Shielding for a capacitive sensor, method for manufacturing such a shield, capacitive sensor for consistency measuring instruments, consistency measuring instrument

Abstract

Shielding (50) for a capacitive sensor, comprising: a ceramic body (51) having a first primary side (52), a second primary side (53), and a plurality of secondary sides (54); a first metal layer (55) arranged on the first primary side (52) and defining a shielding section (55'), wherein the first metal layer (55) extends from a first end section (56) of one of the secondary sides (54) over a portion of its length; a second metal layer (57) arranged on the first primary side (52) and defining a shielding section (57'), wherein the second metal layer (57) extends from at least a second end section (58) of one of the secondary sides (54) such that it partially surrounds the first metal layer (55), wherein the second metal layer (57) is arranged at a distance from the first metal layer (55) such that a portion of the first primary side (52) remains uncovered;wherein the first end section (56) is prepared to electrically connect a first electrical conductor or connecting wire (59') to the first metal layer (55), and wherein at least one second end section (58) is prepared to connect at least one corresponding second electrical conductor or connecting wire (59") to the second metal layer (57).

Description

[0001] The present invention relates to a shield for a capacitive sensor, to a capacitive sensor for uniformity measuring devices, and to a uniformity measuring device. The present invention also relates to a method for manufacturing the aforementioned shield.

[0002] As is known, a uniformity meter is a device for measuring the mass uniformity of a textile thread or yarn, such as cotton, synthetic, blended, or other materials. The measurement is performed by passing the textile thread or yarn at a substantially constant speed through the shields of a capacitive sensor, which consist of two flat, parallel bodies. The uniformity meter measures the mass change of the thread or yarn by measuring the electrical capacitance of the capacitor of the capacitive sensor, which consists of the aforementioned shields, in which the air and the thread or yarn between the shields act as a dielectric material.When the mass of the thread or yarn changes, the dielectric constant of the dielectric material between the shields changes, and consequently, the electrical capacitance of the capacitor changes according to a known relationship. Measuring this electrical capacitance is therefore an indirect measure of the mass of the thread or yarn.

[0003] Different types of capacitive sensors are known.

[0004] In particular, capacitive sensors of a first type consist of capacitors with metal shields. Such metal shields are generally formed by two opposing and parallel metal bodies in the shape of parallelepipeds. The metal shields are further connected via electrical conductors to a processing unit included in the uniformity meter, which is programmed to process the measured values ​​of the capacitive sensor and determine the mass value of the thread and yarn.

[0005] The shields must be connected to the housing of the device (i.e., the uniformity meter) and, in particular, they must be supported in such a way that they remain spaced apart and parallel. However, since both the shields and the body of the meter are made of conductive metal, it is necessary to support the shields by means of support elements made of an electrically insulating material to ensure that the shields do not come into electrical contact with the housing of the uniformity meter, thereby causing a short circuit between them. The installation of the first type of capacitive sensors is therefore not easy and presents a number of difficulties due precisely to the need to electrically separate the shields and the housing of the device.

[0006] The capacitive sensors of a second type consist of shields made with supporting bodies of ceramic material, which are opposite to each other and parallel to each other and have a metal layer on their facing surfaces.

[0007] Fig. 1 shows schematically a shield 1 of a capacitive sensor of the second type.

[0008] Such a shield 1 comprises a ceramic body 2 having a first side and a second side opposite the first side. The first side is provided with a first metallic surface layer 3 and a second metallic surface layer 4 surrounding the first metallic surface layer. The ceramic body 2 has a first metallized hole 5, which is open on the first side at the first metallic surface layer 3 and which extends transversely to both sides, and a second metallized hole 6, which is open at one end of the ceramic body 2 and extends longitudinally until it intersects and connects to the first hole 5.

[0009] A first electrical conductor or connecting wire 7 is typically connected to the ceramic body 2 by means of a weld made at the opening of the second metallized hole 6.

[0010] In this way, the first metallic surface layer 3 is electrically connected to the first electrical conductor or connecting wire 7 via the metallized holes 6, 5, whereby the shield can then be electrically connected to the processing unit in the uniformity measuring device.

