JP7433716B2 - heads up display device - Google Patents

Description

The present invention relates to a head-up display device.

Head-up display devices are known that reflect light representing an image displayed on a display device on the windshield (so-called windshield) of a vehicle, thereby displaying the image on the windshield as a virtual image of the space in front of the vehicle. . Thereby, the driver can visually recognize an image indicating information related to the driving of the vehicle (speed information, car navigation information, etc.) superimposed on the scenery in front of the windshield.

The display device includes a liquid crystal panel and a backlight device, and the backlight device irradiates the liquid crystal panel with light to display an image. A backlight device includes a plurality of light sources (for example, light emitting diodes) arranged in a matrix in order to uniformly irradiate the entire surface of a liquid crystal panel with light. For example, Patent Document 1 discloses a backlight device (illumination device) including a surface light source in which ten light emitting diodes (LEDs) are arranged in two rows and five columns.

On the other hand, due to the characteristics of liquid crystal, liquid crystal panels leak light from a backlight device even when displaying black, making it difficult to display complete black. Therefore, at night, the difference in contrast between the black image displayed in the windshield display area by the head-up display device and the black surrounding the display area (nighttime scenery) creates a postcard effect in which the display area stands out. Occur. In this case, the outline of the display area enters the driver's field of vision, making him feel bothered.

Japanese Patent Application Publication No. 2007-87792

As a measure against the postcard effect, head-up display devices using OLEDs and MEMS lasers have been developed. In the case of these methods, the postcard effect is less likely to appear due to the difference in method from the case of using a liquid crystal panel. However, all of these methods are higher in cost than when using a liquid crystal panel.

The present invention was conceived under the above circumstances, and an object of the present invention is to provide a head-up display device that has a simple configuration and can reduce the postcard effect.

In order to solve the above problems, the present invention takes the following technical measures.

A head-up display device provided by the present invention includes a display device, and reflects light representing an image displayed on the display device on a transmissive reflective section, thereby converting the image into a virtual image of a space in front of a vehicle. A head-up display device that displays information on a transmissive reflective section, the display device including a liquid crystal panel and a backlight device that irradiates light to the liquid crystal panel, the backlight device including a plurality of light sources and the and an irradiation surface that irradiates light to a liquid crystal panel, and the plurality of light sources are arranged such that the brightness at any one of the four corners of the irradiation surface is lower than the brightness at the center.

In a preferred embodiment of the present invention, the irradiation surface includes a first edge and a second edge perpendicular to the first edge, and the plurality of light sources are located most at the first edge. a first light source disposed close to the first edge; and a second light source closest to the first edge among the light sources disposed closest to the second edge, the second light source comprising: The light source is disposed on the opposite side of the first edge from the first light source in a direction parallel to the second edge.

According to the present invention, in the backlight device, a plurality of light sources are arranged such that the brightness at any of the four corners of the irradiation surface is lower than the brightness at the center. Therefore, the light emitted from the irradiation surface is darker at any of the four corners than at the center. Therefore, the black part at any of the four corners of the image displayed in the display area of the transmissive reflection section is darker than the black part at the center, and the contrast difference with the black around the display area is small. This reduces the postcard effect. Further, according to the present invention, since the arrangement of the plurality of light sources is only devised, it can be realized with a simple configuration, and the manufacturing cost can be suppressed compared to the case where OLED or MEMS laser is used.

Other features and advantages of the invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing an outline of a head-up display device according to a first embodiment. FIG. 2 is a block diagram showing the functional configuration of the head-up display device shown in FIG. 1. FIG. FIG. 3 is a schematic plan view showing the arrangement of light emitting diodes D in the backlight device according to the first embodiment. 4 is a block diagram showing the internal configuration of the backlight device shown in FIG. 3. FIG. It is a figure which shows an example of the image displayed on a windshield. FIG. 7 is a schematic plan view showing a modification of the backlight device according to the first embodiment. FIG. 7 is a schematic plan view showing a modification of the backlight device according to the first embodiment. FIG. 7 is a schematic plan view showing a modification of the backlight device according to the first embodiment. FIG. 7 is a schematic plan view showing a backlight device of a head-up display device according to a second embodiment. It is a figure which shows an example of the image displayed on a windshield.

