Abstract: A suspended transmission line with an embedded signal channeling device includes a support layer and a conductor supported by the support layer between first and second plates each having a ground plane. The conductor includes a combined signal line and a plurality of discrete signal lines extending from the combined signal line. The discrete signal lines each transmit a portion of a signal transmitted on the combined signal line. A propagation structure is disposed between the first and second plates to substantially contain an electromagnetic field generated by the propagating signal.

Abstract: The invention relates to a combiner (1) for electromagnetic waves that are to be sent or received in, for example, a radio base station.

Abstract: A transmitter 18 and a receiver 24 are formed integrally with a dielectric substrate 12. The transmitter 18 includes a transmitter filter 14 and a transmitter antenna 16 connected to the transmitter filter 14. The receiver 24 includes a receiver filter 20 and a receiver antenna 22 connected to the receiver filter 20. The transmitter filter 14 is formed with resonant elements 30a-30c arranged parallel to each other. The transmitter antenna 16 includes an antenna 32 formed from an electrode film on the upper surface of the receiver filter 20. The receiver filter 20 is formed from resonant elements 34a-34c arranged parallel to each other. The receiver antenna 22 includes an antenna 36 formed from an electrode film on the upper surface of the dielectric substrate 12.

Abstract: In a phase shifter for digitally shifting the phase of an RF (Radio Frequency) signal by changing a switched line which is connecting two main lines into another switched line, at least one of the switched lines is always connected to one of the main lines so as to operate as an open stub when the RF signal is not passed through the switched line.

Abstract: A monolithic conduct includes a laminated stack of insulator sheets and inductor via-holes that are connected to each other in the direction in which the insulator sheets are laminated, thereby forming columnar inductors. Coupling adjusting via-holes are also connected to each other in the direction in which the insulator sheets are laminated, thereby forming a columnar coupling adjusting conductor. The columnar coupling adjusting conductor is disposed between and substantially parallel to the columnar inductors.

Abstract: A multi-layered LC composite component achieves greatly increased attenuation in the proximity of a central frequency without increasing insertion loss. In the arrangement of the multi-layered LC composite component, an end of each of inductor patterns is connected to a connecting pattern to be short-circuited. These inductor patterns define inductors. Frequency-adjusting capacitor patterns are opposed to open-circuited ends of the inductor patterns to define capacitors. As a result, the capacitors and the inductors define LC resonators. The connecting pattern is opposed to shield patterns via insulating sheets to define a common capacitor.

Abstract: An acoustic mirror is described which is formed of at least one first insulating layer, a first metal layer disposed thereon, a second insulating layer disposed thereon and a second metal layer disposed thereon. An auxiliary layer is produced on the first insulating layer whereby a recess extending as far as the first insulating layer is created therein. The first metal layer is substantially deposited and removed by chemical/mechanical polishing until the parts of the first metal layer disposed outside the recess are no longer present. The second metal layer is also produced in a recess with the aid of chemical/mechanical polishing. More than two insulating layers and two metal layers can be provided. The first metal layer and the second metal layer can be produced in the same recess.

Abstract: In one embodiment, an N-stage ladder circuit is serially connected to a bridge (lattice circuit. The N-stage ladder circuit receives differential inputs, e.g. mixers, while the bridge lattice circuit outputs a singled end output, e.g. amplifier. In another embodiment, a bridge lattice circuit is serially connected to an N-stage ladder circuit. The bridge lattice circuit receives a single ended load while the N-stage ladder circuit provides a differential output. Film bulk acoustic resonators are used in the combination ladder and lattice structure for both embodiments to provide the necessary band-pass functionality as well as make the necessary transition from differential to single ended load.

Abstract: An aircraft circuit breaker includes a housing; separable contacts mounted in the housing; a latchable operating mechanism including a latch member which when unlatched opens the separable contacts; and an overcurrent assembly responsive to selected conditions of current flowing through the separable contacts for unlatching the latch member to trip the separable contacts open. A movable and illuminable arc fault indicator has a first ring portion and second leg portions internal to the housing. An arc fault actuator which when energized moves one of the second leg portions. An arc fault current assembly responds to selected arc fault conditions of current flowing through the separable contacts to energize the arc fault actuator to move the second leg portions internal to the housing and the first ring portion external to the housing. The arc fault current assembly includes a light for illuminating the first ring portion.

