Patent Application
20180190448
The present invention relates to a key switch and a keyboard.
A keyboard including multiple key switches is known as one type of information input device used, for example, for a computer.
A known key switch includes a support mechanism that supports a key top to be pressed, a rubber cup that elastically biases the key top upward, and a membrane switch including contacts that are pressed and connected to each other when the key top is pressed (Patent Document 1).
[Patent Document 1] Japanese Laid-Open Patent Publication No. 2003-263257
When a key switch includes two pairs of contacts that are intended to be turned on at the same time when a key top is pressed, the two pairs of contacts may not be reliably turned on because the force and manner of pressing the key top vary depending on operators.
One exemplary object according to an aspect of the present invention is to provide a key switch and a keyboard configured such that multiple pairs of contacts can be reliably turned on.
According to an aspect of the present invention, a key switch includes a movable part configured to be moved by a pressing operation, a support mechanism that movably supports the movable part, an electrical connector including multiple pairs of contacts of upper electrodes and lower electrodes, and a disc spring that is disposed between the movable part and the electrical connector and configured to be elastically deformed by movement of the movable part and to press the electrical connector. The multiple pairs of contacts are provided for one movable part. When the disc spring is deformed by the movement of the movable part, the disc spring is configured to simultaneously press the multiple pairs of contacts provided for the corresponding movable part.
An aspect of the present invention makes it possible to reliably turn on multiple pairs of contacts.
Non-limiting embodiments of the present invention are described below with reference to the accompanying drawings.
Throughout the accompanying drawings, the same or corresponding reference numbers are assigned to the same or corresponding components, and repeated descriptions of those components are omitted. Unless otherwise mentioned, the drawings do not indicate relative sizes of components. A person skilled in the art may determine actual sizes of components taking into account the embodiments described below.
The embodiments described below are examples, and the present invention is not limited to those embodiments. Also, not all of the features and their combinations described in the embodiments may be essential to the present invention.
The keyboard 100 includes key switches 1, a base 21, a support 22, and the membrane sheet 23.
The key switches 1 are attached to the base 21. The base 21 is a metal plate and has a strength that is sufficient to hold the key switches 1. Frames 21a for supporting the linking parts 11 and 12 are formed on a surface of the base 21.
Each key switch 1 includes a key top 10 to be operated by an operator, a gear link mechanism 13 that supports the key top 10 such that the key top 10 is movable in a vertical direction, the membrane sheet 23 including a switch that opens and closes when pressed by the key top 10, and a disc spring 51 that biases the key top 10 in a direction away from the base 21.
The key top 10 includes a pressing part 10a that is in contact with the disc spring 51 and presses the disc spring 51. The pressing part 10a is disposed in an inner central region of the key top 10. The pressing part 10a includes insertion parts 10b that are slits formed in an end portion of the pressing part 10a.
The gear link mechanism 13 is an example of a support mechanism and includes two linking parts 11 and 12. The key top 10 is supported on the base 21 by the linking parts 11 and 12. The linking parts 11 and 12, respectively, include sliding shafts 11a and 12a at first ends and rotational shafts 11b and 12b at second ends.
The sliding shafts 11a and 12a of the linking parts 11 and 12 are inserted into the frames 21a of the base 21, and are supported by the frames 21a so as to be slidable along the surface of the base 21. The rotational shafts 11b and 12b are inserted into the insertion parts 10b formed in the pressing part 10a and are rotatably supported by the insertion parts 10b.
Also, as illustrated in
As illustrated in
Each of the upper layer 24 and the lower layer 26 is formed of polyethylene terephthalate (PET). Upper electrodes 31 and 32 are printed on the upper layer 24 and lower electrodes 27 and 28 are printed on the lower layer 26 by using a conductive paste.
The spacer 25 forms a gap between the upper layer 24 and the lower layer 26. The spacer includes a hole 25a in a position facing the disc spring 51 to form a gap 91 between the upper layer 24 and the lower layer 26.
In an area of the lower layer 26 corresponding to the gap 91, a contact 27a of the lower electrode 27 and a contact 28a of the lower electrode 28 are formed. In an area of the upper layer 24 corresponding to the gap 91, a contact 31a of the upper electrode 31 and a contact 32a of the upper electrode 32 are formed. As illustrated in
The contacts 27a, 28a, 31a, and 32a are disposed in an area 92 of the membrane sheet 23 that is to be pressed by the disc spring 51. The contacts 27a and 32a face each other in the vertical direction, and the contacts 28a and 31a face each other in the vertical direction. The contact 27a of the lower electrode 27 and the contact 32a of the upper electrode 32 form one pair of contacts, and the contact 28a of the lower electrode 28 and the contact 31a of the upper electrode 31 form one pair of contacts.
