JP3718838B2 - Key switch - Google Patents

Description

  The present invention relates to a key switch using jump buckling, and more particularly, to a key switch structure including a plurality of parts as a continuous body.

  2. Description of the Related Art In recent years, information devices such as portable personal computers have been reduced in size and thickness, and it has been desired to reduce the size and thickness of a keyboard as well as a computer body. The keyboard is a two-dimensional arrangement of a plurality of key switches.

  In order to obtain a good operability, the key switch of the notebook computer is required to have a key stroke of about 3 mm and a maximum reaction force of 0.4 to 0.5 N. Sometimes there is a reaction force, and it is required to quickly return to its original shape when unloaded. Also, as a sensory element, it is required that there is a click feeling when a key is pressed. The conventional general structure used to satisfy these requirements is a combination of a pantograph mechanism for ensuring the horizontal posture of the key stroke and key top, and a rubber dome that generates a reaction force and a click feeling. This is the structure.

  On the other hand, Patent Document 1 proposes using a jumping buckling of a metal foil in order to obtain a good click feeling. Jump buckling is a phenomenon seen in shell structures and flat curved beam structures, and is used to give a click feeling to input devices such as key switches. The shell structure refers to a thin curved three-dimensional structure, and resists its own weight and external force with its three-dimensional rigidity.

Patent Document 1 relates to a key switch that uses a circular tactile spring (reference numeral 2 in the literature), and a tactile spring is buckled and reversed to obtain a click feeling. Since the “peripheral portion of the tact spring 2 is always in contact with the peripheral fixed contact 7” (paragraph number 0013), the tact spring is adhesively fixed to the peripheral fixed contact or simply contacted. Conceivable. Further, from FIG. 1 of this document, the shape of this tact spring seems to generate a strain load in the peripheral direction when buckling is reversed, and the tact spring itself absorbs the strain load generated when buckling is reversed. Since there is no mechanism to do so, it is considered that a strain load acts on the peripheral fixed contact.
Japanese Patent Laid-Open No. 11-7862

The structure using both the pantograph and the rubber dome uses one set of pantograph mechanisms for each key top, so that the number of parts is very large and the assembling cost is also increased. Structure of Patent Document 1, the advantages there Ru structural lies in not using a pantograph mechanism is simplified.

However, tact springs are individually made of metal materials according to the number of switches, and peripheral fixed contacts are also made individually and assembled one by one according to the key switch arrangement. Further reduction is desired. Further, in order to obtain a tact spring, it is necessary to form a metal spring material into a circular shape. Processing a plate-shaped metal plate into a circular shape by pressing or the like requires higher precision than the processing of bending a metal plate, and the shape of the circular-shaped tact spring becomes asymmetric. In such a case, the shape when the buckling is reversed is inclined, and a good click feeling is not obtained.

The present invention is intended to solve the above problems, it is possible to easily create a key switch using through buckling of the metal plate at a general-purpose technique, which can reduce the number of parts and assembling steps It is an object to provide a key switch.

  A key switch according to a first aspect of the present invention includes a click plate 2 made of a single metal foil formed so as to cover an upper portion of the switch portion, and a key top 4 that comes into contact with the upper surface of the click plate. In a key switch in which a protrusion located below the click plate 2 presses the switch portion when the top 4 is pressed, the unit elements 2b of the click plate 2 are bent pieces 2o, 2m, 2n protruding outward at the center of the four sides. A square 2d having a basic shape is formed as a basic shape, and is bent upwardly at the diagonal and four sides of the square in the basic shape to form a shell structure.

  According to the present invention, the necessary keystrokes can be easily obtained by the flexure pieces 2o, 2m and 2n provided at the center of the four sides of the square 2d, and a good click can be obtained by the jumping buckling in the shell structure of the square 2d portion. A feeling can be obtained. The bending pieces 2o, 2m, and 2n are formed in a tongue shape, but the reaction force during the stroke can be adjusted by making the tip side narrower. Moreover, since the shell structure is also formed by combining linear fold lines, press working is also easy.

  Furthermore, since the top part of each unit element 2b of the click plate is formed in a quadrangular pyramid shape, a pantograph is used by making the back surface 4b of the key top in contact therewith a quadrangular pyramid recess corresponding to the quadrangular pyramid. Even without it, the horizontal posture of the key top can be maintained.

