Push type switch

A push type switch which enables an operator to obtain an upscale impression when he operates the push type switch. A switch body 3 is rigidly fixed to a printed wiring board 5. A casing 7 having a plurality of guide grooves 71h is fixed to the printed wiring board 5. A plurality of rails 91a provided on a knob 9 capable of transmitting a pushing force to the switch body 3 are slidably inserted into the guide grooves 71h such that the knob 9 can slide on the casing 7. A grease is applied to the guide grooves 71h and the rails 91a. The viscosity of the grease is set to be within a range of 1000 to 2750 Pa.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a push type switch, and more particularly to a push type switch which is capable of creating an upscale impression when operating (pushing) the push type switch.

2. Description of the Related Art

Conventionally, a key switch is known which is comprised of a membrane substrate, a pair of fixed contact points, a click rubber, a frame, and a key top (see e.g. Japanese Laid-Open Patent Publication (Kokai) No. 2004-71306 (Paragraph numbers [0011] to [0014], FIG. 1))

The membrane substrate is disposed on a chassis e.g. of electronic equipment.

The pair of fixed contact points are provided on the membrane substrate.

The click rubber has a generally domed shape, and covers the pair of fixed contact points. The click rubber has a conductive rubber provided on an inner surface thereof. The conductive rubber is opposed to the pair of fixed contact points in a manner spaced therefrom.

The frame is opposed to the membrane substrate and the click rubber in a manner slightly spaced therefrom. The frame includes a slide guide that has a hollow cylindrical shape.

The key top has a sliding portion. The sliding portion is in the form of an octagonal column and inserted into the slide guide, such that it slides in the direction of the thickness of the chassis.

The slide guide and the sliding portion are coated with a grease for smooth sliding and reduction of generation of noise.

When the key top is pushed with a finger, the sliding portion is caused to slide to press the click rubber. When the click rubber is pressed to a certain extent, it is inverted in shape, i.e. changed from a convex state into a concave state, whereby the conductive rubber is brought into contact with the pair of fixed contact points. As a result, the pair of fixed contact points are closed. Further, when the click rubber is inverted in shape, a click feeling is created.

When the finger is released from the key top, the key top returns to its original position by the resilience thereof, and the conductive rubber moves away from the pair of fixed contact points.

An upscale impression is demanded of a push type switch disposed on an instrumental panel for an automotive vehicle.

To impart the upscale impression to the above key switch, it is envisaged to use an expensive material for the key top, or decorates the key top with a special color or pattern.

However, there was a limit to creating the upscale impression, unless an operation feeling in operating the key switch is enhanced.

SUMMARY OF THE INVENTION

The present invention has been made in view of these circumstances, and an object thereof is to provide a push type switch which is capable of causing an operator to sense an upscale impression when he operates the push type switch.

To attain the above object, the present invention provides a push type switch comprising a switch body, a fixing member to which the switch body is rigidly fixed, a movable member slidably supported by the fixing member such that the movable member can transmit a pushing force to the switch body, and a grease applied to sliding portions of the fixing member and the movable member, wherein a viscosity of the grease is within a range of 1000 to 2750 Pa.

According to this push type switch, the viscosity of the grease is within a range of 1000 to 2750 Pa, so that when an operator pushes the movable member with his finger, he feels that an appropriate weight (a force his fingertip receives from the grease) is transmitted to his fingertip, and recognizes that the movable member is moved more slowly than in the prior art. Further, the operator can feel that rattling of the movable member and generation of noise are more suppressed than in the prior art. As a result, the push type switch according to the present invention is capable of giving an upscale impression to the operator when he operates the push type switch.

Preferably, the grease is a fluorine-based grease.

According to this preferred embodiment, since the grease is a fluorine-based grease, no significant changes in the viscosity are caused by temperature. As a result, it is possible to prevent the operation feeling from being changed due to changes in temperature.

Preferably, a guide groove is formed in one of the fixing member and the movable member, and a rail for sliding relative to the guide groove is formed on the other of the fixing member and the movable member.

