Abstract:
A method and the device for acquiring and processing measurement quantities in a sewing machine ( 1 ) using at least one camera ( 25 ), situated on a sewing machine ( 1 ), for the acquisition and processing of image data for sewing machine elements and sewing elements. An image processing unit connected downstream from the camera ( 25 ) processes the images supplied by the camera ( 25 ), taking into account data stored in a target quantity memory, and influences the behavior of the machine control unit dependent on the result of the processing.

Description:
BACKGROUND  
       [0001]     The subject matter of the present invention is a device and a method for acquiring and processing measurement quantities in a sewing machine.  
         [0002]     It is known that in sewing machines a camera can be provided that monitors the article being sewn during the sewing process. In this way, differences in quality that may be caused by different transport characteristics of different types of sewn articles can be acquired.  
         [0003]     As is disclosed for example in DE 19850742, the camera can be used to determine the position of two adjacent stitch points of the sewing needle on the article being sewn. A comparator device determines deviations of the actual values from stored target values for the position of these stitch points, and influences the advance of the material in such a way that subsequent stitch points deviate as little as possible from the desired target positions.  
         [0004]     Although the characteristics of the article being sewn, which can vary greatly, in interaction with the device for transporting the article being sewn are not the only factors responsible for the problem-free functioning of a sewing machine, up until now a camera has been used only to monitor the article being sewn.  
       SUMMARY  
       [0005]     Therefore, the object of the present invention is to create a device and a method for using a camera to acquire and process measurement quantities in a sewing machine that ensure problem-free operation of the sewing machine.  
         [0006]     This objective is achieved by a device and a method for acquiring and processing measurement quantities in a sewing machine. With the method according to the present invention and the device according to the present invention, sewing machine elements and their disposition on the sewing machine can be monitored. Thus, for example, items of information concerning the type of particular sewing machine elements and their correct disposition on the sewing machine can be acquired. The acquisition and evaluation take place using one or more cameras connected to an image processing unit. According to the position of the camera, or of an imaging optical system allocated to the camera, imaging information on sewing machine elements can be acquired from the inside of the lower arm (e.g., spool, spool capsule, or throat plate) or from above the throat plate (e.g., sewing needle, sewing foot, throat plate, hoop). The cameras and/or the imaging optical systems, or parts thereof, can be situated so as to be capable of movement. They can for example be mounted so as to be capable of pivoting about one or more pivot axes, and/or so as to be capable of movement along an axis of translation. Changes of position can be brought about for example using step motors or other drive means that can be controlled by the sewing machine control unit. The image information is evaluated by an image processing unit. The image processing unit can use features, or comparison or target quantities, that are stored in a target quantity memory. In a preferred construction of the present invention, the image processing unit can in addition also store information or target quantities in the target quantity memory. Such target quantities can for example include color or character codes, or information concerning shape, contour, structure, or position of a sewing machine element.  
         [0007]     The image processing unit can be functionally connected with the sewing machine control unit or can be a component thereof. The image processing unit can check for the presence and/or the correct mounting of one or more sewing machine elements and/or their spatial position on the sewing machine. Various functions of the sewing machine control unit that use the information from the image processing unit can contribute to the automation, simplification, or improvement of operating, monitoring, and control tasks, the issuance of warnings when errors occur or the execution of certain subsequent operations, the prevention of accidents, or the ensuring or improvement of the quality of the sewing process.  
         [0008]     In addition to the acquisition and evaluation of information concerning sewing machine elements that are components or accessories of the sewing machine, the image processing unit can also be fashioned for the acquisition and evaluation of information concerning sewing elements. The category of sewing elements includes the article being sewn and the threads used for the processing of the article being sewn before and after the processing. The information concerning sewing elements can also be used by the sewing machine control unit in particular for the controlling or regulation of sewing processes, for example for influencing the longitudinal and/or transverse movement of a material transport device.  
         [0009]     The camera can also be used to determine criteria of comparison for the target quantity memory. Alternatively, or in addition, such features or target quantities can also be read into the target quantity memory via an interface. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The present invention is explained in more detail in the following with reference to the drawing Figures.  
