Light modulation unit and projection-type image display device

Abstract

To provide a light modulation unit and a projection type image display device, which reduce thermal deformation caused by a temperature rise of a color prism.SOLUTION: A light modulation unit comprises a color prism and a heat absorbing member. The color prism includes a first prism on which first modulated light modulated by a first modulation element is incident and a second prism on which second modulated light modulated by a second modulation element is incident. The first prism has a first surface facing the second prism. The second prism has a second surface facing the first surface of the first prism. The color prism has a first facing region and a second facing region which the first surface of the first prism and the second surface of the second prism face respectively. The distance between the first surface and the second surface in the first facing region is smaller than the distance between the first surface and the second surface in the second facing region. The second modulated light passes through the first facing region, and the heat absorbing member is arranged in the second facing region outside the first facing region.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a light modulation unit and a projection-type image display device including the same. [Background technology]

[0002] 2. Description of the Related Art Hitherto, many three-panel projection image display devices have been developed that display images by separating and synthesizing the three primary colors of R (red), G (green), and B (blue).

[0003] A three-panel projection image display device separates white illumination light into the three primary colors of R / G / B using a dichroic filter installed inside a color prism, and directs the light to a light modulation element for each R / G / B color installed in each prism, passing through or passing through and reflecting from different block-shaped prisms inside the color prism.The light modulation element then selects the direction of reflection, separating the light beam to be projected from the unwanted light beam, and the light beam to be projected passes through the prism again, where the dichroic filter combines the light beams to be projected for each color of R / G / B.The combined projection light beam passes through the projection optical system and forms an image on a screen.

[0004] Projection-type image display devices are being developed to achieve even higher brightness in order to improve visibility during the day and to project onto larger screens. To increase the light output from the projection optical system, the intensity of the light incident on the color prism from the illumination light is increased. In this process, the color prism is configured such that light beams repeatedly transmit and reflect within each prism, resulting in some light energy being absorbed and generating heat through internal absorption by the optical components that make up the color prism. This causes birefringence due to changes in internal stress within the color prism, which is known to degrade the quality of the projected image, such as reducing contrast, in projection-type image display devices that use liquid crystal elements.

[0005] Therefore, particularly in ultra-high brightness projection image display devices, digital micromirror devices (hereinafter referred to as "DMDs") are often used as light modulation elements, due to their low degradation under high light intensity and low birefringence. While this dramatically improves brightness, the high brightness also significantly increases the energy density per unit volume within the color prism, resulting in significant changes in internal stress due to heat generation. During use of the projection image display device, deformation due to thermal expansion of the prism occurs, which has an even greater impact than birefringence. This deformation causes the light path within the prism to deviate from the desired optical path, resulting in a phenomenon known as "convergence shift" (hereinafter referred to as "convergence shift"), whereby the light beams emitted from the projection optical system to the screen, which should be focused on a single point on the screen, are shifted in position for each of the R, G, and B colors, significantly reducing the quality of the projected image.

[0006] Patent Document 1 discloses a projection type image display device in which a heat sink is attached to the side of a prism with a thermally conductive sheet sandwiched therebetween, thereby reducing thermal deformation of the prism due to increased brightness and improving image quality. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-224417 Summary of the Invention [Problem to be solved by the invention]

[0008] In the technology described in Patent Document 1, a heat conductive sheet is attached to the sides of the prisms that do not face each other, and a heat sink is then attached on top of that. This makes it difficult to dissipate heat inside the prism, and is therefore less effective at suppressing temperature increases in the prism.

[0009] An object of the present disclosure is to provide a light modulation unit and a projection-type image display device that can reduce thermal deformation of a color prism caused by a rise in temperature and suppress convergence deviation. [Means for solving the problem]

[0010] The light modulation unit according to the present disclosure includes a first light modulation element that modulates incident first color light and outputs it as first modulated light, a second light modulation element that modulates incident second color light and outputs it as second modulated light, a third light modulation element that modulates incident third color light and outputs it as third modulated light, a color prism that separates incident illumination light into the first color light, the second color light, and the third color light and outputs them toward the corresponding first light modulation element, second light modulation element, and third light modulation element, respectively, and combines the first modulated light incident from the first light modulation element, the second modulated light incident from the second light modulation element, and the third modulated light incident from the third light modulation element, and outputs it as projection light, and a heat absorption member that absorbs heat from unnecessary light in the color prism. The color prism includes a first prism onto which the first modulated light is incident, a second prism onto which the second modulated light is incident, and a third prism onto which the third modulated light is incident. The first prism has a first surface facing the second prism, and the second prism has a second surface facing the first surface of the first prism. The color prism has a first facing region and a second facing region where the first surface of the first prism and the second surface of the second prism face each other. The distance between the first surface and the second surface in the first facing region is shorter than the distance between the first surface and the second surface in the second facing region. The illumination light into which the first color light is separated and the second modulated light pass through the first facing region. A heat absorption member is disposed in the second facing region outside the first facing region.