Embodiments of the present invention will be specifically described below with reference to the drawings.

1 to 5 are diagrams for explaining a head-up display device A1 according to the first embodiment. FIG. 1 is a schematic diagram showing an outline of a head-up display device A1. FIG. 2 is a block diagram showing the functional configuration of the head-up display device A1. FIG. 3 is a plan view showing the backlight device. FIG. 4 is a block diagram showing the internal configuration of the backlight device shown in FIG. 3. FIG. 5 is a diagram showing an example of an image displayed on the windshield, which is taken when the vehicle is driving at night.

As shown in FIGS. 1 and 2, the head-up display device A1 includes a display device 1, a first mirror 51, a second mirror 52, and a control device 4. The head-up display device A1 is arranged at a position in the vehicle width direction corresponding to the driver's seat, using the interior space of the instrument panel of the vehicle B. As shown in FIG. 1, the head-up display device A1 reflects the light representing the image displayed on the display device 1 on the windshield 7 (so-called windshield), thereby displaying the image in the space in front of the vehicle B. It is displayed on the windshield 7 as a virtual image V. The windshield 7 is a transparent plate made of glass, for example, and functions as a transmissive/reflective portion that transmits or reflects light depending on the angle of the incident light. The images displayed on the display device 1 include images showing various types of information (hereinafter referred to as "driving information") related to the traveling of the vehicle B, such as speed information and navigation information. The image displayed on the display device 1 is generated by the image generation section 60. An image containing driving information is displayed as a virtual image V superimposed on the scenery in front of the windshield 7, so the driver can direct his/her line of sight to the meter unit located on the instrument panel, the car navigation monitor, etc. It is possible to recognize driving information without moving the vehicle.

For example, as shown in FIG. 5, in the display area 71 of the windshield 7, an image showing the time, vehicle speed, fuel gauge, and road information is displayed superimposed on the scenery ahead. Note that the driving information displayed on the windshield 7 is not limited. In FIG. 5, the display area 71 is shown by a two-dot chain line for convenience in order to show the range of the display area 71, but in reality, the display area 71 is not displayed on the windshield 7. In this embodiment, the display area 71 is arranged below the windshield 7.

The display device 1 displays an image indicating travel information and emits light representing the image. In this embodiment, as shown in FIG. 1, the display device 1 is arranged in the housing of the head-up display device A1, with the display surface 1a on which an image is displayed facing slightly rearward and diagonally upward. Details of the internal configuration of the display device 1 will be described later.

The first mirror 51 is a mirror for reflecting light from the display device 1 toward the second mirror 52. In this embodiment, the first mirror 51 is arranged on the housing of the head-up display device A1 so as to reflect the reflected light from the display device 1 forward when viewed from the side. In this embodiment, the first mirror 51 is a plane mirror.

The second mirror 52 is a mirror for reflecting the reflected light from the first mirror 51 toward the windshield 7. In the present embodiment, the second mirror 52 is configured to reflect the reflected light from the first mirror 51 diagonally upward and backward toward a lower region of the windshield 7 that extends diagonally upward and rearward when viewed from the side. It is arranged in the housing of the head-up display device A1. The windshield 7 reflects the light reflected from the second mirror 52 toward the driver's viewpoint E. The windshield 7 is normally curved in a concave shape toward the indoor side, and the second mirror 52 is a concave mirror. Thereby, the image displayed on the display device 1 is displayed as an enlarged virtual image V at the end of the optical path L from the windshield 7 to the viewpoint E. The surface shape of the second mirror 52 is appropriately designed depending on the curvature of the windshield 7 and the magnification ratio of the image.

