JP2016166917A - Mirror display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mirror display capable of increasing transmission amount of light emitted from a display while enhancing the reflectance of external light.SOLUTION: A mirror display 1 includes: a display part 10 that emits light for displaying images; a mirror part 30 which includes a reflection layer 32 disposed over the display part 10 at the display plane 10a side, and plural fine windows 33 formed in the reflection layer 32; and a lens array part 20 which is disposed between the display part 10 and the mirror part 30, and which includes plural compound parabolic lenses 21 for focusing the light on each of the plural fine windows 33, which is emitted from the display part 10 toward the mirror part 30.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a mirror display.

  Conventionally, a device (mirror display) in which the front side of a thin display such as a liquid crystal display is closed with a half mirror has been put into practical use. For example, a mirror display is installed in a housing or a wall that blocks outside light, and the front side space of the display is closed with a half mirror having a light reflectance of about 50%, thereby setting the display side to the installation space. It has a darker configuration. In such a mirror display, the half mirror functions as a mirror when the display is not operating. When an image is displayed on the display screen, the image is visually recognized from the front side of the half mirror by transmitting the backlight of the display to the front side through the half mirror.

  In the conventional mirror display, since the image is displayed by transmitting the backlight light to the front side through the half mirror, there is a half mirror having an average visible light reflectance of about 50% and an average transmittance of about 25%. It is used. The conventional mirror display has a drawback that the screen is darker than a normal mirror. Due to the influence of the thickness of the metal film constituting the half mirror, the screen tends to appear yellowish as a whole. If the reflectance of light by the half mirror is increased to improve the function as a mirror, the amount of light transmitted through the half mirror is reduced, and the screen becomes dark when an image is displayed. Therefore, in order to improve the function as a mirror, it is required to increase the amount of transmitted light when displaying an image while increasing the reflectance of light.

JP 2011-071973 A Japanese Patent No. 4543301

  The problem to be solved by the present invention is to provide a mirror display that can increase the transmission amount of light emitted from the display while increasing the reflectance of external light.

  The mirror display of the embodiment includes a display unit that emits light for displaying an image, a reflective layer disposed on the display surface side of the display unit, and a mirror unit that includes a plurality of fine windows formed in the reflective layer; A lens array unit that is disposed between the display unit and the mirror unit and includes a plurality of compound parabolic lenses that individually collect light emitted from the display unit toward the mirror unit into a plurality of fine windows. doing.

It is a figure which shows the 1st structural example of the mirror display by embodiment. It is a figure which shows the compound paraboloid lens in the mirror display shown in FIG. It is a figure which shows the 2nd structural example of the mirror display by embodiment. It is a figure which shows the 1st modification of the mirror display by embodiment. It is a figure which shows the 2nd modification of the mirror display by embodiment. It is a figure which shows the 1st manufacturing process of the mirror display by embodiment. It is a figure which shows the 2nd manufacturing process of the mirror display by embodiment.

  Hereinafter, a mirror display according to an embodiment will be described with reference to the drawings. In each embodiment, substantially the same constituent parts are denoted by the same reference numerals, and the description thereof may be partially omitted. The drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each part, and the like are different from the actual ones. Unless otherwise specified, the term indicating the direction such as up and down in the description indicates the relative direction when the display surface side of the display unit, which will be described later, is up, and the actual direction based on the gravitational acceleration direction And may be different.

  FIG. 1 is a cross-sectional view illustrating a configuration of a mirror display according to an embodiment. A mirror display 1 shown in FIG. 1 includes a display unit 10, a lens array unit 20, and a mirror unit 30. The display unit 10 has a display surface 10a and a non-display surface 10b. The display unit 10 emits light for displaying an image from the display surface 10a. That is, the display unit 10 includes pixels 11A, 11B, and 11C, and a color image is displayed by light emitted from these pixels 11A to 11C.

  Examples of the display unit 10 include a backlight type liquid crystal display including a liquid crystal cell and a backlight module. The backlight type liquid crystal display includes a backlight module (not shown) disposed on the non-display surface 10b side. In the backlight type liquid crystal display, light emitted from the backlight module is transmitted through the pixels 11A, 11B, and 11C, and a color image is displayed by the transmitted light. The display unit 10 is not limited to a backlight type liquid crystal display, and may be a plasma display, a field emission display, an organic electroluminescence (EL) display, a rear projection display, or the like.

