Projection-type image display device

Abstract

To provide a projection type image display device capable of improving contrast while suppressing brightness decline and color change.SOLUTION: The projection type image display device includes: an illumination optical system that generates illumination light by combining first color laser light and second color laser light from a light source; a light modulation unit that modulates the illumination light to generate image light; and a projection optical system that enlarges and projects the image light. The light source unit is configured to reduce the difference in height between the light source image of the first color laser light and the light source image of the second color laser light is small. A relay optical system includes a reflective first diaphragm with a variable aperture diameter located at a first pupil position. The projection optical system includes an absorption type second diaphragm with a variable aperture diameter, which is located at the second pupil position conjugate to the first pupil position.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a projection-type image display apparatus, and more particularly, to a configuration that uses a diaphragm to convert laser light from a light source into illumination light with a small spread to provide high-contrast image light. [Background Art]

[0002] With the advancement of solid-state light source technology, projection-type image display apparatuses are gradually replacing conventional discharge tube lamps as their light sources with LEDs or lasers, which have advantages such as long service life, being mercury-free and non-explosive. In particular, although the light output from a single laser element is small, the etendue of its light output is relatively small, so units formed by arranging a plurality of lasers in an array are used as light sources, and projectors with high output exceeding 5000 lumens have also been commercialized.

[0003] Laser units, in which a large number of lasers are two-dimensionally mounted at high density and housed in a package, are common. Further, while brightness has been achieved up to a certain level, higher contrast of projected images is increasingly being demanded for higher image quality.

[0004] However, in projection-type image display apparatuses, contrast is inferior to that of self-luminous devices. To improve contrast, it is necessary to realize illumination with small spread (illumination with a large F-number). However, in conventional light sources, when an illumination system with a large F-number is introduced for higher contrast, light with large spread among the light from the light source is removed, resulting in a significant loss of brightness.

[0005] Further, although image display devices are becoming smaller and higher in definition, light modulated by each minute pixel interferes with each other, becomes stray light in the projection optical system, and is one of the factors that impair contrast. In view of this situation, the following proposals have been made conventionally.

[0006] For example, in Patent Document 1, one aperture means is placed in either the illumination optical system or the projection optical system, so that at least one of the red, green, and blue colors of light has different light distribution characteristics from the other colors of light. When the aperture means is stopped down, a change in the color balance of the final image occurs, but this is corrected and maintained by modulation of the light source.

[0007] Furthermore, Patent Document 2 describes a system in which a variable aperture is provided in both the illumination optical system and the projection optical system, with the aperture ratio of the illumination optical system being greater than that of the projection optical system. This aims to obtain images with high contrast. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2006-178080 [Patent Document 2] Japanese Patent Publication No. 2006-285089 [Overview of the project] [Problems that the invention aims to solve]

[0009] In Patent Document 1, the color of the projected image changes with aperture changes. While color changes can be suppressed by changing the light source output, the overall color change may become unacceptable, and generally the brightness distribution of the center and periphery also changes. Thus, modulating the light source alone only provides partial improvement.

[0010] Patent Document 2 describes how contrast can be obtained by providing variable apertures in both the illumination optical system and the projection optical system. However, since a single xenon tube or mercury lamp is used as the light source, the brightness is easily reduced by the aperture of the illumination optical system.

[0011] This disclosure aims to provide a projection-type image display device that suppresses a decrease in brightness, suppresses color changes, and improves contrast.

[0012] The projection-type image display device of this disclosure includes a light source unit that emits a first color laser light which is blue and a second color laser light which is different from blue; an illumination optical system that generates illumination light by combining the first color laser light and the second color laser light from the light source unit; an optical modulation unit that generates image light by modulating the illumination light from the illumination optical system according to an image signal input from the outside; and a projection optical system that magnifies the image light emitted from the optical modulation unit and projects it onto an object to be projected. The light source unit includes a first light source component that includes a plurality of first laser light-emitting elements arranged in an array, each emitting a first color laser light; and a second light source component that includes a plurality of second laser light-emitting elements arranged in an array, each emitting a second color laser light. The area of ​​the light-emitting surface of the first light source component is different from the area of ​​the light-emitting surface of the second light source component. The illumination optical system includes a relay optical system that guides the illumination light to the optical modulation unit. The light source unit further includes an optical system that modifies at least one of the height of the light source image of the first color laser light and the height of the light source image of the second color laser light. The optical system of the light source unit is configured such that the difference between the height of the light source image of the first color laser light and the height of the light source image of the second color laser light is reduced. The relay optical system includes a first reflective aperture with a variable aperture diameter, positioned at a first pupil position where the illumination light is focused. The projection optical system includes a second absorbing aperture with a variable aperture diameter, positioned at a second pupil position which is conjugate to the first pupil position. [Effects of the Invention]

[0013] The projection-type image display device described herein is capable of providing a projection-type image display device that suppresses a decrease in brightness, suppresses color changes, and improves contrast. [Brief explanation of the drawing]

[0014] [Figure 1] Overall configuration diagram of the projection-type image display device according to the embodiment. [Figure 2] Front view showing the shape of the blue laser unit and the shapes of the red and green laser units. [Figure 3]Front view showing an example arrangement of a comparative example of red and green laser units [Figure 4] Explanatory diagram illustrating the light beam distribution obtained in the arrangement example of the comparative example of red and green laser units [Figure 5] Perspective view showing an arrangement example according to the present disclosure of red and green laser units [Figure 6] Explanatory diagram illustrating the light beam distribution obtained in the arrangement example according to the present disclosure of red and green laser units [Figure 7] Perspective view showing an arrangement example according to the present disclosure of a blue laser unit [Figure 8] Explanatory diagram illustrating the light beam distribution obtained in the arrangement example according to the present disclosure of a blue laser unit [Figure 9] Explanatory diagram illustrating the light beam distribution before incidence on an afocal optical system [Figure 10] Explanatory diagram illustrating the light beam distribution after emission from an afocal optical system [Figure 11] Perspective view showing an example configuration of an aperture stop unit [Figure 12] Comparison diagram of aperture diameters of a stop DETAILED DESCRIPTION OF EMBODIMENTS

[0015] Hereinafter, embodiments will be described in detail with appropriate reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of already well-known matters and repeated description for substantially the same configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding for those skilled in the art.