Next, details of the internal configuration of the display device 1 will be described.

The display device 1 includes a liquid crystal panel 2 and a backlight device 3, as shown in FIG. The display device 1 is a transmissive display device in which a backlight device 3 irradiates a liquid crystal panel 2 with light and displays an image using the light that passes through the liquid crystal panel 2.

The liquid crystal panel 2 is similar to that used in general liquid crystal displays, and its type and format are not limited. In the liquid crystal panel 2, driving of each pixel (switching between passing and blocking light) is controlled by a control device 4.

The backlight device 3 includes a plurality of light emitting diodes D, and is arranged on the back side of the liquid crystal panel 2 (on the opposite side to the side where the first mirror 51 is arranged) (see FIG. 1). The backlight device 3 includes an irradiation surface 3a that irradiates light emitted by a plurality of light emitting diodes D toward the liquid crystal panel 2. The shape of the irradiation surface 3a is a rectangle that matches the shape of the liquid crystal panel 2. Note that the backlight device 3 includes a lens that condenses and diffuses the light emitted from each light emitting diode D and a diffusion film, but a detailed description thereof will be omitted. The display device 1 forms an image on the display surface 1a using light that passes through the liquid crystal panel 2 out of the light emitted from the irradiation surface 3a by the backlight device 3.

In this embodiment, the backlight device 3 includes a series light source group 30 and a drive circuit 31, as shown in FIGS. 3 and 4. As shown in FIG. 4, the series light source group 30 includes seven light emitting diodes D connected in series. Note that the order in which the seven light emitting diodes D are connected is not limited. Furthermore, the method of connecting the seven light emitting diodes D is not limited either. For example, all seven light emitting diodes D may be connected in parallel, or three light emitting diodes D connected in series and four light emitting diodes D connected in series may be connected in parallel. Each light emitting diode D is a light emitting diode that emits white light when energized. As shown in FIG. 3, the seven light emitting diodes D are arranged with their light emitting surfaces Da facing toward the liquid crystal panel 2 (the front side of the paper in FIG. 3). In addition, in FIG. 3, in order to show the arrangement of each light emitting diode D, a lens and a film are shown. The outer surface of the film corresponds to the irradiation surface 3a that irradiates light.

The seven light emitting diodes D include light emitting diodes D1 to D7. The light emitting diodes D1 to D4 are arranged at regular intervals in the x direction, which is the longitudinal direction of the irradiation surface 3a and the width direction of the vehicle B. The light emitting diodes D5 to D7 are arranged at regular intervals in the x direction, and are arranged on one side (upper side in FIG. 3) of the light emitting diodes D1 to D4 in the y direction, which is a direction orthogonal to the x direction. It is located. Light emitting diode D5 is arranged between light emitting diode D1 and light emitting diode D2 in the x direction. Light emitting diode D6 is arranged between light emitting diode D2 and light emitting diode D3 in the x direction. Light emitting diode D7 is arranged between light emitting diode D3 and light emitting diode D4 in the x direction. The light emitting diodes D1 to D4 irradiate light to a region of the liquid crystal panel 2 corresponding to a lower region of the display region 71 of the windshield 7. The light emitting diodes D5 to D7 irradiate light to a region of the liquid crystal panel 2 corresponding to an upper region of the display region 71 of the windshield 7.

The irradiation surface 3a has an edge 3b on one end side in the x direction (left end side in FIG. 3), an edge 3c on one end side in the y direction (upper end side in FIG. 3), and an edge 3c on the other end side in the x direction ( It has an edge 3d on the right end side (in FIG. 3), and an edge 3e on the other end side in the y direction (lower end side in FIG. 3). The light emitting diode D1 is arranged at the position closest to the edge 3b. The light emitting diode D4 is arranged at the position closest to the edge 3d. The light emitting diodes D5 to D7 are arranged closest to the edge 3c. Among the light emitting diodes D5 to D7, the light emitting diode D5 is placed closest to the edge 3b, and is placed closer to the edge 3d than the light emitting diode D1 in the x direction. The light emitting diode D7 is disposed closest to the edge 3d among the light emitting diodes D5 to D7, and is disposed closer to the edge 3b than the light emitting diode D4 in the x direction.

