Abstract: Disclosed herein is a support structure of a touch panel. According to the present invention, by implementing a touch panel support structure having the maximum resistance to vibration and warpage transferred to the touch panel by a vibration generating device, it is possible to uniformize a vibration width by minimizing a deviation of vibration displacement for each position of a touch panel and it is possible to safely protect the touch panel by effectively absorbing external shock through a cushion operation of a buffering member.

Abstract: A membrane switch has two membranes. Each membrane includes a substrate section and a tail section extending from the substrate section. Each membrane has a circuit surface and a back surface opposite to each other. The two substrate sections overlap with the two circuit surfaces facing to each other. One of the two tail sections has a bypass portion at least partially avoiding the projection of the other tail section in the normal direction of the other circuit surface. The distal ends of the two tail sections overlap with the two back surfaces facing to each other.

Abstract: A low current switch has a flexible movable contact that can be deflected by an actuator. In some implementations the switch may permit a low current switch to be manufactured using elements of a high current switch without requiring large amounts of precious metal. The flexible movable contact may be arranged as one or more cantilevers that are deflected using a rocking actuator. The actuator interacts with the movable contact in such a way as to provide tactile feedback to an operator comparable to a high current switch having a rigid movable contact. Also described are a set of low and high current switches, components of a low current switch, and a method of manufacturing a low current switch.

Abstract: A device for controlling an electronic apparatus, comprising: a generally flat upper panel; a lower armature of a support with respect to which armature the upper panel can move in a generally vertically downward movement; a switch; and at least two arms for actuating the switch, each arm comprising a first end which bears on the upper panel, a second end which bears on the switch, and an intermediate portion which bears on the armature, in which the arms cooperate with the upper panel and the armature in order to keep the upper panel parallel to a horizontal plane during its vertical movement with respect to the armature.

Abstract: A device includes a substrate, a top touch panel, and an electrode supported by the substrate including a conductive compressible material extending from the substrate to the top touch panel. Another electrode is supported by the substrate and arranged to form an electric field coupling with the electrode including the compressible material. A touch sensitive region is transferred from the substrate to the top touch panel by the compressible material.

Abstract: A multi-mode keyboard for a portable electronic device is provided. The keyboard comprising: a layer of flexible transparent touch sensors for receiving touch input; a layer of flexible output device; and a dome sheet for receiving key click input.

Abstract: A touch panel includes a first substrate having a first conductive layer on one surface; a second substrate having a second conductive layer on a surface on a side facing the first conductive layer; a plurality of first electrodes extending from the first conductive layer; and a plurality of second electrodes extending from the second conductive layer. The first conductive layer is formed of a plurality of parallel strips; and the plurality of first electrodes are formed of a straight portion extending in a predetermined direction, and an inclined portion coupled to the straight portion by being inclined by a predetermined angle with respect to a direction orthogonal to the straight portion. Fading, thickness variation and the like at the time of printing can be prevented and fine patterning can be easily carried out, so that an inexpensive touch panel in which overall miniaturization is achieved can be obtained.

Abstract: A dome sheet structure of a mobile communication terminal may include: a metal dome covering a contact point printed on a printed circuit board; and a light guide film disposed on the metal dome. The light guide film may be bonded with the metal dome in a bonding area, and the bonding area may be an area between two concentric circles having different diameters and centered at a center of the metal dome.

Abstract: A safety hand grip for handlebar operated vehicles utilizes an elongate pressure switch in the form of an elongated strip embedded longitudinally within the wall of the resilient hand grip to actuate the horn. A raised area extending substantially the length of the grip and integral with the wall is situated directly over the switch and serves to locate the elongate switch and to concentrate the force applied by the fingers of the operator and transmit that force directly to the elongate switch. The grip can be rotated so the raised portion is positioned under the operator's fingers according to the gripping preference. Dual sided connectors attached to leads from the elongate switch and interposed between the connectors from the horn and battery and the connectors from the console button present on the vehicle enable the horn to be actuated by both the switch and the button.

