Projection-type image display device

Abstract

A projection-type image display device according to the present disclosure comprises: a red laser light source that outputs red light; a green laser light source that outputs green light; a blue laser light source that outputs blue light; an excitation laser light source that outputs excitation light; a wavelength conversion element that, through irradiation with the excitation light, emits colored light, which is light of a wavelength region differing from each of the wavelength regions of the red light, the green light, and the blue light; a light synthesizing element that synthesizes the red light, the green light, the blue light, and the colored light to generate synthesized light; a light uniformizing element that uniformizes an intensity distribution of the synthesized light; an optical modulation element that modulates the light uniformized by the light uniformizing element into image light on the basis of an input image signal; and a projection unit that projects the light modulated by the optical modulation element.

Description

Projection-type image display device

[0001] The present disclosure relates to a projection-type image display device that includes a red laser light source, a green laser light source, a blue laser light source, and a wavelength conversion element that emits light when irradiated with excitation light.

[0002] Patent Document 1 discloses a projection-type image display device in which, in each of at least two light-emitting means selected from a red light-emitting means, a green light-emitting means, and a blue light-emitting means, light of a wavelength shifted from the primary color light is added to the primary color light, thereby ensuring at least two brightnesses of red, green, and blue, and also in which the wavelength range of the light emitted from each of the at least two light-emitting means is wider than when only primary color light is emitted, thereby improving the color reproducibility of intermediate colors between red, green, and blue.

[0003] Patent No. 6086282

[0004] The present disclosure provides a projection-type image display device that can achieve both a wider color gamut and higher brightness, and at the same time reduce speckle noise.

[0005] The projection-type video display device of the present disclosure includes a red laser light source that emits red light, a green laser light source that emits green light, a blue laser light source that emits blue light, an excitation laser light source that emits excitation light, a wavelength conversion element that emits yellow light when irradiated with the excitation light, a light combining element that combines the red light, green light, blue light, and yellow light, a light homogenizing element that homogenizes the red light, green light, blue light, and yellow light, a light modulation element that modulates the light homogenized by the light homogenizing element, and a projection unit that projects the light modulated by the light modulation element.

[0006] According to the present disclosure, it is possible to realize a wider color gamut of image light displayed on a projection-type image display device.

[0007] 1. A diagram showing a projection type video display device in embodiment 1. 2. A diagram showing an RGB light source unit in embodiment 1. 3. A diagram showing an excitation light source unit in embodiment 1. 4. A diagram showing a phosphor wheel in embodiment 1. 5. A spectrum diagram of color light in a projection type video display device in embodiment 1. 6. A diagram showing a subframe configuration in embodiment 1. 7. A diagram showing an image frame configuration in embodiment 1. 8. A spectrum diagram of each color segment in embodiment 1. 9. A spectrum diagram of each color segment in embodiment 1. 10. A spectrum diagram of each color segment in embodiment 1. 11. A spectrum diagram of each color segment in embodiment 1. 12. A chromaticity diagram in embodiment 1. 13. A chromaticity diagram in embodiment 1. 14. A table showing projection light characteristics in the embodiment.

[0008] 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.

[0009] 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.

[0010] [Embodiment 1] (Projection-type video display device) The configuration of a projection-type video display device according to embodiment 1 will be described below with reference to Figures 1 to 6. Figure 1 is a diagram showing the optical configuration of a projection-type video display device 100 according to embodiment 1. In embodiment 1, an example will be shown in which red component light R, green component light G, blue component light B, and yellow component light Ye are used as video light.

[0011] As shown in FIG. 1, first, the projection-type image display device 100 has an RGB light source unit 10, an excitation light source unit 20, a phosphor wheel 30, a dichroic mirror 40, a rod integrator 50, a DMD (Digital Mirror Device) 60, and a projection unit 70.

