Light source device and sterilization and odor removal device

Abstract

The present invention provides a new light source device using an excimer lamp, particularly a light source device for sterilization / deodorization. The light source device includes an excimer lamp (1) and a flyback type lighting device that supplies power to the excimer lamp. The lighting device includes a transformer (2), a switching element (4), and a control circuit (5) that supplies a drive signal to the switching element (4). The control circuit (5) performs on / off control of the switching element (4) so that the switching frequency (FS) of the switching element (4) at the start of lighting is lower than the switching frequency (FO) during constant lighting, and the duty ratio (TS) of the switching element (4) at the start of lighting becomes a value smaller than the duty ratio (TO) during constant lighting.

Description

Technical Field

[0001] The present invention relates to a light source device. In particular, it relates to a light source device including an excimer lamp that emits ultraviolet light through dielectric barrier discharge and a lighting device therefor. Background Art

[0002] In recent years, a sterilization / deodorization device using an excimer lamp that emits ultraviolet light through dielectric barrier discharge has been known. This excimer lamp has a structure in which a so-called dielectric barrier discharge is generated by a pair of electrodes disposed sandwiching a light-emitting tube made of a dielectric material, and the discharge gas sealed inside is excited to emit ultraviolet light. For example, when xenon gas is sealed as the discharge gas, vacuum ultraviolet light having a single peak at a wavelength of 172 nm is generated.

[0003] In recent years, such excimer lamps have received attention for use in vehicles and lighting fixtures, and there is also a strong demand for the development of devices corresponding to such uses as light source devices.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent No. 6717335 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] Therefore, an object of the present invention is to provide a new light source device using an excimer lamp, particularly a light source device for sterilization / deodorization.

[0009] Means for Solving the Problems

[0010] To solve the above problems, the light source device according to the present invention includes: an excimer lamp that emits ultraviolet light through dielectric barrier discharge; and a flyback lighting device that supplies power to the excimer lamp. The lighting device includes: a switching element; a transformer having its primary side connected to the switching element and its secondary side connected to the excimer lamp; and a control circuit that supplies a drive signal to the switching element.

[0011] The control circuit performs on / off control of the switching element so that the switching frequency (FS), which is the frequency of the turn-on timing of the switching element at the start of lighting of the excimer lamp, is lower than the switching frequency (FO) during the constant lighting of the excimer lamp, and the duty ratio (TS) of the switching element at the start of lighting of the excimer lamp becomes a value smaller than the duty ratio (TO) of the switching element during the constant lighting of the excimer lamp.

[0012] Furthermore, it is characterized in that the control circuit controls the switching element to turn on and off, so that the switching frequency (FS) at the time of starting the lighting of the excimer lamp gradually increases toward the switching frequency (FO) at the time of the constant lighting of the excimer lamp.

[0013] Furthermore, it is characterized in that the control circuit controls the switching element to turn on and off, so that the duty ratio (TS) at the time of starting the lighting of the excimer lamp gradually increases toward the duty ratio (TO) at the time of the constant lighting of the excimer lamp.

[0014] Furthermore, it is characterized in that the excimer lamp includes a substantially rod-shaped light-emitting tube and a pair of ring-shaped electrodes arranged at both ends of the light-emitting tube.

[0015] Furthermore, it is characterized in that the excimer lamp emits ultraviolet light with a wavelength of 172 nm.

[0016] Furthermore, it is characterized in that the excimer lamp has a light-emitting tube with a total length of 10 cm or less and is a sterilization / deodorization lamp used in a closed space.

[0017] Furthermore, the sterilization / deodorization device according to the present invention includes: an excimer lamp that emits ultraviolet light through dielectric barrier discharge; and a flyback lighting device that supplies power to the excimer lamp.

[0018] Moreover, the lighting device includes: a switching element; a transformer that is connected to the switching element on the primary side and to the excimer lamp on the secondary side; and a control circuit that supplies a driving signal to the switching element. The control circuit controls the switching element to turn on and off, so that the switching frequency (FS), which is the frequency of the turn-on timing of the switching element at the time of starting the lighting of the excimer lamp, is lower than the switching frequency (FO) at the time of the constant lighting of the excimer lamp, and the duty ratio (TS) of the switching element at the time of starting the lighting of the excimer lamp becomes a value smaller than the duty ratio (TO) of the switching element at the time of the constant lighting of the excimer lamp.

