Head-up display device and method of controlling display

Abstract

To reduce a difference in brightness when switching between virtual image display and real image display in a case where a display and light sources of a backlight are shared between the virtual image display and the real image display.SOLUTION: A head-up display device comprises: an imaging optical system 2 that includes a first reflection member 22 having, as a polarization state, first and second polarization states different from each other in transmittance, and a second reflection member 23 reflecting first display light L1 transmitted through the first reflection member, and in which the display light in the first polarization state is emitted through a first optical path OP1 reflected by a surface of the first reflection member and forms a virtual image V1, and the display light in the second polarization state is transmitted through the first reflection member 22, is emitted through a second optical path OP2 reflected by the second reflection member 23, and forms a real image V2; and a control section 13 that controls the polarization state and controls to turn on and off of each of a plurality of light sources 14 of a backlight 12. When the virtual image is displayed, the control section controls such that at least some of the light sources 14 are turned on, and when the real image is displayed, the control section controls such that at least some of the light sources are turned on, and the power consumption is increased compared with that in the virtual image display.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a head-up display device having an outlet from which display light is emitted toward a light-transmitting member, thereby allowing a virtual image and a real image of a display image represented by the display light to be visually recognized. [Background technology]

[0002] There is known a head-up display device in which display light is emitted from an emission port toward a light-transmitting member, thereby allowing a virtual image and a real image of the display image represented by the display light to be viewed. For example, Patent Document 1 proposes a head-up display device in which, in a structure in which a display image displayed on a screen by light from a display device is reflected toward the light-transmitting member, the front-to-back positional relationship between the optical focus of an imaging optical system and the screen is changed to switch the display between a state in which a virtual image is viewed outside the light-transmitting member and a state in which a real image is viewed inside the light-transmitting member (see paragraphs

[0008] to

[0014] and Figures 2(a) and (b) of Patent Document 1).

[0003] In a head-up display device having such a structure, as a result of the display switching, appropriate brightness and uniformity cannot be obtained when switched to a real image viewing state, and conversely, if the brightness and uniformity are adjusted to appropriate brightness and uniformity in the real image viewing state, they become inappropriate in the virtual image viewing state.For this reason, for example, Patent Document 2, which was unpublished as of the filing date of this application, describes a head-up display device that, when switching between displaying a virtual image and a real image, can obtain good brightness and uniformity in both the virtual image viewing state and the real image viewing state by switching between a lenticular lens for the virtual image viewing state and a lenticular lens for the real image viewing state (see paragraph

[0008] and Figures 5 to 9 of Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-70074 [Patent Document 2] Patent application 2023-046171 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the technology described in the above-mentioned Patent Document 2, good luminance and uniformity can be obtained in both the virtual image viewing state and the real image viewing state. However, when the display image is switched between a virtual image and a real image, if the backlight brightness is the same, the light distribution characteristics from the display device are different for the virtual image display and the real image display, resulting in a difference in brightness between the virtual image display and the real image display. In particular, the inventors recognized that the real image display is darker than the virtual image display.

[0006] This phenomenon is known to occur because, for example, when a virtual image is displayed, light distribution characteristics are required that widen the optical axis in both the vertical direction (V direction) and the horizontal direction (H direction) (the backlight light source irradiates the display so that the illumination light is divergent), as shown in (A) and (B) of a virtual image, whereas when a real image is displayed, light distribution characteristics are required that narrow the optical axis in both the vertical direction (V direction) and the horizontal direction (H direction) (the backlight light source irradiates the display so that the illumination light is converged), as shown in (C) and (D) of a real image. If a virtual image or a real image is displayed using the light distribution characteristics shown in (A), (B), (C), and (D) of Figure 7, the virtual image will be displayed with appropriate brightness and uniformity, but the real image will not be displayed with appropriate light distribution characteristics, and therefore appropriate brightness and uniformity cannot be ensured. The light distribution characteristics can be adjusted by the structure of the lens group, but because it is difficult to design lenses that are optimized for both virtual and real images, a lens group optimized for virtual images will not be able to ensure appropriate brightness and uniformity when displaying a real image (see paragraphs

[0019] to

[0023] of Patent Document 2).

[0007] Therefore, an object of the present invention is to provide a head-up display device that can reduce the difference in brightness when switching between virtual image and real image displays when multiple light sources for the display and backlight are shared between virtual image display and real image display.

[0008] Other objects of the present invention will become apparent to those skilled in the art by referring to the following exemplary aspects and best modes, as well as the accompanying drawings. [Means for solving the problem]

[0009] In order to facilitate an understanding of the outline of the present invention, the following examples are given of embodiments according to the present invention.

[0010] A first aspect according to the present invention is a head-up display device having an outlet, and emitting display light from the outlet toward a light-transmitting member, thereby allowing a virtual image and a real image of a display image represented by the display light to be viewed, the head-up display device including: a display; a backlight including a plurality of light sources; a first reflecting member having a first polarization state and a second polarization state whose transmittance differs depending on the polarization state; and a second reflecting member that reflects the display light that has passed through the first reflecting member, wherein the first display light in the first polarization state is emitted along a first optical path that is reflected by a surface of the first reflecting member to form the virtual image, and the second display light in the second polarization state is The optical system includes an imaging optical system that transmits light through the first reflecting member and exits on a second optical path where it is reflected by the second reflecting member to form the real image, and a control unit that controls the polarization state and controls the turning on and off of each of the multiple light sources of the backlight, wherein the control unit controls at least some of the multiple light sources of the backlight to be turned on when the virtual image is displayed, and controls at least some of the multiple light sources of the backlight to be turned on when the real image is displayed, and controls the multiple light sources of the backlight to consume more power than when the virtual image is displayed.