According to this preferred embodiment, a guide groove is formed in one of the fixing member and the movable member, and a rail for sliding relative to the guide groove is formed on the other of the fixing member and the movable member. Therefore, the movable member can slide more stably. Further, according to the present invention, it is possible to further enhance the upscale impression during operation of the push type switch.

More preferably, a first grease reservoir is formed in at least one of the guide groove and the rail.

According to this preferred embodiment, since a first grease reservoir is formed in at least one of the guide groove and the rail, loss of the grease is caused only in a small amount even after the push type switch is used for a long time period. This makes it possible to maintain an excellent operation feeling for a long time period.

More preferably, a second grease reservoir is formed in one end of either the guide groove or the rail.

According to this preferred embodiment, since a second grease reservoir is formed in one end of either the guide groove or the rail, loss of the grease is caused only in a small amount even after the push type switch is used for a long time period. This makes it possible to maintain an excellent operation feeling for a long time period.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1is an exploded perspective view of a push type switch according to a first embodiment of the present invention;FIG. 2is a perspective view of a knob of theFIG. 1push type switch, as viewed obliquely from below;FIG. 3Ais a front view of theFIG. 1push type switch;FIG. 3Bis a plan view of theFIG. 1push type switch;FIG. 3Cis a bottom view of theFIG. 1push type switch;FIG. 3Dis a right side view of theFIG. 1push type switch;FIG. 4is a cross-sectional view taken on line IV-IV ofFIG. 3A;FIG. 5is a cross-sectional view taken on line V-V ofFIG. 3D; andFIG. 6is an enlarged view of part A appearing inFIG. 5.

As shown inFIGS. 1 to 6, the push type switch is comprised of a switch body3, a printed wiring board5, a casing7, and a knob (movable member)9.

The switch body3is disposed at a corner of the printed wiring board5. The switch body3includes a click board31, a pair of fixed contact points (not shown), and a movable contact point (not shown). The click board31is made of an elastic material having insulating properties such that it has a generally domed shape. The click board31has a protrusion31aformed on the top thereof. The pair of fixed contact points are arranged on the printed wiring board5, and covered by the click board31. The movable contact point is disposed on an inner surface of the click board31in a manner opposed to the pair of fixed contact points.

The printed wiring board5is formed with a conductor pattern (not shown). Part of the conductor pattern is connected to the pair of fixed contact points.

The casing7is formed of resin as a unitary member, and includes a hollow section71, a frame72, and an accommodating section73.

The hollow section71has a generally hollow prismatic shape, and includes three pillar-like portions71a, and a plurality of plate-like portions71dformed between the three pillar-like portions71a. The pillar-like portions71aextend along the direction of the height H1(seeFIG. 1) of the hollow section71. The pillar-like portions71aare larger in height than the plate-like portions71d, and hence the upper ends of the pillar-like portions71aprotrude from the upper end faces of the plate-like portions71d, and the protruding portions serve as grease supply protrusions71e(seeFIGS. 1 and 4). The pillar-like portions71aeach have an outer side surface formed with a guide groove71hthat extends along the direction of the height H1of the hollow section71. The grease supply protrusions71eare formed with grease supply reservoirs (second grease reservoirs)71k. The grease supply reservoirs71kcommunicate with the guide grooves71h, respectively, and extend in a manner widened toward the ends thereof.

The two plate-like portions71dopposed to each other are formed with protrusions71p, respectively. The protrusions71pare generally wedge-shaped.

The frame72surrounds one end of the hollow section71, and includes three grease supply reservoirs (second grease reservoirs)72a. The grease supply reservoirs72acommunicate with the guide grooves71h.

The accommodating section73is formed at a corner of the frame72in a manner such that a half thereof extends into the hollow section71(seeFIG. 5). The top of the accommodating section73is formed with a hole73a. The accommodating section73accommodates the switch body3.

The above described printed wiring board5and the casing7constitute a fixing member having the switch body3fixed thereto.

