Touch field structure for reducing electromagnetic interference

Abstract

Touch field structure for reducing electromagnetic interference, featuring: a touch-sensitive field module (21) with at least one electrode layer (211); and a noise suppression module (23) which forms a layer stack structure with the touchpad module (21), wherein the noise suppression module (23) has a dielectric layer (231) arranged on the touchpad module (21) and a conductive thin-film layer (232) arranged on the dielectric layer (231), wherein the conductive thin-film layer (232) serves as the touchpad surface (201) of the touchpad structure (20), but is not used to generate a touchpad signal, and wherein there is a potential difference between the conductive thin-film layer (232) and the at least one electrode layer (211), wherein the conductive thin-film layer (232) changes its distance to the at least one electrode layer (211) when touched and thereby changes the capacitance value existing between the two.

Description

[0001] The present invention relates to a touch field structure and in particular to a touch field structure designed to reduce electromagnetic interference.

[0002] With advancing technological development, the range of applications for modern touchpad structures has expanded considerably. Such touchpad structures (also called tactile field structures) are now found in industrial automation systems, medical devices, military equipment, vehicle electronics, aerospace engineering, public transportation systems, and a wide variety of outdoor applications.

[0003] However, the applications mentioned often involve operating environments with strong electromagnetic interference. During operation, touch-field structures can be affected by electromagnetic interference (EMI) from other electronic devices. The electromagnetic radiation generated by such devices can lead to instabilities in the touch-field function, cause a reduction in sensitivity, or even result in image errors and display anomalies.

[0004] To ensure the electromagnetic compatibility of electronic, electrical, and electromechanical devices and systems, the U.S. Department of Defense developed the military standard MIL-STD-461. This standard includes a complete test protocol for evaluating both a device's electromagnetic emissions and its susceptibility to electromagnetic interference. The goal is to prevent and control unwanted electromagnetic interference to ensure the operational reliability of military systems.

[0005] Against this background, the central technical challenge for current touch-field structures is to reliably ensure their immunity to electromagnetic interference.

[0006] The invention is based on the objective of avoiding the shortcomings of insufficient interference immunity of conventional touch structures and creating a touch field structure whose ability to suppress electromagnetic interference is reliably ensured.

[0007] This problem is solved according to the invention by a touch-field structure for reducing electromagnetic interference, which has the features specified in claim 1. Further advantageous embodiments of the invention will become apparent from the features of the dependent claims.

[0008] According to the invention, a touch-field structure for reducing electromagnetic interference is provided, comprising a touch-field module with at least one electrode layer and an interference suppression module that forms a layer-stack structure with the touch-field module. The interference suppression module has a dielectric layer arranged on the touch-field module and a conductive thin-film layer arranged on the dielectric layer. The conductive thin-film layer serves as the touch-field surface of the touch-field structure but is not used to generate a touch-field signal. A potential difference exists between the conductive thin-film layer and the at least one electrode layer. Upon contact, the conductive thin-film layer changes its distance from the at least one electrode layer, thereby altering the capacitance value between them.

[0009] According to the invention, the dielectric layer comprises an insulating medium.

[0010] According to the invention, the dielectric layer has several spacer elements distributed in the insulating medium.

[0011] According to the invention, the insulating medium is a gas.

[0012] According to the invention, the insulating medium is an insulating liquid.

[0013] According to the invention, the interference suppression module has a support layer which is arranged on the side of the dielectric layer facing the at least one electrode layer.

[0014] According to the invention, the interference suppression module has at least one adhesive area that connects the support layer to the conductive thin film layer.

[0015] According to the invention, the touch-sensitive field module has several electrode layers.

[0016] According to the invention, the touch-sensitive field module has at least one adhesive layer which connects the several electrode layers together.

[0017] According to the invention, the touch field module has at least one auxiliary support layer which is assigned to one of the several electrode layers.

[0018] According to the invention, the touchpad module has at least one auxiliary interference suppression layer which is assigned to one of the several electrode layers.

[0019] In the embodiment described above, the touch-field structure according to the invention for reducing electromagnetic interference has, in particular, the following features compared to the prior art: The touch-field structure according to the invention comprises an interference suppression module having a dielectric layer and a conductive thin-film layer. The dielectric layer is arranged on the touch-field module, while the conductive thin-film layer is supported by the dielectric layer and lies above the touch-field module, thereby forming the touch-field surface of the touch-field structure. A potential difference exists between the conductive thin-film layer and the at least one electrode layer, which effectively reduces electromagnetic interference on the touch-field module.

