Rotary operation device

A rotary operation device that can prevent misassembly of a rotary operation member and a rotational force transmission member, has a rotary operation member, a rotation detector, and a rotational force transmission member. The rotary operation member has a first gear and the rotational force transmission member has a second gear and a transmission axis. One of the rotary operation member and the rotational force transmission member has a first interference portion that interferes with the other member in a position misaligned from a proper engagement position where the first gear and the second gear are engaged in a proper phase relationship. The other member comprises a second interference member that interferes with the first interference portion in a position misaligned from the proper engagement position and an escape portion that receives the first interference portion in the proper engagement position to allow assembly with the one member.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 of Japanese Application No. 2012-049155, filed on Mar. 6, 2012, which is herein expressly incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rotary operation device used to operate an electronic device mounted in a vehicle.

2. Description of Related Art

A rotary operation device is conventionally known as an operation device mounted in various electronic devices. When being mounted in a vehicle, such as an automobile, for example, such a rotary operation device is used to operate an electronic device in the vehicle, specifically, an air conditioner, a car navigation system, or a car audio system. Related Art 1 discloses such a rotary operation device, which includes a rotary operation member, a rotation detector, and a rotational force transmission member. The rotary operation member is rotated around a specific rotation axis. The rotation detector detects a rotary operation amount of the rotary operation member. The rotational force transmission member transmits a rotational force of the rotary operation member to the rotation detector. The rotary operation member has a first gear on an entire periphery of the rotation axis. The rotational force transmission member has a second gear and a transmission axis. The second gear is engaged with the first gear and is thus rotated in association with rotation of the rotary operation member. The transmission axis rotates integrally with the second gear. The transmission axis, which is reliably positioned to the rotation detector and is coupled therewith, transmits the rotation to the rotation detector. Thus, an output from the rotation detector varies in accordance with the operation amount of the rotary operation member. In other words, the operation position of the rotary operation member and the output from the rotation detector are in a constant relationship with each other in the rotary operation device.

The rotary operation device should be assembled such that the first gear of the rotary operation member and the second gear of the rotational force transmission member are provided in a proper engagement position where the gears are surely engaged in a proper phase relationship. With the gears assembled in the proper engagement position, the rotary operation member is rotated to a predetermined operation position, and then the rotation detector outputs an appropriate signal associated with the operation position or operation amount. However, in a case where the teeth of the first gear and the teeth of the second gear are misaligned from the proper engagement position even at one tooth in assembly, even when the rotary operation member is rotated to the operation position or operation amount, the rotation detector outputs a signal different from the appropriate signal or there is an error in the output signal. For instance, in a case where the rotation detector is of a variable resistance type and the rotary operation member and the rotational force transmission member are assembled in a position misaligned from the proper engagement position, even when the rotary operation member is rotated to the predetermined position, the rotation detector outputs a signal based on a resistance value different from a resistance value that renders the appropriate signal. In a case where the rotation detector is a rotary encoder that outputs pulses and the rotary operation member and the rotational force transmission member are assembled in a position misaligned from the proper engagement position, a pulse signal is likely to be output at an operation amount different from an operation amount of the rotary operation member at which a predetermined pulse signal is output. Specifically, the rotation detector and the rotational force transmission member are reliably positioned and assembled. Thus, when the rotary operation member and the rotational force transmission member are assembled with the first gear and the second gear misaligned from the proper engagement position, the malfunctions above occur.

In this regard, the rotary operation device disclosed in Related Art 1 has a confirmation mark on at least either of the rotary operation member or the rotational force transmission member. This confirmation mark enables confirmation of the first gear and the second gear in the proper engagement position during assembly of the rotary operation member and the rotational force transmission member. This facilitates assembly of the members in the proper engagement position.

However, even when the rotary operation member and the rotation detector are assembled while the confirmation mark is being checked, the rotary operation member and the rotation detector are possibly assembled with the first gear and the second gear in a position misaligned from the proper engagement position. Thus, a concern over misassembly of the members still remains.

SUMMARY OF THE INVENTION

In view of the circumstances above, the present invention provides a rotary operation device that can prevent misassembly of a rotary operation member and a rotational force transmission member.

