Key unit and electronic device

Abstract

To provide a key unit and an electronic device that can be made thin.SOLUTION: A key unit includes a frame and a key top. The frame has a pivot or a bearing. The key top has a bearing that fits into the pivot of the frame, or a pivot that fits into the bearing of the frame, and is attached to the frame so as to be rotatable. A first side surface connected to the top surface of the key top facing the frame, and a second side surface connected to the top surface of the frame facing the first side surface, are each a cylindrical surface formed by moving a concentric curve centered on the pivot along the pivot.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to electronic devices such as electronic dictionaries and key units.

Background Art

[0002] Conventionally, as a key unit for an electronic dictionary or a notebook personal computer, for example, a plurality of key tops are stacked in a predetermined arrangement via a rotation shaft on a plate-like base member having a plurality of contacts.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a plurality of key tops are stacked and arranged on a plate-like base member as in the above-described conventional key unit, it is difficult to sufficiently thin the key unit.

[0005] An object of the present invention is to provide a key unit and an electronic device that can be thinned.

Means for Solving the Problems

[0006] A key unit according to an aspect of the present invention includes a frame and key tops. The frame has a rotation shaft or a bearing. The key tops have a bearing that fits into the rotation shaft of the frame or a rotation shaft that fits into the bearing of the frame, and are rotatably attached to the frame. A first side surface connected to the upper surface of the key top facing the frame and a second side surface connected to the upper surface of the frame facing the first side surface are each a cylindrical surface formed by moving a concentric curve centered on the rotation shaft along the rotation shaft.

Effects of the Invention

[0007] According to one aspect of the present invention, a key unit capable of being thinned and an electronic device can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an external perspective view of an electronic dictionary 100 which is an example of an electronic device. In FIG. 1, a state where a second housing 4 is opened with respect to a first housing 2 of the electronic dictionary 100 is shown. The first housing 2 is formed in a flat rectangular plate shape and includes a key unit 10 according to an embodiment of the present invention. The second housing 4 is formed in a flat rectangular plate shape and includes a display 5. The key unit 10 receives an input operation by a user. The display 5 displays various information to the user and also receives an input operation by the user. The display 5 is a so-called touch panel. The electronic dictionary 100 is used, for example, by placing the back surface of the first housing 2 in contact with the upper surface of a desk or the like and opening the second housing 4 as shown in the figure.

[0010] The electronic dictionary 100 includes a hinge portion 6 that connects the first housing 2 and the second housing 4. The hinge portion 6 rotatably connects the illustrated rear end of the first housing 2 and the illustrated lower end of the second housing 4. The second housing 4 can be arranged in an open position illustrated in FIG. 1 where it is opened with respect to the first housing 2 and a closed position (not shown) where the second housing 4 is overlapped on the upper surface of the first housing 2. The open position (rotation angle) of the second housing 4 with respect to the first housing 2 can be arbitrarily changed. In a state where the second housing 4 is opened to the open position, the key unit 10 can be operated and the display 5 can be viewed. In a state where the second housing 4 is arranged in the closed position, the display 5 overlaps on the key unit 10 and the electronic dictionary 100 is in a folded state.

[0011] In the following description, regardless of the rotation position of the second housing 4, the front end side of the first housing 2 is defined as the front of the electronic dictionary 100, the rear end side with the hinge portion 6 is defined as the rear of the electronic dictionary 100, and the vertical direction of the electronic dictionary 100 is defined in a state where the back surface of the first housing 2 is arranged horizontally. Also, the left-right direction of the electronic dictionary 100 is defined when viewing the first housing 2 from the front.

[0012] The key unit 10 has, as an example, 29 key tops 12 of the same shape arranged in three rows one behind the other. The key tops 12 in each row are arranged with almost no gap between the adjacent key tops 12 on the left and right. The first housing 2 has a rectangular opening 3 for exposing the 29 key tops 12 of the key unit 10 to the front surface side. For the 10 key tops 12 in the front row, the 9 key tops 12 in the second row adjacent to the rear are respectively arranged between the key tops 12 in the front row. The 10 key tops 12 in the third row at the rear are each arranged with a half-pitch shift from the key tops 12 in the second row. Therefore, the 10 key tops 12 in the front row and the 10 key tops 12 in the third row are in positions facing each other front and back with the 9 key tops 12 in the second row sandwiched therebetween.

