JP2019158914A - Illumination device and projector - Google Patents

Abstract

To provide an illumination device capable of increasing efficiency for light utilization and reducing speckle noise.SOLUTION: The illumination device comprises: a light source part 10 emitting mixed color light including a plurality of color light beams illuminating a plurality of light modulation elements respectively; and an illumination optical system 11 separating emission light from the light source part 10 into a plurality of color light beams and irradiating each light modulation element with each color light beam at a mutually different optical path. One of the plurality of color light beams is a laser beam. The illumination optical system 11 has a relay optical system 12 forming, on the light modulation element, an optical image formed by using the laser beam and at least one first diffusion plate 14 disposed at a pupil position of the relay optical system 12.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an illuminating device that generates illumination light including a plurality of colored lights, and a projector including the illuminating device.

A mercury lamp containing mercury, which is a harmful substance, is used as a light source for a high-intensity data projector. In recent years, there has been an urgent need to develop mercury-free products for projectors amidst the desire for products that are environmentally friendly. Under such circumstances, development of projectors using light emitting diodes (LEDs) and laser diodes (LDs) as light sources has been promoted, and recently, low-intensity LED projectors and laser projectors have been put on the market.
However, a high-luminance LED light source has not been mass-produced, and a small, high-power green LD light source has not been mass-produced. For this reason, these light sources or data projectors combining these light sources have not yet been put on the market.

On the other hand, mercury-free high-intensity data projectors using a phosphor as a light source have already been put on the market. In this data projector, the light source unit includes a phosphor that is excited by excitation light and emits yellow fluorescence (including a green component and a red component), and the yellow fluorescence emitted from the phosphor and the blue light that is laser light, The mixed color light is synthesized. The light emitted from the light source unit is separated into red light, blue light, and green light, and each color light is modulated using a light modulation element such as a liquid crystal panel to form a red image, a blue image, and a green image. The projection lens enlarges and projects the red image, the blue image, and the green image.
In the data projector, since laser light is used as blue light, spotted noise called speckle is generated in the projected image. Generally, speckle noise can be reduced by disposing a diffusion plate on a laser beam path. In order to reduce speckle noise, many data projectors have a plurality of diffuser plates arranged in the light source section.
Patent Document 1 describes a configuration in which a diffuser plate is arranged in a laser optical path in order to reduce speckle noise.

JP 2014-163974 A

However, the data projector in which the diffusion plate is arranged in the light source unit has the following problems.
When a plurality of diffusion plates are arranged in the light source unit, diffused blue light (diverged light) propagates over the entire optical path from the light source unit to the projection lens. In this case, since the optical path through which blue light (diverged light) propagates is long, the amount of light out of the optical path out of the blue light (diverged light) that does not contribute to the display of the projected image increases. , Light utilization efficiency decreases.

  In order to increase the light utilization efficiency of blue light (diverging light), it is desirable to reduce the divergence angle of the diffusion plate and to dispose the diffusion plate near the light modulation element on the blue light path. However, if the divergence angle of the diffusion plate is reduced, the effect of reducing the spec noise is reduced. On the other hand, in order to increase the spec noise reduction effect, it is desirable to increase the divergence angle of the diffusion plate. However, when the divergence angle of the diffusion plate is increased, the amount of light that does not contribute to the display of the projected image increases, and the light utilization efficiency decreases.

  The objective of this invention is providing the illuminating device and projector which can solve the said problem.

  In order to achieve the above object, an illumination device according to the present invention separates a light source unit that emits mixed color light including a plurality of color lights that respectively illuminate a plurality of light modulation elements, and a light emitted from the light source unit into the plurality of color lights And an illumination optical system that irradiates each light modulation element with each color light through different optical paths. One of the plurality of color lights is laser light, and the illumination optical system includes a relay optical system that forms an optical image formed using the laser light on the light modulation element, and the relay optical system. And at least one first diffuser plate disposed at the pupil position.

  The projector of the present invention includes the above-described illumination device, a plurality of light modulation elements that respectively modulate a plurality of color lights emitted from the illumination device to form image light, and the plurality of light modulation elements formed by the plurality of light modulation elements A projection optical system for projecting images in a superimposed manner.

  According to the present invention, light utilization efficiency can be increased and spec noise can be reduced.

