Virtual image display device

Abstract

To provide a virtual image display device that prevents a reduction in display quality.SOLUTION: A HUD 10 as a virtual image display device causes a FWS 3 to reflect display light of an image to display a virtual image VRI. The HUD 10 comprises a polarizing plate 43 that transmits specific polarized light of the display light, and an image display control unit 61 that controls a display state of the image. The image display control unit 61 has a deterioration state determination unit 62 that determines a deterioration state of the polarizing plate 43, and a correction unit 63 that corrects the display state according to the deterioration state.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] TECHNICAL FIELD This disclosure relates to technology for displaying virtual images. [Background technology]

[0002] Display devices that display virtual images are known. The display device disclosed in Patent Document 1 is configured such that a reflective panel is provided in the optical system, and a portion of external light that enters the device is transmitted through the reflective panel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-71763 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology of Patent Document 1 reduces the amount of external light, such as sunlight, that enters the polarizer of a display panel. However, because some of the external light still enters the polarizer, the polarizer deteriorates more rapidly than when it was shipped. Therefore, there is concern that the deterioration of the polarizer will reduce the display quality of virtual images.

[0005] One of the purposes of the disclosure of this specification is to provide a virtual image display device that suppresses degradation of display quality. [Means for solving the problem]

[0006] One of the aspects disclosed herein is a virtual image display device that displays a virtual image (VRI) by reflecting display light of an image on a reflecting member (3), a polarizing plate (43) that transmits a specific polarized light of the display light; an image display control unit (61) that controls the display state of the image; The image display control unit a deterioration state determination unit (62) that determines the deterioration state of the polarizing plate; a correction unit (63) that corrects the display state according to the deterioration state; death, The polarizing plate is placed in a position where it is expected to be irradiated with sunlight, a timer (53) that counts time and stops counting the time at the time when it is estimated that the incidence of sunlight on the polarizing plate will be blocked; The deterioration state determination unit determines the deterioration state due to sunlight irradiation by referring to the timer. do. One of the disclosed aspects is a virtual image display device that displays a virtual image (VRI) by reflecting display light of an image on a reflecting member (3), a polarizing plate (43) that transmits a specific polarized light of the display light; an image display control unit (61) that controls the display state of the image; The image display control unit a deterioration state determination unit (62) that determines the deterioration state of the polarizing plate; a correction unit (63) that corrects the display state according to the deterioration state, The polarizing plate is placed in a position where it is expected to be irradiated with sunlight, The deterioration state assessment unit assesses the deterioration state due to sunlight irradiation by estimating the cumulative amount of sunlight irradiation on the polarizing plate from information regarding the hours of sunlight and information for identifying the positional relationship between the polarizing plate and the sun.

[0007] According to this aspect, the display state of the image is corrected in accordance with the deterioration state of the polarizing plate, and therefore, even if the polarizing plate deteriorates, the deterioration of the display quality of the virtual image displayed by the display light transmitted through the polarizing plate can be suppressed by the correction.

[0008] Note that the symbols in parentheses included in the claims, etc., are intended to exemplify the correspondence with the parts of the embodiments described below, and are not intended to limit the technical scope. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a state in which a HUD is mounted on a vehicle. [Figure 2] FIG. 1 is a diagram showing a schematic configuration of a HUD or the like. [Figure 3] FIG. [Figure 4] Cross-sectional view of line IV-IV in Figure 3. [Figure 5] FIG. 2 is a diagram showing the functional configuration of a control unit. [Figure 6] 10 is a graph conceptually showing a γ table. [Figure 7] Chromaticity diagram showing the change in the color reproduction range due to deterioration of the polarizing plate. [Figure 8] 10 is a flowchart showing an example of a correction process performed by a control unit. [Figure 9] FIG. 1 is a diagram showing a schematic configuration of a HUD or the like. [Figure 10] 10A and 10B are diagrams for explaining virtual division of a polarizing plate or a screen. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments will be described with reference to the drawings. Note that corresponding components in each embodiment are given the same reference numerals, and redundant description may be omitted. When only a portion of the configuration is described in each embodiment, the configuration of another embodiment described previously can be applied to the remaining portion of the configuration. Furthermore, in addition to the combinations of configurations explicitly stated in the description of each embodiment, configurations of several embodiments can also be partially combined together even if not explicitly stated, as long as there is no particular problem with the combination.

