Image projection device

Abstract

To provide an image irradiation device constituted so as to project an image for display on an image display board, and effectively suppressing the formation of unwanted images in a peripheral region of the image for display due to generation of stray light.SOLUTION: A structure is adopted in which a plurality of columnar protrusions 52 are formed on an inner surface 50a of a housing 50 in which an image generation unit to generate an image for display is accommodated, and second columnar protrusions 54 with a height lower than that of the plurality of columnar protrusions 52 are formed between the columnar protrusions. Thus, even when some of emitted light from the image generation unit or the sunlight and the like reach the inner surface 50a of the housing 50, the reached light is reflected a number of times between the plurality of columnar protrusions 52 and between the plurality of columnar protrusions 52 and the second columnar protrusions 54, so as to effectively attenuate its intensity. Consequently, the percentage of reflected light is reduced and the generation of stray light is effectively suppressed.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an image projection device configured to project a display image onto an image display panel. [Background technology]

[0002] Conventionally, as an in-vehicle image projection device, there has been known an image projection device that is configured to project a display image onto an image display panel, such as a front window or a light-transmitting plate, arranged on the inside of the vehicle cabin when placed inside the vehicle cabin.

[0003] This image projection device, as described in, for example, "Patent Document 1," is configured to include an image generation unit that generates an image for display and a housing that accommodates the image generation unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-890 Summary of the Invention [Problem to be solved by the invention]

[0005] In such an image projection device, a part of the light emitted from the image generating unit may be reflected on the inner surface of the housing and become stray light, which may reach the image display plate. The stray light that reaches the image display plate may cause an unintended and unnecessary image to be formed in the peripheral area of ​​the display image.

[0006] Furthermore, sunlight entering the vehicle interior through the windshield or the like may enter the interior space of the housing and become stray light due to reflection on the inner surface thereof.

[0007] It should be noted that such a problem may also occur in image projection devices other than those mounted on vehicles.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide an image projection device configured to project a display image onto an image display panel, which can effectively suppress the formation of unnecessary images in the peripheral area of ​​the display image due to the generation of stray light. [Means for solving the problem]

[0009] The present invention is intended to achieve the above object by improving the configuration of the housing.

[0010] That is, the image projection device according to the present invention is An image projection device configured to project a display image on an image display board, The display device includes an image generating unit that generates the display image, and a housing that accommodates the image generating unit. A plurality of columnar projections are formed on the inner surface of the housing, A second columnar projection portion having a height lower than each of the plurality of columnar projection portions is formed between the plurality of columnar projection portions. And, In addition, the image projection device according to the first aspect of the present invention is a ratio of a pitch between the plurality of columnar projections to a height of each of the plurality of columnar projections is set to a value of 1.5 or less, In addition, the image projection device according to the second invention of the present application is the pitch between the plurality of columnar projections is set to a value of 200 μm or less, The height of each of the plurality of columnar projections is set to a value of 50 μm or more. The present invention is characterized in that:

[0011] The above-mentioned "image projection device" is not particularly limited in its specific use as long as it is configured to project a display image onto an image display board, and can be used, for example, as an in-vehicle head-up display.

[0012] The above-mentioned "image display board" is not particularly limited in its specific configuration as long as it is configured to project a display image, and for example, a translucent plate placed on the front window of a vehicle or on the inside of the passenger compartment can be used.

[0013] The above-mentioned "multiple columnar protrusions" are formed on the inner surface of the housing, but the specific area in which they are formed is not particularly limited, and they may be formed over the entire area of ​​the inner surface of the housing, or may be formed over only a portion of that area.

[0014] The specific height and cross-sectional shape of each of the "plurality of columnar protrusions" are not particularly limited, and for example, cylindrical or prismatic shapes can be used.

[0015] The "second columnar protrusion" is not particularly limited in terms of its specific height, cross-sectional shape, etc., so long as it is formed to have a height lower than each of the plurality of columnar protrusions. Effect of the Invention

[0016] The image projection device of the present invention is configured to project a display image onto an image display panel, and an image generating unit that generates the display image is contained in a housing. A plurality of columnar protrusions are formed on the inner surface of the housing, and second columnar protrusions that are lower in height than each of the plurality of columnar protrusions are formed between each other, thereby obtaining the following advantageous effects.

