JPH073584A - Weft-detecting device of loom - Google Patents

Abstract

PURPOSE:To enable to exactly judge the presence or absence of a weft without disposing a light-reflecting member in a welt guide groove. CONSTITUTION:The weft-detecting device contains a light-projecting means 20 for projecting light containing plural wavelength components toward a weft 14, plural light-receiving means 22, 23 for receiving the light reflected from the weft and having sensitivity characteristics different in peak wavelengths, respectively, and a judging means 18 for judging the presence or absence of the weft on the basis of the outputted signal of the light-receiving means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weft detecting device for a loom, which detects the presence or absence of a weft on the basis of a light ray incident on a light receiving element.

[0002]

2. Description of the Related Art In general, a weft detecting device using a photoelectric weft detector projects light toward a weft, receives the reflected light by a photodetector, and outputs the weft based on an output signal of the photodetector. The presence or absence of is determined. The determination of the presence or absence of the weft yarn is based on the fact that the voltage level of the output signal of the light receiver is different when the weft yarn is present in front of the light receiver and when it is not present. However, in this type of photoelectric weft detection device, if the weft and the reed wing that is the background of the weft have similar colors, the output signal of the photoreceiver differs (level) when the weft is present and when it is not present. difference)
Does not appear, and it is mistakenly determined that there is no yarn, and as a result, the loom is uselessly stopped.

In order to solve the above problems, there has been proposed a weft detecting device in which two light receivers are arranged for one light projector and a reflecting member having a different reflectance is arranged as a background member for each light receiver. (Japanese Utility Model Publication No. 3-18538). However, in this weft detecting device, since the location of the reflecting member is in the weft guide groove of the reed, the reflecting member itself becomes an obstacle to weft insertion, which may cause weft insertion failure.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to accurately determine the presence or absence of a weft without disposing a reflecting member in the weft guide groove.

[0005]

A weft detecting device of the present invention comprises a light projecting means for projecting light including a plurality of wavelength components toward a weft and a plurality of light receiving means for receiving a reflected light beam from the weft. It is characterized in that it includes a plurality of light receiving means having different peak wavelengths of sensitivity characteristics, and a judging means for judging the presence or absence of the weft based on the output signals of these light receiving means.

Since the peak wavelengths of the sensitivity characteristics of the light receiving means are different from each other, the level difference between the output signals of the light receiving means when the weft is present and when the weft is not present is different for each light receiving means. By utilizing such a level difference, in the determination means, for example, by comparing a value obtained by adding the output signals of the light receiving means with a threshold value or by comparing each output signal of the light receiving means with the threshold value, The presence or absence of can be determined.

Even if the level difference between the output signals of one light receiving means is not a value sufficient to accurately determine the presence or absence of the weft,
The level difference between the output signals of the other light receiving means becomes a value sufficient to accurately determine the presence or absence of the weft.

As described above, according to the present invention, since a plurality of light receiving means having different peak wavelengths of the sensitivity characteristic are used, the difference in the voltage level which is important for determining the presence or absence of the weft is different for each light receiving means. As a result, the presence or absence of the weft can be accurately determined without disposing the reflecting member in the weft guide groove.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, a weft detecting device 10 is constructed as a device for detecting a weft 14 flying on a flight path formed by a plurality of reeds 12. The weft detection device 10 includes a reflective feeler head 16 and a determination circuit 18 that determines the presence or absence of a weft based on the output signal of the feeler head.

The feeler head 16 is a reflective feeler head and is attached to a reed or the like. The feeler head 16 includes a light projector 20 for directing and projecting a white light beam toward the weft yarn 14, a plurality of light receivers 22 for receiving reflected light from the weft yarn 14 and the reed wing 12 which is the background thereof,
24 and.

The light receivers 22 and 24 have sensitivity characteristics in which the peak wavelengths of the sensitivity characteristics are different from each other. Waveforms of the sensitivity characteristics of the light receivers 22 and 24 and their peak wavelengths λ1 and λ2
Is shown in FIG. Such light receivers 22 and 24 can be configured by using light receiving elements whose sensitivity characteristics have different peak wavelengths for each light receiver, and an optical filter having light passing characteristics different for each light receiver. It can also be configured by using a light receiving element that receives light that has passed through the filter.

The determination circuit 18 includes detection circuits 26 and 28 provided for each of the light receivers 22 and 24, and an AND circuit 30 that generates a logical product signal of output signals of both detection circuits. Each detection circuit 26, 28 compares the voltage level of the output signal from the corresponding photodetector 22, 24 with a threshold value,
Determine the presence or absence of wefts.

The determinations in the detection circuits 26 and 28 differ depending on the voltage level difference (level difference) when the weft yarn is present and when the weft yarn is not present.
The truth value "1" indicating the existence of the weft may be generated when the voltage level of the output signal from 24 is equal to or higher than the threshold value, and the truth value "0" may be output at other times. The truth value "0" indicating the existence of the weft thread may be generated when the voltage level of the output signals from 22, 24 is equal to or higher than the threshold value, and the truth value "1" may be output at other times.

