JPS5960886A - Method of controlling phase in dim of discharge lamp - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phase control method for dimming a discharge lamp.

In the control system for lighting using discharge lamps,
Illumination has been adjusted by changing the phase angle or firing angle of the thyristor. In other words, dimming control is performed by determining the firing angle with the zero cross point as a reference during the half cycle period of the sine waveform from the power supply.
If the cross point cannot be detected accurately due to distortion of the sine waveform from the power supply or noise components, the reference point for determining the firing angle will fluctuate, causing flickering in the illumination of the discharge lamp.

An object of the present invention is to eliminate inaccurate detection of zero-crossing points due to distortion of the sinusoidal waveform from the power source or noise superimposition, and ultimately to eliminate flickering in the illumination of a discharge lamp.

That is, in the present invention, the sine waveform from the power source is converted into a waveform, noise components are removed from the sine wave, and the waveform is shaped to eliminate the possibility of detecting a point other than the zero-crossing point as the zero-crossing point. Next, the phase shift amount θ of the sine wave by the P-wave circuit
In order to compensate for Determine the firing angle of the sine waveform from . In this case, the zero and cross points of the shaped waveform may be detected, and this detection time may be delayed by a phase corresponding to nπ-θ to determine the zero and cross points of the sine waveform from the power supply, or the shaped waveform may be delayed by a phase corresponding to nπ-θ, and then the zero-crossing point of the delayed sine waveform is detected and used as the zero-crossing point of the sine waveform from the power supply.

The invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of a phase control circuit for implementing the method of the present invention. A sine waveform from a power source is applied to input terminal 2. Connected to the input terminal 2 is a CRP wave circuit 4, the output of this Oki wave circuit 4 is connected to a zero cross detection circuit B, and the output of this detection circuit B is connected to a delay circuit 8. 10 is an output terminal of the phase control circuit.

FIG. 2 shows waveforms appearing at the input and output terminals of each component circuit of the phase control circuit.

Figure 2 (al is the waveform from the power supply, which contains distortion or noise components. The waveform from this power supply is applied to the Oki wave generator 4 and is shaped into a sine wave as shown in Figure 2 (bl). However, the phase of this shaped sine wave is delayed by θ and υ from the waveform from the power supply.

This shaped sine wave is then applied to zero-crossing detection circuit B. An example of a zero-crossing detection circuit is one in which the sine wave output from an Oki wave device is made into a rectangular wave, and then differentiated to generate a detection pulse at the zero-crossing point. This zero-crossing detection pulse is shown in FIG. 2 (cl). Naturally, this zero-crossing detection pulse is delayed in phase by θ from the zero-crossing point of the sine wave from the power supply.

This zero cross detection pulse is applied to the delay circuit 8,
It is delayed by nπ-θ (n is an integer) to coincide with the zero crossing point of the sine wave from the power supply.

Figure 2 (d) shows the case where the detection pulse is delayed by π-θ (n = 1), and the detection pulse is at 14 zero-crossing points (see the x mark in Figure 2 (a)) from the positive to the negative of the sine wave from the power supply. match.

Figure 2 (d') shows the case where the detection pulse is delayed by 2π-θ (n = 2), and the detected pulse is the zero-crossing point where the sine wave from the power supply goes from negative to positive (see the 0 mark in Figure 2 (a)). ) matches. In either case, the firing angle of the sine wave from the power source can be determined based on this detection pulse.

As described above, according to the present invention, since the ignition angle is accurately determined, instantaneous changes in control power are eliminated, thereby completely eliminating flickering during dimming of the discharge lamp.

[Brief explanation of the drawing]

FIG. 1 shows a phase control circuit for implementing the method of the invention. FIG. 2 shows waveforms at the input and output terminals of each component circuit of the phase control circuit shown in FIG. That is, Fig. 2a shows the sine wave from the power supply, Fig. 2b shows the output waveform of the p-wave circuit, Fig. 2c shows the zero-cross detection pulse, and Figs. 2d and 2d' respectively (π-θ). , (2π-θ). 2... Input terminal of phase control circuit, 4... P-wave circuit,
6... Zero cross detection circuit, 8... Delay circuit, 1
0: Output terminal of the phase control circuit. Patent applicant: Toshiba Electric Materials Co., Ltd. Agent: Patent Attorney Tatsuo Ito; Agent: Patent Attorney: Tetsuya Ito. (Procedures, Amendments, Writing Method) February 23, 1981 Kazuo Wakasugi, Commissioner of the Patent Office1, Indication of the case, Patent Application No. 169488 of 1982, Title of the invention: Phase control method in dimming of discharge lamps 3 , Relationship with the case of the person making the amendment Patent applicant address: 1-43 Shibaura-chome, Minato-ku, Tokyo Name (37
5) Toshiba Electric Materials Corporation Representative Dairoku Sato 4, Agent 105 Address Toranomon Electric Building, 2-8-1 Toranomon, Minato-ku, Tokyo Telephone (501) 9370 February 2, 1982 (Showa 5)
8.2.22 Dispatch) 7. In the subject of the amendment, "4. Brief explanation of drawings" 8. In the description of the contents of the amendment, page 5, line 7, ``i.e.,'' on the same page. 11
The line ``detection pulse'' is shown. Delete up to ″.

Claims (1)

[Claims] The sine waveform from the power supply is shaped into a p-wave, and the point at which the phase is shifted by nπ-θ (n is an integer) from the zero-crossing point of the sine waveform whose phase is shifted by θ due to the p-wave is determined, and from this point on, the sine waveform from the power supply is shifted by θ. 1. A phase control method for dimming a discharge lamp, characterized in that the discharge lamp is dimmed by determining the firing angle of a sine waveform.