  The key top 4 on the click plate 2 has a structure in which the key top 4 is bonded to the top of each unit element 2b, a structure in which a protrusion 4a provided on the back surface of the key top is inserted into and fixed to a through hole 2g provided in the top of the shell. It is possible to adopt a structure in which the key tops 4 are integrally formed in a sheet shape with flexibility between the key tops. The jump buckling of the click plate 2 occurs at the peripheral edge of the square 2d portion of each unit element, and the horizontal holding action of the key top 4 according to the above form is not hindered by the buckling deformation.

In the key switch according to claim 2 of the present invention, on the premise of the invention according to claim 1, each side of the circumscribed square 2c in which the basic shape of the click plate 2 circumscribes the corner of the square 2d at each center of the four sides is provided. The unit element is provided with connecting pieces 2f at both ends of one diagonal line in the circumscribed square , and the connecting pieces are connected to the connecting frame 2a made of the metal foil. The click plate has a shape in which a plurality of unit elements 2b are continuous .

← 0006,0008
The metal foil click plate does not have a strain load absorbing function like the rubber dome, so the strain load when the key top is pressed and the tact spring is buckled and reversed is transmitted to the peripheral fixed contacts and other peripheral members. It is thought to cause fatigue failure.

According to the invention of claim 2, the connecting piece 2f is flexibly deformed by the connecting pieces 2f provided at two locations for each unit element 2b by giving the connecting piece 2f flexibility to absorb the strain load at the time of buckling deformation. The strain load at the time can be absorbed.

  According to the present invention, since the click plate 2 has a shape in which a plurality of unit elements 2b are connected via the connecting piece 2f, the click plate 2 having the plurality of unit elements 2b is formed with a single metal foil. be able to.

In the key switch according to claim 3 of the present invention, on the premise of the invention according to claim 1, the click plate 2 is provided with a plurality of unit elements 2b, and each unit element is arranged horizontally at the tip of a 2 m piece of bending piece. A bent connecting piece 2k and a slide piece (2p) bent in the horizontal direction at the tip of the bending piece (2n) facing the one bending piece , the adjacent unit element 2b includes the connecting piece. It is characterized by being connected to each other.

  According to the present invention, when each unit element 2b is pressed, the horizontal strain load generated in the peripheral portion of each unit element is diffused in three directions where the connection piece 2k is not provided. It is not necessary to have a strain load absorbing structure such as a notch, which is advantageous in terms of workability and durability.

  The slide piece 2p can also be provided on all of the bending pieces 2n and 2o except the bending piece 2m provided with the connecting piece 2k.

In the key switch according to claim 4 , on the premise of the invention according to claim 3 , the click plate 2 is provided between the fixed plate 5 and the fixed cover 6 having the window 6a for exposing the shell of the unit element 2b. The connecting piece 2k and the slide piece 2p are sandwiched and stacked.

  The connecting piece 2k that connects each unit element is sandwiched and fixed between the fixed plate 5 and the fixed cover 6. On the other hand, since the slide piece 2p is slidably held in the horizontal direction between the fixed plate 5 and the fixed cover 6, a plurality of key switches can be easily operated in a state in which the strain load of each unit element 2b can be released. Can be assembled.

According to a fifth aspect of the present invention, the thickness of the metal foil forming the click plate 2 is calculated from the third root of the buckling load input to the key switch. It is characterized by.

  According to the present invention, the plate thickness of the metal foil forming the click plate 2 can be easily calculated from the specification value or the predicted value of the buckling load input to the key switch.

  With the configuration and operation of the present invention as described above, it is possible to obtain a key switch that has all of the key strokes required for a notebook computer, pressing reaction force, and click feeling, has a small number of parts, and is easy to assemble. . That is, a desired key stroke, pressing reaction force, and click feeling can be obtained by a shell structure combining the square 2d of each unit element 2b of the click plate and the flexure pieces 2o, 2m, 2n. Since it can be stably held at the top of each unit element 2b, a pantograph mechanism for maintaining the parallelism of the key tops is also unnecessary. A plurality of unit elements 2b can be integrally formed from a single metal plate in a state in which the strain load generated at the peripheral edge of the shell is absorbed or released when pressed, and the click plate 2 is simply sandwiched between the fixed plate 5 and the fixed cover 6. It is possible to assemble a plurality of key switches by simply doing.

