WO2024042632A1

WO2024042632A1 - In-vehicle display device

Info

Publication number: WO2024042632A1
Application number: PCT/JP2022/031850
Authority: WO
Inventors: 真彦宇野; 満坂井
Original assignee: 三菱電機株式会社
Priority date: 2022-08-24
Filing date: 2022-08-24
Publication date: 2024-02-29

Abstract

The purpose of the present disclosure is to restrict, in an in-vehicle display device that has a horizontally long display surface spanning across the driver seat side and the passenger seat side, the viewing angle only in a partial region of the display surface. An in-vehicle display device according to the present disclosure comprises: a display surface (15); a light source (11); a viewing angle restriction structure (12) that is disposed between the light source (11) and the display surface (15) so as to form a laminate with the display surface (15), and that narrows the viewing angle of light which has entered from the light source (11) and emits the light; a viewing angle widening structure (13) that is disposed between the viewing angle restriction structure (12) and the display surface (15) so as to form a laminate with the viewing angle restriction structure (12) and the display surface (15), that is sectioned into a plurality of sectional regions in the planar direction which is parallel to the display surface (15), and that performs either transmission or diffusion of light which has entered from the viewing angle restriction structure (12); and a transmission-diffusion control unit (14) that carries out, with respect to each of the plurality of sectional regions, transmission-diffusion control for controlling which one of transmission and diffusion the viewing angle widening structure (13) performs on light entered from the viewing angle restriction structure (12).

Description

In-vehicle display device

The present disclosure relates to an in-vehicle display device.

In recent years, in-vehicle display devices have been proposed that have a horizontally elongated display surface that spans the entire surface of a vehicle dashboard. According to such an in-vehicle display device, an image for the driver's seat can be displayed on a portion of the display surface in front of the driver's seat, and an image for the passenger seat can be displayed on a portion in front of the passenger seat. However, there was a problem in that the image intended for the passenger seat could be seen from the driver's seat, causing the driver's attention to be diverted.

If the in-vehicle display device has separate display screens for the driver's seat and passenger's seat, the viewing angle of only the display screen on the passenger's seat is narrowed to prevent the driver from seeing images for the passenger's seat. be able to. However, in an in-vehicle display device having a horizontally long display surface, the viewing angle is constant between the driver's seat side and the passenger seat side, so it is difficult to prevent the driver from seeing images for the passenger seat.

As a conventional technology related to viewing angle control of a vehicle-mounted display device having a horizontally long display surface, Patent Document 1 discloses an example of the combined use of an optical element for controlling the viewing angle and a transmission/scattering switching element. The problem with this conventional example is that when the display surface becomes horizontally long, the peripheral area of the display surface is perceived to be dark. The peripheral area of the display surface has a large horizontal viewing angle from the viewer, so it is perceived as dark due to the viewing angle characteristics of the liquid crystal.

As a solution to this problem, the technology in Patent Document 1 improves the brightness for a specific viewer by using an optical element that optimizes the viewing angle of the display surface so that light is projected toward the specific viewer. are doing. Furthermore, since this will deteriorate the brightness for observers other than a specific observer, if there are multiple observers, the viewing angle is widened by scattering light with a transmission/scattering switching element.

Japanese Patent Application Publication No. 2011-95719

The technology of Patent Document 1 improves the visibility of the periphery of the display surface by controlling the viewing angle, and does not limit the visibility of a part of the display surface.

The present disclosure has been made in order to solve the above-mentioned problems, and in an in-vehicle display device that has a horizontally long display screen extending between the driver's seat side and the passenger seat side, the viewing angle is limited to only a part of the display screen. The purpose is to limit the

The in-vehicle display device of the present disclosure is an in-vehicle display device installed in a vehicle, and includes a display surface that is continuously arranged from the front of the driver's seat of the vehicle to the front of the front passenger seat of the vehicle, and a light source. , a viewing angle limiting structure is provided between the light source and the display surface to be laminated with the display surface, and narrows the viewing angle of the light incident from the light source and outputs the light; A viewing angle expanding structure is provided in a laminated manner with the limiting structure and the display surface, is divided into a plurality of divided regions in a plane direction parallel to the display surface, and transmits or diffuses light incident from the viewing angle limiting structure. , a transmission and diffusion control unit that performs transmission and diffusion control to control whether the viewing angle expansion structure transmits or diffuses the light incident from the viewing angle restriction structure for each of the plurality of divided regions.

The in-vehicle display device of the present disclosure can control whether light is transmitted or diffused for each segmented area of the viewing angle expansion structure. Therefore, in the viewing angle expansion structure, the viewing angle can be narrowed in the region where light is transmitted, and the viewing angle can be widened in the region where light is diffused. In this way, the viewing angle of a partial area of the display surface can be narrowed. Objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and accompanying drawings.

