JP2011054436A - Lighting device - Google Patents

Abstract

Provided is an illumination device that has excellent color rendering properties, can suppress deterioration due to ultraviolet rays, and can reduce manufacturing costs.
According to one aspect of the present invention, a lighting device includes a light source and a light emitting glass that covers at least a part of the light source, and the light emitting glass emits light emitted from the light source. An illumination device 1 is provided, which is excited by light having a wavelength shorter than the absorption edge wavelength of the glass 6 and emits continuous spectrum light having a wavelength longer than the wavelength that excites the light emitting glass 6.
[Selection] Figure 1

Description

  The present invention relates to a lighting device using luminescent glass.

  In recent years, light emitting diodes (hereinafter referred to as “LEDs”) have been widely used as light sources or indicators for lighting devices. In particular, white light emitting LEDs are important as illumination devices, and are realized by various methods. Currently, the following three types of methods are known as methods for producing white light emitting LEDs.

(1) A method of combining a blue light emitting LED chip and a YAG phosphor added with Ce ²⁺ that emits yellow light by blue light emitted from the blue light emitting LED chip (see Patent Document 1),
(2) A method of emitting light by providing a phosphor containing a rare earth element on a near-ultraviolet diode,
(3) There is a method of creating a white light emitting LED using three LEDs of a red light emitting LED, a green light emitting LED, and a blue light emitting LED.

  The method (1) has advantages such as long life, low power consumption, and no inclusion of environmentally hazardous substances compared to conventional light sources such as lighting devices. Is expected as a light source.

  However, in this method, since the phosphor is mixed with the transparent resin and provided on the blue light-emitting LED, there is a problem that the transparent resin deteriorates due to light and heat and the life is shortened. In addition, since white is realized by mixing blue and yellow, there is also a problem of lack of color rendering.

  In the method (2), an expensive rare earth element is used, so that there is a problem of high cost. Moreover, it is necessary to add one or more kinds of fluorescent elements. Further, since the phosphor is mixed with the resin in the same manner as in the method (1), there is a problem that the resin is easily deteriorated by ultraviolet rays and the life is shortened.

  In the method (3), white is obtained by using three LEDs, a red light emitting LED, a green light emitting LED, and a blue light emitting LED. Therefore, the brightness balance of each LED is important. There is a problem that it is difficult to adjust sex. Moreover, since three LEDs are used, the apparatus becomes complicated. Furthermore, since it is produced by mixing with a resin in the same manner as in the above method (1), there is a problem that the resin is easily deteriorated by ultraviolet rays and its life is shortened.

JP 2000-208815 A

  The present invention has been made to solve the above problems. That is, an object of the present invention is to provide an illumination device that has excellent color rendering properties, can suppress deterioration due to ultraviolet rays, and can reduce manufacturing costs.

  According to one aspect of the present invention, there is provided a lighting device including a light source and a luminescent glass covering at least a part of the light source, wherein the luminescent glass is based on an absorption edge wavelength of the luminescent glass emitted from the light source. An illumination device is provided, which is excited by a light having a short wavelength and emits a continuous spectrum light having a wavelength longer than the wavelength for exciting the light emitting glass.

  According to one embodiment of the present invention, it is possible to provide an illumination device that has excellent color rendering properties, can suppress deterioration due to ultraviolet rays, and can reduce manufacturing costs.

It is a typical longitudinal cross-sectional view of the illuminating device which concerns on embodiment. It is an emission spectrum at the time of exciting the luminescent glass which concerns on Example 1 with the ultraviolet-ray with a wavelength of 360 nm. 6 is a graph showing a transmittance curve of a luminescent glass with respect to a wavelength according to Example 3. It is an emission spectrum at the time of exciting the light emission glass which concerns on Example 3 with the ultraviolet-ray with a wavelength of 255 nm, 280 nm, and 300 nm.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic longitudinal sectional view of a lighting device according to the present embodiment. As shown in FIG. 1, the lighting device 1 mainly includes a base material 2, a reflective layer 3, leads 4, a light source 5, a light emitting glass 6, and the like.

  The base material 2 accommodates the light source 5 inside. A recess 2 a is formed in the base material 2, and a light source 5 is disposed at the bottom of the recess 2 a. The recess 2a has a tapered shape, specifically, an opening of the recess 2a that extends from the bottom toward the top.

