US3258824A - Apparatus for checking of travelling yarn in textile machinery - Google Patents

Apparatus for checking of travelling yarn in textile machinery Download PDF

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US3258824A
US3258824A US398663A US39866364A US3258824A US 3258824 A US3258824 A US 3258824A US 398663 A US398663 A US 398663A US 39866364 A US39866364 A US 39866364A US 3258824 A US3258824 A US 3258824A
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yarn
voltage
amplifier
circuit
transistor
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Gith Walter
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H63/00—Warning or safety devices, e.g. automatic fault detectors, stop-motions ; Quality control of the package
    • B65H63/06—Warning or safety devices, e.g. automatic fault detectors, stop-motions ; Quality control of the package responsive to presence of irregularities in running material, e.g. for severing the material at irregularities ; Control of the correct working of the yarn cleaner
    • B65H63/062—Electronic slub detector
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H63/00—Warning or safety devices, e.g. automatic fault detectors, stop-motions ; Quality control of the package
    • B65H63/06—Warning or safety devices, e.g. automatic fault detectors, stop-motions ; Quality control of the package responsive to presence of irregularities in running material, e.g. for severing the material at irregularities ; Control of the correct working of the yarn cleaner
    • B65H63/062—Electronic slub detector
    • B65H63/065—Electronic slub detector using photo-electric sensing means, i.e. the defect signal is a variation of light energy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2701/00—Handled material; Storage means
    • B65H2701/30—Handled filamentary material
    • B65H2701/31—Textiles threads or artificial strands of filaments

