Abstract: A system for providing a measure of the smoothness of a moving web in which light from a source is focused on a spot on the moving web. Light from an arc of substantially 360.degree. around the optical axis is collected and light from 120.degree. sectors of the collected light is reflected to three detectors the outputs of which are processed to provide the smoothness measure.

Abstract: A roller caliper gauge for providing an accurate measurement of the thickness of a high speed web of paper or the like in which a proximity device located within a housing disposed between a pair of rollers on a head on one side of the web is responsive to a web in an operative position adjacent to the housing. A platen on a head on the other side of the housing is pneumatically moved toward the rollers to cause the web to make line contact with the rollers when in the operative position.

Abstract: Monochromatic infrared radiation of variable wavelengths between 1.0 and 3.5 microns is directed upon a portion of a moving web, and the spectra of infrared radiation reflected from the web portion and of radiation transmitted through the web portion are separately measured by sensors located on both sides of the web. These spectra are combined to provide an absorption spectrum insensitive to any elastic scattering that is also present. Measures of the contents of the web constituents are generated by least-square fitting the individual absorption spectra of the constituents to the measured absorption spectrum of the web. Means for calibrating the reflectance and transmittance measurements and for keeping the sensor viewing windows free of dirt and dust are also disclosed.

Abstract: Apparatus for measuring the color, brightness and opacity of a moving web in which light from a plurality of sources is directed towards and through a moving web. Light reflected from the surface of the web is conveyed by a plurality of light pipes to a first photodetector array located at a point remote from the web. A circular variable bandpass filter varies the wavelength of the radiation reaching the detector substantially continuously through the optical spectrum to produce a detector output which periodically scans the optical spectrum. The detector outputs at various wavelengths are weighted by a microcomputer to produce brightness and X, Y and Z tristimulus values. Light transmitted through the web is conveyed by a plurality of light pipes to a second photodetector array also located at a point remote from the web. The photodetector is also monitored by the microcomputer to provide an indication of the opacity of the web.

Abstract: Microwave moisture measuring apparatus for on-line monitoring of a paper web in which a source of radiation is measured and directed towards the web. Detectors measure the transmitted and reflected energy, and a microcomputer, also having inputs in accordance with the temperature and weight of the web, provides an indication of the moisture content of the web.

Abstract: Apparatus for measuring and controlling the color of a moving web in which a circular variable bandpass filter having a passband varying substantially continuously with angular displacement through the optical spectrum is interposed in the optical path between the web and a detector and is rotated to produce a detector output which periodically scans the optical spectrum. In one disclosed embodiment, the detector outputs at the various wavelengths are weighted to produce X, Y and Z tristimulus values while, in another disclosed embodiment, dye flows are so controlled as to minimize the total square error between the measured reflectance spectrum and the desired reflectance spectrum.

Abstract: Microwave moisture measuring apparatus in which a plurality of transmitting antennas direct microwave radiation through individual portions of a moisture-containing sheet material to respective receiving antennas coupled to a common detector. A microwave pulse is provided to one end of a transmission line containing delay elements to provide successively delayed pulses to the transmitting antennas. The delayed pulses are separately received by the detector and analyzed to permit individual measurement of the moisture content of the sheet material portions.

Abstract: In a feedback color control system for controlling the flows of two colorants used to color an article, a first error signal is generated as a function of deviations in the color saturation of the article from a desired saturation, and a second error signal is generated as a function of deviations in the hue of the article from a desired hue. The flows of the dyes are varied in the same sense in response to the first error signal and are varied in opposite senses in response to the second error signal.

Abstract: Apparatus for determining the content of moisture or other substance in a material by measuring its relative reflectance at two infrared wavelengths. A chopped radiation beam is produced by arranging a tuning fork such that an oscillating element alternatively moves first and second spaced optical bandpass filters having first and second passband wavelengths into position to intercept a beam of source radiation. The chopped beam is directed on the material being analyzed, and radiation reflected therefrom is applied to a radiation detector. The relative transmittances of the filters at their passband wavelengths are such that the radiation detector generates alternating pulses of equal amplitude for a material having a specified content of the substance. The tuning fork also includes a third filter of zero transmittance which periodically interrupts the beam of source radiation so that the detector provides a background signal which is used to correct the amplitudes of the alternating pulses.

