Patent Publication Number: US-6218635-B1

Title: Push and rotary operating type electronic device

Description:
FIELD OF THE INVENTION 
     The present invention relates to a push and rotary operating type electronic device mainly employed in communication terminal equipment such as a portable telephone. Such a push and rotary operating type electronic device is operated by rotating a portion of an outer periphery of a cylindrical operating knob projecting from an operating surface of the equipment toward a tangential direction and also by depressing the same toward a center of rotation. 
     BACKGROUND OF THE INVENTION 
     A rotary encoder equipped with a push switch such as one shown in a general perspective view of FIG. 12 is a type of push and rotary operating type electronic devices heretofore known. 
     This rotary encoder equipped with a push switch includes a mount board  1  having contact points, a rotary encoder unit  2  as a rotary operating type electronic component disposed on the mount board  1 , and a push switch unit  3  as a push-to-operate type electronic component also disposed on the mount board  1  at an opposite side of the rotary encoder unit  2 , as shown in FIG. 12 and a sectioned side view of FIG.  13 . The rotary encoder unit  2  is fixed in such a manner as to be movable for a certain extent in a vertical direction (the direction of an arrow V shown in FIG.  12  and FIG.  13 ). The push switch unit  3  is fixed so as not to be movable. 
     The mount board  1  having contact points includes a plate-shaped plastic body provided with a recess  5  including guide rails  4  for the rotary encoder unit  2  to move along, another recess  6  for fixing the push switch unit  3 , and contact plates  8  having terminals  7  protruding downwardly for leading an electric signal of the rotary encoder unit  2  to an outside, as shown in a general perspective view of FIG.  14 . 
     The rotary encoder unit  2  includes: (a) a sliding contact body  9  made of plastic, inserted into the recess  5  of the mount board  1  having contact and retained by the guide rails  4  so as to be movable within a certain extent in the vertical direction (the direction of the arrow V shown in FIG.  12  and FIG.  13 ); (b) a resilient metal plate  10  mounted in plastic resin of the sliding contact body  9  by insertion molding, and having flexible contact blades  11 A and  11 B extending both forward and backward; (c) a rotor  14  made of plastic provided on its back surface with a radially-extended movable contact plate  13 , to which the flexible contact blade  11 A makes resilient contact, and held rotatably with a cylindrical axle  12 , which is fixed in a center of the sliding contact body  9 ; and (d) a disk-shaped operating knob  15  mounted with the cylindrical axle  12  in between so as to rotate the rotor  14 , as shown in the sectioned side view of FIG.  13 . The flexible contact blade  11 B extending backward from the sliding contact body  9  is in resilient contact with the contact plates  8  on the mount board  1  having contact points in order to lead an electric signal from the rotary encoder unit  2 . 
     A leaf spring  16  protruding from a bottom end of the sliding contact body  9  provides for a biasing force by contacting resiliently against pin-shaped projections  17  (refer to FIG. 14) on a front surface of the mount board  1  having contact points in order to maintain the rotary encoder unit  2  in a position apart from the push switch unit  3  in an ordinary condition. 
     The push switch unit  3  is fixed on the mount board  1  having contact points by being inserted in the recess  6  on a surface opposite to the rotary encoder unit  2  in a manner that an actuating button  18  of the push switch unit  3  is in contact with a pushing section  12 A at the backside of the cylindrical axle  12  of the rotary encoder unit  2 , as shown in FIG.  13 . Terminals  19  for leading an electric signal to the outside protrude downwardly below the mount board  1 . 
     As the rotary encoder equipped with a push switch is constructed as above, it is mounted on a wiring board  20  in equipment, with the terminals  7  of the rotary encoder unit  2  and the terminals  19  of the push switch unit  3 , all protruding from a mount surface at the underside of the mount board  1 , inserted into mount holes  21  and  22  and soldered, as shown in FIG. 15, when it is installed in the communication terminal equipment and the like. 
     The rotary encoder is installed in a manner that a peripheral rim  15 A of the disk-shaped operating knob  15  protrudes from an operating surface  23  on an upper enclosure of the equipment in order that the peripheral rim  15 A is manipulable. 
     The rotary encoder equipped with a push switch constructed as above operates in a manner, which will be described hereinafter. 
     When the peripheral rim  15 A of the disk-shaped operating knob  15  is turned by applying a force in a tangential direction (the direction of an arrow H shown in FIG.  12 ), the rotor  14  rotates about the cylindrical axle  12 . 
