Projector

Abstract

To improve utilization efficiency of light emitted from a light source of a projector.SOLUTION: A projector P includes: a first light source 1 that emits first light; a first light guide element 2 that has a first incident end 21 on which the first light emitted from the first light source 1 is incident, and a first emission end 22 from which the first light incident from the first incident end 21 is emitted, and reflects the first light incident from the first incident end 21 by an inner surface; a first polarizing element 8 that is arranged inside the first light guide element 2, reflects a first polarization component, and transmits a second polarization component; a first light modulation element 4 that modulates the first light emitted from the first emission end 22 on the basis of image information; and a projection optical system 5 that projects the light emitted from the first light modulation element 4. The first polarizing element 8 is inclined with respect to an axis L perpendicular to an incident surface 21a of the first incident end 21 in the first light guide element 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a projector. [Background technology]

[0002] Patent Document 1 describes a projector that uses a light modulation element to form image light and then enlarges and projects it using a projection lens. A transparent block made of acrylic resin or the like and a condenser lens are placed between the light source and the light modulation element. The light source is an LED. The cross-sectional area of ​​the block at its output end is larger than that of its input end, and the illuminance distribution of the light emitted from the light source is homogenized before it enters the condenser lens. The condenser lens forms an image of the incident light source at the entrance pupil position of the projection lens. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-180962 Summary of the Invention [Problem to be solved by the invention]

[0004] In projectors, light with uniform polarization is incident on a light modulation element, so light sources that emit unpolarized light have the problem of poor light utilization efficiency, with nearly half of the emitted light beam being unable to be used for image formation. [Means for solving the problem]

[0005] In order to solve the above problem, the projector of the present invention includes a first light source that emits first light, a first incident end into which the first light emitted from the first light source is incident and a first exit end from which the first light incident from the first incident end is emitted, and includes a first light guide element that reflects the first light incident from the first incident end on an inner surface thereof, a first polarization element that is disposed inside the first light guide element and reflects a first polarization component and transmits a second polarization component, a first light modulation element that modulates the first light emitted from the first exit end based on image information, and a projection optical system that projects the light emitted from the first light modulation element, wherein the first polarization element is tilted with respect to an axis perpendicular to the incident surface of the first incident end of the first light guide element. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 2 is an explanatory diagram showing a main part of the projector of the first embodiment. [Figure 2] 4 is an explanatory diagram showing a path of a first light that has entered a first light guide element. FIG. [Figure 3] FIG. 10 is an explanatory diagram showing a main part of a projector according to a modified example. [Figure 4] 10 is a table showing values ​​of the utilization efficiency of the first light when the angle of the first polarizing element is different. [Figure 5] FIG. 10 is an explanatory diagram showing the main parts of a projector according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] DETAILED DESCRIPTION OF THE INVENTION Hereinafter, a projector according to an embodiment of the invention will be described with reference to the drawings.

[0008] (Embodiment 1) 1 is an explanatory diagram showing the main parts of a projector P of embodiment 1. As shown in FIG. 1, the projector P projects image light onto a screen S. The projector P includes a first light source 1, a first light guide element 2, a first collimating element 3, a first light modulation element 4, a projection optical system 5, a control unit 6, and a polarizing plate 7. In this embodiment, the first light source 1, the first light guide element 2, the first collimating element 3, the first light modulation element 4, the polarizing plate 7, and the projection optical system 5 are arranged in this order along an axis L described below.

[0009] The first light source 1 emits a first light. The first light is unpolarized light. The first light source 1 is formed, for example, from an ultra-high pressure mercury lamp, an LED, a laser light source, or a light source using a phosphor. In this embodiment, the first light source 1 is an LED. As shown in FIG. 1, the first light source 1 includes an LED element 11 that emits the first light and a substrate 12 on which the LED element 11 is disposed.

[0010] The first light guide element 2 internally reflects and emits the first light incident from the first light source 1. Note that internal reflection means that the first light is reflected on the inner surface of the first light guide element 2. The first light guide element 2 aligns the polarization direction of the first light and emits the first light. In other words, the first light guide element 2 converts at least a part of the first polarization component of the first light into a second polarization component and emits the first light. Therefore, the first light emitted from the first light guide element 2 has an increased second polarization component compared to when the first light entered the first light guide element 2.

[0011] The first collimating element 3 collimates the first light emitted from the first light guide element 2 and emits the collimated light. The first light modulation element 4 modulates the first light, the polarization direction of which has been aligned by the first light guide element 2, to generate image light. A polarizing plate 7 disposed on the exit side of the first light modulation element 4 transmits a first polarization component contained in the image light. The projection optical system 5 enlarges the image light and projects it onto the screen S. Note that a polarizing plate that transmits a second polarization component may be added to the entrance side of the first light modulation element 4.

