Abstract: A household appliance for drying a laundry item, the household appliance having a treatment chamber and a closed process air circuit to feed process air through the treatment chamber. The process air circuit includes a blower to move the process air; a condenser to condense out moisture in the process air; a heater to heat the process air; a measurement device to determine a temperature of the process air; and a controller to control the blower and the heater as a function of the measurement signal. An analyzer determines an energy requirement to dry the laundry item prior to initiating a drying process for the laundry item. An integrator determines an energy input to the process air via the heater up to a respective measurement time. A comparator compares the energy input with the energy requirement and ends the drying process when the energy input matches the energy requirement.

Abstract: One type of dryer, namely a laundry dryer (1), comprises a water tank (20) and a drum (30). At the time of drying laundry, the interior of the drum (30) functions as a hermetically closed drying chamber (170). The air in the closed drying chamber (170) is sucked into a circulation duct (171) and heated by means of a heater (173) to a hot air before being blown into the closed drying chamber (170). The hot air having absorbed moisture from the laundry comes into contact with dehumidification water in a cooling chamber (174) within the circulation duct (171), thereby being dehumidified. The dehumidification water is sprayed by a mist generator (180). In the drying process, the mist generator (180) generates mist of metal ion water which has passed through an ion dissolving unit (100) and sprays the mist to the laundry.

Abstract: A system for drying a load of wood including: a heat generating device providing heat necessary for drying the load of wood, apparatus for generating a gaseous coolant flow for treating the load of wood by combustion of biomass under O2, the gaseous coolant flow being essentially constituted by CO2, a heat exchange device allowing the transfer of the heat produced by the heat generating device to the gaseous coolant flow for treating the load of wood, a unit for treating/drying the load of wood, including a central volume, known as a technical or treatment volume, dedicated to the drying of the wood, and inlet and outlet hatches for the loads of wood, situated at the upstream and downstream ends of said central volume, and a thermal device for the dehydration and condensation of the steam extracted from the wood during the drying cycle.

Abstract: An auxiliary laundry treating machine that is capable of improving energy efficiency and maximally securing a laundry receiving space and a multiple treating system including the same are disclosed. The auxiliary laundry treating machine includes a machine body mounted at one side of a main laundry treating machine that washes or dries laundry, a container for receiving laundry, the container being configured to be inserted into and withdrawn from the machine body, and an air supply unit mounted in the main laundry treating machine for supplying air into the container. The air supply unit includes a blowing fan for suctioning and blowing air in the main laundry treating machine and a heater for heating the air blown by the blowing fan. Also, the multiple treating system includes a main laundry treating machine for washing or drying laundry and the auxiliary laundry treating machine.

Abstract: In a sensor system for a domestic laundry dryer in which a canister-shaped condensate container 5 is mounted in a receiving chamber 15, at least one sensor S2 is used to monitor the insertion of the condensate container 5. Another sensor S1 takes over the detection of a limiting filling level 12 of the condensate in the condensate container 5. When this level is reached, emptying of the condensate container 5 is requested by switching an audible and/or visual attention signal. This container can be removed from the inside of the loading door 6. At least one sensor S2 is a non-contact switch. The sensor system contains a circuit arrangement which can be influenced by the sensor or sensors S for controlling the drying program of the laundry dryer. The sensor or sensors preferably S contain magnetically influencable switches. They form a switching system comprising a magnetically influencable switching contact 1 and a magnet 2.

Abstract: An apparatus, system and method of controlling heated air drying of product. Exhaust temperature is measured during drying and compared to a target or ideal exhaust temperature function or reference. The exhaust temperature function or reference is correlated to a target or ideal drying rate for the product. Drying factors are adjusted to compensate for variance between measured exhaust temperature and the target or ideal exhaust temperature function to influence actual exhaust temperature to follow the target or ideal exhaust temperature function during drying. Drying factors such as inlet air temperature and drying pressure can be controlled manually or automatically by the comparison to promote efficient and controlled drying.

Abstract: A retrofit turner and sensor unit includes, on its upper portion, a grain turner for moving grain from a central portion in the grain pathway to a defined outer space for measurement. On its lower portion, the retrofit unit includes a moisture sensor and a temperature sensor provided in a plate configuration in line with the outer wall of the grain dryer for sensing moisture and temperature of grain in the defined space. In the preferred configuration, the plate sensor includes redundancies, and is mounted on a hinged door. The retrofit unit is easily installed into an existing grain dryer with columns and continuous flow capabilities, and electrically connected with a controller/processor and a motor for metering rolls which determine grain speed through the dryer.

