JP7787371B2 - Light modulation unit and projection-type image display device - Google Patents

Description

The present invention relates to an optical modulation unit and a projection-type image display device.

Conventionally, there are projection-type image display devices that project image light obtained by optically modulating illumination light. An optical modulation element modulates illumination light into image light (ON light) or unwanted light (OFF light). The image light is projected onto a screen by a projection lens unit, and the unwanted light is absorbed by a light shielding plate.

Some such projection-type image display devices are equipped with an imaging device that captures light incident from the projection target through the projection lens unit. For example, in Patent Document 1, an imaging unit is positioned in the direction of reflection of light incident from the projection optical system onto the reflective surface of the TIR prism.

JP 2013-218262 A

However, if the brightness of the illumination light is increased to make the image light brighter, the temperature of the light shielding plate that absorbs unnecessary light rises, and this heat can affect the imaging unit, causing problems with the imaging light, such as causing the image to become out of focus.

The present disclosure aims to provide an optical modulation unit and a projection-type image display device that reduce heat conduction to the imaging section.

The light modulation unit according to the first aspect of the present disclosure includes a light modulation element that modulates incident illumination light into image light or unwanted light, a prism that is disposed opposite the light modulation element and guides the illumination light to the light modulation element, a light blocking plate that blocks the unwanted light emitted from the light modulation element, a frame that houses the prism, an imaging unit that captures the imaging light that has entered through the prism, and a fixing unit that fixes the light blocking plate to the frame. The imaging unit is attached to the frame on the opposite side of the fixing unit from the prism.

A light modulation unit according to a second aspect of the present disclosure includes a light modulation element that modulates incident illumination light into image light or unwanted light, a prism that is arranged opposite the light modulation element and guides the illumination light to the light modulation element, a light blocking plate that blocks the unwanted light emitted from the light modulation element, a frame that houses the prism, an imaging unit that captures the imaging light incident through the prism, and a fixing portion that fixes the light blocking plate to the frame. The frame has a first frame portion and a second frame portion, the fixing portion is arranged in the first frame portion, the imaging unit is fixed to the second frame portion, and a gap is formed between the first frame portion and the second frame portion.

The projection-type image display device of the present disclosure comprises the above-mentioned light modulation unit and a projection lens unit fixed to a frame.

This disclosure can provide an optical modulation unit and a projection-type image display device that reduce heat conduction to the imaging section.

FIG. 1 is a diagram showing a configuration of a projection-type image display device according to a first embodiment; 1 is a perspective view of the appearance of a light modulation unit and a projection lens unit; 1 is a perspective view of the appearance of a light modulation unit and a projection lens unit; 1 is a perspective view of the appearance of a light modulation unit and a projection lens unit; Front view of the light modulation unit and the projection lens unit Front view of the light modulation unit with the projection lens unit removed Perspective view of the frame 1 is a perspective view of a light-shielding plate and a first heat dissipation unit; A perspective view showing the positional relationship between the light blocking plate, the prism, the imaging unit, and the light modulation element. Perspective view of the imaging unit Perspective view of a prism A diagram showing the optical paths of image light and unwanted light. Diagram showing the optical path of imaging light FIG. 10 is a front view of the light modulation unit according to the modification of the first embodiment. 10 is a front view of the light modulation unit according to the second embodiment.

The following describes the embodiments in detail, with reference to the drawings as appropriate. However, more detailed explanations than necessary may be omitted. For example, detailed explanations of matters that are already well known or duplicate explanations of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following explanation and to make it easier for those skilled in the art to understand.

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.

(Embodiment 1)
[1-1. Configuration of projection-type image display device]
A projection-type image display device 1 according to embodiment 1 will be described with reference to Fig. 1. Fig. 1 is a diagram showing the configuration of the projection-type image display device 1 according to embodiment 1. The projection-type image display device 1 according to embodiment 1 is, for example, a so-called one-chip DMD projector that uses one DMD (Digital Micromirror Device).

The projection-type image display device 1 of embodiment 1 comprises a light source device 3, a relay optical system 4, a light modulation unit 5, a projection lens unit 6, and a control unit 7.

