Are push buttons switches?

Push Button Switch

A rotor on which a moving contact is attached is received and rotatably held in a body, and a knob is received and held in the body side by side with the rotor and is movable. A plurality of first and second teeth are circumferentially staggered with each other on an outer perimeter surface of the rotor near one end and near the other end, respectively, in the direction of the axis of the rotor to project from the surface. An inclined surface is formed in each of the first and second teeth. A projecting part is formed on the knob to project toward the rotor. In response to a depression of the knob, the projecting part pushes the inclined surface of the second teeth to rotate the rotor and, in response to a return of the knob, pushes the inclined surface of the first teeth to rotate the rotor.

The invention provides a push-button switch including: a star wheel which is rotated by a constant angular step in one direction by a depression of a push button that automatically returns; an indenter which is pressed against the outer periphery of the star wheel by a spring; a contact  which is attached so as to corotate with the star wheel, and which serves as a movable contact; and terminals with which the contact is contacted in accordance with a rotation angle, and which serve as stationary contacts. A small projection  having a rounded tip end is disposed in each of ridge portions of the star wheel. Even when the slope of each ridge portion does not have a large inclination angle, the star wheel is prevented from being stopped at a position where the ridge portion is opposed to the indenter.

Self-locking push button switch operating device

Self-locking switch is a common push button switch. When the switch button is pressed for the first time, the switch is turned on and maintained, that is, self-locking, and when the switch button is pressed for the second time, the switch is turned off, and the switch button pops up at the same time. This kind of switch was used in early TVs and monitors that were directly and completely powered off.

The only difference between the lighted self-locking switch and the ordinary self-locking switch is that the lighted switch makes full use of the space in its button to place a small indicator light bulb or LED, one end of which is connected to the zero line, and the other end is generally connected through a drop. The piezoresistor is connected in parallel with the normally open contact of the switch. When the switch is closed, the device operates and also provides power for the indicator light.

1. The circuit is powered on and the air switch QF is turned on → the power indicator EL is on.

2. During the starting process, press the start button SB2 → KM coil is energized → → KM auxiliary moving contact is closed → → KM main contact is closed → → motor M starts and runs continuously. When SB2 is released, although it returns to the disconnected position , but the KM coil remains energized due to the KM's auxiliary moving contact (which has been closed) in parallel with it.

This function of using the moving contact of the contactor itself to keep the contactor coil energized is called self-locking or self-protection, and the moving contact is called a self-locking (or self-protecting) contact. It is because of the function of the self-locking contact that the motor can still continue to run when the SB2 is released, instead of jogging.

3. Stop process → KM self-locking contact is disconnected → press stop button SB1 → KM coil is de-energized → → KM main contact is disconnected → → motor M stops rotating when SB1 is released, although its normally closed contact recovers for the closed position.

However, because the self-locking contact of the contactor KM has been disconnected at the moment when the coil is de-energized, the self-locking is released (the normally open contact of SB2 has also been disconnected), so the coil of the contactor KM cannot be energized. When the contacts are disconnected, the motor M will not turn any more.