Abstract:
A switch capable of individually switching two circuits through a double action of an actuator. The switch comprises: an actuator adapted to slide in a casing by a given stroke; a spring for energizing the actuator toward an initial position; a locking mechanism for preventing the actuator from returning toward the energizing direction by the spring at an intermediate position in the stroke; primary-side contacts adapted to be switched by means of the actuator in the course of movement thereof from the initial position to the intermediate position in the stroke; and secondary-side contacts adapted to be switched by means of the actuator in the course of movement thereof where the actuator further reciprocates against the spring from the locked state at the intermediate position.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a double-action switch capable of individually switching two sets of contacts. 
     2. Description of the Prior Art 
     In switches having two circuits wherein a first circuit is actuated and then a second circuit is actuated while the first circuit is held in its actuated state, it is often necessary to provide two switches operated independently and connected to the respective circuits. When two switches are provided, there is a need for providing space on a chassis or the like for mounting the switches, which increases the overall size of the part containing the two switches. Moreover, there are possibilities that the operator may forget to turn OFF one of the switches in operation. Therefore, the operation of such switches of the prior art is complicated. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide a switch capable of individually switching two circuits through a double action of a single actuator, thereby overcoming the above-mentioned disadvantages of the prior art. 
     Other objects and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following drawings illustrate preferred embodiments of the present invention, in which: 
     FIG. 1 is an exploded perspective view of a switch in accordance with a preferred embodiment of the present invention; 
     FIG. 2(A) is a longitudinal sectional view of the switch shown in FIG. 1 in the initial-position state; 
     FIG. 2(B) a plan view of a part of the switch shown in FIG. 1 in the initial-position state, particularly illustrating the operation of the contacts thereof; 
     FIG. 3(A) is a longitudinal sectional view of the switch shown in FIG. 1 in the locked state; 
     FIG. 3(B) is a plan view of a part of the switch shown in FIG. 1 in the locked state, particularly illustrating the operation of the contacts thereof; 
     FIG. 4(A) is a longitudinal sectional view of the switch shown in FIG. 1 in the state where an actuator thereof is moved from the locked state; 
     FIG. 4(B) is a plan view of a part of the switch shown in FIG. 1 in the state shown in FIG. 4(A), particularly illustrating the operation of the contacts thereof; 
     FIG. 5(A) is a plan view of a heart-shaped cam groove constituting a locking mechanism of the switch shown in FIG. 1; 
     FIG. 5(B) is a developed sectional view showing the shape of the inside of the heart-shaped cam groove shown in FIG. 5(A); 
     FIG. 6 is a diagram showing the operations of primary and secondary side contacts of the switch of the present invention; 
     FIGS. 7(A) and 7(B) are sectional views of a part of a switch in accordance with another embodiment of the present invention based on the embodiment shown in FIG. 1 with a change in the structure of an auxiliary spring employed therein; 
     FIG. 8(A) is a longitudinal sectional view of the switch in accordance with still another embodiment of the present invention; 
     FIG. 8(B) is a plan view of a part of the switch shown in FIG. 8(A), particularly illustrating the operation of contacts thereof; and 
     FIG. 9 is a partly-sectioned side elevational view of a switch in accordance with a further embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will be described hereinunder with reference to the accompanying drawings. 
     FIG. 1 is an exploded perspective view of a switch in accordance with a preferred embodiment of the present invention. FIGS. 2(A), 3(A) and 4(A) are sectional views of the switch, respectively, while FIGS. 2(B), 3(B) and 4(B) are plan views of a part of the switch, particularly illustrating the operation of the contacts thereof, respectively. 
