Patent Application
20090277766
The present invention relates to an elastic member for a pushbutton switch with which input operation is carried out for electronics and the like.
Conventional pushbutton switches with which input operation is carried out for electronics are provided with an elastic member placed beneath the key-top. This elastic member provides elastic resilience against the operator when the pushbutton is pressed down, and generates a clicking sensation when the pushbutton is displaced by a certain amount in a stroke. As shown in
In such pushbutton switches where elastic deformation of an elastic member is used, the sensation that the operator feels when pressing down the pushbutton switch is characterized by the relationship between the load applied to the pushbutton switch by the operator pressing down the button (load the operator receives from the pushbutton switch) and the distance by which the button is pressed down, that is, the stroke.
Various tactile sensations at the time of operation may be required for such pushbutton switches, depending on the application. In order to gain the desired tactile sensation, it is required in the load-stroke characteristics shown in
As a method for meeting the requirement (1), an elastic member may be incorporated in a pushbutton switch in such a state as to be compressed in advance by the housing or the like (hereinafter referred to as advance compression). In addition, as a method for meeting the requirement (2), Patent Document 1, for example, discloses an elastic member shown in
In the case where it is additionally desired for the requirement (1) to be met in the elastic member having an annular protrusion in the top portion, which receives pressure, as described in Patent Document 1, however, the form of the pressing portion is sometimes lost, because the annular protrusion is already deformed in the initial state, where the elastic member is incorporated in the pushbutton switch in such a state as to be compressed in advance. Therefore, the stroke S1 intended in the elastic member may not be gained, and it may become difficult to adjust the peak stroke. Furthermore, the annular protrusion, which is expected to elastically change in form after connection is made, is already deformed, and therefore, the desired increase in the resilient load sometimes cannot be gained.
Accordingly, pushbutton switches are advantageous for meeting various requirements in terms of the tactile sensations at the time of operation in the case where it is possible in the load-stroke characteristics of the pushbutton switch shown in
Accordingly, an objective of the present invention is to provide an elastic member for a pushbutton switch which enables gentle increase in the resilient load in the case where pressing is continued after the protrusion of the elastic member makes contact with the switch elements. Another objective of the present invention is to enable easy adjustment of the peak stroke in the elastic member for a pushbutton switch.
In order to achieve the above described objects and in accordance with one aspect of the present invention, an elastic member for a pushbutton switch is provided. The elastic member includes a base portion, a connection portion which extends from the base portion, a pressing portion which is supported above the base portion by the connection portion, and a protrusion which protrudes downward from the pressing portion. In this elastic member for a pushbutton switch, the protrusion is hollow.
According to one embodiment of the present invention, the pressing portion of the elastic member for a pushbutton switch has an opening which continues from the hollow portion of the protrusion, and the hollow portion and the opening have a constant cross-sectional form.
According to one embodiment, in the case where the protrusion is substantially cylindrical, the inner diameter of the hollow portion of this protrusion is preferably 40% to 90%, and more preferably 40% to 80% of the outer diameter of the protrusion.
According to one embodiment, the base portion is annular and shaped like a plate, the connection portion is shaped like a truncated cone and extends diagonally upward from the inner periphery of the base portion, and the pressing portion is substantially shaped like a disc.
According to one embodiment, the base portion is made up of a pair of prism shaped base portions which are placed at a distance from each other, the connection portion is shaped like a thin plate and extends diagonally upward from the respective upper ends of the pair of base portions which face each other, and the pressing portion is shaped like a rectangular plate. Furthermore, the hollow portion of the protrusion may have an opening on a side of the protrusion.
According to one embodiment, the elastic member for a pushbutton switch may be provided with a conductive portion on the lower surface of the protrusion.
The elastic member for a pushbutton switch may be formed of a rubber-like elastic body.
According to one embodiment, the rubber-like elastic body may be made of silicone rubber.
a) is a graph showing the load-stroke characteristics in the structure for a pushbutton switch using the elastic member of Example 1;
a) is a graph showing the load-stroke characteristics in the structure for a pushbutton switch using the elastic member of Example 2;
The elastic member 100 is provided with an annular plate-shaped base portion 3, a connection portion 2 which is thin and extends diagonally upward from the inner periphery of the base portion 3, and a substantially disc-shaped pressing portion 1 which is supported above the base portion 3 by the connection portion 2. According to the present embodiment, as shown in
The key-top 8 is arranged so that the pressing surface 8b protrudes from the upper surface of the housing 9 through the opening 12 in the housing 9.
