Switch mechanism

Abstract

The utility model relates to a switch mechanism, which comprises an interference component, wherein the interference component can be displaced into a core of an inductor, so as to change the inductance of the inductor in a manner related to the degree of displacement of the interference component.

Description

Technical Field

[0001] The utility model relates to a switch mechanism, in particular to an inductive user interface switch, and more particularly to a keyboard switch. Background Art

[0002] Keyboard switches of the type produced by Cherry, Unionwell or Kailh are typically electromechanical devices with two connections that allow the switch to be determined to be open or closed. This type of switch is binary (1 or 0). Its operation indicates a single point distance of travel of the actuator and relies on physical contact that causes normal wear and tear.

[0003] Optical and magnetic switches can measure and report distance traveled. However, optical switches are expensive, especially for reporting multiple levels, and are easily affected by dust or dirt. Magnetic / Hall effect switches require a magnet and Hall effect sensor for each key. Sensors and magnets are expensive. Hall switches are also susceptible to stray magnetic fields. Utility Model Content

[0004] A switch according to the present invention (e.g., a keyboard switch, a micro switch, or other switch type) includes an inductive coil on a suitable carrier (e.g., a printed circuit board (PCB) or other material with printed or otherwise formed traces, such as PET (hereinafter simply referred to as PCB)). The coil is preferably formed by traces in a circular configuration on a layer below the mechanical portion of the switch. A hole passes through the PCB substantially in the center or core of the coil. The coil is electrically connected to an inductance measurement system. An interfering member penetrates the hole and moves or shifts from a retracted position into the core of the coil in response to a user actuating the switch. The inductance of the coil changes relative to the degree of displacement of the interfering member from the retracted position.

[0005] The interfering member is typically biased to the retracted position by means of a spring mechanism or another push-back force generating mechanism.

[0006] A keyboard switch is used as an example, but not limiting. The keyboard switch according to the utility model is a contactless device, that is, the switch decision does not require electromechanical contacts. The inductance varies with the displacement of the interference member, and thus the speed and depth of actuation can be determined based on the inductance measurement results. The decision level of the switch (1 or 0) can be set for different positions of the interference member relative to the coil. Multiple levels can also be determined and used.

[0007] The extent (distance) of the displacement of the interfering element is related to the change in inductance. This change in inductance may also be related to the speed of displacement of the interfering member.

[0008] The interfering member that occupies space within the core of the coil may be a metal such as copper, iron, etc. that reduces the inductance of the coil, or it may be a ferrite or similar material that increases the inductance.

[0009] It is important that the magnetic flux inside the core is evenly distributed. It is possible to use coil windings on both sides of the PCB, with one winding superimposed on the other. This increases the even space of magnetic flux that can be affected by interfering components. In PCBs with more than two layers, adding more layers to the coil can reduce the outer diameter of the coil while maintaining a predetermined inductance and therefore reduce possible crosstalk / cross coupling between adjacent coils assembled in a predetermined area.

[0010] The interference member may be shaped to assist in measuring long key travel and to linearize the relationship between travel and change in inductance. The linearization may also be done mathematically. The switch may include a locating guide, e.g. in tubular form, which aligns with a hole in the PCB. The interference member may be able to move back and forth inside the locating guide. The interference member need not be circular and may be, e.g., square or rectangular.

[0011] In various embodiments, alignment and positioning of the body of the switch and the PCB is accomplished using extrusions or pins or other formations that fit into holes in the PCB. In such cases where no positioning tube is required, the interfering member may fill a greater proportion of the hole in the inductor. This results in a greater change in inductance because the interfering member penetrates deeper into the core of the inductor or fills a greater proportion of the volume of the core.

[0012] Some switches include a rod located in a central position that guides the movement of the switch. The rod is typically made of the same material as the body of the switch. However, a metal or ferrite interference member may replace the rod or be attached to the rod in a manner that affects the inductance of the inductor in response to the interference member being displaced into the core of the coil, such movement being caused by the user actuating the switch.

[0013] In some embodiments, the conductive bar can be used to sense the proximity of a user's finger to a key by operating the inductive coil (or another electrode) as a capacitive sensor.

[0014] The switch structure may be combined with an arch switch plate or structure that can provide a spring action and push-back force. Such an arch structure may also provide tactile feedback (snap) when the switch is pressed beyond a certain depth. The arch structure may be metal (e.g., a metal arch plate) or a flexible material such as rubber or silicone, for example.

[0015] By analyzing the displacement curve measured with the inductive sensor, it is possible to determine when the arch clicks, because at the moment the arch clicks, the opposing force is reduced and the displacement is accelerated without change. If the switch selection is done using the inductance measurement, this change in movement speed is important for adjusting the tactile effect and the switch selection. However, a predetermined change in inductance can also be selected to make the switching decision; this is assisted by the collapse effect of the arch.