[0011] Moreover, the light modulation unit according to the present disclosure includes a first light modulation element that modulates incident first color light and outputs it as first modulated light, a second light modulation element that modulates incident second color light and outputs it as second modulated light, a third light modulation element that modulates incident third color light and outputs it as third modulated light, a color prism that separates incident illumination light into the first color light, the second color light, and the third color light and outputs them toward the corresponding first light modulation element, second light modulation element, and third light modulation element, respectively, and combines the first modulated light incident from the first light modulation element, the second modulated light incident from the second light modulation element, and the third modulated light incident from the third light modulation element, and outputs it as projection light, and a heat absorption member that absorbs heat from unnecessary light in the color prism. The color prism has a first prism onto which the first modulated light is incident, a second prism onto which the second modulated light is incident, a third prism onto which the third modulated light is incident, and a fourth prism having the same thickness as the heat absorption member. The first prism has a first surface facing the second prism, and the second prism has a second surface facing the first surface of the first prism. The color prism has a first facing region and a second facing region where the first surface of the first prism and the second surface of the second prism face each other, respectively. The illumination light into which the first color light is separated and the second modulated light pass through the first facing region, and the heat absorption member is disposed in the second facing region outside the first facing region, and the fourth prism is disposed in the first facing region.

[0012] A projection-type image display device according to the present disclosure includes the above-described light modulation unit, a light source section that supplies illumination light to the light modulation unit, and a projection optical system that magnifies the projection light emitted from the light modulation unit. [Effects of the Invention]

[0013] The present disclosure can provide a light modulation unit and a projection-type image display device that can reduce thermal deformation of a color prism caused by a rise in temperature and suppress convergence deviation. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing the overall configuration of a projection-type image display device according to a first embodiment. [Figure 2] FIG. 1 is a perspective view showing an overall configuration of an optical modulation unit according to a first embodiment; [Figure 3] Cross-sectional view of arrow III in Figure 2 [Figure 4] FIG. 1 is a plan view of the light modulation unit with the heat dissipation member removed from the color prism. [Figure 5] Perspective view of a color prism [Figure 6] Enlarged plan view of a color prism [Figure 7] Plan view of the light modulation unit [Figure 8] 1 is a perspective view of a heat absorbing member and a heat dissipating member of an optical modulation unit; [Figure 9] An explanatory diagram showing the optical path of illumination light within a color prism [Figure 10] An explanatory diagram showing the optical path of modulated light within a color prism [Figure 11] An explanatory diagram showing the optical path of unwanted light within a color prism [Figure 12] FIG. 10 is a perspective view showing the overall configuration of an optical modulation unit according to a second embodiment. [Figure 13] Cross-sectional view of arrow XIII in FIG. 12 [Figure 14] FIG. 10 is a perspective view showing the overall configuration of an optical modulation unit according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of well-known matters or redundant explanation of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following explanation and to facilitate understanding by those skilled in the art.

[0016] The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0017] (Embodiment 1) 1 to 11, a projection-type image display device 1 and a light modulation unit 330 according to the first embodiment will be described below. As a specific example of a projection-type image display device according to the present disclosure, a projection-type image display device having a DMD as a light modulation element will be described below.

[0018] [1-1.Configuration] Fig. 1 is a schematic diagram showing the overall configuration of a projection-type image display device 1 according to an embodiment. The projection-type image display device 1 in Fig. 1 includes an illumination optical system 10 that supplies light to a color prism 340, the color prism 340, and a projection optical system 140 that projects the combined light obtained by color combining in the color prism 340.

[0019] The illumination optical system 10 includes multiple blue semiconductor lasers (hereinafter referred to as "LDs") 201 and 202 and multiple lens groups 210 and 220. The lens group 210 is composed of a convex lens 211 and a concave lens 212, and is an afocal lens that re-collimates the light emitted from the LD 201. The lens group 220 is composed of a convex lens 221 and a concave lens 222, and is an afocal lens that re-collimates the light emitted from the LD 202. The LDs 201 and 202 emit blue light in a wavelength range from 447 nm to 462 nm and emit linearly polarized light. The LDs 201 and 202 are arranged so that the emitted light becomes P-polarized with respect to the incident surface of the dichroic mirror 206.

[0020] When the light emitted from the LD 201 passes through the convex lens 211 and the concave lens 212, it is shaped into parallel light with a desired beam width, and then passes through the diffusion plate 204 and reaches the dichroic mirror 206.

[0021] Dichroic mirror 206 has spectral reflectance characteristics that transmit and reflect blue light at wavelengths of 465 nm for P-polarized light and 442 nm for S-polarized light, where the reflectance is 50%, and reflects colored light containing green and red components at 96% or more. Since the blue light from LD 201 that enters dichroic mirror 206 is arranged to be P-polarized with respect to the incident surface of dichroic mirror 206, the light emitted from LD 201 passes through dichroic mirror 206 as is and proceeds in the direction of condenser lens group 230.

[0022] The blue light transmitted through dichroic mirror 206 is incident on condenser lens group 230. Condenser lens group 230 is made up of condenser lenses 231 and 232, and gradually condenses the light to form a condensed spot near phosphor wheel 250.

[0023] The phosphor wheel 250 is a circular substrate that is equipped with an aluminum substrate and a drive motor in the center, and can be controlled to rotate around the central axis. A reflective film is formed on the surface of the aluminum substrate, and a phosphor layer is further formed on that surface. The reflective film is a metal layer or a dielectric film that reflects visible light. The phosphor layer is formed with a Ce-activated YAG yellow phosphor that is excited by blue light and emits yellow light containing green and red wavelength components. A typical chemical structure of the crystalline matrix of this phosphor is Y3Al5O 12 The phosphor layer is formed in a circular ring shape.

