Optics: measuring and testing – By shade or color – With color determination by light intensity comparison
Reexamination Certificate
2000-09-25
2001-09-04
Evans, F L (Department: 2877)
Optics: measuring and testing
By shade or color
With color determination by light intensity comparison
C356S402000, C008S400000, C366S132000, C250S226000
Reexamination Certificate
active
06285453
ABSTRACT:
TECHNICAL FIELD
The present invention generally relates to on-line color monitoring and control of fibers produced by an extrusion device. More specifically, the invention relates to the measurement of the color of moving yarn or fibers soon after extrusion. Two alternative sensor mechanisms are disclosed—one which measures color prior to spooling of the product, and another which measures color after the product is collected on the spool. In addition, the color measurement signal is quickly checked against a reference signal using an optical switch.
BACKGROUND ART
In the past, the color of a product produced by an extrusion device has been monitored and controlled in an off-line manner. Typically, the extrusion device or system would be operated until color equilibrium was achieved, followed by collection of a product having a certain color. The spool of collected product would then be removed from the system, and taken to a color laboratory where the color would be measured using an off-line spectrometer. Then, once a color evaluation was made, the spool would be returned to the extrusion device or system, adjustments would be made to the level of the colorant provided to the extrusion device, and another run of about ten minutes or so would be commenced. This process would be repeated until evaluation of the color of the product in the color laboratory indicated that the desired color, within acceptable limits, had been achieved.
The latter process was not only time-consuming and inefficient, but also resulted in substantial waste. That is to say, a large amount of scrap material was produced and wasted during each run. Thus, if several runs during a given period of time were necessary in order to evaluate and adjust the color of the product, a very substantial amount of waste material would result.
The latter system or process was also inefficient from the standpoint of time in that each run would take about ten minutes or so, and then the color evaluation in the laboratory would take another thirty minutes to one hour. Thus, if several repetitions of the evaluation process were necessary before the final acceptable coloration was achieved, the entire pre-production process could take several hours.
Accordingly, there has been a need for the development of an on-line color monitoring and control system and method. Moreover, there is a need for the development of such an on-line color monitoring and control system and method employing the most modern optical technology for both transmission of incident light toward the product and reflection of light from the product, as well as handling and transfer of the light through an optical spectrum analyzer to that portion of the system which actually performs the evaluation of the coloration of the product.
It is recognized that on-line measurement of the color of extruded pellets in compounding operations is known in the art. For example, see the following: U.S. Pat. No. 3,972,854—Costolow and U.S. Pat. No. 5,559,173—Campo. In addition, on-line color control of fiber extrusion has been achieved by measuring the color of a fiber melt. In this regard, see U.S. Pat. No. 4,684,488—Rudolph.
Nevertheless, measurement of the color of moving yarn or fiber (or a filament of a yarn), or of a collection of fibers, is not known in the prior art. Moreover, the employment of alternative sensor mechanisms for measuring color of an extruded product prior to spooling and on-spool, respectively, is also not known in the art. Finally, employment of means for quickly checking the color measurement signal against a reference signal, and specifically use of an optical switch to accomplish that purpose, are also not known in the art.
Therefore, there is a need in the art for development of an on-line color monitoring and control system and method which measures the color of moving yarn or fiber (or filament of a yarn), or of a collection of fibers. Mechanisms for measurement of color both prior to spooling and on-spool are also needed. Finally, a means for quickly checking the color measurement signal against a reference signal, using an optical switch, is also needed.
The following patents are considered to be of background interest relative to the present invention, and are burdened by the disadvantages of prior art methods and arrangements, as discussed above: U.S. Pat. No. 5,526,285—Campo et al.; U.S. Pat. No. 5,468,586—Proper et al.; U.S. Pat. No. 5,387,381—Saloom; U.S. Pat. No. 5,282,141—Faas et al.; U.S. Pat. No. 5,092,168—Baker; U.S. Pat. No. 5,053,176—Cameron et al.; U.S. Pat. No. 4,788,650—Willis et al.; U.S. Pat. No. 4,761,129—Aste et al.; U.S. Pat. No. 4,745,555—Connelly et al.; U.S. Pat. No. 4,688,178—Connelly et al.; U.S. Pat. No. 3,388,261—Roberts et al.;
DISCLOSURE OF INVENTION
The present invention generally relates to an on-line color monitoring and control system and method, and more particularly to a system and method for measuring the color of a product produced by an extrusion device, determining whether the color falls within acceptable limits, and increasing or decreasing the level of the colorant provided to the extrusion device so as to adjust the color of the product.
As discussed in more detail below, the system of the present invention is utilized with an extrusion system. More importantly, the system of the present invention employs a color sensing arrangement which, in conjunction with an optical spectrum analyzer (OSA), provides a color sensor signal to a module (typically, a digital computer). The latter provides a serial data output to a programmable logic controller (PLC), which provides control signals to the feeder/mixer arrangement of the extrusion system for the purpose of adjusting the colorant level of the raw material provided to the extrusion device. Finally, in accordance with the invention, the PLC also provides an output to a network for the purpose of providing status information and the like.
It is to be further understood that, in accordance with the invention, a specially designed optical switch is provided for selecting between a reference signal and a measurement signal so as to provide a corresponding output to the OSA or spectrometer. In addition, in one embodiment, the inventive system employs a spring-loaded, twin-roller measuring arrangement for a light receiver so as to perform color measurement “on spool,” and to provide a light measurement signal to the OSA. In a further embodiment of the invention, a yarn guide is employed and color measurement is performed prior to spooling of the material in question. Finally, in accordance with the invention, the color monitoring and control system is software-controlled via a programmed element or PLC connected, via a serial data communications link, to a personal computer.
Therefore, it is a primary object of the present invention to provide an on-line color monitoring and control system and method.
It is an additional object of the present invention to provide a system and method for measuring the color of a product produced by an extrusion device.
It is an additional object of the present invention to provide a system and method which determine whether the color of an extruded product falls within acceptable limits.
It is an additional object of the present invention to provide a system and method which increases and decreases the level of colorant provided to an extrusion device so as to adjust the color of the extruded product.
It is an additional object of the present invention to provide a color monitoring and control system which employs a specially designed optical switch for selecting between a reference signal and a measurement signal.
It is an additional object of the present invention to provide a color monitoring and control system which, in one embodiment employs a spring-loaded, twin-roller measuring arrangement to provide “on spool” color measurement of a product.
It is an additional object of the present invention to provide a color monitoring and control system which, in another embodiment, employs a yarn guide to perform color measure
Evans F L
Prisma Fibers Inc.
Seeber Joseph G.
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