JP2005070518A - Light source device, illumination optical device, and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device for preventing the damage of a collimating concave lens caused by thermal distortion and also preventing a size increase, and to provide an illumination optical device and a projector equipped with the illumination optical device. <P>SOLUTION: A collimating concave lens 74 is arranged in the vicinity of the 2nd focus of an elliptical reflector 72, and has a thermal expansion coefficient of ≤40×10<SP>-7</SP>/°C and a heat resistance temperature of ≥300°C. For example, borosilicate glass, high silica glass whose silicic acid content is ≥96%, quartz glass and crystallized glass or the like all having a thermal expansion coefficient of ≤33×10<SP>-7</SP>/°C are included as the material of the lens 74. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light source device, an illumination optical device, and a projector.

2. Description of the Related Art Conventionally, a projector including a light modulation device that modulates a light beam emitted from a light source lamp according to image information and a projection optical system that enlarges and projects the light beam modulated by the light modulation device has been used.
In such a projector, an illumination optical device including a plurality of optical elements is provided in order to uniformly illuminate an image forming area of the light modulation device without unevenness.
This illumination optical device includes a light source device and a uniform illumination optical system having a function of dividing a light beam from the light source device into a plurality of partial light beams and superimposing them on an image forming region of the light modulation device.
The light source device has a light emitting tube (light source lamp) as a radiation light source, an elliptical reflector, and a collimating concave lens, and the radial light beam emitted from the light source lamp is reflected by the reflector and emitted to be collimated. Parallelized with a concave lens.
Since the convergent light emitted from the elliptical reflector is incident on the collimating concave lens, thermal distortion is likely to occur. In particular, since the luminance of light from the light source lamp is highest near the second focal point of the elliptical reflector, if a collimating concave lens is arranged near the second focal point, thermal distortion may occur in the collimating concave lens, which may be damaged. .
Therefore, it has been proposed to prevent the occurrence of thermal distortion by installing the collimating concave lens at an intermediate position between the first focal point and the second focal point of the elliptical reflector, and disposing the collimating concave lens in a portion having low luminance ( For example, see Patent Document 1)

JP 2000-347293 A (page 5, FIG. 3)

  However, in such a method, the collimating concave lens must be arranged closer to the ellipsoidal reflector than the second focal point of the ellipsoidal reflector, and the light beam enters the collimating concave lens before the luminous flux from the elliptical reflector is sufficiently converged. Therefore, it is necessary to increase the light beam incident area of the collimating concave lens. Therefore, there is a problem that the light source device and the illumination optical device are increased in size.

  An object of the present invention is to provide a light source device, an illumination optical device, and a projector that can prevent the collimated concave lens from being damaged due to thermal distortion and can prevent an increase in size.

The light source device of the present invention includes an arc tube, an elliptical reflector that emits the luminous flux emitted from the luminous tube in a fixed direction, and a parallelizing concave lens that collimates the luminous flux reflected by the elliptical reflector. In the light source device, the collimating concave lens is disposed in the vicinity of a second focal point of the elliptical reflector, and the collimating concave lens has a thermal expansion coefficient of 40 × 10 ⁻⁷ / ° C. or less and a heat resistant temperature of 300 ° C. or more. It is characterized by being.
Here, the vicinity of the second focal point of the elliptical reflector means a position where the shadow of the arc tube starts to disappear. For example, if the elliptical reflector has a first focal length of 12 mm and a second focal length of 84 mm (72 mm from the bright spot), it is parallelized to a position of 55 mm, that is, a position 17 mm before the second focal position (elliptical reflector side). Install a concave lens. Further, when the first focal length of the elliptical reflector is 12 mm and the second focal length is 60 mm (48 mm from the bright spot), a collimating concave lens is installed at a position 13 mm before (ellipse reflector side) from the second focal position.
According to the present invention, the collimating concave lens has a thermal expansion coefficient of 40 × 10 ⁻⁷ / ° C. or lower and a low thermal expansion coefficient. Therefore, the elliptical reflector is the position where the luminance of light from the arc tube is highest. Even when a collimating concave lens is disposed near the second focal point, thermal distortion is unlikely to occur. Thereby, the damage by the thermal strain of the collimating concave lens can be prevented.
In addition, since the heat-resistant temperature of the collimating concave lens is 300 ° C. or higher, it is possible to prevent alteration due to heat.
Furthermore, since the collimating concave lens is disposed in the vicinity of the second focal point of the elliptical reflector, a sufficiently converged light beam is incident on the collimating concave lens. Therefore, it is not necessary to ensure a large light beam incident area of the collimating concave lens, thereby preventing an increase in the size of the light source device.

