Image projection device

Abstract

An image projection device according to an embodiment of the present invention comprises: a light radiation unit radiating a plurality of light beams having different wavelengths; a light modulation unit; a projection lens unit for projecting incident light; and a light coupling unit including a first prism and a second prism. The plurality of light beams radiated from the light radiation unit are coupled into one path via the first prism of the light coupling unit and radiated to the light modulation unit. The light radiated to the light modulation unit is reflected to be incident to the light coupling unit, and then is reflected by the second prism and radiated to the projection lens unit.

Description

video projection device

[0001] The present invention relates to an image projection device, and more particularly, to an image projection device that projects by combining light.

[0002] A video projection device converts an externally supplied video signal into projection light, which is then enlarged and projected onto a screen or other device. The light projected onto the screen is processed by converting the light from a light source, such as a lamp, within the device into a light that corresponds to the image. These video projection devices are becoming increasingly smaller and are increasingly being used in conjunction with electronic devices such as laptops and head-mounted displays.

[0003] The method of implementing the image signal supplied to the image projection device into an image is classified into the LCD method and the DLP (Digital Light Processing) method, depending on whether LCD (Liquid Crystal Display) or DMD (Digital Micro-mirror Device) is applied.

[0004] The DLP method utilizes a device that integrates multiple reflective elements onto a single chip, selectively reflecting light to produce high-brightness, high-resolution images. DLP projectors reflect light onto a DMD, and images are created based on the degree of reflection. Therefore, several reflection processes are performed within the projector.

[0005] Meanwhile, image projection devices utilize green, red, and blue light to create color in images. Because they employ multiple light sources, their positions cannot be identical. Consequently, their positions are not perfectly aligned in the projected image, resulting in poor light uniformity. This issue requires improvement. This is particularly problematic when image projection devices are used in compact electronic devices such as head-mounted displays.

[0006] The technical problem to be achieved by the present invention is to provide an image projection device capable of providing an image with high light uniformity even in a compact size.

[0007] The technical problem to be solved by the present invention is to provide an image projection device capable of providing a clear image.

[0008] An image projection device according to an embodiment of the present invention includes a light irradiation unit that irradiates a plurality of lights having different wavelengths, a light modulation unit, a projection lens unit that projects the incident light, and a light coupling unit including a first prism and a second prism, wherein a plurality of lights irradiated from the light irradiation unit are combined into one path through the first prism of the light coupling unit and are irradiated to the light modulation unit, and the light irradiated to the light modulation unit is reflected and incident to the light coupling unit, and then reflected through the second prism and irradiated to the projection lens unit.

[0009] In an image projection device according to an embodiment of the present invention, the first prism is a laminated prism in which a plurality of wedge prisms are laminated, and one or two of the wedge prisms may have a spherical surface.

[0010] In an image projection device according to an embodiment of the present invention, the first prism is a laminated prism in which first, second, and third wedge prisms are sequentially laminated, and the curvature of the upper surface of the first wedge prism may be the same as the curvature of the lower surface of the second wedge prism, and the curvature of the upper surface of the second wedge prism may be the same as the curvature of the lower surface of the third wedge prism.

[0011] In an image projection device according to an embodiment of the present invention, the first wedge prism can reflect red light, the second wedge prism can reflect green light, and the third wedge prism can reflect blue light.

[0012] In an image projection device according to an embodiment of the present invention, the first wedge prism may be disposed between the second wedge prism and the light modulation unit in a direction perpendicular to the light modulation unit, the second wedge prism may be disposed between the first wedge prism and the third wedge prism in a direction perpendicular to the light modulation unit, and the third wedge prism may be disposed on the second wedge prism in a direction perpendicular to the light modulation unit.

[0013] In an image projection device according to an embodiment of the present invention, the plurality of lights having different wavelengths are red light, green light, and blue light, the first wedge prism, the second wedge prism, and the third wedge prism reflect the plurality of lights having different wavelengths, and the curvature of the upper surface of each of the first wedge prism, the second wedge prism, and the third wedge prism can be determined according to the light corresponding to each wedge prism.

[0014] In an image projection device according to an embodiment of the present invention, the curvature of the upper surface of the wedge prism corresponding to the red light may be 16.7 to 16.8 mm, the curvature of the upper surface of the wedge prism corresponding to the green light may be 17.2 to 17.3 mm, and the curvature of the upper surface of the wedge prism corresponding to the blue light may be 17.7 to 17.8 mm.