Abstract: Input device adhesive techniques are described. A pressure sensitive key includes a sensor substrate having one or more conductors, a spacer layer, and a flexible contact layer. The spacer layer is disposed proximal to the sensor substrate and has at least one opening. The flexible contact layer is spaced apart from the sensor substrate by the spacer layer and configured to flex through the opening in response to an applied pressure to initiate an input. The flexible contact layer is secured to the spacer layer such that at first edge, the flexible contact layer is secured to the spacer layer at an approximate midpoint of the first edge and is not secured to the spacer along another portion of the first edge and at a second edge, the flexible contact layer is not secured to the spacer layer along an approximate midpoint of the second edge.

Abstract: There is provided a switch assembly for an electronic card. The switch assembly is mounted within a housing of the card and comprises a switch member adapted to travel axially relative to the housing between a rest position and an actuated position upon application of pressure on the switch member. An actuation member is positioned adjacent the switch member and adjacent an upper face of the housing. Upon exertion of pressure on the upper face, the pressure also applies on the actuation member, thereby displacing the latter. Displacement of the actuation member in turn transfers the pressure to the switch member to move the latter to the actuated position.

Abstract: An in-mould molding touch module includes a flexible printed circuit having a touch control circuit, and a molding flexible film. The flexible film contains integratedly the flexible printed circuit by an in-mould injecting mode. The flexible film has an outer surface for touch control. The outer surface is configured for being pressed for driving the touch control circuit of the flexible printed circuit to output signals. Therefore, the present touch module is manufactured simply, and has a thin thickness.

Abstract: A dome switch can include a dome mounted to a circuit board and secured by a sheet constructed from a material that is impermeable to air. To allow air enclosed by a volume between the dome and the circuit board to be expelled when the dome is depressed, the sheet can include at least one venting hole through which air can flow to the environment of the switch. To prevent contaminants from accessing the volume between the dome and the circuit board through the at least one venting hole, the dome switch can include a membrane positioned over the venting hole. The membrane can be constructed from a material that is permeable to air, but impermeable to contaminants. In some cases, the membrane can be constructed from a mesh material.

Abstract: A D/A integrated pressure key for a keyboard is shown. A digital signal output first when a pressure is applied on the single key, and then an analog signal output while applying a bigger pressure over the same key. The magnitude of the analog signal output is positively related to the magnitude of the pressure applied on the integrated pressure key.

Abstract: Example embodiments disclosed herein relate to a key including a primary dome, a plurality of second domes, and a first layer. The primary dome is to compress a switch if the primary dome collapses. The first layer is over the primary and secondary domes. The first layer collapses the primary dome and does not engage the secondary domes, if the first layer is pressed substantially levelly or parallel to the rest position.

Abstract: The invention relates to a PCB tact switch, and more particularly, to a PCB tact switch having excellent water resistance because same does not have holes on the top and bottom which are open to the outside, capable of preventing erroneous operation through improved contact point safety, and capable of preventing product disengagement through improved fixing strength by being soldered to a substrate.

Abstract: A push switch includes a case having a recess portion, a first fixed contact placed in the recess portion, and a second fixed contact placed in the recess portion. Furthermore, the push switch includes a dome-shaped movable contact placed in the recess portion and having a center portion facing the first fixed contact with a space therebetween, a protective sheet for covering the recess portion, and a protrusion member fixed to the protective sheet by welding at a convex side of the center portion of the movable contact. The first fixed contact and the second fixed contact are provided at positions that are brought into contact with the movable contact when the movable contact is elastically reversed.

Abstract: A D/A integrated pressure key for a keyboard is disclosed. A digital signal output first when a pressure is applied on the single key, and then an analog signal output while applying a bigger pressure over the same key. The magnitude of the analog signal output is positively related to the magnitude of the pressure applied on the integrated pressure key.

Abstract: A switch includes an insulative case with fixed electrodes and a movable electrode therein. The case includes a first surface configured to contact with a circuit board and a second surface configured to oppose to the circuit board via a gap. The movable electrode moves between a first position for placing the fixed electrodes in a conductive state and a second position for placing the fixed electrodes in a nonconductive state. Each of the fixed electrodes includes a contact terminal which contacts with the movable electrode and an external connecting terminal exposed on the second surface and soldered to a land of a wiring terminal on the circuit board. The external connecting terminal includes a first portion opposed to the land and a second portion connected to the first portion that has an area larger than an area of the first portion.