Here, examples of the material for the collimating concave lens include borosilicate glass having a thermal expansion coefficient of 33 × 10 ⁻⁷ / ° C. or less, high silicate glass having a silicic acid content of 96% or more, quartz glass, and crystallized glass. Of these, borosilicate glass having a thermal expansion coefficient of 33 × 10 ⁻⁷ / ° C. or less is preferable because it is inexpensive. Here, as the borosilicate glass having a thermal expansion coefficient of 33 × 10 ⁻⁷ / ° C. or less, for example, Pyrex (registered trademark) manufactured by Corning Glass, Tempax (trade name) manufactured by Schott, or the like can be used. .

Furthermore, in the present invention, it is preferable that the collimating concave lens has a thickness dimension of 2 mm or more along the light beam transmission direction.
According to the present invention as described above, the collimated concave lens can be used as explosion-proof glass by setting the thickness dimension along the light beam transmission direction of the collimated concave lens to 2 mm or more. That is, by attaching the collimating concave lens so as to cover the opening of the elliptical reflector, it is possible to prevent the fragments from being scattered when the arc tube is ruptured. When the thickness dimension of the collimating concave lens is less than 2 mm, the collimating concave lens is also damaged along with the rupture of the arc tube, so that it is difficult to use as an explosion-proof glass.

An illumination optical device according to the present invention is an illumination optical device for illuminating a light modulation device that modulates a light beam emitted from a light source according to image information to form an optical image. A beam splitting optical element configured to divide the light beam emitted from the light source device into a plurality of partial light beams, and to split the light beam. And a condensing lens that superimposes the partial light beams divided by the optical element on the image forming area of the light modulation device.
The projector according to the present invention includes such an illumination optical device.
Such an illumination optical device and projector according to the present invention include the above-described light source device, and therefore can achieve the same effects as the light source device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing the structure of an optical system of a projector 1 according to an embodiment of the present invention. The projector 1 is an optical device that modulates a light beam emitted from a light source in accordance with image information to form an optical image and projects it on a screen in an enlarged manner. The projector illumination optical system (illumination optical device) 10, color The optical system includes a separation optical system 20, a relay optical system 30, an optical device 40, a cross dichroic prism 50 that is a color synthesis optical system, and a projection lens 60 that is a projection optical system. Although not shown, the optical elements constituting the optical systems 10 to 50 are positioned and accommodated in an optical component casing called a light guide in which a predetermined illumination optical axis is set.
The illumination optical device 10 includes a light source device 70 and a uniform illumination optical system 80, and the light source device 70 includes a light source lamp 71 (light emission tube), an elliptic reflector 72 that reflects a light beam emitted from the light source lamp 71, and a sub-light source. A reflecting mirror 73 and a collimating concave lens 74 are provided.
The uniform illumination optical system 80 divides the light beam emitted from the light source device 70 into a plurality of partial light beams, and aligns the polarization direction of each partial light beam with a P-polarized light beam or an S-polarized light beam. A first lens array 81, a second lens array 82 that is a condensing lens, a polarization conversion element 83, and a condenser lens 84 that is a condensing lens are configured.
Details of the light source device 70 will be described later.

  The color separation optical system 20 includes two dichroic mirrors 21 and 22 and a reflection mirror 23. A plurality of partial light beams emitted from the illumination optical device 10 by the dichroic mirrors 21 and 22 are converted into red (R) and green ( G) and blue (B) have a function of separating into three color lights.

  The relay optical system 30 includes an incident side lens 31, a relay lens 33, and reflection mirrors 32 and 34, and has a function of guiding red light, which is color light separated by the color separation optical system 20, to the liquid crystal panel 41R. ing.

