Arrangement for Operating an Electronically Controlled Sewing Machine in a Diagnostic Mode

This invention relates to sewing machines and, more particularly, to electronically controlled sewing machines.

Sewing machines employing sophisticated electronic technology for the storage and subsequent retrieval of stitch pattern information for a multiplicity of patterns have enjoyed great commercial success in recent years. One great advantage of the use of an electronically controlled sewing machine is in its simplicity of operation and control, as perceived by the user. On the other hand, if such a machine malfunctions, it is often difficult for a service technician to diagnose the reason for such malfunction. Accordingly, it would be desirable to provide an aid to help a service technician in diagnosing faults in an electronically controlled sewing machine.

It is therefore an object of the present invention to provide an arrangement for operating an electronically controlled sewing machine in a diagnostic mode.

It would also be desirable to provide such an arrangement without adding any hardware, so that the cost of the sewing machine is kept low.

It is therefore a further object of the present invention to provide an arrangement for operating an electronically controlled sewing machine in a diagnostic mode which utilizes the already existing hardware of the sewing machine.

The foregoing and additional objects are attained in accordance with the principles of this invention by providing an electronically controlled sewing machine including diagnostic means for operating the sewing machine in a diagnostic mode. The sewing machine includes input means for allowing an operator to select functions to be performed by the sewing machine and indicating means for providing an indication of the function selected by an operator via the input means. The diagnostic means includes means for utilizing the indicating means to provide an indication to the operator of the operation of the sewing machine while in the diagnostic mode.

In accordance with an aspect of this invention, the arrangement includes means for monitoring the speed of operation of the sewing machine and utilizing the indicating means to indicate the speed of operation.

In accordance with another aspect of this invention, the sewing machine includes motor control means for controlling the speed of operation of the sewing machine which normally operates in response to an operator setting of a speed control device, such as a foot controller. The arrangement includes means for operating the sewing machine at a fixed predetermined speed independent of operator control.

In accordance with a further aspect of this invention, the arrangement includes means for utilizing the indicating means to indicate the relative position of the sewing machine needle.

In accordance with yet a further aspect of this invention, the diagnostic means includes means for controlling the indicating means to indicate the sewing machine functions in a predetermined ordered sequence and at a regular rate. This allows the service technician to check on the functioning of the indicating means.

The foregoing will be more readily apparent upon reading the following description in conjunction with the drawings wherein:

FIG. 1 is a front elevational view of an illustrative sewing machine in which this invention may be incorporated;

FIG. 2 illustrates a general block diagram of a microcomputer based control system for the sewing machine of FIG. 1; and

FIGS. 3A, 3B, 4A, 4B and 5 are flow charts of programs and subroutines for operating the microcomputer of FIG. 2 in accordance with the principles of this invention.

Referring now to the drawings, wherein like elements in different figures thereof have the same reference character applied thereto, FIG. 1 shows a sewing machine designated generally by the reference numeral 10. The sewing machine 10 includes a work supporting bed 12, a standard 14, a bracket arm 16 and a sewing head 18. The sewing machine stitch forming instrumentalities include a needle 20 capable of being endwise reciprocated and laterally jogged to form zig zag stitches and a work feed dog (not shown) operating upwardly through slots formed in a throat plate on the bed 12 to transport the work across the bed 12 between needle penetrations. The pattern of stitches produced by operation of the sewing machine, i.e., the positional coordinates of each stitch penetration may be influenced, for example, by data stored in a memory unit and extracted in timed relation with the operation of the sewing machine, as is well known in the art.

On the front panel of the sewing machine 10 there is provided an input means whereby the operator can effect control of the functions of the sewing machine. This input means includes switches and dials whereby the operator may select a pattern to be sewn by the sewing machine as well as effecting modifications to the pattern. Pattern selection is effected illustratively through an array 22 of pushbutton switches 24, each of which corresponds to a pattern of stitches, the information for forming which is stored within the memory of the sewing machine 10. Associated with each of the pushbutton switches 24 is a pictorial representation of the pattern as it would be sewn by the sewing machine upon actuation of that switch. The input means also includes a stitch width control (bight override) 26 and a stitch length control (feed override) 28. The controls 26 and 28 each includes a pushbutton switch which is operator actuated to effect the respective width or length modification and includes a rotary portion for setting the magnitude of the modification. There are also provided pushbutton switches 30, 32 and 34 for selecting large buttonhole, small buttonhole and round end buttonhole patterns, respectively. A pushbutton switch 36 is provided for reverse sewing. Single pattern selection is effected via a switch 38. The mirror image of a pattern in the bight direction is selected via the switch 40 and the mirror image of the pattern in the feeding direction is selected via the switch 42. The switch 44 is utilized for doubling the length of a sewn pattern. Indicating means for indicating to an operator the status of each of the various functions which may be selected is also provided on the front panel of the sewing machine 10. Illustratively, this takes the form of a plurality of light emitting diodes (LED's) 46 each in close proximity to its respective input switch.

