Mechanical switch design mechanism

Abstract

A mechanical switch design mechanism comprising switch activation, wherein the switch activation is not dependent on electromechanical contact, further comprising an inductance-influencing disturbance element, an inductor with an inductor core, and a recoil force generation mechanism, wherein the disturbance element can be displaced from a retracted position over a distance under a user actuation force against a recoil force generated by the recoil force generation mechanism to be closer to the inductor core and thereby change the inductance of the inductor in a manner related to the displacement path of the disturbance element.

Description

BACKGROUND OF THE INVENTION

[0001] The invention relates to a mechanical switch design mechanism. A keyboard switch of the type manufactured by Cherry, Unionwell, or Kailh is typically an electromechanical device with two terminals that allow for the determination of an open or closed state. This type of switch is binary (1 or 0). Its function indicates a single-point stroke of an actuator and depends on physical contact, which leads to normal wear and tear.

[0002] Optical and magnetic switches can measure and report the travel distance. However, optical switches are expensive, especially when reporting multiple levels, and are susceptible to dust or dirt. Magnetic / Hall-effect switches require a magnet and a Hall-effect sensor for each button. The sensor and magnet are costly. Hall-effect switches are also susceptible to magnetic stray fields. SUMMARY OF THE INVENTION

[0003] A mechanical switch mechanism or switch, e.g., a keypad switch, a microswitch, or another type of switch, according to the present invention comprises an induction coil on a suitable substrate, e.g., a printed circuit board (PCB) or another material such as PET with printed or otherwise formed traces (hereinafter referred to as PCB). The coil is preferably formed by traces in a circular configuration on a layer beneath a mechanical part of the switch. A hole passes through the PCB substantially at the center or core of the coil. The coil is electrically connected to an inductive sensing system. A disturbance element penetrates the hole and, in response to an actuation of the switch by the user, is moved or displaced from a retracted position into the core of the coil.The inductance of the coil changes depending on the degree of displacement of the disturbance element from the withdrawn position.

[0004] The disruptive element is typically preloaded into the retracted position by a spring mechanism or other mechanism to generate recoil force.

[0005] The keyboard switch is used as an example, but this is not a limiting factor. A keyboard switch according to the invention is a contactless device, meaning that no electromechanical contact is required for the switching decision. The inductance varies with the displacement of the interference element, and thus the speed and depth of actuation can be determined by inductive measurements. Decision levels for the switch (1 or 0) can be set for different positions of the interference element relative to the coil. Multiple levels can also be defined and used.

[0006] The extent (the path) of the displacement of the disturbance element is related to the change in inductance. Such a change in inductance can also be related to the rate of displacement of the disturbance element.

[0007] The interfering element that occupies space in the core of the coil can be metal, e.g. copper, iron, etc., which reduces the inductance of the coil, or it can be ferrite or a similar material that increases the inductance.

[0008] It is important that the magnetic flux within the core is evenly distributed. It is possible to use coil windings on both sides of the PCB, with one winding positioned above the other. This increases the homogeneous space of magnetic flux that can be affected by the interfering element. In a PCB with more than two layers, adding more layers for the coil can reduce the coil's outer diameter while maintaining a predetermined inductance, thus reducing potential crosstalk / coupling between adjacent coils located within a predefined area.

[0009] The interference element can be shaped to assist in measuring a long key travel and linearize the relationship between travel and change in inductance. Linearization can also be achieved mathematically. The switch can incorporate a positioning guide, for example, a tube-shaped element aligned with the hole in the PCB. The interference element can be moved back and forth within the positioning guide. The interference element does not have to be circular and can be, for example, square or rectangular.

[0010] In another embodiment, the alignment and position of the switch body and the PCB are achieved by using extrudates, pins, or other features that fit into holes in the PCB. If no positioning tube is required, the interfering element can fill a larger portion of the bore in the inductor. This results in a greater change in inductance because the interfering element penetrates deeper into the core of the inductor or fills a larger portion of the core's volume.