[0016] The inventor(s) provide the accompanying drawings and the following description for those skilled in the art to fully understand the present disclosure, and do not intend to limit the subject matter recited in the claims by these contents.

[0017] (Embodiment) Hereinafter, the embodiment will be described with reference to FIGS. 1 to 12. First, reference is made to FIG. 1. FIG. 1 is a configuration diagram of a projection-type image display apparatus 1 according to a first embodiment of the present disclosure.

[0018] [1-1. Structure] As shown in Figure 1, the projection-type image display device 1 comprises a light source unit 10, an illumination optical system 20, a light modulation unit 30, a projection lens unit 138 as a projection optical system, and a control unit 50. The light source unit 10 emits a first-color laser light which is blue, a second-color laser light which is green and different from blue, and a third-color laser light which is red and different from blue and green. The illumination optical system 20 generates illumination light by combining the blue laser light, green laser light, and red laser light from the light source unit 10. The light modulation unit 30 generates image light by modulating the illumination light from the illumination optical system 20 according to an image signal input from an external source. The projection lens unit 138 magnifies and projects the image light emitted from the light modulation unit 30 onto the projection target.

[0019] The light source unit 10 includes blue laser units 101a and 101b that emit blue laser light (hereinafter referred to as blue light), green laser units 102a and 102b that emit green laser light (hereinafter referred to as green light), and red laser units 103a and 103b that emit red laser light (hereinafter referred to as red light). The light source unit 10 has two laser light units for each color that emit laser light, and combines these laser lights to obtain white light.

[0020] The light sources for each of the aforementioned colors are arranged in an array, with a lens placed on the emission side of the laser light source to obtain parallel light. Of these, the blue laser has a higher luminescence efficiency than the other colors, so to obtain white light when combined with other colors, it can be constructed with a combination of laser light sources and lenses that has fewer light-emitting elements than the other colors. This makes it possible to construct a small package and keep the cost down.

[0021] Refer to Figure 2. Figure 2 is a front view showing the light source package, where Figure 2(a) is a front view of the blue laser units 101a and 101b, and Figure 2(b) is a front view of the green laser units 102a and 102b and the red laser units 103a and 103b, respectively. In this embodiment, as shown in Figure 2(a), the blue light is provided by blue laser units 101a and 101b, each having 14 laser light-emitting elements 104a. As shown in Figure 2(b), the green laser units 102a and 102b and the red laser units 103a and 103b are provided, each having 20 laser light-emitting elements 105a and 106a, respectively, for green and red light. The blue laser units 101a and 101b are examples of the first and fourth light source components, respectively. The green laser units 102a and 102b are examples of the second and fifth light source components, respectively. The red laser units 103a and 103b are examples of a third light source component and a sixth light source component, respectively.

[0022] Refer to Figures 3 and 4. Figure 3 is a diagram showing the configuration of a red laser unit or a green laser unit placed in a planar manner as a comparative example. Figure 4 is a diagram showing the arrangement of the light beam in the case of Figure 3. In the laser units of each color described above, the light-emitting part is concentrated in the center relative to the outer shape. As shown in Figure 3, in the comparative example, the red laser units 103a and 103b are placed side by side with their outer shapes touching. Similarly, the green laser units 102a and 102b are placed side by side with their outer shapes touching.

[0023] In reality, when the lasers are arranged in a planar configuration, more space is required between the light-emitting parts to avoid interference with the package's outer shape. Therefore, conventionally, there is a longer gap between each laser unit. In this configuration, as shown in Figure 4, for example, using red as an example, there is a gap of distance D1R between the luminous fluxes 103aL and 103bL from the red laser units 103a and 103b. That is, as a light source, the luminous flux including this distance D1R is treated as the red luminous flux 107R. Similarly, for green, there is a gap of distance D1R between the luminous fluxes 102aL and 102bL from the green laser units 102a and 102b. As a light source, the luminous flux including this distance D1R is treated as the green luminous flux 107G.

[0024] On the other hand, in this embodiment, the light beam from the light source is combined via a mirror, as shown in Figure 5. Figure 5 shows the arrangement of the red and green laser units according to this disclosure.

[0025] The luminous beam 103aL from the red laser unit 103a and the luminous beam 103bL from the red laser unit 103b are reflected by mirrors 108a and 108b, respectively, and emitted from the light source unit 10 as a single red luminous beam 109R. Mirrors 108a and 108b are, for example, dichroic mirrors. Mirror 108a has a thin film that reflects red light formed in the lower half of its region. Mirror 108b is the same mirror but positioned upside down, and has the characteristic of reflecting red light incident on the upper half of its region. By arranging mirrors 108a and 108b, the red laser units 103a and 103b can be positioned so that their outlines overlap in a front view or side view (see Figure 6(b)), and the arrangement areas of their respective laser light-emitting elements 106a do not overlap, thereby reducing the size of the combined luminous beam 107R. Mirror 108b is an example of a third mirror. Mirror 108a is an example of a sixth mirror.

[0026] Furthermore, the luminous beam 102aL from the green laser unit 102a and the luminous beam 102bL from the green laser unit 102b are reflected by mirrors 110a and 110b, respectively, and emitted from the light source unit 10 as a single green luminous beam 109G. Mirrors 110a and 110b are, for example, partial mirrors having total internal reflection characteristics on one side of their reflective surface, either above or below. For example, in mirror 110a, a total internal reflection surface is formed in the lower half of the region. Mirror 110b is the same mirror but positioned upside down, with a total internal reflection surface formed in the upper half of the region. By arranging mirrors 110a and 110b, the green laser units 102a and 102b can be positioned such that their outlines overlap in a front or side view (see Figure 6(b)), and the arrangement areas of their respective laser light-emitting elements 105a do not overlap, thereby reducing the size of the combined green luminous beam 109G. Mirror 110b is an example of a second mirror. Mirror 110a is an example of a fifth mirror.

[0027] As a result, the light from the light source after reflection by each mirror can be arranged at intervals of a distance D2R that is sufficiently smaller than the distance D1R (Figure 4), as shown in Figure 6 when the optical path reflected by mirrors 108a and 108b is viewed from the -Y direction in Figure 1. Figure 6 is an explanatory diagram illustrating the light beam distribution obtained in an example arrangement of the red and green laser units according to this disclosure. Figure 6(a) is a front view showing the light beam distribution obtained in an example arrangement of the red and green laser units according to this disclosure, and Figure 6(b) is a side view of the red and green laser units.