[0012] For example, the first polarized light component is an S polarized light component, and the second polarized light component is a P polarized light component. In this case, the polarizing plate 7 transmits the S polarized light component contained in the image light. Note that the first polarized light component may be a P polarized light component, and the second polarized light component may be an S polarized light component.

[0013] The first light modulation element 4 is, for example, a liquid crystal panel. The control unit 6 operates the first light modulation element 4 based on an external image signal such as a video signal. The projector P is a single-panel projector that generates image light using a single liquid crystal panel. The first light is light of a first wavelength band. For example, the first light is white light containing red, green, and blue light. The first light modulation element 4 has pixels corresponding to the respective colors of light. As a result, the first light modulation element 4 modulates the color light corresponding to each pixel to form full-color image light. Note that the first light may be light of a wavelength band different from that of white light.

[0014] (First light guide element) FIG. 2 is an enlarged view of the first light guide element 2. As shown in FIGS. 1 and 2, the first light guide element 2 has a first incident end 21 into which the first light emitted from the first light source 1 is incident, and a first emitting end 22, which is the end opposite to the first incident end 21. The first light guide element 2 internally reflects the first light incident from the first incident end 21 and emits it from the first emitting end 22. The axis L shown in FIGS. 1 and 2 is a straight line that passes through the center of the incident surface 21a of the first incident end 21 and is perpendicular to the incident surface 21a. In this embodiment, the substrate surface 12a on which the LED elements 11 of the first light source 1 are arranged is perpendicular to the axis L. In this embodiment, the axis L coincides with the central axis of the first light guide element 2. Note that the axis L does not have to coincide with the central axis of the first light guide element 2.

[0015] The first light guide element 2 is a cylindrical reflector having openings at the first entrance end 21 and the first exit end 22. The inner surface of the first light guide element 2 is a reflective surface that reflects the first light. As shown in FIG. 1 , the opening area of ​​the first light guide element 2 is larger at the first exit end 22 than at the first entrance end 21. The inner surface of the first light guide element 2 is an inclined surface with a constant inclination angle with respect to the axis L. The cross-sectional area of ​​the first light guide element 2 cut along a plane perpendicular to the axis L increases from the first entrance end 21 toward the first exit end 22. The cross-sectional shape of the first light guide element 2 cut along a plane perpendicular to the axis L is not particularly limited. For example, it may be a polygon such as a rectangle, or a circle. The first light guide element 2 may be formed from a single member or may be formed by combining multiple base materials. When the first light guide element 2 is formed from multiple base materials, the inner surface of the first light guide element 2 is formed by the facing surfaces of the multiple base materials.

[0016] In this specification, the plane having the opening edge of the first incident end 21 as its outer periphery is referred to as the incident surface 21a of the first incident end 21. For example, if the opening of the first incident end 21 is a polygon such as a rectangle, the plane formed by multiple sides, such as four sides, surrounding the opening is referred to as the incident surface 21a. Similarly, the exit surface 22a of the first exit end 22 is a plane having the opening edge of the first exit end 22 as its outer periphery. In this embodiment, the incident surface 21a and the exit surface 22a of the first light guide element 2 are parallel to each other. Note that the incident surface 21a and the exit surface 22a do not have to be parallel to each other.

[0017] The first light guide element 2 has a first polarizing element 8 and a first retardation section 9 disposed therein. The first polarizing element 8 is a polarization separation element that reflects a first polarized light component and transmits a second polarized light component. As shown in FIGS. 1 and 2, the first polarizing element 8 extends from the first incident end 21 side to the first exit end 22 side. As shown in FIG. 2, the first polarizing element 8 is inclined in a direction that forms an angle θ with respect to an axis L that is perpendicular to the incident surface 21a. Therefore, the first light incident from the incident surface 21a illuminates one surface 8a of the first polarizing element 8.

[0018] As shown in FIGS. 1 and 2 , the first polarizing element 8 divides the internal space of the first light guide element 2 into a first space R1 and a second space R2. The first space R1 is a space surrounded by the first incident end 21, one surface 8a of the first polarizing element 8, and the first inner surface region 23 of the first light guide element 2. The inner surface of the first light guide element 2 includes the first inner surface region 23 and a second inner surface region 24 facing the first inner surface region 23. The second space R2 is a space surrounded by the first exit end 22, the other surface 8b of the first polarizing element 8, and the second inner surface region 24 of the first light guide element 2. The first polarizing element 8 is inclined in a direction toward the second inner surface region 24 as it approaches the first incident end 21, and in a direction toward the first inner surface region 23 as it approaches the first exit end 22.

