Display device

Abstract

A display device (10) includes a display element (30) having a display surface (31), an optical element (40) having a first surface (41) and a second surface (42) facing the first surface, light emitted from the display surface being incident on the first surface, being reflected by the second surface in a direction different from the display surface, and being emitted from the first surface, and a housing (20) in which the display element and the optical element are built in. The optical element is disposed so that the height direction of the optical element is along the vertical direction, and in a cross-sectional view obtained by observing a cross section of the optical element including the vertical direction, when t1 / t2 is set as a thickness ratio, where t1 is a first thickness at an upper end of the optical element in a reference direction parallel to a normal line (N) of an origin of the second surface, and t2 is a second thickness at a lower end of the optical element in the reference direction, the value of the thickness ratio when the width of the display element is equal to the width of the optical element is set as an upper limit of the thickness ratio, and the value of the thickness ratio that makes the depth of the housing the same as the depth of the housing at the upper limit and is smaller than the upper limit is set as a lower limit of the thickness ratio.

Description

Technical Field

[0001] This disclosure relates to a display device. Background Technology

[0002] In recent years, display devices for displaying images have been known. For example, as an example of a display device, Patent Document 1 discloses a display device comprising a display, a semi-transparent mirror for reflecting an image displayed on the display, and a concave mirror for reflecting the image reflected by the semi-transparent mirror.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-210229 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] Miniaturization of display devices has been a long-standing desire. Therefore, the object of this disclosure is to provide a display device capable of being miniaturized.

[0008] Solution for solving the problem

[0009] One aspect of this disclosure relates to a display device comprising: a display element having a display surface; an optical element having a first surface and a second surface facing the first surface, light emitted from the display surface being incident on the first surface, reflected by the second surface in a direction different from the display surface, and exiting from the first surface; and a housing housing the display element and the optical element, wherein the first surface and the second surface are formed as concave curved surfaces recessed toward the incident direction of the light, the optical element is configured such that the height direction of the optical element is along the vertical direction, and in a cross-sectional view of the optical element including the vertical direction, when the first thickness at the upper end of the optical element in a reference direction parallel to the normal to the origin of the second surface is set as t1, and the optical element... When the thickness ratio is t1 / t2, where the second thickness at the lower end of the element in the reference direction is t2, (i) based on the correlation between the thickness ratio and the width of the display element in the width direction orthogonal to the plane including the height direction and the reference direction, the value of the thickness ratio when the width of the display element is equal to the width of the optical element is set as the upper limit of the thickness ratio; (ii) based on the correlation between the thickness ratio and the depth of the housing in the depth direction orthogonal to the plane including the height direction and the width direction, the value of the thickness ratio that makes the depth of the housing the same as the upper limit and smaller than the upper limit is set as the lower limit of the thickness ratio, wherein the thickness ratio satisfies the relationship of being above the lower limit and below the upper limit.

[0010] The effects of the invention

[0011] The display device according to this disclosure can be miniaturized. Attached Figure Description

[0012] Figure 1 This is a schematic diagram showing the state in which the display device according to Embodiment 1 is installed in a vehicle.

[0013] Figure 2 This is a schematic diagram showing the outline structure of the display device according to Embodiment 1.

[0014] Figure 3 This is an explanatory diagram showing the relationship between the optical element and the display surface according to Embodiment 1.

[0015] Figure 4 This is an explanatory diagram showing the relationship between the optical elements and the display surface involved in the comparative example.

[0016] Figure 5 This is a graph showing the relationship between the thickness ratio of the optical element and the width of the display element in Embodiment 1.

[0017] Figure 6 This is a graph showing the relationship between the thickness ratio of the optical element and the depth of the housing in Embodiment 1.

[0018] Figure 7 This is a schematic diagram showing the outline structure of the display device according to Embodiment 2.

[0019] Figure 8 This is a schematic diagram showing the outline structure of the display device according to Embodiment 3.

[0020] Figure 9 This is a schematic diagram showing the outline structure of the display device according to Embodiment 4.

[0021] Figure 10 This is a perspective view showing the optical element involved in Embodiment 5.

[0022] Figure 11 This is a front view showing the optical element involved in Embodiment 6.

[0023] Figure 12 This is a structural diagram showing the optical element involved in Embodiment 7. Detailed Implementation

[0024] One aspect of this disclosure relates to a display device comprising: a display element having a display surface; an optical element having a first surface and a second surface facing the first surface, light emitted from the display surface being incident on the first surface, reflected by the second surface in a direction different from the display surface, and exiting from the first surface; and a housing housing the display element and the optical element, wherein the first surface and the second surface are formed as concave curved surfaces recessed toward the incident direction of the light, the optical element is configured such that the height direction of the optical element is along the vertical direction, and in a cross-sectional view of the optical element including the vertical direction, when the first thickness at the upper end of the optical element in a reference direction parallel to the normal to the origin of the second surface is set as t1, and the optical element... When the thickness ratio is t1 / t2, where the second thickness at the lower end of the element in the reference direction is t2, (i) based on the correlation between the thickness ratio and the width of the display element in the width direction orthogonal to the plane including the height direction and the reference direction, the value of the thickness ratio when the width of the display element is equal to the width of the optical element is set as the upper limit of the thickness ratio; (ii) based on the correlation between the thickness ratio and the depth of the housing in the depth direction orthogonal to the plane including the height direction and the width direction, the value of the thickness ratio that makes the depth of the housing the same as the upper limit and smaller than the upper limit is set as the lower limit of the thickness ratio, wherein the thickness ratio satisfies the relationship of being above the lower limit and below the upper limit.