Abstract: The invention relates to a method of operating a laundry treating appliance having a rotatable drum defining a laundry treating chamber. The laundry in the laundry treating chamber may be imaged and a fluffing state of the laundry determined based on the imaging of the laundry. The operation of the laundry treating appliance may be based on the determined fluffing state.

Abstract: The invention relates to a laundry treating appliance and method for controlling the operation of the laundry treating appliance by determining the surface area of the laundry based on image data of the laundry.

Abstract: The invention relates to a method of determining the presence of a drying rack based on image data of the laundry located in a treating chamber of a laundry treating appliance.

Abstract: A combination clothes dryer and air filter. The device is adapted for reversal of airflow through a housing to allow a horizontal position and a vertical position for operation. The device is adapted for easy storage in the horizontal position.

Abstract: A dryer fire protection system has a control circuit for controlling power supplied from a source, via a power cord comprising a neutral line and at least one entry live line, to a load connected with the neutral line and at least one load live line. The control circuit has a relay comprising an electromagnet and a normally closed switch, when the electromagnet is de-energized, to allow power to flow between the entry live line and corresponding load live line. An electromagnet control circuit connected between the entry line and neutral line has a plurality of normally open thermostats in parallel and mounted within the cabinet external of a drum and ducting associated therewith. Power is normally disconnected from the electromagnetic circuit to de-energize the electromagnet. Excessive cabinet heat closes at least one thermostat to power the electromagnet circuit to energize the electromagnet to open the switch.

Abstract: A home laundry drier (1) having a revolving drum (5) for housing the laundry to be dried, a hot-air generator (7) for circulating a stream of hot air inside the drum (5), and a steam generator (17) for feeding steam into the drum (5); the steam generator (17) having an electric boiler (18) designed to receive a given quantity of water and immediately convert it into a stream of low-pressure steam to be fed into the drum (5), a demineralized-water reservoir (20) located over and communicating with the electric boiler (18), and a lint filter (23) located upstream from the water reservoir (20); the water reservoir (20) receiving distilled water from the water canister (12) of the heat exchanger (10) of the hot-air generator (7) via a water drain circuit (13); and the laundry drier (1) also having a liquid level sensor (26) for determining when the water in the water reservoir (20) is below a given minimum level, and a central control unit (24) for determining whether the water reservoir (20) is in a given low-wa

Abstract: A laundry room machine and a drying method thereof are provided. The laundry room machine may includes a payment device for collecting a payment for operation of the laundry room machine. The laundry room machine performs drying of laundry items for a preset dry time corresponding to a selected drying course. The drying method includes determining a condition of the laundry items by measuring a humidity level, and either sustaining the preset dry time or resetting a hot air supplying time and cooling time based on the determined condition of the laundry items.

Abstract: An appliance having a dispensing system and a detection system for detecting failure modes related to the dispensing system.

Abstract: A clothes dryer includes a motor adapted to be mounted on a frame of the dryer for driving a dryer belt to rotate a drum of the dryer. The motor includes a rotor adapted to rotate the belt, at least one winding energizable to cause rotation of the rotor, and a first switch operable to control energization of the winding. A second switch has a sensor for sensing belt breakage. The second switch is mounted on the first switch and is electrically connected to the winding so that when the belt is no longer sensed, the second switch stops operation of the winding and thereby stops rotation of the rotor.

Abstract: A restriction sensor system for identifying the existence of blockages in exhaust conduits of clothes dryers. The restriction sensor system may be used as a retrofit system that is capable of being installed on existing clothes dryers. The restriction sensor system may include a fitting configured to be coupled to an exhaust conduit of a clothes dryer and a blockage indicator housing positioned remote from a clothes dryer. The pressure sensing device may be capable of determining changes in air pressure in the exhaust conduit. Once the air pressure present in the exhaust conduit exceeds a threshold air pressure, the pressure sensing device may send a signal to an indicator to generate an alarm, which may be a visual alarm or audible alarm, or both.

Abstract: The present invention relates to a laundry dryer capable of removing and/or preventing wrinkles of laundry. A laundry dryer includes a drum to hole laundry, a steam generator to selectively supply steam to the drum, a water supply source to hold water that is supplied to the steam generator, a water softening member provided in the water supply source to soften water, and a drain hose through which the water of the water supply source is selectively drained outside.