[0013] As shown in FIGS. 3 and 4, the key top 12 is substantially rectangular plate-shaped and has a front surface 12a (upper surface) that the user presses with a finger, a back surface 12b opposite to the front surface 12a, a front end 12F, and a rear end 12R. As shown in FIG. 6, the front end 12F has a flat end surface 121 that is substantially orthogonal to the back surface 12b connected to the front edge of the back surface 12b, and a flat inclined surface 122 between the end surface 121 and the front edge of the front surface 12a. The inclined surface 122 is slightly inclined rearward from the upper edge of the end surface 121 toward the front edge of the front surface 12a. The rear end 12R has a cylindrical surface 123 that is curved as will be described later and connected to the front surface 12a. The cylindrical surface 123 is an example of a first side surface and is a curved surface formed by moving an arc-shaped curve centered on the shaft portions 22b of the rotation shafts 22L and 22R to be described later in the left-right direction. The front surface 12a of the key top 12 is slightly inclined in a direction away from the back surface 12b from the rear end 12R toward the front end 12F. That is, the thickness of the key top 12 gradually increases from the rear end 12R toward the front end 12F. The front surface 12a of the key top 12 constitutes a part of the front surface of the key unit 10.

[0014] In this embodiment, the column surface 123 at the rear end 12R of the key top 12 is formed into a cylindrical surface that can be obtained by moving an arc centered on the shaft portions 22b of the rotation shafts 22L and 22R in the left - right direction. However, the column surface 123 only needs to have a shape that is difficult to interfere with the column surface 151 of the frame 15, which will be described later, during the rotation of the key top 12, and may be a free - form surface close to a cylindrical surface. For example, the column surface 123 may be a surface including an elliptical column surface, an oblong column surface, or the like.

[0015] The back surfaces 12b of the plurality of key tops 12 are arranged on the same flat virtual surface in a state where all the key tops 12 are arranged at the initial positions shown in FIG. 1. The front ends 12F and the rear ends 12R of the key tops 12 in each column are aligned in a straight line in the left - right direction. There is a predetermined gap between the rear ends 12R of the plurality of key tops 12 in the front - most row and the front ends 12F of the plurality of key tops 12 in the second row, and there is also a predetermined gap between the rear ends 12R of the plurality of key tops 12 in the second row and the front ends 12F of the plurality of key tops 12 in the third row. There is a frame 14 of the case 11, which will be described later, between the front - most row of key tops 12 and the key tops 12 in the second row, and there is a frame 15 between the key tops 12 in the second row and the key tops 12 in the third row. In FIG. 1, the illustration of the front - rear direction gaps (frames 14, 15, 16) between the key tops 12 in each column is omitted.

[0016] As shown in FIG. 2, the key unit 10 includes a circuit board 1, a contact rubber sheet 7, and a case 11 in addition to the plurality of key tops 12 described above. The case 11 independently holds the rear ends 12R of the plurality of key tops 12 in a rotatable manner and is attached in the above-described arrangement. Then, the contact rubber sheet 7 is disposed on top of the circuit board 1, and the case 11 having the plurality of key tops 12 is disposed on top of the contact rubber sheet 7. Most of the volume of the plurality of key tops 12 is disposed within the thickness of the case 11, and there is no portion that overlaps above and below the case 11 beyond the thickness of the case 11. The circuit board 1 has 29 contacts (not shown) at positions facing each of the plurality of key tops 12 below. The contact rubber sheet 7 has 29 substantially cylindrical bulging portions 8 at positions facing each of the plurality of key tops 12 below. That is, the plurality of bulging portions 8 of the contact rubber sheet 7 overlap the plurality of contacts of the circuit board 1 respectively, and the plurality of key tops 12 overlap thereon respectively.