[0024] The phosphor layer excited by the spot light emits yellow-range light containing green and red components. By rotating phosphor wheel 250 around its central axis, the temperature rise of the phosphor layer due to blue excitation light is suppressed, and the fluorescence conversion efficiency can be maintained stably. Light incident on the phosphor layer fluoresces and emits green and red components of light, which then exits phosphor wheel 250. The green and red components of light emitted from the phosphor layer are emitted as natural light with a random polarization state, condensed again by condenser lenses 232 and 231, converted into approximately parallel light, and then incident on dichroic mirror 206. Since dichroic mirror 206 has the property of reflecting light containing green and red components, the light reflected by dichroic mirror 206 enters condenser lens 104 and is condensed on rod integrator 105.

[0025] On the other hand, when the light emitted from LD 202 passes through convex lens 221 and concave lens 222, it is shaped into approximately parallel light with a desired beam width, then its direction is changed by mirror 203, and after passing through diffuser plate 205, it reaches dichroic mirror 206. Similarly, the blue light of LD 202 that enters dichroic mirror 206 is arranged to be P-polarized with respect to the entrance surface of dichroic mirror 206, so that the light emitted from LD 202 passes through dichroic mirror 206 as it is, enters condenser lens 104, and is collected on rod integrator 105.

[0026] In this way, the yellow-range light containing green and red components emitted from phosphor wheel 250 and the blue component light from LD 202 are combined by dichroic mirror 206 and emitted as white to rod integrator 105. These red, green, and blue component light exhibit good three primary colors, and by color combining these color lights, good white-balanced light emission characteristics can be obtained. In addition, by performing ON / OFF control with DMD 106, they can be converted into a color with desired chromaticity coordinates.

[0027] Rod integrator 105 is a solid rod made of a transparent material such as glass. Rod integrator 105 generates light with a uniform light intensity distribution by internally reflecting incident light multiple times. Note that rod integrator 105 may also be a hollow rod whose inner wall is made of a mirror surface.

[0028] Lenses 121, 122, and 123 are relay lenses that approximately image the light emitted from rod integrator 105 onto DMD 106. The light emitted from rod integrator 105 is After passing through lenses 121, 122, and 123 and being reflected by mirrors 134 and 135, the light enters a total internal reflection prism (hereinafter referred to as a "TIR prism") 130.

[0029] The TIR prism 130 is configured by two approximately triangular prisms joined together with a small gap between them. This allows the optical paths of the illumination light and the projection optical system to be branched within the TIR prism according to the light incident angle, making it possible to miniaturize the color prism 340 and increasing design flexibility. Alternatively, the TIR prism 130 may be configured with a single approximately triangular prism, which totally reflects light incident at an angle equal to or greater than the critical angle. Light entering the TIR prism 130 from the mirror 135 is totally reflected by this prism surface and enters the color prism 340 of the light modulation unit 330.

[0030] [1-2. Optical modulation unit] Next, light modulation unit 330 will be described with reference to Figures 2 and 3. Figure 2 is a perspective view showing the overall configuration of light modulation unit 330. Figure 3 is a cross-sectional view taken along the line III in Figure 2. Light modulation unit 330 includes a color prism 340 that separates the colors of incident light, DMDs 106B, 106R, and 106G as light modulation elements that modulate the separated light, and a heat absorption member 350 that absorbs heat from unnecessary light within color prism 340. In addition, light modulation unit 330 includes a heat dissipation member 353 that dissipates heat absorbed by heat absorption member 350 in order to reduce a temperature rise within color prism 340.

[0031] Color prism 340 is composed of three prisms 340B, 340R, and 340G, with blue-reflecting dichroic coating layer 185 formed on the surface of prism 340B adjacent to prism 340R, and red-reflecting dichroic coating layer 186 formed on the surface of prism 340R adjacent to prism 340G. Prism 340B is a prism having a substantially triangular prism shape, and light incident from TIR prism 130 passes through prism 340B and then reaches blue-reflecting dichroic coating layer 185.

[0032] Blue-reflecting dichroic coating layer 185 is configured to reflect a wavelength corresponding to blue light and transmit other light such as green light and red light. Blue-reflecting dichroic coating layer 185 has a characteristic that, for example, when the angle of incidence on the coated surface is 27 degrees, the wavelength at which the transmittance for green light is 50% is 505 nm.

[0033] On the other hand, the red-reflecting dichroic coating layer 186 is configured to reflect a wavelength corresponding to red light and transmit other light such as green light and blue light. For example, the red-reflecting dichroic coating layer 186 has a characteristic that the wavelength at which the transmittance for green light is 50% when the incident angle on the coated surface is 27 degrees is 596 nm.

[0034] The white light that enters through the TIR prism 130 and reaches the blue-reflecting dichroic coating layer 185 is incident on the blue-reflecting dichroic coating layer 185 provided on the prism 340B in the color prism 340, and the blue component of the light is reflected and then totally reflected on the surface of the prism 340B before being approximately imaged on the DMD 106B.

[0035] On the other hand, the green and red component light beams are incident on prism 340R after passing through blue-reflecting dichroic coating layer 185. Prism 340R is a prism having a substantially triangular prism shape, and the light beams incident from prism 340B pass through prism 340R and then reach red-reflecting dichroic coating layer 186. After the red component light beams are reflected by red-reflecting dichroic coating layer 186, the green and red component light beams are totally reflected by the surface of prism 340R by first air gap 343 provided between prism 340R and prism 340B, and then form a substantial image on DMD 106R.