It is a block diagram which shows the structure of the illuminating device by the 1st Embodiment of this invention. It is a schematic diagram which shows the structure of the illuminating device by the 2nd Embodiment of this invention. It is a characteristic view which shows the transmission characteristic of a dichroic mirror. It is a schematic diagram which shows the structure of a fluorescent substance wheel, Comprising: (a) is a front view, (b) is a side view. It is a schematic diagram which shows the main optical systems which illuminate a liquid crystal panel uniformly. It is a schematic diagram which shows the structure of a polarization conversion element. It is a schematic diagram which shows the structure of a projector.

Next, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing a configuration of a lighting apparatus according to the first embodiment of the present invention.
Referring to FIG. 1, the illumination device of the present embodiment includes a light source unit 10 and an illumination optical system 11. The light source unit 10 emits mixed color light including a plurality of color lights that respectively illuminate the plurality of light modulation elements. The illumination optical system 11 separates the light emitted from the light source unit 10 into a plurality of color lights, and irradiates each light modulation element with each color light through different optical paths. One of the plurality of color lights is laser light.

The illumination optical system 11 includes a relay optical system 12 that forms an optical image (illumination image) formed using laser light on the light modulation element, and at least one first optical system provided in the relay optical system 12. Diffusing plate 14. For example, the first diffusion plate 14 is disposed at the pupil position of the relay optical system 12.
According to the illumination device of the present embodiment, the first diffusion plate 14 is disposed in the relay optical system 12 that is closer to the light modulation element than the light source unit 10. In this case, since the optical path length of the diverging light emitted from the first diffusion plate 14 is shorter than the optical path length of the diverging light when the diffusion plate is provided in the light source unit 10, the light that does not contribute to the display of the projected image The amount of light can be reduced, and the light use efficiency can be increased.

  In addition, a Fourier image of an optical image (illumination image) corresponding to the angle component is formed at the pupil position of the relay optical system 12. By arranging the first diffusion plate 14 at this pupil position, light emitted from one point of the optical image (illumination image) can be incident on the first diffusion plate 14 from a plurality of angles. The spec noise is averaged and suppressed by the multiple effect. In addition, spec noise can be reduced by diffusing light with the first diffusion plate 14. Thus, since the spec noise can be reduced using both the angle multiplexing effect and the diffusion effect, the spec noise reduction effect can be increased. In addition, since the diffusion angle of the first diffusion plate 14 can be made smaller than the case where the spec noise is reduced only by the diffusion effect, the amount of light that does not contribute to the display of the projected image is reduced, and the light use efficiency is improved. It can be increased.

In the illumination device of the present embodiment, the relay optical system 12 may include first to third relay lenses. In this case, the first relay lens is disposed on the light source unit 10 side, the third relay lens is disposed on the light modulation element side, and the second relay lens is disposed between the first and third relay lenses. The pupil position of the relay optical system 12 may be formed between the second relay lens and the third relay lens.
In addition, the light source unit 10 may include a laser light source that emits laser light and at least one second diffusion plate that is provided immediately after the laser light source.

  In the above case, the light source unit 10 is positioned so as to face the first condensing lens across the second diffusing plate and the first condensing lens provided between the second diffusing plate and the laser light source. A second condenser lens provided on the first lens, and the second diffuser plate may be disposed at a focal position of the first lens. Further, the diffusion angle of the second diffusion plate may be larger than the diffusion angle of the first diffusion plate 14. Furthermore, the light source unit 10 further includes a phosphor unit that emits color light that is fluorescence, and a color synthesis unit that emits mixed color light by combining the emission light of the phosphor unit and the emission light of the laser light source. You may do it. Further, the laser light source may be a blue laser light source that emits blue laser light.

Moreover, the illuminating device of this embodiment may further have a means for swinging or rotating the first diffusion plate 14.
The lighting apparatus of the present embodiment, a plurality of light modulation elements that respectively modulate a plurality of color lights emitted from the lighting apparatus to form image light, and a plurality of images formed by the plurality of light modulation elements are projected in an overlapping manner. A projector having a projection optical system may be provided. In this projector, the light modulation element may be a liquid crystal panel.