[0019] The first retardation section 9 is disposed in the first space R1. The first retardation section 9 changes the polarization component of the first light. In this embodiment, the first retardation section 9 changes the polarization component reflected by the first polarizing element 8 into a polarization component transmitted through the first polarizing element 8. That is, the first retardation section 9 changes the first polarization component into a second polarization component. The first retardation section 9 is, for example, a λ / 4 plate. The first retardation section 9 extends along the first inner surface region 23. In this embodiment, the first retardation section 9 is disposed so as to be in surface contact with the first inner surface region 23. For example, the first retardation section 9 is in the form of a film and is fixed to the first inner surface region 23 with an adhesive. The first retardation section 9 is disposed in a range in the first inner surface region 23 where the first polarization component reflected by one surface 8a of the first polarizing element 8 is incident.

[0020] In FIG. 2, of the polarization components of the first light, the first polarization component is indicated by a solid arrow S, and the second polarization component is indicated by a dashed arrow P. As shown in FIG. 2, the first light enters the first space R1 from the first incident end 21. When the first light entering the first space R1 reaches the first polarizing element 8, the first polarization component indicated by the solid arrow S is reflected by the first polarizing element 8, and the second polarization component indicated by the dashed arrow P is transmitted through the first polarizing element 8. The first polarization component reflected by the first polarizing element 8 is reflected by the first inner surface region 23. At this time, the first polarization component transmits through the first retardation unit 9 once immediately before and once immediately after reflection. As a result, at least a portion of the first polarization component is converted into the second polarization component, which then transmits through the first polarizing element 8.

[0021] The end of the first polarizing element 8 on the first incident end 21 side may or may not be connected to the second inner surface region 24 or the opening edge of the first incident end 21. In this embodiment, as shown in FIGS. 1 and 2 , the end of the first polarizing element 8 on the first incident end 21 side is separated from the second inner surface region 24 of the first light guide element 2 and the opening edge of the first incident end 21. Therefore, most of the first light incident from the first incident end 21 enters the first space R1 and is confined within the first space R1, but some of the first light incident from the first incident end 21 passes through the gap between the first polarizing element 8 and the second inner surface region 24 and enters the second space R2. Therefore, some of the first polarization component of the first light enters the second space R2.

[0022] When the end of the first polarizing element 8 on the first incident end 21 side is configured to be connected to the second inner surface area 24 or the opening edge of the first incident end 21, the first polarization component of the first light incident from the first incident end 21 is entirely reflected by the first polarizing element 8. This improves the efficiency of polarization conversion.

[0023] Similarly, the end of the first polarizing element 8 on the first exit end 22 side may or may not be connected to the first inner surface region 23 or the opening edge of the first exit end 22. In this embodiment, as shown in Figures 1 and 2, the end of the first polarizing element 8 on the first exit end 22 side is separated from the first inner surface region 23 and the opening edge of the first exit end 22.

[0024] (Effects of the first embodiment) The projector P of the first embodiment includes a first light source 1 that emits first light, a first incident end 21 into which the first light emitted from the first light source 1 enters, and a first exit end 22 from which the first light incident from the first incident end 21 exits, a first light guide element 2 that reflects the first light incident from the first incident end 21 on its inner surface, a first polarizing element 8 that is disposed inside the first light guide element 2 and reflects a first polarized component and transmits a second polarized component, a first light modulation element 4 that modulates the first light emitted from the first exit end 22 based on image information, and a projection optical system 5 that projects the light emitted from the first light modulation element 4. The first polarizing element 8 is inclined with respect to an axis L that is perpendicular to the incident surface 21a of the first incident end 21 of the first light guide element 2.

[0025] The projector P of the first embodiment causes the first light emitted from the first light source 1 to be incident on the first polarizing element 8, which reflects the first polarization component and transmits the second polarization component, thereby increasing the polarization components that can be used to form image light and emitting the increased polarization components from the first light guide element 2. This improves the utilization efficiency of the first light emitted from the first light source 1. Furthermore, because the polarization conversion is performed using the first light guide element 2, there is no need to ensure space for placing an additional element between the first light source 1 and the first light modulation element 4. This makes it possible to avoid the projector P becoming larger.

[0026] The first light guide element 2 of the first embodiment has therein a first phase difference section 9 that changes the polarization component of the first light. In this way, by disposing an element that performs polarization conversion inside the first light guide element 2, the efficiency of polarization conversion inside the first light guide element 2 is improved. Therefore, it is possible to improve the utilization efficiency of the first light emitted from the first light source 1. Furthermore, because the polarization direction is aligned inside the first light guide element 2 before being emitted, it is possible to omit the polarizing plate that is conventionally arranged on the incident side of the first light modulation element 4. Therefore, it is possible to reduce the number of components and make the projector P more compact.

