Abstract: The method of forming an MNOS transistor having a stepped channel oxide region utilizes intentional undercutting of the oxide in the channel region to provide a self-aligned mask for ion implanting a region of the same conductivity type, but more heavily doped which will be centrally located beneath the thin portion of the channel region in order to increase the threshold window of the device while saving a photomask operation.

Abstract: A method of fabricating semiconductor components having electrodes and terminals. The method includes preparing an undivided semiconductor wafer having at least one pn-junction; etching a grid pattern of grooves into at least one side of the undivided wafer, thereby forming mesas with concave side surfaces and elevations with upper surfaces bounded by closed rounded curves; coating the exposed lateral surfaces of the etched mesas with a passivating layer; metallizing the upper surfaces of these elevations, thereby providing ohmic contacts for the undivided semiconductor wafer; and breaking the undivided semiconductor wafer into individual semiconductor chips along the lines of the etched grooves.

Abstract: A method for fabricating a semiconductor device includes the formation of a monitoring element in a substrate. The monitoring element has substantially the same structure and size as a circuit element on the device which is to be monitored. Polycrystalline electrodes are contacted to the semiconductor regions of the monitoring element and extend on an insulating film covering the surface of the substrate. The electrical characteristics of the monitoring element are measured by contacting probes of a measuring apparatus to portions of the polycrystalline electrodes.

Abstract: A hybrid mosaic IR/CCD focal plane structure has high detector element packing densities which may be achieved using cost effective planar processing technology. The focal plane structure preferably includes an insulator layer over a silicon substrate which contains integrated circuit CCD signal processing circuitry. A mosaic photovoltaic (Hg,Cd)Te detector array is fabricated on the insulator layer. The photosignals from the detector array are coupled to the CCD circuitry by thin film electrical interconnects together with contact pads which extend through the insulator layer and are exposed at the surface of the insulator layer.

Abstract: A thermally actuatable electrical switch construction having a deformable contact member normally disposed in electrical contact with a stationary contact member while a temperature sensitive member of the construction is in a solid condition and being deformed out of contact with the stationary contact member by deforming means of the construction when the temperature sensitive member is rendered non-solid by sensing a temperature above a predetermined temperature, the deformable contact member being deformed in a direction toward the temperature sensitive member by the deforming means when the temperature sensitive member is rendered non-solid and being carried by a lead that projects into the switch construction whereby the lead and the deformable contact member define a subassembly that is adapted to be initially inserted into the construction to be secured thereto.

Abstract: The improved method of the present invention comprises mixing zinc particles comprising zinc metal and/or zinc oxide with a concentration of bonding agent sufficient to bond the particles together when subject to mechanical roller pressure so as to form a continuous film but insufficient to totally encapsulate the particles, treating the resultant mixture to form a freely flowable doctorable powder of mesh size below about 40 mesh, doctoring the powder to a desired thickness on a conveyor, rolling the doctored powder in a nip between pressure rollers to form a continuous film, combining the film with a current collector and then dividing the resultant film into zinc electrodes of predetermined size.In carrying out the method, the current collector may be passed into the pressure nip along with the doctored powder during formation of the film.

Abstract: A method of producing a structure of connection terminals with contacts includes a step of forming a synthetic resin by molding with a comb-shaped intermediate material buried therein such that end portions of the terminals of the intermediate are left unburied and cutting off the portion of the intermediate material connecting the terminals from the terminals.

Abstract: An automated assembly apparatus for inserting electrical parts into a printed circuit board includes parts supply means for supplying parts to parts conveyance means according to a predetermined sequence. The parts conveyance means is equipped with parts conveyance jigs and an identification code the detection of which determines the parts which are delivered to each jig for eventual conveyance to parts insertion means equipped with a plurality of chucks adapted to successively transfer the delivered parts, regardless of their size and shape, to an awaiting circuit board, and to insert the parts into the circuit board at prescribed positions according to a predetermined sequence.

Abstract: A method of inserting and fixing, by means of a machine, lead wires of the electronic components to a printed circuit board having a number of lead-wire-inserting holes, wherein a movable member relative to the printed circuit board is abutted to an electronic component which is already planted (or inserted) in the neighboring space of the targeted lead-wire-inserting holes for the component-to-be-planted, in order to slightly push away the already planted component for clearing or expanding the neighboring space, by means of causing a deformation to the lead wires of the already planted component. This invention includes the provision of apparatuses for realizing the above-mentioned method into practical use.