The elastic member 100 is placed beneath the key-top 8. In the elastic member 100 according to the present embodiment, a conductive portion 7 is additionally formed on the lower surface 4a of the pusher 4. This conductive portion 7 can be formed by applying a conductive ink, for example, at the end of the pusher 4. A circuit substrate 10 is placed beneath the elastic member 100. A pair of electrical contacts 11a and 11b are provided as switch elements for opening and closing the electrical circuit provided on the circuit substrate 10. The conductive portion 7 of the elastic member 100 and the electrical contacts 11a and 11b on the circuit substrate 10 are placed in such a manner as to face each other.
In this structure for a pushbutton switch, when the key-top 8 is pressed down, the pressing portion 1 of the elastic member 100 is pressed in such a manner that the connection portion 2 elastically changes in form, and shortly thereafter the connection portion 2 buckles, as shown in
The elastic member 100 according to the present invention is formed of a material having rubber elasticity (rubber-like elastic body). This material may be a synthetic rubber, such as silicone rubber, urethane rubber and ethylene propylene rubber, in addition to styrene based, olefin based, polyester based and urethane based thermoplastic elastomers. From among the materials, silicone rubber is preferable, because it has little permanent distortion when compressed and is excellent in terms of durability. In order to gain rubber elasticity, it is preferable for the hardness of the material for forming the elastic member 100 to be 30 to 70 (values measured using type A durometer in compliance with JIS-K6253 (corresponding to ISO 7619-1)). Furthermore, in the case where the pushbutton switch is illuminated by providing a light source beneath the elastic member 100, it is preferable for the elastic member 100 to have translucency.
It is preferable for the inner diameter D1 in the hollow portion 5 of the pusher 4 shown in
In the elastic member 100 according to the first embodiment, the pusher 4 has a hollow portion 5, and therefore, the pusher 4 easily bends when pressed in comparison with the case where the pusher is solid. Therefore, increase in the resilient load becomes small after the pusher 4 makes contact with the electrical contacts 11a and 11b. As a result, a softer tactile sensation is provided to the operator.
In the elastic member 100, the ratio of the inner diameter D1 of the hollow portion 5 to the outer diameter D2 of the pusher 4 can be changed, and thus, the rate of load increase (inclination of solid line C in
In the elastic member 100, in the case where the inner diameter D1 in the hollow portion 5 of the pusher 4 is in a range from 40% to 90% of the outer diameter D2 of the pusher 4, the desired load characteristics are gained after the pusher 4 makes contact with the electrical contacts 11a and 11b as described above, and at the same time, the durability is ensured secured for the pusher 4.
In order to gain a soft tactile sensation, the elastic member 100 does not have an annular protrusion on the upper surface of the pressing portion 1, unlike conventional elastic members. Therefore, in the case where the structure for a pushbutton switch is formed in a state where the elastic member 100 is compressed in advance, it is not necessary to take deformation of the annular protrusion due to advance compression into consideration, and therefore, it becomes easy to adjust the peak stroke. In addition, the rate of load increase after the pusher 4 makes contact with the electrical contacts 11a and 11b can be adjusted in the elastic member 100, as described above, by changing the ratio of the inner diameter D1 in the hollow portion 5 to the outer diameter D2 of the pusher 4 while barely affecting the peak stroke S1.
In the case where an opening 6 which continues from the hollow portion 5 of the pusher 4 is created in the pressing portion 1 in the elastic member 100, the air inside the hollow portion 5 easily escapes to the outside when the pusher 4 is compressed through pressing. In addition, it becomes easy to create a hollow structure for the pusher 4 in a manufacturing process.
The elastic member 200 is provided with a pair of prism shaped base portions 3 which are placed at a distance from each other, thin plate shaped connection portions 2 which respectively extend diagonally upward from the upper end of these two base portions 3 which face each other, and a pressing portion 1 shaped like a rectangular plate which is supported above the base portions 3 by the connection portions 2. The pressing portion 1 is provided with a substantially prism shaped pusher 4 which protrudes downward from the lower surface of the pressing portion 1. The lower surface 4a of the pusher 4 is located above the lower surface 3a of the base portions 3. A hollow portion 5 having openings on the two sides of the pusher 4 is created in the pusher 4.