The light source device 3 comprises a laser light source 11, a phosphor wheel 12, and a color wheel unit 20. Laser light in the blue wavelength range emitted from the multiple laser light sources 11 is collimated by multiple collimator lenses (not shown) provided corresponding to each laser light source 11. The collimated blue light enters the subsequent convex lens 13, where its beam width is reduced, and then enters the subsequent diffuser plate 14 where it is diffused and the uniformity of the light is improved. The blue light with its uniformity improved enters the subsequent concave lens 15 and is converted into a parallel beam.

The blue light collimated by the concave lens 15 enters the selective reflection element 16, which is tilted approximately 45 degrees relative to the optical axis, and then travels straight ahead to enter the convex lens 17. The selective reflection element 16 has spectral characteristics that allow light in the wavelength range of blue light emitted from the laser light source 11 to pass through, and reflect light in the wavelength range of fluorescence that is wavelength-converted by the phosphor wheel 12 using the blue light from the laser light source 11 as excitation light. The selective reflection element 16 is, for example, a dichroic mirror.

The blue light incident on the convex lens 17, in combination with the subsequent convex lens 18, enters the wavelength conversion elements or passage areas arranged in annular regions on the substrate of the subsequent phosphor wheel 12. The passage areas are through holes formed in the phosphor wheel 12. The phosphor wheel 12 is positioned around its rotation axis so that the blue excitation light focused by the convex lenses 17 and 18 enters the annular wavelength conversion elements or passage areas.

The blue light focused onto the wavelength conversion element of the phosphor wheel 12 by the convex lenses 17 and 18 is wavelength-converted into fluorescent light, and the light's direction of travel is changed by 180 degrees before it is incident again on the convex lenses 18 and 17 in that order and converted into parallel light. The fluorescent light that is wavelength-converted here is, for example, green light and yellow light.

The fluorescence that has exited the convex lens 17 and been collimated is then incident again on the selective reflection element 16. As mentioned above, the selective reflection element 16 has the property of reflecting light in the fluorescence wavelength range, so it changes the direction of the light in the fluorescence wavelength range by 90 degrees and makes it incident on the convex lens 39.

Next, the blue light from the laser light source 11, which is focused in the passing area of the phosphor wheel 12, passes through the phosphor wheel 12 and is collimated by the subsequent convex lenses 31 and 32. The light is then guided by a downstream relay lens system consisting of three reflecting mirrors 33, 35, and 37 and three convex lenses 34, 36, and 38 so that it is collimated and enters the selective reflection element 16 from a direction 90 degrees from the incident direction of the light from the laser light source 11. Note that while the relay optical system here is constructed with three mirrors and three convex lenses, other configurations may be used as long as they have similar performance.

Blue light that enters the selective reflection element 16 from the convex lens 38 passes through the selective reflection element 16 and continues straight ahead.

With the above configuration, fluorescent light and blue light are time-divided and incident on the convex lens 39.

The time-division fluorescence and blue light incident on the convex lens 39 from the selective reflection element 16 are focused by the convex lens 39 and then incident on the color wheel 22 of the downstream color wheel unit 20. The color wheel 22 is controlled by the control unit 7 to rotate synchronously with the phosphor wheel 12, and is fitted with multiple filters that transmit some or all wavelengths of the blue light and fluorescence, depending on the characteristics of the optical system.

The control unit 7 is a circuit that can be realized using semiconductor elements, etc., and can be configured, for example, with a microcomputer, CPU, MPU, GPU, DSP, FPGA, or ASIC. The control unit 7 realizes predetermined functions by reading data and programs stored in an internal memory unit (not shown) and performing various arithmetic operations. The memory unit can be realized, for example, with a hard disk drive (HDD), SSD, RAM, DRAM, ferroelectric memory, flash memory, magnetic disk, or a combination of these.