  At this time, the dichroic mirror 21 of the color separation optical system 20 transmits red light and green light and reflects blue light among the light beams emitted from the illumination optical device 10. The blue light reflected by the dichroic mirror 21 is reflected by the reflection mirror 23, passes through the field lens 44, and reaches the blue liquid crystal panel 41B. The field lens 44 converts each partial light beam emitted from the second lens array 82 into a light beam parallel to the central axis (principal light beam). The same applies to the field lens 44 provided on the light incident side of the other liquid crystal panels 41G and 41R.

Of the red light and green light transmitted through the dichroic mirror 21, the green light is reflected by the dichroic mirror 22, passes through the field lens 44, and reaches the green liquid crystal panel 41G. On the other hand, the red light passes through the dichroic mirror 22, passes through the relay optical system 30, passes through the field lens 44, and reaches the liquid crystal panel 41R for red light.
The relay optical system 30 is used for red light because the optical path length of the red light is longer than the optical path lengths of the other color lights, thereby preventing a decrease in light utilization efficiency due to light divergence or the like. Because. That is, this is to transmit the partial light beam incident on the incident side lens 31 to the field lens 44 as it is. The relay optical system 30 is configured to pass red light of the three color lights, but is not limited thereto, and may be configured to pass blue light, for example.

  The optical device 40 modulates an incident light beam according to image information to form a color image, and includes three incident-side polarizing plates (illustrated) on which the respective color lights separated by the color separation optical system 20 are incident. ), A field lens 44 arranged on the incident side of the incident side polarizing plate, a liquid crystal panel 41 (41R, 41G, 41B) as a light modulation device arranged in the subsequent stage of each incident side polarizing plate, and each liquid crystal An exit-side polarizing plate (not shown) disposed at the rear stage of the panels 41R, 41G, and 41B and a cross dichroic prism 50 as a color synthesis optical system are provided.

The liquid crystal panels 41R, 41G, and 41B are obtained by hermetically enclosing a liquid crystal that is an electro-optical material between a pair of transparent glass substrates. For example, a polysilicon TFT is used as a switching element and is incident on the incident side according to a given image signal. Modulates the polarization direction of the polarized light beam emitted from the polarizing plate. The image forming areas of the liquid crystal panels 41R, 41G, 41B are rectangular.
The incident-side polarizing plate is an optical conversion element that transmits only a polarized light beam in a certain direction and absorbs other light beams among the respective color lights separated by the color separation optical system 20. The exit side polarizing plate also transmits only a polarized light beam in a predetermined direction among light beams emitted from the liquid crystal panel 41 and absorbs other light beams.
The field lens 44 is an optical element for making the emitted light beam narrowed down by the condenser lens 84 of the illumination optical device 10 parallel to the illumination optical axis.

The cross dichroic prism 50 forms a color image by synthesizing optical images emitted from the exit-side polarizing plate and modulated for each color light.
The cross dichroic prism 50 is provided with a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light in a substantially X shape along the interface of four right-angle prisms. Three color lights are synthesized by the multilayer film.
The color image emitted from the cross dichroic prism 50 is enlarged and projected by the projection lens 60 to form a large screen image on a screen (not shown).

The light source device 70 will be described with reference to FIGS.
The light source device 70 includes a lamp housing 75 and a cover member 76 in addition to the light source lamp 71, the elliptical reflector 72, the sub-reflecting mirror 73, and the collimating concave lens 74 described above.
The light source lamp 71 as a light-emitting tube is composed of a quartz glass tube having a central portion swelled in a spherical shape. The central portion is a light-emitting portion 711, and portions extending on both sides of the light-emitting portion 711 are sealing portions 712.

Although not shown in FIG. 3, a pair of tungsten electrodes, which are spaced apart from each other by a predetermined distance, and mercury, a rare gas, and a small amount of halogen are enclosed inside the light emitting portion 711.
Inside the sealing portion 712, a molybdenum metal foil that is electrically connected to the electrode of the light emitting portion 711 is inserted and sealed with a glass material or the like. A lead wire 713 as an electrode lead wire is further connected to the metal foil, and the lead wire 713 extends to the outside of the light source lamp 71.
When a voltage is applied to the lead wire 713, discharge occurs between the electrodes, and the light emitting unit 711 emits light.

