JP7516868B2 - Head-up display - Google Patents

Description

The present invention relates to a head-up display.

An increasing number of vehicles are being equipped with head-up displays (HUDs) as a means of providing the driver with driving information such as route guidance and warnings of obstacles. HUDs project display light from a display device onto the vehicle's windshield or a translucent projection member to display a virtual image. Generally, HUDs form one virtual image, and the position at which the virtual image is formed is fixed. Technology has also been disclosed for changing the position at which the virtual image is formed (see Patent Document 1).

JP 2008-268485 A

The present invention provides a head-up display capable of displaying multiple virtual images with different imaging positions.

The head-up display according to the first aspect of the present invention comprises a display device that emits display light and displays an image, and a first transparent display that is arranged on the optical axis of the display device, transmits the display light from the display device, and displays an image. The image displayed by the display device and the image displayed by the first transparent display are superimposed and displayed on a display member.

A head-up display according to a second aspect of the present invention is the head-up display of the first aspect, further comprising a second transparent display that is disposed between the display device and the first transparent display, is disposed on an optical axis of the display device, transmits display light from the display device, and displays an image;
The image displayed by the display device, the image displayed by the second transparent display, and the image displayed by the first transparent display are displayed on the display member in a superimposed manner.

The head-up display according to the third aspect of the present invention is the first aspect, further comprising a reflecting member that reflects the display light from the display device and the display light from the first transparent display toward the display member.

The fourth aspect of the present invention is a head-up display according to any one of the first to third aspects, in which the first transparent display includes an anti-reflection film provided on the display surface.

The head-up display according to the fifth aspect of the present invention is any one of the first to fourth aspects, in which the display device includes an illumination device that emits light and a liquid crystal display element that transmits the light from the illumination device.

The sixth aspect of the present invention relates to a head-up display according to any one of the first to fourth aspects, in which the display device is a self-luminous display device.

The seventh aspect of the present invention relates to a head-up display according to any one of the first to sixth aspects, in which the first transparent display is a transparent organic EL display, a transparent inorganic EL display, or a transparent liquid crystal display.

The present invention provides a head-up display capable of displaying multiple virtual images with different imaging positions.

FIG. 1 is a schematic diagram of a head-up display according to a first embodiment. FIG. 2 is a block diagram of a head-up display. FIG. 3 is a schematic diagram illustrating a virtual image displayed on the display member. FIG. 4 is a flowchart illustrating the operation of the head-up display. FIG. 5 is a schematic diagram illustrating an example of an image displayed by the head-up display. FIG. 6 is a schematic diagram of a head-up display according to the second embodiment.

The following describes the embodiments with reference to the drawings. However, the drawings are schematic or conceptual, and the dimensions and ratios of each drawing are not necessarily the same as those in reality. Even when the same parts are shown in different drawings, the dimensional relationships and ratios of each may be different. In particular, the following embodiments are examples of devices and methods for embodying the technical idea of the present invention, and the shape, structure, arrangement, etc. of the components do not specify the technical idea of the present invention. In the following description, elements having the same function and configuration are given the same reference numerals, and duplicate descriptions are omitted.

[1] First embodiment [1-1] Configuration of head-up display 1 Fig. 1 is a schematic diagram of a head-up display 1 according to a first embodiment. The head-up display 1 includes a display device 10, a transparent display 20, and a reflective member 30. The display device 10, the transparent display 20, and the reflective member 30 are disposed within a dashboard 40 of a vehicle. The display device 10, the transparent display 20, and the reflective member 30 are fixed to the positions shown in Fig. 1 using a support member (not shown).

The display device 10 displays an image. The display device 10 is configured as a display device having an illumination device (light source unit) or a self-luminous display device. In this embodiment, the display device 10 is configured as, for example, a liquid crystal display device. That is, the display device 10 includes an illumination device (backlight) and a liquid crystal display element. The display device 10 may be a self-luminous organic EL (electroluminescence) display device, an inorganic EL display device, or the like.

The transparent display 20 is disposed on the optical axis OA of the display device 10. The transparent display 20 is disposed so that its display surface is perpendicular to the optical axis OA of the display device 10. The transparent display 20 is also called a transmissive display. The transparent display 20 is a display device that is capable of transmitting incident light and displaying an image. Specifically, the transparent display 20 has a transparent display area, and is capable of displaying an image in this transparent display area. The transparent display 20 is also capable of displaying its own image superimposed on a background image in the transparent display area. Examples of transparent displays include transparent organic EL displays, transparent inorganic EL displays, and transparent liquid crystal displays.