[0020] The invention and its embodiments are explained in more detail below with reference to the drawing. The drawing shows: Fig. 1 a schematic layer structure view of a first embodiment of the present invention; Fig. 2 an embodiment of the first embodiment of the present invention; Fig. 3 a schematic layer structure view of a second embodiment of the present invention; Fig. 4 a schematic layer structure view of a third embodiment of the present invention; Fig. 5 a schematic layer structure view of a fourth embodiment of the present invention; Fig. 6 a schematic layer structure view of a fifth embodiment of the present invention; Fig. 7 a schematic layer structure view of a sixth embodiment of the present invention; Fig. 8 a schematic layer structure view of a seventh embodiment of the present invention; and Fig. 9 a schematic layer structure view of an eighth embodiment of the present invention.

[0021] The terms "a" or "an" used in this description serve solely for linguistic simplification and correspond to their usual meaning within the scope of technical protection of this utility model. These terms are to be interpreted as including both the singular and the plural, unless the context clearly indicates otherwise or the quantity is expressly limited. A component described as single may therefore be provided for multiple times.

[0022] The directional terms used in this description, such as "top" or "bottom," serve solely for clarity and refer to the orientation shown in the accompanying figures. These terms do not constitute a restrictive definition of spatial orientation; rather, the components and structures can be used in any position or orientation depending on the practical application.

[0023] With reference to the Fig. 1 to Fig. Section 9 relates to a touch-sensitive field structure 20 comprising a touch-sensitive field module 21 and an interference suppression module 23. The touch-sensitive field module 21 has at least one electrode layer 211, which serves to detect touch by means of capacitive sensor technology. The capacitive detection principle is generally known to those skilled in the art and is therefore not explained further here.

[0024] The interference suppression module 23 and the touchpad module 21 form a layered stack structure, with the interference suppression module 23 arranged above the touchpad module 21. The interference suppression module 23 comprises a dielectric layer 231 and a conductive thin-film layer 232. The dielectric layer 231 is arranged on the touchpad module 21, is electrically insulating, and is not in conductive contact with the touchpad module 21. The conductive thin-film layer 232 is arranged on the dielectric layer 231 and forms a touchpad surface 201 of the touchpad structure 20. The touchpad surface 201 is designed for contact by a conductor 40, for example, a finger. However, the conductive thin-film layer 232 does not generate a touchpad signal. Rather, it reduces the electromagnetic interference of the touch field module 21.Specifically, the touchpad signal refers to a signal that describes the position at which the conductor 40 touches the touchpad structure 20. After contact between the conductive thin film 232 and the conductor 40, the conductive thin film 232 itself does not generate a signal that directly indicates the contact position of the conductor 40. However, this does not preclude the possibility that the conductive thin film 232 generates a signal that can be used to calculate the contact position of the conductor 40. The conductive thin film 232 is electrically separated from the touchpad module 21 by the dielectric layer 231, and a potential difference exists between the conductive thin film 232 and the at least one electrode layer 211.The potential difference can be generated by setting one of the two layers – either the conductive thin-film layer 232 or the electrode layer 211 – to a higher potential and the other to a lower potential. Specific implementation variants include: 1. the conductive thin-film layer 232 is grounded and the at least one electrode layer 211 is subjected to a voltage; or 2. the conductive thin-film layer 232 is subjected to a voltage and the at least one electrode layer 211 is grounded.

[0025] The following explains the functionality of the keypad structure 20. With reference to Fig. 2. The touchpad structure 20 operates in conjunction with a touchpad evaluation chip 30. The touchpad structure 20 is factory-configured such that it is energized but not in contact with the device. In this state, both the at least one electrode layer 211 and the conductive thin-film layer 232 are connected to the touchpad evaluation chip 30. After applying an operating voltage to the at least one electrode layer 211, the touchpad evaluation chip 30 detects a first capacitance value via the at least one electrode layer 211. When the conductive thin-film layer 232 is energized, the touchpad evaluation chip 30 determines a second capacitance value, which arises from the capacitive coupling between the conductive thin-film layer 232 and the at least one electrode layer 211.

[0026] When the conductor 40 touches the touchpad structure 20, the touchpad structure 20 is actuated by the conductor 40, whereby the conductive thin-film layer 232 changes its distance to the at least one electrode layer 211 as a result of the force applied by the conductor 40. The touchpad processing chip 30 then detects a third capacitance value between the conductor 40 and the conductive thin-film layer 232. If this third capacitance value exceeds the sum of the first and second capacitance values, the touchpad processing chip 30 outputs a touchpad signal that describes the contact coordinates of the conductor 40.

