Abstract: Provided is a key switch that enables sufficiently enhancement of the rigidity of a key top. A key switch includes a support plate; a key top disposed on the support plate; a link configured to link the key top with the support plate; a switch; a first arm disposed on a back surface of the key top between the link and a first short-side end of the key top, and extending in a long-side direction of the key top; a second arm disposed on the back surface of the key top between the link and a second short-side end of the key top, and extending in the long-side direction of the key top; and a reinforcement plate mounted on the key top. The reinforcement plate comprises a short-side part extending in the short-side direction of the key top between the first arm and the second arm.

Abstract: A keyswitch includes a base, a keytop, and first and second support members rotatably intersecting with each other. The keytop has an engaging slot having a rotation space and an opening. The first support member has a first pivot shaft pivoted to the engaging slot and a first connecting mechanism movably connected to the base. When the first pivot shaft is passing through the opening, the engaging slot squeezes the first pivot shaft to cause deformation of a groove of the first pivot shaft so as to make the first pivot shaft have a first size. When the first pivot shaft enters the rotation space, the amount of deformation of the groove decreases to make the first pivot shaft have a second size greater than the first size and a gap of the opening, so that the first pivot shaft could be constrained in the engaging slot.

Abstract: A key structure of a keyboard device includes a scissors-type connecting member and a base plate. The base plate includes a base plate fixing hook, a base plate sliding hook and a stopping structure. The entrance of the base plate fixing hook and the entrance of the base plate sliding hook face the same side. Due to the configurations of the base plate, the scissors-type connecting member can be easily assembled within the base plate fixing hook and the base plate sliding hook. In addition, the scissors-type connecting member can be fixed on the base plate by using the base plate fixing hook and the stopping structure.

Abstract: Described herein are techniques related to a leveled touchsurface with planar translational responsiveness to vertical travel. Examples of a touchsurface include a key of a keyboard, touchpad of a laptop, or a touchscreen of a smartphone or tablet computer. With the techniques described herein, the touchsurface is constrained to remain in a level orientation while a user presses the touchsurface like a button or key. Also, with the techniques described herein, a planar-translation-effecting mechanism imparts a planar translation to the touchsurface while it travels vertically (e.g., downward) as the user presses the touchsurface. This Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: A flat press button is provided. The press button includes a base plate, a link member, and a cap. The link member is disposed on the base plate. The cap, having an embossed strip and a flange, pivots at the link member, wherein the embossed strip and the flange are formed at the opposing sides of the cap, and the embossed strip and the flange are operated in a pivotal swinging manner around a pivot axis to abut the base plate alternatively.

Abstract: Methods and apparatus for a touchsurface assembly such as a key assembly are described. The touchsurface assembly includes a sheet metal component having ramps formed therein and a keycap having ramp contacting features and a touchsurface for receiving a press force that moves the keycap toward a pressed position. The ramp contacting features contact at least one of the ramps in the sheet metal component while the keycap moves toward the pressed position, the ramps guiding the keycap to move in a second direction orthogonal to the press direction as the keycap moves from the unpressed position toward the pressed position.

Abstract: The key assembly comprises a keycap having a touchsurface for receiving a press force that moves the keycap from an unpressed position toward a pressed position. The keycap has first and second ramp contacting features comprising first and second angular protrusions. The first and second angular protrusions have first and second protrusion angles relative to first and second side portions of the keycap (respectively). The key assembly also comprises a base having first and second ramps that contact the first and second ramp contacting features and guide the keycap in the press direction and the second direction as the keycap moves from the unpressed position toward the pressed position. The base has first and second angular features configured to contact the first and second angular protrusions of the first and second ramp contacting features (respectively) to resist rotation of the keycap as the keycap moves toward the pressed position.

Abstract: A key switch structure capable of reducing the height of a key switch, reducing the number of components, and reducing manufacturing costs. The key switch structure includes: a key top; first and second linking mechanisms and adapted to support the key top; a membrane sheet having a contact point portion; a back plate disposed below the membrane sheet and having a function to guide light; and an LED sheet having an LED as a light emitting element disposed thereon, wherein the LED is disposed to be adjacent to the back plate.