[0016] In another embodiment, the interfering member may be a magnet, and a ferrite layer or ferrite portion may cover the inductor (or be positioned inside the inductor core). When 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 member, i.e., the degree to which the user has pressed the switch, can be derived.

[0017] Since the interfering member displacement in the inductor alone and in the magnetic / inductive combination can be measured continuously, it is possible to provide an analog equivalent output signal of the switch actuation.

[0018] It is also possible to adjust the switch activation point, since this can be determined entirely by software decisions. For example, having a very shallow switch activation point, i.e. a very light press or a press with a short travel, may be advantageous for fast switch operations. On the other hand, a deep switch level may be selected, for example, to inhibit or prevent accidental switch selection. According to the invention, the on and off levels of the switch (called switching decision) can be set at different levels.

[0019] Using the selectable level feature, it is possible for a product to provide context sensitive keyboard response with or without user intervention. For example, a program for a game may automatically select a shallow trigger level when the shooter is operating a pistol, but a deep trigger level for a rocket propelled grenade or pulling the pin on a hand grenade. This is purely exemplary.

[0020] The word processing program may automatically adjust the key selection level based on some metric that determines the user's accuracy or proficiency. Different keys may have different selection levels based on layout and / or another metric, such as hand / finger reach.

[0021] In another embodiment, the key operation may be adjusted to artificially shift the zero level or rest level. For example, when a key is repeatedly pressed, the user may not fully release the key before pressing it again. It is possible that the keyboard (or program) controller detects this and only requires a similar level or predetermined level of pressing if the key is not fully released, but starting from the new zero level or base level, i.e., before the key can be pressed again, the key will not need to be fully released, and the required shift level for switch activation is constant. This can be repeated until the key reaches its full operating depth. This method of operation can, for example, result in much faster switch operation, such as for shooting in games.

[0022] In another embodiment, users may set their own preferences for different actions or portions of the program(s) or game.

[0023] If touching the switch results in a slight depression, and before reaching the selected level of depression (almost like capacitive touch detection), the program can indicate this to the user via visual (or other) feedback. This feature may be especially useful in the dark, on keyboards without backlighting.

[0024] Other mechanical switch construction methods are also possible, for example, a scissor-type or butterfly-wing-type implementation according to the present invention moves the interference member into (or out of) the core of the inductor coil to affect the inductance of the coil. Such other switch configurations may, for example, assist or be intended to implement low-profile or low-travel keys, such as those used in, for example, laptop computers and notebook computers.

[0025] A further application of the utility model can be used in a keyboard switch that utilizes a flexible (e.g., metal, rubber, or silicone) arch to provide or generate a push-back force against a user activation force, and can also provide a click tactile sensation when the arch is pressed beyond a predetermined point and then collapses (similar to a mechanical arch plate switch effect). These arches are well known in the art. In some prior art cases, a non-metallic arch has a conductive (e.g., graphite) layer inside the top portion, and when the arch collapses, it causes an electrical connection on the PCB or other surface on which it is mounted. In another prior art embodiment, the arch collapses under user pressure, and then pressure is applied to the layer below the arch to form an electrical connection. Both of these prior art cases are examples of electromechanical switch constructions. According to the utility model, it is suggested to have a metal or ferrite portion in the top portion of the rubber (or applicable material) arch as an interference member. When the interference member collapses under user pressure, the interference member affects the inductance of the coil positioned below it. The interference member may be embedded in the dome material and therefore no electrical contact is required. This is beneficial when considering the wear that may be caused by a large number of actuations.

[0026] The interference member is ideally shaped to move into the core of the inductor when the arch collapses, and in this way influence the inductance of the inductor located adjacent the arch.The interference member need not be located in the center of the mechanical switch construction; it only needs to move relative to the switch activation depression.

[0027] Not only can the deformation of the switch be measured, but also the speed of the user actuation and the depth of the switch actuation information can be extracted from the inductance measurement. Repeated switch activations can also be much faster than with electromechanical switches due to the debounce requirements of electromechanical switches. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention is further described by way of example with reference to the accompanying drawings, in which:

[0029] Figure 1a and Figure 1b 10 and 11 illustrate a keyboard switch with an interfering member inside a positioning guide in a retracted position and in an activated state, respectively,

[0030] Figure 2 is a cross-sectional view of a keyboard switch having an off-center locating pin and having a centrally located interfering member,

[0031] Figure 3 is a cross-sectional view of a keyboard switch in an activated state, wherein the interfering member is displaced to the maximum extent through the hole in the PCB,

[0032] Figure 4 is a view of a keyboard switch from below, showing the PCB, the inductor coil, and the locating pins positioned inside the locating holes in the PCB,

[0033] Figure 5 shows an inductive sensing keyboard,

[0034] Figure 6 A low profile key configured to operate in accordance with the present invention is shown.

