Sensor devices for detecting at least one physical variable

Abstract

This invention relates to a sensor device for detecting at least one physical variable, comprising a housing, at least one sensor element disposed within the housing, at least one circuit board disposed within the housing and including a circuit arrangement, and at least one input device disposed on the housing for performing an input operation, the input operation being processed in the circuit arrangement to affect sensor properties. The device is characterized in that, for achieving a touch-sensitive effect, the input device includes an actuation region and a capacitance region, the actuation region being disposed on a wall of the housing and permeable to an electric field, the capacitance region being disposed on the circuit board or formed as part of the circuit board, and wherein the circuit board is disposed within the housing such that the capacitance region is directly below the actuation region.

Description

Technical Field

[0001] The present invention relates to a sensor device for detecting at least one physical variable. Background Technology

[0002] Such sensor devices are used, for example, as position measurement systems. These systems detect, for instance, the position of a working piston along the cylinder axis. The Hall effect is used, for example, to detect this position.

[0003] Such sensor devices are known, for example, from DE 10 2019 203 878 A1. This sensor device includes a sensor circuit board with a first sensor array for detecting a first physical variable and a second sensor array for detecting capacitance, processing means for processing the sensor signals from the first and second sensor arrays, and a sensor housing having a recess therein to receive the sensor circuit board. The second sensor array includes a conductive sensor plate received within the recess and having a contact device with a resilient contact spring. The contact device allows non-positive and conductive coupling between the sensor plate and the sensor circuit board.

[0004] The first sensor array for detecting a first physical variable can be designed to detect, for example, magnetic flux density, magnetic field strength, or temperature. To provide input possibilities, the sensor device includes a second sensor array designed to detect capacitance. This allows for the detection of the operator's intention without the use of moving parts such as microswitches. In this sensor device, a touch-sensitive sensor plate is connected to a sensor circuit board in a complex manner by means of an elastic contact spring, which allows for frictional engagement and conductive coupling between the sensor plate and the sensor circuit board. This design not only requires complex manufacturing and assembly but also necessitates appropriate mounting space for arranging the sensor plate.

[0005] Furthermore, there are sensors that use buttons, for example. These buttons also require a significant amount of space and further structural components. They hinder ever-growing miniaturization. Moreover, mechanical buttons wear down due to moisture / water ingress and must be sealed. In many cases, buttons are so small that tools (such as pins) are still needed to actuate them.

[0006] It is also known that input can be made using a special adjustment tool (e.g., a magnet), which allows different switching states on a switching assembly mounted inside a housing and cooperating with a magnet, without external contact. Optical buttons, resistive buttons, or capacitive buttons on circuit boards specifically designed for this purpose are also conceivable. However, optical buttons need to be protected from external light and dust. Resistive buttons are sensitive to dust and moisture. Capacitive buttons, when placed on circuit boards specifically designed for this purpose, are costly and complicate the construction and manufacturing process.

[0007] Therefore, the object of the present invention is to provide a sensor device in which the user can directly influence the processing of sensor signals in the sensor device, and to overcome the above-mentioned disadvantages. Summary of the Invention

[0008] This objective is achieved by a sensor device featuring the characteristics of this invention. Because the capacitor region is directly disposed on the circuit board or as an integral part of the circuit board, and the circuit board is positioned within the housing such that the capacitor region is directly below the actuation region disposed within the housing wall, a compact and easily implemented structure is achieved. In particular, additional components, such as additional sensor boards, can be eliminated. Conversely, the capacitor region is formed directly on the circuit board or as an integral part of the circuit board.

[0009] This arrangement not only allows for low space requirements but also enables simple, particularly economical, production, and is wear-free compared to mechanical solutions, for example. Furthermore, it features low energy requirements compared to optical solutions. It is also vibration-resistant and corrosion-resistant. Since the circuit board can take virtually any form—e.g., straight, curved, circular, etc.—the sensor area formed on or as part of the circuit board can be easily adapted to curved or circular housing contours.

