Abstract:
An electromagnetic relay comprising a flat electromagnet, a movable plate member having on a lower surface a plurality of projections and a contact circuit device as stacked up together, said contact circuit device including a plurality of contact switching members each of which consists of a single movable blade and a single stationary contact, said movable blade being biased by the projections in accordance with their movement so as to provide a switching operation in cooperation with the corresponding stationary contact.

Description:
BRIEF SUMMARY OF THE INVENTION 
     The present invention relates to a flat-shaped electromagnetic relay providing a plurality of contact open-and-close operations, and more particularly to a thin flat-shaped electromagnetic relay of stacked-up construction having a flat-shaped electromagnetic device and a flat-shaped contact circuit device driven by the electromagnetic device. 
     The conventional flat-shaped electromagnetic relay for use on printed circuit boards is essentially such that an electromagnetic device and a contact device of a hinge-type relay are horizontally assembled in side-by-side relationship or a stamped plate is employed for use as a magnetic circuit. Since such relay employs the contact device wherein a pair of make and break contacts are disposed facing each other with respect to a common contact therebetween, it has the disadvantage that the height of the relay cannot be smaller than a certain height, e.g. 10 mm, because such contact device requires a certain minimum height. If it is attempted to reduce the height, the relay has had to be increased in lateral dimensions. A packed reed relay for use on a printed circuit board also is well known which is constructed in the same configuration as an IC package. Since such a reed relay normally provides a make-contact only in response to energization thereof and may cause a characteristic stick accident between contacts, the reed relay is restricted in use. 
     The present invention, on the other hand, enables an electromagnetic relay to be constructed within desired extremely small volumetric dimensions, such as an IC package 8mm in height, and to provide precise multiple switching operations by forming the relay of thin flat-shaped electromagnetic and contact circuit devices as stacked up together, said contact circuit device comprising a plurality of contact switching members each of which consists of a single movable blade and a single stationary contact so as to ensure a small overall height. 
     It is, therefore, a primary object of the present invention to provide an electromagnetic relay which is small in size, especially in height, and is easy to assemble. 
     It is a further object of the present invention to provide an electromagnetic relay which comprises a flat-shaped electromagnetic device and a flat-shaped contact circuit device. 
     It is a still further object of the present invention to provide an electromagnetic relay having a plurality of contact switching members each consisting of a single movable blade and a single stationary contact wherein the contact switching members are driven to move in a predetermined relation. 
     It is another object of the present invention to provide an electromagnetic relay wherein each contact switching member performs an independent switching operation without interference with neighboring contact switching members and is shielded from external electric noise. 
     It is still another object of the present invention to provide an electromagnetic relay which is highly resistant to external forces acting thereon and may be of a hermetic seal. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     Other objects as well as the numerous advantages of the electromagnetic relay according to the present invention will become apparent from the following detailed description and the accompanying drawings, in which: 
     FIG. 1 is a perspective disassembled view showing an electromagnetic relay as one embodiment of the present invention; 
     FIG. 2 is a front assembled sectional view showing the electromagnetic relay of FIG. 1; 
     FIG. 3 is a perspective view showing a lower surface of a plate member of the relay of FIG. 1; 
     FIG. 4 is a top plan semi-assembled view showing a contact circuit device of the relay of FIG. 1; 
     FIG. 5 is a front sectional view taken along the line A-A of the device FIG. 4; 
     FIG. 6 is a bottom plan view showing the device of FIG. 4; 
     FIG. 7 is a front sectional view taken along the line B-B of the device of FIG. 6; 
     FIG. 8 is a side partially sectional view of the device of FIG. 4; 
     FIG. 9 is a plan view of a lead frame for use in the device of FIG. 4; 
     FIG. 10 is a schematic illustration showing construction of contact switching members of the relay of FIG. 1; 
     FIG. 11 is a schematic illustration showing the movement of the plate member of FIG. 3; 
     FIG. 12 is a perspective segmentary view as semi-assembled showing a contact switching member of the contact circuit device shown in FIG. 1. 