[0011] In a first aspect, the display device includes a first reflecting member having a first polarization state and a second polarization state whose transmittance differs depending on the polarization state, and a second reflecting member that reflects the display light that has passed through the first reflecting member, and has an imaging optical system in which the display light in the first polarization state is emitted along a first optical path where it is reflected by the surface of the first reflecting member to form a virtual image, and the display light in the second polarization state is emitted along a second optical path where it is transmitted through the first reflecting member and reflected by the second reflecting member to form a real image, and a control unit controls the polarization state of the imaging optical system to turn on at least some of the multiple light sources of the backlight when a virtual image is displayed, and on the other hand, to turn on at least some of the multiple light sources of the backlight when a real image is displayed, and controls the multiple light sources of the backlight to consume more power than when a virtual image is displayed.

[0012] When the backlight's multiple light sources are, for example, light-emitting diodes (LEDs), the control unit controls the ON / OFF timing of each LED and the value of the current flowing through the LED, and also controls the voltage supplied to the backlight by an LED drive circuit (e.g., light source drive unit 133 in FIG. 2 ) to improve power efficiency. In this way, in a head-up display device that can switch between virtual image display and real image display and in which multiple light sources for the display and backlight are shared between the virtual image display and the real image display, by controlling the power supplied to the backlight to be increased when switching from virtual image display to real image display, the difference in brightness when switching between virtual image display and real image display can be reduced, thereby minimizing the discomfort felt by the occupant who is the viewer, and at the same time, appropriate brightness and uniformity can be ensured for both the virtual image display and the real image display. Furthermore, by reducing the difference in brightness (luminance difference) when switching from virtual image display to real image display, the discomfort felt by the occupant who is the viewer can be reduced.

[0013] In a second aspect dependent on the first aspect, the control unit may perform control to increase a value of a current flowing through the plurality of light sources of the backlight when the real image is displayed.

[0014] In the second aspect, when switching the display from a virtual image to a real image, the control unit controls the value (current value) of the current flowing through the multiple light sources (e.g., LEDs) of the backlight to improve the brightness of the backlight, thereby reducing the difference in brightness between the displays without increasing the lighting area of ​​the multiple light sources of the backlight, thereby suppressing the discomfort felt by the occupant who is viewing the display. In particular, since the brightness can be increased when a real image is displayed, appropriate brightness and uniformity can be ensured for both the virtual image display and the real image display.

[0015] In a third aspect dependent on the first or second aspect, the control unit may perform control to increase the number of light sources turned on among the plurality of light sources of the backlight when the real image is displayed.

[0016] In the third aspect, when switching the display from a virtual image to a real image, the control unit increases the number (area) of light sources that are turned on among the backlights that have multiple light sources implemented, thereby reducing the difference in brightness between the respective displays and suppressing the discomfort felt by the occupant who is viewing them. In particular, since the brightness can be increased when a real image is displayed, appropriate brightness and uniformity can be ensured for both the virtual image display and the real image display.

[0017] In a fourth aspect dependent on the first to third aspects, when displaying the real image, the control unit may perform control to increase the value of the current flowing through the plurality of light sources of the backlight, and may also perform control to increase the number of light sources that are turned on among the plurality of light sources of the backlight.

[0018] In the fourth aspect, when switching the display from a virtual image to a real image, the control unit controls the value of the current flowing through the multiple light sources (e.g., LEDs) of the backlight to improve the brightness of the backlight, and by increasing the number (area) of light sources that are turned on among the multiple light sources implemented in the backlight, the difference in brightness between the respective displays can be further reduced (minimized). In particular, since the brightness can be increased when a real image is displayed, appropriate brightness and uniformity can be ensured for both the virtual image display and the real image display.

[0019] A fifth aspect according to the present invention provides an imaging optical system including an outlet, a backlight including a plurality of light sources, a display that transmits illumination light emitted by the light sources to generate a display image, a first reflecting member having a first polarization state and a second polarization state whose transmittance differs depending on the polarization state, and a second reflecting member that reflects the first display light that has transmitted through the first reflecting member, wherein the first display light in the first polarization state is emitted along a first optical path reflected by a surface of the first reflecting member to form a virtual image, and the second display light in the second polarization state is emitted along a second optical path reflected by the second reflecting member to form a real image, and a control unit that controls the polarization states and controls turning on and off each of the plurality of light sources of the backlight. A control method for a head-up display device, comprising: a step in which the control unit controls the polarization state to switch the display light to be emitted to display light of a first polarization state or display light of a second polarization state; a step in which the control unit controls to turn on at least some of the plurality of light sources of the backlight when the first display light of the first polarization state is emitted from the emission outlet to form the virtual image; and a step in which the control unit controls to turn on at least some of the plurality of light sources of the backlight and to increase the power consumed by the plurality of light sources of the backlight compared to when the virtual image is formed by emitting the second display light of the second polarization state from the emission outlet to form the real image.