[0027] The inner surface of the first light guide element 2 includes a first inner surface region 23 and a second inner surface region 24 different from the first inner surface region 23. The first polarizing element 8 defines a first space R1 surrounded by the first incident end 21, the first inner surface region 23, and the first polarizing element 8, and a second space R2 surrounded by the first exit end 22, the second inner surface region 24, and the first polarizing element 8. In this way, the first polarization component that cannot pass through the first polarizing element 8 can be confined in the first space R1. Therefore, polarization conversion can be performed efficiently.

[0028] In the first embodiment, the first phase difference unit 9 is disposed in the first space R1. By disposing an element that performs polarization conversion in the first space R1 in this manner, the efficiency of polarization conversion in the first space R1 is improved. Therefore, the utilization efficiency of the first light emitted from the first light source 1 is improved.

[0029] In the first embodiment, the first phase difference portion 9 is in surface contact with the first inner surface region 23. For example, the first phase difference portion 9 is preferably fixed to the first inner surface region 23 by adhesion. In this way, the first phase difference portion 9 can be stably held within the first light guide element 2. Therefore, the physical durability of the first light guide element 2 is improved.

[0030] In the first embodiment, the first retardation portion is a λ / 4 plate. Therefore, polarization conversion can be performed simply by fixing it to the inner surface of the first light guide element 2 and transmitting light before and after reflection. Therefore, polarization conversion can be performed efficiently with a compact structure.

[0031] (Variation) Fig. 3 is an explanatory diagram showing the main parts of a projector P1 of a modified example. Hereinafter, the same parts as those of the first embodiment will be assigned the same reference numerals and explanations thereof will be omitted, and only different parts will be explained. As shown in Fig. 3, the projector P1 includes a first light source 1, a first light guide element 2A, a first collimating element 3, a first light modulation element 4, a projection optical system 5, a control unit 6, and a polarizing plate 7. The first light guide element 2A of the modified example differs from the first light guide element 2 of the first embodiment in that it does not include a first phase difference section 9.

[0032] Similar to the first light guide element 2 of the first embodiment, the first light guide element 2A of the modified example has a first polarizing element 8 disposed therein. The first polarizing element 8 is tilted with respect to the axis L and separates a first space R1 and a second space R2. When the first light is incident, a first polarized component that cannot be transmitted through the first polarizing element 8 is confined in the first space R1. The first polarized component is reflected between the first inner surface region 23 and the first polarizing element 8. A second polarized component included in the reflected component is transmitted through the first polarizing element 8. Therefore, the polarized components that can be used to form image light can be increased and emitted from the first light guide element 2. This improves the utilization efficiency of the first light emitted from the first light source 1.

[0033] (simulation) FIG. 4 is a table showing values ​​of the utilization efficiency of the first light when the angle of the first polarizing element 8 is different. For each of the first light guide element 2 of the first embodiment and the first light guide element 2A of the modified example, the utilization efficiency of the first light was simulated when the angle θ between the first polarizing element 8 and the axis L was set to 30 degrees, 60 degrees, and 90 degrees. As a comparative example, the utilization efficiency of the first light was also simulated when the first polarizing element 8 was not disposed inside. The shapes of the first light guide elements 2 and 2A used in the simulation were the shapes in which the inclination of the inner surface of the first light guide element 2 and 2A, i.e., the angle θ1 shown in FIG. 2, was 66.6 degrees and the shape in which the angle θ1 was 75.9 degrees. The simulation result when the angle θ1 was 66.6 degrees is shown in FIG. 4.

[0034] The simulation results for the first embodiment (with the first retardation section 9) showed that the utilization efficiency of the first light was 47% in the comparative example (without the first polarizing element 8), while it was 82% at θ=30 degrees, 77% at θ=60 degrees, and 72% at θ=90 degrees. Therefore, in the first embodiment, the range of the peak angle at which the utilization efficiency of the first light is maximized is 0 degrees<θ<60 degrees. Therefore, by setting the angle θ of the first polarizing element 8 within the range of 0 degrees<θ<60 degrees, it is possible to improve the utilization efficiency of the first light.

[0035] The simulation results for the modified example (without the first retardation section 9) showed that the utilization efficiency of the first light was 49% in the comparative example (without the first polarizing element 8), while it was 59% at θ=30 degrees, 77% at θ=60 degrees, and 75% at θ=90 degrees. Therefore, in the modified example, the range of the peak angle at which the utilization efficiency of the first light is maximized is 30 degrees<θ<90 degrees. Therefore, by setting the angle θ of the first polarizing element 8 within the range of 30 degrees<θ<90 degrees, it is possible to improve the utilization efficiency of the first light.

