1. Field of the Invention
The present invention relates to a multidirectional switch which outputs a switching signal in accordance with the tilting direction of a stem, and, more particularly, to a multidirectional switch which outputs a switching signal even when a stem is pushed.
2. Description of the Related Art
A description of a conventional multidirectional switch will be given with reference to the relevant drawings.
FIG. 8 is a sectional view of a conventional multidirectional switch. FIG. 9 is a plan view of a housing of the conventional multidirectional switch. FIG. 10 is an exploded perspective view of movable contact springs and the housing of the conventional multidirectional switch. FIG. 11 illustrates the operation of the conventional multidirectional switch.
As shown in FIGS. 8 to 10, a housing 20 is molded out of a synthetic resin material, and comprises side walls 20a that surrounds four sides, an inside bottom portion 20b surrounded by the side walls 20a, four bosses 20c provided in a standing manner so as to extend outward from the four corners of the open end of the side walls 20a, four positioning portions 20d provided near the bosses 20c, and four inner protrusions 20e protruding from the inside bottom portion 20b. 
At the inside bottom portion 20b of the housing 20 are exposed a circular central fixed contact 2, a common contact 3 which surrounds the periphery of the central fixed contact 2, and peripheral fixed contacts 4 disposed at four locations, at the front, back, left and right sides along the periphery of the common contact 3. The central fixed contact 2, the common contact 3, and the peripheral fixed contacts 4 protrude outwardly as terminals 5 from opposing side walls 20a of the housing 20. Here, the four protrusions 20e at the inside bottom portion 20b are provided in a standing manner so as to surround the circular central fixed contact 2.
A central tactile spring 60 serving as a central movable contact spring is formed by using a highly resilient base material, such as phosphor bronze or SUS, and subjecting the base material to surface treatment using silver (Ag). The central tactile spring 60 is dome shaped and is placed on the common contact 3 such that it is surrounded by the protrusions 20e. 
Peripheral tactile springs 70 serving as peripheral movable contact springs are formed by using highly resilient base materials, such as phosphor bronze or SUS, and subjecting the base materials to surface treatment using silver (Ag). The peripheral tactile springs 70 are formed into rectangular shapes. A bulging portion 70a which is fixed on both sides is integrally formed at the center of its corresponding peripheral tactile spring 70. The peripheral tactile springs 70 are placed on the common contact 3, inwardly of each of the peripheral fixed contacts 4, and are positioned by the corresponding protrusions 20e and the inside walls of the housing 20.
In other words, the central tactile Spring 60, serving as a central movable contact spring, and each of the peripheral tactile springs 70, serving as a peripheral movable contact spring, are formed with different shapes, and are separately disposed inside the housing 20.
A first stem 8 is molded out of a synthetic resin material, and comprises a cylindrical portion 8a, a skirt 8b, and four semicircular protrusions 8c, which are integrally formed. The skirt 8b spreads obliquely downward from one end portion of the cylindrical portion 8a. Each semicircular protrusion 8c is formed at the bottom surface of the skirt 8b so as to be maintained at equal angular distances of approximately 90 degrees from each other. The protrusions 8c oppose the bulging portions 70a of their corresponding peripheral tactile springs 70.
A guide hole 9 is formed in the center portion of the cylindrical portion 8a so as to pass vertically therethrough.
Four protrusions 8d are integrally formed at the peripheral edge of the lower portion of the skirt 8b. These protrusions 8d extend outwardly from portions midway between corresponding two adjacent protrusions 20e, and engage the corresponding positioning portions 20d of the housing 20.
The first stem 8 is rockably supported with respect to the housing 20 by the peripheral tactile springs 70, which are placed on the inside bottom portion 20b of housing 20. The housing protrusions 20e have slots in a lower portion thereof (as best seen in FIG. 9) which hold the peripheral tactile springs 70 in place.