The drive circuit 31 is a drive circuit that drives each light emitting diode D of the series light source group 30. The drive circuit 31 is connected to the anode side terminal of the series light source group 30. The cathode side terminal of the series light source group 30 is grounded. Note that the position of the drive circuit 31 in the backlight device 3 is not limited, and may be any position that does not interfere with the light emitted by each light emitting diode D.

The control device 4 controls the liquid crystal panel 2 and the backlight device 3, and is realized by, for example, a microcomputer equipped with a CPU and a memory.

The control device 4 controls driving of each pixel of the liquid crystal panel 2 based on display image information input from the image generation section 60. The image generation unit 60 generates an image to be displayed on the display device 1 based on driving information input from various sensors, various ECUs (Electronic Control Units), and the like. Examples of travel information input to the image generation unit 60 to generate the image include the vehicle B's vehicle speed, engine speed, remaining fuel level, shift position, navigation information, cumulative mileage, time, and outside temperature. , direction information, parking brake information, information indicating the lighting and status of lights, seatbelt attachment/detaching information, cooling water temperature, failure diagnosis information, security information, etc. Note that the driving information used to generate the image is not limited. The image generation unit 60 outputs image data of the generated image to the control device 4 as display image information. Note that the head-up display device A1 may include an image generation section 60.

Further, the control device 4 controls the drive circuit 31 of the backlight device 3 based on the illuminance input from the illuminance sensor 62. The illuminance sensor 62 is, for example, a sensor that is placed in front of the vehicle B and detects the surrounding illuminance. The illuminance detected by the illuminance sensor 62 is used, for example, to determine whether to turn on or turn off the light. The illuminance sensor 62 outputs the detected illuminance to the control device 4.

The control device 4 sets the brightness of the series light source group 30 based on the illuminance input from the illuminance sensor 62. The higher the illuminance input from the illuminance sensor 62 and the brighter the surroundings of the vehicle B, the brighter the background of the display area 71 of the windshield 7 becomes. Therefore, the control device 4 sets the brightness of the series light source group 30 to a large value in order to increase the brightness of the image displayed in the display area 71 and improve visibility. Note that the value to be set for the brightness with respect to the illuminance input from the illuminance sensor 62 is determined through experiments so as to be as optimal as possible.

The control device 4 adjusts the brightness of each light emitting diode D by so-called PWM dimming. In PWM dimming, the lighting period in which a driving current is applied to the light emitting diode to turn it on and the extinguishing period in which the driving current is cut off and the light is turned off are alternately switched at a fixed short cycle, and the proportion of the lighting period in one cycle ( This technology changes the brightness of a light emitting diode by changing the duty ratio. By shortening the switching cycle (increasing the frequency), the human eye can no longer perceive the flicker caused by turning on and off. When the duty ratio becomes higher, the lighting period becomes longer, so the brightness of the light emitting diode increases, and when the duty ratio becomes lower, the lighting period becomes shorter, so the brightness of the light emitting diode becomes lower. When the duty ratio is "0", the light emitting diode is turned off.

The control device 4 outputs a pulse signal according to the set brightness to the drive circuit 31. The drive circuit 31 adjusts the brightness of each light emitting diode D to a set brightness by switching the drive current flowing through the series light source group 30 according to a pulse signal input from the control device 4. Since the light emitting diodes D of the series light source group 30 are connected in series, the same drive current flows and they emit light with the same brightness. Note that the control device 4 may be included in the display device 1.

Next, the functions and effects of the head-up display device A1 according to the present embodiment will be explained.