[0036] In the simulation, the in-plane illuminance distribution of the first light emitted from the first light guide elements 2 and 2A was also obtained. As a result, the first light guide element 2 with the first phase difference section 9 had low in-plane illuminance uniformity when θ = 60 degrees and θ = 90 degrees. The first light guide element 2A without the first phase difference section 9 had low in-plane illuminance uniformity when θ = 90 degrees. Therefore, by setting the range of θ as described above, it is possible to improve the utilization efficiency of the first light and to uniformize the in-plane illuminance distribution of the emitted first light. Note that when the angle θ1 was 75.9 degrees, similar results were obtained as when it was 66.6 degrees.

[0037] (Other variations) The first light guide element 2 of the first embodiment and the first light guide element 2A of the modified example are not limited to the shapes shown in Figs. 1 and 3. For example, the inner surface of the first light guide element 2 does not have to be a flat surface with a constant inclination angle with respect to the axis L, and may be a curved surface. Furthermore, the incident surface 21a and the exit surface 22a do not have to be parallel. For example, the first light guide element 2 may be configured to emit light in a direction intersecting the axis L perpendicular to the incident surface 21a.

[0038] The first light guide element 2 of the first embodiment and the first light guide element 2A of the modified example are not limited to cylindrical reflectors. For example, the first light guide element 2 may be a block made of a light-transmitting material, and the outer peripheral surface of the block may be provided with a reflective layer that reflects light inward, thereby internally reflecting light incident from the first incident end 21. In this case, the incident surface 21a and the exit surface 22a are end surfaces of the block.

[0039] (Embodiment 2) 5 is an explanatory diagram showing a main part of a projector P2 according to a second embodiment. As shown in FIG. 5, the projector P2 causes light from three light sources to pass through light guide elements and enter three light modulation elements, and combines and projects the three image lights. The projector P2 includes a first light source 1R, a first light guide element 2R, a first collimating element 3R, a first light modulation element 4R, and a polarizing plate 7R; a second light source 1G, a second light guide element 2G, a second collimating element 3G, a second light modulation element 4G, and a polarizing plate 7G; a third light source 1B, a third light guide element 2B, a third collimating element 3B, a third light modulation element 4B, and a polarizing plate 7B; a light combining element 10; a projection optical system 5; and a control unit (not shown).

[0040] The first light source 1R emits a first light. The second light source 1G emits a second light different from the first light. The third light source 1B emits a third light different from the first light and the second light. The first light, second light, and third light are unpolarized light. The first light is light in a first wavelength band. The second light is light in a second wavelength band. The third light is light in a third wavelength band. For example, the first light is red light. The wavelength band of red light is, for example, 600 nm to 680 nm. The second light is green light. The wavelength band of green light is, for example, 500 nm to 600 nm. The third light is blue light. The wavelength band of blue light is, for example, 420 nm to 500 nm.

[0041] The first light source 1R, the second light source 1G, and the third light source 1B are configured with an ultra-high pressure mercury lamp, an LED, a laser light source, a light source using a phosphor, etc., as in the first embodiment. In this embodiment, the first light source 1R, the second light source 1G, and the third light source 1B are all LEDs.

[0042] The first light guide element 2R, the second light guide element 2G, and the third light guide element 2B can be configured similarly to the first light guide element 2 of the first embodiment or the first light guide element 2A of the modified example. In the embodiment shown in Fig. 5, the first light guide element 2R, the second light guide element 2G, and the third light guide element 2B are all configured similarly to the first light guide element 2A of the modified example. That is, the first light guide element 2R, the second light guide element 2G, and the third light guide element 2B all internally reflect incident light and have a polarization separation element disposed therein that reflects a first polarization component and transmits a second polarization component.

[0043] As shown in FIG. 5, a first polarizing element 8R is disposed inside the first light guide element 2R. The first polarizing element 8R is inclined with respect to an axis LR perpendicular to the incident surface of the first incident end 21R of the first light guide element 2R. A second polarizing element 8G is disposed inside the second light guide element 2G. The second polarizing element 8G is inclined with respect to an axis LG perpendicular to the incident surface of the second incident end 21G of the second light guide element 2G. A third polarizing element 8B is disposed inside the third light guide element 2B. The third polarizing element 8B is inclined with respect to an axis LB perpendicular to the incident surface of the third incident end 21B of the third light guide element 2B.