(Second Embodiment)
FIG. 2 is a schematic diagram showing a configuration of a lighting apparatus according to the second embodiment of the present invention.
Referring to FIG. 2, the illumination device includes a light source unit 1 and an illumination optical system 2. The light source unit 1 is a white light source that emits white light in which yellow light and blue LD light are mixed.
First, the configuration related to the optical path of yellow light of the light source unit 1 will be described. The light source unit 1 includes an excitation light source and a phosphor unit.

The excitation light source includes a blue LD array composed of a plurality of blue LDs 1a and a plurality of collimator lenses 1b provided for each blue LD 1a. The blue LD light (diverged light) emitted from each blue LD 1a passes through the collimator lens 1b and becomes pseudo-parallel light. The quasi-parallel light from each collimator lens 1b is the emission light (excitation light) of the excitation light source.
Excitation light emitted from the excitation light source passes through the lenses 1c, 1d, and 1e. The lenses 1c, 1d, and 1e constitute a reduction optical system that reduces the diameter of the light beam from the excitation light source. The light emitted from the reduction optical system is pseudo-parallel light. By reducing the beam diameter of the excitation light, it is possible to make the optical system subsequent to the reduction optical system smaller.

The light emitted from the reduction optical system enters the dichroic mirror 1f. FIG. 3 shows the transmission characteristics of the dichroic mirror 1f. As shown in FIG. 3, the dichroic mirror 1f has a characteristic of reflecting light in the blue wavelength region and transmitting light in other wavelength regions in the visible wavelength region. The dichroic mirror 1f reflects the excitation light (blue) from the reduction optical system toward the phosphor wheel 1i.
Lenses 1g and 1h are disposed between the dichroic mirror 1f and the phosphor wheel 1i. The lenses 1g and 1h collect excitation light, which is reflected light from the dichroic mirror 1f, on the phosphor wheel 1i.

FIG. 4 schematically shows the configuration of the phosphor wheel 1i. 4 is a front view, and FIG. 4B is a side view.
Referring to FIG. 4, the phosphor wheel 1i has a metal plate 5a. The metal disk 5a is a disk in which a reflective film such as aluminum is vapor-deposited on a metal disk. A yellow phosphor portion 5b including a phosphor that is excited by excitation light and emits yellow fluorescence is formed on the metal disk 5a. The yellow phosphor portion 5b is obtained by coating the phosphor with a uniform film thickness containing the phosphor in a binder or the like.

The yellow phosphor portion 5b emits yellow light obtained by wavelength-converting excitation light that is blue LD light. In the yellow phosphor portion 5b, the concentration and film thickness of the phosphor are adjusted so that the wavelength of the incident blue light is converted as much as possible. The wavelength conversion efficiency of the phosphor depends on the temperature of the phosphor, and the wavelength conversion efficiency is higher as the temperature is lower. The irradiation density of the excitation light per unit time is reduced by rotating the metal plate 5a with the motor 5c. Thereby, the temperature rise of a fluorescent substance is suppressed and wavelength conversion efficiency is ensured.
The light emission area of the yellow phosphor portion 5b depends on the irradiation size of blue light that excites the phosphor. Considering the light capturing efficiency in the latter optical system, it is advantageous that the light emitting area is small. Therefore, if it is attempted to reduce the irradiation size of the excitation light and ensure the light capturing efficiency of the optical system in the subsequent stage, the irradiation density to the phosphor inevitably increases. In view of these, in order to reduce the irradiation density to the phosphor, the metal plate 5a coated with the phosphor is rotated by the motor 5c as described above.

The yellow light emitted from the phosphor wheel 1i sequentially passes through the lens 1h and the lens 1g and enters the dichroic mirror 1f. Since the phosphor emits yellow fluorescence in all directions, the yellow light emitted from the phosphor wheel 1i is divergent light. This yellow light (diverging light) passes through the lens 1h and the lens 1g and becomes pseudo-parallel light.
Yellow light (pseudo parallel light) that has passed through the lens 1h and the lens 1g passes through the dichroic mirror 1f. The yellow light transmitted through the dichroic mirror 1f sequentially passes through the lenses 1j and 1k. The lenses 1j and 1k are reduction optical systems that reduce the beam diameter. The light emitted from the reduction optical system is pseudo-parallel light. By reducing the beam diameter of the excitation light, it is possible to make the optical system subsequent to the reduction optical system smaller.