According to this embodiment, each light emitting diode D of the series light source group 30 emits light with the same brightness, but since the light emitting diodes D1 to D7 are arranged unevenly (not in a matrix shape) as shown in FIG. The entire surface of the surface 3a is not irradiated with light of the same brightness. Specifically, among the four corners of the irradiation surface 3a, the corner portion where the edge 3b and the edge 3c intersect, and the corner portion where the edge 3d and the edge 3c intersect are separated from any light emitting diode D. Therefore, light with lower brightness than other parts, for example, the central part, is irradiated. Therefore, in the display area 71 of the windshield 7 shown in FIG. The contrast difference with the surrounding black becomes smaller. This makes the upper and both corner portions of the outline of the display area 71 less noticeable. Generally, when human eyes recognize contours, they often recognize corners. Therefore, if the outline of the corner portion is not noticeable, the overall outline will not be very noticeable. This reduces the postcard effect and reduces the driver's annoyance, leading to improved driving safety and improved visual quality. Further, according to the present embodiment, since the arrangement of the light emitting diodes D is simply devised, it can be realized with a simple configuration, and the manufacturing cost can be suppressed compared to the case of using an OLED or a MEMS laser.

Note that in this embodiment, the brightness of the areas 711 and 712 at both upper corners of the display area 71 is low, so when an image is displayed in these areas, visibility becomes poor. However, in the head-up display device A1, the arrangement of each part of the displayed image is fixed, and it can be set so that no image is displayed in the areas 711 and 712. Furthermore, in the present embodiment, the black portions of the corners of both lower sides of the display area 71 are approximately the same as the black portions of the central portion of the display area 71, so that the lower outline of the display area 71 is can create a postcard effect. However, at night when the postcard effect occurs, the road that is the background of the lower area of the display area 71 is illuminated by headlights and becomes bright, so the postcard effect does not occur much.

Moreover, according to this embodiment, the number of light emitting diodes D arranged can be reduced compared to the case where a plurality of light emitting diodes D are arranged in a matrix. For example, in the case of the backlight device 3 shown in FIG. 3, eight light emitting diodes D are required when the light emitting diodes D are arranged in a matrix, but in this embodiment, it is configured with seven light emitting diodes D. . This makes it possible to reduce the number of parts. Therefore, manufacturing costs can be suppressed. Furthermore, by reducing the number of light emitting diodes D used, the total amount of heat emitted from the light emitting diodes D is reduced. Thereby, the heat sink can be made smaller, so the head-up display device A1 can be made smaller and lighter.

In addition, although the head-up display apparatus A1 demonstrated the case where an image is displayed on the windshield 7 in this embodiment, it is not restricted to this. The head-up display device A1 may display an image on a combiner, which is a transparent plate-shaped component placed between the windshield 7 and the driver. In this case, the "combiner" corresponds to the "transmission/reflection section" of the present invention.

In the present embodiment, a case has been described in which the head-up display device A1 reflects the image displayed on the display device 1 on the first mirror 51 and the second mirror 52 and projects it on the windshield 7. The number of mirrors disposed between 1 and the windshield 7 is not limited. For example, the head-up display device A1 may include only one of the first mirror 51 and the second mirror 52, or may further include an additional mirror. Further, the head-up display device A1 may not include the first mirror 51 and the second mirror 52, and may directly project the image displayed on the display device 1 onto the windshield 7. The orientation of the display surface 1a of the display device 1, the orientation of the displayed image, and the arrangement position, shape, and orientation of each mirror are determined so that the image is appropriately displayed in the display area 71 of the windshield 7. Designed accordingly.

In the present embodiment, a case has been described in which the control device 4 adjusts the brightness of each light emitting diode D by PWM dimming, but the invention is not limited to this. For example, the control device 4 may adjust the brightness of each light emitting diode D by causing the drive circuit 31 to change the magnitude of the drive current flowing through each light emitting diode D.