A second stem 10 is molded out of a synthetic resin material. A flange 10a is integrally formed at the bottom end of the second stem 10. The bottom surface of the flange 10a opposes the top surface of each of the protrusions 20e of the housing 20 so as to be maintained at a predetermined distance therefrom. The second stem 10 protrudes upward from the first stem 8 as a result of being inserted into the guide hole 9 from therebelow, and is stopped by the flange 10a so as not be dislodged from the first stem 8. A presser protrusion 10b is integrally formed at the center of the lower surface of the second stem 10. The bottom end of the presser protrusion 10b is in contact with the central tactile spring 60.
A cover 11 is formed of a metal plate by a pressing operation. A circular central hole 11a is formed in the center of the cover member 11, and mounting holes (not shown) are formed in the four corners thereof. A portion which widens in the downward direction is formed at the peripheral edge of the central hole 11a. With the skirt 8b of the first stem 8 being passed through the center hole 11a, the cover member 11 covers the open end of the top portion of the housing 20 by caulking the bosses 20c passed through their corresponding mounting holes (not shown).
In the multidirectional switch having the abovedescribed structure, the central tactile spring 60 and each of the peripheral tactile springs 70 are separately disposed inside the housing 20. The peripheral tactile springs 70 and the corresponding protrusions 8c are made to oppose each other with predetermined separations therebetween in order to provide a play therebetween. Therefore, in certain states of use of the switch, when, as shown in FIG. 11, the second stem 10 and the first stem 8 are rocked with respect to the housing 20 so that the entire multidirectional switch is tilted while in a switched state. In this configuration, one of the peripheral tactile springs 70b is compressed, while, the distance between the peripheral tactile spring 70c disposed opposite to the direction of operation of the first stem 8 and the corresponding protrusion 8c increases. Therefore, the peripheral tactile spring 70 may lift from the inside bottom portion 20b of the housing 20, causing the outside end of the peripheral tactile spring 70 to move upward along the corresponding side wall 20a of the housing 20. If the peripheral tactile spring 70 stays on the side wall 20a when the multidirectional switch is tilted back to its original position (as will sometimes occur), the switching of the peripheral tactile spring 70 may be hindered.
In the above-described multidirectional switch, in order to always cause each of the peripheral tactile springs and the central tactile spring to be in electrical conduction with the common contact, it is necessary to wire the common contact so as to surround the central tactile spring. This has prevented size reduction of the multidirectional switch in the widthwise direction.
In addition, a large number of tactile springs are used, and the assembly operations are troublesome to carry out, so that the multidirectional switches cannot be provided at low costs.
To achieve the foregoing and other objects of the invention a multidirectional switch is provided that includes a housing having disposed at an inside bottom portion thereof a central fixed contact, a common contact, and a plurality of peripheral fixed contacts. A plurality of metallic movable contact springs are positioned to oppose the central fixed contact and the peripheral fixed contacts, respectively. The movable contact springs are connected together and are also in electrical communication with the common contact.
An actuator assembly (e.g., an operating rod) is arranged permit any selected one of the movable contact springs to be brought into electrical communication with its opposing fixed contact.
In one form of the present invention, the movable contact springs are integrally formed from a metallic material. In some implementations they are dome-shaped.
In another form of the present invention, the housing is substantially rectangular in shape and the plurality of peripheral fixed contacts are disposed at the four corners of the housing in still another form of the present invention, the movable contact springs comprise a central movable contact spring disposed so as to oppose the central fixed contact, and peripheral movable contact springs disposed so as to oppose the corresponding peripheral fixed contacts. In this form of the multidirectional switch, a pair of the connecting portions that oppose each other extend from an outer peripheral edge of the central movable contact spring. In addition, connecting portions are provided, one branching and extending from each connecting portion, with the peripheral movable contact springs being connected at ends of the branched connecting portions.
In still another form of the present invention, the operating rod comprises a first stem which has a guide hole formed in the center thereof and which is rockably supported with respect to the housing, and a second stem which is slidably fitted to the guide hole and which protrudes from the first stem. In this form of the multidirectional switch, by tilting the first stem in a predetermined direction through the second stem, a desired one of the peripheral fixed contacts is brought into electrical conduction with the common contact through the corresponding movable contact spring and the connecting portion. In addition, by pushing the second stem, the central fixed contact is brought into electrical conduction with the common contact through the corresponding movable contact spring.