Definitions

  • My invention relates to apparatus for checking travelling yarn in textile machine for slubs, doubling or the like I faults.
  • the yarn being processed in a textile fabricating machine must be supervised for detecting the occurrence of slubs, or such faults as double or multiple threads as may result from knotting operations. It has been proposed to employ for such purposes a measuring device which superimposes upon an electrical base voltage a fault-responsive pulse for releasing a protective device which prevents the further processing of the faulty yarn.
  • the base parameter value upon which the electrical pulses are superimposed may also be constituted by the electrical intensity, frequency or other parameter.
  • the base value itself may possess any magnitude and hence may also be equal to zero, for example, in which case the faultresponsive measuring or sensing device is merely required to produce pulses.
  • the base value may also have a magnitude departing from zero so that, for example, during normal yarn-processing operation, a constant output value is furnished from the sensing or measuring device and the occurrence of slubs, multiple threads or the like results in the superposition of larger or smaller measuring pulses upon the normally constant base value of the output, these signals then being employed for releasing the above-mentioned protective device which prevents the further processing of the yarn.
  • the supervision of the travelling yarn is effected in such a manner that differences in cross section, diameter, or volume of the yarn as are caused by a slub or by multiple threads are sensed by a measuring member, and the measuring value corresponding to the change in yarn dimension is amplified through a differentiating circuit before being supplied to the protector device, such as a device which severs the yarn.
  • the protector device such as a device which severs the yarn.
  • the invention is based upon the recognition that a satisfactory checking of travelling yarn on the basis of the differentiation is not feasible,
  • Shown at a, b, c, d and e in FIG. 1 are respectively different shapes of a slub in a thread of yarn (shown schematically).
  • the graph immediately below the schematic representation of the slubs shows the transverse cross-sectional dimension (on the ordinate) versus the length (on the abscissa) of the slub.
  • the illustrated slubs and cross sections are so chosen that all of the slubs have the same maximum cross-sectional dimension.
  • the third graph in FIG.1 shows the voltages on the ordinate (versus length on the abscissa) obtained by differentiation and hence, the corresponding rate of change, with reference to the cross-sectional graphs shown above the respective voltage diagrams.
  • this result is achieved by providing the yarn checking apparatus with a yarn sensing transducer which issues electrical signal pulses in response to the slubs and other faults to be detected, and with a direct-current amplifier in the input circuit of which the signal pulses are superimposed upon a fundamental operating voltage, while the output circuit of the amplifier is connected with an electrically actuable device for stopping the yarn processing operation in response to the signal pulses.
  • the amplifier is provided with regulating circuit means, preferably a negative feedback circuit which maintains the voltage of the amplifier output circuit substantially constant relative to changes of the fundamental component of the input voltage, so that the controlled device is actuated only in response to the yarn-fault signals independently of changes in fundamental voltage.
  • the device for stopping the yarn processing operation may serve to block the winding operation of a winding machine for example, or it may prevent the knotter of such a Winding machine from performing the knotting operation.
  • the device may also effect severing of the yarn by tearing or cutting it, or it may serve to block the further travel of the yarn by arresting it.
  • the apparatus according to the invention requires the provision of a direct-current amplifier which forms a genuine difference with respect to the cross section, diameter or volume of the yarn. Such a difference formation is independent of shape as well as time. Consequently, an apparatus according to the invention is suitable for operation with different travelling speeds of the yarn.
  • differentiating measuring equipment due to the fact that the measurement or the change in cross section is dependent on time, the difficulty of providing definite measuring or sensing results arises even in the cases during operation when the yarn travel speed is only very slight. For example, it has been virtually infeasible with the conventional differentiating equipment to obtain satisfactory results during the starting-up period of a winding station.
  • an apparatus according to the present invention secures satisfactory checking results not only during the gradual acceleration of a winding station up to its normal operating speed, but also permits a sensing operation with the yarn at standstill.
  • a direct-current amplifier to be employed for difference formation in apparatus according to the invention generally exhibits the disadvantage that it uniformly amplifies not only the signal pulses superimposed upon the base or fundamental voltage or input current, but also any fluctuations or changes of the input fundamental parameter. Such fluctuations may occur, for example, as a result of fluctuations in feeder voltage or due to changes in temperature.
  • the sensing member which produces the fault-responsive signal pulses consists of a photoelectric cell, different illumination intensities, stemming for example from different brightness of the light sources employed for illuminating the photoelectric cells, may also have the effect of changing the normal input value of the voltage or current supplied to the input circuit of the amplifier.
  • the electrical signal pulses are produced with the aid of a capacitive sensing device such as a capacitor, then slight changes in the humidity content of the yarn or of the ambient air may cause changes in the fundamental input parameter value of the amplifier.
  • a feedback regulation is preferably effected in such a manner that only a portion of the amplifier output voltage which is above an adjustable limit value, is series opposed to the voltage proportional to the fundamental input voltage.
  • a Zener diode is connected into the feedback circuit for example.
  • a Zener diode acts as a voltage limiter or regulator.
  • FIG. 1 shows the group of explanatory diagrams discussed in the foregoing.
  • FIG. 2 is a schematic circuit diagram of an apparatus embodying the invention by way of example.
  • FIG. 2a shows a sensor and severing device applicable in the apparatus according to FIG. 2.
  • FIG. 2b shows a modified embodiment of a sensor also applicable in an apparatus otherwise corresponding to FIG. 2.
  • FIG. 3 is an explanatory graph relating to the performance of apparatus according to FIG. 2.
  • FIG. 4 is a circuit diagram of a bridge-typenetwork of two cooperating sensors applicable in apparatus otherwise corresponding to FIG. 2.
  • FIG. 5 shows the circuit diagram of the modified severing device applicable in apparatus according to FIG. 2.
  • FIG. 6 is a schematic circuit diagram of another apparatus also embodying the invention.
