JP5804536B2 - Illumination optical system and projection display device - Google Patents

Description

  The present invention relates to an illumination optical system and a projection display device including the illumination optical system.

  An illumination optical system, an image forming element that modulates light (illumination light) emitted from the illumination optical system based on an image signal, and a projection optical system that projects light (image light) modulated by the image forming element A projection display device provided is known. The illumination optical system includes a light source and a plurality of optical elements for guiding light emitted from the light source to the image forming element. For the image forming element, a liquid crystal panel, DMD (Micro Mirror Device), or the like is used. A projection display device using a liquid crystal panel as an image forming element is generally called a “liquid crystal projector”, and a projection display device using a DMD is generally called a “DMD projector”.

  In recent years, an LED (Light Emitting Device) has attracted attention as a light source of the illumination optical system. Patent Document 1 describes a projection display device including an illumination optical system that uses an LED as a light source.

JP 2003-186110 A

  However, LEDs emit less light than discharge lamps. For this reason, in order to obtain a bright image, it is important to increase the light emission amount of the LED and improve the utilization efficiency of the light emitted from the LED. In order to increase the light emission amount of the LED, it is necessary to enlarge the light emission area of the LED. On the other hand, in order to improve the light utilization efficiency, it is necessary to reduce the etendue of the LED. Specifically, it is necessary to make the etendue of the LED equal to or less than the product of the area of the light incident surface of the image forming element and the light capture angle.

  However, the etendue of the LED is determined by the product of the light emitting area of the LED and the solid angle (radiation angle) of the light emitted from the LED. Therefore, if the light emission area of the LED is increased in order to increase the light emission amount, the etendue increases and the light use efficiency decreases.

  The illumination optical system according to the present invention is an illumination optical system used in a projection display device. One of the illumination optical systems according to the present invention includes a solid-state light source, and a light conversion unit that converts the first light emitted from the solid-state light source into second light having a peak wavelength different from that of the first light. A polarization conversion element that aligns the polarization direction of the second light, and an optical system that guides the second light emitted from the light conversion unit to the polarization conversion element. The light conversion unit is formed on a first surface on which a wavelength selection film that transmits the first light and reflects the second light is formed, and on a part of the surface of the wavelength selection film. A phosphor layer that is excited by the first light and emits the second light. The polarization conversion element has a polarization separation surface and a reflection surface alternately arranged at a first pitch, and a polarization direction of light reflected by the reflection surface matches a polarization direction of light transmitted through the polarization separation surface. And a phase difference plate. The optical system includes a high light intensity region corresponding to a region where the phosphor layer is formed on the first surface of the light conversion unit, and the first surface of the light conversion unit, A secondary light source image having a light intensity distribution in which a low light intensity region corresponding to a region where a phosphor layer is not formed alternately exists at a second pitch equal to or less than the first pitch, On the incident surface.

  Another illumination optical system according to the present invention includes a solid-state light source, a second light having a peak wavelength different from that of the first light, and the first light emitted from the solid-state light source, A light conversion unit that converts the light into a third light having a different peak wavelength from the second light, a first polarization conversion element that aligns the polarization direction of the second light, and the third light A second polarization conversion element that aligns the polarization direction, a first optical system that guides the second light emitted from the light conversion unit to the first polarization conversion element, and a light emitted from the light conversion unit And a second optical system for guiding the third light to the second polarization conversion element. The light conversion unit is a phosphor layer formed on a first surface and a part of the first surface, and is a first phosphor that is excited by the first light and emits the second light. A phosphor layer formed on another part of the first surface, wherein the second phosphor layer is excited by the first light and emits the third light. And have. The first and second polarization conversion elements are polarized light separation surfaces and reflection surfaces alternately arranged at a first pitch, and light transmitted through the polarization separation surface with a polarization direction of light reflected by the reflection surfaces. And a retardation plate that matches the polarization direction. The first optical system includes a high light intensity region corresponding to a region where the first phosphor layer is formed on the first surface of the light conversion unit, and the first light conversion unit. And a low light intensity region corresponding to the region where the second phosphor layer is formed on the surface of the surface having a light intensity distribution alternately present at a second pitch equal to or less than the first pitch. A next light source image is formed on the incident surface of the first polarization conversion element. The second optical system includes a high light intensity region corresponding to a region where the second phosphor layer is formed on the first surface of the light conversion unit, and the first light conversion unit. A secondary light source image having a light intensity distribution in which low light intensity regions corresponding to regions on which the first phosphor layer is formed alternately exist at the second pitch, It is formed on the incident surface of the second polarization conversion element.