[0044] The first polarizing element 8R is a polarization separation element that reflects the first polarization component and transmits the second polarization component. The second polarizing element 8G is a polarization separation element that reflects the third polarization component and transmits the fourth polarization component. The third polarizing element 8B is a polarization separation element that reflects the fifth polarization component and transmits the sixth polarization component. The third polarization component and the fifth polarization component may be the same polarization component as the first polarization component or may be different. The fourth polarization component and the sixth polarization component may be the same polarization component as the second polarization component or may be different. The definitions of the axis LR perpendicular to the incident plane of the first incident end 21R, the axis LG perpendicular to the incident plane of the second incident end 21G, and the axis LB perpendicular to the incident plane of the third incident end 21B are the same as the definition of the axis L in the first embodiment.

[0045] The angle θr between the first polarizing element 8R and the axis LR, the angle θg between the second polarizing element 8G and the axis LG, and the angle θb between the third polarizing element 8B and the axis LB may be the same or different. For example, it is preferable that θr, θg, and θb are each greater than 30 degrees and less than 90 degrees. Within this range, there are peak angles at which the utilization efficiencies of the first, second, and third light are maximized.

[0046] A control unit (not shown) operates the first light modulation element 4R, the second light modulation element 4G, and the third light modulation element 4B based on an external image signal such as a video signal. The first light modulation element 4R modulates the first light, the polarization direction of which has been aligned by the first light guide element 2R, to generate image light of a first wavelength band. The second light modulation element 4G modulates the second light, the polarization direction of which has been aligned by the second light guide element 2G, to generate image light of a second wavelength band. The third light modulation element 4B modulates the third light, the polarization direction of which has been aligned by the third light guide element 2G, to generate image light of a third wavelength band. The first polarization components of the three image lights with different wavelength bands pass through polarizers 7R, 7G, and 7B and enter the light combining element 10 from different directions. The projector P2 projects the full-color image light emitted from the light combining element 10 onto a screen S.

[0047] (Effects of the second embodiment) The projector P2 of the second embodiment includes a first light source 1R that emits first light, a first incident end 21R into which the first light emitted from the first light source 1R enters and a first exit end 22R from which the first light incident from the first incident end 21R exits, a first light guide element 2R that reflects the first light incident from the first incident end 21R on its inner surface, a first polarizing element 8R that is disposed inside the first light guide element 2R and reflects a first polarized component and transmits a second polarized component, a first light modulation element 4R that modulates the first light emitted from the first exit end 22R based on image information, and a projection optical system 5 that projects the light emitted from the first light modulation element 4R. The first polarizing element 8R is inclined with respect to an axis LR that is perpendicular to the incident surface of the first incident end 21R of the first light guide element 2R.

[0048] In addition to the above, the projector P2 of the second embodiment further includes a second light source 1G that emits second light, a second light guide element 2G that includes a second incident end 21G into which the second light emitted from the second light source 1G is incident and a second exit end 22G from which the second light incident from the second incident end 21G is emitted and that internally reflects the second light incident from the second incident end 21G, a second polarizing element 8G that is disposed inside the second light guide element 2G and that reflects the third polarized component and transmits the fourth polarized component, a second light modulation element 4G that modulates the second light emitted from the second exit end 22G based on image information, and a projection optical system 5 that projects the light emitted from the second light modulation element 4G. The second polarizing element 8G is inclined with respect to an axis LG that is perpendicular to the incident surface of the second incident end 21G of the second light guide element 2G.

[0049] The projector P2 of the second embodiment increases and emits polarized components that can be used to form image light inside the first light guide element 2R and the second light guide element 2G, by using a first polarizing element 8R that reflects the first polarized component and transmits the second polarized component, and a second polarizing element 8G that reflects the third polarized component and transmits the fourth polarized component. Therefore, the utilization efficiency of the first light emitted from the first light source 1R and the utilization efficiency of the second light emitted from the second light source 1G are improved, and it is possible to avoid an increase in the size of the projector P2.

[0050] In addition to the above, the projector P2 of the second embodiment further includes a third light source 1B that emits third light, a third incident end 21B into which the third light emitted from the third light source 1B is incident and a third exit end 22B from which the third light incident from the third incident end 21B is emitted, a third light guide element 2B that internally reflects the third light incident from the third incident end 21B, a third polarizing element 8B that is disposed inside the third light guide element 2B and that reflects the fifth polarized component and transmits the sixth polarized component, a third light modulation element 4B that modulates the third light emitted from the third exit end 22B based on image information, and a projection optical system 5 that projects the light emitted from the third light modulation element 4B. The third polarizing element 8B is inclined with respect to an axis LB that is perpendicular to the incident surface of the third incident end 21B of the third light guide element 2B.

[0051] The projector P2 of the second embodiment includes not only the first light guide element 2R and the second light guide element 2G, but also the third light guide element 2B, and a third polarizing element 8B having a polarization separation function therein. This improves the utilization efficiency of the third light emitted from the third light source 1B, and prevents the projector P2 from becoming larger.