[0011] The ceramic body 2 also has, at the end where the second metallized hole 6 was made, a third metallized hole 8 and a fourth metallized hole 9, to which a second electrical conductor or connecting wire 10 and a third electrical conductor or connecting wire 11 are anchored, respectively. The third hole 8 and the fourth hole 9 are electrically connected to the second surface layer 4, which is consequently also electrically connected to the second electrical conductor or connecting wire 10 and the third electrical conductor or connecting wire 11. The first electrical conductor or connecting wire 7 is intended to be connected to the potential of the shield 1, while the second electrical conductor or connecting wire 10 and the third electrical conductor or connecting wire 11 are intended to be connected to the potential of the electrical ground.The second surface layer 4 is intended to act as a shielding layer in which the internal electric field lines are necessarily closed, which without this shielding layer would close on areas or objects in the vicinity of the shielding 1 that do not belong to the capacitor of the capacitive sensor and would influence the capacitance measurement.

[0012] The manufacturing process of such a shield includes the following steps: - Manufacturing a semi-finished product from ceramic material by molding and subsequent firing in a kiln; - carrying out mechanical machining of the semi-finished product obtained, generally by grinding, in order to give the product the desired geometry with predetermined tolerances and thus obtain the ceramic body 2; - making a plurality of holes in the ceramic body 2 along the longitudinal extension axis X, thereby creating the second hole 6, the third hole 8 and the fourth hole 9; - drilling the ceramic body 2 along an axis transverse to the two sides, thereby creating the first hole 5; - performing metallization by screen printing on the first side, thereby creating the first metallic surface layer 3 and the second metallic surface layer 4; - Carrying out manual metallization of the aforementioned holes, for example using a brush, in order to completely coat the inner surface of the holes; - Firing the ceramic body 2 in the kiln to fix the metallization on the ceramic; - Making a soldering connection between the electrical conductors or connecting wires 7, 10, 11 and the holes 6, 8, 9; - Filling the first hole 5 with electrically insulating material.

[0013] This manufacturing process has some disadvantages.

[0014] A first disadvantage is that drilling a ceramic body, especially longitudinally, is a very delicate operation, posing a high risk of damage or breakage. The second hole 6, the third hole 8, and the fourth hole 9 must be drilled very carefully and slowly.

[0015] To minimize the risk of breakage of the ceramic body, the body must be shaped to minimize the length of the second hole 6. Such a shape is achieved by the mechanical machining mentioned above, which, however, requires caution and care to avoid breakage of the ceramic body.

[0016] Another disadvantage of the manufacturing process described above is that the metallization of the inner walls of the holes must be done manually, which further slows down the process.

[0017] The object of the present invention is to remedy the aforementioned disadvantages and in particular to develop a shield for a capacitive sensor, a capacitive sensor for uniformity measuring devices and a uniformity measuring device which are simpler, faster and more economical to manufacture than according to the prior art.

[0018] A further object of the present invention is to provide a method for producing a shield for a capacitive sensor which is simpler, faster and more economical to implement than the known methods.

[0019] These and other objects are achieved according to the present invention by producing a shield for a capacitive sensor, a capacitive sensor for uniformity measuring devices and a uniformity measuring device according to independent claims 1, 7 and 8 and by developing a method for producing a shield for a capacitive sensor according to claim 11.

[0020] Further features of the shield for a capacitive sensor, the capacitive sensor for uniformity measuring devices, the uniformity measuring device and the method for producing a shield for a capacitive sensor are the subject of the dependent claims.

[0021] The features and advantages of a shield for a capacitive sensor, a capacitive sensor for uniformity measuring devices, a uniformity measuring device and a method for manufacturing a shield for a capacitive sensor according to the present invention will become even more apparent in the following purely exemplary and non-limiting description with reference to the attached schematic drawings, of which: - Fig. Figure 1 is a schematic perspective view of a shield for a capacitive sensor according to the prior art; - Fig. Figure 2 is a schematic perspective view of a shield for a capacitive sensor according to the invention; - Fig. 3a is a schematic perspective view of a uniformity measuring device according to the invention; - Fig. 3b a view of a detail from Fig. 3a is; - Fig. 4 is a schematic perspective view of a device arranged between the shields of the capacitive sensors of the uniformity measuring device of Fig. 3 arranged plate element; - Fig. 5 is a schematic perspective exploded view of a detail of the uniformity measuring device of Fig. 3a is; - Fig. 6 a schematic perspective view of the detail from Fig. 5 is.