[0011] Some switches incorporate a rod in a central position that guides the switch's movement. The rod is typically made of the same material as the switch body. However, a metal or ferrite interference element may replace the rod or be attached to the rod in a way that affects the inductor's inductance in response to a displacement of the interference element into the coil core, caused by the user actuating the switch.

[0012] In some embodiments, the conductive rod can be used to detect the proximity of a user's finger to a button by operating the induction coil (or another electrode) as a capacitive sensor.

[0013] The switch structure can be combined with a dome-shaped switch plate or a structure that provides a spring action and recoil force. Such a dome structure can also provide tactile feedback (snap) when the switch is pressed beyond a certain depth. The dome structure can be made of metal (e.g., a metal dome plate) or a flexible material such as rubber or silicone.

[0014] Analyzing the displacement curve measured by the inductive sensor allows us to determine when the dome snaps into place. At the moment the dome snaps, the return force decreases, and the displacement inevitably accelerates. This change in the speed of movement is crucial for coordinating the tactile feedback with the switch selection when the switch selection is based on inductive measurements. However, a predetermined change in inductance can also be used to trigger a switching decision; this is further supported by the collapsing action of the dome structure.

[0015] In another embodiment, the interfering element can be a magnet, and a ferrite layer or portion can cover the inductor (or be positioned within the inductor core). As the magnet approaches the ferrite / inductor, the properties of the ferrite change in a way that affects the measured inductance. From this change in the measured inductance, the displacement of the interfering element, i.e., the degree to which the user presses the switch, can be deduced.

[0016] Since only the displacement of the disturbance element in the inductor and in the magnetic / inductive combination can be continuously measured, it is possible to provide an analog equivalent output signal of the switch actuation.

[0017] It is also possible to adjust the switch activation point, as this can be determined purely by a software decision. For example, it may be advantageous to have a very shallow switch activation point for rapid switch operation, i.e., a very light press or a press with a short stroke. On the other hand, a deeper switch level can be chosen to, for example, inhibit or prevent accidental switch selection. According to this invention, the on and off levels of the switch (referred to as switching decisions) can be set at different levels.

[0018] The selectable trigger level feature allows a product to offer context-sensitive keyboard responses with or without user intervention. For example, a game program could automatically select a low trigger level when a shooter operates a pistol, but a low trigger level for a rocket-propelled grenade or pulling the pin on a hand grenade. This is purely an example.

[0019] A word processing program can automatically adjust the key selection level to a metric that determines the user's accuracy or skill. Different keys can have different selection levels depending on the layout and / or another metric, such as hand or finger reach.

[0020] In another embodiment, the key actuation can be configured to artificially shift the zero or rest plane. For example, if a key is pressed repeatedly, the user might not fully release the key before pressing it again. It is possible for the keyboard (or program) control to detect this and, if the key is not fully released, require only a similar or predetermined depress plane, but from the new zero or base plane. That is, the key does not need to be fully released before it can be pressed again, and the required shift plane for the switch actuation remains constant. This process can be repeated until the key reaches its full actuation depth. This functionality can, for example, result in significantly faster switch actuation, such as when shooting in a game.

[0021] In another embodiment, users can set their own preferences for different actions or parts of one or more programs or a game.

[0022] When a switch is touched, resulting in a slight press, and before the press threshold is reached (almost like capacitive touch detection), the program can indicate this to the user via visual (or other) feedback. This feature can be particularly helpful in the dark on a keyboard without backlighting.

[0023] Other methods for mechanical switch construction are also possible, for example, scissor or butterfly designs which, according to this invention, move an interfering element into (or out of) the core of an inductive coil in order to influence the coil's inductance. Such other switch designs can, for example, help or aim to implement low-profile or short-travel keys, such as those used in laptops and notebooks.

