Source: https://patents.justia.com/patent/10410806
Timestamp: 2019-10-15 11:38:05
Document Index: 486553109

Matched Legal Cases: ['Application No. 201410767031', 'Application No. 2014', 'Application No. 201710424845', 'Application No. 107103377', 'Application No. 201710424845', 'Application No. 201810202347']

US Patent for Reaction force generating member for a key switch device Patent (Patent # 10,410,806 issued September 10, 2019) - Justia Patents Search
Justia Patents US Patent for Reaction force generating member for a key switch device Patent (Patent # 10,410,806)
Jun 1, 2017 - FUJITSU COMPONENT LIMITED
Hereinafter, a description will be given of a relationship between a stroke S of the key top 10 (i.e., an amount of depression) and a load (i.e., a depression force) F. FIG. 5A is a diagram illustrating a load displacement characteristic of the key switch device 100 according to the present embodiment. FIG. 5B is a diagram illustrating a load displacement characteristic of the key switch device according to a comparative example. Here, in FIGS. 5A and 5B, the stroke S is set to a horizontal axis, the load F is set to a vertical axis, and a point “a” of contact-ON is illustrated additionally.
In FIG. 5A, a dotted line indicates the load displacement characteristic of the dome rubber 15, and an alternate long and short dash line indicates the load displacement characteristic of the contact depression member 16 (specifically, the coil spring 16b), and a solid line indicates a characteristic acquired by combining the load displacement characteristics of the dome rubber 15 and the contact depression member 16. When the load F of the key top 10 increases from 0, the stroke S also increases from 0 with the increase in the load F, as illustrated in FIG. 5A. At this time, the dome rubber 15 performs the elastic deformation, and the reaction force from the dome rubber 15 acts on the key top 10. The load displacement characteristic of the key switch device 100 when the load F is from 0 to F0 is equal to the load displacement characteristic of the dome rubber 15 itself. The load F rises until the load which acts on the dome rubber 15 reaches a buckling load (i.e., the load F0) of the dome rubber 15. When the load which acts on the dome rubber 15 reaches the buckling load, subsequently the load F decreases gently with the increase in the stroke S. A peak load F0 is obtained by the elastic buckling deformation of the dome rubber 15, and hence the operator can get a particular click feeling in a key touch operation.
In this case, a stroke S3 corresponds to an initial length L3 between a lower end of the contact depression member 16 (i.e., a lower end of the coil spring 16b) and the membrane sheet 14 (see FIG. 3). This length L can be set by adjusting the length of the coil spring 16b. The stroke S3 can be changed by adjusting the length L, and hence the stroke S1 of the key top 10 at the time of contact-ON can be changed. That is, by adjusting the length L, the stroke S1 of the key top 10 at the time of contact-ON can be set arbitrarily.
In the present embodiment, the stroke S1 is set to a value that is larger than a stroke S0 in which the peak load F0 is generated, and that is smaller than an end stroke S2 (for example, a middle value between the strokes S0 and S2). Thereby, since the contact 14d is turned on in a reduction domain of the load F after the operator gets the click feeling, an operator's operation feeling corresponds to the ON-operation of the contact 14d well, and hence the operability of the key switch improves.
FIG. 5B illustrates the load displacement characteristic of the key switch device when a projection is provided downward from the cylinder unit 15c of the dome rubber 15. Here, the dome rubber 15 in which the cylinder unit 15c is closed is used, and a projection 151 is provided downward from the cylinder unit 15c, as illustrated in FIG. 6. FIG. 6 is a cross-section diagram of the key switch device according to the comparative example. In this case, when the load F of the key top 10 increases from 0 as illustrated in FIG. 5B, the stroke S also increases from 0 with the increment in the load F. When the load which acts on the dome rubber 15 reaches the buckling load, the load F becomes a maximum value F0. Then, the load decreases. When the projection 151 contacts the membrane sheet 14 at the stroke S3, the load F rises again.