[0020] In a fifth aspect, the control unit includes a first reflecting member having a first polarization state and a second polarization state whose transmittance differs depending on the polarization state, and a second reflecting member that reflects the display light that has passed through the first reflecting member, and controls the polarization state of an imaging optical system in which the display light in the first polarization state is emitted along a first optical path where it is reflected by the surface of the polarized reflecting member to form a virtual image, and the display light in the second polarization state is emitted along a second optical path where it is transmitted through the first reflecting member and reflected by the second reflecting member to form a real image, and the control unit is configured to have a control procedure (step) of controlling the imaging optical system to turn on at least some of the multiple light sources of the backlight when emitting display light in the first polarization state to form a virtual image, and turning on at least some of the multiple light sources of the backlight and controlling the power consumed by the multiple light sources of the backlight to be larger than when emitting display light in the second polarization state to form a virtual image.

[0021] Therefore, when LEDs are implemented as the multiple light sources of the backlight, for example, the control device can improve power efficiency by controlling the ON / OFF timing of each LED and the current value flowing through the LED row, as well as controlling the voltage supplied to the backlight by an LED drive circuit (e.g., light source drive unit 133 in FIG. 2). In this way, in a head-up display device that can switch between virtual image display and real image display and in which multiple light sources of the display device and backlight are shared between virtual image display and real image display, by controlling the power supplied to the backlight to be increased when switching from virtual image display to real image display, the difference in brightness when switching between virtual image display and real image display can be minimized, ensuring appropriate brightness and uniformity for both virtual image display and real image display. Furthermore, by reducing the difference in brightness (luminance difference) when switching from virtual image display to real image display, the discomfort felt by the occupant who is viewing the display can be reduced.

[0022] Those skilled in the art will easily understand that the exemplified embodiments according to the present invention can be further modified without departing from the spirit of the present invention. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram showing an example of a configuration including an imaging optical system of a head-up display device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of a control system of the head-up display device according to the embodiment of the present invention. [Figure 3] FIG. 3 is a flowchart showing an example of the operation of the control system of the head-up display device according to the embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing an example of an arrangement (layout) of a plurality of light sources mounted in a backlight of a head-up display device according to an embodiment of the present invention. [Figure 5] FIG. 5 is a diagram showing an example of a light source lighting pattern of a plurality of light sources mounted in a backlight when a virtual image is displayed and when a real image is displayed in the head-up display device according to the embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing another example of the light source lighting pattern of a plurality of light sources mounted in the backlight when the head-up display device according to the embodiment of the present invention displays a virtual image and when it displays a real image. [Figure 7] FIG. 7 is a diagram cited for explaining the orientation characteristics when a virtual image is displayed and the orientation characteristics when a real image is displayed. DETAILED DESCRIPTION OF THE INVENTION

[0024] The best mode described below is used to facilitate understanding of the present invention, and therefore, those skilled in the art should be aware that the present invention is not unduly limited by the mode described below (hereinafter referred to as the present mode).

[0025] (Configuration of the embodiment) Refer to FIG. 1. FIG. 1 is a diagram showing an example of a configuration including an imaging optical system 2 of a head-up display device (hereinafter referred to as HUD device 1 unless otherwise specified) according to this embodiment. The HUD device 1 of this embodiment includes a light source 14 mounted on a light source circuit board 140 (see FIG. 4), which is made of, for example, LEDs, emitting white light in the visible wavelength range; a backlight 12 including lenses (a condenser lens and a lenticular lens, not shown) that focus the light emitted by the light source 14; and a display 11, such as a liquid crystal display, that generates an image using the light emitted from the light source 14 and switches the polarization state of the emitted light between a first polarization state and a second polarization state, thereby generating display light L1 and L2 that represent a display image. The light source circuit board 140 is connected to a control unit 13 (control circuit board) (described later) by wiring (not shown), and is controlled by the control unit 13 to turn on or off the LEDs serving as the light source 14.

[0026] The HUD device 1 of this embodiment also includes a first reflecting member 22, for example, a half mirror, having a first polarization state and a second polarization state whose transmittance differs depending on the polarization state, a second reflecting member 23 that reflects display light L1 transmitted through the first reflecting member 22, and a third reflecting member 24 that reflects display light L (display light L1 representing a virtual image V1 and display light L2 representing a real image V2) representing a display image displayed on the display 11 toward a windshield WS that is a light-transmitting member. Here, the display light L1 in the first polarization state is emitted along a first optical path OP1 where it is reflected by the surface of the first reflecting member 22 to form a virtual image V1, and the display light L2 in the second polarization state is transmitted through the first reflecting member 22 and emitted along a second optical path OP2 where it is reflected by second and third reflecting members 23 and 24 to form a real image V2, forming an imaging optical system 2.

[0027] Although countless light rays would normally be emitted from the display 11, for the sake of simplicity, only representative light rays emitted from the center of the display 11 and passing through the center of the eyebox are shown by solid lines (virtual image V1) and dashed lines (real image V2). The first reflecting member 22 may be any member other than a half mirror that transmits the first display light L1 on one surface and reflects the second display light L2 on the other surface. For example, a member with a wavelength-selective film attached or a coated transparent member may be used. A lenticular lens 21 made of a translucent resin material is interposed between the display 11 and the first reflecting member 22. This lenticular lens 21 extends the display light L (L1, L2) generated and emitted by the display 11 in different directions, thereby improving uniformity.