  On the display surface 10 a side of the display unit 10, a mirror unit 30 is arranged. The mirror unit 30 has a flat plate 31 that is transparent to visible light. A reflective layer 32 is formed on one surface (back surface) 31 a of the transparent flat plate 31. The mirror unit 30 is arranged so that the reflective layer 32 is located on the display surface 10 a side of the display unit 10. The surface of the reflective layer 32 is a mirror surface. When the display unit 10 is not operating, the mirror unit 30 reflects light (external light) OL incident on the surface (front surface) 31b opposite to the formation surface 31a of the reflective layer 32 of the transparent flat plate 31. It functions as a mirror. The transparent flat plate 31 can be omitted depending on the formation process (described later) of the reflective layer 32 to be applied.

  The material for forming the transparent flat plate 31 may be either an inorganic material or an organic material. As the transparent flat plate 31, a highly transparent glass plate or acrylic resin plate is preferably used. The material of the reflective layer 32 is not particularly limited as long as it is a material that reflects visible light. For the reflective layer 32, a metal film made of a metal such as aluminum, silver, chromium, nickel, zinc or the like having a high visible light reflectivity or an alloy containing one or more of these metals, or a dielectric multilayer film is used. The thickness of the reflective layer 32 is not particularly limited as long as it can reflect visible light. In order to obtain high mirror performance in the mirror unit 30, it is preferable that the reflectance of the reflective layer 32 is high. From such a point, it is preferable that the reflective layer 32 has such a thickness that the transmittance of light having a wavelength of 550 nm is 5% or less.

  The reflective layer 32 has a plurality of fine windows 33. The fine window 33 is formed by partially opening the reflective layer 32. The shape of the fine window 33 is not particularly limited, and a square, a rectangle, a rhombus, a hexagon, an octagon, a circle, an ellipse, or the like can be applied. The fine window 33 functions as a window (transmission hole) that transmits light (display light) DL emitted from the display unit 10. Therefore, the fine window 33 is made of a material that transmits visible light. The fine window 33 may be hollow or may be filled with a transparent material such as glass, transparent resin, or metal oxide. The fine window 33 preferably has a transmittance of 50% or more in the visible light region so as to transmit the display light DL with a small loss.

  When the mirror unit 30 including the reflective layer 32 in which a plurality of fine windows 33 are formed functions as a mirror, the fine windows 33 preferably have a size that cannot be recognized by human vision. Human vision has a property called area effect, in which the smaller the image area, the more difficult it is to distinguish color differences. On the other hand, there is a limit of spatial resolution in vision, and it is said that the limit is usually about 1/16 mm (62.5 μm). Due to such physiological characteristics of vision, a fine window formed in a state of being less than the limit value of spatial resolution and isolated from the mirror cannot be recognized by visual recognition by the human eye. The reflective layer 32 having such a minute window 33 is recognized as a mirror having a reflectance defined by the aperture ratio of the minute window 33.

  The size of the fine window 33 is preferably 1/16 mm or less. The size of the fine window 33 indicates the diameter of a circle in the case of a circle, the length of the long axis in the case of an ellipse, and the diameter of a circle inscribed in the polygon in the case of a polygon. For example, when one side of the pixel 11 of the display unit 10 is 200 μm, one minute window 33 is associated with one pixel 11, and the square minute windows 33 having one side of 20 μm are arranged in a square lattice shape, The aperture ratio of the window 33 is only 1%. The reflective layer 32 having such a fine window 33 exhibits substantially the same optical characteristics as a normal mirror. However, when the size of the fine window 33 is reduced to about the wavelength of visible light, the wave nature of light becomes remarkable and an abnormal light transmission phenomenon occurs. For this reason, the light transmission characteristics change, and the condensed light cannot be emitted efficiently. Furthermore, the formation cost of the fine window 33 increases. The size of the fine window 33 is preferably 1 μm or more. The size of the fine window 33 can be confirmed with an optical microscope or the like.

