KEY INPUT DEVICE

A key input device includes: a key; a member having a hole through which the key is movably inserted; and wall parts separate from each other and extending from an edge of the hole in a direction perpendicular to a board of the device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2023-159324, filed on Sep. 25, 2023, the entire disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a key input device.

DESCRIPTION OF RELATED ART

There is known a key input device that has key tops arranged on a surface. For example, JP1998-207594A discloses a keyboard of a pressing structure that includes key tops, sliders, dome springs, and housings. Each slider is provided on the cylindrical inner wall of the key top and allows the key top to slide along the housing. Each dome spring receives the key top and shows a positive or negative snap characteristic. The housing houses the key top and the dome spring.

SUMMARY OF INVENTION

According to an aspect of the present disclosure, there is provided a key input device including: a key; a member having a hole through which the key is movably inserted; and wall parts separate from each other and extending from an edge of the hole in a direction perpendicular to a board of the device.

DETAILED DESCRIPTION

Hereinafter, an embodiment of the present disclosure is described in detail with reference to the figures. The scope of the present disclosure is not limited to the illustrated examples.

First, the overall configuration of a calculator (electronic desk calculator)1as an electronic device in this embodiment is described with reference toFIG.1toFIG.4.FIG.1is a plan view of the calculator1in this embodiment.FIG.2is a cross-sectional view of the calculator1along the II-II line inFIG.1.FIG.3is a cross-sectional view of the calculator1along the III-III line inFIG.1.

The calculator1is a small calculator that receives key inputs by a user and performs calculations with an internal electronic circuit. The calculator1in this embodiment has keytops the heights of which slope stepwise in the lateral direction when viewed by the user. The calculator1is thus designed such that the key tops fit the dominant hand and fingers of the user. The components of the calculator1related to key inputs constitute a key input device.

As shown inFIG.1toFIG.3, the calculator1includes a top casing10and a bottom casing20as a casing (member) and is placed on a placement surface M1of a table, for example. InFIG.1toFIG.3, three-dimensional axes of X, Y, and Z are shown. The +Z direction is the vertical upward direction with respect to the placement surface M1. The placement surface M1is a two-dimensional XY surface. On the placement surface M1, the X-axis corresponds to the lateral direction (short-side direction) of the calculator1, and the Y-axis corresponds to the longitudinal direction (long-side direction) of the calculator1.

The top casing10is the upper side (+Z direction side) of the calculator1and is made of resin, for example. The top casing10of the calculator1includes a key input section11and a display section12. The key input section11includes multiple keys14and a selector switch15.

The keys14include numeric keys, operation keys, and function keys, for example. The numeric keys include keys for inputting numbers [00], [0] to [09] and for inputting the decimal point [.], for example. The operation keys include keys to be used in four basic arithmetic operations, such as keys for inputting operators of [+] (addition), [−] (subtraction), [×] (multiplication), and [÷] (division) and a key for: inputting [=] (execution of operation), for example. The function keys include an all-clear key [AC], a clear key [C], memory keys [MC], [MR], [M−], and [M+], a square-root key [√], and a percentage key [%], for example.

The selector switch15is a slide switch that includes a rounding selector and a decimal selector, for example. The rounding selector is a switch for specifying how to calculate numbers below the decimal point. The decimal selector is a switch for specifying the digits below the decimal point.

As shown inFIG.1, the exterior of the calculator1has a substantially rectangular shape when viewed from the top surface (+Z direction side). The key input section11is provided on the −Y direction side of the top casing10when the calculator1is viewed from the top surface. The display section12is provided on the +Y direction side of the top casing10.

The display section12includes a display16and a solar panel17on the casing surface12a. The casing surface12ais a region on the +Y direction side of the top surface of the casing. The display16is provided on the −Y direction side of the casing surface12a. The display16has an oblong rectangular display screen, for example. The long side of the display screen of the display16extends from the first end side (the end of the casing in the −X direction) to the second end side (the end of the casing in the +X direction) opposite the first end. The solar panel17is provided on the +Y direction side of the casing surface12a. The solar panel17is an electronic component that converts light energy into electric energy (power) by using the photovoltaic effect.