[0035] Figure 7a , Figure 7b An arched structure with a flat interfering member is shown,

[0036] Figure 8 An arch with a shaped interference member is shown,

[0037] Fig. 9 shows an arched structure with additional pressure sensing features, and

[0038] Fig.10 A ferrite layer is shown between the magnetic interference member and the coil. DETAILED DESCRIPTION

[0039] The following description will provide an understanding of the present invention with reference to the accompanying drawings. This description is only exemplary and not exhaustive, as there are other embodiments of the present invention that fall within the scope of the claims.

[0040] Figure 1a and Figure 1b The keyboard switch 10 is shown mounted to a printed circuit board (PCB) 12. An inductor coil 14 is formed by a circular trace on the PCB. A hole 16 in the center of the coil penetrates the PCB. A positioning guide tube 18 is aligned with and positioned within the hole 16.

[0041] The portion of the switch 10 that is movable in response to user actuation 20 includes an interference member 22 that moves closer to and into the inductor coil 14 within the guide tube 18. This change in position causes a change in the inductance of the coil 14, which can be measured with a connected inductance measurement integrated circuit (not shown). The coil can be formed on the underside or on the upper side or on both sides of the PCB. Measurement of inductance and changes in inductance can be easily achieved using known techniques not described herein.

[0042] The displacement of the interference member 22 opposes the push-back force of the spring 26 which returns the interference member to the retracted position in the absence of a user actuation force.

[0043] The leading end 34 of the interference member 22 may be flat-headed to provide a more abrupt change in inductance from a first value when the interference member is just outside the core of the coil to a second value when the interference member is inside the core of the inductor coil, or the interference member may be shaped to have a varying cross-section, becoming wider in diameter over a particular length starting from a sharp leading end 34, such as having a tapered shape to allow for a variable change in inductance during travel of the interference member over that length. Such a shape allows for a gradual change in inductance over a desired distance, i.e., from minimal interference to maximum interference.

[0044] It is also possible that the interfering member has a shape that linearizes the relationship between the change in inductance and the actuation displacement.

[0045] Figure 2 and Figure 3 The keyboard switch 10A is shown in an activated state and a retracted state, utilizing an over-center detent pin 38 to locate the switch on the PCB 12 . Figure 4 1 is a plan view of the switch 10A from below. The interference member may have a larger diameter than if the positioning tube guide 18 (FIG. 1) is used.

[0046] In any embodiment, the interference member may be attached to the actuator by means of an adhesive, by means of a mechanical fastening arrangement, or in any other practical manner.

[0047] Figure 5 is a perspective view of a keyboard 40 comprising a number of switches 44, a switch housing 42, an inductive coil 46 beneath each switch (which enables the actuation of each switch to be determined by means of a measurement of the inductance of the coil or a change thereof), and electronics (not shown) for measuring and for communicating with a computer system. The keyboard may be a separate external unit, or may be part of a computer, such as in a laptop or notebook computer.

[0048] The communication processor on the keyboard can also control the switch level selection according to user preference settings, or implement dynamic switch level selection as described above. The level selection can also be controlled by a program (e.g., a game) running on the computer.

[0049] The level setting may be selected on a per user basis, or may even be determined on a per session basis.

[0050] Figure 6 600 (laptop keyboard) is an example of a low profile switch 600 suitable for operation as an inductive switch according to the present invention. The PCB 601 on which the switch is mounted may also include an inductive coil 602. The switch consists of a housing 603, a mechanism 604 and a cover 606. The mechanism 604 has been attached to a member 605 which may be a conductive or ferrite material. When the switch is actuated by the user, the member 605 moves into the core of the coil 602 and in this way affects the measured inductance of the coil 602 which is related to the depth to which the user presses the key.

[0051] LED 607 can be used to provide visual indication to the user. In order to facilitate visual indication, cover 606 must be transparent or at least have transparent parts.

[0052] An integrated circuit for measuring the inductance of the coil 602 is not shown, but may be mounted on the PCB 601, and the integrated circuit may handle a plurality of keys.

[0053] exist Figure 7a , an example of a flexible (e.g., silicone) arch 700 type structure 710 with an interference member 701 is shown. This is a side view of a plane cut through the middle of an arch of exemplary dimensions. The arch structure is typically spherical when viewed from the top. Such a flexible arch can be viewed as replacing a metal (or other) spring mechanism to generate a push-back force against a user's actuation force, and thus it is used as part of a mechanical key structure.

[0054] The arch 700 is made of a flexible material. An interference member 701 may be attached to the bottom of the inner top portion of the arch. The interference member 701 may also be molded into the material for durability - as indicated by reference numeral 702. As previously described, an interference member made of ferrite or another high permeability material will increase the inductance when it is close to the inductor, while an interference member comprising a conductive material will reduce the inductance when it is close, depending on the orientation.