When, for example, yellow fluorescence is emitted from the phosphor wheel 12, the color wheel 22 rotates synchronously. The color wheel 22 has at least one of the following regions: a region that transmits the wavelength range of the fluorescence as is; a region that reflects the red portion of the fluorescence and transmits green light; or a region that reflects the green portion of the fluorescence and transmits red light. Furthermore, the blue light that passes through the phosphor wheel 12's transmission region corresponds to a region that transmits the wavelength range of the fluorescence as is, so that colored light of different wavelength ranges is focused in time series near the incident end of the rod integrator 23.

Light incident on the rod integrator 23 of the color wheel unit 20 is homogenized by the rod integrator 23, and the homogenized light is emitted from its exit end. In embodiment 1, the color wheel 22 is positioned in front of the rod integrator 23, but it may also be positioned after the rod integrator 23. The light exiting the rod integrator 23 is guided to the light modulation element 51 (described later) by the relay optical system 4, which is composed of convex lenses 41, 42, and 43.

The light modulation unit 5 has a prism 44, a light modulation element 51, and an imaging unit 53. Light that passes through the convex lenses 41, 42, and 43 and enters the prism 44 enters the minute gap 48 in the prism 44 at an angle greater than the total reflection angle, and is reflected, changing the direction of travel of the light before entering the light modulation element 51.

The light modulation element 51 changes the direction of light and emits it in response to a signal from the control unit 7 synchronized with the colored light emitted by the combination of the phosphor wheel 12 and the color wheel 22. The light modulation element 51 is, for example, a DMD that changes the direction of light by changing the orientation of micromirrors. The light modulation element 51 may be supported by the frame 61, or may be supported by another member so as to maintain a distance from the prism 44.

The image light, whose direction of travel has been changed in response to the image signal by the light modulation element 51, enters the prism 44 and enters the minute gap 48 of the prism 44 at an angle less than the total reflection angle, thereby passing through the projection lens unit 6 and projecting it onto a screen (not shown). Furthermore, the imaging light incident from the screen through the projection lens unit 6 travels to the prism 44 and is guided to the imaging unit 53, where it is imaged.

[1-2. Configuration of the optical modulation unit]
The light modulation unit 5 according to the first embodiment will be described below with reference to Figs. 2 to 5. Fig. 2 is an external perspective view of the light modulation unit 5 and the projection lens unit 6. Figs. 3A and 3B are external perspective views of the light modulation unit 5 and the projection lens unit 6 with the lens mounter 60 removed. Fig. 4 is a front view of the light modulation unit 5 and the projection lens unit 6. Fig. 5 is a front view of the light modulation unit 5 with the projection lens unit 6 removed. In each drawing, the direction in which image light is emitted from the projection lens unit 6 is defined as the Z-axis direction, and the plane perpendicular to the Z-axis is defined as the XY plane.

The light modulation unit 5 further includes a lens mounter 60, a frame 61, a light shielding plate 63, a first heat dissipation section 65, and a second heat dissipation section 67.

The lens mounter 60 is a member that supports the projection lens unit 6, and the projection lens unit 6 is attached to it. The lens mounter 60 has a roughly rectangular parallelepiped shape, and the projection lens unit 6 is inserted into an opening 60a provided on one side. The lens mounter 60 is attached to the flange surface 71 of the frame 61 via a first dustproof sheet 62. The lens mounter 60 and frame 61 are made of, for example, a resin material.

The light-shielding plate 63 absorbs unwanted light modulated by the light modulation element 51. The light-shielding plate 63 is attached to the frame 61 by a fixing portion 69. The light-shielding plate 63 is made of metal and has good thermal conductivity. The light-shielding plate 63 extends from the inside to the outside of the frame 61 and has a flat plate portion 63a (see Figure 7) that extends along the outer wall of the frame 61. A first heat dissipation portion 65 is attached to the flat plate portion 63a.

The first heat dissipation section 65 is a member that dissipates heat from the light shielding plate 63 and has, for example, multiple fins.

The second heat dissipation section 67 is a member that dissipates heat from the frame 61 and has, for example, multiple fins. The second heat dissipation section 67 is directly disposed on the frame 61, midway along or near the path from the fixed section 69 to the imaging section 53.