         [0011]      FIG. 1  shows a sewing machine in a side view;  
         [0012]      FIG. 1A  is a detail view taken from  FIG. 1  in the indicated area A in the area of the shuttle in an enlarged, partially exploded view;  
         [0013]      FIG. 2  shows a schematic diagram of a part of a sewing machine having an acquisition device;  
         [0014]      FIG. 3   a  is a view of a first throat plate;  
         [0015]      FIG. 3   b  is a view of a second throat plate;  
         [0016]      FIGS. 4   a - 4   d  are views of four different types of sewing feet;  
         [0017]      FIG. 5   a  shows a side view of a sewing machine with a correctly fastened sewing foot;  
         [0018]      FIG. 5   b  shows a side view of a sewing machine with an incompletely fastened sewing foot;  
         [0019]      FIG. 5   c  shows a side view of a sewing machine in which the sewing foot lies flat;  
         [0020]      FIG. 5   d  shows a side view of a sewing machine in which the sewing foot lies obliquely;  
         [0021]      FIGS. 6   a - 6   i  are views of nine different sewing needle types. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]      FIGS. 1 and 1 A schematically show a sewing machine  1  having a base  3 , a pedestal  5  that is fastened to and supported on base  3 , and a free or lower arm  7  fastened thereto, as well as upper arm  9 . A display unit  10 , or a display screen and operating elements  12 , are situated laterally on the upper arm  9 . The front end of upper arm  9  is formed as a sewing machine head  11 . On the lower side of sewing machine head  11 , extends a needle bar  13  having a needle holder  15 , a sewing needle or needle  17  placed in needle holder  15 , a sewing foot holder  19  having a sewing foot  21  placed therein, and a threading device  23 . Two cameras  25 , represented by broken lines, are integrated into the sewing machine head  11 , or in an additional module  27  that is fastened laterally thereon and that can be removed, in such a way that they can acquire one or more of the sewing machine elements or parts thereof that are visible between the sewing machine head  11  and the lower arm  7 . An additional camera  25 , likewise represented by broken lines, is situated in the front area of the lower arm  7  in such a way that it can acquire sewing machine elements or parts thereof that are visible there. Alternatively, cameras  25  can also be situated in other areas of the sewing machine  1 , for example in the area of the pedestal  5  or of the upper arm  9 . In addition, optical elements, such as for example light waveguides  29 , lenses  31 , or mirrors for the formation of an acquisition area, can be placed on the camera  25 . In this way, even unfavorably situated areas of acquisition can be imaged using a camera  25 . Cameras  25  can thus be situated on the sewing machine  1  where there is available space for them, largely independent of their areas of acquisition. In this way, even sewing machine elements that are difficult to access can be acquired. In the simplest embodiment of the present invention, one camera  25  is sufficient. A plurality of cameras  25  can however also work together in such a way that objects such as sewing machine elements or sewing elements can be acquired from a variety of directions.  
         [0023]     The designation “sewing machine elements” includes components and accessory parts that are situated fixedly on the sewing machine  1  as well as parts and accessories that can be detached from the sewing machine; for example, the needle bar  13 , the needle holder  15 , the needle  17 , the sewing foot holder  19 , the sewing foot  21 , the threading device  23 , a throat plate  33 , a hook  35 , a bobbin case  37  placed in the hook  35 , or a bobbin  39  placed in the bobbin case  37  that is empty or is partially or completely equipped with thread. For better visibility of the sewing machine elements, in  FIG. 1 a  cover  41 , situated on the front side of the lower arm  7 , is opened. Additional possible sewing machine elements include detachable work supports, straightedges, additional apparatuses, or hoops (not shown).  
         [0024]      FIG. 2  shows a schematic diagram of the design of the device for acquiring measurement quantities. The cameras  25  can for example comprise black-and-white or color CCD or CMOS image sensors having a one-or two-dimensional array of light-sensitive pixels. They are connected to an image processing unit  43  that processes the image information acquired by the cameras  25 . Alternatively, a separate image processing unit  43  can be allocated to each of the cameras  25 . This image processing unit can for example be completely or partially integrated on the same chip as the camera  25 .  
         [0025]     The image processing unit  43  is functionally connected to a target quantity memory  45 , for example in a non-volatile flash memory. In addition, there is a functional connection between the image processing unit  43  and the sewing machine control unit (called machine control unit  47  for short). Of course, the image processing unit  43  can also be integrated completely or partially into the machine control unit  47 . The machine control unit  47  comprises a plurality of interfaces, for example to operating elements  12 , to the display unit  10 , to an acoustic signal transducer  49 , and to main drive  51 , which, depending on the design of the sewing machine  1 , is used for example to drive the needle bar  13  and the hook  35 .  