[0028] The display light L (L1, L2) emitted from the display 11 is ultimately projected toward the windshield WS, which is a light-transmitting member, through an emission port 17, which is an opening provided in the upper part of the housing of the HUD device 1. As a result, an occupant DR, who is a viewer riding in the vehicle C, can visually recognize the display light L1 or L2 reflected by the windshield WS, and can visually recognize a virtual image V1 formed on the far side of the windshield WS (the outside of the vehicle across the windshield WS) and a real image V2 formed on the near side of the windshield WS (the inside of the vehicle across the windshield WS).

[0029] The HUD device 1 of this embodiment further includes a control unit 13 that controls the polarization state as described above and controls the on / off of each of the multiple light sources 14 of the backlight 12 (see 14 in FIG. 2, not shown in FIG. 1). When displaying a virtual image V1, the control unit 13 controls at least some of the multiple light sources 14 of the backlight 12 to be turned on, and when displaying a real image V2, the control unit 13 controls at least some of the multiple light sources 14 of the backlight 12 to be turned on and increases the power consumed by the multiple light sources 14 of the backlight 12 compared to when displaying the virtual image V1. Note that the control unit 13 can also control the display content on the display 11, as will be described later.

[0030] Please refer to Fig. 2. Fig. 2 is a diagram showing an example of the configuration of the control system of the HUD device 1 of this embodiment. More specifically, it is a functional configuration diagram showing the configuration of the image generation unit (hereinafter referred to as PGU10: Picture Generation Unit) in the HUD device 1, and also includes the control unit 13 shown in Fig. 1. Note that Fig. 2 shows only the minimum necessary configuration directly related to the present invention, and other well-known configurations are omitted.

[0031] 2, the PGU 10 includes a display device 11, a backlight 12 (light source 14), and a control unit 13. The control unit 13 includes a display control unit 131 that issues a command to the display device 11 to generate display lights L1 and L2 that represent a display image based on information or signals transmitted from various devices 30, such as a vehicle speed sensor, a navigation device, a RADAR (Radio Detecting and Ranging), or a LiDAR (Light Detection and Ranging).

[0032] The control unit 13 also includes a display drive unit 132 that generates an image using light irradiated from the light source 14 of the backlight 12 based on a signal transmitted from a switch 20 that switches the driving mode (manual driving, automatic driving) of the vehicle C, switches the polarization of the emitted light between a first polarization and a second polarization state that are different from each other, and controls the switching of the polarization direction of the display 11 that generates display light L1, L2 that represents the display image.

[0033] The control unit 13 also includes a light source driving unit 133 that controls the supply of power necessary to turn on and off the light sources 14 mounted on a light source circuit board 140 (see FIG. 4 ) of the backlight 12. The light source driving unit 133 controls the ON / OFF timing of each LED mounted on the light source circuit board 140 as the light source 14 and the value of the current (current value) flowing through each LED, and also controls the voltage supplied to the light sources 14, thereby improving power efficiency. As described above, in the HUD device 1 that is capable of switching between the virtual image V1 display and the real image V2 display and in which the multiple light sources 14 included in the display unit 11 and the backlight 12 are shared by the virtual image V1 display and the real image V2 display, when switching from the virtual image V1 display to the real image V2 display, the light source driving unit 133 controls the power supplied to the backlight 12 (light sources 14) to be increased, thereby reducing the difference in brightness when switching between the virtual image V1 and the real image V2 display. Therefore, the difference in brightness (luminance difference) when switching from the virtual image V1 display to the real image V2 display is reduced, thereby suppressing the discomfort felt by the occupant DR who is the viewer.

[0034] The display 11 includes a TFT (Thin Film Transistor) display element 111 that generates display light L1, L2 representing figures of any shape based on a signal transmitted from a display control unit 131, and a switching element 112 that switches the emitted display light L to either first polarized display light L1 or second polarized display light L2 in accordance with a signal transmitted from a display drive unit 132.

[0035] In the configuration of FIG. 2, for example, during manual driving, the display drive unit 132 controls the switching element 112 to emit display light L1 of a first polarization. At this time, the display control unit 131 controls the display element 111 to generate display light L1 that displays vehicle information, route guidance information, warning displays, etc. Furthermore, for example, during autonomous driving, the display drive unit 132 performs switching control on the switching element 112 to emit display light L2 of a second polarization. At this time, the display control unit 131 controls the display element 111 to generate display light L2 that displays an assistant or agent that supports the driving of the occupant R, characters representing them, etc.

[0036] In this way, in the HUD device 1 of this embodiment, when it is desired to display a virtual image V1, the display 11, which controls polarization, sets the polarization state of the backlight 12 (light source 14) to a polarization state that is reflected by, for example, the first reflecting member 22, which is composed of a half mirror.The display light L1 is reflected by the second reflecting member 23 and enters the third reflecting member 24, is further reflected by the third reflecting member 24 and enters the windshield WS, which is a translucent member, is reflected by the windshield WS, and becomes a virtual image V1 that can be displayed on the outside of the vehicle across the windshield WS (an imaging area that is virtually set in front of the vehicle C and is set at an angle with respect to the road surface) (see optical path OP1 in Figure 1).