    
    
     DETAILED DESCRIPTION 
     Referring, now, to FIG. 1 and FIG. 2, there is shown an electromagnetic relay as one embodiment of the present invention. The electromagnetic relay is of a stacked-up construction having a flat electromagnetic 100, a movable plate member 200, and a flat contact circuit device 300. The electromagnet 100 and the plate member 200 form a flat electromagnetic device. A cover 400 is an upper cover member, the inner surface of which is adapted to contact a peripheral side wall 311 of a base 310. The electromagnet 100 consists of I-shaped magnetic core 110 which is covered with a molded plastic 120, and a coil 130 which is wound on a spool formed in a center portion of the core 110. The plate member 200 includes a permanent magnet 220, a soft magnetic bar 230, a pair of stub shafts 241 and a molded plastic carrier 240 carrying the magnet 220, the bar 230 and the shafts 241. The permanent magnet 220 may be a permanent magnet rod as a whole, or a soft magnetic bar carrying on a middle portion thereof a permanent magnet piece. The plate member 200 is mounted on the base 310 so as to be swingable with respect to the shafts 241. The shafts 241 are positioned at both ends of the carrier 240 in the centerline between the magnet 220 and the bar 230, and are swingably supported by a pair of recesses 312 formed in an inner surface of the side wall 311. The recesses 312 also receive the ends 121 of the electromagnet 100 which are positioned above the plate member 200. As shown in FIG. 3, the plate member 200 has on the lower surface thereof eight projections 203 to 210 which are positioned in parallel and spaced-apart side portions thereof. 
     In FIGS. 4,5,6,7,and 8, there is shown the contact circuit device 300 as semi-assembled before movable contact members 330 are assembled therein, and external terminals 1a to 12a and 1b to 12b are cut out from a lead frame 320. The lead frame 320 is made from single sheet of metal, e.g., phosphor bronze, by stamping as shown in FIG. 9. The base 310 is a molded plastic which is molded on the lead frame 320. The inner end of each of external terminals 1a to 12a and 1b to 12b is extending inwardly of the base 310 and is exposed to an inner compartment 313 thereof so as to carry on the lower surface of the base 310 the movable contact member 330 or a stationary contact member 340. Some of the movable contact members 330 are fixed to ends 3a&#39;, 5a&#39;, 8a&#39;, and 10a&#39; of terminals 3a, 5a, 8a, and 10a in one direction and the remaining members 330 to ends 4b&#39;, 6b&#39;, 7b&#39;, and 9b&#39; if terminals 4b, 6b, 7b, and 9b in the opposite direction, by spot welding. Stationary contact members 340 are respectively fixed to inner ends 3b&#39;, 4a&#39;, 5b&#39;, 6a&#39;, 7a&#39;, 8b&#39;, 9a&#39;, and 10b&#39; of the corresponding terminals. The base 310 has eight through holes 3c, 4c, 5c, 6c, 7c, 8c, 9c, and 10c adjacent to the stationary contact members 340, so that the projections 203 to 210 may depress the corresponding movable contact members 330 through the holes 3c to 10c. 
     As shown in FIG. 2, when the coil 130 is not excited, the permanent magnet 220 will be attracted by the core 110 into contact therewith, and the projections 204, 206, 207, and 209 will downwardly depress the corresponding movable contact members 330. When the coil 130 is excited, the core 110 will be magnetized in a reverse direction so that the permanent magnet 220 repels the core 110 and the soft magnetic bar 230 is attracted by the core 110, with the result that the projections 203, 205 208, and 210 will downwardly depress the corresponding movable contact members 330. As shown in FIG. 10, the relay of FIG. 1 provides a contact construction wherein break-contacts (i.e. contact circuit opened upon energization) can be formed between the external terminals 3a and 3b, 5a and 5b, 8a and 8b, and 10a and 10b, and make-contacts, (i.e. a contact circuits closed upon energization) can be formed between the external terminals 4a and 4b, 6a and 6b, 7a and 7b, and 9a and 9b,respectively. The arrow marks in solid line of FIG. 10 show the biasing forces applied to the movable contact members 330 when the coil 130 is excited, and the arrow marks in broken line show the biasing forces applied to the members 330 when the coil 130 is not excited. 