[0012] 2, the RGB light source unit 10 is composed of a red light source 10R, a green light source 10G, a blue light source 10B, a mirror 14R, a dichroic mirror 14G, and a dichroic mirror 14B. The red light source 10R is composed of a red light source heat dissipation substrate 11R, a plurality of red light source emitters 12R, and a plurality of red light source collimating lenses 13R. The green light source 10G is composed of a green light source heat dissipation substrate 11G, a plurality of green light source emitters 12G, and a plurality of green light source collimating lenses 13G. The blue light source 10B is composed of a blue light source heat dissipation substrate 11B, a plurality of blue light source emitters 12B, and a plurality of blue light source collimating lenses 13B. The red light source emitter 12R, the green light source emitter 12G, and the blue light source emitter 12B are each configured, for example, by a laser diode (LD) or a light-emitting diode (LED). In this embodiment, the red light source emitter 12R is configured by a red laser diode that emits light with a dominant wavelength of 642 nm (red component light R), the green light source emitter 12G is configured by a green laser diode that emits light with a dominant wavelength of 525 nm (green component light G), and the blue light source emitter is configured by a blue laser diode that emits light with a dominant wavelength of 465 nm (blue component light B). However, these wavelengths are not limited thereto. For example, the dominant wavelength of the red light source emitter 12R may be 630 to 650 nm, the dominant wavelength of the green light source emitter 12G may be 515 to 535 nm, and the dominant wavelength of the blue light source emitter 12B may be 440 to 470 nm.

[0013] The mirror 14R reflects the light emitted from the red light source 12R. The dichroic mirror 14G reflects the light emitted from the green light source 10G and transmits the light emitted from the red light source 12R reflected by the mirror 14R. The dichroic mirror 14B reflects the light emitted from the blue light source 12B, transmits the light emitted from the red light source 12R that has been reflected by the mirror 14R and transmitted by the dichroic mirror 14B, and transmits the light emitted from the green light source 12G that has been reflected by the dichroic mirror 14G. Therefore, the light emitted from the RGB light source unit 10 is white light that is a combination of light with a dominant wavelength of 642 nm (red component light R), light with a dominant wavelength of 525 nm (green component light G), and light with a dominant wavelength of 465 nm (blue component light B).

[0014] 3, the excitation light source unit 20 is composed of an excitation light source 20Ex and a mirror 24. The excitation light source 20Ex is composed of an excitation light source heat dissipation substrate 21, a plurality of excitation light source emitters 22, and a plurality of excitation light source collimating lenses 23. The excitation light source emitters 22 are composed of, for example, a laser diode (LD) or a light emitting diode (LED).

[0015] In this embodiment, the excitation light source emitter 22 is configured with a blue laser diode that emits light (excitation light Ex) with a dominant wavelength of 455 nm. However, this wavelength is not limited, and for example, the dominant wavelength of the excitation light source emitter 22 may be 440 to 470 nm, or may be the same dominant wavelength as the blue light source emitter 12B.

[0016] As shown in Fig. 4, the phosphor wheel 30 is composed of a substrate 31, a reflective film 32 formed on the substrate 31, a phosphor film 33 coated in a circular shape on the reflective film 32, and a motor 34 for rotating the substrate 31. The phosphor wheel 30 is an example of a wavelength conversion element. Fig. 4(a) is a view of the phosphor wheel as viewed in the z direction of Fig. 1, and Fig. 4(b) is a view as viewed in the y direction of Fig. 1.

[0017] The phosphor film 33 is composed of a yellow phosphor film that emits yellow light when irradiated with excitation light Ex. In Fig. 4A, a reference numeral in parentheses indicates that a component not enclosed in parentheses is located above it. That is, Fig. 4A shows that a reflective film 32 is disposed on a substrate 31, and a phosphor film 33 is located on the reflective film 32.