The elliptical reflector 72 is an integrally molded product made of glass provided with a neck-shaped portion 721 through which the sealing portion 712 of the light source lamp 71 is inserted and an elliptically curved reflecting portion 722 extending from the neck-shaped portion 721.
An insertion hole 723 is formed at the center of the neck portion 721, and a sealing portion 712 is disposed at the center of the insertion hole 723.
The reflection part 722 is formed by vapor-depositing a metal thin film on an elliptically curved glass surface, and the reflection surface of the reflection part 722 is a cold mirror that reflects visible light and transmits infrared rays.
The light source lamp 71 is disposed inside the reflecting portion 722 so that the light emission center between the electrodes in the light emitting portion 711 is the first focal position of the elliptical curved surface of the reflecting portion 722.
When the light source lamp 71 is turned on, the light beam emitted from the light emitting unit 711 is reflected by the reflecting surface of the reflecting unit 722 and becomes convergent light that converges to the second focal position of the elliptical curved surface.

When fixing the light source lamp 71 to such an elliptical reflector 72, the sealing part 712 of the light source lamp 71 is inserted into the insertion hole 723 of the elliptical reflector 72, and the light emission center between the electrodes in the light emitting part 711 is the reflecting part. It arrange | positions so that it may become the 1st focus of the elliptical curved surface of 722, and it fills the inside of the insertion hole 723 with the inorganic type adhesive which has a silica and an alumina as a main component. In this example, the lead wire 713 extending from the front sealing portion 712 is also exposed to the outside through the insertion hole 723.
Further, the dimension in the optical axis direction of the reflection part 722 is shorter than the length dimension of the light source lamp 71. When the light source lamp 71 is fixed to the elliptical reflector 72 in this way, the sealing part on the front side of the light source lamp 71 is provided. 712 protrudes from the light beam exit opening of the elliptical reflector 72.

The sub-reflecting mirror 73 is a reflecting member that covers approximately the front half of the light emitting part 711 of the light source lamp 71 in the light emission direction. Although not shown, the reflecting surface is formed in a concave curved surface that follows the spherical surface of the light emitting part 711. The reflection surface is a cold mirror like the elliptical reflector 72.
By attaching the sub-reflecting mirror 73 to the light-emitting unit 711, the light beam radiated to the front side of the light-emitting unit 711 is reflected by the sub-reflecting mirror 73 toward the elliptical reflector 72, and from the reflecting unit 722 of the elliptical reflector 72 It is injected.
By using the sub-reflecting mirror 73 in this way, the light beam radiated to the front side of the light emitting unit 711 is reflected to the rear side, so that even if the elliptical curved surface of the reflecting unit 722 is small, it is emitted from the light emitting unit 711 All the luminous fluxes can be emitted in a fixed direction, and the size of the elliptical reflector 72 in the optical axis direction can be reduced.

The collimating concave lens 74 is for collimating the light beam emitted from the light source lamp 71, and is disposed near the second focal point of the elliptical reflector 72. Here, the vicinity of the second focal point of the elliptical reflector 72 refers to a position where the shadow of the light source lamp 71 starts to disappear. For example, as shown in FIG. 4, when the first focal length f1 of the elliptical reflector 72 is 12 mm and the second focal length f2 is 84 mm (72 mm from the bright spot), the position is 55 mm, that is, 17 mm before the second focal position. A collimating concave lens 74 is installed at the position of the ellipse reflector side. When the first focal length f1 of the elliptical reflector 72 is 12 mm and the second focal length f2 is 60 mm (48 mm from the bright spot), the collimating concave lens 74 is placed at a position 13 mm before (ellipse reflector side) from the second focal position. Install.
As shown in FIG. 3, the collimated concave lens 74 has a light incident surface 741 that is an aspheric surface, for example, a hyperboloid concave surface, and a light exit surface 742 that is a flat surface. Of the thickness dimension along the light beam transmission direction of the collimating concave lens 74, the dimension T1 between the thinnest portion, that is, the portion of the concave surface that is most concave on the light beam exit surface 742 side, and the light exit surface 742 is: It is 2 mm or more, for example, 3 mm. The diameter of the collimating concave lens 74 is, for example, about 20 mm.
An antireflection film (AR film) 741A is applied to the light incident surface 741 of the collimating concave lens 74. By doing in this way, the utilization efficiency of light can be improved. Further, an ultraviolet cut film 742A is formed on the light exit surface 742 of the collimating concave lens 74. The ultraviolet cut film 742 </ b> A prevents ultraviolet rays from being reflected by reflecting the ultraviolet rays, thereby preventing the ultraviolet rays from being emitted from the light source device 70. The ultraviolet cut film 742A is a general ultraviolet cut film on the assumption that the incident light beam is parallel light.