Next, reference is made to Figures 5 and 6. Figure 6 is a perspective view of the frame 61. The frame 61 houses the prism 44, and has the projection lens unit 6 and imaging unit 53 attached to it. The frame 61 has a flange surface 71 to which the lens mounter 60 is attached, and a recess 73 recessed from the flange surface 71 on the side opposite the emission direction of the image light. The recess 73 is formed by a bottom wall 75 and a side wall 77. A through hole 75a, for example, of a substantially rectangular shape, is formed in the bottom wall 75, and the prism 44 and the light modulation element 51 face each other via the through hole 75a. The image light modulated by the light modulation element 51 and unwanted light pass through the through hole 75a and the prism 44.

A protrusion 79 is disposed on the side wall 77, rising toward the space of the recess 73. The prism 44 is aligned with the protrusion 79 and glued to the bottom wall 75 for fixation. An opening 80 is provided on the longitudinal side of the prism 44, opposite the through-hole 81, to allow illumination light to enter the frame 61. The imaging unit 53 is disposed on the opposite side of the fixing portion 69 from the recess 73, which is the space that houses the prism 44. Therefore, the imaging unit 53 is attached to the frame 61 on the opposite side of the fixing portion 69 from the prism 44. Here, "opposite side" refers not only to a state in which the prism 44 is located between the fixing portion 69 and the imaging unit 53, as shown in Figure 5, but also to a state in which they are on opposite sides of the center line CL of the prism 44 in the width direction.

The fixing portion 69 fixes the light blocking plate 63 to the frame 61. The fixing portion 69 has a spacer 69a and a fixing screw, and the light blocking plate 63 is attached to the frame 61 by screwing it via the spacer 69a. By using the spacer 69a, the light blocking plate 63 is fixed to the frame 61 without coming into direct contact with the frame 61, and by limiting the path for heat transfer from the light blocking plate 63 to the frame 61 to only the spacer 69a, heat transfer from the light blocking plate 63 to the frame 61 is reduced.

(Prism width)
Furthermore, the distance from the fixed portion 69 to the imaging unit 53 is longer than the width of the prism 44. In this way, the distance from the fixed portion 69 to the imaging unit 53 is sufficient, which reduces the transfer of heat from the fixed portion 69 to the imaging unit 53. Here, the width of the prism 44 is the length in the short direction of the prism 44 in a plane perpendicular to the depth direction (Z-axis direction) of the prism 44, which is the emission direction of the image light (see FIG. 10 ).

Refer to Figure 9. Figure 9 is a perspective view of the imaging unit 53. The imaging unit 53 includes a lens 57 constituting a reduction optical system, a camera body 55 having an imaging element 55a that receives imaging light, a lens barrel 58 that holds the lens 57 therein, and a flange 59 that supports the lens barrel 58. The imaging element 55a is, for example, a solid-state imaging element such as a CCD image sensor or a CMOS image sensor. The lens 57 is, for example, a convex lens, and the reduction optical system may be composed of multiple lenses. The lens barrel 58 supports the lens 57 at one end, and the other end is connected to the camera body 55, so that the distance between the imaging element 55a and the lens 57 is maintained constant.

With the lens barrel 58 of the imaging unit 53 inserted into a through hole 81 (see Figure 6) formed in the frame 61 on the opposite side of the fixing portion 69 from the prism 44, the flange 59 is fixed to the frame 61, for example, by a screw.

Please refer to Figures 8, 10 and 11. Figure 8 is a perspective view showing the positional relationship between the light-shielding plate 63, prism 44, imaging unit 53 and light modulation element 51, Figure 10 is a perspective view of the prism, and Figure 11 is a diagram showing the optical paths of image light and unwanted light. Figure 11(a) shows the optical path of image light, and Figure 11(b) shows the optical path of unwanted light. In Figures 8, 10 and 11, the minute gap 48 of the prism 44 is omitted.

The prism 44 is a total internal reflection prism (TIR prism) and includes a first prism 46, a second prism 47, and a minute gap 48 (see Figure 1). Illumination light incident on the first surface 46a of the first prism 46 is totally reflected by the second surface 46b of the first prism 46, exits from the third surface 46c of the first prism 46, and enters the light modulation element 51.

