported by an elastic member, includes an inverter that converts a direct current power into an alternating-current power with a specified frequency to drive the linear motor, a current detector that detects the output current of the inverter, a voltage detector that detects the output voltage of the inverter, an amplitude detector that detects an amplitude of the movable element of the linear motor, an amplitude controller adjusts the output current or output voltage in a first control cycle so that the amplitude of the movable element is a desired constant value, and a resonant controller that adjusts the output frequency of the inverter in a second control cycle which is larger than the first control cycle so that the output current of the inverter is substantially minimum on condition that the amplitude is substantially constant.

Abstract: A linear actuator includes an inner yoke, an outer yoke and a coil for generating a magnetic field between the outer yoke and the inner yoke. The outer yoke includes a first facing portion facing the inner yoke and a second facing portion which faces the inner yoke. An insulating coil bobbin around which the coil is wound includes an engaging part which engages with both the first facing portion and the second facing portion of the outer yoke. A magnet is disposed between the inner yoke and the outer yoke and a movable body is integrally connected with the magnet. An alternating magnetic field is generated by the coil such that the movable body along with the magnet is reciprocally moved in the axial direction in conjunction with the alternating magnetic field.

Abstract: A free piston gas compressor comprising a cylinder, a piston reciprocable within the cylinder and a reciprocating linear electric motor derivably coupled to the piston having at least one excitation winding. A measure of the reciprocation time of the piston is obtained, any change in the reciprocation time is detected and the power input to said excitation winding is adjusted in response to any detected change in reciprocation time.

Abstract: Compatibility of a small spring constant and large supporting load is realized, so that a stable operation is assured even if a fine-movement linear motor fails. A supporting unit, having a plurality of magnets whose same poles are arranged facing each other, is adapted to support the self-weight of a top plate on which an object to be positioned is mounted, using a repulsive force in a direction orthogonal to the facing direction of the plurality of magnets. In a characteristic curve representing the relationship between the floating force and displacement in a floating direction, the tangent inclination when the object is at a first position in the floating direction is negative, and the relationship of floating force<the self-weight holds when the object is at a second position lower than the first position.

Abstract: A control system for a linear motor adapted to accurately supply a moving window of power to the stator coils. A plurality of individually switched stator coils run the length of a linear motor to move a rotor down the long axis of the stator. Accurate inductive-based position sensors continuously provide position data for the moving rotor. A processing unit calculates a proper time delay from a source voltage peak in order to apply power to the next stator coil in the moving direction of the rotor such that no DC offshoot/undershoot occurs. The linear motor control system optionally includes a failure prevention switching scheme in which pairs of individual stator coils on opposite sides of a double-sided stator are switched together.

Abstract: A drive control method includes detecting an angular displacement of a rotor driven by a pulse motor, calculating a difference between the detected angular displacement and a preset target value of the angular displacement, and calculating a drive pulse frequency of a drive pulse signal used to drive the pulse motor. The pulse motor is driven by the drive pulse signal having the drive pulse frequency to allow the rotor at a constant angular velocity.

Abstract: To reduce the magnetic flux leakage through the gap between magnetic pole teeth of an armature so as to reduce the magnetic attraction force generated between the armature and a needle, an armature unit is provided with two magnetic poles 1 and 2, on the top of which are magnetic pole teeth 11a, 12b, 21b, and 22a protruding toward the opposing magnetic pole, where the magnetic pole teeth of the magnetic pole 1 are arranged at two heights, upper and lower, and the magnetic pole teeth of the opposing magnetic pole 2 are arranged at two heights, upper and lower, so that the magnetic flux flows upward and downward alternately between the upper and lower magnetic pole teeth. The needle 6 equipped with permanent magnets moves relatively in the gap 8 between the upper and lower magnetic pole surfaces of the armature unit.

Abstract: An apparatus for effecting non-contact linear door displacement comprising a tubular motor formed of a stator (1) formed from a plurality of magnets (21) arranged along a linear axis (15), and at least one thrust block (3) each formed of at least one electrically conductive coil encircling the stator (1) at a distance sufficient to facilitate electro-mechanical interaction between the plurality of coils and the stator (1), at least one door (5) attached to at least one of the plurality of thrust blocks (3) via a hanger (9) and the at least one door (5) capable of a movement in the direction of the linear axis (15), a rolling component (11) to enable movement of the hanger (9) in the direction of the linear axis (15), and a control mechanism (70) for sensing the position of each of the at least one door (5) and issuing an electrical control signal to each of the plurality of thrust blocks (3) so as to affect the movement of the at least one door (5).

Abstract: The present invention is directed to a coil unit of a single-acting linear engine. The coil unit includes an iron core with coils that are linked with the iron core by way of a cast compound thereby forming a molded part. The molded part is enclosed by a housing having a narrow circumferential gap formed between the housing and the molded part. Through the gap, cooling air may flow or be blasted. The air extensively cools the iron core with the coils and thermally insulates the housing from the iron core and the coils.

