DE102014118461B4 - Method for determining the parameters of a moving yarn or other linear textile structure in a textile machine and optical line sensor for carrying out this method - Google Patents

Abstract

Method for determining parameters of a moving yarn or other linear textile structure in a textile machine by means of a vertical projection of the yarn onto individual optical elements (10) of an optical line sensor having adjacently arranged individual optical elements (10) of rectangular shape which provide at their output an analog signal corresponding to the degree of their irradiation, wherein the yarn is irradiated by radiation from a single radiation source with a cyclically alternating low radiation intensity and a high radiation intensity, wherein in each cycle the analog signals from all individual optical elements (10) are tracked and recorded at least at the high radiation intensity and the analog signal at the low radiation intensity is subtracted from them for each individual optical element (10) either in advance or in the corresponding cycle, whereby the resulting analog signal from the individual optical elements (10) is freed from all parasitic influences and its size depends only on the degree of irradiation from the radiation source of the optical sensor.

Description

Area of technology

The invention relates to a method for determining the parameters of a moving yarn or other linear textile structure in a textile machine by means of a vertical projection of the yarn onto individual optical elements of an optical line sensor which has one or two rows of individual optical elements of a rectangular shape which provide at their output an analog signal which corresponds to the degree of their irradiation.

The invention further relates to an optical line sensor comprising a sensor with a plurality of individual optical elements arranged next to one another in one or two rows for determining the parameters of a moving yarn or other linear textile structure in a textile machine by means of a vertical projection of the yarn onto individual optical elements of the sensor by means of a single radiation source.

State of the art

Known optical sensors for evaluating online yarn quality have a radiation source and an optical one- or two-line CMOS sensor, between which the respective yarn moves, the shadow of which is projected onto the optical elements of the sensor.

As a rule, a source generating radiation in the visible spectrum or in the infrared or ultraviolet spectrum is used as the source of light radiation. The source can be either monochromatic or composed of the spectrum of monochromatic components.

The influence of parasitic radiation sources can be minimized by appropriate design of the measuring zone in such a way that the parasitic radiation does not penetrate the respective sensor. However, to completely suppress the influence of parasitic sources, it would be necessary to completely close off the respective measuring zone, which is problematic in the case of a universal sensor that measures yarn quality. Another way to suppress the influence of parasitic sources is to use a source for yarn illumination with a high radiation intensity. The disadvantage of this method, however, is the high energy consumption of such a source and high heat loss. It is also possible to use, for example, optical filters that only allow the required radiation spectrum to pass through and suppress others.

Each optical element of the CMOS sensor generates an electric charge corresponding to the energy of the incident rays. The amount of the generated electric charge depends on the sensitivity of the optical element, the incident light energy and the time of irradiation of the optical element. However, the energy falling on the sensor and thus the sensor measurement are influenced by parasitic radiation sources (e.g. light bulbs, sunlight, flashing beacons, etc.), which affect the amount of energy falling on the optical element and thus introduce an error into the measurement. Another parasitic influence is the temperature and so-called noise of the optical element. The disadvantage of optical sensor technology is that electrons in the optical elements are created not only as a result of the incident light (from functional and parasitic radiation sources), but also depending on the ambient temperature, size of the optical sensor, sensor architecture and production technology. Although the sensor in question is completely dark, the optical element generates an output signal that is generated as a result of quantum events in the semiconductor. The positive property is that the parasitic currents are always the same under the respective conditions and are added additively to the output signal.

The EN 10 2010 037 676 B4 describes a method for tracking yarn quality (color homogeneity of the yarn surface), wherein the yarn quality is detected by means of an optical line sensor having a series of optical elements of a rectangular shape, and wherein the output of the optical elements corresponds to the degree of irradiation.

In the EP 1 319 926 B1 A device for contactless measurement of at least one property of a running thread or a thread-like textile structure is described, which comprises an optical line sensor with a plurality of pixels arranged next to one another in at least one line. The optical line sensor is integrated together with at least some of the electronic circuits for processing and/or evaluating the signal of the optical line sensor in a semiconductor-integrated customer-specific ASIC circuit, and the electronic circuits for processing and/or evaluating the signal of the optical line sensor are integrated with the optical line sensor on a common semiconductor chip and/or housed in a common housing.

From the EN 10 2004 053 736 A1 A yarn sensor is known for optically scanning a yarn that is moving in its longitudinal direction in a measuring gap, in which a light beam is sent from a light source into the measuring gap. There is at least one receiver for directly transmitted light and elements for transmitting the light between the light source, measuring gap and receivers. The light source is a radiator with Lambertian radiation characteristics. The light-transmitting element contains an aperture and a lens, whereby the aperture is imaged at least approximately at infinity. A diffuser is arranged between the light source and the aperture, which generates radiation that passes through the aperture and is symmetrical to the optical axis of the lens. The quality of the measurement results is thereby improved. The yarn sensor can be used in the textile industry on spinning or winding machines.