The elastic member 300 has the same structure as the elastic member 200, except that an opening 6 which continues from the hollow portion 5 of the pusher 4 is created on the upper surface 1a of the pressing portion 1. The hollow portion 5 of the pusher 4 and the opening 6 of the pressing portion 1 have a constant lateral cross-sectional form. As shown in
In the case where the elastic member 200 or 300 is incorporated in the structure for a pushbutton switch for use, the connection portions 2 elastically change in form and buckle when the pressing portion 1 of the elastic member 200 or 300 is pressed, so that the lower surface 4a of the pusher 4 makes contact with the switch elements (not shown) on the circuit substrate provided beneath the elastic member 200 or 300, and thus, the electric circuit on the circuit substrate is opened or closed, in the same manner as the elastic member 100 in
In the elastic members 200 and 300 according to the second and third embodiments, the inclination of solid line C in
It is preferable for the width W1 in the hollow portion 5 of the pusher 4 to be 40% to 90% of the width W2 of the pusher 4. In the case where the width W1 in the hollow portion 5 of the pusher 4 is less than 40% of the width W2 of the pusher 4, it becomes difficult for the pusher 4 to deform, while in the case where the ratio exceeds 90%, the pusher 4 becomes too flexible, and in either case, the desired load characteristics cannot be gained. In addition, in the case where the width W1 in the hollow portion 5 of the pusher 4 exceeds 90% of the width W2 of the pusher 4, the pusher 4 becomes less durable, which is not preferable.
The elastic members 200 and 300 according to the second and third embodiments can be formed of the same material as the elastic member 100 according to the first embodiment. In addition, it is preferable for the hardness of the material for forming the elastic members 200 and 300 to be 30 to 70 (values measured using type A durometer in compliance with JIS-K 6253 (corresponding to ISO 7619-1)), as in the case of the first embodiment. Furthermore, in the case where the pushbutton switch is illuminated by providing a light source beneath the elastic member 200 or 300, it is preferable for the elastic member 200 or 300 to have translucency.
The elastic members 200 and 300 according to the second and third embodiments may be incorporated in the structure for a pushbutton switch in the same manner as the elastic member 100 according to the first embodiment, and at the same time, provide the same advantages.
Furthermore, the connection portions 2 and the base portions 3 are formed only on the sides of the pressing portion 1, and therefore, the area where the elastic members 200 and 300 according to the second and third embodiment are installed can be reduced, and at the same time, it becomes possible to place these members in closer proximity to other parts.
It is also possible to modify the above described embodiments as follows.
In the first embodiment, the opening 6, which continues from the hollow portion 5 of the pusher 4, does not need to be created in the pressing portion 1. In this case, it is preferable to provide an air escape for air inside the hollow portion 5 to escape when the pusher 4 is compressed through pressing in at least either the pressing portion 1 or the pusher 4.
In the first embodiment, the form of the base portion 3 is not particularly limited, and may be any form.
In the second embodiment, the hollow portion 5 of the pusher 4 does not need to have an opening on the sides of the pusher 4.
In the second and third embodiments, a conductive portion may be provided on the lower surface 4a of the pusher 4.
In the case where the elastic member 100, 200 or 300 according to any of the first to third embodiments is incorporated in the structure for a pushbutton switch, the elastic member 100, 200 or 300 may be sandwiched between the housing 9, the key-top 8 and the circuit substrate 10 in such a state as to be compressed in advance in the direction in which the key-top 8 is pressed down. In this configuration, the peak stroke can be adjusted to a desired level.
In the structure for a pushbutton switch in which the elastic member 100, 200 or 300 according to any of the first to third embodiments is incorporated, pressure sensitive switch elements may be used as switch elements placed on the circuit substrate 10. In this case, it becomes unnecessary to form a conductive portion 7 on the lower surface 4a of the pusher 4 of the elastic member 100, 200 or 300.
The elastic member 100 shown in
The elastic members of Examples 2 to 4 were respectively fabricated using the same material as in Example 1, without changing the outer diameter D2 of the pusher 4 and the outer diameter D3 of the pressing portion 1, but changing the inner diameter D1 in the hollow portion 5 of the pusher 4, in the form of the elastic member 100 of Example 1. In the elastic members of Examples 2 to 4, the ratio was set as shown in Table 1 for each of the inner diameter D1 in the hollow portion 5 of the pusher 4 to the outer diameter D2 of the pusher 4 and the outer diameter D3 of the pressing portion 1.
