JP2001249405A - Illumination apparatus and projector equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination apparatus with high use efficiency of light which is free from causing an extremely large light loss when a light source position, a shape of a reflective surface, etc., change slightly, and with which the parallel illuminating light is obtained. SOLUTION: A light source 1 is disposed at the focus of a main reflecting mirror 3 being a main reflective means, and the main reflecting mirror 3 is formed of a spherical reflecting mirror 3a consisting of a spherical surface, and a revolution parabolic reflecting mirror 3b consisting of paraboloid of revolution. Then, the condenser lens 4 is disposed at the opening of the main reflecting mirror 3 so that the light being made incident directly from the light source 1, and the reflected light from spherical reflecting mirror 3a may be condensed in parallel. Furthermore, an auxiliary reflecting mirror 5 of the spherical surface being an auxiliary reflective means is disposed so that the light source 1 may serve as the focus, and the opening 6 for emitting the illuminating light is formed in the auxiliary reflecting mirror 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device used for a projector and the like, and a projector using the same.

[0002]

2. Description of the Related Art In general, a reflector having a light-collecting property is used in an illuminating device. In addition to directly irradiating light from a light source, light from the light source is reflected by the reflector and collected. This increases the light use efficiency. However, since the light from the light source diffuses radially, if there is light that is not condensed by a reflecting mirror or the like but escapes, the light use efficiency has been reduced by the amount of the escaped light.

Conventionally, as a technique for reducing such scattered light, a technique described in Japanese Patent Application Laid-Open No. 6-250288 is known. FIG. 11 shows a configuration diagram of the lighting device.

The illuminating device shown in FIG. 11 has a configuration in which a light source is arranged at a focal position of a spheroidal mirror and a spherical mirror, and light passing through an opening is converged by a condenser lens to illuminate an object to be irradiated. In this illumination device, light emitted in a direction different from that of the spheroidal mirror is reflected by the spherical mirror, returned to the light source position again, passed through the light source position, and then reflected by the spheroidal mirror to increase the light use efficiency. are doing.

[0005] Further, by forming the opening into a shape that can irradiate only the object to be irradiated, the light utilization efficiency is further increased.

[0006]

In FIG. 11, when the aperture is made very small, most of the light generated from the light source can be obtained as parallel light. However, in practice, the smaller the aperture is, the more the amount of light affected by diffraction increases, so that the amount of light passing through the condenser lens is very small. Further, even when the shape of the reflection surface slightly changes due to the position of the light source or the influence of heat, the focal point of the spheroidal mirror and the position of the aperture are not aligned, and an extremely large light loss occurs.

Conversely, if the aperture becomes slightly larger, more light is directly incident on the aperture from the light source, so that more light cannot be collimated by the condenser lens. Therefore, the light incident on the irradiation target does not have a fixed angle, and when used as a light source such as a projector incorporating a large number of optical components or optical components having strong incident angle dependence, it is difficult to design an optimal optical system. . As a result, there is a possibility that problems such as an increase in light loss until the image is projected and an effect as designed in each optical component cannot be obtained.

The present invention solves such a problem, and an object of the present invention is to firstly provide an illuminating device having high light use efficiency and obtaining parallel illumination light.
Second, it is an object of the present invention to provide an illumination device that does not cause an extremely large loss of light even if the position of a light source or the shape of a reflection surface slightly changes. Another object of the present invention is to provide a projector with high image quality and a bright image by using such a lighting device.

[0009]

In order to achieve the above object, an illuminating device according to the present invention comprises a light source, a main reflecting means having a spherical portion and a paraboloid of revolution, and an opening of the main reflecting means. Arranged, light collecting means for collimating the light reflected by the spherical portion and the light directly incident from the light source, and the light directly incident from the light source was condensed at the focal point of the paraboloid of revolution. And an auxiliary reflecting means for irradiating the paraboloid of revolution.