[0028] The red luminous flux 109R formed across this distance D2R can emit light of the same output with a smaller luminous flux than the red luminous flux 107R that includes distance D1R. Therefore, the distance D4R between the centroid position 103aG of the luminous flux 103aL from the red laser unit 103a and the centroid position 103bG of the luminous flux 103bL from the red laser unit 103b, which are ultimately emitted from the light source unit 10, is shorter than the distance D3R between the centroid position 103aF (see Figure 4) of each luminous flux 103aL and the centroid position 103bF of the luminous flux 103bL, which are formed by placing the outer shapes of the red laser unit 103a and the red laser unit 103b side by side in contact in the spacing direction. As a result, the red light can be converted into a luminous flux with high light density. In other words, the distance D4R between the centroid of the red laser beam reflected by mirror 108b and the centroid of the red laser beam reflected by mirror 108a is shorter than the distance D3R between the center position (centroid 103aF) of red laser unit 103a and the center position (centroid 103bF) of red laser unit 103b when the outlines of red laser unit 103a and red laser unit 103b are placed side by side in contact.

[0029] Furthermore, similar to red light, the green light beam 109G formed across the distance D2R can emit light of the same output with a smaller light beam than the green light beam including the distance D1R. Therefore, the distance D4R between the centroid position 102aF of the light beam 102aL from the green laser unit 102a and the centroid position 102bG of the light beam 102bL from the green laser unit 102b, which are ultimately emitted from the light source unit 10, is shorter than the distance D3R between the centroid position 102aF of the respective light beams 102aL (see Figure 4) and the centroid position 102bF of the light beam 102bL, which are formed by placing the outer shapes of the green laser unit 102a and the green laser unit 102b side by side in contact in the spacing direction. As a result, green light can also be converted into a light beam with a high light density. In other words, the distance D4R between the centroid of the green laser beam reflected by mirror 110b and the centroid of the green laser beam reflected by mirror 110a is shorter than the distance D3R between the center position (centroid 102aF) of green laser unit 102a and the center position (centroid 102bF) of green laser unit 102b when the outer shapes of green laser unit 102a and green laser unit 102b are placed side by side in contact.

[0030] As shown in Figure 5, the green laser units 102a and 102b are the same size as, for example, the red laser units 103a and 103b, and mirrors 110a and 110b, which have total internal reflection characteristics, are arranged on one side of the reflective surface above or below the same optical path. Therefore, the light source luminous flux of green light obtained by passing the light reflected by mirrors 110a and 110b through the red reflective dichroic mirrors 108a and 108b is configured to be superimposed on the red luminous flux 109R.

[0031] Although the shape, size, and orientation of the laser units differ for blue light and red light, if the laser units are arranged on the same plane as in conventional designs, the spacing between the laser units becomes large to avoid interference between the respective light source packages. For blue light, as with red and green light, a small blue light beam can be achieved by combining the light using mirrors 111a and 111b, which have reflective properties on only one side (upper or lower). Mirror 111b is an example of a first mirror. Mirror 111a is an example of a fourth mirror.

[0032] Figure 7 is a perspective view showing an example of the arrangement of a blue laser light source according to this disclosure. Figure 8 is an explanatory diagram illustrating the luminous flux distribution obtained in the example of the arrangement of the blue laser unit according to this disclosure. Figure 8(a) is a front view showing the luminous flux distribution obtained in the example of the arrangement of the blue laser unit according to this disclosure, and Figure 8(b) is a side view of the blue laser unit. Thus, Figure 7 shows an example of the arrangement of the blue light source package and mirror, and Figure 8 shows the combined luminous flux of the light source.

[0033] Similar to red light, the blue light source beam 112 formed across the distance D6R can emit light of the same output with a smaller beam than the blue light beam containing the beams 101aL and 101bL from the two blue laser units 101a and 101b, which are positioned so that their outlines touch. Therefore, the distance D8R between the centroid position 101aG of the beam 101aL from blue laser unit 101a and the centroid position 101bG of the beam 101bL from blue laser unit 101b, which are ultimately emitted from the light source unit 10, is shorter than the distance between the centroid position of each beam 101aL and the centroid position of the beam 102bL, which are formed by placing the outlines of blue laser units 101a and 101b side by side in contact in the spacing direction, similar to red and green light. This allows the blue light to be converted into a beam with a high light density. In other words, the distance D8R between the centroid of the blue laser beam reflected by mirror 111b and the centroid of the blue laser beam reflected by mirror 111a is shorter than the distance between the center of blue laser unit 101a and the center of blue laser unit 101b when the outer shapes of blue laser unit 101a and blue laser unit 101b are placed side by side in contact.

[0034] In addition, in Figures 1 and 7, there is no light that passes through mirrors 110a and 111a, so they can be ordinary mirrors that reflect all visible light, and for the same reason, mirrors 110b and 111b can be mirrors that partially reflect all visible light.

[0035] The illumination optical system 20 uses laser light from the red laser units 103a and 103b and green laser units 102a and 102b shown in Figure 5, and the blue laser units 101a and 101b shown in Figure 7. However, since the red and green light source beams 109 and the blue light source beam 112 are of different magnitudes, if they are combined as is, the height of each ray incident on the focusing lens 114 that focuses the light onto the rod integrator 113 will be different. As a result, the red and green laser light is incident on the rod integrator 113 at a larger angle than the blue laser light, causing the projected image to have stronger red and green in the peripheral parts than in the center, resulting in color unevenness.

[0036] Therefore, in this embodiment, the light source unit 10 includes a blue afocal optical system 115 that equalizes the height of the blue, red, and green light beams, and a red and green afocal optical system 116. The blue afocal optical system 115 includes a convex lens 115a and a concave lens 115b. The red and green afocal optical system 116 includes a convex lens 116a and a concave lens 116b. The blue light emitted from the blue afocal optical system 115 and the red and green light emitted from the red and green afocal optical system 116 are combined by a blue-transmitting dichroic mirror 117 and incident on the focusing lens 114.