[0017] In the assembled state of the key unit 10, the tips of the plurality of bulging portions 8 of the contact rubber sheet 7 in the protruding direction contact the back surfaces 12b of the plurality of key tops 12, and the bulging portions 8 are slightly compressed in the vertical direction by elastic deformation, and the key tops 12 are biased upward by the restoring force of the bulging portions 8. In other words, the bulging portions 8 of the contact rubber sheet 7 have a thickness (vertical protruding height) such that they can bias the opposing key tops 12 upward in the assembled state of the key unit 10. Further, the contact rubber sheet 7 has a carbon conductor (not shown) applied to the back surface on the circuit board 1 side (the inner surface of the bulging portion 8). The contact rubber sheet 7 can be formed of an elastic member such as silicone rubber or an elastomer, for example. When the user presses the surface 12a of the key top 12 downward, the carbon conductor on the inner surface of the bulging portion 8 of the contact rubber sheet 7 conducts the contacts of the circuit board 1, and a key input is made. When the user removes a finger from the surface 12a of the key top 12, the key top 12 is biased upward by the restoring force of the bulging portion 8 and returned to the initial position.

[0018] As shown in FIGS. 2 and 3, the case 11 has a frame portion 13 and three frames 14, 15, and 16. The frame portion 13 is formed in a rectangular frame shape sized to fit inside the opening 3 of the first housing 2. The frame portion 13 has a front portion 13F and a rear portion 13R that are spaced apart from each other in the front-rear direction and extend in the left-right direction. The three frames 14, 15, and 16 are provided further inside the frame portion 13. The front portion 13F of the frame portion 13 and the three frames 14, 15, and 16 are, for example, rod-shaped frames with a substantially rectangular cross-section over their entire lengths. The case 11 can be formed, for example, by integrally molding with resin. The foremost frame 14 among the three frames 14, 15, and 16 is disposed between the foremost key tops 12 and the key tops 12 in the second row with a predetermined interval behind the front portion 13F of the frame portion 13. The frame 15 is disposed between the key tops 12 in the second row and the key tops 12 in the third row with a predetermined interval behind the frame 14. The frame 16 is connected to the rear portion 13R of the frame portion 13 at the rear end side of the key tops 12 in the third row with a predetermined interval behind the frame 15. That is, the three frames 14, 15, and 16 are spaced apart from each other in the front-rear direction, arranged parallel to each other, and extend over the entire length of the frame portion 13 in the left-right direction. Note that there are two plate-like portions 11L and 11R on the inner sides of both left and right ends of the frame portion 13 where no key tops 12 are provided. The two plate-like portions 11L and 11R are between the frame 14 and the frame 15.

[0019] The structures for attaching the key tops 12 to the frames 14, 15, and 16 of the case 11 are the same for all the key tops 12. Therefore, here, mainly focusing on one key top 12 in the second row provided between the frame 14 and the frame 15, the structure for attaching that key top 12 to the case 11 will be described representatively.

[0020] As shown in FIGS. 4 and 5, the frame 15 behind the key tops 12 in the second column has a plurality of pairs of bearing recesses 17L, 17R for rotatably mounting two pairs of two pivot shafts 22L, 22R protruding from the rear end 12R of the key tops 12. The other frames 14, 16 also have a plurality of pairs of bearing recesses 17L, 17R. Further, the frame 15 has a plurality of engaging recesses 18 for engaging an engaging convex portion 24 (FIG. 6) protruding from the front end 12F of the key tops 12 in the third column. Similarly, the frame 14 has a plurality of engaging recesses 18 for engaging the engaging convex portion 24 of the key tops 12 in the second column. A plurality of engaging recesses 18 are also provided in the front portion 13F of the frame portion 13 to engage the engaging convex portion 24 of the key tops 12 in the foremost column. The frames 14, 15 each have both a plurality of pairs of bearing recesses 17L, 17R and a plurality of engaging recesses 18 at positions longitudinally offset. The plurality of pairs of bearing recesses 17L, 17R have the same structure, and the plurality of engaging recesses 18 also have the same structure.