[0019] Advantages of the Invention:

[0020] The light source device according to the present invention can reliably light the excimer lamp by performing control different from that during constant lighting at the time of starting the lighting. Description of the Drawings

[0021] Figure 1 Shows the overall structure of the light source device according to the present invention.

[0022] Figure 2 A shows an enlarged view of the excimer lamp according to the present invention.

[0023] Figure 2 B shows an enlarged view of the excimer lamp related to the present invention.

[0024] Figure 3 It shows the waveform of the voltage applied to the lamp of the light source device related to the present invention.

[0025] Figure 4 It is a timing chart showing the control content of the light source device related to the present invention.

[0026] Figure 5 It is a timing chart showing the control content of the light source device related to the present invention.

[0027] Figure 6 It is a timing chart showing the control content of the light source device related to the present invention.

[0028] Reference Numeral Explanation

[0029] 1 Excimer lamp

[0030] 2 Transformer

[0031] 3 Input circuit

[0032] 4 Switching element

[0033] 5 Drive circuit Detailed Description of the Preferred Embodiments

[0034] Figure 1 It shows the overall structure of the light source device related to the present invention. Figure 1 The shown light source device includes an excimer lamp 1, a transformer 2, an input circuit 3, a switching element 4, and a control circuit 5. The excimer lamp 1 (hereinafter also simply referred to as "lamp 1") has a pair of electrodes, and these two electrodes are electrically connected to the secondary winding of the transformer 2. At one end of the primary winding of the transformer 2, an input circuit 3 supplied with power from a commercial power source and a DC power source is connected. At the other end of the primary winding of the transformer 2, a switching element 4 such as an FET element is connected, and a control circuit 5 is connected to the gate of the switching element 4. Figure 1 The shown circuit is generally referred to as a boost flyback circuit, and corresponding to the turn-off timing of the switching element 4, a single-pulse voltage waveform is periodically repeated on the secondary side of the transformer 2.

[0035] Figure 2 A and Figure 2 B shows an enlarged view of the lamp 1 related to the present invention. Figure 2 A shows an external view of the lamp 1, Figure 2B represents the internal structure of lamp 1. Lamp 1 includes a light-emitting tube 11 that is generally rod-shaped as a whole, and a pair of electrodes 12 and 13 are disposed at both ends thereof. The light-emitting tube 11 is made of quartz glass as a dielectric material, and xenon gas as a discharge gas is sealed inside. If a voltage is applied to the two electrodes, discharge occurs inside the light-emitting tube 11 as shown in Figure 2 B. Through this discharge, the sealed gas is excited to become an excimer state, and vacuum ultraviolet light with a wavelength of, for example, 172 nm is generated. In addition, for the sake of simplicity of illustration, platinum paste is coated on the inner surface of the light-emitting tube 11 at a position corresponding to the electrode 12 as a starting auxiliary functional component. In Figure 2 B, the state of discharge occurring inside the light-emitting tube 11 is schematically illustrated by shaded expressions.

[0036] In addition, the electrode forms of the pair of electrodes 12 and 13 are not limited to the Figure 2 structures shown in A and Figure 2 B. For example, a pair of long strip-shaped electrodes can also be disposed on the outer surface of the light-emitting tube in a manner extending along the length direction (for example, Japanese Patent Laid-Open No. 2009-123406), or only one of the electrodes can be disposed inside the light-emitting tube (for example, Japanese Patent Laid-Open No. 2002-319371).

[0037] In addition, when the light source device related to the present invention is used as a sterilization / deodorization device, as lamp 1, a lamp 1 that emits UVC (wavelength 200 - 280 nm) or vacuum ultraviolet light (wavelength 200 nm or less) is used. When Kr (krypton) and Br (bromine) are sealed as the light-emitting gas, a radiation spectrum having a single peak at a wavelength of 207 nm is emitted from KrBr * (krypton bromide excimer). In addition, when Kr (krypton) and chlorine (Cl) are sealed, a radiation spectrum having a single peak at a wavelength of 222 nm is emitted from KrCl * (krypton chloride excimer). The lamp 1 related to the present invention is also envisioned to be mounted on a vehicle or a lighting fixture. In this case, the rod-shaped light-emitting tube is relatively short. If numerical examples are given, the total length of the light-emitting tube 11 is 40 mm, and the light-emitting tube diameter is φ6 mm.

[0038] Figure 3 represents the voltage waveform occurring on the secondary side of the transformer 2 of the light source device related to the present invention.