  • FIG. 7 illustrates schematically a further embodiment of apparatus according to the invention.
  • FIG. 8 is an explanatory diagram relating to the apparatus according to FIG. 7.
  • the illustrated apparatus comprises a sensing device whose sensor 101 consists of a photoelectric cell, such as a silicon diode, which generates a voltage in dependence upon the amount of illumination issuing from a light source 101'.
  • the generated voltage of the photocell 101 remains constant, but when the yarn has a slub or other cross-sectional irregularity, the shadow travelling over the cell surface varies accordingly so that the generated voltage likewise changes.
  • the apparatus is further provided with a severing device which, in the embodiment according to FIG. 2a, comprises a normally inactive cutter which, when actuated by an electromagnet 100, will cut the yarn.
  • a photocell 101 is connected at its terminals L, K in a potentiometer circuit as shown in FIG. 2, so that the volt-age generated in the cell 101 varies in response to the passage of a slub.
  • the resulting voltage pulses are amplified in a direct-current amplifier which energizes the magnet 100 and thus operates the cutter 100.
  • the amplifier comprises four amplifying stages with respective transistors 10 2, 103, 104-, and a regulating stage with a transistor 106.
  • the transistor 102 operates in grounded emitter configuration and thus has a high input resistance.
  • the next following stages 103 to 105 are galvanically coupled in cascade. All transistors 102 to 106 are connected between the negative terminal A and the positive terminal B of a direct-voltage source, the positive terminal B being grounded.
  • the cutter control magnet or relay 100 is series connected in the collector circuit of the transistor 105 in the output stage.
  • This output circuit also comprises a series-connected diode 109 which serves as a threshold member and thus imparts to the amplifier stage of transistor 105 a corresponding switching characteristic.
  • Similar threshold valves 107 and 108 are connected in the emitter circuits of the respective transistors 103 and 104, the diode 108 for transistor 104 being additionally operative with respect to the transistor 105.
  • the transistors 103, 104 and 105 have a common adjustable emitter resistor 110 which has a very low-ohmic value in comparison with the other resistors. By virtue of the negative feedback coupling still to be described, the resistor 110 permits controlling the amplifying gain or sensitivity of the amplifier.
  • the collector circuits of transistors 102, 103 and 104 contain respective resistors 111, 112 and 113. In analogy to the gain-control resistor 110, a resistor 114 is connected in the emitter circuit 102 and an adjustable potentiometer rheostat 115 is connected in the emitter circuit of transistor 106.
  • the change in output signal causes the transistor 102 to be turned on in a manner more fully described hereinafter.
  • a current will now flow from negative terminal A through the resistor 111, transistor 102 and resistor 114 to the positive terminal B. Due to this current flow, the negative potential at the point E in the emitter circuit of transistor 102 is raised to a potential determined by the resistance magnitudes of resistances 111 and 114, with the result of turning the transistor 103 on. Now a current will flow from terminal A through resistor 112, transistor 103, threshold diode 106 and resistor 110 to terminal B.
  • a circuit point F between transistors 103 and 104 which, as long as transistor 103 is turned 011, has approximately the same negative potential as the terminal A, now assumes, due to the conducting condition of transistor 103, a more positive potential which nearly corresponds to that of the negative terminal B. This has the effect of blocking the transistor 104. Consequently, the current which, when transistor 104 is turned on, will flow from terminal A through resistor 113, point G, transistor 104, threshold diode 108 and resistor 110 to terminal B, is now interrupted. This causes the negative potential at point G to be raised considerably so that the transistor 105 is turned on and passes current through the cutter coil 100. To the extent described so far, the amplifier circuit is known per se.
  • the voltage normally occurring at the collector point D of transistor 105 and corresponding to the output voltage of the amplifier is kept constant even if the fundamental or base voltage which is impressed across the input terminals K, L and which determines the working or zero point of the amplifier, should change.
  • the voltage at point D is to be constant only with respect to changes of the input fundamental voltage, but not with respect to the signal pulses which result from slubs and other yarn faults and which are superimposed upon the voltage across the input terminals K, L.
  • the changes in fundamental input voltage may stem from changes in temperature or other effects acting upon the amplifier as well as upon gradual changes in brightness of the illumination produced by the light source 101' (FIG. 2) or also by the obscuring of the photocell 101 due to the gradual deposition of dust thereon. Any such changes in fundamental input voltage differ from the superimposed signal pulses in that changes of the fundamental voltage occur at a relatively slow rate.
  • the constancy of the amplifier output voltage at point D with respect to such slow changes in fundamental input voltage between the terminals K, L is achieved by virtue of a regulating feedback circuit which commences at point D between the cutter control coil 100 and the transistor 105.
  • This feedback circuit has the purpose of furnishing a voltage proportional to the output voltage at point D, and placing this feedback voltage in bucking relation to the fundamental input voltage impressed in the input terminals K, L. It is particularly advantageous if the entire voltage proportional to the output voltage at point D is not thus applied in opposition to the fundamental input voltage, but if only a share of the output voltage at point D is thus applied, this share having a value above an adjusted limit magnitude.
  • the feedback circuit is provided with a Zener diode 116.
  • the above-mentioned share of voltage having a value above the limit determined by the Zener diode 116, is supplied in series-opposition to the fundamental input voltage through an electrical storage component, this component being constituted by a capacitor 118 in the illustrated embodiment.
  • the regulating feedback voltage is preferably applied to the input circuit of the amplifier through an auxiliary amplifying stage constituted by the above-mentioned transistor 106 and the potentiometer rheostat 115.
  • a control current flows through the base-emitter path of the transistor I106 and the rheostat 115.
  • the transistor 106 like the transistor 102, is operated in grounded emitter configuration so that it also possesses a high input resistance. Furthermore the auxiliary amplifier stage of transistor 106 constitutes an impedance matching transformer because the load resistance of rheostat 115 in the emitter circuit of transistor 106 is low ohmic.
  • the transistor 2106 conducts more or less current from terminal A through the collector and emitter of transistor 106 and through the rheostat 115 to the terminal B.
