WO2021200912A1

WO2021200912A1 - Head-up display

Info

Publication number: WO2021200912A1
Application number: PCT/JP2021/013479
Authority: WO
Inventors: 久敏丸岡
Original assignee: 日本精機株式会社
Priority date: 2020-03-30
Filing date: 2021-03-30
Publication date: 2021-10-07
Also published as: JPWO2021200912A1

Abstract

Provided is a head-up display having high display quality. A head-up display HUD comprises a display unit 1 for outputting display light PL representing an image, and a control unit for controlling the display unit 1, and causes the display light PL to be reflected on a windshield WS of a vehicle and causes a virtual image Vx of the display light PL to be recognized from an eye box EBx. The control unit corrects distortion of the virtual image Vx by deforming the image on the basis of a warping setting value WMx stored in a storage unit. The warping setting value WMx is not optimized for a center point EBx (1, 1) of the eye box EBx, and a statistical variation of evaluation values of virtual images Vx (0, 0), ... Vx (4, 4) recognized from a plurality of points EBx (0, 0), ... EBx (4, 4) in the eye box EBx is made less than a predetermined value.

Description

Head-up display

The present disclosure relates to distortion correction of a virtual image displayed by a head-up display mounted on a vehicle.

There is a conventional head-up display disclosed in Patent Document 1. This head-up display reflects the display light emitted from the display that displays the image on the reflector or the windshield of the vehicle, and displays a virtual image of the display light through the windshield. In such a head-up display, the virtual image is distorted in the process of reflecting the reflector and the windshield.

Therefore, the head-up display disclosed in Patent Document 1 has a distortion correction processing function called warping due to deformation of the image in order to correct the distortion of the virtual image described above.

Japanese Unexamined Patent Publication No. 2011-105306

However, since the warping setting value is determined based on the center point in the eyebox, the inventor of the present disclosure has a problem that the display quality of the head-up display deteriorates as the line of sight deviates from the center point in the eyebox. Recognized.

The present disclosure aims to provide a head-up display with high display quality in view of the above-mentioned problems.

The head-up display of the present disclosure is
A head-up display that includes a display unit that outputs display light that represents an image and a control unit that controls the display unit, and reflects the display light on the windshield of the vehicle so that a virtual image of the display light can be visually recognized from the eye box. There,
Equipped with a storage unit that stores warping setting values
The control unit deforms the image based on the warping set value to correct the distortion of the virtual image.
The warping set value is not optimized for the center point of the eyebox, and the statistical variation of the evaluation value of the virtual image visually recognized from a plurality of points in the eyebox is less than a predetermined value. ..

According to the present disclosure, it is possible to provide a head-up display with high display quality.

Schematic diagram of the configuration of the head-up display of the present disclosure The figure which shows the image before correction and the warping mesh Diagram showing virtual images corresponding to each viewpoint position in the eyebox Diagram showing the procedure for calculating the warping mesh

The head-up display of the present disclosure will be described with reference to the attached drawings 1-4. In each figure, the left-right direction of the vehicle is shown as the X direction, the vertical direction of the vehicle is shown as the Y direction, and the front-rear direction of the vehicle is shown as the Z direction. Further, in FIG. 1, the main ray of the display light PL is illustrated for easy visual understanding.

The head-up display HUD is an in-vehicle instrument that projects display light PL representing vehicle information (running speed, various vehicle warnings, route guidance information, etc.) onto the windshield WS of the vehicle and displays vehicle information by a virtual image of the display light PL. be. The passenger P of the vehicle can visually recognize the virtual image by visually recognizing the windshield WS from the inside of the eye box which is the area where the virtual image can be visually recognized.

The head-up display HUD includes a display unit 1 that outputs the display light PL, a reflection unit 2 that reflects the display light PL toward the windshield WS, a case 3, and a control circuit board.

The display unit 1 is, for example, an image display such as a liquid crystal display, an organic EL display, or a rear projection type projector. The display unit 1 displays an image that is controlled by the control circuit board and represents vehicle information, and outputs the display light PL from this image.

The reflection unit 2 is a concave mirror that can rotate around the rotation axis AX extending in the left-right direction (X direction in FIG. 1) of the vehicle.