  Furthermore, since the click plate 2 can be composed of a single metal foil, it is not necessary to use many complicated parts or perform complicated assembly as in the past, and the number of parts and assembly man-hours are greatly increased. Reduction can be achieved. In addition, the click plate 2 can have a plurality of unit elements 2b in a continuous shape, and can be collectively formed by press-cutting and pressing a single metal foil. At this time, the sides to be press-cut and the bent portions to be press-processed are all formed by straight lines, so that any processing can be easily performed, and the cost can be reduced. Furthermore, since the click plate 2 can be created by batch molding of a single metal foil, the number of parts and assembly man-hours can be greatly reduced.

In addition, even when a plurality of unit elements 2b are continuous, a strain load due to buckling inversion of the unit elements 2b is absorbed by the connecting pieces 2f and 2k, or diffused in three directions where no connecting pieces are provided. As a result, the influence of the strain load on the peripheral portions of adjacent unit elements and the like is suppressed, and high reliability can be maintained. For example, even if a plurality of adjacent key switches are pressed, problems such as poor conduction do not occur.

  In addition, according to the present invention, since the plate thickness is calculated from the buckling load input to the key switch, the design according to the purpose of use of the key switch is easily performed.

  Hereinafter, a first embodiment of the present invention will be described with reference to the drawings, taking as an example a key switch used in a keyboard of a personal computer or the like.

  An overview of the click plate portion of the key switch of this embodiment is shown in FIG. 1 to FIG. 3, and a sectional view of the mounted state is shown in FIG. As shown in FIG. 4, the key switch 1 includes a click plate 2 and a key top 4. The click plate 2 is made of stainless steel (SUS304) foil having a thickness t of 0.05 mm as a metal foil, and has a shape in which unit elements 2b are connected to a matrix-like connecting frame 2a.

  As shown in FIG. 2, the unit element 2b is provided with notches on the four sides of the circumscribed square plate 2c so that corners 2e of the inscribed square 2d inscribed in the circumscribed square 2c appear, and corners of the connecting frame 2a are provided. It is the shape which connected the front-end | tip of the provided connection piece 2f to the both ends of one diagonal of the circumscribed square 2c, respectively. Further, four through holes 2g are provided in the vicinity of the center of the inscribed square 2d, and in the vicinity of the connecting portion of the connecting piece 2f with the inscribed square 2d, horizontal flexibility for absorbing a strain load is imparted. For this purpose, several notches 2h are formed.

  Further, as shown in FIG. 3, the diagonal line 2i and the four sides (the base part of the bending piece) of the inscribed square 2d are bent in an upward convex direction at a gentle angle, so that the unit element 2b has an inscribed square and four bending pieces. The shell structure which consists of is formed.

  In the present embodiment, a stainless steel foil is used as the metal foil, but the present invention is not limited to this, and the use of other metal foils such as phosphor bronze is also included in the present invention. Among various metal foils, stainless steel foils are excellent in strength, corrosion resistance, and heat resistance. Therefore, they are also used in precision machine parts that place importance on durability, and have high reliability.

  The click plate 2 of the present embodiment is formed by batch molding the whole by press-cutting the stainless steel foil so as to have the shape shown in FIG. 1 and press-processing so as to have the three-dimensional shape shown in FIG. Can do. FIG. 2 is an enlarged view of the unit element 2b. At this time, since the side to be press-cut and the line to be pressed (bending portion) are all straight lines, any processing can be easily performed. Furthermore, since the whole is collectively formed, it is not necessary to produce and assemble individual parts for each unit element 2b, and since it can be formed in a shape suitable for the key arrangement of the keyboard structure, man-hours and costs can be reduced. It can be greatly reduced. Normally, when assembling individual parts, deterioration of assembly accuracy due to variation in arrangement is unavoidable, but as in this embodiment, parts having specific functions are continuous (also called functional continuums). If it can be created by (called), it is possible to solve such a problem concerning the assembly accuracy.

  FIG. 4 shows a sectional view of the key switch 1 according to the present embodiment in a mounted state. 4 is a cross-sectional view taken along line XX in FIG. As shown in FIG. 4A, the key switch 1 includes a click plate 2 on the upper part of a sheet-like membrane switch 3 as a switch portion, and a portion where the notch 2h on the back surface of the connecting piece 2f is not formed. Is attached to the membrane switch 3 and the protrusion 4a of the key top 4 is fitted into the through hole 2g provided in the top of the click plate 2. Adhesion of the back surface of the connecting piece 2f is performed with an adhesive applied to the surface of the membrane switch 3 by printing or the like. The membrane switch 3 has a structure in which thin film sheets are stacked. In a normal state, the movable contact 3a and the fixed contact 3b are separated from each other. When pressed from above, the movable contact 3a and the fixed contact 3b come into contact with each other. Conductivity is obtained.