     A flexible contact blade  11 A fixed to the sliding contact body  9  at a front side slides resiliently over the radially-extended movable contact plate  13  on the back surface of the rotor  14  so as to make and break an electric current, thereby functioning as the rotary encoder unit  2 . The electric current is transferred from the flexible contact blade  11 A to the contact plate  8  on the mount board  1  having contact points via the flexible contact blade  11 B in the back. The electric current is then communicated to a circuit on the wiring board  20  of the equipment through the terminals  7  provided for external connection. 
     As shown in FIGS. 13 and 15, a depressing force is given on the peripheral rim  15 A of the disk-shaped operating knob  15  in a vertically downward direction (the direction of the arrow V 1 ) toward a center of the disk-shaped operating knob  15  against a biasing force of the leaf spring  16 , which thrusts the rotary encoder unit  2  upward, to move the whole rotary encoder unit  2  along the guide rails  4  on the mount board  1  having contact points. This causes the pushing section  12 A of the cylindrical axle  12  to press the actuating button  18 , and actuates the push switch unit  3 . Contacts of the push switch unit  3  close a circuit of the wiring board  20  of the equipment via the terminals  19 . 
     The rotary encoder unit  2  is thrust back and returns into its original position by the resilient restoring force of the leaf spring  16 , when the depressing force being given to the disk-shaped operating knob  15  is removed. 
     When mounting the push and rotary operating type electronic device of the prior art on communication terminal equipment or the like, however, it shall be so mounted as to avoid the mount board  1  having contact points from coming out of the operating surface  23  of the upper enclosure. Since the mount surface of the mount board  1  to be mounted on the wiring board  20  is designed to locate in a position considering the lowest portion of the outside diameter and upward/downward within its movable range of the peripheral rim  15 A of the disk-shaped operating knob  15 , a space between the operating surface  23  and the wiring board  20  in the equipment needs to be widened. This causes a problem that a thickness of the equipment from the operating surface  23  of the upper enclosure to a rear surface of a bottom enclosure becomes so bulky. 
     In addition, the push and rotary operating type electronic device of the prior art requires a circuit for the signal of the rotary encoder unit  2  to include a path through the flexible contact blade  11 B on the sliding contact body  9  and the contact plates  8  on the mount board  1 , thereby giving rise to another problem that demands great care in handling during assembling and for maintaining reliable electrical contacts in a long term of usage due to many flexible contacts and sliding contact plates. 
     SUMMARY OF THE INVENTION 
     A push and rotary operating type electronic device includes: (a) an operating knob having an extended width and a cylindrical shape, and an outer peripheral surface of which is protruded from an operating surface on an upper enclosure of equipment; (b) a substrate body for rotatably supporting a rotatable body at its one side, the rotatable body supporting the cylindrical operating knob rotatably; (c) a rotary operating type component having a rotary contact plate on one of end surfaces of the cylindrical operating knob and a flexible contact blade fixed to the substrate body; and (d) a push-to-operate type component disposed on the substrate body in a manner that it is operated by a rotational movement of the rotatable body caused by a depressing manipulation of the cylindrical operating knob. 
     The push and rotary operating type electronic device of the invention, to be more specific, includes: the cylindrical operating knob supported at both of its end surfaces in a manner to be rotatable around its axis, and for being manipulated with the peripheral surface; the rotary contact plate having an electric contact surface, and disposed on one of the end surfaces of the cylindrical operating knob; the rotatable body supported rotatably at one side of it, and for rotatably supporting the cylindrical operating knob; the substrate body for rotatably supporting the rotatable body together with the cylindrical operating knob as an integral unit; the push-to-operate type component disposed on the substrate body in a position apart from a supporting portion of the rotatable body in such a manner as to be operated by rotational motion of the rotatable body; and a contact bar having the flexible contact blade at one end for contacting resiliently with an electric contact surface provided on the rotary contact plate and an externally connecting terminal at the other end of it, and fixed to the substrate body. 
     A push and rotary operating type electronic device has such features as: (a) it can enlarge the manipulating surface of the operating knob because of its extended width and cylindrical shape; (b) it can reduce a height dimension of an enclosure of the equipment in which this push and rotary operating type electronic device is installed; (c) the push-to-operate type component can be manipulated smoothly, since the rotatable body can move around the supporting part at one side of it, when the cylindrical operating knob is depressed; and furthermore (d) it provides high contact reliability at a low cost, since it contains a small number of resilient contacts and contacting points. 
     The push and rotary operating type electronic device is provided with an actuator having resiliency as an integral part of or securely fixed to the rotatable body. The push-to-operate type component is actuated by depressing it with this actuator. The actuator having resiliency has an effect of buffering an adverse effect to the push-to-operate type component, if an impulsive load is applied in a direction of depressing the cylindrical operating knob. The actuator can also prevent the push-to-operate type component from making an abnormal sound due to an angular play in the rotatable body. 
