Abstract: A system optically detects and measures release agent on a rotating image member in an ink jet printer. The system includes a collimated light source oriented to direct a collimated beam of light generated by the source towards a rotating image member, an image sensor for generating an image of a portion of the rotating image member from a portion of the collimated beam of light reflected by the rotating image member, an image differentiator for measuring a difference between a first image generated by the image sensor and a second image generated by the image sensor, and a release agent measurement generator that is coupled to the image differentiator to receive the difference between the two images and to generate a measurement of the release agent on the rotating image member.

Abstract: Systems and methods are provided for detecting intermittent, weak or missing jets of a printer. The detection is implemented using a test pattern. Detected failed jets may be confirmed using a verification target. A printhead containing nozzles corresponding to detected failed jets may be wiped or purged.

Abstract: A development unit used in xerographic printing retains a mixture of at least a first colorant and a second colorant. An illuminator directs toward at least a portion of the mixture a first light of one color, a second light of a second color, and a third light substantially outside of a visible range. A photosensor records a first reflectance signal based on light reflected from the mixture substantially in a visible range, and a second reflectance signal based on light reflected from the mixture substantially outside a visible range. The signals can be used to maintain the mixture at the desired total color and other properties.

Abstract: A lead edge sheet curl sensor apparatus and method are disclosed. In general, a first and a second light emitter are aligned wherein the light beams from the first light emitter and second light emitter cross. The first and second light emitter beams cross at the transport media sheet substrate path wherein the transport media sheet substrate path is the path of a media sheet substrate with zero curl. First and second light detectors are aligned to receive the light beams from the first and second light emitters. A media sheet substrate with either positive or negative curl on the lead edge of the sheet substrate interrupts light beams from first and second light emitters, as detected at first and second light detectors. The time delay between the light beam interruptions is proportional to the sheet substrate curl, and the order of interruptions indicates whether the sheet substrate curl is positive or negative.

Abstract: A lead edge and/or trail edge sheet curl sensing and constraint method and system. First and second light emitters and detector pairs are aligned such that the light beams from the first light emitter and second light emitter cross at the transport media sheet substrate path, which constitutes the path of a media sheet substrate with zero curl. A media sheet substrate with either positive or negative curl on the lead edge of the sheet substrate interrupts light beams from the first and second light emitters, as detected by first and second light detectors. A similar approach can be used to detect the trail edge curl. The time delay between the light beam interruptions is proportional to the sheet substrate curl, and the order of interruptions indicates whether the sheet substrate curl is positive or negative. A first pair and a second pair of substrate constraint rollers can also be provided in the paper path upstream and downstream of the sensing system.

Abstract: Systems and methods are provided for determining registration errors in the cross process direction of a printer. A first straight line is obtained by detecting line centers of a first plurality of dashes in a test pattern. A second straight line is obtained by detecting a line center positions of a second plurality of dashes in the test pattern. A difference between the off-set of the first straight line and the off-set of the second straight line is used in determining registration errors.

Abstract: Systems and methods provide calibration for a linear array sensor. A test pattern having a plurality of lines is used. Comparison between expected and measured spacing between a pair of neighboring lines is used to determine sensor position displacement.

Abstract: A device to measure toner concentration can include a selector that selects a type of developer material to be measured and a sensor that detects an amount of light reflected off a developer material. A controller within the device can determine a value corresponding to a toner concentration of the developer material based on the amount of light detected by the sensor.

Abstract: System and methods are provided for detecting color separation misalignment in raster optical scanners. A dash minimum response curve is obtained from a plurality of minimal responses sensed from a plurality of dashes in a test pattern. The frequency of the dash minimum response curve a is used to detect skew or bow, depending on whether the frequency is a constant or a variable.

Abstract: Systems and methods provide calibration for a linear array sensor. A test pattern having a plurality of lines is used. Comparison between expected and measured spacing between a pair of neighboring lines is used to determine sensor position displacement.

Abstract: An apparatus and method for determining toner concentration of a sample comprised of toner and carrier, including exposing the sample to light; the exposing includes emitting light at a predefined wavelength based upon the color of the toner; detecting the light reflected off the sample with an optical sensor; and determining the toner concentration of the sample base upon the light reflected off the sample.