The knob9is approximately box-shaped and formed of resin. The knob9has a skirt91, a pushed portion92, and a pushing portion93.

The skirt91has a generally hollow prismatic shape, and includes three rails91a, and a plurality of plate-like portions91dformed between the three rails91a. The rails91aextend along the direction of the height H2(seeFIG. 1) of the knob9. The rails91aare larger in height than the plate-like portions91d, so that the foremost ends of the rails91aprotrude from the end faces of the plate-like portions91d, and the protruding portions serve as grease supply protrusions91e(seeFIG. 1). The rails91aare formed with respective grease-holding grooves (first grease reservoirs)91h. The grease-holding grooves91hextend along the direction of the length of the rails91a.

The rails91aare slidably inserted into the associated guide grooves71h. As described above, in the first embodiment, the guide groove71hand the rails91aconstitute respective sliding portions.

The grease supply protrusions91eenter the grease supply reservoirs72a, when the knob9is closest to the frame72.

Opposed two of the plate-like portions91dare formed with holes91p, respectively. The holes91pare rectangular in shape and have the associated protrusions71preceived therein. In this state, the protrusions91pcan be relatively moved within a predetermined range. This range determines the stroke of the knob9, which is thus prevented from falling off the casing7.

The pushed portion92is for being pushed with a finger. The pushed portion92has a plate-like shape, and is connected to one end of the skirt91. The pushed portion92has three grease supply reservoirs (second grease reservoirs)92a. The three grease supply reservoirs92aare formed in a manner surrounding the rails91a, and communicate with the grease-holding grooves91h. The grease supply reservoirs92areceive the grease supply protrusions71e, when the knob9is closest to the frame72.

The pushing portion93is disposed at a corner of the pushed portion92, and connected to the skirt91. The foremost end of the pushing portion93is inserted into the accommodating section73via the hole73a. The pushing portion93pushes the protrusion31aof the click board31.

Grease11is applied to the guide grooves71hand the rails91a(seeFIG. 6). As the grease11, there is used a fluorine-based grease the viscosity of which is within a range of 1000 to 2750 Pa.

It should be noted that the viscosity of the grease11is expressed in terms of torque. The torque is defined here as a shearing force (in units of Pa) obtained when 0.2 cc of the grease is placed on a plate of a rotation viscometer, and the plate is rotated at a rotational speed of 10 rpm.

FIG. 7is a cross-sectional view taken on the same line as inFIG. 4, in a state where the knob is not pushed, andFIG. 8is a cross-sectional view taken on the same line as inFIG. 4, in a state where the knob is pushed.

Next, a description will be given of the operation of the push type switch according to the present embodiment.

In a state where the operator is not pushing the knob9with his finger (the state shown inFIG. 7), the knob9is urged by the resilience of the click board31via the protrusion31a, whereby the knob9is at a position away from the printed wiring board5.

When the operator pushes the knob9with his finger against the resilience of the click board31, the pushing force is transmitted to the click board31via the pushing portion93and the protrusion31a, whereby the click board31is progressively crushed. When the pushing force applied to the click board31exceeds a predetermined value, the click board31is inverted in shape, i.e. changed from a convex state into a concave state, as shown inFIG. 8. At this time, a click feeling is obtained, and the movable contact point is brought into contact with the pair of fixed contact points, whereby the switch body3is turned on.

When the operator releases his finger from the knob9, the knob9is returned to its original position by the resilience of the click board31, and the movable contact point is moved away from the pair of fixed contact points, whereby the switch body3is turned off.

Next, a description will be given of the circulation of the grease11.

In the state where the operator is not pushing the knob9with his finger, the knob9is spaced away from the printed wiring board5by the click board31, as described above. In this state, the grease supply protrusions71eand91eare away from the grease supply reservoirs92aand72a, respectively.