The EP 0 761 585 A1 relates to a yarn sensor for scanning a yarn moving in its longitudinal direction in a measuring gap with a light beam from a light source, with a first receiver for directly transmitted light, at least one second receiver for light reflected from the yarn and one element for transmitting the light between the measuring gap, the light source and a receiver. In order to keep the size and the external dimensions as small as possible, the optical axes of the elements for transmitting the light are arranged together in a plane that is at least approximately perpendicular to the yarn.

The aim of the present invention is to develop the method for determining the parameters of a moving yarn or other linear textile structure in an optical sensor, in which the resulting analog signal will be freed from all parasitic influences and its magnitude will depend only on the degree of irradiation from the radiation source of the optical sensor. It is also to create an optical line sensor for carrying out this method.

Explanation of the nature of the invention

The aim of the invention is achieved by a method for determining the parameters of a moving yarn or other linear textile structure, the essence of which is that the yarn is irradiated with radiation with a cyclically alternating low radiation intensity and high radiation intensity, in each cycle analog signals from all individual optical elements are tracked and recorded at least at the high radiation intensity, and from them for each individual optical element the value of the analog signal at a low intensity of the respective radiation is subtracted, which is determined either in advance or in the corresponding cycle, whereby the resulting analog signal is freed from parasitic influences and its size depends only on the degree of irradiation from the radiation source of the optical sensor. In this way, all parasitic influences are eliminated in an energetically undemanding manner and the resulting analog signal corresponds only to the degree of irradiation or shading by the yarn or other linear textile structure to be tracked.

The simplification of the method according to the invention is achieved if, in the case of radiation with a low radiation intensity, the radiation source of the optical sensor emits zero radiation. In this case, the radiation source radiates or does not radiate, which can be easily regulated and monitored without the need to set different radiation intensities of the respective sources.

To compare the analog signals from consecutive measurements, it is advantageous if the analog signals from individual optical elements are tracked at identically long intervals.

At the same time, it is advantageous if the analog signals of individual optical elements are tracked at low radiation intensity in the identically long intervals, whereby as long as both analog signals at a high radiation intensity and analog signals at a low radiation intensity are tracked in the identically long intervals, it simplifies their mutual subtraction.

To simplify the evaluation, the cyclically alternating low and high radiation intensity of the source of the optical sensor has a frequency that is equal to the undivided multiple of the evaluation frequency of the optical line sensor.

The radiation intensity of the radiation source changes due to the amount of current supplied to the respective radiation source. In the case of zero radiation intensity, no current is supplied to the radiation source.

From a price point of view, it is advantageous if the radiation source is formed by an LED diode.

The nature of the optical line sensor for carrying out the method according to the invention consists in the fact that the radiation source for cyclic irradiation of the individual optical elements of the sensor by radiation with a high radiation intensity and radiation with a low radiation intensity and analog circuits evaluating the difference between the analog signals of the individual optical elements are coupled to the source of the control signals, which are mutually synchronized in time. For temporal synchronization, it is advantageous if the lengths of the intervals at a low and high radiation intensity are identical and the times of scanning are synchronized with the evaluation frequency of the optical line sensor.

The simplification of the design and the increase in the reliability of the optical line sensor are achieved when at least the source of the control signals, the analog circuits that evaluate the difference between the analog signals from individual optical elements, and individual optical elements of the respective sensor are arranged on a common semiconductor substrate.

Explanation of the drawings

• 1 graphische Darstellung des Bestrahlungsgrades des einzelnen optischen Elementes des jeweiligen Sensors,
• 2 Schaltungszeichnung, die erfindungsgemäß arbeitet und
• 3a Zeitverlauf der Strahlung der Strahlungsquelle, Verfolgung der analogen Werte der optischen Elemente und Datenverarbeitung aus den optischen Elementen mit einer kontinuierlichen Verfolgung des analogen Signals bei einer niedrigen Strahlungsintensität und
• 3b Zeitverlauf der Strahlung der Strahlungsquelle, Verfolgung der analogen Werte der optischen Elemente und Datenverarbeitung aus den optischen Elementen mit dem im Voraus abgetasteten analogen Wert bei einer niedrigen Strahlungsintensität.

To explain the invention, the drawings are used, where it shows:

• 1 graphical representation of the irradiance of the individual optical element of the respective sensor,
• 2 Circuit drawing that works according to the invention and
• 3a Time course of the radiation of the radiation source, tracking of the analog values of the optical elements and data processing from the optical elements with a continuous tracking of the analog signal at a low radiation intensity and
• 3b Time course of the radiation from the radiation source, tracking the analog values of the optical elements and processing data from the optical elements with the pre-sampled analog value at a low radiation intensity.