[0037] On the other hand, in the HUD device 1 of this embodiment, when it is desired to display a real image V2, the display 11, which controls polarization, changes the polarization state of the backlight 12 (light source 14) to a polarization state that is transmitted by, for example, a first reflecting member 22 composed of a half mirror, so that the display light L2 is reflected by the second reflecting member 23 and incident on the third reflecting member 24, is further reflected by the third reflecting member 24 and incident on the windshield WS, which is a translucent member, is reflected by the windshield WS, and becomes a real image V2 that can be displayed on the passenger compartment side in front of the occupant DR across the windshield WS (an imaging area that is virtually set when the vehicle is standing perpendicular to the road surface) (see the second optical path OP2 in Figure 1).

[0038] That is, for example, the imaging area of ​​virtual image V1, which has an angle of less than 45 degrees with the road surface, looks like the display content is unfolded on the road surface, so when performing navigation, the display content looks like it is superimposed on the road surface, which has the advantage of enabling intuitive information presentation. On the other hand, the imaging area of ​​real image V2, which has an angle of 45 degrees or more with the road surface, is expected to be used in situations such as autonomous driving and watching entertainment content while stopped, and has the advantage of improving visibility by being displayed while standing in front of the road surface.

[0039] (Operation of the embodiment) Please refer to Fig. 3. Fig. 3 is a flowchart showing an example of the operation of the control system of the HUD device 1 of this embodiment. Also, Fig. 4 is a diagram showing an example of the arrangement (layout) of the plurality of light sources 14 mounted on the backlight 12 of the HUD device 1 of this embodiment on the light source circuit board 140. Hereinafter, with reference to Figs. 3 and 4, the operation of the control system (PGU 10, mainly the control unit 13) of the HUD device 1 of this embodiment shown in Fig. 2 will be described in detail.

[0040] In the PGU 10, the control unit 13 (display drive unit 132) first determines whether the vehicle C is being manually driven or automatically driven based on a signal transmitted from the switch 20 that switches the driving mode (manual driving, automatic driving) of the vehicle C (step ST101). If it is determined that the vehicle C is being manually driven (step ST101 “M”), the control unit 13 (display drive unit 132) controls the imaging optical system 2 so that the display light L1, which is the first polarization, is emitted via the switching element 112 of the display 11. That is, the control unit 13 (display control unit 131) switches the imaging optical system 2 so that the display light L1 is projected from the emission port 17 toward the windshield WS along the first optical path OP1 (step ST102). At this time, the control unit 13 (display control unit 131) controls the display element 111 of the display 11 to generate the first display light L1 (virtual image V1) that represents vehicle information, route guidance information, warning display, etc. (step ST103).

[0041] Next, the control unit 13 (light source driving unit 133) controls the lighting of at least some (here, all LEDs) of the LEDs serving as the light source 14, for example, as shown in Figure 4 as an example of the arrangement (layout) of the light source 14 on the light source circuit board 140 (step ST104), and the display 11 emits (projects) the generated display light L1 (virtual image V1) toward the windshield WS, which is a translucent member, via the imaging optical system 2 (first optical path OP1) and the emission port 17 (step ST108).

[0042] On the other hand, if the vehicle C is in autonomous driving (step ST101 "A"), the control unit 13 (display drive unit 132) controls the imaging optical system 2 so that the switching element 112 emits the second polarized light, that is, the second display light L2. That is, the imaging optical system 2 is switched so that the second display light L2 is projected from the emission port 17 toward the windshield WS along the second optical path OP2 (step ST105). At this time, the display control unit 131 controls the display element 111 to generate the second display light L2 representing an assistant or agent that supports the driving of the occupant DR, characters representing them, or the like (step ST106).

[0043] Next, the control unit 13 (light source driving unit 133) controls to turn on at least some (here, all LEDs) of the LEDs serving as the light sources 14, as shown in an example of the arrangement (layout) of the light sources 14 on the light source circuit board 140 in Fig. 4, and also controls to increase the power supplied to the light sources 14 mounted on the light source circuit board 14 of the backlight 12 compared to when a virtual image is displayed (step ST107). Here, when controlling the power supplied to the light sources 14, for example, it is possible to increase the value (current value) of the current flowing through the multiple light sources 14 of the backlight 12, or to increase the number (lighting area) of light sources 14 that are turned on, or to do both, thereby increasing the amount of power consumption and making the brightness when the real image V2 is displayed brighter than when the virtual image V1 is displayed.

[0044] Furthermore, as shown in FIGS. 5(A) and 5(B), for example, some of the light sources 14 of the backlight 12 may be turned on when the virtual image V1 is displayed, and all of the light sources 14 may be turned on when the real image V2 is displayed. In this case, the brightness of each light source 14 may be the same when the virtual image V1 and the real image V2 are displayed, or the light sources 14 may be brighter when the real image V2 is displayed. While the lighting pattern of the light sources 14 when the real image V2 is displayed shown in FIG. 5(B) shows all the light sources 14 turned on, if the power consumption is greater when the real image V2 is displayed than when the virtual image V2 is displayed, some of the light sources 14 that were turned on when the virtual image V1 was displayed may be turned off when the real image V2 is displayed, as shown in the lighting patterns of FIGS. 6(A) and 6(A) and 6(B). Details of the lighting patterns of the light sources 14 shown in FIGS. 5(A) and 6(A) and 6(B) will be described later.