[0015] In an image projection device according to an embodiment of the present invention, a dichroic reflective coating may be applied between the first wedge prism and the second wedge prism, between the second wedge prism and the third wedge prism, and to the upper surface of the third wedge prism.

[0016] In an image projection device according to an embodiment of the present invention, a coating may be provided between the first wedge prism and the second wedge prism to reflect light corresponding to the first wedge prism, a coating may be provided between the second wedge prism and the third wedge prism to reflect light corresponding to the second wedge prism, and an upper surface of the third wedge prism may be coated to reflect light corresponding to the third wedge prism.

[0017] In an image projection device according to an embodiment of the present invention, the projection lens unit may be configured as a telephoto lens.

[0018] In an image projection device according to an embodiment of the present invention, the light modulation unit may be configured so that light transmitted through the second prism is incident on the reflective surface of the light modulation unit at an angle of 29 degrees or 34 degrees.

[0019] In the image projection device according to an embodiment of the present invention, the second prism may be a TIR (Total Internal Reflection) prism.

[0020] In an image projection device according to an embodiment of the present invention, the light irradiation unit may include a plurality of light sources that irradiate light having different wavelengths and a plurality of collimators corresponding to each of the plurality of light sources.

[0021] According to an embodiment of the present invention, an image projection device with improved light uniformity can be provided.

[0022] According to an embodiment of the present invention, the image projection device can be made compact in size.

[0023] According to an embodiment of the present invention, the clarity of an image provided by an image projection device can be improved.

[0024] FIG. 1 is a perspective view showing the configuration of a projection system according to one embodiment of the present invention in an image projection device.

[0025] FIG. 2 is a front view of a projection system according to one embodiment of the present invention in an image projection device.

[0026] FIG. 3 is a plan view of a projection system according to one embodiment of the present invention in an image projection device.

[0027] FIG. 4 is a side view of a projection system according to one embodiment of the present invention in an image projection device.

[0028] Figure 5 is an exploded view of the first prism of the image projection device according to the present invention.

[0029] Figure 6 is a drawing showing the path of light in an image projection device according to the present invention.

[0030] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0031] However, the technical idea of ​​the present invention is not limited to some of the embodiments described, but can be implemented in various different forms, and within the scope of the technical idea of ​​the present invention, one or more of the components between the embodiments can be selectively combined or substituted for use.

[0032] In addition, terms (including technical and scientific terms) used in the embodiments of the present invention may be interpreted as having a meaning that can be generally understood by a person of ordinary skill in the technical field to which the present invention belongs, unless explicitly and specifically defined and described, and terms that are commonly used, such as terms defined in a dictionary, may be interpreted in consideration of the contextual meaning of the relevant technology.

[0033] Additionally, the terms used in the embodiments of the present invention are intended to describe the embodiments and are not intended to limit the present invention.

[0034] In this specification, the singular may also include the plural unless specifically stated otherwise in the phrase, and when it is described as “A and / or at least one (or more) of B, C”, it may include one or more of all combinations that can be combined with A, B, C.

[0035] Additionally, in describing components of embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used.

[0036] These terms are intended only to distinguish one component from another, and are not intended to limit the nature, order, or sequence of the component.

[0037] And, when a component is described as being 'connected', 'coupled' or 'connected' to another component, it may include not only cases where the component is directly connected, coupled or connected to the other component, but also cases where the component is 'connected', 'coupled' or 'connected' by another component between the component and the other component.

[0038] Additionally, when described as being formed or arranged "above or below" each component, "above" or "below" includes not only cases where the two components are in direct contact with each other, but also cases where one or more other components are formed or arranged between the two components. Furthermore, when expressed as "above" or "below", it can include the meaning of a downward direction as well as an upward direction based on one component.

[0039] FIG. 1 is a perspective view showing the configuration of a projection system according to one embodiment of the present invention in an image projection device.

[0040] Referring to FIG. 1, the projection system of the image projection device may include a light irradiation unit (100), a light modulation unit (200), a projection lens unit (300), and a light coupling unit (400).