The image light modulated by the light modulation element 51 enters the third surface 46c of the first prism 46, passes through the second surface 46b and the first surface 47a and second surface 47b of the second prism 47, and enters the projection lens unit 6.

In addition, the unwanted light modulated by the light modulation element 51 enters the third surface 46c of the first prism 46, passes through the second surface 46b and the first surface 47a and second surface 47b of the second prism 47, and enters the light shielding plate 63.

Imaging light incident from the projection target through the projection lens unit 6 is incident on the second surface 47b of the second prism 47. The imaging light entering the second prism 47 is totally reflected by the first surface 47a of the second prism 47 and travels toward the second surface 47b, is totally reflected again by the second surface 47b and travels toward the third surface 47c, is totally reflected again by the third surface 47c and travels toward the fourth surface 47d. The imaging light exiting the fourth surface 47d of the second prism 47 is incident on the lens 57 of the imaging unit 53 (see Figure 8). In this way, the imaging light can reach the imaging unit 53.

[1-3. Effects, etc.]
As described above, in the first embodiment, the light modulation unit 5 includes the light modulation element 51 that modulates incident illumination light into image light or unnecessary light, the prism 44 that is disposed opposite the light modulation element 51 and guides the illumination light to the light modulation element 51, the light blocking plate 63 that blocks the unnecessary light emitted from the light modulation element 51, the frame 61 that houses the prism 44, the imaging unit 53 that captures the imaging light that is incident via the prism 44, and the fixing part 69 that fixes the light blocking plate 63 to the frame 61. The imaging unit 53 is attached to the frame 61 on the opposite side of the fixing part 69 from the prism 44.

The imaging unit 53 is attached to the frame 61 on the opposite side of the fixing portion 69 that fixes the light-shielding plate 63 to the frame 61 relative to the prism 44, ensuring a sufficient distance between the imaging unit 53 and the fixing portion 69. As a result, even if heat from unwanted light is transferred from the light-shielding plate 63 to the fixing portion 69 of the frame 61, the distance from the fixing portion 69 to the imaging unit 53 reduces the transfer of heat to the imaging unit 53. As a result, it is possible to prevent the imaging unit 53 from being hindered in capturing imaging light due to heat.

In addition, the distance from the fixed portion 69 to the imaging unit 53 is longer than the width of the prism 44. This ensures a sufficient distance from the fixed portion 69 to the imaging unit 53, thereby reducing the transfer of heat from the fixed portion 69 to the imaging unit 53.

The fixing portion 69 also has a spacer 69a that is placed between the light blocking plate 63 and the frame 61. This allows the light blocking plate 63 and the frame 61 to be in contact with each other via the spacer 69a, preventing direct contact between the light blocking plate 63 and the frame 61 and reducing the transfer of heat from the light blocking plate 63 to the frame 61.

The imaging unit 53 also includes an imaging element 55a that receives imaging light and a lens 57 that constitutes a reduction optical system. Even when the imaging unit 53 includes a lens 57, heat is less likely to be transmitted from the fixed part 69, reducing distortion of the lens 57 due to heat.

The light-shielding plate 63 extends from the inside to the outside of the frame 61 at a location closer to the fixed portion 69 than the imaging unit 53, and has a flat plate portion 63a, which is an extending portion located outside the frame 61. Because the light-shielding plate 63 has the flat plate portion 63a located outside the frame 61, heat generated by unwanted light received inside the frame 61 can be dissipated by the flat plate portion 63a outside the frame 61. Furthermore, because the flat plate portion 63a is located closer to the fixed portion 69 than the imaging unit 53, heat is more likely to be dissipated by the flat plate portion 63a than to be conducted to the imaging unit 53. Because the flat plate portion 63a is located midway along the heat conduction path from the fixed portion 69 to the imaging unit 53 in the frame 61, heat conduction to the imaging unit 53 can be reduced.