[0037] Refer to Figure 9. Figure 9 is an explanatory diagram illustrating the distribution of light beam before incidence into the afocal optical system. Here, the height of the light beam (light source image) may be the length in the width direction, which is the minor axis DS direction, of each laser beam constituting the blue laser beams 101aL and 101bL, or it may be the length in the major axis DL direction. Below, an example in which the width direction of the light beam is equalized as the height of the light beam will be explained. Here, the width of the light beam incident on the blue afocal optical system 115 is denoted as BW1, the width of the light beam emitted after passing through the blue afocal optical system 115 is denoted as BW2, and the magnification of the blue afocal optical system 115 is denoted as BW2 / BW1. That is, the blue afocal optical system 115 (an example of the first afocal optical system) changes the width BW1 (height of the light source image of the blue laser beam) to the width BW2 (first height).

[0038] Similarly, the width of the light beam incident on the red and green afocal optical system 116 is RGW1, and the width of the light beam emitted after passing through the red and green afocal optical system 116 is RGW2, so the magnification of the red and green afocal optical system 116 is RGW2 / RGW1. That is, the red and green afocal optical system 116 (an example of a second afocal optical system) changes the width RGW1 (height of the source image of the green laser light) to the width RGW2 (second height). Also, the red and green afocal optical system 116 (an example of a second afocal optical system) changes the width RGW1 (height of the source image of the red laser light) to the width RGW2 (second height). Here, the height of the source of the green laser light emitted after passing through the red and green afocal optical system 116 is not necessarily the same as, and may be different from, the height of the source of the red laser light emitted after passing through the red and green afocal optical system 116. Note that the afocal optical system 115 for blue light and the afocal optical systems 116 for red and green light are examples of optical systems for the light source unit 10.

[0039] Reference is made to FIG. 10. FIG. 10 is an explanatory diagram illustrating the light beam distribution after emission from an afocal optical system. In this case, when attempting to match the height of light rays incident on the condenser lens 114, BW2=RGW2 is obtained, while since BW1<RGW1, the afocal optical system for blue 115 and the afocal optical system for red and green 116 have different magnifications. In this manner, the magnification of the afocal optical system for blue 115 and the afocal optical system for red and green 116 are set to be different such that the image width BW2 of the blue laser light beams 101aL and 101bL and the image width RGW2 of the green and red laser light beams 102aL, 102bL, 103aL, and 103bL are respectively larger than the image width BW1 of the light beams 101aL and 101bL upon emission thereof and the image width RGW1 of the light beams 102aL, 102bL, 103aL, and 103bL upon emission thereof, and become equal to each other. However, the matching in the width direction described here is merely an example; depending on the light amount distribution of each light source and the overall optical characteristics, matching may be performed in the major axis DL direction of the laser light, or matching may be performed in both the minor axis DS direction and the major axis DL direction of the laser light, or matching may be performed such that the blue light beam spreads more than the red and green light beams in the minor axis DS direction of the laser light, and the red and green light beams spread more than the blue light beam in the major axis DL direction of the laser light. As described above, the afocal optical system for blue 115 and the afocal optical system for red and green 116 are configured such that the difference between the width BW2 and the width RGW2 is reduced. More specifically, the afocal optical system for blue 115 and the afocal optical system for red and green 116 are configured such that the difference between the width BW2 and the width RGW2 is smaller than the difference between the width BW1 and the width RGW1. Here, each of the difference between the width BW2 and the width RGW2 and the difference between the width BW1 and the width RGW1 means the absolute value of the difference.

[0040] In particular, the afocal optical system 116 for red and green light has a greater reduction in the width of the light beam. Note that if the blue light source is even smaller, or if the condensing lens 114 is larger and BW1=BW2 is used, the blue afocal optical system 115 is unnecessary, but the magnification of the red and green afocal optical system 116 will be even smaller. Figure 10 shows the magnifications of blue, red, and green light superimposed. Thus, the light source unit 10 is equipped with a blue afocal optical system 115 and a red and green afocal optical system 116, each with different magnifications.

[0041] The light source unit 10 does not necessarily have to include both the blue afocal optical system 115 and the red and green afocal optical systems 116. In one example, the light source unit 10 includes the blue afocal optical system 115 but does not include the red and green afocal optical systems 116. In this case, since the light source unit 10 does not include the red and green afocal optical systems 116, the width RGW1 is equal to the width RGW2. The blue afocal optical system 115 is configured such that the difference between the width BW2 and the width RGW2 is smaller than the difference between the width BW1 and the width RGW1. Specifically, the blue afocal optical system 115 reduces the difference between the width BW2 and the width RGW2 by expanding the width BW1 to the width BW2. In another example, the light source unit 10 does not include the blue afocal optical system 115 but does include the red and green afocal optical systems 116. In this case, since the light source unit 10 does not have a blue afocal optical system 115, the width BW1 is equal to the width BW2. The red and green afocal optical systems 116 are configured such that the difference between the width BW2 and the width RGW2 is smaller than the difference between the width BW1 and the width RGW1. Specifically, the red and green afocal optical systems 116 reduce the width RGW1 to the width RGW2, thereby reducing the difference between the width BW2 and the width RGW2.

[0042] The illumination optical system 20 comprises a rod integrator 113 and a relay optical system 121. The relay optical system 121 comprises a lens 118, an illumination aperture unit 119, a lens 123, a folding mirror 124, and a field lens 125.

[0043] Light incident on the rod integrator 113 undergoes multiple reflections within the rod integrator 113 before passing through the lens 118 and reaching the illumination aperture unit 119. The illumination aperture unit 119 is positioned at or near the location where the light source image is formed by the lens 118. This position becomes the first pupil position of the relay optical system 121 that transfers the image from the output port 113a of the rod integrator 113 onto the image display element.

[0044] Light that passes through the aperture 122 of the illumination aperture unit 119 passes through the lens 123, is reflected by the folding mirror 124, then passes through the field lens 125, and enters the total internal reflection prism 126.

[0045] The optical modulation unit 30 comprises a total reflection prism 126, a color prism unit 131, and optical modulation elements 137R, 137G, and 137B.

[0046] The total internal reflection prism 126 is made up of a first prism 127 and a second prism 128 fixed together while maintaining a small gap (air gap). Light incident on the total internal reflection prism 126 is totally reflected by the total internal reflection surface 129, and then passes through surface 130 before entering the color prism unit 131.