Abstract: A pressure sensitive trip mechanism for actuating a circuit breaker operating mechanism to trip a circuit breaker includes a trip lever and a trip bar. The trip lever is rotatable about a first pivot. The trip bar is positioned proximate the trip lever. The trip bar is arranged to rotate about a second pivot in response to a predetermined level of pressurized gas created by separation of the pair of electrical contacts, thereby urging the trip lever to unlatch the circuit breaker operating mechanism. The pressure sensitive trip mechanism provides for very fast tripping of the circuit breaker in the event of a short circuit condition or an overcurrent fault condition within any one on the circuit breaker poles. In a multi-pole circuit breaker, the present invention provides for protection against single-phasing.

Abstract: A magnetically actuated pushbutton switch has individual switch modules pre-assembled as standalone subassemblies. Each subassembly has a platform with a cavity on its underside. A portion of the platform is magnetized. A metallic armature is held in the cavity by the magnetic attraction of the platform. The switch subassemblies are mounted on a substrate that has electrodes thereon. The armature is movable into and out of shorting relation with the electrodes. Plugs on the platform may align with holes on the substrate to locate the subassemblies.

Abstract: A solenoid for an electromagnetic valve is provided with a bobbin on which a coil has been wound, a movable iron core fitted into an iron core hole of the bobbin and a fixed magnetic pole member attracting the movable iron core, the movable iron core has a main body portion with an even section fitted into the iron core hole, and a flange portion with an even section formed on a portion extending from the iron core hole of the main body distal end, and the ring has a first portion which is positioned on a distal end side and which has a large diameter hole in which the flange portion is fitted and a second portion which is positioned on a proximal end side and which has a small diameter hole in which the main body portion is fitted.

Abstract: Inductive microcomponent (1), such as a microinductor or microtransformer, comprising a metal winding (2) having the shape of a solenoid, and a magnetic core (4) including a strip made of a ferromagnetic material, positioned at the center of the solenoid (2), and characterized in that the core comprises at least one additional strip made of a ferromagnetic material (13), separated from the other strip (12) by a spacer layer (14) made of a non-magnetic material, the thickness of which is such that the strips (12, 13) located on either side of the spacer layer (14) are antiferromagnetically coupled.

Abstract: An indicator light which when installed in combination with either a circuit protector or a fuse, etc., will automatically illuminate to notify a user that an electrical overload has occurred.

Abstract: A hermetic compressor is disclosed having an electric motor, a compressor unit, and an overload protector within a hermetically sealed housing. The overload protector includes a thermally activated switching device for selectively providing current to the electric motor, a heater element thermally coupled to the switching device, and a control circuit controlling the heater element. The overload protector allows the disconnection of power to the motor due to factors and conditions specified in the remotely located control circuit.

Abstract: A pair of electrodes are provided through a base. A cap and the base constitute a chamber, and are connected to each other by fitting projections provided on the base, into locking grooves formed in the cap. A fuse element is connected to upper portions of the electrodes, located in the chamber, by appropriate means such as soldering or welding. The base is in the form of a rectangle having long sides and short sides. A pair of semi-elliptic air pass holes are formed in substantially central portions of the base along the respective long sides, and opposed to each other.

Abstract: A fuse 1 includes a pair of terminals 2, a housing 4 and a fusible body 5. The one ends 3a of the terminals 2 are housed within the housing 4. The housing 4 includes a pair of end walls 12a, 12b, a pair of side walls 13a, 13b, a first partition wall 21 and a pair of second partition walls 22. The inner faces 15a, 15b of the pair of end walls 12a, 12b are opposite to each other in a direction orthogonal to the direction of arranging the terminals in parallel and extend along the end faces of the terminals. The inner faces 16a, 16b of the side walls 13a, 13b are opposite to each other in a direction of arranging the terminals in parallel. The first partition wall 21 is located between the pair of terminals 2. The pair of second partition walls 22 are located between the first partition wall and the inner faces 16a, 16b, respectively.

Abstract: A variable voltage protection component in accordance with this invention comprises a reinforcing layer of insulating material having a substantially constant thickness embedded in a voltage variable material. With this configuration, the reinforcing layer defines a uniform thickness for the variable voltage protection component that is resist to compressive forces that may cause a reduction in the clamp voltage or a short in the voltage variable material. In addition, the variable voltage protection component can be attached to a compressible ground plane to form a variable voltage protection device. Methods are provided for making the variable voltage protection component and device.