[0036] The green light component that is not reflected by the red-reflecting dichroic coating layer 186 is incident on the prism 340G. The prism 340R is a substantially quadrangular prism, and after passing through the prism 340G, it forms a substantial image on the DMD 106G.

[0037] The DMDs 106B, 106R, and 106G are modulated based on various control signals such as image signals to generate image light (DMD-ON light) with different light intensities. Specifically, the DMDs 106B, 106R, and 106G each have multiple movable micromirrors. Each micromirror basically corresponds to one pixel in the projected image. The DMDs 106B, 106R, and 106G change the angle of each micromirror based on various control signals to switch whether or not to direct reflected light toward the projection optical system 140. Reflected light directed toward the projection optical system 140 is image light (DMD-ON light), and reflected light not directed toward the projection optical system 140 is unwanted light (DMD-OFF light). Hereinafter, modulated light refers to image light that is projected as an image.

[0038] The blue modulated light LB2 reflected by DMD 106B re-enters prism 340B, is totally reflected on the surface of prism 340B, and then re-enters blue-reflecting dichroic coating layer 185. The modulated light LB2 mostly reflected by blue-reflecting dichroic coating layer 185 passes through prism 340B, enters projection optical system 140, and then exits toward projection surface 400. Unwanted light that is not projected as an image (DMD-OFF light) re-enters prism 340B from DMD 106B, is totally reflected on the surface of prism 340B, and then re-enters blue-reflecting dichroic coating layer 185. The unwanted blue light mostly reflected by blue-reflecting dichroic coating layer 185 passes through prism 340B, and then exits outside of color prism 340 without entering projection optical system 140.

[0039] The red modulated light LR2 reflected by the DMD 106R re-enters the prism 340R, is totally reflected by the surface of the prism 340R, and then re-enters the red-reflecting dichroic coating layer 186. The modulated light LR2 mostly reflected by the red-reflecting dichroic coating layer 186 passes through the prism 340R, passes through the first opposing region 345, and re-enters the blue-reflecting dichroic coating layer 185 provided on the prism 340B. The modulated light LR2 mostly transmitted by the blue-reflecting dichroic coating layer 185 passes through the prism 340B, enters the projection optical system 140, and then exits toward the projection surface 400. Unwanted light (DMD-OFF light) that is not projected as an image re-enters the prism 340R from the DMD 106R, is totally reflected by the surface of the prism 340R, and then re-enters the red-reflecting dichroic coating layer 186. The unwanted red light that is mostly reflected by the red-reflecting dichroic coating layer 186 passes through the prism 340R, and then enters the heat absorbing member 350 disposed in the second facing region 347 without entering the projection optical system 140.

[0040] The green modulated light LG2 reflected by DMD 106G re-enters prism 340G and then re-enters red-reflecting dichroic coating layer 186. The modulated light LG2 that is mostly transmitted by red-reflecting dichroic coating layer 186 passes through prism 340R, then passes through first opposing region 345 and re-enters blue-reflecting dichroic coating layer 185 provided on prism 340B. The modulated light LG2 that is mostly transmitted by blue-reflecting dichroic coating layer 185 passes through prism 340B, then enters projection optical system 140, and is then emitted to projection surface 400. Unwanted light that is not projected as an image (DMD-OFF light) re-enters prism 340G from DMD 106G and then re-enters red-reflecting dichroic coating layer 186. The unwanted green light LG3 that is mostly transmitted by the red-reflecting dichroic coating layer 186 passes through the prism 340R, and then does not enter the projection optical system 140 but enters the heat absorption member 350 arranged in the second facing region 347. The modulated light LB2, LR2, and LG2 are combined when they exit the prism 340B and enter the projection optical system 140.

[0041] Projection optical system 140 includes multiple projection lenses and magnifies the color-combined image light emitted from color prism 340. In this way, the projection light reflected by DMDs 106B, 106R, and 106G is color-combined again within color prism 340 into blue, green, and red light, and then reaches projection surface 400 through projection optical system 140 and is perceived as a full-color image. The images to be displayed include both still images and moving images.

[0042] [1-3. Color Prism] Next, the configuration of color prism 340 will be described in detail with reference to Fig. 2 to Fig. 6. Fig. 4 is a plan view of light modulation unit 330 with heat dissipation member 353 removed from color prism 340. Fig. 5 is a perspective view of color prism 340. Fig. 6 is a partially enlarged plan view of color prism 340. In the following description, the positive direction in the Y-axis direction in each figure will be referred to as the upward direction, and the negative direction in the Y-axis direction will be referred to as the downward direction.

[0043] As shown in FIGS. 2 to 6, the color prism 340 is composed of three block-shaped prisms 340B, 340R, and 340G. Prism 340B has prism surface 340Ba facing TIR prism 130, prism surface 340Bb facing DMD 106B, and prism surface 340Bc facing prism 340R. In prism 340B, a blue-reflecting dichroic coating layer 185 is formed on prism surface 340Bc adjacent to prism 340R, and prism surface 340Bc reflects light emitted from DMD 106B. Prism 340B has a substantially triangular prism shape and has a recess 340Bd formed by cutting out a portion of prism 340B. Recess 340Bd has, for example, a substantially rectangular parallelepiped shape.

[0044] Prism 340R has a triangular prism shape and includes prism surface 340Ra facing prism 340B, prism surface 340Rb facing DMD 106R, and prism surface 340Rc facing prism 340G. In prism 340R, red-reflecting dichroic coating layer 186 is formed on prism surface 340Rc that is close to prism 340G. In addition, a first air gap 343 and a second air gap 344 exist between prism 340B and prism 340R.

