Abstract:
According to an aspect of the present disclosure, a color sensor is provided for sensing whether a ground roller in a corona treatment system needs to be serviced. The color sensor is capable of detecting imperfections which have changed the reflectance level of the ground roller from a predefined level. According to another aspect of the present disclosure, if a determination is made that the ground roller needs to be serviced, then an alarm is activated and/or the operation of the corona treatment system is ceased.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to corona treatment of a web. More particularly, it relates to a color sensor capable of detecting imperfections on a ground roller used in a corona treatment system, to indicate that the ground roller needs to be serviced. 
       BACKGROUND 
       [0002]    Corona treatment is a method using an electrical corona discharge to modify a surface of a web to improve its ability to accept inks and adhesives. In a corona treatment, a high voltage electrode is mounted parallel to and spaced from a ground roller, which forms a grounded electrode. The air gap between the electrodes is energized, forming a corona, which, when web is passed therethrough modifies the material the web is formed of, and makes the web more receptive to ink and adhesives. Corona will be produced anywhere there is air within this air gap. 
         [0003]    The occurrence known as “backside treat” is the result of a corona being produced on both sides of a web being treated, even though the corona treatment system is only intended to treat one side of the web. The resulting undesired treatment on the backside of the web may result in blocking and picking. The resulting undesired treatment on the backside of the web may also cause an insufficient treat level on the side of the web requiring treatment, since some the power intended for treating the web was delivered to the opposite side, thus, reducing the watt density provided to the side to be treated. 
         [0004]    There are a number of causes for backside treat, all of which are the result of air being entrapped under the web being treated. One of the most common causes for backside treat is dirt buildup on the corona ground roll. Regardless if the corona treatment system is a bare roll or a covered roll, dirt buildup gets deposited on the surface of the ground roller. These uneven deposits of dirt buildup lift the web off the surface of the ground roller, entrapping air underneath the web. To eliminate backside treat caused by dirt buildup, the ground roller must be cleaned. 
       SUMMARY 
       [0005]    In one aspect, a color sensor capable of detecting whether a ground roller used in a corona treatment system needs to be serviced is provided. The color sensor is capable of detecting imperfections which have changed the reflectance level of the ground roller from a predefined level. 
         [0006]    In another aspect, if a determination is made that the ground roller needs to be serviced, then an alarm is activated and/or the operation of the corona treatment system is ceased. 
         [0007]    The scope of the present invention is defined solely by the appended claims and is not affected by the statements within this summary. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
           [0009]      FIG. 1  depicts a perspective view of a corona treatment system which incorporates features of the present disclosure; 
           [0010]      FIG. 2  depicts an alternate perspective view of a portion of the corona treatment system, with curtains removed to show features of the present system; 
           [0011]      FIG. 3  depicts a side elevation view of the corona treatment system; 
           [0012]      FIG. 4  depicts a cross-sectional view of the corona treatment system along line  4 - 4  of  FIG. 1 ; 
           [0013]      FIG. 5  depicts an enlarged partial view of the corona treatment system; 
           [0014]      FIG. 6  depicts a cross-sectional view of the corona treatment system along line  6 - 6  of  FIG. 3 ; 
           [0015]      FIG. 7  depicts a cross-sectional view of the corona treatment system along line  7 - 7  of  FIG. 3 ; and 
           [0016]      FIG. 8  depicts a block view of a control system. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    While the invention may be susceptible to embodiment in different forms, there is shown in the drawings, and herein will be described in detail, specific embodiments with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that as illustrated and described herein. Therefore, unless otherwise noted, features disclosed herein may be combined together to form additional combinations that were not otherwise shown for purposes of brevity. 
         [0018]    The drawings illustrates a corona treatment system  20  which incorporates features of the present disclosure. The corona treatment system  20  may be adapted to be used in conjunction with a printing press (not shown). The corona treatment system  20  includes a cylindrical ground roller  22 , a high voltage electrode  24 , and a color sensor  26  for sensing imperfections on the surface  22   a  of the ground roller  22 . Imperfections as defined herein are items on the ground roller  22  which change the reflectance level of the ground roller  22  from a predefined level. For example, imperfections can be caused by debris on the ground roller  22 , water on the ground roller  22 , oxidation on the ground roller  22 , pitting on the ground roller  22 . The corona treatment system  20  is used to modify a surface of a flexible web (not shown) to improve its ability to accept inks and adhesives. The web is passed between the ground roller  22  and the electrode  24  during which the material of web is treated to modify the material. Examples of webs that may be treated by the corona treatment system  20  include, but are not limited to, paper, polymer films, elastomers, plastics, foams, etc. 