1 is a diagram showing the configuration of an in-vehicle display device according to Embodiment 1. FIG. 1 is a front view of a liquid crystal display device according to Embodiment 1. FIG. 1 is a cross-sectional view of a liquid crystal display device according to Embodiment 1. FIG. 1 is a cross-sectional view of a liquid crystal display device according to Embodiment 1. FIG. It is a figure showing light diffusion control in a PDLC film. It is a figure showing light transmission control in a PDLC film. FIG. 2 is a cross-sectional view of a liquid crystal display device in which the viewing angle is controlled by dividing the display screen into three parts. FIG. 2 is a front view of a liquid crystal display device that controls the viewing angle by dividing the display screen into three parts. FIG. 2 is a front view of a liquid crystal display device that controls the viewing angle by dividing the display surface into a 5×21 mesh. It is a figure showing a viewing angle when there is no LCF. It is a figure which shows the viewing angle when there is LCF. FIG. 7 is a diagram showing viewing angles when the spacing between louvers is narrowed in the LCF. It is a figure which shows the viewing angle when a louver is made high in LCF. It is a figure which shows the viewing angle when a louver is tilted in LCF. FIG. 3 is a diagram showing the structure of an LCF that widens the viewing angle at the center of the display screen. 3 is a flowchart showing the operation of the in-vehicle display device according to the first embodiment. FIG. 3 is a diagram showing the configuration of an in-vehicle display device according to a second embodiment. FIG. 3 is a diagram showing the hardware configuration of a transmission diffusion control section and a brightness control section. FIG. 3 is a diagram showing the hardware configuration of a transmission diffusion control section and a brightness control section.

<A. Embodiment 1>
<A-1. In-vehicle display device>
FIG. 1 is a diagram showing the configuration of an in-vehicle display device 101 according to the first embodiment. The in-vehicle display device 101 is a display device mounted on a vehicle, and includes a light source 11 , a viewing angle limiting structure 12 , a viewing angle expanding structure 13 , a transmission diffusion control section 14 , and a display surface 15 .

The viewing angle limiting structure 12, the viewing angle expanding structure 13, and the display surface 15 are stacked in this order, and the light emitted from the light source 11 reaches the display surface 15 via the viewing angle restricting structure 12 and the viewing angle expanding structure 13.

The light source 11 emits light toward the viewing angle limiting structure 12.

The viewing angle limiting structure 12 is provided between the light source 11 and the display surface 15 and limits the viewing angle of the light emitted from the light source 11. The viewing angle limiting structure 12 reduces the viewing angle of light in all areas in the direction of the display surface.

The light whose viewing angle is limited by the viewing angle limiting structure 12 enters the viewing angle expanding structure 13. The viewing angle expanding structure 13 is provided between the viewing angle limiting structure 12 and the display surface 15. The viewing angle expansion structure 13 is divided into a plurality of regions in the direction of the display surface. Some areas of the viewing angle expansion structure 13 widen the viewing angle of the light incident from the viewing angle limiting structure 12 and output it to the display surface 15, while other areas receive the light incident from the viewing angle limiting structure 12. The light is output to a display surface 15 without changing the viewing angle. Here, in the viewing angle expansion structure 13, the area where the viewing angle is increased is referred to as a viewing angle expansion area, and the area where the viewing angle is not changed is referred to as a viewing angle unchanged area.

The transmission diffusion control unit 14 controls which areas of the viewing angle expansion structure 13 are designated as viewing angle expansion areas and viewing angle unchanged areas.

The light whose viewing angle is controlled by the viewing angle expansion structure 13 is emitted from the display surface 15 to the outside of the vehicle-mounted display device 101 as display light. Here, from the portion of the display surface 15 located directly above the viewing angle expansion area of the viewing angle expansion structure 13, the viewing angle is narrowed by the viewing angle restriction structure 12, and then the viewing angle is narrowed by the viewing angle expansion area. Expanded light is emitted. Further, from a portion of the display surface 15 located directly above the viewing angle constant area of the viewing angle expanding structure 13, light is emitted with the viewing angle narrowed by the viewing angle limiting structure 12. Therefore, the viewing angle of the portion of the display surface 15 located directly above the viewing angle constant region of the viewing angle expanding structure 13 is lower than that of the portion located directly above the viewing angle expanding region of the viewing angle expanding structure 13. small.

<A-2. Liquid crystal display>
2 to 4 show the configuration of a liquid crystal display device 201, which is an example of the in-vehicle display device 101 according to the first embodiment. FIG. 2 is a front view of the liquid crystal display device 201, and FIGS. 3 and 4 are cross-sectional views of the liquid crystal display device 201 taken along line AA' in FIG. As shown in FIG. 3, the liquid crystal display device 201 includes a direct backlight 21, a light guide plate 22, a diffusion sheet 23, a lens sheet 24, a light control film (LCF) 25, and a PDLC (Polymer Dispersed Liquid Crystal). ) The film 26 and the liquid crystal panel 28 are laminated in this order.

The upper surface of the liquid crystal panel 28 corresponds to the display surface 15 of the in-vehicle display device 101.

The direct backlight 21 corresponds to the light source 11 of the in-vehicle display device 101.

The light emitted from the direct type backlight 21 and incident on the light guide plate 22 spreads within the light guide plate 22, passes through the diffusion sheet 23 and the lens sheet 24 in this order, and enters the LCF 25.