     The push and rotary operating type electronic device includes a spring disposed between the rotatable body and the substrate body for providing a biasing force in a direction of separating them with respect to each other. Disposing the spring allows adjustment of the depressing force required to manipulate the push and rotary operating type electronic device to an appropriate value. The spring can also reduce the likelihood of actuating the push-to-operate type component erroneously during a rotating manipulation of the cylindrical operating knob. It also has an effect of preventing an abnormal sound due to an angular play in the rotatable body. 
     The push and rotary operating type electronic device is so constructed that the rotatable body is supported rotatably from both ends at one side of it in a direction parallel to a rotational axis of the cylindrical operating knob, in a span wider than a longitudinal dimension of the cylindrical operating knob, and the push-to-operate type component is disposed at the other side in generally mid point between the supporting portions at both ends of the rotatable body. This structure has an advantageous effect for making the push-to-operate type component to operate by rotating the rotatable body smoothly irrespective of position on a peripheral surface of the cylindrical operating knob where upon the depressing force is applied, when manipulating the cylindrical operating knob. 
     The push and rotary operating type electronic device includes a rotary encoder and a push switch to serve respective functions of the rotary operating type component and the push-to-operate type component. The electronic component providing function of a rotary encoder equipped with a push switch can be connected directly to a digital circuit such as a microcomputer and the like, that are used widely for communication equipment in late years, thereby providing an advantage of simplifying control of the equipment. 
     The push and rotary operating type electronic device is provided with a plurality of radially-oriented ditches and ridges on either of an end surface of the cylindrical operating knob and the rotary contact plate. A bulge on a resilient body retained by the rotatable body is in contact resiliently and slidably on the radially-oriented ditches and ridges. In this structure, the rotary contact plate stops in such a position where the flexible contact blade does not stay in contact with the electric contact surface, when the bulge on the rotatable body slips into any one of ditches. This structure has such advantages as providing a stable manipulation accompanying a feel of clicks when turning the cylindrical operating knob, and no likelihood of producing an erroneous signal due to a malfunction of the rotary operating type component during a manipulation of the push-to-open component. 
     The push and rotary operating type electronic device disposes the flexible contact blade fixed to the substrate body in a manner to make resilient contact with the rotary contact plate in a position on or close to a line drawn between a center of the rotary contact plate and a rotational axis, i.e. a center of a rotational motion of the rotatable body. This arrangement gives an advantage of reducing a shift in position where the flexible contact blade makes resilient contact with the rotary contact plate during a depressing manipulation of the cylindrical operating knob. It also helps to assure a length of the flexible contact blade necessary for it to keep a predetermined magnitude of flexion. 
     The push and rotary operating type electronic device disposes the flexible contact blade fixed to the substrate body in a manner to make resilient contact with the rotary contact plate in a position on or extremely close to a line, which passes through a center of the rotary contact plate in a direction perpendicular to the line drawn between the center of the rotary contact plate and the rotational axis, i.e. the center of the rotating motion of the rotatable body. This arrangement gives an advantage of virtually eliminating adverse effect of a shift in position where the flexible contact blade makes resilient contact with the rotary contact plate during a depressing manipulation of the cylindrical operating knob, by allowing a fair margin of a dimension in a radial direction of the rotary contact plate, since the shift occurs in this direction only. 
     The push and rotary operating type electronic device has a distinctive structure in that: (a) the cylindrical operating knob is provided with a recess of large diameter at one of end surfaces and a circular hole in a center of the other one of the end surfaces; (b) the rotary contact plate is fixed in an inner periphery of the recess; (c) the cylindrical operating knob is rotatably supported by inserting from an exterior side a supporting axle of a relatively thin diameter fixed to the rotatable body through a small circular hole in a center of the rotary contact plate, and inserting another supporting axle projecting from the rotatable body into the circular hole in the other end surface; (d) the flexible contact blade fixed to the substrate body is held to be in resilient contact with the electric contact surface on an exterior side of the rotary contact plate; and (e) the bulge on the resilient body fixed to the thin supporting axle is held to be in contact resiliently with the ditches and ridges on an interior side surface of the rotary contact plate within the recess. This structure provides an advantage of realizing the push and rotary operating type electronic device of small size that produces a feel of clicks during a rotating manipulation of the cylindrical operating knob, and gives a smoothness in depressing manipulation. 