  According to the present invention, an illumination optical system with high brightness and low etendue and a projection display device including the illumination optical system are realized.

FIG. 1 is a schematic plan view showing a first embodiment of the illumination optical system of the present invention. FIG. 2 is an enlarged plan view showing the light conversion unit. FIG. 3 is a schematic plan view showing a first surface of the light conversion unit. FIG. 4 is a schematic diagram showing the light intensity distribution of the secondary light source image. FIG. 5 is a schematic cross-sectional view showing a polarization conversion element. FIG. 6 is a schematic plan view showing an example of a projection display device provided with the illumination optical system of the present invention. 7A and 7B are schematic plan views showing the light emitting surface of the LED, and FIG. 7C is a schematic plan view showing the first surface of the light conversion unit. FIG. 8 is an enlarged plan view showing the light conversion unit. FIG. 9 is a schematic plan view showing a second opening of the light tunnel. FIG. 10 is a schematic plan view showing another example of a projection display device provided with the illumination optical system of the present invention. FIG. 11 is a schematic plan view showing a first surface of the light conversion unit. FIG. 12 is a schematic plan view showing a first surface of the light conversion unit.

  Next, one embodiment of the present invention will be described. FIG. 1 is a plan view showing a configuration of an illumination optical system according to the present embodiment. The illustrated illumination optical system includes a solid-state light source 10, five lenses (lenses 11, 12, 13, 14, 15), a dichroic mirror 16, a light tunnel 17, and a polarization conversion element 18.

  The light tunnel 17 is a hollow prism having a reflecting surface formed inside, and rectangular openings are formed at both ends. In the following description, of the two openings of the light tunnel 17, the opening through which the light emitted from the solid light source 10 enters is referred to as a “first opening” and is the opening opposite to the first opening. The part is called a “second opening” for distinction. However, such a distinction is merely a distinction for convenience of explanation.

  As shown in FIG. 1, the solid-state light source 10 and the light tunnel 17 face each other. The lenses 11, 12 and 13, the dichroic mirror 16 and the lens 14 are arranged in this order between the solid light source 10 and the light tunnel 17 facing each other. Further, the lens 15 is disposed between the dichroic mirror 16 and the polarization conversion element 18.

  As shown in FIG. 1, a light conversion unit 20 is provided in the second opening of the light tunnel 17. FIG. 2 shows the light conversion unit 20 in an enlarged manner. As shown in FIG. 2, the light conversion unit 20 includes a glass block 21 having a substantially trapezoidal cross-sectional shape. The glass block 21 is attached to the second opening of the light tunnel 17 such that one surface (bottom surface 22) closes the second opening of the light tunnel 17. A wavelength selection film 23 is formed on the entire bottom surface 22 of the glass block 21 that covers the second opening of the light tunnel 17. The wavelength selection film 23 has wavelength selectivity that transmits light (peak wavelength λ1) emitted from the solid light source 10 and reflects light having a longer wavelength (peak wavelength λ2) than light emitted from the solid light source 10. . A reflective film 24 is formed on a surface other than the bottom surface of the glass block 21.

  Further, as shown in FIG. 3, a phosphor layer 25 is partially formed on the wavelength selection film 23 formed on the glass block bottom surface 22. Specifically, the phosphor layer 25 is laminated only on one half of the surface of the wavelength selection film. The phosphor layer 25 is formed by applying a medium in which the phosphor is dispersed to a predetermined region on the surface of the wavelength selection film. As the medium, for example, a silicon-based binder, glass, translucent ceramics, or the like can be used.

  Refer to FIG. 1 again. The first light (excitation light) emitted from the solid light source 10 passes through the lenses 11 to 13, the dichroic mirror 16, and the lens 14 and enters the light tunnel 17 from the first opening of the light tunnel 17. The excitation light incident on the light tunnel 17 reaches the light conversion unit 20 while being repeatedly reflected in the light tunnel 17. As shown in FIG. 2, a part of the excitation light reaching the light conversion unit 20 enters the front surface of the phosphor layer 25 to excite the phosphor. Another part of the excitation light that reaches the light conversion unit 20 passes through the wavelength selection film 23 and enters the glass block 21. The excitation light incident on the glass block 21 is reflected by the reflection film 24 and incident on the back surface of the phosphor layer 25 to excite the phosphor. In any case, the second light (fluorescence) is emitted from the phosphor excited by the excitation light. In other words, light is emitted from the region where the phosphor layer 25 is formed, but no light is emitted from the region where the phosphor layer 25 is not formed. That is, adjacent light emitting portions and non-light emitting portions exist on the glass block bottom surface 22 (on the wavelength selection film 23).