Next, a configuration related to the optical path of the blue LD light of the light source unit 1 will be described. The light source unit 1 has a blue light source.
The blue light source has a blue LD array composed of a plurality of blue LDs 11 and a plurality of collimator lenses 1 m provided for each blue LD 11. The blue LD light (diverged light) emitted from each blue LD 1l passes through the collimator lens 1m, and becomes pseudo-parallel light. Blue LD light (pseudo parallel light) from each collimator lens 1b is incident on the dichroic mirror 1f via the diffusion plate 1n. The diffusion plate 1n diffuses blue LD light.

The dichroic mirror 1f reflects the blue LD light (diffused light) from the diffusing plate 1n toward the lens 1j. Blue LD light that is reflected light from the dichroic mirror 1f sequentially passes through the lenses 1j and 1k. The lenses 1j and 1k reduce the beam diameter of the blue LD light.
In the light source unit 1, blue LD light and yellow light are combined by the dichroic mirror 1f. The light source unit 1 emits mixed color light of blue LD light and yellow light. The mixed color light enters the fly-eye lens 2a. The reduction optical system including the lenses 1j and 1k plays a role of adjusting the beam diameter in order to ensure the light capturing efficiency in the subsequent illumination optical system, and at the same time irradiates the fly-eye lens 2a with pseudo-parallel light. To play a role.

Next, the configuration of the illumination optical system 2 will be described. The illumination optical system 2 illuminates the liquid crystal panel uniformly.
FIG. 5 shows a main optical system that uniformly illuminates the liquid crystal panel. As shown in FIG. 5, an optical system including fly-eye lenses 2a and 2b, a superimposing lens 2d, and field lenses 2f and 2k illuminates liquid crystal panels 2i and 2n uniformly.

The fly-eye lenses 2a and 2b are arranged so as to face each other. Each of the fly-eye lenses 2a and 2b includes a plurality of minute lenses, and each minute lens of the fly-eye lens 2a faces each minute lens of the fly-eye lens 2b.
The light emitted from the light source unit 1 enters the fly-eye lens 2a. In the fly-eye lens 2a, the light emitted from the light source unit 1 is divided into a plurality of light beams corresponding to the number of microlenses. Each microlens has a similar shape to the effective display area of the liquid crystal panel, and condenses the light flux from the light source unit 1 in the vicinity of the fly-eye lens 2b. Each micro lens of the fly-eye lens 2b forms an image of the corresponding micro lens of the fly-eye lens 2a on the liquid crystal panels 2i and 2n.

The superimposing lens 2d and the field lens 2k direct chief rays from the microlenses of the fly-eye lens 2a toward the center of the liquid crystal panel 2n, and superimpose images of the microlenses on the liquid crystal panel 2n. Similarly, the superimposing lens 2d and the field lens 2f direct chief rays from the microlenses of the fly-eye lens 2a toward the center of the liquid crystal panel 2i, and superimpose images of the microlenses on the liquid crystal panel 2i.
The size of the secondary light source image formed by the fly-eye lens 2a is larger than the aperture shape of each minute lens of the fly-eye lens 2b. When the secondary light source image protrudes from the adjacent lens, the protruding portion becomes a component that irradiates the outside of the effective surface of the liquid crystal panel, and as a result, the light use efficiency decreases.

Reference is again made to FIG. Light emitted from the fly-eye lenses 2a and 2b enters the dichroic mirror 2e via the polarization conversion element 2c and the superimposing lens 2d. The polarization conversion element 2c aligns the polarization direction of incident light to P-polarized light or S-polarized light.
FIG. 6 shows the configuration of the polarization conversion element 2c. As shown in FIG. 6, the polarization conversion element 2c includes a polarization separation film 6a having the characteristics of reflecting S-polarized light and transmitting P-polarized light, and a half-wave plate 6b. In the polarization conversion element 2c, white light (random polarization) from the fly-eye lens 2b enters the polarization separation film 6a at an incident angle of approximately 45 °. The polarization separation film 6a separates random polarized light into P-polarized light and S-polarized linearly polarized light. The P-polarized light that has passed through the polarization separation film 6a passes through the half-wave plate 6b. The half-wave plate 6b rotates the polarization direction of the incident P-polarized light by 90 degrees and emits it as S-polarized light. On the other hand, the S-polarized light reflected by the polarization separation film 6a is reflected again by the adjacent polarization separation film 6a and emitted while maintaining the polarization. In this way, the polarization direction is aligned in a single direction.