         [0026]     In  FIGS. 3   a  and  3   b,  two different throat plates  33  are shown having stamped-in length scales and pass-through slots  53  for a clutch feed  34  ( FIG. 5   c  and  5   d ). The two throat plates  33  differ in the size or length of a needle pass-through opening  55  and/or of a code  57  that is printed or stamped on the upper side and/or the underside of the throat plate  33 . The code  57  can for example be fashioned as a bar code, as a number, or as a color code, and is uniquely assigned to a particular type of throat plate.  
         [0027]     In  FIGS. 4   a - 4   d,  four different types of sewing feet are shown. They differ not only in their shape or design, but also by a visibly printed or stamped code  57  in the form of a number. The code “ 1 ” characterizes a back-transport foot for useful and decorative stitching, code “ 2 ” designates an overlock foot, code “ 9 ” designates a darning foot, and code “ 37 ” designates a patchwork foot.  
         [0028]     Sewing machine elements need not necessarily be characterized with a code, if a unique identification is also possible on the basis of other features.  
         [0029]     In  FIGS. 5   a  and  5   b,  the fastening of a sewing foot  21  to the sewing foot holder  19  is shown schematically. Here, a cup-type recess  59  on the upper side of the sewing foot  21  is pushed from below over a peg  61  that protrudes downward on the sewing foot holder  19 . Subsequently, the sewing foot  21  is clamped fast on the sewing foot holder  19  using a knee lever  63 . If the sewing foot  21  is not seated properly on the sewing foot holder  19 , this can be recognized for example by a lowered and/or oblique position of the sewing foot  21 , or by a changed pivot position of the knee lever  63  in comparison with a position it should have when the sewing foot  21  is correctly fastened.  
         [0030]      FIGS. 5   c  and  5   d  show the different positions of the sewing foot  21 , or of a sewing foot sole  22  coupled to the sewing foot  21  at the bottom, for the case of a flat seating on clutch feed  34  ( FIG. 5   c ) and during the crossing of a seam  65  of an article  67  that is being sewn.  
         [0031]      FIGS. 6   a - 6   i  show a plurality of different types of sewing needles. They comprise differing features, such as for example needle diameter d, type of point (cutting point, rounding diameter of a ball point), number of needles  17  in the case of multiple needles, distances s between individual needles  17  of such a group, shape of the needles (e.g., round needles, sword-shaped needles). Needles  17  shown in  FIG. 6   a - 6   i  are, respectively: a sword-shaped needle  17   a,  a drilling needle  17   b,  a double needle  17   c,  a needle  17   d  having a cutting point, a needle  17   e  having a fine point, two needles  17   f  and  17   g  having medium ball points, a needle  17   h  having a fine ball point, and a universal needle  17   i  having a slightly rounded point.  
         [0032]     In the target quantity memory  45  there may be stored, in suitable form, target quantities and/or comparative values and/or criteria for comparing measurement quantities that are acquired by the cameras  25  and prepared by the image processing unit  43 .  
         [0033]     One or more of the cameras  25  can be situated such that, in addition to at least one sewing machine element, they can also acquire sewing elements or parts thereof before, during, or after the processing by the sewing machine  1 . The term “sewing elements” includes for example the article being sewn  67 , threads such as the upper thread and the bobbin thread, a hem, seam, or stitching pattern on the article being sewn  67 , a pattern for a hem or a stitching pattern, or the like. Partial areas of such sewing elements are also designated as sewing elements. Sewing elements can thus be brought into the stitch formation area between the lower arm  7  and the upper arm  9  during sewing and/or embroidering and/or quilting or similar processes, and can be processed or acquired there.  