[0055] exist Figure 7b In the embodiment of the present invention, the interference member 704 is completely embedded in the material of the arch 700, and emphasizes that no electrical connection is required. When the user presses the arch to overcome the push-back force generated by the arch, the arch side collapses and the interference member moves closer to the surface 706 on which the arch structure is mounted. The interference member then affects the inductance of the inductor 708 placed under the arch.

[0056] exist Figure 8 8, an embodiment 820 is shown with a shaped interference member 801 that will move into the core of an inductor under the arch 800 when the arch is pressed. The inductor can be a coil 804 on a PCB 806 that has a hole 810 in the middle into which the interference member 801 can fit. The effect of the interference member moving into the core of the coil is sensed and the change in inductance can be measured. This is similar to the interference member and coil arrangement shown in FIG. 1. A portion 802 of the member 801 can be embedded in the arch material.

[0057] exist Fig. 9 , an embodiment 920 is shown that allows detection of a forceful press resulting in collapse of the arch 900. The flexible barrier structure 903 prevents the interfering member 901 from fully entering the core of the inductor (i.e., in a manner similar to Figure 8 When sufficient pressure is applied to deform the blocking member 903, the interfering member 901 will move even closer to the inductor and will cause a further change in the measured inductance.

[0058] The flexible arch may have many shapes, sizes or forms and may be used with many different types of mechanical switch configurations such as scissor or butterfly mechanisms. However, according to the present invention, actuation is measured without the need for a Hall switch or electrical contacts.

[0059] exist Fig.10, a switch embodiment 150 is shown using a magnet 151 as an interference member, and in which a layer 152 of ferrite material is positioned between the interference member 151 and the coil 154, or in the core of the coil formed on a printed circuit board 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 manner that affects the inductance of the coil 154. This embodiment does not require a magnetic sensor (typically a Hall sensor) at each switch. Layer 152 or another layer of, for example, plastic material (provided for this purpose) acts as a sealing isolation layer and prevents fluids that may accidentally splash onto the switch 150 from reaching and then possibly damaging electronic equipment that may or may not be related to the switch and is located below the layer.

Claims

1. A switch mechanism comprising a switch activation portion that does not rely on electromechanical contact, and further comprising an interference member that affects inductance, an inductor having a core, and a push-back force generating mechanism, wherein: The interference member is displaceable from a retracted position by a distance under a user actuation force against a push-back force generated by the push-back force generating mechanism to be closer to the inductor core and thereby change the inductance of the inductor in a manner related to the distance of displacement of the interference member.

2. The switch mechanism according to claim 1, wherein: The inductor comprises an inductor coil on a carrier having a hole in the carrier adjacent to the core of the inductor coil, and wherein the interference member is capable of being displaced from the retracted position located outside the hole or at one end of the hole into the hole and into the core of the inductor coil under the user actuation force to change the inductance of the inductor coil, and wherein the inductor coil is formed by traces on the carrier, which is optionally a printed circuit board.

3. The switch mechanism according to claim 1, wherein: The interfering member has a front end portion, and has a cross-sectional area that increases over a predetermined length from the front end portion.

4. The switch mechanism according to claim 1, wherein: The push-back force generating mechanism comprises a flexible, non-conductive arch-like structure which generates a tactile sensation when the arch-like structure collapses under the user actuation force, and wherein the arch-like structure comprises the interference member which is capable of being displaced into the core of the inductor when the arch-like structure is depressed.

5. The switch mechanism of claim 1, comprising a keyboard switch, and comprising an inductance measurement circuit to measure the change in inductance caused by the displacement of the interference member, and wherein, The measured information is used for at least one of: determining a distance of movement of a key used to displace the interfering member; and the speed of movement of the key used to displace the interfering member.

6. The switch mechanism of claim 1 comprising a computer keyboard switch, and wherein: The activation parameters of the switch mechanism are automatically set by a program running on the computer.

7. The switch mechanism of claim 1, comprising a keyboard switch, and wherein: The switching decision changes dynamically in response to the speed of activation or the distance of retraction of the key used to displace the interfering member.

8. The switch mechanism of claim 1, configured such that a user touch causing displacement of the interference member is detectable and reported to the user.

9. The switch mechanism of claim 1, comprising a sealing barrier positioned below the switch mechanism to prevent fluid from contacting electronic equipment below the sealing barrier.

10. The switch mechanism according to claim 1, wherein: The interference member is magnetic, and the switching mechanism includes a ferrite layer positioned between the interference member and the inductor such that the displacement of the magnetic interference member proximate to the ferrite layer affects the inductance of the inductor.

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