     A casing 1 has at its upper end a projection 1a formed in the rear part and a pair of pins 1b formed in the front part. A cover 2 for covering the upper side of the casing 1 has a groove 2a formed at its rear end part and notches 2b formed at the sides of its front end. The cover 2 can be secured onto the casing 1 by allowing the groove 2a to engage with the projection 1a as well as the notches 2b to engage with the pins 1b. Contact plates 3 and 4 constituting primary-side contacts are mounted in the inner rear part of the casing 1, while contact plates 5 and 6 constituting secondary-side contacts are disposed in front of the contact plates 3 and 4. The contact plates 3, 4, 5, 6 have supporting pieces 3a, 4a, 5a, 6a formed at their respective upper ends. These supporting pieces are inserted in supporting slits 2c, 2d, 2e, 2f formed in the cover 2, respectively. Moreover, the contact plates 3, 4, 5, 6 have supporting pieces 3b, 4b, 5b, 6b formed at their respective lower ends. These supporting pieces are inserted in supporting slits (not shown) formed in the bottom part of the casing 1. The contact plates 3, 4, 5, 6 are secured inside the casing 1 through their respective supporting pieces thus supported. In addition, the contact plates 3, 4, 5, 6 are provided with pairs of upper and lower resiliently contacting pieces 3c, 4c, 5c, 6c. The resiliently contacting pieces 3c and 5c are adapted to resiliently contact one inner surface 1c of the casing 1, while the resiliently contacting pieces 4c and 6c are adapted to resiliently contact the other inner surface 1d. Furthermore, the contact plates 3, 4, 5, 6 have resiliently deformable arms 3d, 4d, 5d, 6d respectively. As shown in FIG. 4(B), a contact 3e formed at the end of the arm 3d and a contact 4e formed at the end of the arm 4d are adapted to resiliently contact each other (the primary-side contacts), while a contact 5e formed at the end of the arm 5d and a contact 6e formed at the end of the arm 6d are adapted to resiliently contact each other (the secondary-side contacts). Similarly, terminals 7, 8, 9, 10 are mounted inside the casing 1. The terminals 7, 8, 9, 10 have their respective upper ends projecting into supporting slits 2g, 2h, 2i, 2j formed in the cover 2 and their respective lower ends project into supporting slits (not shown) formed in the bottom plate of the casing 1, respectively. In addition, the central part of the terminal 7 is clamped between the resilient contacting piece 3c of the above-mentioned contact plate 3 and the inner surface 1c of the casing 1. Similarly, the terminal 8 is clamped between the resilient contacting piece 4c and the inner surface 1d, while the terminal 9 is clamped between the resilient contacting piece 5c and the inner surface 1c, and the terminal 10 is clamped between the resileint contacting piece 6c and the inner surface 1d. As a result, the terminal 7 and the contact plate 3 are adapted to conduct to each other. Similarly, the terminal 8 and the contact plate 4, the terminal 9 and the contact plate 5, as well as the terminal 10 and the contact plate 6 are adapted to conduct to each other, respectively. Moreover, the casing 1 has a pair of grooves 1e, 1f formed in its front outer surface. A fixing member 11 slidably fitted with the grooves 1e and 1f for fixing the switch main body to the chassis or the like. 
     An actuator 12 is mounted inside the casing 1. The actuator 12 has two actuating members 12a, 12b integrally formed at its lower part. Each of the actuating members 12a, 12b has a pentagonal section, as shown in FIG. 2(B). One actuating member 12a is adapted to be able to intervene between projections 3f, 4f formed on the arms 3d, 4d of the contact plates 3, 4, respectively, forming the primary-side contacts, through the operation of the actuator 12, while the other actuating member 12b is adapted to be able to intervene between projections 5f, 6f formed on the arms 5d, 6d of the contact plates 5, 6, respectively, forming the secondary-side contacts, through the operation of the actuator 12. Moreover, the actuator 12 has a rib 12c formed at its front lower end. Similarly, the actuating members 