Abstract: An electronic device includes a panel, a base, a button, and a balance bar. The panel defines an opening. The base is fixed to a rear side of the panel. A switch and a resilient resisting portion are mounted to a front surface of the base. The button is sandwiched between the panel and the base. The button is partially received in the opening. Two pivot portions are formed a rear side of the button. The balance bar includes a first bar abutting against the resisting portion, two second bars respectively extending from opposite ends of the first bar, and two feet respectively extending from distal ends of the second bars to pivotably connect the pivot portions. When the button is pressed, the balance bar restricts the button to just move linearly to the switch.

Abstract: A keyswitch mechanism having reduced key rattle and a keyboard having reduced key rattle. A rattle suppression mechanism may be formed on a portion of the scissor mechanism or on a portion of the keycap. The rattle suppression mechanism is configured to maintain force on the portion of the scissor mechanism abutting the keycap.

Abstract: A scissors-type connecting member includes an inner frame and an outer frame. The inner frame includes a pivot rod. The pivot rod includes a curved edge and two flat slant surfaces. The outer frame includes a pivot hole, an entrance, and a guiding surface. The pivot hole has a flat bottom surface. The entrance is located beside the pivot hole. The guiding surface is disposed under the entrance. For assembling the scissors-type connecting member, the pivot rod of the inner frame is moved into the pivot hole along the guiding surface. When the inner frame is rotated relative to the outer frame, the two flat slant surfaces of the pivot rod are respectively stopped by the bottom surface of the pivot hole and the guiding surface. Consequently, a rotating angle of the inner frame relative to the outer frame is limited.

Abstract: Push button switch assembly, in particular for insertion in a control panel of a domestic appliance, the push button switch assembly comprising at least one push button and a frame for receiving the at least one push button, wherein the push button has a push button cap, whose top wall or rather upper side is to be manipulated by a user, and an actuating element, in particular an actuating pin, for actuating a switch, especially a micro switch, of a circuit board arranged underneath the push button switch assembly upon actuation of the push button cap, wherein the push button cap is provided with spring legs resting on a frame bottom and counteracting the actuation of the push button cap, characterized in that at least two spring legs are provided, which are formed in a rotationally symmetric or in an axially symmetric arrangement at the push button cap.

Abstract: A friction device, keypad assembly and portable electronic device are disclosed. In one embodiment, there is provided a keypad assembly for a portable electronic device, comprising: a keypad having a number of keys each having an actuator post attached to a back side thereof; a circuit board; a light guide located between the keypad and the circuit board, the light guide defining a number of holes which provide paths for respective actuator posts to travel through to contact respective electrical switches on the circuit board; and at least one friction device located in one of the holes of the light guide, the friction device providing a physical barrier limiting movement of the actuator post in a direction normal to a direction of actuation, the friction device applying friction to at least one side of the actuator post and resisting movement of the actuator post in the direction of actuation.

Abstract: In a key switch, a base is disposed under a keycap. A frame has a receiving space for accommodating the keycap, and the receiving space is defined with a first dimension, a second dimension and a third dimension, and any two of the first, second and third dimensions are perpendicular to each other. A guiding mechanism is disposed between the keycap and the base, and configured to guide the keycap in response to an external force exerted on the keycap to move in substantially parallel to the frame with a first displacement in the first dimension, a second displacement in the second dimension and a third displacement in the third dimension.

Abstract: A key structure including a bottom portion, a keycap, an elastic element and a positioning unit is provided. The keycap includes a plurality of fixing portions. The elastic element is configured between the bottom portion and the keycap. The positioning unit is fixed on the bottom portion and is assembled with the fixing portions. The keycap moves relative to the bottom portion via the positioning unit.

Abstract: A keycap structure includes a reinforcement element and a keycap body. The reinforcement element includes two long segments and two short segments. The keycap body includes plural fixing parts and two protruding parts. The plural fixing parts are used for fixing two ends of each long segment of the reinforcement element. The two protruding parts are used for pushing the two short segments of the reinforcement element, so that the reinforcement element is subjected to deformation. Consequently, the reinforcement element generates a reacting force to push against the bilateral sides of the keycap body. Under this circumstance, the top surface of the keycap body is formed as a downwardly-concave arc-shaped surface, so that the shape of the keycap structure is effectively corrected.