The light shielding plate 63 also includes a first heat dissipation section 65 located on the flat plate portion 63a, which is an extension of the light shielding plate 63. By providing the first heat dissipation section 65 on the flat plate portion 63a, heat can be efficiently dissipated by the first heat dissipation section 65 from the light shielding plate 63 inside the frame 61 via the external flat plate portion 63a, thereby reducing the heat transmitted from the fixing section 69 to the frame 61.

In addition, a second heat dissipation section 67 is arranged in the frame 61. Since the second heat dissipation section 67 is arranged in the frame 61 between the fixed section 69 and the imaging section 53, heat from the fixed section 69 is dissipated by the second heat dissipation section 67, further reducing transmission of heat to the imaging section 53.

The projection-type image display device 1 also includes a projection lens unit 6 fixed to a frame 61 via a lens mounter 60. The connection between the frame 61 and the lens mounter 60 is an airtight structure. A light-shielding plate 63 extends from the inside to the outside of the frame 61, and a second dustproof sheet 72 (see Figures 2 and 3A) is disposed at the portion where the light-shielding plate 63 extends from the inside to the outside of the airtight structure. The second dustproof sheet 72 is disposed so as to fill the gap between the first dustproof sheet 62 and the light-shielding plate 63. The first dustproof sheet 62 and the second dustproof sheet 72 are made of, for example, a resin material or a fiber material. The second dustproof sheet 72 also reduces the transfer of heat from the frame 61 via the lens mounter 60 to the projection lens unit 6, thereby reducing the transfer of heat transferred to the projection lens unit 6 back to the frame 61.

Also, as shown in FIG. 13, the imaging unit 53 is fixed directly to the frame 61, but this is not limited to this. The imaging unit 53 may be fixed to the frame 61 via a heat insulating material 83. The heat insulating material 83 can further reduce the transfer of heat from the fixed portion 69 via the frame 61 to the imaging unit 53. Note that the heat insulating material 83 may be placed not only around the lens barrel 58 but also between the flange 59 and the frame 61.

(Embodiment 2)
Next, an optical modulation unit 5A according to a second embodiment will be described with reference to Fig. 14. Fig. 14 is a front view of the optical modulation unit 5A according to the second embodiment.

In embodiment 2, the frame 61 of embodiment 1 is composed of two divided bodies. Other than this and the points described below, the optical modulation unit 5 of embodiment 1 and the optical modulation unit 5A of embodiment 2 share the same configuration, so further explanation will be omitted.

The frame 61A of embodiment 2 has a first frame portion 91 and a second frame portion 93, and is configured by combining the first frame portion 91 and the second frame portion 93. A fixing portion 69 is disposed in the first frame portion 91, and the imaging unit 53 is fixed to the second frame portion 93. A gap 95 is formed between the first frame portion 91 and the second frame portion 93, and the air layer in the gap 95 functions as a heat insulating layer, reducing the transfer of heat from the first frame portion 91 to the second frame portion 93.

As such, in embodiment 2, the light modulation unit 5A includes a light modulation element 51 that modulates incident illumination light into image light or unwanted light, a prism 44 that is arranged opposite the light modulation element 51 and guides the illumination light to the light modulation element 51, a light blocking plate 63 that blocks the unwanted light emitted from the light modulation element 51, a frame 61A that houses the prism 44, an imaging unit 53 that captures the imaging light incident through the prism 44, and a fixing portion 69 that fixes the light blocking plate 63 to the frame 61A. The frame 61A has a first frame portion and a second frame portion 93, with the fixing portion 69 arranged in the first frame portion 91 and the imaging unit 53 fixed to the second frame portion 93, and a gap 95 formed between the first frame portion 91 and the second frame portion 93.

The frame 61 is composed of a first frame portion 91 and a second frame portion 93, and a gap 95 is formed between the first frame portion 91, in which the fixing portion 69 is arranged, and the second frame portion 93, in which the imaging unit 53 is fixed. This reduces the transfer of heat from the first frame portion 91 to the second frame portion 93, making it less likely that heat will be transferred from the fixing portion 69 to the imaging unit 53.

In addition, the gap 95 is groove-shaped, and the first frame portion 91 and the second frame portion 93 are not completely separate entities, but may be connected on the light modulation element 51 side.