Abstract: A vehicle wash system may have a drying station that may have a frame and a blower mounted on the frame. The blower may be used blowing liquid from the surface of a vehicle and may have a plenum with a cavity opening, an exit port, and an interior cavity. An impeller may be positioned inside the cavity, and when driven by a motor, may be operable to draw air into the cavity compress the air, and then emit an airflow from the plenum through the exit port. The blower may have an inlet region formed proximate the cavity opening and be in communication with the cavity. The inlet region may have a generally tubular inlet opening. A movement apparatus may be provided that is movable axially relative to the inlet opening to vary the size of the tubular inlet opening. The system may also include a sensor system operable to detect the presence and/or absence of a vehicle at drying station.

Abstract: A bearing including a wearable section including a wear sensor is provided. The bushing includes a wear sensor that provides feedback to a user relating to the amount of useable life of the bearing that has been used. The sensor may be in the form of a wire imbedded in the wearable section of the bearing such that as the wearable section wears over time, the wire may be worn through breaking a circuit including the wire. An indicator module can sense the breakage of the wire and determine the amount of useable life of the bearing that has been used. In one implementation, the bearing is used in a drying drum. In one form of the invention, a method of monitoring wear of the bearing is provided that includes monitoring changes in electrical properties of a sensor mounted in the bearing.

Abstract: An automatic ground surface dryer, system and method for automatically, conveniently, quickly and effectively drying a ground surface without the need for manual labor and capable of quickly drying a large ground surface is described. The automatic ground surface dryer has a frame, a drying apparatus mounted to the frame, a support for the frame to facilitate movement of the frame over the ground surface, a motor coupled to the frame to move the frame over the ground surface, and a controller coupled to the motor and the drying apparatus to drive the motor and to operate the drying apparatus in response to a rainfall data signal from a rainfall data gathering system which gathers rainfall data.

Abstract: A tumble dryer with a fire-extinguishing facility includes a fire sensor for detecting a fire in a laundry drum of the tumble dryer, and an extinguishing medium supply device for introduction of an extinguishing medium into the laundry drum of the tumble dryer on actuation of a fire-extinguishing device. The extinguishing medium supply device includes a laundry freshening device.

Abstract: Disclosed is a clothing dryer comprising a drum in which a drying object is contained, an exhaust duct connected to the drum and exhausting air in the drum, a blowing fan mounted at an intermediate portion of the exhaust duct and configured to move air, a fan housing receiving the blowing fan and temperature sensors installed at the fan housing. And, temperature sensor mounting portions are formed in the fan housing so as to prevent foreign materials from being accumulated at a front portion of the temperature sensors disposed at a front side of a flow direction of air passing through the fan housing, accordingly it is capable of preventing the foreign materials such as lint from being accumulated at the front side of the temperature sensors and of reducing resistance against air flow.

Abstract: A system (110) for drying a charge of lumber includes a kiln (112), one or more sensors (114) for sensing the one or more monitored conditions associated with the operation of the kiln (112) when drying the charge of lumber; and a control system (116) for controlling the operation of the kiln (112) and the one or more sensors (114). The control system (116) is responsive to the one or more sensors (114) and is arranged to recognise a predetermined change in the one or more conditions and to control the operation of the kiln (112) by adjusting one or more kiln drying parameters in a manner predetermined by the nature of the change.

Abstract: A laundry treatment machine capable of determining whether a lint filter is installed therein is provided. Therefore, it is possible to prevent the infiltration of foreign substance into a heater or a drum, which may be caused when a lint filter is not installed in a laundry treatment machine, and thus to prevent a fire or damage to laundry. In addition, it is possible to easily implement a lint filter detection device for determining whether a lint filter is installed in a laundry treatment machine.

Abstract: The object of the present invention is to provide a method for drying in a dryer which can reduce power consumption at a small load by improving a drying method of the dryer. The object of the present invention can be achieved by providing a dryer including a drum for holding a drying object, a heater for providing hot air to the drying object, a sensing unit for producing a measured value varied with an amount of the drying object in the dram, and a control unit for determining the amount of the drying object from the measured value produced with the sensing unit, and controlling an operation capacity of the heater according to a result of the determination.