[0045] Finally, the display 11 emits (projects) the generated second display light L2 (real image V2) toward the windshield WS, which is a light-transmitting member, via the imaging optical system 2 (second optical path OP2) and the emission port 17 (step ST108). In this way, in the HUD device 1, which is capable of switching between displaying the virtual image V1 and the real image V2 and in which the multiple light sources 14 of the display 11 and the backlight 12 are shared by displaying the virtual image V1 and the real image V2, by controlling the power supplied to the backlight 12 to be increased when switching the display from the virtual image V1 to the real image V2, the difference in brightness when switching between displaying the virtual image V1 and the real image V2 can be reduced, and appropriate luminance and uniformity can be ensured for both the virtual image display and the real image display.

[0046] 5A and 5B show examples of light source lighting patterns of the plurality of light sources 14 mounted on the backlight 12 when the virtual image V1 of the HUD device 1 of this embodiment is displayed (FIG. 5A) and when the real image V2 is displayed (FIG. 5B). In FIGS. 5A and 5B, the light source mounting areas surrounded by dashed lines and marked "ON" are lit, and the light source mounting areas marked "OFF" are extinguished. In the lighting pattern of the light sources 14 when the virtual image V1 is displayed as shown in FIG. 5A, the light sources 14 arranged in two rows on each side of the long side (horizontal) edge of the rectangular light source circuit board 140 are extinguished (marked "OFF"), and the light sources 14 arranged between them are lit (marked "ON"). On the other hand, in the lighting pattern of the light sources 14 when the real image V2 is displayed as shown in FIG. 5B, all the light sources 14 are lit (marked "Hatched"). The brightness of each light source 14 in the lighting pattern of the light source 14 when the real image V1 shown in Figure 5(B) is displayed may be the same as when the virtual image V1 shown in Figure 5(A) is displayed, or may be brighter than when the virtual image V1 is displayed.

[0047] 6A and 6B show other examples of lighting patterns of the plurality of light sources 14 mounted on the backlight 12 when the HUD device 1 of this embodiment displays a virtual image V1 (FIG. 6A) and a real image V2 (FIG. 6B). In FIGS. 6A and 6B, the light source mounting areas surrounded by dashed lines and marked "ON" are lit, and the light source mounting areas marked "OFF" are extinguished. In the light source lighting pattern when a virtual image is displayed shown in FIG. 6A, the light sources 14 laid out in two rows on each side of the edge of the rectangular light source circuit board 140 in the long side direction (horizontal direction) are extinguished (denoted as "OFF"), and the light sources 14 laid out between them are lit (denoted as "ON"). On the other hand, in the lighting pattern when a real image is displayed shown in FIG. 6B, the light sources 14 laid out in the mounting area in the bottom row in the short side direction (vertical direction) of the rectangular light source circuit board 140 are extinguished (denoted as "OFF"), and the light sources 14 laid out in the other areas are lit (denoted as "ON"). The light source 14 laid out in the mounting area in the bottom row of FIG. 6(B) may be turned off as a measure against stray light.

[0048] (Effects of the embodiment) As described above, the head-up display device of this embodiment is, for example, as shown in FIG. 1, a HUD device 1 that has an outlet 17 and emits display light L from the outlet 17 toward a light-transmitting member (windshield WS), thereby allowing a virtual image V1 and a real image V2 of the display image represented by the display light L to be viewed. The HUD device 1 includes a display 11, a backlight 12 including a plurality of light sources 14, a first reflecting member 22 having a first polarization state and a second polarization state whose transmittance differs depending on the polarization state, and a second reflecting member 23 that reflects the display light L1 that has passed through the first reflecting member 22, wherein the first display light L1 in the first polarization state is emitted along a first optical path OP1 where it is reflected by the surface of the first reflecting member 22 to form a virtual image V1, and the second display light L2 in the second polarization state is emitted along a second optical path OP2 where it is reflected by the second reflecting member 23 to form a real image V2, and a control unit 13 that controls the polarization state and controls the turning on and off of each of the plurality of light sources 14 of the backlight 12. When displaying virtual image V1, control unit 13 controls at least some of the multiple light sources 14 of backlight 12 to be turned on, and when displaying real image V2, control unit 13 controls at least some of the multiple light sources 14 of backlight 12 to be turned on and to increase the power consumed by multiple light sources 14 of backlight 12 compared to when virtual image V2 is displayed.

[0049] The HUD device 1 of this embodiment includes a first reflecting member 22 having a first polarization state and a second polarization state whose transmittance differs depending on the polarization state, and a second reflecting member 23 that reflects the display light that has passed through the first reflecting member 22. The first display light L1 in the first polarization state is emitted along a first optical path OP1 that is reflected by the surface of the first reflecting member 22 to form a virtual image V1, and the second display light L2 in the second polarization state is transmitted through the first reflecting member 22 and reflected by the second reflecting member 23 to form a virtual image V2. The optical system has an imaging optical system 2 that emits light through a path OP2 and forms a real image V2, and a control unit 13 controls the polarization state of the imaging optical system 2 so that when a virtual image V1 is displayed, at least some of the multiple light sources 14 of the backlight 12 are controlled to be turned on, while when a real image V2 is displayed, at least some of the multiple light sources 14 of the backlight 12 are controlled to be turned on, and the power consumed by the multiple light sources 14 of the backlight 12 is controlled to be greater than when the virtual image V1 is displayed.