[0021] As shown in FIG. 5, the key top 12 includes two pivot shafts 22L, 22R and an engaging convex portion 24. The two pivot shafts 22L, 22R project integrally rearward from the back surface 12b near the rear end 12R of the key top 12. The two pivot shafts 22L, 22R are provided spaced apart in the left-right direction of the key top 12. As shown in FIG. 6, the engaging convex portion 24 projects forward from the end face 121 at the front end 12F of the key top 12. The engaging convex portion 24 is provided at the center in the left-right direction of the key top 12. The key top 12 provided with the two pivot shafts 22L, 22R and the engaging convex portion 24 can be formed, for example, by integral molding with resin.

[0022] The key top 12 has a shape that is symmetric with respect to an imaginary central plane that extends in the vertical and front-rear directions through the center in the left-right direction thereof. For this reason, the two rotation axes 22L and 22R also have a shape that is symmetric with respect to the imaginary central plane. Thus, here, mainly, the left rotation axis 22L will be described as a representative, and the description of the right rotation axis 22R will be omitted. The rotation axis 22L is provided on the back surface 12b near the rear end 12R of the key top 12 at a position spaced to the left from the center in the left-right direction of the key top 12. The rotation axis 22L has a substantially rectangular block-shaped support portion 22a that projects rearward from the back surface 12b of the key top 12 beyond the rear end 12R, and a substantially columnar shaft portion 22b provided at the rear end of the support portion 22a. The shaft portions 22b of the left and right rotation axes 22L and 22R are coaxially arranged.

[0023] As shown in FIG. 7, the engagement convex portion 24 projects forward from the end face 121 of the tip 12F at the center in the left-right direction of the key top 12. The engagement convex portion 24 is formed in a substantially frustum of a quadrangular pyramid shape having a rectangular flat top surface 248 at the top. The engagement convex portion 24 has a flat rectangular bottom surface 243 that extends in the horizontal direction and a joining surface 244 that extends vertically upward from the rear end side of the bottom surface 243. The bottom surface 243 is arranged in the same plane as the back surface 12b of the key top 12. The joining surface 244 is one side surface of the quadrangular pyramid and is the surface that connects to the end face 121 of the tip 12F. The lower end of the joining surface 244 terminates at the back surface 12b of the key top 12. The upper end of the joining surface 244, that is, the top surface 248, is located slightly below the ridge line between the end face 121 and the inclined surface 122. In addition, the engagement convex portion 24 has three inclined surfaces 245, 246, and 247 that are inclined so as to converge from the remaining three sides of the bottom surface 243 toward the top surface 248, respectively. The top surface 248 at the upper end of the frustum of the quadrangular pyramid where the four surfaces 244, 245, 246, and 247 of the engagement convex portion 24 meet is a surface parallel to the back surface 12b of the key top 12.

[0024] As shown in FIG. 5, the two bearing recesses 17L and 17R of the frame 15 that receive the two rotation shafts 22L and 22R of the key top 12 have a shape that is symmetric with respect to the above-described imaginary central plane orthogonal to the frame 15. Therefore, here, the left bearing recess 17L will be described, and the description of the right bearing recess 17R will be omitted. The bearing recess 17L is a recess for fitting the left rotation shaft 22L of the key top 12. The bearing recess 17L is a hole that opens to the lower surface 15d and the front surface 151 of the frame 15. The bearing recess 17L has a substantially cylindrical bearing portion 171 that fits the shaft portion 22b of the rotation shaft 22L by press-fitting and a groove portion 172 that receives the support portion 22a of the rotation shaft 22L. The bearing portion 171 is a hole that opens to the lower surface 15d of the frame 15 and is located between the upper surface 15c and the lower surface 15d of the frame 15. The groove portion 172 extends forward from the center in the left-right direction of the bearing portion 171, and the rear end is connected to the bearing portion 171. The groove portion 172 opens to the front surface 151 of the frame 15.