The collimating concave lens 74 as described above has a thermal expansion coefficient of 40 × 10 ⁻⁷ / ° C. or lower and a heat resistant temperature of 300 ° C. or higher. The material of the collimating concave lens 74 is, for example, a thermal expansion coefficient of 33. Examples thereof include borosilicate glass of not more than 10 ⁻⁷ / ° C., high silicate glass having a silicic acid content of 96% or more, quartz glass, crystallized glass and the like.
Examples of the borosilicate glass having a thermal expansion coefficient of 33 × 10 ⁻⁷ / ° C. or less include, for example, Pyrex (registered trademark) manufactured by Corning Glass Co., Ltd. (thermal expansion coefficient 33 × 10 ⁻⁷ / ° C., heat resistant temperature 500 ° C.), Schott Tempax (trade name) (thermal expansion coefficient 33 × 10 ⁻⁷ / ° C., heat resistant temperature 500 ° C.).
As a high silicate glass having a silicic acid content of 96% or more, borosilicate glass (Na ₂ OB ₂ O ₃ —SiO ₂ ) is heated to 600 ° C. to cause phase separation, and Na ₂ OB ₂ O ₃ and SiO ₂ After the two phases are separated, an entangled state is created, and Na ₂ OB ₂ O ₃ is dissolved in concentrated hydrochloric acid to produce a glass composed of SiO _{2 with} a purity of about 96%, which is obtained by heating. Examples thereof include Vycor (trade name) manufactured by Corning Glass (thermal expansion coefficient 7.5 × 10 ⁻⁷ / ° C., heat resistant temperature 1200 ° C.).
An example of crystallized glass is Neoceram (trade name) (thermal expansion coefficient -7 × 10 ^-7 / ° C.) manufactured by Nippon Electric Glass Co., Ltd.
Among them, Pyrex (registered trademark) and Tempax (trade name) exemplified as borosilicate glass having a thermal expansion coefficient of 33 × 10 ⁻⁷ / ° C. or less are inexpensive, and it is preferable to use these.

As shown in FIG. 3, the lamp housing 75 is an integrally molded product made of synthetic resin having an L-shaped cross section, and includes a horizontal portion 751 and a vertical portion 752.
The horizontal portion 751 is a portion that engages with the wall portion of the light guide and hides the light source device 70 in the light guide to prevent light leakage. Although not shown, the horizontal portion 751 is provided with a terminal block for electrically connecting the light source lamp 71 to an external power source. The lead wire 713 of the light source lamp 71 is provided on the terminal block. Is connected.

The vertical portion 752 is a portion for positioning the elliptical reflector 72 in the optical axis direction. In this example, the front end portion of the elliptical reflector 72 on the light beam emission opening side is fixed to the vertical portion 752 with an adhesive or the like. The vertical portion 752 is formed with an opening 753 that transmits the light beam emitted from the elliptical reflector 72.
Further, projections 754 are formed on the horizontal portion 751 and the vertical portion 752. The protrusion 754 engages with the concave portion formed in the light guide described above, and when engaged, the light emission center of the light source lamp 71 is disposed on the illumination optical axis of the light guide.

The cover member 76 is attached so as to cover the light beam emission opening of the elliptical reflector 72, and a heat absorption part 761 formed of a substantially circular cylindrical body attached to the opening 753 of the vertical part 752 of the lamp housing 75. The plurality of heat dissipating fins 762 projecting outside the heat absorbing portion 761 and the lens mounting portion 763 formed at the tip of the heat absorbing portion 761 are configured as a metal integrally molded product.
The heat absorption part 761 is a part that absorbs radiant heat radiated from the light source lamp 71 and heat of convection air in the sealed space in the elliptical reflector 72 and the cover member 76, and the inner surface thereof is subjected to black anodized treatment. ing. The substantially conical inclined surface of the heat absorbing portion 761 is parallel to the inclination of the convergent light by the elliptical reflector 72. There is no such thing.