[0047] This color prism unit 131 is constructed by bonding together a first prism 133 having a blue-transmitting dichroic mirror surface 132 that reflects blue light, a second prism 135 having a green-transmitting dichroic mirror surface 134 that reflects red and blue light, and a third prism 136. However, an air gap is provided between the first prism 133 and the second prism 135 to utilize total internal reflection.

[0048] As shown in Figure 1, optical modulation elements 137R, 137G, and 137B are arranged facing the end faces of each prism. These optical modulation elements are, for example, DMDs in which tiny mirrors are arranged two-dimensionally. The tilt direction of the tiny mirrors is controlled in two directions in accordance with the video signal input from the outside via the control unit 50. When the signal is ON, the reflected light reflected by the tiny mirrors returns to the color prism unit 131 at an incident angle of 0°. When the signal is OFF, the reflected light reflected by the tiny mirrors returns to the color prism unit 131 at a larger angle. Optical modulation element 137B is for blue light modulation, optical modulation element 137R is for red light modulation, and optical modulation element 137G is for green light modulation.

[0049] The light modulation elements 137R, 137G, and 137B, each in which the pixels are in white display mode, return to the color prism unit 131, and after passing through there, they pass through the second prism 128 and the first prism 127 of the total internal reflection prism 126 and enter the projection lens unit 138.

[0050] A projection aperture unit 139 is positioned at the second pupil position of the projection lens unit 138. The first pupil position where the illumination aperture unit 119 is positioned and the second pupil position where the projection lens unit 138 is positioned are conjugate to each other. Incident light to the projection lens unit 138 passes through the aperture 140 and reaches the screen, which is the projection target (not shown in the figure). The projection lens unit 138 is detachably fixed via its projection lens flange portion 141 to a mounting member 142 provided on the housing of the main body of the projection-type image display device 1 (not shown in the figure). Such a fixing portion can be made up of a bayonet or the like. In this way, by inputting different signals to the light modulation elements 137R, 137G, and 137B according to the image signal, a color display can be realized on the screen.

[0051] The illumination aperture unit 119 has high reflectivity on its surface and is further equipped with multiple vane members that have diffusion properties. The diffuse reflection of the illumination aperture unit 119 is formed by the textured finish of the surface and the stucco pattern treatment with many randomly arranged irregularities. As a result, even when exposed to strong light, the heat generated by the aperture itself is suppressed, and the reflected light is diffused and focused at an arbitrary position to suppress heat generation and burning of other components.

[0052] However, even highly reflective materials still absorb heat, so materials with excellent thermal conductivity, such as aluminum or copper, are used to suppress the occurrence of burning and other issues. Thus, the illumination aperture unit 119 of the illumination optical system 20 is composed of multiple movable vane members made of materials that have been treated to have high thermal conductivity and high reflectivity, and its surface is a diffuse reflective surface. In one example, the multiple vane members mainly diffusely reflect more than 70% of the light incident on the multiple vane members. In another example, the multiple vane members diffusely reflect more than 80% of the light incident on the multiple vane members.

[0053] These apertures are driven by actuators connected via cams under control from the control unit 50 of the main body 3, and are configured to allow arbitrary setting of the aperture diameter of the opening 122 of the illumination aperture unit 119. An example of the specific structure of the illumination aperture unit 119 is shown in Figure 11. Figure 11 is a perspective view showing an example of the configuration of the illumination aperture unit 119 and the projection lens unit 138.

[0054] The illumination aperture unit 119 is equipped with a stepping motor 143 as an actuator, a slip clutch 144 on its output shaft, and a connecting gear 145. This is connected to a fan-shaped gear 146 extending from an aperture cam (not shown in the figure), thereby moving multiple aperture blades 147 according to the amount of rotation of the stepping motor 143, and thereby controlling the aperture diameter of the aperture 122. The incident side is equipped with a front plate 148 made of high-reflectivity aluminum. This front plate 148 may also be treated to diffuse light.

[0055] Similarly, the projection aperture unit 139 of the projection lens unit 138 also has multiple aperture blades 147 driven via cams, and the diameter of the aperture 140 is variable by control from the main body. Unlike the illumination aperture unit 119, the surface treatment of the aperture blades 147 of the projection lens unit 138 is heat-resistant black. This suppresses the generation of stray light within the projection lens unit 138. Thus, the projection aperture unit 139 contains a light-absorbing material and has multiple movable aperture blades 147. In one example, the multiple aperture blades 147 absorb more than 90% of the visible light incident on them. In another example, the multiple aperture blades 147 absorb more than 95% of the visible light incident on them. Furthermore, the relationship between the F-number of the illumination optical system 20, determined by the illumination aperture unit 119, and the F-number of the projection lens unit 138 (projection optical system), determined by the projection aperture unit 139, is maintained such that the F-number of the illumination optical system 20 is always greater than or equal to the F-number of the projection lens unit 138. This reduces the thermal load on the projection aperture unit 139.

[0056] Illumination optical system F-number ≥ Projection optical system F-number As mentioned above, the projection lens unit 138 is a replaceable lens type. Therefore, when the projection lens unit 138 is removed from the main body 3 of the projection-type image display device 1, or when it is mounted on a body other than the main body 3 that satisfies the functions of this disclosure, the aperture diameter of the projection aperture unit 139 is set to the first aperture diameter PD1, which is the first state. In other words, when the projection lens unit 138 is removed from the main body 3 of the projection-type image display device 1 and is not controlled externally, the aperture diameter of the projection aperture unit 139 is set to the first aperture diameter PD1. When mounted on the main body 3 that satisfies the functions of this disclosure, the aperture diameter of the projection aperture unit 139 is set to the second aperture diameter PD2, which is the second state, and when mounted on the main body 3 that satisfies the functions of this disclosure and controlled to stop down, the aperture diameter of the projection aperture unit 139 is set to the third aperture diameter PD3. The first aperture diameter PD1, the second aperture diameter PD2, and the third aperture diameter PD3 are configured such that the following relationship holds.