Abstract: An apparatus and method for determining toner concentration of a sample comprised of toner and carrier, including exposing the sample to light; the exposing includes emitting light at a predefined wavelength based upon the color of the toner; detecting the light reflected off the sample with an optical sensor; and determining the toner concentration of the sample base upon the light reflected off the sample.

Abstract: A developability sensing system with an optical sensor for measuring the density of imaging material samples on an imaging surface of a printer, with an illumination source and photosensor system for measuring the amount of reflected illumination from the imaging materials. A first lens system and its first photosensor may receive both specularly and diffusely reflected illumination from certain imaging materials. A separate lenslet system is positioned outside of the first lens system. It may comprise one to four spaced apart generally cylindrical lenslets with a central axis generally perpendicular to the imaging material sample and an end surface facing the imaging material sample defined by a segment of a hyperbolic curved surface to form a rotationally symmetrical lens with a hyperbolic cross-section.

Abstract: In color printing with a color registration system for the registration of plural color images on an image bearing surface, such as a photoreceptor belt of a color printer, chevron shaped registration marks are imaged on the image bearing surface, which registration marks correspond to the color images and are sensed by a registration marks sensor as the image bearing surface moves in its process direction. The registration marks sensor has chevron shaped optical sensing areas provided by a matching pair of spaced apart elongated bi-cell detectors in a generally chevron shaped pattern. Each of these spaced apart elongated bi-cell detectors has a parallelogram shaped optical sensing area. That parallelogram shaped sensing area is defined by elongated parallelogram sides extending at the same angle as one leg of the chevron shaped registration marks, and parallelogram ends which are parallel to the process direction, so as to provide higher color registration accuracy.

Abstract: Method and apparatus for controlling amplifier gain, e.g., as used in ESV of a xerographic copier, has a light source, e.g., an LED, optically coupled to a gain control light dependent resistor (LDR). The LDR can be in a negative feedback loop around an amplifier. There is a voltage sensing probe located near the photoreceptor belt of the copier and coupled to an input of the amplifier.

Abstract: A sensor detects the presence of opaque and transparent copy substrates in a substrate transporting path and includes an LED disposed near the transporting path for projecting light toward a reflector on the opposite side of the media transport path and a phototransistor located relative to the LED and reflector to receive light reflected from the reflector which is periodically interrupted by substrates within the transporting path to provide an output proportional to the light received from the LED via the reflector. The operating range of the phototransistor has a linear portion and a saturated portion. A control, electrically connected to the sensor, adjusts the phototransistor to maintain the output signal in the linear portion of the operating range. The sensor is tilted at an angle with respect to the horizontal of a copy substrate to be able to detect transparencies.

Abstract: In accordance with the present invention a toner concentration and temperature sensing 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 sensing apparatus includes a micro controller device for controlling a sensing head to selectively generate a magnetic field within the developer container according to a first set of parameters stored in the micro controller. A preselected portion of the developer material is compressed by the magnetic field and a signal is generated across the sensing device and determining the resistance thereof. The signal across the sensing device varies as a function of the concentration of the toner. The micro controller converts the observed signal into a toner concentration value based on a second set of stored parameters.

Abstract: An infrared densitometer which measures the diffuse component of reflectivity as marking particles are progressively deposited on a moving photoconductive belt. Collimated light rays are projected onto a test patch including the marking particles. The light rays reflected from the test patch are collected and directed onto a photodiode array. The photodiode array generates electrical signals proportional to the total flux and a diffuse component of the total flux of the reflected light rays. Circuitry compares the electrical signals and determines the difference to generate an electrical signal proportional to the specular component of the total flux of the reflected light rays. Additional circuitry adds the electrical signals proportional to the total flux and the diffuse component of the total flux of the reflected light rays and compares the result of the summed signal to the specular component to provide a total diffuse signal for controlling developed mass.

Abstract: An electrostatic measuring apparatus for measuring unknowns such as the electrostatic potential of a surface in a non-contacting manner, including a tuning fork and a sensing electrode, and in which the frequencies of two different vibration modes of the fork are separated by a slotted supporting structure which is united with the fork, and in which harmful amplitudes of vibration of the fork are avoided by an amplitude limiting structure integral with the sensing electrode. The amplitude limiting structure includes arms extending around the ends of the tines.

Abstract: 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.