[0017] That is, even if a part of the emitted light from the image generating unit reaches the inner surface of the housing, by forming a plurality of columnar protrusions and a second columnar protrusion in the reaching area, the reaching light can be reflected a plurality of times between the plurality of columnar protrusions and between the plurality of columnar protrusions and the second columnar protrusion, and the intensity of the light can be effectively attenuated. This makes it possible to reduce the proportion of light that reaches the inner surface of the housing and is then emitted as reflected light into the space outside the housing.

[0018] Furthermore, for example, in a vehicle-mounted image projection device, even if sunlight entering the vehicle cabin through the front window or the like enters the internal space of the housing and reaches its inner surface, by forming a plurality of columnar protrusions and a second columnar protrusion in the reaching area, the reaching light can be reflected multiple times between the plurality of columnar protrusions and between the plurality of columnar protrusions and the second columnar protrusion, thereby effectively attenuating its intensity. This makes it possible to reduce the proportion of light that reaches the inner surface of the housing and then exits as reflected light into the external space of the housing.

[0019] Therefore, it is possible to effectively prevent the light reflected on the inner surface of the housing from becoming stray light and reaching the image display panel, and thus it is possible to effectively prevent the formation of unnecessary images due to stray light in the peripheral area of ​​the display image.

[0020] Moreover, as described above, by forming a plurality of second columnar protrusions along with a plurality of columnar protrusions on the inner surface of the housing, the number of times that the light emitted from the image generating unit, sunlight, etc. that reaches the inner surface of the housing is reflected can be significantly increased compared to a configuration in which only a plurality of columnar protrusions are formed on the inner surface of the housing, and this makes it possible to significantly reduce the proportion of light that reaches the inner surface of the housing and is then emitted into the space outside the housing as reflected light.

[0021] Thus, according to the present invention, in an image projection device configured to project a display image onto an image display panel, it is possible to effectively prevent the formation of unnecessary images in the peripheral area of ​​the display image due to the occurrence of stray light.

[0022] Moreover, according to the present invention, the generation of stray light can be suppressed without applying an anti-reflective coating or the like to the inner surface of the housing, thereby enabling the cost of the image projection device to be reduced.

[0023] In the above configuration, if the ratio of the pitch between the plurality of columnar protrusions to the height of each of the plurality of columnar protrusions is set to a value of 1.5 or less, the number of times that the light emitted from the image generating unit, sunlight, etc. that reaches the inner surface of the housing is reflected between the plurality of columnar protrusions and between the plurality of columnar protrusions and the second columnar protrusion can be sufficiently ensured, thereby ensuring a sufficient attenuation effect of the light intensity. Therefore, the proportion of light that is emitted as reflected light into the external space of the housing after reaching the inner surface of the housing can be significantly reduced.

[0024] In the above configuration, if the pitch between the plurality of columnar protrusions is set to a value of 200 μm or less and the height of each of the plurality of columnar protrusions is set to a value of 50 μm or more, the number of times that the light emitted from the image generating unit, sunlight, etc. that reaches the inner surface of the housing is reflected between the plurality of columnar protrusions and between the plurality of columnar protrusions and the second columnar protrusion can be sufficiently ensured, thereby ensuring a sufficient attenuation effect of the light intensity. Therefore, the proportion of light that reaches the inner surface of the housing and is emitted into the external space of the housing as reflected light can be significantly reduced.

[0025] In the above configuration, if the housing is further configured to be composed of a resin molded product having carbon black dispersed therein, the presence of carbon black can reduce the reflectance of light that reaches the inner surface of the housing, thereby making it possible to more effectively suppress the generation of stray light.

[0026] In the above configuration, if the image projection device further includes a reflector disposed in the housing for reflecting the light emitted from the image generating unit toward the image display plate, it becomes easy to guide the light emitted from the image generating unit to the image display plate. However, in the case of such a configuration, there is a risk that stray light will be generated when the light reflected by the reflector reaches the inner surface of the housing, so that it is particularly effective to adopt the configuration of the present invention. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a side cross-sectional view showing an image projection device according to an embodiment of the present invention mounted on a vehicle. [Diagram 2] View from the direction of arrow II in Figure 1 [Diagram 3] Detailed view of part III in Fig. 1 [Figure 4] Detailed view of part IV in Fig. 3 [Diagram 5] Detailed view of V part in Fig. 4 [Figure 6] VI direction view of Figure 5 [Figure 7] FIG. 7 is a view similar to FIG. 5, showing a first modified example of the embodiment. [Figure 8] FIG. 7 is a view similar to FIG. 5, showing a second modification of the embodiment; [Figure 9] FIG. 7 is a view similar to FIG. 6, showing a third modification of the embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0029] Fig. 1 is a side cross-sectional view showing an image projection device 10 according to this embodiment in a state where it is mounted on a vehicle 100. Fig. 2 is a view seen in the direction of the arrow II in Fig. 1.