According to such a configuration, the light directly incident on the light collecting means from the light source is emitted from the opening as parallel light. Also, the light directly incident on the spherical portion of the main reflection means from the light source is reflected and collected near the position of the light source,
The light enters the light condensing means and is emitted from the opening as parallel light. The light directly incident on the paraboloid of revolution of the main reflection means from the light source is reflected and emitted as parallel light from the opening. Further, the light directly incident on the auxiliary reflection means from the light source is reflected and condensed near the position of the light source, and then is incident on the paraboloid of revolution of the main reflection means, and is reflected as parallel light to form the aperture. Emitted from.

Therefore, it is not necessary to pass the illumination light through a very small opening after condensing the illumination light as in the related art, and the opening can be made relatively large. Even if it changes slightly, there is no extremely large loss of light, and almost all light generated from the light source can be obtained as parallel light.

Further, in the illumination device of the present invention, the outer shape of the light condensing means may include a locus of a straight line connecting the point moving on the peripheral shape of the opening of the auxiliary reflecting means and the light source,
A shape defined by an intersection with a plane perpendicular to the optical axis, and an outer peripheral shape of the spherical portion is a shape defined by an intersection of the straight line locus and the spherical portion; An image obtained by projecting the outer peripheral shape of the object surface portion at infinity in the optical axis direction is not larger than an image projecting the peripheral shape of the opening of the auxiliary reflection means at infinity in the optical axis direction, and the outer periphery of the spherical portion is not enlarged. An image whose shape is projected at infinity in the optical axis direction is not larger than an image whose outer peripheral shape of the paraboloid of revolution is projected at infinity in the optical axis direction. The image projected at infinity is characterized in that the outer peripheral shape of the spherical portion does not become larger than the image projected at infinity in the optical axis direction.

[0013] According to such a configuration, the outer shape of the light condensing means is such that the trajectory of the straight line connecting the point moving on the peripheral shape of the opening of the auxiliary reflecting means and the light source, and the plane perpendicular to the optical axis. , The light going directly from the light source to the opening always passes through the light condensing means, and there is no light passing directly from the light source through the opening. In addition, since the outer peripheral shape of the spherical portion is a shape defined by the intersection of the spherical portion and the locus of a straight line connecting the point moving on the peripheral shape of the opening and the light source, the light reflected on the spherical portion Always converge on the light source and then pass through the converging means.

Further, an image obtained by projecting the peripheral shape of the paraboloid of revolution at infinity in the optical axis direction is not larger than an image projecting the peripheral shape of the opening of the auxiliary reflection means at infinity in the optical axis direction. The image of the outer peripheral shape of the spherical portion projected at infinity in the optical axis direction is not larger than the image of the outer peripheral shape of the paraboloid of revolution projected at infinity in the optical axis direction. Since the image projected at infinity in the optical axis direction does not become larger than the image projected at infinity in the optical axis direction on the outer periphery of the spherical portion, all the light reflected on the paraboloid of revolution collects light. The light passes through the opening of the auxiliary reflection means as parallel light without being affected by the auxiliary reflection means.

Accordingly, since the light passing through the opening of the auxiliary reflecting means always passes through the condensing means or is reflected on the paraboloid of revolution, almost all the light generated from the light source is converted into parallel light. Can be emitted from the opening of the auxiliary reflection means. Further, since the light passing through the opening of the auxiliary reflecting means is a light beam having the same shape as an image obtained by projecting the outer peripheral shape of the paraboloid of revolution at infinity in the optical axis direction, the illuminated object such as a circular or rectangular object Irradiates only the object to be irradiated.

Therefore, almost all the light generated from the light source can be illuminated on the object to be irradiated with high light use efficiency as parallel light.

Further, since the projector of the present invention is provided with the illumination device having high parallelism and high light use efficiency as described above, a high quality and bright image can be obtained.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a sectional view showing a configuration of a lighting device according to a first embodiment of the present invention.

