JPH0766059B2 - Thread detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an improvement in a yarn detection method, and more specifically, to skillfully utilize an optical inverse-square law. The present invention relates to an epoch-making detection method capable of searching for the presence or absence of a thread in a road with surprisingly high accuracy,
This is a new technology that can be used for various textile machines such as weaving machines, twisting machines, and winders.

[Conventional technology and problems to be solved]

Conventionally, as a method for detecting an abnormality in a yarn feeding state in a textile device such as a loom, a twisting machine, and a winder, (1) a mechanical detection method using a dropper mechanism, (2) a piezoelectric element or a microswitch is used. A method such as an electric detection method using (3) a photoelectric detection method using a light emitting / receiving element has been put into practical use.

However, in the mechanical detection method and the electrical detection method of the above (1) and (2), the contact member must be brought into contact with the thread that is the object to be monitored, and thus the strength of the thread is inevitable. -There was a problem that it was unsuitable for searching thin yarns, highly stretchable yarns, or stationary yarns due to the constraint of tension.

On the other hand, regarding the photoelectric detection method of the above (3), there is a direct light receiving method that searches for the presence or absence of a yarn by whether or not there is an object that crosses the beam emitted from the light projecting element toward the light receiving element, and the light projecting method. There is a reflective light receiving system that projects light from the element to the yarn path and searches for the presence or absence of the yarn by increasing or decreasing the reflected light that returns from there, both of which have excellent high-speed response and are non-contact. Since there is an advantage that it can be applied to low-tension yarns and stretchable yarns as well, there are the following difficulties.

That is, the difficulty is that with respect to the former direct light receiving system,
This means that a large number of light emitting / receiving elements are required to search the entire width of the yarn path, and the circuit configuration must be complicated. Regarding the latter reflection / light receiving method, a pair of light emitting / receiving elements is used. It is possible to cover the entire width of the yarn path with a thin thread, and for a static thread that does not vibrate, the absolute amount of the received light is amplified and detected because the amount of reflected light from the yarn depending on the amount of light emitted is small. Due to the fact that the configuration must be adopted, amplification is inevitably performed by the DC coupling amplifying means, and as a result, the 0 point of the DC coupling amplifying means tends to shift due to temperature drift and the like, and the amount of light reflected by the yarn is small. In this case, it is impossible to distinguish whether the output shift is due to the amount of reflected light or due to drift. For this reason, it is necessary to add a special correction mechanism to the detection circuit, and eventually the entire circuit becomes complicated.

It is a technical object of the present invention to improve the search accuracy of a reflection-light receiving type photoelectric detection method which is rich in high-speed response and has a wide search width for one light emitting / receiving element.

[Means adopted to solve technical problems]

That is, the present invention utilizes the "law of inverse square of distance" in which the magnitude of the light quantity in the light-transmitting / receiving relationship is "inversely proportional to the square of the distance from the light source".
A description will be given with reference to FIG. 1 (schematic diagram) when L ₁ and L ₂ are used: The light emitting elements L ₁ and L having the same illumination output and arranged at different distances in the yarn path through which the yarn should pass. While illuminating from _{2 in} turn,
A light receiving element E receives the reflected light from each of the yarns by the illumination of the light projecting elements L ₁ and L ₂ , and the presence or absence of the yarn in the yarn path is searched by the level difference between the reflected light. , and the if there is a yarn in the yarn path, the light projecting element L ₁ and the law distance r ₁ is short for the distance inverse square than the distance r ₂ between the light projecting element L ₂ and the thread of the thread As a result, the level of the light reflected from the yarn by the illumination of the light projecting element L ₁ becomes higher than the level of the light reflected from the yarn by the illumination of the light projecting element L ₂ , so that the level difference between the two reflected light is constant. It appears larger than the reference value, and conversely, when there is no yarn in the yarn path, the level difference does not reach the reference value.

In the above description, the light projecting elements L ₁ and L ₂ are placed at different distances.
Although it mentions about the case where the
When L ₁ and L ₂ are arranged on the same circumference with the same distance from one point, it is also possible to use three or more light emitting elements L by changing the illumination output of the light emitting elements L ₁ and L _2. It is also possible to eliminate the "blindspot" on the equidistant line where the level difference of the reflected light does not occur by using ₁ · L ₂ · L ₃ ... L _n .

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the accompanying drawings.