[0022] In the figures, 50 denotes a shield for a capacitive sensor.

[0023] The shield 50 consists of a ceramic body 51 which extends lengthwise along a longitudinal direction X and which has a first primary side 52, a second primary side 53 opposite the first primary side 52, and a plurality of secondary sides 54 lying transversely to the first primary side 52 and the second primary side 53.

[0024] The shield 50 also includes a first metal layer 55 disposed on the first primary side 52 and extending from a first end portion 56 of one of the secondary sides 54 of the ceramic body 51 over part of its length. Therefore, the first metal layer 55 does not extend over the entire first primary side 52 of the ceramic body 51, but is located only at a first end portion 56 thereof.

[0025] The first metal layer 55 is defined or shaped such that it defines a shielding section 55' intended for arrangement at the shielding potential.

[0026] The shield 50 also includes a second metal layer 57 arranged on the first primary side 52 and extending from at least a second end portion 58 of one of the secondary sides 54 of the ceramic body 51 such that it partially surrounds the first metal layer 55. In particular, as shown in Fig. 2, the second metal layer 57 on the first primary side 52 overlaps the first metal layer 55, except at the end of the first primary side 52 adjacent to the secondary side 54, where the first end portion 56 is formed. Advantageously, the first metal layer 55 is continuous between adjacent sides of the shield 50; in particular, the first metal layer 55 is continuous between the first primary side 52 and the secondary side 54 from which the first metal layer 55 extends.

[0027] Furthermore, the second metal layer 57 is arranged at such a distance from the first metal layer 55 that a part of the first primary side 52 remains free between the first metal layer 55 and the second metal layer 57.

[0028] In particular, the first metal layer 55 and the second metal layer 57 never come into contact with each other.

[0029] Furthermore, the second metal layer 57 is defined or shaped such that it defines a shielding section 57' intended for arrangement at the potential of the electrical ground.

[0030] The first end portion 56 is prepared to electrically connect a first electrical conductor or connecting wire 59' to the first metal layer 55, and the at least one second end portion 58 is prepared to electrically connect at least one corresponding second electrical conductor or connecting wire 59" to the second metal layer 57. In this way, by connecting the first electrical conductor or connecting wire 59' to a power source, the shielding portion 55' can be brought to the shielding potential, and by connecting the at least one second electrical conductor or connecting wire 59" to the electrical ground, the shielding portion 57' can be maintained at the electrical ground potential.

[0031] Preferably, the first end portion 56 and the at least one second end portion 58 belong to the same secondary side 54.

[0032] Preferably, the first metallized layer 55 has a supply section 55" extending from the first end section 56 and terminating in the shielding section 55'. In use, the supply section 55" and the shielding section 55' are intended to be arranged at the same shielding potential, one being the extension of the other. In practice, the supply section 55" and the shielding section 55' may be differently shaped. In the particular embodiment of Fig. 2, the supply section 55" has a substantially thread-like, elongated shape, while the shielding section 55' has a more transversely extended shape compared to the supply section 55" and is substantially rectangular.

[0033] With reference to the above and as in Fig. 2, the second metal layer 57 is arranged around each side of the shielding portion 55' of the first metal layer 55, except at the side portion from which the supply portion 55" of the first metal layer 55 extends, so that the shielding portion 55' of the first metal layer 55 can be connected to the first end portion 56.

[0034] Preferably, the shield 50 also comprises a first metallized hollow seat 61 formed in the first end portion 56; the first metallized hollow seat 61 is advantageously suitable for receiving a head portion of the first electrical conductor or lead wire 59'. Furthermore, the first metallized hollow seat 61 is superficially provided with a corresponding third metal layer 62, which is in contact with the first metal layer 55. In this way, electrical contact is established between the first electrical conductor or lead wire 59', the third metal layer 62, and the first metal layer 55; in practice, in this embodiment, the first end portion 56 electrically connects the first electrical conductor or lead wire 59' to the first metal layer 55 by receiving the head portion of the first electrical conductor or lead wire 59' in the first metallized hollow seat 61.