[0011] (First embodiment) As shown in FIG. 1 , the virtual image display device according to the first embodiment of the present disclosure is a head-up display (hereinafter referred to as HUD) 10. The HUD 10 is configured to be mounted on a vehicle 1. Here, the vehicle 1 is broadly interpreted to include various vehicles such as automobiles, railroad cars, aircraft, ships, and stationary game cabinets. In particular, the vehicle 1 in this embodiment is a four-wheeled automobile. In the following description, the directions of front, rear, up, down, left, and right are expressed based on the vehicle 1 on a horizontal plane HP.

[0012] The HUD 10 is installed on an instrument panel 2 of the vehicle 1. The HUD 10 projects display light toward a front windshield (hereinafter, referred to as FWS) 3 of the vehicle 1. As a result, the HUD 10 displays an image as a virtual image VRI that can be viewed by an occupant (e.g., a driver) of the vehicle 1. That is, the display light reflected by the FWS 3 reaches a visibility area EB set in the interior of the vehicle 1, allowing the occupant, whose eye point EP is positioned in the visibility area EB, to view various pieces of information.

[0013] The FWS 3 is formed into a translucent plate made of, for example, glass or synthetic resin, and is disposed above the instrument panel 2. The FWS 3 is disposed at an angle so that it moves away from the instrument panel 2 as it extends from the front to the rear. The FWS 3 has a reflective surface onto which the image display light from the HUD 10 is projected, formed into a smooth concave or flat surface. Therefore, the FWS 3 functions as a reflective member that reflects the display light. Through the FWS 3, the occupant can visually recognize the outside world view superimposed on the virtual image VRI. The FWS 3 has the property of transmitting external light such as sunlight, but may be configured to block external light other than visible light. For example, the FWS 3 may have a UV blocking function.

[0014] The display light does not have to be projected onto the FWS 3. For example, a light-transmitting, plate-shaped combiner may be installed in the interior of the vehicle 1 separately from the FWS 3, and the display light may be projected onto the combiner. In this case, the combiner functions as a reflective member.

[0015] The visible area EB is a spatial area that becomes visible to the occupants of the vehicle 1 when the virtual image VRI displayed by the HUD 10 satisfies a predetermined standard (for example, the entire virtual image VRI has a predetermined luminance or higher), and is also called an eye box. The visible area EB is typically set so as to overlap with the iris set in the vehicle 1. The iris is set in the shape of a virtual ellipsoid based on an eye range that statistically represents the spatial distribution of the eye points EP of the occupants in the interior of the vehicle 1.

[0016] As shown in FIGS. 1 and 2, the HUD 10 includes a housing 11, an optical system 20, a light path changing mechanism 30, a display 40, and a control unit 50.

[0017] The housing 11 is installed inside the instrument panel 2. The housing 11 has a hollow box shape and accommodates other elements of the HUD 10. The housing 11 has a window 11a at an upper portion facing the FWS 3. The window 11a may be physically open, or may be covered with a dustproof sheet that allows display light to pass through.

[0018] The optical system 20 guides the display light emitted from the display 40 to the FWS 3. The optical system 20 may be a magnifying optical system that magnifies the virtual image VRI relative to the image on the display 40. The optical system 20 forms an optical path for the display light from the display 40 through the FWS 3 to the visible area EB. The optical system 20 includes mirrors such as a first mirror and a second mirror. The first mirror is formed into a rectangular plate shape from, for example, synthetic resin or glass. The first mirror and the second mirror have reflective surfaces formed by, for example, depositing a reflective film made of aluminum on their surfaces. The reflective surfaces are formed into a smooth flat surface, a smooth concave surface, a smooth convex surface, or the like.

[0019] Here, of the first mirror and the second mirror, the mirror arranged on the FSW side in the optical path may be capable of changing the orientation of its reflecting surface by the optical path changing mechanism 30. The optical path changing mechanism 30 may be configured to include a motor such as a stepping motor that rotates the mirror, for example.

[0020] The display 40 shown in Fig. 3 is, for example, a transmissive liquid crystal display. The display 40 is formed by housing a dot-matrix TFT (Thin Film Transistor) liquid crystal panel 41 and a backlight in a casing. The display 40 displays an image on the screen 44 by transmitting illumination through the backlight onto a screen 44 of the liquid crystal panel 41, and projects display light that contributes to the display through the screen 44.

[0021] The display 40 is connected to the control unit 50 via a flexible cable 45. In addition, a substrate on which a drive circuit for driving the liquid crystal panel 41 is mounted is arranged on the flexible cable 45.