In this embodiment, a light emitting diode D is used as a light source, but the light source is not limited to this. Other light sources may also be used.

The method of arranging the light emitting diodes D in the backlight device 3 is not limited to that shown in FIG. 3 . FIG. 6 is a schematic plan view showing a modified example of the backlight device 3. In the backlight device 3 according to the modification, there are only two light emitting diodes D, a light emitting diode D5 and a light emitting diode D6, arranged on one side in the y direction (upper side in FIG. 6). The light emitting diode D5 is arranged at the same position as the light emitting diode D2 in the x direction. The light emitting diode D6 is arranged at the same position as the light emitting diode D3 in the x direction. In other words, the backlight device 3 according to the present modification is arranged at one end in the y direction and at both ends in the x direction of the plurality of light emitting diodes D arranged in a matrix of 2 rows and 4 columns. The light emitting diode D is not arranged.

The light emitting diode D1 is arranged at the position closest to the edge 3b. The light emitting diode D4 is arranged at the position closest to the edge 3d. The light emitting diodes D5 to D6 are arranged at positions closest to the edge 3c. Among the light emitting diodes D5 to D6, the light emitting diode D5 is placed closest to the edge 3b, and is placed closer to the edge 3d than the light emitting diode D1 in the x direction. Among the light emitting diodes D5 to D6, the light emitting diode D6 is placed closest to the edge 3d, and is placed closer to the edge 3b than the light emitting diode D4 in the x direction.

Also in this modification, among the four corners of the irradiation surface 3a, the corner portion where the edge 3b and the edge 3c intersect, and the corner portion where the edge 3d and the edge 3c intersect, are not exposed to any of the light emitting diodes D. Because they are far apart, light with lower brightness than other parts, for example, the central part, is irradiated. Therefore, also in this modification, the postcard effect is reduced. Moreover, according to this modification, the number of light emitting diodes D arranged can be further reduced. Therefore, manufacturing costs can be further reduced, and further reduction in size and weight is possible.

FIG. 7 is a schematic plan view showing another modification of the backlight device 3. The backlight device 3 according to the modified example of FIG. 7(a) is one in which the area of the irradiation surface 3a is smaller than that of FIGS. 3 and 6. In this modification, two light emitting diodes D are arranged on one side in the y direction (upper side in FIG. 7), and three light emitting diodes D are arranged on the other side in the y direction (lower side in FIG. 7). has been done. The backlight device 3 according to the modified example of FIG. 7(b) is one in which the area of the irradiation surface 3a is smaller than that of the modified example of FIG. 7(a). In this modification, one light emitting diode D is arranged on one side in the y direction (upper side in FIG. 7), and two light emitting diodes D are arranged on the other side in the y direction (lower side in FIG. 7). has been done. These variations also reduce the postcard effect. Furthermore, compared to the case where a plurality of light emitting diodes D are arranged in a matrix, the number of light emitting diodes D arranged can be reduced, so manufacturing costs can be suppressed and the size and weight can be reduced.

FIG. 8 is a schematic plan view showing another modification of the backlight device 3. The backlight device 3 according to the modified example of FIG. 8 is one in which the area of the irradiation surface 3a is larger than that of FIGS. 3 and 6. In this modification, three light emitting diodes D are arranged on one side in the y direction (upper side in FIG. 7), and four light emitting diodes D are arranged on the other side in the y direction (lower side in FIG. 7). Also, four light emitting diodes D are arranged at the center in the y direction. In this modification as well, the postcard effect is reduced. Furthermore, compared to the case where a plurality of light emitting diodes D are arranged in a matrix, the number of light emitting diodes D arranged can be reduced, so manufacturing costs can be suppressed and the size and weight can be reduced.