In view of the circumstances above, the present invention provides a rotary operation device including a rotary operation member rotated around a specific rotation axis; a rotation detector detecting rotary operation of the rotary operation member; and a rotational force transmission member transmitting, to the rotation detector, a rotational force generated in association with the rotary operation of the rotary operation member. The rotary operation member includes a first gear transmitting the rotational force of the rotary operation member to the rotational force transmission member. The rotational force transmission member includes a second gear engaged with the first gear; and a transmission axis linked to the second gear, rotatable around a central axis thereof, and coupled with the rotation detector. One of the rotary operation member and the rotational force transmission member includes a first interference portion provided in a portion displaced in a rotation direction in accordance with rotation thereof and having a shape that interferes with the first interference portion so as to prevent assembly with the other member in a position misaligned from a proper engagement position where the first gear and the second gear are engaged in a proper phase relationship. The other member includes a second interference member and an escape portion, the second interference member being provided in a portion displaced in a rotation direction in accordance with rotation thereof and having a shape that interferes with the first interference portion so as to prevent assembly with the one member in a position where the first gear and the second gear are misaligned from the proper engagement position, the escape portion having a shape that receives the first interference portion when the first gear and the second gear are provided in the proper engagement position so as to prevent interference with the first interference portion and allow assembly with the one member and that prevents interference with the first interference portion when the rotary operation member and the rotational force transmission member are rotated relative to each other in a state where the first gear and the second gear are assembled in the proper engagement position.

The rotary operation device of the present invention can prevent misassembly of the rotary operation member and the rotational force transmission member. Specifically, when the first gear and the second gear are provided in the proper engagement position where the gears are engaged in the proper phase relationship, the first interference portion of the one member is received in the escape portion of the other member and does not interfere with the other member, thus allowing assembly of the members at this position. In contrast, when the first gear and the second gear are provided in a position misaligned from the proper engagement position, the first interference portion interferes with the second interference portion, thus preventing assembly of the members at this position. In addition, the escape portion has a shape that does not interfere with the first interference portion when the rotary operation member and the rotational force transmission member are rotated relative to each other in a state where the first gear and the second gear are assembled in the proper engagement position, thus not affecting operability of the rotary operation member after the members are assembled.

Furthermore, in the present invention, preferably the gear of the one member is rotated in the rotation direction thereof in association with rotation of the gear and includes a rotation surface intersecting a rotation axis direction of the gear. The first interference portion is preferably linked to the rotation surface at a position inward of an outer periphery of the rotation surface. The second interference portion preferably has a shape projecting outward of an outer periphery of the gear of the other member in a radial direction of the gear. The escape portion is preferably positioned adjacent to the second interference portion along a circumferential direction of the other member.

Thus, the first interference portion is linked to the rotation surface intersecting the rotation axis direction of the gear at a position inward of the outer periphery of the rotation surface. Unlike a case where the first interference portion projects outward of the outer periphery of the rotation surface, damage is effectively limited to the first interference portion when an external force is exerted on the first interference portion in the rotation axis direction during assembly of the rotary operation member and the rotational force transmission member.

Furthermore, in the present invention, the first interference portion is preferably a projection projecting from the rotation surface in the rotation axis direction of the gear. The escape portion is preferably a recess recessed inward of an outer periphery of the second interference portion. The recess preferably includes an opposing portion and a pair of widening portions, the opposing portion facing an outer portion of the projection orthogonal to the rotational axis direction of the projection when the first gear and the second gear are provided in the proper engagement position, the pair of widening portions extending from the opposing portion and widening so as to be further apart from each other toward the projection from two ends of the second interference portion in the rotation direction in the opposing portion.

As described above, the present invention provides the rotary operation device that can prevent misassembly of the rotary operation member and the rotational force transmission member.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are described with reference to the drawings.FIGS. 3 and 4(a) to4(d) show only a second interference portion43, a recess43a, a first gear44, a disk52, and a second gear51, which are described later, and exclude other components.FIGS. 5 and 6show only a second interference portion43′, the recess43a, the first gear44, a disk52′, and the second gear51, which are described later, and exclude other components. InFIGS. 3 to 6(a) to6(d), a central opening of an inner40described later is excluded.

First Embodiment

A rotary operation device according to a first embodiment of the present invention is described with reference toFIGS. 1 to 4(d).