Abstract: A glass cutter includes a head at one end, a manipulator at the opposite end, a casing arranged at the head and defined by a support plate and a circular cover plate firmly connected thereto, a plurality of cutting discs supported circularly and rotatably between the support plate and the circular cover plate, of which cutting discs always one is in readiness for cutting. The casing of the cutting discs is retained exchangeable in an elongated recess at the head of the glass cutter and the support plate is formed multi-edged at the perimeter. The support plate of the cutting discs engages with two flattened faces parallel to one another at lateral confinements of the recess which defines an arc at its inner end at the head of the glass cutter. Two opposing grooves parallel to the lateral confinements of the recess are associated with the recess in advance thereof for accommodating the portions of the stand-by cutting discs projecting relative to the casing of the cutting discs.

Abstract: A chain saw having an improved safety brake actuating mechanism is disclosed. The actuating mechanism includes a safety lever pivotally mounted on the chain saw housing for movement from an operating position to a braking position in which a brake band is brought into frictional engagement with motive means which drives a cutting chain. A latching member is pivotally mounted on the safety lever for releasable latching engagement with the housing. A spring member engaged intermediate the housing and the latching member exerts a yieldable force on the safety lever which constantly biases the safety lever for movement from the operating position to the braking position while also exerting a yielding latching force on the latching member.

Abstract: A hand-held instrument is illustrated wherein a counting cycle may be initiated by pressing the active electrode against a tooth to be examined. A digital to analog converter controls a battery operated current source to supply stimulating current pulses whose intensity is linearly increased in steps at the counting rate, independently of the electrical resistance presented by the external current flow path. The counter controls an indicator which displays the successive output current values, and displays the last reading for a predetermined time interval at the end of the counting cycle.

Abstract: An orthodontic spring clip is made of bent wire and comprises a first portion which is preferably formed of at least two spaced elongated members, adapted to engage over at least a part of a portion of a bracket having an arch wire receiving opening therein, and to pass over at least a portion of the arch wire receiving opening of the bracket in order to retain an arch wire in the opening relative to the bracket. The spring clip further comprises a second portion comprised of at least two elongated members coupled to the first portion of the clip and adapted to engage the bracket with the first portion of the clip at least partially covering the arch wire receiving opening of the bracket. Further, means is provided for coupling together the elongated members of at least one of the first and second clip portions. Further disclosed are specific spring clip arrangements and novel bracket constructions having means cooperating with orthodontic spring clips.

Abstract: A beta-titanium alloy wire is used as the force-imparting component in orthodontic appliances. The alloy provides up to a threefold improvement over 18-8 stainless steel wire in load deflection rate and a twofold increase in maximum elastic displacement while providing a low modulus of elasticity and optimum low level force magnitudes. The wire also finds utility as ligature wires, as clasps and related structures in orthodontic and prosthetic appliances and as surgical arch bars for jaw fractures and the like.

Abstract: An orthodontic method for moving maxillary teeth by spreading the midpalatal suture completely obviates the time-consuming procedure of securing the appliance to the teeth by means of orthodontic bands and brackets specially fitted around the teeth by directly bonding the appliance to lingual surface areas of the teeth. An improved maxillary expansion appliance includes a pair of U-shaped anchoring elements each having a plurality of mounting pads secured thereto which are adapted to be bonded by means of an adhesive directly to lingual surface areas of opposed maxillary teeth and form the sole points of contact between the appliance and the teeth, yet provide firm anchoring of the appliance to the teeth while significantly improving oral hygiene and eliminating the unsightly appearance of orthodontic frame work on the facial surfaces of the teeth visible when the lips are parted. The improved appliance includes shiftable structure for facilitating final fitting of the appliance to the teeth.

Abstract: A drilling apparatus for the preparation of bone cavities includes a plurality of drills which are simultaneously driven in opposite direction with the cutting surfaces of each drill overlapping the cutting surfaces of at least one other drill to provide intersecting bone cavities. The drills may be driven by gearing located within the drill head or by gearing located in an attachment suitable for connection to a conventional drill head having a single output drive. The drills may be disposed along a straight or curved line or may be disposed in a triangular relationship with the axis of rotation of one of the drills being transversely movable relative to the axis of rotation of another drill.