[0041] The light irradiation unit (100) can generate and / or irradiate a plurality of lights having different wavelengths. The plurality of lights having different wavelengths may be red light, green light, and blue light. The light irradiation unit (100) may include a light source (not shown) that emits each of the plurality of lights. Specifically, the light irradiation unit (100) may include a red light source that emits red light, a green light source that emits green light, and a blue light source that emits blue light. In addition to the plurality of light sources, the light irradiation unit (100) may include a collimator (110, 120, 130). The collimator (110, 120, 130) can convert the light emitted from the light sources into parallel rays. Since the present invention includes a plurality of light sources, the number of collimators (110, 120, 130) may also be a plurality. That is, the collimators (110, 120, 130) can correspond to each of the multiple light sources.

[0042] The optical modulation unit (200) can adjust the reflection angle of light irradiated from the light irradiation unit (100) and incident through the optical coupling unit (400). The optical modulation unit (200) can be digitally controlled. The optical modulation unit (200) can include a plurality of micro-mirrors, and each of the plurality of micro-mirrors can be digitally controlled. For example, the optical modulation unit (200) can be a DMD (Digital Micro-mirror Device) that has micro-mirrors whose inclination angles change between an ON state and an OFF state according to a control signal arranged in a grid on a plane.

[0043] The projection lens unit (300) can project incident light onto a screen (not shown). The projection lens unit (300) can include multiple projection lenses. The projection lens unit (300) can enlarge and project light using the multiple projection lenses. At least some of the multiple projection lenses can be telephoto lenses.

[0044] The optical coupling unit (400) may include a first prism (410) and a second prism (420).

[0045] The first prism (410) can combine the respective paths of the plurality of light beams irradiated from the light irradiation unit (100) into one. The first prism (410) may be in the form of a stack of wedge prisms to combine the respective paths of the plurality of incident light beams into one. The number of stacked wedge prisms may be the same as the number of incident light beams. The wedge prism may have one or / and two spherical surfaces, and the curvatures of the upper and lower surfaces may be different. The first prism (410) is described in more detail in FIG. 5.

[0046] According to the present invention, a plurality of lights can be combined by the first prism (410), so that an image projected with a plurality of lights can have improved light uniformity.

[0047] The second prism (420) may be a TIR (Total Internal Reflection) prism. The TIR prism may be referred to as a total reflection prism or a total internal reflection prism. The TIR prism can change the direction of light propagation or flip the image up, down, left, and right by utilizing the phenomenon of total internal reflection of light. In the present invention, the TIR prism can direct the light emitted from the first prism (410) and incident thereon to the light modulation unit (200). Thereafter, the TIR prism can direct the light reflected from the light modulation unit (200) and incident thereon to the projection lens unit (300). The light passing through the TIR prism can form a projection image.

[0048] FIGS. 2 to 4 illustrate a projection system according to an embodiment of the present invention in an image projection device as viewed from the front, from above, and from the side, and will be briefly described below.

[0049] FIG. 2 is a front view of a projection system according to one embodiment of the present invention in an image projection device.

[0050] Referring to FIG. 2, a light irradiation unit may be arranged on one side of the image projection device, i.e., the front of the light projector. The light irradiation unit may include a plurality of light sources (not shown) and corresponding collimators (110, 120, 130). The plurality of light sources may be red light sources, green light sources, and blue light sources. The collimators (110, 120, 130) may cause the light irradiated from the light sources to form parallel rays and be incident on the first prism (410) of the light coupling unit. The positions of the plurality of light sources and the collimators (110, 120, 130) may vary depending on the type of the light source. The positions of the plurality of light sources and the collimators (110, 120, 130) may vary depending on the size of the first prism (410). The positions of the plurality of light sources and collimators (110, 120, 130) may vary depending on the distance of the plurality of light sources and collimators (110, 120, 130) from the first prism (410), and the distance between the plurality of light sources and collimators (110, 120, 130) and the degree of rotation up, down, left, and right may vary. In conclusion, the positions of the plurality of light sources and collimators (110, 120, 130) may be positions set so that each of the plurality of lights incident from the collimators (110, 120, 130) to the first prism (410) is emitted from the first prism (410) along the same path.