With reference toFIGS. 1 and 2, the rotary operation device according to the present embodiment includes a rotary operation member20, a rotation detector72, a rotational force transmission member50, and a holder60. The rotary operation member20is rotated around a specific rotation axis. The rotation detector72detects rotary operation of the rotary operation member20. The rotational force transmission member50transmits a rotational force of the rotary operation member20to the rotation detector72. The holder60holds the rotary operation member20and the rotational force transmission member50. In the description below, a side on which an operator operates in a rotation axis direction, specifically, an end wall32side of a dial30described later is referred to as a front surface side or a front end side; and a side opposite thereto is referred to as a rear surface side or a rear end side. The rotary operation device is accommodated in a casing10in a state where the dial30is exposed to the front surface side.

The casing10has a circular opening11and a display12, the opening11exposing the dial30to the front surface side, the display12indicating an operation position of the dial30. With reference toFIG. 2, the casing10accommodates components other than the dial30of the rotary operation device.

The rotary operation member20has the dial30and the inner40, the dial30being rotated by an operator, the inner40being connected to the dial30so as to be rotated along with the dial30. The dial30and the inner40are provided as separate members in the present embodiment, but may be provided integrally.

The dial30has a tubular holding portion31and an end wall32, the holding portion31being held for rotary operation, the end wall32being provided on the front end side of the holding portion31. A rear end portion of the holding portion31has an engaged portion for connection with the inner40. The engaged portion is connected to the inner40, thus preventing relative rotation of the dial30and the inner40. The end wall32closes the front end side of the holding portion31and is connected to the front end of the holding portion31.

The inner40has an inner tubular portion41, a dial connector42, the second interference portion43, the recess43a, and the first gear44. The inner tubular portion41can be engaged with a hook61a described later. The dial connector42is connected to the dial30. The second interference portion43is provided on an outer peripheral surface of the dial connector42. The recess43a, which serves as an escape portion, is provided in a position circumferentially adjacent to the second interference portion43. The first gear44transmits a rotational force exerted on the rotary operation member20to the rotational force transmission member50. As shown inFIGS. 1 and 2, the inner40has an opening in a central portion thereof through which an inner connector61described later can be inserted.

The dial connector42has a tubular shape slightly larger than the inner tubular portion41and is fitted into the holding portion31. The dial connector42has an engaging portion which is engaged with the engaged portion of the holding portion31.

The second interference portion43projects outward in a radial direction orthogonal to the rotation axis from the outer peripheral surface on the rear end side of the dial connector42. An outer periphery of the second interference portion43has an arcuate shape. The recess43ais recessed inward of the outer periphery of the second interference portion43in the radial direction. Functions of the second interference portion43and the recess43aare described later.

The first gear44is provided in a position different from the position where the second interference portion43is provided in the rotation axis direction. In the present embodiment, the first gear44is positioned closer to the rear surface side than the second interference portion43. Specifically, the first gear44is an external gear having a smaller diameter than that of the second interference portion43.

The rotational force transmission member50is coupled with the rotary operation member20and the rotation detector72so as to transmit the rotational force of the rotary operation member20to the rotation detector72. Specifically, the rotational force transmission member50has the second gear51, a disk52, and a transmission axis53. The second gear51is engaged with the first gear44. The disk52is provided on the front surface side of the second gear51. The transmission axis53is rotated integrally with the second gear51and is coupled with the rotation detector72.

The second gear51is engaged with the first gear44and is thus rotated in association with rotation of the rotary operation member20. In the present embodiment, the second gear51is an external gear having a fewer number of teeth than the first gear44. Specifically, the number of teeth is a quarter of that of the first gear44. Furthermore, the second gear51has a rotation surface51arotated in association with rotation of the second gear51in a rotation direction thereof. The rotation surface51ais provided on the front surface side of the second gear51and intersects the rotation axis direction of the second gear51. In the present embodiment, the rotation surface51ais a plane orthogonal to the axis direction of the transmission axis53.

The disk52is connected to the front surface side of the rotation surface51aand projects from the rotation surface51atoward the front surface side. The disk52is accommodated inside an outer periphery of the rotation surface51a. The disk52has a circular main body and a projection52aprojecting outward from an outer periphery of the main body in a radial direction thereof to serve as a first interference portion. The main body has a radius so as to be in contact with or substantially proximate to the outer periphery of the second interference portion43, as shown inFIGS. 4(c) and4(d). A function of the projection52ais described later along with the second interference portion43and the recess43a. An example is illustrated in the present embodiment in which the disk52has a circular main boy. The main body may be eliminated.