12a, 12b have ribs 12d, 12e formed at their lower ends. The ribs 12c, 12d, 12e are inserted in a guide groove 1g formed in the bottom plate of the casing 1, thereby allowing the actuator 12 to slide along the guide groove 1g. The actuator 12 has a supporting plate 12f integrally formed at its front part and moreover, a knob-fixing rod 12g is integrally formed at the end thereof. A spring 13 is compressed between the supporting plate 12f and the above-mentioned fixing member 11 so as to urge the actuator 12 away from the fixing member 11. A step 12h is formed in the front upper part of the actuator 12 and adapted to contact the inner surface of a cap 14 secured to the upper part of the casing 1 by means of the spring 13. FIG. 2(A) shows the state where the step 12h is brought into contact with the inner surface of the cap 14. This state is the initial-position state of the actuator 12. In addition, a groove 12i is formed in the rear upper surface of the supporting plate 12f, and an auxiliary spring 15 is inserted inside the groove 12i. Moreover, abutment steps 12j are formed at the upper positions on both sides of the groove 12i. Furthermore, a heart-shaped cam groove 12k is formed on the upper surface of the actuator 12. On the other hand, the above-mentioned cap 14 is secured by fitting fixing holes 14a formed in its sides with projections 1h formed on the casing 1. The cap 14 has a stopper 14b projecting from its front end. When the actuator 12 is pushed inside of the casing 1, the above-mentioned auxiliary spring 15 abuts against the stopper 14b, and when the actuator 12 is pushed in furthermore, the above-mentioned abutment steps 12j can abut against the stopper 14b. A U-shaped pin 16 and a spring 17 for pressing the pin 16 downwardly are mounted inside the cap 14. One of the bent portions of the pin 16 is supported by a supporting hole 14c bored in the front bottom part of the cap 14 so that the pin 16 can pivot horizontally, while the other bent portion is inserted in the heart-shaped cam groove 12k on the actuator 12. 
     FIG. 5(A) is an enlarged plan view of the heart-shaped cam groove 12k formed on the actuator 12. The heart-shaped cam groove 12k has seven cam positions, from (I) to (VII). The surfaces of the respective cam positions vary in contour and elevation as shown in FIG. 5(B) (a developed sectional view). The cam position (V) is formed into an extended groove longer than the corresponding cam groove of conventional cam grooves. The cam position (V) is for allowing the actuator 12 to reciprocate further inwardly in the casing 1 from the locked state. 
     The operation of the switch of the present invention arranged as described above will be described hereinunder. 
     The switch is arranged such that pushing the actuator 12 inwardly allows the primary-side contacts 3e, 4e and secondary-side contacts 5e, 6e to perform ON/OFF operations as shown in a diagram of FIG. 6. It is to be noted that, in FIG. 6, a line α indicates the operation of the primary-side contacts 3e, 4e while a β indicates the operation of the secondary-side 5e, 6e. Moreover, ON denotes the state where the contacts are connected with each other, while OFF designates the state where the contacts are separate from each other. 
     FIGS. 2(A) and 2(B) show the state where the actuator 12 is projected outwardly by the force of the spring 13 and stopped by the contact of the step 12h of the actuator 12 with the inner surface of the cap 13, i.e., the initial state of the switch. Moreover, the end of the pin 16 is at the position (a) in the cam position (I) of the heart-shaped cam groove 12k. Under this initial state illustrated at (a) of FIG. 6, one actuating member 12a provided on the actuator 12 is between the projections 3f and 4f of the two contact plates 3, 4 forming the primary-side contacts, so that the contacts 3e, 4e are separate from each other, i.e., in a non-conducting state (OFF). Also, the other actuator 12b is between the projections 5f and 6f of the two contact plates 5, 6 forming the secondary-side contacts, so that the contacts 5e, 6e are separate from each other, i.e., in a non-conducting state (OFF). 