[0025] Based on this, it is possible to make the width of the display element less than or equal to the width of the optical element without increasing the effective display area of ​​the display element. In other words, it is possible to suppress the enlargement of the display element. Furthermore, excessive enlargement of the housing depth, i.e., the distance from the optical element to the emission portion of the housing, can also be suppressed. Therefore, miniaturization can be achieved for the device as a whole.

[0026] The display device involved in one aspect of this disclosure may also have a thickness ratio that satisfies the relationship of 0.5 or more and 4.0 or less.

[0027] Based on this, since the range of the thickness ratio (t1 / t2) that can suppress the enlargement of the display element and the enlargement of the housing depth can be determined, a specific design policy for miniaturization can be obtained.

[0028] The display device involved in one aspect of this disclosure may also have a mirror disposed at a position opposite to the display surface and the first surface.

[0029] Therefore, since a mirror is positioned facing both the display surface of the display element and the first surface of the optical element, light emitted from the display surface can be reflected by the mirror and enter the optical element from the first surface. This allows for both the reduction of the size of the suppression device and the extension of the optical path length.

[0030] The display device involved in one aspect of this disclosure may also be a plane mirror.

[0031] Therefore, by using easily manufactured plane mirrors as the mirror, it is possible to extend the optical path length while suppressing manufacturing costs.

[0032] The display device involved in one aspect of this disclosure may also be a semi-transparent mirror disposed between the mirror and the optical element.

[0033] Based on this, a semi-transparent mirror is arranged between the mirror and the optical element. Therefore, light emitted from the display surface can be guided towards the mirror by reflection from the semi-transparent mirror, and the light reflected by the mirror can pass through the semi-transparent mirror, be reflected by the optical element, and then reflected again by the semi-transparent mirror. This further extends the optical path length.

[0034] In one embodiment of the display device disclosed herein, the lower edge of the optical element, when viewed from the front, may be formed as a downward-protruding curve.

[0035] Therefore, since the lower edge of the optical element is formed into a downward-protruding curve, the effective display area of ​​the display element can be reduced. Consequently, the display element can be miniaturized, further promoting the miniaturization of the device itself.

[0036] In one embodiment of the display device disclosed herein, the display element may be formed as a curved plate corresponding to the lower curve and disposed at a position facing the lower side.

[0037] Based on this, since the curved shape of the lower edge of the display element and the optical element corresponds to the curved plate shape, the display element can be arranged along the lower edge of the optical element. As a result, unused space can be reduced, and the miniaturization of the device itself can be further promoted.

[0038] In one embodiment of the display device disclosed herein, the optical element may be formed to be left-right symmetrical in a configuration such that the height direction of the optical element is along the vertical direction.

[0039] Based on this, since the optical elements are formed to be symmetrical from left to right, it is possible to suppress image distortion in the left-right direction (width direction).

[0040] The display device according to one aspect of this disclosure may also be such that, in the optical element, the surfaces other than the first surface and the second surface have a first light-absorbing portion that absorbs more light than the first surface and the second surface.

[0041] Therefore, since a first light-absorbing portion is provided on the surfaces of the optical element other than the first and second surfaces, the reflection and transmission of light on these surfaces can be suppressed. This suppresses unwanted light emission and improves image quality.

[0042] In one embodiment of the display device disclosed herein, the area of ​​the first surface may be smaller than the area of ​​the second surface, and a second light-absorbing portion that absorbs more light than the effective display area of ​​the optical element is provided around the periphery of the first surface, in addition to the range corresponding to the effective display area of ​​the display element. The second light-absorbing portion has a size that includes the second surface when viewed from the front.

[0043] Based on this, a second light-absorbing portion with a size that includes the second surface is provided around the periphery of the first surface, in addition to the range corresponding to the effective display area of ​​the display element, thereby suppressing the ambient light emission of the first surface or the second surface.

[0044] In one embodiment of this disclosure, the display device may also be such that, when the optical element is viewed from the front, the width of the lower end of the optical element is smaller than the width of the upper end, and the upper limit of the thickness ratio is set as the value of the thickness ratio when the width of the display element is equal to the width of the lower end of the optical element.

[0045] Based on this, the width of the display element can be made smaller than the width of the lower edge (bottom end) of the optical element when its shape is an inverted trapezoid when viewed from the front. Therefore, the enlargement of the display element can be further suppressed, and thus the overall device can be further miniaturized.

[0046] The display device involved in one aspect of this disclosure may also have a thickness ratio of 1.7 or less.

[0047] Based on this, by determining the upper limit of the thickness ratio (t1 / t2) that can further suppress the enlargement of display elements, a more specific design policy for miniaturization can be obtained.

[0048] The display device involved in one aspect of this disclosure may also have a frame portion provided on the second surface.

[0049] Based on this, a viewing distance difference is generated between the image emitted from the device and the frame, thus enabling visual confirmation of the image with increased depth.

[0050] The display device according to one aspect of this disclosure may also have an anti-reflection unit provided on the first surface of the optical element.

[0051] Based on this, reflections at the first surface can be suppressed by the anti-reflection unit, making it easy for the driver to observe the virtual image.

[0052] (Implementation Method)

[0053] The embodiments described below are all specific examples of this disclosure. The numerical values, shapes, materials, constituent elements, arrangement positions of constituent elements, and connection methods shown in the following embodiments are examples and are not intended to limit this disclosure. In addition, constituent elements in the following embodiments that are not described in the independent claims are described as arbitrary constituent elements.

[0054] In the following embodiments, expressions such as parallel and orthogonal, which describe the relative orientation of two directions, are sometimes used, but these expressions also include cases that are not strictly defined as such. For example, when referring to two directions as parallel, unless otherwise specified, it means not only that the two directions are completely parallel, but also that they are substantially parallel, i.e., containing, for example, a difference of a few percent.