[0018] The phosphor film 33 is composed of a yellow phosphor film that emits yellow light (light with a dominant wavelength of 560 to 590 nm) when irradiated with excitation light. The yellow light described above is an example of colored light output by a wavelength conversion element. The phosphor film 33 can be produced, for example, by mixing ceramic phosphor powder into an adhesive (silicone resin), applying the mixture to a substrate, and curing it at high temperature. Examples of ceramic phosphors used in the phosphor film 33 include YAG phosphors and LAG phosphors, which are cerium-activated garnet structure phosphors.

[0019] The position of the phosphor wheel 30 where the excitation light is irradiated changes in the circumferential direction as the motor 34 rotates, and the emitted light Ye is emitted from the phosphor film 33. Although the phosphor wheel 30 is used in this embodiment, a fixed, non-rotating phosphor light source may also be used.

[0020] Returning to FIG. 1, the dichroic mirror 40 transmits the red component light R, the green component light G, and the blue component light B, and emits the emitted light Ye ０ Yellow component light Ye １ It has a coating property that reflects light.

[0021] 1, we will first explain the optical paths of the red component light R, green component light G, and blue component light B. The light (red component light R, green component light G, and blue component light B) emitted from the RGB light source unit 10 is guided to the rod integrator 50 via a mirror 111, a diffuser 112, a lens 113, a mirror 114, a diffuser 115, a mirror 116, a lens 117, a dichroic mirror 40, a lens 118, a mirror 119, and a lens 121.

[0022] The mirrors 111, 114, and 116 are reflecting mirrors that reflect red component light R, green component light G, and blue component light B, respectively.

[0023] The mirror 119 is configured to receive red component light R, green component light G, blue component light B, and yellow component light Ye. １ It is a reflective mirror that reflects

[0024] The diffusion plates 112 and 115 are diffusion plates that adjust the spread angles of the red component light R, the green component light G, and the blue component light B.

[0025] Lens 113 is a lens that focuses red component light R, green component light G, and blue component light B near diffuser plate 115. At this time, the size and shape of the focused spot formed on diffuser plate 115 are determined according to the diffusion angle characteristics of diffuser plate 112. Lens 117 is a lens that approximately collimates the divergent light emitted from diffuser plate 115. Lenses 118 and 121 are lenses that focus the light that has been approximately collimated by lens 117 onto rod integrator 50. At this time, the focused spot formed on diffuser plate 115 is approximately imaged on the incident surface of rod integrator 50 via lenses 117, 118, and 121 (the incident surfaces of diffuser plate 115 and rod integrator 50 are approximately conjugate).

[0026] Next, the excitation light Ex and the emission light Ye ０ , yellow component light Ye １ The light emitted from the excitation light source unit 20 (excitation light Ex) is irradiated onto the phosphor wheel 30 via the diffusion plate 122, the dichroic mirror 40, the lens 123, and the lens 124. The irradiation of the excitation light Ex causes the phosphor wheel 30 to emit the emitted light Ye. ０ is emitted. ０ is guided to the rod integrator 50 via the lens 124, the lens 123, the dichroic mirror 40, the lens 118, the mirror 119, and the lens 121. At this time, the emitted light Ye ０ is reflected by the dichroic mirror 40 and becomes yellow component light Ye １ This becomes:

[0027] The diffusion plate 122 is a diffusion plate that adjusts the divergence angle of the excitation light Ex.

[0028] The lenses 123 and 124 are lenses that focus the excitation light Ex on the surface of the phosphor wheel 30. At this time, the size and shape of the focused spot formed on the phosphor wheel 30 are determined according to the diffusion angle characteristics of the diffuser plate 122. In addition, the lenses 123 and 124 focus the emitted light Ye emitted from the phosphor wheel 30. ０ The light is converted into approximately parallel light.

[0029] The lenses 118 and 121 are lenses that condense the light that has been converted into approximately parallel light by the lenses 123 and 124 onto the rod integrator 50. At this time, the emitted light Ye emitted from the phosphor wheel 30 ０ is approximately imaged on the incident surface of rod integrator 50 via lenses 124, 123, 118, and 121 (the exit surface of phosphor wheel 30 and the incident surface of rod integrator 50 are approximately conjugate).

