Eastman-kodak Company

Other

Nexpress Solutions, Inc.

Allen J Rushing

Matthias Hermann Regelsberger

William A Hameister

Yee S Ng

Peter S Alexandrovich

Philip A Stern

Kelly Stephen Robinson

Anne F Lairmore

Bruce R Benwood

George N Tsilibes

David R Jackson

Walter B Sherwood

David D Almeter

Bruce B Steele

Paul A LaChapelle

Dongli Yang

Donald J Clar, Jr

Brian D McLean

Sally L Stearns

A densitometer using a light-to-frequency converter is disclosed. The converter outputs an oscillating signal with frequency characteristic of the incident light intensity. Digital controls may be input to the converter to set the frequency range of the output. The period count or frequency count of the converter output may be numerically divided to obtain a quotient within a small range. A lookup table is addressed according to the period count or frequency count, and return an offset scaled logarithm. The lookup table output is processed numerically to obtain a scaled density value. The converter may be adapted to process analog voltage inputs rather than light inputs. The logarithmic conversion then becomes applicable to a variety of fields besides densitometry.

Digital densitometer using light-to-frequency converter

A multi-channel densitometer has a light sensor for each channel. The channels may be on a single circuit board, or may be on small, independently locatable probes. The outputs from the sensors are input to a single conveniently located controller circuit. The controller circuit provides power and control signals to the sensors, and processes the sensor outputs to obtain sample optical density. The multi-channel configuration saves space where the density measurements are needed, reduces the component count and cost, and facilitates calculation of multi-channel density functions, such as uniformity, transfer efficiency and color balance.

Multi-channel densitometer

A densitometer with a controllable light emitter intensity operates to reduce excessive exposure of sensitive materials, such as photoconductive film. During normal printer operation, the emitter is operated in a pulsed-mode, thereby reducing emitter temperature and prolonging its useful life. Exposure of the photoconductor is also reduced, which may prolong its useful life and avoid image defects. The pulse width, frequency, and duty-cycle are chosen to give these benefits without compromising density measurement capability. The emitter drive circuitry is connected to a motion sensor so that emitter intensity is reduced to a low level when photoconductor motion is stopped. A test mode is provided during which the emitter intensity is reduced by a calibrated amount, simulating the presence of a calibrated test sample.

Digital densitometer with controlled light emitter

A method and apparatus of generating rendered image data for use in reproducing an image with a series of patterns of halftone dots. In the method and apparatus an unrendered pixel value of a pixel to be rendered is compared with each of a series of threshold values in accordance with respective comparison criteria and a grey level for a rendered pixel of a halftone dot is generated by having certain threshold values define increasing grey level values of the rendered pixel upon meeting respective criteria and at least one threshold value of the series defines a decrease in grey level value of the rendered pixel for meeting a respective comparison criteria.

Apparatus and method for rendering halftone dot structures using grey level dots

An auto-ranging digital densitometer, for determining the optical density of a test sample, includes a photodetector and a digital logarithmic converter. Within the logarithmic converter, an amplifier circuit is adapted to produce an output signal proportional to intensity of light incident on the photodetector. The amplifier circuit has multiple gains that successively increase, one to the next, by a ratio between 2.3:1 and 5.7:1. Gain select logic selects the gain to provide good density resolution and avoid amplifier saturation. An analog-to-digital converter is adapted to convert the output signal of the amplifier circuit to digital format. A lookup table address is formed at least in part from the output of the analog-to-digital converter. The lookup table outputs at least the lower-order digits of the density value corresponding to the gain and the amplifier output. Density range is extended, resolution improved, and the requirement for a second lookup table is eliminated. The digital logarithmic converter portion of the densitometer is also applicable to other fields besides densitometry.

Auto-ranging digital densitometer with lookup table

A densitometer with built-in data processing capability uses synchronizing signals to collect data at defined spots on a moving endless belt or drum test sample. A calibration cycle accumulates data for later use in measurement correction. After correction, measurement data are output or stored for later output to a host processor or display device. Data averaging, filtering, smoothing, statistical functions, and pattern recognition are also provided by the densitometer circuitry.

Digital densitometer with calibration and statistics

An auto-ranging densitometer is disclosed for determining the density of a test sample, wherein the densitometer includes a photodetector and an amplifier circuit adapted to produce an output signal proportional to intensity of light on the photodetector. The amplifier circuit has multiple gains that successively increase in an approximately 2:1 ratio increment. An analog to digital converter is adapted to convert the output signal of the amplifier circuit to digital format. A density signal generator circuit is adapted to receive the output of the analog to digital converter, whereby density resolution non-uniformity is minimized due to small gain increments such that the analog to digital converter needs deal with less extreme variations in density resolution.

Digital densitometer with auto-ranging

An auto-ranging densitometer includes a photodetector and an amplifier circuit adapted to produce an output signal proportional to intensity of light on the photodetector. The amplifier circuit has multiple gains that successively increase. An analog to digital converter converts the output signal of the amplifier circuit to digital format. A gain select logic outputs a gain code used to select the gain of the amplifier. A density signal generator circuit includes two LUTs, one of the LUTs being adapted to receive the output of the analog to digital converter and produce an output density scaled to include only low order bits; and the other of the LUTs being to receive the gain code and produce an output density scaled to include only high order bits. The outputs of the two LUTs are concantenation added to produce a summation density signal.

