WO2016149842A1

WO2016149842A1 - Electrode assembly for capacitively testing an elongated textile material

Info

Publication number: WO2016149842A1
Application number: PCT/CH2016/000036
Authority: WO
Inventors: Gabriela Peters; Loris De Vries; Rafael Storz
Original assignee: Uster Technologies Ag
Priority date: 2015-03-20
Filing date: 2016-02-29
Publication date: 2016-09-29

Abstract

An electrode assembly (5) for capacitively testing an elongated textile material comprises an electrode (64) as part of a measuring capacitor for capacitively testing the elongated textile material. It further comprises a substrate (6) made of an electrically non-conductive material with a first essentially plane base surface (61), a second essentially plane base surface (62) and a peripheral surface (63) between the first base surface (61) and the second base surface (62), the substrate (6) bearing the at least one electrode (64). A metal frame (7) covers at least part of the peripheral surface (63). The metal frame (7) has a convex, smooth surface (74) extending outwardly from the first base surface (61) to the second base surface (62). The metal frame (7) protects the electrode (64) from electrostatic and electromagnetic influences from the outside and thus makes possible a sophisticated evaluation yielding several parameters of the textile material and eliminating the humidity.

Description

ELECTRODE ASSEMBLY FOR CAPAC1TIVELY TESTING AN ELONGATED

TEXTILE MATERIAL

BACKGROUND OF THE INVENTION

The invention relates to an electrode assembly for capacitively testing an elongated textile material, according to the preamble of the first claim. The invention also relates to an apparatus for testing an elongated textile material, according to the preamble of a further claim.

DESCRIPTION OF THE PRIOR ART Apparatus for capacitively testing an elongated textile material such as yarn, roving or sliver are used to measure certain parameters of the textile material in a textile laboratory. The measured parameters indicate the quality of the textile material. They can encompass, for example, a mass per unit length or a material composition of the textile material. Such apparatus are known from CN-87' 104'921 A and CN- iOl '223'442 A. They comprise a housing which accommodates sensors for measuring parameters of the textile material, electronic circuits for evaluating the sensor signals, and a conveyor for conveying the textile material. The textile material runs on a textile-material path along a front panel of the housing, usually in the vertical direction top down. The sensors are arranged successively along the textile-material path and have measuring slits for accommodating the running textile material.

CN-1 '236O90 A discloses a capacitive device for measuring properties of a textile product in a measurement slot in which the textile product is inserted. The measurement slot is formed by the plane surfaces of two substrates facing each other. Each of the surfaces bears an electrode of a measuring capacitor for accommodating the textile product, an electrode of a compensation capacitor and a conductor. CN- 1 '236O90 A also discloses an arrangement of several measurement slots with various widths, which are jointly arranged in a single element. The measurement slots have various widths in order to allow for products with various diameters.

More complex electric circuits with electrodes for the capacitive examination of a textile product are shown in CH-707'093 A2.

CN-1 Ό86'899 A proposes to mask out edge zones of the measurement slot by means of plastic guides put over the substrates bearing the measuring electrodes. The guides reduce the width of the measurement slot and thus better define the position of the test material within the measurement slot. Thus, the "position effect" is reduced and the measurement accuracy is improved.

US-3,754,172 A discloses a measuring electrode formed by vapor deposition as a metal coating on a high-frequency ceramic substrate. A further metal coating on the substrate surrounding the measuring electrode serves as a grounded shield for shielding the measuring electrode from undesired electromagnetic influences from the outside.