[0050] Here, if the multiple light sources 14 of the backlight 12 are implemented as, for example, LEDs, the control unit 13 can improve power efficiency by controlling the ON / OFF timing of each LED and the value of the current flowing through the LED, as well as controlling the voltage supplied to the backlight 12 by an LED drive circuit (e.g., the light source drive unit 133 in FIG. 2 ). In this way, in the HUD device 1 that can switch between displaying a virtual image V1 and a real image V2 and in which the multiple light sources 14 of the display unit 11 and the backlight 12 are shared between displaying the virtual image V1 and the real image V2, by controlling the power supplied to the backlight 12 to be increased when switching from displaying the virtual image V1 to displaying the real image V2, the difference in brightness when switching between the virtual image V1 and the real image V2 can be reduced, ensuring appropriate luminance and uniformity for both the virtual image display and the real image display. Furthermore, by reducing the difference in brightness (luminance difference) when switching from displaying the virtual image V1 to displaying the real image V2, the discomfort felt by the occupant DR, who is the viewer, can be reduced.

[0051] Furthermore, in the HUD device 1 of this embodiment, when switching the display from the virtual image V1 to the real image V2, the control unit 13 controls the value (current value) of the current flowing through the multiple light sources 14 (e.g., LEDs) of the backlight 12 to improve the brightness of the backlight 12, thereby making it possible to reduce (minimize) the difference in brightness between the respective displays without increasing the lighting area of ​​the multiple light sources 14 of the backlight 12. In particular, since the brightness can be increased when the real image V2 is displayed, it is possible to ensure appropriate brightness and uniformity for both the virtual image V1 display and the real image V2 display.

[0052] Furthermore, in the HUD device 1 of this embodiment, when switching the display from the virtual image V1 to the real image V2, the control unit 13 can reduce (minimize) the difference in brightness between the respective displays by increasing the number (lighting area) of the light sources 14 that are turned on among the backlight 12 that has a plurality of light sources 14 mounted therein. In particular, since the brightness can be increased when the real image V2 is displayed, appropriate brightness and uniformity can be ensured for both the virtual image V1 display and the real image V2 display.

[0053] Furthermore, in the HUD device 1 of this embodiment, when switching the display from the virtual image V1 to the real image V2, the control unit 13 controls the value (current value) of the current flowing through the multiple light sources 14 (e.g., LEDs) of the backlight 12 to improve the brightness of the backlight 12, and by increasing the number (lighting area) of the light sources 14 that are turned on among the multiple light sources 14 mounted in the backlight 12, the difference in brightness between the respective displays can be further reduced (minimized). In particular, since the brightness can be increased when the real image V2 is displayed, appropriate brightness and uniformity can be ensured for both the virtual image V1 display and the real image V2 display.

[0054] The control method for the head-up display device of the present embodiment includes, for example, as shown in FIG. 1, a backlight 12 including an outlet 17 and a plurality of light sources 14 (see FIG. 4), a display 11 that transmits illumination light emitted by the light sources 14 to generate a display image, a first reflecting member 22 having a first polarization state and a second polarization state whose transmittance differs depending on the polarization state, and a second reflecting member 23 that reflects first display light L1 that has transmitted through the first reflecting member 22, The control method for the HUD device 1 includes an imaging optical system 2 in which a first display light L1 in an optical state is emitted along a first optical path OP1 where it is reflected by the surface of a first reflecting member 22 to form a virtual image V1, and a second display light L2 in a second polarization state is transmitted through the first reflecting member 22 and emitted along a second optical path OP2 where it is reflected by a second reflecting member 23 to form a real image V2, and a control unit 13 that controls the polarization state and also controls the turning on and off of each of the multiple light sources 14 of the backlight 12. The control method includes, for example, as shown in FIG. 3, a step (ST102 or ST105) in which the control unit 13 controls the polarization state to switch the display light L to be emitted between display light L1 in a first polarization state or second display light L2 in a second polarization state; a step (ST104) in which the control unit 13 controls at least some of the multiple light sources 14 of the backlight 12 to be turned on when the first display light L1 in the first polarization state is emitted from the emission outlet 17 to form a virtual image V1; and a step (ST107) in which the control unit 13 controls at least some of the multiple light sources 14 of the backlight 12 to be turned on and to increase the power consumed by the multiple light sources 14 of the backlight 12 compared to when the virtual image V1 is formed when the control unit 13 emits second display light L2 in the second polarization state from the emission outlet 17 to form a real image V2.

[0055] According to the control method for the HUD device 1 of this embodiment, the control unit 13 controls the polarization state of the imaging optical system 2, which includes the first reflecting member 22 having a first polarization state and a second polarization state whose transmittance differs depending on the polarization state, and in which the first display light L1 in the first polarization state is emitted along a first optical path OP1 where it is reflected by the surface of the first reflecting member 22 to form a virtual image V1, and the display light L2 in the second polarization state is transmitted through the first reflecting member 22 and emitted along a second optical path OP2 where it is reflected by the second reflecting member 23 to form a real image V2. When emitting first display light L1 in a first polarization state to form a virtual image V1, at least some of the multiple light sources 14 of the backlight 12 are controlled to be turned on, while when emitting second display light L2 in a second polarization state to form a real image V2, at least some of the multiple light sources 14 of the backlight 12 are controlled to be turned on and the power consumed by the multiple light sources 14 of the backlight 12 is controlled to be greater than when emitting second display light L2 in the first polarization state to form a virtual image V1.