The key input section11includes the keys14on the casing surface11a. The casing surface11ais a region on the −Y direction side of the top surface of the casing. In the key input section11, the keys14are arranged substantially in a matrix from the first end side toward the second end side of the casing and from the third end side (the end of the casing in the +Y direction) toward the fourth end side (the end of the casing in the −Y direction). The keys14each include a key top141. The key top141has a touch surface141tat the top surface of the key top141. The touch surface141tis a surface to be pressed by a finger of the user for key input. Among the keys14, the direction parallel to the upper side/lower side of the key input section11is referred to as the row direction (FIG.1,FIG.2), and the direction parallel to the left side/right side of the key input section11is referred to as the column direction (FIG.1,FIG.3), for example. The keys14are arranged at predetermined intervals (key pitches) in the row direction and in the column direction.

As shown inFIG.2andFIG.3, the bottom casing20is fitted to the top casing10from the bottom side (the −Z direction side) and has feet21. The bottom casing20is made of resin, for example. The bottom surface of the bottom casing20except the feet21(the casing bottom surface) is formed to be parallel to the placement surface M1. The feet21are made of an elastic body, such as rubber. The feet21are in contact with the placement surface M1when the calculator1is placed on the placement surface M1. The feet21prevent the placed calculator1from slipping and muffle noise when the calculator1is placed.

As shown inFIG.2, the casing surface11aof the key input section11is at a predetermined angle θ1to the casing bottom surface (the placement surface M1, a board40to be described later) in the row direction from the second end side to the first end side. As shown inFIG.3, the casing surface11ais at a predetermined angle θ2to the casing bottom surface (the placement surface M1) in the column direction from the fourth end side to the third end side.

It is preferable that the angle θ1be in the range of 1° to 9°, for example. It is more preferable that the angle θ1be in the range of 1° to 3°. The angle θ1is set to 3°, for example. The angle θ2is set to 3°, for example.

As shown inFIG.2, the height of the casing surface11aof the key input section11from the placement surface M1(board40) decreases from the first end side toward the second end side. Thus, the casing surface11aof the key input section11of the calculator1slopes to the right. The heights of the touch surfaces141tof the keys14from the casing surface11ain the +Z direction are substantially uniform. That is, the height of at least part of the touch surfaces141tof the keys14on the first end side is higher than the height of at least part of the touch surfaces141tof the keys14on the second end side with respect to the placement surface M1.

According to the structure of the calculator1, when the calculator1is used with the right hand of the user (right-handed user), the touch surfaces141tof the keys14fit the hand and fingers of the user. Thus, the calculator1is easy to use and causes less fatigue to the user.

The calculator1may be configured such that the height of the casing surface11aof the key input section11from the placement surface M1(board40) decreases from the second end side toward the first end side, namely such that the casing surface11aslopes to the left, on the assumption that the calculator1is used with the left hand of the user (left-handed user). That is, the height of at least part of the touch surfaces141tof the keys14on the second end side is higher than the height of at least part of the touch surface141tof the keys14on the first end side with respect to the placement surface M1.

On the other hand, regarding the display16of the display section12, the height of the first end side of the display screen from the placement surface M1is not higher than the height of the second end side thereof. In the example shown inFIG.2, the first end side and the second end side of the display section12are at the same height from the placement surface M1.

As shown inFIG.3, the casing of the calculator1is bended at the boundary between the key input section11and the display section12such that the upper side of the top casing surface is raised. That is, the casing surface12aincluding the display section12leans to the casing surface11aincluding the key input section11at a predetermined tilt angle in the +Z direction. Since the casing surface12aincluding the display section12leans in the column direction, the viewability of the display screen of the display16is increased.

The internal configuration of the calculator1is described with reference toFIG.4toFIG.6.FIG.4is an enlarged cross-sectional view of the key14B inFIG.2.FIG.5shows the back surface of the top casing10.FIG.6is an enlarged perspective view of the region VI on the back surface side of the top casing10.

As shown inFIG.1toFIG.4, in the casing (the top casing10and the bottom casing20), the calculator1includes the display16, the solar panel17, the key tops141, rubber keys30as an elastic member, the board40, and a nonwoven fabric sheet50as a sheet member. The key tops141each consist of a base part1411and a key-marking part1412. The base part1411is an outside layer of the key top141. The base part1411is made of resin in the background color of letters (key markings) on the touch surface141t. The key-marking part1412is an inside layer of the key top141. The key-marking part1411is made of resin in the color of letters on the touch surface141t. The key-marking part1412is exposed on the touch surface141tthrough the base part1411to show a letter (key marking). The background color is different from the letter color.