FIG. 1 is a schematic diagram of the method of the present invention, FIG. 2 is a schematic diagram of an embodiment system for carrying out the method of the present invention, FIG. 3 is a timing chart diagram, and the signal lines listed in Example A are “threads”. The signal line enumerated in the “present signal” and the example B indicates the “no thread signal”. 3 (a) is an output waveform in the photoelectric output amplifier 3, FIG. 3 (b) is an output waveform in the differentiator 4, FIG. 3 (c) is an output waveform in the differential signal amplifier 5, and FIG. Shows the output waveform in the comparator 6, and FIG. 8E shows the output waveform in the retrigger 8.

In FIG. 2, reference numeral 1 denotes a weft guide ring, and the light projecting elements L ₁ and L ₂ and the light receiving element E having the same illumination output are arranged inward around the guide ring 1. Has been done. The object designated by the symbol Y in the inner space of the guide ring 1 is a weft. Further, the yarn path in this embodiment is set within a range (φ · χ · ψ · ω) in which the irradiation space formed by the light projecting element L ₁ and the irradiation space formed by the light projecting element L ₂ overlap, It is set to the area surrounded by (α, β, φ, χ, ω) or the area surrounded by (α, β, ψ) that does not include the equidistant line PP of L ₁ and L ₂ . (See Figure 1).

Reference numeral 2 indicates a switching circuit, which supplies DC electricity supplied from the power source P to the light projecting element L ₁ or L ₂ via the voltage regulators VR ₁ and VR ₂ instantaneously and alternately.

Indicated by reference numeral 3 is a photoelectric output amplifier that amplifies the photoelectric output signal of the light receiving element E that photoelectrically converts the reflected light,
Reference numeral 4 is a differentiator, 5 is a differential signal amplifier, 6 is a comparator, 7 is a value setting device, and 8 is a retrigger.

By the way, the illumination light sequentially and alternately emitted by the light projecting elements L ₁ and L ₂ is reflected by the yarn Y existing in the yarn path and is received by the light receiving element E.
The incident light quantity of the light receiving element E corresponding to L ₁ and L ₂ in this case is the optical distance inverse square law (B = 1 /
r ² : However, B is controlled by the illuminance and r is the distance from the light source. Now, suppose that in FIG. 1, the distance r between L ₂ and the thread Y is
_{If 2} is twice the distance r ₁ between L ₁ and the yarn Y, the brightness of L ₂ illuminating the yarn Y is 1 / l of the illumination of L _1.
4, the amount of reflected light received by the light receiving element E also has a large level difference. Therefore, the light receiving element E
The photoelectric output signal by means of appears as an amplitude waveform whose level changes depending on the distance between the light projecting elements L ₁ and L ₂ and the yarn Y (shown in column A (a) of FIG. 3). ,
When the yarn Y does not exist in the yarn path, the photoelectric output having an oscillating waveform is not generated (shown in the column B (a) of FIG. 3).

Next, this photoelectric output signal is amplified by the photoelectric output amplifier 3 and input to the differentiator 4, where it is differentiated and the level difference of the amplitude waveform is output as a quantitative differential value signal. In this embodiment, for convenience, only the case where the differential waveform is "positive" will be described (see column A (b) of FIG. 3).

This differential value signal is further input to the differential value signal amplifier 5, amplified to a required level, and sent to the comparator 6 (see column A (c) of FIG. 3). On the other hand, shiki value setter 7
From FIG. 3, a shiki value signal having a level corresponding to the preliminarily set shiki value is sent to the comparator 6 (A in FIG. 3).
(Indicated by a dotted line s in column B), the differential value signal and the squeeze value signal are compared in the comparator 6. And
When the value of the differential value signal is larger than the value of the shiki value signal, the "thread present signal" is output and input to the retrigger 8 (see column A (d) of Fig. 3), and conversely the differential value signal. When the value of is smaller than the value of the shiki value signal, the "thread absence abnormality signal" ab is output and input to the retrigger 8 (see column B (d) of FIG. 3). When the "no-thread signal" ab is continuously input to the retrigger 8 for a certain period of time or longer, the retrigger 8 outputs a stop signal st to stop the loom (third part). (See column B (e) of the figure). In the above embodiment, the switching time of the switching circuit 2 is set shorter than the stop signal generation standby time of the retrigger 8. in this case,
The shorter the switching time by the switching circuit 2, the higher the search time density, but there is no problem with the time width of about 1 mm / s to 10 mm / s.

FIG. 4 is an example of another detection system for carrying out the method of the present invention. In this embodiment, one of the three light projecting elements is used.
This shows the case of illuminating the yarn path by adjusting the light emitting amount of each piece, and the light emitting outputs of the light emitting elements L ₂ and L ₃ are the same, and the light emitting output of the light emitting element L ₁ is adjusted. It is set lower than the above L ₂ and L ₃ .