[0051] Referring again to FIG. 2, when viewed from one side of the image projection device, the projection system may show a plurality of light sources and collimators (110, 120, 130) of the light irradiation unit and a first prism (410) of the light coupling unit. The plurality of light sources and collimators (110, 120, 130) may overlap with the first prism (410) of the light coupling unit, but may not do so depending on the spacing between the plurality of light sources and collimators (110, 120, 130) and the first prism (410). The second prism (420) of the light coupling unit may be visible, but may not be visible depending on its size.

[0052] According to one embodiment, the light modulation unit (200) may be positioned below the first prism (410) of the light coupling unit. The light modulation unit (200) and the first prism (410) may be positioned at a predetermined distance apart. A second prism (420) may be positioned between the light modulation unit (200) and the first prism (410), but the second prism (420) may be hidden by the first prism (410) and may not be visible.

[0053] FIG. 3 is a plan view of a projection system according to one embodiment of the present invention in an image projection device.

[0054] Referring to FIG. 3, when the projection system of the image projection device is viewed from above, a light irradiation unit (100), a light coupling unit (400), and a projection lens unit (300) may be arranged in that order. The light irradiation unit (100) may include a plurality of light sources (not shown) and corresponding collimators (110, 120, 130), and the positions of the collimators (110, 120, 130) may vary depending on the type of light source, the distance from the light coupling unit (400), and the size of the light coupling unit (400). The collimators (110, 120, 130) can convert light irradiated from the light source into parallel rays, and the direction of light incident on the first prism (410) of the light coupling unit (400), i.e., the incident angle of light, can be adjusted depending on the degree of rotation up, down, left, and right. The incident angle of light incident through each collimator (110, 120, 130) may be different.

[0055] A light coupling unit (400) may be placed next to the light irradiation unit (100). The light coupling unit (400) may include a first prism (410) and a second prism (420) as described in FIG. 1, and the first prism (410) may be placed on the second prism (420). There may be a gap between the first prism (410) and the second prism (420). The first prism (410) may have a shape in which the upper surface is wider than the lower surface, and the second prism (420) may have a shape in which the lower surface is wider than the upper surface. Due to these shapes, when the projection system of the image projection device is viewed from above, the first prism (410) may be visible through the light coupling unit (400), and the second prism (420) may or may not be visible.

[0056] A projection lens unit (300) may be placed after the optical coupling unit (400). The projection lens unit (300) may be composed of multiple lenses, and although FIG. 3 shows a projection lens unit (300) composed of four lenses, the present invention is not limited thereto.

[0057] FIG. 4 is a side view of a projection system according to one embodiment of the present invention in an image projection device.

[0058] Figure 4 shows the projection system of an image projection device in a state where light enters from the left and exits from the right.

[0059] Referring to FIG. 4, the projection system of the image projection device may include a light irradiation unit (100), a first prism (410) and a second prism (420) of the light coupling unit, and a projection lens unit (300) arranged in sequence, and the light modulation unit (200) may be arranged below the second prism (420).

[0060] The light irradiation unit (100) may include a plurality of light sources (not shown) and corresponding collimators, as described above with reference to FIGS. 1 to 3. The position of the collimator may be determined by the position of light incident on the first prism (410) through the collimator. The light incident on the first prism (410) through the collimator may be light incident on the first wedge prism of the first prism (410).

[0061] The first prism (410) may be a stacked prism and may include a first wedge prism (411), a second wedge prism (413), and a third wedge prism (417). The first wedge prism (411), the second wedge prism (413), and the third wedge prism (417) may be stacked in sequence, and a coating may be applied between the wedge prisms to reflect light of a specific wavelength. Each wedge prism may have one or / and two spherical surfaces. The contact surfaces of the stacked wedge prisms may have the same curvature. For example, when a first wedge prism (411) and a second wedge prism (413) are in contact, the curvature of the upper surface of the first wedge prism (411) and the curvature of the lower surface of the second wedge prism (413) may be the same. The curvature of the upper surface of each wedge prism may correspond to a plurality of wavelengths of light.

[0062] A plurality of light rays having different wavelengths can travel along the same path by the first prism (410) in which a plurality of wedge prisms (411, 413, 417) are stacked, so that an image in which a plurality of light rays are projected can have improved light uniformity.

[0063] The first prism (410) and the second prism (420) may be arranged so that their faces correspond to each other. The first prism (410) and the second prism (420) may be arranged so that their corresponding faces are spaced apart from each other by a certain distance.