[0057] First aperture diameter PD1 > Second aperture diameter PD2 > Third aperture diameter PD3 Figure 12 shows a comparison diagram of aperture diameters. Figure 12(a) is an explanatory diagram showing the first aperture diameter PD1 in the first state, Figure 12(b) is an explanatory diagram showing the second aperture diameter PD2 in the second state, and Figure 12(c) is an explanatory diagram showing the third aperture diameter PD3 in the third state. Note that the first aperture diameter PD1 in the first state and the second aperture diameter PD2 in the second state are predetermined sizes, and the third aperture diameter PD3 can be set to any size from the second state to the third state by control from the control unit 50 in the main body 3. By further narrowing the aperture diameter of the projection aperture unit 139 from the second state, the amount of light projected decreases, but the contrast can be increased. Therefore, depending on how the projection-type image display device 1 is used, such as the projection size and ambient brightness, if a higher contrast than the second state is desired, the desired contrast can be obtained by setting the third aperture diameter PD3 to any size. In other words, the projection aperture unit 139 is configured to move from the second state to a third state in which it is set to a third aperture diameter PD3 that is smaller than the second aperture diameter PD2. The third aperture diameter PD3 is set to any size smaller than the second aperture diameter PD2 by control from the control unit 50 in the main body 3.

[0058] As described above, when the projection lens unit 138 is mounted on a projector body not according to this disclosure, if there is no illumination aperture unit 119, the blades of the projection aperture unit 139 may be damaged by heat if they are directly exposed to the image light. When mounted on a body 3 that satisfies the functions of this disclosure, the illumination light is narrowed by the illumination aperture unit 119, so even if the second aperture diameter PD2 is smaller than the first aperture diameter PD1, it is possible to prevent the blades of the projection aperture unit 139 from being damaged by heat. Therefore, the first aperture diameter PD1 and the second aperture diameter PD2 have the relationship described above. In other words, the projection aperture unit 139 is configured such that the first aperture diameter PD1 in the first state is always larger than the second aperture diameter PD2 in the second state.

[0059] Furthermore, in the case of the set according to this disclosure, the second aperture diameter PD2 is achieved by mechanical or electrical action when the set is mounted, while in the case of other sets, the first aperture diameter PD1 is maintained because there is no such action when the set is mounted.

[0060] Regarding the detection of attachment / detachment of the main body 3 and the projection lens unit 138, and the aperture drive, as described above, electrical contacts may be provided on both the main body 3 and the projection lens unit 138 for drive, or a mechanism structure that operates only when the main body 3 is equipped with the functions of this disclosure may be provided. In that case, it can be realized by making the projection aperture driveable. The basic structure of the projection aperture unit 139 is the same as that of the illumination aperture unit 119, but since it needs to be housed inside the projection lens unit 138, a smaller actuator may be used, and the connecting gears may also be small and arranged in a ring shape.

[0061] Thus, with the projection lens unit 138 mounted on the projection-type image display device 1, the projection lens unit 138 can set the aperture diameter of the projection diaphragm unit 139 by mechanical or electrical control from the main body 3 of the projection-type image display device 1.

[0062] [1-2. Effects, etc.] As described above, the projection-type image display device 1 according to this embodiment includes a light source unit 10 that emits a first color laser light which is blue and a second color laser light which is green, which is different from blue; an illumination optical system 20 that generates illumination light by combining the first color laser light and the second color laser light from the light source unit 10; an optical modulation unit 30 that generates image light by modulating the illumination light from the illumination optical system 20 according to an image signal input from the outside; and a projection lens unit 138 that magnifies and projects the image light emitted from the optical modulation unit 30 onto a projection target. The light source unit 10 includes blue laser units 101a, 101b in which a plurality of blue laser light-emitting elements that each emit blue laser light are arranged in an array; green laser units 102a, 102b in which a plurality of green laser light-emitting elements that each emit green laser light are arranged in an array; and red laser units 103a, 103b in which a plurality of red laser light-emitting elements that each emit red laser light are arranged in an array. The area of ​​the light-emitting surfaces of the blue laser units 101a and 101b differs from the area of ​​the light-emitting surfaces of the green laser units 102a and 102b and the red laser units 103a and 103b. The illumination optical system 20 includes a relay optical system 121 that guides illumination light to the light modulation unit 30. In the relay optical system 121, at the first pupil position where the illumination light is focused, there are blue afocal optical system 115 and red and green afocal optical systems 116 with different magnifications depending on the blue, green, and red laser light, such that the height of the light source image of the blue, green, and red laser light is equal to the height when emitted from each laser unit. The relay optical system 121 includes a reflective illumination diaphragm unit 119 with a variable aperture at the first pupil position. The projection lens unit 138 includes an absorptive projection diaphragm unit 139 with a variable aperture at a second pupil position conjugate to the first pupil position.

[0063] By configuring the system as described above, and by equipping it with a high F-number illumination and projection lens unit, the entire projection area can be made white or black, and high contrast can be obtained not only in terms of the brightness ratio between the two, but also in terms of window contrast, which is the display of a small area of ​​black within a white screen. In particular, the latter can be made to perform better than conventional systems because reflected light and stray light within the projection optical system, especially within the projection lens unit 138, are causes of degradation. Furthermore, in this disclosure, since the light source unit 10 is a laser and the spread of light is small, the spread of illumination light in the illumination optical system 20 can be minimized, and the brightness does not drop as much even with a high F-number due to the illumination aperture unit 119 and projection aperture unit 139 compared to conventional systems. In addition, since the relay optical system 121 is equipped with afocal optical systems 115 and 116 with different magnifications, the intensity distribution in the pupil of the illumination optical system 20 is almost the same for each color of light. Therefore, even when the illumination aperture unit 119 further narrows the aperture 122 in conjunction with the projection aperture unit 139 of the projection lens unit 138 to obtain higher contrast, the balance between each color does not change, and an image without color change can be provided.

[0064] The light-emitting surface area of ​​the blue laser units 101a and 101b is smaller than that of the green laser units 102a and 102b and the red laser units 103a and 103b. As a result, the amount of blue light is concentrated in the central region, and when this is combined with the green and red laser light, the central region of the combined light will appear bluish, while the peripheral region will lack blue light. In this state, when the illumination light is focused by the illumination aperture unit 119 and the image light is focused by the projection aperture unit 139, the color may change due to vignetting of the surrounding light depending on the degree of focusing. To address this, optical systems with different magnifications are provided according to each laser light so that the height of the light source image of the blue, green, and red laser light is equal to the height at which they are emitted from each laser unit. This reduces the concentration of blue light in the central region and reduces the color change due to vignetting. Furthermore, the phrase "so that the height of the light source images of the blue, green, and red laser beams are equal to the height at which they are emitted from their respective laser units" includes not only cases where they are exactly equal, but also cases where the height of the light source images of the blue, green, and red laser beams is closer to the height at which they are emitted from their respective laser units.