Now, in the embodiment system of FIG. 4, the light projecting element L ₁
Equidistance P ₁ -P ₁ and L _2, equidistant lines P ₃ -P ₃ with equidistance P ₂ -P _2, the light emitting element L ₂ and L ₃ between the light projecting element L ₁ and L ₃
Assuming that the yarn Y comes to the crossing point where the two cross each other, the light emitting output of the light emitting element L ₁ is lower than that of the other light emitting elements L ₂ and L _{3 in the} system of this embodiment. In the photoelectric output amplifier 3, the fluctuation of the received light amount level is as shown in the column A (a) of FIG. In the signal processing in this system example, as in the case of FIG. 2, the differential value signal output via the photoelectric output amplifier 3, the differentiator 4, and the differential value signal amplifier 5 is processed by the comparator 6 as a skew value. The retrigger 8 outputs a stop signal st when the output of the "thread-free signal" ab by the comparator 6 continues for a certain period of time or more. In this case, the switching time width of the light projecting elements L ₁ , L ₂ , L ₃ (one cycle of switching to L ₁ L ₂ L ₃ ) is set shorter than the width of the stop signal generation standby time of the retrigger 8. Needless to say.

FIG. 6 is an example of another weft detection system for carrying out the method of the present invention. In this example system, by using the distance inverse-square law can not search the existence of yarn region, i.e. the distance from the light projecting element L _1, the distance are equal equidistant line P from the light emitting element L ₂ It established a sub-light projecting element L ₃ on the extension of -P, leave supplementary illuminated toward the light receiving elements E along with the sub-light projecting element L ₃ to the line P-P, the sub-light projecting When the amount of light received by the light-receiving element E by the element L ₃ is drastically reduced from a certain reference value, "thread is present" on the equidistant line PP.
In addition, the method of the present invention is combined with a conventionally known direct light reception detection method. In the signal processing in this system example, the differential value signal output via the photoelectric output amplifier 3, the differentiator 4, and the differential value signal amplifier 5 is converted into a false value signal by the comparator 6 as in the case of FIG. It is assumed that the comparison is performed by a system, and the retrigger 8 outputs a stop signal st when the output of the “thread-free signal” ab by the comparator 6 continues for a certain time or longer.

[Effect of the present invention]

As described above with reference to the embodiments, in the method of the present invention, the means for illuminating the yarn path alternately from at least two light projecting elements is employed. A clear level difference is generated between the reflected light and the reflected light, which causes a clear change in the waveform of the photoelectric output signal generated by the light receiving element depending on the presence or absence of the yarn in the yarn path.

Therefore, according to the method of the present invention, the presence / absence of the yarn in the yarn path can be searched with high accuracy only by monitoring the photoelectric output signal from the light receiving element.

As described above, the method of the present invention, while inheriting the advantages of the conventional reflection / reception type yarn detection method, dramatically improves the yarn search sensitivity, and the cost for implementing the method is conventionally reduced. It can be said that the practical merit is almost the same as that of the photoelectric detection method described in 1.

[Brief description of drawings]

FIG. 1 is a schematic diagram of the method of the present invention, and FIG. 2 is a schematic view of a weft detection system when the method of the present invention is applied to a weft guide ring interposed between a weft storage device and a jet nozzle in a jet loom. FIG. 3 is a timing chart diagram of an embodiment system using two light emitting elements, FIG. 4 is a schematic view of an embodiment system using three light emitting elements, and FIG. 5 is an embodiment of FIG. FIG. 6 is a timing chart in the system, and FIG. 6 is a schematic diagram showing still another example of the weft detection system. L ₁ / L ₂ / L _{3 to} L _n …… Emitting element, E …… Receiving element, VR ₁・ V
R ₂ · VR ₃ ~VR _n ...... voltage regulator.

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Claims (3)

[Claims] 1. A yarn path through which a yarn passes is illuminated alternately from at least two or more light projecting elements (L ₁ , L ₂ ... L _n ) while the light projecting elements (L ₁ , L ₂ ) are sequentially illuminated. _Ln ) each reflected light from the yarn by the illumination is received by the light receiving element (E), and the presence or absence of the yarn is searched by the level difference between these reflected lights. Detection method. 2. The light quantity of at least one of the light projecting elements (L ₁ , L ₂ ... L _n ) is adjusted by adjusting any of the voltage regulators (VR ₁ , VR ₂ , VR ₃ ... VR _n ). According to claim 1,
Thread detection method. 3. The yarn detecting method according to claim 1, wherein at least one of the light projecting elements (L ₁ · L ₂ ... L _n ) is adjusted in amount of light by making the installation distance different.