WO2019026748A1

WO2019026748A1 - Display device and head-mounted display

Info

Publication number: WO2019026748A1
Application number: PCT/JP2018/028044
Authority: WO
Inventors: 奈留臼倉; 加藤　浩巳
Original assignee: シャープ株式会社
Priority date: 2017-08-02
Filing date: 2018-07-26
Publication date: 2019-02-07

Abstract

The purpose of the present invention is to suppress color unevenness. According to the present invention, a liquid crystal display device (10) is provided with: a liquid crystal display unit (11) on which an image is displayed; a lens unit (12) which provides the image displayed on the liquid crystal display unit (11) onto an eyeball (EY) of a user, and which is thicker in the central portion than in the edge portion; a light-transmitting unit (15) which is provided to at least one of the liquid crystal display unit (11) and the lens unit (12), and which has light transmission properties; and a low refractive index light-transmitting film (16) which has a lower refractive index than the light-transmitting unit (15), while having light transmission properties, and which is arranged so as to be in contact with the light-transmitting unit (15), while being thinner in the central portion than in the edge portion.

Description

Display device and head mounted display

The present invention relates to a display device and a head mounted display.

DESCRIPTION OF RELATED ART Conventionally, what was described in the following patent document 1 as an example of a display apparatus is known. The display device described in Patent Document 1 includes means for acquiring information on the aberration generated in the display optical system and information on the aberration generated in the optical system for vision correction used by the observer, and the two aberrations The aberration correction is performed on the basis of

JP, 2010-96864, A

(Problems to be solved by the invention)
According to the display device described in Patent Document 1 described above, it is possible to carry out, for each individual, an appropriate correction for the aberration caused by the combination of the display optical system and the optical system for vision correction used by the observer. It becomes possible. Here, in general, a lens used for a display optical system has a spectrum such that the transmittance for light of short wavelength in visible light is relatively lower than the transmittance for light of longer wavelength than that. It has transmittance characteristics. Since the lens has a structure in which the thickness changes, the transmitted light may have a specific color depending on where the thickness is different, which may be viewed by the user.

The present invention is completed based on the above circumstances, and it is an object of the present invention to suppress color unevenness.

(Means to solve the problem)
The display device according to the present invention is a display unit for displaying an image, and a lens unit for forming an image displayed on the display unit on the eye of the user, and the lens unit having a center side thicker than the end side It is a low refractive index light transmitting film which is provided in at least one of a display unit and the lens unit and has a light transmitting property and a light transmitting property and a refractive index lower than that of the light transmitting section. And a low-refractive-index light-transmitting film which is disposed in contact with the light-transmitting portion and whose center side is thinner than the end side.

In this way, when the image is displayed on the display unit, the image is formed on the eye of the user by the lens unit. The lens portion is thicker at the center side than at the end side, so that it is possible to make the image displayed on the display portion visible to the user in an enlarged manner. The light transmitting portion provided in at least one of the display portion and the lens portion is in contact with a low refractive index light transmitting film having a light transmitting property and a refractive index lower than that of the light transmitting portion. Here, according to the Fresnel equation, since the reflection light at the light transmitting portion is reduced by lowering the refractive index of the low refractive index light transmitting film, the anti-reflection effect can be obtained. If the reflected light of the light transmitting part is reduced by the low refractive index light transmitting film, the transmitted light of the light transmitting part will be increased.

By the way, in general, the lens portion has a spectral transmittance characteristic such that the transmittance for the short wavelength light in visible light is relatively lower than the transmittance for the longer wavelength light. For this reason, in the lens portion, the transmitted light tends to have a specific tint compared to the end side on the relatively thick central side. In that respect, since the low refractive index light transmitting film is thinner at the center side than at the end side, the transmittance of short wavelength light is higher at the center side than at the end side. Specifically, the thickness of the low refractive index light transmitting film is d, the refractive index of the low refractive index light transmitting film is n, the wavelength of light passing through the low refractive index light transmitting film is λ, and the low refractive index light transmitting film Assuming that the incident angle of light passing through is θ, the equation represented by “d = λ / (4 n · cos θ)” holds. Here, since the light transmitted through the center side of the low refractive index light transmitting film has a smaller incident angle θ than the light transmitted through the end side, the value of cos θ in the above equation is relatively large and close to 1 It becomes. In addition, by making the center side of the low refractive index light transmitting film thinner than the end side, d in the above equation becomes smaller, so the value of the wavelength λ becomes smaller. That is, on the center side of the low refractive index light transmitting film, the transmittance of light on the short wavelength side is higher than that on the end side. As described above, the light transmitted through the center side of the lens portion is unlikely to have a specific color.