[0010] A particularly advantageous aspect of the invention specifies that the capacitor region is arranged on the edge of the circuit board, and the circuit board is arranged perpendicular to the actuation region, such that the edge of the circuit board and the capacitor region arranged thereon are located below the contact region. Due to this arrangement of the capacitor region on the edge of the circuit board, no circuit board surface is used to form the capacitor region. Therefore, the entire circuit board surface can be used for circuit layout.

[0011] A particularly advantageous aspect of the invention specifies that a capacitive region is achieved on the edge of the circuit board by metallizing the edge. In this way, additional components, such as metal strips arranged on the edge of the circuit board, can be completely eliminated. Metallization of the side edges is a standard process in circuit board manufacturing and is very inexpensive. Therefore, as in solutions known in the prior art, no additional components are required. Furthermore, the metallized side edges are achieved with much smaller tolerances, which allows for a smaller wall thickness in the actuation region within the housing or housing wall of the sensor device, said actuation region being permeable to an electric field.

[0012] A particularly advantageous aspect of the invention specifies that the housing has an elongated cubic form, with its width less than its height and its height less than its length, such that there are two long, narrow housing surfaces and two long, wide housing surfaces, with the actuation region arranged in the long, narrow housing surfaces, and the circuit board arranged parallel to the long, wide housing surfaces. This housing form is particularly advantageous in the position detection of the cylinder described at the beginning, because this housing can be inserted into a corresponding recess on the cylinder. In this case, the elongated circuit board is mounted somewhat upright in the housing, and its metallized edge is opposite to the long, narrow housing surface in which the actuation region is arranged. As a result, a long actuation region is also achievable, which allows for a variety of corresponding circuit options.

[0013] The actuation region is advantageously larger than the capacitance region, so that the capacitance region is completely located within the actuation region.

[0014] The actuation region is made of a material with a high dielectric constant, which enables reliable capacitive actuation.

[0015] The sensor device can perform various tasks. Specifically, the sensor can be from the group consisting of: magnetic field sensors, acceleration sensors, temperature sensors, pressure sensors, flow sensors, and brightness sensors. The sensor device is particularly advantageous for use with magnetic field sensors to allow the detection of the piston position in a cylinder using the Hall effect as described above. Attached Figure Description

[0016] Figure 1 An isometric view of the sensor device according to the present invention is shown;

[0017] Figure 2 Showing the arrangement in Figure 1 An isometric side view of the circuit board in the sensor device shown; and

[0018] Figure 3 The circuit layout for detecting and evaluating sensor signals is shown. Detailed Implementation

[0019] Sensor devices in Figure 1 The sensor device is schematically shown and can be used, for example, to detect the position of a working piston along the cylinder axis of a cylinder. This sensor device includes a housing 100, which has a substantially elongated cubic form, with its width B less than its height H, and its height H much less than its length L. The cube has a circular end face 105, two long, narrow housing faces 110, and two long, wide housing faces 120. An actuation region 130 is arranged in one of the long, narrow housing faces 110 and is made of a material with a high dielectric constant. The housing itself can be made of a wide variety of non-conductive materials. A circuit board 200 is arranged within the housing 100, similarly having an elongated shape adapted to the size of the housing. Three Hall elements 230 are arranged on the circuit board 200 and are used, for example, to detect the position of the piston in a piston-cylinder unit in which the sensor device is arranged. Furthermore, a switching device (not shown) for processing the sensor signal is arranged on the circuit board 200. The circuit board 200 has metallization 220 on its edges. These edges are arranged opposite the actuation region 130 in the mounted state of the circuit board 200. Here, the circuit board 200 extends parallel to the long and wide outer casing surface 120; it is perpendicular to the long and narrow outer casing surface 110. The metallized edge 220 is located directly below the actuation region 130. The actuation region 130 is larger than the metallized edge 220 of the circuit board 200. The connecting line 210 is used to provide power on one hand and to read sensor data on the other, and leads to the circuit board 200.

