JP2003317517A - Light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device which can assure a high efficiency of light emission generated from a light emitting means and moreover can miniaturize cameras, projectors, and other optical apparatuses. <P>SOLUTION: The light source device comprises a reflection means 3 projecting light illuminated from a light emitting tube 2 forward, where the reflection means 3 comprises: a main reflection part 32 reflecting the visible light of incident light illuminated from the light emitting tube 2 and transmitting infrared light; a transparent part 31 transmitting the infrared light, which is illuminated from the light emitting tube 2 and passes through the main reflection part 32; a wavelength conversion part 33 made of a wavelength conversion film which excites visible light when the infrared light passing through the transparent part 31 enters; and an auxiliary reflection part 34 reflecting the visible light wavelength-converted by a wavelength conversion part 33. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device suitable for use in a flash, a projector, a vehicle lighting device, or the like.

[0002]

2. Description of the Related Art In recent years, as the size of a camera has been reduced, the efficiency of a light emitting portion in a light source device such as a flash has been improved. Usually, for example, xenon (X
e) An arc tube such as a tube, and a reflecting mirror that reflects the light emitted from the arc tube and effectively irradiates and projects light on a subject.

As a method of irradiating and projecting light from the arc tube with high efficiency, the reflectance of a reflecting mirror is increased or a prism is used as described in JP-A-4-275535. Total reflection is performed.

[0004]

By using these methods, it is possible to improve the reflectance of the irradiation light from the arc tube. However, such improvement of the reflectance does not further improve the efficiency of the irradiation light. The limit is approaching. By the way, normally, in a camera using a film of silver chloride (silver halide), visible light, that is, about 380 nm to 78 nm.
Although light in the wavelength range of 0 nm is used, light from the arc tube used for a light source device such as a flash does not necessarily irradiate only necessary light in the visible light range.

For example, from a xenon tube used as an arc tube for a light source device such as a flash, as shown in FIG. 8, in addition to visible light occupying about 40%, infrared light and ultraviolet light are simultaneously irradiated. Has been done. Of these, the ratio of ultraviolet light to the irradiation light is usually about 5%, which is very small, so that the utilization effect cannot be expected so much. However, infrared light accounts for a relatively large ratio of about 55%. Despite this, this effective use is rarely made.

In view of the above circumstances, the present invention can improve the efficiency of the irradiation light from the arc tube.
Furthermore, it is an object of the present invention to provide a light source device that enables miniaturization of optical devices such as cameras and projectors.

[0007]

First, an invention according to claim 1 is a light source device comprising a light emitting means and a reflecting means for projecting light emitted from the light emitting means toward the front. The reflecting means includes a transparent portion formed of a transparent member capable of transmitting infrared light that has passed through the main reflecting mirror of the light emitted from the light emitting means, and the light emitted from the light emitting means is incident on the transparent portion. Of the light that reflects visible light and transmits infrared light through a main light reflecting film, and a wavelength conversion that excites the visible light when the infrared light that has passed through the main light reflecting portion is incident. It is characterized by comprising a wavelength conversion part formed of a film and an auxiliary reflection part formed of at least a reflection film that reflects visible light that has been wavelength-converted by the wavelength conversion part and is transmitted.

As a result, it becomes possible to utilize the infrared light which has not been effectively utilized among the emitted light from the light emitting means, thereby improving the efficiency of the emitted light from the light emitting means. You can As a result, for example,
It is possible to reduce the capacity of the driving capacitor of the light emitting means, and to that extent, it is possible to reduce the size of a device such as a camera or projector equipped with this light source device or a vehicle lighting fixture.

Secondly, in the invention according to claim 2, the auxiliary reflection section reflects the wavelength-converted visible light and the unconverted infrared light which has not been converted by the wavelength conversion section. You may comprise.

As a result, the unconverted infrared light can be reflected by the auxiliary reflection portion, and the wavelength conversion function of the unconverted infrared light can be performed again by the wavelength conversion portion, and the wavelength conversion efficiency can be doubled. become able to. As a result, it becomes possible to convert the infrared light into visible light with higher efficiency and increase the irradiation light amount or irradiation intensity of visible light.