[0045] Prism 340G has a rectangular prism shape and has prism surface 340Ga facing prism 340R and prism surface 340Gb facing DMD 106G.

[0046] Color prism 340 has a first facing region 345 and a second facing region 347 where prism surface 340Bc of prism 340B and prism surface 340Ra of prism 340R face each other. A first air gap 343 exists in first facing region 345, and first air gap 343 and recess 340Bd exist in second facing region 34. Second facing region 347 is a region located outside first facing region 345.

[0047] A distance D1 between the prism surface 340Bc of the prism 340B and the prism surface 340Ra of the prism 340R in the first facing region 345 is smaller than a distance D2 between the prism surface 340Bc of the prism 340B and the prism surface 340Ra of the prism 340R in the second facing region 347.

[0048] The first facing region 345 is a region where the blue light separated from the illumination light L1 passes from the prism 340B to the prism 340R, and where the modulated lights LR2 and LG2 pass from the prism 340R to the prism 340B. Therefore, the optical axis of the blue light separated from the illumination light L1 passes through the first facing region 345, and the optical axes of the modulated lights LR2 and LG2 projected as an image pass through the first facing region 345.

[0049] A heat-absorbing member 350 is disposed in the second facing region 347. This allows the heat-absorbing member to be inserted to a position where it does not interfere with the progression of light incident on or emitted from each DMD. The heat-absorbing member 350 is disposed in contact with the prism surface 340Ra of the prism 340R. This allows the heat inside the prism 340R, which is the most likely of the three prisms to accumulate heat, to be conducted to the heat-absorbing member 350, thereby actively cooling the total reflection surface (prism surface 340Ra) of the prism 340R, which has been difficult to cool. As a result, fluctuations in the angle of total reflection of the modulated red light LR2 due to thermal deformation can be reduced, thereby suppressing convergence deviation.

[0050] The heat absorbing member 350 is made of, for example, metal or carbon. Examples of metal materials include copper and aluminum. The heat absorbing member 350 has, for example, a thin rectangular parallelepiped shape, and is fitted into the recess 340Bd of the prism 340B.

[0051] A second air gap 344 is formed between the heat absorption member 350 and the prism surface 340Bc of the prism 340B. Because the heat absorption member 350 is not in direct contact with the prism 340B, heating of the prism 340B by the heat absorption member 350 can be reduced.

[0052] 2, a heat dissipation member 353 is disposed on the side surface (upper surface) of each of the prisms 340B, 340R, and 340G. The heat dissipation member 353 includes a heat dissipation plate 355 and a heat sink 357.

[0053] Heat sink 355 is attached to the side surface (top surface) of each of prisms 340B, 340R, and 340G. See also FIGS. 7 and 8. FIG. 7 is a plan view of light modulation unit 330, and FIG. 8 is a perspective view of heat absorption member 350 and heat sink 353 of light modulation unit 330. Heat sink 355 is, for example, a metal plate or metal sheet. Heat sink 355 is directly connected to heat absorption member 350, but may also be thermally connected via another member.

[0054] The heat sink 357 is directly connected to the heat dissipation plate 355, and dissipates heat conducted from the heat absorption member 350 into the atmosphere via the heat dissipation plate 355. The heat sink 357 has, for example, multiple fins, and dissipates heat into the atmosphere between the fins. This allows the heat absorption member 350 and the color prism 340 to be cooled.

[0055] Next, the relationship between the first facing region 345, the second facing region 347, and the optical path of light passing through them will be described with reference to FIGS.

[0056] 9 shows the optical path of illumination light L1 that is incident on TIR prism 130, which is disposed in front of color prism 340, and propagates to DMD 106G. Illumination light L1 is totally reflected by TIR prism 130 and enters prism 340B, where blue light LB is separated from illumination light L1 and enters DMD 106B. Illumination light L1 from which blue light LB is separated passes through first opposing region 345 from prism surface 340Bc of prism 340B to prism surface 340Ra of prism 340R.

[0057] The illumination light L1 incident on the prism 340R is separated into red light LR and green light Lg, which propagate toward the DMD 106R and DMD 106G, respectively.

[0058] 10 , modulated light LG2 modulated by DMD 106G enters prism 340G and then further enters prism 340R. Within prism 340R, modulated light LG2 is combined with modulated light LR2 modulated by DMD 106R, and this combined light passes from prism surface 340Ra of prism 340R to prism surface 340Bc of prism 340B in first opposing region 345. The combined light of modulated light LG2 and modulated light LR2 that entered prism 340B is further combined with modulated light LB2 modulated by DMD 106B within prism 340B, and is emitted from prism 340B toward projection optical system 140 as image light L2.

[0059] 11, light reflected as unwanted light by each DMD propagates toward second facing region 347 without passing through first facing region 345. For example, unwanted light LG3 reflected by DMD 106G enters prism 340G, then further enters prism 340R, and then enters heat absorption member 350 arranged in second facing region 347. A portion of unwanted light LG3 that enters heat absorption member 350 is absorbed by heat absorption member 350, and the remainder is reflected and emitted to the outside of color prism 340. Note that a very small portion of unwanted light LG3 does not enter heat absorption member 350, but enters prism 340B and is emitted to the outside of color prism 340.

[0060] In this way, the heat absorbing member 350 is not disposed in the first facing region 345, but is disposed in the second facing region 347 through which unwanted light passes, and therefore does not affect the projection of the image light L2.