[0030] In these figures, the direction indicated by X is the "forward" direction of the image projection device 10 (also the "forward" direction of the vehicle), the direction indicated by Y is the "leftward" direction perpendicular to the "forward" direction, and the direction indicated by Z is the "upward" direction. This is the same in the other figures.

[0031] As shown in FIGS. 1 and 2, the image projection device 10 of this embodiment is an in-vehicle head-up display, and is configured to project a display image PIC on a display area 102A of a front window 102 serving as an image display board when placed in the passenger compartment of a vehicle 100.

[0032] The display area 102A is positioned in the lower area of ​​the windshield 102 and in the area in front of the steering wheel 104, so that the driver 2 of the vehicle 100 can easily visually recognize it. Note that Fig. 2 shows a state in which the vehicle speed (50Km / h) is displayed together with a left-facing arrow as a specific example of the display image PIC.

[0033] The image projection device 10 is disposed so as to be located in front of the steering wheel 104 and in the vicinity of the lower part of the windshield 102 .

[0034] As shown in FIG. 1, the image projection device 10 includes an image generating unit 20 that generates an image that is the basis for the display image PIC, first and second reflecting mirrors 30, 40 that sequentially reflect the light emitted from the image generating unit 20 toward the display area 102A of the front window 102, a housing 50 that accommodates the image generating unit 20 and the first and second reflecting mirrors 30, 40, and a translucent cover 60 attached to the housing 50.

[0035] FIG. 3 is a detailed view of part III in FIG.

[0036] 3, the image generating unit 20 includes a liquid crystal panel 22, and is placed on the lower wall of the housing 50 in the rear region of the internal space 12 of the housing 50 with the liquid crystal panel 22 facing upward. The image generating unit 20 is adapted to generate an image that is the source of the display image PIC on the liquid crystal panel 22 by irradiating the liquid crystal panel 22 with a backlight from below.

[0037] The first reflecting mirror 30 is configured as a plane mirror, and is disposed above the image generating unit 20. The first reflecting mirror 30 is configured to reflect the irradiated light from the image generating unit 20 forward, and is supported by the housing 50 in a state where it is positioned relative to the image generating unit 20.

[0038] The second reflecting mirror 40 is configured as a concave mirror, and is disposed in front of the first reflecting mirror 30. The second reflecting mirror 40 is configured to reflect the light emitted from the image generating unit 20, which is reflected by the first reflecting mirror 30, upward. The second reflecting mirror 40 is supported by the housing 50 via a rotating support member 42, which allows the angle to be adjusted so that the reflected light from the first reflecting mirror 30 is correctly incident on the display area 102A of the front window 102.

[0039] The housing 50 is made of an opaque resin molded product and opens upward. The entire area of ​​the inner surface 50a of the housing 50 has a fine uneven structure (this will be described later).

[0040] The light-transmitting cover 60 is made of a colorless and transparent resin panel curved downward, and is attached to the upper end opening of the housing 50 in a state in which it is inclined slightly upward toward the rear. This light-transmitting cover 60 ensures dustproofness of the internal space 12 of the housing 50 while allowing the reflected light from the second reflecting mirror 40 to enter the display area 102A.

[0041] 4 is a detailed view of a portion IV in FIG. 3, and FIG. 5 is a detailed view of a portion V in FIG.

[0042] As shown in Figures 4 and 5, a plurality of columnar protrusions 52 are formed on the inner surface 50a of the housing 50, and second columnar protrusions 54 having a lower height than each of the columnar protrusions 52 are formed between the columnar protrusions 52.

[0043] The plurality of columnar projections 52 are formed at a substantially constant pitch and at a substantially constant height. Each columnar projection 52 has a conical shape close to a cylinder, and its tip is formed in a hemispherical shape.