With the contacts 27a, 28a, 31a, and 32a formed as described above, the membrane sheet 23 is configured such that two pairs of contacts are provided for one disc spring 51 (or one key tope 10). Thus, with the key switch 1 of the present embodiment, the pair of the contact 27a of the lower electrode 27 and the contact 32a of the upper electrode 32 and the pair of the contact 28a of the lower electrode 28 and the contact 31a of the upper electrode 31 are simultaneously turned on when the key top 10 is operated.
The lower electrodes 27 and 28 and the upper electrodes 31 and 32 of the membrane sheet 23 are connected to the drive circuit 41. The drive circuit 41 is connected to an apparatus 44 such as a personal computer.
The drive circuit 41 includes a first control circuit 42 connected to the lower electrode 28 and the upper electrode 31, and a second control circuit 43 connected to the lower electrode 27 and the upper electrode 32. In the present embodiment, the first control circuit 42 and the second control circuit 43 are mutually-independent electric circuits. For example, the drive circuit 41 outputs a signal to the apparatus 44 when a control signal output by the first control circuit 42 and a control signal output by the second control circuit 43 are identical to each other. However, the method of outputting a signal is not limited to this example.
The disc spring 51 is disposed between the membrane sheet 23 and the key top 10. More specifically, the disc spring 51 is disposed between the support 22 disposed on the membrane sheet 23 and the lower surface of the pressing part 10a.
The disc spring 51 includes a pressed part and a skirt part 53. The pressed part 52 is in contact with the pressing part 10a of the key top 10, and is located in the middle of the disc spring 51. The skirt part 53 buckles when the pressed part is pressed and a load is applied to the disc spring 51. The skirt part 53 is shaped like a skirt and extends from the periphery of the pressed part 52 toward the support 22.
Next, workings of the key switch 1 are described with reference to
When the key top 10 is pressed by an operator in a state as illustrated in
As illustrated in
When the key top 10 is pressed, the pressing part 10a presses the pressed part 52 of the disc spring 51. When the key top 10 is pressed a predetermined distance, the disc spring 51 buckles and is reversed upside down, and the pressed part 52 presses the upper layer 24 of the membrane sheet 23.
The area 92 in
An area 93 in
When the disc spring 51 buckles and is reversed, the pressed part 52 presses the area 92, and the upper layer 24 is deformed. As a result of the deformation, the pair of the contact 27a and the contact 32a and the pair of the contact 28a and the contact 31a are turned on simultaneously.
Pressing characteristics of the key switch 1 using the disc spring 51 are described below. The pressing characteristics of a key switch indicate a relationship between the load of pressing a key top and a stroke (moved distance) of the key top.
In
The pressing characteristics obtained while the key top is pressed are different from the pressing characteristics obtained while the key top is pushed back by a disc spring or a rubber cup. Accordingly, as illustrated in
First, the pressing characteristics of a key switch using a rubber cup are described with reference to
When the key top is pressed, the rubber cup is pressed by the key top moving downward, and the rubber cup is elastically deformed. The elastic force of the rubber cup generated by the elastic deformation is applied to the key top and pushes the key top upward. As a result, the pressing load of the key top gradually increases.
In the example of
When the key top reaches a position (B2) corresponding to a moved distance of about 1.10 mm, the rubber cup contacts the membrane sheet. In this state, the lower electrodes and the upper electrodes of the membrane sheet are still apart from each other, and the pairs of contacts are not turned on.
When the key top is further pressed from this state, the rubber cup presses the membrane sheet, and the upper layer of the membrane sheet is deformed toward the lower layer. When the upper layer is deformed, a force to push the key top upward is generated in the membrane sheet. Accordingly, after the moved distance of the key top exceeds about 1.10 mm, the load to press the key top increases.
As the key top is pressed further, the upper layer is further deformed toward the lower layer, and the upper electrodes contact and are electrically connected to the lower electrodes. In the example of
When the key top is pressed further and the upper layer is deformed up to a deformation limit position, further movement of the key top is prevented. In the example of
When the force pressing the key top is removed and the key top returns to a position (B5) corresponding to a moved distance of about 1.22 mm, the upper electrodes are disconnected from the lower electrodes and the switch is turned off. When the key top reaches a position (B6) corresponding to a moved distance of about 1.50 mm, the rubber cup moves away from the upper layer. When the key top reaches a position (B7) corresponding to a moved distance of about 0.50 mm, the buckled rubber cup is restored to its original shape and the key top returns to its original state before being pressed.