  • This current produces in rheostat 115 a voltage drop of which a portion is tapped off and is connected in seriesopposed relation to the voltage of the photocell 101 at input terminal K.
  • the negative voltage tapped ofi the rheostate 1'15 always adjust itself automatically so that the above-presumed voltage of minus 18 volts at point D remains preserved.
  • the voltage of the photoelement 101 slowly decreases due to the deposition of dust. Then the base of transistor 102 receives a more negative bias voltage, and this transistor then permits a higher current to pass through the resistors 111 and 114. This also increases the current passing through the transistor 103, which in turn reduces the forward current passing through the transistor 104, so that the current passing through transistor 105 is increased. This effects a gradual reduction of the voltage at point D. Consequently a slowly increasing shading of or drop in illumination at the sensor cell 101 causes a corresponding gradual decline of the voltage at point D.
  • Zener diode 1-16 Since the Zener diode 1-16 always enfonces a constant voltage drop, a decline of the voltage at point D from minus 18 volts to minus 17 volts, for example, has the effect of reducing the voltage at point H from minus 3 to minus 2 volts.
  • the reduced voltage of point H causes a reduced control current to flow through the emitter of the transistor 106 so that voltage drop of the rheostat also becomes lower.
  • the correspondingly lower feedback voltage at input terminal K is now in series opposition to the lower voltage of the slightly darkened cell 101.
  • the regulating feedback is so rated that the voltage at input terminal K is reduced by the same amount by which the voltage of the photocell 101 has been increased. Consequently, the transistor 102 is controlled for the same state of conductance as existed prior to the occurrence of the slight shading of the cell 101, so that the other transistors 103, 104, 105 also operate under the original control conditions, and the point D is regulated to the original value of minus 18 volts.
  • the above described, very effective regulating feedback comp-rising the Zener diode 116 operates with delay due to the capacitor 118.
  • the delaying time can be adapted to the requirements of the particular application by employing a capacitor 118 of corresponding capacitance value.
  • the operating voltage of the first amplifier stage comprising the transistor 102 is stabilized by another Zener diode 1 19.
  • the point M in the collector circuit of transistor 102 is always maintained at a predetermined maximum voltage, for example minus volts. If this voltage, for example due to increased blocking of transistor 102, is increased to a higher value, then the excess voltage would be shunted off through the Zener diode 119.
  • the embodiment shown in FIG. 2 is further provided with two capacitors 120 and 121 which prevent the occurrence of high-frequency oscillations in the amplifier.
  • a resistor 122 serves for determining the operating point of the threshold diodes 108 and 109.
  • the switch 130 When the switch 130 is opened, the capacitor 118 cannot be charged, nor can the capacitor 118 discharge through the transistor 106. Furthermore, under these conditions, the transistor 106 cannot receive a regulating pulse from point D.
  • the operation of switch 130 is important for immediately regaining the original regulating condition of the direct-current amplifier in the event of yarn interruption.
  • the embodiment shown in FIG. 2 is provided with a sensing member constituted by a photoelectric cell which furnishes voltage pulses when responding to the passage of slubs, double threads or similar yarn faults. While this photocell is assumed to be of the voltage-generating type, it will be understood that it may also consist of a resistance diode which varies its ohmic resistance in accordance with changes in illumination.
  • Such a photocell has normally a given resistance and is normally supplied with a given voltage so that the current passing through the cell produces a voltage drop which constitutes the above-mentioned fundamental input value of the amplifier, the cell resistance and consequently the output voltage being changed in response to the presence of slubs or other yarn faults so that the resulting changes in voltage drop are composed of the fundamental magnitude and a superimposed pulse voltage.
  • the fault-responsive sensor in the apparatus according to the invention may operate on a different principle.
  • a capacitive sensing or measuring member may be used.
  • FIG. 2b Such an embodiment is illustrated in FIG. 2b.
  • the yarn Y travels between the two electrode plates 90 and 91 of a capacitor which is connected in a bridge circuit 92 normally balanced to provide no output voltage, or a given constant output voltage through a rectifier 94 to the input terminals L, K of the amplifier.
  • the passage of the slub or other yarn fault through the capacitive sensor unbalances the bridge network and thus causes a pulse voltage to be applied to terminals L, K.
  • the humidity content of the yarn and of the ambient air affects the measuring result when using a capacitive sensor.
  • the dielectric constant of water is and that of textile threads is about 2 to 6. Consequently, even slight fluctuations in humidity have a considerable effect upon the result of capacitive measurements. For this reason, optical sensors are generally preferable.
  • the disadvantages of optical measurements such as the effect of dust collection and fluctuations in brightness due to unstable current supply, for example which are able to vary the fundamental input value and thereby the working or zero point of the amplifier, are compensated satisfactorily by the above-described regulating feedback circuit.
  • a silicon diode as light-sensitive cell. It is known that the short-circuit current of a silicon photodiode increases and decreases in linear proportion to the illumination. However, the noload voltage of a silicon diode does not vary linearly but rather logarithmically. This logarithmic behavior of the no-load voltage can be advantageously utilized in the performance of yarn-fault checking apparatus according to the invention. This will be explained with reference to FIG. 3.
  • the diagram shown in FIG. 3 indicates along the abscissa the amount of illumination in lux to which the active surface of the silicon photodiode is subjected, and the ordinate indicates the corresponding voltage.
  • the curve represents the no-load voltage U in dependence upon the intensity of illumination. It will be recognized that, for example, a shading of 20% always results in the same voltage change U regardless of the absolute illumination intensity, except that only the base values of the voltage are different in dependence upon the illumination intensity. Since, as explained above, these different base values of voltage are compensated by the regulating feedback circuit in an apparatus according to the invention, these different base values have no effect upon the amplifying performance.
  • the amplifier according to FIG. 2 be controlled in accordance with another feature of the invention, in dependence upon the no-load voltage of the silicon diode. This is achieved by operating the first amplifier stage with the transistor 102 in common emitter configuration and thereby having a high input resistance. As a result, the silicon photodiode 101 is subjected almost to no-load current so that the no-load voltage of the diode 101 can become effective.