White light (S-polarized light) that is emitted from the polarization conversion element 2c enters the dichroic mirror 2e via the superimposing lens 2d. The dichroic mirror 2e has a characteristic of reflecting light in the red wavelength region of visible light and transmitting light in other wavelength regions.
Of the light emitted from the polarization conversion element 2c, red light is reflected by the dichroic mirror 2e. The reflected light (red) of the dichroic mirror 2e is incident on the liquid crystal panel 2n via the field lens 2k, the reflecting mirror 21 and the polarizing plate 2m.
The transmitted light (green and blue) of the dichroic mirror 2e enters the dichroic mirror 2g via the field lens 2f. The dichroic mirror 2g has a characteristic of reflecting light in the green wavelength region of visible light and transmitting light in other wavelength regions.

The green light that has passed through the field lens 2f is reflected by the dichroic mirror 2g. The reflected light (green) of the dichroic mirror 2g enters the liquid crystal panel 2i via the polarizing plate 2h.
The blue light that has passed through the field lens 2f passes through the dichroic mirror 2g. The transmitted light (blue) of the dichroic mirror 2g enters the liquid crystal panel 2w via the relay lens 2p, the reflection mirror 2q, the relay lens 2r, the diffusion plate 2s, the reflection mirror 2t, the relay lens 2u, and the polarizing plate 2v.

Between the dichroic mirror 2g and the relay lens 2p, a rectangular uniform illumination image is formed by superimposing the images of the microlenses of the fly-eye lens 2a. The relay optical system including the relay lens 2p, the reflection mirror 2q, the relay lens 2r, the reflection mirror 2t, and the relay lens 2u is an equal-magnification image of a rectangular uniform illumination image formed between the dichroic mirror 2g and the relay lens 2p. Are formed on the liquid crystal panel 2w.
The relay optical system is configured to form a pupil position between the relay lens 2r and the reflection mirror 2t. The diffusion plate 2s is disposed at the pupil position of the relay optical system. By disposing the diffusing plate 2s at the pupil position of the relay optical system, it is possible to suppress the reduction rate of the light utilization efficiency in the subsequent stage of the diffusing component by the diffusing plate 2s and to effectively reduce speckle noise. is there.
More specifically, a Fourier image corresponding to the angle component is formed at the pupil position of the relay optical system. If the diffusing plate 2s is arranged at this pupil position, speckle reduction by angle multiplexing can be expected effectively.

Also in the illuminating device of the present embodiment, the diffusing plate 2s is disposed in the relay optical system closer to the liquid crystal panel 2w than the light source unit 1, so that the divergence emitted from the diffusing plate 2s is the same as in the first embodiment. The optical path length of light can be shortened, and the light utilization efficiency can be increased.
Further, since the diffusing plate 2s is arranged at the pupil position of the relay optical system 12, the spec noise can be reduced by using both the angle multiplexing effect and the diffusing effect as in the first embodiment. In this case, since the divergence angle of the diffusing plate 2s can be reduced, it is also possible to reduce the amount of light that does not contribute to the display of the projected image and increase the light utilization efficiency.

Moreover, in the illuminating device of this embodiment, the diffusion plate 1n is arrange | positioned immediately after the blue light source which consists of several blue LD1l. The diffuser plate 1n serves to reduce speckle noise, and at the same time, uniformizes the illumination light using the microlenses of the fly-eye lenses 2a and 2b (when the light beams from the microlenses are superimposed on the liquid crystal panel) The uniformity of illumination light). The greater the diffusion angle of the diffusion plate 1n, the more uniform the illumination light.
If the diffusing plate 1n is disposed in the light source unit 1, the optical path of the diverging light emitted from the diffusing plate 1n becomes long, so that the light use efficiency may be reduced. In the present embodiment, in consideration of the improvement of light utilization efficiency and speckle noise using the diffusion plate 2s, the improvement of the uniformity of illumination light using the diffusion plate 1n and the reduction of speckle noise, The diffusion angles of 1n and 2s are set appropriately. For example, when the diffusion plate 2s is mainly used for reducing speckle noise and the diffusion plate 1n is mainly used for improving the uniformity of illumination light, the diffusion angle of the diffusion plate 1n is set to the diffusion angle of the diffusion plate 2s. It may be larger than. In this case, it is possible to improve the uniformity of illumination light while maintaining the effect of reducing speckle noise.

