APPARATUS FOR INSPECTION OF WRAPPER

Abstract: The present invention relates to a quality control system for wrapping, and in particular a quality control system for wrapping roll-shaped objects which comprises one or more lighting elements (1) which is or are aimed towards the object (2) such that the light coming from the lighting element hits the surface of the object (2) at an angle, a monitoring device (3) to record the shadows which form on the surface of the object and to record the faults and/or irregularities in the wrapping, and a device for processing the data. A system formed in accordance with the invention uses a CCD linescan camera as a monitoring device (3), which is aimed horizontally to photograph the surface of the object (2) while it is in the process of being wrapped and as the object is being turned or spun in a horizontal circular direction.

Description: APPARATUS FOR INSPECTION OF WRAPPER The present invention relates to a system for quality control in wrapping and in particular a system for quality control in wrapping roll-shaped objects, which comprises one or more lighting elements which is or are directed towards the object in such a way that the light from the lighting element hits the surface of the object at an angle, a monitoring device to record the shadows in the wrapping formed on the surface of the object and to record the faults in the wrapping and/or irregularities, and a device for processing the data. Many objects, such as rolls produced in the paper and cardboard industry, are wrapped in a packing department or corresponding place set aside for wrapping before the rolls are transported into storage and further at some stage to the customer. When the wrapping is wrapped around the roll, sometimes wrinkles or other irregularities form in the wrapping which are caused by the wrapping set unevenly set on the surface of the roll. If there are wrinkles or other faults or irregularities in the wrapping, the risk of physical damage to the wrapping during transport increases. Additionally, wrinkles or other irregularities in the wrapping can accumulate water, dust and/or dirt during storage or transportation, which can damage the wrapping and also possibly the contents of the wrapping. Furthermore, said irregularly wrapped objects have a bad appearance. In packing departments, wrapping and the wrapping appearance is generally only visually monitored. If faults or irregularities in the packing are defected, the old wrapping is taken away and new wrapping is applied. The rolls and the wrapping of rolls and corresponding objectsare wrapped mechanically and automatically so the effective detection of wrinkles and other irregularities is difficult in the packing department. There is quality control equipment available, but it cannot be used simultaneously in conjunction with the wrapping mechanism, but rather afterwards. The aim of the invention is to provide a control system for the wrapping of objects, by which data concerning irregularities and/or faults in the wrapping can be obtained immediately during the wrapping process, taken into consideration and the problems corrected. Additionally, the aim of the invention is to provide a control system for the wrapping process which is simple in its structure and functions sefely and reliably. The object of the invention is accomplished with a system, the characteristics of which are set forth in the patent claims. A system formed in accordance with the invention uses a CCD linescan camera as a monitoring device, which is adjusted horizontally to photograph the surface of the object during the wrapping process, as the object is moving horizontally in a circular motion. The target of the photograph is, in other words, the curved surface (side of the roll) which moves spinning horizontally. A spotlight illuminates all of the wrinkles, faults and/or other irregularities in the wrapping. These faults and/or other irregularities become extremely conspicuous in the spotlight which causes them to appear as dark shadows. With a functioning CCD linescan camera as a monitoring device, the illuminated surface in question can be observed and monitored. The monitoring is carried out as different areas at certain heights and of certain widths are photographed. The data from the CCD linescan camera is transmitted in a manner known perse to a conventional computer in which the different filmed areas are joined to one another, forming a continuous picture of the wrapping. The computer processes the information, for example, by analyzing the contrast differences which are darker (shadows) or brighter (reflections) areas compared to the base shade. This is achieved by aiming the lights at an angle to the photographed target area. The end result is that the control system provides data about irregularities in the wrapping on the entire surface area of the object. The data is transmitted for analysis in the desired way and is taken into consideration in handling the object in question in the event that the set criteria for quality or control are not being met. With a system formed in accordance with the invention, data can be automatically and reliably obtained about the quality of the wrapping of the object immediately during the wrapping process and defects in the wrapping quality can be addressed immediately in quality control. The advantage in using a CCD linescan camera is that the photographed area is linear, in other words, the photographed area is vertically well limited so that there are no problems when installing other equipment. For example, the picture taken consists of a photographed area approximately 3 mm in height and as wide as the object, but other heights may also be used in different applications. When using a CCD linescan camera, the picture is not vertically and/or horizontally distorted, even though it is the wrapping surface, a moving surface, which is being photographed. The picture is taken with one camera from the front, in other words, the picture is two-dimensional . In an a preferable embodiment of the invention, the lighting element or elements are placed horizontally in relation to the surface of the object being monitored. When the lighting element or elements are placed in this way, the necessary qualities of the wrapping become clearly visible as shadows. In a preferable additional embodiment of the invention, the lighting element or elements are placed vertically in relation to the surface of the object being monitored. A lighting element or lighting elements placed in this way also makes it easy to see shadows indicating irregularities in the wrapping. A system formed in accordance with the invention comprises, in a preferable method of application, several lighting elements located at a distance from the object. In this context, the term "lighting elements" refers to different electric lamps or corresponding element or light-transmitting elements from one or more light sources, such as optical fibers or corresponding elements. The number of lighting elements depends on the area of the surface to be illuminated, on the distance to the wrapping and on the amount of luminosity required. Thus, the number of lighting elements may vary in different applications of the invention, according to purpose. Additionally, the system' s lighting elements are placed appropriately so that the beams of light from the lighting elements are aimed to shine at least partially overlapping one another on the surface of the object, so that a uniformly illuminated area is formed on the surface of the object. When the light beams are aimed to partially overlap one another, it creates a brightly lit surface on the wrapping and shadows become clearly visible. It is also possible to use one uniform wedge of light which can be produced in a prior known way by using a light lens system or a light source located farther away from the wrapping. The invention will now be described in more detail with reference to the accompanying drawing in which Figure 1 illustrates a certain application of a quality control system formed in accordance with the invention, diagrammatically presented as seen from the side. Figure 2 illustrates a system formed in accordance with Figure 1 as viewed from the camera (photo of the front of the wrapping) , and Figure 3 illustrates a close-up view of three lighting components and the figures formed by their light on the surface of the wrapping. A quality control system for wrapping formed in accordance with the figures comprises several lighting elements 1 and a monitoring device 3 located at a distance away from the lighting elements. In this application, the lighting elements are placed evenly distanced from one another on a supporting element 4. In this system a lighting system based on optical fibers is used, which is composed of separately adjustable lighting components and projectors which function as light sources for the fiber light. The number and implementation of the components may vary in different applications. Also other types of lighting systems may be used in other applications. The supporting element 4 for the lighting elements is a long beam or corresponding object, which is placed at a distance from the surface of the roll 2 at an angle to the lower part of the roll. An advantageous placing for the spotlight is as close as possible to the location where the differences in the distance between the wrapping and the lighting will be the smallest possible. However other placings are also possible. Lighting elements or lighting components 1 are set adjustably and so that they can be turned onto the supporting element, but in such a way that the light beams are aimed in the same direction so that shadows etc. will become visible. Lighting elements 1 formed in accordance with Figure 2 are placed so that their light shines horizontally and vertically diagonally at an angle to the surface of the object being monitored 2. They are oriented in a way that they do not bring about reflections or shadows on the wrapping of the surrounding material. The variations in distance between the wrapping and lighting are taken into consideration when adjusting the lighting and the surface area to be illuminated and the system is regulated. As presented in Figure 1, the roll-shaped object 2 is placed on the supporting cylinders 8 and the object 2 is being wrapped in wrapping as it is turned or spun around with the help of the supporting cylinders. The outer circle represents the largest possible roll and wrapping and the inner circle represents the smallest possible roll and wrapping. Lighting elements formed in accordance with Figure 3 are placed such that light beams are oriented to shine at least partially one on top of the other and to overlap on the surface of the object. In this way, a continuous horizontal illuminated area is formed on the surface of the object. Since the light beams come from the side and the wrapping surface is not a two-dimensional plane, the light beams are oval-shaped. The light beams overlap one another such that the edges of the first 5 and third 6 light beams illuminate the same spot which is the central point for the second 7 or center light beam. In this application, all of the light beams overlap one another halfway. The monitoring device 3 is a CCD linescan camera. The camera is placed according to Figure 1 perpendicularly in relation to the illustrated roll and at such a distance from the roll that the lit areas on the surface of the roll can be effectively seen. The camera vertically and in a piecemeal way photographs areas which are illuminated horizontally by the lighting system along the entire wrapping area. The wrapping is photographed in either black and white or color. The camera continually photographs the wrapping at certain intervals as the roll is being turned at the wrapping station, or immediately thereafter. With a picture capturing card, the photographed data from the CCD linescan camera is transferred to a computer. An examination for wrinkles or other faults is done on the entire surface of the photo. Software for wrapping quality control processes the data from the photographed wrapping by analyzing contrasts and color differences. Wrinkles and other faults are detected by studying the local shade contrasts of the picture. Data from the photo is defined in terms of the surface, width, height, quantity and location of the wrinkles. As the final result, the quality control software yields data about observed differences in the wrapping over the entire wrapped surface area. The data obtained from the control system can be processed automatically by incorporating it as a part of the other activities of the packing department or according to the criteria for control set by the operator. The invention is not limited to the advantageous application set forth in this patent application. The invention is versatile and its form may vary within the frames of the idea of the invention put forth in the claims .