The plurality of radiating fins 762 are configured as plate-like bodies extending in a direction perpendicular to the optical axis of the light source device 70, and a gap through which cooling air can be sufficiently passed is formed between the radiating fins 762.
The lens mounting portion 763 is formed of a cylindrical body that protrudes from the tip of the heat absorbing portion 761, and a parallelizing concave lens 74 that parallelizes the convergent light of the elliptical reflector 72 is mounted on this cylindrical portion. Note that the collimating concave lens 74 is fixed to the lens mounting portion 763 with an adhesive or the like, although not shown. When the collimating concave lens 74 is attached to the lens attachment portion 763, the space inside the light source device 70 is completely sealed, and even if the light source lamp 71 is ruptured, fragments are not scattered outside.
Such a light source device 70 is housed in the light guide of the projector 1 described above. Although not shown in FIG. 1, the projector 1 includes a cooling fan disposed adjacent to the light source device 70, and this cooling fan generates cooling air along the extending direction of the heat radiation fins 762 of the cover member 76. It comes to spray. Conversely, the radiation fins may be disposed obliquely to the optical axis according to the direction of the cooling air.
Thus, by providing the radiation fin 762 in the cover member 76, the heat absorbed by the heat absorption part 761 can be efficiently radiated.

Therefore, according to this embodiment, the following effects can be produced.
(1-1) Since the collimating concave lens 74 has a thermal expansion coefficient of 40 × 10 ⁻⁷ / ° C. or less and a low thermal expansion coefficient, the elliptical reflector 72 that has the highest luminance of light from the light source lamp 71 Even if the collimating concave lens 74 is disposed in the vicinity of the second focal point, thermal distortion hardly occurs in the collimating concave lens 74. Thereby, damage due to thermal distortion of the collimating concave lens 74 can be prevented.
In addition, since heat distortion is unlikely to occur in the collimating concave lens 74, the thickness of the collimating concave lens 74 can be ensured, and thereby the strength of the collimating concave lens 74 can be ensured.
In addition, since the heat resistant temperature of the collimating concave lens 74 is 300 ° C. or higher, it is possible to prevent alteration due to heat.

(1-2) Since the collimating concave lens 74 is disposed near the second focal point of the elliptical reflector 72, a sufficiently converged light beam is incident on the collimating concave lens 74. Therefore, it is not necessary to ensure a large light beam incident area of the collimating concave lens 74, and this can prevent the light source device 70 and the illumination optical device 10 from becoming large.
(1-3) Further, in order to seal the inside of the light source device 70 and to have an explosion-proof structure, a flat glass transparent plate or the like is attached to the lens mounting portion 763 of the cover member 76 instead of the parallelizing concave lens 74. However, in this case, since a transparent plate is required in addition to the collimating concave lens 74, the number of members increases. On the other hand, in this embodiment, since the collimating concave lens 74 is attached to the lens mounting portion 763 of the cover member 76, a transparent plate is not necessary, thereby reducing the number of members.

(1-4) When the thickness dimension of the collimated concave lens along the light beam transmission direction is less than 2 mm, the collimated concave lens may be damaged when the light source lamp 71 is ruptured. On the other hand, in this embodiment, since the thickness dimension along the light beam transmission direction of the collimating concave lens 74 is 2 mm or more, the collimating concave lens 74 is less likely to be damaged when the light source lamp 71 is ruptured. In addition, it is possible to prevent the fragments from being scattered when the light source lamp 71 is ruptured.

(1-5) When Pyrex (registered trademark) or Tempax (trade name) exemplified as borosilicate glass having a thermal expansion coefficient of 33 × 10 ⁻⁷ / ° C. or less is used as the material of the collimating concave lens 74 Since these materials are inexpensive, the manufacturing cost of the light source device 70 can be reduced.
Further, when quartz is used as the material of the collimating concave lens 74, since quartz has high thermal conductivity, heat does not accumulate in the collimating concave lens 74, thereby reliably preventing the occurrence of thermal distortion. can do.