As a matter of fact, the design of the electronic circuits containing the measuring electrode and the means and methods for evaluating their output signals have made enormous progress since the publication of US-3,754,172 A. Methods have been developed for extracting from the output signals not only the mass per unit length of the textile material, but also further intrinsic and extrinsic parameters such as the composition of the textile material or its humidity. This is achieved, for instance, by a multi-channel technology as described in CN-1 '226'001 A and/or by a multi-frequency technology as described in CN-101 '405'598 A. Such powerful, sensitive capacitive testing devices and methods are prone to electrostatic and electromagnetic influences from the outside.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide an electrode assembly in which the electrode is effectively protected from electrostatic and electromagnetic influences from the outside. It is a further object to reduce the mutual abrasion of the electrode assembly and the test material. It is a still further object to provide an apparatus for testing an elongated textile material with an electrode assembly fulfilling the objects given above.

These and other objects are solved by the electrode assembly defined in the first claim and by the apparatus defined in a further claim. Advantageous embodiments are indicated in the dependent claims.

The electrode assembly for capacitively testing an elongated textile material according to the invention comprises at least one electrode as part of a measuring capacitor for capacitively testing the elongated textile material. It further comprises a substrate made f an electrically non-conductive material with a first essentially plane base surface, a second essentially plane base surface and a peripheral surface between the first base surface and the second base surface, the substrate bearing the at least one electrode. A metal frame covers at least part of the peripheral surface. The metal frame has a convex, smooth surface extending outwardly from the first base surface to the second base surface.

The metal frame preferably covers the peripheral surface from three different spatial directions.

The metal frame is preferably made of a metal with a Mohs hardness equal to or higher than 4. It can be made, for example, of chromium steel.

In one embodiment, the at least one electrode is arranged on the first base surface and/or on the second base surface. The at least one electrode can contain silver. A shielding layer, made of the same material as the at least one electrode and electrically insulated fro the at least one electrode, can be arranged on the same base surface as the at least one electrode. It is advantageous if the metal frame is in electric contact with the shielding layer.

At least part of the first base surface and/or second base surface is preferably covered by an electrically insulating glaze.

At least part of the substrate is preferably covered by a plastic cap. The apparatus for testing an elongated textile material according to the invention comprises a housing with a front panel, along which front panel a textile-material path of the elongated textile material extends. The apparatus further comprises at least two electrode assemblies protruding from the front panel, each of the at least two electrode assemblies bearing at least one electrode, and at least two adjacent electrode assemblies being arranged such that their respective electrodes form a measuring capacitor for

accommodating the textile material. At least one of the at least two electrode assemblies is an electrode assembly according to the invention, as described above. The metal frame of the at least one electrode assembly preferably covers the whole peripheral surface protruding from the front panel.

In one embodiment, the at least two adjacent electrode assemblies are arranged such that their respective electrodes form a measuring capacitor are electrode assemblies according the invention, as described above. The base surfaces facing each other of the at least two adjacent electrode assemblies are preferably arranged parallel to each other and spaced apart from each other so as to form a measurement slot. The base surfaces facing each other of the at least two adjacent electrode assemblies are preferably perpendicular to the front panel.

A first advantage of the electrode assembly according to the invention is that the electrode is effectively protected by the metal shield from electrostatic and electromagnetic influences from the outside. Thanks to this protection, the full potential of new capacitive testing technologies such as the multi-channel or the multi-frequency technology can be tapped. The sensor output signals show less disturbances and thus can be sophistically evaluated for obtaining a plurality of precisely measured parameters such as the mass per unit length, the composition, the humidity of the textile material or the presence and composition of foreign matter possibly contained in the textile material. Influences of varying ambient humidity can be eliminated. A second advantage is that the abrasion of the electrode assembly by the textile material is reduced thanks to the metal shield forming a hard edge of the electrode assembly, and the abrasion of the textile material by the electrode assembly is reduced thanks to the convex, smooth surface of the metal shield. Less abrasion means less debris, especially in the measurement slot, which again results in a higher precision and reliability of the measurement results.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is now explained in closer detail by references to drawings which illustrate an embodiment of the invention.

Figure 1 shows an apparatus with an electrode assembly according to the

invention in a perspective view.

Figure 2 shows the electrode assembly according to the invention in a perspective view.