The transparent LCD display does not include a backlight, a polarizing plate, or a color filter. It includes an illumination device and an active matrix type LCD element. The illumination device is arranged on the side (edge) of the LCD element, and consists of red, green, and blue LEDs (Light Emitting Diodes). The transparent LCD display uses a field sequential method in which red, green, and blue LEDs are blinked in sequence at high speed. The LCD element is a type that can scatter light, and displays an image by scattering red, green, and blue light.

The reflective member (reflecting mirror) 30 is disposed on the optical axis OA of the display device 10. The reflective member 30 is composed of a concave mirror, a plane mirror, or the like. The reflective member 30 reflects the display light from the display device 10 and the transparent display 20 toward the display member 41. When a concave mirror is used as the reflective member 30, the concave mirror can magnify the display light from the display device 10 and the transparent display 20 at a predetermined magnification rate. The dashboard 40 has an opening through which the display light reflected by the reflective member 30 passes.

The display member 41 is used to project the display light from the display device 10 and the transparent display 20. When the driver (observer) 42 sees the display light reflected by the display member 41, the driver 42 can see virtual images 50, 51 through the display member 41. Examples of information that the driver 42 can see as the virtual images 50, 51 include vehicle speed, engine RPM, mileage, navigation information, outside air temperature, and caution information (warning information) related to the surrounding conditions.

The display member 41 is the windshield (front glass) of the vehicle. The display member 41 may also be a semi-transparent (or transparent) screen (combiner) provided exclusively for the head-up display 1. The combiner is used, for example, by being placed on the instrument panel (also called the front panel or dashboard) of the vehicle, attached to the rearview mirror located in front of the driver 42, or attached to a sun visor installed at the top of the windshield. The combiner is made of, for example, a curved, plate-shaped synthetic resin base material, and a thin metal film such as aluminum (Al) or silver (Ag) is vapor-deposited on the surface of the base material, and the vapor-deposited film provides a semi-transparent function.

[1-2] Block Configuration of Head-Up Display 1 Next, a description will be given of a block configuration of the head-up display 1. FIG.

The head-up display 1 includes a display device 10, a transparent display 20, drive circuits 31 and 32, a voltage generating circuit 33, an operation unit 34, and a control circuit 35.

The display device 10 includes a display element 11 and a backlight (illumination device) 12. The display element 11 is made of a liquid crystal display element. The backlight 12 emits light and emits illumination light toward the display element 11. The display element 11 transmits the illumination light to perform optical modulation and display an image. The display light DL1 emitted from the display device 10 is incident on the transparent display 20.

The drive circuit 31 drives the display device 10. Specifically, the drive circuit 31 controls the orientation of the liquid crystal layer included in the display device 10 by applying a voltage to multiple electrodes included in the display device 10. The drive circuit 31 also controls the on and off of the backlight 12.

The drive circuit 32 drives the transparent display 20. Specifically, the drive circuit 32 applies a voltage to multiple electrodes included in the transparent display 20, causing the transparent display 20 to display an image. The transparent display 20 transmits the display light from the display device 10 and emits display light DL2. In other words, the display light DL2 emitted from the transparent display 20 includes the display light from the display device 10.

The voltage generation circuit 33 uses an external power source to generate multiple voltages necessary for the operation of the head-up display 1. The voltages generated by the voltage generation circuit 33 are supplied to each module in the head-up display 1, particularly to the drive circuits 31 and 32.

The operation unit 34 receives operations from the driver 42. The operation unit 34 generates a control signal corresponding to the operation from the driver 42 and sends this control signal to the control circuit 35.

The control circuit 35 controls the overall operation of the head-up display 1. The control circuit 35 can control the drive circuits 31 and 32 based on a control signal sent from the operation unit 34. The control circuit 35 supplies the drive circuit 31 with a signal necessary for the display device 10 to display an image. Similarly, the control circuit 35 supplies the drive circuit 32 with a signal necessary for the transparent display 20 to display an image.

[1-3] Operation The operation of the head-up display 1 configured as above will be described below. FIG.

"f" in Figure 3 is the focal point of the concave mirror (reflective member) 30, and "o" in Figure 3 is the center of curvature of the concave mirror 30. The center of curvature of a concave mirror is the center of a spherical surface (circle of curvature) that is tangent to the pole (or near the pole) where the optical axis and the concave mirror intersect. If the distance from the concave mirror 30 to the center of curvature o is "r", then the distance from the concave mirror 30 to the focal point f is "r/2".

In FIG. 3, the image 52 displayed by the display device 10 and the virtual image 50 that corresponds to the image 52 and is viewed by the driver 42 are indicated by hatched arrows. The image 53 displayed by the transparent display 20 and the virtual image 51 that corresponds to the image 53 and is viewed by the driver 42 are indicated by unhatched arrows.

The display device 10 displays the image 52. That is, the position of the image 52 in FIG. 3 corresponds to the position of the display device 10. The position at which the virtual image 50 is viewed is calculated by the point where a first line passing through the center of curvature o and the image 52 intersects with a second line extending horizontally from the point where the line passing through the focal point f and the image 52 reaches the concave mirror 30.