         [0019]    In general, the corona treatment system  20  includes a power supply cabinet  30  with a control panel  32  from which depends a first end plate  34  and, in parallel relationship thereto, a second end plate  36 , the ground roller  22  rotatably mounted between the plates  34 ,  36 , the color sensor  26  in proximity to the ground roller  22 , an electrode support tube  38  mounted between the plates  34 ,  36 , an electrode magazine  40  mounted on the electrode support tube  38  and supporting the high voltage electrode  24  in spaced relationship from the ground roller  22 , a plurality of idler rollers  42  rotatably mounted between the plates  34 ,  36  and spaced from the ground roller  22 , and an apparatus  400  provided within the cabinet  30  which communicates with the color sensor  26  and controls a display and/or light  46  on the cabinet  30 . Tie bars  48  may be provided between the end plates  34 ,  36 . The color sensor  26  is in proximity to the ground roller  22  so that the color sensor  26  can sense the reflectance levels of the ground roller  22 . The color sensor  26  may be mounted on one of the end plates; as shown, the color sensor  26  is mounted on end plate  34 ; the color sensor  26  may be mounted on the ground. 
         [0020]    The electrode support tube  38  and electrode magazine  40  mounted thereon may be pivotally connected to the end plates  34 ,  36  as is known in the art. Alternatively, the electrode magazine  40  may be slidably mounted on the electrode support tube  38  as is known in the art. This allows the electrode magazine  40  to be moved between an inoperative or maintenance position, and an operative or web treating position. The electrode support tube  38  is hollow and has an open end  50 . The electrode support tube  38  has a plurality of apertures  52  therethrough which face the ground roller  22 . Venting of ozone generated during the corona treatment and cooling for the electrode  24  is provided by the path formed by the apertures  52 , the electrode support tube  38  and its open end  50  in a known manner. 
         [0021]    The electrode magazine  40  has a pair of shields  54 ,  56  which are connected to the electrode support tube  38 , and support tubes  58  for supporting the electrode  24  between the shields  54 ,  56 . As such, the shields  54 ,  56  aid in guiding the ozone to be vented through the electrode support tube  38 . 
         [0022]    The electrode  24  may be a plurality of parallel electrodes; the electrode  24  may be a ceramic electrode, a FIN electrode, a segmented electrode, as is known in the art. 
         [0023]    The ground roller  22  is mounted for a rotation on a shaft  60  between the end plates  34 ,  36  and is positioned beneath the support tube  22  and beneath the electrode  24 . The electrode  24  may span the length of the ground roller  22 . The ground roller  22  and the electrode  24  may be spaced 1.5 mm away from each other to form an air gap  62 , see  FIGS. 5 and 6 . Ground rollers used in corona treatment systems are known in the art. The ground roller  22  may have a surface  22   a  formed of steel, ceramic, rubber, etc. The ground roller  22  may be formed of a self-supporting tube of a rigid dielectric material, such as a glass fiber reinforced epoxy or a glass fiber reinforced polymeric polyester. A conductive layer may be bonded to an inner wall of the ground roller  22 . The conductive layer is a relatively thin conductive metallic film or a coating containing a conductor, such as graphite. The conductive layer is relatively thin and does not have to be self-supporting because it is supported by the inner wall of the roller. 
         [0024]    The idler rollers  42  are mounted for rotation on respective shafts  64  between the end plates  34 ,  36 , and lie in space relationship below the ground roller  22 . 
         [0025]    The power supply cabinet  30  includes a power supply and a high voltage transformer provided with a high voltage wire. The wire terminates in a high voltage connection normally enclosed by a high voltage cover plate located behind the end plate  34 . The high voltage connection establishes a high voltage field between the ground roller  22  and the electrode  24  with the web to be treated interposed between the electrode  24  and the ground roller  22 . As is well known, the high voltage field establishes a corona discharge that causes the chemical composition of the material of the web to be modified which, in turn, improves selected characteristics of the material of the web such as wettability so that printed matter or coating may be more advantageously adhered thereto. 