In the embodiment shown in FIG. 2, the truth value "1" is generated when the weft is not present. Therefore, one of the detection circuits 26 and 28 has the truth value of “with weft”.
When the signal of 0 "is output, the AND circuit 30 outputs a signal of the truth value" 0 "of" with weft ", and outputs a signal of the truth value" 1 "of" without weft "in other cases.

In the weft detecting device 10, the amount of light incident on each of the light receivers 22 and 24 (the amount of light reflected from the reed wing) when no weft is present is distributed as shown by the chain line 32 in FIG. 4, and the weft is present. When the amount of light incident on each of the light receivers 22 and 24 (the amount of light reflected from the weft) is distributed as shown by the solid line 34 in FIG. 4, the peak of the sensitivity characteristic is obtained when the weft is present and when it is not present. The amount of light incident on the light receiver 22 having the wavelength λ1 causes a small difference of ΔL1, whereas the amount of light incident on the light receiver 24 having the peak wavelength λ2 of the sensitivity characteristic causes a large difference of ΔL2.

Therefore, according to the weft detecting device 10, even if the level difference between the output signals of one of the light receivers 22 and 24 is an insufficient value for accurately determining the presence or absence of the weft, the other light receiver is provided. Since the level difference between the output signals of 24 or 22 becomes a value sufficient to accurately determine the presence or absence of the weft, the detection circuit 28 or 26 corresponding to the other photodetector 24 or 22.
Always outputs a "thread present" signal if a weft exists, and as a result, the presence or absence of the weft can be accurately determined without disposing the reflecting member in the weft guide groove.

This is because even if the weft and the reed wing that is the background of the weft have similar colors, since they are not the same material, the degree of light absorption is different, and if a certain wavelength is concerned, This is because even if the degree of light absorption is similar, the degree of light absorption is always different in other wavelength regions.

In the weft detecting device 10, the projector 20
Does not necessarily have to generate white light as long as it generates light containing a wavelength component received by both light receivers 22 and 24, and includes, for example, a light beam of wavelength λ1 and a light beam of wavelength λ2. It may be a light source that generates light rays. Further, the determining circuit may be configured by an adding circuit that adds the output signals of both the light receivers 22 and 24 and a detecting circuit that compares the output signals of the adding circuits with a threshold value and determines the presence or absence of the weft.

Referring to FIG. 5, the weft detecting device 40 is
The reflection type feeler head 42 is provided with light emitters 44 and 46 for each of the light receivers 22 and 24, a decision circuit 48 adds an output signal of both light receivers 22 and 24, and an output of the adder circuit. It is different from the weft detecting device 10 in that it includes a detection circuit 52 that compares the signal with a threshold value and determines the presence or absence of the weft.

The light projectors 44 and 46 project light rays containing the components of wavelengths λ1 and λ2, which can be received by the light receivers 22 and 24, respectively. Such projectors 44 and 46 can be configured by using, for example, a light emitting element and an optical filter that passes a light ray of a specific wavelength component among the light rays from the light emitting element, or a specific light emitting element. It can be configured by using a monochromatic light source such as a laser oscillator that generates only light rays of wavelength components.

Also in the weft detecting device 40, both the light receivers 22 and 24 are detected when the weft is present and when it is not present.
The amount of incident light of wavelength .lambda.1 to .DELTA.L1 causes a difference of .DELTA.L1, while the amount of incident light of wavelength .lambda.2 causes a difference of .DELTA.L2. Therefore, even if the level difference between the output signals of one of the light receivers 22 and 24 is insufficient to accurately determine the presence or absence of the weft, the level difference between the output signals of the other light receiver 24 or 22 is equal to the level of the weft yarn. Since it will be a value sufficient to accurately determine the presence or absence of
Adder circuit 50 for adding the output signals of both light receivers 22 and 24
The level difference between the output signals of 1 and 2 becomes a value sufficient to accurately determine the presence or absence of the weft, and as a result, the detection circuit 52 outputs the "yarn present" signal whenever the weft exists.

In the weft detecting device 40, the photodetectors 44 and 46 that generate a white light beam may be used, and the judging circuit 18 shown in FIG. Further, a multiplying circuit may be used instead of the adding circuit 50. In both of the weft detecting devices 10 and 40,
You may use three or more light receivers.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a weft detection device of the present invention.

FIG. 2 is a block diagram showing an embodiment of an electric circuit of the weft detection device of FIG.

FIG. 3 is a diagram showing an example of a sensitivity characteristic waveform of a light receiver.

FIG. 4 is a diagram showing an example of distribution characteristics of wavelength components of a light beam incident on a light receiver.

FIG. 5 is a block diagram of an electric circuit showing another embodiment of the weft detection device of the present invention.

[Explanation of symbols]

 10,40 Weft detecting device 12 Reed wing 14 Weft 20,44,46 Projector 22,24 Light receiver

Claims (1)

[Claims] 1. A plurality of light receiving means comprising a light projecting means for projecting light including a plurality of wavelength components received by the light receiving element toward a weft, and the light receiving element for receiving a reflected light beam from the weft. A weft detection device for a loom, comprising: a plurality of light receiving means having mutually different peak wavelengths of sensitivity characteristics, and a determination means for determining the presence or absence of a weft based on the output signals of these light receiving means.