| 摘要 |
A pushbutton tuner includes a plurality of pushbutton actuators each effective to achieve a tuning to a desired preset frequency. Each pushbutton actuator includes a slide plate carried by a support plate so as to be movable between operative and inoperative positions, a lockable control plate pivotally mounted on the slide plate, a pair of upright pins fixedly mounted on the control plate, and a pair of cam members having their one end pivotally mounted on the support plate so that one of the upright pins engages one of the cam members as the slide plate moves to its operative position. A pair of movable plates are carried by the support plate so as to be movable across the slide plates. One of the movable plates is pivotally connected with the other end of one of the cam members while the other movable plate is pivotally connected with the other end of the other cam member. The pair of movable plates are interconnected by a link member which causes one of the movable plates to move in the opposite direction whenever the other movable plate moves in one direction in response to engagement of one upright pin with one of the cam members to cause angular movement thereof. When the other movable plate moves in the opposite direction from the movement of the one movable plate, the other cam member angularly moves in the opposite direction from that of the one cam member until it engages the other upright pin. When both upright pins engage the cam members, the cam members cease to rotate and a component of force acts at the points of engagement between the pins and the cam members in a direction to effectively prevent further rotation of the cam members. The position of the movable plates when further rotation of the cam members is prevented corresponds to the preset frequency.
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