     As the actuator 12 is pressed inwardly against the spring 13, the end of the pin 16 moves from the cam position (I) to the cam positions (II) and (III) of the heart-shaped cam groove 12k. At an intermediate position (e.g., the position (b)), the actuating member 12a is first slipped out from between the projections 3f, 4f, causing the primary-side contacts 3e, 4e to be brought into the ON state. At this time, the actuating member 12b is still between the secondary-side projections of 5f, 6f, so that the contacts 5e, 6e are in the OFF state (see (b) in FIG. 6). As the actuator 12 is further pressed inwardly, the pin 16 reaches the position (c) in the cam position (IV). At this time, the actuating member 12b is also slipped out from between the projections 5f, 6f, causing the secondary-side contacts 5e, 6e to be also temporarily brought into the ON state (see (c) in FIG. 6). When the pressing force on the actuator 12 is removed at this position, the actuator 12 is returned towards its outer position by the force of the spring 13. Since a step is formed at the boundary between the cam positions (III) and (IV) of the heart-shaped cam groove 12k, the pin 16 urged downwardly by the spring 17 cannot climb over this step. Consequently, the return operation of the actuator 12 allows the pin 16 to reach the position (d) in the cam position (V) one step lower than the cam position (IV). When the pin 16 is at the position (d), the actuator 12 cannot return toward the cam position (IV), i.e., the actuator 12 is locked. This state is shown in FIGS. 3(A) and 3(b). Under this locked state, the actuating member 12b is between the projections 5f, 6f again, so that the secondary-side contacts 5e, 6 e are in the OFF state. Also at this time, the primary-side contacts 3e, 4e are maintained in the ON state (see (d) in FIG. 6). 
     Next, when the actuator 12 is further pressed inwardly under the locked state, the pin 16 moves from the position (d) to the position (e) in the cam position (V). It is to be noted that since the cam position (V) is one step lower than the cam position (IV), there is no possibility that the pin 16 may return to the cam position (IV). The state where the pin 16 has reached the position (e) is shown in FIGS. 4(A) and 4(B). At this time, the actuating member 12b is slipped out from between the projections 5f, 6f, causing the secondary-side contacts 5e, 6e to be brought into the ON state. It is to be noted that, similarly to the case at the position (d), the primary-side contacts 3e, 4e are maintained in the ON state (see (e) in FIG. 6). In addition, when the pin 16 is at the position (e), the auxiliary spring 15 mounted on the front part of the actuator 12 is brought into contact with the front end of the stopper 14b, allowing the finger pressing the actuator 12 to feel a larger resistance. When the pressing force on the actuator 12 is removed at the position where the finger feels the resistance, the actuator 12 is urged outwardly by the force of the spring 13, and the pin 16 returns along the cam position (V) to the position (f), i.e., to the same lock position as the position (d). Thus, by pressing in the actuator 12 from the lock position to the postiion where the resistance force by means of the spring 15 increases and then resistance force by means of the spring 15 increases and then force, the pin 16 is reciprocated in the cam position (V) (the extended groove) in the course, (d)-(e)-(f). Repetition of this reciprocation (the state shown in FIG. 3(A) and that shown in FIG. 4(A) are alternately repeated) permits only the secondary-side contacts 5e, 6e to perform an ON/OFF operation (the line β in FIG. 6) with the primary-side contacts 3f, 4f maintained in the ON state (the line α in FIG. 6). 
     The return operation for bringing each of the primary- and secondary-side contacts into the OFF state will be described hereinunder. As the actuator 12 is pressed in under the state where the pin 16 is at the position (d) or (f), when the pin 16 is at the position (e), the auxiliary spring 16 abuts against the stopper 14b, causing the resistance against the finger to increase (see FIG. 4(A)). When the actuator 12 is further pressed in against the resistance until the abutment step 12j of the actuator 12 is brought into contact with the stopper 14b, the pin 16 reaches the position (g) in the cam position (VI) one step lower than the cam position (V). At this time, both the primary-side contacts 3e, 4e and the secondary-side contacts 5e, 6e are in the ON state (see (g) in FIG. 6). When the pressing force on the actuator 12 is removed at that time, the actuator 12 is returned towards its initial outer position by the force of the spring 13. Since the cam position (VI) is one step lower than the cam position (V), the pin 16 will not return to the cam position (V) but reaches the position (i) in the initial cam position (I) through the cam positions (VI), (VII). Accordingly, the actuator 12 returns to the initial position shown in FIGS. 2(A) and 2(B). In the course of this return operation, the actuating member 12b first intervenes between the projections 5f, 6f, causing the secondary-side contacts 5e, 6e to be brought into the OFF state (see (h) in FIG. 6) and then, the actuating member 12a intervenes between the projections 3f, 4f, causing the primary-side contacts 3e, 4e to be also brought into the OFF state (see (i) in FIG. 6). 