[0055] The optical paths illustrated in the figures of the following implementation methods represent the general concept and therefore may not reflect the actual optical paths.

[0056] In the following description and figures, the width and left-right directions of the optical element are defined as the X-axis, the height and vertical directions are defined as the Y-axis, and the direction orthogonal to both the X-axis and Y-axis is defined as the Z-axis. The Z-axis is the depth direction of the housing, as described later. In the following description, the positive X-axis direction refers to the direction of the arrow on the X-axis, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. When referred to only as the X-axis direction, it means either the positive or negative X-axis direction. The same applies to the Y-axis and Z-axis directions.

[0057] [Implementation Method 1]

[0058] Figure 1 This is a schematic diagram showing the state in which the display device 10 according to Embodiment 1 is installed in the vehicle 1. Figure 1 The vehicle 1 and the housing 20 are shown in cross-section.

[0059] like Figure 1As shown, the display device 10 is a device for displaying images. In this embodiment, the display device 10 is installed inside the passenger compartment of the vehicle 1. For example, the display device 10 displays images captured by a camera positioned behind the vehicle 1. Thus, the driver 2 of the vehicle 1 can view the images by viewing the display device 10 (see reference 10). Figure 1 The dashed arrow (which allows for visual confirmation of the situation behind vehicle 1) provides visual information.

[0060] In addition, for example, the display device 10 may also display images showing the vehicle speed of the vehicle 1, the detection results of objects approaching the vehicle 1, or navigation information from the current location of the vehicle 1 to the destination.

[0061] Figure 2 This is a schematic diagram showing the general structure of the display device 10 according to Embodiment 1. Figure 2 In the image, the housing 20 is shown in cross-section. (As shown in the image...) Figure 2 As shown, the display device 10 includes a housing 20, a display element 30, an optical element 40, and a mirror 50.

[0062] The housing 20 houses the display element 30, the optical element 40, and the mirror 50. In this embodiment, the housing 20 is suspended from the roof of the vehicle 1. The housing 20 has an emission portion 22 for light emitted from the display element 30 to be emitted to the outside of the housing 20. The emission portion 22 is a through hole that connects the interior space of the housing 20 with the exterior space. Inside the housing 20, the mirror 50 is disposed near the corner of the emission portion 22 in the positive Y-axis direction, the optical element 40 is disposed near the inner side in the negative Z-axis direction, and the display element 30 is disposed near the bottom surface of the housing 20 at a position opposite to the mirror 50 in the negative Y-axis direction.

[0063] The display element 30 has a display surface 31 from which light representing an image is emitted. For example, the display surface 31 emits light representing an image captured by a camera filming the rear of the vehicle 1. The display element 30 may be implemented as an LCD (Liquid Crystal Display), an organic EL (Electro Luminescence) display, or a micro LED (Light Emitting Diode) display. The display element 30 is formed such that the entire display surface 31 is flat. The display element 30 is configured to accommodate the orientation of the light-directing mirror 50 from the display surface 31.

[0064] Mirror 50 is a plane mirror, positioned facing the display surface 31 of the display element 30 and the first surface 41 of the optical element 40. Specifically, mirror 50 is configured to reflect light emitted from the display surface 31 toward the first surface 41. This extends the optical path length of the light path Op1.

[0065] Next, the optical element 40 will be described in detail. For example... Figure 2 As shown, the optical element 40 is formed of a light-transmitting material such as a light-transmitting resin (e.g., PMMA (polymethyl methacrylate), PC (polycarbonate), COC (cyclic olefin copolymer), COP (cyclic olefin polymer), etc.), or glass, with a first surface 41 and a second surface 42 facing each other. The optical element 40 is configured such that the first surface 41 receives light from the mirror 50. Therefore, light from the display surface 31 is reflected by the mirror 50, enters the optical element 40 from the first surface 41, is reflected by the second surface 42 in a direction different from that of the display surface 31, and is emitted from the first surface 41 toward the emission portion 22 (in...). Figure 2 (The diagram shows an example of the light path Op1). Additionally, in... Figure 2 In this configuration, the optical element 40 is arranged in a posture in which its height direction is aligned with the vertical direction. Furthermore, the optical element 40 only needs to be arranged in a posture in which its height direction is aligned with the vertical direction. That is, the height direction of the optical element 40 may not be perfectly aligned with the vertical direction, and may include a difference of approximately a few percent.

[0066] like Figure 2 As shown, the first surface 41 and the second surface 42 of the optical element 40 are concave surfaces that are recessed in the direction away from the mirror 50, that is, smooth concave surfaces that are recessed in the direction of light incidence. Specifically, the first surface 41 and the second surface 42 are respectively freeform surfaces using polynomial functions, etc.

[0067] Figure 3 This is an explanatory diagram showing the relationship between the optical element 40, the display surface 31, and the mirror 50 involved in Embodiment 1. Figure 3 (a) is a perspective view showing the optical element 40, the display surface 31, and the mirror 50. Figure 3 (b) is a front view of optical element 40. Figure 3 (c) is a front view showing the effective display area 32 of the display surface 31 corresponding to the optical element 40. Figure 3 In (c), the effective display area 32 is indicated by dotted shading.

[0068] like Figure 3 As shown in (a), the thickness of the optical element 40 is smaller than the width and height of the first surface 41 when viewed from the front. Additionally, as... Figure 3 As shown in (b), when viewed from the front, the optical element 40 is formed in a symmetrical shape. Specifically, when viewed from the front, the optical element 40 is an inverted trapezoidal shape that is longer in the X-axis direction, and its lower side 43 is formed in a downward-protruding curve.