[0035] In this case, the shield 50 also comprises at least one second metallized hollow seat 63 formed in the at least one second end portion 58; the at least one second metallized hollow seat 63 is advantageously suitable for receiving a head portion of the at least one corresponding second electrical conductor or lead wire 59". Each of the second metallized hollow seats 63 is superficially provided with a corresponding fourth metal layer 64 in contact with the second metal layer 57.In this way, electrical contact is established between the at least one second electrical conductor or lead wire 59", the fourth metal layer 64, and the second metal layer 57; in practice, in this embodiment, the at least one second end portion 58 electrically connects the corresponding second electrical conductor or lead wire 59" to the second metal layer 57 by receiving the head portion of the corresponding second electrical conductor or lead wire 59" in the at least one second metallized hollow seat 63.

[0036] Preferably, the shield 50 comprises two second metallized hollow seats 63 formed in two corresponding second end portions 58.

[0037] In the case that the second end sections 58 belong to the same secondary side 54 as the first end section 56, as in the Fig. 2, the two metallized hollow seats 63 can be formed from opposite sides relative to the first metallized hollow seat 61; the second metal layer 57 is, in this way, U-shaped.

[0038] Preferably, the shield 50 also comprises a fifth metal layer (not shown) arranged on the second primary side 53, which extends over part of its length starting from the first end section 56. The fifth metal layer is defined or shaped such that it defines a shielding section (not shown) intended for arrangement at the shielding potential. In this case, the shield 50 comprises a sixth metal layer (not shown) arranged on the second primary side 53, which extends starting from the at least one second end section 58 such that it partially surrounds the fifth metal layer.

[0039] In particular, the sixth metal layer on the second primary side 53 surrounds the fifth metal layer, except at the end of the first second primary side 53, which is adjacent to the secondary side 54, where the first end portion 56 is formed. Advantageously, the fifth metal layer is continuous between adjacent sides of the shield 50, in particular, the fifth metal layer is continuous between the second primary side 53 and the secondary side 54, from which the fifth metal layer extends.

[0040] In particular, the sixth metal layer is arranged at such a distance from the fifth metal layer that a part of the second primary side 53 remains free between the fifth metal layer and the sixth metal layer.

[0041] Furthermore, the sixth metal layer is defined or shaped such that it defines a shielding portion (not shown) intended for arrangement at an electrical ground potential.

[0042] The first end portion 56 is prepared to electrically connect the first electrical conductor or connecting wire 59' also to the fifth metal layer, and the at least one second end portion 58 is prepared to electrically connect the at least one corresponding second electrical conductor or connecting wire 59" to the sixth metal layer.

[0043] In this case, the shield 50 can be used simultaneously in two adjacent capacitive sensors since it has a shielding section 55' on both primary sides 52, 53.

[0044] The fifth metal layer may also have a supply section (not shown) extending from the first end section 56 and terminating in the shielding section. The supply section and the shielding section of the fifth metal layer are intended, in use, to be arranged at the same shielding potential, with one being an extension of the other.

[0045] With reference to the above, the sixth metal layer is arranged around each side of the shielding portion of the fifth metal layer, except at the side portion from which the supply portion of the fifth metal layer extends, in order to allow the shielding portion of the fifth metal layer to be connected to the first end portion 56.

[0046] Preferably, the shielding sections 55', the supply sections 55" and the shielding sections 57' formed on the two primary sides 52, 53 are each identically shaped.

[0047] In the following, reference is made only to the layers and sections formed on the first primary side 52, whereby all considerations are also applicable to the layers and sections formed on the second primary side 53.

[0048] The shield 50 can advantageously be used in a capacitive sensor 70 for uniformity measuring devices.

[0049] In particular, the capacitive sensor 70 for uniformity measuring devices according to the invention comprises two shields 50 spaced apart and arranged in parallel, each shield 50 being connected to a first electrical conductor or connecting wire 59' and to at least one second electrical conductor or connecting wire 59". When using the shields 50 in the capacitive sensor 70, attention is drawn to the importance of the shield section 55", which forces the internal electric field lines to close on the shield section 55", thereby preventing the internal electric field lines from interacting with elements located near the capacitive sensor 70 and thus leading to erroneous detection.