[0030] 5 shows the spectrum of each color light. The dichroic mirror 40 transmits the excitation light Ex, the blue component light B, the green component light G, and the red component light R, and transmits the emission light Ye ０ Among them, yellow component light Ye １ Therefore, the yellow component light Ye １ The wavelength band of yellow component light Ye is located between green component light (525 nm) and red component light (642 nm), and is mainly light of 525 to 642 nm. １ The dominant wavelength of yellow component light Ye is 525 to 642 nm. １ The dominant wavelength of the yellow component light Ye is 575 nm. １ The wavelength band of (2) may be any other dominant wavelength as long as it is in the yellow wavelength band (560 to 590 nm).

[0031] The rod integrator 50 is a solid rod made of a transparent material such as glass. The rod integrator 50 homogenizes the light emitted from the RGB light source unit 10 and the light emitted from the phosphor wheel 30. The rod integrator 50 may be a hollow rod whose inner wall is made of a mirror surface. The rod integrator 50 is an example of a light homogenizing element.

[0032] The light emitted from rod integrator 50 passes through lenses 131 , 132 , and 133 , and is incident on a total reflection prism consisting of triangular prisms 141 and 142 , and then incident on DMD 60 .

[0033] The DMD 60 modulates each color component light (red component light R, green component light G, blue component light B, and yellow component light Ye) generated by the RGB light source unit 10 and the phosphor wheel 30 in a time-division manner. Specifically, the DMD 60 is composed of multiple movable micromirrors. Each micromirror basically corresponds to one pixel. The DMD 60 switches between reflecting light toward the projection unit 70 and not reflecting light toward the projection unit 70 through a modulation operation that changes the angle of each micromirror in response to a video signal.

[0034] 6A and 6B show the correspondence between the display period of each color on the DMD 60 and the light emission period of each color light source. In this embodiment, during operation of the DMD 60, one video frame (e.g., 1 / 60 sec) is composed of multiple subframes ( FIG. 6B ), and each subframe is composed of color segments corresponding to the color displays of R, Ye, G, Cy, and B ( FIG. 6A ). The more subframes there are per video frame, the faster the color switching speed, thereby reducing the color breaking phenomenon. To achieve a switching speed at which the color breaking phenomenon is barely noticeable, it is desirable to have 16 or more subframes (16x speed). Note that the color segments in one subframe may be configured as R, G, B or R, G, B, Ye, or may have a configuration with different numbers of colors mixed in different subframes. The order of the color segments may also be regular or irregular.

[0035] 6A, 6B, and 7A-7E, the principle of image light generation in the DMD 60 will be described. The DMD 60 expresses the gradation of each color corresponding to the color segments R, Ye, G, Cy, and B. During the period of the color segment R, the red light source 10R and the excitation light source 20Ex are turned on. That is, as shown in FIG. 7A, red component light R and yellow component light Ye generated in response to the excitation light Ex are emitted. １is modulated by the DMD 60. During the period of the color segment Ye, the red light source 10R, the green light source 10G, and the excitation light source 20Ex are turned on, that is, as shown in FIG. 7B, the yellow component light Ye generated in response to the red component light R, the green component light G, and the excitation light Ex is modulated. １ is modulated by the DMD 60. During the period of the color segment G, the green light source 10G and the excitation light source 20Ex are turned on, that is, as shown in FIG. 7C, green component light G and yellow component light Ye generated in response to the excitation light Ex are modulated. １ is modulated by the DMD 60. During the period of the color segment Cy, the green light source 10G, the blue light source 10B, and the excitation light source 20Ex are turned on, that is, as shown in FIG. 7D, the green component light G, the blue component light B, and the yellow component light Ye generated in response to the excitation light Ex are modulated. １ is modulated by the DMD 60. During the period of color segment B, the blue light source 10B is turned on, that is, blue component light B as shown in FIG. 7E is modulated by the DMD 60. The DMD 60 is an example of a light modulation element. That is, the red light source 10R, the green light source 10G, the blue light source 10B, and the excitation light source 20Ex are controlled by a control unit (not shown) so that the light sources are turned on in subframes corresponding to the respective segment periods, and are turned off in the respective subframe periods not corresponding to the respective segment periods.