[0020] The circuitry used for detecting and evaluating sensor signals is arranged in Figure 3 As shown in the diagram, the operator's finger 310 is positioned above the capacitor region 315. The capacitor region 315 is affected by the approaching finger 310. The resistor 320 serves as ESD protection for the downstream circuitry.

[0021] A sampling capacitor 330 is provided. Reference numeral 300 denotes a sensing controller that detects changes in capacitance of region 315 using the sampling capacitor 330 and translates them into digital information. Here, the known principle of charge transfer acquisition is used. In principle, other methods could also be employed to determine the capacitance change of region 315. The sensing controller 300 can be composed entirely of discrete components, implemented as a single integrated circuit, or integrated into a microcomputer.

[0022] The circuit board 200 is arranged somewhat upright within the housing 100, such that the metallized edge 220 is opposite the actuation region 130. Metallization of the side edges is a standard process in circuit board manufacturing, and its cost is very low. Therefore, an additional circuit board for use as a sensor element is unnecessary. Furthermore, the metallized side edges 220 can be achieved with much smaller tolerances, enabling smaller wall thicknesses for the housing of the position measurement system. The outer edge can be achieved with an accuracy within a few μm, for example, using laser processing. The metallization itself similarly has tolerances within a few μm. Therefore, when overmolding the sensor, much smaller wall thicknesses can be used, as the housing wall only needs to compensate for smaller tolerances. The shorter the distance from the capacitance region, the smaller the capacitance region itself can be while maintaining the same sensitivity.

[0023] Due to the compact structure, power consumption and therefore inherent heat must be minimized. The capacitive area form of a touch-sensitive input device saves power and space, and is particularly suitable for integration into very small position sensors. In addition to damping, humidity in the surrounding environment can be measured via the capacitive area in the form of a metallized edge 220, thereby providing additional condition monitoring information. A further advantage of this solution is that the circuit board can take any form, such as straight, curved, or circular, and therefore can conform to any housing form to a certain extent.

Claims

1. A sensor device for detecting at least one physical variable, comprising a housing (100), at least one sensor element disposed in the housing (100), at least one circuit board (200) disposed in the housing (100) and including a circuit arrangement, and at least one input device disposed on the housing (100) for performing an input operation, said input operation being processed in the circuit arrangement to affect sensor properties. Its features are, To achieve touch sensitivity, the input device includes an actuation region (130) and a capacitance region (220). The actuation region (130) is disposed on the housing wall (110) and is permeable to an electric field. The capacitance region (220) is disposed on the circuit board (200) or formed as part of the circuit board, wherein the circuit board (200) is disposed in the housing (100) such that the capacitance region (220) is located directly below the actuation region (130). The capacitor region (220) is implemented on the edge of the circuit board (200) by metallizing the edge of the circuit board (200).

2. The sensor device according to claim 1, characterized in that, The capacitor region (220) is arranged on the edge of the circuit board (200), and the circuit board (200) is arranged perpendicular to the actuation region (130), such that the edge of the circuit board (200) and the capacitor region (220) arranged therein are located below the actuation region (130).

3. The sensor device according to claim 1 or 2, characterized in that, The housing (100) has the form of an elongated cube, the width (B) of which is less than its height (H), and the height (H) of which is less than its length (L), such that there are two long narrow housing surfaces (110) and two long wide housing surfaces (120), and the actuation region (130) is arranged in the long narrow housing surface (110), and the circuit board (200) is arranged parallel to the long wide housing surface (120).

4. The sensor device according to claim 1 or 2, characterized in that, The actuation region (130) is larger than the capacitance region (220), such that the capacitance region (220) is completely located within the actuation region (130).

5. The sensor device according to claim 1 or 2, characterized in that, The actuation region (130) is made of a material with a high dielectric constant.

6. The sensor device according to claim 1 or 2, characterized in that, The sensor device includes sensors from the group consisting of: magnetic field sensors, acceleration sensors, temperature sensors, pressure sensors, flow sensors, and brightness sensors.

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