         [0026]    In use, the web is guided upwardly by the idler rollers  42  and wound about the ground roller  22  in spaced relationship from the electrode  24 . The web does not span the entire length of the ground roller  22  such that there is a portion  66  exposed at at least one end of the ground roller  22 . The electrode  24  spans this portion  66  such that the surface  22   a  of this portion  66  of the ground roller  22  is subjected to the high voltage from the electrode  24 . The ground roller  22  supports the web which is treated as it passes through the air gap  62  between the ground roller  22  and the electrode  24  in a direction transverse to the longitudinal direction of the electrode  24 . The air gap  62  between the two electrodes  22 ,  24  is normally about 1.5 mm wide and a corona discharge develops in the air gap  62  when the electrode  24  is energized by the power supply to create a high voltage. The surface of the web passing through the air gap  62  is modified by the exposure to the corona so that its printing properties are improved. However, the high frequency voltage generated by the electrode  24  is also applied to the ground roller  22 . This causes the ground roller  22  to be heated which causes imperfections, such as oxidation and pitting, on the surface  22   a  of the ground roller  22 . These imperfections will be present on the portion  66  of the ground roller  22  and are detected by the color sensor  24 . 
         [0027]    The color sensor  26  has a specific reflectance monitoring capacity and is mounted at a defined distance D from the ground roller  22 . The color sensor  26  is resistant to dust, water, debris, heat and ozone; such a sensor is commonly designated as a IP64 sensor. The color sensor  26  may be mounted in a variety of positions relative to the circumference of the ground roller  22  as shown in  FIG. 6 . As shown in  FIG. 6 , the color sensor  26  (shown in full line) may mounted so as to be generally diametrically opposed to the electrode  24 . The color sensor  26  is spaced a minimum at an angle α which is 45 degrees away from the electrode  24  as shown in  FIG. 6 . A variety of mounting positions for the color sensor  26  are shown in  FIG. 6 , but the sensor  26  can be mounted at any position around the circumference of the ground roller  22  through the arc shown by arrow β. 
         [0028]    The color sensor  26  illuminates the portion  66  of the surface of the ground roller  22  with white light and captures and analyzes the reflected color values. The color sensor  26  is pre-programmed to recognize a base reflectance state at the ground roller  22  which represents a “clean” appearance of the ground roller  22 , that is a state where there are no imperfections on the ground roller  22 . The color sensor  26  is pre-programmed to recognize an “unacceptable reflectance state” at the ground roller  22  representing a threshold contaminated appearance of the ground roller  22 , that is, when there are imperfections on the ground roller  22 . Since the imperfections will be present on the portion  66  of the ground roller  22 , once the portion  66  of the ground roller  22  proximate to the color sensor  26  reaches the unacceptable reflectance state, a signal is sent from the color sensor  26  to the apparatus  400  to activate an alarm  401  and/or to cease operation of the corona treatment system  20 . An example of a suitable color sensor  26  is sold under the tradename colorSENSOR 26 OT-3-MA sold by MICRO-EPSILON MESSTECHNIK GmbH &amp; Co. KG. 
         [0029]    The color sensor  26  is positioned such that the color sensor  26  directs its light beam onto the portion  66  of the ground roller  22  that is not covered by the web during the corona treatment of the web. As shown, the color sensor  26  is positioned proximate to an end of the ground roller  22 . 
         [0030]    The color sensor  26  may be mounted on an arm  68  extending from the end plate  34 . The arm  68  of the color sensor  26  is moveable relative to the end plate  34  so that the color sensor  26  can be moved toward or away from the ground roller  22  a predetermined distance, for example, the color sensor  26  may be positioned 2 to 5 inches away from the ground roller  22  to provide a sensing diameter of 0.5 inches to 2 inches on the ground roller  22 ; the sensing diameter is dependent upon the diameter of the ground roller  22 . The arm  68  can be moved, thus moving the color sensor  26 , and then fixed into a new position relative to the end plate  34 . The color sensor  26  may be moved to accommodate differently sized ground rollers and to minimize any shadowing. 
         [0031]    As shown, the arm  68  has a first portion  70  which abuts against the end plate  34 , and a second portion  72  which is perpendicular to the first portion  70 . As shown in  FIG. 7 , the first portion  70  has a slot  74  through which a fastener  76  is seated. The fastener  76  is threaded into an aperture in the end plate  34 . The color sensor  26  is attached to the free end of the second arm  68 . To change the position of the color sensor  26  relative to the ground roller  22 , the fastener  76  is loosened so that the arm  68  can be moved relative to the end plate  34 . This allows the fastener  76  to translate within the slot  74 , thereby allowing the arm  68  and color sensor  26  to move to a new position. Once the color sensor  26  is positioned in a desired new position, the fastener  76  is secured to prevent further relative movement between the arm  68 /color sensor  26  and the end plate  34 . The slot  74  could instead be provided on the end plate  34 , with the aperture in the arm  68 . It is to be understood that this structure for allowing relative movement between the color sensor  26  and end plate  34  is illustrative only and that many structures may be provided for allowing the relative movement between the color sensor  26  and end plate  34  which would be known to one of ordinary skill in the art. 
