Light dimmer, light dimming system and light dimming method

The invention provides a light dimmer. The light dimmer is connected between an alternating-current power supply and a light source driver in series and comprises a first branch and a second branch which are connected in parallel, wherein the first branch comprises a first switch, and the second branch comprises a first one-way rectifier; and when the light dimmer is in a light dimming state, the first switch is disconnected, and the light dimmer outputs a first half-wave signal. Thus, when the first switch is disconnected, the light dimmer is in the light dimming state, the first one-way rectifier conducts an alternating-current signal into the half-wave signal in a one-way manner, so that the light dimmer capable of outputting a light dimming signal in the half-wave form can be realized, and the light source driver performs light dimming according to the light dimming signal. In addition, the devices used by the light dimmer are the switches and the one-way rectifiers, so that even though the rear-stage light driver is a capacitive load, the influence on the accuracy of the light dimming signal emitted to the light dimmer also can not be caused, and an impedance matching circuit does not need to be added. The invention also provides a light dimming system and a light dimming method.