Multi-directional switch having a plurality of manual switches

Abstract: A plurality of fixed contacts and a movable contact are provided on a substrate so that opposite contacts form a unit switch. A holding plate having a spherical overhang holding wall is mounted on the substrate, and an operating plunger having a plurality of radially extending arms is slidably mounted in a hole formed in the holding plate, and rotatably held in the spherical overhang holding wall. A plurality of projections are formed on the underside of the plunger, each of the projections is provided corresponding to the movable contact.

Description: BACKGROUND OF THE INVENTION The present invention relates to a multi-directional switch comprising a plurality of manual switches and used in electronic devices such as a portable telephone, video camera, car radio and others. The multi-directional switch comprises a plurality of fixed contacts circularly arranged in a housing, and an operating plunger tiltably provided in the housing and having a plurality of branches, each having a movable contact which can be contacted with a corresponding fixed contact in the housing by manipulating the operating plunger, thereby producing a specific signal. Fig. 12 is a sectional side view of a multi-directional switch disclosed in the Japanese Patent Application Laid Open 10-188738. There is provided on the bottom of a housing 1 a central fixed contact 2, four peripheral fixed contacts 4, a central movable contact 6 corresponding to the central fixed contact 2, four peripheral movable contacts 7, each provided for a corresponding fixed contact 4, and a circular common fixed contact 3. The central movable contact 6 has a circular tray shape. The peripheral movable contact 7 has a central arcuated yieldable bridge 7a. A peripheral portion of the central movable contact 6 contacts with the common fixed contact 3 and the central portion of the contact 6 is not contacted with the central fixed contact 2. An inner portion of the peripheral movable contact 7 contacts with the common fixed contact 3, and the bridge 7a is not contacted with the peripheral fixed contact 4. A first stem 8 and a second stem 10 as an operating plunger are mounted on the movable contacts 6 and 7. The first stem 8 comprises a cylindrical portion 8a and a skirt portion 8b having a spherical peripheral wall. The skirt portion 8b has four projections 8c on the underside thereof, each contacts with a corresponding bridge 7a of the movable contact 7. The first stem 8 is tiltably held by wall of a hole of a cover 11 at the spherical wall thereof. The second stem 10 has a quadratic prism shape and is vertically slidably mounted in a guide hole 9 of the first stem 8, and prevented from removing from the hole 9 by a flange 10a. The switches are operated by manipulating the second stem 10. For example, when the second stem 10 is tilted to the left, the first stem 8 is also tilted to the left, so that the projection 8c pushes the bridge 7a to yield it, thereby contacting the bridge to the fixed contact 4. Thus, the contact 4 is electrically connected to the common contact 3 by the bridge 7a. Other switches are similarly operated. When the second stem 10 is depressed, a projection 10b pushes the central movable contact 6 to yield it so that the movable contact 6 contacts with the fixed contact 2. In the above described conventional multi-directional switch, the first stem 8 comprises the cylindrical portion 8a and the skirt portion 8b, and the second stem 10 is upwardly projected from the first stem 8. Consequently, the height of the switch becomes large, and hence it is difficult to reduce the thickness and the size of the switch. Another known multi-directional manual switch is disclosed in GB-A-2331850. This discloses a multi-directional manual switch comprising a substrate having plurality of fixed contacts and a movable contact provided above each of the fixed contacts so that opposite contacts form a unit switch and a holding plate having a spherical overhang holding wall mounted on the substrate; an operating plunger slidably mounted in a hole formed in the holding plate, and rotatably held in the spherical overhang holding wall, and a plurality of projections forming the underside of the plunger, each of the projections being provided corresponding to the movable contact. The operating plunger of GB-A-2331850 comprises a lower cylindrical portion 30 and an upper portion 2 upwardly projected from the cylindrical portion 30. Consequently, similar to the arrangement described above the height of the switch is large and it is difficult to reduce the thickness and size of the switch. SUMMARY OF THE INVENTION An object of the present invention is to provide a multi-directional switch which may be reduced in thickness and size thereof. Another object of the invention is to provide a multi-directional switch which is