[0050] The capacitive sensor 70 can be used in a uniformity measuring device 80.

[0051] The uniformity measuring device 80 according to the invention comprises a main body 81, at least one capacitive sensor 70 connected to the main body 81 and at least one electrically conductive plate element 82 arranged between the shields 50 of the at least one capacitive sensor 70.

[0052] Advantageously, the plate element 82 is shaped such that it is in contact from opposite sides only with the second metal layers 57 or the sixth opposing metal layers; namely, the at least one plate element 82 is shaped such that it acts as a spacer for the respective shields 50. During normal operation of the uniformity measuring device, it must be ensured that the shields 50 of a capacitive sensor 70 never come into contact with each other and, if possible, remain at a predetermined distance and parallel to each other.

[0053] Preferably, the at least one plate element 82 has two opposite sides, each of which has, in a corresponding position, a stepped portion 83 that projects beyond the first metal layer 55 or the fifth metal layer of the shield 50 that it faces, without contact. The stepped portion 83 is produced, for example, by milling.

[0054] Preferably, the uniformity measuring device 80 comprises a plurality of adjacently arranged capacitive sensors 70, wherein each capacitive sensor 70 shares at least one shield 50 with the adjacent capacitive sensor(s) 70. The shared shields 50 are necessarily provided with shield sections, supply sections, and shield sections on both primary sides 52, 53.

[0055] Preferably, the various shields 50 are arranged at a variable spacing in the uniformity measuring device 80. The spacing between the shields 50 depends on the thickness of the thread running between two adjacent shields 50; the thicker the thread, the greater the spacing between the shields 50 it must traverse.

[0056] In this case, the uniformity measuring device 80 comprises plate elements 82 of variable thickness arranged between the shields 50 in such a way as to change the distance between the shields 50.

[0057] The plate element 82 extends over a length which substantially corresponds to the length of the supply section 55" of the shields 50.

[0058] In the uniformity measuring devices 80 having at least two shields 50 and a plate element 82 arranged therebetween, the first metal layer 55 and the fifth metal layer of the two opposing shields 50 are completely electrically shielded by the respective shield sections 57' due to the effect of the electrical contact made by the plate element 82 with the second metal layer 57 and the sixth metal layer, respectively.

[0059] As in the Fig. 5 and Fig. 6, the first metal layer 55 and the fifth metal layer face the stepped portion 83 such that the supply portions 55" do not come into contact with the plate element 82; in this way, the supply portions 55" are electrically insulated from one another.

[0060] In contrast, the shielding sections 57' of the second metal layer 57 and the sixth metal layer of two consecutive and opposing shields 50 are in contact with the plate element 82 and come into electrical contact with each other, so that the second metal layer 57 and the sixth metal layer with the plate element 82 completely shield the respective supply sections 55". This electrical shielding is comparable to the shielding achieved by a coaxial cable.

[0061] Depending on the thickness of the plate element 82, the stepped section 83 can alternatively be designed as a through-opening 83, as in Fig. 5. In other words, the plate element 82 has a through-opening 83 for particularly thin thicknesses.

[0062] The method for producing a shield 50 according to the invention for a capacitive sensor is described below.

[0063] The procedure includes the following steps: a) providing a ceramic body 51, the ceramic body extending lengthwise along a longitudinal direction X and having a first primary side 52, a second primary side 53 opposite the first primary side 52, and a plurality of secondary sides 54 transverse to the first primary side 52 and the second primary side 53; (b) applying a first metallization to the first primary side to form the first metal layer 55 and the second metal layer 57; c) preparing the first end portion 56 of the ceramic body 51 to electrically connect a first electrical conductor or lead wire 59' to the first metal layer 55; d) preparing the at least one second end portion 58 of the ceramic body 51 to electrically connect at least one corresponding second electrical conductor or connecting wire 59" to the second metal layer 57.

[0064] In case the shield 50 is to be provided with shielding sections 55', supply sections 55" and shielding sections 57' on both primary sides 52, 53, the method steps are carried out on both primary sides 52, 53.