Abstract: The present invention relates systems and methods for compensating for errors associated with a linear motion system. The systems and methods determines one or more errors associated with the linear motion system and adjusts or corrects an input drive signal associated with the linear motion system to compensate for the one or more errors. The one or more errors of the linear motion system can include cogging errors and ripple errors. The one or more errors can be measured using a measurement system or the one or more errors can be associated with selectable coefficients or parameters, such as standard errors, or device type errors stored in a library.

Abstract: A sliding means with built-in moving-magnet linear motor is provided, realizing high-speed operation and much response ability of a table to a stationary bed, and also accurate position control of the table to the bed. With the sliding means of this invention, armature windings carry a three-phase current while a driving circuit is transferred to the external driver to make the bed slim in construction. Thus, the sliding means is reduced in overall height. A field magnet of rare earth permanent magnet is effective in raising flux density, thereby providing high propulsion for the table. An encoder to monitor a position of the table is an optical encoder having an optical linear scale, which contributes to improvement in accurate monitoring. The construction in which the armature windings connected to cords, lines, and so on are placed on the stator side has no fear of causing dust and dirt, thus realizing clean environment.

Abstract: A specimen positioning mechanism (10) includes a movable stage (12) movable along multiple axes, a plate (35) connected to and supporting a specimen mounting chuck (14), multiple linear displacement mechanisms (36, 38) coupling the plate to the movable stage and mutually spaced apart at different locations between the movable stage and the plate and separately controllable to change distances between the movable stage and the plate, and a flexible member (22) coupling the movable stage and the plate. The flexible member is motion compliant in three axes of motion. The flexible member in response to linear displacements of the linear displacement mechanisms allows linear and rotational movement of the specimen mounting chuck in the three axes of motion compliance.

Abstract: A patient bed for use with at least one imaging device in which a plurality of scans to be correlated are performed, as well as in a continuous motion scanner used to compile whole-body scans. The patient bed includes a horizontal rail base and a movable patient surface. Electronic controllers are provided for controlling the horizontal and vertical positioning of the patient surface. The horizontal rail base is secured to the support proximate the scanner. A linear motor is used to generate horizontal motion of the patient bed. The linear motor is controlled using a motion controller in communication with a computer associated with the imaging device. A pedestal is provided for mounting a vertical carriage assembly. A vertical track is carried by the pedestal for controlling vertical travel of the patient bed. A motor is provided for controlling vertical motion. A pallet support member is cantilevered from the vertical carriage assembly for carrying a pallet.

Abstract: A stage assembly (10) for moving and positioning a device (26) includes a device table (20), a device holder (24) that retains the device (26), and a stage mover assembly (14). The stage assembly (10) includes one or more features that can isolate the device holder 24 and the device (26) from deformation. In some embodiments, the stage assembly (10) allows precise rotation of the device (26) between a first position (42) and a second position (44) without influencing the flatness of the device (26) and without deflecting and distorting the device (26). For example, the stage assembly (10) can include a carrier (60) and a holder connector assembly (62). The carrier (60) is supported above the device table (20) and rotates relative to the device table (20). The holder connector assembly (62) connects the device holder (24) to the carrier (60). Further, the stage assembly (10) can include a holder mover (120) that rotates the device holder (24) relative to the device table (20).

Abstract: A multiple degree-of-freedom ultra-precision (DOF) robotic system yielding either rigid body guidance or large deformation analysis (LDRS, i.e. semi-flexible and flexible robotics) is developed based on the technology of integrating a multiple DOF ultra-precision shadow robotic measurement system with a multiple DOF robot for form a closed-loop linkage chain to establish a corresponding closed-loop feedback control of end-effecter of said robotic system without the use and limitation of any target or artificial marker in work-cell as the reference. In this way, the major degrading problems that greatly drag down the positioning accuracy of a robot have been fairly resolved. The embodiment conducts the details of the development of such a multiple DOF ultra-precision robotic system for the general applications in precision engineering.

Abstract: A controlled motion system, which has a mover that is movably mounted on a track for moving along a path. Active and reactive elements are associated with the track and mover, and are configured for driving and controlling the mover along the path. A controller is operatively associated with the active elements for controlling the driving of the mover, and a position sensor is associated with the track and configured for sensing the position information corresponding to the position of the mover along the path. The sensor is associated with the controller for transmitting the position information to the controller. The sensors are also preferably configured such that the position information is transmitted from the mover through the sensor at a sensing speed faster than about 10,000 meters per second.

Abstract: The invention relates to a system and a method for performing a manufacturing operation at a predetermined position relative to a first path. The system includes a plurality of first elements mounted for movement relative to the first path. The first elements have a plurality of motion parameters which are independently controllable. Active elements are operatively associated with reactive elements to produce relative movement between the first elements and the first path, with the active elements controlling the relative movement. A controller controls the activation of the active elements and a first tool is associated with each first element for performing at least part of the manufacturing operation. The system may also include at least one second element and a second path.