A conventional elastic member as that shown in
A conventional elastic member as that shown in
A conventional elastic member as that shown in
The elastic members of Comparative Examples 4 and 5 were respectively fabricated using the same material as in Example 1, without changing the outer diameter D2 of the pusher 4 and the outer diameter D3 of the pressing portion 1, but changing the inner diameter D1 in the hollow portion 5 of the pusher 4, in the form of the elastic member 100 of Example 1. In the elastic members of Comparative Examples 4 and 5, the ratio was set as shown in Table 1 for each of the inner diameter D1 in the hollow portion 5 of the pusher 4 to the outer diameter D2 of the pusher 4 and the outer diameter D3 of the pressing portion 1.
The respective elastic members of Examples 1 to 4 and Comparative Examples 1 to 5 were used to fabricate structures for a pushbutton switch as that shown in
Rate of load increase=(load when stroke 1.5 mm−load when stroke 1.0 mm)/0.5 mm
In the elastic members of Examples 1 to 4, the pusher 4 had a hollow structure, and therefore, the rate of load increase became small after the lower surface of the pusher 4 made contact with the contacts on the circuit substrate, so that a soft tactile sensation was gained. In addition, in the elastic member of Example 1, even when compressed in advance, the peak stroke S1 barely changed in comparison with the elastic member having a solid pressing portion of Comparative Example 1. This is considered to be because the inner diameter D1 in the hollow portion 5 of the pusher 4 was set sufficiently small relative to the outer diameter D3 of the pressing portion 1 in the elastic members of Examples 1 to 4, and therefore, the upper surface of the pressing portion 1 barely deformed, even when compressed in advance. As a result, in Examples 1 to 4, the ratio of the inner diameter D1 in the hollow portion 5 to the outer diameter D2 of the pusher 4 was changed within a predetermined range (from 40% to 80%), and thus, the rate of load increase could be adjusted within a range of 2.82 N/mm to 8.48 N/mm while barely changing the peak stroke S1.
In contrast, the rate of load increase was great in the elastic member of Comparative Example 1 after the lower surface of the pusher 4 made contact with the contacts on the circuit substrate, and therefore, the desired tactile sensation was not gained. In addition, it was possible to reduce the increase in the load after contact was made in the elastic members of Comparative Examples 2 and 3. In the elastic members of Comparative Examples 2 and 3, however, the ratio of the inner diameter D4 of the annular protrusion 13 to the outer diameter D3 of the pressing portion 1 was considerably great in comparison with the ratio of the inner diameter D1 in the hollow portion 5 of the pusher 4 to the outer diameter D3 of the pressing portion 1 in Example 1, as shown in Table 1. Therefore, in the elastic members of Comparative Examples 2 and 3, the annular protrusion 13 was deformed through advance compression, and therefore, the peak stroke changed greatly. Accordingly, it was difficult to adjust the load curve for the elastic members of Comparative Examples 2 and 3, where the annular protrusion 13 was provided. In the elastic member of Comparative Example 4, the rate of load increase became great after the lower surface of the pusher 4 made contact with the contacts on the circuit substrate, and the desired tactile sensation was not gained. This is considered to be because the inner diameter D1 in the hollow portion 5 of the pusher 4 was small relative to the outer diameter D2 of the pusher and the ratio thereof was 32% in the elastic member of Comparative Example 4, and therefore, the outer peripheral wall 4b of the pusher was thick, making it difficult for the outer peripheral wall 4b of the pusher 4 to bend when pressed. In the elastic member of Comparative Example 5, the inner diameter D1 in the hollow portion 5 of the pusher 4 was too great relative to the outer diameter D2 of the pusher 4 and the ratio thereof was 92%, and therefore, the outer peripheral wall 4b of the pusher 4 was thin, making the pusher 4 excessively flexible. Therefore, in the elastic member of Comparative Example 5, the rate of load increase became extremely small after the lower surface of the pusher 4 made contact with the contacts on the circuit substrate, and thus, the desired tactile sensation was not gained. In addition, it is also possible in the elastic member of Comparative Example 5 that a problem may arise with the durability, because the outer peripheral wall 4b of the pusher 4 is excessively thin.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-310101 | Oct 2005 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2006/321005 | 10/23/2006 | WO | 00 | 4/18/2008 |