[0024] Another application of this invention may be for use in a keyboard switch that utilizes a flexible (e.g., metal, rubber, or silicone) dome to provide or generate the recoil force against a user activation force, and may also provide a tactile snap sensation when the dome is pressed beyond a defined point and then snaps shut (similar to the effect of a mechanical dome plate switch). These domes are known in the prior art. In some prior art applications, the non-metallic dome has a conductive (e.g., graphite) layer in its upper portion, and when the dome snaps shut, it creates an electrical connection on the PCB or other surface on which it is mounted.In another prior art implementation, the dome collapses under user pressure, and then pressure is applied to the layers beneath the dome to create an electrical connection. Both prior art implementations are examples of an electromechanical switch design. According to this invention, it is proposed to provide a metal or ferrite element as a disruptive element in an upper part of the dome made of rubber (or another suitable material). The disruptive element affects the inductance of a coil positioned beneath it when it collapses under user pressure. The disruptive element can be embedded in the dome material, in which case no electrical contact is required. This is advantageous when considering wear that can result from a high number of actuations.

[0025] The interference element is ideally shaped to move into the core of an inductor when the dome collapses, thereby influencing the inductance of an inductor positioned next to the dome. The interference element need not be located in the center of the mechanical switch assembly, but only need to move in relation to the pressure applied during switch actuation.

[0026] Not only can the deformation of the switch be measured, but information about the speed of user actuation and the depth of switch actuation can also be obtained from the inductive measurements. Repeated switch actuations can also be much faster than with electromechanical switches, since the latter require debouncing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention is further described by means of examples with reference to the accompanying drawings, which show: Fig. 1a and Fig. 1b a keyboard switch with a disruptive element in a positioning guide in a retracted position or in an activated state, Fig. 2 a sectional view of a keyboard switch with an off-center positioning pin and a centrally positioned interference element, Fig. 3 A sectional view of a keyboard switch in an activated state with a disruptive element displaced to a maximum through a hole in the PCB, Fig. 4 a bottom view of the keyboard switch showing the PCB, the inductive coil and the positioning pins positioned in the positioning holes in the PCB, Fig. 5 a keyboard with inductive detection, Fig. 6 a low-profile button designed for actuation according to this invention, Fig. 7a and Fig. 7b a dome structure with a flat disturbance element, Fig. 8 a dome with a shaped disruptive element, Fig. 9 a dome structure with additional pressure detection features, and Fig. 10 a ferrite layer between a magnetic interference element and a coil. DETAILED DESCRIPTION OF THE INVENTION

[0028] The following description is intended to provide an understanding of the invention with reference to the accompanying drawings. The description is only exemplary and not exhaustive, as there are other implementations of the invention that fall within the scope of the claims.

[0029] The Fig. 1a and Fig. Figure 1b shows a keyboard switch 10 mounted on a printed circuit board (PCB) 12. An induction coil 14 is formed on the PCB by circular traces. A hole 16 in the center of the coil penetrates the PCB. A positioning guide tube 18 is aligned with and positioned in the hole 16.

[0030] A portion of the switch 10, which is movable in response to a user actuation 20, has a protrusion 22 that moves within the guide tube 18 closer to and into the induction coil 14. This change in position results in a change in the inductance of the coil 14, which can be measured with a connected integrated inductive measuring circuit (not shown). The coil can be located on the underside of the PCB, on the top side, or on both sides. Measuring the inductance and any changes in inductance is readily possible using known methods, which are not described here.

[0031] The displacement of the disturbance element 22 proceeds against the recoil force of a spring 26, which returns the disturbance element to a retracted position when no actuating force is applied by the user.

[0032] The front end 34 of the interfering element 22 can have a flat nose to effect a more abrupt change in inductance from a first value, when the interfering element is just outside the core of the coil, to a second value with the interfering element inside the core of the induction coil. Alternatively, the interfering element can be shaped with a varying cross-section, from a sharp front end 34 over a certain length that widens in diameter, e.g., with a conical shape, to allow a variable change in inductance during the movement of the interfering element over this length. This shape allows for a gradual change in inductance over the desired path, i.e., from minimum interference to maximum interference.