[0027] From the foregoing, it follows that the interference suppression module 23 can be combined with the existing touchpad module 21 to form a layered stack structure. The interference suppression module 23 according to the invention improves the conditions for generating the touchpad signal, in particular the relevant capacitance values, so that unwanted electromagnetic waves are filtered out and electromagnetic interference on the touchpad module 21 is reduced. Furthermore, the touchpad structure 20 according to the invention does not require an additional surface protection layer, as is common in conventional touchpad structures. Instead, the interference suppression module 23 of the touchpad structure 20 simultaneously serves as a protective layer for the touchpad module 21.Furthermore, the touchpad structure 20 according to the invention fulfills the test requirements regarding electric field radiation specified in the military standard MIL-STD-461G established by the US Department of Defense. Although the touchpad structure 20 uses capacitive sensor technology for touch detection, it simultaneously exhibits properties characteristic of both capacitive and resistive touchpad structures, such as a soft surface and increased resistance to moisture and water.

[0028] Various embodiments of the present invention are explained below. It should be noted that all embodiments are based on the previously described technical measures and belong to the same technical field.

[0029] With reference to Fig. In one embodiment, the dielectric layer 231 comprises an insulating medium 233. The insulating medium 233 consists of a material that has both insulating and supporting properties and serves to separate the conductive thin-film layer 232 from the at least one electrode layer 211. This prevents a direct electrical current path from forming between the conductive thin-film layer 232 and the at least one electrode layer 211, while still allowing energy transfer between the two layers and maintaining the electrically isolated state. In one embodiment, the insulating medium 233 can be a gas. In another embodiment, the insulating medium 233 can be an insulating liquid.

[0030] With reference to Fig. 1 and Fig. In a further embodiment, the dielectric layer 231 is provided to have several additional spacer elements 234 if the insulating medium 233 alone cannot provide sufficient support. The spacer elements 234 are distributed within the insulating medium 233, are electrically insulating, and also serve to separate the conductive thin-film layer 232 from the at least one electrode layer 211. In one embodiment, the spacer elements 234 can be used in combination with a gas as the insulating medium 233. In another embodiment, the spacer elements 234 can also be used with an insulating liquid as the insulating medium 233.

[0031] In another embodiment, the conductive thin-film layer 232 consists of an indium tin oxide layer [ITO film]. In another embodiment, the interference suppression module 23 has a support layer 235 arranged on the side of the dielectric layer 231 facing the at least one electrode layer 211. The support layer 235 serves to mechanically support the dielectric layer 231 and the conductive thin-film layer 232. In another embodiment, the support layer 235 can consist of transparent glass or be designed as a transparent film. Based on this, the interference suppression module 23 in another embodiment has at least one adhesive area 236.The at least one adhesive area 236 is arranged between the support layer 235 and the conductive thin film layer 232 and extends along the edge region of the support layer 235 and the conductive thin film layer 232 to connect both layers.

[0032] With further reference to the Fig. 1 to Fig. In one embodiment, the keypad structure 20 has an optical adhesive layer 25. The optical adhesive layer 25 is arranged between the keypad module 21 and the interference suppression module 23 and serves to connect the keypad module 21 to the interference suppression module 23. The optical adhesive layer 25 is translucent, so that in an embodiment in which the keypad structure 20 forms a keypad-display module together with a display unit, it does not impair the optical display of the display unit.

[0033] In a further embodiment, with reference to the Fig. 4 to Fig. 6, the electrode layer 211 can be configured as a single layer. The electrode layer 211 has two conductive patterns, each extending in different directions and arranged as two sublayers within the same structural layer. These two conductive patterns correspond to the X-lines and Y-lines commonly used in engineering. If a capacitive change occurs in the two conductive patterns, the touch-field evaluation chip 30 can determine the touch-field coordinates of the conductor 40 based on the position of the respective capacitance change. In a further embodiment, with reference to Fig. 5, the touch-sensitive module 21 can additionally have an auxiliary support layer 212. The auxiliary support layer 212 consists of transparent glass and is arranged below the electrode layer 211 to provide mechanical support for it. In a further embodiment, with reference to Fig. 6, the touchpad module 21 can have an auxiliary interference suppression layer 213 arranged below the electrode layer 211.

[0034] With reference to the Fig. 1 to Fig. 3 In a further embodiment, the touchpad module 21 can have several electrode layers 211. Each of the several electrode layers 211 has a different conductive pattern extending in different directions. One of the several electrode layers 211 corresponds to the X-lines commonly used in the relevant technical field, while another of the several electrode layers 211 corresponds to the so-called Y-lines. In one embodiment, the touchpad module 21 has an adhesive layer 214 for connecting the several electrode layers 211.