     External terminals 1a, 1b, 12a, and 12b are coil input terminals which are electrically connected to the coil 130 and also to diodes 308 and 309 for absorbing the back electromotive force. The diodes 308 and 309 are mounted in grooves 301 and 302 formed in the base 310. External terminals 2a, 2b, 11a, and 11b are ground terminals which, as shown in FIG. 9, are connected to a shield plate 322 and tongues 324. The tongues 324 are adapted to engage with the core 110 as assembled. The grounded core 110 is for use as a shield member which can shield the contact circuit device 300 from external magnetic noise in low frequency. The grounded shield plate 322 is for use as an electrostatic screening member and high frequency magnetic shield member so as to shield the contact members of the device 300 from the external noise. The shield plate 322 having a plurality of apertures 323 which are filled with a portion of the resin base 310 not only provides tight contact between the thin base 310 and the plate 322, but also reinforces the base 310 as a whole. 
     In FIG. 12, there is shown a portion of the semi-assembled contact circuit device 300. The base 3l0 has on the lower surface a plurality of walls e and grooves d to provide an electrically isolated free space or compartment between the movable and stationary contact members 330 and 340 of each contact pair. The movable contact members 330 each consists of a base 331 and movable twin-contacts 332. The base 331 is fixed to the end 4b&#39; of the terminal 4b by spot welding, and the contact member 330 is flexably mounted on the base 310. In assembling, the member 330 can be easily positioned in the base 310 by fitting the base 331 to the groove d. Each wall e of the base 310 is adapted to contact a cover plate 500 so as to provide a closed compartment. By sealing the joint of the base 310 and cover members 400 and 500 with adhesive material, the relay may be hermetically sealed as a whole. If the plate 500 is made of magnetic material, the relay may be magnetically shielded. 
     Since the relay is of the stacked-up construction having electromagnet 100, plate member 200, and contact circuit device 300, the major dimensions of the relay mainly depend upon the accuracy of metal moulds for molding plastics. As shown in FIG. 11, and error x of stroke X of the projection from the original position of FIG. 11 to an operating position, where the movable contact member disengages from the stationary contact member, is mainly defined by errors p, q, r, and s of the metal moulds. Stated differently, the relay may be precisely and easily assembled without adjustment. 
     The base 310 has on the upper surface a rib 314 in the direction crossing the walls e on the lower surface thereof at right angles, so that the thin base 310 may be reinforced. 
     As shown by broken lines in FIG. 4, the external terminals are cut out from the plate 320 and bent in the shape shown in FIG. 1. If necessary, a common portion, such as a portion 321 between 6b and 7b, may be left uncut to provide a make-and-break-contact circuit. 
     As another embodiment of the present invention, pairs of movable and stationary contact members may be disposed in other modified arrangements. For example, all movable contact members may be arranged in the same direction so that make-contact only or break-contact only may be provided. Or the base of each movable contact member may be disposed near the longitudinal centerline of the base (310 in the embodiment shown in the drawings and the free end thereof be arranged adjacent to both sides of the base of the contact circuit device. Alternatively, each pain of movable and stationary contact members may be mounted on the upper surface of the base of the contact circuit device, so that when the projections positioned in a lower position depress the movable contact members, the movable contact members will come in contact with the corresponding stationary contact members. 
     Moreover, the external terminals may be arranged to extend from the lower surface of the contact circuit device. 
     In the foregoing embodiments, the plate member carries the permanent magnet which urges the plate member toward its original position as a resetting member. Alternatively, the plate member may be of the construction having a resetting spring in place of the permanent magnet. 
     As still another embodiment of the present invention, a plate member carrying a soft magnet bar may be mounted over an electromagnet, wherein the plate member is fixed to, and the electromagnet having projections is swingably mounted on, a contact circuit device. 
     It should be understood the above description is merely illustrative of the present invention and that many changes and modifications may be made by those skilled in the art without departing from the scope of the appended claims.