[0065] Preferably, step c) comprises the steps: - Producing a first hollow seat in the first end portion 56 of the ceramic body 51; - Applying a second metallization to the surface of the first hollow seat and in contact with the first metal layer 55, thereby creating the first metallized hollow seat 61.

[0066] In this case, step d) includes the steps: - Producing at least one second hollow seat in the at least one second end portion 58 of the ceramic body 51; - Applying a third metallization to the surface of the at least one second hollow seat and in contact with the second metal layer 57, thereby creating the at least one second metallized hollow seat 63.

[0067] The metallization can be done, for example, by screen printing.

[0068] To fix the metallization, the shield 50 can be placed in an oven in a manner known per se.

[0069] The application of the first electrical conductor or connecting wire 59' and the at least one second electrical conductor or connecting wire 59" is also carried out in a manner known per se, for example by soldering.

[0070] From the present description, the features of the shield, the capacitive sensor, the uniformity measuring device and the method which are the subject of the present invention, as well as the corresponding advantages, are clearly apparent.

[0071] Because the first metal layer and the second metal layer each extend from an end portion of the ceramic body, it is no longer necessary to drill through the ceramic body and manually metallize the holes to electrically connect the electrical conductors or connecting wires to the shielding portion and the shielding portion. According to the present invention, it is sufficient to prepare the end portions to establish the electrical connections.

[0072] If this preparation involves the manufacture of the first and second metallized hollow seats, such seats need not be deep, as they only serve to accommodate the head portions of the electrical conductors or connecting wires. Therefore, the design of such metallized hollow seats is not as critical as that of the holes according to the prior art. The process for manufacturing the shields is therefore simpler, less risky, and less time-consuming and costly, as it does not require any manual processing.

[0073] Since no holes need to be made, no special machining is required to shape the ceramic body.

[0074] The capacitive sensor according to the invention is also safe and easy to install on the uniformity measuring device thanks to the presence of the plate element, which is easy to manufacture and install and at the same time ensures the distance between the shielding sections.

[0075] Finally, it is clear that the shield, the capacitive sensor, the uniformity measuring device, and the method thus conceived are susceptible to numerous modifications and variations, all of which fall within the scope of the invention; furthermore, all details can be replaced by technically equivalent elements. In practice, any materials and dimensions can be used depending on the technical requirements.