[0064] A light modulation unit (200) may be placed below the second prism (420). The second prism (420) and the light modulation unit (200) may be placed so that a gap of a certain interval is formed between them.

[0065] A projection lens unit (300) may be placed on the right side of the second prism (420). The projection lens unit (300) may be composed of multiple lenses. Light emitted from the second prism (420) may be incident on the projection lens unit (300).

[0066] Figure 5 is an exploded view of the first prism of the image projection device according to the present invention.

[0067] Referring to FIG. 5, the first prism (410) may include a first wedge prism (411), a second wedge prism (413), and a third wedge prism (417). The first prism (410) may be a prism in which the first wedge prism (411), the second wedge prism (413), and the third wedge prism (417) are sequentially stacked.

[0068] The first wedge prism (411) is the prism placed at the lowest position, and its lower surface may be formed of a line or a surface. If the lower surface of the first wedge prism (411) is formed of a surface, it may be an aspherical surface, but is not limited thereto. On the other hand, the upper surface (412) of the first wedge prism may be formed of a spherical surface. The upper surface (412) of the first wedge prism may be coated so as to reflect light of a specific wavelength. The curvature of the upper surface (412) of the first wedge prism may be a curvature corresponding to the specific wavelength. Specifically, if the specific wavelength corresponds to red light, the upper surface (412) of the first wedge prism may be coated so as to reflect red light, and the curvature of the upper surface (412) of the first wedge prism may be a curvature corresponding to red light. The curvature corresponding to the red light may be 16.7 to 16.8 mm. If the curvature of the upper surface (412) of the first wedge prism is outside of 16.7 to 16.8 mm, the red light may not be combined with other lights reflected from the upper surface (414) of the second wedge prism and the upper surface (418) of the third wedge prism, and may proceed along a different path.

[0069] The second wedge prism (413) is a prism positioned in the middle, and both the upper surface (414) and the lower surface (415) may be formed as spherical surfaces. The lower surface (415) of the second wedge prism may be in contact with the upper surface (412) of the first wedge prism. More specifically, the lower surface (415) of the second wedge prism may be in contact with the upper surface (412) of the coated first wedge prism. The lower surface (415) of the second wedge prism and the upper surface (412) of the first wedge prism may have the same curvature in order to be in contact with each other.

[0070] According to one embodiment, the upper surface (414) of the second wedge prism may also be coated to reflect light of a specific wavelength. For example, the upper surface (414) of the second wedge prism may be coated to reflect green light. The upper surface (414) of the second wedge prism may also have a curvature corresponding to the light reflected from the coated upper surface (414) of the second wedge prism. For example, when green light is reflected from the upper surface (414) of the second wedge prism, the curvature of the upper surface (414) of the second wedge prism may be a curvature corresponding to the green light. The curvature corresponding to the green light may be 17.2 to 17.3 mm. When the curvature of the upper surface (414) of the second wedge prism is outside of 17.2 to 17.3 mm, the green light may not be combined with other lights reflected from the upper surface (412) of the first wedge prism and the upper surface (418) of the third wedge prism, and may proceed along a different path.

[0071] The third wedge prism (417) is the prism placed at the top, and both the upper surface (418) and the lower surface (419) may be formed as spherical surfaces. The lower surface (419) of the third wedge prism may be in contact with the upper surface (414) of the second wedge prism. More specifically, the lower surface (419) of the third wedge prism may be in contact with the upper surface (414) of the coated second wedge prism. The lower surface (419) of the third wedge prism and the upper surface (414) of the second wedge prism may have the same curvature in order to be in contact with each other.

[0072] According to one embodiment, the upper surface (418) of the third wedge prism may also be coated to reflect light of a specific wavelength. For example, the upper surface (418) of the third wedge prism may be coated to reflect blue light. The upper surface (418) of the third wedge prism may also have a curvature corresponding to light reflected from the coated upper surface (418) of the third wedge prism. For example, when blue light is reflected from the upper surface (418) of the third wedge prism, the curvature of the upper surface (418) of the third wedge prism may be a curvature corresponding to blue light. The curvature corresponding to blue light may be 17.7 to 17.8 mm. When the curvature of the upper surface (418) of the third wedge prism is outside of 17.7 to 17.8 mm, the blue light may not be combined with other lights reflected from the upper surface (412) of the first wedge prism and the upper surface (414) of the second wedge prism, and may proceed along a different path.