As shown in FIG. 1, a light source 1 is disposed at a position substantially at a focal point of a main reflecting mirror 3 which is a main reflecting means, and the main reflecting mirror 3 has a spherical reflecting mirror 3a having a spherical surface and a paraboloid of revolution. And a rotating parabolic reflecting mirror 3b. That is, the focal point of the spherical reflecting mirror 3a is at the position of the light source 1, and the focal point of the rotating parabolic reflecting mirror 3b is at the position of the light source 1 and at an infinity point. In addition, a condenser lens 4 as a condensing means is disposed in the opening of the main reflecting mirror 3 so as to collimate the light directly incident from the light source 1 and the light reflected from the spherical reflecting mirror 3a. Further, a spherical auxiliary reflecting mirror 5 serving as an auxiliary reflecting means is arranged so that the light source 1 becomes a focal point. The auxiliary reflecting mirror 5 has a circular opening 6 having the same shape as the circular non-irradiation body 7. Have been.

Next, the peripheral shape of the opening 6, the external shape of the condenser lens 4, the outer peripheral shape of the spherical reflecting mirror 3a, and the outer peripheral shape of the rotating parabolic reflecting mirror 3b will be described in detail.

FIG. 2 is a perspective view showing the relationship between the opening 6, the condenser lens 4, and the spherical reflecting mirror 3a. FIG. 3 is a perspective view showing the relationship between the opening 6 and the rotating parabolic reflecting mirror 3b. It is a front view when the lighting device by this invention is seen from infinity of an optical axis direction.

As shown in FIG. 2, the external shape of the condenser lens 4 is defined by a locus of a straight line connecting a point moving on the peripheral shape of the circular opening 6 and the light source 1 and a plane perpendicular to the optical axis. The outer peripheral shape of the spherical reflecting mirror 3a has a shape represented by the intersection of the above-described locus of the straight line and the spherical reflecting mirror 3a.

Further, the outer peripheral shape of the paraboloid of revolution 3b has a circular shape having the same size as the opening 6, as shown in FIG.

Therefore, as shown in FIG. 4, when the illuminating device according to the present invention is viewed from infinity in the optical axis direction, the outer peripheral shape of the rotating parabolic reflecting mirror 3b matches the peripheral shape of the opening 6, and the spherical reflecting mirror is used. The outer peripheral shape of 3a is smaller than the outer peripheral shape of the paraboloid of revolution 3b, and the outer shape of the condenser lens 4 matches the outer peripheral shape of the spherical reflecting mirror 3a. This is because an image obtained by projecting the outer peripheral shape of the rotating parabolic reflector 3b at infinity in the optical axis direction is not larger than an image obtained by projecting the peripheral shape of the opening 6 at infinity in the optical axis direction. An image obtained by projecting the outer peripheral shape of the mirror 3a at infinity in the optical axis direction is converted into a parabolic reflecting mirror 3b.
Is not larger than an image projected at infinity in the optical axis direction, and an image obtained by projecting the outer shape of the condenser lens 4 at infinity in the optical axis direction is obtained by changing the outer peripheral shape of the spherical reflecting mirror 3a in the optical axis direction. It satisfies the condition that it does not become larger than the image projected at infinity.

With the above configuration, as shown in FIG. 1, light directly incident on the condenser lens 4 from the light source 1 is obtained as light parallel to the optical axis 2, and the light from the light source 1 is reflected on the spherical reflecting mirror 3a.
Is directly reflected, condensed on the light source 1 and then incident on the condenser lens 4 to be obtained as light parallel to the optical axis 2. The light directly incident on the rotary parabolic reflecting mirror 3b from the light source 1 is reflected and obtained as light parallel to the optical axis 2 from the opening 6, and the light directly incident on the auxiliary reflecting mirror 5 from the light source 1 is After being reflected and condensed on the light source 1, it is incident on the rotating parabolic reflector 3 b, reflected and obtained as light parallel to the optical axis 2 from the opening 6.

Therefore, almost all the light generated from the light source 1 can be obtained as parallel light from the opening 6, and the light obtained from the opening 6 projects the opening 6 at infinity in the direction of the optical axis 2. Because it becomes a circular light beam of the same size as the shape
Irradiation can be performed only on the irradiation target 7 having the same circular shape.