[0044] The ratio of the pitch P between the multiple columnar protrusions 52 to the height H1 of each of the multiple columnar protrusions is set to a value of 1.5 or less. Specifically, the pitch P is set to a value of about P=70 to 200 μm, and the height H1 is set to a value of about H1=50 to 140 μm.

[0045] Each of the multiple second columnar protrusions 54 is located approximately in the center of a pair of columnar protrusions 52 located on both the front and rear sides of it, and a connection portion 56 connecting to one of the columnar protrusions 52 is formed in its lower region.

[0046] Each of the second columnar protrusions 54 also has a conical shape close to a cylinder, and its tip is formed into a hemispherical shape. The height H2 of each of the second columnar protrusions 54 is set to a value of about H2=0.4 to 0.8×H1 relative to the height H1 of each of the columnar protrusions 52. The diameter of each of the second columnar protrusions 54 is set to a value smaller than that of each of the columnar protrusions 52.

[0047] FIG. 6 is a view taken in the direction of an arrow VI in FIG.

[0048] As shown in FIG. 6, an inner surface 50a of a housing 50 has a configuration in which a fine concave-convex structure as shown in FIG. 5 is developed two-dimensionally.

[0049] That is, the multiple columnar protrusions 52 and second columnar protrusions 54 are arranged in a line in the front-rear direction in the cross-sectional shape shown in Fig. 5, and are formed in multiple rows at equal intervals in the left-right direction. In this case, the multiple columnar protrusions 52 and second columnar protrusions 54 are arranged with a half pitch shift in the front-rear direction between adjacent rows. As a result, the multiple columnar protrusions 52 are arranged in a square oblique lattice pattern with the pitch P as shown by the two-dot chain line in the figure, and the second columnar protrusions 54 are arranged approximately in the center of each lattice.

[0050] The pitch P is the pitch along the diagonal line of the above-mentioned square oblique lattice, and the pitch Po along the side of the above-mentioned square oblique lattice is smaller than the pitch P.

[0051] 4, light that reaches the inner surface 50a of the housing 50 in the internal space 12 is absorbed or diffusely reflected without being specularly reflected by the inner surface 50a. This is because the inner surface 50a of the housing 50 has the fine uneven structure as described above.

[0052] That is, as shown in Fig. 5, the light that reaches the inner surface 50a of the housing 50 is reflected multiple times between the adjacent columnar protrusions 52 and second columnar protrusions 54. Note that Fig. 5 shows the optical paths of light incident from directions inclined at 45° and 75° with respect to the inner surface 50a of the housing 50.

[0053] Furthermore, as shown in FIG. 6, since the fine uneven structure is developed two-dimensionally, light is reflected multiple times between the columnar protrusions 52 constituting adjacent rows, and also reflected multiple times between the second columnar protrusions 54.

[0054] The light reaching the inner surface 50a of the housing 50 loses intensity each time it is reflected, so that the proportion of light that is ultimately reflected toward the internal space 12 of the housing 50 is extremely small. Specifically, the proportion of the total amount of reflected light to the total amount of light incident on the inner surface 50a of the housing 50 is less than 5%.

[0055] The fine uneven structure on the inner surface 50a of the housing 50 (i.e., a structure in which a plurality of columnar protrusions 52 are formed and second columnar protrusions 54 having a lower height than each of the columnar protrusions 52 are formed between the columnar protrusions 52) can be formed by texturing. In this case, it is possible to form a transferred shape of the fine uneven structure by subjecting the surface of the mold for molding the housing 50 to etching or laser processing. When etching the surface of the mold for molding the housing 50, a method in which etching is performed multiple times with the etching pattern shifted can be used.

[0056] Next, the optical function of the image projection device 10 will be described.

[0057] An optical path R shown in FIGS. 1 and 3 is an original optical path when the driver 2 visually recognizes the display image PIC projected on the display area 102A of the front windshield 102 by the image projection device 10.

[0058] The optical paths Ra and Rb shown in FIGS. 1 and 3 are optical paths other than the original optical path R, and are optical paths in which stray light may occur.

[0059] The optical path Ra is the optical path of the light emitted from the image generating unit 20, which is emitted from the end region of the liquid crystal panel 22, reflected sequentially by the first and second reflecting mirrors 30, 40, and reaches the upper end region of the rear wall portion on the inner surface 50a of the housing 50.