Abstract: The present invention provides a keyboard preventable keycaps from breaking off, which comprises a keyboard main body, and a limit board fixed to the keyboard main body. The keyboard main body comprises a base board, a thin film circuit board mounted on the base board, an elastic body mounted above the thin film circuit board, a scissors structure, and a keycap. The center of the scissors structure is provided with a hollow part. The elastic body is located above the thin film circuit board and in the hollow part at the center of the scissors structure. The keycap is located on the elastic body. The scissors structure is mounted to the keycap and passes through the thin film circuit board to be moveably mounted to the base board. The keycap comprises a top surface and side surfaces connected with the top surface, and the side surface is provided with a locking part extending outwards therefrom.

Abstract: A key switch device including a key top; a pair of link members connected to the key top and interlocked with each other to guide a vertical motion of the key top; a switch mechanism including a membrane sheet switch capable of opening and closing a contact section of an electrical circuit in accordance with the vertical motion of the key top; a flexible thin film sheet attached to the membrane sheet switch; and a housing attached to the thin film sheet, the housing adapted to connect the link members to the thin film sheet.

Abstract: Key stabilization techniques for a key assembly or keyboard are provided. In one embodiment, a key assembly includes a keycap having a touch surface for receiving a press force that moves the keycap from an unpressed position toward a pressed position. The key assembly also includes a base having a planar-translation effecting mechanism supporting the keycap to guide the keycap in the press direction and the second direction as the keycap moves from the unpressed position toward the pressed position. A key stabilization mechanism positioned in the keycap, the base or both the keycap and the base configured to the stabilize the keycap so that the touch surface remains substantially planar while the keycap moves from the unpressed position toward the press position to resist tilt of the keycap and rotation of the keycap about an axis in the press direction as keycap moves toward the pressed position.

Abstract: A thin press button is provided. The press button includes a base plate, a link member, a cap, and at least one stopper. The link member, having a sliding recess, is disposed on the base plate. The cap pivots on the link member. The stopper has a first end and a second end, wherein the first end pivots on the cap and the second end is slidably disposed in the sliding recess.

Abstract: An input device with swing operation includes a supporting frame, a flexible printed circuit installed on the supporting frame for outputting a signal, a supporting base fixed on the supporting frame, a cap pivoted to the supporting base, and a hook respectively pivoted to the supporting base and the cap. An inclined angle is formed between the hook and the supporting frame when the cap is not pressed down. The hook and the cap pivots relative to the supporting base when the cap is pressed down. The input device further includes a resilient component disposed between the flexible printed circuit and the cap for being pressed by the cap to actuate the flexible printed circuit when the cap is pressed down.

Abstract: A keyswitch structure includes a base plate, a keycap, a lift mechanism, and a balance link. The lift mechanism connects between the keycap and the base plate such that the keycap can move up and down relative to the base plate. The balance link is formed substantially in a U-shaped profile. The middle portion thereof is rotatably disposed on the base plate; the two ends thereof are respectively formed in an L-shaped profile and rotatably inserted into two slot structures on the keycap or the lift mechanism or both. Compared with a conventional balance link formed in an n-shaped profile connecting a keycap and a base plate, the invention provides more diverse structural connections, conducive to structural miniaturization. Furthermore, a support of the lift mechanism includes a protrusion capable of being blocked by a limitation structure disposed on the base plate for controlling the rotation angle of the support.

Abstract: There is provided a key switch structure including: a plate shaped key top; a link mechanism supporting the key top such that the key top can be depressed; a membrane sheet comprising a contact point portion; a back plate supporting the link mechanism and adhered to the membrane sheet; a plurality of holder members insert molded onto the back plate and supporting the link mechanism; and a resilient member provided between the key top and the membrane sheet, the resilient member being compressed by depressing of the key top and pressing the contact point portion to make a continuity.

Abstract: The present invention relates to a key structure and a keyboard having the same. The key structure includes a seat, a conductive membrane disposed on the seat, a scissor assembly, a light source, and a cap. The seat has a plurality of protruding hooking portions. At least one conducting section is defined on the conductive membrane away from the central portion thereof. The collapsible scissor assembly is arranged between the seat and the cap. The key structure has at least one protrusion arranged above the corresponding conducting section. A rubber element having a hole formed on the top portion thereof is disposed centrally on the conductive membrane. The light source is arranged beneath and covered by the rubber element. The cap is disposed on the scissor assembly. The protrusion may be arranged on the side portion of the scissor assembly or the undersurface of the cap.

