JPH04226696A - Sensor adjustment using for sewing so as to match pattern - Google Patents

Abstract

PURPOSE: To optimally suit a device for detecting a pattern to the respective patterns. CONSTITUTION: In order to scan sewing materials 11a and 11b in an intended sewing direction for length at least same as the repetition length of the pattern, sensor systems 10a, 10b, 12a and 12b are separated before starting a sewing process during an adjustment stage, and adjustment is performed to a value for maximizing an amplitude change area by at least one of the operation parameters of a pattern sensor for determining the modulation area of detection signals during the adjustment stage. In order to clearly separate the detection signals before and after the sewing material reaches a scanning position, an optical detector is specially provided, and the detector releases a step or a device for offset and/or amplitude adjustment when the sewing material reaches the grasping position of the pattern sensor first. By this method, it is guaranteed that only signal fluctuation by the pattern is counted in and a signal value generated in the case that the sewing material is absent is not counted into an adjustment standard.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for adjusting a sensor system used for sewing matching patterns.

The present invention includes two pattern sensors that generate detection signals under optical scanning of a sewing piece during operation of a sewing machine, and the detection signals reproduce brightness changes due to the pattern of the corresponding sewing piece as amplitude changes. Sewing with two patterns in the sewing machine is sent to a processing device, which detects information about one-dimensional or two-dimensional deviation of the patterns of both sewing pieces under comparative analysis of the detection signals. The present invention relates to a method and apparatus for adjusting a sensor system used to sew pieces in a matching pattern.

0003

[Prior Art] For example, two pieces of textile fabric with one pattern
In order to sew together two patterned sewing pieces, such as two pieces, so that the patterns match, during the sewing process both sewing pieces must be constantly oriented toward each other so that the pattern elements match at the sewing position. Must be aligned.

It is generally known to further automate the inspection and correction of pattern deviations that may occur during sewing, which is necessary for this purpose; in this case, so-called pattern sensors are usually used, which pattern sensors are installed on the sewing machine. During operation, the sewing piece is optically scanned to generate a detection signal, and when the pattern sensor is moved, the detection signal reproduces the brightness change due to the pattern of the sewing piece in question as an amplitude change. In order to receive information about the magnitude and direction of the pattern, possibly two-dimensional, deviation, the signal processing device uses a comparative analysis of both detection signals to determine the temporal "degree of overlap" of the corresponding signal parts.
or, in some cases, checked for time lag. Under the use of this information, the interaction of two feeding systems acting separately on both sewing pieces (Z
usammenspiel) is controlled.

Various algorithms are known for the comparative analysis of both detection signals. For example, German Patent Publication No. 33 46 163 C1 discloses the computation of pattern deviation from a cross-relation function of simultaneously acquired parts of the detection signal, in which a displacement parameter associated with the maximum of the function is detected and accepts direct inductive reasoning to pattern deviation according to the degree of overlap. Another method is known, for example from DE 37 04 824 A1, in which edges (Fl
The objective is to compare the temporal positions of (anke).

Suitable pattern sensors are likewise known in different embodiments. The pattern sensor detects the light reflected from the sewing piece, usually at a location close to the sewing needle, and is arranged above or below both sewing pieces that are present together, each with one specific illumination device (e.g. Public notice No. 3346163C1
) or is present as a flatly formed element between both upper and lower sewing pieces, in particular with common lighting devices (e.g. DE 37 26 704 and DE 38 43 073) reference).

It has been found that the detection signal sent by the pattern sensor is not perfectly suitable in all cases, but should derive from the detection signal the necessary unambiguous information about the pattern deviations that occur. For many patterns, the differences in brightness, and therefore the amplitude changes in the sensed signal, are so weak that the processing unit is never in a position to recall explicit information about pattern shift. Here an improvement is achieved in certain cases, when the pattern becomes color acquainted (farbtu
From the detection signals of the various color extractions scanned by the sensor system and transmitted during operation, the detection signal exhibiting the greatest intensity difference is always selected, as is known, for example, from DE 39 02 473 A1. As noted in the same publication, it is possible to have different calculation methods available in the processing unit for pattern deviations in order to always choose the calculation method that provides the best calculation for each pattern during operation. I can do it.