Abstract: An electrical device comprising a pair of electrodes, three substrates, and PTC elements inserted between the substrates, each PTC element having metal layers on both surfaces, in which each of the outer substrates has a metal layer on the inner surface, the two metal layers being electrically connected to one of the electrodes and in electrical contact with the respective metal layers of the PTC elements facing said metal layers of the outer substrates, and the center substrate has a metal layer on both surfaces, such metal layers being electrically connected to the other electrode and in electrical contact with the respective metal layers of the PTC elements facing said metal layers of the center substrate. This electrical device can increase the area of the PTC elements without increasing the projected area as a whole.

Abstract: A compact and low resistance laminated semiconductor ceramic device which is provided with a positive resistance-temperature characteristic and has a broad resistance-change range and a high breakdown voltage in addition to ohmic contact between semiconductor ceramic layers and internal electrodes is provided. A doped barium titanate semiconductor ceramic having an average particle diameter of not more than about 1.0 &mgr;m, a c/a axis ratio of not less than about 1.005, and a barium site/titanium site ratio from about 0.99 to 1.01, in which a donor element, such as lanthanum (La), is used.

Abstract: A vertical Hall sensor includes a semiconductor crystal with three or more arm sections that are arranged at a uniform angle distance to each other. A central electrode and external current electrodes are arranged on the surface of the sensor, and a plurality of Hall voltage contacts is arranged therebetween. The semiconductor crystal is thick enough for a current flow to pass between the electrodes in each arm section of the semiconductor crystal, whereby the current flow produces several sensitivities in the Hall sensor corresponding to the number of arm sections with a correspondingly predefined angular dependency for a magnetic field that is directed in a parallel position with respect to the surface. The Hall voltages, which can be produced using one such multi-arm vertical Hall sensor, can be used in a reinforced and direct manner as an output signal for an electric motor.

Abstract: To protect components connected to a car radio, which each have a microprocessor and are connected to the car radio via a bus, when the component is connected to the car radio for the first time, a specific ID signal, which is stored in the component so as to be secured against access by the user, is transmitted by the car radio to the component via the bus. When the component and/or the car radio are turned on again, the ID signal stored in the component is compared to the ID signal of the car radio and the component and/or the car radio cannot be turned on unless the ID signal of the car radio is identical to (matches) the stored ID signal. Thus, the car radio, which is theft-protected per se, assumes a “guardian” function for the connected components.

Abstract: A library terminal permits a user to execute a loan transaction without assistance. The library terminal (i) provides a visible scan line from a bar code reader indicating the correct positioning of the bar code on a circulating item, (ii) leads a user through a loan transaction, (iii) provides an explicit feedback to a user when an article has an improper position on the article receiving area, (iv) both checks out and checks in circulating items, (v) stores fonts in bit maps of screen displays instead of in a separate font memory, (vi) integrates a security marker reader, a printer, and a controller in the same housing, (vii) processes financial transaction related to the borrowing of circulating items, and/or (viii) displays actions for helping the user to correct errors in use of the terminal.

Abstract: When a “window automatic opening mode” is set in advance by a window automatic opening mode setting switch (14), and the user who carries a portable unit (1A) approaches an onboard unit, doors are automatically unlocked, and a window of a predetermined door is opened when the electric field strength of a radio signal from the portable unit (1A) becomes larger than a predetermined value. This function can be disabled by the window automatic opening mode setting switch (14).

Abstract: An AGH interactive burglar-proof safety system is disclosed, This system is a bidirectioanl transmission mode and includes a mobile module (GSM), a hand free module, a communication interface and a burglar-proof control mainframe. By this system, as the burglars enter into a car, it may inform the car owner immediately. Therefore, the car owner may execute necessary actions for this condition to prevent the action of the burglars so as to provide an interactive burglar-proof function.

Abstract: A rollover sensing system (10) includes a roll rate sensor (14) operative to sense a roll rate of rotation of a vehicle (12) and to provide a roll rate signal having an electrical characteristic indicative thereof. A controller (26) is connected to the roll rate sensor (14) and is operative to determine a roll angle of the vehicle (12) based on the roll rate signal. The controller (26) includes a threshold having a value functionally related to roll angle. The controller (26) determines the occurrence of a vehicle rollover condition in response to the sensed roll rate crossing the threshold.