Abstract: An evaporator core drying system in which air that is blown by a blower is concentrated into a narrow cross-sectional air stream of high speed purge air which passes progressively across the area of the evaporator core, per an appropriate blow algorithm, so as to effectively and efficiently dry the evaporator core. Preferably, the configurable barrier is composed of at least one roller door located between the blower and the evaporator core.

Abstract: A clogging degree deciding method for a dryer, which can accurately determine a clogging degree of an air passage, even when there is an influence of external environments, is disclosed. The clogging degree deciding method includes reading information as to clogging of an air passage, and displaying a clogging degree of an exhaust duct or a clogging degree of a filter in accordance with the read clogging information. The clogging information includes an ON/OFF duty ratio of a temperature control member. The displaying step includes comparing a difference between two ON/Off duty ratios finally stored with a filter-clogging determination reference value, and determining the clogging degree of the filter, based on a result of the comparison. Accordingly, it is possible to provide the clogging degrees of the exhaust duct and filter to the user.

Abstract: The present invention relates to a dehumidification plant for a granular material, comprising at least one hopper (2) having at least one loading mouth (3a) and one discharge mouth (3) for granular material, at least one upper feeding mouth in the at least one hopper (2) and at least one lower delivery mouth of a gaseous medium therefrom, humidity absorbent means (51, 52) designed to absorb the humidity conveyed by the gaseous medium; at least two towers (29, 36) arranged to contain the absorbent means (51, 52); supplying means designed to feed the gaseous medium to the at least one hopper (2) and the at least two towers (29, 36); at least one electronic control unit (46); detection means arranged to detect process variables of the plant and electrically connected with the at least one electronic control unit (46).

Abstract: A drying apparatus includes a humidity sensor module, a micro control unit (MCU) module, an indicator circuit, and a fan module. The humidity sensor module measures relative humidity of air in a computer, and converts that measurement to an electronic signal. The MCU module receives the electronic signal from the humidity sensor module, and respectively outputs an indication signal and a control signal when the measured humidity is greater than a predetermined value stored in the MCU module. The indicator circuit indicates the humidity in the computer is too high when it receives the indication signal from the MCU module. The fan is activated when it receives the control signal from the MCU module.

Abstract: A device and method for drying containers, in particular bottles, having a drying unit for removing water on the container surface. The drying process saves energy and is adapted to ambient conditions, so that labels, for example, can be applied reliably in a downstream labeling machine. The device includes at least one measuring unit for measuring ambient parameters. In addition, a control unit designed so that the drying performance of the drying unit can be regulated as a function of at least one measured ambient parameter is provided. The device and method makes it possible to prevent the condensation of water on the container surface or to keep it below a certain minimum.

Abstract: The present invention relates to a laundry machine and a method for operating the same for removing wrinkles or the like from laundry by using high temperature and high humidity air instead of steam. The method for operating a laundry machine includes the steps of a course selecting step for selecting an operating course, and a high temperature and high humidity air supply step for supplying high temperature high humidity air to a drum from an air supply unit.

Abstract: The present invention provides an improved dryer (22) that is adapted to dry an object (?) and to an improved method of drying an object. The improved dryer (22) broadly includes: a conveyor (32) for translating an object (?) to be dried, the conveyor having an entrance end (33) and an exit end (34); an enclosure (35) surrounding the conveyor; a movable panel (36) arranged within the enclosure; an actuator (38) mounted on the enclosure and operatively arranged to selectively move the panel toward and away from the object; a first air knife (39) operatively arranged to discharge a first jet of air through the conveyor toward the object; and a second air knife (40) mounted on the movable panel and operatively arranged to discharge a second jet of air toward the object; whereby the actuator may be operated to move the panel into closer proximity with the object as the object moves along the conveyor from the entrance end to the exit end to dry the object.

Abstract: A clogging detecting apparatus for a dryer is provided that can check a clogging state of an air passage according to an off time of a drying operation. The clogging detecting apparatus may include a heater for heating the air of the air passage, a temperature control unit for turning on/off a power supply from a power unit to the heater according to a temperature of the air passage or a temperature of the heater, and a judgment unit for judging the clogging state of the air passage according to an on/off time of the temperature control unit. The clogging detecting apparatus may precisely judge the clogging state of the air passage according to a quantity of laundry dried in the dryer regardless of external factors such as a variation of an external common power.

Abstract: The present invention relates to a laundry dryer that can prevent as well as remove wrinkles of laundry. A laundry machine includes a drum selectively rotatable, a steam generator to supply high temperature steam to the drum, and a controller to determine whether there is a malfunction of the steam generator by using a temperature increasing time inside the steam generator.