     Furthermore, the push and rotary operating type electronic device has a structure in that (a) the rotatable body, the thin supporting axle and the resilient body are made of metallic material, and (b) a flexible contact having an electrical continuity to a grounding terminal and fixed to the substrate body is so positioned as to be in contact resiliently with the rotatable body. This structure provides an effect of reliably protecting the equipment from an adverse effect of static electricity generated during manipulation of a peripheral surface of the cylindrical operating knob. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a general perspective view depicting a rotary encoder equipped with a push switch, representing a push and rotary operating type electronic device of a first exemplary embodiment of the present invention; 
     FIG. 2 is a longitudinal sectional view depicting the same rotary encoder equipped with a push switch, as is taken along a vertical plane across a center of a rotary axis; 
     FIG. 3 is an exploded perspective view depicting the same rotary encoder equipped with a push switch; 
     FIG. 4 is a schematic view depicting a portion in vicinity of encoder contacts of the same rotary encoder equipped with a push switch; 
     FIG. 5 is a partially sectioned side view depicting the same rotary encoder equipped with a push switch; 
     FIG. 6 is another partially sectioned side view depicting the same rotary encoder equipped with a push switch wherein a push switch unit is in its actuated position; 
     FIG. 7 is another partially sectioned side view of the same rotary encoder equipped with a push switch depicting first means for buffering a large depressing force applied to a cylindrical operating knob; 
     FIG. 8 is a partially sectioned front view of a rotary encoder equipped with a push switch depicting second means for buffering a large depressing force applied to the cylindrical operating knob in a second exemplary embodiment of the present invention; 
     FIG. 9 is a partially sectioned side view of a rotary encoder equipped with a push switch depicting third means for buffering a large depressing force applied to the cylindrical operating knob in a third exemplary embodiment of the present invention; 
     FIG. 10 is a partially sectioned side view of a rotary encoder equipped with a push switch depicting fourth means for buffering a large depressing force applied to the cylindrical operating knob in a third exemplary embodiment of the present invention; 
     FIG. 11 is a partially sectioned side view depicting a rotary encoder equipped with a push switch, representing a push and rotary operating type electronic device of a fourth exemplary embodiment of the present invention; 
     FIG. 12 is a general perspective view depicting a rotary encoder equipped with a push switch, representing a push and rotary operating type electronic device of the prior art; 
     FIG. 13 is a sectioned side view depicting the same rotary encoder equipped with a push switch; 
     FIG. 14 is a general perspective view depicting a mount board having contact points, representing an essential portion of the same rotary encoder equipped with a push switch; and 
     FIG. 15 is a cross-sectioned partial view depicting a device wherein the same rotary encoder equipped with a push switch is installed. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Exemplary Embodiment 
     FIG. 1 is a general perspective view depicting a rotary encoder equipped with a push switch, representing a push and rotary operating type electronic device of a first exemplary embodiment of the present invention; FIG. 2 is a longitudinal sectional view taken along a vertical plane across a center of a rotary axis; and FIG. 3 is an exploded perspective view depicting the same. 
     As shown in FIG.  1  through FIG. 3, the rotary encoder equipped with a push switch of this exemplary embodiment includes: (a) a substrate body  32  provided with a push switch unit  31  serving as a push-to-operate type component on its upper surface; (b) a rotatable body  33  supported rotatably by the substrate body  32 ; (c) a cylindrical operating knob  34  as an actuator held rotatably on the rotatable body  33 , and (d) a rotary encoder unit  37  serving as a rotary operating type component including flexible contact blades  36 A and  36 B fixed to the substrate body  32  in a manner to make resilient contact against a rotary contact plate  35  held on an end surface of the cylindrical operating knob  34 . 
     The substrate body  32  made of plastic has a shape of flat plate. A pair of stationary contacts  31 A and  31 B is fixed in a circular recess located at one side in generally mid point of it by insertion molding in a manner that they are exposed on an upper surface. Connecting terminals  31 C and  31 D, each having an electrical continuity with their respective stationary contacts  31 A and  31 B, are led out downwardly at one side of the substrate body  32 . 
     The push switch unit  31  is formed by placing a circular dish-like resilient movable contact  31 E over the stationary contacts  31 A, and covering the top of them by a flexible film  31 F. 
     A pair of circular supporting holes  32 A and  32 B are provided facing against each other at both ends of the substrate body  32  at a longitudinal side opposite to the push switch unit  31 . 
     The rotatable body  33  is a square-shaped frame made of metal, and projections  33 A and  33 B on both ends at one side of it are supported rotatably by the pair of circular supporting holes  32 A and  32 B of the substrate body  32 . A hook  32 C extended from the substrate body  32  to connect with a longitudinal side frame  33 C opposite to the supported side limits a position of the rotatable body  33  below an upper bound. 