  • FIG. 4 shows by way of example a sensor stage equipped with two silicon photodiodes 101a and 101b which are applicable, in lieu of the single photocell 101 (shown in FIG. 2), for controlling the direct-current regulated amplifier.
  • the two photodiodes 101a and 101b according to FIG. 4 are connected in respective legs of a bridge network which is connected to the input terminals L and K of the amplifier shown in FIG. 2.
  • An adjustable potentiometer or rheostat 126 which forms two other legs of the bridge network permits calibrating the zero point of the network.
  • Another adjustable rheostat 127 serves for adapting to one another the generally slightly different voltage characteristics of the two photodiodes according to FIG. 3, so that for the same amount of shading the same voltage drop is produced in both diodes.
  • a sensor device of the type shown in FIG. 4 is particularly advantageous for detecting double or multiple threads.
  • the photodiodes 101a and 10112 are spaced from each other along the yarn path, and the respective voltage value simultaneously determined ahead of the knot and behind the knot are compared with each other in the bridge network.
  • the comparison shows a difference, causing the machine operation to stop, for example, by actuating the yarn cutter coil 100 through the operation of the amplifier shown in FIG. 2.
  • the pulses supplied to the amplifier input terminals K and L may change their polarity.
  • the voltage impressed upon the cutter control coil 100 under normal operating conditions that is when no fault-responsive pulses are applied to the input terminals K and L, amounts to only two volts because the coil 100 is connected between the minus 20 volts of terminal A and the regulated minus 18 volts at point D. If a pulse, instead of reducing the negative voltage would increase the negative voltage from minus 18 volts to minus 19 or minus 20 volts, for example, then the coil 100 could not properly respond.
  • FIG. 5 An embodiment of such a modification is shown in FIG. 5, it being understood that the circuit portion of FIG. 5 is applicable in a system otherwise corresponding to FIG. 2.
  • the winding 1000 is connected between the voltage supply terminals A and B in series with an adjustable resistor 128.
  • the constant voltage adjusted by means of the resis tor 128 can be impressed on the winding 1000.
  • the winding 100b acting opposite thereto is connected in the output circuit of the amplifier according to FIG. 2. While the amplifier output circuit according to FIG. 5 is different from that shown in FIG. 2, it will be understood that such and other modifications are readily applicable. It will be recognized that according to FIG. 5 the winding 10% forms part of a voltage divider whose tap point D is the starting point of a regulating feedback circuit extending through the Zener diode 116 to the transistor 106 (FIG. 2). The transistor 105 in this case is so controlled that the voltage normally obtaining between points C and D--this voltage being,
  • the potential of point D is regulated for constancy as in the embodiment according to FIG. 2.
  • a rapid positive or negative pulse issues from the photocells 101a and 1011) according to FIG. 4, for example due to the occurrence of a double thread, then the voltage at point D (FIG. 5 rises or drops, and the magnet 100a will respond because now one of the two magnetic fields will predominate.
  • the last amplifier stage may be provided in the form of a monostable switching stage, for example.
  • the magnet 100a (FIG. 5) be not energized by the pulse stemming from the passing of the knot through the sensing location, because otherwise the passing of each knot would result in the severing of the yarn even when no double thread were present.
  • the very short pulses produced by the passage of the knot itself therefore, are not supposed to cause a response of the cutter or cutter relay.
  • Such performance can be achieved, for example, without requiring a multivibrator, simply by taking advantage of the pick-up delay of the cutter or cutter relay.
  • an apparatus modified by employing the bridgetype sensor according to FIG. 4 and the amplifier output circuit according to FIG. 5, is suitable for the purpose of detecting multiple threads by comparing the measuring or signal voltage from respective sensing operations simultaneously effected in the yarn portions preceding and following a knot respectively.
  • the measuring values ahead of a knot and behind the knot may also be determined sequentially, stored and then compared with each other in a bridge network.
  • the storing of the two measuring values may be effected for example in two capacitors, and the very short voltage pulse produced by the knot itself may be used for releasing the switching from the first to the second capacitor.
  • An electrical timing member may then discontinue the measuring operation and initiate the voltage comparison, which thereafter, in the event of a discrepancy, will release the pulse for controlling the yarn severing device.
  • the voltage pulse produced by the knot may be given an increased amplitude 'by means of a resonance member so as to become ineffective with respect to the charging of the storage capacitors.
  • a sensing device for this apparatus comprises two photoelectric cells 101a and 101d. While these are shown only schematically, they are preferably so mounted that their respective sensitive surfaces are located at right angles to each other, the yarn to be checked passing through the intersection point of two beams of light impinging upon the respective cell surfaces.
  • Such a photoelectric sensing device is more fully described and illustrated in the copending applications Serial No. 307,077, filed September 6, 1963, of H. Raasch and W. Gith and Serial No. 398,653, filed September 23, 1964, of H. Raasch.
  • the two cells 1010 and 101d are parallel connected between the amplifier input terminals K and L.
  • the apparatus would also be operative if only one photo cell were used, but in such a case the particular advantages of operating with intersecting light beams would be missmg,
  • the feedback regulated amplifier 129 controlled by the two silicon diodes 101a and 101d corresponds to the one shown in FIG. 2, so that it suffices to indicate in FIG. 6 only the amplifier terminals A, B, C, D, L and K.
  • a start-control switch 130 which is closed manually or automatically whenever a knotting operation is terminated and the yarn commences its travelling motion. This is because the sensing operation is to commence only at this instant, since the yarn is already located in the sensing gap prior to the commencement of the yarn travel.
  • the provision of the switch 136 also ensures that any pulses which may occur when the yarn is being inserted into the sensing gap will not cause the release of the cutter-control magnet 101) (FIG. 2). As shown in FIG.
  • the start-control switch opens the feedback circuit at point R. Since the capacitor 118 is capable of storing its voltage during greatly prolonged periods of time, the closing of switch 13-0 immediately causes the voltage of capacitor 118, acting upon the transistor 1% and the potentiometer rheostat 115, to promptly reestablish the regulating condition existing prior to the preceding opening of the switch 130.