  As shown in FIG. 4B, when the key top 4 is pressed from above, the upper surface of the unit element 2 b forming the shell structure is buckled and the protrusion 4 a of the key top 4 is the surface of the membrane switch 3. Is pressed to bring the movable contact 3a and the fixed contact 3b into contact with each other, and electrical conduction is obtained at this contact portion. Further, when the jumping buckling phenomenon occurs in the unit element 2b, a click feeling is obtained. When the unit element 2b undergoes buckling deformation, a strain load (arrow A in FIG. 4B) is applied from the center of the inscribed square 2d to the peripheral direction, but the strain is caused by the notch 2h formed in the square connecting piece 2f. Is absorbed and does not affect the shape of the adjacent unit element 2b.

  In the present embodiment, as a strain absorbing mechanism at the time of buckling deformation, the connecting piece 2f has a quadrangular shape and a cut 2h is formed in the connecting piece 2f. However, as shown in FIGS. 5 and 6, the shape of the connecting piece 2f is It may be a thin plate. 1, 2 and 5 and 6, the connecting piece 2f is formed at the upper right and lower left of the unit element 2b. However, the present invention is not limited to this, and the upper left and right of the unit element 2b are not limited thereto. It may be formed below. Alternatively, the position of the connecting piece 2f is arbitrary according to the implementation, such as reversing the position of the connecting piece 2f for each key row. The key switch of the present invention can also be applied to a button switch used for an electronic device.

  Next, the design of the key switch of the present invention will be described. First, for the unit element 2b of the present embodiment, a mechanical characteristic evaluation using the plate thickness t as a parameter was performed. In the evaluation method, a forced displacement is applied to the center of the unit element 2b, and the reaction force is measured with a minute load cell. The result is shown in FIG. From FIG. 7, it can be seen that the buckling load decreases as the plate thickness t decreases, and the displacement when buckling also decreases. Therefore, it can be said that the plate thickness is an important parameter in the jumping buckling phenomenon.

  Next, the change of the buckling load with respect to the plate thickness t is shown in FIG. The horizontal axis is the cube of the thickness t, and the vertical axis is the buckling load. FIG. 8 shows that the buckling load is proportional to the cube of the plate thickness. The proportionality constant is determined by the size and shape of the unit element. From the above results, when designing the unit element 2b, it can be said that the plate thickness may be calculated from the cube root of the desired buckling load.

  9 to 13 are views showing a second embodiment of the present invention, and showing the embodiment corresponding to claims 4 to 6. FIG. In the second embodiment, four adjacent unit elements 2b are formed from a single metal plate, and the four unit elements 2b are connected by a connecting piece 2k having no horizontal flexibility. The slide piece 2p extending in the horizontal direction at the tip of the bending piece 2n facing the bending piece 2m provided with the connecting piece 2k, and the click plate 2 fixing the connecting piece 2k and the sliding piece 2p to the fixing plate 5 The first embodiment is different from the first embodiment described above in that it is sandwiched and held by the fixed cover 6. Only differences from the first embodiment will be described in detail below.

  The flexure piece 2o of the first embodiment has the same shape for all four unit elements, whereas in the second embodiment shown in FIGS. 9 to 13, the flexure piece 2m connected to the connecting piece 2k. Is a rectangle, and the bending piece 2n facing the rectangular bending piece is provided with an integral slide piece 2p folded back in the horizontal direction at the tip thereof. FIG. 10 is a diagram showing a cut end surface in the center of one unit element in the direction from the slide piece 2p to the connecting piece 2k. Refraction points PA to PE correspond to the points PA to PE in FIG. Yes.

  The click plate 2 having the above structure is assembled while being sandwiched between the fixed plate 5 shown in FIG. 11 and the fixed cover 6 shown in FIG. The fixing plate 5 is formed with a shallow recess 5a having a depth corresponding to the thickness of the click plate at a portion where the click plate is located. On the other hand, the fixed cover 6 is provided with four windows 6a having a size that exposes each of the four shells of the click plate (the portion including the square 2d and the bending pieces 2m, 2n, and 2o). The size of the window 6a is a size that does not hinder the displacement even when the top of the unit element 2b is pushed down and the tips of the bending pieces 2n and 2o are displaced in the direction of spreading in three directions. No window is provided in the portion 6k of the connecting piece 2k of the click plate and the portion 6p corresponding to the tip of the slide piece 2p.