         [0034]     In the target quantity memory  45 , as target quantities or comparison quantities there can be stored information concerning sewing machine elements, or individual features of such sewing machine elements, such as their situation, size, color, shape, and position, e.g. in relation to the sewing machine  1  or in relation to other sewing machine elements. Thus, for example concerning the sewing feet  21  an item of visual information can be stored concerning how they can be recorded by one of the cameras  25  when the sewing foot  21  is correctly fastened to the sewing foot holder  19 . Alternatively, or in addition, an image of the contours or edges of a sewing foot  21  fastened in this way to the sewing foot holder  19 , or of a code  57  situated on the sewing foot  21 , can also be stored. Instead of, or in addition to, the items of visual information concerning correctly mounted sewing machine elements, typical images of incorrectly mounted sewing machine elements can also be stored in the target quantity memory  45 . The image processing unit  43  can process the items of image information recorded by the camera or cameras  25  in accordance with the rules given in a program memory (not shown) as to whether and, if so, which, of the features stored in the target quantity memory  45  agree sufficiently with the features acquired by the camera or cameras  25 , or deviate from these features. If an agreement of features can be determined, the image processing unit  43  can also check the position and orientation thereof. If the image processing unit  43  determines for example that a sewing foot  21  has the number three as code  57 , but that this number three is not situated in the expected orientation and/or at the expected location in the image segment recorded by the associated camera  25 , this is an indication that the sewing foot  21  is not correctly fastened to the sewing foot holder  19 . An additional indication of an incorrectly mounted sewing foot  21  can be the determination that the knee lever  63  on the sewing foot holder  19  is in an open position ( FIG. 5   b ). The image processing unit  43  can cause the machine control unit  47  to warn the user, by means of a warning tone or a warning message spoken by a synthesized voice, of the problem of an incorrectly mounted sewing foot  21 . Alternatively, or in addition, a warning message can also be outputted on the display device  10 , indicating the determined problem. Analogous to the determination as to whether and which sewing foot  21  is fastened to the sewing foot holder  19 , and whether the fastening is free of problems, the present and correct fastening of other sewing machine elements can also be checked. In addition to, or instead of, warning messages, the machine control unit  47  can also initiate other measures. Such processes may include those described non-definitively below:  
         [0035]     Through comparison of the camera image with image information stored in the target quantity memory  45 , the image processing unit  43  recognizes that a particular type of sewing foot is correctly placed in the sewing foot holder. This information is relayed to the machine control unit  47 . Subsequently, the machine control unit  47  displays for selection on the display  10 , which is fashioned as a touch screen, only sewing stitches or stitch types that are compatible with this sewing foot type.  
         [0036]     On the basis of data requested by the image processing unit  43 , the machine control unit  47  recognizes that a double needle  17   c  has been placed in the needle holder  15 , and that a throat plate  33  that is not compatible with this needle type is fastened to the lower arm  7 , for example by a snap connection, screw connection, or magnetic connection. As a first measure, the machine control unit  47  prevents the main drive  51  from being able to be activated, or decouples the needle bar  13  from the main drive  51 . As a further measure, a warning is outputted on the display  10  and/or the acoustic signal generator  49 , as described above.  
         [0037]     The machine control unit  47  receives from image processing unit  43  a communication that a foreign object, such as for example a pin, a scissors, or the finger of a person, is situated in the stitch formation area under the needle  17 . As described, the machine control unit  47  prevents the sewing process from starting. Of course, safety-relevant quantities can also be acquired in redundant or parallel fashion by additional acquisition means.  
         [0038]     The machine control unit  47  initiates the storing of data currently acquired by the image processing unit  43  in a temporary working memory (not shown) and continuously updates these data. The sequence and frequency of these updatings and/or of the acquisition of individual sewing machine elements by the image processing unit  43  can depend for example on actions of the operator such as the operation of the foot switch for starting the sewing process, on a possible risk of injury, and on the risk of damage to the sewing machine  1 .  
         [0039]     The machine control unit  47  signals the image processing unit  43  to acquire items of information such as for example the presence, the correct mounting, or the type of various sewing machine elements.  
         [0040]     Analogous to items of information concerning the sewing machine elements, the image processing unit  43  can also acquire, process, and store in the target quantity memory  45  items of information concerning sewing elements, their structural features, and their situation and orientation, for example in relation to the sewing machine  1  or in relation to sewing machine elements. Thus, for example, for one or more different types of material or fabric, and for particular orientations of the material given a flat seating on the lower arm  7  in the area of the throat plate  33 , the typical directions of the thread orientations, the thread thickness, and/or the distance between adjacent threads and/or the number of threads per length unit in one or more directions or dimensions, and/or the color, can be stored. In addition, in the target quantity memory  45  images can be stored of the upper thread threaded in the needle  17 , or of the course of the upper thread in the area of the needle  17  or in the area between the sewing machine head  11  and the throat plate  33 , as well as images of the bobbin thread in the area of the hook  35 .  
         [0041]     In the following, additional sewing elements or features of such sewing elements are stated in a non-conclusive list:  
         [0042]     Color of threads or of seams,  
         [0043]     Thickness of threads or of seams,  
         [0044]     Thread orientation without and with broken thread,  
         [0045]     Brightness, color, shape, design, contour, structure, size, position, or orientation of a sewing element or of a part thereof,  
         [0046]     Seam appearance (in particular, the design of a seam, the thread entry and/or knotting),  
         [0047]     Various types of material, seated flatly,  
         [0048]     Embroidery pattern or images, or applications,  
         [0049]     Shapes or contours of the article being sewn, with correct and/or incorrect (e.g. bunched or twisted) seating.  