When the knob9is pushed to be moved toward the printed wiring board5, the grease11hardly leaks from the guide grooves71hsince the grease11within the guide grooves71his held by the grease-holding grooves91h. When the switch body3is turned on, a small amount of the grease11is discharged from the guide grooves71h. However, the grease11discharged from the guide grooves71his stored in the grease supply reservoirs72aand92a, as shown inFIG. 8. Further, at this time, the grease supply protrusions71eand91eare inserted into the grease supply reservoirs92aand72a, respectively, and the grease11stored in the grease supply reservoirs72aand92ais attached to the grease supply protrusions71eand91e.

When the finger is released from the knob9to allow the knob9to be returned to its original position by the resilience of the click board31, the grease11attached to the grease supply protrusions71eand91ereturns to the guide grooves71h. This reduces the loss of the grease11to a very small amount.

Next, a description will be given of an operation feeling produced by operating the knob9.

During a time period from the start of pushing of the knob9by the operator to the switch-on of the switch body3, the rails91aslide within the guide grooves71h. At this time, since the grease11having a high viscosity exists between the rails91aand the guide grooves71h, the rails91aare moved slowly, and what is more, generation of noise, such as rattling or sliding noise of the knob9, is suppressed. Thus, the operator feels an appropriate resistance on his fingertip when pressing the knob9, and the knob9moves quietly and slowly without rattling. As a result, the operator can obtain an upscale impression of the push type switch. Further, also when the click board31is inverted in shape, the grease11having a high viscosity softens the click feeling, which enhances the upscale impression.

Next, a description will be given of the effects of the present embodiment.

According to the push type switch, the grease11having a viscosity within the range of 1000 to 2750 Pa is used. Therefore, when the operator pushes the knob9, an appropriate pressure acts on a finger of the operator, and the knob9moves quietly and slowly with little rattling. As a result, the operator can obtain an upscale impression of the push type switch.

Further, since the grease11is a fluorine-based grease, no significant change in the viscosity is caused by temperature, which makes it possible to prevent the operation feeling from being changed due to changes in temperature.

Furthermore, since the grease-holding grooves91h, the grease supply reservoirs72aand92a, and the grease supply protrusions71eand91eare employed, the loss of the grease11is small even after the push type switch is used for a long time period. This makes it possible to maintain the upscale impression of the push type switch for a long time period.

It should be noted that although in the present embodiment, the fluorine-based grease is used as the grease11, this is not limitative, but an olefin-based grease, for example, may be employed as the grease11.

Further, although in the present embodiment, the grease-holding grooves91hare formed in the rails91a, it is not necessarily required to form the grease-holding grooves91hin the rails91a.

It should be noted that although the grease supply protrusions71eand the grease supply reservoirs72aare formed in the casing7, and the grease supply protrusions91eand the grease supply reservoirs92aare formed in the knob9, it is not necessarily required to provide the grease supply protrusions71eand91e, or the grease supply reservoirs72aand92a.

Further, although in the present embodiment, the guide grooves71hare formed in the casing7, and the rails91aare provided in the knob9, this is not limitative, but the guide grooves may be formed in the knob9and the rails may be provided in the casing7.

It should be noted that the number of the guide grooves71hand that of the rails91aare not limited to three.

Next, a description will be given of a test performed for defining a range of viscosity of grease producing the upscale impression of the push type switch during operation thereof.

Table 1 indicates samples and viscosities of greases employed in the test.

FIG. 9is a graph showing the relationship between the average ranks of samples and the viscosities of greases;FIG. 10is a view showing a table of evaluation items and evaluation scores of the samples on a seven-point (−3 to 3-point) scale;FIG. 11is a graph showing the relationship between the average evaluation scores of the respective samples as to the feeling of softness obtained during operation of the knob and the viscosities of the greases;FIG. 12is a graph showing the relationship between the average evaluation scores of the respective samples as to rattling of the knob and the viscosities of the greases; andFIG. 13is a graph showing the relationship between the average evaluation scores of the respective samples as to generation of noise during the operation of the knob and the viscosities of the greases.

As shown in Table 1, a push type switch which has no grease applied to sliding portions (the guide grooves71hand the rails91a) is referred to as Sample A. Push type switches which have greases having different viscosities applied to sliding portions thereof are referred to as Sample B to Sample G, respectively. The viscosities of the greases used in the respective samples are shown in Table 1.