[0060] Since the inner surface 50a of the housing 50 has the fine uneven structure as described above, light that reaches the upper end region of the rear wall of the inner surface 50a is not specularly reflected. If specular reflection were to occur at the upper end region of the rear wall of the inner surface 50a, the light would reach the lower region of the display area 102A through the light-transmitting cover 60 as shown by the light path Ra' indicated by the two-dot chain line in the figure, resulting in the formation of an unnecessary image PICa' as shown in FIG. 2.

[0061] On the other hand, optical path Rb is the optical path taken when sunlight enters the internal space 12 of the housing 50 through the front window 102 and the translucent cover 60, is reflected by the first reflecting mirror 30, and reaches the lower wall portion of the inner surface 50a of the housing 50.

[0062] Since the inner surface 50a of the housing 50 has the fine uneven structure as described above, the light that reaches the lower wall of the inner surface 50a is not specularly reflected. If the light were specularly reflected at the lower wall of the inner surface 50a, it would reach the upper vicinity of the display area 102A on the front window 102 through the light-transmitting cover 60 as shown by the light path Rb' indicated by the two-dot chain line in the figure, and thus an unnecessary image PICb' would be formed as shown in FIG.

[0063] Next, the operation of this embodiment will be described.

[0064] The image projection device 10 of this embodiment is configured to project a display image PIC on a front window 102 serving as an image display panel, and an image generating unit 20 that generates the display image PIC is accommodated in a housing 50. A plurality of columnar protrusions 52 are formed on the inner surface 50a of the housing 50, and second columnar protrusions 54 having a lower height than each of the plurality of columnar protrusions 52 are formed between the columnar protrusions 52, so that the following effects can be obtained.

[0065] That is, even if a part of the emitted light from the image generating unit 20 reaches the inner surface 50a of the housing 50, since the multiple columnar protrusions 52 and the second columnar protrusions 54 are formed in the reaching area, the reaching light can be reflected multiple times between the multiple columnar protrusions 52 and between the multiple columnar protrusions 52 and the second columnar protrusions 54, thereby effectively attenuating the intensity of the light. This makes it possible to reduce the proportion of light that reaches the inner surface 50a of the housing 50 and then is emitted as reflected light into the external space of the housing 50.

[0066] In the image projection device 10 according to the present embodiment, sunlight entering the vehicle cabin through the front window 102 may enter the internal space 12 of the housing 50 through the light-transmitting cover 60 and reach the inner surface 50a, but since the plurality of columnar protrusions 52 and the second columnar protrusions 54 are formed in the area where the sunlight reaches, the reaching light is reflected multiple times between the plurality of columnar protrusions 52 and between the plurality of columnar protrusions 52 and the second columnar protrusions 54, and the intensity of the light can be effectively attenuated. This makes it possible to reduce the proportion of light that reaches the inner surface 50a of the housing 50 and then exits as reflected light into the space outside the housing 50.

[0067] Therefore, it is possible to effectively prevent the light reflected by the inner surface 50a of the housing 50 from becoming stray light and reaching the display area 102A of the front window 102 through the light-transmitting cover 60. This makes it possible to effectively prevent the formation of unnecessary images (see images PICa' and PICb' shown in FIG. 2) due to stray light in the peripheral area of ​​the display image PIC.

[0068] Moreover, by forming a plurality of second columnar protrusions 54 along with a plurality of columnar protrusions 52 on the inner surface 50a of the housing 50 as in the present embodiment, the number of times that the light emitted from the image generating unit 20, sunlight, etc. that reaches the inner surface 50a of the housing 50 is reflected can be significantly increased compared to a configuration in which a plurality of columnar protrusions 52 are simply formed on the inner surface 50a of the housing 50. As a result, the proportion of light that reaches the inner surface 50a of the housing 50 and is then emitted into the space outside the housing 50 as reflected light can be significantly reduced.

[0069] Thus, according to this embodiment, in the image projection device 10 configured to project the display image PIC on the front window 102, it is possible to effectively prevent the formation of unnecessary images in the peripheral area of ​​the display image PIC due to the occurrence of stray light.

[0070] Moreover, according to this embodiment, the generation of stray light can be suppressed without applying an anti-reflective coating or the like to the inner surface 50a of the housing 50, and therefore the cost of the image projection device 10 can be reduced.