[0052] At least one of the first light guide element 2R, the second light guide element 2G, and the third light guide element 2B may not have a polarization separation element therein.

[0053] In the projector P2 of the second embodiment, it is preferable that the first light guide element 2R, the second light guide element 2G, and the third light guide element 2B each have an element similar to the first phase difference section 9 of the first embodiment, i.e., a polarization conversion element such as a λ / 4 plate that converts the first polarization component into the second polarization component, disposed therein. This improves the efficiency of polarization conversion within each light guide element. This can improve the utilization efficiency of the first light emitted from the first light source 1. When a polarization conversion element such as a λ / 4 plate is disposed within each light guide element, it is preferable that θr, θg, and θb are each greater than 0 degrees and less than 60 degrees. This can improve the utilization efficiency of the first light, the second light, and the third light.

[0054] Summary of the Disclosure A summary of this disclosure is provided below.

[0055] (Appendix 1) a first light source that emits a first light; a first light guiding element including a first incident end into which the first light emitted from the first light source is incident and a first emitting end from which the first light incident from the first incident end is emitted, the first light guiding element reflecting the first light incident from the first incident end on an inner surface; a first polarizing element disposed inside the first light guide element, which reflects a first polarized component and transmits a second polarized component; a first light modulation element that modulates the first light emitted from the first emission end based on image information; a projection optical system that projects the light emitted from the first light modulation element, The projector, wherein the first polarizing element is tilted with respect to an axis perpendicular to an incident surface of the first incident end of the first light guide element.

[0056] According to Supplementary Note 1, it is possible to convert the polarization components not used for forming image light in the first light guide element into polarization components used for forming image light and emit the converted light. Therefore, it is possible to emit a large amount of effective light, improving the utilization efficiency of the first light emitted from the first light source 1. Furthermore, because the polarization conversion is performed using the first light guide element 2, there is no need to secure space for placing an additional element between the first light source 1 and the first light modulation element 4. This prevents the projector from becoming larger. Furthermore, because the polarization direction is aligned inside the first light guide element 2 and emitted, if a polarizing plate is not placed on the incident side of the first light modulation element 4, it is possible to reduce the number of components and achieve a more compact projector.

[0057] (Appendix 2) 2. The projector according to claim 1, wherein the first light guide element has therein a first phase difference section that changes the polarization component of the first light.

[0058] Supplementary Note 2 improves the efficiency of polarization conversion inside the first light guide element, thereby improving the utilization efficiency of the first light emitted from the first light source 1.

[0059] (Appendix 3) an inner surface of the first light guide element includes a first inner surface region and a second inner surface region different from the first inner surface region; The projector described in Appendix 2, characterized in that the first polarizing element divides a first space surrounded by the first incident end, the first inner surface area, and the first polarizing element, and a second space surrounded by the first exit end, the second inner surface area, and the first polarizing element.

[0060] According to Supplementary Note 3, the first polarization component that cannot pass through the first polarizing element can be confined in the first space. Therefore, polarization conversion can be performed efficiently, and the utilization efficiency of the first light emitted from the first light source 1 is improved.

[0061] (Appendix 4) The projector described in Supplementary Note 3, wherein the first phase difference section is disposed in the first space.

[0062] According to Supplementary Note 4, polarization conversion can be performed in the first space that the first polarization component is confined in. Therefore, the efficiency of polarization conversion is improved, and the utilization efficiency of the first light emitted from the first light source 1 is improved.

[0063] (Appendix 5) The projector described in Supplementary Note 4, wherein the first phase difference section is in surface contact with the first inner surface area.

[0064] According to Supplementary Note 5, the first phase difference portion 9 can be stably held within the first light guide element 2. Therefore, the physical durability of the first light guide element 2 is improved.

[0065] (Appendix 6) The projector according to any one of Supplementary Note 2 to Supplementary Note 5, wherein the first retardation section is a λ / 4 plate.

[0066] According to Supplementary Note 6, polarization conversion can be performed efficiently by simply transmitting light.

[0067] (Appendix 7) When the angle between the line perpendicular to the incident plane and the first polarizing element is θ, 3. The projector according to claim 2, wherein 0 degrees<θ<60 degrees.

[0068] According to Supplementary Note 7, polarization conversion can be performed efficiently. Also, the in-plane illuminance distribution of the first light emitted from the first polarizing element can be made uniform.

[0069] (Appendix 8) When the angle between the line perpendicular to the incident plane and the first polarizing element is θ, 2. The projector according to claim 1, wherein 30 degrees<θ<90 degrees.

[0070] According to Supplementary Note 8, polarization conversion can be performed efficiently. Also, the in-plane illuminance distribution of the first light emitted from the first polarizing element can be made uniform.