[0033] It is also possible that the disturbance element has a shape that linearly balances the relationship between the change in inductance and the actuation displacement.

[0034] The Fig. 2 and Fig. Figure 3 shows a keyboard switch 10A in the retracted and activated states, which uses the eccentric positioning pins 38 to position the switch on the PCB 12. Fig. Figure 4 shows a bottom view of switch 10A. The interfering element can have a larger diameter than when using the positioning tube guide 18 ( Fig. 1).

[0035] In any embodiment, the interfering element can be attached to the actuator by means of an adhesive, a mechanical fastening arrangement, or in any other practical way.

[0036] Fig. Figure 5 shows a perspective view of a keyboard 40, which includes many switches 44, a switch housing 42, inductive coils 46 under each switch to allow the actuation of each switch to be determined by measuring the inductance of a coil or its change, and electronics (not shown) for measurements and for communication with a computer system. The keyboard can be a standalone external unit or part of a computer, for example in a laptop or notebook.

[0037] A communication processor on the keyboard can also control switch level selections from user preference settings or implement dynamic switch level selections as described above. Level selection can also be controlled by a program (e.g., a game) running on the computer.

[0038] The layer settings can be selected per user or even set per session.

[0039] Fig. Figure 6 is an example of a low-profile switch 600 (laptop keyboard) designed for operation as an inductive switch according to this invention. A PCB 601 on which the switch is mounted may also include an inductive coil 602. The switch is constructed with a housing 603, a mechanism 604, and a cover 606. An element 605, which may be a conductive or ferrite material, is attached to the mechanism 604. When the switch is actuated by a user, the element 605 moves into the core of the coil 602 and thus influences the measured inductance of the coil 602 in relation to the depth to which the key is depressed by the user.

[0040] An LED 607 can be used to provide visual indications for the user. To facilitate visual indications, the cover 606 must be transparent or at least have a transparent portion.

[0041] An integrated circuit for measuring the inductance of coil 602 is not shown, but can be mounted on PCB 601, and this integrated circuit can manage multiple buttons.

[0042] In Fig. Figure 7a shows an example of a structure 710 of type with a flexible (e.g., silicone) dome 700 with a disruptive element 701. This is a side view of a plane passing through the center of a dome with an exemplary form factor. The dome structure is typically spherical when viewed from above. This flexible dome can be considered a substitute for a metal (or other) spring mechanism to generate a recoil force against an actuating force applied by a user and is thus used as part of a mechanical keypad structure.

[0043] The dome 700 is made of a flexible material. The interference element 701 can be attached to the underside of the inner upper part of the dome. For durability, the interference element 701 can also be molded into the material, as indicated by reference numeral 702. As previously described, an interference element made of ferrite or another highly permeable material increases the inductance when it is closer to the inductor, whereas an interference element comprising an electrically conductive material decreases the inductance as it approaches the inductor, depending on its orientation.

[0044] In Fig. 7b The interference element 704 is completely embedded in the material of the dome 700 and indicates the point where no electrical connection is required. When the dome is pushed by the user to overcome the recoil force generated by the dome, the dome sides fold together, and the interference element approaches a surface 706 on which the dome structure is mounted. The interference element then affects the inductance of an inductor 708 located under the dome.

[0045] In Fig. Figure 8 shows an embodiment 820 with a shaped perturbation element 801 that moves into the core of an inductor under a dome 800 when the dome is pressed. The inductor can be a coil 804 on a PCB 806 with a hole 810 in the center into which the perturbation element 801 can fit. The inductance is affected by the movement of the perturbation element into the core of the coil, and the change in inductance can be measured. This is similar to the one described in Fig. 1. Disturbance element and coil arrangement shown. Part 802 of element 801 may be embedded in the dome material.