[0022] Liquid crystal panel 41 is formed by laminating multiple functional layers, as shown in the cross section of Fig. 4. For example, the multiple functional layers are arranged in order from the backlight side: HC layer 41a, TAC layer 41b, PVA polarizer layer 41c, TAC layer 41d, glass layer 41e, glass layer 41f, viewing angle compensation layer 41g, TAC layer 41h, PVA polarizer layer 41i, TAC layer 41j, and HC layer 41k.

[0023] The HC layers 41a and 41k are abbreviations for hard coat layers. The HC layers 41a and 41k may be made of, for example, HC films. The HC layers 41a and 41k are provided as a pair at the outermost positions of the liquid crystal panel 41. The HC layers 41a and 41k have high hardness and function to protect the liquid crystal panel 41. The HC layers 41a and 41k have high light transmittance.

[0024] The TAC layers 41b, 41d, 41h, and 41j are abbreviations for triacetyl cellulose layers. The TAC layers 41b, 41d, 41h, and 41j may be made of, for example, TAC films, and are arranged to sandwich the corresponding PVA polarizer layers 41c and 41i from both sides. The TAC layers 41b, 41d, 41h, and 41j function as base materials for the PVA polarizer layers 41c and 41i and protect the PVA polarizer layers 41c and 41i. The TAC layers 41b, 41d, 41h, and 41j have high light transmittance.

[0025] The PVA polarizer layers 41c and 41i are abbreviations for polyvinyl alcohol polarizer layers. The PVA polarizer layers 41c and 41i are made of, for example, a PVA polarizing film. The PVA polarizing film is formed into a film in which the iodine molecules are aligned in the same direction by, for example, adding iodine to polyvinyl alcohol and stretching it. The PVA polarizer layers 41c and 41i have a transmission axis and an absorption axis that are substantially perpendicular to each other, depending on the alignment direction of the iodine molecules. The PVA polarizer layers 41c and 41i have the property of transmitting polarized light along the transmission axis and absorbing polarized light along the absorption axis.

[0026] The glass layers 41e and 41f include a highly translucent glass substrate and thin-film transistors or color filters formed on its surface. The glass layers 41e and 41f are arranged in pairs to sandwich the liquid crystal. The liquid crystal changes its orientation in response to the voltage applied to each pixel by the thin-film transistor. Depending on the orientation, the polarization direction of backlight passing through the liquid crystal can be rotated.

[0027] The pair of PVA polarizer layers 41c and 41i, which are arranged to sandwich the liquid crystal, are arranged with their transmission axes substantially perpendicular to each other, which makes it possible to control the transmittance of backlight through the liquid crystal panel 41 for each pixel according to the voltage applied to each pixel.

[0028] The viewing angle compensation layer 41g may be formed of, for example, a viewing angle compensation film, and improves the degradation of the viewing angle characteristics caused by the liquid crystal or PVA polarizer layers 41c and 41i.

[0029] Here, the PVA polarizer layer 41c and the pair of TAC layers 41b and 41d sandwiching it constitute a polarizing plate 42 that transmits specific polarized light and absorbs other polarized light. The PVA polarizer layer 41i and the pair of TAC layers 41h and 41j sandwiching it constitute a polarizing plate 43. The polarizing plates 42 and 43 tend to deteriorate in response to heat generation. For example, the deteriorated polarizing plates 42 and 43 exhibit a decrease in transmittance and a red discoloration.

[0030] In this embodiment, sunlight enters the interior of the HUD 10 through the FWS 3 and the window 11a, travels along an optical path opposite to that of the display light, and can reach the display 40. Therefore, of the pair of polarizing plates 42, 43 of the liquid crystal panel 41, the polarizing plate 43 located on the mirror side is positioned in a position where it is expected to be irradiated with sunlight. Such polarizing plate 43 generates heat in response to sunlight irradiation, and exhibits degradation characteristics in which degradation progresses.

[0031] According to experiments by the inventors, when polarizing plate 43 is irradiated with a xenon lamp simulating sunlight for 300 hours, the transmittance of polarizing plate 43 decreases by about 30% compared to the initial state. As a result, the chromaticity coordinates on the xy chromaticity diagram of the CIE 1931 color space of an image displayed using polarizing plate 43 change by about 0.03.

[0032] The control unit 50 is a unit that controls the virtual image display of the HUD 10. The control unit 50 may be stored inside the housing 11. The control unit 50 may be disposed outside the housing 11. The control unit 50 is capable of controlling the image display of the display device 40 and the light path changing mechanism 30. The control unit 50 includes a timer 53 and a computer 51.