Abstract: The invention provides a monitoring system for monitoring an internal combustion engine. The monitoring system includes a power source having a winding and a magnet that magnetically interacts with the winding to generate a winding signal. The monitoring system further includes a conditioner that conditions the winding signal to generate a conditioned signal, a counter circuit powered by the conditioned signal that outputs an indication signal, and a visual or audible indicator that provides indication to the user upon receiving the indication signal.

Abstract: A system and method for implementing a configurable security monitor utilizing an integrated information portal are provided. A premises server is in communication with a variety of information sources that produce monitoring data for a defined monitoring target, such as a premises. The premises server transmits the monitoring data to a central server that receives the data and traverses one or more logical rule sets to determine whether the inputted data violates the rules. The rules are generally specified by a user, such as a system administrator to define the level of monitoring desired and an appropriate response in the evaluation of the monitoring data against the rule.

Abstract: Control apparatus and method including a first control device, located at the vehicle or premises, for monitoring or detecting an event, which generates and/or transmits a first notification signal containing event information to a second control device located remote from the vehicle or premises. The second control device generates and/or transmits a second notification signal to a remote communication device for providing notification of the event occurrence. Control apparatus and method including a first control device, located at a vehicle or premises, which generates and/or transmits a first signal for activating, deactivating, enabling, or disabling, a vehicle or a premises system, equipment system, subsystem, device, component, appliance, a vehicle, or a premises, in response to a signal generated and/or transmitted from a remote second control device. The second control device is responsive to a third signal generated and/or transmitted by a remote third control device.

Abstract: A monitoring apparatus for a vehicle or a premises, including a monitoring device for monitoring operation, system status, equipment system status, or activity, or a device for detecting a state of disrepair of a system or equipment system. The monitoring device or device is located at the vehicle or premises. The monitoring device or device transmits data to a first processing device located remote from the vehicle or premises. The data is received by the first processing device. The first processing device is capable of transmitting the data to a second processing device located remote from the vehicle or premises and remote from the first processing device. The second processing device is capable of receiving the data. The data can include operational data and video information, or information regarding a state of disrepair of the system or equipment system.

Abstract: A portable security alarm system which can be installed on a temporary basis and removed from an object whose movement is to be detected including a motion detecting and radio signal transmitting member for mounting proximate the object whose movement is to be detected, a member for selectively coupling and decoupling the motion detecting and radio signal transmitting member relative to the object whose movement is to be detected, a combined radio signal receiving and alarm generating member for receiving a signal from the combined motion detecting and radio signal transmitting member and producing an alarm, a remote control for actuating and deactuating the radio signal receiving and alarm generating member, an information gathering device adapted to receive the predetermined signal, to gather information relating to the movement, and to transmit the information, and a remote notification device adapted to receive the information from the information gathering device, to establish data communication with a r

Abstract: An infrared detection and alarm system for the bottom shelf of shopping carts having attached to the bottom shelf an infrared emitter which shall emit therefrom infrared light which shall be received by an infrared detector when no merchandise is located on the bottom of the cart and if a piece of merchandise is located on the bottom shelf the light shall be interrupted. Upon interruption of the light, a transmitter shall communicate a code to a receiver mounted on the checkout stand at which point said receiver shall activate an LED warning light to communicate to the sales clerk the presence of merchandise on the bottom shelf of the shopping cart.

Abstract: A monitoring device to prevent separation including a transmitter portion adapted for coupling with a person or object to be monitored. A receiver portion is provided that is adapted for being worn on a person. The receiver portion is in communication with the transmitter portion. The receiver portion has a predetermined separation parameter measured between the receiver portion and the transmitter portion. The receiver portion includes the ability to determine the distance between the receiver portion and the transmitter portion. The receiver portion includes an alarm for sounding once the predetermined separation parameter has been exceeded. The transmitter portion also includes an alarm for startling a would-be wrongdoer and alerting others near the object of person being monitored.

Abstract: Apparatus for monitoring movement of a person's eye, e.g., to monitor drowsiness. The system includes a frame that is worn on a person's head, an array of emitters on the frame for directing light towards the person's eye, and an array of sensors on the frame for detecting light from the array of emitters. The sensors detect light that is reflected off of respective portions of the eye or its eyelid, thereby producing output signals indicating when the respective portions of the eye is covered by the eyelid. The emitters project a reference frame towards the eye, and a camera on the frame monitors movement of the eye relative to the reference frame. This movement may be correlated with the signals from the array of sensors and/or with signals from other sensors on the frame to monitor the person's level of drowsiness.