In the illuminating device of this embodiment, a means for swinging or rotating at least one of the diffusion plates 1n and 2s may be provided. By swinging or rotating the diffusion plate 1n or the diffusion plate 2s, it is possible to reduce intensity distribution caused by the periodic structure of the diffusion plate itself. The speckle noise reduction effect when the diffusion plate 2s arranged on the Fourier plane is swung or rotated is larger than the speckle noise reduction effect when the diffusion plate 1n is swung or rotated. Therefore, it is desirable to provide means for swinging or rotating the diffusion plate 2s.
Moreover, in the illuminating device of this embodiment, you may insert a condensing lens before and behind the diffusion plate 1n. In this case, if the diffusion plate 1n is disposed on the focal plane of the condensing lens on the blue LD 1l side, the diffusion effect can be obtained more effectively, and the diffusion plate 1n can be made smaller.

Next, the configuration of the entire projector including the illumination device of the present embodiment will be described.
FIG. 7 is a schematic diagram showing the configuration of the projector.
Referring to FIG. 7, the projector includes an illumination device including the light source unit 1 and the illumination optical system 2 illustrated in FIG. 2, an image forming unit, and a projection optical system. Since the configuration of the illumination device is as described above, the description thereof is omitted here, and the image forming unit and the projection optical system will be described in detail.

The image forming unit includes polarizing plates 2h, 2j, 2m, 2o, 2v, 2x, liquid crystal panels 2i, 2n, 2w, and a cross dichroic prism 2y. The illumination optical system 2 emits green light toward the liquid crystal panel 2i, emits red light toward the liquid crystal panel 2n, and emits blue light toward the liquid crystal panel 2w.
A polarizing plate 2h and a polarizing plate 2j are respectively disposed on the incident surface side and the emission surface side of the liquid crystal panel 2i. Using these polarizing plates 2h and 2j, gradation characteristics corresponding to the spatial modulation of the liquid crystal panel 2i are obtained. Similarly, a polarizing plate 2m and a polarizing plate 2o are respectively disposed on the incident surface side and the emitting surface side of the liquid crystal panel 2n, and a polarizing plate 2v and a polarizing plate 2x are disposed on the incident surface side and the emitting surface side of the liquid crystal panel 2w, respectively. Has been placed. The liquid crystal panel 2i forms a green image, the liquid crystal panel 2n forms a red image, and the liquid crystal panel 2w forms a blue image.

The cross dichroic prism 2y has first to third entrance surfaces and an exit surface. The liquid crystal panel 2n is arranged to face the first incident surface of the cross dichroic prism 2y. The liquid crystal panel 2i is disposed to face the second incident surface of the cross dichroic prism 2y. The liquid crystal panel 2w is disposed to face the third incident surface of the cross dichroic prism 2y.
Light emitted from the liquid crystal panel 2n (red) is incident on the first incident surface of the cross dichroic prism 2y via the polarizing plate 2o. Light (green) emitted from the liquid crystal panel 2i is incident on the second incident surface of the cross dichroic prism 2y via the polarizing plate 2j. Light emitted from the liquid crystal panel 2w (blue) is incident on the third incident surface of the cross dichroic prism 2y via the polarizing plate 2x.

In the cross dichroic prism 2y, the red light incident from the first incident surface, the green light incident from the second incident surface, and the blue light incident from the third incident surface overlap each other and exit from the exit surface. . That is, the cross dichroic prism 2y combines the red image light, the green image light, and the blue image light from the liquid crystal panels 2n, 2i, and 2w into the same optical path and emits them.
The projection optical system includes a projection lens 3a disposed to face the exit surface of the cross dichroic prism 2y. Red image light, green image light, and blue image light emitted from the liquid crystal panels 2n, 2i, and 2w enter the projection lens 3a through the same optical path. The projection lens 3a enlarges and projects images formed by the liquid crystal panels 2n, 2i, and 2w.