The key top141is formed of the base part1411and the key-marking part1412by two-color molding. By the two-color molding, the letters (key markings) on the touch surfaces141tare prevented from fading even if the touch surfaces141tare physically worn by the pressing of the user. The key top141may not include the key-marking part1412and may be formed by single-color molding.

The key top141includes the touch surface141tand a flange141f. The key top141is arranged such that the touch surface141tis parallel to the flat surface of the board40. The flange141fis a flange-shaped edge part that protrudes in the direction of a plane parallel to the surface of the board40. After the key top141is pressed by the user and moved (stroked) in the direction perpendicular to the board40, the key top141returns in the reverse direction. When the key top141returns, the flange141fabuts the top casing10(the base plate40-side end of wall parts130to be described later) with the nonwoven fabric sheet50inbetween. The flange141fthus stops the key top141.

The rubber key30is a substantially plate-shaped member made of elastic material, such as rubber. The rubber key30includes a flat surface part31and multiple rubber key tops32. The flat surface part31is a flat-shaped base body of the rubber key30and is placed on the flat surface of the board40. The rubber key tops32are arranged at positions corresponding to the key tops141over the flat surface of the board40. The rubber key tops32are substantially dome-shaped spring parts that receive the pressed key tops141. The keys14each include the key top141and the corresponding rubber key top32.

As shown inFIG.4, the rubber key top32includes a connecting part321and a support part322. The connecting part321is connected to the bottom end of the key-marking part1412of the key top141. The connecting part321receives the pressed key top141. The support part322is connected to the flat surface part31and supports the connecting part321such that the connecting part321is at a predetermined distance from the flat surface of the board40in the direction perpendicular to the flat surface of the board40toward the top surface. In a case where the key top141does not include the key-marking part1412, the connecting part321may be connected to the bottom of the key top141instead of the bottom of the key-marking part1412.

The connecting part321of the rubber key top32is connected to the corresponding key top141such that the moving direction (keystroke direction) of the key top141is perpendicular to the flat surface of the board40.

In a normal state, the support part322holds the connecting part321at a distance from the board40so that the key top141, which is mounted on the connecting part321, is movable when being pressed. When the key top141is pressed, the connecting part321is pressed until being in contact with the board40. The bottom of the connecting part321is provided with a conductive member. When the connecting part321is pressed down along with the key top141, the conductive member is brought into contact with an electrode provided on the board40to detect the press of the key. By the contact between the conductive member of the connecting part321and the electrode of the board40, electrodes corresponding to the key14on the board40are electrically connected. Thus, the press of the key14is input.

The rubber key tops32that correspond to the key tops141having the same-sized touch surfaces141tare made uniform so that the key tops141having the same-sized touch surfaces141tgive the same operability (click feeling) when pressed. That is, the rubber key tops32that correspond to the key tops141having the same-sized touch surfaces141tare made of the same material in the same shape and dimensions so that the rubber key tops32have a substantially equal amount of mass.

The click feeling refers to the feeling of the user when he/she presses the key top141and recognizes the restoring force (repulsive force) of the buckled or compressed rubber key top32made of elastic material.

The board40is a printed circuit board (PCB) that supports the keys14in the casing. On the board40, the keys14, circuit elements and so forth are mounted. The casing surface11aof the top casing10is formed and positioned such that the casing surface11ais parallel to the flat surface of the board40in the cross section along the column direction and such that the casing surface11aslopes to the board40at the angle θ1in the cross section along the row direction.

The nonwoven fabric sheet50is a sheet of nonwoven fabric placed between the flanges14fof the keys14and the top casing10(the wall parts130to be described later). When the key top141returns to its original position by the restoring force of the rubber key top32after being pressed, the direct contact of the flange141fto the top casing10produces a large sound. The nonwoven fabric sheet50prevents the direct contact of the flange141fto the top casing10and absorbs the contact force, thereby reducing the contact sound (keystroke sound) generated by the returning of the key top141. The calculator1may not include the nonwoven fabric sheet50.

The structure of the top casing10is described with reference toFIG.5andFIG.6. As shown inFIG.2,FIG.4andFIG.5, the casing surface11aof the top casing10has holes101as openings. The holes101are arranged to correspond to the key tops141of the keys14. The key tops141are inserted through the holes101, and the holes101guide the movement of the key tops141and expose the touch surfaces141ton the top surface (substantially toward the +Z direction). The shapes of the holes101correspond to the shapes of the touch surfaces141t. For example, the holes101have a rectangle shape with rounded four corners.

