JP2656027B2 - Weft detection method for shuttleless loom - Google Patents

Description

The present invention relates to a method for detecting a weft in a shuttleless loom, and more particularly to a method for detecting the presence or absence of a weft inserted into a warp shed. And a method for processing the detection signal.

(Prior Art) Generally, Japanese Patent Application Laid-Open No. 50-160555 or
As disclosed in Japanese Patent No. 156192, the signal output from the weft detector is compared with a reference level signal set in advance in an identification circuit, and the output signal value is equal to or more than the reference level signal value in a predetermined machine rotation angle range. In this case, a machine stop signal is output from the identification circuit, and this signal processing is entirely realized by an analog circuit. The reference level signal to be compared on such an analog circuit is set as the greatest common denominator based on the value of the actual weft detection signal obtained from the experimental data under various conditions, or the actual open circuit is set. As disclosed in JP-A-60-156192, the output signal value from the weft detector is set while recognizing it on an oscilloscope.

(Problems to be Solved by the Invention) However, such a manual setting method of the reference level signal increases the discriminating ability in accordance with the actual weft presence / absence state, that is, the fluctuating signal noise ratio (S / N ratio). Is difficult, and the complexity and uncertainty of having to rely on humans to change the reference level signal depending on the situation is unavoidable. Such inconvenience is caused by the adoption of the analog circuit configuration, and cannot be solved as long as the judgment processing is performed with the analog signal unchanged.

As a conventional technique, a weft detection processing method for a loom disclosed in Japanese Patent Application Laid-Open No. 57-161144 has been proposed. In this method, a weft is detected, a minimum value of the weft detection signal is obtained and tracked at predetermined intervals, a determination level is calculated from the minimum value and a noise level, and the detection signal is determined based on the determination level. It is.

However, in the above-described conventional example, the supply of the weft yarn is temporarily stopped, the yarn absence signal is sampled several times, and its maximum value B
Is determined as the maximum noise signal, and is fixed. Then, the thread presence signal is detected several times, and based on the minimum value A and the fixed maximum noise signal (the thread absence signal), the threshold level X is calculated as X = [(AB) /
4] + B Therefore, the determination level X cannot be obtained properly, and the detection accuracy cannot be improved. As described above, when the threshold level X is calculated from the minimum value A of the thread presence detection signal and the noise level (maximum value B) of the thread absence signal, when the minimum value A is low, the determination level X is also low, and the noise level is low. (Maximum value B) is too close to the determination level X, and there is a possibility that the noise level (Maximum value B) is determined as a detection signal.

Configuration of the Invention (Means for Solving the Problems) Therefore, in the present invention, an analog signal output from a weft detector is converted into a digital signal as a detection signal.
A weft in a shuttleless loom that inputs to a digital signal processing circuit having a digital signal identification function corresponding to the presence or absence of a weft, and compares the digital signal with a set reference level signal to determine the presence or absence of a weft inserted. In the detection method,
A detection signal from the weft detector is input to the digital signal processing circuit, and the presence / absence of a weft is determined by comparing an initial reference level signal with a detection signal of a weft detection time set in a predetermined machine rotation angle range. The initial reference level based on the average value of the maximum point of the detection signal of the weft detection time at a predetermined rotation during the machine operation and the average value of the maximum point of the noise detection signal at a time other than the weft detection time. After changing the signal, the reference level signal after the change is compared with the detection signal at the weft detection time to determine the presence or absence of a weft, and the change setting operation is repeated to sequentially change the reference level signal after the change. Changed settings.

(Operation) That is, by converting an analog signal output from the weft detector into a digital signal, the digital signal enabling setting control of setting of a reference level signal for identifying the presence or absence of a weft based on the input digital signal. A signal processing circuit identifies the detected converted digital signal.

The reference level signal and the detection signal at the weft detection time are compared to determine the presence or absence of a weft. Further, the average value of the maximum point of the detection signal of the weft detection time,
The reference level signal is changed and set based on the average value of the maximum points of the detection signal other than the weft detection time. Therefore, an appropriate reference level signal is obtained, and the detection accuracy of the presence or absence of the weft is improved.

(Embodiment) An embodiment in which the present invention is embodied in an air jet loom will be described below with reference to FIGS.

In this embodiment, the weft detector is composed of a light projecting element 3 and a light receiving element 4 which are opposed to each other with a guide hole 2a of a guide type weft detecting body 2 erected on the slay 1 interposed therebetween. The projected steady light is photoelectrically converted by the light receiving element 4 to detect the weft Y inserted into the guide hole row of the not-shown weft guide member together with air from the weft insertion main nozzle (not shown). The detection signal output from the hole receiving element 4 is amplified by an amplifier circuit 5 and an analog-digital conversion circuit (hereinafter, referred to as an analog-digital conversion circuit)
The signal is input to a digital signal processing circuit 7 through an A / D conversion circuit 6. The signal Sa1 output from the light receiving element 4 is an analog signal as shown in FIG. 2A, and the analog signal Sa1 is amplified to a signal Sa2 in an analog state as shown in FIG. 2B. The amplified analog signal Sa2 is converted into a digital signal Sd1 as shown in FIG.
The signal is input to the digital signal processing circuit 7.

The digital signal processing circuit 7 is a microprocessor or a digital signal processor. An initial reference level signal L1 value for identifying the presence or absence of a weft is input and set, and a digital signal processing program for the input digital signal is input and set in advance. I have. The setting of the initial reference level signal L1 is set to the greatest common divisor based on the value of the actual weft detection signal obtained from the experimental data under various conditions, as described in the related art section.

