JP2543654Y2 - Weft detection device for air jet loom - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Industrial application field) The present invention relates to a weft detecting device of an air jet loom, and particularly to an optical reflection type weft detecting device.

(Prior Art) An air jet loom is provided with a plurality of reeds having a weft guiding recess formed on the front surface thereof, and the weft is inserted by a weft insertion nozzle along a weft guiding groove in which the weft guiding recesses are arranged. There are those that fly and insert weft. Here, in order to detect whether or not the weft is inserted into the weft and reaches the anti-weft insertion side, a weft guide formed on a reed on the anti-weft insertion side as disclosed in Japanese Utility Model Application Laid-Open No. 62-11192. In some cases, a feeler is provided behind the groove. The feeler is provided with a light emitter and a light receiver facing the weft guide groove formed in front of the reed, and changes in the amount of received light due to the light from the light emitter being reflected by the weft and entering the light receiver. Is used to detect the presence or absence of a weft.

In the weft detecting device having the above configuration, even when the weft has not arrived, the external light such as the indoor illuminating light or the outdoor sunlight enters the light projector, so that the signal output from the feeler is not zero. For this reason, an appropriate value between the feeler signal value when there is no thread and the feeler signal value when there is a thread is set as a threshold, and the weft detection signal is generated only when the feeler signal is equal to or greater than the threshold. . However, if the feeler signal value when there is no thread is relatively large and the difference from the feeler signal value when there is a thread is small, the range for determining the presence or absence of the thread based on the threshold value becomes narrower, and the effect of noise entering the light receiver And there is a risk that erroneous detection of the weft may occur.

As means for solving this problem, Japanese Patent Laid-Open No.
As described in JP-A-71457, the signal value output by the feeler when there is no thread before weft insertion is stored and held by the sample hold circuit, and the signal value output by the feeler during weft insertion and the sample hold circuit are stored and held. The signal value is compared with the signal value, and the difference obtained by subtracting the signal value without the thread from the signal value at the time of weft insertion output by the feeler is output from the amplifier circuit to detect whether or not the feeler of the weft has arrived. There is something like that.

(Problem to be Solved by the Invention) However, in the above-described conventional weft detecting device, when the reed 2 on which the feeler is mounted is in a state where the warp is in an open state and the weft insertion is performed, as shown in FIG. Is different from the main spindle angle (right side in the drawing) and the main spindle angle B (left side in the figure) before beating and beating in the open state, and when wefting is performed, A is before wefting. (At the time of non-weft insertion)
More external light 10 than B enters the feeler 1. The reason for this is that in A, the light receiving unit 4 of the feeler 1 faces upward (toward the ceiling) and in B before weft insertion, the light receiving unit 4 of the feeler 1 faces downward (to the floor). Here, external light such as lighting or sunlight
Is incident toward the floor side from the ceiling-hanging side, so that when weft insertion is performed, more external light 10 is incident on A. In FIG. 4, reference numeral 3 denotes a light emitting unit.

Here, as shown in FIG. 5, the sample hold signal is emitted at a main shaft angle of 40 ° to 70 ° before beating and after beating, ie, when the weft is inserted, the feeler 1 Are output when the spindle angle is 200 ° to 280 °, the base signal of the sample-and-hold signal output by the feeler 1 during non-weft insertion when there is no thread (there is always a base signal because there is no thread). More signals are output from the feeler 1 at the time of weft insertion than external light is incident, and the base signal without the thread is also larger than the base signal of the sample hold signal.

As a result, even if both signals are compared with great effort, the base signals of both signals are different, and the base signal at the time of weft insertion is larger, so it did not arrive when the weft should arrive at the feeler due to poor weft insertion. Nevertheless, there is a risk of erroneously detecting that there is a weft.

This invention has been made in view of the above points, and has as its object to improve the reliability of weft detection.

[Structure of device]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a light emitting device and a light receiving device which are provided on a non-weft insertion side and are arranged toward a weft guide groove formed in front of a reed. An optical feeler for detecting the presence of a weft yarn, sample-and-hold means for storing and holding a first signal value output by the feeler during non-weft insertion, and output of the first signal value and the feeler during weft insertion. And a comparing means for comparing the second signal value with the second signal value and outputting a difference between the first signal value and the base signal value when the weft does not reach the feeler at the second signal value. And means for correcting the first signal value and the first signal value to have substantially the same level.