Abstract: Coherent electromagnetic radiation is directed upon particles suspended in a fluid medium to produce scattered radiation. The particles are subjected to an electric field alternating between a first and second intensity. The coherent radiation and the scattered radiation are directed upon a detector to produce a heterodyne signal the spectrum of which is analyzed. The spectral composition of the heterodyne signal obtained with the first intensity of applied electric field is compared with the spectral composition obtained with the second intensity of applied electric field to provide a measurement of the electrophoretic mobility of the suspended particles.

Abstract: An on-line system for determining the content, in a sheet material such as a paper web, of one or more additives such as titanium dioxide exhibiting relatively high-energy X-ray fluorescence and of an additive such as clay exhibiting relatively low-energy X-ray fluorescence. The sheet is irradiated with X-ray radiation of sufficiently high energy to cause the high-energy fluorescence additives to emit fluorescent radiation. Fluorescence intensity signals are generated as a function of the intensity of the fluorescent radiation from the high-energy fluorescence additives, and an absorption signal is generated as a function of the radiation passing through the sheet material without being absorbed. The fluorescence intensity signals are used to determine the content of the high-energy fluorescence additives and to determine the expected absorption of the exciting radiation by the material with the determined contents of those additives.

Abstract: An optical shoe assembly for use with an optical head in an on-line system for continuously monitoring the color, opacity and brightness of a moving web of paper, or the like, in which the shoe frame supports a length of the web over a housing opening, the edge of which is normally in a sealing relationship with the edge of a first side of a block rotatably supported in the housing.This first block side is formed with an optically black recess covered by a quartz shoe carrying a transversely extending white background over a portion thereof to provide spaced white and black backgrounds in the normal operating condition of the shoe assembly. Respective second and third sides of the block carry a white standard, such, for example, as a mirror, and a black standard which standards may selectively be positioned in the housing opening by a motor which drives the block mounting shaft.

Abstract: In a multi-stage bleaching system in which respective bleaching chemicals are added to the stock in various stages, apparatus in which in the first stage in which chlorine is added to the brown stock, the first of a pair of sensing units associated with the stage comprises a source of red light directed onto the incoming brown stock and a suitable detector for sensing light scattered from the stock to produce a first signal representative of the brightness of the incoming stock and the second similar sensing unit of the pair senses the brightness of the stock immediately following the addition of chlorine to produce a second signal. The first and second signals are compared to produce a difference signal indicative of the change in brightness independently of the condition of the incoming stock and this difference signal is compared with a set point standard to provide a control signal for regulating the addition of the chlorine to the brown stock.

Abstract: An on-line system for continuously monitoring the color, opacity and brightness of a moving web of paper or the like in which an optical shoe providing black and white backgrounds spaced in the direction of movement of the web supports a portion of the web below and generally in registry with an optical head made up of a light integrating sphere for directing light from a source onto the web over the shoe and a plurality of elongated sensing units mounted in the upper portion of the sphere and including a centrally located brightness measuring unit oriented generally perpendicularly to the web toward a point over the black background, four circumferentially spaced color tristimulus sensing units, each of which is oriented at an angle to the axis of the central unit so as to be directed at the same point as is that unit and a sixth opacity sensing unit angularly oriented with respect to the axis of the central unit so as to be directed toward a point over the white background spaced downstream of the first poi

Abstract: An on-line system for determining the content, in a sheet material such as a paper web, of one or more additives such as titanium dioxide exhibiting relatively high-energy X-ray fluorescence and of an additive such as clay exhibiting relatively low-energy X-ray fluorescence. The sheet is irradiated with X-ray radiation of sufficiently high energy to cause the high-energy fluorescence additives to emit fluorescent radiation. Fluorescence intensity signals are generated as a function of the intensity of the fluorescent radiation from the high-energy fluorescence additives, and an absorption signal is generated as a function of the radiation passing through the sheet material without being absorbed. The fluorescence intensity signals are used to determine the content of the high-energy fluorescence additives and to determine the expected absorption of the exciting radiation by the material with the determined contents of those additives.