  The reflective layer 3 is formed on the tapered inner surface of the recess 2a. By reflecting the light from the light source 5 by the reflective layer 3, the luminous efficiency of the luminescent glass 6 can be improved.

  The lead 4 is for supplying power to the light source 5, and is configured so that the light source 5 is turned on by supplying power to the light source 5 from a power source (not shown) via the lead 4.

  The light source 5 is not particularly limited as long as it can emit light having a wavelength shorter than the absorption edge wavelength, which will be described later, of the light emitting glass 6, and the light source 5 can also be used that emits light having a wavelength existing in the complete absorption region, which will be described later. It is. Specifically, examples of the light source 5 include those that emit ultraviolet rays such as ultraviolet diodes and ultraviolet lamps.

  The light emitting glass 6 is disposed so as to cover at least a part of the light source 5. In the present embodiment, the luminescent glass 6 is disposed on the light source 5. Specifically, the luminescent glass 6 is formed not only in the recess 2a but also on the recess 2a.

  It is preferable that the luminescent glass 6 has arbitrary irregularities on the surface other than the surface on the light source 5 side. In this Embodiment, the surface on the opposite side to the surface at the side of the light source 5 in the light emission glass 6 is formed in convex shape. By forming irregularities on the luminescent glass 6, the surface area can be increased, and the luminous efficiency can be improved.

  The light emitting glass 6 preferably includes an absorption film 6a that absorbs a specific light component from the light source 5 on a surface other than the surface on the light source 5 side. In the present embodiment, an absorption film 6a is formed on the surface of the light emitting glass 6 opposite to the surface on the light source 5 side. Instead of the absorption film 6a, a reflection film that reflects a specific light component from the light source 5 may be formed. By forming a film that absorbs or reflects ultraviolet rays as the absorbing film 6a or the reflective film, when a light source that emits ultraviolet rays is used, leakage of ultraviolet rays can be prevented and efficiency can be improved.

  The light emitting glass 6 is excited by light having a wavelength shorter than the absorption edge wavelength of the light emitting glass 6 and emits continuous spectrum light having a wavelength longer than the excitation wavelength. Here, the “absorption edge” in the present invention means the lowest energy at which light absorption starts. A wavelength corresponding to this is called an “absorption edge wavelength”, and light having a wavelength longer than that wavelength is transmitted. In general, the “absorption edge wavelength” is obtained by extrapolation by linearly fitting the rising portion in the relationship in the absorption spectrum. In FIG. 3 shown later, the absorption edge wavelength exists in the vicinity of 380 nm.

  The luminescent glass 6 is preferably excited by light having a wavelength existing in the complete absorption region of the luminescent glass 6. Here, the “complete absorption region” in the present invention is a wavelength region shorter than the absorption edge wavelength and means a wavelength region in which the light transmittance of the luminescent glass 6 is almost zero. In FIG. 3 shown later, the complete absorption region is a region of about 320 nm or less. Higher emission intensity can be obtained by excitation with light having a wavelength existing in the complete absorption region.

  The continuous spectrum light emitted from the light emitting glass 6 is preferably continuous in a wavelength region of at least 400 to 800 nm. This is because if the continuous spectrum light is continuous in at least a wavelength region within this range, excellent color rendering in white can be realized.

The light emitting glass 6 is not particularly limited as long as it is excited by light having a wavelength shorter than the absorption edge wavelength of the light emitting glass 6 and emits continuous spectrum light having a wavelength longer than the excitation wavelength. Examples of the glass include tin oxide-containing glass. The tin oxide-containing glass is manufactured using a glass material, a raw material containing SnO ₂ having a content of 1 mol% or more, and a reducing agent, and tin oxide obtained by reducing SnO ₂ with a reducing agent. Is included.

The glass material preferably contains silicon oxide and optionally boric acid or boron oxide. As a particularly preferred embodiment, the glass material further contains boron oxide, aluminum oxide, calcium oxide, or sodium oxide. By containing such an oxide, the melting point of the glass is lowered, so that even when 1 mol% or more of SnO ₂ is added, the reduced tin oxide is suppressed from being oxidized. Therefore, it is possible to realize a tin oxide-containing glass having excellent transparency and high emission intensity. As such a glass material, for example, borosilicate glass (borosilicate glass) mainly composed of boric acid and silicic acid, soda lime glass mainly composed of Na ₂ O · CaO · SiO ₂ and the like are preferably used. Can be used.