     It is to be noted that although when the pin 16 is at the position (c), both the primary- and secondary-side contacts are once brought into the ON state in the above-described embodiment, it is also possible to move the actuator 12 to the lock position (d) while maintaining the secondary-side contacts 5e, 6e in the OFF state at the position (c), by changing the length of the cam position (IV) or the positional setting of the actuating members 12a, 12b. 
     Another embodiment of the present invention is shown in FIGS. 7(A) and 7(B). 
     The switch shown in FIG. 7(A) has an auxiliary spring 21 mounted on the front part of the actuator 12, which auxiliary spring 21 is a plate spring (the spring 13 employed in the switch shown in FIG. 1 is a coiled spring). The auxiliary spring 21 may be made of metal or integrally formed with the actuator 12 by using the same resin as the material therefor. Moreover, the switch shown in FIG. 7(B) has a rubber bumper 22 secured to the frong part of the actuator 12 in place of the auxiliary spring. 
     The switch shown in FIGS. (A) and 8(B) is provided with as the primary-side contacts, contacts 31a, 32a formed on respective resilient arms 31, 32, similar to those shown in FIG. 1, and as the secondary-side contacts, contacts 33a, 34a are formed on a thin movable piece 33 and a thick movable piece 34 respectively. The primary-side contacts 31a, 32a are disposed at the front position in a casing 30, while the secondary-side contacts 33a, 34a are disposed at the rear position therein. An actuator 35 slidably provided in the casing 30 is energized in the projecting direction by means of a spring 36. The actuator 35 is provided with an actuating member 35a similar to that shown in FIG. 1 and an actuating member 35b projecting rearwardly. Moreover, a heart-shaped cam groove 35c completely identical to that shown in FIGS. 5(A) and 5(B) is formed on the upper surface of the actuator 35, and one end of a pin 38 disposed in a cap 37 provided on the upper part of the casing 30 is inserted in the heart-shaped cam groove 35c. 
     The operation of this switch will be described hereunder. Referring to FIGS. 8(A) and 8(B) showing the switch in the initial position, the actuating member 35a is between the projections 31b and 32b, so that the primary-side contacts 31a, 32a are in the OFF state. The rear actuating member 35b is also separate from the movable piece 33, so that the secondary-side contacts 33a, 34a are also in the OFF state. Under this state, the end of the pin 38 is at the position (a) (see FIG. 5(A)) in the cam position (I) of the heart grooved cam 35c. As the actuator 35 is pressed inwardly until the pin 38 reaches the position (d) in the cam position (V) through the cam positions (II), (III), (IV) and the actuator 35 is brought into a locked state where it is prevented from returning, the actuating member 35a is slipped out from between the projections 31b, 32b, causing the primary-side contacts 31a, 32a to resiliently contact each other, i.e., the primary-side contacts 31a, 32a are brought into the ON state. At this point of time, the actuating member 35b is separate from the movable piece 33, so that the secondary-side contacts 33a, 34a are still in the OFF state. When the actuator 35 is further pressed in from this lock position, the actuating member 35b presses the movable piece 33, causing the secondary-side contacts 33a, 34a to contact each other, i.e., the secondary-side contacts 33a, 34a are brought into the ON state. At the time when the actuating member 35b presses the movable piece 33 to resiliently contact the movable piece 34, the pin 38 reaches the position (e) (see FIG. 5(A)) in the cam position (V) of the heart-shaped cam groove 35c. Since the movable piece 34 is formed of a relatively thick plate material, there is an increase in the resistance against the finger pressing the actuator 35. When the pressing force on the actuator 35 is removed at the time when the resistance against the finger increases, the actuator 35 is returned by the spring 36, and the pin 38 returns from the position (e) to the position (f) in the cam position (V) (the extended groove), causing the actuator 35 to be brought into the locked state again. In other words, by repeating the process that the actuator 35 under the locked state is pressed inwardly until the movable piece 33 is brought into resilient contact with the movable piece 34 and the resistance against the finger increases, the secondary-side contacts 33a, 34a are allowed to perform an ON/OFF operation with the primary-side contacts 31a, 32a maintained in the ON state. Next, in the return operation for making both the primary and secondary sides OFF, the actuator 35 is pressed into a deeper position. When the actuating member 35b causes the movable piece 33 to resiliently contact the movable piece 34, the resistance against the finger increases. However, when the thick movable piece 34 is deflected, the pin 38 reaches the position (g) in the cam position (VI) of the heart groove cam 35c one step lower than the cam position (V). Then when the pressing force on the actuator 35 is removed, the actuator 35 is returned by the spring 36, and the pin 38 returns to the position (i) in the cam position (I) through the cam positions (VI), (VII), causing the actuator 35 to return to the initial position shown in FIGS. 8(A), 8(B). 