Then, a plurality of monitors were caused to operate Samples A to G, and the ranks or places of Samples A to G in the respective ranks orders as to the relative merits and demerits thereof concerning the operation feeling, rattling, and noise were determined on a sample-by-sample basis, and the averages of the ranks or places of each of Samples A to G in the rank orders were obtained. The results are shown inFIG. 9.

The monitors felt upscale impressions from samples of a third place or higher in the average rank order. The viscosities of the greases used in the samples of the third place or higher are within a range of 1000 Pa to 2750 Pa.

Then, Samples A to G were evaluated as to the feeling of softness (feeling of resistance), the rattling of the knob, and the generation of noise during the operation of the knob. To express results of evaluation in numerical points, as shown inFIG. 10, evaluations concerning each item were classified into seven levels in which positive evaluations are assigned scores of 3, 2, and 1 in decreasing order of the evaluations, whereas negative evaluations are assigned scores of −1, −2, and −3 in decreasing order of the evaluations. Further, when neither of the positive evaluations and the negative evaluations can be given, an evaluation score of 0 was imparted.

The monitors evaluated Samples A to G as to each item of evaluation. The relationship between the respective average evaluation scores of Samples A to G concerning the feeling of softness and the viscosities of the greases is shown inFIG. 11; the relationship between the respective average evaluation scores of Samples A to G concerning the rattling of the knob and the viscosities of the greases is shown inFIG. 12; and the relationship between the respective average evaluation scores of Samples A to G concerning noise and the viscosities of the greases is shown inFIG. 13.

As shown inFIG. 11, the average evaluation score concerning the feeling of softness is higher as the viscosity of the grease is higher. However, the feeling of softness and the upscale impression of the push type switch during operation thereof do not coincide with each other. When the viscosity is larger than 2500 Pa, the feeling of softness becomes excessive, and most of the monitors felt extreme reduction in the feeling of input operation (feeling of pushing in the push type switch).

Referring toFIG. 12andFIG. 13, however, the average evaluation scores concerning the rattling of the knob and the generation of noise are higher as the viscosity of the grease is higher, and hence the total evaluation makes it possible to obtain the upscale impression even after the viscosity of the grease exceeds 2500 Pa. Therefore, as shown inFIG. 9, the range of the viscosity of the grease where the upscale impression can be obtained was determined to be 1000 to 2750 Pa.

FIG. 14is a graph showing the relationship between the sliding speed and the sliding resistance of the knob exhibited when a low-viscosity grease is used or when a high-viscosity grease is used.

Referring toFIG. 14, in the case where the low-viscosity grease is used (Sample B), which is indicated by a dotted line, the sliding resistance F of the knob9does not become so large even when the sliding speed v of the knob9becomes higher. On the other hand, in the case where the high-viscosity grease is used (Sample D), which is indicated by a solid line, when the sliding speed v of the knob9becomes higher, the sliding resistance F of the knob9increases at a higher rate than the rate of increase in the sliding speed v.

Assuming that the coefficient of viscosity of a grease is represented by C, and the sliding speed of the knob by v, the sliding resistance F of the knob9can be obtained by the following equation:
F=Cv

As described above, if the high-viscosity grease is used, the sliding resistance F of the knob9increases at a higher rate than the rate of the increase in the sliding speed v, so that a sharp change in load on the knob9is alleviated. This action mainly leads to enhancement of the operation feeling produced when the click board31is inverted in shape.

Based on the results of the test described above, the range of the viscosity of the grease11was determined to be 1000 to 2750 Pa.

Since it is difficult to describe the difference between the operation feeling of Sample C and that of Sample D, the difference is represented by a graph shown inFIG. 15.

InFIG. 15, the horizontal axis represents the stroke of the knob, and the vertical axis represents the speed of the knob and the load on the knob.