Abstract: A dryer for drying moist goods is provided. The dryer reduces the amount of conditioned air used during the drying cycle by drawing drying air from the exterior of the building rather than the interior of the building thereby reducing the overall energy efficiency of the building. The dryer includes an air flow passage extending between a fresh air inlet and an exhaust air outlet. A drying chamber forms a portion of the air flow passage and is interposed between the fresh air inlet and the exhaust air outlet. A blower moves air through the air flow passage. The fresh air inlet and exhaust air outlet are separated from one another by a common wall and are positioned adjacent to one another. The fresh air inlet and exhaust air outlet are configured to attach to a combined supply and exhaust duct such that exhaust air and fresh air are passed between the dryer and the exterior of the building through the combined supply and exhaust duct.

Abstract: A vacuum drying apparatus and a vacuum drying method are provided wherein it is possible to reduce the drying time of an object to be dried and the surface condition of the object to be dried after drying is extremely satisfactory. A vacuum pump is connected to an exhaust port of a vacuum chamber through a suction pipe, and a frequency converter is provided on the input side of an alternating current motor for driving the vacuum pump to form a vacuum drying apparatus. A substrate coated with coating liquid is placed in the vacuum chamber of the vacuum drying apparatus.

Abstract: An invention is provided for a hand drying apparatus for drying and sanitizing hands is disclosed. The hand drying apparatus includes a housing having an air intake opening and a heating element situated within the housing capable of heating air drawn into the hand drying apparatus through the air intake opening. Also located within the housing is an air conduit that is in communication with the air intake opening. Further included is a blower that is capable of drawing an air stream into the air conduit through the air intake opening. An ozone gas generator is in communication with the air conduit that is capable of injecting ozone into the air stream to create an ozonated air stream. In this manner, the blower ejects a heated ozonated air stream out of the hand drying apparatus through the air conduit, whereby a user's hands are dried and sanitized.

Abstract: The present invention relates to a hair drier with a 3-Dimensional control interface, comprising a housing, a control button, a power supply, a heating element and a control circuit. An electrical connection is set among the power supply, the heating element and the control circuit. The control button has a 3-D control interface and can control each functional element of the hair drier separately or synchronously. This hair drier is single-key controlled and various functions of the hair drier can be realized by easily changing the angle of the button to a different direction, or moving the button towards different directions. This hair drier is simple in structure, easy to operate and convenient to use.

Abstract: The invention provides an apparatus, methods, and compositions for dispensing a fragrance onto laundry in a dryer without substantial loss of that fragrance during the drying process. The apparatus includes an electrostatic vapor generator capable of dispensing a fragrance composition into a dryer. The invention also provides electrostatically dispensable fragrance compositions containing glycols, vegetable oils, and perfumes. The invention further provides a kit and method for enhancing residual fragrance on laundry by adding a fabric conditioning composition and a fragrance composition in separate steps during the laundering process. The invention includes embodiments wherein the dispensation of the fragrance compositions is computer controlled.

Abstract: A clothes dryer has a first four pole motor that rotates a rotatable drum in the dryer through a transmission system. The clothes dryer has a second two pole self speed regulated induction motor connected to a blower fan in the air passageway of the dryer. The second motor rotates the fan to draw air out of the dryer and exhaust the air to an external vent. The second motor provides a long venting application and has a slip characteristic whereby the speed of the second motor automatically varies directly proportional to air flow restrictions associated with the external vent.

Abstract: The present invention relates to a process for controlling the temperature of a product in the form of a web (12) that is influenced by an IR ramp (9) for surface treatment of the web (12). With the help of a number of temperature sensors (26), the temperature of the web (12) is measured continuously within evenly distributed zones across and along its direction of movement (28), and the values obtained from the respective zone of the web (12) are transmitted to the respective drier modules (2) for the purpose of subjecting the aforementioned zones of the web to heat. The invention also relates to an arrangement with which the aforementioned process is executed.

Abstract: System and method for controlling an appliance for drying clothing articles is provided. The appliance has a container for receiving the clothing articles. A motor is provided for rotating the container about an axis. A heater is provided for supplying heated air to the container during a dry cycle. A sensor is provided for providing a signal indicative of moisture content of the articles. Memory is provided memory for storing historical stop time data of respective dry cycles. A noise-reduction filter is coupled to receive the signal from the moisture sensor to provide selectable filtering to that signal. A timer provides a signal indicative of elapsed time upon start of the dry cycle. A module is responsive to the historical data in the memory for determining an initial estimate of the stop time of the dry cycle to be executed. A processor allows for estimating the stop time of the dry cycle as the cycle is being executed.