     A projection  33 E located on a lower surface of a flexible arm  33 D provided near the longitudinal side frame  33 C stays in contact with a top end of the push switch unit  31 , so as to maintain the rotatable body  33  in the upper bound position within its movable limit under normal conditions. 
     The rotatable body  33  actuates the push switch unit  31  when it rotates and moves downward from this ordinary position. 
     The cylindrical operating knob  34  having a peripheral manipulation surface  34 A in a longitudinal width smaller than a span between the pair of circular supporting holes  32 A and  32 B is retained inside of the frame of the rotatable body  33 . The cylindrical operating knob  34  is rotatable about a rotary axis shown as a dashed line in FIG. 3, which is in parallel to a rotational axis of the rotatable body  33  between the two projections  33 A and  33 B. 
     The cylindrical operating knob  34  has the rotary contact plate  35 , which is press-fixed to an inner periphery of a recess  34 B provided in one end surface of it, as shown in FIG.  2 . The cylindrical operating knob  34  is rotatably supported by a thin supporting axle  38 A and another supporting axle  33 H projecting coaxially in a manner to face the thin supporting axle  38 A. That is, the cylindrical operating knob  34  is rotatably supported by the thin supporting axle  38 A projecting from a metal cover plate  38  overlaid on and fixed to a cross side frame  33 F of the rotatable body  33 , and the supporting axle  33 H projecting from another cross side frame  33 G in parallel with the cross side frame  33 F in a manner to face the thin supporting axle  38 A along a coaxial line, that these two supporting axles  38 A and  33 H inserted respectively into a small circular hole  35 A in a center of the rotary contact plate  35  and a circular hole  34 C in a center of the other end surface of the operating knob  34 . 
     The rotary contact plate  35  is provided on its exterior side surface with a center contact portion  39 A serving as a common contact point and a plurality of radial contact points  39 B extending radially outward from the center contact point  39 A at predetermined angular intervals, as shown in FIG.  4 . The two flexible contact blades  36 A and  36 B of contact bars  36 C and  36 D held by insertion molding in a contact board  36 , which is fixed on the substrate body  32 , maintain resilient contacts with this electric contact surface, and connecting terminals  36 E and  36 F respectively in continuity with the contact bars  36 C and  36 D are led downward. The rotary contact plate  35  is provided on its interior side surface with a plurality of radially-oriented ridges and ditches  40  in corresponding angular arrangement with the radial contact portions  39 B. A resilient bulge  41 A on a leaf spring  41  made of resilient metal plate and fixed to a tip end of the thin supporting axle  38 A is made to contact resiliently with plurality of the radially-oriented ridges and ditches  40  within the recess  34 B in the cylindrical operating knob  34 . 
     When the rotary contact plate  35  is turned with the cylindrical operating knob  34 , the flexible contact blades  36 A and  36 B slide resiliently on the center contact portion  39 A and the radial contact portions  39 B, and the resilient bulge  41 A slides resiliently on the radially-oriented ridges and ditches  40  respectively, so as to function as the rotary encoder unit  37  for generating an electric signal (pulse signal) between the connecting terminals  36 E and  36 F, while producing a feeling of clicks. 
     Positions where the flexible contact blades  36 A and  36 B make resilient contact with the exterior side surface of the rotary contact plate  35  are located on or near a line connecting in phantom from a center of the rotary contact plate  35  to a center of the circular supporting holes  32 A and  32 B, i.e. an rotational axis of a rotational motion of the rotatable body  33 , and in between these centers, as shown in FIG.  5 . The flexible contact blade  36 B is so placed that it does not contact with any of the radial contact portions  39 B, but remains in position on an insulated surface area, when the rotary contact plate  35  stays in any rotated position in which the resilient bulge  41 A of the leaf spring  41  in contact with the interior side surface is caught in one of the ditches  40 A among the radially-oriented ridges and ditches  40 . 
     In addition, a grounding contact bar  42  (refer to FIG. 2) is fixed in the contact board  36  by insertion molding in line with the contact bars  36 C and  36 D. A flexible contact blade  42 A of the grounding contact bar  42  makes a resilient contact on the metal cover plate  38 , and a connecting terminal  42 B extending downward is connected to a grounding circuit in the equipment. 
     The rotary encoder equipped with a push switch of the present exemplary embodiment is constructed as above, and it operates in a manner, which will be described next. 
     In FIG.  1  through FIG. 5, when the cylindrical operating knob  34  is turned by applying a force in a tangential direction (the direction of an arrow H shown in FIG.  1  and FIG. 5) on an upper part of the peripheral manipulation surface  34 A, the rotary contact plate  35  mounted to the cylindrical operating knob  34  rotates about the thin supporting axle  38 A. 
