Two-wire dimmer switch

Abstract

A two-line dimmer switch provided with: a primary open-close circuit (10) having a triac (11) as a primary switch element; a frequency-detecting circuit (17) for detecting the frequency of an AC source (2); an auxiliary open-close circuit (18) for directing load current when the primary switch element is not conducting, using a thyristor as an auxiliary switch element; a dimmer-setting circuit (4) operated by the user; and a control circuit (16) for detecting the frequency of the AC source (2) on the basis of a detection signal from the frequency-detection circuit (17) and estimating a voltage zero cross point, starting output of a drive signal for causing the auxiliary open-close circuit (18) to conduct at a first timing, and stopping output of the drive signal at a second timing before a predetermined time in relation to the next estimated voltage zero cross point; wherein when the load current value is small and the primary open-close circuit (10) is not conducting, the load current is continued on the auxiliary open-close circuit (18). The brightness of the LED bulb is thereby stabilized and flickering and shimmering are minimized, even when the LED bulb is connected as the lighting load.

Description

technical field [0001] The invention relates to a two-wire dimmer switch for adjusting the brightness of a lighting load. Background technique [0002] Conventionally, for the purpose of dimming an incandescent light bulb, a dimming switch using a semiconductor switching element such as a triac has been put into practical use. Figure 8 A basic circuit configuration of a two-wire dimmer switch 50 using a triac 51 is shown (first conventional example). The two-wire dimmer switch 50 is connected in series with the AC power source 2 and the lighting load (incandescent bulb) 3 . The two-wire dimmer switch 50 includes: a triac 51, a diac (trigger diode) 52 connected to the gate electrode of the triac 51 for outputting a gate drive signal, A variable resistor 53 , a fixed resistor 54 , a capacitor 55 , a filter element 56 , and the like are connected to an operating member operated by a user. [0003] In the two-wire dimmer switch 50, when the switch 57 is turned on, the capacit...

AI Technical Summary

Problems solved by technology

However, since a current of several mA to tens of mA flows through the phototriac 63, it consumes a lot of power in order to maintain long-term conduction.

In particular, since the LED light bulb is essentially the above-mentioned electronic circuit itself, and consumes little power, if the side of the two-wire dimmer switch 60 consumes a lot of power, it may fall into an uncontrollable situation.

Images