[0061] [1-4. Effects, etc.] As described above, in the present embodiment, light modulation unit 330 includes DMD 106B that modulates incident blue light and outputs the first modulated light, DMD 106R that modulates incident red light and outputs the second modulated light, DMD 106G that modulates incident green light and outputs the third modulated light, color prism 340, and a heat absorption member that absorbs heat from unnecessary light within color prism 340. Color prism 340 separates incident illumination light into blue light, red light, and green light and outputs the light toward the corresponding DMDs 106B, 106R, and 106G, respectively, and combines the first modulated light incident from DMD 106B, the second modulated light incident from DMD 106R, and the third modulated light incident from DMD 106G to output the combined light as projection light. Color prism 340 has prism 340B onto which the first modulated light is incident, prism 340R onto which the second modulated light is incident, and prism 340G onto which the third modulated light is incident. Prism 340B has prism surface 340Bc facing prism 340R, and prism 340R has prism surface 340Ra facing prism surface 340Bc of prism 340B. Color prism 340 has first facing region 345 and second facing region 347 where prism surface 340Bc of prism 340B faces prism surface 340Ra of prism 340R, respectively. Distance D1 between prism surface 340Bc and prism surface 340Ra in first facing region 345 is smaller than distance D2 between prism surface 340Bc and prism surface 340Ra in second facing region 347. The illumination light from which the blue light has been separated and the second modulated light are transmitted through the first facing region 345 , and the heat absorbing member 350 is disposed in the second facing region 347 outside the first facing region 345 .

[0062] In prism 340B and prism 340R facing prism 340B, heat absorption member 350 is arranged in second facing region 347 outside first facing region 345 through which illumination light L1, from which blue color light has been separated, and modulated light LR2 pass, so that heat inside prism 340R can be absorbed. This reduces thermal deformation that accompanies a rise in temperature of color prism 340, and suppresses convergence deviation due to thermal deformation of prism 340R.

[0063] (Embodiment 2) The light modulation unit 330A according to the second embodiment will be described with reference to Fig. 12 and Fig. 13. Fig. 12 is a perspective view showing the overall configuration of the light modulation unit 330A according to the second embodiment. Fig. 13 is a cross-sectional view taken along the arrow XIII in Fig. 12.

[0064] In the light modulation unit 330 of the first embodiment, the first air gap 343 is arranged in the first facing region 345. In the light modulation unit 330A of the second embodiment, the prism 340K is arranged in the first facing region 345. Except for this point and points described below, the light modulation unit 330 of the first embodiment and the light modulation unit 330A of the second embodiment have a common configuration, and description thereof will be omitted.

[0065] Prism 340K, which has approximately the same thickness as heat absorption member 350, is disposed below the heat absorption member (in the negative Y-axis direction) between prism surface 340Ra of prism 340R and prism surface 340Bc of prism 340B. Prism 340K has the same refractive index as prism 340R. This eliminates the need to form a recess in prism surface 340Bc of prism 340B, thereby reducing the effort required to process prism 340B.

[0066] As described above, in the present embodiment, in light modulation unit 330A, color prism 340A has prism 340B, prism 340R, prism 340G, and prism 340K having the same thickness as heat absorption member 350. Prism 340K is arranged in first facing region 345.

[0067] The configuration of Embodiment 2 can also achieve the same effects as those of Embodiment 1. Furthermore, in Embodiment 2, prism 340K is in contact with prism 340R and first air gap 343 is provided between prism 340K and prism surface 340Bc of prism 340B, but prism 340K may be in contact with prism 340B and provided between prism 340K and prism surface 340Ra of prism 340R. In this case, it is desirable that prism 340K have the same refractive index as prism 340B.

[0068] (Other embodiments) As described above, the above-described embodiments have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. Furthermore, it is also possible to combine the components described in the above-described embodiments to create new embodiments.

[0069] In each of the above-described embodiments, prisms 340B, 340R, and 340G in color prism 340 are configured in this order to separate blue, red, and green colored light, respectively, but the order in which the colored light is separated is not limited thereto. For example, the order in which the colored light is separated may be green, red, and blue. In this case, prism 340B separates green colored light from illumination light L1.

[0070] In each of the above-described embodiments, heat dissipation member 353 has heat sink 357, but is not limited to this. As shown in Fig. 14, heat dissipation member 353 may be heat dissipation plate 355 and heat receiving component 358 of a liquid cooling system that cools heat dissipation plate 355. Fig. 14 is a perspective view showing the overall configuration of light modulation unit 330B according to a modified example.

[0071] The heat receiving component 358 has an inlet 358a through which cooling water flows in, and an outlet 358b through which cooling water whose temperature has increased by absorbing heat from the heat receiving component 358 is discharged. Because the cooling water flows through the heat receiving component 358, the heat in the prism 340R that is conducted to the heat receiving component 358 via the heat absorption member 350 can be efficiently dissipated.

[0072] In the above-described first embodiment, the first facing region 345, the second facing region 347, and the heat absorbing member 350 are provided between the prism 340B and the prism 340R, but this is not limiting. The first facing region 345, the second facing region 347, and the heat absorbing member 350 may be provided between the prism 340R and the prism 340G to promote heat dissipation from the prism 340G. Similarly, in the second embodiment, the heat absorbing member 350 and the prism 340K may be provided between the prism 340R and the prism 340G.

