JP2020091195A - Display device - Google Patents

Abstract

To provide a display device with which visibility is good.SOLUTION: A display device comprises: an image display 21 for displaying an image on a display screen 22; a light source 41 for emitting visible light; and an optical laminar unit 31 for introducing visible light from the light source into the inside. The optical laminar unit 31 includes a reflection structure 32 formed on at least a portion of a front face 31a exposed to the viewing side and having irregularities 32a for reflecting the visible light introduced into the inside to the viewing side, with at least a portion of a reverse side 31b opposite from the front face 31a adhered to the display screen 22.SELECTED DRAWING: Figure 2

Description

The disclosure of this specification relates to a display device.

Conventionally, display devices used in vehicles have been known. The device disclosed in Patent Document 1 includes an image display, a light source, and a light guide plate. The light guide plate introduces visible light from the light source therein. Then, in the light guide plate arranged apart from the display screen of the image display, visible light introduced into the inside of the light guide plate is partially exposed on the back side opposite to the viewing side. A reflective structure having unevenness that reflects on the viewing side is formed.

JP, 2018-75930, A

That is, in the light guide plate of Patent Document 1, a reflection structure is formed on a part of the back surface, and the reflection realizes efficient reflection due to a difference in refractive index between the inside and the outside of the light guide plate. Such a difference in refractive index can be set large by providing an air layer having a low refractive index between the back surface of the light guide plate and the display screen. However, as a reciprocity of providing an air layer by separating the back surface and the display screen, when external light such as sunlight enters from the outside of the device, the reflection of the external light on the back surface and the display screen may occur. It is feared that the visibility of the display may deteriorate during the daytime.

One of the objects of the disclosure of this specification is to provide a display device having good visibility.

One of the aspects disclosed herein is an image display (21) for displaying an image on a display screen (22),
A light source (41) that emits visible light,
An optical layered part (31) which is formed in a layer using an optical adhesive material having translucency and which introduces visible light from a light source into the inside,
The optical layered portion forms a reflection structure (32) having at least a part of the front surface (31a) exposed on the viewing side and having unevenness (32a) that reflects visible light introduced thereinto on the viewing side. In addition, at least a part of the back surface (32b) opposite to the front surface is adhered to the display screen.

According to such an aspect, what introduces the visible light from the light source into the inside is an optical layered portion formed in a layer using an optical adhesive material having translucency. At least a part of the front surface of the optical layered portion is provided with irregularities of a reflective structure that reflects the introduced visible light to the viewer side. Since the front surface is exposed to the viewing side, even if a reflective structure is formed on the front surface, a large difference in the refractive index at the interface can be set, so that efficient reflection is realized. Then, by transferring the reflecting structure to the front surface, the back surface can be bonded to the display screen. By adhering the back surface and the display screen, even when external light such as sunlight enters from the outside of the device, reflection of the external light on the back surface and the display screen is suppressed. Therefore, it is possible to prevent the visibility of the display from being deteriorated during the daytime. As described above, it is possible to provide the vehicular display device having good visibility.

It should be noted that the reference numerals in parentheses are merely illustrative of the correspondence with the portions of the embodiments described below, and are not intended to limit the technical scope.

It is a front view of the display device of the first embodiment. It is the II-II sectional view taken on the line of FIG. It is a figure which shows typically the cross-section of the image display of 1st Embodiment. It is an enlarged front view for demonstrating arrangement|positioning of the reflective structure of 1st Embodiment. It is an expansion perspective view for explaining the reflection control structure of a 1st embodiment.

An embodiment will be described based on the drawings.

(First embodiment)
As shown in FIG. 1, the display device 10 according to the first embodiment of the present disclosure is a display device for a vehicle used in a vehicle, and is opposed to a seat on which an occupant as a viewer who visually recognizes the device 10 is seated. It is installed on the instrument panel. The display device 10 is capable of displaying vehicle information toward the viewing side where the occupant is located. In particular, the display device 10 of the present embodiment is a graphic meter mainly for displaying an image by the image display 21.

In addition, in this embodiment, the respective directions indicated by the upper, lower, front, rear, left, and right are described with reference to a vehicle on a horizontal plane.

As shown in FIG. 2, such a display device 10 includes a case portion 11, an image display 21, an optical layer portion 31, a light source 41, and the like.

The case portion 11 includes a rear case 12, a facing member 13, a front plate 14, and the like. The rear case 12 is formed of, for example, a synthetic resin so as to have a light-shielding property, and covers the image display 21 from the rear side.

The facing member 13 is formed of, for example, a synthetic resin so as to have a light shielding property. The look-back member 13 has openings on the viewing side and the back side, and is formed in a deformed tubular shape along the outer periphery of the device 10. An upper portion of the look-back member 13 which is arranged above the image display 21 is larger than a lower portion which is arranged below the image display 21 toward the visual recognition side.

The front plate 14 is formed of a semi-translucent resin such as a colored acrylic resin or polycarbonate resin into a curved plate shape that closes the entire viewing side opening of the dial member 13. As a result, the display on the image display 21 and the like is visually recognized by the occupant through the front plate 14. Due to the above-mentioned relationship between the upper and lower projections, the front plate 14 is arranged so as to be inclined obliquely downward and curved so as to be concave toward the back side (image display 21 side). Has been formed.

Although the front plate 14 of the present embodiment is set to have a visible light transmittance of about 30% due to smoke-like coloring, it may be set to an arbitrary value of 30% or more. Visible light in the present embodiment means light having a wavelength in the range of 380 to 750 nm.

The image display 21 displays an image on a display screen 22 having a rectangular and flat outline, for example. In particular, the image display 21 of the present embodiment employs, for example, an OLED display (Organic Light-Emitting Diode Display) using a rigid substrate as a self-luminous display. As shown in FIG. 3, the image display 21 includes a light emitting unit 25, a polarization unit 26, and the like.

The light emitting unit 25 is disposed so as to be sandwiched between a pair of translucent flat plate-shaped substrate layers 24a and 24b. The light emitting unit 25 is formed by two-dimensionally arranging organic light emitting diodes (OLEDs) for forming pixels. By arranging adjacent organic light emitting diodes to emit visible light of different colors such as red, green, and blue, various colors can be reproduced by combining different colors. As another configuration, various colors can be reproduced by combining an organic light emitting diode that emits white light as visible light and a color filter.

The polarization part 26 is arranged on the viewing side of the light emitting part 25, and is formed in more detail in a close contact state with the viewing side substrate layer 24a. A circularly polarizing plate is used for the polarization unit 26 of the present embodiment. The polarization part 26 has a linear polarization layer 26a and a retardation layer 26b in a state of being laminated on each other by bonding or the like.

The linear polarization layer 26a is arranged on the viewing side of the retardation layer 26b. The linear polarizing layer 26a is a so-called polarizing film, and is formed into a thin flat plate by adding iodine to a synthetic resin such as polyvinyl alcohol resin, and the transmission axis and the absorption axis are substantially orthogonal to each other depending on the orientation direction of iodine molecules. Have in the state. Linearly polarized light along the transmission axis passes through the linearly polarized layer 26a, and linearly polarized light along the absorption axis is absorbed by the linearly polarized layer 26a. Substantially, this linear polarization layer 26a forms a part of the front surface 22a of the display screen 22 which faces the viewing side.

The retardation layer 26b is a so-called retardation film, and is formed so as to impart a retardation of about ¼ wavelength to visible light. That is, the linearly polarized light is converted into approximately circularly polarized light by the transmission of the retardation layer 26b, and the circularly polarized light is converted into approximately linearly polarized light by the transmission of the retardation layer 26b.

As a result, even when external light is incident on the display screen 22 from the viewing side to the back side, most of the light is absorbed by the linear polarization layer 26a, and thus the external light is visually recognized on the image display 21. The reflection to the side is suppressed.

A frame portion 23 is formed around the display screen 22. The frame portion 23 is formed of, for example, a synthetic resin so as to have a light-shielding property, and surrounds the display screen 22 over the entire circumference.

It is preferable that the front surface 23a of the frame portion 23 facing the viewing side is restricted from forming a step with respect to the front surface 22a of the display screen 22. Thereby, the two front surfaces 22a and 23a can form a substantially common flat surface portion. In addition, by extending the polarizing portion 26 to the portion of the frame portion 23 on the outer peripheral side of the portion where the light emitting portion 25 is provided, a flat portion that is integral with both the front surfaces 22a and 23a is formed. May be.

The image display 21 formed in this manner is formed in a panel shape having a thickness of 2.0 mm or less, more preferably about 1.4 mm, and with respect to the rear case 12 arranged on the rear side of the image display 21. Is held.

In the present embodiment, on the display screen 22, two pointers PD are displayed side by side as an image. Information corresponding to each pointer PD is displayed by rotating each pointer PD and appropriately changing the indicated position.

The optical layer portion 31 is formed into a layer having a substantially uniform thickness using an optical adhesive material having a light-transmitting property. The refractive index of the optical adhesive material is as close as possible to the refractive index of the material forming the front surface 22a of the display screen 22, that is, the material of the linearly polarizing layer 26a of the polarizing portion 26 (for example, the difference in refractive index is 0). . 1) to be selected). As the optical adhesive material, for example, an optical adhesive sheet (OCA) having a thickness of 1.0 mm or less, more preferably about 0.5 mm is used. The optical pressure-sensitive adhesive sheet is mainly formed of a translucent synthetic resin such as acrylic resin, silicone resin, or urethane resin, and is formed in a viscous sheet shape.

The optical layered portion 31 has a front surface 31a exposed on the viewing side and a back surface 31b adhered to the front surface 22a of the display screen 22 and the front surface 23a of the frame portion 23. ing. The back surface 31b of the optical layered portion 31 and the both front surfaces 22a and 23a are adhered in a planar manner over the entire surface, so that they are in close contact with each other without substantially interposing an air layer therebetween. There is.

In this way, the optical layered portion 31 has the overlapping region OR1 overlapping the display screen 22 and the protruding region OR2 arranged outside the overlapping region OR1 and overlapping the frame portion 23. The outer peripheral contour of the optical layered portion 31 is formed, for example, according to the outer peripheral contour of the frame portion 23. The side surface 31c forming the outer peripheral contour of the optical layered portion 31 has a planar shape substantially perpendicular to the front surface 31a and the back surface 31b by being cut by, for example, a sharp cutter.

The light source 41 has a plurality of light emitting elements on a light source circuit board 42 which is arranged so as to face the side surface 31c of the optical layered portion 31 with a predetermined distance from the side surface 31c. In particular, in the present embodiment, the light source circuit board 42 is arranged so as to face the side surface 31c facing upward of the side surfaces 31c. Each light source 41 and the side surface 31c face each other vertically with a slight gap therebetween. The light source 41 may be in contact with the side surface 31c. The light source circuit board 42 is held by the rear case 12.

The plurality of light emitting elements forming the light source 41 are arranged at a predetermined pitch. Each light emitting element employs an inorganic light emitting diode (LED) in the form of a point light source, more specifically a micro chip LED, and each light emitting element emits visible light when connected to a power source. Particularly, in the present embodiment, each light emitting element emits light with substantially the same color and the same brightness. In addition, each light emitting element is configured to be able to switch between a lighting state and a non-lighting state simultaneously.

With such a facing arrangement (or abutting arrangement) between the light source 41 and the side surface 31c, visible light from the light source 41 is introduced into the inside of the optical layered portion 31 with the direction from the upper side to the lower side as the incident direction. .. The visible light introduced into the inside of the optical layer portion 31 travels downward in the inside along the extending direction of the optical layer portion 31.

The optical layer portion 31 displays using visible light from the light source 41. Specifically, the optical layered portion 31 can display a symbol by forming the reflection structure 32 and the reflection regulation structure 33 on the front surface 31a thereof. In the present embodiment, the entire front surface 31a is covered with either the reflection structure 32 or the reflection regulation structure 33.

The reflecting structure 32 is formed on the front surface 31a so as to have the unevenness 32a that reflects the visible light introduced therein to the viewing side. The unevenness 32a has a shape in which peaks and valleys are alternately and repeatedly appearing in the two-dimensional direction at a pitch and a protrusion height equal to or longer than the wavelength of visible light emitted from the light source 41 (for example, in the range of 1 to 10 μm). Presents.

The “pitch equal to or more than the wavelength of visible light emitted by the light source 41” is strictly a pitch equal to or greater than the minimum wavelength of the visible light emitted by the light source 41. The same applies to the protruding height. In addition, the pitch of the irregularities 32a of the reflective structure 32 means the dimension between the adjacent peaks with a valley in between, and in the case where there is variation in the dimension inside the continuous reflective structure 32, the dimension is concerned. Means the average value of.

When the visible light from the light source 41 enters the reflecting structure 32, the visible light is reflected once or a plurality of times at the peaks and valleys, and thus can be reflected to the viewing side. Since the reflected visible light is radially emitted from the front surface 31a, it is visually recognized that the reflective structure 32 emits light in a planar shape. Therefore, the region RR in which the reflective structure 32 is formed is recognized as a design.

Now, as shown in an enlarged view in FIG. 4, the reflective structure 32 of the present embodiment is not necessarily formed without a gap in the recognition region RR recognized as a pattern. In the recognition region RR, small regions SS are arranged in a two-dimensional direction and are divided in a grid pattern having a pitch sufficiently larger than the pitch of the irregularities 32a (for example, in the range of 20 to 100 μm). The reflective structure 32 is formed in a part of the small areas SS among the plurality of small areas SS. It is also possible to adjust the brightness of each part of the pattern by the ratio of the area of the small region SS where the reflecting structure 32 is formed and the small region SS where the reflecting structure 32 is not formed. Specifically, the reflective structure 32 of the present embodiment is provided in a part of the small area SS that forms a check pattern by skipping one.

Note that, in FIG. 3, a portion in which the reflective structure 32 is arranged is shown by dot-shaped hatching.

In addition, the unevenness 32a of the reflective structure 32 of the present embodiment is set to a fine size in which each uneven shape is unrecognizable to the naked eye while having a pitch and a protrusion height equal to or longer than the wavelength of visible light emitted from the light source 41. To be done. Thereby, when the light source 41 is turned off, it is possible to make the viewer substantially unable to recognize the design.

Even inside the recognition region RR, it is preferable that the reflection regulation structure 33 is formed in a portion where the reflection structure 32 is not formed, and this is also the case in the present embodiment. Of course, outside the recognition region RR, of the reflection structure 32 and the reflection regulation structure 33, substantially only the reflection regulation structure 33 is formed.

The reflection regulation structure 33 is formed to have irregularities 33a that regulate the reflection of external light such as sunlight or visible light emitted from the image display 21 on the front surface 31a. The unevenness 33a of the reflection restricting structure 33 is significantly different from the unevenness 32a of the reflective structure 32, and the peaks and the peaks are formed at a pitch smaller than the wavelength of visible light emitted from the light source 41 (for example, in the range of 100 to 200 nm). It has a shape in which valleys appear alternately and repeatedly in a two-dimensional direction.

The "smaller pitch than the wavelength of the visible light emitted by the light source 41" is, strictly speaking, a pitch smaller than the minimum wavelength of the visible light emitted by the light source 41. In addition, the pitch of the unevenness 33a of the reflection regulation structure 33 means a dimension between adjacent peaks with a valley portion interposed therebetween, and when there is a variation in the dimension inside the continuous reflection regulation structure 33, It means the average value of the dimension.

Such a reflection regulation structure 33 is also generally called a moth-eye structure. As shown in an enlarged manner in FIG. 5, the mountain portion of the reflection restricting structure 33 is a cone-shaped protrusion 33b that protrudes in a cone shape (for example, a cone shape) from the rear surface side to the viewer side. In the reflection regulation structure 33, the effective refractive index for light having a wavelength smaller than the pitch of the unevenness 33a functions so as to continuously decrease from the base end portion to the tip end portion of the conical protrusion 33b. .. Therefore, the reflection of light at the interface is regulated at the portion where the reflection regulation structure 33 is formed.

In the present embodiment, the pattern formed by the reflective structure 32 is an index ID designated by the pointer PD. Two index IDs are displayed side by side corresponding to each pointer PD. Each index ID is formed by arranging the scale ID1 and the character ID2 corresponding to the scale ID1 in an annular shape concentric with the rotation center RC of the pointer PD. The scale ID1 is located closer to the outer periphery than the character ID2 with respect to the rotation center RC. The character ID2 is entirely arranged inside the overlapping region OR1 of the optical layered portion 31 which overlaps the display screen 22. On the other hand, a part of the graduation ID1 is arranged outside the overlapping region OR1 in the optical layered portion 31, that is, outside the protruding region OR2.

In the present embodiment, the index ID on the left side displays the speed in cooperation with the pointer PD because the character ID2 is a number representing the speed of the vehicle. The index ID on the right side displays the engine speed in cooperation with the pointer PD because the character ID2 is a number representing the engine speed of the vehicle. In this way, the image on the display screen 22 and the design by the optical layered portion 31 adhered to the display screen 22 cooperate with each other to realize an integrated display having good visibility and being difficult to be displaced from each other. ing.

(Effect)
The operation and effect of the first embodiment described above will be described again below.

According to the first embodiment, what introduces the visible light from the light source 41 into the inside is the optical layered portion 31 formed in a layer using an optical adhesive material having translucency. At least a part of the front surface 31 a of the optical layered portion 31 is provided with the unevenness 32 a of the reflecting structure 32 that reflects the introduced visible light to the viewer side. Since the front surface 31a is exposed on the viewing side, even if the reflection structure 32 is formed on the front surface 31a, the refractive index difference at the interface can be set to be large, so that efficient reflection is realized. .. By forming the reflective structure 32 on the front surface 31a, the back surface 31b can be bonded to the display screen 22. By adhering the back surface 31b and the display screen 22, even when external light such as sunlight enters from the outside of the device 10, the back surface 31b and the display screen 22 reflect the external light. Suppressed. Therefore, it is possible to prevent the visibility of the display from being deteriorated during the daytime. As described above, the display device 10 having good visibility can be provided.

Further, according to the first embodiment, the reflection regulation structure 33 that regulates the reflection of the light on the front surface 31a in at least a part of the front surface 31a of the optical layered portion 31 excluding the reflection structure 32. Unevenness 33a is formed. Since reflection of the external light on the front surface 31a is also suppressed by the reflection restricting structure 33, it is possible to further suppress the deterioration of the visibility of the display during the daytime. Since both the reflection structure 32 and the reflection regulation structure 33 are formed on the front surface 31a by the concavities and convexities, the steps for forming the concavities and convexities 32a, 33a can be made common. As described above, it is possible to easily manufacture the display device 10 having good visibility.

According to the first embodiment, the unevenness 32a of the reflective structure 32 is formed with a pitch larger than the wavelength of visible light, and the unevenness 33a of the reflection regulation structure 33 is formed with a pitch smaller than the wavelength of visible light. Has been formed. Since the opposite reflection function is realized by the difference in pitch between the unevennesses 32a and 33a, it is possible to easily manufacture the display device 10 having good visibility.

Further, according to the first embodiment, the pointer PD is displayed on the display screen 22, and the index ID indicated to the pointer PD is displayed by the pattern formed by the reflective structure 32. Since the pointer PD and the index ID are displayed by the display member having different properties, the pointer PD and the index ID can be easily distinguished, and the display can be easily read. Further, since the optical layered portion 31 is adhered to the display screen 22 without being separated from the display screen 22, parallax is unlikely to occur between the pointer PD and the index ID, and even if vibration of the vehicle occurs, for example, the pointer PD and the index ID. Since the relative position to the ID is maintained, it is easy to read the displayed value accurately. Therefore, the display device 10 having good visibility can be provided.

Further, according to the first embodiment, the reflective structure 32 is arranged so as to extend outside the overlapping region OR1 overlapping the display screen 22. According to such protrusion, it is possible to realize a display with a sense of expanse, regardless of the size of the display screen 22.

Further, according to the first embodiment, the back surface 31b and the display screen 22 are planarly bonded. Due to such planar adhesion, there is very little room for an air layer to intervene between the back surface 31b and the display screen 22, and therefore the effect of suppressing reflection of external light on the back surface 31b and the display screen 22 is extremely high. Will be things.

(Other embodiments)
Although one embodiment has been described above, the present disclosure should not be construed as being limited to the embodiment, and can be applied to various embodiments without departing from the scope of the present disclosure.

Specifically, as a first modification, a thin and flexible resin OLED display that is flexible and thin can be used as the image display 21, and a liquid crystal display or the like other than the OLED display can be used.

As a second modification, the front surface 22a of the display screen 22 may have a curved surface shape or may have some irregularities.

As a third modification, the reflection restricting structure 33 may not be provided, and the portion of the front surface 31a excluding the reflective structure 32 may be formed flat.

As a modified example 4, an arbitrary design can be adopted as the design displayed by the reflection structure 32. For example, the design may be a design of a warning light that displays a warning. Further, for example, a design that does not display information such as a decorative design that decorates the display screen 22 may be adopted.

As a fifth modification, not only the pointer PD but also any image can be adopted as the image displayed on the display screen 22.

As a modified example 6, the light source 41 is not limited to one using an inorganic light emitting diode, but the light source 41 may be configured using, for example, a fluorescent tube, an organic light emitting diode, a laser light source, or the like.

As a modified example 7, the display device 10 is not limited to one used in a vehicle, for example, a display device used in a moving body such as an aircraft or a ship, a home electric appliance such as a refrigerator, an information communication device such as a smartphone, a game, a pachinko machine. It may be a game machine such as a display device used for street advertising.

The numerical range of each constituent element described in the first embodiment is not limited to this, and can be appropriately selected according to the application of the display device.

21 image display, 22 display screen, 31 optical layered portion, 31a front surface, 32b back surface, 32 reflective structure, 32a unevenness, 41 light source

Claims (6)

An image display device (21) for displaying an image on the display screen (22),
A light source (41) that emits visible light,
An optical layered portion (31) which is formed in a layer using an optical adhesive material having translucency and which introduces the visible light from the light source into the inside thereof,
The optical layered portion has a reflection structure (32) having, on at least a part of a front surface (31a) exposed on the viewing side, unevenness (32a) that reflects the visible light introduced into the inside to the viewing side. And a display device in which at least a part of the back surface (32b) opposite to the front surface is adhered to the display screen. At least a part of the area excluding the reflection structure of the front surface is provided with a reflection restriction structure (33) having irregularities (33a) for restricting reflection of light on the front surface. The display device according to claim 1. The unevenness of the reflection structure is formed at a pitch equal to or larger than the wavelength of the visible light, and the unevenness of the reflection regulation structure is formed at a pitch smaller than the wavelength of the visible light. Display device. A pointer (PD) is displayed on the display screen,
The display device according to any one of claims 1 to 3, wherein an index (ID) indicated by the pointer is displayed by a pattern formed by the reflective structure. The display device according to any one of claims 1 to 4, wherein the reflective structure is disposed outside the overlapping region (OR1) that overlaps the display screen in the optical layered portion. The display device according to claim 1, wherein the back surface and the display screen are bonded in a planar shape.

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