  When the ratio of the fine windows 33 in the reflective layer 32 is defined as the aperture ratio, the aperture ratio is preferably in the range of 0.1% to 50%. When the aperture ratio of the reflective layer 32 is less than 0.1%, it is difficult to efficiently emit display light from the aperture. When the aperture ratio of the reflective layer 32 exceeds 50%, even in the case of a perfect reflector (reflectance 100%), the reflectivity decreases by the aperture ratio, and the reflectivity of the reflective layer 32 becomes less than 50%. . In this case, it is difficult to obtain a mirror that is more reflective than a half mirror. The arrangement of the fine windows 33 may be periodic or random. The periodic array may be a square lattice or a triangular lattice. In consideration of the aspect ratio of the pixel, the period may be different in the period axis direction. If the fine windows 33 are periodically arranged, the mirror image may be blurred due to light diffraction when a plane wave is incident on the mirror unit 30. In order to avoid such a problem, although the transmittance of the display light is lowered, the arrangement of the fine windows 33 may be a random arrangement to avoid the diffraction phenomenon.

  Between the display unit 10 and the mirror unit 30, there are a plurality of compound parabolic lenses 21 that individually collect light emitted from the display unit 10 toward the mirror unit 30 onto a plurality of fine windows 33. A lens array unit 20 is disposed. The lens array unit 20 functions as a condenser that efficiently guides light emitted from the display unit 10 to the individual fine windows 33. The compound parabolic lens 21 and the fine window 33 have a one-to-one correspondence. The optical symmetry of the mirror unit 30 is broken by the addition of the lens array unit 20 and has a high transmittance with respect to the light emitted from the display unit 10 side on the back surface.

  In general, the light emitted from the display unit 10 has a certain directivity distribution. The directivity distribution of light emitted from the display unit 10 is obtained by measuring the luminance at each angle using a luminance meter. The angular width that is ½ of the measured peak intensity of the directivity distribution is called the half-value width of the directivity distribution. A half value of the half-value width of the light directivity distribution is called a half-value half width. The smaller the half width at half maximum of the directivity distribution, the closer to the parallel light, and the larger the half width, the closer to the completely diffused light. The radiated light in a general liquid crystal display is light (diffused light) having a FWHM of approximately 5 degrees to 30 degrees in the directivity distribution. In order to efficiently condense the diffused light emitted from the display unit 10 onto the fine window 33, it is necessary to design a concentrator in consideration of the directivity distribution of the light of the display unit 10.

  In the mirror display 1 of the embodiment, a compound parabolic lens 21 is applied as a collector of diffused light emitted from the display unit 10. As shown in FIG. 2, the compound parabolic lens 21 includes a first surface (large aperture surface) 21 a on which light is incident, a second surface (small aperture surface) 21 b on which light is emitted, and a large aperture surface. It has a parabolic side surface (parabolic surface) 21c that connects 21a and the small-diameter surface 21b. Although FIG. 2 shows the case where both the large-diameter surface 21a and the small-diameter surface 21b are circular, the present invention is not limited to this. The shape of the large-diameter surface 21a and the small-diameter surface 21b may be a polygon such as a square, a rectangle, a rhombus, a hexagon, an octagon, or an ellipse.

  The compound parabolic lens 21 is an optical element that reflects the light L incident at a certain range of angle from the large-diameter surface 21a by the parabolic surface 21c on the side surface and collects it on the small-diameter surface 21b. The width of the large-diameter surface 21a is D1 [unit: μm], the width of the small-diameter surface 21b is D2 [unit: μm], the distance between the large-diameter surface 21a and the small-diameter surface 21b is L [unit: μm], The refractive index inside the paraboloid 21c is n1, and the angle formed by the light L incident on the large-diameter surface 21a from the air and the center line A of the compound paraboloid lens 21 is φ [unit: degree]. When the maximum angle that can be focused on the small-aperture surface 21b by the object lens 21 is φmax, the compound paraboloid lens 21 satisfies the following expressions (A), (B), and (C): It is.

φ′max = sin ⁻¹ (sin φmax / n1) (A)
D2 = D1 · sinφ′max (B)
L = (D1 + D2) / 2 · tan φ′max (C)
The widths D1 and D2 of the large-diameter surface 21a and the small-diameter surface 21b of the compound parabolic lens 21 are the diameter of a circle when the surfaces 21a and 21b are circular, and the length of the long axis when the surfaces are elliptical. In the case of a polygon, it refers to the diameter of a circle inscribed in the polygon.