(1-6) In this embodiment, the light incident surface 741 of the collimating concave lens 74 is an aspheric concave surface and the light exit surface 742 is a flat surface, so that light is not refracted at the light exit surface 742. The parallelism of the emitted light beam can be increased.
Further, by making the light incident surface 741 of the collimating concave lens 74 concave, it is possible to prevent interference between the collimating concave lens 74 and the sealing portion 712 of the light source lamp 71 or the lead wire 713 connected to the sealing portion 712. .
Furthermore, by making the light incident surface 741 of the collimating concave lens 74 concave, even when the light source lamp 71 is ruptured, it is difficult for fragments of the light source lamp 71 to collide with the collimating concave lens 74, and the collimating concave lens 74 is damaged. It can prevent more reliably.

(1-7) Since the ultraviolet ray cut film 742A is formed on the light exit surface 742 of the collimating concave lens 74, it is possible to prevent ultraviolet rays from being emitted from the light source device 70. Thereby, it can prevent that the liquid crystal panel 41 deteriorates with an ultraviolet-ray.
In addition, when the ultraviolet cut film is applied to the concave surface side of the collimating concave lens, there is a possibility that the characteristics of the ultraviolet cut film cannot be exhibited sufficiently. On the other hand, in this embodiment, since the ultraviolet cut film 742A is formed on the plane side of the collimating concave lens 74, the characteristics of the ultraviolet cut film 742A can be sufficiently exhibited.

(1-8) Furthermore, since the collimating concave lens 74 has a light beam incident surface 741 which is an aspheric concave surface, the collimated concave lens 74 collimates the light beam on the light beam incident surface 741 side, and converts the collimated light beam to the light beam exit surface 742. Ejected from. Therefore, when the ultraviolet cut film is formed on the light incident surface 741, a special ultraviolet cut film corresponding to the incident angle of the light beam must be used. In contrast, in the present embodiment, the ultraviolet ray cut film 742A is formed on the light emission surface 742, and the collimated light beam is incident on the ultraviolet ray cut film 742A. A typical UV cut film 742A can be used. Thereby, the manufacturing cost of the light source device 70 can be reduced.
(1-9) The ultraviolet ray cut film 742A formed on the light exit surface 742 of the collimating concave lens 74 reflects ultraviolet rays to prevent the ultraviolet rays from passing therethrough. The ultraviolet light reflected by the ultraviolet cut film 742A is incident on the light source lamp 71. Since the light source lamp 71 emits light having a longer wavelength than the incident ultraviolet light, the intensity of visible light emitted from the light source lamp 71 is improved. be able to.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the light source device 70 of the above-described embodiment, the inside of the light source device 70 is sealed by mounting the collimating concave lens 74 on the lens mounting portion 763 of the cover member 76. The transparent plate may be mounted on the lens mounting portion 763 of the cover member 76, and a collimating concave lens may be disposed in the subsequent stage to be parallelized.
Furthermore, in the said embodiment, although the thickness dimension of the light beam permeation | transmission direction of the collimating concave lens 74 was 2 mm or more, it is not restricted to this and may be less than 2 mm. In particular, when the collimated concave lens is not used for explosion protection, it may be less than 2 mm.

In the embodiment, the material of the collimating concave lens 74 is a borosilicate glass having a thermal expansion coefficient of 33 × 10 ⁻⁷ / ° C. or less, a high silicate glass having a silicic acid content of 96% or more, quartz glass, and crystallized glass. However, the present invention is not limited to this, and it is optional as long as the thermal expansion coefficient is 40 × 10 ⁻⁷ / ° C. or lower and the heat resistant temperature is 300 ° C. or higher.
Further, in the above embodiment, the light source device 70 of the present invention is employed in the projector 1 including the liquid crystal panel 41. However, the present invention is not limited to this, and the projector including the light modulation device using the micromirror is not limited thereto. A light source device may be employed.
In the above embodiment, the present invention is applied to the light source device 70 in which the light source lamp 71 is provided with the sub-reflecting mirror 73. The present invention may be adopted. By doing so, the number of members can be reduced, and the light source device can be made more inexpensive.
Furthermore, in the said embodiment, although the thing in which the radiation fin was formed in the cover member was used, it is not limited to the thing of such a shape, For example, you may use the thing without a radiation fin.