The transparent display 20 displays the image 53. That is, the position of the image 53 in FIG. 3 corresponds to the position of the transparent display 20. The position at which the virtual image 51 is viewed is calculated by the point where a first line passing through the center of curvature o and the image 53 intersects with a second line extending horizontally from the point where the line passing through the focal point f and the image 53 reaches the concave mirror 30.

When a concave mirror is used as the reflecting member 30, the display device 10 and the transparent display 20 are positioned on the concave mirror 30 side relative to the focal point f of the concave mirror 30.

The display light from the display device 10 is reflected by the concave mirror 30 and then reaches the display member 41. The driver 42 sees the image 52 displayed by the display device 10 as a virtual image 50 through the display member 41. The display light from the transparent display 20 is reflected by the concave mirror 30 and then reaches the display member 41. The driver 42 sees the image 53 displayed by the transparent display 20 as a virtual image 51 through the display member 41.

The driver 42 sees the virtual image 50 and the virtual image 51 superimposed on each other. The virtual image 50 and the virtual image 51 are also seen by the driver 42 at different image positions. Specifically, the virtual image 50 is seen relatively far from the driver 42, and the virtual image 51 is seen relatively close to the driver 42.

Figure 4 is a flowchart explaining the operation of the head-up display 1.

The head-up display 1 has two operating modes, a first operating mode M1 and a second operating mode M2. The first operating mode M1 is a mode in which only the display device 10 displays an image. The second operating mode M2 is a mode in which both the display device 10 and the transparent display 20 display an image.

The control circuit 35 monitors whether or not an operation mode has been selected, for example, by the driver 42 operating the operation unit 34 (step S100). If an operation mode has been selected, the process proceeds to step S101.

When the first operation mode M1 is selected (step S101 = Yes), the control circuit 35 executes the first operation mode M1 (step S102). In the first operation mode M1, the control circuit 35 causes the display device 10 to display an image and turns off the transparent display 20. This allows the driver 42 to view only the virtual image 50 displayed by the display device 10. The transparent display 20 being off means that the transparent display 20 is entirely transparent and does not display an image.

When the second operation mode M2 is selected (step S101 = No), the control circuit 35 executes the second operation mode M2 (step S103). In the second operation mode M2, the control circuit 35 causes the display device 10 to display an image and also causes the transparent display 20 to display an image. As a result, the driver 42 sees the virtual image 51 displayed by the transparent display 20 superimposed on the virtual image 50 displayed by the display device 10.

For example, the display device 10 displays driving information such as vehicle speed and route information as information that is always displayed while driving. The transparent display 20 displays warning information such as "railroad crossing ahead" and "pedestrians ahead" as information that is displayed in an emergency.

The control circuit 35 may determine the process of switching between the first operation mode M1 and the second operation mode M2. The control circuit 35 may normally execute the first operation mode M1, and execute the second operation mode M2 when it determines that it is necessary to display predetermined information. The control circuit 35 may also receive information from a sensor provided in the vehicle, and use this information to display warning information on the transparent display 20.

Figure 5 is a schematic diagram illustrating an example of an image displayed by the head-up display 1. Figure 5(a) is a diagram illustrating an example of an image displayed only by the display device 10. Figure 5(b) is a diagram illustrating an image displayed by the display device 10 and the transparent display 20. That is, Figure 5(a) is a display example of the first operation mode M1, and Figure 5(b) is a display example of the second operation mode M2.

As shown in FIG. 5(a), in the first operating mode M1, the display device 10 displays an image related to the vehicle speed, and the transparent display 20 is turned off. A virtual image 50 related to the vehicle speed is displayed on the windshield 41.

As shown in FIG. 5(b), in the second operating mode M2, the display device 10 displays an image related to the vehicle speed, and the transparent display 20 displays an image related to a sign indicating a railroad crossing. A virtual image 50 related to the vehicle speed and a virtual image 51 related to the sign indicating a railroad crossing are displayed on the windshield 41. The vehicle speed and the sign are then displayed superimposed.

[1-4] Modifications An anti-reflection film may be provided on the display surface of the transparent display 20. The display surface of the transparent display 20 is the surface opposite to the surface facing the display device 10.

Anti-reflection films having a moth-eye structure may also be used as the anti-reflection structure. A moth-eye structure is a structure in which multiple cone-shaped protrusions are arranged at equal intervals or without gaps.

External light such as sunlight travels an optical path opposite to that of the head-up display 1 to reach the transparent display 20 and is reflected by the display surface of the transparent display 20. This reflected light is visible to the driver, degrading the display characteristics of the head-up display 1.