[0008]

[Problem to be Solved by the Invention] Despite the known possibility of optimally adapting the processing of the detection signal to each pattern by selecting a color extraction or calculation method, it is possible that the pattern does not actually exist. Even if it is not possible to automatically match and sew the pattern by means of For example, due to cost reasons, the sensor system should be made color savvy (
When one would forego the processing device for many calculation methods or the processing device for many calculation methods, one would consider these measures to be very expensive. There may be cases where It is therefore advantageous to have, additionally or alternatively to the known optimization techniques, another possibility of optimally adapting the devices involved in pattern recognition to the respective pattern. It is the object of the present invention to satisfy this desire.

[0009]

According to the invention, the object includes two pattern sensors that generate detection signals under optical scanning of the sewing piece during operation of the sewing machine, the sewing piece to which the detection signal corresponds. The sewing machine reproduces the brightness change due to the pattern of the sewing machine as an amplitude change and sends it to a processing device, and the processing device detects information about one-dimensional or two-dimensional deviation of the pattern of both sewing pieces under comparative analysis of the detection signals. A method of adjusting a sensor system used to sew two patterned sewing pieces so that the patterns match in The sensor system is commanded during the adjustment phase before the start of the sewing process to scan in the direction, and at least one of the operating parameters of the pattern sensor defines the modulation range of the sensed signal during the adjustment phase and the amplitude change range This problem is solved by a sensor system adjustment method characterized in that the sensor system is adjusted to a value that maximizes.

The basic configuration of the device for solving the problem includes an adjustment member for adjusting the operating parameters of the pattern sensor that determines the modulation area of the detection signal, and an adjustment member that grasps the magnitude of the detection signal of each pattern sensor and adjusts the detection signal accordingly. a control device operable during the adjustment phase before the start of the sewing process in order to control the magnitude of the detection signal to the target value by energizing the adjustment member; It includes two pattern sensors that generate detection signals under target scanning, and the detection signals reproduce the brightness changes due to the pattern of the corresponding sewing piece as amplitude changes and are sent to a processing device, which performs a comparative analysis of the detection signals. The sensor system used in the sewing machine to sew two patterned pieces so that the patterns match, obtains information about one-dimensional or two-dimensional misalignment of the patterns on both pieces. In the adjustment device, the magnitude grasped by the control device is the magnitude of the detection signal that determines the modulation region of the detection signal when scanning the sewing piece, and the control device controls the adjustment member to determine the amplitude change region of the detection signal. This is a sensor system adjustment device characterized by biasing in the direction of maximizing the force.

Advantageous embodiments of the invention are shown in the embodiments below.

0012

[Operation and Effect] The basic idea of the invention is to connect an adjustment step before the sewing operation, in which the sewing product is scanned by a pattern sensor, so as to obtain a detection signal that also occurs during the sewing operation. . At least one operating parameter of the sensor system, which defines the modulation range of the detection signal, is adjusted here to a value at which the amplitude change of the detection signal is at a maximum.

The operating parameters of the sensor system that define the modulation range of the sensed signal are amplification and offset. Under "amplification" is generally understood the rise of a sensor characteristic curve which shows the amplitude of the sensing signal as a function of the scanned material properties of the garment. This material property is the reflectance in the case of reflected light scanning, and the transmittance of the sewn article in the case of transmission scanning. "Offset" is to be understood as an axial translation of the sensor characteristic curve.

The optimum amplification value for a given offset is the value at which the maximum value of the detection signal reaches the modulation upper limit of the direct pattern sensor, since in this condition also the width of the amplitude change region of the detection signal, ie This is because the peak-to-peak value of the amplitude change is maximized, providing the processing device with the best conditions for signal analysis and calculation of pattern shift. In an embodiment of the invention, the amplification of the sensor system is thus adjusted appropriately during the adjustment phase.