As shown in FIGS. 7 and 8, the number and arrangement of light emitting diodes D arranged in the backlight device 3 are appropriately designed depending on the area and shape of the irradiation surface 3a. That is, the number of light emitting diodes D arranged in the x direction and the number of light emitting diodes D arranged in the y direction in the backlight device 3 are not limited. Further, as shown in FIG. 6, there is also a degree of freedom in the arrangement of the light emitting diodes D in the backlight device 3. In the backlight device 3, the light emitting diode D closest to the edge 3b among the light emitting diodes D disposed closest to the edge 3c is the light emitting diode D disposed closest to the edge 3b. Therefore, the light emitting diode D closest to the edge 3d among the light emitting diodes D disposed on the edge 3d side in the x direction or closest to the edge 3c is the closest to the edge 3d. It is sufficient that the light emitting diode D is disposed closer to the edge 3b in the x direction than the light emitting diode D disposed at that position.

<Second embodiment>
9 and 10 are diagrams for explaining a head-up display device A2 according to a second embodiment of the present disclosure. FIG. 9 is a schematic plan view showing the backlight device 3 of the head-up display device A2, and corresponds to FIG. 3. FIG. 10 is a diagram showing an example of an image displayed on the windshield 7, and corresponds to FIG. 5. In addition, in these figures, the same or similar elements as in the above embodiment are given the same reference numerals as in the above embodiment. The head-up display device A2 according to the present embodiment is different from the first embodiment in the position of the display area 71 in the windshield 7.

Although not shown, the second mirror 52 (see FIG. 1) of the head-up display device A2 is configured to reflect the reflected light from the first mirror 51 toward the upper region of the windshield 7. It is placed in the A2 casing. Thereby, the display area 71 is arranged above the windshield 7, as shown in FIG.

As shown in FIG. 9, the backlight device 3 according to the second embodiment has the arrangement positions of the light emitting diodes D1 to D4 and the arrangement positions of the light emitting diodes D5 to D7 in the backlight device 3 according to the first embodiment. , are reversed in the y direction. That is, the light emitting diodes D5 to D7 are arranged on the other side (lower side in FIG. 9) in the y direction with respect to the light emitting diodes D1 to D4. The light emitting diodes D1 to D4 irradiate light to a region of the liquid crystal panel 2 corresponding to an upper region of the display region 71 of the windshield 7. The light emitting diodes D5 to D7 irradiate light to a region of the liquid crystal panel 2 corresponding to a lower region of the display region 71 of the windshield 7.

The light emitting diode D1 is arranged at the position closest to the edge 3b. The light emitting diode D4 is arranged at the position closest to the edge 3d. The light emitting diodes D5 to D7 are arranged closest to the edge 3e. Among the light emitting diodes D5 to D7, the light emitting diode D5 is placed closest to the edge 3b, and is placed closer to the edge 3d than the light emitting diode D1 in the x direction. The light emitting diode D7 is disposed closest to the edge 3d among the light emitting diodes D5 to D7, and is disposed closer to the edge 3b than the light emitting diode D4 in the x direction.

According to this embodiment, since the light emitting diodes D1 to D7 are arranged unevenly (not in a matrix) as shown in FIG. 9, the irradiation surface 3a does not irradiate light with the same brightness over the entire surface. Specifically, among the four corners of the irradiation surface 3a, the corner portion where the edge 3b and the edge 3e intersect, and the corner portion where the edge 3d and the edge 3e intersect are separated from any light emitting diode D. Therefore, light with lower brightness than other parts, for example, the central part, is irradiated. Therefore, in the display area 71 of the windshield 7 shown in FIG. The contrast difference between 71 and the surrounding black becomes smaller. This makes the lower corner portions on both sides of the outline of the display area 71 less noticeable. This reduces the postcard effect and reduces the driver's annoyance, leading to improved driving safety and improved visual quality. Further, according to the present embodiment, since the arrangement of the light emitting diodes D is simply devised, it can be realized with a simple configuration, and the manufacturing cost can be suppressed compared to the case of using an OLED or a MEMS laser.