The transmission axis53is rotated in association with the rotation of the second gear51in the rotation direction thereof. The transmission axis53has a long shape in a direction parallel to the rotation axis of the rotary operation member20. The transmission axis53is fitted with the rotation detector72such that the rotation of the transmission axis53is transmitted to the rotation detector72.

The holder60holds the rotary operation member20and the rotational force transmission member50. The holder60holds the rotary operation member20so as to allow the rotary operation member20to rotate relative to the holder60. The holder60holds the rotational force transmission member50so as to allow the rotational force transmission member50to rotate relative to the holder60. The holder60has an inner connector61, a peripheral wall62, and a bottom wall63. The inner connector61can be engaged with the inner tubular portion41of the inner40. The peripheral wall62is provided outward of the inner connector61relative to the rotation axis of the rotary operation member20. The bottom wall63connects a rear end portion of the inner connector61and a rear end portion of the peripheral wall62.

The inner connector61has a hook61aon the front end side and slits61bprovided on both sides of the hook61ain the circumferential direction. The inner connector61has a diameter so as to be fitted in the inner tubular portion41of the inner40. The hook61ais engaged with the front end of the inner tubular portion41when the inner connector61is fitted into the inner tubular portion41from the rear surface side of the inner tubular portion41. In the present embodiment, the inner connector61has a tubular shape and four hooks61aare provided at 90° intervals in the circumferential direction of the inner connector61. The slits61ballow the hook61ato bend in the radial direction.

The peripheral wall62has a rotary operation member enclosure62athat surrounds the rotary operation member20and a rotational force transmission member enclosure62bthat surrounds the rotational force transmission member50. The rotary operation member enclosure62ais provided concentrically to the inner connector61. The rotational force transmission member enclosure62bis connected to the rotary operation member enclosure62aand projects outward in the radial direction orthogonal to the axis direction of the rotary operation member20from the rotary operation member enclosure62a.

The bottom wall63has a plane orthogonal to the rotation axis of the rotary operation member20. The bottom wall63has a rotary operation member mount63aon which the rotary operation member20is mounted and a rotational force transmission member mount63bon which the rotational force transmission member50is mounted. The rotary operation member20is mounted on the rotary operation member mount63asuch that the front surface thereof and the rear surface of the first gear44are opposite to each other. The rotational force transmission member50is mounted on the rotational force transmission member mount63bsuch that the front surface thereof and the rear surface of the second gear51are opposite to each other. With reference toFIG. 2, the rear end portion of the inner40is engaged with a groove in an inner end of the rotary operation member mount63a. Then, the inner40is rotated relative to the holder60while an outer peripheral surface of the rear end portion is slid in contact with an inner peripheral surface of the groove. The rotational force transmission mount63bincludes a transmission axis though-hole63cthrough which the transmission axis53of the rotational force transmission member50can be inserted.

The rotation detector72is mounted on a circuit board71having a predetermined wiring pattern. The circuit board71has a transmission axis through hole71a through which the transmission axis53of the rotational force transmission member50can be inserted to the rear surface side.

The rotation detector72has a rotation member capable of rotating relative to the circuit board71. The rotation of the rotation member switches contact points included in the rotation detector72. The rotation detector72can be of a variable resistance type or a rotary encoder that outputs pulses. The rotation member has a transmission axis fitting hole72ain which the transmission axis53can be fitted. The rotation member is rotated by the rotation of the transmission axis53inserted through the transmission axis fitting hole72a. In other words, the transmission axis fitting hole72acan transmit the rotation of the transmission axis53to the rotation member. Specifically, the transmission axis fitting hole72ahas a shape that matches a cross-sectional shape of the transmission axis53in a direction orthogonal to the rotation axis in the transmission axis53. In the present embodiment, the cross-sectional shape of the transmission axis53and the shape of the transmission axis fitting hole72aare each substantially a D shape. The transmission axis fitting hole72aand the transmission axis through hole71aare aligned in the rotation axis direction of the transmission axis53. The transmission axis53, which is inserted through the transmission axis through hole63c, is inserted through the transmission axis fitting hole72aand the transmission axis through hole71a.

The functions of the second interference portion43, the recess43a, and the projection52aas the first interference portion are described below.