[0065] (Other embodiments) As described above, the above embodiments have been explained as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to these embodiments and can be applied to embodiments that have been modified, replaced, added, or omitted. Furthermore, it is possible to create new embodiments by combining the components described in the above embodiments.

[0066] In this embodiment, the light beams of each color were arranged at high density by devising the arrangement of the laser unit and mirrors, which are the light sources. However, the means are not limited to this, and the same effect can be expected even with a prism, as long as the final light source image size (light beam height from the optical axis) is converted to a similar value by changing the afocal optical diameter magnification according to the color of the light.

[0067] In this embodiment, the optical modulation unit 30 was a system equipped with three DMD devices as optical modulation elements, but it can also be applied to a one-chip system using one DMD or a system using three LCD panels. However, the mainstream LCD panel system uses a microlens array as the integrator, and in this case, the same effect can be obtained by placing the illumination aperture near the exit-side microlens array, which is the pupil position.

[0068] In this embodiment, the light source unit 10 comprises a blue laser unit, a green laser unit, and a red laser unit, emitting blue laser light, green laser light, and red laser light respectively, but is not limited to this configuration. The light source unit 10 may also comprise a blue laser unit and a green laser unit, or a blue laser unit and a red laser unit, emitting two-color laser light.

[0069] As described above, embodiments have been explained as examples of the technology in this disclosure. For this purpose, attached drawings and a detailed description have been provided. Therefore, among the components described in the attached drawings and detailed description, there may be not only components that are essential for solving the problem, but also components that are not essential for solving the problem, in order to illustrate the above technology. For this reason, the mere fact that these non-essential components are described in the attached drawings and detailed description should not be immediately assumed to be essential.

[0070] Furthermore, since the embodiments described above are for illustrative purposes of the technology described herein, various modifications, substitutions, additions, omissions, etc., can be made within the claims or their equivalents.

[0071] (Summary of the embodiment) (1) The projection-type image display device of the present disclosure comprises: a light source unit that emits a first color laser light which is blue and a second color laser light which is a different color from blue; an illumination optical system that generates illumination light by combining the first color laser light and the second color laser light from the light source unit; an optical modulation unit that generates image light by modulating the illumination light from the illumination optical system in accordance with an image signal input from the outside; and a projection optical system that magnifies and projects the image light emitted from the optical modulation unit onto a projection target. The light source unit comprises a first light source component in which a plurality of first laser light-emitting elements, each emitting a first color laser light, are arranged in an array, and a second light source component in which a plurality of second laser light-emitting elements, each emitting a second color laser light, are arranged in an array. The area of ​​the light-emitting surface of the first light source component is different from the area of ​​the light-emitting surface of the second light source component. The illumination optical system comprises a relay optical system that guides the illumination light to the optical modulation unit. In the relay optical system, at the first pupil position where the illumination light is focused, optical systems with different magnifications are provided according to the first and second color laser beams, such that the height of the light source images of the first and second color laser beams is equal to their respective emission heights. The relay optical system is provided at the first pupil position with a reflective first diaphragm having a variable aperture diameter. The projection optical system is provided at a second pupil position conjugate to the first pupil position with an absorptive second diaphragm having a variable aperture diameter.

[0072] This allows for high contrast and reduces reflected and stray light within the projection optical system. Furthermore, because the light source is a laser with limited spread, the spread of illumination light in the illumination optical system is minimized, resulting in less brightness loss even at higher F-numbers compared to conventional systems. In addition, by incorporating optical systems with different magnifications in the relay optical system, the intensity distribution within the pupil of the illumination optical system is almost the same for each color of light. Therefore, even when the illumination aperture is further narrowed in conjunction with the aperture of the projection lens unit to obtain higher contrast, the balance between each color remains unchanged, providing an image without color shift.

[0073] (2) In the projection-type image display device of (1), the light source unit emits laser light of a third color different from the first and second colors, and the illumination optical system generates illumination light by combining the laser light of the first color, the laser light of the second color, and the laser light of the third color. The light source unit includes a third light source component in which a plurality of third laser light-emitting elements, each emitting laser light of the third color, are arranged in an array. The area of ​​the light-emitting surface of the first light source component is different from the area of ​​the light-emitting surface of at least one of the second and third light source components. The optical system of the relay optical system is configured such that the magnification of at least the laser light of the first color is different from the magnification of the laser light of the second color or the third color, such that the height of the light source images of the first color, second color, and third color laser light at the first pupil position where the illumination light is focused is equal to the height of the respective emission heights of the laser light of the first color.

[0074] (3) In the projection-type image display device of (1) or (2), the projection optical system is a projection lens unit that can be attached to and detached from the main body of the projection-type image display device. The projection lens unit is equipped with a second aperture, and when the second aperture is not controlled externally, the second aperture is in a first state set to a first aperture diameter, and when the projection lens unit is mounted on a predetermined projector, the second aperture is in a second state set to a second aperture diameter. The aperture diameters of the second aperture in the first state and the second state are always controlled such that the aperture diameter in the first state > the aperture diameter of the aperture in the second state.

[0075] (4)(3) In the projection-type image display device, when the projection lens unit is mounted on a predetermined projection-type image display device, the second aperture of the projection lens unit can be changed to a third state in addition to a second state in which it is set to a second aperture diameter, under control from the main body of the projection-type image display device. The aperture diameters of the second aperture in the first, second, and third states have the relationship: aperture diameter in the first state > aperture diameter in the second state > aperture diameter in the third state, and the third aperture diameter of the second aperture can be set to any size from the second state to the third state under control from the main body.

[0076] In the projection-type image display device of (5)(4), with the projection lens unit mounted on the projection-type image display device, the projection lens unit can set the aperture diameter of the second diaphragm by mechanical operation control or electrical operation control from the main body of the projection-type image display device.

[0077] (6) In any one of the projection-type image display devices described in (1) to (5), the first aperture of the illumination optical system is composed of a plurality of movable blades made of a material that has been treated to have high thermal conductivity and high reflectivity, and its surface is a diffuse reflecting surface.

[0078] (7) In any one of the projection-type image display devices described in (3) to (5), the second aperture of the projection lens unit comprises a light-absorbing material and has a plurality of movable blades.