Now, with the operation of the loom, the digital signal processing circuit 7 receives the converted digital signal Sd1 and the initial reference level signal L1.
The values are compared within a predetermined machine rotation angle range [α, β] set as the weft detection timing, and as shown in FIG. 2 (c), the signal portion Sd (Y ), It is determined that weft is present. If the converted digital signal Sd value does not exceed the initial reference level signal L1 value, it is determined that there is no weft, and a machine stop signal is transmitted to the machine drive motor M. Therefore, the signal portion Sd (N) within the machine rotation angle range [α, β] is determined to be noise. Further, the digital signal processing circuit 7 determines that the signal portion Sd (Y) during the m rotations of the machine is the average μ of the population of m maximum points P (MAX) and the machine rotation angle range [α, β]. M of the maximum point p (max) of the outer signal part sd (n)
The average value ν of the population consisting of
, Change and set the initial reference level signal L1. In this process, both signal parts Sd (Y) and sd in the population
New maximum point data is added instead of the earliest maximum point data in (n), and a new average value is calculated and set. The converted digital signal Sd2 shown in FIG. 2D shifts to a lower level than the converted digital signal Sd1 of FIG. 2C, and is changed and set by the digital signal processing circuit 7 based on this. The reference level signal L2 value is lower than the initial reference level signal L1 value. That is, the reference level signal is appropriately changed and set according to the actual signal-to-noise ratio (S / N ratio), and it is possible to maintain a high weft detection capability according to the actual weft presence state. Of course, a similar response can be made to a change in the S / N ratio due to disturbance light or a yarn type, a change in photoelectric conversion performance due to fly fouling or a change with time.

Further, the digital signal processing circuit 7 outputs a display command to the display device 8 when there is a reference level signal fluctuation that is regarded as abnormal, and warns the weft insertion abnormality. Thereby, it is possible to cope with the detection abnormality.

The improvement of the weft detection capability and the abnormality alarm are performed by converting an analog signal output from the weft detector into a digital signal required as input data to a microprocessor or a digital signal processor having a high degree of control. In addition to the digital signal processing program as described above, for example, a waveform judgment program for judging the waveform of the weft presence detection signal portion Sd (Y) from the number of signal points equal to or larger than the reference level signal value is incorporated. It is also possible. Therefore, it is possible to relatively freely perform expansion and addition of functions by changing a program, such as automatic adjustment of the sensitivity of identifying the presence or absence of a weft, judgment and display of the cause of a detection abnormality, and also reduce variation in the weft detection performance between looms. .

The present invention is, of course, not limited to the above embodiment, but is also applicable to, for example, weft detection using modulated light as shown in FIG. The analog signal Sa′1 modulated as shown in FIG. 3 (a) is amplified as shown in FIG. 3 (b), and the amplified analog signal Sa′2
Undergo a detection process as shown in FIG. 3 (c). Then, the detected analog signal Sa'3 is converted into a digital signal Sd 'as shown in FIG. 3 (d), and the converted digital signal Sd' and the reference level signal L 'are converted into a digital signal as in the above embodiment. The comparison is made in the processing circuit.

In addition, the weft signal detected in the present invention can be easily input to a central control device or the like to analyze and accumulate the data.

Effect of the Invention As described in detail above, in the present invention, since the analog signal from the weft detector is converted into a digital signal required as input data to the digital signal processing circuit having a high degree of control, the presence or absence of the weft can be detected. It has an excellent effect that performance can be improved.

Further, in the present invention, an appropriate standard is determined based on the average value of the maximum points of the detection signals of the weft detection timing set in the predetermined machine rotation angle range and the average value of the maximum points of the detection signals other than the weft detection time. A level signal can be obtained, and the detection accuracy of the presence or absence of a weft can be improved.

Further, in the present invention, the presence / absence of a weft is determined by comparing an initial reference level signal with a detection signal of a weft detection time set in a predetermined machine rotation angle range, and the weft detection at a predetermined rotation during the machine operation is performed. The initial reference level signal is changed and set based on the average value of the maximum point of the timing detection signal and the average value of the maximum point of the noise detection signal at a time other than the weft detection time. For this reason, it is possible to maintain a high weft detection capability in accordance with the actual weft presence state even with respect to the S / N ratio displacement caused by disturbance light or yarn type, fluctuation of photoelectric conversion performance caused by fly fouling or change over time. It is possible.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing an embodiment embodying the present invention, and FIGS. 2 (a), (b), (c) and (d) are graphs showing a detection signal processing method. 3 (a),
(B), (c), and (d) are graphs each showing another example of the processing method of the detection signal. Light emitting element 3 and light receiving element 4, which constitute the weft detector, A / D
Conversion circuit 6, digital signal processing circuit 7, weft Y.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-161143 (JP, A) JP-A-58-208446 (JP, A) JP-A-57-161144 (JP, A)

Claims (1)

(57) [Claims] An analog signal output from a weft detector is converted into a digital signal as a detection signal, and is input to a digital signal processing circuit having a digital signal identification function corresponding to the presence or absence of a weft. In a weft detection method in a shuttleless loom that determines the presence or absence of a weft inserted by comparing with a set reference level signal, a detection signal from the weft detector is input to the digital signal processing circuit, and an initial reference A level signal is compared with a detection signal of a weft detection time set in a predetermined machine rotation angle range to determine the presence or absence of a weft, and the maximum point of the detection signal of the weft detection time at a predetermined rotation during the operation of the machine. The initial reference level signal is changed and set based on the average value of the noise detection signal and the average value of the maximum point of the noise detection signal at times other than the weft detection time, and thereafter, A weft detection method for a shuttleless loom in which a level signal and a detection signal at the weft detection time are compared to determine the presence or absence of a weft, and to repeat the change setting operation to sequentially change and set the changed reference level signal. .