[0069] As described above, the first surface 41 and the second surface 42 of the optical element 40 are concave curved surfaces. Therefore, as Figure 3 As shown in (c), the effective display area 32 of the display surface 31 facing the optical element 40 becomes a shape that flips the front view shape of the optical element 40 upside down, and one long side 33 becomes a straight line.

[0070] Here, as a comparative example, an optical element 40z with a rectangular shape when viewed from the front is shown. Figure 4 This is an explanatory diagram showing the relationship between the optical element 40z, the display surface 31z, and the mirror 50z involved in the comparative example. Figure 4 (a) is a perspective view showing the optical element 40z, the display surface 31z, and the mirror 50z. Figure 4 (b) is a front view of optical element 40z. Figure 4 (c) is a front view showing the effective display area 32z corresponding to the optical element 40z of the display surface 31z. Figure 4 In (c), the effective display area 32z is indicated by dotted shading.

[0071] like Figure 4 As shown in (b), when viewed from the front, the optical element 40z is formed as a rectangle that is longer in the X-axis direction. Therefore, the lower edge 43z of the optical element 40z is formed as a straight line. In this optical element 40z, the first surface 41z and the second surface 42z become the freeform surfaces described above. Therefore, as... Figure 4 As shown in (c), the effective display area 32z of the display surface 31z facing the optical element 40z becomes a curved shape with a pair of longer edges protruding in the same direction. Figure 4 In (a), the portion corresponding to the long side 33 of the effective display area 32 in the embodiment is shown by a dashed line. In this way, since the area of ​​the effective display area 32z in the comparative example is larger than the area of ​​the effective display area 32, the display element of the comparative example is also larger. In other words, the display element 30 in the embodiment can be made smaller compared to the display element of the comparative example.

[0072] Next, the thickness of the optical element 40 will be explained. For example... Figure 2As shown, when the origin of the function representing the freeform surface forming the second surface 42 is set as the reference position P, the direction parallel to the normal N of the second surface 42 at the reference position P is set as the reference direction N1. The length of the upper end of the optical element 40 in the reference direction N1 is set as the first thickness t1, and the length of the lower end of the optical element 40 in the reference direction N1 is set as the second thickness t2. In the optical element 40, the thickness of the portion between the upper and lower ends is the thickness between the first thickness t1 and the second thickness t2. The thickness of any part of the optical element 40 is smaller than the height and width of the optical element 40. Furthermore, in this embodiment, the case where the origin of the function representing the freeform surface forming the second surface 42 is set as the reference position P is illustrated, but the center of the second surface 42 when viewed from the front can also be set as the reference position P.

[0073] Here, the variation of the width of the display element 30 relative to the ratio (t1 / t2) of the first thickness t1 and the second thickness t2 is simulated. Furthermore, this ratio (t1 / t2) is also referred to as the thickness ratio. Additionally, when the thickness ratio is greater than 1 (i.e., t1 > t2), the upper end is thicker than the lower end; when the thickness ratio is less than 1 (i.e., t2 > t1), the lower end is thicker than the upper end.

[0074] Figure 5 This is a graph showing the thickness ratio of the optical element 40 according to Embodiment 1 and the width of the display element 30. In other words, Figure 5 The results show simulations of how the width of the display element 30 changes to fully display the image on the display surface 31 when the thickness ratio is changed. Specifically, Figure 5 (a) shows the simulation results. Figure 5 (b) shows the positional relationship between the display element 30 and the optical element 40. Figure 5 In (a), the horizontal axis represents the thickness ratio (t1 / t2), and the vertical axis represents the width of the display element 30. Furthermore, the width of the display element 30 refers to the length of the display element 30 in the width direction orthogonal to the plane including the height direction (Y-axis direction) and the reference direction N1, that is, the X-axis direction of the display element 30.

[0075] according to Figure 5 The thickness ratio is generally positively correlated with the width of the display element 30, but there is a tendency for the width of the display element 30 to increase slightly when the thickness ratio decreases.

[0076] Here, according to Figure 5The simulation results in (a) show that when the thickness ratio is 4 or less, the width of the display element 30 is smaller than the width W1 of the upper edge (upper end) of the optical element 40. In other words, it can be seen that by making the thickness ratio 4 or less, the width of the display element 30 can be made smaller than the width W1 of the upper edge (upper end) of the optical element 40. Furthermore, it can be seen that when the thickness ratio is 1.7 or less, the width of the display element 30 is smaller than the width W2 of the lower edge 43 (lower end) of the optical element 40. In other words, it can be seen that by making the thickness ratio 1.7 or less, the width of the display element 30 can be made smaller than the width W2 of the lower edge 43 (lower end) of the optical element 40, which is more preferable in terms of miniaturization. Furthermore, here, the upper edge and upper end of the optical element 40 refer to the same part, and the lower edge and lower end of the optical element 40 refer to the same part. In particular, in Figure 5 In the front view of the optical element 40 shown in (b), the lower side 43 is formed into a shape that convexes downwards gently, and the entire lower side 43 is also referred to as the lower end.

[0077] Therefore, based on the correlation between the thickness ratio and the width of the display element 30 in the width direction orthogonal to the plane including the height direction and the reference direction N1, the width of the display element 30 and the width of the optical element 40 are compared. Figure 5 The value of the thickness ratio when the upper ends of (b) are equal (=4.0) is set as the upper limit of the thickness ratio.

[0078] Furthermore, when viewing the optical element 40 from the front, the width W2 of the lower end (lower side 43) of the optical element 40 is smaller than the width W1 of the upper end (upper side). The structure in which the upper limit of the thickness ratio is set to the value of the thickness ratio (=1.7) when the width of the display element 30 is equal to the width W2 of the lower end (lower side 43) of the optical element 40, can make the portion of the housing 20 that houses the display element 30 facing the lower side 43 smaller, and is therefore more preferable.