  The content of the glass material in the raw material is preferably 20 to 80 mol% of silicon oxide, 10 to 50 mol% of boric acid or boron oxide, and 0 to 50 mol% of sodium oxide, and 20 to silicon oxide. More preferably, it is ˜50 mol%, boron oxide is 10-30 mol%, and sodium oxide is 5-30 mol%, silicon oxide is 30-50 mol%, and boron oxide is 20-30 mol%.

  In order to make glass materials easier to vitrify and enable stable glass production, lithium oxide, phosphorus oxide, calcium oxide, calcium phosphate, yttrium oxide, indium oxide, barium oxide, barium phosphate, antimony oxide, oxidation It is preferable to include one or more compounds selected from the group consisting of bismuth, lanthanum oxide, and magnesium oxide. The content of this compound is preferably 1 to 20 mol% in the raw material, and more preferably 1 to 13 mol%.

SnO ₂ may be at not less than 1 mol% content in the raw material, but preferably is 1 to 20 mol%, more preferably 3~17mol%, 5~15mol% is particularly preferred. This is because if the SnO ₂ content is less than 1 mol%, the emission intensity when irradiated with ultraviolet rays may not be sufficiently obtained. Also, when the transparency of glass is required, because the content of SnO ₂ is produced an opaque crystalline portion in the glass exceeds 20 mol%, it may not be possible to form a transparent glass. When SnO ₂ having a content of 1 mol% or more is used, the content of tin oxide in the glass is about 1 mol% or more, and SnO ₂ having a content of 3 to 17 mol% or 5 to 15 mol% is added. When used, the content of tin oxide in the glass is about 3 to 17 mol% and about 5 to 15 mol%.

“Tin oxide” contained in the tin oxide-containing glass is obtained by reducing SnO ₂ with a reducing agent, and is a concept that hardly contains SnO ₂ . Specifically, this tin oxide is considered to be an oxide of tin having a valence of 2 to less than 4. That is, as the tin oxide, two kinds of oxides of SnO and SnO ₂ are generally known. In this case, the valence of tin is bivalent and tetravalent, but it has a bivalent tin and a hole. It is also considered that a state or a trivalent state exists. When SnO ₂ is reduced, it is considered that tin oxide having a divalent tin and a hole, or trivalent tin oxide can be produced preferentially.

The content of the reducing agent is preferably from 10 to 70% of the content of SnO _2. The reducing agent is not particularly limited as long as it is a substance capable of reducing SnO ₂ , but is a substance that becomes a constituent component of glass by being oxidized or a substance that is vaporized at the melting temperature of the glass material by being oxidized. It is preferable that The former substance becomes a constituent component of glass by being oxidized, and the latter substance is discharged from the glass by being oxidized. Therefore, for example, the transparency of the glass is not affected.

  The above “component of glass” means not only the main component of glass but also substances generally added to glass. Examples of the substance that becomes a constituent component of glass by being oxidized include one or more substances selected from the group consisting of Si, Al, and Zn.

Examples of the substance that vaporizes when oxidized include carbohydrates such as carbon and sugar. When carbon and carbohydrates are oxidized, they are vaporized as CO ₂ and can be discharged from the molten glass.

In order to manufacture such an illuminating device 1, the molten luminescent glass material is poured into a mold formed to have the shape of the luminescent glass 6, and the luminescent glass material is cooled and solidified. When producing tin oxide-containing glass as the luminescent glass, the glass material explained above, SnO ₂ having a content of 1 mol% or more, and a raw material containing a reducing agent are heated to melt the glass material and SnO _2. Is reduced with a reducing agent, and the molten glass is poured into a mold and cooled to solidify.

  When producing tin oxide-containing glass, a raw material having the above composition can be melted at a relatively low temperature of 1300 ° C to 1500 ° C. If the temperature is lower than 1300 ° C, the raw material may not melt.

  The time for melting the raw material at the melting temperature is preferably about 30 minutes to 4 hours. If it is less than 30 minutes, the glass component is insufficiently melted, so that crystals remain in the melt and the transparency when the glass is solidified is impaired. On the other hand, if the melting is performed for more than 4 hours, the reduced tin oxide may be oxidized, which affects the light emission characteristics of the glass or makes the glass opaque.