(Effect of the invention)
According to the present invention, color unevenness can be suppressed.

The schematic perspective view which shows the state which the user mounted on the head the head mounted display which concerns on Embodiment 1 of this invention A schematic side view showing an optical relationship between a liquid crystal display unit and a lens unit provided in a head-mounted device constituting a head mounted display, a user's eye, and a virtual display Side view showing liquid crystal display unit, lens unit and eyeball of user A table showing the relationship between the incident angle of light to the incident surface of the lens unit and the optical path length of light transmitted through the lens unit The side view which shows the liquid crystal display part which concerns on Embodiment 2 of this invention, a lens part, and a user's eyeball The side view which shows the liquid crystal display part which concerns on Embodiment 3 of this invention, a lens part, and a user's eyeball

First Embodiment
Embodiment 1 of the present invention will be described with reference to FIGS. 1 to 4. In the present embodiment, a goggle-type head-mounted display (HMD) HMD and a liquid crystal display device (display device) 10 used therefor are exemplified.

The goggle type head mount display HMD is equipped with a head mounted device HMDa mounted so as to surround both eyes in the head HD of the user, as shown in FIG. As shown in FIG. 2, the liquid crystal display device 10 is incorporated in the head mounted device HMDa. The liquid crystal display device 10 includes a liquid crystal display unit (display unit) 11 for displaying an image, and a lens unit (eyepiece lens unit) 12 for forming an image displayed on the liquid crystal display unit 11 on an eye (eye) EY of a user. And at least. The liquid crystal display unit 11 at least includes a liquid crystal panel (display panel) 13 having a display surface 13 a for displaying an image, and a backlight device (illumination device) 14 for irradiating the liquid crystal panel 13 with light for display. The lens unit 12 is disposed between the liquid crystal display unit 11 and the eye EY of the user, and imparts a refraction function to transmitted light. By adjusting the focal length of the lens unit 12, an image formed on the retina (eye) EYb through the lens EYa of the eye EY is more visible than the actual distance L1 from the eye EY to the liquid crystal display unit 11. The user can be made to recognize as being displayed on the virtual display VD apparently existing at the position of the far distance L2. Thus, the user can use a virtual display VD having a screen size (for example, in the range of several tens of inches to several hundreds of inches) much larger than that of the liquid crystal display unit 11 (for example, in the range of It is possible to visually recognize the magnified image (virtual image) displayed on the. Although it is possible to mount one liquid crystal display unit 11 on the head-mounted device HMDa and display the right-eye image and the left-eye image on the liquid-crystal display unit 11, the liquid-crystal display unit 11 may be displayed on the head-mounted device HMDa. It is also possible to display two right eye images on one liquid crystal display unit 11 and display left eye images on the other liquid crystal display unit 11. When one liquid crystal display unit 11 is mounted on the head mounted device HMDa, the screen size is, for example, in the range of 5 inches to 7 inches, and when two liquid crystal display units 11 are mounted on the head mounted device HMDa The screen size is, for example, in the range of 2 inches to 3.5 inches. Although not shown, the head-mounted device HMDa also includes an earphone or the like that is addressed to the user's ear and emits a sound.

Next, the liquid crystal panel 13 and the backlight device 14 constituting the liquid crystal display unit 11 will be sequentially described. As shown in FIG. 2, the liquid crystal panel 13 has a substantially rectangular plate shape as a whole, and the plate surface on the lens unit 12 side is a display surface 13a for displaying an image. The liquid crystal panel 13 includes a pair of glass substrates bonded together with a predetermined gap therebetween, a liquid crystal layer containing liquid crystal molecules which is a substance sealed between both glass substrates and whose optical characteristics change with application of an electric field. And at least a pair of polarizing plates attached to the outer surfaces of the two glass substrates. In one glass substrate (array substrate, active matrix substrate), a rectangular region surrounded by switching elements (for example, TFTs) connected to source wiring and gate wiring orthogonal to each other, source wiring and gate wiring In addition to the plane arrangement of the pixel electrodes arranged in the matrix and connected to the switching elements, an alignment film and the like are provided. The other glass substrate (opposite substrate, CF substrate) is provided with a color filter in which colored portions such as R (red), G (green), B (blue), etc. are planarly arranged in a matrix in a predetermined arrangement. A grid-like light shielding layer (black matrix) disposed between the colored portions, a solid counter electrode facing the pixel electrode, an alignment film, and the like are provided. On the other hand, the backlight device 14 is disposed on the back side (back side) with respect to the liquid crystal panel 13 and imparts an optical action to a light source (for example, an LED) emitting light (white light) or light from the light source. And an optical member for converting light into planar light.