[0079] Furthermore, the relationship between the ratio of the first thickness t1 to the second thickness t2 (thickness ratio) and the depth of the housing 20 from the optical element 40 to the emission portion 22 was simulated. Figure 6 The results are shown in the figure. Figure 6 This is a graph showing the relationship between the thickness ratio of the optical element and the depth of the housing according to Embodiment 1. Figure 6 In the diagram, the horizontal axis represents the thickness ratio (t1 / t2), and the vertical axis represents the depth of the housing 20. Furthermore, the depth of the housing 20 is defined as the distance (interval) from the reference position P on the second surface 42 of the optical element 40 to the emission portion 22. Figure 6It is known that when the thickness ratio is between 4 and 1.3, there is a tendency for the depth to decrease as the thickness ratio decreases, while when the thickness ratio is below 1.3, there is a tendency for the depth to increase as the thickness ratio decreases. Furthermore, it is known that when the thickness ratio is less than 0.5, the depth tends to exceed the depth Dmax when the thickness ratio is 4. Therefore, by setting the thickness ratio to 0.5 or higher, it is possible to suppress the excessive depth.

[0080] Therefore, based on the correlation between the thickness ratio and the depth of the shell 20 in the depth direction (Z-axis direction) which is orthogonal to the same height direction (Y-axis direction) and width direction (X-axis direction), the thickness ratio is set to the lower limit if the depth is the same as the depth Dmax of the shell 20 when the upper limit (=4.0) (=Dmax) and smaller than the upper limit (=0.5).

[0081] As described above, the display device 10 according to this embodiment includes: a display element 30 having a display surface 31; an optical element 40 having a first surface 41 and a second surface 42 facing the first surface 41, light emitted from the display surface 31 is incident on the first surface 41, reflected by the second surface 42 in a direction different from the display surface 31, and emitted from the first surface 41; and a housing 20 housing the display element 30 and the optical element 40. The first surface 41 and the second surface 42 are formed as concave curved surfaces recessed toward the incident direction of light. When the optical element 40 is arranged such that its height direction is along the vertical direction, in a cross-sectional view of the optical element 40 including the vertical direction, when the first thickness at the upper end of the optical element 40 in the reference direction N1 parallel to the normal N of the origin of the second surface 42 is set as t1, and the second thickness at the lower end of the optical element 40 in the reference direction N1 is set as t2, and t1 / t2 is set as the thickness ratio, (i) based on the thickness ratio and the thickness of the display element 30 in the same direction including the height direction and the reference direction... The correlation between the width in the width direction orthogonal to the plane of N1 is used to set the thickness ratio when the width of the display element 30 is equal to the width of the optical element 40 as the upper limit of the thickness ratio. (ii) Based on the correlation between the thickness ratio and the depth of the housing 20 in the depth direction orthogonal to the plane including the height and width directions, the thickness ratio that makes the depth of the housing 20 the same as the depth Dmax of the housing 20 when the upper limit is reached, and smaller than the upper limit, is set as the lower limit of the thickness ratio. The thickness ratio satisfies the relationship that is above the lower limit and below the upper limit.

[0082] Based on this, the width of the display element 30 can be made to be less than or equal to the width of the optical element 40 without increasing the effective display area of ​​the display element 30. In other words, the enlargement of the display element 30 can be suppressed. Furthermore, excessive enlargement of the depth of the housing 20, i.e., the distance from the optical element 40 to the emission portion 22 of the housing 20, can also be suppressed. Therefore, miniaturization can be achieved for the device as a whole.

[0083] Furthermore, in the display device 10, the thickness ratio satisfies the relationship of 0.5 or more and 4.0 or less.

[0084] Based on this, since the range of the thickness ratio that can suppress the enlargement of the display element 30 and the enlargement of the depth of the housing 20 is determined, a specific design policy for miniaturization can be obtained.

[0085] Furthermore, the display device 10 includes a mirror 50 positioned opposite the display surface 31 and the first surface 41. Because the mirror 50 is positioned opposite the display surface 31 of the display element 30 and the first surface 41 of the optical element 40, light emitted from the display surface 31 can be reflected by the mirror 50 and enter the optical element 40 from the first surface 41. This allows for an increase in the optical path length while minimizing the size of the device.

[0086] Furthermore, mirror 50 is a plane mirror. Therefore, by using a plane mirror that is easy to manufacture as mirror 50, it is possible to extend the optical path length while suppressing manufacturing costs.

[0087] In addition, when viewed from the front, the lower edge 43 of the optical element 40 is formed as a curved shape that protrudes downwards.

[0088] Therefore, since the lower edge 43 of the optical element 40 is formed into a downward-protruding curve, the effective display area of ​​the display element 30 can be reduced. Thus, the display element 30 can be miniaturized, and the miniaturization of the device itself can be further promoted.

[0089] In addition, the optical element 40 is formed to be symmetrical about the left and right when the height direction of the optical element 40 is arranged along the vertical direction.

[0090] Based on this, since the optical element 40 is formed to be symmetrical from left to right, it is possible to suppress image distortion in the left-right direction (width direction).

[0091] Furthermore, in the display device 10, when the optical element 40 is viewed from the front, the width of the lower end of the optical element 40 is smaller than the width of the upper end, and the upper limit of the thickness ratio t1 / t2 is the value of the thickness ratio t1 / t2 when the width of the display element 30 is equal to the width of the lower end of the optical element 40.

[0092] Based on this, the width of the display element 30 can be made smaller than the width of the lower side 43 of the optical element 40 when its shape is an inverted trapezoid when viewed from the front. Therefore, the enlargement of the display element 30 can be further suppressed, and thus the overall device can be further miniaturized.

[0093] In addition, the thickness ratio in the display device 10 is 1.7 or less.

[0094] Based on this, since an upper limit is determined on the thickness ratio that can further suppress the enlargement of the display element 30, a more specific design policy for miniaturization can be obtained.

[0095] Furthermore, in Embodiment 1, an optical element 40 with its lower side 43 formed as a downwardly protruding curved shape is illustrated, but the lower side of the optical element may also be straight or a downwardly protruding curved shape.

[0096] In addition, in Embodiment 1, the case where mirror 50 is a plane mirror is illustrated, but it can also be a curved mirror.

[0097] [Implementation Method 2]

[0098] Next, the display device 10A according to Embodiment 2 will be described. Furthermore, in the following description, the same reference numerals will be used for parts that are the same as in other embodiments, and their descriptions may sometimes be omitted.

[0099] Figure 7 This is a schematic diagram showing the general structure of the display device 10A according to Embodiment 2. Specifically, Figure 7 Is with Figure 2 The corresponding diagram. (For example...) Figure 7 As shown, the display device 10A includes a housing 20, a display element 30, and an optical element 40, but does not include a mirror 50. Furthermore, within the housing 20, the display element 30 is disposed near the corner of the emission portion 22 in the positive Y-axis direction, and the optical element 40 is disposed near the inner surface in the negative Z-axis direction.

[0100] With this structure, there is no need to have a mirror 50 in the optical path of Op2, thus simplifying the structure.

[0101] [Implementation Method 3]

[0102] Next, the display device 10B according to Embodiment 3 will be described. Figure 8 This is a schematic diagram showing the outline structure of the display device 10B according to Embodiment 3. Specifically, Figure 8 Is with Figure 2 The corresponding diagram.

[0103] like Figure 8 As shown, the display device 10B includes a housing 20, a display element 30, an optical element 40, a mirror 50, and a transflective mirror 60. Inside the housing 20, the mirror 50 is positioned near its inner surface in the negative Y-axis direction, the display element 30 is positioned near its bottom surface in the positive Z-axis direction, and the optical element 40 is positioned near its top surface in the positive Z-axis direction. The optical element 40 is positioned such that its first surface 41 and second surface 42 protrude towards the top surface. Furthermore, inside the housing 20, the transflective mirror 60 is positioned between the display element 30 and the optical element 40. The transflective mirror 60 is positioned such that it reflects light from the display element 30, transmits light reflected by the mirror 50, and reflects light reflected by the optical element 40. Therefore, the light emitted from the display surface 31 of the display element 30 is reflected by the semi-transparent mirror 60 and then by the mirror 50. After passing through the semi-transparent mirror 60, it is reflected by the optical element 40 and further reflected by the semi-transparent mirror 60 before being emitted from the emission section 22. As a result, the optical path length of the light path Op3 can be further extended.

[0104] In this way, the display device 10B according to Embodiment 3 has a semi-transparent mirror 60 disposed between the mirror 50 and the optical element 40. Therefore, light emitted from the display surface 31 can be reflected by the semi-transparent mirror 60 and guided to the mirror 50. Furthermore, the light reflected by the mirror 50 passes through the semi-transparent mirror 60, is reflected by the optical element 40, and is reflected again by the semi-transparent mirror 60. As a result, the optical path length can be further extended.

[0105] Here, the semi-transparent mirror 60 can be configured with a reflective polarizer and a λ / 4 retardation plate disposed on the glass substrate (in this case, the reflective polarizer is disposed on the display element 30 side of the glass substrate, and the λ / 4 retardation plate is disposed on the optical element 40 side). Alternatively, it can be configured with a λ / 4 retardation plate disposed on the mirror 50. With such a configuration, when using a display element 30 with a polarizer on the display surface 31, the light emitted from the display element 30 can be effectively guided towards the driver 2.

[0106] [Implementation Method 4]

[0107] Next, the display device 10C according to Embodiment 4 will be described. Figure 9 This is a schematic diagram showing the outline structure of the display device 10C according to Embodiment 4. Specifically, Figure 9 (a) is a perspective view showing the optical element 40 and display element 30c included in the display device 10C. Figure 9 (b) is a front view showing the optical element 40 and the display element 30c. Figure 9 In (a), the ejection portion 22 of the housing 20 is also illustrated. Furthermore, in Figure 9 For ease of understanding, the record of mirror 50 has been omitted.

[0108] like Figure 9 As shown, the display element 30c is formed in a curved shape corresponding to the curve of the lower edge 43 of the optical element 40, and is positioned opposite to the lower edge 43. Therefore, the display surface 31c of the display element 30c is also curved. For example, in Figure 9 In (b), a flat display element 30 is illustrated with a double-dotted line. In the case of the flat display element 30, its two ends in the X-axis direction are far away from the optical element 40, and the corresponding gap becomes useless space. On the other hand, if it is a curved display element 30c, the display element 30c can be arranged along the lower edge 43 of the optical element 40, thereby suppressing useless space.

[0109] In the display device 10C according to Embodiment 4, the display element 30c is formed as a curved plate corresponding to the curve of the lower edge 43 and is disposed at a position facing the lower edge 43. Because the display element 30c is formed as a curved plate corresponding to the curve of the lower edge 43 of the optical element 40, the display element 30c can be disposed along the lower edge 43 of the optical element 40. This reduces unused space and further promotes miniaturization of the device itself.

[0110] [Implementation Method 5]

[0111] Next, the optical element 40d according to Embodiment 5 will be described. Figure 10 This is a perspective view showing the optical element 40d according to Embodiment 5. Figure 10 As shown, the optical element 40d has a first light-absorbing portion 46d on its side surface 44d, excluding the first surface 41d and the second surface 42d. Specifically, the side surface 44d is formed to surround the first surface 41d and the second surface 42d, and the first light-absorbing portion 46d is provided on the entire surface of the side surface 44d. Figure 10 In the diagram, the first light-absorbing portion 46d is indicated by a dotted shading. The first light-absorbing portion 46d is formed to absorb more light than the first surface 41d and the second surface 42d. Specifically, the first light-absorbing portion 46d is a black layer stacked on the side surface 44d. As a result, light is absorbed at the first light-absorbing portion 46d.

[0112] In this way, in the optical element 40d according to Embodiment 5, the side surface 44d (other than the first surface 41d and the second surface 42d) has a first light-absorbing portion 46d that absorbs more light than the first surface 41d and the second surface 42d.

[0113] Based on this, a first light-absorbing portion 46d is provided on the side 44d of the optical element 40d, excluding the first surface 41d and the second surface 42d, thereby suppressing the reflection and transmission of light at the side 44d. This suppresses unwanted light emission, thereby improving image quality.

[0114] Furthermore, the first light-absorbing portion 46d can absorb more light than the first surface 41d and the second surface 42d, and the manner in which it is made is arbitrary. For example, the first light-absorbing portion 46d can be a colored layer other than black, can be composed of a light-shielding sheet, or can be a structure with a rougher surface roughness compared to the first surface 41d and the second surface 42d.

[0115] [Implementation Method 6]

[0116] Next, the optical element 40e according to Embodiment 6 will be described. Figure 11 This is a front view showing the optical element 40e according to embodiment 6. Figure 11 In the diagram, the outline of the second surface 42e is shown using dashed lines. For example... Figure 11 As shown, the area of ​​the first surface 41e of the optical element 40e is smaller than the area of ​​the second surface 42e. A strip-shaped second light-absorbing portion 47e is disposed around the periphery of the first surface 41e. Figure 11 In the diagram, the second light-absorbing portion 47e is indicated by a dotted shade. The area A (first surface 41e) surrounded by the second light-absorbing portion 47e corresponds to the effective display area of ​​the display element 30. That is, area A is the range projected by the maximum image (light) irradiated from the display surface 31 of the display element 30. The second light-absorbing portion 47e, when viewed from the front, is the size that includes the second surface 42e. Specifically, the shape of the second surface 42e is incorporated in such a way that it overlaps with the frame formed by the second light-absorbing portion 47e. The second light-absorbing portion 47e is formed to absorb more light than area A. Specifically, the second light-absorbing portion 47e is a light-shielding sheet overlapping the first surface 41e. As a result, light is absorbed at the second light-absorbing portion 47e.

[0117] In this way, in the optical element 40e according to embodiment 6, the area of ​​the first surface 41e is smaller than the area of ​​the second surface 42e. At the periphery of the first surface 41e, except for the range A in the optical element 40e corresponding to the effective display area of ​​the display element 30, there is a second light-absorbing portion 47e that absorbs more light than the first surface 41e and the second surface 42e. The second light-absorbing portion 47e has a size that includes the second surface 42e when viewed from the front.

[0118] Based on this, a second light-absorbing portion 47e, which is sized to include the second surface 42e, is provided around the periphery of the first surface 41e, except for the range A corresponding to the effective display area of ​​the display element 30. This can suppress the ambient light emission of the first surface 41e or the second surface 42e.

[0119] Furthermore, the second light-absorbing portion 47e can be made to absorb more light than range A, and its form can be arbitrary. For example, the second light-absorbing portion 47e can be a colored layer such as a black layer, or it can be a structure with a rougher surface roughness compared to range A.

[0120] [Implementation Method 7]

[0121] Next, the optical element 40f according to Embodiment 7 will be described. Figure 12 This is a structural diagram showing the optical element involved in Embodiment 7. Figure 12 (a) is a three-dimensional view of the optical element. Figure 12 (b) is a cross-sectional view of the optical element. Furthermore, Figure 12 (a) is from and Figure 10 A stereoscopic image obtained by observing from the same direction.

[0122] like Figure 12 As shown, in the optical element 40f having a first surface 41f and a second surface 42f, a frame portion 48f is provided on the second surface 42f. Figure 12 The diagram shows a structure where the frame portion 48f is a black frame. The frame portion 48f is formed along the outer periphery of the second surface 42f with a predetermined width. Specifically, the frame portion 48f is a strip-shaped light-shielding sheet arranged along the outer periphery of the second surface 42f, and a reflective film is formed only in the areas of the second surface 42f where the light-shielding sheet is not formed. Thus, a visual observer can visually confirm the black frame in the image.

[0123] In this way, in the optical element 40f according to embodiment 7, a frame portion 48f is provided on the second surface 42f.

[0124] Based on this, a viewing distance difference is generated between the image emitted from the display device 10 and the frame portion 48f, thus enabling visual confirmation of the image with increased depth.

[0125] Furthermore, the 48f frame is not limited to a black frame; it can be used as long as it is consistent with... Figure 11 The area shown, A, can absorb more light, and its shape and color can be arbitrary. For example, the frame portion 48f can also be a dark color such as gray or dark blue. In addition, the frame portion 48f can also be a colored layer such as a black layer, or it can be a structure with a rougher surface roughness compared to area A.

[0126] Furthermore, the frame portion 48f is not limited to a structure disposed on the entire outer periphery of the second surface 42f; for example, it may be a structure disposed only on the lower edge or a portion of the outer periphery.

[0127] In addition, such as Figure 12 As shown, in the optical element 40f having a first surface 41f and a second surface 42f, an anti-reflective film 49f is provided on the first surface 41f. The anti-reflective film 49f is a so-called AR (Anti-Reflection) coating. Specifically, the anti-reflective film 49f is formed, for example, by adhering an AR coating film to the first surface 41f. Furthermore, the anti-reflective film 49f is not limited to the structure of adhering an AR coating film to the first surface 41f; for example, it can also be formed by coating the first surface 41f with an AR coating agent, or by vapor deposition. In addition, in the optical element 40f according to Embodiment 7, an anti-reflective film 49f is provided on the first surface 41f.

[0128] Based on this, the reflection at the first surface 41f is suppressed by the anti-reflective film 49f, so the driver 2 can easily observe the virtual image.

[0129] Furthermore, as an example of an anti-reflective unit, an anti-reflective film 49f is shown here, but the anti-reflective unit can be any type as long as it can prevent reflection from the first surface 41f. For example, it can also be used as an anti-reflective unit by forming fine irregularities on the first surface.

[0130] [Other implementation methods, etc.]

[0131] The above description illustrates one or more embodiments of the display device involved in this disclosure, but this disclosure is not limited to these embodiments. Various modifications to these embodiments that are conceivable to those skilled in the art, and combinations of constituent elements from different embodiments, can also be included within the scope of one or more embodiments of this disclosure, provided they do not depart from the spirit of the disclosure.

[0132] Industrial availability

[0133] This disclosure can be used in display devices and the like for displaying images.

[0134] Explanation of reference numerals in the attached figures

[0135] 1: Vehicle; 2: Driver; 10, 10A, 10B, 10C: Display device; 20: Housing; 22: Ejection section; 30, 30c: Display element; 31, 31c, 31z: Display surface; 32, 32z: Effective display area; 33: Long side; 40, 40d, 40e, 40f, 40z: Optical element; 41, 41d, 41e, 41f, 41z: First surface; 42, 42d, 42e, 42f, 4 2z: Second side; 43, 43z: Bottom; 44d: Side; 46d: First light-absorbing part; 47e: Second light-absorbing part; 48f: Frame; 49f: Anti-reflective film (anti-reflective unit); 50, 50z: Mirror; 60: Semi-transparent mirror; A: Range; L1: First reference value; L2: Second reference value; L10, L11: Line; N: Normal; N1: Reference direction; Op1, Op2, Op3: Optical path; P: Reference position.

Claims

1. A display device comprising: A display element having a display surface; An optical element having a first surface and a second surface facing the first surface, wherein light emitted from the display surface is incident on the first surface, reflected by the second surface in a direction different from the display surface, and exits from the first surface; and The housing contains the display element and the optical element. in, The first surface and the second surface are formed as concave curved surfaces that are recessed towards the incident direction of the light. When the optical element is configured such that its height direction is along the vertical direction, in a cross-sectional view of the optical element including the vertical direction, when the first thickness at the upper end of the optical element in a reference direction parallel to the normal to the origin of the second surface is set as t1, and the second thickness at the lower end of the optical element in the reference direction is set as t2, and t1 / t2 is set as the thickness ratio, (i) Based on the correlation between the thickness ratio and the width of the display element in the width direction orthogonal to the plane including the height direction and the reference direction, the value of the thickness ratio when the width of the display element is equal to the width of the optical element is set as the upper limit of the thickness ratio. (ii) Based on the correlation between the thickness ratio and the depth of the housing in a depth direction orthogonal to the plane including the height direction and the width direction, the value of the thickness ratio that makes the depth of the housing the same as the upper limit and is smaller than the upper limit is set as the lower limit of the thickness ratio. The thickness ratio satisfies the relationship that it is above the lower limit and below the upper limit.

2. The display device according to claim 1, wherein, The thickness ratio satisfies the relationship of being greater than 0.5 and less than 4.

0.

3. The display device according to claim 1 or 2, wherein, It has a mirror positioned opposite to the display surface and the first surface.

4. The display device according to claim 3, wherein, The mirror in question is a plane mirror.

5. The display device according to claim 3, wherein, It has a semi-transparent, semi-reflective mirror disposed between the mirror and the optical element.

6. The display device according to claim 1 or 2, wherein, When viewed from the front, the lower edge of the optical element is formed as a downward-protruding curve.

7. The display device according to claim 6, wherein, The display element is formed into a curved plate shape corresponding to the curve of the lower side, and is positioned opposite to the lower side.

8. The display device according to claim 1 or 2, wherein, The optical element is formed to be symmetrical about the left and right sides when it is configured such that the height direction of the optical element is along the vertical direction.

9. The display device according to claim 1 or 2, wherein, In the optical element, the surfaces other than the first and second surfaces have a first light-absorbing portion that absorbs more light than the first and second surfaces.

10. The display device according to claim 1 or 2, wherein, The area of ​​the first face is smaller than the area of ​​the second face. Around the periphery of the first surface, in addition to the area corresponding to the effective display area of ​​the display element, there is a second light-absorbing portion that absorbs more light than that area. The second light-absorbing portion has a size that includes the second surface when viewed from the front.

11. The display device according to claim 1 or 2, wherein, When viewed from the front, the width of the lower end of the optical element is smaller than the width of the upper end. The upper limit of the thickness ratio is set as the value of the thickness ratio when the width of the display element is equal to the width of the lower end of the optical element.

12. The display device according to claim 11, wherein, The thickness ratio is 1.7 or less.

13. The display device according to claim 1 or 2, wherein, A frame is provided on the second side.

14. The display device according to claim 1 or 2, wherein, An anti-reflection unit is provided on the first surface of the optical element.

Images