Thirdly, in the invention according to claim 3, at the same time that the auxiliary reflection portion reflects the wavelength-converted visible light, the unconverted infrared light not converted by the wavelength conversion portion. It may be configured to transmit light.

This makes it possible to effectively transmit / emit unconverted infrared light out of infrared light, which is a kind of heat rays, to the outside. Therefore, by using, for example, a halogen tube in which infrared rays occupy a large proportion of the emitted light as the light emitting means, the problem of heat generation in a vehicle lighting device, a projector, or the like, which is likely to adversely affect peripheral devices due to heat generation, is simultaneously solved. It can be resolved.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. [First Embodiment] FIG. 1 shows a flash device of a camera to which a light source device according to a first embodiment of the present invention is applied.
Further, it is provided with an arc tube 2 which is a light emitting means, a reflecting means 3, and a protector lens (not shown) for protecting the light emitting means, the reflecting means 3 and the like.

As the arc tube 2, a xenon (Xe) discharge tube is used in this embodiment, and a main reflection part 3 described later is used.
2 is provided at one focal position. Further, both end portions of the arc tube 2 projecting to the left and right are supported by support members (not shown). This support member is provided with a trigger electrode, and is configured to apply a required trigger voltage to the electrodes at both ends in order to cause the xenon (Xe) discharge tube to perform a light emitting operation. Further, the electrode portion of this support member is connected to a discharge circuit via a lead wire (not shown), and although a capacitor or the like is used in this discharge circuit, the irradiation efficiency is improved compared to the conventional one. Therefore, the capacitor capacity is being reduced.

The arc tube 2 is made up of the xenon (X
e) Other than the discharge tube, for example, a metal halide lamp, a halogen lamp or the like may be used. Of these, the halogen lamp has wavelength distribution characteristics as shown in FIG.
Since about 70% is infrared light, it is possible to greatly improve the utilization efficiency of the light source light, as compared with the case where the infrared light (heat) is allowed to escape.

As shown in FIG. 2, the reflecting means 3 comprises a transparent portion 31, a main reflecting portion 32, a wavelength converting portion 33, and an auxiliary reflecting portion 34. Of these, the transparent portion 31 is an appropriate transparent material that transmits at least a portion of the infrared light transmitted through the main reflecting portion 32, which will be described later, out of the light emitted from the arc tube 2 with a high transmittance, for example, a transparent material. , An acrylic (PMMA) -based, a polycarbonate (PC) -based synthetic resin or the like is used to form an appropriate shape (substantially elliptical in this embodiment), and also serves as a casing for holding the shape.

The main reflection part 32 is for reflecting visible light and transmitting infrared light, and is provided on the surface (inner surface) facing the arc tube 2 provided in the vicinity of one focus position of this ellipse. A visible light reflection film is formed. This visible light reflection film,
It is designed to reflect visible light (light in the wavelength range of about 380 to 780 nm) and transmit infrared light (light with a wavelength of about 780 nm or more), and is a kind of band interference filter called a cold mirror (visible light). Light reflection mirror).

This cold mirror (Diathermy mirror)
Is a structure in which a high-refractive material and a low-refractive material are alternately and repeatedly formed into a thin film in multiple layers. For example, for the high-refractive material (H), TiO ₂ , Ta ₂ O ₅ , and a low-refractive index material ( L)
SiO ₂ and MgF ₂ are used as the material, and when the physical film thickness of these materials is d and the refractive index is n, air / [ ⁽ 0.5H) L (0.5H)] ^{n is} obtained in the following configuration. / Transparent portion However, H; a high refractive index layer of nd = λ / 4 L; a low refractive index layer of nd = λ / 4 is formed.

The visible light reflecting film is, for example, as shown in FIG. 3, a main reflecting portion 32 and a transparent portion 3 from the outside (air).
As for the light in the direction toward 1, the infrared light is transmitted, but the light in the direction from the transparent portion 31 through the main reflection portion 32 to the outside (air) transmits visible light. Is configured to be able to. Also,
In this visible light reflection film, the reflection wavelength range can be set relatively arbitrarily by appropriately adjusting the refractive index and the film thickness of the substance forming the film.