     According to the rotation of the rotary contact plate  35  a flexible contact blades  36 A and  36 B fixed to the substrate body  32  slide resiliently over the center contact portion  39 A and radial contact portions  39 B on the exterior side surface of the rotary contact plate  35 , to make and break a circuit, and function as the rotary encoder unit  37 . 
     At the same time, the resilient bulge  41 A of the leaf spring  41  slides resiliently on the plurality of radially-oriented ridges and ditches  40  on the interior side surface of the rotary contact plate  35  to produce a feeling of clicks in coordination with the making and breaking of the circuit. 
     When the cylindrical operating knob  34  stops rotating, the resilient bulge  41 A slips into one of the ditches  40 A among the radially-oriented ridges and ditches  40 , and the flexible contact blade  36 B stops on the insulated surface area separated from the radial contact portions  39 B. 
     Signal from the rotary encoder unit  37  is transferred via the connecting terminals  36 E and  36 F to the circuit in the equipment in which the rotary encoder is used. 
     Incidentally, a depressing force is applied downwardly on the upper part of the cylindrical operating knob  34 , when it is turned. However, a force required to cause the dish-like resilient movable contact  31 E of the push switch unit  31 , with which the flexible arm  33 D of the rotatable body  33  supporting the cylindrical operating knob  34  makes contact, to make an elastic deformation may be designed to be greater than the depressing force so that an erroneous operation of the push switch unit  31  can be avoided during the rotating manipulation of the rotary encoder unit  37 . 
     Furthermore, a location on the peripheral manipulation surface  34 A of the cylindrical operating knob  34 , to which the tangential force is applied, is not necessarily the upper part at the center in a widthwise direction of the peripheral manipulation surface  34 A of the cylindrical operating knob  34 . The cylindrical operating knob  34  can rotate smoothly in the like manner, even if the force is applied to the cylindrical operating knob  34  at any other locations off the center toward either the right side or the left side, and the rotary encoder unit  37  can be operated satisfactorily. Static electricity may be generated by a hand and fingers of an operator making contact with the peripheral manipulation surface  34 A of the cylindrical operating knob  34 . However, the static electricity does not cause an adverse effect to the circuit of the equipment, since it is discharged from the metal rotatable body  33  and the cover plate  38  to a grounding circuit of the equipment via the flexible contact blade  42 A and the connecting terminal  42 B of the grounding contact bar  42 . 
     On the other hand, when a depressing force is applied vertically downward (the direction of the arrow V) to the upper part of the peripheral manipulation surface  34 A of the cylindrical operating knob  34  in order to push down the cylindrical operating knob  34 , as shown in FIG. 6, the rotatable body  33  supporting the cylindrical operating knob  34  makes a rotational movement around the rotational axis across the projections  33 A and  33 B. This motion of the rotatable body  33  causes the projection  33 E on the underside surface of the flexible arm  33 D to push a center portion of the dish-like resilient movable contact  31 E above the stationary contact  31 A downward via the flexible film  31 F of the push switch unit  31  on the substrate body  32 , and thereby forcing the resilient movable contact  31 E to make an elastic deformation. 
     An underside surface at the center of the resilient movable contact  31 E comes into contact with the stationary contact  31 B, so as to close between the stationary contacts  31 A and  31 B. This makes an electrical continuity of the push switch unit  31 , and an electric current is transferred to a circuit in the equipment via the connecting terminals  31 C and  31 D. 
     When the depressing force applied to the cylindrical operating knob  34  is removed thereafter, an elastic restoring force of the resilient movable contact  31 E of the push switch unit  31  pushes back the rotatable body  33  into its original position shown in FIG. 5 via the flexible arm  33 D, and thereby the push switch unit  31  turns into an open mode. 
     The push switch unit  31  functions as a push-on type switch in the case described above. 
     In this exemplary embodiment, a location on the peripheral manipulation surface  34 A of the cylindrical operating knob  34 , to which the depressing force is applied when actuating the push switch unit  31 , is not necessarily the upper part at the center in the widthwise direction of the peripheral manipulation surface  34 A of the cylindrical operating knob  34 . The rotatable body  33  can be moved smoothly to actuate the push switch unit  31 , even if the depressing force is applied to the cylindrical operating knob  34  at any other locations off the center toward either the right side or the left side, since the peripheral manipulation surface  34 A of the cylindrical operating knob  34  has the longitudinal width smaller than the span between the pair of circular supporting holes  32 A and  32 B of the substrate body  32  retaining the rotatable body  33 , as has been described. 