Abstract: A dome switch device enables electric contact by pressing of a central region or even any other region of a dome sheet formed to extend in a longitudinal direction with the same result regarding the amount of electrical contact. The dome switch device preferably includes a dome sheet extending along a longitudinal direction and having conductivity and a contact module provided on a substrate such that a plurality of both-pole (two-pole) contact portions are arranged alternately along the longitudinal direction of the dome sheet, in which the contact module, when being pressed regardless of where along the dome sheet is pressed, whether being pressed on a central region thereof or any other region other than the central region, electrically contacts the dome sheet with a high quality electrical contact.

Abstract: A switch cover is configured by having a first deformation portion that is connectively provided at a flat surface portion of a cylindrical portion placed to surround a periphery of a switch portion, and deforms by an external stress, a second deformation portion that is connectively provided at a curved surface portion of the cylindrical portion, and deforms by the external stress, and a stress transmitting portion that is connectively provided at the first and the second deformation portions, and transmits a stress having a component in a perpendicular direction to an outer surface of an operation portion main body to the switch portion when the first deformation portion is deformed inward of the cylindrical portion by the external stress.

Abstract: A switch includes a case, fixed electrodes, a movable electrode and a pressing member. The fixed electrodes and the movable electrode are arranged inside the recess. The pressing member is arranged so as to cover at least a part of the recess, and displaces the movable electrode from the second position to the first position by a pressing force from the outside. The pressing member includes a first bent part and a second bent part, and a deforming part disposed therebetween. The deforming part is opposed to the movable electrode with a gap in a state where the movable electrode is in the second position. The deforming part is configured to be flexibly deformed toward the outside of the case in a state where the movable electrode is in the first position in which the fixed electrodes are in a conductive state.

Abstract: A keyboard includes a membrane circuit board, a luminous key, a light-emitting element and a plastic film layer. The luminous key has a keycap with a light-transmissible part. The luminous key is configured for triggering a membrane switch of the membrane circuit board. The light-emitting element is disposed on the membrane circuit board and arranged under the light-transmissible part for emitting a light beam. The plastic film layer is disposed on the membrane circuit board, and includes a convex structure, which is integrally formed with the plastic film layer. The light-emitting element is enclosed by the convex structure. The convex structure has an opening aligned with the light-emitting element. The keyboard of the present invention has enhanced production yield and reduced light leakage.

Abstract: First conductive patterns, which each contain two or more first large lattices electrically connected by a first connection in series in a first direction, are formed on a first transparent substrate, and second conductive patterns, which each contain two or more second large lattices electrically connected by a second connection in series in a second direction perpendicular to the first direction, are formed on a second transparent substrate. As viewed from above, the first conductive patterns and the second conductive patterns are arranged adjacent to each other, and the first connection and the second connection are arranged facing each other. The first large lattices are electrically connected via three or more connection paths in the first connection, and the second large lattices are electrically connected via three or more connection paths in the second connection.

Abstract: There is provided a dome-shaped movable contact piece having a sufficient durability with a long indentation amount and with low indentation pressure, reduced in a bottom thrust feeling, and a dome-shaped movable contact piece fixedly adhering the same dome-shaped movable contact piece to a sheet. The long-stroke dome-shaped movable contact piece comprises a dome-shaped contact piece provided with a click action function, and not less than four L-shaped or triangular slits, wherein apex angle parts of the slits are directed to the central position of the dome-shaped contact piece, a central part of the dome-shaped contact piece and a peripheral part of the dome-shaped contact piece are joined with each other by joining parts each directed radially and having a uniform width. The dome-shaped contact piece is fixedly adhered to the sheet only at necessary parts thereof.

Abstract: An ultra-thin computer input device includes a substrate carrying a circuit layout having sets of comb-like contact portions arranged in a staggered manner, and an outer membrane arranged on the substrate and provided with conducting portions corresponding to the comb-like contact portions of the circuit layout of the substrate and electrically insulative beads located on a part of the bottom side of each conducting portion and stopped against the comb-like contact portions of the circuit layout of the substrate. Because the invention eliminates the use of metal domes, rubber domes or scissor-type linking elements, the thickness and number of component parts of the ultra-thin computer input device can be greatly reduced.

Abstract: Switch assemblies that mitigate stack up variations and methods of making the same are provided. The stack up variations are mitigated by embodiments that use a floating switch design. The floating switch design may eliminate height variations in the stack up by directly mounting an activation assembly to a support bracket. This ensures that the stack up height of the activation assembly and support bracket remain fixed, independent of a flexible printed circuit board (PCB) that may also be secured to the activation assembly. This way, regardless of the thickness of the flexible PCB and any height variations in solder used to secure the flexible PCB to the activation assembly, the stack up height of the activation assembly and support bracket remains fixed.