[0073] Here, the first wedge prism (411) is described as corresponding to red light, the second wedge prism (413) is described as corresponding to green light, and the third wedge prism (417) is described as corresponding to blue light. However, the first wedge prism (411) may correspond to blue light, the second wedge prism (413) may correspond to green light, and the third wedge prism (417) may correspond to red light. When the corresponding light is changed, the coating and curvature applied to the upper surface may vary based on the corresponding light.

[0074] Since the first to third wedge prisms are stacked, multiple beams of light can be combined and travel along a single path. Since multiple beams of light travel along the same path, they can be projected onto the same area, resulting in a clearer projected image and improved light uniformity. In other words, if multiple beams of light travel along different paths to display a single area, i.e., a pixel, the projected areas may not be completely aligned, resulting in a lowered clarity of the projected image and lower light uniformity.

[0075] Figure 6 is a drawing showing the path of light in an image projection device according to the present invention.

[0076] Based on what has been described in FIGS. 1 to 5, FIG. 6 illustrates that red light is irradiated to the first collimator (110), green light is irradiated to the second collimator (120), and blue light is irradiated to the third collimator (130). In FIG. 6, the path of the red light is indicated as 630, the path of the green light is indicated as 620, and the path of the blue light is indicated as 610. The path of the red light, the path of the green light, and the path of the blue light may all be the same when each light is reflected from the upper surface of the first prism (410).

[0077] Referring to FIG. 6, when red light is irradiated from a red light source, it is incident on the first collimator (110), and can be emitted as parallel rays through the first collimator (110) and incident on the first prism (410). The red light incident on the first prism (410) is reflected from one surface of the first prism (410) and proceeds to the upper surface of the first prism (410), but can be reflected again from the upper surface of the first wedge prism coated to reflect red light. Thereafter, the red light can exit the first prism (410) and incident on the second prism (420). The red light can be incident and emitted on the second prism (420), reflected by the light modulation unit (200), and incident on the second prism (420) again. The red light that is re-injected into the second prism (420) can be totally reflected by the second prism (420) and enter the projection lens unit (300). The red light that is injected into the projection lens unit (300) can be magnified and form part of the projected image.

[0078] Likewise, when green light is irradiated from a green light source, it can be incident on the second collimator (120) and emitted as parallel rays through the second collimator (120) to be incident on the first prism (410). The green light incident on the first prism (410) is reflected from one surface of the first prism (410) and proceeds to the upper surface of the first prism (410), but can be reflected again from the upper surface of the second wedge prism coated to reflect green light. Thereafter, the green light can exit the first prism (410) and be incident on the second prism (420). The green light can be incident and emitted on the second prism (420), reflected by the light modulation unit (200), and then incident on the second prism (420) again. The green light re-incident through the second prism (420) can be totally reflected by the second prism (420) and enter the projection lens unit (300). The green light incident on the projection lens unit (300) can be magnified and form part of the projected image.

[0079] Finally, when blue light is irradiated from a blue light source, it is incident on the third collimator (130), and can be emitted as parallel rays through the third collimator (130) and incident on the first prism (410). The blue light incident on the first prism (410) is reflected from one surface of the first prism (410) and proceeds to the upper surface of the first prism (410), but can be reflected again from the upper surface of the third wedge prism coated to reflect blue light. Thereafter, the blue light can exit the first prism (410) and incident on the second prism (420). The blue light can be incident and emitted on the second prism (420), reflected by the light modulation unit (200), and incident on the second prism (420) again. The blue light re-injected into the second prism (420) can be totally reflected by the second prism (420) and enter the projection lens unit (300). The blue light entering the projection lens unit (300) can be magnified and form part of the projected image.

[0080] The red, green, and blue lights passing through the first prism (410) can all travel along the same path. That is, the red, green, and blue lights can combine and travel together. As multiple light sources all travel along the same path, the projected image can be made clearer due to improved light uniformity. If the paths of the red, green, and blue lights are not the same, the positions at which the multiple lights are projected to express one pixel can vary, which can lower the light uniformity.