Therefore, since it is not necessary to make the opening very small, there is no extremely large loss of light even if the position of the light source or the shape of the reflection means slightly changes, and almost all light generated from the light source is not lost. Can be illuminated as parallel light on a circular object to be irradiated, so that high light use efficiency can be obtained.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS.

FIG. 5 is a sectional view showing the structure of a lighting device according to a second embodiment of the present invention. In the present embodiment, the types and arrangements of the components are basically the same as those of the first embodiment described above.
, The outer shape of the condenser lens 4, the outer shape of the spherical reflecting mirror 3a, and the outer shape of the rotating parabolic reflecting mirror 3b. The peripheral shape of the opening 6 is formed such that an image projected at infinity in the direction of the optical axis 2 becomes the same rectangle as the non-irradiation body 7.

Next, the peripheral shape of the opening 6, the external shape of the condenser lens 4, the outer peripheral shape of the spherical reflecting mirror 3a, and the outer peripheral shape of the rotating parabolic reflecting mirror 3b will be described in detail.

FIG. 6 is a perspective view showing the relationship between the opening 6, the condenser lens 4, and the spherical reflecting mirror 3a. FIG. 7 is a perspective view showing the relationship between the opening 6 and the rotating parabolic reflecting mirror 3b. It is a front view when the lighting device by this invention is seen from infinity of an optical axis direction.

As shown in FIG. 6, the external shape of the condenser lens 4 is defined by the locus of a straight line connecting the point moving on the peripheral shape of the opening 6 and the light source 1 and the intersection of the plane perpendicular to the optical axis. The outer peripheral shape of the spherical reflecting mirror 3a is a shape represented by the line of intersection of the above-described straight line and the spherical reflecting mirror 3a.

In the outer peripheral shape of the paraboloid of revolution 3b, as shown in FIG. 3, a trajectory of a straight line parallel to the optical axis 2 passing through a point moving on the periphery of the opening 6 and The shape is represented by the line of intersection with the object surface reflecting mirror 3b.

Therefore, as shown in FIG. 5, when the illumination device according to the present invention is viewed from infinity in the optical axis direction, the outer peripheral shape of the rotating parabolic reflector 3b matches the peripheral shape of the opening 6, and the spherical reflector is used. The outer shape of 3a is smaller than the outer shape of the paraboloid of revolution 3b, and the outer shape of the condenser lens 4 is smaller than the outer shape of the spherical mirror 3a. This is because an image obtained by projecting the outer peripheral shape of the rotating parabolic reflector 3b at infinity in the optical axis direction is not larger than an image obtained by projecting the peripheral shape of the opening 6 at infinity in the optical axis direction. An image obtained by projecting the outer shape of the mirror 3a at infinity in the optical axis direction is not larger than an image obtained by projecting the outer shape of the rotating parabolic reflector 3b at infinity in the optical axis direction. Satisfies the condition that the image projected to infinity in the optical axis direction does not become larger than the image projected to infinity in the optical axis direction of the outer peripheral shape of the spherical reflecting mirror 3a.

With the above arrangement, as shown in FIG. 5, light directly incident on the condenser lens 4 from the light source 1 is obtained as light parallel to the optical axis 2, and the light from the light source 1 is reflected by the spherical reflecting mirror 3a.
Is directly reflected, condensed on the light source 1 and then incident on the condenser lens 4 to be obtained as light parallel to the optical axis 2. The light directly incident on the rotary parabolic reflecting mirror 3b from the light source 1 is reflected and obtained as light parallel to the optical axis 2 from the opening 6, and the light directly incident on the auxiliary reflecting mirror 5 from the light source 1 is After being reflected and condensed on the light source 1, it is incident on the rotating parabolic reflector 3 b, reflected and obtained as light parallel to the optical axis 2 from the opening 6.