The LCF 25 corresponds to the viewing angle limiting structure 12 of the in-vehicle display device 101. The LCF 25 includes a plurality of louvers 25L spaced apart from each other. The louver 25L blocks light at a large angle with respect to the vertical direction perpendicular to the display surface 15. This limits the viewing angle of the display surface 15.

The PDLC film 26 constitutes the viewing angle expansion structure 13 of the in-vehicle display device 101. Although not shown in FIG. 3, as shown in FIG. 5, the PDLC film 26 is sandwiched between two transparent ITO (Indium Tin Oxide)

electrodes

31 and 32, and two more ITO (Indium Tin Oxide) electrodes from the outside. It is sandwiched between PET (Polyethylene Terephthalate)

films

33 and 34. That is, the PDLC film 26 and

ITO electrodes

31 and 32 in the liquid crystal display device 201 correspond to the viewing angle expansion structure 13 of the in-vehicle display device 101. The PDLC film 26 has a structure in which spherical liquid crystal capsules 29 are enclosed within a polymer matrix 27.

The PDLC film 26 diffuses or transmits light passing through the PDLC film 26 depending on the applied voltage. The transmission diffusion control unit 14 controls the diffusion and transmission of light passing through the PDLC film 26 by controlling on/off of the voltage applied between the

ITO electrodes

31 and 32 at both ends of the PDLC film 26.

As shown in FIG. 5, when no voltage is applied between the

ITO electrodes

31 and 32, the orientation of the liquid crystal 30 confined in the liquid crystal capsule 29 varies. Therefore, the light incident on the PDLC film 26 is diffused by the PDLC film 26. That is, the PDLC film 26 is in a "diffusion mode" that diffuses light.

On the other hand, as shown in FIG. 6, when a voltage is applied between the

ITO electrodes

31 and 32, the orientation of the liquid crystal 30 confined in the liquid crystal capsule 29 is aligned in one direction. Therefore, the light incident on the PDLC film 26 passes straight through the PDLC film 26. That is, the PDLC film 26 is in a "transmission mode" in which light is transmitted.

The light emitted from the PDLC film 26 enters the liquid crystal panel 28 and is emitted from the display surface 15 as display light. Therefore, as shown in FIG. 3, light with a relatively large viewing angle is emitted from the liquid crystal panel 28 directly above the PDLC film 26 in the diffusion mode. On the other hand, as shown in FIG. 4, light with a relatively small viewing angle is emitted from the liquid crystal panel 28 directly above the PDLC film 26 in the transmission mode.

In the liquid crystal display device 201, the viewing angle of the horizontally long display surface 15 is controlled not uniformly but for each part. To make this possible, at least one of the

ITO electrodes

31 and 32 is divided and arranged in a plane direction parallel to the display surface 15.

FIG. 7 shows an example in which the ITO electrode 31 is divided into three

ITO electrodes

311, 312, and 313 in the plane direction. In this case, the ITO electrode 32 becomes a common electrode. The transmission diffusion control section 14 controls voltage application between each of the

ITO electrodes

311, 312, and 313 with respect to the ITO electrode 32. For example, if a voltage is applied only between the ITO electrode 313 and the ITO electrode 32, only the area directly under the ITO electrode 313 in the PDLC film 26 will be in the transmission mode, and the other areas will be in the diffusion mode. As a result, the viewing angle of only the area directly above the ITO electrode 313 on the display surface 15 is narrowed, and the viewing angle becomes smaller than the area directly above the

ITO electrodes

311 and 312.

By dividing the ITO electrode 31 into the

ITO electrodes

311, 312, and 313 in this way, the transmission diffusion control section 14 can individually control each of the areas directly under the

ITO electrodes

311, 312, and 313 in the PDLC film 26. This makes it possible to perform transmission/diffusion control. In other words, the PDLC film 26 is divided into sections corresponding to the

ITO electrodes

311, 312, 313 in the plane direction. Moreover, the area directly under the

ITO electrodes

311, 312, and 313 in the PDLC film 26 is also referred to as a segmented area.

Although FIG. 7 shows an example in which the upper ITO electrode 31 is divided, the lower ITO electrode 32 may be divided instead of the ITO electrode 31. In this case, the ITO electrode 31 becomes a common electrode.

FIG. 8 shows a plan view of the liquid crystal display device 201 in which the ITO electrode 31 is divided into

ITO electrodes

311, 312, and 313 similarly to FIG. In FIG. 8, the liquid crystal panel 28 provided on the ITO electrode 31 is not shown in order to show how the ITO electrode 31 is divided. This also applies to FIG. 9, which will be described later. Of the display surface 15, the area directly above the ITO electrode 311 is the driver's seat side area located in front of the driver's seat, and the area directly above the ITO electrode 313 is the passenger seat side area located in the front front of the passenger seat. The area directly above the ITO electrode 312 is a central area located between the driver's seat side area and the passenger seat side area. The driver's seat side area, the passenger seat side area, and the center area are also referred to as a first display area, a second display area, and a third display area, respectively.