Figures 3 and 4 show different parts of the electrode assembly according to the invention in perspective views.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 shows an apparatus 1 according to the invention in a perspective view. The apparatus 1 comprises a housing 2 with a front panel 3. A textile-material path 4 of an elongated textile material extends along the front panel 3. The elongated textile material can be, e.g., a yam, a roving or a sliver. It is not drawn in Figure 1 , but runs on the textile- material path 4 along the front panel 3 in the vertical direction top down. The textile material is delivered via a changer means 1 1 and a deflection roller 12 into the textile-material path 4. A feeder means 13 can be provided for feeding the textile material into the textile-material path 4. Alternatively, the textile material can be delivered from the side via delivery rolls 14. Various sensors for measuring various parameters of the textile material are arranged successively along the textile-material path 4 and have measuring slits for accommodating the running textile material. A capacitive sensor assembly 15 for measuring a mass-related parameter of the textile material protrudes from the front panel 3. A bottom part of the apparatus 1 contains conveyor means 16 for conveying the textile material along the textile-material path 4. The conveyor means 16 can be designed as a roller delivery mechanism with two cooperating conveying rollers, at least one of which is driven by a motor. At the end of its path, the textile material is sucked off the textile- material path 4 through a vent 17, and is then disposed. The capacitive sensor assembly 15 according to the invention is shown in more detail in Figure 2. The view of Figure 2 is shifted by 90° with respect to Figure 1. Thus, in Figure 2 a textile material 9 to be tested runs essentially from the right to the left, indicated by an arrow 91 , whereas in Figure 1 it runs from top to bottom. Figure 3 shows a metal frame 7 and Figure 4 a corresponding substrate 6 of an electrode assembly 5 according to the invention.

The capacitive sensor assembly 15 comprises five electrode assemblies 5.1-5.5. Each electrode assembly 5.1 -5.5 comprises a substrate 6 with a first essentially plane base surface 61 , a second essentially plane base surface 62 and a peripheral surface 63 between the first base surface 61 and the second base surface 62. In each case, the base surfaces facing each other of two adjacent electrode assemblies 5.1 , 5.2 are arranged parallel to each other and spaced apart from each other so as to form a measurement slot 8.1 ; further measurement slots 8.2-8.4 are drawn in Figure 2. Each substrate 5.1 -5.5 bears the at least one electrode 64, which is visible in Figure 4. The two adjacent electrode assemblies 5.1 , 5.2 are arranged such that their respective electrodes form a measuring capacitor for accommodating the textile material 9. The various substrates and the various electrodes can have various sizes. The measurement slots 8.1-8.4 can have various widths in order to allow for textile materials 9 with various diameters. The five electrode assemblies 5.1 -5.5 are mounted in a housing 50. The housing 50 also accommodates an electronic circuit (not shown) connected with the electrodes for providing input signals to the electrodes and for evaluating output signals of the electrodes.

In a first electrode assembly 5.1 and a second electrode assembly 5.2 of Figure 2, a metal frame 7.1 , 7.2 in each case covers the whole peripheral surface 63 protruding from the front panel 3. The metal frame 7 is shown separately in Figure 3. It has essentially the shape of a reversed U, with three straight sections 71 -73, and thus covers the peripheral surface 63 of the substrate 6 from three different spatial directions. The two legs 71, 72 of the U cover the flanks of the substrate 6, i.e., the regions where the textile material 9 enters and leaves the measurement slot 8.1 during the testing process. The middle section 73 of the U covers the front face of the substrate 6, i.e., the region where the textile material 9 is inserted into the measurement slot 8.1 before start of the test. The metal frame 7 has a convex, smooth surface 74 extending outwardly from the first base surface 61 to the second base surface 62 of the substrate 6. Also the corners, where the straight sections 71, 73 and 72, 73 join, are rounded off. Thus, the textile material 9 never runs over a sharp edge. The hardness on the Mohs scale of the metal frame 7 is preferably equal to or higher than 4. The metal frame 7 can be made, e.g., of bulky chromium steel with a Mohs hardness of 6. The metal frame 7 can be fastened to the substrate 6, e.g., by screws (not shown).