[0035] With reference to Fig. In a further embodiment, the touch-sensitive field module 21 is provided with at least one auxiliary support layer 212. The auxiliary support layer 212 serves as additional mechanical support and is assigned to one of the several electrode layers 211. With reference to Fig. In a further embodiment, figure 8 provides that several auxiliary support layers 212 are provided. The several auxiliary support layers 212 are each assigned to one of the several electrode layers 211.

[0036] With reference to Fig. In one embodiment, Figure 7 provides that the touchpad module 21 has at least one auxiliary interference suppression layer 213. The auxiliary interference suppression layer 213 serves as additional shielding against external interference signals and is assigned to one of the several electrode layers 211. With reference to Fig. In a further embodiment, 2, several auxiliary interference suppression layers 213 are provided. Each of the several auxiliary interference suppression layers 213 is assigned to one of the several electrode layers 211.

[0037] In summary, a touch-field structure for reducing electromagnetic interference is disclosed, comprising a touch-field module (21) and an interference suppression module (23), wherein the touch-field module (21) has at least one electrode layer (211), while the interference suppression module (23) forms a layer stack structure with the touch-field module (21) and has a dielectric layer (231) arranged on the touch-field module (21) and a conductive thin-film layer (232) arranged on the dielectric layer (231). The conductive thin-film layer (232) serves as the touch-field surface (201) of the touch-field structure (20) but is not used to generate a touch-field signal. A potential difference exists between the conductive thin-film layer (232) and the at least one electrode layer (211).When touched, the conductive thin film layer (232) changes its distance to at least one electrode layer (211) and thus the capacitance value existing between the two.

[0038] The foregoing examples merely represent preferred embodiments of the present invention and do not serve to limit the scope of protection. All equivalents, variations, or modifications apparent to a person skilled in the art and lying within the scope of protection of the appended claims are therefore to be considered as being covered by the scope of protection of the present invention.

Claims

[1] Touch field structure for reducing electromagnetic interference, comprising: a touch-sensitive field module (21) with at least one electrode layer (211); and a noise suppression module (23) which forms a layer stack structure with the touchpad module (21), wherein the noise suppression module (23) has a dielectric layer (231) arranged on the touchpad module (21) and a conductive thin-film layer (232) arranged on the dielectric layer (231), wherein the conductive thin-film layer (232) serves as the touchpad surface (201) of the touchpad structure (20), but is not used to generate a touchpad signal, and wherein there is a potential difference between the conductive thin-film layer (232) and the at least one electrode layer (211), wherein the conductive thin-film layer (232) changes its distance to the at least one electrode layer (211) when touched and thereby changes the capacitance value existing between the two. [2] Touch field structure for reducing electromagnetic interference according to claim 1, characterized by, that the dielectric layer (231) has an insulating medium (233). [3] Touch field structure for reducing electromagnetic interference according to claim 2, characterized by , that the dielectric layer (231) has several spacer elements (234) distributed in the insulating medium (233). [4] Touch field structure for reducing electromagnetic interference according to claim 3, characterized by , that the insulating medium (233) is a gas. [5] Touch field structure for reducing electromagnetic interference according to claim 3, characterized by , that the insulating medium (233) is an insulating liquid. [6] Touch field structure for reducing electromagnetic interference according to one of claims 1 to 5, characterized by, that the interference suppression module (23) has a support layer (235) which is arranged on the side of the dielectric layer (231) facing the at least one electrode layer (211). [7] Touch field structure for reducing electromagnetic interference according to claim 6, characterized by , that the interference suppression module (23) has at least one adhesive area (236) that connects the support layer (235) to the conductive thin film layer (232). [8] Touch field structure for reducing electromagnetic interference according to one of claims 1 to 5, characterized by , that the touchpad structure (20) has an optical adhesive layer (25) which connects the touchpad module (21) to the interference suppression module (23). [9] Touch field structure for reducing electromagnetic interference according to one of claims 1 to 5, characterized by , that the touch field module (21) has several electrode layers (211). [10] Touch field structure for reducing electromagnetic interference according to claim 9, characterized by , that the touch field module (21) has at least one adhesive layer (214) which connects the several electrode layers (211) together. [11] Touch field structure for reducing electromagnetic interference according to claim 10, characterized by , that the touch field module (21) has at least one auxiliary support layer (212) which is assigned to one of the several electrode layers (211). [12] Touch field structure for reducing electromagnetic interference according to claim 10, characterized by , that the touchpad module (21) has at least one auxiliary interference suppression layer (213) which is assigned to one of the several electrode layers (211).

Images