Therefore, according to the configuration shown in FIG. 8, the viewing angle can be individually controlled for the driver's seat side area, the passenger seat side area, and the center area of the display surface 15. For example, the transmission diffusion control unit 14 can prevent the driver from viewing the image on the passenger seat side by narrowing the viewing angle of only the passenger seat side region of the display surface 15.

Although FIG. 8 shows an example in which the ITO electrode 31 is divided into three parts: the driver's seat side, the center part, and the passenger seat side, the example in which the ITO electrode 31 is divided is not limited to this. As shown in FIG. 9, the ITO electrode 31 may be divided into a mesh shape such as 5×21 squares. According to the example of FIG. 9, it is possible to control the viewing angle of the display surface 15 for each finer region.

<A-3. LCF＞
In the liquid crystal display device 201, the LCF 25 corresponds to the viewing angle limiting structure 12. The LCF 25 includes a light absorbing plate called a louver 25L. 10 to 14 show changes in the viewing angle depending on the shape or arrangement of the louver 25L. 10 to 14, the upper side of the figure is the display surface 15 side of the liquid crystal display device 201, and the lower side is the back side opposite to the display surface 15.

FIG. 10 shows a comparative example without the LCF 25. In this case, the viewing angle of the light passing through the lens sheet 24 is large. 11 to 14 show the case where the LCF 25 is provided. As shown in FIG. 11, when the LCF 25 is present, the viewing angle is smaller than when the LCF 25 is not present.

FIG. 12 shows a case where the arrangement interval of the louvers 25L is narrower than that in FIG. 11. In this case, the viewing angle will be smaller than that in FIG. FIG. 13 shows a case where the arrangement intervals of the louvers 25L are the same as in FIG. 11, and the height of the louvers 25L is increased. In this case, the viewing angle will be smaller than that in FIG. FIG. 14 shows a case where the louver 25L is tilted to the right. In this case, the viewing angle becomes asymmetrical with a wide rightward view.

In the liquid crystal display device 201 of this embodiment, the viewing angle of light is made small in advance by the LCF 25, and then the viewing angle is made large in a portion of the display surface 15 by the diffusion function of the PDLC film 26. That is, the narrow viewing angle characteristic of the liquid crystal display device 201 is due to the contribution of the LCF 25, and the wide viewing angle characteristic is due to the contribution of the PDLC film 26. By using the LCF 25 and the PDLC film 26 together, it is possible to switch between a narrow viewing angle and a wide viewing angle.

Therefore, the height and arrangement interval of the louvers 25L are determined in advance depending on how much the viewing angle should be reduced in the area of the display surface 15 where the viewing angle is desired to be limited.

In the driver side area of the display surface 15, information mainly used only by the driver, such as meter information necessary for driving, is displayed. Furthermore, drivers rarely make large movements in their posture while driving. Therefore, the viewing angle of the driver side area may be narrow.

The area on the passenger seat side of the display surface 15 is basically required to have a wide viewing angle. However, when entertainment video content such as a TV or DVD is displayed in the passenger seat side area, it is not desirable for the driver to view this video content while driving. Therefore, in such a case, it is necessary to switch the viewing angle of the passenger seat side area to a narrow viewing angle so that the driver cannot see the image of the passenger seat side area.

The central area of the display surface 15 is used as a center display and often displays navigation images. Navigation images are often used not only by the driver but also by the passenger. Therefore, it is desirable that the central portion of the display surface 15 has a wide viewing angle.

Considering that the center display is always required to have a wide viewing angle, the louver 25L of the LCF 25 may have a structure as shown in FIG. 15. In FIG. 15, areas of the LCF 25 corresponding to the driver's seat side area, the center area, and the passenger seat side area of the display surface 15 are defined as

areas

25a, 25b, and 25c, respectively. By making the height of the louvers 25L in the region 25b lower than the height of the louvers 25L in the

regions

25a and 25c, the viewing angle in the central region of the display surface 15 is widened in the front stage of the PDLC film 26.

Alternatively, the viewing angle in the central region of the display surface 15 may be widened in the front stage of the PDLC film 26 by making the arrangement interval of the louvers 25L in the region 25b larger than the arrangement interval of the louvers 25L in the

regions

25a and 25c.

<A-4. Light source>
The liquid crystal display device 201 of this embodiment uses a direct type backlight 21 as the light source 11.

An edge-type backlight that receives light from LEDs placed on the side surface of the light guide plate 22 is often used in medium-sized or small-sized liquid crystal display devices, but is not very suitable for large-sized liquid crystal display devices. As the display surface 15 becomes larger, the number of LEDs that can be arranged on the side surface of the light guide plate 22 increases, but the distance from the LEDs to the center of the display surface 15 increases, making it difficult to spread light evenly over the entire display surface 15. It is. Furthermore, the number of LEDs that can be arranged increases as the size of the display surface 15 increases to the first power, while the area of the display surface 15 increases as the square of the dimension of the display surface, so the larger the display surface 15 becomes, the more brightness decreases.