[0073] In the first embodiment described above, recess 340Bd is formed on prism surface 340Bc of prism 340B, but this is not limited to this. The recess into which heat absorption member 350 is fitted may be formed on prism surface Ra of prism 340R, or may be formed on both prism surface 340Bc of prism 340B and prism surface Ra of prism 340R. In this way, recesses may be provided on only one prism surface of the opposing prisms, or on both prism surfaces.

[0074] In the first embodiment described above, heat-absorbing member 350 has a length that is approximately half the longitudinal length of prism 340R, but this is not limited to this. Heat-absorbing member 350 may be provided with holes through which illumination light L1 incident on DMDs 106R and 106G and modulated light from DMDs 106R and 106G pass, and may be in contact with the entire surface of prism surface 340Ra of prism 340R. In this case, the portion of the heat-absorbing member with the holes becomes the first facing region, and the area outside the holes becomes the second facing region.

[0075] As described above, the embodiments have been described as examples of the technology of the present disclosure. For this purpose, the accompanying drawings and detailed description have been provided. Therefore, the components described in the accompanying drawings and detailed description may include not only components essential for solving the problem, but also components that are not essential for solving the problem in order to exemplify the technology. Therefore, the fact that these non-essential components are described in the accompanying drawings or detailed description should not be interpreted as immediately indicating that these non-essential components are essential.

[0076] Furthermore, since the above-described embodiments are intended to illustrate the technology of the present disclosure, various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents.

[0077] (Outline of the embodiment) (1) The light modulation unit of the present disclosure includes a first light modulation element that modulates incident first color light and outputs it as first modulated light, a second light modulation element that modulates incident second color light and outputs it as second modulated light, a third light modulation element that modulates incident third color light and outputs it as third modulated light, a color prism that separates incident illumination light into the first color light, the second color light, and the third color light and outputs them toward the corresponding first light modulation element, second light modulation element, and third light modulation element, respectively, and combines the first modulated light incident from the first light modulation element, the second modulated light incident from the second light modulation element, and the third modulated light incident from the third light modulation element, and outputs it as projection light, and a heat absorption member that absorbs heat from unnecessary light in the color prism. The color prism includes a first prism onto which the first modulated light is incident, a second prism onto which the second modulated light is incident, and a third prism onto which the third modulated light is incident. The first prism has a first surface facing the second prism, and the second prism has a second surface facing the first surface of the first prism. The color prism has a first facing region and a second facing region where the first surface of the first prism and the second surface of the second prism face each other. The distance between the first surface and the second surface in the first facing region is shorter than the distance between the first surface and the second surface in the second facing region. The illumination light from which the first color light is separated and the second modulated light pass through the first facing region, and a heat absorption member is disposed in the second facing region outside the first facing region.

[0078] In the first prism and the second prism facing the first prism, a heat absorption member is arranged in the second facing region outside the first facing region through which the illumination light from which the first color light is separated and the second modulated light pass, so that heat inside the second prism can be absorbed. This reduces thermal deformation due to temperature rise of the color prism and suppresses convergence deviation due to thermal deformation of the second prism.

[0079] (2) In the optical modulation unit of (1), in the second opposing region, a recess is provided on either the first surface side of the first prism or the second surface side of the second prism, and the heat absorption member is fitted into the recess and arranged in contact with the second surface of the second prism.

[0080] (3) In the optical modulation unit of (1), a recess is provided on each of the first surface side of the first prism and the second surface side of the second prism, and the heat absorption member is fitted into each recess and arranged in contact with the second surface of the second prism.

[0081] (4) The light modulation unit of the present disclosure includes a first light modulation element that modulates incident first color light and outputs it as first modulated light, a second light modulation element that modulates incident second color light and outputs it as second modulated light, a third light modulation element that modulates incident third color light and outputs it as third modulated light, a color prism that separates incident illumination light into the first color light, the second color light, and the third color light and outputs them toward the corresponding first light modulation element, second light modulation element, and third light modulation element, respectively, and combines the first modulated light incident from the first light modulation element, the second modulated light incident from the second light modulation element, and the third modulated light incident from the third light modulation element, and outputs it as projection light, and a heat absorption member that absorbs heat from unnecessary light in the color prism. The color prism has a first prism onto which the first modulated light is incident, a second prism onto which the second modulated light is incident, a third prism onto which the third modulated light is incident, and a fourth prism having the same thickness as the heat absorption member. The first prism has a first surface facing the second prism, and the second prism has a second surface facing the first surface of the first prism. The color prism has a first facing region and a second facing region where the first surface of the first prism and the second surface of the second prism face each other. The illumination light into which the first color light is separated, the second modulated light, and the third modulated light pass through the first facing region. The heat absorption member is disposed in the second facing region outside the first facing region, and the fourth prism is disposed in the first facing region.

[0082] In the first prism and the second prism facing the first prism, a heat absorption member is arranged in the second facing region outside the first facing region through which the illumination light from which the first color light is separated and the second modulated light pass, so that heat inside the second prism can be absorbed. This reduces thermal deformation due to temperature rise of the color prism and suppresses convergence deviation due to thermal deformation of the second prism.

[0083] (5) The optical modulation unit according to any one of (1) to (4) further comprises a heat dissipation member to which heat from the heat absorption member is conducted.

[0084] (6) In the optical modulation unit of (5), the heat dissipation member includes a heat sink that dissipates heat conducted from the heat absorption member.

[0085] (7) In the optical modulation unit of (5), the heat dissipation member includes a heat-receiving component of a liquid cooling system through which cooling water flows in and out.

