Abstract: A method for making a bed for a gantry-style milling machine, where said machine has a routing spindle which said machine is capable of moving in the X, Y and Z directions, and where said machine has means to support a bed, comprising placing material millable by the machine on said support means and planing said material level with the machine.

Abstract: A linear drive system with an associated cover system wherein said linear drive system comprises a load, a lead screw, a lead nut operatively engaged to said lead screw such that said lead nut can travel along said lead screw by virtue of rotation of the lead nut, a load engaging structure means connecting the lead nut to the load such that as the lead nut travels along the lead screw, the load is moved, and motor means operatively engaged with the lead nut such that said motor means operates to rotate the lead nut, thereby moving the load.A cover system an opening formed by two surfaces. Said cover system has a bridge structure, which can be a roller assembly, which is supported by structural means over and across the width of the opening. A band is positioned to cover the opening and is also mounted over the bridge structure. As the bridge structure is moved along the opening, the band is lifted from the opening, thereby allowing access to the opening by a device.

Abstract: A low cost servo operated digital positioning system which utilizes a phase shift control circuit in combination with an encoder and servo circuit for driving a moveable element. The encoder generates a pair of signals A which may be equivalent to a sine signal A and a cosine signal A. The phase shift circuit multiplies signals from the encoder by a sine of a demand signal B and by a cosine of the demand signal B and produces a sine (A+B) signal and a cosine (A+B) signal. These sine and cosine shift signals are introduced into a servo circuit for control of a moveable element. By phase shifting these signals it is possible to substantially increase the overall number of positions to which a moveable member may be moved and thereby substantially increase the overall accuracy of a positioning system.

Abstract: A closed loop servo operated digital control system in which a dynamically operable moveable member can be effectively and accurately controlled during movement from an initial position to a command position by compensating for both velocity error and for position error. A differential between a present measured position of the moveable member and a command position provides a position error signal. Present velocity is determined by computing position differential as a function of time. A velocity error signal is obtained by subtracting the determined velocity from a velocity command which is stored as a velocity command profile. The total error is the resultant sum of the position error and a velocity error and this sum is converted to an analog signal in order to power an amplifier/motor which, in turn, provides power for the control system.

Abstract: A microprocessor based mark-sense ballot card reading system has automatic mark detection threshold adjustment, automatic skew and card speed correction, and provision for simultaneous, accurate reading of both sides of a ballot card regardless of card input orientation. A multidispatch, miltipage real time control program is utilized to enable multiple event detection on each card side and asynchronous processing of such multiple events on a two-sided card. Positive document sensing and control are monitored by the microprocessor control system. A folded card path card transport mechanism with diverter stations operates under microprocessor control to determine card destination.

Abstract: Digital error correcting circuitry is disclosed which processes two analog output signals from an incremental position optical encoder to correct for both offset and amplitude errors. The peak amplitude values of the analog signals are stored in a digital storage register and are used to calculate bias signals of the proper polarity and amplitude to cancel the offset errors in each of the encoder signals. The peak amplitude values are also used to generate an amplitude correction factor which is applied to one of the encoder signals to correct the peak-to-peak amplitude of that signal so that it is equal to the peak-to-peak amplitude of the other encoder signal.

Abstract: A digital positioning system having high accuracy is disclosed, which employs an incremental position optical encoder as the position transducer. In response to the output signal from the encoder, the system provides coarse and fine position signals which are combined to form a composite digital signal representing the absolute position of a moveable control member. The composite position signal has a resolution of greater than one part in one million. Trigonometric conversion techniques are used to derive high resolution incremental position information from the encoder output signals.

Abstract: A positioning control servo uses a digital feedback control system and an analog feedback control system, both simultaneously generating control signals to a servo summing node. The digital system derives negative feedback from velocity values which are raised to any programmed exponential value according to a linear velocity profile. The analog system feedback signals provide a non-linear velocity profile and fine position adjustment and dominates control at the servo end of travel. Interface control is provided from multiplexing a single digital feedback control system with a plurality of servo systems. The interface control selects a unique velocity profile in a digital system for each particular servo system. No switching is required between the digital and analog systems because both have continuous input to the servo summing node.

Abstract: An apparatus adjusts the angular orientation of a moving carriage carrying a type font in a true font, stop-to-print, moving head high speed printer. This rotational adjustment provides a simple but accurate paper thickness adjustment which simplifies the printer construction and increases its reliability.

Abstract: In a solenoid driven hammer for an impact printer, the armature, which is driven by the magnetic field provided by the solenoid's coil, is integral with the hammer which strikes a printing element on a print wheel. The shape of the pole piece in the solenoid conforms to the shape of the leading surface of the armature to provide a magnetic force field that is of constant strength as the armature is propelled toward the pole piece when the solenoid coil is energized. The hammer, being unitary with the armature, is thereby propelled against the printing element. As the hammer rebounds after striking the printing element, the armature strikes a polyurethane cushion which absorbs substantially all of the energy of the armature/hammer unit, thereby bringing the unit to a complete stop so that the next stroke may be quickly commenced.

Abstract: An audio fidelity system which may adopt the form of a preamplifier or a preamplifier-amplifier combination and which includes facilities for mixing any of a plurality of input sources. In addition, the system permits equalization of the frequencies in each of a plurality of audio fidelity channels in the provision of a separate potentiometers for each of the major frequency of each channel. The circuit is uniquely designed to eliminate hum which normally occurs in low-level switches by eliminating the feedback through the amplifier circuits.

Abstract: An audio fidelity frequency equalizer system for use with audio fidelity sound equipment in order to frequency contour sound reproduction to obtain a desired listening environment. The frequency equalizer system of the present invention includes a plurality of potentiometer controls for adjusting the frequency output in each of the eleven major separate octave bands which cover a range from approximately 20 Hz to approximately 20,000 Hz. The frequency equalizer system of the present invention includes an operational amplifier with each of the aforementioned potentiometers connected across the equalizer in feedback relationship. Moreover, each of the potentiometers operate in conjunction with a unique resonance circuit in order to achieve the desired frequency adjustability of the octave bands.