[0033] The timer 53 is a circuit that counts time. The timer 53 may be set to 0, for example, before shipping. The timer 53 may be configured to continue counting time even when the control unit 50 is in a sleep state while mounted on the vehicle 1. The sleep state here refers to a state in which an operating clock signal is not supplied to the processor 51b (described later) and the functions of the control unit 50 are stopped.

[0034] Furthermore, the timer 53 of this embodiment is configured to stop or resume counting the time during the night when it is estimated that sunlight is blocked from irradiating the polarizing plate 43. Furthermore, the timer 53 is configured to stop or resume counting the time while the vehicle 1 is parked in a garage or the like where sunlight is blocked from irradiating the polarizing plate 43. Specifically, the timer 53 of this embodiment is configured to stop or resume counting the time in response to a signal from the solar radiation sensor 4. If the amount of light detected by the solar radiation sensor 4 exceeds a predetermined amount (if the amount of light is expected during the day), the timer 53 continues to count the time during that time. If the amount of light detected by the solar radiation sensor 4 is equal to or less than the predetermined amount (if the amount of light is expected during the night), the timer 53 stops counting the time during that time.

[0035] The solar radiation sensor 4 is mounted on, for example, the instrument panel 2 of the vehicle 1, and is positioned facing upward toward the FWS 3. The solar radiation sensor 4 includes a light receiving element such as a photodiode and a spectral filter that blocks unnecessary light other than sunlight wavelengths from among the light incident on the solar radiation sensor 4.

[0036] The computer 51 may have at least one memory 51a and one processor 51b. The memory 51a may be at least one type of non-tangible storage medium, such as a semiconductor memory, a magnetic medium, or an optical medium, that non-temporarily stores programs and data readable by the processor 51b. The memory 51a may further include a rewritable volatile storage medium, such as a random access memory (RAM). The processor 51b may include at least one type of core, such as a central processing unit (CPU), a graphics processing unit (GPU), or a reduced instruction set computer (RISC)-CPU. The control unit 50 may further include a circuit, such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC).

[0037] 5, the control unit 50 includes an image display control unit 61 that controls the display state of an image as a functional block realized by a processor 51b that executes a program. Here, the image display control unit 61 includes a deterioration state determination unit 62 and a correction unit 63.

[0038] The deterioration state determination unit 62 determines the deterioration state of the polarizing plate 43. Although the deterioration state determination unit 62 may directly inspect the deterioration state of the polarizing plate 43, in this embodiment, the deterioration state determination unit 62 indirectly estimates the deterioration state of the polarizing plate 43. The deterioration state determination unit 62 of this embodiment refers to the timer 53.

[0039] Specifically, the deterioration state determination unit 62 acquires the cumulative time counted by the timer 53. The deterioration state determination unit 62 estimates the deterioration state of the polarizing plate 43 based on the cumulative time. Here, the timer 53 is designed to operate in response to a signal from the solar radiation sensor 4, so that nighttime, time when the vehicle is in a garage, and the like are excluded from the time that contributes to deterioration. Therefore, with a simple configuration and processing, it is possible to improve the accuracy of determining the deterioration state.

[0040] The degradation state determination unit 62 provides the determination result to the correction unit 63. The determination result here may be a value that quantifies the degradation state. In this embodiment, the determination result may be the accumulated time itself acquired from the timer 53, in which case the degradation state determination unit 62 simply functions as an accumulated time acquisition unit.

[0041] The correction unit 63 corrects the display state of the image according to the result of the deterioration state determination. Specifically, the correction unit 63 corrects at least one of the luminance and display color of the image according to the deterioration state. The correction unit 63 of this embodiment refers to the correction table 71 to correct both the luminance and display color of the image.

[0042] In brightness tone correction, the correction unit 63 refers to a database of γ tables, for example, as a correction table 71 non-temporarily stored in the memory 51a. The database has a plurality of γ tables. The γ table is a lookup table used for γ (gamma) correction, and is used to reduce the computational processing load for applying gamma correction to each pixel. The γ table stores pairs of pre-correction brightness values ​​(e.g., referred to as gradations) and post-correction brightness values ​​(e.g., referred to as brightness) in an array. The correspondence between the brightness values ​​before and after correction is based on a γ curve.

[0043] A plurality of γ tables are prepared in advance based on an estimate of the change in brightness of the virtual image VRI perceived by the occupant due to the progression of deterioration of the polarizing plate 43. For example, as shown in FIG. 6, tables with different γ values, such as γ = 2.1, 2.2, and 2.3, are prepared. The total number of γ tables prepared may be two or three. A large number of γ tables, such as 50 to 100, may be prepared by setting the γ value in small increments, such as 0.1.