     In addition, the rotary contact plate  35  of the rotary encoder unit  37  does not rotate while actuating the push switch unit  31  with a depressing force applied to the cylindrical operating knob  34 , because the resilient bulge  41 A of the leaf spring  41  stays in one of the ditches  40 A among the radially-oriented ridges and ditches  40  on the interior side surface of it, as described above. 
     The points where the flexible contact blades  36 A and  36 B, i.e. contact points of the rotary encoder unit  37 , contact resiliently on the center contact portion  39 A and the radial contact portions  39 B on the exterior side surface of the rotary contact plate  35  shift slightly, when actuating the push switch unit  31 . However, this does not cause any adverse effect even if the resilient contacting point is shifted slightly, since the flexible contact blade  36 A is in resilient contact with the center contact portion  39 A, i.e. a common contact. A magnitude of the rotational motion at a given point of the rotatable body  33  increases with a distance of that point from a center line drawn in phantom across the two projections  33 A and  33 B, i.e. the rotational axis of the rotatable body  33 . Hence, the magnitude becomes smaller as the distance to the rotational axis becomes shorter. The flexible contact blade  36 B shifts very slightly with a motion of the rotatable body  33 , because it is closest to the rotational axis of the rotatable body  33 . Moreover, since the flexible contact blade  36 B stays on the insulated area without resiliently contacting any of the radial contact portions  39 B, as described above, there is not the slightest chance for the rotary encoder unit  37  to generate an erroneous signal. 
     If an excessively large depressing force is applied vertically downward to the cylindrical operating knob  34 , the flexible arm  33 D of the rotatable body  33  elastically deforms by a predetermined dimension, as shown in FIG. 7, after the push switch unit  31  closes the circuit by elastic deformation of the resilient movable contact  31 E. It is so constructed that a projection  33 I provided on an underside surface of the longitudinal side frame  33 C connecting the flexible arm  33 D consequently strikes on the upper surface of the substrate body  32  in order to stop the depressing force. Therefore, the push switch unit  31  does not receive a depressing force greater than a force required for the elastic deformation of the flexible arm  33 D. The projection  33 E on the underside surface of the flexible arm  33 D may be maintained to be in contact resiliently with the top end of the push switch unit  31  with the flexible arm  33 D kept deformed slightly under the normal condition, so as to prevent the rotatable body  33  from making an abnormal sound due to an angular play in the rotational direction. 
     As described above, the push and rotary operating type electronic device of the present exemplary embodiment is provided with a large cylindrical manipulating surface, yet it can reduce a height dimension of an enclosure of the equipment in which this push and rotary operating type electronic device is housed. In addition, the push-to-operate type component can be manipulated smoothly, since the rotatable body can move around the supporting part at one side of it, during depressing manipulation the cylindrical operating knob. Furthermore, this electronic device has an advantage of providing high contact reliability with low cost, since it contains a small number of resilient contacts and contacting points. 
     Second Exemplary Embodiment 
     With reference to the accompanying figure, a rotary encoder equipped with a push switch will be described hereinafter as a representative of a push and rotary operating type electronic device of a second exemplary embodiment of the present invention. 
     FIG. 8 is a partially sectioned front view of the rotary encoder depicting a second means for preventing a large depressing force from being applied to the push switch unit  31  when the cylindrical operating knob  34  is being depressed downward. The rotary encoder of this exemplary embodiment is provided with an elastic actuator  44  instead of the flexible arm  33 D and the projection  33 E on its underside surface in the foregoing structure of the first exemplary embodiment. The elastic actuator  44  made of rubber or the like material has predetermined dimensions and a predetermined elasticity, and it is press-fitted in a cavity  43 B provided in the center of a underside surface of a longitudinal side frame  43 A located at an opposite side of a rotational axis of a rotatable body  43 . A tip end of the elastic actuator  44  is placed to be in contact elastically with the top end of the push switch unit  31 . A projection  43 C is provided on each side of the elastic actuator  44  at a lower surface of the rotatable body  43 . 
     According to the above configuration, when an excessively large depressing force is applied to the cylindrical operating knob  34 , the elastic actuator  44  is compressed by a predetermined magnitude after the push switch unit  31  closes the circuit (in the case of a push-on type switch), and a projection  43 C provided on each side of the elastic actuator  44  strikes on the upper surface of the substrate body  32  to stop the depressing force. 
     This push and rotary operating type electronic device of the present exemplary embodiment can provide a similar effectiveness while achieving a further reduction in size of the device than the structure of the first exemplary embodiment. 
     Third Exemplary Embodiment 
     Referring now to the accompanying figures, a rotary encoder equipped with a push switch will be described hereinafter as a representative of a push and rotary operating type electronic device of a third exemplary embodiment of the present invention. 
