The present invention relates to a miniature switch and particularly to the structure of a multi-direction switch.
Multi-direction switch is one of input devices adopted for use on small electronic devices such as personal digital assistant (PDA) or mobile communication devices. A conventional multi-direction switch provides input commands or instructions that include horizontal xe2x80x9cdirection instructionxe2x80x9d (such as X and Y axes and right up, right down, left up and left down) and a single xe2x80x9cbutton key instructionxe2x80x9d (such as the instruction generated when the multi-direction switch is depressed). By means of this multi-direction switch, the cursor of a small electronic device may be controlled or operation of functional items may be executed.
Refer to FIGS. 1A, 1B and 1C for a conventional multi-direction switch. As shown in FIG. 1A, it has a base dock 10 which has first to fourth electrodes 101-104 located respectively at four corners. There is a central electrode 105 in the center surrounding by a common electrode 106 (generally a common ground electrode). The first to fourth electrodes 101-104 have respectively a leg 101a-104a exposed outside the periphery of the base dock 10 to connect a circuit (such as a circuit on a printed circuit board). The central electrode 105 and the common electrode 106 connect respectively to the circuit through legs 105a and 106a that also are exposed outside the base dock 10. The main operation element of the multi-direction switch is a joystick 11. It has four metal contact legs 110 extending horizontally from the periphery thereof. By moving the joystick 11, the four metal legs 110 may be respectively in contact with the first to fourth electrodes 101-104. The joystick 11 has a bottom end 111 in the center above two overlapped and elastic metal blades 121 and 122 in normal conditions. The metal blade 122 is located at the lower side to be in contact with the common electrode 106 in the normal conditions (also referring to FIG. 1C).
When the joystick 11 is depressed vertically, the two elastic metal blades 121 and 122 are deformed to enable the center point of the lower metal blade 122 in contact with the central electrode 105 so that the central electrode 105 and the common electrode 106 are connected and become conductive through the elastic metal blade 122 to generate a button key instruction. By the same token, when the joystick 11 is moved in the horizontal direction, the metal contact leg 110 in the corresponding direction will be moved to contact any one or more of the first to fourth electrodes 101-104 in the corresponding direction. Through the contact of the first to fourth electrodes 101-104 and the metal contact leg 110, the metal contact leg 110 and the elastic metal blades 121 and 122 that in contact with the bottom end 111 of the joystick 11 in normal conditions, and the common electrode 106 may form electric connection. And through signal triggering conditions of the first to fourth electrodes 101-104, a xe2x80x9cdirectional instructionxe2x80x9d of the joystick 11 may be determined.
The maximum compression displacement of the joystick 11 of such a multi-direction switch is limited by the deformation of the elastic metal blades 121 and 122 (about 0.15 mm). The oscillation amplitude of the joystick 11 at two sides of the axial direction is also restricted in a smaller range. As a result, it causes inconvenience during user operation. Moreover, as the metal contact leg 110 is extended horizontally, when the joystick 11 is moved, in order to ensure that the metal contact leg 110 to connect any one or more of the first to fourth electrodes 101-104, the locations of the first to fourth electrodes 101-104 have to be raised to an elevation close to the metal contact leg 110 (as shown in FIG. 1B). Such a design shrinks the vertical distance between the metal contact leg 110 and the first to fourth electrodes 101-104 and is prone to cause erroneous movement. For instance, when the joystick 11 is depressed, a small shaking of the joystick 11 could cause the metal contact leg 110 to mistakenly touch the first to fourth electrodes 101-104 and result in erroneous movement and generate a wrong directional instruction. And the small dimension and gap also make fabrication and assembly difficult.
Therefore the primary object of the present invention is to provide a multi-direction switch that is less likely to generate erroneous movements.
The present invention mainly has redesigned the metal contact legs of the joystick and the corresponding electrode elements to achieve the object mentioned above. The invention has lowered the location of the electrode elements and changed the shape of the metal contact legs to increase the interval of the metal contact legs and the electrode elements. Therefore it can prevent the metal contact legs from mistakenly connecting to the electrode elements when the joystick is depressed. The oscillation amplitude of the joystick during operation increases and operational maneuverability improves.
Furthermore, the design of the invention also reduces the difficulty of fabrication and assembly.
The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.