[0056] Therefore, when LEDs are implemented as the multiple light sources 14 of the backlight 12, for example, the control unit 13 controls the ON / OFF timing of each LED and the value of the current (current value) flowing through the LED, and also controls the voltage supplied to the backlight 12 by an LED drive circuit (for example, the light source drive unit 133 in FIG. 2 ), thereby improving power efficiency. In this way, in the HUD device 1 that is capable of switching between the virtual image V1 display and the real image V2 display and in which the multiple light sources 14 of the display unit 11 and the backlight 12 are shared by the virtual image V1 display and the real image V2 display, by controlling the power supplied to the backlight 12 to be increased when switching from the virtual image V1 display to the real image V2 display, the difference in brightness when switching between the virtual image V1 and the real image V2 display can be reduced, and appropriate luminance and uniformity can be ensured for both the virtual image V1 display and the real image V2 display. Furthermore, the difference in brightness (luminance difference) when switching the display from the virtual image V1 to the real image V2 is reduced, thereby suppressing the sense of discomfort felt by the occupant DR who is the viewer.

[0057] In the above-described embodiment, the windshield WS is used as the light-transmitting member, but a flat glass or a combiner may also be used.

[0058] The present invention is not limited to the above-described exemplary embodiments, and those skilled in the art will be able to easily modify the above-described exemplary embodiments to the extent that they fall within the scope of the claims. [Explanation of symbols]

[0059] REFERENCE SIGNS LIST 1 Head-up display device (HUD device), 2 Imaging optical system, 10 Image generation unit (PGU), 11 Display, 12 Backlight, 13 Control unit, 14 Light source, 17 Outlet, 20 Switch, 21 Lenticular lens, 22 First reflecting member, 23 First reflecting member, 24 Third reflecting unit material, 30... various devices, 111... display element, 112... switching element, 131... display control section, 132... display drive section, 133... light source drive section, 140... light source circuit board, V1... virtual image, V2... real image, L(L1, L2)... display light, L1... first display light, L2... second display light, OP1... first optical path, OP2... second optical path

Claims

1. A head-up display device has an exit port, and emits display light from the exit port toward a light-transmitting member, thereby allowing a virtual image and a real image of a display image represented by the display light to be visually recognized, the head-up display device including: a display; a backlight including a plurality of light sources; a first reflecting member having a first polarization state and a second polarization state whose transmittance differs depending on the polarization state; and a second reflecting member that reflects the display light that has passed through the first reflecting member, wherein the first display light in the first polarization state is emitted along a first optical path that is reflected by a surface of the first reflecting member to form the virtual image, and the second display light in the second polarization state is transmitted through the first reflecting member to form the virtual image. a control unit that controls the polarization state and controls the turning on and off of each of the plurality of light sources of the backlight, and when the virtual image is to be displayed, the control unit controls to turn on at least some of the plurality of light sources of the backlight, and when the real image is to be displayed, the control unit controls to turn on at least some of the plurality of light sources of the backlight and to increase the power consumed by the plurality of light sources of the backlight compared to when the virtual image is displayed.

2. The control unit 2. The head-up display device according to claim 1, wherein when the real image is displayed, a control is performed to increase a value of a current flowing through the plurality of light sources of the backlight.

3. The control unit 2. The head-up display device according to claim 1, wherein when the real image is displayed, control is performed to increase the number of light sources that are turned on among the plurality of light sources of the backlight.

4. The control unit 2. The head-up display device according to claim 1, wherein when the real image is displayed, control is performed to increase the value of the current flowing through the plurality of light sources of the backlight, and control is performed to increase the number of light sources that are turned on among the plurality of light sources of the backlight.

5. a control unit that controls the polarization states and controls turning on and off of each of the plurality of light sources of the backlight, the control unit comprising: an imaging optical system including: an exit port; a backlight including a plurality of light sources; a display that generates a display image by transmitting illumination light emitted by the light sources; a first reflecting member having a first polarization state and a second polarization state whose transmittance differs depending on the polarization state; and a second reflecting member that reflects the display light that has transmitted through the first reflecting member, the first display light in the first polarization state being emitted along a first optical path that is reflected by a surface of the first reflecting member to form a virtual image; and a control unit that controls the polarization states and controls turning on and off each of the plurality of light sources of the backlight, the control unit comprising: The control unit controlling the polarization state to switch the first display light to be emitted to display light in a first polarization state or the second display light in a second polarization state; The control unit a step of controlling the backlight so that at least a part of the plurality of light sources is turned on when the display light in the first polarization state is emitted from the emission outlet to form the virtual image; The control unit a step of turning on at least some of the plurality of light sources of the backlight when the second display light in the second polarization state is emitted from the emission outlet to form the real image, and performing control to increase the power consumed by the plurality of light sources of the backlight compared to when the virtual image is formed.

Images