The metal frame 7 has basically two functions. Firstly, it effectively protects the electrode 64 from electrostatic and electromagnetic influences from the outside and thus makes possible a sophisticated and precise evaluation of the electrode output signals, yielding several parameters of the textile material and eliminating the humidity. The large mass of metal and the large area covered by the metal frame 7 contribute to this first function. Secondly, it reduces the mutual abrasion of the electrode assembly 5, 5.1, 5.2 and the textile material 9. The hard, large, convex, smooth surface of the metal frame 7 contributes to this second function.

The substrate 6 is made, e.g., of an electrically non-conductive ceramic material. It has essentially the shape of a flat cuboid, except for a base part with a trapezoidal recess. The side lengths of the cuboid can be, for instance, 12 cm x 6 cm x 1 cm. In the example of Figure 4, a rectangular electrode 64 is arranged on the first base surface 61 of the substrate 6. The electrode 64 can be realized as a metal coating containing silver, deposited on the first base surface 61 by screen printing. The electrode 64 is contacted by a first electric line 66 fed through a bore inside the substrate 6. A shielding layer 65, made of the same material as the electrode 64 and electrically insulated from the electrode 64, is also arranged on the first base surface 61. The shielding layer 65 can essentially cover the whole first base 61 surface except for a rectangle in which lies the electrode 64. It can also be deposited on the first base surface 61 by screen printing. The shielding layer 65 is contacted by a second electric line 67 and a third electric line 68, which are grounded. Preferably, the metal frame 7 is in electric contact with the shielding layer 65 and thus also grounded. The grounded metal frame 7 and the grounded shielding layer 65 give together an optimum protection for the electrode 64 from electrostatic and electromagnetic influences from the outside. Electric components on the second base surface 62 can be designed in a similar way as the electric components 64, 65 the first base surface 61. An electrode (not shown) on the second base surface can have a different size and/or shape than the electrode 64 on the first base surface 61 , depending on the size of the respective measurement slot and the textile material to be tested in said measurement slot. Alternatively, the second base surface 62 can be without any electrode, which can be especially the case for the marginal electrode assembly 5.1. The second base surface 62 can be covered by a shielding layer or uncovered.

One or both base surfaces 61 , 62 of the substrate 6 can bear more complex electric circuits than the one shown in Figure 4. Examples of such electric circuits are given in

CN-1 '236'090 A and in CH-707'093 A2.

At least part of the first base surface 61 and/or second base surface 62 is preferably covered by an electrically insulating glaze. Such a glaze protects the electric components 64, 65 on the base surfaces 61 , 62 from electric and mechanical contact with other components, and from the undesired influence of humidity in the ambient air. Moreover, at least part of the substrate 6 is preferably covered by a plastic cap 69. The plastic cap 69 provides further mechanical protection for the electric components 64, 65 and better defines the position of the textile material 9 within the measurement slot 8.1 , as described in CN-1'086'899 A. The plastic caps 69 put over the substrates arc the reason why the electric components 64, 65 cannot be seen in Figure 2.