[0039] At the moment (t0) when the switching element 4 constituting the flyback turns off, a single-pulse voltage occurs in the secondary winding of the transformer 2. If the switching element 4 turns off at the next timing (t1), the same voltage waveform is repeatedly generated.

[0040] Here, there are many types of lighting devices for excimer lamps that supply sine waves and rectangular pulses to the lamp. However, in the present invention, through the Figure 1 flyback circuit shown, a voltage waveform having a substantially single peak as shown in Figure 3 is supplied to lamp 1. The oscillating current after the peak hardly occurs due to the relationship with the regenerative current of the FET element (switching element 4). Conventionally known excimer lamps generally have a relatively large overall length of 100 mm or more. In order to generate good discharge between the electrodes, sine waves and rectangular wave pulses with relatively high voltages are supplied to the excimer lamp. On the other hand, the light source device according to the present invention is envisioned for use in being mounted on a vehicle or a lighting fixture as one application. In this case, the overall scale of the light source device becomes small. In this case, in the Figure 2 lamp 1 shown in A and Figure B, those with an overall length of less than 100 mm are also used. Therefore, a flyback type lighting circuit suitable for low power and high voltage can be adopted. If the flyback method is used for an excimer lamp that requires high power, the transformer of the lighting device becomes huge, and the switching element requires products corresponding to large currents and high voltages, so it is not practical.

[0041] ​ A timing chart for explaining the control content for stably lighting the lamp 1 according to the present invention is shown.

[0042] At time T1, lamp 1 is lit. The period from time T1 to time T3 is set as the lighting start state, and the period after time T3 is set as the constant lighting state.

[0043] The switching frequency (FS) from time T1 to time T2 is set to a value lower than the switching frequency (FO) during constant lighting. The switching frequency corresponds to the frequency of the signal from the control circuit 5 to the switching element 4 in ​ , but it can also be said to be the period of the current waveform supplied to lamp 1 in ​ . The switching frequency is sometimes also referred to as the on-timing frequency.

[0044] Furthermore, the duty ratio (ON DUTY) (TS) of the switch from time T1 to time T3 is set to a value lower than the duty ratio (TO) during constant lighting.

[0045] The reason is that the lamp power during constant lighting is set to be approximately the same value even during lighting startup. That is, at the start of lighting of lamp 1, in order to light stably, the lighting frequency is reduced and the supply voltage to lamp 1 is increased. On the other hand, if the lamp power becomes high, as the amount of ultraviolet rays increases, the amount of ozone generated increases, so the duty ratio of the switching element 4 is reduced.

[0046] If numerical examples are given, it is as follows. The lamp voltage during constant lighting is 3.8 kV, and the lamp voltage during lighting startup is 4.5 kV. The switching frequency (FO) during constant lighting is 28 kHz, and the switching frequency (FS) during lighting startup is 24 kHz. The duty ratio (TO) of the switching element 4 during constant lighting is 80%, and the duty ratio (TS) of the switching element 4 during lighting startup is 53%. The timing for switching the switching frequency from the value (FS) during lighting startup to the value (FO) during constant lighting (the elapsed time from time T1 to time T2) is 10 msec, and the timing for switching the duty ratio of the switching element from the value (TS) during lighting startup to the value (TO) during constant lighting (the elapsed time from time T1 to time T3) is 18 msec.

[0047] Thus, although the light source device according to the present invention is miniaturized, it can be stably lit and started up, and when the lamp 1 is lit and started up, the problem of a large amount of ozone being generated along with an increase in the amount of ultraviolet rays can be avoided.

[0048] ​ is ​ a modified example, showing a time chart for explaining the control content for stably lighting the lamp 1 according to the present invention.

[0049] The lamp 1 is lit at time T1. The period from time T1 to time T3 is set as the startup lighting state, and the period after time T3 is set as the constant lighting state.

[0050] ​ The control shown in ​ differs from the control shown in

[0051] in that at the timing (T2) for switching the switching frequency from the set value (FS) during lighting startup to the set value (FO) during constant lighting, control is performed to gradually increase the duty ratio (ONDUTY) of the switching element 4.

[0052] ​ is ​ 、 ​ a further modified example, showing a time chart for explaining the control content for stably lighting the lamp 1 according to the present invention.

[0053] At time T1, the lamp 1 is lit. The period from time T1 to time T3 is set as the startup lighting state, and the period after time T3 is set as the constant lighting state.