[0071] In this embodiment, since the ratio of the pitch P between the plurality of columnar protrusions 52 to the height H1 of each of the plurality of columnar protrusions 52 is set to a value of 1.5 or less, it is possible to ensure a sufficient number of times that the light emitted from the image generating unit 20, sunlight, etc., that has reached the inner surface 50a of the housing 50 is reflected between the plurality of columnar protrusions 52 and between the plurality of columnar protrusions 52 and the second columnar protrusion 54, thereby ensuring a sufficient attenuation effect of the light intensity. Therefore, it is possible to significantly reduce the proportion of light that, after reaching the inner surface 50a of the housing 50, is emitted as reflected light into the external space of the housing 50.

[0072] In this embodiment, the pitch between the multiple columnar protrusions 52 is set to a value of 200 μm or less, and the height of each of the multiple columnar protrusions 52 is set to a value of 50 μm or more, so that the number of times that the light emitted from the image generating unit 20, sunlight, etc. that has reached the inner surface 50a of the housing 50 is reflected between the multiple columnar protrusions 52 and between the multiple columnar protrusions 52 and the second columnar protrusions 54 can be sufficiently ensured, thereby ensuring a sufficient attenuation effect of the light intensity. Therefore, the proportion of light that reaches the inner surface 50a of the housing 50 and then is emitted as reflected light into the external space of the housing 50 can be significantly reduced.

[0073] Furthermore, in this embodiment, the first and second reflecting mirrors 30, 40 that sequentially reflect the light emitted from the image generating unit 20 toward the display area 102A of the front window 102 are disposed in the internal space 12 of the housing 50, so that it is possible to easily guide the light emitted from the image generating unit 20 to the display area 102A of the front window 102. At that time, there is a risk of stray light being generated when the light reflected by the first and second reflecting mirrors 30, 40 reaches the inner surface 50a of the housing 50, so that it is particularly effective to employ the configuration of this embodiment.

[0074] In the above embodiment, the multiple columnar protrusions 52 and the second columnar protrusions 54 are described as being formed over the entire area of ​​the inner surface 50a of the housing 50, but it is also possible to configure them to be formed only in areas where light that causes stray light may be incident.

[0075] In the above embodiment, the configuration is described as including first and second reflecting mirrors 30, 40, but it is also possible to have a configuration including a single reflecting mirror, or a configuration without any reflecting mirrors.

[0076] In the above embodiment, each of the multiple columnar protrusions 52 and the second columnar protrusions 54 has been described as having a conical shape close to a cylinder, but it is also possible to configure them to have other shapes (for example, a pyramidal shape close to a square prism or a hexagonal prism).

[0077] In the above embodiment, the image display panel is described as being configured as the front window 102, but it is also possible to configure the image display panel using a translucent plate or the like arranged on the inside of the vehicle compartment of the front window 102.

[0078] In the above embodiment, the image projection device 10 has been described as being an in-vehicle head-up display, but it may also be used for other purposes.

[0079] Next, a modification of the above embodiment will be described.

[0080] First, a first modification of the above embodiment will be described.

[0081] FIG. 7 is a view similar to FIG. 5, showing a main part of a housing 150 of an image projection device according to this modified example.

[0082] As shown in FIG. 7, the housing 150 of this modified example is also made of a resin molded product having a shape similar to that of the housing 50 of the above embodiment, but differs from the above embodiment in that it has carbon black 158 dispersed therein.

[0083] By adopting the configuration of this modified example, the presence of carbon black 158 can make the reflectance of light that reaches inner surface 150a of housing 150 even smaller than in the above embodiment, thereby making it possible to more effectively suppress the generation of stray light.

[0084] Next, a second modification of the above embodiment will be described.

[0085] FIG. 8 is a view similar to FIG. 5, showing a main part of a housing 250 of an image projection device according to this modified example.

[0086] As shown in FIG. 8, the housing 250 of this modified example is also made of a resin molded product similar to the housing 50 of the above embodiment, but the fine uneven structure formed on the inner surface 250a of the housing 250 is partially different from that of the above embodiment.

[0087] That is, in this modified example, a plurality of columnar protrusions 252 are formed on the inner surface 250a of the housing 250, and second columnar protrusions 254 having a lower height than each of the plurality of columnar protrusions 252 are formed between each of the columnar protrusions 252, but this modification differs from the above embodiment in that two second columnar protrusions 254 are formed each.