Abstract: A handpiece for a medical instrumentation device is formed with manually deformable ribs on an outer sleeve. The ribs align with conductive surfaces inside the handpiece that make contact with an internal flexible electronic circuit to activate the device when force is applied to the ribs. Removing the force deactivates the device.

Abstract: This is directed to a dome switch that may prevent liquid from coming into contact with circuit elements of the switch. A deformable dome may include a conductive inner surface region and may be placed over a conductive contact pad such that the dome may deform and the conductive elements may contact each other. At least one sheath may be positioned between the conductive region of the dome and the contact pad positioned below the dome for preventing liquid external to the one or more sheaths from contacting the conductive portions of the switch. In some embodiments, a first sheath may be coupled to the inner surface of the dome about the conductive inner surface region and a second sheath may be coupled to a mounting surface about the conductive contact pad, such that when a user deforms the dome, one of the sheaths may extend into the other sheath.

Abstract: Multiple-pole single-throw dome switch assemblies for electronic devices and methods for creating the same are provided. For example, a switch assembly may include a deformable dome that may have a conductive inner surface. The switch assembly may also include three conductive pads, at least two of which may be positioned underneath the dome. When the dome is deformed, each one of the three conductive pads may be electrically coupled to the conductive inner surface of the dome. When the dome is not deformed, at least one of the three conductive pads may be electrically isolated from the conductive inner surface of the dome.

Abstract: A power switch includes an operating button, an elastic member, a printed circuit board, a support member, and a fixing module. The operating button includes a connecting portion. The elastic member includes a fixing portion and an elastic portion. The printed circuit board includes a main body and a contacting element. The support member includes a base portion and a receiving portion perpendicularly extending from the base portion, and the base portion defines a hole communicating with the receiving portion. The fixing module includes a cover and a contacting member formed on the cover. The connecting portion of the operating button is fixed to the main body and is received in the hole of the support member and the receiving portion. The fixing portion of the elastic member is sandwiched between the connecting portion of the operating button and the main body.

Abstract: A printed wiring board has a first switch contact pattern, a second switch contact pattern, and a cutting portion that cuts a plating bar formed thereon. A metal dome is arranged to be in contact with the first switch contact pattern and allows the first switch contact pattern and the second switch contact pattern to be conductive by being deformed. A first sheet attached to the printed wiring board via an adhesive has a first opening portion formed in a region where the metal dome is arranged and a second opening portion formed in the region where a cutting portion is formed. A second sheet is attached to the first sheet via the adhesive to cover the first opening portion and the second opening portion.

Abstract: Touch sensitive mechanical keyboards and processes for routing the drive and sense lines of the touch sensitive keyboard using patterned dome-switches are provided. The keyboard can include one or more mechanical keys having a touch sensor located within or beneath a keycap. The keyboard can further include a dome-switch beneath each keycap to detect a depression of the corresponding key. The dome-switch can be formed from an elastic (or malleable) material and can include patterned conductive traces within the elastic material. The patterned conductive traces can be used to route stimulation signals and sense signals to and from the touch sensor. In some examples, a first end of the patterned conductive traces can be coupled to the drive and sense lines of the touch sensor and a second end of the patterned conductive traces can be coupled to a flexible circuit or PCB.

Abstract: A touch panel includes a first transparent substrate and a second transparent substrate which are bonded by a frame-shaped seal member. One of a surface of the first transparent substrate and a surface of the second transparent substrate is a protrusion formation surface, and the other is a protrusion facing surface. On the protrusion formation surface, protrusions and a first resistive film are formed. The first resistive film includes first contact regions covering tops of the protrusions. On the protrusion facing surface, a second resistive film that includes second contact regions facing the first contact regions is formed. The protrusion formation surface or the protrusion facing surface includes a void region where the resistive film is not formed. Insulating spacers regulate a given distance between the first contact regions and the second contact regions. A space between the first and second transparent substrates contains an insulating liquid.

Abstract: An electronic component comprises a flexible planar substrate which is substantially non-stretchable, the substrate having at least two slits arranged to allow first and second portions of the substrate lying in the same plane to be moved apart, the first portion of the substrate supporting a region of conductive material.