Abstract: The system for remote and non-visual detection of illumination device operation which is operational to identify the operational state of individual illumination devices. This is accomplished by placing the unit under test in a steady state operating condition during the burn-in and/or environmental stress testing process. The illumination devices are individually selected and operated during the test and the operational state of the selected illumination device determined. The determination of the operational state of the illumination device is effected by measuring the incremental change in power drawn by the unit under test resulting from the activation of the selected illumination device. An anomaly in the measured change in power consumption is indicative of a failure mode for the selected illumination device.

Abstract: A system for identification and tracking of tags distributed in a room, wherein the system includes an electromagnetic pulse generator to produce a local electromagnetic spike, a tag reactive to the local electromagnetic spike to provide a data signal, a data receiver for receiving the data signal, and a tag tracking system receiving input from the electromagnetic pulse generator and the data receiver, the tag tracking system storing state records of position and informational content of the tag.

Abstract: A thermal analyzer comprising a measurement module (8) having a heating furnace (1), a measurement station (16 ) which controls the measurement module (8) and has a measurement user interface, a monitor (24) and software operating on respective central processing units (6, 12 and 20). An inquiry made about the existence of data and transfer of user-designated data to the measurement stat ion (16) in which measurement data are stored from the monitor station (23) permits us to monitor the data at the monitor station (23).

Abstract: A distance measuring and monitoring device equipped automobile reverse radar comprises: a photocoupler camera with a wide-angle lens installed at an automobile rear end for taking pictures of possible obstacles behind the automobile body; a distance measuring inductor for calculation of lateral distance between two lateral corners of the automobile body and an obstacle; and a power supply for supplying power to the photocoupler camera, the distance measuring inductor, and the display. The image of the obstacle is mirror-image processed, then forwarded to an image synthesizer for image synthesization, and transferred to a video processor and shown in a display. A reverse gear signal is the effective signal for triggering the power supply.

Abstract: A docking system for airport terminals has a docking station subsystem and a docking station for each gate. The docking station subsystem is connected via a communication network to a central working position. The docking station subsystem includes an airfield situation monitoring and processing segment ASMPS, at least one advisor and guidance display segment AGDS, a data and status handler segment DSHS having at least one video camera (9, 10) for each center line of the gate, and at least one ground operation panel segment GOPS. The docking station subsystem has an auxiliary subsystem connected to it, by which information relating to aircraft models and the gate can be entered in the docking station subsystem. A docking guidance system is connected to other systems of an airport and includes a docking guidance subsystem for each gate of the airport.

Abstract: A system and method of identifying a point of interest of an object located in front of a computer controlled display area captured by an image capture device is performed by capturing an image of the display area within the capture area of the image capture device. Pixels within the captured data are identified that correspond to the object within the display area and to the peripheral boundary of the display area within the capture area. Pixels are identified and stored that correspond to the common subset of the object pixels and the peripheral boundary pixels. A search is performed using the common pixels and the object pixels to determine a pixel corresponding to the point of interest of the object in the display area within the capture area.

Abstract: A multi-turn rotary encoder that includes a first code carrier connected with an input shaft, a scanning device that scans the first code carrier and generates an absolute position of the input shaft within one revolution, and a digital code word is present at an output of the scanning device and a second code carrier for measuring the number of revolutions of the input shaft. A reduction gear is arranged between and coupled to the first and second code carriers. The second code carrier includes a magnetic body with at least one north and south pole and a substrate with a spatial arrangement of sensor elements integrated therein, which are sensitive to magnetic fields, is associated with the magnetic body.

Abstract: A rear-mount integrated rotary encoder comprises a mechanical portion and a printed circuit board portion. The mechanical portion of a rear mount integrated rotary encoder comprises a housing including a bushing for receiving one end of a rotatable. The rotatable shaft passes through an open front portion of the housing and is mechanically connected to exposed rotatable circuit contacting members. The printed circuit board portion has an encoder contact pattern formed thereon. The printed circuit board has an area larger than the cross sectional area of the housing. The encoder contact pattern surrounds an aperture in the circuit board. The rotatable shaft of the rotary encoder is passed through the aperture such that the rotatable circuit contacting members contact the encoder contact pattern on the circuit board. The housing includes projections, substantially orthogonal to the circuit board, for engaging a feature of the circuit board for securing the integrated encoder in an assembled state.