[0025] The front surface 151 of the frame 15 facing the column surface 123 at the rear end 12R of the key top 12 is an example of the second side surface, and is a curved column surface formed by moving an arc-shaped curve centered on the bearing portion 171 of the bearing recess 17L in the left-right direction. Hereinafter, the front surface 151 of the frame 15 may also be referred to as the column surface 151. The column surface 151 of the frame 15 and the column surface 123 of the key top 12 are arranged concentrically around the shaft portions 22b of the rotation shafts 22L and 22R with a uniform gap therebetween. In the present embodiment, the column surface 151 on the front surface of the frame 15 is formed into a cylindrical surface formed by moving an arc centered on the shaft portions 22b of the rotation shafts 22L and 22R of the key top 12 in the left-right direction. However, the column surface 151 may have a shape that does not interfere with the above-described column surface 123 during the rotation of the key top 12, and may be a free-form surface close to a cylindrical surface. For example, the column surface 151 may be a surface including an elliptical column surface or an oblong column surface.

[0026] When attaching the rotation shafts 22L and 22R of the key top 12 to the bearing recesses 17L and 17R of the frame 15, attach the key top 12 from the back side of the case 11. In this case, first, tilt and arrange the key top 12 in the illustrated posture where the rotation shafts 22L and 22R are positioned upward, move the key top 12 upward in this posture, and press-fit the shaft portions 22b of the rotation shafts 22L and 22R into the bearing portions 171 of the bearing recesses 17L and 17R of the frame 15. Then, as shown in FIG. 4, rotate the tip 12F of the key top 12 upward about the shaft portion 22b, place the support portions 22a of the rotation shafts 22L and 22R in the groove portions 172 of the bearing recesses 17L and 17R, and engage the engaging convex portion 24 at the tip 12F of the key top 12 with the engaging recess 18 of the frame 14. In the assembled state of the key unit 10, the engaging convex portion 24 is pressed against the engaging recess 18 by the restoring force of the bulging portion 8 of the contact rubber sheet 7. For this reason, the engagement between the engaging convex portion 24 and the engaging recess 18 prevents the key top 12 from popping upward.

[0027] As shown in FIG. 8, the engaging recess 18 of the frame 14 that engages with the engaging convex portion 24 of the key top 12 opens to the rear surface 14b, the lower surface 14d, and the upper surface 14c of the frame 14. The engaging recess 18 has a first portion 18a having a rectangular parallelepiped shape with a predetermined thickness in the vertical direction, and a second portion 18b having a substantially frustum-of-a-square-pyramid shape into which the engaging convex portion 24 of the key top 12 is fitted. The cross-section of the first portion 18a cut at an arbitrary height position in the horizontal plane is a rectangle that is slightly larger than the bottom surface 243 of the engaging convex portion 24. The second portion 18b is continuous with the upper portion of the first portion 18a. The inner surface of the second portion 18b is continuous with the inner surface of the first portion 18a. The second portion 18b has, on its inner surface, an inclined receiving surface 185 that contacts the inclined surface 245 of the engaging convex portion 24 in a surface-to-surface manner, an inclined receiving surface 186 that contacts the inclined surface 246 of the engaging convex portion 24 in a surface-to-surface manner, and an inclined receiving surface 187 that contacts the inclined surface 247 of the engaging convex portion 24 in a surface-to-surface manner. The upper end of the second portion 18b opens at the upper surface 14c of the frame 14. That is, there is a rectangular opening 188 on the upper surface 14c of the frame 14 that exposes the top surface 248 of the engaging convex portion 24. As shown in FIG. 9, in a state where the engaging convex portion 24 of the key top 12 is fitted into the engaging recess 18 of the frame 14, the top surface 248 of the engaging convex portion 24 is flush with the upper surface 14c of the frame 14.

[0028] As shown in FIG. 9, when the engaging convex portion 24 is engaged with the engaging recess 18, the inclined surface 245 of the engaging convex portion 24 contacts the inclined receiving surface 185 of the engaging recess 18 in a surface-to-surface manner, the inclined surface 246 of the engaging convex portion 24 contacts the inclined receiving surface 186 of the engaging recess 18 in a surface-to-surface manner, and the inclined surface 247 of the engaging convex portion 24 contacts the inclined receiving surface 187 of the engaging recess 18 in a surface-to-surface manner. At this time, the top surface 248 of the engaging convex portion 24 is exposed from the opening 188 of the engaging recess 18 and is flush with the upper surface 14c of the frame 14.