[0046] In Fig. Figure 9 shows an embodiment 920 which enables the detection of a hard push past the folding of the dome 900. Flexible barrier structures 903 prevent the interfering element 901 from fully entering the core of the inductor (i.e., in a similar construction to that shown in Figure 9). Fig. 8 shown). If sufficient pressure is applied to deform the blocking elements 903, the interfering element 901 moves even closer to the inductor and leads to further changes in the measured inductance.

[0047] The flexible domes can be in many shapes, sizes, or designs and can be used with many different types of mechanical switch constructions, such as scissor or butterfly mechanisms. However, according to this invention, actuation is measured without a Hall effect switch or electrical contact.

[0048] In Fig.Figure 10 shows a switch embodiment 150 using a magnet 151 as a disturbance element, and in which a ferrite material layer 152 is positioned between the disturbance element 151 and a coil 154 or in the core of a coil formed on a PCB 153. When the switch 150 is actuated, the magnet 151 moves closer to the ferrite material 152 and affects the properties of the ferrite material in a way that influences the inductance of the coil 154. For this implementation, no magnetic sensor (typically Hall effect) is required on each switch. The layer 152, or another layer, e.g., made of a plastic material (provided for this purpose), acts as a sealing layer and prevents liquids accidentally spilled onto the switch 150 from reaching and potentially damaging any electronics that may be in contact with the switch and located beneath the layer.

Claims

[1] A mechanical switch design mechanism including switch activation, wherein the switch activation is not dependent upon electromechanical contact, further comprising an inductance affecting perturbation element, an inductor having an inductor core, and a recoil force generating mechanism, wherein the perturbation element is displaceable under a user actuation force against a recoil force generated by the recoil force generating mechanism from a retracted position over a distance to be closer to the inductor core and thereby change the inductance of the inductor in a manner related to the displacement distance of the perturbation element. [2] A mechanical switch construction mechanism according to claim 1, wherein the inductor comprises an induction coil on a carrier, with a hole in the carrier adjacent to the core of the induction coil, and wherein the perturbation element is displaceable under the user actuating force from the retracted position located outside or at one end of the hole into the hole and into the core of the induction coil to change the inductance of the induction coil, and wherein the induction coil is formed by tracks on the carrier, the carrier preferably being a printed circuit board. [3] A mechanical switch construction mechanism according to claim 1 or 2, wherein the perturbation element has a front end and has a cross-sectional area, the cross-sectional area increasing over a predetermined length from the front end. [4] A mechanical switch construction mechanism according to any preceding claim, wherein the mechanism for generating recoil force comprises a flexible, non-electrically conductive dome structure that generates a tactile sensation when the dome structure collapses under user actuation force, and wherein the dome structure includes the perturbation element that is displaceable into the inductor core when the dome structure is depressed. [5] A mechanical switch construction mechanism according to any one of the preceding claims, comprising a keyboard switch and having an inductive measuring circuit for measuring the change in inductance caused by the displacement of the perturbation element, and wherein information of the measurement is used for at least one of the following: for determining the path of movement of a key, the key being used to displace the perturbation element, and the speed of movement of a key, the key being used to displace the perturbation element. [6] A mechanical switch construction mechanism according to any preceding claim, comprising a computer keyboard switch, wherein activation parameters of the switch mechanism are automatically set by a program running on the computer. [7] A mechanical switch construction mechanism according to any preceding claim, comprising a keyboard switch, wherein a switching decision is dynamically changed in response to the activation speed or retraction distance of a key used to displace the perturbation element. [8] A mechanical switch construction mechanism according to any preceding claim, configured such that a user touch causing displacement of the perturbation element is detectable and reported to the user. [9] A mechanical switch construction mechanism according to any one of the preceding claims, comprising a sealing layer positioned beneath the switch mechanism to prevent liquids from coming into contact with the electronics beneath the sealing layer. [10] A mechanical switch construction mechanism according to any preceding claim, wherein the perturbation element is magnetic, the switch construction mechanism comprising a ferrite layer positioned between the perturbation element and the inductor such that displacement of the magnetic perturbation element closer to the ferrite layer affects the inductance of the inductor.

Images