FIG. 2 shows a general block diagram of a microcomputer based controller for an electronic stitch pattern sewing machine, which controller may be utilized to control the operation of the sewing machine 10 (FIG. 1) and which operates in accordance with the principles of this invention. Accordingly, the microcomputer 50 receives input signals from the input switches 52 indicative of the functions the sewing machine operator desires to be performed by the sewing machine. The input switches 52 may include the pattern selection switches 24 and 30-34 as well as the function switches 26, 28 and 36-44. The microcomputer 50 includes an internal central processor unit (CPU) 54 and a program and pattern ROM 56. The CPU 54 obtains from the ROM 56, in timed relation with the operation of the sewing machine, pattern data for controlling the bight actuator system 58 and the feed actuator system 60. The bight actuator system 58 and the feed actuator system 60 are similar in construction and are adapted to convert a digital code word from the microcomputer 50 into a mechanical position which locates the sewing machine needle in a conventional stitch forming instrumentality and provides a specific work feed for each needle penetration, respectively, as is well known in the art. The microcomputer 50 also provides signals to the LED drivers 62 to control the illumination of the LEDs 46 (FIG. 1) to indicate the function selected by the sewing machine operator. Also shown in FIG. 2 is a motor control system 64 which communicates with the microcomputer and which may be controlled by the microcomputer such as, for example, to prevent the sewing machine from operating or to limit the speed at which the sewing machine can be operated or even to operate the sewing machine without operator intervention. During normal sewing, the motor control system 64 operates the sewing machine 10 in accordance with operator commands received from, for example, a foot controller 65. Illustratively, the microcomputer 50 is a type TMS 7040 microcomputer manufactured by Texas Instruments wherein the CPU 54 provides addresses to the ROM 56 over the leads 66 and receives in return bytes of data and program over the leads 68.

In accordance with the principles of this invention, under operator control, the sewing machine 10 may be placed in a diagnostic mode. This may be accomplished by supplying to people authorized to operate the machine in a diagnostic mode, such as for example, service technicians, a plug-in module which fits into an appropriate receptacle (not shown) and which functionally replaces the program and pattern ROM 56 (FIG. 2) with a diagnostic ROM for operating the sewing machine 10 in a diagnostic mode. Alternatively, the program and pattern ROM 56 may be provided with a diagnostic program and data for operating the sewing machine in a diagnostic mode, which program and data would be accessed by the operator (technician) actuating an anomalous combination of the pattern selection switches 24, such as, for example, by simultaneously depressing a defined pair of the switches.

When the machine is placed in the diagnostic mode, a test of the LEDs 46 is automatically initiated. Each of the LEDs 46 from left to right, beginning with the LED associated with the reverse switch 36, and proceeding across and down the panel of the sewing machine 10, ending with the LED associated with the feed override switch 28, is lit for about 1/2 second. When the sewing machine is in the diagnostic mode, the actuation of only five of the switches is recognized, all other switch actuations being ignored. Thus, if the operator actuates the straight stitch switch, the sewing machine 10 will be controlled to sew a straight stitch. If the operator actuates the zig zag switch, the sewing machine is caused to sew a ric rac pattern. If the operator actuates the blindstitch switch, a motor test is performed, as will be described hereinafter. If the bight override switch 26 or the feed override switch 28 is actuated, the corresponding override is turned on or off.

During the LED test, the needle bar remains in the center (straight stitch) position, but signals from the armshaft sensor (not shown) are ignored and the bight and feed actuators remain stationary. When the LED test is completed, the LED associated with the reverse switch 36 is caused to respond to the armshaft sensor such that it is dark when the needle is up and illuminated when the needle is down. Actuating the straight stitch switch selects that pattern and if the LED test is still running, it is terminated immediately. The LED associated with the straight stitch switch is illuminated. Actuating the zig zag switch selects the ric rac pattern but illuminates the LED associated with the zig zag switch. This operation also terminates the LED test if it is running. Actuating the blindstitch switch causes the sewing machine to run at a fixed speed without operator control of the foot controller. This test is a partial check to isolate a defect in the foot controller. The LED test is terminated when this test is selected.

After the LED test is concluded, the speed of the sewing machine is monitored and displayed by means of the bottommost row of the LEDs 46. Thus, if the sewing machine speed is between 650 and 750 stitches per minute, the leftmost of the LEDs in the bottom row is illuminated. As the speed increases, in 100 stitches per minute range increments, succeeding LEDs in that row are illuminated until the last LED in the row is illuminated when the speed is between 1150 and 1250 stitches per minute.

The APPENDIX to this specification illustrates a program for operating the microcomputer 50 in a diagnostic mode, as discussed above. This program is written in assembly language for the TMS 7040 microcomputer, and is for a machine having a specific switch configuration slightly different from that illustrated in FIG. 1. However, the operation of the sewing machine in accordance with the program in the APPENDIX is as described above. FIGS. 3A and 3B together form a flowchart for the program set forth in tfhe APPENDIX FIGS. 4A and 4B are flowcharts of subroutines of that program for the feed and bight overrides, respectively. FIG. 5 is a flowchart of a subroutine of that program for illuminating the LEDs.

Accordingly, there has been disclosed an arrangement for operating a sewing machine in a diagnostic mode. Since this arrangement utilizes switches and indicators which are already available in the sewing machine, no additional hardware is required. It is understood that the above-described embodiment is merely illustrative of the application of the principles of this invention. Numerous other embodiments may be devised by those skilled in the art without departing from the spirit and scope of this invention, as defined by the appended claims. For example, although a programmed microcomputer has been disclosed, this invention may also be practiced with a hard wired processor.