[0044] The correction unit 63 selects one of the multiple γ tables to be used for the entire image, depending on the result of determining the deterioration state of the polarizing plate 43. This selection can be achieved by previously setting tables that individually correspond to ranges of values ​​indicating the deterioration state. As the polarizing plate 43 deteriorates, the transmittance of the polarizing plate 43 decreases. Therefore, the correction unit 63 can be configured to select a table that gradually increases the γ value as the deterioration of the polarizing plate 43 progresses. In this way, one or both of the backlight and the liquid crystal panel 41 can be controlled so that the brightness increases as the transmittance of the polarizing plate 43 decreases.

[0045] In correcting the display color, the correction unit 63 corrects the display color based on the color gamuts (also called color spaces) CG0 and CG1 corresponding to the degradation state. As shown by the triangles in Figure 7, the color gamut CG1 corresponding to a degradation state where a certain degree of degradation has progressed changes from the color gamut CG0 corresponding to the initial state. Accordingly, even if the display color is controlled to have the same gradation, the actual display color displayed as a virtual image will change as degradation progresses.

[0046] Therefore, if it is determined that substantially the same color as in the initial state can be reproduced by correcting the color tone in the deteriorated state, the correction unit 63 corrects the color tone so that the same color as in the initial state can be reproduced. On the other hand, if it is determined that substantially the same color as in the initial state cannot be reproduced even if the color tone in the deteriorated state is corrected, the correction unit 63 corrects the color tone so that the color as close as possible to the initial state can be reproduced.

[0047] When correcting the display color, the correction unit 63 may refer to a database of chromaticity correction tables, such as correction table 71 non-temporarily stored in memory 51a. The chromaticity correction table may store the correspondence between the deterioration state and the amount of color correction. In this way, the correction unit 63 generates a video signal based on the correction result and outputs the video signal to the display device 40.

[0048] Next, an example of a correction method performed by the control unit 50 will be described with reference to the flowchart of Fig. 8. A series of processes shown in steps S11 to S13 is executed by at least one processor at a predetermined execution cycle or based on a predetermined trigger.

[0049] In S11, the deterioration state determining unit 62 refers to the timer 53 and determines the deterioration state of the polarizing plate 43. After the process of S11, the process proceeds to S12.

[0050] In S12, the correction unit 63 determines whether the deterioration of the polarizing plate 43 has progressed compared to the past. If the determination is Yes, the process proceeds to S13. If the determination is No, the correction unit 63 continues to use the past correction amount or the correction table 71, and ends the series of processes.

[0051] In S13, the correction unit 63 changes the correction table 71 to be adopted depending on the deterioration state. After S13, the series of processes ends.

[0052] According to the first embodiment described above, the display state of an image is corrected in accordance with the deterioration state of the polarizing plate 43. Therefore, even if the deterioration of the polarizing plate 43 progresses, the correction can suppress deterioration in the display quality of the virtual image VRI displayed by the display light transmitted through the polarizing plate 43.

[0053] Furthermore, according to the first embodiment, the brightness of the image displayed on the screen 44 is corrected. Therefore, it is possible to prevent the brightness of the virtual image VRI from decreasing and the visibility from deteriorating as the deterioration of the polarizing plate 43 progresses.

[0054] According to the first embodiment, the memory 51a serving as a storage medium stores a plurality of γ tables, and the γ table to be used is changed depending on the deterioration state. By selecting a γ table as the correction mode, the response characteristics of the gradation characteristics of the image are changed, so that the occurrence of a visual discomfort when the driver views the corrected display can be suppressed.

[0055] Furthermore, according to the first embodiment, the display color of the image displayed on the screen 44 is corrected. Therefore, it is possible to prevent the display color from changing from the originally intended color as the deterioration of the polarizing plate 43 progresses.

[0056] Furthermore, according to the first embodiment, the polarizing plate 43 is placed in a position where it is expected to be irradiated with sunlight. Then, the deterioration state due to sunlight irradiation is determined. Since the deterioration of the polarizing plate 43 in the HUD 10 is closely related to sunlight irradiation, the accuracy of determining the deterioration state of the polarizing plate 43 can be improved.

[0057] Furthermore, according to the first embodiment, timer 53 is provided as a timer that counts time and stops counting time at the time when it is estimated that sunlight will be blocked from entering polarizing plate 43. Then, the deterioration state is determined by referring to timer 53. Since the deterioration state of polarizing plate 43 is determined based on the actual time count result, it is possible to improve the accuracy of determining the deterioration state of polarizing plate 43.