  Further, in order to suppress the oxidation of the reduced tin oxide, it is preferable to melt and solidify the glass in an inert gas atmosphere such as nitrogen.

Since the tin oxide-containing glass thus obtained contains tin oxide in a divalent to tetravalent state in the glass, light emission can be obtained by irradiation with ionizing radiation such as ultraviolet rays. Specifically, broad light emission in the visible light band can be obtained by irradiating ultraviolet rays having a wavelength of 200 to 380 nm. That is, the light emission characteristic of tin oxide is a characteristic obtained when the valence of tin in the tin oxide is in a divalent state or an unstable state between divalent and tetravalent. The wavelength is considered to change. According to the tin oxide-containing glass of the present invention, SnO ₂ is reduced to obtain tin oxide, so that tin oxide having a valence of 2 or more and less than 4 can be produced with advantage as described above. Thereby, efficient light emission characteristics can be realized and the center of light emission can be controlled. The emission center wavelength can be changed by controlling the content of the reducing agent and the synthesis time.

  According to the present embodiment, since the light emitted from the light emitting glass 6 is continuous spectrum light, excellent color rendering can be realized. In particular, when continuous spectrum light is continuous in the visible light region of 400 to 800 nm, an excellent color rendering property close to natural white can be realized. Further, since the output is continuous spectrum light, it is difficult to be influenced by light from the light source 5, and an output with a stable color temperature can be obtained.

  Moreover, since no transparent resin is used, deterioration due to ultraviolet rays hardly occurs. Moreover, since glass is used, it can be processed freely by pressing the softened one.

  Furthermore, since no phosphor is used, it is not necessary to manufacture the phosphor, and it is not necessary to mix the phosphor and the resin, so that the manufacturing cost can be reduced. In addition, since tin oxide is inexpensive, when manufacturing a luminescent glass containing tin oxide, the manufacturing cost can be further reduced.

  The present invention will be described in detail by way of examples, but the scope of the present invention is not limited by the examples. In this example, the light-emitting glass described in the above embodiment mode was manufactured and various experiments were performed.

Example 1
First, a light emitting glass as a sample was produced. Specifically, a mixture of SiO ₂ , H ₃ BO ₃ , Na ₂ CO ₃ , SnO ₂ , Si, and BaCO ₃ so as to have the following raw material composition is used at 1400 ° C. for 2 hours in an electric furnace. After being heated and melted, the molten glass composition was poured out on a carbon plate and rapidly cooled to room temperature to obtain a luminescent glass having a size of 1 mm × 10 mm × 10 mm. In addition, content of the tin oxide contained in this glass was about 15 mol%.
SiO ₂ 50 mol%
B ₂ O ₃ 15 mol%
Na ₂ O 8mol%
SnO ₂ 15 mol%
Si 7mol%
BaO 5mol%

  In order to investigate the emission characteristics of the luminescent glass thus obtained, emission was examined when excited with ultraviolet light having a wavelength of 360 nm using a fluorescence spectrophotometer (F-4800, manufactured by Hitachi, Ltd.). The obtained emission spectrum is shown in FIG. As shown in FIG. 2, when excited at a wavelength of 360 nm, continuous spectrum light was emitted in the wavelength region of 400 to 800 nm. From this result, it was confirmed that when this light emitting glass was provided on an ultraviolet diode, a white light emitting diode was obtained.

Example 2
A light-emitting glass was placed on an ultraviolet diode that emits ultraviolet light having a wavelength of 365 nm, and the color rendering properties were examined when light was emitted by being excited by ultraviolet light from the ultraviolet diode. The luminescent glass used was the same as the luminescent glass of Example 1 except that the thickness was 5 mm.

  The color rendering property Ra of light emitted from the luminescent glass was 93.

Example 3
The emission characteristics of the luminescent glass when excited by ultraviolet light having a wavelength of 300 nm or less were examined. The same light emitting glass as in Example 1 was used as the light emitting glass in this example. FIG. 3 is a graph showing a transmittance curve of the luminescent glass with respect to the wavelength.