[0079] (8) In any one of the projection-type image display devices described in (1) to (7), the illumination optical system is equipped with afocal optical systems of different magnifications.

[0080] In the projection-type image display device of (9)(8), the afocal optical system provided in at least the first color optical path has a different magnification from the afocal optical systems provided in the other color optical paths.

[0081] (10) In any one of the projection-type image display devices described in (1) to (9), the laser light of a first color emitted from the light source unit is emitted together from the laser light of a first color emitted from each of the multiple first light source components, and the distance between the centroid positions of the respective light beams from the multiple first light source components is shorter than the distance formed when the outer shapes of each first light source component are placed touching in the spacing direction.

[0082] (11) In any one of the projection-type image display devices described in (1) to (10), the second color laser light emitted from the light source unit is emitted together from the second color laser light emitted from each of the multiple second light source components, and the distance between the centroid positions of the respective light beams from the multiple second light source components is shorter than the distance formed when the outer shapes of each second light source component are placed touching in the spacing direction.

[0083] In the projection-type image display device of (12)(2), the laser light of the third color emitted from the light source is emitted by combining the laser light of the third color emitted from each of the multiple third light source components, and the distance between the centroid positions of the respective light beams from the multiple third light source components is shorter than the distance formed by lining up the outer shapes of each third light source component in the spacing direction. [Industrial applicability]

[0084] This disclosure is applicable to projection display devices that use laser light as a light source. [Explanation of symbols]

[0085] 1. Projection-type image display device 10 Light source section 20 Illumination optical system 30 Optical Modulation Section 50 Control Unit 101a, 101b Blue Laser Unit 102a, 102b Green Laser Unit 103a, 103b Red Laser Unit 104a Laser light-emitting element 105a Laser light-emitting element 106a Laser light-emitting element 107G, 109G Green luminous flux 107R, 109R red luminous flux 108a, 108b mirror 110a, 110b, 111a, 111b mirror 112 Light source luminous flux 113 Rod Integrator 113a Output port 114 Focusing lens 115 Afocal Optics for Blue 115a convex lens 115b concave lens 116 Afocal Optics for Red and Green 116a Convex lens 116b Concave lens 117 Blue Transmitting Dichroic Mirror 118 lenses 119 Illumination diaphragm unit 121 Relay Optics 122 Aperture 123 Lens 124 Folding mirror 125 Field Lens 126 Total Internal Reflection Prism 127 The First Prism 128 The Second Prism 129 Total reflection surface 130 The first prism surface 131 Color Prism Unit 132 Blue Transmitting Dichroic Mirror Surface 133 The First Prism 134 Green Transmitting Dichroic Mirror Surface 135 The Second Prism 136 The Third Prism 137R, 137G, 137B Optical Modulators 138 Projection lens unit 139 Projection aperture unit 141 Projection lens flange section 142 Mounting component 143 Stepping motor 144 Slip Clutch 145 gear 146 Fan-shaped gear 147 aperture blades 148 Front plate

Claims

1. A light source unit that emits a laser beam of a first color and a laser beam of a second color different from the first color, An illumination optical system that generates illumination light by combining the first color laser light and the second color laser light from the light source unit, A light modulation unit generates image light by modulating illumination light from the illumination optical system in accordance with an image signal input from an external source, The system includes a projection optical system that amplifies the image light emitted from the light modulation unit and projects it onto the object to be projected, The illumination optical system includes a relay optical system that guides the illumination light to the light modulation unit. The relay optical system includes a first reflective aperture having a variable aperture diameter, positioned at a first position where the illumination light is focused. The projection optical system includes a second absorption-type aperture having a variable aperture diameter, positioned at a second position conjugate to the first position. The light source unit has an optical system that modulates at least one of the first color laser light or the second color laser light so that the difference in height between the light source images of the first color laser light and the second color laser light is reduced. Projection-type image display device.

2. The light source emits laser light of a third color different from the first and second colors. The illumination optical system generates the illumination light by combining the first color laser light, the second color laser light, and the third color laser light. The projection-type image display device according to claim 1.

3. The projection optical system is a projection lens unit that can be attached to and detached from the main body of the projection-type image display device. The projection lens unit includes the second aperture, If the second aperture is not controlled externally, the second aperture enters a first state where it is set to the first aperture diameter. When the projection lens unit is mounted on a predetermined projector, the second aperture enters a second state where it is set to a second aperture diameter. The second aperture is configured such that the first aperture diameter in the first state is always larger than the second aperture diameter in the second state. The projection-type image display device according to claim 1.

4. The second aperture is configured to move from the second state to a third state in which it is set to a third aperture diameter smaller than the second aperture diameter. The third opening diameter is set to any size smaller than the second opening diameter by control from the main body. The projection-type image display device according to claim 3.

5. With the projection lens unit mounted on the projection-type image display device, the aperture diameter of the second diaphragm is set by mechanical or electrical control from the main body of the projection-type image display device. The projection-type image display device according to claim 4.

6. The first aperture is, It has multiple movable wings, The aforementioned movable multiple blades primarily diffusely reflect more than 70% of the light incident on them. The projection-type image display device according to claim 1.

7. The second aperture is, It has multiple movable wings, The aforementioned movable multiple blades absorb more than 90% of the visible light incident on them. The projection-type image display device according to claim 1.

8. The second color is green, The third color is red. The projection-type image display device according to claim 2.

9. The relay optical system further comprises a lens that focuses the illumination light to the first position. The projection-type image display device according to claim 1.

10. The aperture diameter of the second aperture is greater than or equal to the aperture diameter of the first aperture. The projection-type image display device according to claim 1.

11. The F-number of the relay optical system is equal to or greater than the F-number of the projection optical system. The projection-type image display device according to claim 1.

12. The light source unit has an optical system in which the magnification for changing the height of the light source image of the first color laser light and the magnification for changing the height of the light source image of the second color laser light are different. The projection-type image display device according to claim 1.

13. The first aperture comprises a plurality of movable blades, The surfaces of the aforementioned movable multiple vanes on the side into which the illumination light is incident are diffuse reflective surfaces formed by a matte finish or a surface treatment with irregularities. The aforementioned movable multiple blades are made of a thermally conductive metal material. The projection-type image display device according to claim 1.

Images