[0036] Returning to FIG. 1 , the image light modulated and generated by the DMD 60 passes through triangular prisms 141 and 142 and enters the projection unit 70. The image light entering the projection unit 70 is enlarged and projected onto a screen (not shown). The projection unit includes an optical system that enlarges and projects the image light, including, for example, multiple lenses. The control unit includes a CPU and executes a control program to control the illumination of the light source and realize the functions of the projection-type image display device 100. Note that the control unit may be realized solely by hardware circuits designed specifically to realize predetermined functions. In addition to the CPU, the control unit may be configured with various circuits such as an MPU, GPU, DSP, FPGA, and ASIC. The control unit may also include a storage device that stores the control program and various information.

[0037] Here, the chromaticity of each color segment can be adjusted by adjusting the light emission intensity of 20Ex (current input to the laser diode) using an excitation light source control unit (not shown). Specifically, for example, during the period of color segment R, red component light R and yellow component light Ye １ As shown in FIG. 8A, the intensity ratio of the chromaticity point R(x Ｒ , y Ｒ ) color light and chromaticity point Ye(x Ｙｅ , y Ｙｅ ) color light, the result is a composite chromaticity point R'(x' Ｒ , y′ Ｒ Similarly, during the period of the color segment G, green component light G and yellow component light Ye １ As shown in FIG. 8A, the intensity ratio of the chromaticity point G(x Ｇ , y Ｇ ) color light and chromaticity point Ye(x Ｙｅ , y Ｙｅ ) color light, the result is a composite chromaticity point G'(x' Ｇ , y′ Ｇ As a result, the color gamut of the projection display device 100 is the color light of the composite chromaticity point R'(x' Ｒ , y′ Ｒ ), composite chromaticity point G'(x' Ｇ , y′ Ｇ ), chromaticity point B(x Ｂ , y Ｂ ) (FIG. 8A), which results in a color gamut that covers Rec. 709. Meanwhile, the light intensity of the excitation light source 20Ex can be freely adjusted within the specification range of the laser diode, but it can also be turned off completely. In this case, the color gamut of the projection display device 100 is a triangular area formed by chromaticity points R(x), as shown in FIG. 8B. Ｒ , y Ｒ ), chromaticity point G(x Ｇ , y Ｇ ), chromaticity point B(x Ｂ , y Ｂ ) is the triangular area formed by

[0038] In this way, the color gamut can be freely varied by adjusting the emission intensity of the excitation light source 20Ex using a control unit (not shown). The projection display device 100 can be equipped with a mode that supports Rec. 709 and a mode that supports Rec. 2020 as video modes. The supported color gamut standards are not limited to these, and can be freely set. Furthermore, the color gamut can be dynamically changed according to the video frame while analyzing the video frame.

[0039] Furthermore, the projection-type image display device 100 uses a laser diode that emits red component light R, green component light G, and blue component light B, which have low visibility, as opposed to yellow component light Ye, which has high visibility. １ The table shown in FIG. 9 shows the yellow component light Ye １ Without yellow component light Ye １ 9 shows the visibility and light intensity at 10,000 lm for the red component light R, green component light G, and blue component light B. １ By mixing the colors, the light intensity required to achieve the same brightness is reduced. Therefore, the light intensity incident on the DMD 60 and the projection unit can be reduced, making it possible to achieve higher brightness.