The second interference portion43, the recess43a, and the projection52aallow assembly of the rotary operation member20and the rotational force transmission member50only when the first gear44and the second gear51are provided in a proper engagement position (position shown inFIG. 3) where the gears are engaged in a proper phase relationship, and prevent assembly of the members in a position other than the proper engagement position. Specifically, the projection52aprojects in a direction connecting central axes of the first gear44and the second gear51in the proper engagement position; the recess43ais capable of receiving the projection52awithout interfering with the projection52ain the proper engagement position; the second interference portion43interferes with the projection52awhen the members are attempted to be assembled in a position other than the proper engagement position. Accordingly, with the first gear44and the second gear51in the proper engagement position, the projection52ais received in the recess43aand does not interfere with the second interference portion43, thus allowing assembly of the members at this position, while with the first gear44and the second gear51in a position other than the proper engagement position, the projection52ainterferes with the second interference portion43, thus preventing assembly of the members at this position.

In the present embodiment, the recess43ahas an opposing portion43band a pair of widening portions43c. The opposing portion43bis a plane that faces an outer (right inFIG. 3) portion of the projection52aorthogonal to a rotation axis direction in the projection52awhen the first gear44and the second gear51are provided in the proper engagement position. The widening portions43c, which extend from the opposing portion43b, are widening planes that are further apart from each other toward the projection52afrom two ends of the second interference portion43in the rotation direction in the opposing portion43b. The recess43adoes not have to include the opposing portion43band the pair of widening portions43c. The recess43amay have a shape in which the pair of widening portions43cis directly adjacent to each other without the opposing portion43b, specifically, substantially a V shape from a plan view; or a shape that includes a curved surface shaped into a recess inward in the radial direction from the outer periphery of the second interference portion43.

An assembly process of the rotary operation device is described below. The rotary operation device according to the present embodiment can be assembled from one direction, as described below.

First, the circuit board71is prepared on which the rotation detector72is mounted. Then, the rear end portion of the holder60is brought into contact with the front surface side of the circuit board71. The holder60is fixed to the circuit board71by a fixer (not shown in the drawing) so as not to rotate relative to the circuit board71. At this time, the holder60is fixed to the circuit board71such that the position of the transmission axis through hole63cof the holder60and the positions of the transmission axis fitting hole72aand the transmission axis through hole71aare aligned in a direction parallel to the rotation axis of the transmission axis53.

The rotational force transmission member50is mounted on the rotational force transmission member mount63bsuch that the transmission axis53is inserted through the transmission axis through hole63c, the transmission axis fitting hole72a, and the transmission axis through hole71a. At this time, the transmission axis53is coupled with the rotation detector72while it is reliably positioned to the transmission axis fitting hole72a.

Subsequently, the inner tubular portion41of the inner40is externally fitted to the inner connector61such that the first gear44and the second gear51are provided in the proper engagement position. At this time, when the first gear44and the second gear51are not provided in the proper engagement position, specifically, when the projection52aof the rotational force transmission member50and the recess43aof the inner40are not in a positional relationship aligned in the rotation axis direction, the inner40and the rotational force transmission member50are not allowed to be assembled. When the projection52aand the recess43aare positioned in alignment with the rotation axis direction, specifically, only when a phase relationship is achieved in which the both gears are provided in the proper engagement position, the inner40is allowed to be inserted to the holder60. Once the projection52ais received in the recess43a, the hook61ais engaged with the front end of the inner tubular portion41. The hook61ais pressed to the inner peripheral surface of the inner tubular portion41at the time of insertion and is thus bent inward and displaced. Upon completion of the insertion, the hook61a restores to a neutral position due to its resilience and engages with the front end of the inner tubular portion41. The projection52aas the first interference portion is connected to the rotation surface51ain a position inward of the outer periphery of the rotation surface51a of the second gear51. Different from a case where the projection52aprojects outward of the outer periphery of the rotation surface51a, the projection52ais thus effectively prevented from being damaged even when an external force is exerted on the projection52ain the rotation axis direction due to a contact of the second interference portion43with the projection52aduring assembly of the inner40and the rotational force transmission member50. The inner40may be assembled to the holder60in a state of being assembled with the rotational force transmission member50.

Lastly, the dial30is externally fitted to the inner40to integrate the both components.

Operations of the rotary operation device according to the present embodiment is described below.

