Abstract:
A stitcher is provided that includes a needle configured to place stitches in a fabric that is moved therethrough. The stitcher includes a sensor positioned below the fabric to monitor stitches placed in the fabric. A microcontroller is provided configured to receive data from the sensor and, based on such data, to compare one or more attributes of the monitored stitches with one or more predetermined parameters relating at least one attribute of the fabric. The predetermined parameter may be either hardcoded inn the microcontroller or input by a user of the stitcher prior to beginning operation of the machine. When the attributes of the monitored stitches fall outside of the predetermined parameters, the microcontroller initiates notification of the user.

Description:
CROSS REFERENCE 
       [0001]    This application claims the priority of provisional application Ser. No. 61/147,517, filed Jan. 27, 2009. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to long-arm stitchers and, more particularly, to a stitch quality monitoring system for long-arm stitchers. 
         [0004]    2. Related Art 
         [0005]    Conventional long-arm sewing machines are generally used for quilting and/or sewing fabrics that are not easily moved through a sewing machine. In particular, quilts generally include two outer layers and a filler material that is sewn between the outer layers. Accordingly, to limit the amount of fabric movement when quilting, long-arm sewing machines are typically mounted on a pair of rails that allow the operator to move the needle of the machine while keeping the quilt stationary. 
         [0006]    However, the fabric thickness can cause the fabric to bunch during movement of the needle and/or may cause erratic feeding of the fabric through the needle. Moreover, the filler being stitched into the quilt is often uneven, thereby adding to sewing difficulties and creating difficultly for the operator to follow a stitching pattern, especially when the pattern is not straight. As such, the stitching in the quilt may become uneven and/or may have variable stitch lengths. Additionally, the sewing thread may break and/or loop undesirably when the speed of the machine is adjusted. 
         [0007]    Typically, stitch quality is monitored visually by the operator of the machine. For example, U.S. Pat. 6,260,495, issued to Stewart, describes a monitoring system for a sewing machine that includes a camera to provide images of the article being sewn on a monitor. The image is held for approximately two or three seconds while a worker visually inspects a quality of the hem. In the event the worker sees a hem that is defective, the worker can hit an on/off switch to stop the sewing machine. Unfortunately, such monitoring systems are subject to human error and can often allow undesirable stitching to go undetected and/or slow the sewing process. 
         [0008]    As such, it is desirable to have a sewing machine capable of monitoring and analyzing the stitching in a quilt as the quilt is assembled. 
       SUMMARY OF THE INVENTION 
       [0009]    A stitcher is provided for placing stitches in a fabric. The stitcher includes a monitoring system having at least one sensor positioned below the fabric and angled toward a needle of the stitcher to monitor the stitches placed in the fabric. A microcontroller communicates with the sensor and is programmed with software that analyzes images of the stitches acquired by the sensor. The images are compared with a predetermined set of parameters stored in a memory associated with the microcontroller. These parameters may be either hardcoded in the memory and/or input by a user of the stitcher. When the attributes of the monitored stitches fall outside of the predetermined set of parameters, the stitcher is stopped. The microcontroller then notifies the user as to which parameter has not been met by the stitches. In one embodiment, a monitor is provided to display images of the stitches for manual stitch analysis and/or to display the parameters that have been violated by the stitches. 
         [0010]    The stitcher may be a long-arm stitcher or a standard sewing machine that is configured for either commercial or household use. In the exemplary embodiment, the attributes of the stitches that are analyzed include any one of stitch looping, thread bunching, stitch length, and/or a distance between stitches. The system may also be configured to notify the user if no stitch is detected. 
         [0011]    These aspects are merely illustrative of the innumerable aspects associated with the present invention and should not be deemed as limiting in any manner. These and other aspects, features and advantages of the present invention will become apparent from the following detailed description when taken in conjunction with the referenced drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    Reference is now made more particularly to the drawings, which illustrate the best presently known mode of carrying out the invention and wherein similar reference characters indicate the same parts throughout the views. 
           [0013]      FIG. 1  is a perspective view of a standard long-arm stitcher. 
           [0014]      FIG. 2  is a schematic view of a monitoring system that may be used with the long-arm stitcher shown in  FIG. 1 . 
           [0015]      FIG. 3  is a schematic view of the monitoring system shown in  FIG. 2  in use with the stitcher shown in  FIG. 1 . 
           [0016]      FIG. 4  is an algorithm of a monitoring process performed by the monitoring system shown in  FIG. 2  to analyze a quality of stitches created by the stitcher shown in  FIG. 1 . 
           [0017]      FIG. 5  is an algorithm of image processing performed by the monitoring system shown in  FIG. 2  to acquire images of the stitches created by the stitcher shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    In the following detailed description numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. For example, the invention is not limited in scope to the particular type of industry application depicted in the figures. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention. 