As shown inFIG.5andFIG.6, the top casing10includes boss parts110, rib parts120, and wall parts130as one body on a casing surface11b. The boss parts110and the rib parts120serve as rib parts. The casing surface11bis the back side (the-Z direction side) of the casing surface11a. The boss parts110, the rib parts120, and the wall parts130are provided at crossing regions11c, not at key pitch regions11p. The key pitch regions11pare side regions between the adjacent holes101in the X-axis direction or the Y-axis direction. The crossing regions11care regions each including a crossing region (intersection) where the extended regions of the key pitch regions11pare crossed.

The boss parts110are internal screw parts for screwing the board40or the bottom casing20to the top casing10with not-illustrated external screws. The boss parts110each include a boss111and ribs112. The boss111extends from the casing surface11bin the direction perpendicular to the flat surface of the board40. There are relatively low bosses11to be screwed to the board40and relatively high bosses111to be screwed to the bottom casing20. The ribs112are flat-surface ribs connected to the boss111in the radial direction from the axis of the boss111. The boss part110has one boss111and four ribs112attached to the boss111, for example, and the ribs112form a cross shape when viewed from the back side.

The ribs112are arranged to hold the rubber key30between the ribs112and the board40. The ribs112have a function of reinforcing the boss111to prevent the boss111from falling and a function of holding and fixing the rubber key30between the ribs112and the board40.

The rib parts120each include a support121and ribs122. The axis of the support121extends from the casing surface11bin the direction perpendicular to the flat surface of the board40. There are relatively low supports121that correspond to the flat surface of the rubber key30and relatively high supports121that extend beyond the flat surface of the rubber key30to position the rubber key30against the board40. The ribs122are flat-surface ribs connected to the support121in the radial direction from the axis of the support121. The rib part120has one support121and four ribs122attached to the support121, and the ribs122form a cross shape when viewed from the back side, for example.

The ribs122are arranged to fix the rubber key30or to hold the rubber key30between the ribs122and the board40. Thus, the ribs122have a function of fixing the rubber key30or holding and fixing the rubber key30between the ribs122and the board40.

Either a boss part110or a rib part120is placed on each of the crossing regions11con the top casing10. The positions and the number of boss parts110and rib parts120(the ratio between the boss parts110and the rib parts120) is appropriately determined in consideration of the shapes and weight balance of the components of the calculator1, weight saving of the calculator1, and secure fastening of the casing.

The wall parts130are arranged on the crossing regions11cso as to correspond to the four corners of the adjacent holes101. The wall parts130extend from the casing surface11bin the direction perpendicular to the flat surface of the board40. The wall parts130each include a round wall-shaped edge portion, for example. The wall parts130are separate from each other and extend from the edges of the holes101in the direction perpendicular to the board40. At the edge of each of the holes101, the top casing10includes a space region11sbetween the wall parts130, which are separate from each other. For example, the top casing10includes the space region11sbetween a wall part130located at the first end side and the third end side and a wall part130located at the second end side and the third end side. Similarly, the top casing10includes the space region11sbetween a wall part130located at the first end side and the third side end and a wall part130located at the first end side and the fourth end side. Similarly, the top casing10includes a space region11sbetween a wall part130located at the first end side and the fourth end side and a wall part130located at the second end side and the fourth end side. Similarly, the top casing10includes a space region11sbetween a wall part130located at the second end side and the third side end and a wall part130located at the second end side and the fourth end side. The space regions11sare each located between adjacent holes101(the key tops141inserted in the adjacent holes101) in the row direction or in the column direction. That is, the space regions11sare each located in the key pitch region11p.

The wall parts130are arranged to hold the nonwoven fabric sheet50between the wall parts130and the flanges141f. As shown inFIG.2andFIG.4, regarding one hole101in the row direction, the height of the first end side edge of the hole101from the flat surface of the board40is higher than the height of the second end side edge of the hole101from the flat surface of the board40. Regarding multiple holes101in the row direction, the height of the first end side edge of the hole101from the flat surface of the board40is higher than the height of the second end side edge of the hole101from the flat surface of the board40. As shown inFIG.3, regarding one hole101or multiple holes101in the column direction, the height of the third end side edge of the hole101from the flat surface of the board40is substantially equal to the height of the fourth end side edge of the hole101from the flat surface of the board40. As shown inFIG.2toFIG.4, the distance between the flat surface of the board40and each of the board40-side ends of the ribs130is substantially uniform in the row direction and the column direction.