In an alternative embodiment, the electrode could be arranged inside the substrate, rather than on a base surface 61 of the substrate 6. LIST OF REFERENCE NUMERALS

1 Apparatus

1 1 Changer means

12 Deflection roller

13 Feeder means

14 Capacitive sensor assembly

15 Conveyor means

16 Vent

2 Housing

3 Front panel

4 Textile-material path

5, 5.1-5.5 Electrode assemblies

6 Substrate

61 , 62 First and second base surfaces of the substrate

63 Peripheral surface of the substrate

64 Electrode

65 Shielding layer

66-68 Electric lines

7 Metal frame

71-73 Straight sections of the metal frame

74 Convex, smooth surface of the metal frame

8.1-8.4 Measurement slots

9 Textile material

91 Direction of movement of the textile material

Claims

1. An electrode assembly (5, 5.1 , 5.2) for capacitively testing an elongated textile

material (9), comprising

at least one electrode (64) as part of a measuring capacitor for capacitivcly testing the elongated textile material (9), and

a substrate (6) made of an electrically non-conductive material with a first essentially plane base surface (61 ), a second essentially plane base surface (62) and a peripheral surface (63) between the first base surface (61) and the second base surface (62), the substrate (6) bearing the at least one electrode (64),

characterized by

a metal frame (7) covering at least part of the peripheral surface (63),

the metal frame (7) having a convex, smooth surface (74) extending outwardly from the first base surface (61) to the second base surface (62).

2. The electrode assembly (5, 5.1 , 5.2) according to claim 1 , wherein the metal frame (7) covers the peripheral surface (63) from three different spatial directions.

The electrode assembly (5, 5.1, 5.2) according to one of the preceding claims, wherein the metal frame (7) is made of a metal with a Mohs hardness equal to or higher than 4.

The electrode assembly (5, 5.1 , 5.2) according to claim 3, wherein the metal frame (7) is made of chromium steel.

The electrode assembly (5, 5.1, 5.2) according to one of the preceding claims, wherein the at least one electrode (64) is arranged on the first base surface (61) and/or on the second base surface (62).

The electrode assembly (5, 5. 1 , 5.2) according to claim 5, wherein the at least one electrode (64) contains silver. The electrode assembly (5, 5.1, 5.2) according to claim 5 or 6, wherein a shielding layer (65), made of the same material as the at least one electrode (64) and electrically insulated from the at least one electrode (64), is arranged on the same base surface (61) as the at least one electrode (64).

The electrode assembly (5, 5.1, 5.2) according to claim 7, wherein the metal frame (7) is in electric contact with the shielding layer (65).

The electrode assembly (5, 5.1 , 5.2) according to one of the preceding claims, wherein at least part of the first base surface (61) and/or second base surface (62) is covered by an electrically insulating glaze.

The electrode assembly (5, 5.1 , 5.2) according to one of the preceding claims, wherein at least part of the substrate (6) is covered by a plastic cap (69).

An apparatus (1) for testing an elongated textile material (9), comprising

a housing (2) with a front panel (3), along which front panel (3) a textile-material path (4) of the elongated textile material extends, and

at least two electrode assemblies (5.1 -5.5) protruding from the front panel (3), each of the at least two electrode assemblies (5.1 -5.5) bearing at least one electrode, and at least two adjacent electrode assemblies (5.1 , 5.2) being arranged such that their respective electrodes form a measuring capacitor for accommodating the textile material (9),

characterized in that

at least one of the at least two electrode assemblies (5.1 , 5.2) is an electrode assembly (5, 5.1 , 5.2) according to claim 1.

The apparatus (1) according to claim 1 1, wherein the metal frame (7) of the at least one electrode assembly (5.1, 5.2) covers the whole peripheral surface (63) protruding from the front panel (3).

The apparatus (1) according to claim 1 1 or 12, wherein the at least two adjacent electrode assemblies (5.1 , 5.2) being arranged such that their respective electrodes form a measuring capacitor are electrode assemblies (5, 5.1 , 5.2) according to claim 1.

The apparatus ( 1 ) according to claim 13, wherein the base surfaces facing each other of the at least two adjacent electrode assemblies (5.1 , 5.2) are arranged parallel to each other and spaced apart from each other so as to form a measurement slot (8.1 ).

The apparatus (1) according to claim 14, wherein the base surfaces facing each other of the at least two adjacent electrode assemblies (5. 1 , 5.2) are perpendicular to the front panel (3).