[0015] An amplified adjustment of a sensor system for pattern-matching stitching during an adjustment phase before the start of the sewing process is known from DE 38 43 073 A1. For this prior art, however, the problem is not to maximize the pattern-dependent amplitude variation of the detection signal, but rather to be able to use the sensor system for edge detection. Therefore, the background to be scanned in the absence of a sewing object is designed to a fixed reference reflectance on the side facing the reflective area of the sewing object, and the amplification is adjusted such that the amplitude of the detection signal falls in said area in the absence of a sewing object. During the adjustment phase, the background is scanned alone and not the sewing material. This measure completely ignores the pattern-related fluctuations of the detection signal, which in the case of the invention forms the adjustment reference.

For example, when the sewing material is very bright or very dark and the pattern shows only a slight difference in brightness,
A situation can be provided in which an amplitude change region exists near the modulation upper or lower limit of the sensor system, so that an increase in the amplitude change is never possible only by an amplification change. For such cases, it is advantageous to move the modulation range of the detection signal to an average between the upper and lower modulation limits of the sensor system by changing the offset of the sensor system. This means already itself extends the range of amplitude changes (i.e. the peak of the detected signal).
This leads to a widening of the two-peak amplitude, since signal swings that are partially limited at the modulation limit are fully effective in the average of the modulation range. This is particularly important in the case of non-linear S-shaped sensor characteristic curves with a maximum slope on average in the modulation area. In a preferred embodiment of the invention, however, both the offset adjustment and the further amplification adjustment are carried out. The offset adjustment can in particular be performed initially and, if desired, in response to an intermediate decision of the definitive sensing signal to make a subsequent amplification adjustment, for example by making an offset adjustment to reduce the peaks of the later sensing signal. - Depends on whether the two-peak amplitude reaches a pre-given minimum value. The determination is also based on the result of the algorithm used in the processing device, e.g. the use of both sensing signals to check whether the amplitude change reaches a predetermined minimum when the movement parameter changes. This can be done based on a cross-correlation function.

A similar determination can also be made at the end of said adjustment step in order to determine whether the sewing product can be guided as a whole automatically by means of existing means or whether it should be guided manually. can be done.

It is already known from DE 40 01 534 A2 to consider the question of whether an automatic correction of pattern deviations in the case of pattern matching sewing is entirely possible by means of the respective methods. However, the problem here is not the characteristics of the pattern or the processing possibilities of the detection signals, but the ability of the correction device to compare initial pattern deviations and very large pattern deviations. According to this prior art, the magnitude of the pattern deviation that exists during the needle-no-thread test process is determined to determine whether the existing pattern deviation is beyond the possibility of automatic correction. Ru. This measure has no contact point with the adjustment of the sensor system to optimize the detection sensor.

In the present invention, the amplification adjustment is carried out in particular in such a way that during the adjustment phase the amplification is first pre-adjusted to a defined value and then the maximum value of the detection signal in this amplification is determined. From this maximum value and the known values of the preset amplification and modulation limits, the amplification value at which the maximum value of the detection signal approaches the modulation limit of the pattern sensor is then calculated and input.

[0020]In order to clearly separate the detection signals before and after the sewing item reaches the scanning position, an optical detection device is provided, in particular an optical detection device, which includes steps or devices for offset and/or amplification adjustment. First, when the sewing object reaches the grasping position of the pattern sensor, it is released. This method also ensures that only the signal fluctuations due to the pattern are taken into account, and that the signal values that occur in the absence of a sewn object are not taken into account in the adjustment standard. The detection device can be formed by an additional light barrier or can be realized by appropriate presetting of the pattern sensor amplification and by suitable signal evaluation. In the last case, in order to detect the seam edge, the maximum possible amplification must be set before the start of sewing, in which case an amplitude jump can be detected in the marginal fabric. It can be started from. After the detection of the sewing material edge, first the amplification factor for scanning the pattern is reset to the average value, and then the actual adjustment phase begins.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Advantageous embodiments of the invention are explained in more detail below with reference to the drawings.