Since the liquid crystal display device 201 has a large horizontally long display surface 15, it is desirable to use a direct type backlight 21.

The direct backlight 21 is constructed by separately arranging a plurality of LED light sources. Here, the divisional arrangement of the direct backlight 21 may be the same as or different from the divisional arrangement of the ITO electrodes 31 in the PDLC film 26.

The power consumption of the liquid crystal display device 201 can be reduced by using Local Dimming, which individually drives and controls each LED light source that makes up the direct backlight 21. This technique is particularly effective for large screen displays, which tend to consume large amounts of power.

<A-5. Operation>
FIG. 16 is a flowchart showing an example of the operation of the liquid crystal display device 201. Here, it is assumed that the ITO electrode 31 of the PDLC film 26 is divided into three parts as shown in FIGS. 7 and 8.

First, the transmission diffusion control unit 14 determines whether the vehicle is traveling (step S101).

If the vehicle is not running in step S101, the process of the transmission diffusion control unit 14 moves to step S104.

If the vehicle is running in step S101, the transmission diffusion control unit 14 determines whether the content displayed on the passenger seat side area of the display surface 15 is entertainment content such as a TV or DVD (step S102). ).

If the content displayed in the passenger seat side area of the display surface 15 is entertainment in step S102, the process of the transmission diffusion control unit 14 moves to step S103. In step S103, the transmission diffusion control unit 14 applies a voltage to the ITO electrode 313 corresponding to the passenger seat side area of the display surface 15, and sets the area of the PDLC film 26 sandwiched between the ITO electrode 313 and the ITO electrode 32 to the transmission mode. do. Note that here, the transmission diffusion control unit 14 does not apply voltage to the

ITO electrodes

311 and 312 corresponding to the driver's seat side portion and the central portion of the display surface 15, but instead The area of the PDLC film 26 that has been removed is set to the diffusion mode. As a result, the viewing angle is reduced only in the area on the passenger seat side of the display surface 15.

In step S102, if the content displayed on the passenger seat side area of the display surface 15 is not entertainment-related, the process of the transmission diffusion control unit 14 moves to step S104.

In step S104, the transmission diffusion control unit 14 does not apply voltage to the ITO electrode 313 corresponding to the passenger seat side area of the display surface 15, and operates the area of the PDLC film 26 sandwiched between the ITO electrode 313 and the ITO electrode 32 in the diffusion mode. shall be. Note that here, the transmission diffusion control unit 14 does not apply voltage to the

ITO electrodes

311 and 312 corresponding to the driver's seat side portion and the central portion of the display surface 15, and the

ITO electrodes

311 and 312 that are sandwiched between the

ITO electrodes

311 and 312 and the ITO electrode 32 The area of the PDLC film 26 is placed in a diffusion mode. As a result, the passenger seat side region of the display surface 15 has a large viewing angle, similar to the driver seat side portion and the central portion.

<A-6. Modified example>
Although the LCF 25 is shown as an example of the viewing angle limiting structure 12 in <A-3>, the viewing angle limiting structure 12 may be realized by the following configuration.

By adjusting the shape of the prism lens formed on the lens sheet 24, the direction or size of the viewing angle can be changed. That is, the viewing angle limiting structure 12 may be realized by a prism lens in the lens sheet 24.

Furthermore, the viewing angle limiting structure 12 may be realized by the liquid crystal panel 28. For example, a voltage-controllable ITO electrode may be provided on the color filter (CF) glass substrate side of the liquid crystal panel 28, and the viewing angle may be controlled by controlling the light distribution of the liquid crystal using this ITO electrode. Further, in addition to the normal liquid crystal panel 28, a narrow viewing angle liquid crystal panel may be added, and the viewing angle may be controlled using two liquid crystal panels.

Furthermore, by changing the shape or height of the separator that separates each LED of the direct type backlight 21, the direction or size of the viewing angle can be changed. That is, the separator of the direct backlight 21 may realize the viewing angle limiting structure 12.

When the in-vehicle display device 101 is a rear projection display, the viewing angle limiting structure 12 is realized by adjusting the shapes of the Fresnel lens and lenticular lens that constitute the projection screen.

When the in-vehicle display device 101 is an organic EL display (OLED), the viewing angle limiting structure 12 is realized by the LCF 25 attached to the organic EL display.

<A-7. Effect＞
The in-vehicle display device 101 according to the first embodiment includes a display surface 15, a light source 11, a viewing angle limiting structure 12, a viewing angle expanding structure 13, and a transmission diffusion control section 14. The display surface 15 is continuously arranged from the front of the driver's seat of the vehicle to the front of the passenger seat of the vehicle. The viewing angle limiting structure 12 is provided between the light source 11 and the display surface 15 so as to be stacked on the display surface 15, and narrows the viewing angle of the light incident from the light source 11 and outputs the light. The viewing angle expansion structure 13 is provided between the viewing angle restriction structure 12 and the display surface 15 in a laminated manner with the viewing angle restriction structure 12 and the display surface 15, and is provided in a plurality of divided regions in a plane direction parallel to the display surface 15. The light incident from the viewing angle limiting structure 12 is either transmitted or diffused. The transmission/diffusion control unit 14 performs transmission/diffusion control for each of the plurality of segmented areas to control whether the viewing angle expanding structure 13 transmits or diffuses the light incident from the viewing angle limiting structure.