Abstract: A housing for containing a dental amalgamator is adapted both to retain liquid mercury lost during operation of the amalgamator such that the liquid mercury may be recovered and confine mercury vapor evolved during amalgamation and exhaust the mercury vapor safely without contaminating the atmosphere of the room or dental office in which the amalgamator is located. The housing includes an opening for access to the amalgamator to insert and remove the mortar and pestal, the opening being normally sealed by a removable closure.

Abstract: Curved dental pliers particularly suited for removing crowns and other dental prostheses are scissors-like or nut-cracker-like in action, the scissors-like pliers having a pair of fulcral projections to the rear of the pivot joint and the others having a fulcrum at the pivot. The fulcral projections locate a proper fulcral point and provide for proper orientation in the arc of removal. The pliers include interchangeable removable cushioning pads for gripping the dental work without damaging same. A support member for use in conjunction with the pliers provides a firm base for receiving the thrust of the fulcral projections.

Abstract: A method for producing a bend comprising a plurality of curvatures of square steel wire for tooth regulation by means of a loop bending pliers, wherein the wire is secured against torsion about its longitudinal axis in a holding device during curving. This is done by a wire holder having a guide bore which is open at both ends and the cross sectional outline of which is adapted exactly to the cross sectional outline of the wire.

Abstract: A linear marking device is provided comprising a ruled straight edge having transparent properties and constructed with a marking implement groove and unique surface gripping strip.

Abstract: A part sizing system in which the upper and lower tolerance limits are illuminated on the same bar graph display. Electrical representations of the upper and lower tolerance limits are alternately coupled to the bar graph display so as to superimpose visual indications of both limits on one another, with each limit being distinguishable from each other by different light intensities. In one embodiment this bar graph display is disposed adjacent another bar graph display in the same housing. The other bar graph display is utilized to provide a visual indication of the output of at least one variable reluctance transducer which measures the size of the part under test. Improved transducer excitation circuitry is also provided for insuring accurate measurements.

Abstract: A process for continuously testing the thickness of the enamel coating of electric wires, in which the wire, after enamelling, passes between a fixed and a movable measuring roller. The wire is wrapped around the fixed measuring roller such that its wrap-around angle has a value between 0 and 15 degrees and the fixed and movable measuring rollers are positioned relative to each other such that their respective planes of symmetry are vertically displaced by a value between 0.5 and 2 mm. Using the process according to the invention, the thickness of enamel applied to the wire can be kept constant to about 0.5 .mu.m.

Abstract: A readily transportable device of relative light weight comprising a pair of tensioned guides for providing accurate and stable reference planes. An embodiment comprises a pair of rods or guides in tension between a pair of end members, the end members being spaced apart by a compression member. The tensioned guides provide planes of reference for measuring devices moved therealong adjacent a component to be measured. The device is especially useful for making on-site dimensional measurements of components, such as irradiated and therefore radioactive components, that cannot readily be transported to an inspection laboratory.

Abstract: An apparatus to be mounted on conventional sextants permitting faster, more accurate readings with memory storage capability. Alternative transducing means are attached to a sextant arm and generate electronic signals corresponding to amount of rotation of the arm. An electronic timing circuit is coupled to the angle signal generator such that both angle and time may be displayed instantaneously in digital format or stored for later display. Multiple memory circuits allow multiple sextant readings and times to be consecutively taken and stored without requiring separate acts of manual data recordation by the operator after each sighting.

Abstract: Survey apparatus and method employs one or more rate gyroscopes having spin axis components directed along an instrument travel axis and in also in directions normal to the travel axis, so that when the gyroscope or gyroscopes are rotated, the earth's rate of rotation will be detected, at all latitudes and at all instrument attitudes.

Abstract: A gyroscopic device of the type having a short-circuited rotor winding or conductor so shaped so as to produce axial and radial flux components when rotated in the earth's magnetic field is coupled to a coaxial sensing coil coaxial which gyroscopically stabilized thereby, signals induced in the sensing coil due to the axial flux component of the rotor is used to derive magnetic heading information and there is provided at least one further coil on the supporting body and inductively linked to the sensing coil and rotor such that when the sensing coil is gyroscopically stabilized by the rotor, the coil supported on the supporting body in relation to the gyroscopically stabilized sensing coil is such that any changes in angular orientation of the supporting body relative to the gyroscopically stabilized sensing coil introduces changes in the signal voltages induced in the coils.