Embodiments of the invention

Optical sensors for online determination of the parameters of a moving yarn or other linear textile structure on a textile machine that produces or processes the respective yarn or other linear textile material have a radiation source and a one- or two-line optical sensor, usually a CMOS sensor. The yarn or other linear textile structure moves in the radiation flux between the radiation source and the optical sensor, onto which the vertical yarn image is projected.

Individual optical elements 10 of the sensor provide an analog signal at their output that corresponds to the degree of their irradiation. 1 the irradiance of the optical element 10 is shown graphically, wherein the black color represents the analog signal corresponding to the amount of energy incident on the optical element 10 and/or in which it is formed by parasitic influences such as temperature and noise of the optical element 10 and parasitic radiation sources.

The value M is the maximum value that the optical element 10 can provide at its output in saturation, i.e. when illuminated by a very strong light source.

Ft is the parasitic value provided by the optical element 10 at its output which is not irradiated by the sensor's light source, at a radiation intensity low equal to zero. This parasitic value corresponds to the sum of all parasitic influences, i.e. parasitic radiation sources and parasitic influences which depend on the temperature of the sensor in the vicinity of the optical element 10, the size of the optical element 10, sensor architecture and production technology.

As long as the low intensity radiation is not zero, the value Ft is increased by the energy caused by this low intensity radiation.

Fs is the value provided by the optical element 10 at its output, which is irradiated by the light source at a high radiation intensity and also includes a parasitic value Ft.

Fr is the resulting value of the analog signal after deducting all parasitic influences. $$\text{Fri}=\text{Fs}-\text{Ft}$$

In order to be able to process the above-mentioned values in this way, they must be obtained from each optical element 10 for the same length of interval. To do this, a radiation source with a cyclically alternating low radiation intensity and high radiation intensity is used, which irradiates the respective yarn, whereby the frequency of the cycles of the radiation source is higher or at least equal to the evaluation frequency of the respective sensor. The cyclical alternation of the radiation with low intensity and high intensity radiation are based on 3a , 3b where, for the sake of simplicity, the low radiation intensity is zero. Time 1 represents the beginning of the radiation with a high intensity and time 6 represents the end of the radiation with a high intensity and at the same time the beginning of the radiation with a low intensity, in the example shown with zero intensity. The radiation with a low intensity continues until the radiation with a high intensity is resumed at another time 1. Time 2 indicates the beginning of the measurement of the optical element 10, regardless of whether already in the interval of radiation with a high intensity or in the interval of radiation with a low intensity. Time 3 indicates the end of the measurement of the optical element 10 for high radiation intensity and at the same time the time of saving the analogue measured value for high radiation intensity for the respective optical element 10, which is equal to the value Fs. Time 4 indicates the end of the measurement of the optical element 10 for low radiation intensity and at the same time the time of saving the analogue measured value for low radiation intensity, which at a low zero radiation intensity is equal to the parasitic value Ft. Time 5 refers to the data processing from the optical element 10, which means subtracting the parasitic value Ft from the total value Fs and storing the resulting value for further processing.

As it is on 3a As shown, the values Ft and Fs can be subtracted in each cycle. In the execution according to 3b the parasitic value Ft is determined and stored at the beginning of the measurement, and in individual cycles only the total value Fs is tracked, which is compared with the parasitic value Ft determined and stored at the beginning of the measurement. Both of these methods can of course be combined appropriately, for example, the parasitic value Ft can always be determined when the work station of the machine where the tracking is taking place is interrupted, for example when the yarn spinning process is interrupted, both as a result of breakage and when the full bobbin is replaced with an empty one.

das nachfolgend in dem analog-digitalen Umwandler 60 zum Signal Fp umgewandelt wird. Zur Sicherstellung der Synchronisierung sind sowohl Differenzglied 50 als auch analog-digitaler Umwandler 60 mit der Quelle 40 der Steuersignale verkoppelt.As it is on 2 for an optical element 10 of the sensor, the analog signal from the optical element 10 is fed via the charge amplifier 20 into the memory cell 310 or into the memory cell 320, which together with the charge amplifier 20 are coupled to the source 40 of control signals, which ensures their synchronization with a radiation source (not shown). This ensures that the analog value Ft is stored in the memory cell 320, which is generated by the influence of all parasitic influences at a time when the radiation source is not radiating (low value of radiation intensity is equal to zero) and the optical element 10 is therefore not irradiated, and the analog value Fs is stored in the memory cell 310, which is generated by the optical element 10 at a time when the radiation source is radiating and the optical element 10 is therefore irradiated. The value Fs therefore includes both the signal generated by the sensor's radiation source and the signal generated by the influence of parasitic influences. Signals Fs and Ft are fed to the output of the differential element 50, at the output of which the signal is $$\text{Fri}=\text{Fs}-\text{Ft},$$

which is subsequently converted to the signal Fp in the analog-digital converter 60. To ensure synchronization, both the differential element 50 and the analog-digital converter 60 are coupled to the source 40 of the control signals.