Abstract: A push button-type switch device includes a pair of fixed contacts, an operable member to be pushed, an actuating member elastically deformable upon the operable member being pushed, a movable contact which short-circuits the pair of fixed contacts due to elastic deformation of the actuating member, and a limiting part arranged to limit a direction in which the operable member moves and making the operable member move in a fixed orientation. The limiting part includes a pair of link members that engage with each other, one ends of the link members rotatably supported by the base portion, and the other ends thereof slidably supported by the operable member. This produces a good click irrespective of a position where the operable member is operated.

Abstract: In a push-button switch, a mark for conveying information to a user is disposed on a portion of a front surface of a push-button for operating a switch main body. A light-guiding plate is disposed between the switch main body and the push-button. A mark diffusing portion that diffuses injected light is disposed on a portion of the light-guiding plate that faces the mark. A mark light source portion injects light into the light-guiding plate so as to be directed toward the mark diffusing portion.

Abstract: A press key includes: a base unit having a metal plate; a position-limiting unit formed with a through hole, the metal plate and the position-limiting unit defining an accommodating space therebetween; a keycap movable between a raised position and a pressed position and including a cap body that corresponds in position to the through hole, and a flange member that extends outwardly from and around the cap body and that abuts against the position-limiting unit when the keycap is at the raised position; and an elastic restoring unit including a scissors-type lever that is connected pivotally to the keycap and the position-limiting unit.

Abstract: A key that includes a body with an optically transmissive or light permeable region and an optical film coupled to or carried by the light permeable region. The key also includes a resilient structure coupled to the body. The key can be assembled or coupled to, or disposed relative or adjacent to, a display screen. The key also includes a switch actuator (e.g., an electromechanical switch actuator or contact element). Displacement of the key, more specifically the body of the key, displaces the switch actuator for actuating a switch. The resilient structure is configured to bias the body at a first position. The body can be actuated or displaced from the first position to a second position for effectuating corresponding displacement of the switch actuator and actuation of the switch. The resilient structure provides or establishes a positive tactile feedback upon user-directed or user-controlled actuation or displacement of the body.

Abstract: Systems and apparatuses are disclosed that enable ultrathin keyboards and the storing keys of an associated physical keyboard to a storage position. The systems comprise a keycap, a keyswitch mechanism coupled to the keycap, a translatable base frame and a spring mechanism to bias the keycap into an operating position. The biasing mechanism may be an arch-shaped spring mechanism or a magnetic biasing mechanism. A portion of the biasing mechanism may be coupled to the base frame. The base frame is translatable between a first position in which the biasing mechanism imparts a force to bias the keycap into the operating position and a second position in which the portion of the biasing mechanism is repositioned such that the force to bias the keycap is at least partially eliminated. A control member may be provided to translate natural user movement into movement of the base frame for collapsing the keyboard.

Abstract: A key structure with a scissors-type connecting member is provided. The key structure includes a base plate, a scissors-type connecting member, and a keycap. The scissors-type connecting member includes a first frame and a second frame. The first frame includes a rotating shaft and an extension structure. The extension structure is extended from a first sidewall of the first frame to a ring-shaped periphery of the rotating shaft for enhancing a structural strength of the rotating shaft. The second frame includes a receiving recess for accommodating the rotating shaft and the extension structure.

Abstract: A key structure with a scissors-type connecting member is provided. The key structure includes a base plate, a scissors-type connecting member, and a keycap. The scissors-type connecting member includes a first frame and a second frame. The first frame includes a rotating shaft and an extension bulge. The second frame includes a receiving recess and a position-limiting cavity. For combining the first frame with the second frame, the rotating shaft is inserted into the receiving recess and the extension bulge is inserted into the position-limiting cavity. Consequently, a rotating range of the extension bulge is limited.

Abstract: A scissors-type connecting member includes an inner frame and an outer frame. The inner frame includes a pivot rod. The pivot rod includes a curved edge and two flat slant surfaces. The outer frame includes a pivot hole, an entrance, and a guiding surface. The pivot hole has a flat bottom surface. The entrance is located beside the pivot hole. The guiding surface is disposed under the entrance. For assembling the scissors-type connecting member, the pivot rod of the inner frame is moved into the pivot hole along the guiding surface. When the inner frame is rotated relative to the outer frame, the two flat slant surfaces of the pivot rod are respectively stopped by the bottom surface of the pivot hole and the guiding surface. Consequently, a rotating angle of the inner frame relative to the outer frame is limited.