     In the embodiment shown in FIG. 9, two actuators 41 (a secondary-side actuator) and 42 (a primary-side actuator) are disposed in series in a casing 40. The secondary-side actuator 41 and the primary-side actuator 42 are urged in the leftward direction as viewed in the Figure (initial positions) by means of springs 43, 44 respectively. The secondary-side actuator 41 is provided with an arm 41a, which is adapted to actuate secondary-side leaf contacts 45. On the other hand, the primary-side actuator 42 is adapted to actuate a self-locking switch 46 disposed in the rear part of the casing 40. In the self-locking switch 46, primary-side contacts are provided. 
     FIG. 9 shows the switch in the initial position state. Under this state, both the actuators 41, 42 are projected leaftwardly. The arm 41a of the actuator 41 is separate from the secondary-side contacts 45, so that they are in the OFF state. Moreover, the primary-side self-locking switch 46 is in the OFF state. When the secondary-side actuator 41 is pressed into the casing 40 under this state, the end of the actuator 41 presses the primary-side actuator 42. A given amount of pressure allows the actuator 42 to move in the direction (shown by an arrow) against the spring 44, and the actuator 42 is locked at that position. At this time, the contacts in the primary-side self-locking switch 46 are brought into the ON state. The actuator 42 stops at the lock position. On the other hand, the secondary-side actuator 41 is returned by the force of the spring 43, causing a gap l to be produced between this actuator 41 and the primary-side actuator 42. Thereafter, it is possible to bring the secondary-side contacts 45 into the ON state by pressing the secondary-side actuator 41 until it contacts the primary-side actuator 42. In other words, operating the secondary-side actuator 41 by a stroke l permits the secondary-side contacts 45 to perform an ON/OFF operation with the primary-side contacts in the self-locking switch 46 maintained in the ON state. Next, in order to bring the primary-side contacts into the OFF state, the actuator 41 is pressed further inwardly from the position where it is brought into contact with the actuator 42. As a result, the lock in the self-locking switch 46 is canceled. Both the actuators 41, 42 are returned to their respective initial positions shown in FIG. 9 by the forces of the springs 43, 44. Consequently, the primary-side contacts in the self-locking switch 46 are brought into the OFF state and at the same time, the secondary-side contacts 45 are also separated from each other, returning to the OFF state. 
     As will be fully understood from the foregoing description, according to the present invention, it becomes possible to repeat the switching operation of the secondary-side contacts with the primary-side contacts maintained in the switched state, since the actuator is locked at the intermediate position in the stroke as well as made capable of reciprocating within a given distance under the locked state so as to switch the primary-side contacts while moving from the initial position to the locked position as well as switch the secondary-side contacts by the reciprocating operation. Accordingly, a single switch can switch two or more circuits, so that it is possible to reduce the space for mounting switches. Moreover, since the primary and secondary side contacts can be simultaneously brought into the OFF state, there is no possibility that the operator may forget to turn OFF one of the switches, which often occurs in the case where two switches are provided. 
     Although the invention has been described through specific terms, it is to be noted here that the described embodiments are not exclusive and various changes and modification may be imparted thereto without departing from the scope of the invention which is limited solely by the appended claims.