Note that in this embodiment, the brightness of the lower corner areas 713 and 714 on both sides of the display area 71 is low, so that when an image is displayed in these areas, visibility becomes poor. However, in the head-up display device A2, the arrangement of each part of the displayed image is fixed, and it can be set so that no image is displayed in the areas 713 and 714. Furthermore, in the present embodiment, the black portions of the upper both corner areas of the display area 71 are approximately the same as the black portions of the central portion of the display area 71, so that in the upper outline of the display area 71, A postcard effect occurs. However, since the upper part of the display area 71 is away from the driver's line of sight during driving, the driver does not feel much bother.

Also, in this embodiment, the number of light emitting diodes D arranged can be reduced compared to the case where a plurality of light emitting diodes D are arranged in a matrix, so manufacturing costs can be suppressed and the size and weight can be reduced. It is.

In this embodiment as well, the number and arrangement of light emitting diodes D arranged in the backlight device 3 can be freely determined, as in the modified examples of the backlight device 3 according to the first embodiment (see FIGS. 6 to 8). There is a degree. The backlight device 3 includes a light emitting diode D that is closest to the edge 3b among the light emitting diodes D that are disposed closest to the edge 3e, and a light emitting diode D that is disposed closest to the edge 3b. Therefore, the light emitting diode D closest to the edge 3d among the light emitting diodes D disposed on the side of the edge 3d in the x direction or closest to the edge 3e is the one closest to the edge 3d. It is sufficient that the light emitting diode D is disposed closer to the edge 3b in the x direction than the light emitting diode D disposed at that position.

For example, in the backlight device 3 shown in FIG. 8, instead of the four light emitting diodes D1 to D4 arranged closest to the edge 3e, the three light emitting diodes D are replaced by the light emitting diodes D5 to D7. By placing them at the same position in the x direction, the black parts of all four corners of the display area 71 (areas 711 and 712 in FIG. 5 and areas 713 and 714 in FIG. It may be darker than the black part.

In the first and second embodiments, a case has been described in which the head-up display devices A1 and A2 are attached to the vehicle B, but the present invention is not limited to this. Head-up display devices A1 and A2 may be attached to other vehicles such as airplanes and ships, for example.

The head-up display device according to the present invention is not limited to the embodiments described above. The specific configuration of each part of the head-up display device according to the present invention can be modified in various ways.

A1-A2: Head-up display device 1: Display device 1a: Display surface 2: Liquid crystal panel 3: Backlight device 3a: Irradiation surface 3b-3e: Edge D, D1-D7: Light-emitting diode Da: Light-emitting surface 30: Series Light source group 31: Drive circuit 4: Control device 51: First mirror 52: Second mirror 60: Image generation unit 62: Illuminance sensor 7: Windshield 71: Display areas 711 to 714: Area B: Vehicle E: Viewpoint L: Optical path V: Virtual image

Claims (2)

The head-up display device includes a display device, and displays the image as a virtual image of a space in front of a vehicle on the transmissive-reflective portion by reflecting light representing an image displayed on the display device on the transmissive-reflective portion. hand,
The display device includes a liquid crystal panel and a backlight device that irradiates light to the liquid crystal panel,
The backlight device includes:
comprising a plurality of light sources and an irradiation surface that irradiates light to the liquid crystal panel,
Among the four corners of the irradiation surface, the brightness of two adjacent parts in the vehicle width direction of the vehicle is lower than the brightness of the central part, and the brightness of the other two parts among the four corners is lower than the brightness of the central part. The plurality of light sources are arranged so that the light source is approximately the same as
Head-up display device. The irradiation surface includes a first edge and a second edge perpendicular to the first edge,
The plurality of light sources are
a first light source located closest to the first edge;
A second light source closest to the first edge among the light sources disposed closest to the second edge;
including;
The second light source is disposed on the opposite side of the first edge from the first light source in a direction parallel to the second edge.
The head-up display device according to claim 1.

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