Patent Application
20100188020
a) Field of the Invention
The present invention relates to a high frequency ballast, and more particularly to a high frequency ballast for a fixed output high intensity discharge lamp, which can output a constant power, and can adjust automatically according to frequencies.
b) Description of the Prior Art
A high intensity discharge (HID) lamp used in an existing market has been applied to illuminate in many ways for years. There are four major kinds of HID lamps in a practical application, such as mercury-vapor lamps, low-pressure sodium-vapor lamps, high-pressure sodium-vapor lamps and metallic halogen lamps. These HID lamps illuminate through discharge of high-pressure or low-pressure gas, and are now the most widely used electric light sources due to a high illumination efficiency. However, due to a discharge mechanism of the gas discharge electric light source, its normal working area is usually provided with a negative resistance feature, meaning that as an electric current increases, a voltage decreases on the contrary, and vice versa. Hence, if the gas discharge lamp is directly connected to a voltage source, the lamp will be burnt out as the electric current increases rapidly to exceed a limit, and a ballast should be connected serially in a circuit to restrict the electric current.
A ballast of a medium power (250 W˜400 W) high intensity discharge lamp and a ballast of a metallic halogen lamp sold in the existing market are mostly electromagnetic ballasts, their working voltages include 110VAC and 220VAC, and a working frequency of all ballasts is 60 Hz. Therefore, none of a light energy efficiency, a power factor, a power loss and a lifetime of usage of the high intensity discharge lamp can achieve an energy-saving effect.
Accordingly, how to solve the aforementioned problems and shortcomings in the prior art is a technological issue of research and development for improvement by the present inventor and related vendors.
The primary object of the present invention is to provide a high frequency ballast for a fixed output high intensity discharge lamp, which is serially connected in order with a power input circuit, an electromagnetic wave interference filtering loop, a rectifying loop, a high power factor correction loop, a voltage-controlled oscillator (VCO) ballast driver and a load loop, wherein the VCO ballast driver is electrically connected to an ignition sequence control logic loop by a built-in voltage-controlled oscillator, and a half-bridge driving loop receives power transmitted by the high power factor correction loop and then converts into a steady power output by the ignition sequence control logic loop. When the lamp cannot start successfully, it can start by itself repeatedly through a restart triggering loop. After the lamp has started, an operational amplifier circuit is used to maintain an original frequency which sets the power, thereby performing an automatic adjustment according to the lamps of various frequencies.
Another object of the present invention is to provide a high frequency ballast for a fixed output high intensity discharge lamp, wherein by the VCO ballast driver, it can assure that all the driving and control functions that the HID lamp needs are provided, such as the ignition sequence control loop, a safety protection loop and an operational amplifier which are used to feedback an electric current loop of the HID lamp to achieve a performance of outputting a constant power.
Still another object of the present invention is to provide a high frequency ballast for a fixed output high intensity discharge lamp, wherein the high frequency (80 KHz˜100 KHz), constant power output (250 W˜400 W) ballast can be used in the high-pressure sodium-vapor lamp and the metallic halogen lamp, and can be used in the voltages of 110VAC and 220VAC, so as to reduce a volume of the ballast, decrease parts used in the circuits, and increase functions of the ballast.
Yet still another object of the present invention is to provide a high frequency ballast for a fixed output high intensity discharge lamp, wherein this kind of ballast can be used in any brands of high-pressure sodium-vapor lamps and metallic halogen lamps, and can be used in the voltages of 110VAC and 220VAC, thereby enabling the ballast to be used very conveniently, and the light energy efficiency, the high power factor and the low loss to achieve the energy-saving effect.
To enable a further understanding of the said objectives and the technological methods of the invention herein, the brief description of the drawings below is followed by the detailed description of the preferred embodiments.
Referring to
Referring to
The aforementioned voltage-controlled oscillator ballast driver 14 is a half-bridge oscillator driver chip and further includes a high-pressure voltage output end 20, a low-pressure voltage output end 21, an oscillation time sequence resistor input end 22 and an oscillation time sequence capacitor input end 23, wherein an output end of the operational amplifier loop 145 forms a parallel loop with the oscillation time sequence resistor input end 22 through resistors and diodes, an anti-phase input end is connected to a source of a MOSFT (Metal Oxide-Silicon Semiconductor Field Effect Transistor) of the low-pressure voltage output end 21, with the source being grounded through a resistor, whereas, a non anti-phase input end is connected to a modulatable reference voltage.
It is of course to be understood that the embodiments described herein is merely illustrative of the principles of the invention and that a wide variety of modifications thereto may be effected by persons skilled in the art without departing from the spirit and scope of the invention as set forth in the following claims.