Abstract: A character input apparatus and method which can give a plurality of different character input mean a capability of complementing each other.

Abstract: A data input device and method of encoding key assignments for a data input system which provides for the mapping of the numerous keys, alpha, numeric, symbolic and function, found in a full-sized standard keyboard into ten data input keys. The data input system aids in reducing clutter associated with data input by incorporating all input functions to a minimum of keys. The data input system, whether depressed through a single stroke or combination, evolves data input from a complex system requiring numerous keys laid out in an unwieldy fashion into a system of single finger keys which are actuated in simple combinations. In practice, each key in the primary ten data input key of the present invention acts as a “shift key” creating user options when first depressed. Pressing a subsequent key or keys or releasing the initial depressed key will cause the desired character or function to occur.

Abstract: A computer keyboard has multiple input/output function and is connected to a computer (or a set-top box). The keyboard comprises a keyboard main body, and a handset slot. The keyboard main body has a control circuit, a scan matrix circuit connected to the control circuit; a first switch and a second switch. The control circuit is connected to the normally-close terminals of the first switch and the second switch. The communication interface (such as USB or RS-232) of the keyboard is connected to the normally-open terminals of the first switch and the second switch. The common terminal of the first switch is connected to the handset slot and the internal circuit of the handset. The common terminal of the second switch is connected to the internal circuit of the computer. The keyboard main body has function key set connected to the control circuit when being pressed.

Abstract: An apparatus and method provide an apparatus and method for reducing noise production and power consumption in a logic device that uses monotonic logic encoded signals. In particular, the apparatus is accomplished by a recode circuitry that receives and recodes a monotonic logic encoded signal received from a first logic circuit in the logic device, into a reduced switching signal. The recode circuitry sends the reduced switching signal to a second logic circuit. A decode circuitry receives and decodes the reduced switching signal back into a monotonic logic encoded signal. The decode circuitry then sends the monotonic logic encoded signal to a second logic circuit in the logic device. The method is accomplished by receiving a monotonic logic encoded signal from a first logic circuit. The monotonic logic encoded signal is converted into a reduced switching signal and transmitted. The reduced switching signal is received and converted back into the monotonic logic encoded signal.

Abstract: A sample rate converter for converting a data stream having a first base sampling frequency to a data stream having a second base sampling frequency. Up-sampling circuitry receives first oversampled data having a first oversampling ratio with respects to the first base frequency and outputs second oversampled data having a second oversampling ratio with respects to the first base sampling frequency. Resampling circuitry resamples the second oversampled data by a resampling frequency ratio of integers representing a ratio of the first and second base frequencies and generates third oversampled data having the second oversampling ratio with respects to the second base frequency. Down-sampling circuitry then down-samples the third oversampled data and generates fourth oversampled data having the first oversampling ratio with respects to the second base frequency.

Abstract: A Universal Variable Length Code (UVLC) encoder for H.26L is provided. This encoder is simple and efficient due to the change of codeword number and codeword alignment technique. The look-up table could absorb the effect of codeword number's change on the previous stage of H.26L encoding. And there is no side effect on complexity of the whole system. The header information coding and byte alignment function could also be integrated in this architecture.

Abstract: In accordance with the invention, a serializer/deserializer core of a field programmable gate array includes a channel clock and a data channel. The data channel can serialize and deserialize data in two modes. In the first mode, an embedded clock signal is recovered from the data. In the second mode, a clock signal is provided by the channel clock. A selection signal determines in which mode each of the data channels in the serializer/deserializer core operates. An stair-step clock generator generates a series of rising edge signals used to serialize and deserialize data. The number of bits serialized and deserialized is determined by the control signals to a set of multiplexers in the stair-step clock generator which determine how many registers in the stair-step clock generator are activated.

Abstract: A data conversion device converts a series of digital signals into an analog signal. The device has a current selection circuit that can vary the direction and magnitude of the current it outputs and an integrating circuit that integrates the current supplied from the current selection circuit to output a voltage. The direction of the current is determined in accordance with the digital signals fed in. When the absolute value of the current is great, the value by which the absolute value of the current is increased is decreased, and the value by which the absolute value of the current is decreased is increased.