Therefore, almost all the light generated from the light source 1 can be obtained as parallel light from the opening 6, and the light obtained from the opening 6 projects the opening 6 at infinity in the optical axis 2 direction. It becomes a rectangular luminous flux of the same size as the shape
Irradiation can be performed only on the irradiation target 7 having the same rectangular shape.

Therefore, since it is not necessary to make the opening very small, there is no extremely large loss of light even if the position of the light source or the shape of the reflecting means slightly changes, and almost all light generated from the light source is not lost. Can be illuminated on the rectangular irradiation object as parallel light, so that high light use efficiency can be obtained.

In the embodiments described above, the peripheral shape of the opening is different, but the peripheral shape of the opening is not limited to these.

It is ideal that the light source used in the present invention is ideally a point light source in which light is diffused in all directions. However, if the light source is relatively similar to the light source, the light source does not depart from the gist of the present invention. Can be used. For example,
There is a light emitting portion of a discharge lamp in which a light source emits light by discharge between electrodes. In this case, it can be considered as a point light source. However, since it is preferable that the electrodes do not block as much light as possible, various arrangements such as a straight line connecting the electrodes being perpendicular or parallel to the optical axis, and various shapes such as straight lines and curves are conceivable.

(Projector) Next, a description will be given of an embodiment of a projector into which the above-mentioned lighting device can be incorporated. In the following description, unless otherwise specified, the light traveling direction is the z direction, the 3 o'clock direction is the x direction, and the 12:00 o'clock direction is the y direction when viewed from the light traveling direction (z direction).

FIG. 9 is a schematic plan view showing a main part of the projector. The projector 10 includes an illumination optical system 10
0, a color light separating optical system 200 including dichroic mirrors 210 and 212, light reflecting optical systems 220 including reflecting mirrors 222 and 224, an incident side lens 230, and a relay lens 232, a reflecting mirror 218, and three elements , Two liquid crystal light valves 250, 252, 254, a cross dichroic prism 260, and a projection lens 270. The liquid crystal light valves 250, 252, and 254 include liquid crystal panels 250b, 252b, and 254b, incident-side polarizing plates 250a, 252a, and 254a, and emission-side polarizing plates 250c, 252c, and 254c, respectively.

The illumination optical system 100 includes an illumination device 110 that emits a substantially parallel light beam, a first lens array 120,
A second lens array 130, a superimposing lens 150, and a reflection mirror 160 are provided. The illumination optical system 100 includes:
This is an integrator optical system for almost uniformly illuminating the effective areas of the liquid crystal panels 250b, 252b, 254b, which are the illumination areas of the three liquid crystal light valves 250, 252, 254. As the lighting device 110, the lighting device according to the first or second embodiment can be used.

FIG. 10 is a perspective view showing the appearance of the first lens array 120. The first lens array 120 has a configuration in which small lenses 122 having a substantially rectangular outline are arranged in a matrix of M rows and N columns. In this example,
M = 6, N = 4. Each small lens 122 divides a parallel light beam incident from the illumination device 110 (FIG. 9) into a plurality of (ie, M × N) partial light beams, and splits each partial light beam in the vicinity of the second lens array 130. Make an image. The external shape of each small lens 122 viewed from the z direction is
0b, 252b, and 254b are set to be substantially similar in shape. For example, if the aspect ratio (ratio of horizontal and vertical dimensions) of the illumination area (area where an image is displayed) of the liquid crystal light valve is 4: 3, each small lens 12
The aspect ratio of 2 is also set to 4: 3.

The second lens array 130 also has a configuration in which small lenses are arranged in a matrix of M rows and N columns so as to correspond to the small lenses 122 of the first lens array 120. The second lens array 130 has a function of aligning the central axes (principal rays) of the respective partial luminous fluxes emitted from the first lens array 120 so as to be perpendicularly incident on the incident surface of the superimposing lens 150. Further, the superimposing lens 150
Are used to convert a plurality of partial light beams into three liquid crystal panels 250b and 25.
2b and 254b. Further, the field lenses 240, 242, and 244 have a function of converting each partial light beam applied to the illumination area into a light beam parallel to the respective central axis (principal ray). In the present embodiment, the second lens array 130 and the superimposing lens 15
0 is a separate configuration, but the second lens array 13
0 may also have the function of the superimposing lens 150. For example, each small lens may be constituted by an eccentric lens. In addition, the second lens array 130 can be omitted when the light beam emitted from the illumination device 110 has excellent parallelism.