         [0032]    As discussed, the color sensor  26  is used to sense a specific level of reflectance at the ground roller  22  and this information is supplied to the apparatus  400  which alerts an operator by an alarm  401 , and/or is used by the apparatus  400  to cease the operation of the corona treatment system  20 . The alarm  401  may take the form of an audible signal, a light, a combination of an audible signal and light, etc. The triggering of the alarm  401  may also be used by the apparatus  400  to cease operation of the corona treatment system  20 . Once the operator is notified, the operator will then know that the ground roller  22  needs to be serviced. 
         [0033]    Other sensors, such as a sensor (not shown) that detects air flow and a sensor (not shown) that detects the speed of the ground roller  22 , may be provided in the corona treatment system  20 . 
         [0034]      FIG. 8  illustrates a block diagram of an apparatus  400  that may be implemented on the corona treatment system  20 , in accordance with some example embodiments. In this regard, when implemented on a corona treatment system  20 , apparatus  400  may enable the corona treatment system  20  to analyze information from the color sensor  26  to activate the alarm  401  and/or cease operation of the corona treatment system  20  in accordance with one or more example embodiments. It will be appreciated that the components, devices or elements illustrated in and described with respect to  FIG. 8  below may not be mandatory and thus some may be omitted in certain embodiments. Additionally, some embodiments may include further or different components, devices or elements beyond those illustrated in and described with respect to  FIG. 8 . 
         [0035]    In some example embodiments, the apparatus  400  may include processing circuitry  410  that is configurable to perform actions in accordance with one or more example embodiments disclosed herein. In this regard, the processing circuitry  410  may be configured to perform and/or control performance of one or more functionalities of the corona treatment system  20 , such as actuating the roller  22  and the electrode  24 , activating the color sensor  26  and analyzing the information from the color sensor  26  to activate the alarm  401  and/or cease operation of the corona treatment system  20  in accordance with various example embodiments. The processing circuitry  410  may be configured to perform data processing, application execution and/or other processing and management services according to one or more example embodiments. 
         [0036]    In some embodiments, the apparatus  400  or a portion(s) or component(s) thereof, such as the processing circuitry  410 , may include one or more chipsets and/or other components that may be provided by integrated circuits. 
         [0037]    In some example embodiments, the processing circuitry  410  may include a processor  412  and, in some embodiments, such as that illustrated in  FIG. 8 , may further include memory  414 . The processing circuitry  410  may be in communication with or otherwise control a wireless communication interface  416  in communication with the color sensor  26  (the color sensor  26  may be hard wired to the processing circuitry  410  and/or control module  418 . 
         [0038]    The processor  412  may be embodied in a variety of forms. For example, the processor  412  may be embodied as various hardware-based processing means such as a microprocessor, a coprocessor, a controller or various other computing or processing devices including integrated circuits such as, for example, an ASIC (application specific integrated circuit), an FPGA (field programmable gate array), some combination thereof, or the like. Although illustrated as a single processor, it will be appreciated that the processor  412  may comprise a plurality of processors. The plurality of processors may be in operative communication with each other and may be collectively configured to perform one or more functionalities of the apparatus  400  as described herein. In some example embodiments, the processor  412  may be configured to execute instructions that may be stored in the memory  414  or that may be otherwise accessible to the processor  412 . As such, whether configured by hardware or by a combination of hardware and software, the processor  412  capable of performing operations according to various embodiments while configured accordingly. 
         [0039]    In some example embodiments, the memory  414  may include one or more memory devices. Memory  414  may include fixed and/or removable memory devices. In some embodiments, the memory  414  may provide a non-transitory computer-readable storage medium that may store computer program instructions that may be executed by the processor  412 . In this regard, the memory  414  may be configured to store information, data, applications, instructions and/or the like for enabling the apparatus  400  to carry out various functions in accordance with one or more example embodiments. In some embodiments, the memory  414  may be in communication with one or more of the processor  412  and transmission power control module  418  via one or more buses for passing information among components of the apparatus  400 . 
         [0040]    The apparatus  400  may further include circuitry, hardware, a computer program product comprising a computer readable medium (for example, the memory  414 ) storing computer readable program instructions that are executable by a processing device (for example, the processor  412 ), or some combination thereof. In some embodiments, the processor  412  (or the processing circuitry  410 ) may include, or otherwise control the transmission power control module  418 . 
         [0041]    The Abstract is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter. 
         [0042]    While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that other embodiments and implementations are possible within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.