The wavelength conversion unit 33 converts the infrared light having a longer wavelength (low energy) than the visible light transmitted through the transparent unit 31 into visible light having a shorter wavelength (high energy). Yes, it is formed on the back surface (outer surface) of the transparent portion 31. In other words, this wavelength conversion film
When it absorbs, it is excited atomically, and it emits fluorescence (electroluminescence) of light of a shorter wavelength that has a higher energy than this. In the present invention, it is formed of an up-conversion type wavelength conversion material (phosphor). There is.

Specific materials for this wavelength conversion film include a YLiF ₄ crystal doped with Tm ³⁺ and a light-emitting source material composed of an erbium (Er) halide.
It is also possible to use a light-emitting body or the like which contains a gadolinium (Gd) or lanthanum (La) halide as a light emission auxiliary substance and which does not require pre-excitation and has a high light emission efficiency. Further, the wavelength conversion film may be a glassy (amorphous) fluorescent substance such as a fluorescent substance obtained by doping Ho ³⁺ into fluoride glass. The wavelength conversion film can be formed into an arbitrary shape by adding an alkaline earth metal chloride as a glass forming aid to an up-conversion type illuminant. It should be noted that the wavelength conversion film is not particularly limited to that described in this embodiment, and the material and the type of the material are not particularly limited as long as the same effect can be obtained. Are applicable.

The auxiliary reflection portion 34 reflects at least visible light in the wavelength range converted by the wavelength conversion film, and is composed of a dielectric multi-layer film mirror or an ordinary mirror on which aluminum or silver is deposited. ing. In particular, if the infrared light remaining without being wavelength-converted by the wavelength conversion film is also reflected at the same time, unless the light is limited to visible light to be reflected, the latter type of mirror is preferable.

Therefore, according to this embodiment, the arc tube 2
Of the irradiation light from the xenon (Xe) discharge tube, which is the light traveling toward the reflecting means 3, first, only visible light is reflected by the main reflecting portion 32, so that the light is reflected by the main reflecting portion 32. Visible light travels to the front side where the housing 10 is opened,
The light is projected in a certain direction of the subject. On the other hand, of the light traveling toward the reflecting means 3, infrared light is the main reflecting portion 3
The light passes through 2 and enters the transparent portion 31. When the infrared light transmitted through the transparent portion 31 enters the wavelength conversion portion 33, the wavelength conversion film forming the wavelength conversion portion 33 is excited and emits fluorescence. That is, a short wavelength, which has a higher energy than infrared light, that is, visible light is generated.

In this way, of the wavelength-converted visible light, the light further traveling from the wavelength conversion section 33 to the auxiliary reflection section 34 is reflected by the auxiliary reflection section 34 and goes backward in the original direction. . That is, the wavelength conversion unit 33 and the transparent unit 3
First, the light passes through the main reflecting portion 32, travels forward, and is projected onto the subject. On the other hand, out of the wavelength-converted visible light, the light traveling in the direction opposite to the auxiliary reflection portion 34 does not reflect at the auxiliary reflection portion 34 but goes backward, and passes through the transparent portion 31 and the main reflection portion 32 again. Then, it travels forward and is projected onto the subject.

In this embodiment, as the reflecting means 3, a semi-elliptical cylindrical shape having an approximately elliptical shape with the same cross section and extending in the longitudinal direction of the arc tube 6 is used, but the reflecting means 3 is not particularly limited to this shape. Absent.

For example, as in the vehicle lighting lamp shown in FIGS. 4 and 5, the reflecting means 3 may be one in which a cut surface parallel to the longitudinal direction of the arc tube 6 is formed in a substantially parabolic shape. . Further, in this case, for example, a halogen lamp may be used as the arc tube 6 instead of the xenon lamp. In the case of this halogen lamp as well, similar to the xenon lamp, the auxiliary reflection section 34 has exactly the same spectral characteristics and is configured to reflect both infrared light and visible light.