[0040] Furthermore, the projection-type image display device 100 is configured to suppress speckle noise caused by red component light R and green component light G, which are highly coherent laser diode emitted light, by suppressing speckle noise caused by yellow component light Ye, which has low coherence. １ By mixing the colors, speckle noise can be reduced.

[0041] (Functions and Effects) In the first embodiment, it is possible to achieve both a wider color gamut and higher brightness by driving the RGB light source unit 10 and the excitation light source unit 20 while adjusting the light emission timing and light emission intensity of the units. At the same time, it is possible to reduce speckle noise.

[0042] [Other Embodiments] As described above, the first embodiment has been described as an example of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can also be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made.

[0043] In the first embodiment, the DMD 60 is used as an example of the light modulation element, but the embodiment is not limited to this. The light modulation element may be one liquid crystal panel or three liquid crystal panels (a red liquid crystal panel, a green liquid crystal panel, and a blue liquid crystal panel). The liquid crystal panels may be either transmissive or reflective.

[0044] In the first embodiment, a phosphor wheel is used as an example of the phosphor that generates the emitted light, but the embodiment is not limited to this. The phosphor may be a static inorganic phosphor ceramic.

[0045] Although yellow light is used as an example of light output from the phosphor wheel in the first embodiment, the present invention is not limited to this. The effects of the present invention can be achieved by outputting light in a wavelength range different from the wavelength ranges of the light output from the red light source emitter 12R, the green light source 12G, and the blue light source emitter 12B.

[0046] It should be noted that the above-described embodiments are intended to illustrate the technology of the present disclosure, and various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents.

[0047] The present disclosure can be applied to a projection-type image display device such as a projector.

[0048] REFERENCE SIGNS LIST 10 RGB light source unit 20 Excitation light source unit 30 Phosphor wheel 40 Dichroic mirror 50 Rod integrator 60 DMD 70 Projection unit 100 Projection type image display device

Claims

1. A projection-type video display device comprising: a red laser light source that emits red light; a green laser light source that emits green light; a blue laser light source that emits blue light; an excitation laser light source that emits excitation light; a wavelength conversion element that emits colored light which is light in a wavelength range different from each of the wavelength ranges of the red light, the green light, and the blue light by irradiation with the excitation light; a light synthesis element that synthesizes the red light, the green light, the blue light, and the colored light to generate synthesized light; a light homogenization element that homogenizes the intensity distribution of the synthesized light; a light modulation element that modulates the light homogenized by the light homogenization element into video light based on an input video signal; and a projection unit that projects the light modulated by the light modulation element.

2. The projection-type video display device according to claim 1, wherein the colored light is light including a wavelength range of yellow light, and the light synthesis element has a characteristic that the main wavelength of the light extracted from the yellow light is 560 to 590 nm.

3. The projection-type video display device according to claim 2, further comprising a control unit, wherein the control unit controls lighting or extinguishing of the light sources during a segment period in which each color component of the video light is generated by the light modulation element.

4. The projection-type video display device according to claim 3, wherein the control unit controls to turn on the red laser light source and the excitation laser light source and turn off the green laser light source and the blue laser light source during a red segment period in the light modulation element.

5. The projection-type video display device according to claim 3, wherein the control unit controls to turn on the green laser light source and the excitation laser light source and turn off the red laser light source and the blue laser light source during a green segment period in the light modulation element.

6. The projection-type video display device according to claim 3, wherein the control unit controls to turn on the blue laser light source and turn off the red laser light source, the green laser light source, and the excitation laser light source during a blue segment period in the light modulation element.

7. The projection-type video display device according to claim 3, wherein the control unit controls to turn on the red laser light source, the green laser light source, and the excitation laser light source and turn off the blue laser light source during a yellow segment period in the light modulation element.

8. The projection type video display device according to claim 3, wherein the control unit controls to turn on the green laser light source, the blue laser light source, and the excitation laser light source and turn off the red laser light source during the cyan segment period in the optical modulation element.

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