Abstract: A key for user input having superior tactile qualities. The key is suspended by a magnetic field force to improve the smoothness of motion. Two compact interleaved members link a keycap to a key base to provide highly precise parallel travel with reduced tilt and flexion, and improved durability.

Abstract: A keyboard device including a lower cover, an upper cover for covering the lower cover and a keyboard module is provided. The lower cover has a plurality of hook structures, and the keyboard module includes a plurality of key caps and a plurality of scissor-type connecting elements. The plurality of hook structures are connected with the plurality of scissor-type connecting elements, and the plurality of scissor-type connecting elements are connected with the plurality of key caps. As a result, the lower cover is able to connect with the plurality of key caps without an additional base plate such that the cost of the keyboard device can be decreased and the volume of the keyboard device can be reduced.

Abstract: A key mechanism can include one or more butterfly hinges. Each butterfly hinge includes a double wing design operative to move between a depressed position and non-depressed position. Hinged coupling mechanisms couple respective arms of the wings together.

Abstract: A lightweight radio/CD player for vehicular application includes a case and frontal interface formed of polymer based material molded to provide details to accept audio devices and radio receivers, as well as the circuit boards required for electrical control and display. The case and frontal interface are of composite structure, including an insert molded electrically conductive wire mesh screen that has been pre-formed to contour with the molding operation. The wire mesh provides shielding and grounding of the circuit boards via exposed wire mesh pads and adjacent ground clips.

Abstract: Keyboard keys are outfitted with alignment features whose configuration, placement and geometry on a key serve to allow the key to automatically self-locate when the key returns from a pressed down, accessed, position, to its home, resting, position. In this manner, keyboards can be designed with keys with minimal keycap gaps that reduce the perceptible variance in the keycap spacing to be ascetically pleasing with minimal manufacturing costs.

Abstract: A link structure can include an outside link member and an inside link member. Shaft holes can be formed in respective inner lateral sides of the outside link member and face each other across a first opening portion. First stopper members can be arranged on the respective inner lateral sides, and each have a first inclined face and a first stopper surface. The outside link member can be elastically deformable based on a pressure applied to the first inclined surfaces that increases a distance between the shaft holes. The inside link member can include a second opening portion, link rotational shafts that are disposed in the shaft holes, and second stopper members each having a second inclined surface and a second stopper surface. The inside link member can be elastically deformable based on a pressure applied to the second inclined surfaces that decreases a distance between the link rotational shafts.

Abstract: A side button structure includes a housing with switches, and a button assembly moveably fixed on the housing; the button assembly includes a flexible pin and at least one pressing blocks, the flexible pin passing through the pressing blocks. Pressing the button assembly enables the flexible pin to deform, the button assembly to move to the housing, and the pressing blocks to attach to the switches.

Abstract: A key for user input having superior tactile qualities. The key is suspended by a magnetic field force to improve the smoothness of motion. Two compact interleaved members link a keycap to a key base to provide highly precise parallel travel with reduced tilt and flexion, and improved durability.

Abstract: A keyswitch and a keyboard are provided. A top plate of a keycap of the keyswitch, for being pressed and decoration, and a frame including groove bodies, for linking with a supporting mechanism, are separated into two components such that the top plate may be implemented as a plate structure with much thinner thickness while maintaining its strength, and the frame with the groove bodies is attached to the top plate via insert molding or adhering. The frame and the top plate form the keycap, in which the groove bodies at the frame and the top plate form sliding slots or engaging slots in cooperation with the supporting mechanism. The thickness of the keycap can be substantially reduced and meanwhile maintain the necessary stroke of the keyswitch and the strength of the keycap. The keyboard having the keyswitches is made possible for further miniaturized with thinner thickness.

Abstract: A keypad assembly includes a first keypad element including a first frame element, first elastic elements connecting with the first frame element, keycaps swingably connected to the first frame element via the first elastic elements, and pressing elements protruding downward from the keycaps, and a second keypad element including a second frame element, second elastic elements connecting with the second frame element, keycaps swingably connected to the second frame element via the second elastic elements, and pressing elements protruding downward from the keycaps.