[0058] (Second embodiment) As shown in Fig. 9, the second embodiment is a modification of the first embodiment. The second embodiment will be described, focusing on the differences from the first embodiment.

[0059] The deterioration state determination unit 62 of the second embodiment estimates the cumulative amount of sunlight irradiated onto the polarizing plate 43, and determines the deterioration state of the polarizing plate 43 from the estimation result. Specifically, the deterioration state determination unit 62 acquires various pieces of information from the locator 5 and the DCM (Data Communication Module) 6 that are communicably connected to the control unit 250.

[0060] Locator 5 performs composite positioning by combining multiple pieces of acquired information to generate highly accurate position information, etc., of vehicle 1. Locator 5 includes, for example, a GNSS (Global Navigation Satellite System) receiver 5a, an inertial sensor 5b, a high-accuracy map database (hereinafter referred to as "map DB") 5c, and a locator ECU 5d.

[0061] The GNSS receiver 5a receives positioning signals transmitted from multiple artificial satellites (positioning satellites). The inertial sensor 5b includes, for example, a gyro sensor and an acceleration sensor. The map DB 5c is mainly composed of non-volatile memory and stores map data with higher accuracy than that used in ordinary navigation.

[0062] The locator ECU 5d is mainly configured as a computer having at least one memory and one processor. The locator ECU 5d combines the positioning signal received by the GNSS receiver 5a, the measurement results of the inertial sensor 5b, and the vehicle speed information of the vehicle 1, and generates position information and direction information of the vehicle 1, and can provide this information to various devices of the vehicle 1, including the control unit 50 of the HUD 10.

[0063] The DCM 6 is a communication module mounted on the vehicle 1. The DCM 6 transmits and receives radio waves to and from base stations around the vehicle 1 via wireless communication in accordance with communication standards such as LTE (Long Term Evolution), 4G, and 5G. By mounting the DCM 6, the vehicle 1 becomes a connected car that can connect to the Internet.

[0064] The degradation state determination unit 62 acquires weather information through the DCM 6. The weather information may be acquired from the database of a meteorological organization of each country (for example, the Japan Meteorological Agency) or from the database of a weather information company. The weather information may include past weather information or current weather information. The weather information may include information on the hours of sunshine in the area where the vehicle 1 is located, and may also include information on the position of the sun.

[0065] The deterioration state determination unit 62 estimates the cumulative amount of sunlight irradiance on the polarizing plate 43 from the position and direction of the vehicle 1 acquired from the locator 5 and weather information acquired through the DCM 6. Specifically, the deterioration state determination unit 62 calculates the amount of sunlight irradiance incident on the HUD 10 or the polarizing plate 43 at each time from the sunshine hours in the area and the relationship between the position and direction of the vehicle 1 and the position of the sun.

[0066] At this time, it is preferable to take into account the attenuation of sunlight due to the UV-cutting function of the FWS 3. The reflectance of sunlight reflected by the FWS 3 also changes depending on the angle of incidence of sunlight on the FWS 3, so it is preferable to calculate the amount of irradiation taking into account the reflectance that depends on the angle.

[0067] Furthermore, if the deterioration state determination unit 62 determines from the map DB5c and the position information of the vehicle 1 that the vehicle 1 is located in a covered parking lot, garage, etc., and sunlight is not irradiating the polarizing plate 43, it may set the amount of irradiation for that time to 0 (exclude).

[0068] Furthermore, the deterioration state determining unit 62 accumulates the amount of irradiation for the number of years (usage period) that have passed since the polarizing plate 43. The deterioration state determining unit 62 determines the deterioration state based on the accumulated amount of irradiation, and provides the determination result to the correcting unit 63.

[0069] According to the second embodiment described above, information on the hours of sunlight and information for identifying the positional relationship between the polarizing plate 43 and the sun are acquired. Then, the deterioration state of the polarizing plate 43 is determined by estimating the cumulative amount of sunlight irradiated onto the polarizing plate 43. Therefore, the accuracy of determining the deterioration state of the polarizing plate 43 can be improved.

[0070] (Third embodiment) As shown in Fig. 10, the third embodiment is a modification of the first embodiment. The third embodiment will be described, focusing on the differences from the first embodiment.

[0071] Sunlight that enters the interior of the HUD 10 and travels along an optical path opposite to that of the display light to reach the display device 40 is concentrated by the optical system 20, which functions as a magnifying optical system. This concentration of sunlight accelerates the deterioration of the polarizing plate 43 of the display device 40. At this time, the degree of deterioration may differ between regions of the polarizing plate 43 due to unevenness in the amount of irradiation caused by the concentration of light or the parking environment, etc. For example, the deterioration of the region corresponding to the central portion of the polarizing plate 43 may progress faster than the deterioration of the region corresponding to the outer periphery of the polarizing plate 43.