As shown in FIG. 9, the second lens array 130 is disposed at an angle of 90 degrees with respect to the first lens array 130 with the reflection mirror 160 interposed therebetween. The reflection mirror 160 is provided to guide the light beam emitted from the first lens array 120 to the second lens array 130. This is not always necessary depending on the configuration of the illumination optical system. For example, this is not necessary if the first lens array 120 and the illumination device 110 are provided in parallel with the second lens array 130.

In the projector 10 shown in FIG. 9, substantially parallel light beams emitted from the illuminating device 110 are combined with the first and second lens arrays 12 constituting an integrator optical system.
The light beams are divided into a plurality of partial light beams by 0 and 130. The partial luminous flux emitted from each small lens of the first lens array 120 is divided into each small lens 13 of the second lens array 130.
Light is condensed so that a light source image (secondary light source image) of the illumination device 110 is formed in the vicinity of 2. Second lens array 130
Of the liquid crystal panels 250b, 252b, and 254b by the superimposing lens 150 while diffusing the partial luminous flux emitted from the secondary light source image formed in the vicinity of.
Superimposed on As a result, each liquid crystal panel 250b,
252b and 254b are almost uniformly illuminated.

The color light separation optical system 200 includes two dichroic mirrors 210 and 212, and a superposition lens 150.
Has a function of separating the light emitted from the light into three color lights of red, green, and blue. First dichroic mirror 21
0 transmits the red light component of the white light beam emitted from the illumination optical system 100 and reflects the blue light component and the green light component. The red light transmitted through the first dichroic mirror 210 is reflected by the reflection mirror 218, passes through the field lens 240, and passes through the liquid crystal light valve 2 for red light.
Reach 50. The field lens 240 converts each partial light beam emitted from the second lens array 130 into a light beam parallel to its central axis (principal ray). Field lens 24 provided in front of another liquid crystal light valve
2,244 is the same.

Of the blue light and the green light reflected by the first dichroic mirror 210, the green light is reflected by the second dichroic mirror 212 and passes through the field lens 242 to reach the liquid crystal light valve 252 for green light. . On the other hand, the blue light passes through the second dichroic mirror 212 and is incident on the incident side lens 230 and the relay lens 2.
Then, the light passes through a relay lens (light guide optical system) 220 provided with a light source 32 and reflection mirrors 222 and 224, and further passes through a light exit side lens (field lens) 244 to reach a liquid crystal light valve 254 for blue light. In addition, the relay lens is used for blue light because the length of the optical path of the blue light is longer than the length of the optical path of the other color light, so as to prevent a reduction in light use efficiency due to light diffusion or the like. It is. That is, it is for transmitting the partial light beam incident on the incident side lens 230 to the exit side lens 244 as it is.

The liquid crystal light valve 250 includes an entrance side polarizing plate 250a, a liquid crystal panel 250b, and an exit side polarizing plate 25.
0c. The transmission axis of the incident-side polarizing plate 250a is set in the direction of s-polarized light, and transmits only s-polarized light among incident light. The liquid crystal panel 250b modulates the polarization direction of the polarized light of the red light emitted from the incident side polarizing plate 250a according to the given image information (image signal). The emission-side polarizing plate 250c has its transmission axis set in the direction of p-polarized light, and transmits only p-polarized light of the modulated light emitted from the liquid crystal panel 250b. Thus, the liquid crystal light valve 250a has a function of modulating incident light according to given image information to form an image.