[0086] (8) The projection-type image display device of the present disclosure includes a light modulation unit according to any one of (1) to (7), a light source unit that supplies illumination light to the light modulation unit, and a projection optical system that magnifies the projection light emitted from the light modulation unit.

[0087] This makes it possible to provide a projection-type image display device that can reduce thermal deformation of the color prism due to a rise in temperature, and suppress convergence deviation due to thermal deformation of the second prism. [Industrial Applicability]

[0088] The present disclosure can be used in a light modulation unit and a projection-type image display device that include a color prism. [Explanation of symbols]

[0089] 1 Projection-type image display device 10 Illumination optical system 104 Condenser Lens 105 Rod Integrator 106, 106B, 106G, 106R DMD 120, 121, 122, 123 Relay lenses 130 TIR prism, 134, 135, 203 Mirror 140 Projection Optical System 185, 186 Dichroic coating layer 201, 202 Blue semiconductor laser 204, 205 Diffusers, 206 Dichroic Mirror 210, 220 Afocal lens group 211, 221 Convex lenses 212, 222 concave lenses 230 Condenser Lens Group 231, 232 Condenser lenses 250 Phosphor Wheel 330 Optical Modulation Unit 340, 340A Color Prism 340B, 340G, 340R, 340K Prism 340Ba, 340Bb, 340Bc, 340Ga, 340Gb, 340Ra, 340Rb, 340Rc prism surface 340Bd recess 343 First Air Gap 344 Second Air Gap 345 1st opposing area 347 Second opposing area 350 Heat absorption member 353 Heat dissipation materials 355 Heat sink 357 Heatsink 400 projection plane L1 illumination light L2 Image Light LB, LG, LR color light LB2, LR2, LG2 modulated light L3, LG3 unnecessary light

Claims

1. a first light modulation element that modulates incident first color light and outputs the modulated light as first modulated light; a second light modulation element that modulates the incident second color light and outputs the modulated light as second modulated light; a third light modulation element that modulates the incident third color light and outputs the modulated third color light; a color prism that separates incident illumination light into the first color light, the second color light, and the third color light, and emits the light toward the corresponding first light modulation element, the second light modulation element, and the third light modulation element, respectively, and combines the first modulated light incident from the first light modulation element, the second modulated light incident from the second light modulation element, and the third modulated light incident from the third light modulation element, and emits the combined light as projection light; a heat absorbing member that absorbs heat from unnecessary light within the color prism, the color prism includes a first prism onto which the first modulated light is incident, a second prism onto which the second modulated light is incident, and a third prism onto which the third modulated light is incident, the first prism has a first surface facing the second prism; the second prism has a second surface facing the first surface of the first prism, the color prism has a first opposing region and a second opposing region in which a first surface of the first prism and a second surface of the second prism face each other, a distance between the first surface and the second surface in the first opposing region is smaller than a distance between the first surface and the second surface in the second opposing region; the illumination light from which the first color light has been separated and the second modulated light are transmitted through the first opposing region; The heat absorbing member is disposed in the second opposing region outside the first opposing region. Light modulation unit.

2. a recessed portion is provided on either the first surface side of the first prism or the second surface side of the second prism in the second opposing region, the heat absorption member is fitted into the recess and is disposed in contact with the second surface of the second prism. The light modulation unit according to claim 1 .

3. a recessed portion is provided on each of a first surface side of the first prism and a second surface side of the second prism; the heat absorbing members are fitted into the respective recesses and are arranged in contact with the second surface of the second prism; The light modulation unit according to claim 1 .

4. a first light modulation element that modulates incident first color light and outputs the modulated light as first modulated light; a second light modulation element that modulates the incident second color light and outputs the modulated light as second modulated light; a third light modulation element that modulates the incident third color light and outputs the modulated third color light; a color prism that separates incident illumination light into the first color light, the second color light, and the third color light, and emits the light toward the corresponding first light modulation element, the second light modulation element, and the third light modulation element, respectively, and combines the first modulated light incident from the first light modulation element, the second modulated light incident from the second light modulation element, and the third modulated light incident from the third light modulation element, and emits the combined light as projection light; a heat absorbing member that absorbs heat from unnecessary light within the color prism, the color prism includes a first prism onto which the first modulated light is incident, a second prism onto which the second modulated light is incident, a third prism onto which the third modulated light is incident, and a fourth prism having the same thickness as the heat absorption member; the first prism has a first surface facing the second prism; the second prism has a second surface facing the first surface of the first prism, the color prism has a first opposing region and a second opposing region in which a first surface of the first prism and a second surface of the second prism face each other, the illumination light from which the first color light has been separated and the second modulated light are transmitted through the first opposing region; the heat absorbing member is disposed in the second opposing region outside the first opposing region, and the fourth prism is disposed in the first opposing region; Light modulation unit.

5. a heat dissipation member to which heat from the heat absorption member is conducted; 5. The light modulation unit according to claim 1.

6. The heat dissipation member includes a heat sink that dissipates heat conducted from the heat absorption member. The light modulation unit according to claim 5 .

7. The heat dissipation member includes a heat-receiving component of a liquid cooling system through which cooling water flows in and out. The light modulation unit according to claim 5 .

8. The light modulation unit according to claim 1 or 4; a light source unit that supplies illumination light to the light modulation unit; a projection optical system that expands the projection light emitted from the light modulation unit, Projection-type image display device.

Images