Abstract: A key assembly which is configured to provide improved click feeling to a user and an electronic device having the same are provided. The key assembly includes a key body of elastic materials and contact projections, each of the contact projections which is protruded and formed from the key body and presses a switch device spaced apart from the key body by a gap providing a certain interval, wherein the key body is installed such that a contact surface of each of the contact projections is in contact with and pushed back by a certain distance by a pre-loading force of the switch device.

Abstract: Certain example embodiments of this invention relate to large-area transparent conductive coatings (TCCs) including carbon nanotubes (CNTs) and nanowire composites, and methods of making the same. The ?dc/?opt ratio of such thim films may be improved via stable chemical doping and/or alloying of CNT-based films. The doping and/or alloying may be implemented in a large area coating system, e.g., on glass and/or other substrates. In certain example embodiments, a CNT film may be deposited and then doped via chemical functionalization and/or alloyed with silver and/or palladium. Both p-type and n-type dopants may be used in different embodiments of this invention. In certain example embodiments, silver and/or other nanowires may be provided, e.g., to further decrease sheet resistance. Certain example embodiments may provide coatings that approach, meet, or exceed 90% visible transmission and 90 ohms/square target metrics.

Abstract: A press key includes: a base plate; a bordering plate disposed above and coupled to the base plate, and formed with a through hole; a keycap movable between a raised position and a pressed position, the keycap being configured to pass through the through hole to be partially exposed from the bordering plate when the keycap is at the raised position; a circuit board disposed between the keycap and the base plate; an elastic restoring unit disposed between the keycap and the circuit board; a limiting mechanism disposed between the bordering plate and the keycap; and a guiding mechanism disposed between the keycap and the base plate to guide the movement of the keycap.

Abstract: A multi-directional switch includes switches, a wiring board having an electrode, a pressure-sensitive body disposed over the electrode, a detection pin disposed on the upper surface of the pressure-sensitive body, and an operating body configured to push the detection pin and the switches by being tilted. The degree of a pushing force exerted by the operating body onto the detection pin changes the contact resistance between the pressure-sensitive body and the electrode. The multi-directional switch enables an electronic apparatus connected thereto to perform diverse functions by reflecting changes in the contact resistance.

Abstract: An operator control apparatus of an electronic domestic appliance contains an operator control panel on that side of the operator control apparatus which faces a user, at least one electrically conductive sensor element on that side of the operator control panel which is averted from the user, and a printed circuit board with at least one electrically conductive contact area which is arranged on that side of the printed circuit board which faces the operator control panel so as to be associated with the at least one sensor element. In this case, the at least one sensor element and the at least one contact area of the printed circuit board are connected to one another by an adhesive which is electrically conductive at least in the connection direction.

Abstract: In an electronic device, a speaker attaching section 17 which is vertically open with respect to a circuit board 10 and into which a speaker 16 is press-fitted is integrally formed on a contact sheet 13 arranged on the circuit board 10 provided inside an upper case 8. Therefore, the speaker 16 can be easily attached in a manner that sound therefrom does not leak, simply by the speaker 16 being press-fitted into the speaker attaching section 17 of the contact sheet 13. Accordingly, in the present invention, the structure of the speaker section 6 is simple and the number of its components is small, whereby the thickness of the speaker section 6 can be reduced. In addition, sound generated by the speaker can be favorably and reliably emitted from the speaker attaching section 17 to the outside of the upper case 8, without chattering noise being generated.

Abstract: A touch input device includes: a film that extends from a bulging portion bulging upward to a flat surface; a first detection region that is formed in the bulging portion and detects coordinates in a first direction and a second direction intersecting with the first direction in response to a touch to a surface of the film by an object; and a second detection region that detects a touch without detecting the coordinates in response to a touch to the surface by the object in a region other than the first detection region.

Abstract: Multiple-pole single-throw dome switch assemblies for electronic devices and methods for creating the same are provided. For example, a switch assembly may include a deformable dome that may have a conductive inner surface. The switch assembly may also include three conductive pads, at least two of which may be positioned underneath the dome. When the dome is deformed, each one of the three conductive pads may be electrically coupled to the conductive inner surface of the dome. When the dome is not deformed, at least one of the three conductive pads may be electrically isolated from the conductive inner surface of the dome.