On the first end side of the top casing10, the heights of the wall parts130(the lengths of the wall parts130in the direction perpendicular to the board40) are substantially uniform. The height of a wall part130is defined between the edge of the hole101and the board40-side end of the wall part130. Thus, in an identical column between the first end and the second end, the heights of the wall parts130, which are defined between the edges of the hole101and the board40-side ends of the wall parts130, are substantially uniform. Further, the heights of the wall parts130formed on the second end side of the top casing10are lower than the heights of the wall parts130formed on the first end side. Thus, in an identical row, the heights of the wall parts130on the top casing10decrease from the first end side toward the second end side.

The wall parts130are configured to guide the key tops141in the moving direction (keystroke direction) when the key tops141are pressed. The lateral surface of each key top141faces the inner lateral surface of the corresponding hole101and the corresponding wall parts130with a narrow gap inbetween. In this embodiment, the lateral surface of the key top141is at a predetermined angle (e.g., 1.5 degrees) to the inner lateral surface of the hole101and the wall parts130. However, the lateral surface of the key top141may be substantially parallel to the inner lateral surface of the hole101and the wall parts130. The wall parts130are configured to receive the flange141f with the nonwoven fabric sheet50inbetween when the pressed key top141returns. The wall parts130extend from the holes101in the moving direction (keystroke direction) of the key tops141. Within the range of the narrow gap, the wall parts130restrain the key tops141from wobbling when the key tops141are stroked.

A known calculator has rib parts similar to the wall parts130in key-pitch regions (e.g., key-pitch regions extending in the column direction) as well as in crossing regions. According to such a known calculator, the contact area between the rib parts and the key top141when the pressed key top141returns is relatively large. According to the present disclosure, the wall parts130are formed only on the crossing regions11cand not formed on the key pitch regions11p. Therefore, the contact area between the wall parts130and the key top141when the pressed key top141returns is relatively small. Further, the top casing10does not have members that contribute to sound reflection, such as rib parts formed on the key pitch regions11p. Therefore, the stroke sound of the key tops141is reduced as compared with the known calculator. Reduction of the keystroke sound means that the volume and pitch of the keystroke sound does not disturb the user.

On the cross section along the row direction inFIG.2, the keys14arranged in the row direction from the first end side toward the second end side are referred to as a key14A, a key14B, a key14C, a key14D, and a key14E in order. The touch surfaces141tof the key tops141of the keys14A to14E are substantially at the same height from the casing surface11ain the +Z direction. By the angle θ1, the heights of the touch surfaces141tof the key tops141of the keys14A to14E from the flat surface of the board40are as follows: key14A>key14B>key14C>key14D>key14E.

In the row direction, the difference in heights of the touch surfaces141tof the key tops141of two adjacent keys14from the board40is substantially the same. In the row direction, the heights of the key tops141themselves of the keys14in the vertical direction from the flat surface of the board40are as follows: key14A>key14B>key14C>key14D>key14E. Thus, the heights of the touch surfaces141tof the keys14from the flat surface of the board40change stepwise in the row direction, depending on the angle θ1of the casing surface11a.

As shown inFIG.2andFIG.3, the touch surfaces141tof the key tops141are formed to be parallel to the flat surface of the board40. In the row direction inFIG.2, the key tops141of the keys14A to14E have the same moving length (keystroke length), which is determined by the movable range of the rubber key tops32and the wall parts130. The rubber key tops32of the respective keys14A to14E have a common structure (the same structure) made of the same material in the same shape (mass). Therefore, the keys14A to14E provide substantially the same touch feeling, and the difference in keystroke sound among the keys14is reduced.

In the cross section in the column direction inFIG.3, the keys14arranged from the fourth end side to the third end side are referred to as a key14F, a key14G, a key14H, a key14I, a key14J, and a key14K in order. By the angle θ2, the heights of the touch surfaces141tof the key tops141of the keys14F to14K from the placement surface M1are as follows: key14K>key14J>key14I>key H>key14G>key14F.