     FIG.  9  and FIG. 10 are partially sectioned side views depicting respectively third and fourth means of buffering a large depressing force applied to the cylindrical operating knob. These rotary encoders equipped with push switch are additionally provided with springs  45  and  46  respectively between their respective substrate bodies  32  and the rotatable bodies  33  for providing biasing forces in a direction to separate them with respect to each other. Further, a gap is provided between the tip end of the projection  33 E on the underside surface of the flexible arm  33 D and the flexible film  31 F which is the top end of the push switch unit  31 , or between the tip end of the elastic actuator  44  and the flexible film  31 F, with the rotatable bodies  33  in an upper bound position within its movable range. 
     The depressing force required to manipulate the cylindrical operating knob  34  of the rotary encoders equipped with push switch can be greater than the force required for the resilient movable contact  31 E of the push switch unit  31  to make a resilient deformation, with the spring  45  or  46 . Moreover, the gap can provide an inactive stroke of the cylindrical operating knob  34 , prior to a start of depressing the resilient movable contact  31 E of the push switch unit  31  in the course of a depressing manipulation. The inactive stroke can reduce the likelihood of actuating the push switch unit  31  in error when, for example, turning the cylindrical operating knob  34 , and prevent an abnormal sound due to the angular play in the rotatable body  33 . 
     Fourth Exemplary Embodiment 
     FIG. 11 is a partially sectioned side view depicting a rotary encoder equipped with a push switch, representing a push and rotary operating type electronic device of a fourth exemplary embodiment of the present invention. A structure of this rotary encoder equipped with a push switch differs from that of the first exemplary embodiment, in which the positions where flexible contact blades  48 A and  48 B make resilient contact with a rotary contact plate  35  of a rotary encoder unit  47  are altered. The structure other than the above aspect is identical to the rotary encoder equipped with a push switch of the first exemplary embodiment. All elements having identical structure as those of the first exemplary embodiment are assigned the same reference numerals, and their description will be omitted. 
     In FIG. 11, the flexible contact blades  48 A and  48 B are so positioned that the positions where they make resilient contact with the rotary contact plate  35  of the rotary encoder unit  47  are on or very close to a line which passes through a center of the rotary contact plate  35  in a direction perpendicular to another line drawn between the center of the rotary contact plate  35  and a rotational axis, i.e. a center of the rotational motion of the rotatable body  33 . The flexible contact blade  48 B is so placed that it does not contact with any of the radial contact portions  39 B, but remains in position on an insulated surface area, when the rotary contact plate  35  stays in any rotated position in which the resilient bulge  41 A of the leaf spring  41  in contact resiliently with the interior side surface is caught in one of the ditches  40 A among the radially-oriented ridges and ditches  40  (not shown in FIG.  11 ), in the same way as in the case of the first exemplary embodiment. 
     In the rotary encoder equipped with a push switch having the foregoing structure, the positions where the flexible contact blades  48 A and  48 B make resilient contact with the center contact portion  39 A and the radial contact portions  39 B on the rotary contact plate  35  shift slightly as the rotatable body  33  makes a rotational movement in the course of a depressing manipulation of the cylindrical operating knob  34  when actuating the push switch unit  31 . However, an adverse effect of this shift can be avoided by allowing a fair margin in a dimension of a radial direction of the individual contacts on the rotary contact plate  35 , i.e. an increase of a radius of the rotary contact plate  35  to a greater dimension than a predetermined value, since the flexible contact blades  48 A and  48 B shift their respective points of resilient contact in a direction of the radius, which is perpendicular to the line drawn in phantom between the center of the rotary contact plate  35  and the rotational axis, or the center of the rotational motion, of the rotatable body  33 . 
     In the first through fourth exemplary embodiments, although what has been described in detail is examples of the rotary encoder in which a push-on type switch is equipped, a push-off type switch may also be used as the push switch unit. 
     Furthermore, although what has been described in detail in the foregoing exemplary embodiments is an example in that the rotary contact plate is mounted on one of the end surfaces of the cylindrical operating knob, one each of the rotary contact plates can be mounted on both of the end surfaces of the cylindrical operating knob. 
     As has been described, the present invention provides an advantageous effect of realizing the push and rotary operating type electronic device that has features including: (a) it has a large cylindrical manipulating surface, yet it can reduce a height dimension of an enclosure of the equipment in which this push and rotary operating type electronic device is housed; (b) the push-to-operate type component can be manipulated smoothly, since the rotatable body can move around the supporting part at one side of it, during depressing manipulation of the cylindrical operating knob; and (c) it provides a push and rotary operating type electronic device with high contact reliability at a low cost, since it contains a small number of resilient contacts and contacting points.