  As shown in FIG. 3, it can be seen that this luminescent glass hardly transmits ultraviolet rays having a wavelength of 300 nm or less. Here, currently commercialized ultraviolet diodes mainly emit light having wavelengths of 365 nm and 375 nm, but are preferably excited by ultraviolet rays having a short wavelength as much as possible from the viewpoint of emission intensity. Therefore, light emission when excited by ultraviolet rays having wavelengths of 255 nm, 280 nm, and 300 nm was examined. The obtained emission spectrum is shown in FIG.

  As shown in FIG. 4, broad emission (emission peak wavelength is 450 nm to 500 nm) is obtained in the wavelength region of 400 to 800 nm in any of the cases where excitation is performed at wavelengths of 255 nm, 280 nm, and 300 nm. The emission intensity was almost the same. From this result, it was confirmed that usable brightness was obtained even when excited with ultraviolet rays having a wavelength of 300 nm or less.

Example 4
A luminescent glass having the same composition as in Example 1 is placed on a black light (low pressure mercury lamp, central wavelength 254 nm, 365 nm, sample incident surface ultraviolet ray intensity 1.4 mW / cm ² ) in a dark room with a power of 4 W, and a wavelength of 255 nm. The luminance of light emitted from the glass was measured with a luminance meter (MINOLTA LS-110) while irradiating ultraviolet rays having a wavelength of 365 nm. The measured results are shown in Table 1.

  In general, the emission intensity becomes higher when excited by short-wave ultraviolet light, so it is considered better to excite at a wavelength of 254 nm than at a wavelength of 365 nm. When it was thicker than the glass thickness, as shown in Table 1, the luminance when excited at a wavelength of 254 nm and a wavelength of 365 was approximately the same. From this result, it was confirmed that both the wavelength 254 nm and the wavelength 365 nm can be used as the excitation light.

  Further, when the light transmittance of glass at a wavelength of 254 nm is compared with the light transmittance of glass at a wavelength of 365 nm, the light transmittance at a wavelength of 365 nm is higher than the light transmittance at a wavelength of 254 nm. This means that, when excited at a wavelength of 254 nm, ultraviolet light having a wavelength of 254 nm is hardly transmitted, so that light is emitted almost only on the glass surface, whereas when excited at a wavelength of 365 nm, ultraviolet light having a wavelength of 365 nm is transmitted to some extent. Therefore, it means that light is emitted not only on the glass surface but also inside the glass. Therefore, the actual light emission region is smaller than that when excited at a wavelength of 365 nm than when excited at a wavelength of 254 nm. From this, it was confirmed that when the same brightness was obtained in the case where excitation was performed at a wavelength of 254 nm and a wavelength of 365 nm, the thickness of the glass could be reduced by excitation with ultraviolet light having a wavelength of 254 nm.

  DESCRIPTION OF SYMBOLS 1 ... Illuminating device, 2 ... Base material, 2a ... Recessed part, 3 ... Reflecting layer, 4 ... Lead, 5 ... Light source, 6 ... Luminescent glass, 6a ... Absorbing film.

Claims (8)

A lighting device comprising a light source and a luminescent glass covering at least a part of the light source,
The luminescent glass is excited by light having a wavelength shorter than the absorption edge wavelength of the luminescent glass emitted from the light source, and emits continuous spectrum light having a wavelength longer than the wavelength that excites the luminescent glass, Lighting device.   The lighting device according to claim 1, wherein a wavelength of light emitted from the light source exists in a complete absorption region of the luminescent glass.   The lighting device according to claim 1, wherein the light emitting glass has unevenness formed on a surface other than the surface on the light source side.   The lighting device according to claim 1, wherein the light emitting glass further includes a film that reflects or absorbs a specific light component from the light emitting glass formed on a surface other than the light source side surface. .   The illuminating device according to claim 1, wherein the light emitted from the light source is ultraviolet light. The luminescent glass is made of a glass material, SnO ₂ having a content of 1 mol% or more, and a raw material containing a reducing agent, and contains tin oxide obtained by reducing SnO ₂ with the reducing agent. The lighting device according to any one of 1 to 5.   The lighting device according to claim 6, wherein the glass material is soda borosilicate glass.   The lighting device according to claim 1, wherein the continuous spectrum light is continuous in a wavelength region of at least 400 to 800 nm.

Images