Abstract: A chalk line dispenser comprising a drive casing and a replacable reel casing, which are joined to form a complete assembly. The drive casing includes a shaft and a coil spring-powered drive therefor, with a thumb-operated lever for releasing a clutch to enable spring reeling of the line. The shaft extends from the drive casing in square cross-section and is engaged by a complementary opening in the reel. The reel casing carries the reel and powdered chalk, and includes a ledge over which the chalkline passes when being reeled into the casing. A squeegee carried on the thumb operator of the clutch release presses the chalkline against the ledge to squeeze any moisture from it, causing same to drop into a moisture sump carried below the ledge. A desiccant may be carried in the moisture sump and/or may be mixed with the powdered chalk itself.

Abstract: Procedure for drying an organic material, most suitably one which is xylogenic (originating from wood), such as veneers for instance, by means of hot circulating air which circulates in the drying space from a blower to a heat exchanger, passes by the organic material, collecting the water vapor released by the material, and further to the blower, whereafter part of the air/water vapor mixture is conducted through a vent, throttled by means of a damper, into the free atmosphere. In the drying space, the temperature and pressure are monitored, and the damper is used to control the vented air quantity in such manner that there is continuously a given, predetermined vacuum in the drying space.

Abstract: A freeze dryer for rapidly and efficiently drying tissue specimens, having a source of heat independent of the cover and mounted for efficient heat transfer to a copper support plate having a substantially flat top surface. A specimen plate is machined from aluminum to have a recessed bottom surface which is matable with the support plate for maximum physical contact. The specimen plate has peripheral walls of a thickness and a height that will eliminate substantially all heat differentials between different portions of the specimen plate interior caused by external variations to allow effective control of the temperature of the specimen plate.

Abstract: A device is provided for drying wide textile webs, and the like, by means of a circulating, heated, gas-like treatment medium which is blown laterally across the web of material by means of jet nozzle elements having upper and lower fingers which are symmetrically arranged with respect to the web of material and extend over the total width of the textile web. The fingers of each nozzle element are provided with one common inlet opening for charging the treatment medium, and the openings for the jet nozzles are alternatively positioned on one side, and on the other side of the web, so as to ensure an even distribution of the treatment medium over the total face of the textile web, after which, the treatment medium flows off the side of the web opposite the common inlet opening.

Abstract: Polyester granules are crystallized and dried by passing hot gases of 120.degree. to 190.degree. C. in upward direction through the stationary layer of loose polyester granules resting in a cylindrical container on a plane or conical perforated tray slowly rotating about its vertical axis. The hot gas is passed through the material in an amount such that no fluidization is brought about. Under the action of the hot gas the granules agglomerate and the agglomerate is alternately slightly lifted and lowered again by stripping edges on the perforated tray whereby the agglomerate portion resting on the tray is disintegrated and the crystallized granules are discharged through slots behind the stripping edges in the tray.

Abstract: An educational toy comprising support means arranged or arrangeable to define a plurality of adjacent stations, a supply of elements each bearing at least one character from which elements the solution of a problem represented by the stations can be built up by placement of the elements on respective stations, and co-operating means on the stations and elements, for verifying that a correct element is mounted on any station, characterized in that the supply of elements is divided into a plurality of groups each having a distinctive visible coding and the stations each bear the appropriate group coding, so that an appropriate element can be chosen from a predetermined number of possibilities corresponding to the number of different elements in its group. The support means can consist of a board marked with a device showing the problem and associated means for receiving the elements, and constituting the stations. Alternatively, the support means can consist of reference elements, cryptically marked e.g.

Abstract: Means for driving the back walls of the buckets of an excavating wheel having a plurality of circumferentially arranged digging buckets. Each digging bucket is provided with a pivotal back wall mounted on the excavating wheel. The excavating wheel is rotatably mounted on a central shaft. A central sprocket is freely rotatably mounted on a bucket wheel hub which is mounted on the central shaft. A mounting bracket is attached directly to the main frame of the vehicle and extends outwardly therefrom. An offset sprocket which is smaller in diameter than the central sprocket is rotatably attached to the opposite end of the bracket. The axes of rotation for the central sprocket and the offset sprocket are parallel. A continuous chain passes around the sprockets with the chain constrained to move in a predetermined path. Push rods are pivotally attached at one end to connecting links of the chain so that the push rods are disposed at equal intervals along the length of the chain.