The reflecting unit 2 is configured to be rotatable from the first angle to the nth (n is a natural number of 2 or more) angles. When the reflecting portion 2 is at the first angle, the virtual image visible region is located in the eye box EB1 at the first position, and the virtual image V1 can be visually recognized from the eye box EB1. Further, when the reflecting unit 2 is at the nth angle, the virtual image visible region is located in the eyebox EBn at the nth position, and the virtual image Vn can be visually recognized from the eyebox EBn. That is, by rotating the reflecting unit 2, the virtual image visible region can be moved in the vertical direction (Y direction in FIG. 2) of the vehicle within the range from the eyebox EB1 to the eyebox EBn, and the viewpoint of the passenger can be changed. The virtual image visible area can be adjusted according to the height.

When an adjustment instruction for the virtual image visible area is input to the control circuit board by an operating means such as a switch provided on the steering of the vehicle, the reflection unit 2 is controlled by the control circuit board to rotate, and the virtual image visible area is formed. Be adjusted.

Case 3 is a case that houses the display unit 1, the reflection unit 2, and the control circuit board. The case 3 is formed with an exit opening that emits the display light PL toward the windshield WS. The exit opening of the case 3 is covered with a translucent dustproof cover 31 such as an acrylic resin plate.

The control circuit board is a circuit board having an arithmetic integrated circuit (calculation unit) for controlling the display unit 1 and the reflection unit 2 and a non-volatile memory (storage unit) such as a flash memory.

(Distortion correction processing based on warping setting value)
The control circuit board performs a warping process that geometrically deforms the image displayed on the display unit 1 in order to correct the distortion of the virtual image caused by the curved shape of the windshield WS. In this warping process, each point OP of the mesh region obtained by dividing the uncorrected image OM in a grid pattern is deformed according to each point WP of the warping mesh (warping set value) WM. This warping mesh WM is stored in the non-volatile memory of the control circuit board. Specifically, each point OP (0,0) ... OP (4,4) of the mesh region obtained by dividing the uncorrected image OM into 16 grids, each point WP (0,0) of the warping mesh WM ... Corresponding to WP (4, 4), the image of each divided region of the uncorrected image OM is texture-mapped to each region of the warping mesh WM.

In the warping mesh WM of the control circuit board, one warping mesh is set at each angle from the first angle to the nth angle of the reflection unit 2. That is, one warping mesh WMx is uniquely set for the eyebox EBx in which the reflecting portion 2 is at the xth angle and the virtual image visible region is in the xth position.

Here, when the reflecting unit 2 is at the x-th angle and the image to be displayed on the display unit 1 is deformed by the warping mesh WMx corresponding to the eye box EBx, the image is visually recognized by the position of the viewpoint of the viewer in the eye box. The inventor of the present disclosure has recognized that the degree of distortion of the virtual image varies.

Specifically, the virtual image Vx (1,1) seen from the center point EBx (1,1) of the eyebox EBx and the points EBx (points EBx) at the four corners of the rectangle centered on the center point EBx (1,1). The inventor of the present disclosure has recognized that the degree of distortion of the virtual image Vx (0,0) ... Vx (2,2) seen from 0,0) ... EBx (2,2) is different.

Then, when one warping mesh WMx is uniquely set for the eyebox EBx in which the reflecting portion 2 is at the xth angle and the virtual image visible region is in the xth position, the viewpoint of the viewer in the eyebox EBx is set. The inventor of the present disclosure has recognized that if the degree of distortion of the virtual image visually recognized depending on the position varies widely, there is a problem that the display quality of the virtual image displayed by the head-up display HUD is lowered and the commercial value is lowered.

In order to solve this problem, a warping mesh WMx with a small variation in the degree of distortion of the virtual image visually recognized depending on the position of the viewpoint of the viewer in the eyebox EBx is calculated by the procedure described below.

(Procedure for calculating warping setting value)
The calculation procedure of the warping mesh WMx uniquely defined for the eye box EBx in which the reflecting portion 2 is at the x-th angle and the virtual image visible region is in the x-th position will be described below.

(First step S1: Setting of initial value of warping mesh WMx)
The warping mesh WMx that minimizes the distortion of the virtual image Vx (1,1) when visually recognized from the center point (1,1) of the eyebox EBx is set as the initial value. After setting, the process proceeds to the second step S2.

(Second step S2: Imaging of virtual image)
A virtual image when visually recognized from each point of the eye box EBx is imaged. Specifically, it was visually recognized from five points of the center point EBx (1,1) of the eyebox EBx and the points EBx (0,0) ... EBx (2,2) at the four corners of the rectangle centered on this point. Virtual image of time Vx (0,0) ... Vx (2,2) is imaged. After imaging, the process proceeds to the third step S3.