With the above configuration, according to the in-vehicle display device 101, the viewing angle can be narrowed only in some areas of the display surface 15 by selectively diffusing light in some divided areas of the viewing angle limiting structure. I can do it. Therefore, the viewing angle can be optimally adjusted for each portion of the display surface 15, such as the driver's seat side portion, the center portion, and the passenger seat side portion.

Further, the transmission/diffusion control unit 14 may perform transmission/diffusion control for each segmented area in accordance with the content displayed in the area of the display surface 15 corresponding to each segmented area of the viewing angle expansion structure 13. As a result, for example, depending on the content displayed on the passenger side area of the display surface 15, it is possible to reduce the viewing angle of the passenger side area and make the image on the passenger side invisible from the driver's seat side. be.

Furthermore, the transmission/diffusion control section 14 may perform transmission/diffusion control for each segmented area of the viewing angle expansion structure 13 depending on whether the vehicle is running or not. As a result, for example, while the vehicle is running, it is possible to reduce the viewing angle of the passenger seat side area of the display screen 15, making it possible to make the image on the passenger seat side invisible from the driver's seat side.

Further, in the liquid crystal display device 201, the viewing angle limiting structure 12 includes the LCF 25, and the viewing angle expanding structure (13) includes a PDLC film 26, an ITO electrode 31 that is a first transparent electrode that sandwiches the PDLC film 26 from both sides, and an ITO electrode 31 that is a first transparent electrode that sandwiches the PDLC film 26 from both sides. The ITO electrode 31 is divided into a plurality of divided

transparent electrodes

311, 312, 313 in a plane direction parallel to the display surface 15, and the transmission diffusion control unit 14 The voltage applied between each of the

ITO electrodes

311, 312, 313 and the ITO electrode 32 may be controlled. According to such a configuration, since only the transparent ITO electrodes 31 are arranged in a divided manner, it is possible to prevent visible seams from appearing on the display surface 15. Therefore, image quality is improved.

<B. Embodiment 2>
<B-1. Configuration>
FIG. 17 is a diagram showing the configuration of an in-vehicle display device 102 according to the second embodiment. The in-vehicle display device 102 is a display device mounted on a vehicle, and includes a brightness control unit 16 that adjusts the brightness of the light source 11 in addition to the configuration of the in-vehicle display device 101 according to the first embodiment.

When the viewing angle of a part of the display surface 15 is expanded by the viewing angle expansion structure 13, the brightness may change rapidly between the area where the viewing angle has been expanded and other areas, and uneven brightness may be visible. be. Therefore, the brightness control unit 16 adjusts the brightness of each area of the display surface 15 to suppress uneven brightness.

When a direct type backlight is used as the light source 11, the brightness control unit 16 controls the viewing angle limiting structure 12 from one end of the boundary between the area where the viewing angle is expanded by the viewing angle expanding structure 13 and another area to the other end. The brightness of the light that enters the viewing angle limiting structure 12 from the light source 11 is controlled so that the brightness of the light that enters the viewing angle expanding structure 13 from the light source 11 changes continuously. This reduces uneven brightness.

When the PDLC film 26 is used as the viewing angle expansion structure 13, when the PDLC film 26 performs two-choice control of transmitting and diffusing light by turning on or off the voltage at the

ITO electrodes

31 and 32, the viewing angle is expanded. The luminance change becomes large at the boundary between the area and other areas. Therefore, the brightness adjustment by the brightness control section 16 is highly effective.

<B-2. Effect>
In addition to the configuration of the vehicle-mounted display device 101, the vehicle-mounted display device 102 according to the second embodiment includes a brightness control unit 16 that controls the brightness of the light that enters the viewing angle limiting structure 12 from the light source 11. When the degree of diffusion, which indicates the degree of light diffusion by the viewing angle expanding structure 13, is different between two adjacent divided areas, the brightness control unit 16 controls the viewing angle limiting structure from one end of the boundary between the two divided areas to the other end. The brightness of the light that enters the viewing angle limiting structure 12 from the light source 11 is controlled so that the brightness of the light that enters the viewing angle limiting structure 12 changes continuously. This makes it possible to smooth the brightness change at the boundary of the area where the viewing angle of the display surface 15 changes, and to reduce brightness unevenness.

<C. Embodiment 3>
<C-1. Configuration>
The configuration of the in-vehicle display device according to the third embodiment is similar to the configuration of the in-vehicle display device 101 according to the first embodiment, and is as shown in FIG. In the third embodiment, brightness unevenness on the display surface 15 is suppressed by transmission diffusion control by the transmission diffusion control section 14.