[0029] When the key unit 10 is assembled, since the key top 12 is biased upward by the bulging portion 8 of the contact rubber sheet 7, the engaging convex portion 24 is pressed upward toward the engaging concave portion 18. For this reason, the three sets of inclined surfaces that are inclined in a direction converging toward the pressing direction (upward) press against each other and come into close contact. At this time, the area of the surface where the engaging convex portion 24 and the engaging concave portion 18 contact is a sufficiently large area, and the engaging convex portion 24 can be stably engaged with the engaging concave portion 18.

[0030] On the other hand, if the engaging convex portion is formed in a plate shape having a thickness in the vertical direction and no inclined surface is provided, in order to ensure sufficient mechanical strength of the engaging convex portion, a sufficient thickness of the engaging convex portion in the vertical direction is required. In this case, the thickness of the engaging convex portion in the vertical direction affects the thickness T of the key unit 10 in the vertical direction. That is, in order to push the key top 12 to conduct the contact on the circuit board 1, the key top 12 requires a stroke in the vertical direction, and it is necessary to prevent the engaging convex portion from interfering with the contact rubber sheet 7 when the key top 12 is pushed to the position where the contact is conducted. For this reason, if the thickness of the engaging convex portion is increased, the thickness of the frame 14 in the vertical direction needs to be increased accordingly, and the key unit 10 becomes thicker.

[0031] In the key unit 10 of the present embodiment, since the engaging recess 18 of the frame 14 has an opening 188 that exposes the top surface 248 of the engaging projection 24 of the key top 12, when the engaging projection 24 of the key top 12 is engaged with the engaging recess 18, a vertical step can be formed between the bottom surface 243 of the engaging projection 24 and the lower surface 14d of the frame 14. This step corresponds to the stroke of the key top 12 for pushing the key top 12 to conduct the contacts on the circuit board 1. Therefore, when the key top 12 is pushed in, the bottom surface 243 of the engaging projection 24 does not protrude below the lower surface 14d of the frame 14, and the bottom surface 243 does not contact the contact rubber sheet 7 either. On the other hand, since the joint surface 244 of the engaging projection 24 is integrated with the tip 12F of the key top 12, the engaging projection 24 can be provided with sufficient mechanical strength. The inclined surfaces 245, 246, 247 of the engaging projection 24 can be said to be a configuration for enabling the movement of the key top 12 within the vertical width of the frame 14, and can be said to be a configuration contributing to the thinning of the key unit 10.

[0032] As described above, according to the key unit 10 of the present embodiment, most of the volume of the plurality of key tops 12 can be arranged within the thickness of the case 11, and the key unit 10 can be thinned. Specifically, the configurations for thinning the key unit 10 include the cylindrical surface 123 of the key top 12 arranged concentrically with respect to the rotation axes 22R, 22L, the cylindrical surface 151 of the frame 15, the inclined surfaces 245, 246, 247 of the engaging projection 24 of the key top 12, and the opening 188 of the engaging recess 18 of the frame 14 that exposes the top surface 248 of the engaging projection 24 on the upper surface 14c of the frame 14.

[0033] The cylindrical surface 123 at the rear end 12R of the key top 12 is a cylindrical surface centered on the shaft portions 22b of the rotation shafts 22R and 22L, and the cylindrical surface 151 on the front surface of the frame 15 that rotatably holds the rear end 12R of the key top 12 is a cylindrical surface centered on the shaft portions 22b of the rotation shafts 22R and 22L. By doing so, the two cylindrical surfaces 123 and 151 can be arranged concentrically. As a result, it is possible to make it difficult for the key top 12 and the frame 15 to interfere during the rotation of the key top 12, the upper surface 15c of the frame 15 and the surface 12a of the key top 12 can be arranged substantially flush, most of the key top 12 can be arranged within the vertical thickness of the frame 15, and the key unit 10 can be made thinner.