[0072] Therefore, in the third embodiment, the polarizing plate 43 or the screen 44 is virtually divided into a plurality of regions, and different amounts of correction are applied to the plurality of regions.

[0073] 10, the polarizing plate 43 or the screen 44 may be virtually divided into nine regions A1 to A9. The deterioration state determining unit 62 then determines the deterioration state of each of the regions A1 to A9 individually. The correcting unit 63 performs individual corrections on each of the regions A1 to A9.

[0074] The correction unit 63 may also apply an optimal correction amount to each region by filtering to output a gradation effect so that the correction amount changes continuously on the screen 44. For example, if it is expected that the deterioration of the region corresponding to the central portion will progress faster than that of the peripheral portion, the correction amount may be changed radially from the central portion to the peripheral portion. The correction amount here may be a correction amount for luminance or a correction amount for chromaticity.

[0075] According to the third embodiment described above, a display 40 is provided that includes a polarizing plate 43 whose deterioration state is determined and that forms an image on a screen 44. Also provided is an optical system 20 that functions as a magnifying optical system that magnifies a virtual image VRI. In such a configuration, a bias in deterioration tendency may occur among multiple regions of the polarizing plate 43 due to the influence of the magnifying optical system. However, different correction amounts are applied among the multiple regions according to the bias in deterioration tendency, thereby making it possible to prevent a situation in which a biased deterioration in display quality occurs in the virtual image VRI.

[0076] (Other embodiments) Although multiple embodiments have been described above, the present disclosure should not be construed as being limited to those embodiments, and can be applied to various embodiments and combinations within the scope that does not deviate from the gist of the present disclosure.

[0077] In another embodiment, the brightness may be corrected by the correction unit 63, and the display color may be managed or adjusted by at least one of the user, the car dealer, and the vehicle inspection company.

[0078] In the first embodiment, the degradation state determining unit 62 may refer to a calendar date instead of the timer 53 and determine the degradation state based on the number of days that have passed since the product was shipped.

[0079] In the second embodiment, the degradation state determining unit 62 may refer to both meteorological information and the detection result of the solar radiation sensor 4 to improve the accuracy of calculating the amount of solar radiation.

[0080] In another embodiment, of the pair of polarizing plates 42, 43 provided on either side of the liquid crystal in the liquid crystal panel 41, the polarizing plate 42 arranged on the backlight side may have lower light resistance than the polarizing plate 43 arranged on the mirror side. By using an inexpensive polarizing plate 42 that is not expected to be irradiated with sunlight, procurement costs can be reduced.

[0081] In another embodiment, of the pair of polarizing plates 42, 43 provided to sandwich the liquid crystal in the liquid crystal panel 41, the polarizing plate 43 arranged on the mirror side may have a lower iodine density than the polarizing plate 42 arranged on the backlight side. By lowering the iodine density of the polarizing plate 43 arranged in a position where it is expected to be irradiated with sunlight, the rate at which deterioration progresses can be slowed down.

[0082] In other embodiments, the polarizing plate placed at a position expected to be irradiated with sunlight may be a polarizing plate other than polarizing plate 43 provided on liquid crystal panel 41. Specifically, the polarizing plate may be a polarizing plate placed on the optical path of HUD 10 to prevent damage to liquid crystal panel 41. As an example of this, a polarizing plate may be used for a dustproof sheet that covers window portion 11a of HUD 10.

[0083] The controller and methods described herein may be implemented by a special-purpose computer comprising a processor programmed to perform one or more functions embodied in a computer program. Alternatively, the apparatus and methods described herein may be implemented by special-purpose hardware logic circuitry. Alternatively, the apparatus and methods described herein may be implemented by one or more special-purpose computers comprising a processor executing a computer program in combination with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory storage medium.

[0084] (Disclosure of technical ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be written in a multiple dependent form, where the subsequent clause alternatively refers to the preceding clause. These multiple dependent clauses define multiple technical ideas.

[0085] <Technical philosophy 1> A virtual image display device that displays a virtual image (VRI) by reflecting display light of an image on a reflecting member (3), a polarizing plate (43) that transmits a specific polarized light of the display light; an image display control unit (61) that controls the display state of the image, The image display control unit a deterioration state determination unit (62) that determines the deterioration state of the polarizing plate; a correction unit (63) that corrects the display state in accordance with the deterioration state.