For purposes of ease of comparison between the operation feeling of Sample C and that of Sample D, the pushing force applied to the knob9during a time period from the start of pushing the knob9to the inversion of the click board31(between strokes S0and S1) was set to be equal between Sample C and Sample D.

A curve VC represents the relationship between the stroke (S) and the speed (V) of a knob9of Sample C, a curve VD represents the relationship between the stroke (S) and the speed (V) of a knob9of Sample D, a curve FC represents the relationship between the stroke (S) and load (F) on the knob9of Sample C, and a curve FD represents the relationship between the stroke (S) and load (F) on the knob9of Sample D.

As shown inFIG. 15, between the strokes S0and S1, the knob9of Sample D moves a little more slowly than the knob9of Sample C.

During a time period from the inversion of the click board31to the stop of the knob9(between strokes S1and S2), both the speed (V) and the load (F) sharply change in Sample C, whereas in Sample D, both the speed (V) and the load (F) change more slowly than in Sample C. This means that in Sample C, the click feeling is sharpened, whereas in Sample D, the click feeling is softened.

As described above, the slower motion and the softer click feeling of the knob9give the upscale operation feeling thereto.

Next, a description will be given of variations of the first embodiment.

FIG. 16is a cross-sectional view showing a sliding portion of a first variation of the first embodiment.

As shown inFIG. 16, in the first variation, each grease supply protrusion91ehas a side surface formed with a plurality of grooves91q.

In the first variation, the grease11becomes easier to be attached to the grease supply protrusions91edue to the grooves91q. As a result, it is possible to enhance the circulation of the grease11.

FIG. 17is a cross-sectional view showing a sliding portion of a second variation of the first embodiment.

As shown inFIG. 17, in the second variation, a portion of each rail91aaccommodated in the associated grease supply reservoir92ais formed with inflated portions91r. The inflated portions91rare configured to have a shape to be fitted in the grease supply reservoir71k. When the grease supply protrusions71eare inserted into the grease supply reservoirs92a, the inflated portions91rreturn the grease11within the grease supply reservoirs71kto the guide grooves71h.

In the second variation, since the grease11within the grease supply reservoirs71kcan be returned to the guide grooves71hby the inflated portions91r, it is possible to enhance the circulation of the grease11, similarly to the first variation.

FIG. 18is an enlarged cross-sectional view showing part A of a third variation of the first embodiment.

As shown inFIG. 18, in the third variation, grease-holding grooves71rare formed in respective opposed inner surfaces of each guide groove71h. The grease-holding grooves71rextend in parallel with the guide groove71h.

In the third variation, since the grease-holding grooves71rare formed in addition to the grease-holding grooves91h, it is possible to further reduce the loss of the grease11.

FIG. 19is an enlarged cross-sectional view showing part A of a fourth variation of the first embodiment.

As shown inFIG. 19, in the fourth variation, grease-holding grooves71rare formed in respective opposed inner surfaces of each guide groove71h, and the grease-holding groove91his eliminated from the top surface of each rail91a(surface opposed to the bottom surface of each guide groove71h).

The fourth variation provides the same advantageous effects as provided by the first embodiment shown inFIG. 1.

FIG. 20is an enlarged cross-sectional view showing part A of a fifth variation of the first embodiment.

As shown inFIG. 20, in the fifth variation, grease-holding grooves91sare formed in respective opposite side surfaces of each rail91a, and the grease-holding groove91his eliminated from the rail91a.

The fifth variation provides the same advantageous effects as provided by the first embodiment shown inFIG. 1.

FIG. 21is an enlarged cross-sectional view showing part A of a sixth variation of the first embodiment.

As shown inFIG. 21, in the sixth variation, a key91tis formed instead of forming the grease-holding groove91hin the top surface of each rail91a(surface opposed to the bottom surface of each guide groove71h). The key91tcreates a gap G for holding the grease11between the top surface of the rail91aand the guide groove71h.

The sixth variation provides the same advantageous effects as provided by the first embodiment shown inFIG. 1.