simple in constructions and reliable in operation. According to the present invention, there is provided a multi-directional manual switch comprising: a circuit board having a plurality of fixed contacts and a moveable contact provided above each of the fixed contacts so that opposite contacts form a plurality of unit switches; a flat holding plate having a spherical overhang holding wall and mounted on the circuit board, characterized in that the flat holding plate has a hole having radially extending branch holes, an operating plunger is made of a flat plate and has a plurality of radially extending arms axially slidably mounted in the branch hole of the hole of the holding plate, and is rotatably held in the spherical overhang holding wall at spherical projections formed at a central portion thereof; and a plurality of projections are formed on an underside of the plunger, so that each of the projections is provided corresponding to each of the movable contacts. The unit switches comprise a central unit switch and a plurality of peripheral unit switches, the projections comprise a central projection and peripheral projections corresponding to the unit switches, the operating plunger is rotatably and axially slidably mounted in the spherical overhang holding wall, and a gap is formed between each of the peripheral projections and the corresponding movable contact in the condition that the central projection contacts with the corresponding movable contact. The movable contact has an inverted tray shape, and the fixed contact of the unit switch comprises a central fixed contact and a plurality of peripheral fixed contacts. These and other objects and features of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS Fig. 1 is a plan view showing a multi-directional switch according to the present invention; Fig. 2 is a sectional view taken along a line II-II of Fig. 1; Fig. 3 is a sectional view taken along a line III-III of Fig. 1; Fig. 4 is a perspective view of a plunger; Fig. 5 is a perspective view of a movable contact; Figs. 6 to 8 are similar drawings to Figs. 1 to 3 for explaining one of operations of the switch; Figs. 9 to 11 are similar drawings to Figs. 1 to 3 for explaining another operation of the switch; and Fig. 12 is a sectional view of a conventional multi-directional switch. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to Figs. 1 through 3, the multi-directional switch of the present invention comprises a flat body 20 and a flat operating plunger 25. The body 20 is formed by laminating a plastic holding plate 21, a plastic spacer 22 and a printed circuit board 23. As shown in Fig. 1, the body 20 has a square shape. The holding plate 21 has a hole 24 in a shape of a cross along the diagonal of the square. Each branch of the hole has a narrow base portion and a wide end portion. The operating plunger 25 is slidably mounted in the hole 24. As shown in Fig. 4, each arm of the operating plunger 25 comprises a narrow base portion 25a and a manipulating end portion 25b. The gap between the manipulating end portion 25b and the wall of the hole 24 is small so that the arm may not pivot in the hole. Referring to Figs. 1 and 2, the holding plate 21 has four supporting portions 27 between adjacent holes 24, each having a spherical overhand holding wall 27a. The operating plunger 25 has four spherical projections 26 between adjacent base portions as shown in Fig. 4. The spherical projections 26 are rotatably supported by the holding walls 27a and prevented from upwardly removing. As shown in Fig. 4, a part of the spherical projection 26 is positioned within the thickness of the operating plunger. Therefore, the height of the switch can be reduced. Referring to Fig. 1, five apertures 28 are formed in the spacer 22 at a central portion and at four portions corresponding to manipulating end portions 25b of the operating plunger 25. In each aperture 28, a circular movable contact 29 is disposed and positioned therein. As shown in Fig. 5, the movable contact 29 has an inverted tray shape having a spherical central portion 29b, and four feet 29a. Each foot 29a contacts with a peripheral fixed contact 32 provided on the printed circuit board 23. The central portion 29b is positioned above a central fixed contact 33 on the circuit board 23. Referring to Fig. 3, on the underside of a central portion of the operating plunger 25, a spherical central projection 30 is formed corresponding to the central fixed contact 33, and a spherical peripheral projection 31 is formed on the underside of each manipulating end portion 25b corresponding to the peripheral fixed contact 32. Although the central projection 30 contacts with the central movable contact 29, the peripheral projections 31 are not contacted with the peripheral movable contact 29, the peripheral projections 31 are not contacted with the peripheral movable contacts 29, thereby providing