(Third step S3: Evaluation of virtual image)
An evaluation value for evaluating the display quality of each virtual image Vx (0,0) ... Vx (2,2) is calculated. This evaluation value is calculated based on the amount of rotation, the amount of enlargement / reduction, and the amount of translation of each virtual image Vx (0,0) ... Vx (2,2) with reference to the image OM before deformation. After the calculation, the process proceeds to the fourth step S4.

(Fourth step S4: Calculate the statistical variation in evaluation)
The statistical variation of the evaluation value calculated in the third step S3 is calculated. This statistical variation is, for example, the coefficient of variation (relative standard deviation) obtained by dividing the standard deviation by the arithmetic mean. The statistical variation may be variance or standard deviation, but from the viewpoint of treating head-up displays of different models with the same evaluation criteria, it is preferable to use a coefficient of variation expressed as a percentage. After the calculation, the process proceeds to the fifth step S5.

(Fifth step S5: Evaluation of calculated warping mesh)
The warping mesh WMx is evaluated from the coefficient of variation calculated in the fourth step S4, and if the evaluation is less than a predetermined level, it is determined that the warping mesh WMx needs to be adjusted. Specifically, it is determined that the warping mesh WMx needs to be adjusted when the coefficient of variation is 0.1 or more, and the process proceeds to the sixth step S6. When the coefficient of variation is less than 0.1, it is determined that the warping mesh WMx has little variation in the distortion of the virtual image and the display quality is high regardless of the position in the eyebox EBx, and the process proceeds to the seventh step S7.

(Sixth step S6: Adjustment of warping mesh)
The warping mesh WMx that minimizes the distortion of the virtual image Vx (1,1) when visually recognized from a certain point EBx (a, b) in the eyebox EBx is recalculated. Specifically, the warping mesh WMx is recalculated by setting the point moved by a predetermined distance toward the point in the eyebox EBx having the worst evaluation value calculated in the third step S3 as the point EBx (a, b). .. Alternatively, the points EBx (a, b) may be calculated from the evaluation value calculated in the third step S3 and the statistical variation of the evaluation calculated in the fourth step S4. After recalculating the warping mesh WMx, the process proceeds to the second step S2.

(7th step S7: determination of warping mesh)
As the warping mesh of the eyebox EBx in which the reflecting portion 2 is at the xth angle and the virtual image visible region is in the xth position, the warping mesh WMx having a coefficient of variation of less than 0.1 in the fifth step S5 is adopted. .. The adopted warping mesh WMx is stored in the non-volatile memory of the control circuit board as a warping mesh corresponding to the xth angle of the reflection unit 2.

The procedure of the first step S1 to the seventh step S7 described above is executed for each of the eyeboxes EB1 to EBn.

With such a configuration, it is possible to provide a head-up display having high display quality with little variation in the degree of distortion of the virtual image visually recognized depending on the position of the viewpoint of the viewer in the eye box.

The head-up display HUD of the present disclosure may be modified as follows.

In calculating the warping mesh WMx, it may be calculated by an evolutionary algorithm such as a genetic algorithm. Alternatively, it may be calculated by multiple regression analysis from parameters such as the curvature of the reflecting mirror 2 and the curvature of the windshield at the position where the display light PL that changes depending on the angle of the reflecting mirror 2 is incident.

HUD ... Head-up display 1 ... Display 2 ... Reflector OM ... Image before deformation WM ... Warping mesh (warping set value)
PL ... Main ray of display light WS ... Windshield EB1-EBn ... Eyebox V1-Vn ... Virtual image

Claims

A head-up display that includes a display unit that outputs display light that represents an image and a control unit that controls the display unit, and reflects the display light on the windshield of the vehicle so that a virtual image of the display light can be visually recognized from the eye box. There,
Equipped with a storage unit that stores warping setting values
The control unit deforms the image based on the warping set value to correct the distortion of the virtual image.
The warping set value is not optimized for the center point of the eyebox, and the statistical variation of the evaluation value of the virtual image visually recognized from a plurality of points in the eyebox is less than a predetermined value. ,
A head-up display that features that.
The evaluation value is calculated based on the amount of rotation, the amount of enlargement / reduction, and the amount of translation of the virtual image based on the image before deformation.
The head-up display according to claim 1.
A rotatable reflector that reflects the display light to the windshield
The storage unit stores a plurality of the warping set values corresponding to the rotation positions of the reflector, and stores the warping set values.
The control unit deforms the image based on the warping set value corresponding to the rotation position of the reflection unit to correct the distortion of the virtual image.
The head-up display according to claim 1.