         [0019]      FIG. 1  illustrates a standard long-arm stitcher  10  including a base  12 , an arm  14 , and a take up lever box  16 . Although the present invention is described with respect to a long-arm stitcher, one of ordinary skill in the art would recognize that the present invention is also applicable to standard sewing machines. Moreover, the present invention is capable of operating with both commercial and household long-arm stitchers and sewing machines. The arm  14  is coupled to the base  12  at a back end  18  of the stitcher  10 . A first portion  20  of the arm  14  extends upward from the base  12 , and a second portion  22  of the arm  14  extends from the first portion  20  substantially parallel to the base  12 . The take up lever box  16  is disposed on the arm  14  at a stitching end  24  of the stitcher  10  that is opposite the back end  18 . The stitching end  24  of the stitcher  10  forms a workspace  26  where a fabric is stitched by an operator of the stitcher  10 . The stitching end includes a needle bar  28  having a needle  30  inserted therein and a hopping foot  32  each extending downward toward a needle plate  34  disposed on the base  12 . The needle plate  34  is attached to a square throat plate  36 . The throat plate  36  is configured to be removed to provide access to a rotary hook assembly (not shown) positioned within the base  12  below the throat plate  36 . 
         [0020]    During operation, the needle bar  28  moves up and down thereby moving the needle  30  to form a stitch in the fabric. The needle bar  28  can be adjusted up or down to provide a proper machine timing height. A small hole in the needle plate  34  restricts movement of the thread as the stitch is formed. The hopping foot  32  raises and lowers with the movement of the needle  30  to press and release the fabric as the stitch is formed. The hopping foot  32  is designed to be used with rulers and templates and has a height that can be adjusted for proper stitch formation. A control box  48  is provided to control the operation of the stitcher  10 . 
         [0021]      FIGS. 2 and 3  illustrate a monitoring system  38  used with the stitcher  10  shown in  FIG. 1  to monitoring a stitch quality during operation of the stitcher  10 . Specifically, the monitoring system  38  is configured to detect and monitor stitches placed in the fabric as it is moved through the stitcher  10 . The monitoring system  38  includes a sensor or camera  40  configured to be positioned adjacent the workspace  26  of the stitcher and below the fabric. In the exemplary embodiment, the sensor  40  is a complementary metal-oxide-semiconductor (CMOS) sensor that provides images of the stitches placed in the fabric as the fabric moves through the stitcher  10 . As is well known in the digital arts, CMOS sensors accomplish the task of capturing light and converting it into electrical signals. A CMOS chip is a type of active pixel sensor made using the CMOS semiconductor process. Extra circuitry next to each photo sensor converts the light energy to a voltage. Additional circuitry on the chip may be included to convert the voltage to digital data. More specifically, the CMOS sensor as utilized in an embodiment of the disclosed monitoring system accumulates a signal charge in each pixel proportional to a local illumination intensity, serving a spatial sampling function. When exposure is complete, a charge-to-voltage conversion takes place in each pixel to create an image. 
         [0022]    In another embodiment, the sensor  40  is any sensor or camera capable of detecting and monitoring the stitches as described herein, for example a charge-coupled device (CCD) sensor. A CCD is an analog device. When light strikes the chip it is held as a small electrical charge in each photo sensor. The charges are converted to voltage one pixel at a time as they are read from the chip. Additional circuitry in the camera converts the voltage into digital information. In short, a CCD sensor transfers each pixel&#39;s charge packet sequentially to a common output structure, which converts the charge to a voltage, buffers it and sends it off-chip as an image. 
         [0023]    In the embodiment shown in  FIG. 3 , three sensors  40  are positioned adjacent to the workspace  26 . Specifically, a first sensor  40   a  is positioned in front  42  of the workspace  26 , and a pair of second sensors  40   b  are positioned on each side  44  of the workspace  26 . Each sensor  40  is angled toward the needle  30  of the stitcher  10 . In an alternative embodiment, the monitoring system  38  includes only sensor  40   a  positioned in front  42  of the workspace  26  and angled toward the needle  30 . In another embodiment, the monitoring system  38  only includes sensors  40   b  positioned on each side  44  of the workspace  26 . In yet another embodiment, the monitoring system  38  includes only one of the pair of sensors  40   b . In each embodiment, the sensors  40  are angled toward the needle  30  of the stitcher  10 . The sensor  40  is configured to acquire images of the fabric and stitches as the stitches are placed in the fabric. These images are then transmitted to a microcontroller  46  in communication with the sensor  40 . 