  The above-mentioned compound parabolic lens 21 is superior in the ability to collect diffused light compared to a normal spherical lens, a diffractive lens, or the like. That is, even when the half-value half width (θ) of the directivity distribution of the light emitted from the display unit 10 is, for example, 20 ° or more, the light having such a spread can be efficiently collected. The upper limit of the half-value half width (θ) of the light directivity distribution is not particularly limited, but is usually about 30 ° as described above. A lens array unit 20 in which such compound parabolic lenses 21 are arrayed is disposed between the display unit 10 and the mirror unit 30, and individual fine windows 33 of the reflective layer 32 are formed by the individual compound parabolic lenses 21. By condensing the light, it is possible to provide the mirror display 1 that is excellent in the reflectivity of the external light OL and the transparency of the display light DL. However, the compound parabolic lens 21 can also be applied to the case of diffused light or parallel light in which the half-width (θ) of the directivity distribution of light is less than 20 °. In such a case, the compound parabolic surface is used. Increasing the light condensing property with the lens 21 improves the brightness of the screen displayed when the display unit 10 operates.

The compound parabolic lens 21 includes a width D1 of the large-diameter surface 21a, a width D2 of the small-diameter surface 21b, a distance L between the large-diameter surface 21a and the small-diameter surface 21b, and a refractive index n1 inside the parabolic surface 21c. It is preferable that the following expressions (1), (2), and (3) are satisfied with respect to the half-value half width θ of the directivity distribution of the display light DL.
θ ′ = sin ⁻¹ (sin θ / n1) (1)
D1 ≧ D2 ≧ D1 · sin θ ′ (2)
L ≦ (D1 + D2) / 2 · tan θ ′ (3)

  The width D1 of the large-diameter surface 21a, the width D2 of the small-diameter surface 21b, and the distance L between the large-diameter surface 21a and the small-diameter surface 21b of the compound parabolic lens 21 are represented by the expressions (1) to (3). Is not satisfied, the incident light is collected at an angle smaller than the half-value half-width θ of the directivity distribution of the display light DL. Since the light that has not been collected cannot pass through the fine window 33, the transmittance of the display light DL decreases. It is preferable that the shape of the small-diameter surface 21 b of the compound parabolic lens 21 substantially matches the shape of the fine window 33. Thereby, the light condensed by the compound parabolic lens 21 can be efficiently transmitted through the fine window 33. The structure of the lens array unit 20 can be analyzed by observing the cross-sectional shape when the lens array unit 20 is cut with an optical microscope, a scanning electron microscope, or the like and measuring the size using a length measuring tool.

  In the lens array unit 20, the light incident from the large-diameter surface 21a of the compound parabolic lens 21 is reflected by the paraboloid 21c on the side surface and condensed on the small-diameter surface 21b. The reflection of light by the paraboloid 21c is performed entirely at the interface between the lens medium 22 forming the compound paraboloid lens 21 and the lens outer medium (surrounding medium) 23 disposed around the lens medium 22. Reflection can be used. A material whose refractive index n1 is larger than the refractive index n2 of the lens external medium 23 is applied to the lens inner medium 22. If the refractive index n2 of the lens outer medium 23 is larger than the refractive index n1 of the lens inner medium 22, a part of the light incident from the large diameter surface 21a is reflected by Fresnel at the interface, but most of the light is transmitted to the lens outer medium 23. Therefore, the light condensed on the small diameter surface 21b is reduced.

  The material of the compound parabolic lens 21 (in-lens medium 22) is preferably transparent to visible light emitted from the display unit 10. As a material for forming the compound parabolic lens 21, a general transparent material such as glass, transparent resin, or metal oxide can be used. If the compound paraboloid lens 21 has low transparency with respect to visible light, the light emitted from the display unit 10 is absorbed before being focused on the fine window 23, and the brightness of the mirror display 1 is lowered. The material of the extra-lens medium 23 is not particularly limited as long as the above refractive index condition is satisfied.

  As another method of reflecting light on the parabolic surface 21 c of the compound parabolic lens 21, there is a method of performing a reflective coating between the lens medium 22 and the lens medium 23. As shown in the second configuration example in FIG. 3, a reflective film 24 may be formed between the lens medium 22 and the lens medium 23. As the material of the reflective film 24, the same material as that for forming the reflective layer 32 can be applied. Even in this case, the material of the compound parabolic lens 21 is preferably transparent to visible light emitted from the display unit 10, and a general transparent material such as glass, transparent resin, or metal oxide is used. Used. When the reflective film 24 is applied, the refractive index of the compound parabolic lens 21 is not particularly limited, and thus the in-lens medium 22 may be air. The material and refractive index of the lens outer medium 23 are not particularly limited.

  The mirror display 1 shown in FIGS. 1 and 3 has a configuration in which one set of compound paraboloid lens 21 and fine window 33 correspond to one pixel 11 of the display unit 10. The correspondence relationship between the pixel 11, the compound parabolic lens 21, and the fine window 33 is not limited to this. As shown in FIG. 4, a plurality of sets of compound paraboloid lenses 21 and fine windows 33 may correspond to one pixel 11 of the display unit 10. Alternatively, as shown in FIG. 5, a plurality of pixels 11 may correspond to one set of compound paraboloid lens 21 and fine window 33. For example, when highly diffusible light is used, the size of the light that can be focused becomes relatively large. Therefore, from the necessity of limiting the area, a plurality of sets of compound paraboloid lenses 21 and microscopic lenses 21 for each pixel 11 The window 33 can be made to correspond.

  In the mirror display 1 of the embodiment, the lens array unit 20 is disposed so as to be in close contact with the display unit 10 and the mirror unit 30. The display unit 10 may be disposed in a state separated from the lens array unit 20 via a spacer, for example. The display unit 10, the lens array unit 20, and the mirror unit 30 may be bonded together via an adhesive layer, or may be arranged so that an air layer is formed therebetween. Alternatively, the display unit 10, the lens array unit 20, and the mirror unit 30 may be bonded using a spacer or the like.

  The mirror display 1 according to the embodiment functions as a mirror by reflecting the external light OL when the display unit 10 is in a non-display state. Although a plurality of fine windows 33 are formed in the reflective layer 32, the fine windows 33 are not visually recognized in the mirror image based on the size of the fine windows 33 as described above. Therefore, it is possible to improve the function of the mirror display 1 as a mirror. That is, the reflectance of the external light OL by the reflective layer 32 having the fine window 33 can be increased without reducing the function as a mirror by reflecting the fine window 33 in the mirror image. Further, unlike the conventional half mirror, the screen does not appear to be yellowish as a whole due to the influence of the thickness of the metal film constituting the mirror.

  On the other hand, when the display unit 10 is in the display state, the light emitted from the display unit 10 toward the mirror unit 30 is condensed on the fine window 33 by the compound parabolic lens 21, thereby efficiently passing through the fine window 33. To Penetrate. When the light DL transmitted through the fine window 33 is emitted to the outside, an image displayed on the display unit 10 is viewed from the front side of the mirror unit 30. And when the display part 10 is a display state, since it has higher light transmittance than the conventional structure using a half mirror, an image can be shown more clearly. As a result, compared to a conventional mirror display using a half mirror, it is possible to provide a mirror display 1 that has both a function as a mirror and a function as a display, and further improves these functions. Become.

  The manufacturing method of the mirror display 1 of embodiment is not specifically limited, A widely well-known manufacturing method can be used. The mirror display 1 of the embodiment is manufactured by the following method, for example. A first manufacturing method of the mirror display 1 shown in FIG. 1 will be described with reference to FIG. First, the reflective layer 32 is formed on the transparent flat plate 31. Subsequently, the fine window 5 is formed in the reflective layer 32 by photolithography (FIG. 6A).

  A positive type photosensitive transparent resin 41 is applied on the reflective layer 3 and is irradiated with diffuse ultraviolet illumination from the transparent flat plate 31 side to be exposed. The photosensitive region of the transparent resin 41 is developed, and the transparent resin 41 is patterned into a composite parabolic shape. An extra-lens medium 23 having a compound parabolic hole 42 is formed (FIG. 6B). Next, the in-lens medium 22 is formed by filling the hole 42 with a transparent resin having a refractive index higher than that of the outside-lens medium 23 (FIG. 6C). In this way, a laminated body of the lens array unit 20 including the compound parabolic lens 21 using total reflection and the mirror unit 30 is obtained. The mirror display 1 of the embodiment is manufactured by disposing a laminated body of the lens array unit 20 and the mirror unit 30 on the display surface 10a side of the display unit 10.

  Next, a second manufacturing method of the mirror display 1 shown in FIG. 1 will be described with reference to FIG. First, a photocurable resin 44 is applied on a transparent support 43, and a mold (transparent master) 45 having a shape obtained by inverting the array shape of the composite parabolic lens 21 is used to form the inside of the lens by an optical nanoimprint method. The medium 22 is formed (FIG. 7A). Subsequently, a photocurable resin having a refractive index smaller than that of the material of the lens medium 22 is applied to form the lens outer medium 23. The lens array unit 20 including the compound parabolic lens 21 is formed (FIG. 7B).

  A reflective layer 32 is formed on the lens array unit 20 (FIG. 7C). Here, a material that reflects visible light and transmits ultraviolet light is applied to the reflective layer 32. As the material of the reflection layer 32, aluminum or silver having a plasma frequency in the ultraviolet region, or an alloy containing at least one of these is used. The plasma frequency of aluminum is around 120 nm, and the plasma frequency of silver is around 320 nm. Aluminum and silver show metallic optical characteristics in the visible light region, and show dielectric optical properties in the ultraviolet region. For this reason, aluminum and silver show a high reflectance in the visible light region and show transparency in the ultraviolet region.

  A positive photosensitive resin layer 46 is formed on the reflection layer 32 described above. When the photosensitive resin layer 46 is irradiated with ultraviolet light from the surface on which the composite parabolic lens 21 is formed, the ultraviolet light is collected by the composite parabolic lens 21 and passes through the reflective layer 32. The photosensitive resin layer 46 is exposed to ultraviolet light that has passed through the reflective layer 32. By developing the exposed photosensitive resin layer 46, a fine hole pattern 47 corresponding to the formation pattern of the fine window 33 is formed in the photosensitive resin layer 46 (FIG. 7D). Using the photosensitive resin layer 46 having the fine hole pattern 47 as an etching mask, the reflective layer 32 is etched to form the fine window 33. By removing the photosensitive resin layer 46, a laminated body of the lens array unit 20 including the compound parabolic lens 21 and the mirror unit 30 is obtained. The mirror display 1 of the embodiment is manufactured by disposing a laminated body of the lens array unit 20 and the mirror unit 30 on the display surface 10a side of the display unit 10.

  Next, a method for manufacturing the mirror display 1 shown in FIG. 3 will be described. First, the optical nanoimprint method is applied in the same manner as in the manufacturing process shown in FIG. 7 to form an in-lens medium 22 (composite parabolic lens 21) on a transparent support. Subsequently, a reflective film 24 is formed by depositing a metal or the like on the lens medium 22. Subsequently, a non-lens medium 23 is formed by applying a transparent resin. The surface of the structure having the in-lens medium 22, the reflection film 24, and the outside lens medium 23 is polished to form the small-diameter surface 21 a of the compound parabolic lens 21. Thereafter, the reflective layer 32 having the fine window 33 is formed in the same manner as the manufacturing process shown in FIG. In this manner, a laminated body of the lens array unit 20 and the mirror unit 30 including the compound parabolic lens 21 using the parabolic reflection coating is obtained. By disposing this laminate on the display surface 10a side of the display unit 10, the mirror display 1 of the embodiment is manufactured.

  The mirror display 1 of the embodiment is a large-sized design display of a public facility such as a commercial building, office building, or a lobby in a station, or a mirror display of a bathroom or a washstand in a home, a digital mirror for assisting rehabilitation operation, a hand mirror Widely used in mirror display devices such as small-sized displays, healthcare digital mirrors equipped with sensors that enable the acquisition and presentation of vital data, AR displays that synchronize mirror images with display images, and digital mirrors for interactive displays. Applicable.

  Next, examples and evaluation results thereof will be described.

Example 1
Square fine windows were formed in a square array with a period of 50 μm on a reflection layer having a complete reflection property provided on a glass substrate having a refractive index of 1.518. An in-lens medium and an out-lens medium having square large-diameter surfaces and small-diameter surfaces corresponding to the individual fine windows were formed on the surface of the reflective layer opposite to the glass substrate surface. By changing the width D2 of the small-diameter surface of the medium in the lens, the distance L between the large-diameter surface and the small-diameter surface, and the aperture ratio as shown in Table 1, seven samples (lens array unit and mirror unit) And a laminated body). The refractive index of the medium inside the compound parabolic lens was 1.518, and the refractive index of the medium outside the lens was 1.333.

  Next, a surface light source with a half-width of light directivity distribution of 20.5 degrees was prepared. A laminated body of a lens array part and a mirror part was disposed on this surface light source, and the reflectance and transmittance of light having a wavelength of 550 nm were evaluated by ray tracing calculation. The results are shown in Table 2. All the samples have a transmittance higher than the aperture ratio of the fine window. From these results, it was confirmed that a high luminance can be obtained by condensing a surface light source on a fine window and emitting it to the outside with individual compound parabolic lenses.

(Example 2)
Square fine windows were formed in a square array with a period of 50 μm on a reflection layer having a complete reflection property provided on a glass substrate having a refractive index of 1.518. On the side opposite to the glass substrate surface side of the reflective layer, there is a hole pattern in which the shape of the compound paraboloid lens (both large-diameter surface and small-diameter surface is square) is inverted corresponding to each fine window. A medium outside the lens (refractive index: 1.518) was formed. A reflection film having complete reflectivity was formed in the hole pattern of the medium outside the lens. The lens medium of the compound parabolic lens was air (refractive index: 1.000). Thus, seven samples were obtained by changing the width D2 of the small-diameter surface of the compound parabolic lens, the distance L between the large-diameter surface and the small-diameter surface, and the aperture ratio as shown in Table 3. (Laminated body of lens array part and mirror part) was created.

  Next, a surface light source with a half-width of light directivity distribution of 20.5 degrees was prepared. A laminated body of a lens array part and a mirror part was disposed on this surface light source, and the reflectance and transmittance of light having a wavelength of 550 nm were evaluated by ray tracing calculation. The results are shown in Table 4. All the samples have a transmittance higher than the aperture ratio of the fine window. From these results, it was confirmed that a high luminance can be obtained by condensing a surface light source on a fine window and emitting it to the outside with individual compound parabolic lenses.

(Comparative Example 1)
An Al half mirror was formed on a glass substrate having a refractive index of 1.518. Four samples were prepared by changing the thickness of the Al film as shown in Table 5. A surface light source having a half-width of light directivity distribution of 20.5 degrees was prepared. An Al half mirror was placed on the surface light source, and the reflectance and transmittance of light having a wavelength of 550 nm were evaluated by ray tracing calculation. The results are shown in Table 5. As a result of comparison with a sample having the same reflectance as the mirror display of Examples 1 and 2, it was confirmed that the transmittance of the half mirror was inferior to that of the mirror display of Examples 1 and 2.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. The configurations of the embodiments can be applied in combination with each other, and can be partially replaced. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

Claims (10)

A display unit that emits light for displaying an image;
A mirror unit comprising a reflective layer disposed on the display surface side of the display unit, and a plurality of fine windows formed in the reflective layer;
A plurality of compound paraboloidal lenses disposed between the display unit and the mirror unit and individually condensing the light emitted from the display unit toward the mirror unit on the plurality of fine windows; A mirror display comprising a lens array unit.   The lens array unit includes an in-lens medium forming the compound parabolic lens, and an out-of-lens medium disposed around the in-lens medium and having a refractive index smaller than that of the in-lens medium. Mirror display as described in.   The lens array unit is disposed between an in-lens medium forming the compound parabolic lens, an out-of-lens medium disposed around the in-lens medium, and between the in-lens medium and the out-of-lens medium. The mirror display according to claim 1, further comprising a reflective film. The compound parabolic lens includes a first surface on which the light is incident, a second surface from which the light is emitted, and a parabolic surface that connects the first surface and the second surface. Prepared,
The first width is D1 [unit: μm], the width of the second surface is D2 [unit: μm], and the distance between the first surface and the second surface is L [unit: μm]. ] Where the refractive index of the in-lens medium forming the compound parabolic lens is n1, and the half-value half-value of the directivity distribution of the light emitted from the display unit is θ [unit: degree]. The mirror display according to any one of claims 1 to 3, wherein the object lens satisfies a relationship of the following expressions (1), (2), and (3).
θ ′ = sin ⁻¹ (sin θ / n1) (1)
D1 ≧ D2 ≧ D1sin θ ′ (2)
L ≦ (D1 + D2) / 2 tan θ ′ (3)   The mirror display according to any one of claims 1 to 4, wherein a size of the fine window is 1/16 mm or less.   6. The mirror display according to claim 1, wherein the light emitted from the display unit is diffused light, and a half-value half-end θ of the directional distribution of the diffused light is 20 ° or more. .   The mirror display according to claim 1, wherein the fine window corresponds to one pixel or a plurality of pixels of the display unit.   The mirror display according to any one of claims 1 to 6, wherein a plurality of the fine windows correspond to one pixel of the display unit.   9. The reflection layer according to claim 1, wherein the reflective layer includes a metal film containing at least one metal selected from the group consisting of aluminum, silver, chromium, nickel, and zinc, or a dielectric multilayer film. The mirror display according to item.   A mirror display device comprising the mirror display according to any one of claims 1 to 9.

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