Two vertically stacked fabric layers 11a are shown on the left side of FIG.
, 11b are shown, and the fabric layer is moved by an associated feed device (not shown) as a sewing item on the needle plate 6 of the sewing machine.
During the sewing operation, it is moved in the direction of the arrow so as to be sewn together by another left needle bar (not shown). The sewing machine used here is German Patent Publication No. 3346163C.
Since this corresponds to the sewing machine disclosed in No. 1, there is no need to go into detail about the sewing machine. both fabric layers 11a,
As shown in FIG. 1, the pattern 11b is formed by, for example, stripes of bright and dark areas extending crosswise to the feeding direction. The pattern elements (stripes) are shown slightly offset from each other in the upper and lower fabric layers, but the pattern elements should be matched to each other when sewing, which is explained briefly below. This is accomplished by selecting control of the device.

[0023] In order to check for pattern deviations, each of the two fabric layers is scanned by an associated pattern sensor. For this, the upper fabric layer 11a is located at the scanning location and the optical sensor 1
The light illuminated by 0a and reflected from the fabric surface layer is captured by a receiver 12a and converted into an electrical signal whose amplitude increases as the fabric layer 11 is moved in the direction of the arrow.
It changes according to the brightness change due to the pattern a. Light receiver 12
The output signal of a is shown inside the dashed box 20 via an amplifier 13a and a filter 14a which suppresses the non-informative spectral components of the signal, and which is shown inside the dashed box 20 and which can be realized, for example, by a microcontroller. Then it reaches an analog/digital converter 15a which provides the detection signal Fa in the form of successive digital amplitude scan values. Lower fabric layer 11b is scanned in a similar manner, in the case shown fabric layer 11
Scanning is performed by a light projector 10b that illuminates the lower side of the needle plate 6 through an opening in the throat plate 6 via a light guide bundle 7, and a light receiver 12b that receives light reflected from the cloth layer 11b via a light guide bundle 8. In order to form a linear scanning field, as is known, for example, from DE 33 46 163 C1, the light guiding bundles 7 and 8 have a particularly small extent in the direction of transport of the sewing material and a large extent perpendicular thereto.

A suitable linear scanning area is also the upper fabric layer 11a.
This can be determined by suitable imaging of the optical system of the further light sensor 10a and the further light receiver 12a. The initial signal of the photoreceiver 12b is similarly passed through an amplifier 13b, a filter 14b, and an analog/digital converter 15b in the form of a digital scanning value and is sent to the electronic switch 20 as a detection signal Fb.
is input to the second input of.

In the processing unit 22 of the electronic switch 20, the amount of overlap or the relative step shift of both signals is confirmed from the scanning values of the detection signals Fa and Fb, and correction signals A and B are derived therefrom. In order to avoid pattern shift due to relative movement of the fabric layers 11a and 11B, both feeding devices are selectively operated. Suitable algorithms for calculating pattern deviations and suitable devices for correction of deviations are known per se, for example from the other above-mentioned patent documents, and do not need to be described individually here. So that the processing device 22 can check the amount of overlap between the detection signals Fa and Fb,
Amplitude changes due to the pattern of the detection signal must be clearly distinguishable. For this reason, the modulation range of the pattern sensor (voltage variation tolerance range)
It is preferable to amplify each of the sensed signals so that the signal (gsbereich) is optimally utilized. Figure 2 shows part F1
, shows the initial signal of one of the receivers 12a or 12b with a maximum amplitude reaching approximately the middle of the modulation range between 0 and 10 volts. Preferably, the maximum amplitude is near the 10 volt modulation limit. In order to adjust the amplification necessary for this purpose, the electronic switching device 20 includes a control device 23, which controls the successive scanning values of the detection signals from the respective memories 21a, 21b during activation. the maximum value is detected and an adjustment signal is provided to the amplification control input G of the respective amplifier 13a or 13b, the adjustment signal being amplified such that the maximum value of the corresponding sensed signal reaches close to the upper modulation limit. Adjust. After this adjustment, electronic switch 2
0 produces a detection signal as shown in part F2 of FIG. arise.

Said adjustment step is carried out during the adjustment phase and before the start of the sewing operation. For this, the operator first activates the adjustment stage input key 25 and moves both fabric layers 11a, 11B into the sewing machine. An optical sensor 30 located at or slightly behind the scanning position of the pattern sensor supplies a release signal E with the indication "sewn item present" as soon as the fabric layer reaches the scanning position.