Abstract: A keyswitch, disposed on a base plate, includes a keycap and a scissors-like supporting structure. The scissors-like supporting structure is disposed on the base plate and supports the keycap. The scissors-like supporting structure includes a first supporting member and a second supporting member. The first supporting member includes a first engaging shaft and a second engaging shaft respectively engaged with the base plate and the keycap. The second supporting member is pivotally connected to the first supporting member and includes a third engaging shaft and a fourth engaging shaft respectively engaged with the base plate and the keycap. A line connected between the centers of gravity of the first and second engaging shaft is not perpendicular to the first and second engaging shaft. A line connected between the centers of gravity of the third and fourth engaging shaft is not perpendicular to the third and fourth engaging shaft.

Abstract: A key structure of a keyboard of the present invention includes a base board and a scissors structure mounted on the base board. The base board is provided with a groove, and a pair of clasps extends upwards from opposite two sides of the groove. The scissors structure includes a first frame and a second frame rotationally connected with the first frame. One end of the first frame is provided with a first rotation spindle, and the first rotation spindle is rotationally connected with the clasps and abuts against the edge of the groove opposite to the clasps. In the present invention, the first rotation spindle abuts against the edge of the groove, which is good for the first rotation spindle being mounted in position to the clasps while assembling the scissors structure, can avoid side slip, and makes the inner structure of the key more stable.

Abstract: An electronic device includes a housing and a power button assembly mounted on the housing. The housing defines an assembly hole and an assembly portion around the assembly hole, and the assembly portion includes a side wall. The power button assembly includes a pressing button received in the assembly hole, a printed circuit board, and a support plate connected to the printed circuit board. The support plate is fixed on the housing, such that the printed circuit board is positioned opposite the pressing button. The support plate includes a plurality of positioning portions bent towards the printed circuit board along an imaginary outline corresponding to the side wall, respectively, and the positioning portions are inserted in the assembly portion and abut the side wall correspondingly.

Abstract: A keypad assembly includes a support member, a key switch, a keycap and a resilient member. The key switch is fixed on the support member, and includes a triggering portion. The keycap is located opposite to the triggering portion. The support member and the key switch are located between the keycap and the resilient member. The resilient member interconnects the keycap and the support member. The resilient member is elastically deformed via resisting the triggering portion when the key switch is not triggered.

Abstract: A illuminant keyboard device includes a bottom frame having a plurality of latch parts, a plurality of keying units disposed on the bottom frame, a membrane switch interposed between the bottom frame and the keying units, a light guide plate interposed between the membrane switch and the bottom frame, a least a light source disposed on predetermined position of the light guide plate, a plate interposed between the membrane switch and the light guide plate and a light-shielding plate interposed between the membrane switch and the keying units. The light guide plate has a plurality of first holes and the plate has a plurality of second holes, the diameter of each of the first holes is larger than the diameter of each of the second holes.

Abstract: A key structure with a scissors-type connecting member is provided. The scissors-type connecting member includes a first frame and a second frame. The first frame includes a rotating shaft and a pushing bulge. After the first frame is stacked on the second frame, if the second frame may be pushed by the pushing bulge, the second frame is subject to deformation to facilitate combining the first frame and the second frame together.

Abstract: A manually operated switch assembly is disclosed. The switch assembly includes a housing, a switch mechanism, and an actuator assembly. The switch mechanism is housed within the housing and is configured to open or close a circuit upon actuation. The actuator assembly is shiftably supported by the housing and generally includes a depressible actuator and a stability element. The actuator presents an actuator length and serves to actuate the switch mechanism when depressed. The stability element is configured to ensure that the actuator moves substantially uniformly along the actuator length when the actuator is depressed such that actuation of the switch mechanism is facilitated regardless of where the actuator is depressed along the actuator length. The switch assembly may be waterproofed, and be formed, at least in part, by a curable liquid sealant supplied to the switch assembly from a single fluid source.

Abstract: A key structure with a scissors-type connecting member is provided. The scissors-type connecting member includes a first frame and a second frame. The first frame has a bulge. The second frame has a recess. The height of the bulge is smaller than the length of the recess entrance. The length of the recess bottom surface is greater than the length of the recess entrance. After the bulge of the first frame is introduced into the recess of the second frame, since the length of the recess bottom surface is greater than the length of the recess entrance, the possibility of detaching the bulge from the recess during the operation of the scissors-type connecting member will be minimized.