  By placing the click plate 2 in the recess 5a of the fixed plate 5 configured as described above and laminating the fixed cover 6 thereon, the click plate 2 has the connection pieces 2k and the tips of the four slide pieces 2p. Is held between the fixed plate 5 and the fixed cover 6, so that the key top portion of the keyboard is formed by laminating the key sheet 4 c so that the key top 4 comes on each unit element 2 b of the click plate. Can be assembled. The key sheet 4c has a structure in which a plate-like key top 4 is pasted or molded on a flexible sheet 4d, and the figure is shown with four key tops. All key tops on the keyboard can be assembled into a single sheet. Similarly, the fixed plate 5 and the fixed cover 6 can correspond to all the key switches arranged on the keyboard by providing a large number of recesses 5a and windows 6a in one synthetic resin sheet.

  When the key top of the key switch assembled in this way is pressed, the horizontal distortion load generated in the unit element 2b of the click plate is caused between the slide piece 2p between the fixed plate 5 and the fixed cover 6, and Since the tips of the bending pieces 2o on both sides slide on the bottom surface of the recess 5a of the fixed plate, the click pieces 2k are released, and it is not necessary to provide the connection pieces 2k with cuts or the like for absorbing the strain load. Is easy to manufacture, and durability is improved. In addition, the sliding property on the bottom face of the recess 5a can be improved by making the tip of the bending piece 2o arcuate or slightly warping upward.

The top view which shows an example of the click plate of 1st Embodiment Enlarged view of the unit element of the click plate of FIG. Overview of unit elements in Figure 2 It is a figure which shows the mounting state of the key switch of this invention, (a) is sectional drawing of the state in which a key top is not pressed down, (b) is sectional drawing of the state in which the key top is pressed down The top view which shows another example of the click plate of 1st Embodiment Enlarged view of the unit element of the click plate in FIG. Graph showing the mechanical properties of unit elements Graph showing the change of buckling load with respect to unit element thickness The top view which shows the example of the click plate of 2nd Embodiment Cross-sectional end view of the unit element of the click plate of FIG. Top view of the fixed plate carrying the click plate of Fig. 9 FIG. 9 is a top view of the fixed cover that holds the click plate in FIG. FIG. 9 is an exploded perspective view showing the actual phase structure of the click plate of FIG.

Explanation of symbols

1 key switch 2 click plate 2a connecting frame 2b unit element 2c circumscribed square 2d inscribed square 2e corner 2f, 2k connecting piece 2g through hole 2h notch 2i diagonal 2m, 2n, 2o flexible piece 2p slide piece 3 membrane switch 3a movable contact 3b Fixed contact 4 Key top 4a Protrusion 4b Back side of key top 4c Key sheet 4d Flexible sheet 5 Fixed plate 5a Recess 6 Fixed cover 6a Window A Direction of strain load X Cutting line t Plate thickness

Claims (5)

A click plate (2) made of a sheet of metal foil formed to cover the top of the switch part, and a key top (4) that contacts the top surface of the click plate. In the key switch in which the protrusion located below the plate (2) presses the switch part,
The unit element (2b) of the click plate (2) has a basic shape of a square (2d) provided with bending pieces (2o, 2m, 2n) protruding outward at the center of the four sides, and the square of the basic shape A key switch that is bent in an upward convex shape on the diagonal and four sides to form a shell structure. The basic shape of the click plate (2) is formed by providing a notch on each side of the circumscribed square (2c) circumscribing at the center of each of the four sides at the corner of the square (2d). The click plate has a plurality of unit elements (2b) by providing connection pieces (2f) at both ends of one diagonal line in the circumscribed square, and connecting the connection pieces to the connection frame (2a) made of the metal foil. The key switch according to claim 1, wherein the key switch has a continuous shape . The click plate (2) includes a plurality of unit elements (2b), and each unit element includes a connecting piece (2k) bent in the horizontal direction at the tip of one piece (2m) of the bent piece, and the one bent piece. The slide piece (2p) bent in the horizontal direction at the tip of the opposing deflecting piece (2n), and adjacent unit elements (2b) are connected to each other via the connecting piece. Key switch. The click plate (2) is connected between the fixed plate (5) and the fixed cover (6) having a window (6a) exposing the shell of the unit element (2b), and the connecting piece (2k) and the slide piece. The key switch according to claim 3, wherein (2p) is sandwiched and stacked. The metal foil forming the click plate (2) has a plate thickness calculated from the third root of the buckling load input to the key switch. 1 is a key switch.

Images