Claims

[1] Shield (50) for a capacitive sensor for uniformity measuring devices, the shield (50) comprising: - a ceramic body (51) extending lengthwise along a longitudinal direction X and having a first primary side (52), a second primary side (53) opposite the first primary side (52), and a plurality of secondary sides (54) transverse to the first primary side (52) and the second primary side (53); - a first metal layer (55) arranged on the first primary side (52) and defining a shielding section (55') intended for arrangement at the shielding potential, the first metal layer (55) extending from a first end section (56) of one of the secondary sides (54) of the ceramic body (51) over part of its length; - a second metal layer (57) arranged on the first primary side (52) and defining a shielding section (57') intended for arrangement at an electrical ground potential, wherein the second metal layer (57) extends from at least a second end section (58) of one of the secondary sides (54) of the ceramic body (51) in such a way that it partially surrounds the first metal layer (55), wherein the second metal layer (57) is arranged at a distance from the first metal layer (55) in such a way that a part of the first primary side (52) remains free between the first metal layer (55) and the second metal layer (57);wherein the first end portion (56) of the ceramic body (51) is prepared to electrically connect a first electrical conductor or connecting wire (59') to the first metal layer (55), and the at least one second end portion (58) of the ceramic body (51) is prepared to electrically connect at least one corresponding second electrical conductor or connecting wire (59") to the second metal layer (57); [2] Shield (50) for a capacitive sensor according to claim 1, wherein the first end portion (56) and the at least one second end portion (58) belong to the same secondary side (54). [3] Shield (50) for a capacitive sensor according to claim 1 or 2, wherein the first metallized layer (55) has a supply section (55") extending from the first end section (56) and terminating in the shield section (55'). [4] Shield (50) for a capacitive sensor according to one or more of the preceding claims, comprising: - a first metallized hollow seat (61) formed in the first end portion (56) of the ceramic body (51), the first metallized hollow seat (61) being suitable for receiving a head portion of the first electrical conductor or connecting wire (59'), the first metallized hollow seat (61) being superficially provided with a corresponding third metal layer (62) in contact with the first metal layer (55); - at least one second metallized hollow seat (63) formed in the at least one second end portion (58) of the ceramic body (51), the at least one second metallized hollow seat (63) being suitable for receiving a head portion of the at least one corresponding second electrical conductor or connecting wire (59"), each of the second metallized hollow seats (63) being superficially provided with a corresponding fourth metal layer (64) in contact with the second metal layer (57); [5] Shield (50) for a capacitive sensor according to the preceding claim 4, comprising two of the second metallized hollow seats (63) formed in two corresponding second end portions (58), wherein the second metal layer (57) is U-shaped. [6] Shield (50) for a capacitive sensor according to one or more of the preceding claims, comprising: - a fifth metal layer arranged on the second primary side (53) and defining a shielding section intended for arrangement at the shielding potential, the fifth metal layer (55) extending from a first end section (56) of the ceramic body (51) over part of its length; - a sixth metal layer arranged on the second primary side (53) and defining a shielding section intended for arrangement at an electrical ground potential, wherein the sixth metal layer extends from the at least one second end section (58) of the ceramic body (51) in such a way that it partially surrounds the fifth metal layer, wherein the sixth metal layer is arranged at a distance from the fifth metal layer such that a part of the second primary side (53) remains free between the fifth metal layer and the sixth metal layer, wherein the first end section (56) of the ceramic body (51) is prepared to electrically connect the first electrical conductor or connecting wire (59') to the fifth metal layer, and the at least one second end section (58) of the ceramic body (51) is prepared,to electrically connect at least one corresponding second electrical conductor or connecting wire (59") to the sixth metal layer., [7] Capacitive sensor (70) for uniformity measuring devices, comprising: - two shields (50) according to one or more of the preceding claims, which are spaced apart and parallel to one another, each of the shields (50) being connected to a first electrical conductor or connecting wire (59') and to at least one second electrical conductor or connecting wire (59"). [8] Uniformity measuring device (80), comprising: - a main body (81); - at least one capacitive sensor (70) according to claim 6, which is connected to the main body (81); - at least one electrically conductive plate element (82) which is arranged between the shields (50) of the at least one capacitive sensor (70) and is designed such that it is in contact from opposite sides only with the second metal layers (57) or the sixth opposing metal layers, wherein the at least one plate element (82) acts as a spacer for the respective shields (50). [9] Uniformity measuring device (80) according to claim 8, wherein the at least one plate element (82) has two opposite sides, each of which has, in a corresponding position, a stepped portion projecting beyond the first metal layer (55) or the fifth metal layer of the shield (50) facing it without contact. [10] Uniformity measuring device (80) according to claim 8 or 9, comprising a plurality of said capacitive sensors (70) arranged side by side, wherein each of said capacitive sensors (70) has at least one shield (50) in common with the adjacent capacitive sensor(s) (70). [11] A method for manufacturing a shield (50) for a capacitive sensor for uniformity measuring device according to one or more of claims 1 to 6, comprising the steps: a) providing the ceramic body (51); b) applying a first metallization to the first primary side (52) so that the first metal layer (55) and the second metal layer (57) are produced; c) preparing the first end portion (56) of the ceramic body (51) to electrically connect a first electrical conductor or connecting wire (59') to the first metal layer (55); d) preparing the at least one second end portion (58) of the ceramic body (51) to electrically connect at least one corresponding second electrical conductor or connecting wire (59") to the second metal layer (57). [12] The method of claim 11, wherein step c) comprises the steps of: - producing a first hollow seat in the first end portion (56) of the ceramic body (51); - applying a second metallization to the surface of the first hollow seat and in contact with the first metal layer (55), thereby producing the first metallized hollow seat (61). and wherein step d) comprises the steps: - producing at least one second hollow seat in the at least one second end portion (58) of the ceramic body (51); - applying a third metallization to the surface of the at least one second hollow seat and in contact with the second metal layer (57), thereby producing the at least one second metallized hollow seat (63).

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