         [0050]     The storing of features or target quantities of the sewing machine elements and the sewing elements can for example take place from an external data carrier via a communication interface of the sewing machine  1 , the data carrier being able to be connected to the sewing machine  1  directly or via a communication network and/or via the Internet (not shown).  
         [0051]     Alternatively, or in addition, the image processing unit  43  can be designed to acquire images of sewing elements and of sewing machine elements that are positioned correctly on the sewing machine  1 , and to store them in the target quantity memory  45 . For this purpose, the user activates a learning mode at one of the operating elements  12 . Subsequently, the cameras  25  acquire, in immediate succession, an image of the correctly positioned sewing machine element or sewing element and an image without this element. From these images, the image processing unit determines an image of the element itself as a difference between the images. This image of the element can be stored in the target quantity memory  45  directly or after a subsequent further processing by the image processing unit  43  using known image processing methods, such as edge extraction or Fourier transformation. Information concerning the sewing machine elements that have been detached from the sewing machine  1  or are fastened correctly or incorrectly on the sewing machine  1  or on the mounting devices thereof can for example be stored in the target quantity memory  45 . The target value memory  45  can also include information concerning a plurality of possible dispositions, operating positions, or orientations of sewing machine elements on the sewing machine  1 .  
         [0052]     In addition to the target quantity memory  45 , the sewing machine  1  can comprise a data memory unit (not shown). This can be physically identical with the target quantity memory  45 , or can alternatively be fashioned as an additional storage medium. In the data memory, images recorded by the camera or cameras  25  can be stored as needed. In this way, for example current sewing operations can be documented, or patterns can be stored. In addition, the sewing machine  1  can comprise a modem, or in general a communication interface, for the creation of communication connections via a network and/or the Internet. Images recorded by the cameras  25  of a problem situation can thus easily be communicated to a help desk, for example. In the reverse direction, images, or any information, can be loaded into the data memory via the Internet. In order to support or facilitate operational steps, such as for example the threading of a thread into the eye of the needle  17 , or the precise positioning of the article being sewn  67  under the needle  17 , images acquired by the camera or cameras  25  can also be displayed on an LCD and/or on the display unit  10 .  
         [0053]     The cameras  25  can be fashioned such that both the acquisition of individual images and also of rapid image sequences are possible. The image processing unit  43  can be fashioned such that, in particular, the following monitoring, auxiliary, storage, measurement, control, or regulatory functions are possible in connection with the machine control unit  47 :  
         [0054]     monitoring of the upper thread and/or of the bobbinthread for thread breakage,  
         [0055]     monitoring of the advance of the material,  
         [0056]     recognition of stretching and/or twisting or bunching, i.e., the drawing together of the material,  
         [0057]     monitoring of the thread entry and/or of the knotting of the bobbin thread and upper thread,  
         [0058]     recognition of shifting of the position of the material during the processing of a stack having a plurality of layers of material,  
         [0059]     monitoring of the seam quality,  
         [0060]     recognition of different types of material,  
         [0061]     recognition of the movement of the material (magnitude, direction).  
         [0000]     This information can be used to determine the slippage, i.e., a deviation of the actual movement of the material from the desired movement. In particular, it can be used as a measurement quantity and the controlling of the material transport device.  
         [0062]     acquisition of the positions of individual patterns or features on the material; use of this information in order to control position during embroidery.  
         [0063]     acquisition or measurement of patterns (size, shape). Use of this information to influence pattern formation, for example in the creation of buttonholes,  
         [0064]     acquisition of the brightness or of the illumination of the article being sewn  67 ; use of this measurement quantity as a regulating quantity for regulating the brightness of a sewing light (not shown),  
         [0065]     acquisition and storing of images of the current sewing operation (archiving, documentation),  
         [0066]     acquisition of images for communication to a help desk (e.g., by means of a modem that is integrated in the sewing machine  1  or that can be connected thereto),  
         [0067]     acquisition and imaging of sewing machine elements and/or sewing elements, or parts thereof, on an LCD or on the display unit  10 , e.g. as an auxiliary means during threading, or for the precise positioning of the article being sewn  67  under the needle  17  during embroidery.  
         [0068]     With the device according to the present invention and the method according to the present invention, during operation of the sewing machine  1  safety can be increased, errors can be prevented, operation can be simplified and/or automated, and the quality can be improved.