[0088] In this case, the multiple columnar protrusions 252 are formed with the same pitch P and height H1 as in the above embodiment. On the other hand, each second columnar protrusion 254 is formed with a height approximately half the height H1 of each columnar protrusion 252.

[0089] By adopting the configuration of this modified example, it is possible to reflect more of the light that reaches the inner surface 250a of the housing 250, and to increase the effect of attenuating the light intensity, thereby more effectively suppressing the occurrence of stray light.

[0090] Next, a third modification of the above embodiment will be described.

[0091] FIG. 9 is a view similar to FIG. 6, showing a main part of a housing 350 of an image projection device according to this modified example.

[0092] As shown in FIG. 9, the housing 350 of this modified example is also made of a resin molded product similar to the housing 50 of the above embodiment. However, the fine uneven structure formed on the inner surface 350a of the housing 350 is partially different from that of the above embodiment.

[0093] That is, in this modified example, a plurality of columnar protrusions 352 are formed on the inner surface 350a of the housing 350 at the same pitch P as in the above embodiment, and second columnar protrusions 354 having a lower height than each of the plurality of columnar protrusions 352 are formed between each of the columnar protrusions 352, but it differs from the above embodiment in that two second columnar protrusions 354 are formed each.

[0094] At this time, the multiple columnar protrusions 352 are arranged in a square oblique lattice pattern with the pitch P remaining the same, and two second columnar protrusions 354 are arranged within each lattice.

[0095] Further, two second columnar projections 354 are connected to each of the plurality of columnar projections 352 via connection portions 356, and at this time, the connection portions 356 extend in a direction inclined with respect to the front-rear direction.

[0096] By adopting the configuration of this modification, it is possible to achieve a configuration in which the multiple columnar protrusions 352 and the second columnar protrusions 354 are two-dimensionally arranged at higher density. This makes it possible to reflect more light that reaches the inner surface 350a of the housing 350, and to enhance the effect of attenuating the light intensity, thereby more effectively suppressing the generation of stray light.

[0097] It should be noted that the numerical values ​​given as the specifications in the above embodiment and its modified examples are merely examples, and it goes without saying that these may be set to different values ​​as appropriate.

[0098] Furthermore, the present invention is not limited to the configurations described in the above embodiment and its modified examples, and various other modified configurations can be adopted. [Explanation of symbols]

[0099] 2 Driver 10. Image projection device 12 Interior Space 20 Image Generation Unit 22 Liquid crystal panel 30 1st reflector 40 Second reflector 42 Rotating support member 50, 150, 250, 350 Housing 50a, 150a, 250a, 350a inner surface 52, 252, 352 Columnar projection 54, 254, 354 2nd columnar protrusion 56, 356 Connection 60 Translucent cover 100 vehicles 102 Front window (image display board) 102A Display area 104 Steering Wheel 158 Carbon Black H1, H2 height P, Po pitch PIC Display image R, Ra, Rb optical path

Claims

1. An image projection device configured to project a display image on an image display board, The display device includes an image generating unit that generates the display image, and a housing that accommodates the image generating unit. A plurality of columnar projections are formed on the inner surface of the housing, a second columnar projection portion having a height lower than each of the plurality of columnar projection portions is formed between the plurality of columnar projection portions, an image projection device, characterized in that a ratio of a pitch between the plurality of columnar projections to a height of each of the plurality of columnar projections is set to a value of 1.5 or less.

2. An image projection device configured to project a display image onto an image display board, The display device includes an image generating unit that generates the display image, and a housing that accommodates the image generating unit. A plurality of columnar projections are formed on the inner surface of the housing, a second columnar projection portion having a height lower than each of the plurality of columnar projection portions is formed between the plurality of columnar projection portions, the pitch between the plurality of columnar projections is set to a value of 200 μm or less, an image projection device, characterized in that the height of each of the plurality of columnar protrusions is set to a value of 50 μm or more;

3. 3. The image projection device according to claim 1, wherein the housing is made of a resin molded product having carbon black dispersed therein.

4. 4. The image projection device according to claim 1, further comprising a reflector disposed within said housing for reflecting the light emitted from said image generating unit towards said image display panel.

Images