An insulating material may also be placed in the gap 95. The insulating material can further reduce heat transfer from the first frame portion 91 to the second frame portion 93. The insulating material may be, for example, foamed plastic or a fiber material.

(Other embodiments)
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 above 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.

(1) In the above-described embodiment, the frame 61 may be provided with a fan that blows air between the fixed portion 69 and the imaging unit 53. This allows the frame 61 between the fixed portion 69 and the imaging unit 53 to be cooled, thereby reducing the transfer of heat from the fixed portion 69 to the imaging unit 53.

(2) In the above-described embodiment, the light modulation unit 5 is a one-chip system using one DMD as a light modulation element, but this is not limited to this. The light modulation unit 5 may also be a three-chip system using three light modulation elements and DMDs.

Furthermore, the above-described embodiments are intended to illustrate the technology of this disclosure, and various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents. Furthermore, it is also possible to combine the components described in the above embodiments to create new embodiments.

(Outline of the embodiment)
(1) A light modulation unit according to a first aspect of the present disclosure includes a light modulation element that modulates incident illumination light into image light or unwanted light, a prism that is disposed opposite the light modulation element and that guides the illumination light to the light modulation element, a light blocking plate that blocks the unwanted light that has been emitted from the light modulation element, a frame that houses the prism, an imaging unit that captures imaging light that has entered through the prism, and a fixing unit that fixes the light blocking plate to the frame. The imaging unit is attached to the frame on the opposite side of the fixing unit from the prism.

The imaging unit is attached to the frame on the opposite side of the prism from the fixed part that secures the light shielding plate to the frame, ensuring a sufficient distance between the imaging unit and the fixed part. This means that even if heat from unwanted light is transferred from the light shielding plate to the fixed part of the frame, the distance from the fixed part to the imaging unit reduces the transfer of heat to the imaging unit. This prevents heat from interfering with the imaging unit's ability to capture imaging light.

(2) In the light modulation unit of (1), the distance from the fixed part to the imaging part is longer than the width of the prism.

(3) In the optical modulation unit of (1) or (2), the fixed portion has a spacer that is placed between the light shielding plate and the frame.

(4) In any one of the optical modulation units (1) to (3), the imaging unit is fixed to the frame via a heat insulating material.

(5) In any one of the optical modulation units (1) to (4), the imaging section includes an imaging element that receives imaging light and a lens that constitutes a reduction optical system.

(6) In any one of the optical modulation units (1) to (5), the light shielding plate extends from the inside to the outside of the frame at a location closer to the fixed part than the imaging part, and has an extending portion located outside the frame.

(7) In the optical modulation unit of (6), a heat dissipation section is provided in the extended portion of the light shielding plate.

(8) In any one of the optical modulation units (1) to (7), a heat dissipation section is arranged in the frame between the fixed section and the imaging section.

(9) In any one of the optical modulation units (1) to (8), a fan is provided in the frame to blow air between the fixed portion and the imaging portion.

(10) A light modulation unit according to a second aspect of the present disclosure includes a light modulation element that modulates incident illumination light into image light or unwanted light, a prism that is arranged opposite the light modulation element and guides the illumination light to the light modulation element, a light blocking plate that blocks the unwanted light emitted from the light modulation element, a frame that houses the prism, an imaging unit that captures the imaging light incident through the prism, and a fixing portion that fixes the light blocking plate to the frame. The frame has a first frame portion and a second frame portion, the fixing portion is arranged in the first frame portion, the imaging unit is fixed to the second frame portion, and a gap is formed between the first frame portion and the second frame portion.

(11) In the optical modulation unit of (10), insulation material is placed in the gap.

(12) The projection-type image display device of the present disclosure comprises any one of the light modulation units (1) to (11) and a projection lens unit fixed to a frame via a lens mounter.

(13) In the projection-type image display device of (12), the connection between the frame and the lens mounter has an airtight structure, a light-shielding plate extends from the inside of the frame to the outside, and a dustproof sheet is arranged in the portion where the light-shielding plate extends from the inside of the airtight structure to the outside.

