Excimer lamp light source device
Provided is an excimer lamp light source device that achieves low cost and avoids the occurrence of narrowly-defined contracted discharge by adopting a lamp bulb having a simple structure and of the type in which a discharge current is passed in a tube axis direction. The excimer lamp light source device includes: an excimer lamp that has a pair of external electrodes configured to induce an electric discharge in a discharge space of a lamp bulb and to cause a discharge current to flow in a tube axis direction of the lamp bulb, and that generates UV light in the discharge space by the discharge; and an inverter having a transformer equipped with a secondary winding to which the external electrodes are connected in order to apply a high-voltage alternating current to the excimer lamp, the inverter supplying power lower than power that causes a linear discharge.
1. An excimer lamp light source device comprising:
an excimer lamp (Y) that has a pair of external electrodes (Ye 1 , Ye 2 ) configured to induce an electric discharge in a discharge space (Yg) of a lamp bulb (Yt) and to cause a discharge current to flow in a tube axis direction of the lamp bulb (Yt), that does not have an internal electrode, and that generates UV light in the discharge space (Yg) by the discharge, the lamp bulb (Yt) enclosing the discharge space (Yg) filled with a discharge gas configured to generate xenon excimer molecules, having a shape in which both ends of a tubular body are hermetically sealed, and having an easily dischargeable substance layer (Yo) that facilitates a discharge formed on at least a part of a surface that is in contact with the discharge space (Yg); and
an inverter (Ui) having a transformer (Tf) equipped with a secondary winding (Ls) to which the external electrodes (Ye 1 , Ye 2 ) are connected in order to apply a high-voltage alternating current to the excimer lamp (Y), wherein
the inverter (Ui) supplies power lower than power that causes a narrowly-defined contracted discharge to the excimer lamp (Y) to light the excimer lamp (Y) in a discharge state that is not the narrowly-defined contracted discharge,
the narrowly-defined contracted discharge being a discharge that mainly has a form consisting of one linear discharge path extending from a vicinity of an inner surface portion of the lamp bulb (Yt) facing a portion of the lamp bulb (Yt) in which one of the external electrodes (Ye 1 , Ye 2 ) is close to or in contact with, to a vicinity of the inner surface portion of the lamp bulb (Yt) facing a portion of the lamp bulb (Yt) in which another of the external electrodes (Ye 1 , Ye 2 ) is close to or in contact with.
2. The excimer lamp light source device according to claim 1 , wherein
the pair of external electrodes (Ye 1 , Ye 2 ) have an inter-electrode distance (Le), which is measured along an outer surface of the lamp bulb (Yt) and is a minimum value of a distance between each other, of a value that is selected from within a region of the inter-electrode distance (Le) where a minimum value of power that generates the narrowly-defined contracted discharge increases or saturates to increase when the inter-electrode distance (Le) is increased, the minimum value of power being determined according to the inter-electrode distance (Le).
3. The excimer lamp light source device according to claim 1 , wherein
a ratio of a power value causing the narrowly-defined contracted discharge to a lamp input power value during normal operation is 105% to 120%.
4. An excimer lamp lighting method in an excimer lamp light source device comprising:
an excimer lamp (Y) that has a pair of external electrodes (Ye 1 , Ye 2 ) configured to induce an electric discharge in a discharge space (Yg) of a lamp bulb (Yt) and to cause a discharge current to flow in a tube axis direction of the lamp bulb (Yt), that does not have an internal electrode, and that generates UV light in the discharge space (Yg) by the discharge, the lamp bulb (Yt) enclosing the discharge space (Yg) filled with a discharge gas configured to generate xenon excimer molecules, having a shape in which both ends of a tubular body are hermetically sealed, and having an easily dischargeable substance layer (Yo) that facilitates a discharge formed on at least a part of a surface that is in contact with the discharge space (Yg); and
an inverter (Ui) having a transformer (Tf) equipped with a secondary winding (Ls) to which the external electrodes (Ye 1 , Ye 2 ) are connected in order to apply a high-voltage alternating current to the excimer lamp (Y), wherein
the inverter (Ui) supplies power lower than power that causes a narrowly-defined contracted discharge to the excimer lamp (Y) to light the excimer lamp (Y) in a discharge state that is not the narrowly-defined contracted discharge,
the narrowly-defined contracted discharge being a discharge that mainly has a form consisting of one linear discharge path extending from a vicinity of an inner surface portion of the lamp bulb (Yt) facing a portion of the lamp bulb (Yt) in which one of the external electrodes (Ye 1 , Ye 2 ) is close to or in contact with, to a vicinity of the inner surface portion of the lamp bulb (Yt) facing a portion of the lamp bulb (Yt) in which another of the external electrodes (Ye 1 , Ye 2 ) is close to or in contact with.
5. The excimer lamp lighting method according to claim 4 , wherein
a ratio of a power value causing the narrowly-defined contracted discharge to a lamp input power value during normal operation is 105% to 120%.