The program switching device 24 formed in the electronic switching device 20 then takes over control of another flow, as shown in the flowchart of FIG. The program changeover device first determines the state of the input key 25 to see if an adjustment step has been input and whether the sewing item is in the scanning position (steps 301 and 302 in FIG. 3). If YES, the memories 21a and 21b are activated and store n successive scan values of the detection signals Fa and Fb occurring during successive movements of the fabric layers 11a and 11b (step 303). The number n can be adjusted by the operator with an adjustment knob and is selected such that a pattern area that is at least as large as the repeat length of the pattern is captured. For small area patterns, relatively few scan steps (e.g. 20) may be sufficient, whereas large area patterns may require a large number (thousands) of scan steps. be.

From the stored scanning values, the sensor control device 23, which is then formed in the electronic switch 20, determines from this value:
In order to calculate how much the amplification of the respective amplifier 13a or 13b should be changed, the respective maximum amplitude is determined (step 304) and the maximum amplitude is brought close to the modulation limit (step 305). The controller 23 then sends an appropriate control signal to the amplification adjustment input G of the appropriate amplifier (step 306).

If desired, now an intermediate step 307
can be inserted, in which step it is determined whether the sensing signal, now with adjusted amplification, is suitable for calculating pattern deviation. On the other hand, the program switching device 24 is configured such that the peak-to-peak amplitude of the detection signal is determined by the control device 23 or the processing device 22 in order to turn on the alarm lamp or other indicator 27 when this value is not obtained. can be commanded to be compared with the minimum value. The determination can also be performed by an algorithm used in the processing device 22 for calculating the pattern shift, for example by determining a correlation function as further described above.

After the amplification adjustment has been successfully completed, the adjustment phase is canceled, for example the signal then sent by key 25 is deleted, and the sewing process is released (step 308).
. The state of signal E (product present) is such that the sewing process ends (step 310) when the fabric layer leaves the scanning position.
It is further monitored (step 309). By inserting another item to be sewn, the program can be started again from the beginning.

[0031] In the case of a large number of cloth patterns, it is possible that a signal level may arise which moves close to the upper or lower limit region of the amplifier and therefore can no longer be amplified. Such a relationship is illustrated by signals F3 and F4 in FIG. In this case, it is advantageous to shift the signal level by a change in offset to approximately the average region of the respective sensor amplifier, so that before amplification the signal is as shown in part F5 of FIG. In fixedly adjusted sensor amplifiers, this movement may already be sufficient in some circumstances to provide a final sensing signal that is sufficiently distinguishable for the processing algorithm for correction of pattern deviations. can. However, an amplification adjustment can still be connected to the offset movement step as described above.

FIG. 4 shows a flow diagram of offset adjustment. The program starts as in the flow diagram of FIG. 3, and after step 303 shown therein, first the average value of the relevant detection signal, rather than its maximum amplification, is determined (step 401). From the determined mean value and the known value of the mean of the modulation area, it is then calculated how the offset has to be adjusted in order to bring the signal mean value to the modulation mean (step 402). The offset value detected in this control device 23 is then set at the associated control input D of the respective amplifier 13a or 13b (step 403). If desired, it is then determined whether the signal is suitable for processing after inputting this offset (step 404), as shown in FIG.
may be performed in a manner similar to that described further above in connection with step 307 of the flow diagram. This determination can be transferred directly to step 308 of the flow diagram of FIG. 3 in case of a positive output, otherwise transferred to step 304 of the flow diagram of FIG.
We obtain a signal as shown in part 6 of .

The optical detector 30 is an expansion detector (not shown) which sends a release signal E as soon as and as long as a sewing item is present in the optical path of this light barrier.
can be a subsequent optical barrier (e.g. a reflective coupler). The task of the optical detector 30, however, can also naturally be obtained from one of the pattern sensors (or from both pattern sensors), with a detection signal of at least one predetermined amount relative to the value it would have in the absence of a sewing object. When an evaluation switch is additionally provided, which is activated by the activation of the regulating phase, in order to generate the release signal E when E changes,
Of course can be accepted. When the scanning system is constructed in such a way that a minimum light reception value occurs in the absence of a sewing object,
The amplification of the sensor system is initially adjusted to a particularly maximum value in order to obtain the release signal E.