Originally, brightness unevenness that occurs at the boundary of a region where the viewing angle changes is caused by a sudden change in the viewing angle near the boundary. When the brightness of the light source 11 is constant, the wider the viewing angle, the lower the visible brightness, and the narrower the viewing angle, the higher the visible brightness. When diffusing the light incident from the viewing angle limiting structure 12 in a certain segmented area of the viewing angle expansion structure 13, the transmission diffusion control unit 14 diffuses the light incident from the viewing angle limiting structure 12 in a certain segmented area of the viewing angle expansion structure 13, in three or more segments that include that segmented area and continue in the same direction. Transmission diffusion control is performed so that the degree of diffusion, which represents the degree of diffusion, changes continuously in the region.

When the PDLC film 26 is used as the viewing angle expansion structure 13 like the liquid crystal display device 201, the transmission diffusion control section 14 not only switches the voltage between the

ITO electrodes

31 and 32 on and off, but also controls the voltage between the

ITO electrodes

31 and 32. Apply an intermediate voltage to . As a result, it is possible to create a transmission mode in which the degree of diffusion is 0, a diffusion mode in which the degree of diffusion is maximum, and an intermediate mode having a degree of diffusion between the transmission mode and the diffusion mode in the PDLC film 26. At this time, on the display surface 15, a viewing angle intermediate between the viewing angle obtained in the transmission mode and the viewing angle obtained in the diffusion mode is obtained.

Utilizing this, the transmission diffusion control unit 14 gradually changes the ITO voltage near the region of the display surface 15 where the viewing angle is switched. As a result, the viewing angle gradually changes on the display surface 15, and brightness unevenness is reduced.

<C-2. Effect＞
In the in-vehicle display device according to the third embodiment, the viewing angle expanding structure 13 can diffuse the light incident from the viewing angle limiting structure 12 at a plurality of different degrees of diffusion. Further, the transmission diffusion control unit 14 performs transmission diffusion control on three or more divided regions of the viewing angle expansion structure 13 that are continuous in the same direction so that the degree of diffusion changes continuously. Therefore, since the viewing angle is gradually changed on the display surface 15, brightness unevenness due to changes in the viewing angle is reduced.

Note that this embodiment may be combined with Embodiment 2. That is, the transmission diffusion control unit 14 continuously changes the degree of diffusion for three or more continuous divided areas in the same direction, and the brightness control unit 16 changes the degree of diffusion between adjacent divided areas in the viewing angle expansion structure 13. The brightness of the light source 11 may be controlled so that the brightness of the light incident from the viewing angle limiting structure 12 changes continuously from one end of the boundary to the other end.

<D. Embodiment 4>
<D-1. Configuration>
The configuration of the in-vehicle display device according to the fourth embodiment is similar to the configuration of the in-vehicle display device 102 according to the second embodiment, and is as shown in FIG. In Embodiment 4, the brightness control unit 16 controls the brightness of light incident on the entire divided area with a high degree of diffusivity when two adjacent divided areas of the viewing angle expansion structure 13 have different degrees of diffusivity due to transmission diffusion control. The brightness of the light that enters the viewing angle limiting structure 12 from the light source 11 is controlled so that the brightness is higher than the brightness of the light that enters the entire segmented area with low diffusivity.

As described above, when the light source 11 has a constant brightness, the wider the viewing angle, the lower the visible brightness, and the narrower the viewing angle, the higher the visible brightness. This phenomenon occurs not only at the boundary between the area where the viewing angle is widened and other areas on the display surface 15, but also throughout the area where the viewing angle is widened or the entire other area. The area where the viewing angle is widened on the display surface 15 appears brighter than other areas. In other words, the area on the display surface 15 where the viewing angle is not widened appears darker than the area where the viewing angle is widened. It is unnatural for the entire area of the display surface 15 to appear bright or dark. Areas that appear too bright or too dark pose problems in terms of visibility.

Therefore, the brightness control unit 16 compensates for the reduction in brightness due to the expansion of the viewing angle in the viewing angle expansion structure 13 by increasing the brightness of the light emitted from the light source 11.

<D-2. Effect＞
In the in-vehicle display device according to the fourth embodiment, when the degree of light diffusion due to the transmission diffusion control is different in two adjacent divided areas of the viewing angle expansion structure 13, the brightness control unit 16 controls the degree of diffusion of the two divided areas. The brightness of the light that enters the viewing angle limiting structure 12 from the light source 11 is controlled so that the brightness of the light that enters the entire divided area with a high degree of diffusion is higher than the brightness of the light that enters the entire divided area that has a low degree of diffusivity. . This achieves balanced brightness across the entire display surface 15.

<E. Hardware configuration>
The transmission diffusion control section 14 in the vehicle-mounted

display devices

101 and 102 and the brightness control section 16 in the vehicle-mounted display device 102 described above are realized by a processing circuit 81 shown in FIG. That is, the processing circuit 81 includes the transmission diffusion control section 14 and the brightness control section 16. Dedicated hardware may be applied to the processing circuit 81, or a processor that executes a program stored in memory may be applied. The processor is, for example, a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), or the like.

When the processing circuit 81 is dedicated hardware, the processing circuit 81 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable Circuit). Gate Array), or a combination of these. The functions of each section, such as the section .