[0071] (Appendix 9) a second light source that emits second light having a wavelength band different from that of the first light; a second light guiding element including a second incident end into which the second light emitted from the second light source is incident and a second emitting end through which the second light incident from the second incident end is emitted, the second light guiding element reflecting the second light incident from the second incident end on an inner surface; a second polarizing element disposed inside the second light guide element and configured to reflect the third polarized light component and transmit the fourth polarized light component; a second light modulation element that modulates the second light emitted from the second emission end of the second light guide element based on image information; a light combining element that combines the light emitted from the first light modulation element and the light emitted from the second light modulation element and emits the combined light toward the projection optical system, The projector described in Supplementary Note 1, wherein the second polarizing element is tilted with respect to an axis perpendicular to the incident surface of the second incident end of the second light guide element.

[0072] According to Supplementary Note 9, in the first light guide element and the second light guide element, polarized light components not used for forming image light can be converted into polarized light components used for forming image light and then emitted. Therefore, a large amount of effective light can be emitted, improving the utilization efficiency of the first light emitted from the first light source and improving the utilization efficiency of the second light emitted from the second light source. Furthermore, because polarization conversion is performed using the first light guide element and the second light guide element, it is possible to avoid an increase in the size of the projector. [Explanation of symbols]

[0073] 1, 1R...first light source, 1G...second light source, 1B...third light source, 2, 2A, 2R...first light guide element, 2G...second light guide element, 2B...third light guide element, 3, 3R...first collimating element, 3G...second collimating element, 3B...third collimating element, 4, 4R...first light modulation element, 4G...second light modulation element, 4B...third light modulation element, 5...projection optical system, 6...controller, 7, 7R, 7G, 7B...polarizing plate, 8, 8R...first polarizing element, 8G...second polarizing element, 8B...third polarizing element, 8a...one side, 8b ...Other surface, 9...First retardation part, 10...Photosynthesis element, 11...LED element, 12...Substrate, 12a...Substrate surface, 21, 21R...First incidence end, 21G...Second incidence end, 21B...Third incidence end, 21a...Incidence surface, 22, 22R...First emission end, 2 2G...second injection end, 22B...third injection end, 22a...injection surface, 23...first inner surface area, 24...second inner surface area, L, LB, LG, LR...axis line, P, P1, P2...projector, R1...first space, R2...second space, S...screen.

Claims

1. a first light source that emits a first light; a first light guide element including a first incident end into which the first light emitted from the first light source is incident and a first emitting end from which the first light incident from the first incident end is emitted, the first light guide element reflecting the first light incident from the first incident end on an inner surface; a first polarizing element disposed inside the first light guide element, which reflects a first polarized component and transmits a second polarized component; a first light modulation element that modulates the first light emitted from the first exit end based on image information; a projection optical system that projects the light emitted from the first light modulation element, The projector, wherein the first polarizing element is tilted with respect to an axis perpendicular to an incident surface of the first incident end of the first light guide element.

2. The projector according to claim 1 , wherein the first light guide element has therein a first phase difference portion that changes the polarization component of the first light.

3. an inner surface of the first light guide element includes a first inner surface region and a second inner surface region different from the first inner surface region; The projector described in claim 2, characterized in that the first polarizing element divides a first space surrounded by the first incident end, the first inner surface area, and the first polarizing element, and a second space surrounded by the first exit end, the second inner surface area, and the first polarizing element.

4. The projector according to claim 3 , wherein the first phase difference unit is disposed in the first space.

5. The projector according to claim 4 , wherein the first retardation section is in surface contact with the first inner surface area.

6. 6. The projector according to claim 2, wherein the first retardation section is a λ / 4 plate.

7. When the angle between the line perpendicular to the incident plane and the first polarizing element is θ, 3. The projector according to claim 2, wherein 0 degrees < θ < 60 degrees.

8. When the angle between a line perpendicular to the incident plane and the first polarizing element is θ, 2. The projector according to claim 1, wherein 30 degrees < θ < 90 degrees.

9. a second light source that emits second light having a wavelength band different from that of the first light; a second light guide element including a second incident end into which the second light emitted from the second light source is incident and a second emitting end from which the second light incident from the second incident end is emitted, the second light guide element reflecting the second light incident from the second incident end on an inner surface; a second polarizing element disposed inside the second light guide element, which reflects the third polarized light component and transmits the fourth polarized light component; a second light modulation element that modulates the second light emitted from the second exit end based on image information; a light combining element that combines the light emitted from the first light modulation element and the light emitted from the second light modulation element and outputs the combined light toward the projection optical system, The projector according to claim 1 , wherein the second polarizing element is tilted with respect to an axis perpendicular to an incident surface of the second incident end of the second light guide element.

Images