FIG. 22is a cross-sectional view showing a sliding portion of a seventh variation of the first embodiment.

As shown inFIG. 22, in the seventh variation, a plurality of grease-holding grooves91uare formed in the opposite side surfaces of each rail91a, instead of forming the grease-holding groove91hin the top surface of the rail91a. The grease-holding grooves91uextend in a direction orthogonal to the direction of the length of the rail91a.

The seventh variation provides the same advantageous effects as provided by the first embodiment shown inFIG. 1.

FIG. 23is an exploded perspective view of a push type switch according to a second embodiment of the present invention;FIG. 24is a perspective view of theFIG. 23push type switch, in a state having part of a casing thereof cut off, and presented in an inverted position;FIG. 25is an enlarged view of part B appearing inFIG. 24; andFIG. 26is a cross-sectional view of theFIG. 23push type switch.

Component parts identical to those of the first embodiment are designated by identical reference numerals, and detailed description thereof is omitted, while only component parts different in configuration from the first embodiment will be described hereinafter.

As shown inFIGS. 23 to 26, the push type switch is comprised of a switch body3, a printed wiring board5, a casing207, a knob209, and a slider210.

As distinct from the first embodiment in which the movable member is formed by the knob9alone, in the second embodiment, a movable member is formed by the knob209and the slider210.

The casing207includes a hollow section271, a lid272, and pillar-like portions273. The casing207contains the slider210, and is rigidly fixed to the printed wiring board5. The hollow section271has a hollow prismatic shape. The lid272is connected to one end of the hollow section271. The lid272is formed with a hole272a, and an inner surface of the lid272is formed with three grease supply reservoirs (second grease reservoirs)272b(seeFIG. 25). The hollow section271has three pillar-like portions273arranged therein. The pillar-like portions273are connected to the hollow section271and the lid272. The pillar-like portions273are each formed with a guide groove273a. The guide grooves273acommunicates with the respective associated grease supply reservoirs272b. Part of one end of each pillar-like portion273is cut out to thereby form a grease supply protrusion273b.

The knob209includes a skirt291and a pushed portion292. The skirt291has a hollow prismatic shape, and is formed with two holes291p. The pushed portion292is in the form of a flat plate, and connected to one end of the skirt291. The periphery of the pushed portion292protrudes from a side surface of the skirt291.

The slider210includes a first hollow portion211and a second hollow portion212.

The first hollow portion211has a hollow prismatic shape, and rails211aare respectively formed at three portions of the sides of the first hollow portion211. One end of each rail211aprotrudes from one end face of the first hollow portion211, and the protruding portion serves as a grease supply protrusion211b(seeFIG. 26). The rails211aare slidably inserted into the respective associated guide grooves273aof the casing207. This enables the slider210to slide on the casing207. When the slider210is lifted by a click board31, the grease supply protrusions211bare inserted into the respective associated grease supply reservoirs272bof the lid272.

The first hollow portion211has one end thereof formed with three overhang portions211cadjacent to the rails211a. The overhang portions211care each formed with a grease supply reservoir211d. The grease supply reservoirs211dreceive one ends of the rails211a. Further, when the slider210is lifted by the click board31, the grease supply reservoirs211dreceive the grease supply protrusions273bof the pillar-like portions273, respectively.

The first hollow portion211has an inner side wall provided with a pushing piece211efor pushing the switch body3, and a reinforcing plate211fsupporting the pushing piece211e(seeFIG. 26).

The second hollow portion212has a hollow prismatic shape. It is next smaller in size than the first hollow portion211, and connected to the other end of the first hollow portion211. The second hollow portion212protrudes from the casing207via the hole272a. The second hollow portion212has side surfaces formed with two protrusions212a. The protrusions212aare inserted into the associated holes291pof the knob209. This fixes the knob209to the second hollow portion212

The second embodiment provides the same advantageous effects as provided by the first embodiment.

It is further understood by those skilled in the art that the foregoing are the preferred embodiments of the present invention, and that various changes and modification may be made thereto without departing from the spirit and scope thereof.