When the processing circuit 81 is a processor, the functions of the transmission diffusion control section 14 and the brightness control section 16 are realized by a combination of software, etc. (software, firmware, or software and firmware). Software etc. are written as programs and stored in memory. As shown in FIG. 19, a processor 82 applied to a processing circuit 81 realizes the functions of each part by reading and executing a program stored in a memory 83. That is, the in-

vehicle display devices

101 and 102 have a memory 83 for storing a program that, when executed by the processing circuit 81, results in the functions of the transmission diffusion control section 14 and the brightness control section 16 being executed. Equipped with. In other words, this program can be said to cause the computer to execute the procedures or methods of the transmission diffusion control section 14 and the brightness control section 16. Here, the memory 83 is a non-volatile or Volatile semiconductor memory, HDD (Hard Disk Drive), magnetic disk, flexible disk, optical disk, compact disk, mini disk, DVD (Digital Versatile Disk) and its drive device, etc., or any storage media that will be used in the future. It's okay.

Note that it is possible to freely combine each embodiment, or to modify or omit each embodiment as appropriate. The above description is in all aspects exemplary. It is understood that countless variations not illustrated may be envisioned.

11 light source, 12 viewing angle limiting structure, 13 viewing angle expanding structure, 14 transmission diffusion control unit, 15 display surface, 16 brightness control unit, 21 direct backlight, 22 light guide plate, 23 diffusion sheet, 24 lens sheet, 25 LCF , 25L louver, 26 PDLC film, 27 polymer matrix, 28 liquid crystal panel, 29 liquid crystal capsule, 30 liquid crystal, 31, 32, 311, 312, 313 ITO electrode, 33, 34 PET film, 81 processing circuit, 82 processor, 83 Memory, 101, 102 In-vehicle display device, 201 Liquid crystal display device.

Claims

An in-vehicle display device installed in a vehicle,
a display surface that is continuously arranged from the front of the driver's seat of the vehicle to the front of the passenger seat of the vehicle;
a light source and
a viewing angle limiting structure provided between the light source and the display surface and stacked on the display surface, narrowing the viewing angle of the light incident from the light source and emitting the light;
The viewing angle limiting structure is provided between the viewing angle limiting structure and the display surface in a laminated manner with the viewing angle limiting structure and the display surface, and is divided into a plurality of divided regions in a plane direction parallel to the display surface, and the viewing angle limiting structure a viewing angle expansion structure that either transmits or diffuses light incident from the structure;
a transmission diffusion control unit that performs transmission diffusion control to control whether the viewing angle expansion structure transmits or diffuses the light incident from the viewing angle restriction structure for each of the plurality of divided regions; prepare,
In-vehicle display device.
The transmission diffusion control unit performs the transmission diffusion control for each of the divided areas according to the content displayed in the area of the display surface corresponding to each of the divided areas.
The in-vehicle display device according to claim 1.
The transmission diffusion control unit performs the transmission diffusion control for each of the divided regions depending on whether the vehicle is traveling or not.
The in-vehicle display device according to claim 2.
the viewing angle limiting structure includes a light control film;
The viewing angle expansion structure includes a PDLC film, and a first transparent electrode and a second transparent electrode that sandwich the PDLC film from both sides,
The first transparent electrode is divided into a plurality of divided transparent electrodes in the surface direction,
The transmission diffusion control unit controls a voltage applied between each of the plurality of divided transparent electrodes and the first transparent electrode.
The in-vehicle display device according to claim 1.
The display surface is located between a first display area located in front of the driver's seat, a second display area located in front of the front passenger seat, and between the first display area and the second display area. a third display area,
A louver provided in an area of the light control film corresponding to the third display area is lower than a louver provided in an area of the light control film corresponding to the first display area and the second display area, or the placement interval is large,
The in-vehicle display device according to claim 4.
If the degree of diffusion, which represents the degree of light diffusion by the viewing angle expanding structure, is different in two adjacent divided areas, the light incident from the viewing angle limiting structure from one end of the boundary between the two divided areas to the other end is different. further comprising a brightness control unit that controls the brightness of light that enters the viewing angle limiting structure from the light source so that the brightness of the light that enters the viewing angle limiting structure changes continuously;
The in-vehicle display device according to claim 1.
The viewing angle expanding structure is capable of diffusing the light incident from the viewing angle limiting structure at a plurality of different degrees of diffusion,
The transmission diffusion control unit performs the transmission diffusion control for the three or more divided regions that are continuous in the same direction so that the degree of diffusion changes continuously.
The in-vehicle display device according to claim 1.
When the degree of diffusion representing the degree of diffusion of light due to the transmission diffusion control is different in the two adjacent divided regions, the brightness of the light that enters the whole of the divided region with the higher degree of diffusion among the two divided regions is , further comprising a brightness control unit that controls the brightness of the light that enters the viewing angle limiting structure from the light source so that the brightness is higher than the brightness of the light that enters the entire segmented area where the degree of diffusion is low;
The in-vehicle display device according to claim 1.