In addition to the embodiments described above, other embodiments of the invention are also possible. Instead of said numerical determination of the amplification or offset value to be adjusted, the amplification element or A closed regulation circuit acting on the offset member can be used. The amplification adjustment can alternatively (or additionally) also be erfolgened by the influence of the illumination intensity of the garment, as shown by the connecting line shown in dashed lines in FIG. or possibly by a modulation of the driver for a common light sensor). Finally, it should be noted that the movements required for the adjustment step of the sewing product can be performed either by the operator's hands or by the feed system of the machine. The feed system may be advantageously treated during the adjustment phase when the processing possibility of the detection signal is checked.

The embodiments of the present invention are as follows.

1) Claim characterized in that during the adjustment phase the amplification of the sensor system is adjusted to an optimal value, at which value the maximum value of the detection signal reaches as close as possible to the upper modulation limit of the pattern sensor. The method described in Section 1.

2) For setting the optimal amplification value a)
the amplification is first preset to a limiting value, b) a maximum value of the sense signal is detected at the preset amplification, and c) the detected maximum value and a plurality of known values of the preset amplification and a modulation upper limit. The method according to claim 1, characterized in that the method is detected from and then set.

3) The offset of the detection signal is adjusted to an optimum value during the adjustment step, in which the range of amplitude variation of the detection signal lies approximately at the average of the modulation range of the pattern sensor. The method described in 1.

4) The third method is characterized in that only the amplification of the detection signal according to the first or second item is adjusted.
The method described in section.

5) It is determined exclusively whether the detection signal can be processed in order to obtain expressive information about the pattern deviation, and in the case of a negative result of this determination, the amplification of the detection signal is performed according to the first method described above. The method according to item 3 above, characterized in that the method is adjusted by item 3 or item 2.

6) The fifth method described above, characterized in that, in order to determine whether the detection signal can be processed, it is determined whether the peak-to-peak value of the amplitude change reaches a predetermined minimum amount. The method described in section.

7) that during the adjustment phase a constant relative movement between the sewing object and the sensor etc. is caused, that the resulting detection signal is fed to a processing device, and that the cross-correlation function changes; It is determined whether or not the amplitude change of the cross-correlation function reaches a predetermined minimum amount in the parameter. The method according to item 5 above for.

8) To adjust the adjustment members (13a, 13b), which determine the amplification of the detection signal depending on the magnitude of the information, in such a way that the maximum value of the detection signal reaches very close to or as close as possible to the adjustment limit. Then, the control device (23) connects a device for grasping the maximum value of the detection signal and a corresponding pattern sensor (
10a, 12a, 13a, 14a, or 10b, 1
2b, 13b, 14b) for receiving information indicating a modulation upper limit.

9) The control device (23) calculates the amplification value to be input from the amplification value input for starting, the maximum value of the detection signal grasped in the case of this input, and the modulation upper limit value. 9. The device according to item 8, characterized in that it includes a calculation device.

10) In order to adjust the adjustment member (13a, 13b) that determines the offset depending on the magnitude of information so that the amplitude change area of the detection signal is located at the average of the modulation area of the corresponding pattern sensor, 3. The control device (23) comprises a device for ascertaining the position of the amplitude variation region of the detection signal and a device for receiving information indicating an average of the modulation region of the pattern sensor. equipment.

11) First, the control device controls the adjustment member (1).
3a, 13b) input the offset adjustment input (D),
Second, the program switching device (2
4) The device according to any one of items 8 to 10 above.

12) After the first operation of the control device (23) is completed, the program switching device (24) is activated to compare the peak-to-peak value of the amplitude change of the detection signal with a predetermined minimum value. Device 13) according to item 11 above, characterized in that the program switching device switches the second operating flow only if possible and the minimum value is not reached.
The sewing material (11a, 11b) is detected by pattern sensors (12a~
15a or 12b-15b), which is activated during the adjustment phase for movement at a constant speed with respect to the processing device (15a or 12b-15b), and the processing device ( The programming device (22) is used to compare the amplitude change obtained in the cross-correlation function (22) depending on the movement parameter of the cross-correlation function with a predetermined minimum value.
), the control device (23) is activated and the program switching device only switches on the second value when this minimum value is not reached.
12. The apparatus according to item 11, for the case where the processing apparatus obtains information about pattern displacement using a cross-correlation function of the detection signals of both pattern sensors, characterized in that the processing flow is switched to the operating flow.