Abstract: In an apparatus for the continuous pressing and decatizing of fabric, a pressure belt serves to move a fabric undergoing treatment around a rotatably-mounted and heatable cylinder. The pressure belt directly contacts the fabric to press it against the cylinder. The surface of the pressure belt is arranged to be heated by a heating roller around which the belt passes prior to passage around the cylinder. The cylinder and heating roller can be independently heated to different temperatures to produce a temperature differential across the fabric as it is pressed. As a result, moisture condensation preferentially occurs on one side of the fabric causing luster reduction on that side of the fabric.

Abstract: A steam iron having an arrangement for producing a puff of steam, in which a duct between the water reservoir and the steam chamber, through which duct the water serving to produce the puff of steam passes into the steam chamber, can be opened and closed by a valve stem operatable from outside the steam iron.

Abstract: An information locket includes an outer housing having substantially parallel front back walls and a partial side wall, and an inner member which is pivotally connected between the front and back walls. The inner member includes a magnifying lens portion and an inner member side wall. The inner member has a storage position in which it is held between the front and back walls of outer housing with a portion of the inner member side wall forming the remaining portion of the outer housing side wall. An information bearing card, which contains personal and medical information printed in substantially reduced form, is held in a compartment formed by one surface of the magnifying lens and the inner member side wall. When the inner member is pivoted to a viewing position, the information bearing card may be removed from the compartment and read by looking through the magnifying lens portion of the inner member.

Abstract: The benefits of a dual caliber gun have been set forth in various periodis. Dual caliber revolvers come into consideration as training weapons. Dual caliber revolvers are also important in survival situations, for example downed aircraft or lost hunters. Prior art dual caliber pistons have one barrel below the other one. Such guns possess an inherent accuracy disadvantage. In addition the internal mechanisms of the guns differ so drastically from standard guns that manufacture is expensive and reliability questionable. A more reliable dual caliber gun is provided herein which has a single trigger, normal spring action, and an unmodified firing mechanism.

Abstract: A fishing lure body has at least one cone shaped air trap pocket with a small apical port opening to the outside whereby on entry of the lure into fishing water the air in the pocket provides some buoyancy and the air is adapted to bubble from the pocket as a fish attractor. Water in the pocket provides a reflecting surface visible through the opening and serves as a further attractor. Soft flexibly resilient structure of the body permits the water to squirt from the pocket through the opening when a fish strikes the lure. The body may be of various forms such as simulating a worm, a lizard, salamander, grub, and the like.

Abstract: An improved fishing rod holder comprised of a support having a bar pivotally mounted thereon for movement between two positions. The bar has a tube near one end thereof for receiving the butt end of a fishing rod and a U-shaped clip near the other end for receiving an adjacent portion of the fishing rod. When the bar is in one position, the fishing rod is inclined and when the bar is in the other position, the fishing rod is almost vertical. One or more springs bias the bar toward the other position. A latch releasably holds the bar in the one position and a solenoid coupled with the latch releases the latch and allows the bar to move quickly from the one position to the other position. A pivotal arm coupled with the switch in the circuit of the solenoid triggers the solenoid when the line on the fishing rod increases in tension. A lock is used to lock the bar in the one position for carrying purposes.

Abstract: Construction elements have two oppositely arranged, connected body portions each having an external surface configuration disposed in the planes of a particular preselected triangular shape. Each body portion has three, outwardly converging, tapered projections with each having one of its projections cut off at a narrower end portion and the cut-off projections are connected together to provide four outwardly extending projections which serve as male connectors. Two adjacent projections extend in the same direction along spaced parallel planes and two projections are oppositely arranged to project out in generally opposite directions. An inwardly converging recess is formed between the adjacent projections which serves as a female connector to interfit with complementary male connectors.

Abstract: An educational toy is a doll of the stuffed variety having a fabric cover. The doll includes a trunk and body appendages, and the trunk has a cavity therein. A fabric door is hingedly connected to cover the cavity, and has indicia thereon. A baby doll is removably carried within the cavity.Self adherent patches are located at selected positions on the assembly whereby the baby doll is attachable to the main doll body.

Abstract: This invention relates to a kinematic art form and amusement device that produces a wide variety of pleasing visual illusions through the combination of a rotating patterned body and pulsating light source.