a gap C there-between. A protective plastic film (not shown) is provided between the holding plate 21 and the spacer 22 so as to protect the circuit on board 23 and the movable contacts 29 from water and dust. In operation, referring to Figs. 7 and 8, when a central portion of the operating plunger 25 is depressed by a finger of an operator as shown by an arrow F, the operating plunger is lowered, keeping a horizontal position. Consequently the central movable contact 29 is yielded to be contacted with the central fixed contact 33 on the circuit board 23. Thus the peripheral fixed contacts 32 are connected to the central fixed contact 33 by the movable contact 29, so that the central switch is closed. At that time, the peripheral projections 31 do not deform the peripheral movable contacts 29 as shown in Fig. 8. This is caused by the gap C in Fig. 3. Namely, the gap C is provided to have a sufficient height so as not to deform the movable contact 29. Even if the operating plunger 25 is slightly tilted, the peripheral switch is not closed. More particularly, the component of the force F at the end portion 25b of the arm is very small compared with the force F at the central portion because of a large lever ratio. Furthermore, since the arm is a cantilever, the arm is flexed when the arm contacts with the fixed contact. Because of these conditions, the peripheral switch is not closed, as long as the arm is not tilted at an extremely large angle. Referring to Figs. 10 and 11, when one of the manipulating end portions 25b of the operating plunger 25 is depressed, the spherical peripheral projection 31 deforms the movable contact 29, so that the movable contact 29 is contacted with the central fixed contact 32. Thus, the peripheral switch is closed. At that time, the operating plunger 25 rotates about a center of the sphere by the spherical overhang holding wall 27a, so that the projection 30 does not deform the movable contact 29 as shown in Fig. 10. Furthermore, other peripheral end portions 25b do not deform the corresponding movable contacts 29 since component of the force of each end portion 25b is small because of the large lever ratio as described above. In accordance with the present invention, since the multi-directional switch is composed by a flat body and a flat operating plunger, the thickness of the switch can be reduced and the construction is simple. In addition, since the plunger is mounted in a hole of the body, the thickness is further reduced. While the invention has been described in conjunction with preferred specific embodiment thereof, it will be understood that this description is intended to illustrate and not limit the scope of the invention, which is defined by the following claims.

Claims: A multi-directional manual switch comprising: a circuit board (23) having a plurality of fixed contacts (32, 33) and a movable contact (29) provided above each of the fixed contacts so that opposite contacts form a plurality of unit switches; a flat holding plate (21) having a spherical overhang holding wall (27a) and mounted on the circuit board, characterized in that the flat holding plate (21) has a hole (24) having radially extending branch holes, an operating plunger (25) is made of a flat plate and has a plurality of radially extending arms axially slidably mounted in the branch hole of the hole (24) of the holding plate, and is rotatably held in the spherical overhang holding wall at spherical projections (26) formed at a central portion thereof; and a plurality of projections (30, 31) are formed on an underside of the plunger, so that each of the projections is provided corresponding to each of the movable contacts. The multi-directional manual switch according to claim 1 wherein the unit switches comprise a central unit switch and a plurality of peripheral unit switches, the projections (31) comprise a central projection(30) and pherical projections(31) corresponding to the unit switches, the operating plunger is rotatably and axially slidably mounted in the spherical overhang holding wall, and a gap is formed between each of the peripheral projections and the corresponding movable contact in a condition that the central projection contacts with the corresponding movable contact. The multi-directional manual switch according to claim 1 wherein the movable contact has an inverted tray shape, and each of the fixed contacts of the unit switch comprises a central fixed contact (33) and a plurality of peripheral fixed contacts (32). The multi-directional manual switch according to claim 3 wherein each of the movable contacts has feet (29a) contacted with the peripheral fixed contacts.

Inventors: MIYASHITA ISAO, MIYASHITA, ISAO, Miyashita, Isao, c/o Citizen Electronics Co. Ltd
Applicants: CITIZEN ELECTRONICS, CITIZEN ELECTRONICS CO., LTD.
Application year: 2000
Main classification: H01H25
IPC codes: H01H25, H01H3, H01H9