In the case of the key switch using the rubber cup as an elastic part, the moved distance of the key top from a position (B1) where the rubber cup starts to buckle to a position (B3) where the upper electrodes are connected to the lower electrodes is comparatively long. More specifically, the key top moves about 0.78 mm from the position B1 (moved distance is about 0.50 mm) to the position B3 (moved distance is about 1.28 mm). The key top moves from the position B1 to the position B3 as a result of being pressed by an operator.
That is, in the key switch using the rubber cup, the upper electrodes are connected to the lower electrodes by a pressing force of the operator pressing the key top.
However, the force and manner of pressing the key top vary depending on operators. Therefore, with the key switch using the rubber cup, when the operator does not press the key top with a force sufficient to simultaneously turn on the two pairs of contacts or the operator presses a part of the key top that is away from the center of the key top, the two pairs of contacts may not be reliably turned on at the same time. Also, with the key switch using the rubber cup, it is necessary to press the rubber cup by continuously pressing the key top a predetermined distance from a position where the rubber cup starts to deform to a position where the pairs of contacts are turned on. However, when, for example, the manner of applying a force to the key top changes while pressing the key top, the timing when a pair of contacts is turned on may become different from the timing when another pair of contacts is turned on, and the two pairs of contacts may not be turned on simultaneously. Next, the pressing characteristics of the key switch 1 using the disc spring 51 of the present embodiment are described with reference to
When an operator presses the key top 10 in a state illustrated in
In the example of
When the disc spring 51 buckles, the pressed part 52 initially protruding upward toward the pressing part 10a in
The skirt part 53 of the disc spring 51 buckles when a certain load (about 0.6 N in the present embodiment) is applied to the disc spring 51, and due to the buckling, the pressed part 52 instantaneously moves in the pressing direction and presses the upper layer 24 as illustrated in
Due to the buckling of the disc spring 51, when the key top 10 moves about 1.38 mm, the load on the key top 10 drastically decreases from the load (about 0.8 N) indicated by A1 to the load (about 0.6 N) indicated by A2 in
The pressed part 52 reversed due to the buckling of the disc spring 51 presses the area 92 of the upper layer 24 of the membrane sheet 23 toward the lower layer 26. As a result, the upper layer 24 is deformed toward the lower layer 26, and the pair of the contact 27a of the lower electrode and the contact 32a of the upper electrode 32 and the pair of the contact 28a of the lower electrode 28 and the contact 31a of the upper electrode 31 are connected, respectively, and the switch is turned on.
When the key top 10 is pressed further after the upper electrodes 31 and 32 are connected to the lower electrodes 27 and 28, the key top 10 moves further downward because the disc spring 51 can elastically deform slightly even after the buckling. When the key top 10 reaches a movement limit position of the key top 10 corresponding to a moved distance of about 1.83 mm (A3), the movement of the key top 10 is prevented also due to the presence of the disc spring 51.
When the force pressing the key top 10 is removed, the key top 10 moves in a direction opposite the pressing direction due to the restoring force of the elastically-deformed disc spring 51. Still, however, the disc spring 51 is in the buckled state until the key top 10 reaches a position (A4) corresponding to a moved distance of about 1.08 mm.
When the key top 10 reaches the position A4 corresponding to a moved distance of about 1.08 mm, the disc spring 51 is restored to its previous state before the buckling. When the disc spring 51 is restored to the previous state, the pressed part returns to its original state and moves away from the upper layer 24. As a result, the pair of the contact 27a of the lower electrode 27 and the contact 32a of the upper electrode 32 and the pair of the contact 28a of the lower electrode 28 and the contact 31a of the upper electrode 31 are disconnected, respectively, and the switch is turned off.
Also, when the disc spring 51 is restored to the previous state, the load on the key top 10 increases as indicated by A5. Thereafter, the key top 10 moves upward due to the restoring force of the disc spring 51 and returns to a state before being pressed.
In the key switch 1 of the present embodiment, the area 92 of the upper layer 24 is pressed by a reversing force of the buckled disc spring 51 and the two pairs of contacts are thereby turned on.