The lens unit 12 is a convex lens having a function of converging (condensing) the incident parallel light flux as shown in FIG. Specifically, the lens unit 12 includes a light incident surface (a surface on the light incident side) 12a facing the liquid crystal display unit 11 and a light emitting surface (a surface on the light emission side) 12b facing the eye EY side of the user. Although the light incident surface 12a and the light exit surface 12b are both convex, they are biconvex lenses. Therefore, in the lens portion 12, the thickness on the center side is larger than the thickness on the end side. Specifically, the thickness of the lens portion 12 is maximum at the center position, the thickness is minimum at the outer end position, and the thickness gradually decreases from the center side toward the end side (continuously Gradually decrease). The lens unit 12 is an aspheric lens in which both the light entrance surface 12 a and the light exit surface 12 b are aspheric. As described above, since the lens unit 12 is thicker at the center side than at the end side, the image displayed on the liquid crystal display unit 11 can be viewed in an enlarged form for the user. .

As shown in FIG. 2, the lens portion 12 is made of a material having excellent light transmittance and substantially transparent (for example, acrylic resin (polymethyl methacrylate resin etc.) etc.), and its refractive index is, for example, 1.48 to 1 It is about the range of .75, preferably 1.70. Accordingly, the entire lens portion 12 is a light transmitting portion 15 having a light transmitting property. The lens unit 12 has a relatively small radius of curvature of the light incident surface 12a, but has a relatively large radius of curvature of the light exit surface 12b. Specifically, in the lens portion 12, the radius of curvature of the light incident surface 12a is, for example, in the range of 25 mm to 38 mm, preferably 38 mm. On the other hand, in the lens unit 12, the radius of curvature of the light exit surface 12b is, for example, in the range of 80 mm to 250 mm, preferably 95 mm. In the lens unit 12, both the conic constant K relating to the light entrance surface 12a and the light exit surface 12b are set to “−1”. That is, both the light incident surface 12a and the light exit surface 12b are paraboloidal surfaces, and thereby collimate parallel light without aberration.

By the way, in general, the lens unit 12 has a transmittance related to light (such as green light and red light) having a longer transmittance related to short wavelength light (such as violet light and blue light) in visible light. As compared with the above, it has a spectral transmittance characteristic that is relatively lower than that of the above, and the wavelength dependency of the refractive index in which the refractive index related to short wavelength light is higher than the refractive index related to long wavelength light. For this reason, compared with the end side on the relatively thick central side of the lens portion 12, the transmitted light tends to have a specific color (purple, blue, etc.), and color unevenness is visually recognized by the user. There was a risk of In particular, in order to widen the viewing angle of the head mounted display HMD, it tends to be required to make the focal point of the lens unit 12 short. Therefore, the radius of curvature of the light entrance surface 12a in the lens unit 12 is reduced. In some cases, the refractive index of the 12 materials may be made high. However, if the curvature radius of the light entrance surface 12a of the lens unit 12 is reduced, the difference in thickness of the lens unit 12 becomes larger at the center side and at the end side, so there is a concern that the above-mentioned color unevenness may deteriorate. Details will be described below with reference to FIG. FIG. 4 is a table showing the relationship between the incident angle (unit: “°”) of the lens unit 12 with respect to the incident surface 12 a and the optical path length (unit: “mm”) of light transmitted through the lens unit 12. Specifically, as shown in FIG. 4, the light transmitted through the central position of the lens unit 12 has an incident angle of 0 ° with respect to the incident surface 12 a of the lens unit 12 and the longest optical path length of 36.13 mm. Become. On the other hand, the light transmitted through the outer end position of the lens unit 12 has an incident angle of 35 °, the shortest optical path length is 10.90 mm, and the optical path length of the light transmitted through the central position It is less than 1/3 of. When the difference in the optical path length between the center side and the end side of the lens unit 12 is generated, the color unevenness may be significantly deteriorated. In addition, when the refractive index related to the material of the lens unit 12 is increased, there is concern that the above-described color unevenness may be deteriorated due to the wavelength dependency of the refractive index.

So, in this embodiment, as shown in FIG. 3, the low refractive index translucent film 16 which has translucency and has a refractive index lower than that of the translucent portion 15 is used as the lens portion 12 (translucent portion 15). It is arranged to be in contact with each other. The low refractive index light transmitting film 16 is thinner at the center side of the lens portion 12 than at the end side. Specifically, the low refractive index light transmitting film 16 is made of magnesium fluoride (MgF ₂ ), and its refractive index is, for example, about 1.36, which is lower than the refractive index of the material of the lens portion 12 It has become. According to Fresnel's equation, the refractive index of the low-refractive-index light-transmissive film 16 is lowered, so that the reflected light at the lens portion 12 is reduced, so that an anti-reflection effect can be obtained. When the reflected light of the lens unit 12 is reduced by the low refractive index light transmitting film 16, the transmitted light of the lens unit 12 is increased. The low refractive index light transmitting film 16 has a film thickness of, for example, about 74 nm at the center position of the lens unit 12, while it has, for example, about 120 nm at the outer end position of the lens unit 12. The film thickness of the low refractive index light transmitting film 16 is minimum at the center position, is maximum at the outer end position, and gradually increases from the center side toward the end side (continuously increases gradually). It is assumed that the thickness change of the lens portion 12 is in an inverse correlation relationship. Here, the boundary position between the center side and the end side of the low refractive index light transmitting film 16 can be defined as follows. First, on the normal to the display surface 13a passing through the center position of the lens unit 12, a position 10 mm away from the light emitting surface 12b of the lens unit 12 (surface opposite to the liquid crystal panel 13) on the opposite side to the liquid crystal panel 11 side As a reference point, it is assumed that light is emitted from the reference point toward the lens unit 12. Of the light traveling from the reference point to the liquid crystal panel 13 through the outermost peripheral end of the lens unit 12, the angle between the light traveling from the reference point to the outermost peripheral end of the lens unit 12 and the normal direction of the display surface 13a Among light reaching from the point to the outermost peripheral end of the liquid crystal panel 13 through the lens portion 12, relative angle between light traveling from the reference point to the lens portion 12 and the normal direction of the display surface 13 a is relative A small angle is defined as "viewing angle". Then, the position where the straight line forming an angle of 25% of the “view angle” with the reference point and the normal direction of the display surface 13 a intersects the low refractive index light transmitting film 16 is the center of the low refractive index light transmitting film 16 It is the boundary position of the side and the end side. The central portion of the low refractive index light transmitting film 16 is a region irradiated with light at an angle smaller than 25% of the “view angle” with respect to the normal direction of the display surface 13a from the reference point. The end side portion of the refractive index light transmitting film 16 is a region to which light is irradiated at an angle larger than 75% of the “viewing angle” with respect to the normal direction of the display surface 13 a from the reference point. In FIG. 3, only the liquid crystal panel 13 is illustrated in the liquid crystal display unit 11. Further, in FIG. 2, the low refractive index light transmitting film 16 in the lens unit 12 is not shown.

As described above, since the low refractive index light transmissive film 16 is thinner at the center side than at the end side, the transmittance of short wavelength light is higher at the center side than at the end side. Specifically, the thickness of the low refractive index light transmitting film 16 is d, the refractive index of the low refractive index light transmitting film 16 is n, the wavelength of light passing through the low refractive index light transmitting film 16 is λ, and the low refractive index Assuming that the incident angle of light transmitted through the light transmitting film 16 is θ, the following equation (1) holds. Here, since the light transmitted through the center side of the low refractive index light transmitting film 16 has a smaller incident angle θ than the light transmitted through the end side, the value of cos θ in the following formula (1) is relatively large. It becomes a value close to 1. In addition, by making the center side of the low refractive index light transmitting film 16 thinner than the end side, d of the following formula (1) becomes small, so the value of the wavelength λ becomes small. That is, on the center side of the low refractive index light transmitting film 16, the transmittance of light on the short wavelength side is higher than that on the end side. As described above, the light transmitted through the center side of the lens unit 12 is difficult to take on a specific color. In addition, since the low refractive index light transmitting film 16 is disposed in contact with the surface of the lens portion 12, the liquid crystal display portion 11 is temporarily provided with a light transmitting portion and a low refractive index light transmitting film in contact therewith. Also, the low refractive index light transmitting film 16 can be provided at low cost.

[Equation 1]
d = λ / (4 n · cos θ) (1)

More specifically, the low refractive index light transmitting film 16 has a thickness on the center side as dc, a refractive index of the low refractive index light transmitting film 16 as n, a wavelength of light transmitted through the center side as λc, and the center side Assuming that the incident angle of light to be transmitted is θc, the following equations (2) and (3) are satisfied. In this way, the transmittance of light with a wavelength of 380 nm to 480 nm, that is, light belonging to the shortest wavelength side of visible light, is higher at the center side of the low refractive index light transmitting film 16 than at the end side. It becomes a thing. As a result, the light transmitted through the center side of the lens unit 12 is more difficult to take on a specific color. Particularly preferably, in the low refractive index light transmitting film 16, in the following formulas (2) and (3), the wavelength λc of light transmitted through the central side is set to 400 nm. In this way, the transmittance of light with a wavelength of 400 nm is higher at the center side of the low refractive index light-transmissive film 16 than at the end side. The light with a wavelength of 400 nm is light particularly near a short wavelength in visible light, so that the transmittance of the light is increased, so that the light transmitted through the center side of the lens unit 12 has a specific color. It becomes even more difficult to take.

[Equation 2]
dc = λ c / (4 n · cos θ c) (2)

[Equation 3]
380 nm ≦ λ c ≦ 480 nm (3)

Furthermore, the low refractive index light transmitting film 16 has a thickness on the end side as de, a refractive index of the low refractive index light transmitting film 16 as n, a wavelength of light transmitted through the end side as λe, and the end side transmits The following equations (4) and (5) are satisfied, where θe is the incident angle of the incident light. In this way, the transmittance of light with a wavelength of 500 nm to 600 nm is higher at the end side of the low refractive index light-transmissive film 16 than at the center side. The light having a wavelength of 500 nm to 600 nm is green light having high visibility as compared to blue light and red light among visible light, and therefore, the transmittance of green light is increased, so that the utilization efficiency of light is good. become. Particularly preferably, in the low refractive index light transmitting film 16, in the following formulas (4) and (5), the wavelength λe of the light transmitted through the end side is set to 550 nm. In this way, the transmittance of light having a wavelength of 550 nm is higher at the end side of the low refractive index light-transmissive film 16 than at the center side. The green light having a wavelength of 550 nm is the light having the highest visibility among the visible light, so that the transmittance of the green light is increased, whereby the light utilization efficiency is further improved.

[Equation 4]
de = λ e / (4 n · cos θ e) (4)

[Equation 5]
500 nm ≦ λe ≦ 600 nm (5)

Furthermore, as shown in FIG. 3, a pair of low refractive index translucent films 16 is disposed in contact with the light incident surface 12 a and the light exit surface 12 b of the lens unit 12. In this way, the light incident on the light incident surface 12 a of the lens unit 12 and the light emitted from the light exit surface 12 b are transmitted through the low refractive index light transmitting film 16 respectively, so the anti-reflection effect is excellent. In addition, it is excellent in the color nonuniformity suppression effect. Moreover, when providing the low refractive index light transmitting film 16 to the lens portion 12, it is possible to use, for example, a dip coating method, so that the cost for installing the low refractive index light transmitting film 16 can be reduced. It is considered suitable.

As described above, the liquid crystal display device (display device) 10 according to the present embodiment includes the liquid crystal display unit (display unit) 11 for displaying an image, and the image displayed on the liquid crystal display unit 11 as a user's eye (eye) A lens unit 12 for forming an image on EY, wherein the center side is thicker than the end side, and provided on at least one of the liquid crystal display unit 11 and the lens unit 12 and a light transmitting unit 15 having a light transmitting property A low refractive index light transmitting film 16 having a light transmitting property and a refractive index lower than that of the light transmitting part 15, the low refractive index being in contact with the light transmitting part 15 and having a center side thinner than an end side And a rate light-transmissive film 16.

In this way, when an image is displayed on the liquid crystal display unit 11, the image is formed on the eye EY of the user by the lens unit 12. Since the lens unit 12 is thicker at the center side than at the end side, the image displayed on the liquid crystal display unit 11 can be viewed in an enlarged form for the user. The light transmitting portion 15 provided in at least one of the liquid crystal display portion 11 and the lens portion 12 is in contact with a low refractive index light transmitting film 16 having a light transmitting property and a refractive index lower than that of the light transmitting portion 15 Are arranged. Here, according to the Fresnel equation, since the reflection light at the light transmitting portion 15 is reduced by lowering the refractive index of the low refractive index light transmitting film 16, an anti-reflection effect can be obtained. When the reflected light of the light transmitting portion 15 is reduced by the low refractive index light transmitting film 16, the transmitted light of the light transmitting portion 15 is increased.

By the way, in general, the lens unit 12 has a spectral transmittance characteristic such that the transmittance for the short wavelength light in visible light is relatively lower than the transmittance for the longer wavelength light than that. . For this reason, the lens portion 12 tends to have a specific tint of transmitted light at the relatively thick center side as compared to the end side. In that respect, since the low refractive index light transmitting film 16 is thinner at the center side than at the end side, the transmittance of short wavelength light is higher at the center side than at the end side. Specifically, the thickness of the low refractive index light transmitting film 16 is d, the refractive index of the low refractive index light transmitting film 16 is n, the wavelength of light passing through the low refractive index light transmitting film 16 is λ, and the low refractive index Assuming that the incident angle of light transmitted through the light transmitting film 16 is θ, an expression represented by “d = λ / (4n · cos θ)” holds. Here, since the light transmitted through the center side of the low refractive index light transmitting film 16 has a smaller incident angle θ than the light transmitted through the end side, the value of cos θ in the above equation is relatively large and close to 1 It becomes a value. In addition, by making the center side of the low refractive index light transmitting film 16 thinner than the end side, d in the above equation becomes smaller, so the value of the wavelength λ becomes smaller. That is, on the center side of the low refractive index light transmitting film 16, the transmittance of light on the short wavelength side is higher than that on the end side. As described above, the light transmitted through the center side of the lens unit 12 is difficult to take on a specific color.

Further, the low refractive index light transmitting film 16 has a thickness on the center side as dc, a refractive index of the low refractive index light transmitting film 16 as n, a wavelength of light transmitted through the center side as λ c, and the center side is transmitted. Assuming that the incident angle of light is θc, the following equations (6) and (7) are satisfied.

[Equation 6]
dc = λ c / (4 n · cos θ c) (6)

[Equation 7]
380 nm ≦ λ c ≦ 480 nm (7)

In this way, the transmittance of light with a wavelength of 380 nm to 480 nm is higher at the center side of the low refractive index light transmitting film 16 than at the end side. As a result, the light transmitted through the center side of the lens unit 12 is more difficult to take on a specific color.

The low refractive index light transmissive film 16 has λc of 400 nm. In this way, the transmittance of light with a wavelength of 400 nm is higher at the center side of the low refractive index light-transmissive film 16 than at the end side. The light with a wavelength of 400 nm is light particularly near a short wavelength in visible light, so that the transmittance of the light is increased, so that the light transmitted through the center side of the lens unit 12 has a specific color. It becomes even more difficult to take.

The low refractive index light transmitting film 16 has a thickness on the end side as de, a refractive index of the low refractive index light transmitting film 16 as n, a wavelength of light transmitting through the end side as λe, and transmits through the end side. When the incident angle of light is θe, the following formulas (8) and (9) are satisfied.

[Equation 8]
de = λ e / (4 n · cos θ e) (8)

[Equation 9]
500 nm ≦ λe ≦ 600 nm (9)

In this way, the transmittance of light with a wavelength of 500 nm to 600 nm is higher at the end side of the low refractive index light-transmissive film 16 than at the center side. The light with a wavelength of 500 nm to 560 nm is green light with high visibility, so the transmittance of the green light is increased to improve the light utilization efficiency.

The low refractive index light transmissive film 16 has λe of 550 nm. In this way, the transmittance of light having a wavelength of 550 nm is higher at the end side of the low refractive index light-transmissive film 16 than at the center side. The green light having a wavelength of 550 nm is the light having the highest visibility among the visible light, so that the transmittance of the green light is increased, whereby the light utilization efficiency is further improved.

In addition, the light transmitting portion 15 is provided in the lens portion 12, and the low refractive index light transmitting film 16 is disposed in contact with the surface of the lens portion 12. In this way, the low refractive index light transmitting film 16 can be provided at low cost, as compared with the case where the liquid crystal display unit 11 is provided with the light transmitting portion.

Further, a pair of low refractive index light transmitting films 16 is disposed in contact with the surface on the light entrance side and the surface on the light exit side of the lens unit 12 respectively. In this way, it is possible to use, for example, a dip coating method when providing the low refractive index light transmitting film 16 to the lens portion 12, which is more preferable for cost reduction.

In addition, the lens unit 12 is a convex lens. This is suitable for reducing the cost of the lens unit 12.

Further, the head mounted display HMD according to the present embodiment includes at least the liquid crystal display device 10 described above, and a head mounted device HMDa having the liquid crystal display device 10 and mounted on the head HD of the user. Prepare. According to the head mount display HMD having such a configuration, when the user wears the head mounted device HMDa on the head HD, an image displayed on the liquid crystal display unit 11 constituting the liquid crystal display device 10 is displayed. The lens unit 12 forms an image on the eye EY of the user, which enables the user to visually recognize the image displayed on the liquid crystal display unit 11 in an enlarged form. In the liquid crystal display device 10 described above, since the light transmitted through the center side of the lens portion 12 is difficult to take on a specific color, the display quality is high, and the immersion feeling of the user is higher. Become.

Second Embodiment
Embodiment 2 of the present invention will be described with reference to FIG. In the second embodiment, the configuration of the lens unit 112 is changed. In addition, the description which overlaps about the structure similar to Embodiment 1 mentioned above, an effect | action, and an effect is abbreviate | omitted.

The lens part 112 which concerns on this embodiment has the Fresnel lens 17 as shown in FIG. Specifically, the lens unit 112 is provided with the Fresnel lens 17 on the light entrance surface 112 a. On the other hand, the low refractive index light transmissive film 116 is not formed on the light incident surface 112 a of the lens portion 112 on which the Fresnel lens 17 is provided, and is selectively disposed only on the light exit surface 112 b. The Fresnel lens 17 has a partial spherical surface arranged in steps. The curvature of the surface of the Fresnel lens 17 is relatively smaller on the outer peripheral end side than on the center side of the lens portion 112. According to the Fresnel lens 17 having such a configuration, it is possible to remove the component of astigmatism. Thereby, thinning and shortening of the focus of the lens portion 112 can be achieved.

As described above, according to the present embodiment, the lens unit 112 has the Fresnel lens 17. This configuration is suitable for achieving thinning and shortening of the focus of the lens unit 112.

Embodiment 3
Embodiment 3 of the present invention will be described with reference to FIG. In the third embodiment, the arrangement of the low refractive index light transmissive film 216 is changed from the first embodiment described above. In addition, the description which overlaps about the structure similar to Embodiment 1 mentioned above, an effect | action, and an effect is abbreviate | omitted.

The low refractive index light transmissive film 216 according to the present embodiment is disposed in contact with the display surface 213a for displaying an image in the liquid crystal display unit 211, as shown in FIG. Therefore, in the present embodiment, the liquid crystal display unit 211 includes the light transmitting unit 215 that transmits light and is in contact with the low refractive index light transmitting film 216. Specifically, in the liquid crystal panel 213 constituting the liquid crystal display portion 211, a polarizing plate disposed on the display surface 213a constitutes a light transmitting portion 215. The polarizing plate constituting the light transmitting portion 215 is made of a material having a refractive index (for example, around 1.5) higher than that of the low refractive index light transmitting film 216. In this way, as compared with the case where the lens portion is provided with the light transmitting portion and the low refractive index light transmitting film in contact therewith as in the first and second embodiments described above, the optical performance of the lens portion 212 is lower It is possible to avoid a situation that can be reduced by the light film 216.

As described above, according to the present embodiment, the light transmitting unit 215 is provided in the liquid crystal display unit 211, and the low refractive index light transmitting film 216 is provided on the display surface 213a for displaying an image in the liquid crystal display unit 211. It is distributed in the form of contact. In this way, it is possible to avoid the situation where the optical performance of the lens portion 212 is reduced by the low refractive index light transmitting film 216, as compared with the case where the light transmitting portion is provided in the lens portion.

Other Embodiments
The present invention is not limited to the embodiments described above with reference to the drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) In each embodiment described above, the case where the wavelength λc of the light transmitted through the center side of the low refractive index light transmitting film is 400 nm is exemplified, but the specific numerical value of the wavelength λc can be appropriately changed is there. Even in such a case, it is preferable that the wavelength λc be in the numerical range with the lower limit of 380 nm and the upper limit of 480 nm, but the range is not necessarily limited to that.
(2) In each embodiment described above, the wavelength λe of the light transmitted through the end side of the low refractive index light transmitting film is 550 nm, but the specific numerical value of the wavelength λe can be appropriately changed. is there. Even in such a case, it is preferable that the wavelength λc be within the numerical range with the lower limit of 500 nm and the upper limit of 600 nm, but the range is not necessarily limited thereto.
(3) In the first embodiment described above, the low refractive index light transmitting film is disposed on each of the light incident surface and the light exit surface of the lens unit. However, any one of the light incident surface and the light exit surface of the lens unit It is also possible to selectively dispose the low refractive index light transmitting film only on one side.
(4) In the second embodiment described above, the low refractive index light transmitting film is selectively disposed only on the light exit surface of the lens unit provided with the Fresnel lens on the light entrance surface. However, the Fresnel lens is disposed. It is also possible to selectively dispose a low refractive index light transmitting film on the light incident surface. In addition, it is also possible to dispose a low refractive index light transmitting film on each of the light entrance surface and the light exit surface of the lens unit provided with the Fresnel lens on the light entrance surface.
(5) In the second embodiment described above, the Fresnel lens is provided on the light incident surface of the lens unit, but it is also possible to provide a linear Fresnel lens, a lenticular lens, or the like on the light incident surface of the lens unit.
(6) In the third embodiment described above, the low refractive index light transmitting film is disposed in contact with the polarizing plate in the liquid crystal panel of the liquid crystal display portion. However, the form in contact with the glass substrate in the liquid crystal panel of the liquid crystal display portion It is also possible to dispose a low refractive index light transmissive film.
(7) In each of the above-described embodiments, the low refractive index light transmitting film is selectively disposed on only one of the lens unit and the liquid crystal display unit. However, both the lens unit and the liquid crystal display unit are provided. It is also possible to dispose a low refractive index light transmissive film on each of
(8) In each embodiment described above, magnesium fluoride is exemplified as the material of the low refractive index light transmitting film, but the specific material used for the low refractive index light transmitting film can be appropriately changed. In that case, as the material used for the low refractive index light transmitting film, the refractive index is preferably as close to 1 as possible, and in general, a fluorine-based material having a low refractive index is preferable.
(9) In each embodiment described above, although the case where the film thickness of the low refractive index light transmitting film changes continuously, the film thickness of the low refractive index light transmitting film changes stepwise. I don't care.
(10) In addition to the embodiments described above, the refractive index related to the material of the lens part and the low refractive index light transmitting film, the optical path length related to the transmitted light of the lens part, and the light entrance surface and light exit surface of the lens unit Specific numerical values such as the radius of curvature and the film thickness of the low refractive index light transmitting film can be changed as appropriate.
(11) In each embodiment described above, the lens portion is an aspheric lens, but the lens portion may be a spherical lens.
(12) In the above-described embodiments, the lens unit is a biconvex lens. However, the lens unit may be a plano-convex lens or the like.
(13) In each of the above-described embodiments, the liquid crystal display unit including the liquid crystal panel is illustrated as the display unit, but other types of display panels (PDP (plasma display panel), organic EL panel, EPD (electrophoretic display panel) ), A display unit provided with a MEMS (Micro Electro Mechanical Systems) display panel or the like may be used.
(14) Although the head mounted display is shown in each of the above-described embodiments, the present invention is applicable to, for example, a head-up display or a projector as an apparatus for enlarging and displaying an image displayed on a liquid crystal display unit using a lens unit. Is applicable.
(15) In the above embodiments, the low refractive index light transmitting film is a single layer film, but the low refractive index light transmitting film is a multilayer film formed by laminating a plurality of films. I don't care. In that case, it is possible to use a plurality of materials having different refractive indexes as the material of the plurality of films constituting the low refractive index light transmitting film.

DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display device (display device) 11,211 ... Liquid crystal display part (display part) 12,112, 212 ... Lens part, 12a, 112a ... Light incident surface (surface by the side of light incidence), 12b, 112b ... Light exit surface (surface on the light exit side), 13a, 213a: display surface, 15, 215: light transmission part, 16, 116, 216: low refractive index light transmission film, 17: Fresnel lens, EY: eye (eye), EYA ... crystalline lens (eye), EYb ... retina (eye), HD ... head, HMD ... head mounted display, HMDa ... head mounted equipment

Claims

A display unit for displaying an image;
A lens unit for forming an image displayed on the display unit on a user's eye, wherein the lens unit is thicker at the center side than at the end side;
A translucent portion provided on at least one of the display portion and the lens portion;
A low refractive index light transmitting film having a light transmitting property and a refractive index lower than that of the light transmitting portion, the low refractive index light transmitting member being in contact with the light transmitting portion and having a center side thinner than an end side. And a light film.
In the low refractive index light transmitting film, the thickness on the central side is dc, the refractive index of the low refractive index light transmitting film is n, the wavelength of light transmitted through the central side is λc, and the central light is transmitted The display device according to claim 1, wherein the following formulas (1) and (2) are satisfied, where θc is an incident angle of the incident light.
[Equation 1]
dc = λ c / (4 n · cos θ c) (1)
[Equation 2]
380 nm ≦ λ c ≦ 480 nm (2)
The display device according to claim 2, wherein the λc of the low refractive index light transmissive film is 400 nm.
In the low refractive index light transmitting film, the thickness on the end side is de, the refractive index of the low refractive index light transmitting film is n, the wavelength of light transmitted through the end side is λe, and the light is transmitted through the end side The display device according to any one of claims 1 to 3, wherein the following equations (3) and (4) are satisfied, where θe is an incident angle of the incident light.
[Equation 3]
de = λ e / (4 n · cos θ e) (3)
[Equation 4]
500 nm ≦ λe ≦ 600 nm (4)
The display device according to claim 4, wherein the λe of the low refractive index light transmissive film is 550 nm.
The light transmitting unit is provided in the lens unit,
The display device according to any one of claims 1 to 5, wherein the low refractive index light transmissive film is disposed in contact with a surface of the lens unit.
The display device according to claim 6, wherein the low refractive index light transmitting film is disposed in a pair so as to be in contact with the surface on the light entrance side and the surface on the light exit side of the lens unit.
The light transmitting unit is provided in the display unit.
The display device according to any one of claims 1 to 5, wherein the low refractive index light transmissive film is disposed in contact with a display surface on which an image is displayed in the display unit.
A display device according to any one of claims 1 to 8;
A head mounted display comprising at least a head mounted device having the display device and mounted on a head of the user.