  • the relay or cutter control magnet 100 shown in FIG. 2 is substituted in the embodiment of FIG. 6 by a resistor 131.
  • the voltage at the reference point D has the eflfect that a conventional monostable multivibrator 138 switches a transistor 152 to conducting condition so that a capacitor 133 is charged from the voltage across resistor 131 through the transistor 132 and a diode 134.
  • a voltage pulse is applied to the amplifier input terminals due to the passage of a knot through the sensing gap, this pulse is greatly peaked in a resonance member, composed of capacitors 135 and 136, and a resonance pulse transformer 137.
  • the extremely short pulse of high amplitude is rectified and supplied to the monostable multivibrator 138.
  • the transistor 132 as well as the transistor 13? are both blocked as long as the knot pulse persists.
  • the monostable multivibrator 138 triggers to its stable condition and turns the transistor 139 on so that a capacitor 140 is then charged through a diode 141 and the transistor 139 to the voltage across resistor 131 which corresponds to the measurement value of the yarn located immediately behind the travelling knot.
  • the just-mentioned triggering of the monostable multivibrator 138 also applies energization to a time delay relay 142 through a resistor 143, a capacitor 144 being connected in shunt relation to the relay 142.
  • the period of delay corresponds to the time required for measuring the second yarn distance behind the knot.
  • the time delay relay 142 switches on, the two capacitors 133 and 140 are abruptly connected by the relay switch 145 to the respective terminals of a resistor 146. If the charging voltage of the capacitors 133 and 140 are equal, which is the case if no double thread is present, then the two voltages compensate each other and no voltage drop occurs at the resistor 146. However, if one of the two capacitors 133 and 140 has received a higher charge than the other because a double thread was located either in front of or behind the knot, then a voltage drop appears along the resistor 146 and is supplied to any suitable amplifier 147.
  • the amplifier 147 is energized from terminals P and Q connected to a source of voltage.
  • the end stage of the amplifier 147 may be identical with the one shown in FIG. so as to be capable of responding to positive as well as to negative pulses.
  • the polarity of the output voltage is then determined by the one capacitor 133 or 140 which has received the higher charge.
  • the multivibrator 138 triggers into its stable starting condition.
  • the capacitors 133 and 146 have meanwhile discharged through the resistor 146.
  • the two diodes 134 and 141 may be silicon p-n junction diodes having a very high blocking resistance. They serve to prevent premature discharge of the capacitors 133 and 140.
  • the measuring distance of the sensing device is not shorter than a given minimum length so that the signal issuing from the sensing device corresponds to a mean value of the yarn being checked. For example, when the yarn dimension is checked by capacitive means such as are exemplified in FIG.
  • the capacitor electrodes can have a length corresponding at least to the given minimum length in the travel direction of the yarn. Another way of extending the measuring distance is to have the yarn during each sensing operation travel a given distance through the sensing device such as the capacitors or photocells.
  • the two photocells 101a and 1411b can be spaced from each other a distance corresponding to the desired measuring distance.
  • the above-mentioned fluctuations and yarn dimensions may be different for different yarns. In some cases the fluctuations may occur over a relatively short distance, whereas in other cases, the fluctuations may occur over larger distances. It is therefore preferable for the length of the measuring distance to be adjustable.
  • An embodiment as shown in FIG. 6 operates to form a mean value of a yarn cross section, diameter or volume with the aid of the described signal storage system, because the charges stored in the respective capacitors 133 and 140, in fact, constitute the mean values of the single or doubled yarn successively detected.
  • simultaneous measuring of the mean value at a single or double yarn would permit dispensing with such a storage system so that the construction and performance of the apparatus is simplified accordingly.
  • the electric circuit connections in the latter case may then correspond to FIG. 2 in conjunction with FIGS. 4 and 5.
  • FIG. 7 schematically shown in FIG. 7 at 150 is the knotter of a yarn-package winding machine.
  • a knot X has just been completed by tying the yarn end coming from below to the yarn end coming from the yarn package located above the knotter 150. However the knot is defective because the lower yarn end forms a loop or double yarn.
  • the yarn travels through two sensing localities 151 and 152 constituted for example by the two photodiodes 191a and 1101b according to FIG. 4.
  • two photodiodes may be mounted at each sensing location as explained in the foregoing with reference to the two photodiodes 1010 and 101d shown in FIG.
  • the two diodes being illuminated by two mutually intersecting beams of light at whose intersection point the yarn is located.
  • the measuring locations are placed above the knotter 150 in the yarn path, substantially as described in the above-mentioned copending application Serial No. 398,653, of H. Raasch.
  • the two sensors 151 and 152 in accordance with the foregoing description at a sufficiently large distance, for example 10 to 15 cm., therebetween, it would be necessary to provide for a sufliciently large space above the knotter 150.
  • the space available in a winding machine above the knotter is not sufficient for such a long measuring distance. It is therefore preferable, according to another feature of the invention, to have the yarn pass laterally in the form of a loop away from and back to the normal path in the manner illustrated in FIG. 7.
  • the yarn tension can be kept within satisfactory limits despite the deflection of the yarn, particularly since the yarn deflection need be maintained only for a short interval of time subsequent to a knotting operation, for example during an interval of about 1 to 2 seconds.
  • the three rollers 153, 154 and 155 must be accelerated each time, the increase in yarn tension resulting from the acceleration can be kept within permissible limits if the rollers and their minute dustsealed ball-bearings are not considerably heavier, for example, than five grams and the outer diameters are not appreciably larger than 7 mm.
  • the temporary deflection of the yarn can then be controlled by shifting the roller 154 from the dot-and-dash position 154' to the left hand side of FIG. 7 shortly before the moment when the switch 130 (FIGS. 2, 6) is closed, the closing of this switch being then effected by the same control means, such as a control cam which also controls the operation of the knotter, as is illustrated and described for example in the above-mentioned copending application Serial No. 398,653.
  • This measuring length corresponds to the distance between the entry of the knot into the sensing location 151 and the entry of the knot into the sensing location 152. Since the deflecting roller 154 can be shifted from the inactive position 154, the length of the measuring distance can be varied by extending or shortening the shifting movement of the roller.