[0034] The shaft portions 22b of the rotation shafts 22R and 22L of the key top 12 and the bearing portions 171 of the bearing recesses 17L and 17R of the frame 15 are fitted with play. Also, by making the cylindrical surfaces 123 of the key top 12 and 151 of the frame 15 into cylindrical surfaces centered on the shaft portion 22b, the gap between the two cylindrical surfaces 123 and 151 is made uniform. Therefore, by making the gap between the two cylindrical surfaces 123 and 151 large enough for the two cylindrical surfaces 123 and 151 to contact when the key top 12 is twisted during rotation, the twist of the key top 12 can be corrected.

[0035] Also, according to the present embodiment, since the cylindrical surfaces 123 of the key tops 12 facing each other and the cylindrical surfaces 151 of the frames 15 (14, 16) are arranged concentrically with a uniform gap therebetween, when the key unit 10 is viewed from the front side, the inside of the key unit 10 cannot be seen from between the rear ends 12R of the key tops 12 in each row and the frames 15 (14, 16) behind them, and the aesthetic appearance can be improved and the design quality can be enhanced. Also, by arranging the cylindrical surface 123 of the key top 12 and the cylindrical surface 151 of the frame 15 concentrically with a minute gap therebetween, an effect of making it difficult for dust to enter the gap can also be expected.

[0036] Further, according to the present embodiment, since a plurality of sets of bearing recesses 17L and 17R are provided in the frames 14, 15, and 16 of the case 11 and a plurality of key tops 12 are directly attached to the case 11, there is no need to separately provide a configuration for rotatably attaching the key tops 12 to the case 11. The number of components constituting the key unit 10 can be reduced, and the key unit 10 can be manufactured at low cost. Further, according to the present embodiment, when attaching the key tops 12 to the frames 14, 15, and 16 of the case 11, it is only necessary to press-fit the rotation shafts 22L and 22R of the key tops 12 into the bearing recesses 17L and 17R of the frames 14, 15, and 16 from the back side of the case 11, and the number of assembly steps can be reduced. Further, the case 11 with a plurality of key tops 12 attached can be handled integrally, and the assembly of the key unit 10 can be facilitated. Note that the key unit 10 of the present embodiment has a configuration in which the rotation shafts 22L and 22R provided at the rear end 12R of the key top 12 are press-fitted and fitted into the bearing recesses 17L and 17R provided in the case 11, but the rotation shaft and the bearing recess may be reversed. Even when the rotation shaft and the bearing recess are reversed, the cylindrical surface 123 at the rear end 12R of the key top 12 and the cylindrical surface 151 on the front surface of the frame 15 are surfaces arranged concentrically with respect to the rotation center of the key top 12.

[0037] FIG. 10 is a perspective view showing a main part of a key unit according to a modification, and FIG. 11 is a side view of the configuration of FIG. 10 as viewed from the direction of arrow F11. The configuration of the modification has the same structure as the above-described embodiment except that the engagement structure of the tip 12F of the key top 12 with respect to the frame 14 is different. Therefore, here, components that function in the same manner as the key unit 10 of the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

[0038] In the modification example, the key top 12 has an engaging convex portion 25 integrally protruding forward from the tip 12F. The engaging convex portion 25 has a bottom surface disposed on the same surface as the back surface 12b of the key top 12 and extends over the entire width of the key top 12 in the left-right direction. Further, the engaging convex portion 25 has a cylindrical surface 251 that curves from the leading edge in the protruding direction toward the end surface 121 of the key top 12. The cylindrical surface 251 curves in a direction bulging upward. The trailing edge of the cylindrical surface 251 is located slightly below the ridge line between the end surface 121 and the inclined surface 122. On the other hand, the frame 14 in front of this key top 12 has a cylindrical surface 142 on its rear surface 14b for engaging the engaging convex portion 25. The cylindrical surface 142 of the frame 14 has a portion that is in surface contact with the cylindrical surface 251 of the engaging convex portion 25 of the key top 12.