Rotating the dial30by holding the holding portion31of the dial30rotates the inner40concurrently with the dial30. Thus, rotating the dial30rotates the rotational force transmission member50, which has the second gear51engaged with the first gear44of the inner40. Then, the rotation of the rotational force transmission member50is transmitted through the transmission axis53to the rotation detector72, from which a predetermined signal is output.

Behaviors of the rotary operation member20and the rotational force transmission member50are described with reference toFIGS. 4(a) to4(c).FIGS. 4(a) to4(c) each illustrate a state where the rotary operation member20is gradually rotated from a state where the rotary operation member20and the rotational force transmission member50are provided in the proper engagement position. Specifically,FIG. 4(a) illustrates a state where the both members are in the proper engagement position;FIG. 4(b) illustrates a state where the rotary operation member20is rotated by 6° from the state ofFIG. 4(a);FIG. 4(c) illustrates a state where the rotary operation member20is rotated by 15° from the state ofFIG. 4(a);FIG. 4(d) illustrates a state where the rotary operation member20is rotated by 21° from the state ofFIG. 4(a). As illustrated, the both members do not interfere with each other in the proper engagement position or during relative rotation.

In the present embodiment, whether the rotary operation member20is rotated in a forward or reverse direction from the state ofFIG. 4(a), the projection52ainterferes with the second interference portion43immediately before the rotation angle reaches 90°. Specifically, the rotary operation member20of the present embodiment is designed such that the rotatable angle is less than 180°. In such a configuration in which the rotation angle of the rotary operation member20is limited, a variable resistance type is preferred for the rotation detector72. The rotary operation device is applied to temperature setting of an air conditioner or volume control of a car audio system. Even in such a case, however, a rotary encoder can be used as the rotation detector72.

As described above, the rotary operation device of the present embodiment can prevent misassembly of the rotary operation member20and the rotational force transmission member50. Specifically, when the first gear44and the second gear51are provided in the proper engagement position, the projection52ais received in the recess43aand thus the projection52aand the second interference portion43do not interfere with each other, allowing assembly of the members at this position. In contrast, when the first gear44and the second gear51are provided in a position other than the proper engagement position, the projection52ainterferes with the second interference portion43, thus preventing assembly of the members at this position. This prevents a defective product with misassembled members from being transferred to the next process in a manufacturing process or from going on sale.

Second Embodiment

A rotary operation device according to a second embodiment of the present invention is described below with reference toFIGS. 5 and 6(a) to6(d). In the second embodiment, descriptions are included only on portions different from the first embodiment; descriptions are omitted for structures, functions, and effects same as those in the first embodiment.

There is a case where the rotary operation device of the present invention is allowed to have a plurality of proper engagement positions depending on an apparatus in which the device is mounted. An example is a case where a rotary encoder that outputs pulses is used as the rotation detector72and the rotary operation member20is rotatable 360°. In this case, a plurality of recesses43aassociated with pulse intervals are provided to provide a plurality of proper engagement positions. The rotary operation device of the second embodiment is different from the rotary operation device of the first embodiment in that a plurality of second interference portions43′, recesses43a, and projections52ais provided, specifically, a plurality of proper engagement positions exist.

The inner40according to the present embodiment has a plurality of second interference portions43′ on an outer peripheral surface of a dial connector42and a plurality of recesses43aprovided between the second interference portions43′. Specifically, eight second interference portions43′ and eight recesses43aare provided at 45° intervals in a circumferential direction of the dial connector42. A disk52′ has a circular main body and a plurality of projections52aon an outer periphery of the main body. Specifically, two projections52aare provided at 180° intervals along the outer peripheral surface of the main body. Thus, the rotary operation device of the present embodiment has a plurality of proper engagement positions, specifically, eight positions for each projection52a. The number of teeth of the first gear44and the number of teeth of the second gear51are identical to those in the first embodiment.

An assembly process of the rotary operation device of the present embodiment is described below.

The circuit board71is prepared on which the rotation detector72is mounted. A process of fixing the holder60to the circuit board71and a process of coupling the rotational force transmission member50with the rotation detector72are the same as those in the first embodiment.

Thereafter, the inner40is assembled to the holder60. Unlike the first embodiment, assembly of the components is allowed at this time, provided any of the recesses43aand any of the projections52aare in a positional relationship aligned in the rotation axis direction.

