Microprocessor based touch dimmer system to control the brightness of one or more electric lamps using single or multi-key devices

摘要

A key touch dimmer includes a switching device through which AC line current is passed to brighten a lamp in response to a control signal generated by a microprocessor. The microprocessor receives an input indicative of the zero crossing points of the AC line current and synchronizes this input with its own internal clock circuitry to generate a firing signal for the switching device at the correct phase angle in the next half cycle of the AC line current. The dimmer has memory capability whereby the lamp, when turned back on, will brighten to a preset level. This brightening is accomplished in a gradual manner. Likewise, a turned off lamp will fade to zero brightness, with the dimmer retaining the preset brightness level. The microprocessor shuts down quickly in the event of a power outage to preserve memory. An optional display includes a plurality of LEDs for indicating light level. Other options include providing the dimmer with several keys, each of which can be adjusted to a respective preset level.