Abstract: A transparent conductive film comprising a transparent film base material, a resin layer having a fine uneven geometrical structure, and a transparent conductive thin film laminated on the film base material through the resin layer, wherein the surface of the transparent conductive thin film has an average centerline roughness (Ra) of 0.11 to 0.18 ?m, the maximum height (Ry) of 0.9 to 1.6 ?m and the average distance between peaks (S) of 0.05 to 0.11 mm. The film can prevent the formation of a Newton's ring and shows satisfactory durability (particularly, pen input durability) and satisfactory display property without buzzing.

Abstract: A touch panel with a built-in display device has No. 1 sensor lines (120) and No. 2 sensor lines (150), which are both formed by a third conductive film and extend in horizontal and vertical directions, respectively. Therefore, the No. 1 sensor lines (120) are configured by single uninterrupted conductors so as to prevent short-circuit where the No. 1 sensor lines (120) cross the No. 2 sensor lines (150). The No. 2 sensor lines (150) are configured by pairs of conductors (151, 152) separated by spaces (SP), so as to sandwich the No. 1 sensor lines (120) therebetween. In addition, pad portions (370) are provided above the spaces (SP), so as to electrically connect the pairs of conductors (151, 152) of the No. 2 sensor lines (150). In this manner, the touch panel with a built-in display device is provided capable of preventing short-circuit of wiring conductors formed in the same layer, thereby increasing the degree of freedom in wiring layout.

Abstract: Input device adhesive techniques are described. A pressure sensitive key includes a sensor substrate having one or more conductors, a spacer layer, and a flexible contact layer. The spacer layer is disposed proximal to the sensor substrate and has at least one opening. The flexible contact layer is spaced apart from the sensor substrate by the spacer layer and configured to flex through the opening in response to an applied pressure to initiate an input. The flexible contact layer is secured to the spacer layer such that at first edge, the flexible contact layer is secured to the spacer layer at an approximate midpoint of the first edge and is not secured to the spacer along another portion of the first edge and at a second edge, the flexible contact layer is not secured to the spacer layer along an approximate midpoint of the second edge.

Abstract: Input device adhesive techniques are described. A pressure sensitive key includes a sensor substrate having one or more conductors, a spacer layer, and a flexible contact layer. The spacer layer is disposed proximal to the sensor substrate and has at least one opening. The flexible contact layer is spaced apart from the sensor substrate by the spacer layer and configured to flex through the opening in response to an applied pressure to initiate an input. The flexible contact layer is secured to the spacer layer such that at first edge, the flexible contact layer is secured to the spacer layer at an approximate midpoint of the first edge and is not secured to the spacer along another portion of the first edge and at a second edge, the flexible contact layer is not secured to the spacer layer along an approximate midpoint of the second edge.

Abstract: An input device includes a printed circuit board for outputting a signal, a supporting base fixed on the printed circuit board, a metal dome switch installed on the printed circuit board, and a cap pivoted to the supporting base. A protrusion is formed on an end of the cap for contacting against the printed circuit board when the cap is not pressed down. The cap pivots relative to the supporting base when the cap is pressed down. An actuator is further formed on the cap and disposed on a side of the metal dome switch. The actuator of the cap presses down the metal dome switch to actuate the metal dome switch when the cap is pressed down.

Abstract: A test body for use in determining moisture content in a laminated insulation of a power transformer by measuring a dielectric frequency response of the test body. The test body has a laminated structure of the same material as the laminated insulation, and has a shape and a size to obtain moisture content characteristics that resembles the moisture content characteristics of the laminated power transformer insulation. The test body further includes electrodes, which are embedded in the laminated structure.

Abstract: To prevent debris from entering the volume between a dome and contacts of a dome switch, a dome can include a channel providing a remote path through which air can be vented. In particular, the channel can extend from the dome to a location within an electronic device that is known to be or expected to be contaminant free (e.g., a region of the device that does not include any interfaces communicating with the device environment). The channel can be defined from components of the dome switch including, for example, as a channel bound by spacer walls between a flex circuit and a film layer. The channel can include an opening for venting the dome switch. In some embodiments, the dome switch can include a protective film applied over the opening in the channel. The protective film can be selected to allow air to flow through, but to prevent contaminants or particles from reaching the channel opening.