         [0024]    The microcontroller  46  may be disposed adjacent to the stitcher  10  and, in the exemplary embodiment, is digitally interfaced with the sensor  40  and electronically coupled to the control box  48 . In alternative embodiments, the microcontroller  46  may be physically coupled to the stitcher  10  or positioned remotely from the stitcher  10  and coupled to the sensor  40  and control box  48  in a wired or wireless manner. The microcontroller  46  is configured to analyze attributes of the stitches detected by the sensor  40  to determine if the attributes fall within a set of predetermined parameters that are defined for the stitches. Specifically, the microcontroller  46  includes a processor  50  programmed with software that analyzes images of the stitches taken by the sensor  40  to compare the attributes of the detected stitches with the predetermined set of parameters. In an embodiment including more than one sensor, the images from each sensor may be combined prior to analysis or each image may be individually analyzed. In the exemplary embodiment, the processor  50  is programmed with American National Standards Institute (ANSI) C software; however, as will be appreciated by one of ordinary skill in the art, the processor may be programmed with any software capable of analyzing the image as described herein. 
         [0025]    In the exemplary embodiment, the attributes analyzed by the microcontroller  46  include the stitch looping and stitch bunching. For example, the microcontroller  46  determines if the stitch looping includes a predetermined amount of thread and/or a predetermined tightness and if a correct amount of thread is being run through the needle. In other embodiments, the microcontroller  46  can be programmed to determine if there is no stitch present in the fabric or if the stitch length and distance between the stitches falls within predetermined parameters. The predetermined parameters are hardcoded in the processor  50  based on a desired stitch length and/or thread size. Alternatively, the predetermined parameters may be programmed by a user prior to operation of the stitcher  10 . Accordingly, the monitoring system  38  allows for automatic detection of the stitches without user intervention. Further, the monitoring system  38  may be customized based on the stitch length and thread size. In the exemplary embodiment, the microcontroller  46  has the ability to save features embedded in the video in non-volatile and/or volatile memory that is used to compare the current stitch with the predetermined parameters for the purpose of “GOOD/BAD” stitch detection. Specifically the features of the stitch are seen as point to point lines of constant contrast in a video array output. This point to point line is analyzed to determine if the stitch is good or bad. For example, the criteria for “GOOD/BAD” may be the detection of the presence or absence of a loop from point to point. If the point to point line is straight, no loop is present and the stitch is flagged as “GOOD”. If the point to point line is not straight and loops from point to point, the stitch is flagged as “BAD”. 
         [0026]    The algorithms shown in  FIGS. 4 and 5  illustrate the steps taken by the monitoring system  38  during operation of the stitcher  10 . As the fabric is run through the stitcher  10 , the microcontroller  46  automatically analyzes each stitch placed in the fabric. Specifically, at step  100  an image of each stitch is taken by the sensor  40  as the fabric passes through the workspace  26 . The image is then processed at step  102  following the algorithm set forth in  FIG. 5 . At step  104 , the microprocessor  46  determines whether the stitch quality falls within the predetermined parameters. If the stitch quality falls within the predetermined parameters  106 , the microcontroller begins analyzing the next stitch. If the stitch quality falls outside of the predetermined parameters  108 , a user warning is initiated  110 . In one embodiment, the stitcher  10  is stopped and a notification is sent to the user via a monitor  52 . The notification includes an analysis of what parameters have been violated by the stitch. The user is then able to adjust the stitcher  10  accordingly to correct the errors in stitching. When the error is corrected, the stitcher  10  is restarted and the microcontroller  46  continues to analyze each stitch. In the exemplary embodiment, the notification displays a description of each parameter violated on the monitor  52 . Alternatively, the notification may be an alarm, a light, and/or any other audio/visual notification. Further, in an alternative embodiment, the user can manually inspect the stitching on the monitor  52  to determine which parameters have been violated. In one embodiment, the user manually stops the stitcher  10  using a switch  54 . Although, the monitor  52  and the switch  54  are illustrated as being integral with the monitoring system  38 , as will be appreciated by one of ordinary skill in the art, these features may be separate from and electronically coupled to the monitoring system  38 . 
         [0027]      FIG. 5  illustrates an algorithm of the image processing step  102 . Upon initiation of the image processing step  102 , color separation  112  is performed to maximize the contrast between the fabric and the thread. Next, the microprocessor  46  detects  114  loops in the stitch by analyzing the thread line. Specifically, loops in the stitch are detected  114  as curves rather than straight lines which indicate a proper stitch. If a loop is detected  116 , a poor quality flag is set  118  to initiate  110  the user warning. If a loop is not detected  120 , the poor quality flag is cleared  122  and the microprocessor  46  begins analyzing the next stitch  124 . Although the algorithm shown in  FIG. 5  is described with respect to determining loops in the stitch, as will be appreciated by one of skill in the art, the same algorithm is also used to monitor each of the predetermined parameters being analyzed by the microprocessor  46 . 
         [0028]    Accordingly, the present invention provides real-time analysis of stitches placed in a fabric by notifying a user of the stitcher  10  when a stitch quality falls outside of predetermined parameters. As such, the present invention provides a more cost efficient means of correcting stitch errors, thereby reducing costs associated with wasting or re-stitching incorrectly prepared fabrics. 
         [0029]    As various modifications could be made to the exemplary embodiments, as described above with reference to the corresponding illustrations, without departing from the scope of the invention, it is intended that all matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.