Digital densitometer with lut output summation to yield density value

An optical densitometer includes a receiver adapted to produce an electrical output voltage characteristic of an optical density to be measured. A voltage-controlled oscillator produces a periodic signal having an output waveform with a frequency and period characteristic of the output voltage of the receiver. A counter produces a digital value corresponding to the output waveform of the periodic signal produced by the oscillator; and a converter produces a digital optical density signal from the digital value. The counter is adapted to produce its digital value corresponding to the frequency or period of the periodic signal produced by the oscillator. The counter may include a portion adapted to produce a digital value corresponding to the frequency of the periodic signal produced by the oscillator; and a portion adapted to produce its digital value corresponding to the period of the periodic signal produced by the oscillator.

Digital densitometer using voltage-controlled oscillator, counter, and

An electrostatographic recording apparatus and method includes a primary charger establishing a uniform primary electrostatic voltage level on an image recording member. A recorder imagewise modulates the electrostatic charge on the image recording member to form a latent electrostatic image. A development station develops the electrostatic image with toner. A controller controls the primary charger by periodically adjusting a signal to the primary charger in response to a signal related to charger efficiency. The charger efficiency is determined as the ratio of the charger's grid voltage to a voltage level established on the recording member. To calculate changes to the grid, voltage control patches are printed on the member and the densities used to determine changes to setpoint values for the charger.

Process control for electrophotographic recording

An electrometer probe is used in an electrophotographic apparatus as part of a process control system to measure charge on a photoconductive film belt. This measurement is used to control voltage level or other process parameter of the electrophotographic process. The probe is supported in an electrometer probe holder so that a sensor aperture of the probe is at a fixed distance from the film belt. In order to ensure proper operation of the electrometer probe, a method and an apparatus for independently calibrating the electrometer probe is provided. A curved plate is provided on the electrometer probe holder. The plate is mounted at the same spacing from the probe aperture as the film belt. This plate has a receptacle for the service person's test lead to attach. The other end of the test lead is attached to a test point for the toning station bias supply. The probe may be reoriented on the probe holder to position the probe aperture at the fixed distance to the plate. Using a service test program, different biases are applied to the plate, and the response of the electrometer is monitored. In this way, troubleshooting of electrometer related errors is easily done without the need to remove the electrometer probe to a special test apparatus.

Electrostatographic reproduction apparatus with electrometer control and

An electrostatographic reproduction method and apparatus includes an electrostatic recording member moving in a process direction. A plurality of recording elements on a writer imagewise expose the recording member to form electrostatic latent images on the recording member. The writer includes driver circuitry for actuating selected recording elements. The exposed recording member is then moved through a development station to develop the latent images. The developed images are transferred to a record member. An operator selectable adjustment controller is manually adjusted for generating adjustments in operation of the recording elements to compensate for a misalignment of a process station in the apparatus.

Copier/printer with manual adjustment for cross-track uniformity

A reproduction apparatus and method particularly suited for an electrophotographic DAD-CAD system having an electrostatic recording member for supporting an electrostatic image, a primary charger establishes a primary charge on the member, the primary charge being defined by a parameter V.sub.o. An exposure device imagewise modulates the primary charge to form an electrostatic image on the recording member. The device has an exposure parameter E.sub.o. A developer station develops the electrostatic image with charged toner. The developer station has an electrical bias to establish a field for urging movement of the toner to the member. The electrical bias has an alternating current component parameter AC and a direct current parameter DC. A controller controls adjustments to the parameters E.sub.o, V.sub.o and AC by measuring a density parameter D.sub.OUT of an exposed and developed area on the member that is formed by operation of the primary charger, the exposure device and the developer station. The controller includes a calculator for calculating an error, .DELTA.D.sub.OUT in the measured density parameter from a density setpoint and multiplying .DELTA.D.sub.OUT by respective first, second and third constants to obtain respective adjustment values used for adjusting E.sub.o, V.sub.o and AC and wherein in repeated use of the controller to provide repeated adjustment values used for adjusting E.sub.o, V.sub.o and AC a fixed ratio is maintained between said first, second and third constants. The controller is also suited to providing adjustments to DC using a fourth constant.

Method and apparatus for controlling production of full productivity

A method and apparatus of producing images includes a primary charger for depositing a primary electrostatic charge on an electrostatographic recording member. A first electrometer measures or senses the primary electrostatic charge. A light source such as an EL panel is enabled to reduce the level of the primary electrostatic charge to provide a reduced voltage level suited for recording on the image frame. The reduced voltage level on the image frame is imagewise modulated to form an electrostatic image. The electrostatic image is then developed with toner. The output of the EL panel is adjusted in response to a first factor related to a measured value of the level of the primary electrostatic charge and a set point value for the level of the reduced voltage level and a second factor related to error in the level of the reduced voltage level from the set point value for the reduced voltage level. In a specific embodiment of a DAD-CAD process, the primary charge on the image frame is imagewise modulated by a first ROS device and developed with a DAD development station. Thereafter, the image frame with the reduced charge level is imagewise modulated by a second ROS device and developed by a CAD development station.

Growing community of inventors

Webster, NY, United States of America

Allen J Rushing