[Second Embodiment] Next, a second embodiment according to the present invention will be described with reference to FIG. In this embodiment, the same parts as those in the first embodiment are designated by the same reference numerals to avoid redundant description. Contrary to the first embodiment, in the second embodiment, the auxiliary reflector 36 reflects the wavelength-converted visible light, and at the same time, the unconverted infrared light not converted by the wavelength conversion film 33. It is configured to transmit light backward.

Therefore, according to this structure, when the illuminating device is applied to, for example, a liquid crystal projector or a luminaire, heat dissipation can be improved, so that various parts in these devices and luminaires can be connected to the arc tube. It is possible to prevent exposure to heat.

[0029]

As described above, according to the present invention, there is provided a light source device comprising the light emitting means and the reflecting means for projecting the light emitted from the light emitting means toward the front. Means, a transparent portion capable of transmitting infrared light of the light emitted from the light emitting means, a main reflection portion that reflects visible light and transmits infrared light of the light emitted from the light emitting means and incident, A wavelength conversion unit configured by a wavelength conversion film that excites visible light when infrared light transmitted through this visible light reflection unit is incident, and an auxiliary reflection unit that reflects visible light wavelength-converted by at least this wavelength conversion unit. Is equipped with.

Therefore, according to the present invention, of the irradiation light from the light emitting means, the infrared light which has not been effectively utilized until now can also be used as the light for illumination or the like, and the irradiation light from the light emitting means can be used. High efficiency can be achieved. As a result, for example, even when the same light emitting means is used to obtain the same amount of light, it is possible to reduce the capacity of the capacitor used for driving the light emitting means, and accordingly, a camera equipped with this light source device can be used. It is possible to reduce the size of a device such as a projector or a vehicle lighting device.

[Brief description of drawings]

FIG. 1 is a perspective view showing a light source device according to a first embodiment of the present invention.

2 is a cross-sectional view of a main part of the light source device shown in FIG.

FIG. 3 is an explanatory diagram showing an operation of the first embodiment.

FIG. 4 is a perspective view showing a light source device according to a second embodiment.

5 is a partial cross-sectional view of the light source device shown in FIG.

FIG. 6 is a graph showing the spectral characteristics of the halogen lamp used as the arc tube of the first embodiment.

FIG. 7 is an explanatory diagram showing an operation of the second embodiment.

FIG. 8 is a graph showing a spectral characteristic of a xenon lamp and a wavelength distribution of natural daylight.

[Explanation of symbols]

1 Flash device 2 Arc tube (light emitting means; xenon (Xe) discharge tube) 3 reflection means 31 Transparent part 32 Main reflector 33 Wavelength converter 34 Auxiliary reflector (infrared and visible light reflection) 36 Auxiliary reflector (cold mirror, infrared light transmission) 5 Lighting lamp 6 Arc tube (light emitting means; halogen lamp)

Claims (3)

[Claims] 1. A light source device comprising: a light emitting means; and a reflecting means for projecting light emitted from the light emitting means forward, wherein the reflecting means emits light emitted from the light emitting means. A transparent portion formed of a transparent member that can transmit infrared light that has passed through the main reflecting mirror, and visible light that reflects infrared light that is transmitted from the light emitting means and is incident infrared light. A main reflection part formed of a visible light reflection film, a wavelength conversion part formed of a wavelength conversion film that excites visible light when the infrared light transmitted through the main reflection part is incident, and a wavelength at least in the wavelength conversion part. A light source device, comprising: an auxiliary reflection portion formed of a reflection film that reflects visible light that is converted and transmitted. 2. The auxiliary reflection unit is configured to reflect the wavelength-converted visible light and the unconverted infrared light that has not been wavelength-converted by the wavelength conversion unit. The light source device according to. 3. The auxiliary reflector reflects the visible light wavelength-converted by the wavelength converter and at the same time transmits the unconverted infrared light not wavelength-converted by the wavelength converter. The light source device according to claim 1, wherein: