JP7545641B2 - Display device - Google Patents

Description

This disclosure relates to a display device mounted on a vehicle, etc.

A head-up display is mounted on a vehicle and projects various information, such as information necessary for the driver to drive, onto a projection member such as a windshield. Today, with the increase in the amount of information and the diversification of the types of information, the methods of displaying images provided to the driver are also diversifying. For example, it is required to display images at any position or with an inclination. Such display control is performed, for example, by reflecting the display light related to the image by passing it through a reflecting means such as a prism lens and changing the direction or angle to any direction, or by devising the placement of the display device within the instrument panel.

JP 2013-047021 A

To ensure the visibility of images for the driver, the display device is required to project the display light without reducing its brightness.

This disclosure has been made in consideration of these circumstances, and aims to provide a display device that can project an image with good visibility at a desired position.

In order to solve the above-mentioned problems, the display device of the present disclosure has a display unit that emits display light related to an image to be viewed by a viewer, a case that houses the display unit and has an opening through which the display light passes, a protective cover that transmits the display light and covers the opening, and a display light control layer that is disposed between the protective cover and the display unit and changes the direction of the transmitted display light, the display light control layer being made of a film having a transparent base and a transparent refractive portion that is disposed in the base and has a refractive index different from that of the base and changes the direction of the transmitted display light, the case being disposed within an instrument panel on which the display device is to be installed, and the display unit emits the display light that is projected and reflected onto a windshield on which the display device is to be installed and viewed by the viewer.

The display device disclosed herein can project an image at a desired position with good visibility.

1 is an explanatory diagram showing an embodiment of a display device according to the present disclosure, the display device being mounted on a vehicle; FIG. 1 is a cross-sectional view illustrating a structure of a display device. FIG. 2 is a cross-sectional view illustrating a display light control layer. FIG. 11 is a cross-sectional view illustrating another display light control layer.

An embodiment of the display device of the present disclosure will be described with reference to the attached drawings. The display device of the present disclosure can be applied to a display device mounted on a vehicle such as an automobile or motorcycle, a ship, an agricultural machine, or a construction machine. The display device is disposed in the instrument panel of the vehicle in which it is mounted, and displays a real or virtual image on the windshield for a viewer to view. In this embodiment, an example will be described in which the display device is disposed in the instrument panel of an automobile in which it is mounted.

FIG. 1 is an explanatory diagram showing a display device 1 mounted on a vehicle, according to an embodiment of the display device of the present disclosure.
FIG. 2 is a cross-sectional view for explaining the structure of the display device 1. As shown in FIG.

The display device 1 is a so-called head-up display (HUD), which projects display light 2 onto the vehicle's windshield 3, which is a projection member, and reflects it in the direction of the driver 4 (viewer) of the vehicle. In particular, the display device 1 projects and reflects the display light 2 onto a light-shielding portion 3a formed around the periphery of the windshield 3, allowing the driver 4 to view it.

The light-shielding portion 3a is a portion made of black ceramics or the like and has a light-shielding color such as black. The light-shielding portion 3a is formed for the purpose of preventing deterioration of the adhesive that secures the windshield 3 to the vehicle due to sunlight, concealing the adhesive, improving the design, etc.

The display device 1 has a case 10, a protective cover 20, a display unit 30, and a display light control layer 40.

The case 10 supports and houses the display unit 30. The case 10 is made of, for example, a synthetic resin having light-blocking properties (for example, black polypropylene). The case 10 has an opening 11 that allows the display light 2 to pass through in the portion facing the windshield 3. The case 10 also has an attachment structure (not shown) for being placed in a space provided within the instrument panel 5. The case 10 is placed, for example, so that the opening surface (protective cover 20) is parallel to the surface 5a of the instrument panel 5.

The protective cover 20 is a plate-shaped member made of a translucent synthetic resin (e.g., inorganic glass, polycarbonate resin, PMMA resin). The protective cover 20 covers the opening 11 of the case 10, thereby protecting the display unit 30 inside the case 10 from moisture, dust, etc.

The display unit 30 has a display panel 31 and a backlight unit 32.

The display panel 31 is disposed on the front side of the display unit 30. The display panel 31 is, for example, a TFT (Thin Film Transistor) type liquid crystal display panel. The display panel 31 has a pair of glass substrates that encapsulate a liquid crystal layer. Transparent electrodes are formed on the pair of glass substrates using ITO (Indium Tin Oxide) or the like. The display panel 31 also has a pair of polarizing plates (polarizing filters) that are arranged to sandwich the pair of glass substrates.

The display panel 31 is connected to a circuit board (not shown) provided separately from the display device 1 via an FPC (Flexible Printed Circuits, not shown). The display panel 31 is controlled by a control unit such as a graphics controller on the circuit board, and a drive voltage is applied to the liquid crystal layer via the transparent electrodes. The orientation of the liquid crystal molecules in the liquid crystal layer is controlled to change the transmittance of each pixel.

The backlight unit 32 is disposed behind the display panel 31. The backlight unit 32 has a light source substrate 33 and an optical sheet 34. The light source substrate 33 has a plurality of LEDs (Light Emitting Diodes) 35. The light source substrate 33 is connected to the above-mentioned circuit board via an FPC. The LEDs 35 emit light when a driving current is supplied. The optical sheet 34 is, for example, a prism sheet that diffuses light. The light emitted from the LEDs 35 illuminates the display panel 31 through the optical sheet 34. As a result, the display unit 30 emits display light 2 related to an image to be viewed by the viewer.

The display light control layer 40 is disposed between the protective cover 20 and the display unit 30, and changes the direction of the transmitted display light 2. Here, FIG. 3 is a cross-sectional view illustrating the display light control layer 40. The display light control layer 40 is a film-like member having a base 41, a refracting portion 42, and a film 46.

The base 41, the refraction portion 42, and the film 46 are made of transparent synthetic resins with different refractive indices. In order to prevent the occurrence of rainbow unevenness when wearing polarized sunglasses, the base 41 and the refraction portion 42 are preferably made of PMMA, polycarbonate, TAC (Triacetylcellulose), or the like, which have low retardation (phase difference).

The refraction section 42 has a triangular convex shape in cross section that narrows from the incident surface 44 of the display light 2 of the display light control layer 40 to the exit surface 45. The base 41 has a plurality of refraction sections 42 of approximately the same shape uniformly spaced apart at regular intervals in one direction (left-right direction in FIG. 3) in the plane of the display light control layer 40. As a result, the display light control layer 40 passes the display light 2a incident from the incident surface 44 at an incident angle within a predetermined range through the base 41 without changing the direction, and emits it from the exit surface 45. On the other hand, the display light control layer 40 reflects the display light 2b incident from the incident surface 44 at an incident angle outside the predetermined range at the refraction section 42 to change the direction, and emits it from the exit surface 45 at a predetermined angle that is approximately parallel to the emission angle of the display light 2a. The display light control layer 40 is designed according to the emission direction of the display light 2 emitted from the display device 1. Specifically, the shape and optical characteristics of the refracting portion 42 are determined so that the display light 2 is emitted toward the light-shielding portion 3a.

The display light control layer 40 is fixed to the protective cover 20 on the emission surface 45 side via an optical bonding layer 51 (adhesive layer). The optical bonding layer 51 is made of a transparent synthetic resin (e.g., a silicone-based, urethane-based, or acrylic-based resin). The display light control layer 40 is fixed to the display panel 31 on the incidence surface 44 side via an adhesive layer 52 (adhesive layer) made of an adhesive.

The optical bonding layer 51 and the adhesive layer 52 may be arranged in reverse. However, the embodiment shown in FIG. 3 is preferable because a closer distance between the display panel 31 and the display light control layer 40 can reduce double display (visualization).

In such a display device 1, the direction of the display light 2 emitted from the display device 1 can be set arbitrarily using the display light control layer 40. This allows the display device 1 to emit the display light 2 toward a desired position on the windshield 3, and to display a variety of information in a variety of ways.

For example, if the refraction section 42 is made of a synthetic resin such as black, this will be perceived by the viewer as a black line, resulting in a decrease in display quality. In contrast, in the present display device 1, the refraction section 42 is made of a transparent synthetic resin, so the viewer does not see any black line portions.

In addition, if the refraction section 42 is made of synthetic resin, such as black, some of the display light 2b reflected by the refraction section 42 is absorbed during reflection, resulting in a decrease in reflectance. In contrast, in the present display device 1, the refraction section 42 is made of a transparent synthetic resin, so some of the light is not absorbed.

For example, it is possible to control the direction of light emitted from the backlight unit 32 using a prism lens or the like and have it enter the display panel 31, but if light enters the display panel 31 at an angle, the brightness of the image will decrease significantly. Also, an air layer is formed between the rear surface of the display panel 31 and the prism lens, and transmission loss occurs due to refraction of light at the rear surface of the display panel 31 and the front surface of the prism lens, reducing the brightness of the image. In contrast, the display device 1 controls the direction of the display light 2 emitted from the display panel 31 using the display light control layer 40, reducing the decrease in brightness of the display light 2 due to refraction and providing excellent image visibility.

Furthermore, since the emission direction of the display device 1 can be set arbitrarily, the placement of the display device 1 within the instrument panel 5 is not restricted, and the degree of freedom in design is also improved. In other words, the placement location and attitude of the display device 1 are not restricted by the projection location of the display light 2.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

In the display device 1, the tip of the refracting portion 42 on the front side is triangular, but it may be curved. Also, the refracting portions 42 are arranged at regular intervals, but they may be formed so that the refracting portions 42a are connected and the gaps are filled by the base portion 41a, as in the display light control layer 40a shown in FIG. 4.

For example, the display device 1 of the present disclosure has been described as projecting the display light 2 onto the light-shielding portion 3a of the windshield 3, but the display device 1 may project the display light 2 onto a transparent portion of the windshield 3, allowing the viewer to view a real image or a virtual image.

The configuration of the display unit 30, i.e., the display panel 31 that generates the display light 2 and the backlight unit 32 that emits backlight for the display panel 31, are examples, and various configurations of the display unit of known head-up displays may be applied.

1 Display device 2, 2a, 2b Display light 3 Windshield 3a Shading part 4 Driver (viewer)
5: Instrument panel 5a; Surface 10: Case 11: Opening 20: Protective cover 30: Display unit 31: Display panel 32: Backlight unit 33: Light source substrate 34: Optical sheet 35: LED
40, 40a Display light control layer 41, 41a Base 42, 42a Refraction portion 44 Incident surface 45 Exit surface 46 Film 51 Optical bonding layer (adhesive layer)
52 Adhesive layer (adhesive layer)

Claims (3)

a display unit that emits display light related to an image to be viewed by a viewer;
a case that houses the display unit and has an opening through which the display light passes;
a protective cover that transmits the display light and covers the opening;
a display light control layer disposed between the protective cover and the display unit and configured to change the direction of the display light transmitted therethrough;
the display light control layer is made of a film having a transparent base and a transparent refractive portion disposed in the base and having a refractive index different from that of the base, thereby changing the direction of the display light transmitted therethrough;
The case is disposed in an instrument panel in which the case is mounted,
The display unit is a display device that emits the display light, which is projected and reflected on a windshield where the display unit is mounted, and is visible to the viewer . The display device according to claim 1, wherein the display light control layer is fixed to the display unit and the protective cover via an adhesive layer. 3. The display device according to claim 2, wherein the display light control layer is fixed to the protective cover via an optical bonding layer made of a transparent resin, and is fixed to the display unit via an adhesive layer made of an adhesive material.

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