Claims: CLAIMS 1. A quality control system for wrapping, and in particular a quality control system for wrapping of roll- shaped objects which comprises one or more lighting elements (1) which is or are aimed towards the object (2) such that the light coming from the lighting element hits the surface of the object (2) at an angle, a monitoring device (3) to record the shadows which form on the surface of the object and to record faults and/or irregularities in the wrapping, and a device for processing the data, c h a r a c t e r i z e d in that the monitoring device (3) is a CCD linescan camera which is aimed horizontally to photograph the surface of the object (2) while it is in the process of being wrapped and as the object is being turned or spun in a horizontal circular direction. 2. A system formed in accordance with claim 1, c h a- r a c t e r i z e d in that the lighting element (1) or lighting elements are arranged horizontally at an angle relative to the surface of the object (2) being monitored. 3. A system formed in accordance with claim 1 or claim 2, c h a r a c t e r i z e d in that the lighting element (1) or elements are arranged vertically at an angle relative to the surface of the object (2) being monitored. 4. A system formed in accordance with any of the claims 1-3 c h a r a c t e r i z e d in that the system comprises several lighting elements (1) located at a distance from the object (2) . 5. A system formed in accordance with claim 4, c h a- r a c t e r i z e d in that the lighting elements (1) are placed such that the light beams coming from them are oriented to shine at least partially overlapping one another on the surface of the object (2) so that they form a continuous lighted area on the surface of the object.

Inventors: LAINE MIKA, SAARINEN KARI, LAINE, MIKA, SAARINEN, KARI
Applicants: LAINE MIKA, SAARINEN KARI, VISY OY, LAINE, MIKA, SAARINEN, KARI
Application year: 1999
Main classification: G01N21
IPC codes: G01N21