At this time, when a given depression force is added to the contact 14d after the projection 151 contacts the membrane sheet 14, the contact 14d of the membrane sheet 14 is turned on. Therefore, the stroke S1 at the time of contact-ON is larger than the stroke S3 in which the load F becomes a minimum value F3. Accordingly, in order to turn on the contact 14d, the operator needs to do key operation until the peak load F0 is exceeded and the load decreases and again increases. However, the operator usually judges that the contact is turned on in the reduction domain of the load F after the peak load F0 is exceeded. Therefore, if the operator needs to do the key operation in the increase domain of the load F, deviation occurs between the operation feeling and the contact depression operation, and hence the operator has a sense of discomfort. With respect to this, in the present embodiment, the contact 14d can be turned on in the reduction domain of the load F, so that the operation feeling and the contact depression operation can be made to correspond well, and the sense of discomfort does not occur.
As described above, the key switch device 100 obtains the load displacement characteristic as indicated by the dotted line of FIG. 10 (an interval between the strokes 0 and S4) and the alternate long and short dash line of FIG. 10 (an interval after the stroke S4), i.e., as indicated by the solid line of FIG. 5A, by combining the load displacement characteristics of two members (i.e., the dome rubber 15, and the coil spring 16b or contact depression rubber 21).
By the way, when the peak load F0 is exceeded, the load displacement characteristic of the dome rubber 15 decreases rapidly as illustrated by the dotted line of FIG. 10. Therefore, when the contact 14d can be turned on by the increase in load smaller than the reduction of the load displacement characteristic of the dome rubber 15 (see the alternate long and short dash line of FIG. 10), the key switch device 100 obtains the load displacement characteristic as illustrated by the solid line of FIG. 5A. In this case, since the contact 14d is turned on in the reduction domain of the load F after the operator gets the click feeling, the operator's operation feeling corresponds to the ON-operation of the contact 14d well, and hence the operability of the key switch improves.
By the way, at the time of depression of the key top 10 of FIG. 11, each projection 12e fixed to the key top 10 serves as a force point, and a half of all load is applied to one of the gear links. As illustrated in FIG. 11, a distance between the shaft 12c (i.e., a fulcrum) of the gear link 12a and the projection 12e (i.e., a force point) of the gear link 12a is indicated by “A”, the front edge (i.e., an acting point) of the contact depression member 12i for turning on the contact 14d is arranged at a position separated by a distance B (B<A) from the fulcrum, and a depression load applied to the force point is indicated by “Pa”. In this case, a load Pb which occurs in the acting point is expressed by “Pb=Pa×A/B”, and becomes larger than the depression load applied to the force point.
Generally, in order to turn on the contact 14d, the load from a little gf (gram-force) to about 10 gf is needed. On the other hand, the peak load of key depression is generally set to about 50 gf. When a peak position is exceeded, the load required for key depression decreases. At the time of the peak load, the load of about 25 gf per gear link is applied to the force point of the gear link. The depression load Pa required in order to acquire at the acting point the load of 10 gf for turning on the contact 14d is calculated by “10 gf=Pa×A/B”. For example, in the case of A/B=4, the depression load Pa is 2.5 gf. At this time, in the load displacement characteristic of the dome rubber 15 as illustrated in FIG. 10, when an amount of load descent from the peak load F0 to the load F1 corresponding to the contact-ON position “a” is set as 2.5 or more gf, the combined load displacement characteristic (see the alternate long and short dash line of FIG. 10) does not rise after the depression load reaches the peak load. Thereby, it is possible to acquire an ideal load displacement characteristic.
As illustrated in FIG. 13, a distance between the shaft 12c (i.e., a force point) of the gear link 12a and the projection 12e (i.e., a fulcrum) of the gear link 12a is indicated by “A”, the front edge (i.e., an acting point) of the contact depression member 12i for turning on the contact 14d is arranged at a position separated by a distance B (B<A) from the fulcrum, and a depression load applied to the force point is indicated by “Pa”. In this case, as with FIG. 11, a load Pb which occurs in the acting point is expressed by “Pb=Pa×A/B”, and becomes larger than the depression load applied to the force point.