14) The comparator is connected to the control device (23) in order for the program switching device (24) to generate a signal indicative of the inoperability of the sewing item (11a, 11b) when the minimum value does not reach the comparator. 14. The device according to claim 12 or 13, characterized in that it operates again after the second operating flow of step 1) is completed.

15) When the release signal (E) is detected by the pattern sensor (
12a to 15a or 12b to 15b) is reached for actuation of the control device (23). The device described.

16) Device according to claim 15, characterized in that the grasping device (30) is formed by a further light barrier.

17) The grasping device is a pattern sensor (12a
- 15a or 12b - 15b) and another evaluation device, and the evaluation device determines that the level of the detection signal of the corresponding pattern sensor is lower than a predetermined amount with respect to the level to be adjusted when there is no sewing material. 16. The device according to claim 15, wherein the device generates a release signal when changing dramatically by an amount greater than or equal to the amount.

18) The light receiving side portion (for example, 13a or 13b) of the pattern sensor to which the control device (23) applies
18. The device according to claim 17, characterized in that the amplification of the release signal (E) is maintained before it indicates the maximum possible value and that the activation of the average starting value carried out by the release signal (E) is initiated. .

[Brief explanation of the drawing]

1 is a schematic illustration of a sensor system for pattern-matching sewing with a device according to the invention for sensor adjustment; FIG.

2 is a diagram of the detection signals of the pattern sensor of the system shown in FIG. 1 under various conditions; FIG.

3 is a flow diagram for the amplification adjustment of the sensor system according to FIG. 1; FIG.

4 is a flow diagram for offset adjustment of the sensor system according to FIG. 1; FIG.

[Explanation of symbols]

11a sewn items 11b sewn items 13a adjustment member 13b adjustment member 23 Control device Fa detection signal Fb detection signal

Claims (2)

[Claims] 1. A sewing machine comprising two pattern sensors that generate a detection signal under optical scanning of a sewing piece during operation of a sewing machine, and the detection signal is processed by reproducing a brightness change due to the pattern of the corresponding sewing piece as an amplitude change. 2 in the sewing machine, which processing device detects information about the one-dimensional or two-dimensional deviation of the pattern of both sewing pieces under comparative analysis of the detection signals.
A method of adjusting a sensor system used to sew two patterned sewing pieces so that the patterns match, the sewing material being scanned in the intended sewing direction for a length that is at least equal to the repeat length of the pattern. the sensor system is commanded during an adjustment phase before the start of the sewing process, and during the adjustment phase at least one of the operating parameters of the pattern sensor defining the modulation range of the sensed signal maximizes the amplitude change range. A method for adjusting a sensor system, characterized in that the sensor system is adjusted to a value. 2. An adjustment member for adjusting the operating parameters of the pattern sensor that defines a modulation region of the detection signal, and an adjustment member that grasps the magnitude of the detection signal of each pattern sensor and adjusts the magnitude of the detection signal. a control device operable during an adjustment phase before the start of the sewing process in order to control the target value by the force of the sewing machine, and which generates a detection signal under optical scanning of the sewing piece during operation of the sewing machine; The detection signal reproduces the brightness change due to the pattern of the corresponding sewing piece as an amplitude change and is sent to a processing device, and the processing device performs a comparative analysis of the detection signal to reproduce the brightness change due to the pattern of the corresponding sewing piece. In a sensor-based adjustment device used for sewing two patterned pieces in a sewing machine so that the patterns match, the control device (23) obtains information about one-dimensional or two-dimensional deviations; The size to be grasped is the sewing piece (11
The magnitude of the detection signal determines the modulation region of the detection signal (Fa, Fb) during the scanning of (a, 11b), and the control device (23) controls the adjustment member (13a, 13b).
A sensor system adjustment device characterized in that the sensor system is biased in a direction that maximizes an amplitude change area of a detection signal.