[0086] <Technical philosophy 2> a display (40) configured to include the polarizer or separate from the polarizer and to form the image on a screen (44); The virtual image display device according to Technical Idea 1, wherein the correction unit corrects the brightness of the image displayed on the screen.

[0087] <Technical philosophy 3> a storage medium (51a) storing a plurality of γ tables; The virtual image display device according to Technical Idea 2, wherein the correction unit changes the γ table to be used depending on the deterioration state.

[0088] <Technical philosophy 4> a display configured to include the polarizer or separately from the polarizer and to form the image on a screen; The virtual image display device according to any one of Technical Ideas 1 to 3, wherein the correction unit corrects a display color of the image displayed on the screen.

[0089] <Technical philosophy 5> The polarizing plate is disposed at a position where it is assumed that sunlight will be irradiated, The virtual image display device according to any one of Technical Ideas 1 to 4, wherein the deterioration state determining unit determines the deterioration state caused by irradiation with sunlight.

[0090] <Technical philosophy 6> a timer (53) that counts time and stops counting the time at a time when it is estimated that sunlight will be blocked from entering the polarizing plate; The virtual image display device according to Technical Idea 5, wherein the deterioration state determination unit determines the deterioration state by referring to the timer.

[0091] <Technical philosophy 7> The virtual image display device described in Technical Idea 5, wherein the deterioration state assessment unit assesses the deterioration state by estimating the cumulative amount of sunlight irradiated onto the polarizing plate from information regarding the hours of sunlight and information for identifying the positional relationship between the polarizing plate and the sun.

[0092] <Technical philosophy 8> a display including the polarizing plate and forming the image on a screen; and a magnifying optical system (20) that magnifies the virtual image, The virtual image display device described in any one of Technical Ideas 5 to 7, wherein the correction unit applies different amounts of correction between multiple areas (A1 to A9) of the polarizing plate depending on the bias in deterioration tendency due to the influence of the magnifying optical system between the multiple areas. [Explanation of symbols]

[0093] 3: FWS (reflecting member), 10: HUD (virtual image display device), 43: polarizing plate, 61: image display control unit, 62: deterioration state determination unit, 63: correction unit, VRI: virtual image

Claims

1. A virtual image display device that displays a virtual image (VRI) by reflecting display light of an image on a reflecting member (3), a polarizing plate (43) that transmits a specific polarized light of the display light; an image display control unit (61) that controls the display state of the image, The image display control unit a deterioration state determination unit (62) that determines the deterioration state of the polarizing plate; a correction unit (63) that corrects the display state in accordance with the deterioration state, The polarizing plate is disposed at a position where it is assumed that sunlight will be irradiated, The apparatus further includes a timer (53) that counts time and stops counting the time at a time when it is estimated that sunlight will be blocked from entering the polarizing plate, The deterioration state determination unit determines the deterioration state due to irradiation of sunlight by referring to the timer.

2. A virtual image display device that displays a virtual image (VRI) by reflecting display light of an image on a reflecting member (3), a polarizing plate (43) that transmits a specific polarized light of the display light; an image display control unit (61) that controls the display state of the image, The image display control unit a deterioration state determination unit (62) that determines the deterioration state of the polarizing plate; a correction unit (63) that corrects the display state in accordance with the deterioration state, The polarizing plate is disposed at a position where it is assumed that sunlight will be irradiated, The deterioration state assessment unit assesses the deterioration state due to sunlight irradiation by estimating the cumulative amount of sunlight irradiation on the polarizing plate from information regarding the hours of sunlight and information for identifying the positional relationship between the polarizing plate and the sun.

3. a display (40) configured to include the polarizer or separate from the polarizer and to form the image on a screen (44); The virtual image display device according to claim 1 , wherein the correction unit corrects the luminance of the image displayed on the screen.

4. Further provided is a storage medium (51a) storing a plurality of γ tables, The virtual image display device according to claim 3 , wherein the correction unit changes the γ table to be used depending on the deterioration state.

5. a display configured to include the polarizer or separately from the polarizer and to form the image on a screen; The virtual image display device according to claim 1 , wherein the correction unit corrects a display color of the image displayed on the screen.

6. a display including the polarizing plate and forming the image on a screen; and a magnifying optical system (20) for magnifying the virtual image, The virtual image display device according to claim 1 or 2, wherein the correction unit applies different correction amounts between the multiple regions (A1 to A9) of the polarizing plate depending on the bias in deterioration tendency due to the influence of the magnifying optical system between the multiple regions.

Images