The dome rubber 15 of FIG. 14 is a dome-shaped member composed of a rubber material by integral molding. The dome rubber 15 includes a ring-shaped base unit 15a, an outer dome unit 15g that extends diagonally upward from the base unit 15a, the cylinder unit 15c that extends upward from the outer dome unit 15q, and an inner dome unit 15h that extends in a reverse conical shape from the cylinder unit 15c. The outer dome unit 15g functions as the reaction force generating member, and the inner dome unit 15h functions as the contact depression member. The outer dome unit 15g inclines from a vertical direction by an angle α (α>45 degrees). A half apex angle θ of the inner dome unit 15h is 45 degrees or more. This is because the inner dome unit 15h does not perform buckling and the load displacement characteristic indicating that the load increases according to the increase in the stroke, such as the linear load displacement characteristic illustrated by the alternate long and short dash line of FIG. 5A, is acquired. When the inner dome unit 15h is a projection, for example, the projection performs the buckling by depression of the key top 10 and a desirable load displacement characteristic may not be acquired.
1. A reaction force generating member, comprising:
a first unit that has a first load displacement characteristic in which a depression load of an operation member increases until the first unit elastically buckles and deforms, and the depression load of the operation member decreases after the first unit is elastically buckled and deformed, according to depression of the operation member;
a second unit that is moved by the deformation of the first unit between a first position contacting the first unit and a second position contacting the first unit and depressing a switch disposed below the operation member, and has a second load displacement characteristic in which the depression load of the operation member increases at least until the switch is turned on according to an amount of depression of the operation member,
wherein a load is not applied to the second unit until the amount of the depression of the operation member reaches a given amount, and a load of the second unit increases after the amount of the depression of the operation member has reached the given amount, and the given amount is larger than the amount of the depression of the operation member at which the first unit is elastically buckled and deformed.
4. The reaction force generating member as claimed in claim 1,
wherein the first unit inclines from a vertical direction by an angle less than 45 degrees, and the second unit has a half apex angle of 45 degrees or more.
5. The reaction force generating member as claimed in claim 1, wherein the first unit comprises:
an outer dome unit that inclines diagonally upward from the base unit; and
a cylinder unit extending upwardly from the outer dome unit,
wherein the second unit extends in a reverse conical shape from the cylinder unit.
8. A reaction force generating member, comprising:
a first unit that has a first load displacement characteristic in which a depression load of an operation member increases until the first unit elastically buckles and deforms, and the depression load of the operation member decreases after the first unit is elastically buckled and deformed, according to depression of the operation member; and
a second unit that depresses a switch disposed below the operation member, and has a second load displacement characteristic in which the depression load of the operation member increases at least until the switch is turned on according to an amount of depression of the operation member,
wherein the first unit is formed integrally with the second unit, and
11. The reaction force generating member as claimed in claim 8, further comprising:
a cylinder unit that extends upwardly from the first unit,
wherein the first unit extends diagonally upward from the base unit, and
the second unit extends in a reverse conical shape from the cylinder unit.
13. A switch actuator, comprising:
a dome-shaped member composed of a rubber material as one piece,
wherein the dome-shaped member includes
a ring-shaped base,
an outer dome that inclines diagonally upward from the base,
a cylinder that extends upwardly from the outer dome, and
an inner dome that extends in a reverse conical shape from the cylinder, and
wherein the outer dome functions as a reaction force generating member that moves the inner dome when the outer dome is depressed, and the inner dome functions as a depression member for the switch.
15. The switch actuator as claimed in claim 13, wherein the inner dome has a half apex angle θ of 45 degrees or more.
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Patent number: 10410806
Patent Publication Number: 20170271103
Inventors: Takeshi Nishino (Tokyo), Shuji Nakamura (Tokyo), Akihiko Takemae (Tokyo), Tamotsu Koike (Tokyo)
Primary Examiner: Anthony R Jimenez
Application Number: 15/610,771
Current U.S. Class: 84/423.0R
International Classification: H01H 9/26 (20060101); H01H 13/72 (20060101); H01H 13/76 (20060101); H01H 13/7073 (20060101); H01H 13/14 (20060101);