[0081] According to one embodiment, red light, green light, and blue light that pass through the second prism (420) and enter the light modulation unit (200) may enter the reflective surface of the light modulation unit (200) at an angle of 29 degrees or 34 degrees.

[0082] In Fig. 6, it is described that red light is irradiated to the first collimator (110), green light is irradiated to the second collimator (120), and blue light is irradiated to the third collimator (130), but this is not limited thereto. For example, blue light may be irradiated to the first collimator (110), green light may be irradiated to the second collimator (120), and red light may be irradiated to the third collimator (130).

[0083] Although the above description focuses on examples, these are merely examples and do not limit the present invention. Those skilled in the art will appreciate that various modifications and applications not exemplified above are possible without departing from the essential characteristics of the present invention. For example, each component specifically shown in the examples can be modified and implemented. In addition, differences related to such modifications and applications should be construed as being included within the scope of the present invention defined in the appended claims.

Claims

1. A light irradiation unit that irradiates multiple lights with different wavelengths; optical modulation unit; A projection lens unit that projects the incident light; and An optical coupling unit including a first prism and a second prism, An image projection device configured such that a plurality of lights irradiated from the light irradiation unit are combined into one path through the first prism of the light coupling unit and irradiated to the light modulation unit, and the light irradiated to the light modulation unit is reflected and incident on the light coupling unit, and then reflected through the second prism and irradiated to the projection lens unit.

2. In paragraph 1, The above first prism is a laminated prism in which a plurality of wedge prisms are laminated, An image projection device in which the above plurality of wedge prisms have one or two spherical surfaces.

3. In paragraph 1, The above first prism is a laminated prism in which first, second, and third wedge prisms are laminated in sequence. The curvature of the upper surface of the first wedge prism is the same as the curvature of the lower surface of the second wedge prism, The curvature of the upper surface of the second wedge prism is the same as the curvature of the lower surface of the third wedge prism. Image projection device.

4. In paragraph 3, The above first wedge prism reflects red light, The above second wedge prism reflects green light, The above third wedge prism is an image projection device that reflects blue light.

5. In paragraph 3, The first wedge prism is positioned between the second wedge prism and the light modulation unit in a direction perpendicular to the light modulation unit, The second wedge prism is disposed between the first wedge prism and the third wedge prism in a direction perpendicular to the light modulation unit, An image projection device, wherein the third wedge prism is positioned on the second wedge prism in a direction perpendicular to the light modulation unit.

6. In paragraph 3, The above multiple lights with different wavelengths are red light, green light, and blue light. The first wedge prism, the second wedge prism, and the third wedge prism reflect a plurality of lights having different wavelengths, An image projection device, wherein the curvature of the upper surface of each of the first wedge prism, the second wedge prism, and the third wedge prism is determined according to the light corresponding to each wedge prism.

7. In paragraph 6, The curvature of the upper surface of the wedge prism corresponding to the above red light is 16.7 to 16.8 mm, The curvature of the upper surface of the wedge prism corresponding to the above green light is 17.2 to 17.3 mm, An image projection device, wherein the curvature of the upper surface of the wedge prism corresponding to the blue light is 17.7 to 17.8 mm.

8. In paragraph 6, An image projection device, wherein a dichroic reflective coating is applied between the first wedge prism and the second wedge prism, between the second wedge prism and the third wedge prism, and on the upper surface of the third wedge prism.

9. In paragraph 8, Between the first wedge prism and the second wedge prism, a coating is provided to reflect light corresponding to the first wedge prism, Between the second wedge prism and the third wedge prism, a coating is applied to reflect light corresponding to the second wedge prism, An image projection device, wherein the upper surface of the third wedge prism is coated to reflect light corresponding to the third wedge prism.

10. In paragraph 1, An image projection device, wherein the above projection lens unit is composed of a telephoto lens.

11. In paragraph 1, An image projection device in which the above light modulation unit is configured so that light transmitted through the second prism is incident on the reflective surface of the above light modulation unit at an angle of 29 degrees or 34 degrees.

12. In paragraph 1, An image projection device wherein the second prism is a TIR (Total Internal Reflection) prism.

13. In paragraph 1, The above light irradiation unit comprises a plurality of light sources that irradiate light with different wavelengths. An image projection device comprising a plurality of collimators corresponding to each of the plurality of light sources.

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