In the solution mentioned, the analog values are sampled and stored for all optical elements 10 regardless of whether the respective optical element 10 is unshaded or partially or completely shaded by the yarn.

In order for the respective results to be correct, it is necessary that both intervals during which the stored signals are formed are identical and that the start of the measurement and the time of storing the values in the memory cells 310, 320 are correctly timed and synchronized. Therefore, the source 40 of control signals is also formed on the same semiconductor substrate. The source 40 of control signals generates the signal for controlling the intensity of the radiation source, adjusts the start of the measurements, determines the time of integration of the electric charge and the end of the measurement of the individual analog values, synchronizes the storage of the values in the memory cells 310, 320 and execution of the calculation.

In cases where the intervals in which the integration of the electric charge occurs are different, the values obtained must be converted in proportion to the lengths of the respective intervals.

The memory cell 310 stores the value Fs for the time T of the radiation of the source and the memory cell 320 stores the parasitic value Ft for the time T with the source switched off, i.e. with zero radiation intensity. Behind the differential element 50 is the resulting analog value Fr.

List of reference symbols

M

maximum value of irradiation of the optical element

Ft

parasitic value of the irradiation of the optical element

Fs

Total irradiation value of the optical element

Fri

resulting value of the irradiation of the optical element

Fp

digitized signal

T

Time of source radiation

1

Beginning of radiation with a high intensity

2

Start of measurement of the optical element

3

End of measurement of the optical element and storage of the high intensity value

4

End of measurement of the optical element and storage of the low intensity value

5

Data processing from the optical element

6

End of radiation with a high intensity

10

optical element of the sensor

20

Charge amplifier

310

Memory cell for Fs

320

Storage cell for Ft

40

Source of the control signal

50

Differential element

60

analog-digital converter

Claims (10)

Method for determining parameters of a moving yarn or other linear textile structure in a textile machine by means of a vertical projection of the yarn onto individual optical elements (10) of an optical line sensor having adjacently arranged individual optical elements (10) of rectangular shape which provide at their output an analog signal corresponding to the degree of their irradiation, wherein the yarn is irradiated by radiation from a single radiation source with a cyclically alternating low radiation intensity and a high radiation intensity, wherein in each cycle the analog signals from all individual optical elements (10) are tracked and recorded at least at the high radiation intensity and the analog signal at the low radiation intensity is subtracted from them for each individual optical element (10) either in advance or in the corresponding cycle, whereby the resulting analog signal from the individual optical elements (10) is freed from all parasitic influences and its size depends only on the degree of irradiation from the radiation source of the optical sensor. Procedure according to Claim 1 , characterized in that in the case of radiation with a low intensity the radiation source of the optical sensor emits zero radiation. Procedure according to Claim 1 or 2 , characterized in that the analog signals from individual optical elements (10) are tracked at the same intervals at a high radiation intensity. Method according to one of the preceding claims, characterized in that the analog signals from individual optical elements (10) are tracked at a low radiation intensity in the same intervals. Procedure according to Claim 3 or 4 , characterized in that the analog signals from individual optical elements (10) at a low radiation intensity are tracked at intervals of identical length as the analog signals from individual optical elements (10) at a high radiation intensity. Procedure according to Claim 1 , characterized in that the cyclically alternating low and high radiation intensity of the radiation source of the optical sensor has a frequency which is equal to the undivided multiple of the evaluation frequency of the optical line sensor. Method according to one of the preceding claims, characterized in that the radiation intensity of the radiation source of the optical sensor is changed by the size of the current supplied to the radiation source. Procedure according to Claim 7 , characterized in that the radiation source is formed by an LED diode. Optical line sensor comprising a sensor with a plurality of optical elements (10) arranged next to one another for detecting Parameters of a moving yarn or other linear textile structure in a textile machine with the aid of a vertical projection of the yarn onto individual optical elements (10) of the sensor by means of a single radiation source for carrying out the method according to one of the preceding claims, wherein the radiation source for cyclically irradiating individual optical elements (10) of the sensor by radiation with a high radiation intensity and radiation with a low radiation intensity and analog circuits evaluating the difference between the analog signals from individual optical elements (10) are coupled to a source (40) of the control signals which are mutually synchronized in time. Optical line sensor according to the Claim 9 , characterized in that at least the source (40) of the control signals, analog circuits evaluating the difference between the analog signals from individual optical elements (10) and individual optical elements (10) of the sensor are arranged on a common semiconductor substrate.

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