[0039] According to the above-described modification example, since the engaging convex portion 25 is provided over the entire width of the key top 12, the mechanical strength can be increased as compared with the engaging convex portion 24 of the above-described embodiment. Further, according to the modification example, since the width of the engaging convex portion 25 in the left-right direction is large, when the key unit 10 is viewed from the front side, the inside of the key unit 10 cannot be seen through the gap between the tip 12F of the key top 12 and the rear surface 14b of the frame 14, and the aesthetic appearance can be improved and the design property can be enhanced.

[0040] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist thereof at the implementation stage. Further, the above-described embodiment includes various inventions, and various inventions can be extracted by combinations selected from a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment and the problem can be solved and the effect can be obtained, the configuration from which these constituent elements are deleted can be extracted as an invention.

Explanation of Reference Numerals

[0041] 1... Circuit board, 2... First housing, 3... Opening, 4... Second housing, 6... Hinge part, 7... Contact rubber sheet, 8... Bulging part, 10... Key unit, 11... Case, 12... Key top, 12a... Surface, 12b... Back surface, 12F... Tip, 12R... Rear end, 121... End face, 122... Inclined surface, 123... Cylindrical surface, 13... Frame part, 13F... Front part, 13R... Rear part, 14, 15, 16... Frame, 15b... Rear surface, 15c... Upper surface, 15d... Lower surface, 151... Cylindrical surface, 17L, 17R... Bearing recess, 171... Bearing part, 172... Groove part, 18... Engaging recess, 18a... First part, 18b... Second part, 185, 186, 187... Inclined receiving surface, 188... Opening, 22L, 22R... Rotation axis, 22a... Support part, 22b... Shaft part, 24... Engaging convex part, 24a... Support part, 24b... Engaging part, 243... Bottom surface, 244... Joint surface, 245, 246, 247... Inclined surface, 248... Top surface, 100... Electronic dictionary.

Claims

1. A frame having a rotating shaft or a bearing, and a key top having a bearing fitted to the rotating shaft of the frame or a rotating shaft fitted to the bearing of the frame, and being rotatably attached to the frame, wherein a first side surface connecting to the upper surface of the key top facing the frame and a second side surface connecting to the upper surface of the frame facing the first side surface are each a cylindrical surface formed by moving a concentric curve centered on the rotating shaft along the rotating shaft, a key unit.

2. The first side surface of the key top and the second side surface of the frame are such that the curve intersecting with a plane orthogonal to the rotating shaft is an arc, and they face each other with a uniform gap therebetween, The key unit according to claim 1.

3. The rotating shaft of the frame and the bearing of the key top, or the bearing of the frame and the rotating shaft of the key top are fitted with play, The gap between the first side surface and the second side surface is sized such that the first side surface and the second side surface come into contact when the key top is twisted with respect to the frame, The key unit according to claim 2.

4. Another frame facing the tip of rotation of the key top is provided, The key top has an engaging convex portion protruding from its tip toward the another frame, The another frame has an engaging concave portion for engaging the engaging convex portion, The engaging concave portion has an opening communicating with the upper surface of the another frame, In a state where the engaging convex portion is engaged with the engaging concave portion, the upper surface of the engaging convex portion is disposed substantially flush with the upper surface of the another frame through the opening of the engaging concave portion, The key unit according to claim 1.

5. The engaging convex portion of the key top has a contact surface inclined with respect to the moving direction of the key top, The engaging concave portion of the another frame has a receiving surface that comes into surface contact with the contact surface, The key unit according to claim 4.

6. The receiving surface includes a plurality of receiving surfaces inclined in different directions, and the contact surface includes a plurality of contact surfaces inclined in the same direction as the plurality of receiving surfaces, The key unit according to claim 5.

7. In an initial state before the key top is pushed in, the upper surface of the key top and the upper surface of the frame are disposed substantially flush with each other, The key unit according to claim 1.

8. An electronic device having the key unit according to any one of claims 1 to 7.

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