Because the buckling of the disc spring 51 does not occur locally, the pressed part 52 reversed as a result of the buckling uniformly presses the entire area 92 of the upper layer 24. Also, the force with which the pressed part 52 presses the upper layer 24 is not the force with which the operator presses the key top 10, but is the reversing force generated when the disc spring 51 is reversed. As a result of the buckling of the disc spring 51, the pressed part 52 instantaneously moves downward and presses the upper layer 24. Accordingly, even if an off-center portion of the key top 10 is pressed by the operator, it does not affect the connection between the upper electrodes 31 and 32 and the lower electrodes 27 and 28. Further, different from a case where a rubber, cup is used, because the pressed part 52 of the buckled disc spring 51 is instantaneously reversed, the upper layer 24 is pressed by the pressed part 52 substantially at the same time as the disc spring 51 starts to buckle. This in turn makes it possible to simultaneously press and turn on two pairs of contacts immediately after the disc spring 51 starts to buckle, and thereby makes it possible to prevent the two pairs of contacts from being turned on at different timings.
As described above, the configuration of the key switch 1 of the present embodiment makes it possible to evenly and uniformly press the area 92 where the pair of the upper electrode 32 (the contact 32a) and the lower electrode 27 (the contact 27a) and the pair of the upper electrode 31 (the contact 31a) and the lower electrode 28 (the contact 28a) are formed, and thereby makes it possible to reliably turn on multiple pairs of contacts at the same time.
Next, variations of the upper electrode and the lower electrode of the key switch are described.
In the above example, each of the contacts 27a, 28a, 31a, and 32a of the electrodes 27, 28, 31, and 32 of the key switch 1 has a semicircular shape. However, the shape of the contacts of the upper electrodes and the lower electrodes is not limited to the semicircular shape, and other types of electrode patterns may be used.
Other examples of upper and lower electrode patterns are described below with reference to
An upper layer 62 in
Contacts 33a of the upper electrode 33 and a contact 34a of the upper electrode 34 are arranged alternately and extend parallel to each other in the area 92. The upper electrode 33 branches into two contacts 33a, and the contact 34a is disposed between the two contacts 33a.
An upper layer 63 in
The upper electrode 35 branches into two contacts 35a, and the upper electrode 36 branches into two contacts 36a. The contacts 35a and the contacts 36a are arranged alternately and extend parallel to each other in the area 92.
An upper layer 64 in
The upper electrodes 37 and 38, respectively, include contacts 37a and 38a that have a fan-like shape in plan view. The contacts 37a and the contacts 38a are arranged alternately in the circumferential direction in the area 92. Also, the two contacts 37a are arranged to face each other across the center of the area 92, and the two contacts 38a are arranged to face each other across the center of the area 92.
An upper layer 65 in
The upper electrodes 39 include four contacts 39a shaped like an isosceles triangle, and the upper electrodes 40 include four contacts 40a shaped like an isosceles triangle. The contacts 39a and the contacts 40a are arranged alternately. Also, each pair of two contacts 39a in the four contacts 39a are arranged to face each other in the area 92, and each pair of two contacts 40a in the four contacts 40a are arranged to face each other in the area 92.
As illustrated in
Embodiments of the present invention are described above. However, the present invention is not limited to the specifically disclosed embodiments, and variations and modifications may be made without departing from the scope of the present invention.
In the key switch 1 of the above embodiment, the disc spring 51 is used as an elastic part disposed between the key top 10 and the membrane sheet 23. However, an embossed sheet illustrated in
The embossed sheet 55 includes a sheet 56 and convex parts 57 formed on the sheet 56. Each convex part 57 buckles when pressed. Thus, the embossed sheet 55 can be used in place of the disc spring 51.
Also in the above embodiment, the gear link mechanism 13 is used as a support mechanism for supporting the key top. However, any other support mechanism such as a pantograph mechanism may be used to support the key top.
The key top 10 and the pressing part 10a are examples of a movable part.
The linking parts 11 and 12 and the frames 21a are examples of a support mechanism.
The membrane sheet 23 is an example of an electrical connector.
The disc spring 51 is an example of a disc spring.
Each of the upper layers 24, 62, 63, 64, and 65 is an example of an electrode sheet including a resin sheet on which upper electrodes are formed.
The lower layer 26 is an example of a printed-circuit board on which lower electrodes are printed.
The point at which the load indicated by A1 drastically decreases to the load indicated by A2 is an example of a load decreasing point at which the load of pressing the movable part first decreases after the movable part starts to be pressed.
The keyboard 100 is an example of a keyboard.
The present international application is based on and claims the benefit of priority of Japanese Patent Application No. 2015-133045 filed on Jul. 1, 2015, the entire contents of which are hereby incorporated herein by reference.
A keyboard and a key switch of the present embodiment may be used, for example, for a console panel of an industrial machine and an operations panel of medical equipment. Although the key switch of the present embodiment is included in a keyboard, the key switch of the present embodiment may be used for any apparatus that requires key input.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-133045 | Jul 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/067208 | 6/9/2016 | WO | 00 |