Subsequently, behaviors of the rotary operation member20and the rotational force transmission member50when the rotary operation member20of the present embodiment is rotated are described with reference toFIGS. 6(a) to6(d).FIGS. 6(a) to6(d) each illustrate a state where the rotary operation member20is gradually rotated from a state where the rotary operation member20and the rotational force transmission member50are provided in the proper engagement position. Specifically,FIG. 6(a) illustrates a state where the both members are in the proper engagement position;FIG. 6(b) illustrates a state where the rotary operation member20is rotated by 15° from the state ofFIG. 6(a);FIG. 6(c) illustrates a state where the rotary operation member20is rotated by 30° from the state ofFIG. 6(a);FIG. 6(d) illustrates a state where the rotary operation member20is rotated by 45° from the state ofFIG. 6(a). As illustrated, the both members do not interfere with each other in the proper engagement position or during relative rotation. Every time the rotary operation member20is rotated by 45°, the projection52ais received in the recess43a. In the present embodiment, whether the rotary operation member20is rotated in a forward or reverse direction from the state ofFIG. 6(a), the rotary operation member20is rotatable 360°.

In a configuration in which the rotation angle of the rotary operation member20is not limited as described above, a rotary encoder that outputs pulses is preferred for the rotation detector72. The rotary operation device is applied to indication selection of a car navigation system. Even in such a case, however, a variable resistance type can be used as the rotation detector72.

In use of a rotary encoder for the rotation detector72, the rotation detector72generates pulses in accordance with a rotary operation amount of the rotary operation member20. The number of teeth of the both gears and the angle between the recesses43aare defined in accordance with pulse intervals. Thus, even when the members are assembled such that the projection52ais positioned in any of the plurality of recesses43a, the rotation detector72generates a pulse when the rotary operation member20is operated for a predetermined rotary operation amount from the assembled position. In other words, a plurality of proper engagement positions can be provided by defining the both gears and the recesses43aas described above.

In addition, the rotary operation device preferably has a mechanism (commonly referred to as a click mechanism) to hold an operation position of the rotary operation member20. With a rotary encoder used for the rotation detector72, the mechanism holds an operation position of the rotary operation member20at a position where a point of pulse generation is surpassed. With a variable resistance type used for the rotation detector72, a threshold is set such that a predetermined output is provided above a predetermined resistance value and a holding position is defined such that an operation position of the rotary operation member20is held at a position where the threshold is surpassed. Thus, every time an operator feels a click by rotating the rotary operation member20, the output from the rotation detector72is switched.

As described above, the rotary operation device of the second embodiment can also prevent misassembly of the rotary operation member20and the rotational force transmission member50. Specifically, when the first gear44and the second gear51are provided in one of the plurality of proper engagement positions, the projection52ais received in the recess43aand thus the projection52aand the second interference portion43do not interfere with each other, allowing assembly of the members at this position. In contrast, when the first gear44and the second gear51are provided in a position other than any of the proper engagement positions, the projection52ainterferes with the second interference portion43, thus preventing assembly of the members at this position.

The embodiments disclosed herein are provided for exemplary purposes in all aspects and should not be construed as limitations. The scope of the present invention is recited in the scope of the patent claims, not in the descriptions of the embodiments above. Furthermore, equivalents of the scope of the patent claims and all modifications within the scope are included.

For example, the rotary operation member20has the second interference portion43,43′ and the recess43awhile the rotational force transmission member50has the projection52aas the first interference portion in the present embodiments. However, they may be provided in a reverse manner. Specifically, the rotary operation member20may have a projection and the rotational force transmission member50may have a second interference portion and a recess. In this case, the projection may have a shape projecting outward of the outer shape of the first gear44in the radial direction or a shape positioned inward in the radial direction. The second interference portion and the recess may be positioned inward of the outer shape of the second gear51in the radial direction or a shape positioned outward in the radial direction.

In the embodiments above, the second interference portion43,43′ and the recess43aare provided on the front surface of the first gear44and the projection52ais provided on the front surface of the second gear51. However, they may all be provided on the rear surfaces of the gears.

Furthermore, the second gear51is in external contact with the first gear44in the embodiments above. However, the first gear may be an internal gear instead of an external gear and the second gear51may be disposed so as to be in internal contact with the first gear44.

Furthermore, the rotation surface51aof the rotational force transmission member50is a plane orthogonal to the axis direction of the transmission axis53in the embodiments above. The rotation surface51a may be a curved surface bulging from the outer periphery of the second gear51toward the center thereof.