Xerox Corporation

Darrel R Rathbun

Gerald A Domoto

Michael D Borton

John J Ricciardelli

John Buranicz

An electrophotographic copying machine adapted to operate in either a functional or a pictorial mode, such that, in the pictorial mode, a light signal is transmitted through a line screen member to modulate an electrostatic latent image of an original document. The amount of light transmitted through the line screen is varied as a function of the amount of light used to generate the electrostatic latent image to control the contrast of the image generated thereby. As a result, pictorial image contrast is readily adjustable by regulating the light intensity of the light transmitted through the line screen member and onto the photoconductive surface for high quality pictorial copies in an electrostatographic copying machine.

Photomode contrast control system for an electrostatographic printing

A system for measuring a percentage of the solids in a liquid developer material is provided. The liquid developer material is received by a liquid developer material application member for application of the liquid developer material to a selected surface. The liquid developer material, when disposed on the developer application member as a film, is characterized by a first value varying as a function of developed mass per unit area (DMA) and a second value varying as a function of film thickness. The measuring system includes: a first sensing system for determining a magnitude corresponding with the first value; a second sensing system for determining a magnitude corresponding with the second value; and a controller, responsive to the first and second sensing systems, for determining the percentage of the solids in the liquid developer material with the determined first and second values.

Apparatus and method for measuring percentage solids in liquid developer

A sensing system for a print development system of a printing system in which a print is developed with developer material and development of the print varies as a function of both a first parameter and a second parameter is provided. The development system includes a capacitance and the sensing system, which measures a first value varying as a function of the first parameter and a second value varying as a function of the second parameter, includes a sensing subsystem for measuring an output by reference to the capacitance; and a signal development subsystem, responsive to the sensing system, for developing, from the output, both a first signal and a second signal with the first signal corresponding to the first value and the second signal corresponding to the second value.

Capacitive based sensing system for use in a printing system

A filming attenuation correcting toner concentration sensor assembly and method of controlling in a container, a concentration of a mixture that includes a light absorbing substance and a clear liquid carrier in solution, while correcting the effects of container filming. The method includes the steps of splitting light from a single light source having a controllable intensity, into a first light beam and a separate second light beam; focusing the first light beam through a first quantity of the mixture contained in a first light transmitting container made of a first material and having a first thickness, as well as focusing the second light beam through a second quantity of the mixture contained in a second light transmitting container made of the first material and having a second thickness greater than the first thickness of the first light transmitting container; generating a first proportional output signal by sensing with a first photodiode, a first attenuated light transmitted from the first light beam through the first light transmitting container and through the first quantity of the mixture; generating a second proportional output signal by sensing with a second photodiode, a second attenuated light transmitted from the second light beam through the second light transmitting container and through the second quantity of the mixture; maintaining the second proportional output signal at a constant level by adjusting the controllable intensity of the single light source; and adjusting the concentration of the light absorbing substance in the mixture such that a filming-effect independent ratio that is equal to the first proportional output signal divided by the second proportional output signal, is also maintained as a constant, thereby achieving a toner concentration of the mixed developer material that is maintained at a desired level, without the undesirable effects of filming of optical surfaces.

Filming attenuation correcting toner concentration sensor assembly and

In accordance with the present invention an apparatus is provided for use with a developer container adapted to retain a quantity of developer material, the developer material including varying concentrations of magnetic carrier material and toner material. The toner concentration sensing apparatus comprises a device for generating a magnetic field within the developer container. The apparatus further comprises a device for controlling the generating device to selectively generate the magnetic field within the developer container, wherein a preselected portion of the developer material is compressed by the magnetic field and a signal is generated across the generating device, the signal across the generating device varying as a function of the concentration of the toner.

Toner concentration sensing apparatus

A fuser temperature control using a resistive bridge driven power circuit. At the beginning of each positive half cycle of the AC line voltage, the possible firing of the triac is delayed by 100 microseconds. During this delay, the fuser temperature is checked by measuring the foil heaters resistance with a DC bridge circuit. One leg of this bridge circuit contains the foil heater. The other leg of the bridge has a potentiometer to set the temperature of the fuser. The output of the bridge circuit is fed into a differential comparator and D-type flip-flop. This combination gives high gain with very little sensitivity to noise. The differential comparator checks the fuser temperature (foil resistance) relative to the set point temperature (set point potentiometer). It determines whether the fuser temperature is above or below the set point temperature. The D-type flip-flop latches this information to either enable or disable the triac triggering circuitry for each full cycle of the line voltage. When the fuser temperature is below the set point temperature, power is enabled to heat the fuser. When the fuser temperature is above the set point temperature it is disabled to cool the fuser. This power decision is made at a rate of 60 Hz in order to keep up with the fusers instant-on characteristics.

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Ontario, NY, United States of America

Darrel R Rathbun