  Refer to FIG. 1 again. The light emitted from the phosphor layer 25 enters the light tunnel 17 from the second opening of the light tunnel 17. The light incident on the light tunnel 17 reaches the first opening while being repeatedly reflected in the light tunnel 17. The light emitted from the first opening of the light tunnel 17 is reflected by the dichroic mirror 16 and enters the lens 15.

  Here, the lens 14 and the lens 15 are designed to form a secondary light source image on the incident surface of the polarization conversion element 18. Specifically, it is designed so that an image of the light conversion unit 20 (glass block bottom surface 22) is formed on the incident surface of the polarization conversion element 18. Further, the light incident on the polarization conversion element 18 through the lenses 14 and 15 is reflected a plurality of times in the light tunnel 17. Therefore, a plurality of secondary light source images are formed in an array on the incident surface of the polarization conversion element 18. Further, in each secondary light source image, the light intensity of the portion corresponding to the light emitting portion (region where the phosphor layer 25 is formed) is increased, and the non-light emitting portion (region where the phosphor layer 25 is not formed). The light intensity in the part corresponding to) becomes weaker. As a result, a secondary light source image having a light intensity distribution as shown in FIG. 4 is formed on the incident surface of the polarization conversion element 18. Specifically, a secondary light source image having a light intensity distribution in which high light intensity regions 31 and low light intensity regions 32 are alternately arranged in stripes is formed. In order to obtain a secondary light source image having a light intensity distribution as shown in FIG. 4, the light tunnel 17 only needs to have at least a pair of opposing reflecting surfaces. Moreover, although the diameter of the light tunnel 17 in the present embodiment gradually increases from the second opening toward the first opening, the diameter of the light tunnel may be constant.

  The polarization conversion element 18 emits light having a uniform polarization direction by rotating the polarization plane of the incident light. Specifically, either the P-polarized component or the S-polarized component contained in the incident light is transmitted, and the other polarization plane is rotated by 90 °. As shown in FIG. 5, the polarization conversion element 18 includes a polarization beam splitter 40 and a phase difference plate (1/2 wavelength plate) 41. In the polarization beam splitter 40, polarization separation films 42 and reflection films 43 are alternately arranged at a predetermined pitch. The phase difference plate 41 is disposed on the exit surface of the polarization beam splitter 40 and on the optical path of the light reflected by the reflection film 43. The phase difference plate 41 may be disposed on the light exit surface of the polarization beam splitter 40 and on the optical path of the light transmitted through the polarization separation film 42.

  Here, the polarization conversion element 18 is set such that the arrangement pitch of the polarization separation film 42 and the reflection film 43 is equal to or greater than the arrangement pitch of the high light intensity region 31 and the low light intensity region 32 shown in FIG. Furthermore, the polarization conversion element 18 is designed and arranged so that light belonging to the high light intensity region 31 shown in FIG. 4 enters the corresponding polarization separation film 42. Therefore, the light belonging to each high light intensity region 31 enters the corresponding polarization separation film 42 and is separated according to the polarization component. Specifically, the P-polarized component contained in the light incident on the polarization separation film 42 is transmitted through the polarization separation film 42, and the S-polarized component is reflected toward the reflection film 43. The S-polarized component incident on the reflective film 43 is reflected by the reflective film 43 and enters the phase difference plate 41. The S-polarized component incident on the phase difference plate 41 is converted into a P-polarized component by rotating the plane of polarization by 90 ° by the phase difference plate 41.

  From the description so far, it should be understood that the etendue of the illumination optical system according to the present embodiment depends on the area of the light emitting section of the light conversion section 20 (area of the phosphor layer 25). That is, the etendue of the illumination optical system according to the present embodiment depends on the area of the phosphor layer 25 and does not depend on the area of the light emitting surface of the solid light source 10. Therefore, even if the light emitting surface of the solid light source 10 is enlarged to increase the light emission amount of the solid light source 10, the etendue of the illumination optical system does not increase. On the other hand, when the light emission amount of the solid light source 10 increases, the amount of light emitted from the phosphor layer 25 increases. In general, an illumination optical system that achieves high-luminance illumination light with a small etendue is realized.

  In addition, when the area of the phosphor layer 25 is smaller than the area of the light emitting surface of the solid light source 10, in order for all of the light emitted from the solid light source 10 to enter one surface of the phosphor layer 25, the solid layer It is necessary to stop the light emitted from the light source 10. However, when the light emitted from the solid light source 10 is reduced, a part of the light is lost. Therefore, in this embodiment, as shown in FIG. 2, a part of the light emitted from the solid light source 10 is incident on the front surface of the phosphor layer 25 and the other part is incident on the rear surface of the phosphor layer 25. ing. With this configuration, the light emitted from the solid light source 10 can be used without waste.

