Recently, electronic devices such as the ones for video, audio, and air-conditioning applications have been increasingly sophisticated. Thus, switching devices and remote control transmitters for operating them have been also required to provide diverse and highly-accurate operations.
The conventional switching devices as described above will be described with reference to FIG. 4.
FIG. 4 is a perspective view illustrating a conventional switching device. In FIG. 4, a plurality of wiring patterns (not shown) are formed on upper and lower faces of wiring board 1. Operation body 2 has a disk-like shape and is attached to wiring board 1 so as to be rotatable at the upper face of wiring board 1. At an outer circumference of operation body 2, a plurality of cam units 3 that protrude outwardly are formed with a predetermined interval therebetween.
Furthermore, lever 5 protrudes from switch 4 so that lever 5 can rock relative to insulating resin case 6. Switch 4 is provided so that, by rocking lever 5 to the left and right, a movable terminal (not shown) stored in case 6 is abutted with or separated from a plurality of fixed terminals (not shown) to allow an electronic signal caused by the abutment and separation to be outputted from a terminal unit.
It is noted that switch 4 is a so-called neutral return type switch in which, when an operation force is cancelled after lever 5 is operated by being rocked to the left or right, switch 4 automatically returns to an original neutral position by a spring attached in case 6 (not shown) for example.
Furthermore, switch 4 is provided at the outer circumference of operation body 2 at the upper face of wiring board 1 so that lever 5 is engaged with cam unit 3 of operation body 2. The terminal unit of switch 4 is connected, by being soldered to a predetermined wiring pattern, to a control apparatus (not shown) provided by an electronic component (e.g., microcomputer).
The switching device having the structure as described above is attached to an electronic device or a remote control transmitter with operation body 2 protruding from an operation unit of the device. Then, a wiring pattern of wiring board 1 is electrically connected to an electronic circuit of the device via a connector or the like.
When operation body 2 is rotated and operated in a clockwise or counterclockwise direction in the above structure, lower parts of cam units 3A, 3B, and 3C or the like provided at the outer circumference of operation body 2 are abutted with lever 5 of switch 4 in accordance with the rotation of operation body 2 to cause oscillation of lever 5 to the left or right, thereby providing an electrical contact or separation between a movable terminal and a fixed terminal.
When operation body 2 is rotated through a large angle in the above operation (e.g., when operation body 2 is rotated through a large angle in a clockwise direction), lever 5 of switch 4 is first pressed by cam unit 3A and is rocked to the left. Thereafter, switch 4 automatically returns to its original neutral position. Then, switch 4 is again pressed by cam unit 3C and is rocked to the left. Thus, an electrical contact or separation of switch 4 is performed two times.
An electronic signal caused by this electrical contact or separation is outputted from a plurality of terminal units to the control apparatus. The control apparatus detects a rotational direction and a rotation angle of operation body 2 based on how many times lever 5 is operated by being rocked to the left or right and how many electrical contacts or separations switch 4 has undergone, thereby detecting an operation position of operation body 2. Thus, the conventional switching device has been structured so that sound volume or temperature of a television, audio equipment, or an air conditioner can be increased or decreased or a channel can be selected in accordance with the rotation of rotating operation body 2.
Known information related to the invention of this application includes, for example, that disclosed in Japanese Patent Unexamined Publication No. 2005-32450.
However, in the above conventional switching device, the rotational direction and the rotation angle of operation body 2 are detected by using cam units 3A and 3B provided at the outer circumference of operation body 2 that is operated by being rotated to rock switch 4. Lever 5 of switch 4 is provided between cam units 3A and 3B. An interval between the respective cam units cannot be equal to or smaller than the width of lever 5. For example, when a plurality of cam units 3 outwardly protruding from the outer circumference are arranged with 30 degrees thereamong, the rotation angle of operation body 2 can be detected only with an interval of 30 degrees. Due to this reason, it has been difficult to finely detect an operation position of operation body 2.