According to this modified example, the amount of light reflected by the display surface of the transparent display 20 from outside can be reduced. This makes it possible to prevent the display characteristics of the head-up display 1 from deteriorating.

[1-5] Advantages of the First Embodiment According to the first embodiment, it is possible to realize a head-up display 1 capable of displaying a plurality of virtual images with different imaging positions. Furthermore, it is possible to display a plurality of virtual images with a simpler configuration without having a mechanical driving mechanism. For example, it is possible to display a plurality of virtual images with different imaging positions without changing the focal length of a lens or a concave mirror.

In addition, by displaying multiple virtual images with different imaging positions, it is possible to display driving information such as the vehicle speed required for normal driving on one virtual image, and temporary information (such as danger avoidance information or route guidance information) on another virtual image.

[2] Second embodiment In the first embodiment, the head-up display 1 is configured to include one transparent display, but two or more transparent displays may be provided. The second embodiment is an example of a head-up display 1 including two transparent displays.

Figure 6 is a schematic diagram of a head-up display 1 according to a second embodiment. The head-up display 1 includes two transparent displays 20-1 and 20-2.

The transparent display 20-1 is disposed on the optical axis OA of the display device 10. The transparent display 20-1 is disposed so that its display surface is perpendicular to the optical axis OA of the display device 10.

The transparent display 20-2 is disposed on the optical axis OA of the display device 10 and between the transparent display 20-1 and the display device 10. The transparent display 20-2 is disposed so that its display surface is perpendicular to the optical axis OA of the display device 10.

The transparent displays 20-1 and 20-2 each display an image. The image on the transparent display 20-1 is viewed by the driver 42 as a virtual image 51-1. The image on the transparent display 20-2 is viewed by the driver 42 as a virtual image 51-2. The configuration other than that of the transparent displays 20-1 and 20-2 is the same as that of the first embodiment.

The three virtual images 50, 51-1, and 51-2 are superimposed on one another and viewed by the driver 42 at different spatial positions.

According to the second embodiment, it is possible to display three or more virtual images with different imaging positions. The other effects are the same as those of the first embodiment.

Also, as in the modified example of the first embodiment, the transparent display 20-1 may be provided with an anti-reflection film.

The present invention is not limited to the above-described embodiments, and can be modified in various ways in the implementation stage without departing from the gist of the invention. The embodiments may also be implemented in appropriate combination, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combinations selected from the multiple constituent elements disclosed. For example, if the problem can be solved and an effect can be obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiments, the configuration from which these constituent elements are deleted can be extracted as an invention.

1...head-up display, 10...display device, 11...display element, 12...illumination device, 20...transparent display, 30...reflective member, 31, 32...drive circuit, 33...voltage generating circuit, 34...operation unit, 35...control circuit, 40...dashboard, 41...display member, 50, 51...virtual image, 52, 53...image.

Claims (8)

a display device that emits display light, displays an image, and has a backlight;
a first drive circuit for driving only the display device;
a first transparent display that is disposed on an optical axis of the display device, transmits display light from the display device, displays an image, and does not have a backlight;
a second drive circuit for driving only the first transparent display;
a control circuit for controlling the first drive circuit and the second drive circuit;
Equipped with
the image displayed by the display device and the image displayed by the first transparent display are displayed so as to be superimposed on an optical axis of the display device, and the superimposed images are displayed on a display member consisting of a windshield of a vehicle ;
The control circuit temporarily displays warning information on the first transparent display based on information from a device provided in the vehicle,
The warning information includes text information.
Head-up display. A second transparent display is disposed between the display device and the first transparent display, is disposed on an optical axis of the display device, transmits display light from the display device, and displays an image;
2. The head-up display according to claim 1, wherein an image displayed by the display device, an image displayed by the second transparent display, and an image displayed by the first transparent display are displayed so as to be superimposed on an optical axis of the display device, and the superimposed images are displayed on the display member. The head-up display according to claim 1 , further comprising a reflecting member that reflects display light from the display device and display light from the first transparent display toward the display member. The reflecting member is a concave mirror.
The concave mirror is configured to magnify the image by reflection;
The head-up display according to claim 3 , wherein the display device and the first transparent display are disposed on a side of the concave mirror relative to a focal point of the concave mirror. The head-up display according to claim 1 , wherein the first transparent display includes an anti-reflection film provided on a display surface. The head-up display according to claim 1 , wherein the display device includes a liquid crystal display element that transmits light from the backlight. The head-up display according to claim 1 , wherein the first transparent display is a transparent organic electroluminescence display, a transparent inorganic electroluminescence display, or a transparent liquid crystal display. The head -up display according to claim 1 , wherein the control circuit is capable of executing a first operating mode in which the first transparent display is fully transparent, and a second operating mode in which an image is displayed on the first transparent display.