  FIG. 6 shows an example of a projection display device to which the present invention is applied. The projection display apparatus according to the present embodiment includes a first blue LED 110, lenses 111, 112, 113, 114, and 115, a dichroic mirror 116, a light tunnel 117G, and a polarization conversion element 118.

  The blue LED 110 corresponds to the solid light source 10 shown in FIG. 1, the lenses 111 to 115 correspond to the lenses 11 to 15 shown in FIG. 1, and the dichroic mirror 116 is the dichroic mirror shown in FIG. 16, the light tunnel 117G corresponds to the light tunnel 17 shown in FIG. 1, and the polarization conversion element 118 corresponds to the polarization conversion element 18 shown in FIG.

  The blue LED 110 faces the first opening of the light tunnel 117G. The lenses 111, 112, 113, the dichroic mirror 116, and the lens 114 are arranged in this order between the blue LED 110 and the first opening of the light tunnel 117G. In addition, a light conversion unit 120 corresponding to the light conversion unit 20 illustrated in FIG. 1 is provided in the second opening of the light tunnel 117G. The dichroic mirror 116 has wavelength selectivity that transmits blue light and reflects green light.

  The projection display apparatus according to this embodiment further includes a second blue LED 201 and a red LED 202. The blue LED 201 is provided at one end of the light tunnel 117B, and the red LED 202 is provided at one end of the light tunnel 117R. The light tunnels 117B and 117R have the same shape, size and function as the light tunnel 117G.

FIG. 7A is a plan view showing a light emitting surface of the first blue LED 110, and FIG. 7B is a plan view showing light emitting surfaces of the second blue LED 201 and the red LED 202. As shown in FIGS. 7A and 7B, the light emitting surface of the first blue LED 110 has an area twice that of the light emitting surfaces of the second blue LED 201 and the red LED 202. Specifically, the area of the light emitting surface of the first blue LED 110 is 12.0 mm ² (width 4.0 mm × height 3.0 mm), whereas the area of the light emitting surface of the second blue LED 201 and the red LED 202 is 6.0. mm ² (width 2.0 mm x height 3.0 mm). Therefore, the light emission amount of the first blue LED 110 is twice the light emission amount of the second blue LED 201 and the red LED 202.

FIG.7 (c) is a top view which shows the bottom face 122 of the glass block 121 which comprises the light conversion part 120 shown in FIG. The glass block bottom surface 122 has the same shape and size as the light emitting surface of the first blue LED 110. That is, the area of the glass block bottom surface 122 is 12.0 mm ² (width 4.0 mm × height 3.0 mm). A wavelength selection film 123 is formed on the entire surface of the glass block bottom surface 122, and a phosphor layer 125 is laminated on the left half of the surface of the wavelength selection film. That is, the area of the wavelength selection film 123 is 12.0 mm ² (width 4.0 mm × height 3.0 mm), and the area of the phosphor layer 125 is 6.0 mm ² (width 2.0 mm × height 3.0 mm). In other words, the shape and dimensions of the phosphor layer 125 are the same as those of the light emitting surfaces of the second blue LED 201 and the red LED 202. The phosphor layer 125 in this embodiment includes a phosphor that is excited by the blue light emitted from the first blue LED 110 and emits green light. The wavelength selection film 123 has wavelength selectivity that transmits blue light emitted from the first blue LED 110 and reflects green light emitted from the phosphor layer 125.

  Refer to FIG. 6 again. The first light (blue light / excitation light) emitted from the first blue LED 110 passes through the lenses 111, 112, 113, the dichroic mirror 116, and the lens 114 and enters the light tunnel 117G. The excitation light incident on the light tunnel 117G passes through the light tunnel 117G and reaches the light conversion unit 120. As shown in FIG. 8, part of the excitation light that reaches the light conversion unit 120 enters the front surface of the phosphor layer 125. Another part of the excitation light that has reached the light conversion unit 120 passes through the wavelength selection film 123 and enters the glass block 121. The excitation light incident on the glass block 121 is reflected by the reflective film 124 formed on the side surface of the glass block 121 and is incident on the back surface of the phosphor layer 125. Then, the phosphor contained in the phosphor layer 125 is excited by the excitation light incident from the front surface or the back surface of the phosphor layer 125, and second light (green light / fluorescence) is emitted from the phosphor layer 125. . The green light emitted from the phosphor layer 125 enters the light tunnel 117G from the second opening of the light tunnel 117G.