Abstract: A grain dryer control system uses the grain dryer discharge temperature to account for moisture reduction in the grain as it cools after discharge from the dryer. The control system includes moisture and temperature sensors and a means to control the discharge of grain from the grain dryer. Given a grain discharge temperature, a control temperature and a moisture reduction factor as a function of temperature, the control system calculates an expected moisture reduction in the grain as the grain cools. Grain is discharged from the dryer when the target moisture content after cooling added to the expected moisture reduction in the grain as the grain cools meets the measured grain moisture content in the dryer.

Abstract: A method and apparatus for controlling the drying process taking place in the dryer section of a paper machine or the like. The total drying efficiency required in the dryer section is first calculated by means of a method known as such, and an optimal drying efficiency distribution is compiled. Using the optimal drying efficiency distribution, the dryer section is divided into two or more imaginary drying segments which differ in their drying action, in at least one of which segments there are at least two dryer units using different forms of energy and/or at least two separately adjustable dryer units using the same form of energy. The total drying efficiency obtained is divided, by means of an optimization method known as such, between the said different drying segments in such a way that a good drying efficiency distribution is achieved in terms of the quality of the web being dried.

Abstract: A laundry drier control method is provided, by which drying time is dynamically controlled according to an amount and type of a drying object, using a calculated medium temperature to determine a medium temperature time. The method includes steps of initiating a drying procedure by actuating drivers, including a heater driver to increase an internal temperature of a laundry drier; determining a medium temperature time by measuring a time lapse from the drying procedure initiating step to a point where the internal temperature reaches a medium temperature between a drying initiation temperature and a maximum drying temperature; setting a drying time based on the determined medium temperature time; and performing the drying procedure for the set drying time. The drying time is set by multiplying the determined medium temperature time by a predetermined factor. The drying initiation temperature is the internal temperature at the time of initiating the drying procedure.

Abstract: Drying semiconductor wafers or substrates by introducing an polar organic compound in liquid form into or onto means for enhancing evaporation within a process chamber and allowing the liquid to evaporate and form a drying vapor within the process chamber.

Abstract: A control circuit for a clothes dryer operating with a 120 volt power supply compensates for changes in the ambient temperature to compensate for premature advancement of the dryer timer motor during an automatic drying cycle. The control circuit has a thermally biased low outlet thermostat and a thermally biased high outlet thermostat which control the energization of a heater in the dryer. The low outlet thermostat and the high outlet thermostat each open circuit at respective lower and higher predetermined temperatures when the outlet air flow from the dryer drum reaches the lower or higher respective predetermined temperatures to thereby de-energize the heater and advance the timer motor. The control circuit includes a thermally biased ambient thermostat that is normally open and unbiased, and that switches control of the heater energization from the low output thermostat to the high outlet thermostat when thermally biased and when the ambient temperature rises above a predetermined ambient temperature.

Abstract: A gas conduit for a load lock chamber. The gas conduit connects to a gas source to introduce gas from the gas source into the load lock chamber of semiconductor equipment. The structure includes a filter mounted on the top surface of the load lock chamber, a pressure limitative device to maintain a preset pressure of gas source, and a gas inlet device including an inlet end connected to the pressure limitative device and an outlet end connected to the filter, wherein the gas inlet device introduces gas from the gas source into the load lock chamber with its maximum flow rate when breaching the vacuum therein.

Abstract: An apparatus for spin drying a semiconductor wafer includes a hollow core spindle and a chuck assembly having grippers for supporting a wafer at an edge thereof. A sleeve is disposed in the central opening of the spindle and a manifold is disposed in the upper end of the sleeve. A capacitance sensor is affixed to the manifold. In another apparatus, an arm having a capacitance sensor mounted thereon is positioned such that the capacitance sensor is disposed above a space to be occupied by a wafer that is supported by the grippers. Yet another apparatus includes an arm having a light source and a detector mounted thereon. The light source directs light toward a surface of a wafer such that light that reflects off of the surface is substantially perpendicular to that surface. The detector is positioned to measure the intensity of the reflected light.