Abstract: A wireless encoder system facilitates operation and control of a motor, such as linear motor. The system includes an encoder sensor moveable with a first part of the motor. The encoder sensor is operative to sense movement of the first part relative the second part and provide an encoder signal having an electrical characteristic indicative of the sensed movement. A transmitter, which is associated with the encoder sensor, is operative to transmit a wireless transmitter signal based on the encoder signal. A remote receiver that receives the wireless transmitter signal thus may determine position and/or movement of the first part of the motor relative to a second part of the motor.

Abstract: A linear motor includes a coil unit and a magnet unit. The coil unit includes an inner yoke extending in a moving direction and a coil arranged outside the inner yoke. The magnet includes a magnet arranged outside the coil. Each of the inner yoke, coil, and magnet includes a plurality of flat portions, the plurality of flat portions of the inner yoke are parallel to an axis of the coil. Each flat portion of the inner yoke is parallel to the corresponding flat portion of the coil and the corresponding flat portion of the magnet. A length of the inner yoke in a direction along the axis of the coil is longer than a length of the magnet in the direction along the axis of the coil, and the inner yoke has a prismatic structure formed by the plurality of flat portions supported by a support member.

Abstract: The present invention provides an improved design of linear motor as well as an improved control strategy. The design allows for a shorted stator, where the armature magnets are controlled to reciprocate to a greater maximum displacement that for a equivalent conventional linear motor. The control strategy is such that a minimum of external sensors are required. The linear motor is driven at its resonant frequency ensuring optionally efficient operation. A determination of the maximum current is made based on a relationship with the resonant frequency and the evaporating temperature/pressure of the vapor entering the compressor. The current is then limited to control the maximum displacement to avoid damage.

Abstract: An apparatus and method are provided for attenuating vibration when driving an object. The apparatus includes a driving device for generating a driving force to drive the object and an attenuation actuator mounted in reciprocal relationship with the driving device for generating an attenuation force substantially concurrently with the generation of the driving force. The attenuation force is generated so as to oppose and at least partially cancel a reaction force exerted by the object in response to the driving force.

Abstract: An apparatus and method for controlling a range of movement of a power piston coupled to an alternator in a linear-motion engine. The apparatus includes a power bridge and a bridge controller. The power bridge is coupled to the alternator and is used to adjust a voltage output from the alternator. The bridge controller is coupled to the power bridge and the alternator and is used to compare the voltage output from the alternator to a reference voltage that corresponds to a desired range of movement of the power piston, and generate a plurality of control signals used to control the operation of the power bridge.

Abstract: A ripple suppressor/compensator useful in the general area of motion control and applicable to a wide range of servomechanisms exhibiting a force ripple characteristics, including the permanent magnet linear motors. An adaptive feed-forward control signal is generated which compensates for the ripple force, thus allowing for more precise tracking performance to be achieved.

Abstract: Methods and apparatus for adjusting a push point of an actuator such that the push point more closely corresponds to a center-of-gravity of a stage being driven by the actuator are disclosed. According to one aspect of the present invention, a method for scanning a stage device which includes a stage, as well as an actuator which has a first coil and a second coil, includes driving the stage using the actuator and determining when driving the stage using the actuator includes driving the stage through a first location associated with the stage. The actuator is arranged to drive the stage through a push point associated with the first coil and the second coil. The method also includes altering the push point when it is determined that driving the stage using the actuator does not result in the stage being driven through the first location associated with the stage.

Abstract: A free piston gas compressor comprising a cylinder, a piston reciprocable within the cylinder and a reciprocating linear electric motor derivably coupled to the piston having at least one excitation winding. A measure of the reciprocation time of the piston is obtained, any change in the reciprocation time is detected and the power input to said excitation winding is adjusted in response to any detected change in reciprocation time.

Abstract: In a driving apparatus of a linear compressor 1 having a power source capable of controlling output current and measuring output electric power, frequency of the linear compressor 1 is controlled such that the amplitude of current which is supplied to the linear compressor 1 is made constant and electric power which is supplied to the linear compressor 1 becomes maximum. With this, it is possible to drive the linear compressor 1 efficiently while following the resonance frequency which keeps varying with variation of a load. Further, a current detecting means 8 capable of detecting output current and electric power from inverter input current is provided, and it is unnecessary to newly add a current sensor.

Abstract: A method, apparatus, and system for controlling a reticle-masking blade in a photolithography system. A reticle-masking blade is supported with a reticle-masking blade carriage assembly. The reticle-masking blade carriage assembly is levitated at a position with respect to a reference frame and at an orientation with respect to the reference frame. Preferably, the reticle-masking blade carriage assembly is electromagnetically levitated. At least one of the position and the orientation of the reticle-masking blade carriage assembly is measured. At least one of the position and the orientation of the reticle-masking blade carriage assembly is controlled. Optionally, the reticle-masking blade carriage assembly is moved within a dimension within a range defined by the reference frame. The dimension can be two dimensions. The movement of the reticle-masking blade carriage assembly can be controlled.