  Refer to FIG. 6 again. The green light incident on the light tunnel 117G reaches the first opening while being repeatedly reflected in the light tunnel 117G. The green light emitted from the first opening of the light tunnel 117G passes through the lens 114 and enters the dichroic mirror 116. The green light incident on the dichroic mirror 116 is reflected by the dichroic mirror 116, passes through the dichroic mirror 301, and enters the lens 115.

  As shown in FIG. 9A, the second blue LED 201 occupies the left half of the second opening of the light tunnel 117B. In other words, the left half of the second opening of the light tunnel 117 </ b> B is covered with the light emitting surface of the blue LED 201. On the other hand, as shown in FIG. 9B, the red LED 202 occupies the right half of the second opening of the light tunnel 117R. In other words, the right half of the second opening of the light tunnel 117R is covered with the light emitting surface of the red LED 202.

  Returning to FIG. The light (blue light) emitted from the second blue LED 201 enters the light tunnel 117B from the second opening of the light tunnel 117B. The blue light incident on the light tunnel 117B reaches the first opening of the light tunnel 117B while being repeatedly reflected in the light tunnel 117B. The blue light emitted from the first opening of the light tunnel 117B passes through the lens 302 and the dichroic mirrors 116 and 301 and enters the lens 115.

  Light (red light) emitted from the red LED 202 is incident on the light tunnel 117R from the second opening of the light tunnel 117R. The red light incident on the light tunnel 117R reaches the first opening of the light tunnel 117R while being repeatedly reflected in the light tunnel 117R. The red light emitted from the first opening of the light tunnel 117R passes through the lenses 303 and 304, is reflected by the dichroic mirror 301, and enters the lens 115.

  A secondary light source image is formed on the incident surface of the polarization conversion element 118 by the light incident on the lens 115 as described above. Specifically, an image of the light conversion unit 120 (glass block bottom surface 122), an image of the light emitting surface of the blue LED 201, and an image of the light emitting surface of the red LED 202 are formed on the incident surface of the polarization conversion element 118. Further, the light incident on the polarization conversion element 118 is reflected a plurality of times in the light tunnels 117R, 117G, and 117B. Therefore, the images are formed in an array on the incident surface of the polarization conversion element 118 and superimposed.

  Here, in the image of the glass block bottom surface 122, the light intensity of the portion corresponding to the light emitting portion (region where the phosphor layer 125 is formed) on the glass block bottom surface 122 is strong, and the non-light emitting portion (phosphor layer is The light intensity of the portion corresponding to the (non-formed region) is weak. In other words, the image of the glass block bottom surface 122 has a light intensity distribution in which the high light intensity regions 31 and the low light intensity regions 32 are alternately arranged in stripes (see FIG. 4).

  Further, the image of the light emitting surface of the blue LED 201 and the image of the light emitting surface of the red LED 202 are superimposed on the high intensity region 31. As described above, white light having an excellent light amount balance can be obtained.

  In general, the luminous efficiency of a green LED is lower than that of a blue LED or a red LED. For this reason, when the green LED having the light emitting surface of the same area as the light emitting surface of the blue LED 201 or the red LED 202 is used instead of the phosphor layer 125, the amount of green light is insufficient. On the other hand, in this embodiment, the area of the phosphor layer 125 is the same as the area of the light emitting surface of the blue LED 201 and the red LED 202, but the area of the light emitting surface of the blue LED 110 that is the excitation light source of the phosphor layer 125 is phosphor. It is twice the area of the layer 125. In other words, the area of the light emitting surface of the blue LED 110 is twice the area of the light emitting surface of the blue LED 201 and the red LED 202. Therefore, since a sufficient amount of green light is emitted from the phosphor layer 125, white light having an excellent light amount balance can be obtained.

  Furthermore, the etendue of the illumination optical system according to the present embodiment depends on the area of the phosphor layer 125, the areas of the light emitting surfaces of the second blue LED 201 and the red LED 202, and the area of the light emitting surface of the first blue LED 110 is Do not depend. Therefore, even if the area of the light emitting surface of the first blue LED 110 is increased, the etendue of the illumination optical system does not increase.

  Refer to FIG. 6 again. The white light obtained as described above is aligned in the polarization direction by the polarization conversion element 118. White light whose polarization direction is aligned enters the dichroic mirror 401. The blue light contained in the white light incident on the dichroic mirror 401 is reflected by the dichroic mirror 401, and the other color lights are transmitted through the dichroic mirror 401.

  The blue light reflected by the dichroic mirror 401 is incident on the liquid crystal panel 406 via the lens 402, the mirror 403, the lens 404 and the incident side polarizing plate 405.

  The colored light that has passed through the dichroic mirror 401 passes through the lens 501 and enters the dichroic mirror 502. The green light included in the color light incident on the dichroic mirror 502 is reflected by the dichroic mirror 502, and the other color light (red light) passes through the dichroic mirror 502.

  The green light reflected by the dichroic mirror 502 enters the liquid crystal panel 505 via the lens 503 and the incident side polarizing plate 504. The red light transmitted through the dichroic mirror 502 is incident on the liquid crystal panel 607 via the lens 601, the mirror 602, the lens 603, the mirror 604, the lens 605, and the incident-side polarizing plate 606.

  The light incident on each of the liquid crystal panels 406, 505, and 607 is modulated based on the image signal, and then enters the cross dichroic prism 701 via the output side polarizing plate and is combined. The light synthesized by the cross dichroic prism 701 is projected by a projection lens 702 onto a screen (not shown).

  FIG. 10 shows another example of a projection display device to which the present invention is applied. The projection display apparatus according to this embodiment includes a blue laser 810, lenses 811, 814, and 815, a dichroic mirror 816, a light tunnel 817, and a polarization conversion element 818.

  The blue laser LED 810 corresponds to the solid-state light source 10 shown in FIG. 1, the lenses 811, 814, and 815 correspond to the lenses 11, 14, and 15 shown in FIG. 1, respectively, and the dichroic mirror 816 is shown in FIG. Corresponding to the dichroic mirror 16 shown, the light tunnel 817 corresponds to the light tunnel 17 shown in FIG. 1, and the polarization conversion element 818 corresponds to the polarization conversion element 18 shown in FIG.

  The blue laser 810 faces the first opening of the light tunnel 817. The lens 811, the lens 814, and the dichroic mirror 816 are disposed in this order between the blue laser 810 and the first opening of the light tunnel 817. In addition, a light conversion unit 820 corresponding to the light conversion unit 20 illustrated in FIG. 1 is provided in the second opening of the light tunnel 817. The dichroic mirror 816 has wavelength selectivity that transmits blue light and reflects green light and red light.

  The projection display apparatus according to this embodiment further includes a blue LED 901. The blue LED 901 is provided at one end of the light tunnel 902. The light tunnel 902 has the same shape, size, and function as the light tunnel 817.

  The first light (blue light / excitation light) emitted from the blue laser 810 passes through the lens 811, the dichroic mirror 816 and the lens 814 and enters the light tunnel 817. The excitation light incident on the light tunnel 817 passes through the light tunnel 817 and reaches the light conversion unit 820.

FIG. 11 is a plan view showing the bottom surface 822 of the glass block 821 constituting the light conversion unit 820. The area of the glass block bottom surface 822 is 12.0 mm ² (width 4.0 mm × height 3.0 mm). A wavelength selection film 823 (FIG. 12) is formed on the entire surface of the glass block bottom surface 822, the first phosphor layer 825G is formed on the left half of the surface of the wavelength selection film, and the second fluorescence is formed on the right half. A body layer 825R is formed. That is, the areas of the phosphor layer 825G and the phosphor layer 825R are 6.0 mm ² (width 2.0 mm × height 3.0 mm). Although not shown, the light emitting surface of the blue LED 901 has the same shape and dimensions as the phosphor layer 825G and the phosphor layer 825R.

  In the first phosphor layer 825G in this embodiment, the fluorescence that is excited by the first light (blue light / excitation light) emitted from the blue laser 810 and emits the second light (green light / fluorescence). Contains the body. On the other hand, the second phosphor layer 825R includes a phosphor that is excited by the first light (excitation light) emitted from the blue laser 810 and emits the third light (red light / fluorescence). Yes. The wavelength selection film 823 has a wavelength selectivity that transmits light emitted from the blue laser 810 and reflects light emitted from the phosphor layers 825G and 825R.

  As shown in FIG. 12, a part of the excitation light reaching the light conversion unit 120 is incident on the front surface of the phosphor layer 825G, and the other part of the excitation light is incident on the front surface of the phosphor layer 825R. Further, the excitation light that has not been absorbed by the phosphor layers 825G and 825R passes through the wavelength selection film 823 and enters the glass block 821. The excitation light that has entered the glass block 821 is reflected by the reflective film 824 formed on the side surface of the glass block 821, and enters the back surface of the phosphor layer 825G or the phosphor layer 825R. Then, the phosphor contained in the phosphor layer 825G is excited by the excitation light incident from the front surface or the back surface of the phosphor layer 825G, and second light (green light / fluorescence) is emitted from the phosphor layer 825G. Is done. Further, the phosphor contained in the phosphor layer 825R is excited by the excitation light incident from the front surface or the back surface of the phosphor layer 825R, and third light (red light / fluorescence) is emitted from the phosphor layer 825R. Is done.

  The green light emitted from the phosphor layer 825G and the red light emitted from the phosphor layer 825R enter the light tunnel 817 through the second opening of the light tunnel 817.

  Refer to FIG. 10 again. Green light and red light incident on the light tunnel 817 reach the first opening while being repeatedly reflected in the light tunnel 817. Green light and red light emitted from the first opening of the light tunnel 817 pass through the lens 814 and enter the dichroic mirror 816. Green light and red light incident on the dichroic mirror 816 are reflected by the dichroic mirror 816 and enter the dichroic mirror 903. The green light incident on the dichroic mirror 903 passes through the dichroic mirror 903 and enters the lens 815. On the other hand, the red light incident on the dichroic mirror 903 is reflected by the dichroic mirror 903 and enters the lens 904.

  Light (blue light) emitted from the blue LED 901 enters the light tunnel 902 from the second opening of the light tunnel 902. The blue light incident on the light tunnel 902 reaches the first opening of the light tunnel 902 while being repeatedly reflected in the light tunnel 902. Blue light emitted from the first opening of the light tunnel 902 passes through the lens 905 and the dichroic mirrors 816 and 903 and enters the lens 815. Note that the light emitting surface of the blue LED 901 covers the left half of the second opening of the light tunnel 902.

  The lens 815 and the lens 814 are designed to form a secondary light source image on the incident surface of the polarization conversion element 818. The lens 815 and the lens 905 are also designed so as to form a secondary light source image on the incident surface of the polarization conversion element 818. Specifically, the lens 815 and the lens 814 are designed to form an image of the phosphor layer 825G on the incident surface of the polarization conversion element 818. The lens 815 and the lens 905 are designed to form an image of the light emitting surface of the blue LED 901 on the incident surface of the polarization conversion element 818.

  Further, the lens 904 and the lens 814 are designed to form a secondary light source image on the incident surface of the polarization conversion element 906. Specifically, the lens 904 and the lens 814 are designed to form an image of the phosphor layer 825R on the incident surface of the polarization conversion element 906.

  Here, the image of the phosphor layer 825G formed on the incident surface of the polarization conversion element 818 and the image of the light emitting surface of the blue LED 901 have a light intensity distribution similar to the light intensity distribution shown in FIG. Further, the image of the phosphor layer 825R formed on the incident surface of the polarization conversion element 906 also has a light intensity distribution similar to the light intensity distribution shown in FIG.

  The polarization direction of the light incident on the polarization conversion element 818 is aligned by the polarization conversion element 818. Further, the polarization direction of the light incident on the polarization conversion element 906 is aligned by the polarization conversion element 906. Thereafter, the light emitted from the polarization conversion element 8181 is separated into green light and blue light, and the green light is incident on the liquid crystal panel 910 and the blue light is incident on the liquid crystal panel 911. Further, the red light emitted from the polarization conversion element 906 enters the liquid crystal panel 912. Since the configuration around each liquid crystal panel is substantially the same as that of the first embodiment, description thereof is omitted.

Claims (10)

An illumination optical system for a projection display device,
A solid light source;
A light conversion unit that converts the first light emitted from the solid-state light source into second light having a peak wavelength different from that of the first light;
A polarization conversion element that aligns the polarization direction of the second light;
An optical system for guiding the second light emitted from the light conversion unit to the polarization conversion element,
The light conversion unit is
A first surface on which a wavelength selection film that transmits the first light and reflects the second light is formed;
A phosphor layer formed on a part of the surface of the wavelength selective film, the phosphor layer being excited by the first light and emitting the second light,
The polarization conversion element is:
Polarization separation surfaces and reflection surfaces alternately arranged at a first pitch;
A retardation plate that matches the polarization direction of the light reflected by the reflection surface and the polarization direction of the light transmitted through the polarization separation surface,
The optical system includes a high light intensity region corresponding to a region where the phosphor layer is formed on the first surface of the light conversion unit, and the first surface of the light conversion unit, A secondary light source image having a light intensity distribution in which a low light intensity region corresponding to a region where a phosphor layer is not formed alternately exists at a second pitch equal to or less than the first pitch, An illumination optical system formed on the incident surface.   The illumination optical system according to claim 1, wherein an area of the phosphor layer is smaller than an area of a light emitting surface of the solid light source. Having a reflective film formed on the second surface of the light conversion section;
A portion of the first light is incident on the phosphor layer from its front surface,
3. The illumination according to claim 1, wherein another part of the first light is reflected by the reflection film after passing through the wavelength selection film and is incident on the phosphor layer from its back surface. Optical system. The optical system includes
A light tunnel comprising a first opening facing the light emitting surface of the solid-state light source, and a second opening located on the opposite side of the first opening;
A dichroic mirror disposed between the light emitting surface of the solid-state light source and the first opening of the light tunnel, which transmits the first light and reflects the second light; A dichroic mirror,
A first lens disposed between the dichroic mirror and the first opening of the light tunnel;
And at least a second lens disposed between the dichroic mirror and the incident surface of the polarization conversion element,
The light conversion unit is provided in the second opening, such that the first surface of the light conversion unit closes the second opening of the light tunnel,
The first lens and the second lens condense the second light that has passed through the light tunnel onto the incident surface of the polarization conversion element to form the secondary light source image. The illumination optical system according to any one of claims 3 to 3. An illumination optical system for a projection display device,
A solid light source;
A second light having a peak wavelength different from that of the first light, and a third light having a peak wavelength different from that of the first light and the second light. A light conversion unit for converting into,
A first polarization conversion element that aligns the polarization direction of the second light;
A second polarization conversion element that aligns the polarization direction of the third light;
A first optical system for guiding the second light emitted from the light conversion unit to the first polarization conversion element;
A second optical system for guiding the third light emitted from the light conversion unit to the second polarization conversion element;
The light conversion unit is
The first aspect,
A phosphor layer formed on a part of the first surface, the first phosphor layer being excited by the first light and emitting the second light;
A phosphor layer formed on another part of the first surface, the second phosphor layer being excited by the first light and emitting the third light,
The first and second polarization conversion elements are:
Polarization separation surfaces and reflection surfaces alternately arranged at a first pitch;
A retardation plate that matches the polarization direction of the light reflected by the reflection surface with the polarization direction of the light transmitted through the polarization separation surface, and
The first optical system includes a high light intensity region corresponding to a region where the first phosphor layer is formed on the first surface of the light conversion unit, and the first light conversion unit. And a low light intensity region corresponding to the region where the second phosphor layer is formed on the surface of the surface having a light intensity distribution alternately present at a second pitch equal to or less than the first pitch. Forming a next light source image on the incident surface of the first polarization conversion element;
The second optical system includes a high light intensity region corresponding to a region where the second phosphor layer is formed on the first surface of the light conversion unit, and the first light conversion unit. A secondary light source image having a light intensity distribution in which low light intensity regions corresponding to regions on which the first phosphor layer is formed alternately exist at the second pitch, An illumination optical system formed on the incident surface of the second polarization conversion element. The illumination optical system according to claim 5, wherein the areas of the first phosphor layer and the second phosphor layer are the same as the area of the light emitting surface of the solid-state light source. Having a reflective film formed on the second surface of the light conversion section;
A part of the first light transmitted through the first phosphor layer is reflected by the reflective film and enters the first phosphor layer from its back surface,
The part of said 1st light which permeate | transmitted said 2nd fluorescent substance layer is reflected by the said reflecting film, and injects into the said 2nd fluorescent substance layer from the back surface. The illumination optical system described. In the optical system including the first optical system and the second optical system ,
A light tunnel comprising a first opening facing the light emitting surface of the solid-state light source, and a second opening located on the opposite side of the first opening;
A dichroic mirror disposed between the light emitting surface of the solid-state light source and the first opening of the light tunnel, wherein the first light is transmitted through the second light and the third light; A first dichroic mirror that reflects the light of
A first lens disposed between the first dichroic mirror and the first opening of the light tunnel;
A second lens disposed between the first dichroic mirror and the incident surface of the first polarization conversion element;
A dichroic mirror disposed between the first dichroic mirror and the second lens, the second dichroic mirror transmitting the second light and reflecting the third light; ,
At least a third lens disposed between the second dichroic mirror and the second polarization conversion element;
The light conversion unit is provided in the second opening, such that the first surface of the light conversion unit closes the second opening of the light tunnel,
The first lens and the second lens condense the second light that has passed through the light tunnel onto the incident surface of the first polarization conversion element to form the secondary light source image,
The first lens and the third lens condense the third light that has passed through the light tunnel onto the incident surface of the second polarization conversion element to form the secondary light source image. The illumination optical system according to any one of claims 5 to 7.   The illumination optical system according to any one of claims 1 to 8, wherein the solid-state light source is an LED or a semiconductor laser.   A projection display apparatus comprising the illumination optical system according to any one of claims 1 to 9.

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