  • FIG. 8 represents the individual stages of operation at which the yarn in the two sensing locations 151 and 152 produce respective signals which are to be compared with each other.
  • the upper diagram shown at a in FIG. 8 relates to a stage in which the knot X has just been tied, as shown in FIG. 7 and the yarn portion above the knot has just been introduced into the sensing or measuring distance by deflection of the guide roller 154. Consequently, at this moment a single yarn passes through both sensing locations 151 and 152 so that the comparison of the corresponding signals does not yield an output signal.
  • the distance travelled by the knot X until it reaches the position shown in diagram of FIG. 8 represents the length l of the measuring distance.
  • the sensing operation is performed along a measuring distance which has a given minimum distance in order to determine a mean value of the yarn dimension being checked.
  • the length of the measuring distance can be adjustable if desired.
  • Other types of amplifiers suitable for static measurements are also applicable.
  • Apparatus for checking travelling yarn in textile machinery for slubs, doubling or the like faults comprising an electrically actuable device for stopping the yarn processing operation, yarn sensing means for issuing signal pulses in response to said faults, a direct current amplifier having an input circuit comprising said sensing means and having an output circuit connected to said device, said input circuit having a fundamental operating voltage upon which said pulses are superimposed, and regulating circuit means connected with said amplifier output circuit for maintaining the voltage of said output circuit substantially constant relative to changes of said fundamental voltage, whereby said device is actuable in response to said yarn-fault responsive signals independently of said changes.
  • Apparatus for checking travelling yarn in textile machinery for slubs, doubling or the like faults comprising an electrically actuable device for stopping the yarn processing operation, yarn sensing means for issuing signal pulses in response to said faults, a direct-current amplifier having an input circuit comprising said sensing means and having an output circuit connected to said device, said input circuit having a fundamental operating voltage upon which said pulses are superimposed, a negative feedback circuit voltage responsively connected to said output circuit and connected with said input circuit in bucking relation to said fundamental voltage for maintaining the voltage of said output circuit substantially constant relative to changes of said fundamental voltage, whereby said device is actuable in response to said yarnfault responsive signals independently of said changes.
  • Apparatus for checking travelling yarn in textile machinery for slubs, doubling or the like faults comprising an electrically actuable device for stopping the yarn processing operation, yarn sensing means for issuing signal pulses in response to said faults, a direct-current amplifier having an input circuit comprising said sensing means and having an output circuit connected to said device, said input circuit having a fundamental operating voltage upon which said pulses are superimposed, a feedback circuit connected between said output and input circuits and having means for applying to said input circuit a feedback voltage proportional to the output-circuit voltage and opposed to a proportion of said fundamental voltage, whereby said device is actuable in response to said signals irrespective of changes in fundamental voltage.
  • said feedback circuit comprising voltage threshold means so as to apply to said fundamental voltage the proportional share of said output-circuit voltage above a magnitude determined by said threshold'means.
  • Yarn checking apparatus comprising a Zener diode connected in said feedback circuit for applying said feedback voltage only when said outputcircuit voltage exceeds a threshold value depending upon said diode.
  • said feedback circuit comprising voltage threshold means for applying said feedback voltage only when said output-circuit voltage exceeds a threshold value depending upon said diode, and a reactive impedance member connected in said feedback circuit for storage and delay of the feedback voltage.
  • said feedback circuit comprising voltage threshold means for applying said feedback voltage only when said output-circuit voltage exceeds a threshold value depending upon said diode, and an auxiliary amplifier stage interposed between said feedback circuit and said .intput circuit for transferring said feedback voltage to said input voltage.
  • said interposed amplifier stage comprising a potentiometric output branch having an adjustable tapped portion connected with said input circuit in series-opposed relation to said fundamental voltage.
  • Yarn checking apparatus comprising an electromagnet for controlling said device, said magnet having two mutually opposed excitation windings, means for supplying adjustable constant voltage connected to one of said two windings, said output circuit of said amplifier comprising a voltage divider, and said other winding forming part of said voltage divider.
  • said yarn sensing means forming a measuring distance of a given minimum length in the yarn travel direction for response of said sensing means to a mean dimensional value of the yarn.
  • Yarn checking apparatus comprising adjustable yarn guiding means for varying the length of said measuring distance.
  • said sensing means comprising two sensors spaced from each other along the yarn travel path, and a bridge network having said sensors connected in respective bridge legs and having terminal points for furnishing said sig nal pulse-s.
  • said sensing means comprising a photoelectric device having a photocell whose normal output voltage constitutes said fundamental operating voltage.
  • Apparatus for checking travelling yarn in textile machinery for slubs, doubling or the like faults comprising an electrically actuable device for stopping the yarn processing operation, photoelectric yarn sensing means having a semiconductor photodiode for issuing signal pulses in response to said faults, said photodiode having a fundamental operating voltage upon which said pulses are superimposed, a direct-current amplifier having an input circuit in which said photodiode is connected, and having an output circuit connected to said device, a feedback circuit connected between said output and input circuits, an auxiliary amplifier stage interposed between said feedback circuit and said input circuit and having a resistive output branch connected in said input circuit in series with said photodiode and poled for mutually opposed polarities of the respective voltage drops of said photodiode and said resistive branch, whereby said device is actuated by said signals irrespective of changes in fundamental voltage.
  • said resistive output branch of said amplifying stage comprising a potentiometer having a variable tapped portion connected in series with said photodiode, and a Zener diode connected in said feedback circuit between said amplifier output circuit and said auxiliary amplifier stage.