  The cross dichroic prism 2y may have first and second dichroic films orthogonal to each other. In this case, the first dichroic film has a characteristic of reflecting the light in the red wavelength region in the visible wavelength region and transmitting the light in the other wavelength region, and the second dichroic film has the visible wavelength. Among the bands, it has a characteristic of reflecting light in a blue wavelength range and transmitting light in other wavelength ranges. The red light incident from the first incident surface is reflected by the first dichroic film and emitted from the emission surface toward the projection lens 3a. The blue light incident from the third incident surface is reflected by the second dichroic film and emitted from the emission surface toward the projection lens 3a. The green light incident from the second incident surface passes through the first and second dichroic films and is emitted from the emission surface toward the projection lens 3a.

  A half-wave plate may be provided on the two incident surfaces of the cross dichroic prism 2y. In this case, the first dichroic film reflects light in the red wavelength region out of the visible wavelength region with respect to S-polarized light, transmits light in other wavelength regions, and is visible with respect to P-polarized light. It has the characteristic of transmitting light in the wavelength range. The second dichroic film reflects light in the blue wavelength region of the visible wavelength range with respect to S-polarized light, transmits light in other wavelength regions, and transmits light in the visible wavelength region with respect to P-polarized light. It has the property of transmitting light. The S-polarized red light incident from the first incident surface is reflected by the first dichroic film and emitted from the emission surface toward the projection lens 3a. The S-polarized blue light incident from the third incident surface is reflected by the second dichroic film and emitted from the emission surface toward the projection lens 3a. S-polarized green light is converted to P-polarized green light by passing through the half-wave plate. The P-polarized green light incident from the second incident surface passes through the first and second dichroic films and is emitted from the emission surface toward the projection lens 3a. In this way, by performing color synthesis in accordance with the polarization direction, it is possible to set a wide wavelength band that can be effectively used during the synthesis of three colors by the cross dichroic prism 2y.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above-described embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Light source part 11 Illumination optical system 12 Relay optical system 14 1st diffuser plate

Claims (10)

A light source unit that emits mixed color light including a plurality of color lights that respectively illuminate a plurality of light modulation elements;
An illumination optical system that divides the light emitted from the light source unit into the plurality of color lights and irradiates each light modulation element with each color light through a different optical path;
One of the plurality of color lights is a laser beam,
The illumination optical system includes:
A relay optical system that forms an optical image formed using the laser beam on the light modulation element;
An illumination device comprising: at least one first diffuser plate disposed at a pupil position of the relay optical system. The relay optical system includes first to third relay lenses,
The first relay lens is disposed on the light source unit side, the third relay lens is disposed on the light modulation element side, and the second relay lens is disposed between the first and third relay lenses. The illumination device according to claim 1, wherein the illumination optical device is disposed and a pupil position of the relay optical system is formed between the second relay lens and the third relay lens. The light source unit is
A laser light source for emitting the laser light;
The lighting device according to claim 1, further comprising at least one second diffusion plate provided immediately after the laser light source. The light source unit is
A first condenser lens provided between the second diffusion plate and the laser light source;
A second condenser lens provided at a position facing the first condenser lens across the second diffusion plate,
The lighting device according to claim 3, wherein the second diffusion plate is disposed at a focal position of the first lens.   The lighting device according to claim 3 or 4, wherein a diffusion angle of the second diffusion plate is larger than a diffusion angle of the first diffusion plate.   The light source unit further includes a phosphor unit that emits color light that is fluorescence, and a color synthesis unit that combines the light emitted from the phosphor unit and the light emitted from the laser light source to emit the mixed color light. The lighting device according to any one of claims 3 to 5.   The illuminating device according to any one of claims 3 to 6, wherein the laser light source is a blue laser light source that emits blue laser light.   The lighting device according to any one of claims 1 to 7, further comprising means for swinging or rotating the first diffusion plate. The illumination device according to any one of claims 1 to 8,
A plurality of light modulation elements that respectively modulate the plurality of color lights emitted by the illumination device to form image light;
A projection optical system that projects the plurality of images formed by the plurality of light modulation elements in an overlapping manner.   The projector according to claim 9, wherein the light modulation element is a liquid crystal panel.

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