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. In addition, this invention is not limited to the content shown below.
An experiment on the durability of the collimated concave lens was performed using a light source device substantially the same as in the above embodiment. The light source lamp used was 165W. As the collimating concave lens, a lens having a thickness of 3 mm and a diameter of 20 mm at the thinnest portion of the thickness along the light beam transmission direction was used. The collimating concave lens was disposed near the second focal point of the light source lamp.
(Example 1)
The material of the collimating concave lens was Tempax (trade name) (thermal expansion coefficient 33 × 10 ⁻⁷ / ° C., heat resistant temperature 500 ° C.) manufactured by Schott.
(Example 2)
The material for the collimating concave lens was Pyrex (registered trademark) (thermal expansion coefficient 33 × 10 ⁻⁷ / ° C., heat resistant temperature 500 ° C.) manufactured by Corning Glass.
(Example 3)
The material for the collimating concave lens was Vycor (trade name) (thermal expansion coefficient 7.5 × 10 ⁻⁷ / ° C., heat resistant temperature 1200 ° C.) manufactured by Corning Glass.
(Comparative example)
The material of the collimating concave lens was BK7 (trade name) manufactured by Schott (thermal expansion coefficient 72 × 10 ⁻⁷ / ° C.).

  Table 1 shows the results of Examples 1 to 3 and the comparative example. In Table 1, o indicates that the collimated concave lens was not damaged, and x indicates that the collimated concave lens was damaged.

In Example 1 to Example 3, since the collimating concave lens was made of a material having a low thermal expansion coefficient and a high heat-resistant temperature, no thermal distortion occurred and the collimating concave lens was not damaged. On the other hand, in the comparative example, since the collimating concave lens was made of a material having a large thermal expansion coefficient, thermal distortion occurred and the collimating concave lens was damaged.
From the above, the effect of the present invention could be confirmed.

  The present invention can be used for a light source device mounted on an optical apparatus such as a projector.

FIG. 2 is a schematic diagram illustrating a structure of an optical system of a projector according to an embodiment of the invention. FIG. 2 is a schematic perspective view illustrating a structure of a light source device of the illumination optical device in the embodiment. Sectional drawing showing the structure of the light source device of the illumination optical apparatus in the said embodiment. The schematic diagram which shows the emission state of the light beam of the light source device of the illumination optical apparatus in the said embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Projector, 10 ... Illumination optical apparatus, 41 (41R, 41G, 41B) ... Liquid crystal panel (light modulation device), 60 ... Projection lens, 70 ... Light source device, 71 ... Light source lamp, 72 ... Ellipse reflector, 73 ... Deputy Reflector, 74 ... Parallelizing concave lens

Claims (8)

A light source device comprising an arc tube, an elliptical reflector that emits a luminous flux emitted from the luminous tube in a fixed direction, and a parallelizing concave lens that collimates the luminous flux reflected by the elliptical reflector,
The collimating concave lens is disposed near a second focal point of the elliptical reflector;
The parallelizing concave lens has a thermal expansion coefficient of 40 × 10 ⁻⁷ / ° C. or lower and a heat resistant temperature of 300 ° C. or higher. The light source device according to claim 1,
The collimating concave lens is made of borosilicate glass having a thermal expansion coefficient of 33 × 10 ⁻⁷ / ° C. or less. The light source device according to claim 1,
The collimating concave lens is made of high silicate glass having a silicic acid content of 96% or more. The light source device according to claim 1,
The collimating concave lens is made of quartz glass. The light source device according to claim 1,
The light source device, wherein the collimating concave lens is made of crystallized glass. The light source device according to any one of claims 1 to 5,
The collimating concave lens has a thickness dimension of 2 mm or more along the light beam transmission direction. An illumination optical device for illuminating a light modulation device that modulates a light beam emitted from a light source according to image information to form an optical image,
A light source device according to any one of claims 1 to 6;
A beam splitting optical element configured by arranging a plurality of small lenses in a matrix in a plane perpendicular to the illumination optical axis, and splitting a beam emitted from the light source device into a plurality of partial beams;
An illumination optical apparatus comprising: a condensing lens that superimposes each partial light beam divided by the light beam splitting optical element on an image forming region of the light modulation device.   A projector comprising the illumination optical device according to claim 7.

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