This disclosure can be used in a light modulation unit that includes a light modulation element that modulates illumination light into image light and an imaging unit that captures imaging light that is the image light reflected from a projection target, and in a projection-type image display device.

REFERENCE SIGNS LIST 1 projection type image display device 3 light source device 4 relay optical system 5, 5A light modulation unit 6 projection lens unit 7 control unit 11 laser light source 12 phosphor wheel 13, 17, 18 convex lens 14 diffuser plate 15 concave lens 16 selective reflection element 20 color wheel unit 22 color wheel 23 rod integrator 31, 32, 34, 36, 38, 39 convex lens 33, 35, 37 reflecting mirror 41, 42, 43 convex lens 44 prism 46 first prism 46a first surface 46b second surface 46c third surface 47 second prism 47a first surface 47b second surface 47c third surface 47d fourth surface 48 minute gap 51 light modulation element 53 imaging unit 55 camera body 55a Image pickup element 57 Lens 58 Lens barrel 59 Flange 60 Lens mounter 61, 61A Frame 62 First dustproof sheet 63 Light shielding plate 63a Flat plate portion 65 First heat dissipation portion 67 Second heat dissipation portion 69 Fixing portion 69a Spacer 71 Flange surface 72 Second dustproof sheet 73 Recess 75 Bottom wall 75a Through hole 77 Side wall 79 Protrusion 80 Opening 81 Through hole 83 Heat insulating material 91 First frame portion 93 Second frame portion 95 Gap

Claims (13)

a light modulation element that modulates incident illumination light into image light or unwanted light;
a prism disposed opposite the light modulation element and guiding the illumination light to the light modulation element;
a light blocking plate that blocks the unnecessary light emitted from the light modulation element;
a frame that houses the prism;
an imaging unit that captures an image of imaging light incident through the prism;
a fixing portion that fixes the light blocking plate to the frame,
the imaging unit is attached to the frame on the opposite side of the fixed unit with respect to the prism;
Light modulation unit. The distance from the fixed portion to the imaging unit is longer than the width of the prism.
The light modulation unit according to claim 1 . The fixing portion has a spacer disposed between the light blocking plate and the frame.
The light modulation unit according to claim 1 . the imaging unit is fixed to the frame via a heat insulating material;
The light modulation unit according to claim 1 . the imaging unit includes an imaging element that receives the imaging light and a lens that configures a reduction optical system;
The light modulation unit according to claim 1 . the light blocking plate extends from the inside to the outside of the frame at a location closer to the fixed part than the imaging part, and has an extension portion disposed outside the frame.
The light modulation unit according to claim 1 . a heat dissipation portion disposed on the extending portion of the light blocking plate;
The light modulation unit according to claim 6 . a heat dissipation unit is disposed between the fixed unit and the imaging unit in the frame;
The light modulation unit according to claim 1 . a fan for blowing air between the fixed portion and the imaging portion in the frame;
The light modulation unit according to claim 1 . a light modulation element that modulates incident illumination light into image light or unwanted light;
a prism disposed opposite the light modulation element and guiding the illumination light to the light modulation element;
a light blocking plate that blocks the unnecessary light emitted from the light modulation element;
a frame that houses the prism;
an imaging unit that captures an image of imaging light incident through the prism;
a fixing portion that fixes the light blocking plate to the frame,
the frame has a first frame portion and a second frame portion;
the fixing portion is disposed on the first frame portion,
the imaging unit is fixed to the second frame unit,
A gap is formed between the first frame portion and the second frame portion.
Light modulation unit. A heat insulating material is disposed in the gap.
The light modulation unit according to claim 10. A light modulation unit according to any one of claims 1 to 11;
a projection lens unit fixed to the frame via a lens mounter;
Projection-type image display device. a connection portion between the frame and the lens mounter having a sealed structure;
the light blocking plate extends from the inside to the outside of the frame;
a dustproof sheet is disposed on a portion of the light-shielding plate extending from the inside to the outside of the sealed structure;
13. The projection-type image display device according to claim 12.