[0054] ​ The control shown in ​The control of the different points is to control the timing (T2) when switching the switching frequency from the lighting start-up (FS) to the constant lighting (FO) so that the operating rate (ON DUTY) of the switching element 4 increases step by step.

[0055] If a numerical example is shown, the operating rate of the switching element 4 at time T2 is 53%, and the operating rate is increased step by step every 1 msec, and it takes 9 msec to change to the operating rate of 80% at constant lighting.

[0056] In this way, by avoiding a sharp change in the operating rate of the switching element 4, the lamp 1 can be stably transferred from the lighting start-up state to the constant lighting state.

Claims

1. A light source device, characterized in that: It includes: An excimer lamp that emits ultraviolet light through dielectric barrier discharge; A flyback lighting device that supplies power to the above-mentioned excimer lamp; A switching element equipped in the above-mentioned lighting device; A transformer equipped in the above-mentioned lighting device, with the primary side connected to the above-mentioned switching element and the secondary side connected to the above-mentioned excimer lamp; And A control circuit equipped in the above-mentioned lighting device that supplies a drive signal to the above-mentioned switching element, When the above-mentioned control circuit starts the lighting of the above-mentioned excimer lamp, within a specified time, while fixing the switching frequency of the above-mentioned switching element at the frequency FS and fixing the duty ratio of the above-mentioned switching element at the duty ratio TS, the above-mentioned switching element is controlled to be turned on and off. After passing the above-mentioned specified time, the above-mentioned control circuit controls the above-mentioned switching element to be turned on and off while increasing the switching frequency of the above-mentioned switching element from the frequency FS and increasing the duty ratio of the above-mentioned switching element from the duty ratio TS. When the above-mentioned excimer lamp is constantly lit, the above-mentioned control circuit controls the above-mentioned switching element to be turned on and off while fixing the switching frequency of the above-mentioned switching element at a frequency FO higher than the frequency FS and fixing the duty ratio of the above-mentioned switching element at a duty ratio TO higher than the duty ratio TS.

2. The light source device according to claim 1, characterized in that: The above-mentioned control circuit controls the above-mentioned switching element to be turned on and off so that the switching frequency FS at the start of lighting of the above-mentioned excimer lamp gradually increases towards the switching frequency FO during the constant lighting of the above-mentioned excimer lamp.

3. The light source device according to claim 1, characterized in that: The above-mentioned control circuit controls the above-mentioned switching element to be turned on and off so that the duty ratio TS at the start of lighting of the above-mentioned excimer lamp gradually increases towards the duty ratio TO during the constant lighting of the above-mentioned excimer lamp.

4. The light source device according to claim 1, characterized in that: The above-mentioned excimer lamp includes a substantially rod-shaped light-emitting tube and a pair of electrodes arranged in a ring shape at both ends of the light-emitting tube.

5. The light source device according to claim 1, characterized in that: The above-mentioned excimer lamp emits ultraviolet light with a wavelength of 172 nm.

6. The light source device according to claim 5, characterized in that: The above-mentioned excimer lamp has a light-emitting tube with a total length of 10 cm or less and is a sterilization / deodorization lamp used in a closed space.

7. A sterilization and deodorization device, characterized in that: It includes: An excimer lamp that emits ultraviolet light through dielectric barrier discharge; A flyback lighting device that supplies power to the excimer lamp; A switching element equipped in the above-mentioned lighting device; A transformer equipped in the above-mentioned lighting device, with the primary side connected to the above-mentioned switching element and the secondary side connected to the above-mentioned excimer lamp; And A control circuit equipped in the above-mentioned lighting device that supplies a drive signal to the above-mentioned switching element, When the above-mentioned control circuit starts the above-mentioned excimer lamp, within a specified time, while fixing the switching frequency of the above-mentioned switching element at the frequency FS and fixing the duty ratio of the above-mentioned switching element at the duty ratio TS, the above-mentioned switching element is controlled to be turned on and off. After the above-mentioned specified time has elapsed, the above-mentioned control circuit controls the above-mentioned switching element to be turned on and off while increasing the switching frequency of the above-mentioned switching element from the frequency FS and increasing the duty ratio of the above-mentioned switching element from the duty ratio TS. When the above-mentioned excimer lamp is constantly lit, the above-mentioned control circuit controls the above-mentioned switching element to be turned on and off while fixing the switching frequency of the above-mentioned switching element at a frequency FO higher than the frequency FS and fixing the duty ratio of the above-mentioned switching element at a duty ratio TO higher than the duty ratio TS.

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