The liquid crystal light valves 252 and 254 also include the incident side polarizing plates 252a and 254a, the liquid crystal panels 252b and 254b, and the outgoing side polarizing plates 252c and 254, respectively.
c, and has the same function as the liquid crystal light valve 250. The cross dichroic prism 260
It has a function as a color light combining unit that forms a color image by combining color light of colors.

The incident-side polarizing plate 250a of the liquid crystal light valve 250 for red light is attached to the flat exit surface of the field lens 240. The output side polarizing plate 250c is attached to the output surface of the liquid crystal panel 250b. The liquid crystal panel 250b is arranged at a certain distance from the incident-side polarizing element 250a. This interval is determined according to the optical relationship with other components, the optical distance, the focal length of the lens, and the like. However, it is desirable to secure a preferable space for cooling the liquid crystal panel 250b and the incident side polarizing plate 250a.

Similarly to the liquid crystal light valve 250 for red light, the polarizing plate 2 on the incident side of the liquid crystal light valve 252 for green light is used.
52a is also attached to the flat exit surface of the field lens 242. In addition, the output side polarizing plate 252c is also attached to the output surface of the liquid crystal panel 252b. The liquid crystal panel 252b is also arranged at a certain distance from the incident side polarization element 252a.

The liquid crystal light valve 254 for blue light has a different configuration from the other liquid crystal light valves 250 and 252. The incident-side polarizing plate 254a of the liquid crystal light valve 254 for blue light includes a liquid crystal panel 254b and the field lens 2.
A transparent plate 246, which is arranged as far as possible from the liquid crystal panel 254b, is attached to the light-emitting surface of a glass plate, for example, between the first gap with the liquid crystal panel 254b. The emission-side polarizing plate 254c of the liquid crystal light valve 254 for blue light is attached to the emission surface of the liquid crystal panel 254b, like the other liquid crystal light valves 250 and 254.

In the cross dichroic prism 260, a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in an approximately X-shape at the interface between the four right-angle prisms. The three colored lights are combined by these dielectric multilayer films to form combined light for projecting a color image.

The combined light generated by the cross dichroic prism 260 is emitted toward the projection lens 270. The projection lens 270 transmits the combined light to the screen 30.
It has a function as a projection means for projecting a color image on the image plane 0 to display a color image.

As described above, the first or the second
The illumination device of the embodiment has high parallelism of emitted light and high light use efficiency. Therefore, if the illumination device of the first or second embodiment is adopted for such a projector, the quality is good. And a bright image can be obtained.

The present invention is not limited to the above-described embodiment, but can be implemented in various modes without departing from the paper. For example, the following modifications are possible.

(1) In the above embodiment, the lighting device 110
Lens array 1 that divides light into a plurality of partial light beams
Although 20, 130 are used, the present invention can be applied to a projector that does not use such a lens array.

(2) In the above embodiment, an example was described in which the illumination device of the present invention was incorporated in a transmissive projector, but the present invention can also be applied to a reflective projector. Here, “transmission type” means that a light valve such as a liquid crystal light valve transmits light, and “reflection type” means that the light valve transmits light. Means
In a reflection type projector, the cross dichroic prism is used as a color light separating unit that separates white light into red, green, and blue light, and recombines the modulated three color light into the same light. It may also be used as a color light combining unit that emits light in the direction. When the present invention is applied to a reflection type projector, almost the same effects as those of a transmission type projector can be obtained. The light valve is not limited to the liquid crystal light valve, and may be, for example, a light valve using a micro mirror.

(3) As the projector, there are a front projection type projector that projects an image from the direction in which the projection surface is observed, and a rear projection type projector that projects an image from the side opposite to the direction in which the projection surface is observed. However, the lighting device of the present invention can be incorporated in any projector.

[0063]

According to the lighting device of the present invention, as in the prior art,
It is not necessary to allow illumination light to pass through the very small opening, and the opening can be made relatively large, so that even if the light source position or the shape of the reflecting surface changes slightly, extremely large light loss occurs. Absent. In addition, since most of the light generated from the light source can be irradiated only on the irradiation target as parallel light, illumination light with high light use efficiency can be obtained. Moreover, since parallel light can be obtained, when used in a projector or the like that uses many optical components, the design of the entire optical system becomes easy.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a lighting device according to a first embodiment, taken along a plane including an optical axis.