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Quality & Reliability (AREA)
  • Treatment Of Fiber Materials (AREA)
  • Filamentary Materials, Packages, And Safety Devices Therefor (AREA)
  • Amplifiers (AREA)
  • Spinning Or Twisting Of Yarns (AREA)
US398663A 1963-09-28 1964-09-23 Apparatus for checking of travelling yarn in textile machinery Expired - Lifetime US3258824A (en)

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Application Number Priority Date Filing Date Title
DER0036246 1963-09-28

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US3258824A true US3258824A (en) 1966-07-05

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US (1) US3258824A (xx)
BE (1) BE653619A (xx)
CH (1) CH432050A (xx)
GB (1) GB1095201A (xx)
NL (1) NL144685B (xx)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3390441A (en) * 1965-12-13 1968-07-02 Zellweger Uster Ag Apparatus and method for reducing the number of unnecessary cuts of yarn
US3476329A (en) * 1965-07-06 1969-11-04 Zellweger Uster Ag Apparatus and method for avoiding unnecessary cuts by electronic yarn cleaners
US3673591A (en) * 1969-11-06 1972-06-27 Peyer Siegfried Yarn defect detector apparatus for textile machinery
US3731069A (en) * 1970-08-29 1973-05-01 Asahi Chemical Ind Apparatus for detecting yarn quality information
US3887814A (en) * 1973-11-01 1975-06-03 Du Pont Yarn slub analyzer
US4566163A (en) * 1983-06-21 1986-01-28 Nippon Selen Co., Ltd. Automatic supervisory system for a warper
US5074480A (en) * 1987-09-01 1991-12-24 Zellweger Uster Ag Process and apparatus for determining the yarn speed on textile machines

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4610707A (en) * 1985-09-05 1986-09-09 Ppg Industries, Inc. Broken filament detector and system therefor

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB716370A (en) * 1950-12-05 1954-10-06 Linen Ind Res Ass Improvements in apparatus for counting or removing faults from yarns and threads
US2936511A (en) * 1954-08-06 1960-05-17 William Hollins & Company Ltd Yarn clearing apparatus
US3154943A (en) * 1959-12-08 1964-11-03 Monsanto Co Slub detector

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB716370A (en) * 1950-12-05 1954-10-06 Linen Ind Res Ass Improvements in apparatus for counting or removing faults from yarns and threads
US2936511A (en) * 1954-08-06 1960-05-17 William Hollins & Company Ltd Yarn clearing apparatus
US3154943A (en) * 1959-12-08 1964-11-03 Monsanto Co Slub detector

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3476329A (en) * 1965-07-06 1969-11-04 Zellweger Uster Ag Apparatus and method for avoiding unnecessary cuts by electronic yarn cleaners
US3390441A (en) * 1965-12-13 1968-07-02 Zellweger Uster Ag Apparatus and method for reducing the number of unnecessary cuts of yarn
US3673591A (en) * 1969-11-06 1972-06-27 Peyer Siegfried Yarn defect detector apparatus for textile machinery
US3731069A (en) * 1970-08-29 1973-05-01 Asahi Chemical Ind Apparatus for detecting yarn quality information
US3887814A (en) * 1973-11-01 1975-06-03 Du Pont Yarn slub analyzer
US4566163A (en) * 1983-06-21 1986-01-28 Nippon Selen Co., Ltd. Automatic supervisory system for a warper
US5074480A (en) * 1987-09-01 1991-12-24 Zellweger Uster Ag Process and apparatus for determining the yarn speed on textile machines

Also Published As

Publication number Publication date
CH432050A (de) 1967-03-15
NL6411205A (xx) 1965-03-29
DE1473577A1 (de) 1969-09-04
GB1095201A (en) 1967-12-13
BE653619A (xx)
DE1473577B2 (de) 1972-10-26
NL144685B (nl) 1975-01-15

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