JP2796286B2 - Discharge lamp lighting device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for lighting a discharge lamp by an electronic circuit, and more particularly to a discharge lamp lighting device suitable for dimming the discharge lamp. [Prior Art] A device described in Japanese Patent Application Laid-Open No. 60-47398 is an example of a discharge lamp lighting device that uses a capacitor as an impedance element and opens and closes a switch to supply an alternating current to the discharge lamp. . This lighting device is operated by opening and closing a switch to supply an alternating current to a discharge lamp via a capacitor to light the lamp. Since this lighting device does not include an inductance element, it can be reduced in size, weight, and cost, but does not consider light control. [Problems to be Solved by the Invention] In the above-described conventional technology, a dimming method is not specified. In addition, in such a device, in order to generally increase the luminous efficiency of the discharge lamp, after rectifying an AC power supply as a power supply,
A DC power supply smoothed using a smoothing capacitor is used.
Therefore, even if it is connected to a semiconductor type phase control dimmer and the flow angle is controlled, it does not greatly affect the output voltage of the smoothing circuit, so that the dimming effect cannot be expected much. The object of the present invention, without the disadvantages of the prior art described above,
An object of the present invention is to provide a small, lightweight, and inexpensive discharge lamp lighting device. [Means for Solving the Problems] The above-described object is to provide a dimming voltage waveform applied to an input purpose, for example, when an output of a semiconductor type phase control type dimmer is connected to a power input terminal. The time from when the applied voltage waveform crosses a predetermined voltage level until it crosses again is measured, and according to the value obtained from the measurement,
This can be achieved by controlling the opening and closing time of a switch for supplying an alternating current to the discharge lamp through a capacitor. [Operation] That is, the control phase angle received by the phase control dimmer is measured from the voltage waveform of the AC input power supply before rectification and smoothing, and the switch opening / closing time, for example, the duty is determined according to the measured result. Control. Therefore, even when the output voltage of the smoothing circuit does not change greatly due to the operation of the phase control dimmer as described above, by changing the duty of the switch, one cycle of opening and closing the switch can be achieved. Since the amount of charge and discharge of the capacitor changes, a large dimming effect can be obtained, and the discharge lamp has a very short rest period, so that there is little flicker. High efficiency and dimming can be performed with a long service life. Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a circuit configuration of the present embodiment, wherein 1 is a rectifying and smoothing circuit, 2 is a switch control circuit, 3 to 6 are semiconductor switches, 7 is a ballast capacitor, 8 is a discharge lamp electrode,
A discharge lamp having 9 and 10; 13 is a voltage waveform detection circuit composed of resistors 11 and 12; 19 is composed of a voltage comparator 14, a counter 15, a digital calculator 16, a reference voltage source 17, and a clock generator 18. Dimming information detector, 20 is a clock generator, 21 is a phase control dimming circuit, 22 is an AC power supply, 23 is a control signal of the semiconductor switches 3 to 6, 24 is an input terminal of the dimming information detector 19, 26 and 27 are power input terminals. First, the basic operation of lighting the discharge lamp of the present circuit will be described. As an operation at the time of starting, the electrodes 9 and 10 of the discharge lamp 8 are preheated. When the switch 6 is opened and the switch 5 is short-circuited, the switches 3 and 4 are alternately opened and closed so as not to be short-circuited at the same time. 9 and
10 is heated. After the electrodes 9 and 10 have been sufficiently preheated in this manner, the switches 3 and 5 are opened and the switches 4 and 5 are opened.
And 6 are shorted to charge the capacitor 7. At this time, the capacitor 7 is charged positively on the discharge lamp side and negatively charged on the side opposite to the discharge lamp. Subsequently, when the switches 4, 5, and 6 are opened and the switch 3 is short-circuited, the sum of the power supply voltage and the charging voltage of the capacitor 7 is applied to the discharge lamp 8 to start discharging. When the switches 3 and 4 are alternately opened and closed with the switches 5 and 6 open after the start of the discharge, an alternating current flows through the discharge lamp 8 via the capacitor 7 and the lighting is continued. By the way, according to the circuit configuration shown in FIG. 1, when the output of the phase control dimmer 21 is applied to the power input terminals 26 and 27, the power input terminal 26 or 27 and the low voltage side output of the rectifying / smoothing circuit 1 are connected. FIG. 2 (a) shows a waveform obtained as a result of dividing the voltage waveform with the resistors 11 and 12 by resistance.
In the waveform diagram of FIG. 2 (a), broken lines indicate waveforms that have not been subjected to flow control. Therefore, the voltage comparator 14
Outputs the waveform shown in FIG. 2 (b). In addition, the broken line in the waveform diagram of FIG. 2 (b) indicates a waveform output from the voltage comparator 14 when a waveform not subjected to the flow angle control is input to the input terminal. Next, when the output of the voltage comparator 14 is ten, the number of clocks shown in FIG. 2C output from the clock generator 18 inputted to the counter 15 is counted, and the output of the voltage comparator 14 becomes one. The dimming information is obtained by calculating the difference from the value counted during the period in the digital calculator 16. As described above, after the start of discharge, switches 5 and 6
While switches are open, switches 3 and 4 are alternately opened and closed to maintain lighting, but FIGS. 3 (a) and 3 (b) show the open / close control signal waveforms of switches 3 and 4 without light control, respectively. . In the case of dimming, the reference clock shown in FIG. 3 (c) is digitally operated in accordance with the operation result obtained by the above-mentioned digital operation unit 16, and shown in FIGS. 3 (d) and 3 (e). A switch open / close control signal is generated, and switch 3
The dimming is performed by controlling the duty of opening and closing of and. In the embodiments described so far, the method of obtaining the dimming information from the power supply voltage waveform has been described. Is obtained. Alternatively, by changing the reference voltage 17, the output pulse width of the voltage comparator 14 can be changed, and the same dimming operation can be performed. [Effects of the Invention] As described above, according to the present invention, a high-frequency discharge lamp lighting device using a DC power supply as a power supply circuit, which is obtained by rectifying and smoothing a commercial AC power supply, using a phase control dimmer. Since dimming control can be performed directly, a discharge lamp lighting device capable of dimming with high efficiency can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the operation of a circuit for detecting dimming information, and FIG. FIG. 2 ... Switch control circuit, 13 ... Voltage waveform detection circuit, 14
… Voltage comparator, 15… Counter, 16… Digital calculator, 17… Reference voltage source, 18… Clock generator, 20…
Clock generator.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-47398 (JP, A) JP-A-57-897 (JP, A) JP-A-58-206099 (JP, A) JP-A-58-58 38491 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H05B 41/38-41/42

Claims (1)

(57) [Claims] In a discharge lamp lighting device configured to include at least a discharge lamp, an impedance element, and a switch (3, 4, 5, 6), and to supply an alternating current to the discharge lamp via the impedance element to light the discharge lamp when the switch is opened and closed. , A power input terminal (2
6, 27), measure the time from when the voltage waveform crosses a predetermined voltage level to when it crosses again,
Controlling the opening and closing time of the switch according to the value obtained by this measurement, and a phase control dimming circuit (21) between the power input terminal (26, 27) and the AC power supply (22);
A discharge lamp lighting device comprising a rectifying and smoothing circuit (1) between the power input terminals (26, 27) and the switch. 2. 2. The measuring device according to claim 1, wherein the measurement of the time from when the voltage waveform crosses a predetermined voltage level to when the voltage waveform crosses again is performed using a counter that operates with a constant clock. Lighting device.