FIG. 2 is a perspective view showing a relationship among an opening, a condenser lens, and a spherical reflecting mirror in the lighting device according to the first embodiment.

FIG. 3 is an exemplary perspective view showing a relationship between an opening and a rotating parabolic reflector in the illumination device according to the first embodiment;

FIG. 4 is an exemplary front view of the lighting device according to the first embodiment when viewed from infinity in the optical axis direction;

FIG. 5 is a cross-sectional view of the lighting device according to the second embodiment, taken along a plane including an optical axis.

FIG. 6 is an exemplary perspective view showing a relationship among an opening, a condenser lens, and a spherical reflecting mirror in a lighting device according to a second embodiment;

FIG. 7 is an exemplary perspective view showing the relationship between an opening and a rotating parabolic reflector in the lighting device according to the second embodiment;

FIG. 8 is a front view of the lighting device according to the second embodiment when viewed from infinity in the optical axis direction.

FIG. 9 is a schematic plan view showing a main part of an embodiment of a projector into which the lighting device of the present invention can be incorporated.

FIG. 10 is a perspective view showing the appearance of the first lens array 120.

FIG. 11 is a sectional view showing a configuration of a lighting device disclosed in Japanese Patent Laid-Open No. 6-250288.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Light source 2 ... Optical axis 3 ... Main reflecting mirror 3a ... Spherical reflecting mirror 3b ... Rotating parabolic reflecting mirror 4 ... Condenser lens 5 ... Auxiliary reflecting means 6 ... Opening 7 ... Irradiation object 10 ... Projector 100 ... Illumination optics System 110 Illumination device 120 First lens array 122 Small lens 130 Second lens array 132 Small lens 150 Superimposing lens 160 Reflection mirror 200 Color light separation optical system 210 First dichroic mirror 212 2nd dichroic mirror 218 reflection mirror 220 light guide optical system 222, 224 reflection mirror 230 incident lens 232 relay lens 240, 242, 244 field lens 246 transparent plate 250, 252, 254 liquid crystal light Bulbs 250a, 252a, 254a... Incident side polarizing plates 250b, 252b, 2 4b ... liquid crystal panel 250c, 252c, 254c ... output-side polarizer 260 ... cross dichroic prism 270 ... projection lens system 300 ... screen

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H04N 5/74 H04N 5/74 K

Claims (3)

[Claims] A light source; a main reflecting means having a spherical portion and a paraboloid of revolution; light reflected by the spherical portion and light directly incident from the light source, the light being disposed at an opening of the main reflecting means. Focusing means for collimating the light, and auxiliary reflecting means for irradiating the light directly incident from the light source at the focal point of the paraboloid of revolution and then irradiating the paraboloid of revolution. A lighting device, characterized in that: 2. The illuminating device according to claim 1, wherein the outer shape of the light condensing means includes a trajectory of a straight line connecting a point moving on a peripheral shape of an opening of the auxiliary reflecting means and the light source; An outer peripheral shape of the spherical portion is a shape defined by an intersecting line between the linear trajectory and the spherical portion; and An image obtained by projecting the outer peripheral shape of the object surface portion at infinity in the optical axis direction is not larger than an image obtained by projecting the peripheral shape of the opening of the auxiliary reflection means at infinity in the optical axis direction. An image obtained by projecting the shape at infinity in the optical axis direction is not larger than an image obtained by projecting the outer peripheral shape of the paraboloid of revolution at infinity in the optical axis direction. In the image projected at infinity, the outer peripheral shape of the spherical portion is set in the optical axis direction. Lighting apparatus characterized by not greater than the image projected at infinity. 3. The lighting device according to claim 1 or 2, a light valve that modulates light emitted from the lighting device, and a projection lens that projects light modulated by the light valve. A projector, comprising: