JPWO2004068197A1 - Composite prism, light source unit, and display device - Google Patents

Abstract

The composite prism (1) has a first selective reflection on the surface constituted by the first corner (101), the third corner (103), the seventh corner (107) and the fifth corner (105). A surface (5) is provided. Further, the second selective reflection surface (6) is formed on the surface constituted by the third corner (103), the fourth corner (104), the fifth corner (105), and the sixth corner (106). I have. The first selective reflection surface (5) and the second selective reflection surface (6) are constituted by a polarization separation film. Therefore, unlike the X-cube, the optical paths of a plurality of color lights can be combined and separated without aligning the ridge lines of the four prisms in a straight line.

Description

  The present invention relates to a composite prism, a light source unit, and a display device used in a projection display device and the like.

2. Description of the Related Art Conventionally, in an optical apparatus such as a projection display apparatus (hereinafter referred to as a projector), a plurality of plate-like optical elements are used for the purpose of synthesizing or separating optical paths of light having different wavelengths. For this reason, there exists a problem that an optical apparatus cannot be reduced in size. Therefore, a cubic dichroic prism in which four right triangular prisms are joined in an X shape may be used as a composite prism that integrates such functions. Such a dichroic prism is called an X-cube because of the shape of the joint portion.
In this dichroic prism, a selective reflection film capable of selectively reflecting red light and a selective reflection film capable of selectively reflecting blue light are arranged in a cross, and is used as an optical path synthesis element in a liquid crystal projector. Yes. At this time, three of the four side surfaces of the dichroic prism are used as the incident end surface, and the other one side surface is used as the output end surface (for example, JP-A-2002-90509).
However, in the X-cube, since the ridge lines of the four prisms need to be aligned, there is a problem that productivity is low and yield is low. In addition, the demand for angular tolerance is severe at the stage of a single prism. For this reason, there is a problem that the X cube becomes expensive. Further, in the case of the X-cube, the ridge lines of the four prisms are aligned in a straight line, so that a liquid crystal projector using the prism has a problem that the ridge line appears in the center of the projected image. Therefore, when the prisms are bonded to each other, the thickness of the adhesive must be reduced. However, if the thickness of the adhesive is reduced, there is a problem that reliability is lowered, such as weakening against heat shock. Furthermore, in the X-cube, the four side surfaces are used as the incident end surface and the output end surface, respectively, so there is no space on the side surfaces. Therefore, there is also a problem that the degree of freedom is low in the layout of the optical elements that constitute the optical path toward the X cube.
In view of the above problems, the problem of the present invention is that, unlike the X-cube, it is not necessary to align the ridge lines of the four prisms in a straight line, improving yield, reducing cost, improving reliability, and improving image quality. Another object of the present invention is to provide a new composite prism capable of improving the degree of freedom in design, a light source unit using the composite prism, and a display device.

In order to solve the above problems, in the composite prism of the present invention, light having at least predetermined optical characteristics is selectively transmitted to a plurality of joint surfaces formed by joining a plurality of light-transmitting members. The first selective reflection surface that reflects the other light and the second selective reflection surface are formed in a direction that intersects each other without being parallel or orthogonal to each other, and the first selective reflection surface and the first selective reflection surface The two selective reflection surfaces can synthesize or separate at least three light paths having different wavelengths.
In the present invention, the first selective reflection surface and the second selective reflection surface are formed on the bonding surface of the translucent member, and the optical paths of at least three lights having different wavelengths are formed by these selective reflection surfaces. Synthesize or separate. For this reason, since it is not necessary to synthesize or separate the optical paths using a single-plate polarization separation element or the like, the cost can be reduced and the degree of freedom in design can be improved. Also, unlike the X cube, it is not necessary to align the ridge lines of the four prisms in a straight line, so the yield is high and the reliability is high. In addition, the image quality can be improved.
In the present invention, each corner of the first rectangular plane having a rectangular parallelepiped shape composed of an opposing first rectangular plane and second rectangular plane is defined as a first corner, a second corner, a third corner, and A fourth corner, and each corner corresponding to the first corner, the second corner, the third corner, and the fourth corner in the second rectangular plane is a fifth corner, When the sixth corner portion, the seventh corner portion, and the eighth corner portion are defined, the first corner portion, the third corner portion, the seventh corner portion, and the fifth corner portion are formed on the first corner. And the second selective reflection surface is provided on a surface constituted by the third corner portion, the fourth corner portion, the fifth corner portion, and the sixth corner portion. It is characterized by.
In the present invention, for example, each of the first selective reflection surface and the second selective reflection surface is constituted by a polarization separation surface. Therefore, each of the first selective reflection surface and the second selective reflection surface transmits one of P-polarized light and S-polarized light within an arbitrary wavelength range, and the other. Reflects the light.
Such a composite prism can be used to form a display device including a plurality of electro-optical devices such as a liquid crystal light valve that modulates each color light emitted from the composite prism.
In another embodiment of the present invention, a plurality of columnar translucent members are joined to form an angle of 45 ° with respect to the incident surface, and a plurality of parallel joining surfaces are provided, and any of the plurality of joining surfaces is provided. The first selective reflection surface that selectively reflects light in a predetermined wavelength band is selected, and light in a wavelength band different from that of the first selective reflection surface is selected for any other joint surface The second selective reflecting surface that reflects the light is provided. Further, it is possible to separate the wavelength light having arbitrary polarized light by joining the polarization separation surfaces in parallel.
In the light source unit using the composite prism according to the present invention, the composite prism selectively uses the first color light in the wavelength bands of the three primary colors of red, green, and blue as the first selective reflection surface. A first dichroic mirror for color light that reflects, and a second dichroic mirror for color light that selectively reflects second color light toward the first dichroic mirror for color light as the second selective reflection surface; For the third color light, which is arranged on the opposite side of the first color light dichroic mirror with respect to the second color light dichroic mirror and reflects the third color light toward the second color light dichroic mirror A first color light source unit that emits the first color light toward the first dichroic mirror for color light, and is disposed toward the second dichroic mirror for color light. A second color light source unit that emits the second color light is disposed, a third color light source unit that emits the third color light toward the reflective surface is disposed, and the first color light source unit is disposed. It is preferable that light emission from the second color light source unit and the third color light source unit to the composite prism is switched at a predetermined timing.
In the light source unit using the composite prism according to the present invention, the composite prism selectively uses the first color light in the wavelength bands of the three primary colors of red, green, and blue as the first selective reflection surface. A first color light dichroic mirror that reflects, and a second color light dichroic mirror that selectively reflects second color light toward the first color light dichroic mirror as the second selective reflection surface; A first color light source unit that emits the first color light toward the first color light dichroic mirror is disposed, and emits the second color light toward the second color light dichroic mirror. A second color light source unit is disposed, and a third color light source unit that emits third color light from the opposite side of the second color light dichroic mirror to the second color light dichroic mirror is provided. , The first color light source unit, the second color light source section, and the third light emitted from the color light source unit to the composite prism preferably be switched at a predetermined timing.
In the present invention, each of the first color light source unit, the second color light source unit, and the third color light source unit is a light emitting element that emits predetermined color light, and the first color light source unit The lighting of the second color light source unit and the third color light source unit is controlled at a predetermined timing.
In the present invention, the first color light source unit, the second color light source unit, and the third color light source unit each emit light of each color obtained by color-dividing white light, Between the first color light source unit, the second color light source unit, the third color light source unit, and the composite prism, a shutter that controls the timing at which each color light is incident on the composite prism. You may employ | adopt the structure by which a means is arrange | positioned.
For example, in a light source unit including two composite prisms according to the present invention, of the two composite prisms, the first composite prism has three primary colors of red, green, and blue as the first selective reflecting surface. A first color light dichroic mirror that selectively reflects the first color light in the wavelength band, and a second color light directed toward the first color light dichroic mirror as the second selective reflection surface. A second color light dichroic mirror that selectively reflects, and a second color light dichroic mirror that is disposed on the opposite side of the first color light dichroic mirror to transmit the third color light to the second color light dichroic mirror. A third color light reflecting surface that reflects toward the color light dichroic mirror, and the second composite prism reflects the first color light to the first color light dichroic mirror of the first composite prism. A first color light reflecting surface that reflects toward the second color light and a second color light that selectively reflects toward the second color light dichroic mirror of the first composite prism as the first selective reflecting surface. A dichroic mirror for two color lights, and a dichroic for third color light that selectively reflects third color light as the second selective reflection surface toward the third color light reflection surface of the first composite prism. And a white light source that emits white light toward the third composite light dichroic mirror of the second composite prism with respect to the second composite prism, and the first composite prism; It is preferable that shutter means for controlling the timing at which each color light is incident on the first composite prism from the second composite prism is disposed between the second composite prism and the second composite prism. .
The light source unit to which the present invention is applied is used for a display device, for example.
For example, a display device is configured by arranging a plurality of the composite prisms in a matrix.
Further, the display device may be configured using an electro-optical device that sequentially modulates the color light emitted from the light source unit and sequentially generates color images corresponding to the color light.
In the present invention, it is preferable that the light source unit includes polarization conversion means for aligning the polarization direction of the color light emitted toward the electro-optical device. If comprised in this way, since the utilization efficiency of light can be improved, the brightness | luminance of a display image can be improved.
In this case, a projector or the like can be configured by using a projection optical system that projects images of each color sequentially formed by the electro-optical device.

FIG. 1 is an explanatory diagram of a composite prism according to Embodiment 1 of the present invention.
2A and 2B are exploded perspective views of the composite prism according to Embodiment 1 of the present invention, and FIG. 2C is an exploded perspective view of a conventional composite prism.
FIG. 3 is an explanatory diagram showing a method for manufacturing the composite prism according to the first embodiment of the present invention.
FIG. 4 is an explanatory diagram showing optical characteristics of the selective reflection surface formed on the composite prism according to Embodiment 1 of the present invention.
FIG. 5 is a front view, a left side view, and a plan view of the composite prism according to the first embodiment of the present invention.
FIG. 6 is an explanatory diagram showing optical characteristics of the selective reflection surface formed in the composite prism according to the modification of the first embodiment of the present invention.
FIG. 7 is an explanatory diagram of a liquid crystal projector using the composite prism according to the modification of the first embodiment of the present invention.
FIG. 8 is an explanatory diagram of a dichroic mirror array used in the liquid crystal projector shown in FIG.
FIG. 9 is an explanatory diagram of another dichroic mirror array used in the liquid crystal projector shown in FIG.
FIG. 10 is an explanatory diagram of the composite prism according to the second embodiment of the present invention.
FIG. 11 is an explanatory diagram showing optical characteristics of the selective reflection surface formed on the composite prism according to Embodiment 2 of the present invention.
FIG. 12 is an explanatory diagram showing a usage example of the composite prism according to the second embodiment of the present invention.
FIG. 13 is an explanatory diagram showing a method for manufacturing the composite prism according to the second embodiment of the present invention.
FIG. 14 is an explanatory diagram of a tail lamp using the composite prism according to the second embodiment of the present invention.
FIG. 15 is an explanatory diagram of a composite prism according to Modification 1 of Embodiment 2 of the present invention.
FIG. 16 is an explanatory diagram of a composite prism according to the second modification of the second embodiment of the present invention.
FIG. 17 is an explanatory diagram showing optical characteristics of the selective reflection surface used in the composite prism according to the second modification of the second embodiment of the present invention.
FIG. 18 is an explanatory diagram of a liquid crystal projector using the composite prism according to the first modification of the second embodiment of the present invention.
FIG. 19 is an explanatory diagram of another liquid crystal projector using the composite prism according to the first modification of the second embodiment of the present invention.
FIG. 20 is an explanatory diagram of a direct-view type liquid crystal display device using the composite prism according to the first modification of the second embodiment of the present invention.

Explanation of symbols

1, 2, Composite prism 5, 7 First selective reflection surface 6, 8 Second selective reflection surface 9 Total reflection surface 31 First rectangular plane 32 Second rectangular plane 51 Red LED
52 Green LED
53 Blue LED
66, 67, 68 Shutter (shutter means)
73 Polarizing Beam Splitters 74, 89, 171-173 Liquid Crystal Light Valve (Electro-Optical Device)
75 Projection optical system 80 Light source unit 81, 82 Polarization separation prism 83 Polarization conversion prism (polarization conversion means)
85 Polarization separation surface 86 Polarization beam splitter 91 Liquid crystal panel 111 White light source 110 Light source unit 150 Dichroic mirror arrays 221, 222, 223, 223, 224, 225 Translucent member LG Green light LR Red light LB Blue light

[Embodiment 1]
FIG. 1 is an explanatory diagram of a composite prism according to Embodiment 1 of the present invention. 2A and 2B are exploded perspective views of the composite prism according to Embodiment 1 of the present invention, and FIG. 2C is an exploded perspective view of a conventional composite prism. FIG. 3 is an explanatory diagram showing a method for manufacturing the composite prism according to the first embodiment of the present invention. FIG. 4 is an explanatory diagram showing optical characteristics of the selective reflection surface formed on the composite prism according to Embodiment 1 of the present invention. FIG. 5 is a front view, a left side view, and a plan view of the composite prism according to the first embodiment of the present invention.
In FIG. 1, the composite prism 1 of this embodiment is a cubic composite prism having a first rectangular plane 31 and a second rectangular plane 32 facing each other, and a plurality of translucent members are joined to each other. The following selective reflection surfaces are formed on the plurality of bonding surfaces formed by the above. That is, each corner of the first rectangular plane 31 is defined as a first corner 101, a second corner 102, a third corner 103, and a fourth corner 104, and the first corner of the second rectangular plane 32 is the first corner. The corner portions corresponding to the portion 101, the second corner portion 102, the third corner portion 103, and the fourth corner portion 104 are respectively designated as the fifth corner portion 105, the sixth corner portion 106, the seventh corner portion 107, and the eighth corner portion. When the portion 108 is used, the first selective reflection surface 5 is provided on the surface constituted by the first corner portion 101, the third corner portion 103, the seventh corner portion 107, and the fifth corner portion 105. Further, the second selective reflection surface 6 is provided on the surface constituted by the third corner portion 103, the fourth corner portion 104, the fifth corner portion 105, and the sixth corner portion 106. Accordingly, the first selective reflection surface 5 and the second selective reflection surface 6 are inclined by 45 ° with respect to the end surface of the composite prism 1.
When such a configuration is expressed using XYZ coordinate axes, the first selective reflection surface 5 includes a first corner portion 101 (x0, y0, z0), a third corner portion 103 (x1, y1, z0), The second selective reflection surface 6 is formed at the third corner portion by being formed on a rectangular joint surface including the seven corner portions 107 (x1, y1, z1) and the fifth corner portion 105 (x0, y0, z1). 103 (x1, y1, z0), a fourth corner portion 104 (x0, y1, z0), a fifth corner portion 105 (x0, y0, z1), and a sixth corner portion 106 (x1, y0, z1). The first selective reflection surface 5 and the second selective reflection surface 6 are not orthogonal to each other.
In order to manufacture the composite prism 1 having such a configuration, as shown in FIG. 2A, first, a rod-shaped beam splitter having a triangular cross section in which a first selective reflection surface 5 made of a multilayer film is formed on an inclined surface. Bar 301 is made.
Next, after this beam splitter bar 301 is joined via the first selective reflection surface 5, as shown in FIG. 2B, it is cut at an angle of 45 ° and polished.
Next, as shown in FIGS. 2B and 3A, a second selective reflection surface 6 made of a multilayer film is formed on the polished surface by low temperature deposition.
Next, as shown in FIG. 3B, after joining again in the bar shape, the cut surface is polished. As a result, the composite prism 1 is completed.
In such a composite prism 1, the flatness of the first selective reflection surface 5 and the second selective reflection surface 6 is not impaired when the composite prism 1 is manufactured. Moreover, since the 1st selective reflection surface 5 and the 2nd selective reflection surface 6 are each formed in the same plane, high flatness can be obtained. Further, unlike the X cube shown in FIG. 3C, it is not necessary to join the four prisms together at the right-angled ridges. Therefore, since it is not necessary to extremely reduce the thickness of the adhesive, good results are obtained even in the heat shock test, and high reliability is provided.
An example in which various optical elements are configured based on the composite prism 1 of this embodiment will be described below. First, in this example, each of the first selective reflection surface 5 and the second selective reflection surface 6 is formed of a multilayer film, and the first selective reflection surface 5 and the second selective reflection surface. Each of 6 is given selective reflection characteristics as described below.
That is, the first selective reflecting surface 5 has the optical characteristics shown in FIG. 4A, and the red light (light in the wavelength band centered on red) and green light (green A surface that transmits P-polarized light and reflects S-polarized light in the visible wavelength band of blue light (light having a wavelength band centered on blue) and blue light (light having a wavelength band centered on blue). The second selective reflection surface 6 is a blue reflection surface that imparts the optical characteristics shown in FIG. 4B and transmits red light and green light and reflects blue light. The second selective reflecting surface 6 is configured to transmit P-polarized light and reflect S-polarized light even for blue light.
In the composite prism 1 configured in this way, as shown in FIGS. 1 and 5, when the light LG incident from the rectangular plane 21 is green light previously polarized into P waves, the light LG (P) is Then, the light passes through the first selective reflection surface 5 and the second selective reflection surface 6 and goes straight toward the rectangular plane 22.
Further, when the light LR incident from the rectangular plane 11 is red light previously polarized into S waves, the light LR (S) is totally reflected by the first selective reflection surface 5 with an incident angle of 45 °. After that, the light passes through the second selective reflection surface 6 and travels toward the rectangular plane 22.
In addition, when the light LB incident from the rectangular plane 32 is blue light LB (S) previously polarized into S waves, the light LB is totally reflected on the second selective reflection surface 6 with an incident angle of 45 °. After the reflection, the light passes through the first selective reflection surface 5 and travels toward the rectangular plane 22.
Therefore, according to the composite prism 1 of the present embodiment, it is possible to synthesize optical paths of three colored lights having different wavelengths.
In other words, when white light whose polarization direction is adjusted is incident from the rectangular plane 22, the red light LR is emitted from the rectangular plane 11, the blue light LB is emitted from the rectangular plane 32, and the rectangular plane 21 Green light LB is emitted. Therefore, it can be said that the optical paths of three or more colored lights having different wavelengths can be separated. At this time, if the polarization direction is adjusted, the combined light of the red light LR and the green light LG can be emitted from the rectangular plane 12 and the combined light of the blue light LB and the green light LG can be emitted from the rectangular plane 31. .
[Modification of Embodiment 1]
6A and 6B show optical characteristics of the first selective reflection surface 5 and the second selective reflection surface 6 used in the composite prism 1 according to the modification of the first embodiment of the present invention. It is explanatory drawing which shows. FIG. 7 is an explanatory diagram of a liquid crystal projector using this composite prism. 8 and 9 are explanatory diagrams of the dichroic mirror array used in the liquid crystal projector shown in FIG.
As described with reference to FIG. 1, the composite prism 1 of the present example is also a cubic composite prism including a first rectangular plane 31 and a second rectangular plane 32 facing each other, The following selective reflection surfaces are formed on a plurality of bonding surfaces formed by bonding the translucent members. That is, each corner of the first rectangular plane 31 is defined as a first corner 101, a second corner 102, a third corner 103, and a fourth corner 104, and the first corner of the second rectangular plane 32 is the first corner. The corner portions corresponding to the portion 101, the second corner portion 102, the third corner portion 103, and the fourth corner portion 104 are respectively designated as the fifth corner portion 105, the sixth corner portion 106, the seventh corner portion 107, and the eighth corner portion. When the portion 108 is used, the first selective reflection surface 5 is provided on the surface constituted by the first corner portion 101, the third corner portion 103, the seventh corner portion 107, and the fifth corner portion 105. Further, the second selective reflection surface 6 is provided on the surface constituted by the third corner portion 103, the fourth corner portion 104, the fifth corner portion 105 and the sixth corner portion 106. Accordingly, the first selective reflection surface 5 and the second selective reflection surface 6 are inclined by 45 ° with respect to the end surface of the composite prism 1. Further, the first selective reflection surface 5 and the second selective reflection surface 6 are not orthogonal.
Here, the first selective reflection surface 5 is constituted by a polarization separation film having optical characteristics shown in FIG. 6A, and the second selective reflection surface 6 is shown in FIG. 6B. It is comprised by the polarization separation film provided with the optical characteristic.
As shown in FIG. 7, the liquid crystal projector using the composite prism 1 configured as described above has a light source unit 110 including a white light source 111 and a reflector 112, and white light emitted from the light source unit 110 is converted to P-polarized light. PBS (polarizing beam splitter) converter 120 for aligning, and dichroic mirror 130 for color-separating the light emitted from PBS converter 120 into blue light LB and mixed light of red light LR and green light LG is doing. For the blue light LB, a total reflection mirror 140 for guiding the light emitted from the dichroic mirror 130 to the rectangular plane 31 (see FIG. 1) of the composite prism 1 is disposed. The light enters the composite prism 1 as light.
On the other hand, for the mixed light of the red light LR and the green light LG, a dichroic mirror array 150 that selectively converts the green light LG into S-polarized light and a total reflection mirror 160 are arranged. The red light LR emitted as P-polarized light from the array 150 and the green light LG emitted as S-polarized light from the dichroic mirror array 150 enter the composite prism 1 along a common optical path.
Here, as the dichroic mirror array 150, the one shown in FIG. 8 or FIG. 9 can be used. Among these dichroic mirror arrays, the one shown in FIG. 8 has a parallelogram or triangular columnar translucent member 155 having an acute angle of 45 degrees in cross-section joined at an inclined end face. A dichroic mirror 152 that reflects green light LG and transmits red light LR is formed at the first bonding interface 151, and a total reflection mirror 154 is formed at the second bonding interface 153 that faces the first linking interface 151. . Further, an integral lens array 156 is disposed on the incident end face of the dichroic mirror array 150, and a ½λ plate 157 is disposed on the exit end face from the total reflection mirror 154.
Accordingly, when the P-polarized red light LR and the P-polarized green light LG emitted from the dichroic mirror 130 shown in FIG. 7 are guided to the dichroic mirror 152 by the integrated lens array 156, the red light LR is transmitted through the dichroic mirror 152. The light is transmitted and emitted as P-polarized light. On the other hand, the green light LG is reflected by the dichroic mirror 152, then reflected by the total reflection mirror 154 toward the 1 / 2λ plate 157, and emitted as S-polarized light.
In the dichroic mirror array 150, as shown in FIG. 9, a dichroic mirror 158 that transmits the green light LG and reflects the red light LR is formed at the first bonding interface 151, and the second dichroic mirror array 150 is opposed to the second dichroic mirror array 150. The junction interface 153 may have a configuration in which a total reflection mirror 159 is formed. In this dichroic mirror array 150, a 1 / 2λ plate 157 is disposed on the exit end face from the dichroic mirror 158. Therefore, when the P-polarized red light LR and the P-polarized green light LG emitted from the dichroic mirror 130 shown in FIG. 7 are guided to the dichroic mirror 158 by the integrated lens array (see FIG. 8), the green light LG is After passing through the dichroic mirror 158, it is converted to S-polarized light by the ½λ plate 157 and then emitted. On the other hand, the red light LR is reflected by the dichroic mirror 158, then reflected by the total reflection mirror 159, and emitted as P-polarized light.
In the liquid crystal projector configured as described above, with respect to a predetermined rectangular plane of the composite prism 1, a reflective liquid crystal light valve 171 (electro-optical device) for red light LR, a reflective liquid crystal light valve 172 for green light LG, In addition, a reflective liquid crystal light valve 173 for the blue light LB is disposed.
Accordingly, when the blue light LB is incident on the composite prism 1, the blue light LB passes through the second selective reflection surface 6, reaches the blue light liquid crystal light valve 173, and then is reflected by the liquid crystal light valve 173. In the meantime, the light component light-modulated for each pixel by the liquid crystal light valve 173 and converted into S-polarized light is reflected by the second selective reflection surface 6 and guided to the projection optical system (not shown).
Further, when the red light LR and the green light LG enter the composite prism 1 as mixed light, only the red light LR passes through the first selective reflection surface 5 and reaches the liquid crystal light valve 171 for red light. Reflected by the liquid crystal light valve 171. In the meantime, the light component light-modulated for each pixel by the liquid crystal light valve 171 and converted to S-polarized light is reflected by the first selective reflection surface 5 and guided to the projection optical system.
On the other hand, the green light LG is reflected by the first selective reflection surface 5 and reaches the liquid crystal light valve 172 for green light, and then is reflected by the liquid crystal light valve 172. In the meantime, the light component light-modulated for each pixel by the liquid crystal light valve 172 and converted into P-polarized light is transmitted through the first selective reflection surface 5 and guided to the projection optical system.
Then, a predetermined color image is displayed on the screen by each color light emitted from the projection optical system.
As described above, in the liquid crystal projector using the composite prism 1 of the present embodiment, the optical path of the blue light LB and the optical path of the mixed light of the red light LR and the green light LG need only be secured around the polarizing prism 1. Therefore, it is possible to reduce the size of the liquid crystal projector. In the liquid crystal projector using the composite prism 1 of this embodiment, when viewed from the polarizing prism 1, the optical path of the blue light LB, the optical path of the mixed light of the red light LR and the green light LG, and the output from the polarizing prism 1 are obtained. Since the light emission path can be arranged three-dimensionally, the degree of freedom in design when arranging the optical system in the liquid crystal projector is high.
Furthermore, unlike the X-cube, the composite prism 1 according to the present embodiment does not concentrate the ridge lines of each prism unit at one place, so that a situation in which the ridge line of the prism unit appears at the center of the projected image can be avoided.
[Embodiment 2]
FIG. 10 is an explanatory diagram of the composite prism according to the second embodiment of the present invention. FIG. 11 is an explanatory diagram showing optical characteristics of the selective reflection surface formed on the composite prism according to Embodiment 2 of the present invention. FIG. 12 is an explanatory diagram showing a usage example of the composite prism according to the second embodiment of the present invention. FIG. 13 is an explanatory diagram showing a method for manufacturing the composite prism according to the second embodiment of the present invention.
In FIG. 10, the composite prism 2 of this embodiment is a dichroic mirror module, and has a columnar translucent member 221 having a right isosceles triangle having an acute angle of 45 degrees in cross section and an acute angle of 45 degrees in cross section. The parallelogram-shaped columnar translucent members 222 and 223 having a parallelogram are joined at the inclined end faces. In addition, a columnar dummy translucent member 224 having a right-angled isosceles triangle having an acute angle of 45 degrees is joined to one end portion 226, and three joining surfaces 231, 232, and 233 are provided. Yes.
Among these three bonding interfaces 231, 232, and 233, the first selective reflection surface 7 formed of a dichroic mirror having the optical characteristics shown in FIG. 11 is formed at the first bonding interface 231. The selective reflection surface 7 reflects the red light LR and transmits the green light LG and the blue light LB. Further, a second selective reflection surface 8 made of a dichroic mirror having the optical characteristics shown in FIG. 11 is formed on the second bonding interface 232, and the second selective reflection surface 8 is formed of red light LR. The green light LG is reflected while the blue light LB is transmitted. Note that a total reflection surface 9 having optical characteristics shown in FIG. 11 is formed on the third bonding interface 233 as a mirror for blue light.
In the composite prism 2 configured in this way, the other end 227 is used as an output end face, and for example, as shown in FIG. 12, a diffusion lens 241 is disposed. A condensing plate 229 is disposed on the side surface of the composite prism 2. Further, the red LED 51 is disposed toward the first selective reflection surface 7 by the light collecting plate 229, the green LED 252 is disposed toward the second selective reflection surface 8, and the blue LED is directed toward the total reflection surface 9. LED53 is arrange | positioned.
In the module configured as described above, the red light LR emitted from the red LED 51 is reflected by the first selective reflection surface 7 in the composite prism 2 and emitted through the diffusion lens 41. The green light LG emitted from the green LED 52 is reflected by the second selective reflection surface 8 in the composite prism 2, then passes through the first selective reflection surface 7, and then passes through the diffusion lens 41. Emitted. The blue light LB emitted from the blue LED 53 is reflected by the total reflection surface 9 in the composite prism 2 and then sequentially transmitted through the second selective reflection surface 8 and the first selective reflection surface 7. The light is emitted through the diffusing lens 41.
Therefore, according to the composite prism 2 of this embodiment, it is possible to synthesize optical paths of three colored lights having different wavelengths. In addition to the white color, six color lights can be emitted by the combination of lighting the LEDs 51, 52, and 53.
In manufacturing the composite prism 2 having such a configuration, as shown in FIG. 13, each surface of a plurality of translucent substrates 160 having two parallel substrate surfaces was described with reference to FIG. After forming the first selective reflection surface 7, the second selective reflection surface 8, and the total reflection surface 9, these laminated substrates (translucent substrate 160) are photocured together with the dummy translucent substrate 161. Over the adhesive adhesive. At that time, the overlapping position is shifted so that the end of each substrate is 45 °. Next, after the photocurable adhesive is cured, it is cut so as to form an angle of 45 ° with respect to the substrate surfaces of the translucent substrates 160 and 161 along the cutting line indicated by the dotted line, and then cut. The surface is polished to produce the composite prism 2 shown in FIG. Therefore, unlike the X-cube, it is inexpensive because it has high production efficiency.
(Usage example of composite prism 2)
FIG. 14 is an explanatory diagram of a tail lamp using the composite prism according to the second embodiment of the present invention.
As for the composite prism 2, for example, as shown in FIG. 14, a display device such as a tail lamp 200 of an automobile can be configured by arranging a large number like a fly array in a matrix. Further, if the composite prism 2 of this embodiment is used, an outdoor display panel having 600,000 dots (1000 dots × 600 dots), or even 1 million dots (1200 dots × 830 dots) can be configured. In any of these display devices, if the three types of LEDs 51, 52, and 53 are lit at a predetermined timing, display can be performed in any color. In addition, the resolution is high even at a short distance, and it is possible to obtain a resolution more than twice that of a conventional display device. In addition to black display with one dot, seven colors can be expressed. In addition to brake lamps, there are seven types of signal lamps such as hazard lamps, back lamps, key lock warning lamps and anti-theft lamps. It can be used as various pilot lamps. Moreover, since the image design can be selected as an option, a unique lamp can be constructed.
[Modification 1 of Embodiment 2]
The composite prism 2 according to Embodiment 2 may be configured as, for example, a dichroic mirror array shown in FIG.
FIG. 15 is an explanatory diagram of a composite prism according to Modification 1 of Embodiment 2 of the present invention. In the composite prism 2 shown here, a columnar translucent member 221 having a right-angled isosceles triangle having an acute angle of 45 degrees in a cross-sectional shape and a columnar light-transmitting member having a parallelogram having an acute angle of 45 degrees in cross-section. Member 222 and a columnar translucent member 225 having an isosceles right triangle having an acute angle of 45 degrees in cross section are joined at an inclined end face, and two joining interfaces 231 and 232 are provided.
Of these two bonding interfaces, a first selective reflection surface 7 made of a dichroic mirror having the optical characteristics shown in FIG. 11 is formed at the first bonding interface 231, and this first selective reflection surface. 7 reflects the red light LR while transmitting the green light LG and the blue light LR. Further, a second selective reflection surface 8 made of a dichroic mirror having the optical characteristics shown in FIG. 11 is formed on the second bonding interface 232, and the second selective reflection surface 8 is formed of red light LR. The green light LG is reflected while the blue light LB is transmitted.
In the composite prism 2 configured in this way, for example, the diffusing lens 41 is disposed with the other end 227 serving as an output end surface. In addition, on the side surface of the composite prism 2, a red LED 51 is disposed toward the first selective reflection surface 7, and a green LED 52 is disposed toward the second selective reflection surface 8. In addition, a blue LED 53 is disposed at the end on the light transmitting member 25 side toward the other end 227.
In the module configured as described above, the red light LR emitted from the red LED 51 is reflected by the first selective reflection surface 7 in the composite prism 2 and emitted through the diffusion lens 41. The green light LG emitted from the green LED 52 is reflected by the second selective reflection surface 8 in the composite prism 2, then passes through the first selective reflection surface 7, and then passes through the diffusion lens 41. Emitted. The blue light LB emitted from the blue LED 53 is sequentially transmitted through the second selective reflection surface 8 and the first selective reflection surface 7, and then emitted through the diffusion lens 41.
Therefore, according to the composite prism 2 of this embodiment, it is possible to synthesize optical paths of three colored lights having different wavelengths. Such a composite prism 2 is also used as a display device such as the tail lamp 200 described with reference to FIG. Available.
[Modification 2 of Embodiment 2]
The composite prism according to Embodiment 2 may be configured as a dichroic mirror array for spectroscopy used in the module shown in FIG. 16, for example.
FIG. 16 is an explanatory diagram of a composite prism according to the second modification of the second embodiment of the present invention. FIG. 17 is an explanatory diagram showing optical characteristics of the selective reflection surface used in the composite prism according to the second modification of the second embodiment of the present invention.
In the composite prism 2 ′ shown here, a columnar translucent member 221 ′ having a right-angled isosceles triangle having an acute angle of 45 degrees and a columnar shape having a parallelogram shape having a sharp angle of 45 degrees. The translucent members 222 ′ and 223 ′ are joined at the inclined end surfaces. Also, a columnar dummy light-transmitting member 224 ′ having a right-angled isosceles triangle having an acute angle of 45 degrees is joined to one end portion 226 ′, and three joining surfaces 231 ′, 232 ′, 233 '.
Of these three bonding interfaces, the first bonding interface 231 ′ is formed with a total reflection surface 7 ′ having optical characteristics shown in FIG. 17 as a mirror for red light. In addition, a first selective reflection surface 8 ′ made of a dichroic mirror having the optical characteristics shown in FIG. 17 is formed on the second bonding interface 232 ′. The first selective reflection surface 8 ′ The blue light LB and the green light LG are reflected, while the red light LR is transmitted. Further, a second selective reflection surface 9 ′ made of a dichroic mirror having optical characteristics shown in FIG. 17 is formed on the third bonding interface 233 ′. While reflecting blue light LR, it transmits green light LG and red light LR.
For example, the shutter 63, the polarization conversion prism 69, the lens array 61, and the white light source 62 are disposed in the composite prism 2 ′ (second composite prism) configured as described above, with one end portion 27 ′ serving as an incident end surface. . Further, the composite prism 2 (first composite prism) described with reference to FIG. 10 is disposed on the side surface of the composite prism 2 ′ via the three shutters 66, 67, and 68 to constitute a light source unit. To do.
In the light source unit configured as described above, the light emitted from the white light source 62 is incident on the composite prism 2 ′ after the polarization direction is aligned by the polarization conversion prism 69. The blue light component contained in the white light is reflected by the second selective reflecting surface 9 ′ of the composite prism 2 ′ and enters the composite prism 2 as the blue light LB, while the red light component and the green light component are The second selective reflecting surface 9 'is transmitted. Next, the blue light LB incident on the composite prism 2 is reflected by the total reflection surface 9, and then sequentially passes through the second selective reflection surface 8 and the first selective reflection surface 7. 41 is emitted.
Further, the red light component and the green light component transmitted through the second selective reflection surface 9 ′ reach the first selective reflection surface 8 ′, and the green light component contained in the red light component and the green light component is the second light of the composite prism 2 ′. The red light component is transmitted through the first selective reflection surface 8 ′ while being reflected by the first selective reflection surface 8 ′ and entering the composite prism 2 as green light LG. The green light LG incident on the composite prism 2 is reflected by the second selective reflection surface 8, then passes through the first selective reflection surface 7, and is then emitted through the diffusion lens 41. .
The red light component transmitted through the first selective reflection surface 8 'is reflected by the total reflection surface 7' and enters the composite prism 2 as red light LR. Then, the red light LG incident on the composite prism 2 is reflected by the first selective reflection surface 7 and then emitted through the diffusion lens 41.
As described above, according to the composite prism 2 ′ of this embodiment, the optical paths of the three color lights having different wavelengths can be separated.
Also, any color can be emitted from the composite prism 2 by opening and closing the three shutters 66, 67, 68 at a predetermined timing. Therefore, it can be used as a light source unit of a field sequential type liquid crystal projector without using a color wheel, and according to such a light source unit, since light absorption in the optical path is small, a high brightness color image can be obtained. Can be displayed.
Further, when configuring an outdoor display panel that requires high luminance, a high-pressure mercury lamp, a halogen lamp, or the like can be used as a light source.
Further, in this example, since the polarization direction of white light is aligned to P-polarized light or S-polarized light by the polarization conversion prism 69 (polarization conversion means), a liquid crystal panel is used as the shutters 66, 67, 68 (shutter means). be able to. If such a liquid crystal panel is used as the shutters 66, 67 and 68, it is easy to achieve synchronization.
[Application Example 1 for Liquid Crystal Projector of Embodiment 2]
The composite prisms 2 and 2 'according to the second embodiment and the modifications thereof can be mounted on a liquid crystal projector as described below.
FIG. 18 is an explanatory diagram of a liquid crystal projector using the composite prism according to the first modification of the second embodiment of the present invention. The liquid crystal projector shown in FIG. 18 uses a composite prism 2 according to a modification of the second embodiment as a light source. A polarizing plate 71 is disposed on the exit side of the composite prism 2 and further includes a polarization separation surface 72. A polarizing beam splitter 73 is arranged. A reflective liquid crystal light valve 74 is disposed so as to face the end surface of the polarization beam splitter 73, and a projection optical system 75 is disposed on the opposite end surface side.
In the liquid crystal projector configured as described above, red light LR, green light LG, and blue light LB are sequentially emitted from the composite prism 2, and only P-polarized light, for example, enters the polarization beam splitter 73 by the polarizing plate 71. The light that has entered the polarization beam splitter 73 is reflected by the polarization separation surface 72 toward the liquid crystal light valve 74, modulated by the liquid crystal light valve 74, and then travels toward the polarization separation surface 72 again. At that time, the S-polarized light passes through the polarization separation surface 72 and is enlarged and projected from the projection optical system 75.
In the meantime, in accordance with the timing when the LEDs 51, 52, 53 of each color are sequentially turned on, the liquid crystal light valve 74 drives each pixel and sequentially forms an image according to the color light. Therefore, a new type of field sequential type liquid crystal projector can be constructed, and according to this liquid crystal projector, a color image can be enlarged and projected from the projection optical system 75.
[Application Example 2 for Liquid Crystal Projector of Embodiment 2]
FIG. 19 is an explanatory diagram of another liquid crystal projector using the composite prism according to the first modification of the second embodiment of the present invention.
The liquid crystal projector shown in FIG. 19 includes a plurality of light source units 80 each including a composite prism 2 according to a modification of the second embodiment and a polarization conversion prism 83 (polarization conversion means) including two polarization separation prisms 81 and 82. , Which is arranged. Here, in the polarization conversion prism 83, a 1 / 2λ plate 88 is disposed between the polarization separation prisms 81 and 82. A polarizing beam splitter 86 having a polarization separation surface 85 is disposed adjacent to the plurality of light source units 80, and a reflective liquid crystal light valve 89 is disposed on the opposite side. FIG. 19 shows a state in which red light LR is emitted.
In the liquid crystal projector configured as described above, the red light LR, the green light LG, and the blue light LB are sequentially emitted from the composite prism 2 to the first polarization separation prism 81 of the polarization conversion prism 83. Of the color light emitted from the composite prism 2, for example, the P-polarized light component passes through the polarization separation surface 85 of the polarization beam splitter 86 after passing through the polarization separation surface of the first polarization separation prism 81, Head to the liquid crystal light valve 89. Then, after being modulated by the liquid crystal light valve 74, the light travels toward the polarization separation surface 72 again. At that time, the S-polarized light is reflected by the polarization separation surface 85 and enlarged and projected from a projection optical system (not shown).
Of the colored light emitted from the composite prism 2, the S-polarized light component is reflected by the polarization separation surface of the first polarization separation prism 81 and converted into P-polarized light by the ½λ plate 88. Thereafter, the light enters the second polarization separation prism 82. Then, after being reflected by the polarization separation surface of the second polarization separation prism 82 and entering the polarization beam splitter 86, the light passes through the polarization separation surface 85 and travels toward the liquid crystal light valve 89. Then, after being modulated by the liquid crystal light valve 89, the light travels again toward the polarization separation surface 85. At that time, the S-polarized light is reflected by the polarization separation surface 85 and enlarged and projected from a projection optical system (not shown).
Meanwhile, in accordance with the timing when the LEDs 51, 52, 53 of each color are sequentially turned on, in the liquid crystal light valve 89, each pixel is driven and images corresponding to the color lights are sequentially formed. Therefore, a color image is enlarged and projected from the projection optical system.
When configured in this way, there is an advantage that the use efficiency of light emitted from the LEDs 51, 52, and 53 is higher than that of a field sequential type liquid crystal projector using a conventional color filter.
[Example of use for direct view display device of embodiment 2]
FIG. 20 is an explanatory diagram of a direct-view type liquid crystal display device using the composite prism according to the first modification of the second embodiment of the present invention.
The liquid crystal display device shown in FIG. 20 is a direct view type display device using a transmissive or transflective liquid crystal panel 91. As the liquid crystal panel 91, for example, an active matrix liquid crystal panel using TFTs as pixel switching elements can be used.
In such a display device, a polarizing plate 92 is disposed on the display surface side, and an optical sheet 96 such as a diffusion plate and a light guide plate 93 are disposed on the back surface side. In addition, a plurality of light source units 80 described with reference to FIG. 19 are arranged on the side end portion of the light guide plate 93. The light source unit 80 includes the composite prism 2 according to the modification of the second embodiment, and the polarization unit. The polarization conversion prism 83 has a 1 / 2λ plate disposed between two polarization separation prisms.
In the display device configured as described above, similarly to the liquid crystal projector shown in FIG. 19, red light LR, green light LG, and blue light LB are sequentially emitted from the composite prism 2, and are guided through the polarization conversion prism 83 to the light guide plate 93. Is incident on. The light that has entered the light guide plate 93 enters the liquid crystal panel 91 while being repeatedly reflected in the light guide plate 93. Then, after being modulated by the liquid crystal panel 91, the light is emitted and a color image is displayed. In the meantime, in accordance with the timing when the LEDs of the respective colors are sequentially turned on, in the liquid crystal panel 91, the respective pixels are driven and images corresponding to the colored lights are sequentially formed. Therefore, these images are combined to display a color image.
The greatest feature of the display device configured as described above is that a color image is displayed without a color filter. Therefore, there is no decrease in light use efficiency due to the color filter. In the display device of this example, the light sources of the three primary colors emitted from the red LED 51, the green LED 52, and the blue LED 53 are converted into polarized light before entering the light guide plate 93. The liquid crystal panel 91 can be output as it is. Therefore, the brightness about three times that of the current level can be obtained, so that the user can see a clear image even when it is necessary to view the image outdoors like a mobile computer or a mobile phone.
[Other embodiments]
In the above embodiment, an example in which a liquid crystal light valve is used as a light valve of a projector has been described. However, according to the present invention, a projector using a micromirror device (DMD: Digital Micromirror Device) as a light valve is described. A compound prism may be used.
In the above embodiment, the example in which the composite prism according to the present invention is used for the projector and the direct-view display device has been described. However, the composite prism according to the present invention may be used for other display devices or other optical devices. Good.

  According to the present invention, unlike the X-cube, the ridge lines of the four prisms do not have to be aligned, so that the optical path synthesis or optical path can be improved in yield, cost, and reliability. A composite prism for separation can be provided. In addition, by using the composite prism according to the present invention, it is possible to improve image quality and design freedom in various display devices.

Claims (16)

A first selective reflection surface that selectively transmits at least light having a predetermined optical characteristic and reflects other light to a plurality of bonding surfaces formed by bonding the plurality of translucent members. And the second selective reflecting surface are formed in a direction intersecting each other without being parallel or orthogonal to each other,
A composite prism characterized in that at least three light paths having different wavelengths can be synthesized or separated by the first selective reflection surface and the second selective reflection surface. In Claim 1, each corner | angular part of the said 1st rectangular plane of the rectangular parallelepiped shape which consists of the 1st rectangular plane and 2nd rectangular plane which oppose is each set as a 1st corner | angular part, a 2nd corner | angular part, and 3rd A corner portion and a fourth corner portion, and each of the corner portions corresponding to the first corner portion, the second corner portion, the third corner portion, and the fourth corner portion in the second rectangular plane is a fifth portion. When the corner, the sixth corner, the seventh corner, and the eighth corner,
The first selective reflection surface is provided on a surface constituted by the first corner, the third corner, the seventh corner, and the fifth corner,
A composite prism comprising the second selective reflecting surface on a surface formed by the third corner, the fourth corner, the fifth corner, and the sixth corner. 3. The composite prism according to claim 2, wherein each of the first selective reflection surface and the second selective reflection surface is constituted by a polarization separation surface. 4. The display device according to claim 2, further comprising a plurality of electro-optical devices that respectively modulate the color lights emitted from the composite prism. In claim 1, comprising a plurality of joint surfaces parallel to each other, joining the plurality of columnar translucent members to form an angle of 45 ° to the incident surface,
The first selective reflection surface that selectively reflects light in a predetermined wavelength band on any one of the plurality of bonding surfaces,
The composite prism comprising the second selective reflection surface that selectively reflects light having a wavelength band different from that of the first selective reflection surface on any other bonding surface. A light source unit comprising a composite prism as defined in claim 5,
The composite prism has a first color light dichroic mirror that selectively reflects the first color light in the wavelength bands of the three primary colors of red, green, and blue as the first selective reflection surface; A second color light dichroic mirror that selectively reflects the second color light toward the first color light dichroic mirror as the second selective reflection surface, and the second color light dichroic mirror. A third color light reflecting surface disposed on the side opposite to the first color light dichroic mirror and reflecting third color light toward the second color light dichroic mirror;
A first color light source unit that emits the first color light toward the first dichroic mirror for color light is disposed;
A second color light source unit that emits the second color light toward the second dichroic mirror for color light is disposed;
A third color light source unit that emits the third color light toward the reflecting surface is disposed;
A light source unit, wherein light emission from the first color light source unit, the second color light source unit, and the third color light source unit to the composite prism is switched at a predetermined timing. A light source unit comprising a composite prism as defined in claim 5,
The composite prism has a first color light dichroic mirror that selectively reflects the first color light in the wavelength bands of the three primary colors of red, green, and blue as the first selective reflection surface; A second color light dichroic mirror that selectively reflects the second color light toward the first color light dichroic mirror as the second selective reflection surface;
A first color light source unit that emits the first color light toward the first dichroic mirror for color light is disposed;
A second color light source unit that emits the second color light toward the second dichroic mirror for color light is disposed;
A third color light source unit that emits third color light from the opposite side of the second color light dichroic mirror to the second color light dichroic mirror;
A light source unit, wherein light emission from the first color light source unit, the second color light source unit, and the third color light source unit to the composite prism is switched at a predetermined timing. In Claim 6 or 7, each of the first color light source unit, the second color light source unit, and the third color light source unit is a light emitting element that emits predetermined color light. ,
The first color light source unit, the second color light source unit, and the third color light source unit are each controlled to be turned on at a predetermined timing. In Claim 6 or 7, each of the first color light source unit, the second color light source unit, and the third color light source unit is obtained by color-dividing white light. Emit light of each color,
The timing at which each color light is incident on the composite prism is controlled between the first color light source unit, the second color light source unit, the third color light source unit, and the composite prism. A light source unit in which shutter means is disposed. A light source unit comprising two compound prisms as defined in claim 5,
Of the two composite prisms, the first composite prism selectively reflects the first color light in the wavelength bands of the three primary colors of red, green, and blue as the first selective reflection surface. A dichroic mirror for one color light, a second dichroic mirror for color light that selectively reflects second color light toward the first dichroic mirror for color light as the second selective reflection surface, A third color light reflecting surface disposed on the opposite side of the first color light dichroic mirror to reflect the third color light toward the second color light dichroic mirror; With
The second composite prism includes a first color light reflection surface that reflects the first color light toward the first color light dichroic mirror of the first composite prism, and the first selective reflection surface. A second color light dichroic mirror that selectively reflects the second color light toward the second color light dichroic mirror of the first composite prism; and a third color light as the second selective reflection surface. A third color light dichroic mirror that selectively reflects toward the third color light reflecting surface of the first composite prism;
And a white light source that emits white light toward the third composite light dichroic mirror of the second composite prism with respect to the second composite prism,
Between the first composite prism and the second composite prism, shutter means for controlling the timing at which each color light enters the first composite prism from the second composite prism is disposed. A light source unit. In Claim 9 or 10, comprising a polarization conversion means for aligning the polarization direction of the white light,
A liquid crystal panel is used as the shutter means. A display device comprising the light source unit as defined in any one of claims 5 to 11. The display device according to claim 12, wherein a plurality of the composite prisms are arranged in a matrix. 13. The display device according to claim 12, further comprising an electro-optical device that sequentially modulates the color light emitted from the light source unit and sequentially generates color images corresponding to the color light. . 15. The display device according to claim 14, wherein the light source unit includes polarization conversion means for aligning the polarization direction of the color light emitted toward the electro-optical device. 16. A projection display device according to claim 14, further comprising a projection optical system that projects images of each color sequentially formed by the electro-optical device.

Images