Abstract: A model racing car having front wheels, rear wheels, drive motors and a radio control receiver and of the front drive type that is adapted to control a large steering angle of the front wheels by means of the output of the radio control receiver, wherein a plurality of the drive motors with reduction gear devices, mounted on each of the front wheels for driving the front wheels independently are caused to rotate in an interlocking fashion as a block by the output of the radio control receiver, whereby the steering angle of the front wheels is controlled.

Abstract: Each of a plurality of rectangular sheet-like plates of rigid material has a plurality of square holes formed therethrough in rows and columns. Each of a plurality of anchoring strips of rigid material is of elongated narrow rectangular configuration with a point formed at one narrow end thereof for penetrating the ground. Each of the anchoring strips has a plurality of square holes formed therethrough in rows and columms. A plurality of selectively openable and closable rings have a diameter sufficient to accommodate two of the plates and passable through the holes thereof. Each of a plurality of bolts has a head with an extending square cross-sectioned shank portion fittable in the holes of the plates and strips whereby the plates are securable to each other via the bolts and wing nuts in any desired structural combination.

Abstract: A plant container having a plurality of downwardly extending compartments, each retaining a dirt ball having the root structure of a growing plant. Each compartment has an open top end and side walls converging downwardly and terminating at the bottom end of the compartment. The bottom end of the compartment is constructed of thin material and is slitted to form yieldable flap members that can bend reverse inwardly on themselves so that an ejecting plunger can be moved upwardly through the bottom of the compartment to eject the dirt ball without damaging its structural integrity.

Abstract: A sensing system for use in a garage or other similar enclosure having an automatic door operator for automatically opening a garage door responsive to a lack of sufficient oxygen therein including a gas detector located within the enclosure responsive to actuate a detection relay which in turn will close a normally open detection switch, the closing of the detection switch will normally cause operation of the door operator to allow oxygen to enter into the enclosure through the door opening, the detection switch being located in a door opening control circuit which includes therein a first limit switch which is open whenever the door is open in order to prevent actuation of the door operator when the door is already open, the door opening control circuit also including a delay clock and delay switch which will be normally closed to allow operation of the door operator, this system also including a time delay circuit with a second limit switch therein which is adapted to be normally open and to close only whe

Abstract: Apparatus for automatic lapping control, based on imbedding an electrode of special construction in a lapping plate of a lapping machine, including at least one piezoelectric wafer in the lapping load, sensing the resonance frequency of the piezoelectric wafers as they pass by the electrode, and automatically terminating the lapping when the resonance frequency equals or exceeds a target frequency; the special electrode construction comprising a facing of a dielectric material with a high dielectric constant and surrounded by an insulator having a low dielectric constant and an average wall thickness larger than its wall thickness at the surface of the lapping plate.

Abstract: A blade sharpener includes a thin cylindrical sharpening rod made of a ceramic material which is loaded with a strong abrasive. This rod is equipped at each end with a conical guide-guard. Means is provided to position the rod with one hand so that the other hand can be used to draw the blade simultaneously along the rod and along the blade from near the blade handle toward the blade tip. The angle of the conical surfaces of the guide-guards with respect to the sharpening rod is the same as the desired angle of the blade to the rod while sharpening. The blade is initially positioned flat against the conical surface of one of the guide-guards to set the angle of the blade to the rod, and that angle is manually mantained during each sharpening stroke.

Abstract: Coolant separator apparatus for a grinding machine of the type used to grind, shape and bevel ophthalmic lenses with a high speed grinding wheel and utilizing recirculating coolants to promote grinding speed and grinding quality with respect to both glass and plastic lenses. The apparatus includes a first tank for containing coolant used in the grinding and edging of glass lenses and a second tank for containing coolant used in the grinding and edging of plastic lenses. Pumps are provided for separately pumping coolant from each of the tanks depending on the presence of glass or plastic. A first nozzle sprays coolant from the first tank when glass is ground and a second nozzle sprays coolant from the second tank when plastic is ground.

Abstract: A method for controlling the rotational speed of a rotary body in which drive means for driving the rotary body is actuated on the basis of predetermined step-like speed command values corresponding to rotational angles of said rotary body. At transition points between said step-like speed command values are preset one or more intermediate speed command values so that the rotary body will change its rotational speed smoothly.