The heights of the touch surfaces141tof the key tops141of the keys14F to14K from the casing surface11aare substantially uniform. Further, the heights of the key tops141themselves of the keys14F to14K in the +Z direction are substantially uniform. Therefore, in the column direction, the heights of the touch surfaces141tof the keys14F to14K from the flat surface of the board40are substantially the same regardless of the angle θ2. Further, the wall parts130corresponding to the key tops141of the respective keys14F to14K are substantially at the same height from the flat surface of the board40in the +Z direction.

The key tops141of the keys14F to14K have the same moving length (keystroke length), which is determined by the movable range of the rubber key tops32and the wall parts130. The rubber key tops32of the keys14F to14K have a common structure (the same structure) made of the same material in the same shape (mass). Therefore, in the column direction, the keys14F to14K provide substantially the same touch feeling, and the difference in keystroke sound among the keys14is substantially the same.

As described above, according to the embodiment, the calculator1includes a key14, a top casing10, and wall parts130. The top casing10has a hole101through which the key14is movably inserted. The wall parts130are separate from each other, and each of the wall parts130extends from the edge of the hole101of the top casing10in the direction perpendicular to the board40of the calculator1.

With such wall parts130, the contact area between the key top141and the top casing10is reduced, and the keystroke sound of the key top141is reduced, as compared with a known calculator.

Further, the calculator1includes a space region11sbetween the wall parts130on the top casing10. The top casing10has multiple holes101. The space region11sis located between adjacent keys14in the row direction or the column direction. With such wall parts130, the contact area between the top casing10and the key tops141is reduced as compared with a known calculator, and the keystroke sound of the key tops141is reduced as compared with a known calculator, and the material cost for the top casing10is reduced.

Further, the key14includes a flange141f. The flange141fis configured to be in contact with the board40-side ends of the wall parts130when the pressed key top141returns. With such a flange141fand wall parts130, the contact area between the top casing10and the key tops141is reduced, and the keystroke sound of the key tops141is reduced, as compared with a known calculator.

Further, the height of a wall part130is defined between the edge of the hole101and the board40-side end of the wall part130; the heights of the wall parts130formed on the first end side of the top casing10are substantially uniform (substantially the same); and the heights of the wall parts130formed on the second end side, which is opposite the first end side, of the top casing10are lower than the heights of the wall parts130formed on the first end side. Therefore, according to the calculator1, the heights of the touch surfaces141tof the key tops141on the first end side from the board40are higher than the heights of the touch surfaces141tof the key tops141on the second end side from the board40. Further, the keystroke sound of the key tops141on the first end side and the second end side is reduced, and the difference in the keystroke sound between the first end side and second end sides is reduced.

Further, the heights of the touch surfaces141tof the keys14from the board40on the first end side are higher than the heights of the touch surfaces141tof the keys14from the board40on the second end side. Therefore, the key tops141of the calculator1fit the hand and fingers of the user better than a known calculator.

Further, the calculator1includes a nonwoven fabric sheet50placed between the board40and the rib parts130. With the nonwoven fabric sheet50, the impact of the returning key tops141on the rib parts130is reduced, and the keystroke sound of the returning key tops141is reduced as compared with a known calculator. Since the calculator1is configured such that the distance between the board40and each of the board40-side ends of the rib parts130is substantially uniform, one sheet of the nonwoven fabric sheet50can reduce the difference in the keystroke sound of the returning key tops141, as compared with a known calculator.

Further, the calculator1includes a rubber key30configured to restore its shape after receiving the pressed key14; and boss parts110and rib parts120that hold the rubber key30between the board40and the boss parts110and the rib parts120. With the boss parts110and the rib parts120, the rubber key30is precisely and appropriately fixed against the board40.

The above-described embodiment is an example of the key input device according to the present disclosure and is not intended to limit the present disclosure.

For example, although the electronic device is the calculator1in the above embodiment, the electronic device is not limited to a calculator. The electronic device may be a device other than a calculator that has multiple keys arranged stepwise and that is used with one hand of the user for key inputs, for example. More specifically, the electronic device may be a remote controller of various kinds of devices, a handy terminal, an external numeric keypad for a personal computer (PC), and a device for inputting PIN numbers, for example.

Although an embodiment of the present disclosure has been described, the scope of the present invention is not limited to the embodiment described above but encompasses the scope of the disclosure recited in the claims and the equivalent thereof.