(Operation) According to the above configuration, the value when the weft does not reach the feeler of the signal output by the feeler during weft insertion (base signal) and the signal output by the feeler during non-weft insertion (base signal) are: Approximately the same level is obtained by the correction means. Therefore, it is possible to prevent the output of a signal indicating the presence of a weft even though the weft does not reach the feeler when it should arrive at the time of weft insertion.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In the figure, an output signal E of the feeler 1 is input to an input terminal a of a switch 6 and a (+) input terminal of a comparator 7 as comparison means. The switch 6 has an input terminal b and an output terminal c. A signal T of the spindle rotation angle detected by the spindle angle detector 5 is input to the input terminal b. The output terminal c of the switch 6 is connected to the input terminal of the storage device 8. Here, the switch 6 is turned on only when the signal T from the spindle angle detector 5 is a signal of the spindle angle B (40 ° to 70 ° shown in FIG. 5) before weft insertion (non-weft insertion). Output signal E of feeler 1
Is set to be output to the storage unit 8. The output terminal of the storage device 8 is connected to the input terminal of the amplifier 9 as a correction means. The amplifier 9 amplifies the signal value input to the input terminal and inputs the amplified signal value to the (−) input terminal of the comparator 7. The comparator 7 outputs the difference between the signals input to the (+) and (-) input terminals as the feeler signal F from the output terminal. In this embodiment, the switch 6 and the storage unit 8 constitute the above-mentioned sample and hold means.

Next, the operation of this embodiment configured as described above will be described first.
This will be described with reference to FIGS.

When the main shaft rotation angle shown in FIG. 5 is 0 °, beating is completed, and when it is between 40 ° and 70 °, the reed 2 is at the angle shown on the left side of FIG. 4, and a sample hold signal is issued. That is, when the main shaft rotation angle signal T _{1 at} this time is input to the input terminal b of the switch 6, the input signal value E _1, which is the first signal value from the feeler _1, is output from the output terminal c to the storage device 8. Entered and stored. It is substantially flat since the input signal value E ₁ in this case is when there not weft insertion at a relatively low level as shown in Figure 2.

Next, when the main shaft rotation angle is close to 200 ° and the reed 2 has the angle shown on the right side of FIG. 4 and the weft has not reached the feeler 1, the input signal value E ₃ of the second signal from the feeler 1 (E ₃ ( The base signal is input to the comparator 7. For input signal values E ₃ at this time to enter many external light to the light receiving unit 4, a relatively high level as shown in Figure 2.

Here, the amplifier 9 amplifies the first signal value E ₁ (base signal) input to the storage unit 8, and amplifies the second signal value E _3.
(Signal value E ₄ ) after being matched with (base signal),
(-) Input terminal, and since the two base signals match, the difference between them is almost zero. On the other hand, when the spindle rotation angle is 200
When the weft insertion is performed between ° to 280 °, feeler 1 second signal values weft rapidly rising than the value E ₃ of the time has not been reached feeler 1 detects the weft yarn, high levels and it outputs a signal value E ₂ of the comparator 7 to the (+) input terminal.
The comparator 7 amplifies a high level signal value E ₂ and the first signal value E ₁ when the second weft a signal value input reaches the feeler 1 second signal value E ₃ amplifies the difference between the value E _4-matched (base signal), and outputs it as feeler signal F shown in Figure 3.

According to this embodiment, since the base voltage of the sample hold signal and the base voltage of the weft detection signal are matched, the difference between the base voltage of the weft detection signal and the feeler detection voltage at the time of weft insertion can be increased. Erroneous detection can be prevented.

[Effect of the invention]

As described above, according to the present invention, the value of the base voltage of the second signal value at the time of weft insertion and the first signal value, which is the base voltage at the time of non-weft insertion, are set to be substantially the same level. Since the correcting means is provided, erroneous detection of the weft can be prevented, the reliability of the weft detecting device can be improved, and the operation thereof can be stabilized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a graph showing signal values before correction, FIG. 3 is a graph showing feeler signal values after correction, and FIG. FIG. 5 is a timing chart showing the rotation angle of the main shaft and the signal output timing. 1 ... feeler 2 ... reed 6,8 ... sample holding means (6 ... switch, 8 ...)
... Memory 7) Comparison means (comparator) 9 Correction means (amplifier)

Claims (1)

(57) [Scope of request for utility model registration] 1. An optical feeler provided on a side opposite to a weft insertion side and arranged to face a weft guide groove formed in front of a reed and detecting the presence of a weft by a light emitter and a light receiver; Sample-and-hold means for storing and holding a first signal value output during non-weft insertion; comparing the first signal value with a second signal value output by the feeler during weft insertion to output the difference; A weft detection device comprising: a base signal value when the weft does not reach the feeler in the second signal value and the first signal value are made to have substantially the same level. A weft detecting device for an air-jet loom, comprising: