Image display system, moving body, image display method, and program

An image display system includes: an image projection unit that projects and displays an image on a display target for a moving body; a posture angle calculation unit that calculates a posture angle for the moving body on the basis of chronological data for acceleration detection values for the acceleration of the moving body in a prescribed time period; and a display control unit that controls the display position at which the image is projected and displayed on the display target, in accordance with the posture angle calculated by the posture angle calculation unit. The acceleration detection values include bi-directional components. The posture angle calculation unit excludes acceleration detection values from the chronological data used when calculating the posture angle, said acceleration detection values being included in an exclusion time period which has a ratio for the bidirectional components, in the prescribed time period, that is outside a prescribed range.

TECHNICAL FIELD

The present disclosure relates to an image display system, a moving body, an image display method and a program. More specifically, the present disclosure relates to an image display system that displays an image by projecting the image to a display object, a moving body including the image display system, an image display method and a program.

BACKGROUND ART

PTL 1 discloses a head-up display device mounted on a vehicle. This head-up display device displays information from an image display unit by projecting it onto the front shield of a vehicle. As a result, the information from the image display unit is superimposed in the field of view of the observer. This head-up display device calculates the attitude angle of the vehicle by detecting the acceleration of the vehicle (moving object) described above, and corrects the display position of the superimposed image according to the attitude angle.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

However, the acceleration of a vehicle may fluctuate significantly due to the disturbances that the vehicle is subjected to while driving. Therefore, the attitude angle of the vehicle cannot be calculated accurately. Therefore, the information from the image display unit cannot be accurately corrected according to the attitude angle of the vehicle.

The present disclosure provides an image display system, a moving body, an image display method and a program that can accurately calculate the attitude angle of a moving body.

Solution to Problem

An image display system according to an aspect of the present disclosure is configured to be mounted in a moving body, the image display system including: an image projection part configured to display an image by projecting the image to a display object of the moving body; an attitude angle calculation section configured to calculate an attitude angle of the moving body on a basis of time-series data of an acceleration detection value of an acceleration of the moving body in a predetermined period; and a display control section configured to control a position where the image is displayed and projected at the display object in accordance with the attitude angle calculated by the attitude angle calculation section. The acceleration detection value includes components of two directions. The attitude angle calculation section excludes the acceleration detection value included in an exclusion period in which a ratio of the components of two directions is outside a predetermined range in the predetermined period, from the time-series data used for calculation of the attitude angle.

An image display system according to an aspect of the present disclosure is configured to be mounted in a moving body, the image display system including: an image projection part configured to display an image by projecting the image to a display object of the moving body; an attitude angle calculation section configured to calculate an attitude angle of the moving body on a basis of time-series data of an acceleration detection value of an acceleration of the moving body in a predetermined period; and a display control section configured to control a position where the image is displayed and projected at the display object in accordance with the attitude angle calculated by the attitude angle calculation section. The attitude angle calculation section excludes the acceleration detection value included in an exclusion period in which an angular velocity detection value of an angular velocity of the moving body is outside a predetermined range, from the time-series data used for calculation of the attitude angle.

A moving body according to an aspect of the present disclosure includes: the above-mentioned image display system; and a moving body main body in which the image display system is mounted. The display object is a windshield of the moving body main body.

An image display method according to an aspect of the present disclosure is a method of controlling an image display system configured to be mounted in a moving body, the method including: an image projection process of displaying an image by projecting the image to a display object of the moving body; an attitude angle calculation process of calculating an attitude angle of the moving body on a basis of time-series data of an acceleration detection value of an acceleration of the moving body in a predetermined period; and a display control process of controlling a position where the image is displayed and projected at the display object in accordance with the attitude angle calculated by the attitude angle calculation process. The acceleration detection value includes components of two directions. The attitude angle calculation process excludes the acceleration detection value included in an exclusion period in which a ratio of the components of two directions is outside a predetermined range in the predetermined period, from the time-series data used for calculation of the attitude angle.

An image display method according to an aspect of the present disclosure is a method of controlling an image display system configured to be mounted in a moving body, the method including: an image projection process of displaying an image by projecting the image to a display object of the moving body; an attitude angle calculation process of calculating an attitude angle of the moving body on a basis of time-series data of an acceleration detection value of an acceleration of the moving body in a predetermined period; and a display control process of controlling a position where the image is displayed and projected at the display object in accordance with the attitude angle calculated by the attitude angle calculation process. The attitude angle calculation process excludes the acceleration detection value included in an exclusion period in which an angular velocity detection value of an angular velocity of the moving body is outside a predetermined range, from the time-series data used for calculation of the attitude angle.

A program according to an aspect of the present disclosure is configured to cause a computer system to execute the above-mentioned image display method.

Advantageous Effects of Invention

The present disclosure provides an effect of more accurately calculating the attitude angle of the image projection part.

DESCRIPTION OF EMBODIMENTS

Overview

As illustrated inFIG.1andFIG.2, for example, image display system10according to the present embodiment is a head-up display (HUD) provided in automobile100as a moving body. Specifically, moving body100includes a moving body main body, and image display system10provided in the moving body main body.

This image display system10is installed in the interior of automobile100so as to project an image to front shield101(windshield) of automobile100from below. In the example illustrated inFIG.2, image display system10is disposed in dashboard102below front shield101. When an image is projected to front shield101from image display system10, the image displayed on front shield101as a display object is visually recognized by user200(driver).

With this image display system10, user200visually recognizes virtual image300projected in object space400set in front of automobile100(outside the vehicle) through front shield101. Here, “virtual image” means an image that is formed like an actual object with divergent light beams of light emitted from image display system10diverging at a display object such as front shield101. Thus, as illustrated inFIG.3, the user200driving automobile100can see virtual image300projected by image display system10in a superimposed manner on the real space spreading in front of automobile100. Thus, with image display system10, for example, it is possible to display various drive assisting information such as vehicle speed information, navigation information, pedestrian information, forward vehicle information, lane deviation information, and vehicle condition information, as virtual image300to be visually recognized by user200. In this manner, user200can visually acquire the drive assisting information by only slightly moving the line of sight from the state where user200is directing the line of sight toward the front side of front shield101.

In image display system10according to the present embodiment, virtual image300formed in object space400includes at least virtual images of two types, first virtual image301and second virtual image302. Here, the “first virtual image” is, for example, information representing a travelling direction of automobile100as navigation information, and can, for example, present arrows indicating right turn or left turn on road surface600. First virtual image301of this type is an image that is displayed using an augmented reality (AR) technique, and is displayed in a superimposed manner at a specific position in the real scenery (such as road surface600, the building, the region around vehicle, and the pedestrian) as viewed from user200. Second virtual image302is, for example, vehicle speed information, and can, for example, present a current travelling speed (vehicle speed) of automobile100. In the example illustrated inFIG.3, first virtual image301represents an arrow indicating “left turn” on a T-junction in front of automobile100as an example. Second virtual image302represents information “50 km/h” as an example.

In image display system10, virtual image300formed in object space400is formed on virtual plane501that intersects optical axis500of image display system10. In the present embodiment, optical axis500extends along road surface600in front of automobile100in object space400in front of automobile100. Further, virtual plane501where virtual image300is formed is approximately perpendicular to road surface600. For example, in the case where road surface600is a horizontal surface, virtual image300is displayed along the vertical surface.

In this case, image display system10according to the present embodiment includes image projection part30and main body part1.

Image projection part30forms image700and projects and displays the formed image700on front shield101to thereby project virtual image300corresponding to image700in object space400. Image projection part30includes image forming part2and projection part3.

Image forming part2includes display surface20, and forms image700on display surface20(seeFIG.8). Image forming part2projects the formed image on projection part3using output light. Projection part3projects, to front shield101, the image projected from image forming part2to thereby project virtual image300corresponding to image700in object space400.

The above-described image forming part2and projection part3are mounted in main body part1. In the state where this main body part1is mounted in automobile100, the attitude of main body part1changes together with the attitude of automobile100due to the load of automobile100, for example. Note that since image projection part30is mounted in main body part1, the attitude of image projection part30is the same as the attitude of main body part1. Therefore, the attitude of main body part1is also the attitude of image projection part30.

To be more specific, for example, when automobile100is tilted forward such as when passengers are in the driver's seat and the front passenger seat, main body part1is also tilted forward; whereas when it is tilted rearward such as when a passenger is in the rear seat or when a load is put in the trunk, main body part1is also tilted rearward. When the attitude of main body part1of image display system10(i.e., the attitude angle of image projection part30) changes, the position of virtual image300projected by this image display system10in object space400also changes. As such, in the case of first virtual image301, for example, when automobile100is tilted forward or tilted rearward, it may be displayed in a superimposed manner at a position shifted from the specific position where it should be originally superimposed in the real scenery as viewed from user200.

In view of this, image display system10according to the present embodiment further includes position correction section4for correcting the display position of virtual image300. Position correction section4changes the display position of virtual image300relative to main body part1(i.e., moving body100) on the basis of the attitude angle of main body part1(i.e., the attitude angle of moving body100). The attitude angle of main body part1is, for example, the inclination of the vertical axis of main body part1with respect to the vertical axis orthogonal to the road surface.

In this manner, the display position of virtual image300is adjusted by adjusting the display position of image700at front shield101in accordance with the attitude angle of main body part1. Therefore, in the case of first virtual image301, for example, image display system10can display it in a superimposed manner at the specific position where it should be originally superimposed in the real scenery as viewed from user200even when automobile100is tilted forward or tilted rearward.

Configuration

As illustrated inFIG.1, image display system10according to the present embodiment includes main body part1, image projection part30, position correction section4, display control section51, and acceleration sensor52. Image projection part30includes image forming part2and projection part3.

Main body part1is composed of one housing, for example. When image forming part2and projection part3are housed in main body part1, image forming part2and projection part3are mounted in main body part1. In the present embodiment, the components (position correction section4and display control section51) other than image forming part2and projection part3are also mounted (housed) in main body part1. Main body part1is fixed in dashboard102of automobile100. It should be noted that the components (position correction section4and display control section51) other than image forming part2and projection part3may not be mounted in main body part1. In addition, main body part1may be composed of a plurality of housings. Alternatively, main body part1may not be a housing in the first place, and may be, for example, a frame, a plate member or the like.

Image projection part30forms image700and projects and displays the formed image700on front shield101to thereby project virtual image300corresponding to image700in object space400.

Image forming part2includes display surface20, and forms image700on display surface20. In the present embodiment, as an example, image forming part2includes liquid crystal panel21(LCD) and light source apparatus22as illustrated inFIG.1. Liquid crystal panel21is disposed in front of light source apparatus22. The front surface of liquid crystal panel21(the surface on the side opposite to light source apparatus22) constitutes display surface20. Light source apparatus22is used as a backlight of liquid crystal panel21. Light from light source apparatus22is transmitted through liquid crystal panel21from the rear side of liquid crystal panel21and output from image forming part2. Light source apparatus22is a planar light source that irradiates substantially the entire back surface of liquid crystal panel21with light using a solid light-emitting element such as a light-emitting diode, a laser diode or the like.

In this image forming part2, when light source apparatus22emits light in the state where image700is displayed at liquid crystal panel21, light output forward from light source apparatus22is transmitted through liquid crystal panel21and output forward from the front surface (display surface20) of liquid crystal panel21. At this time the light output forward from display surface20is light (image light) reflective of image700displayed on liquid crystal panel21. Accordingly, when display surface20is viewed from the front side, image700appears to be displayed on display surface20, and thus image700is formed on display surface20.

Note that while image forming part2includes liquid crystal panel201, such a configuration is not limitative. For example, image forming part2may be configured to form image700by scanning laser light from the back surface of display surface20of image forming part2.

Here, the vertical direction of display surface20corresponds to the vertical direction of image700, and the lateral direction of display surface20corresponds to the lateral direction of image700. The vertical direction of projected image700is a direction along the vertical direction of virtual image300(seeFIG.2) projected in object space400(seeFIG.2), i.e., the vertical direction in the field of view of user200(seeFIG.2). The lateral direction of projected image700is a direction along the lateral direction of virtual image300projected in object space400, i.e., the horizontal direction in the field of view of user200.

Projection part3projects and displays image700on front shield101using output light of image forming part2to thereby project virtual image300corresponding to image700in object space400.

As illustrated inFIG.1, projection part3includes first mirror31and second mirror32. First mirror31and second mirror32are disposed in the order of first mirror31and second mirror32on the light path of output light from image forming part2. More specifically, first mirror31is disposed in front of display surface20of image forming part2such that output light of image forming part2impinges on it. First mirror31reflects output light of image forming part2toward second mirror32. Second mirror32is disposed at a position (e.g., a position on the front lower side of first mirror31) where the output light of image forming part2reflected by first mirror31impinges. Second mirror32reflects upward (i.e., front shield101) the output light of image forming part2reflected by first mirror31. First mirror31is, for example, a convex mirror, and second mirror32is, for example, a concave mirror.

With this configuration, projection part3enlarges or reduces image700displayed on display surface20of image forming part2into an appropriate size, and projects it on front shield101as a projection image. As a result, virtual image300is displayed in object space400. Specifically, in the field of view of the user200driving automobile100, virtual image300of image700projected from image display system10is displayed in a superimposed manner on the real scene spreading in front of automobile100.

Display control section51controls image forming part2. Display control section51is composed of a microcomputer with a central processing unit (CPU) and a memory as main components, for example. In other words, display control section51is implemented as a computer including a CPU and a memory, and the computer functions as display control section51when the CPU executes a program stored in the memory. Here, the program is recorded in advance in the memory of display control section51, but may be provided using a telecommunication line such as the Internet, or a recording medium such as a memory card in which it is recorded.

Display control section51forms given image700on display surface20by controlling image forming part2. In addition, display control section51controls the display position of image700at display surface20. In this manner, display control section51controls the display position of image700at front shield101. As a result, the display position of virtual image300projected in object space400relative to main body part1can be controlled.

Through a software process, display control section51can display (draw) a given image content on liquid crystal panel21. In this manner, given image700is formed on display surface20and the display position of image700at display surface20is controlled. For example, when virtual image300(first virtual image301and second virtual image302) as illustrated inFIG.3is projected in object space400, the content of first virtual image301(such as the attitude and position of the arrow), and the content of second virtual image302(such as the vehicle speed) are determined at display control section51. Further, display control section51also determines the position of image700at the front surface of liquid crystal panel21, i.e., at display surface20. When the position of image700at display surface20changes, the display position of virtual image300relative to main body part1also changes.

Acceleration sensor52detects the acceleration (in the present embodiment, motion acceleration) (detection value G) that acts on automobile100. The motion acceleration is an acceleration that is generated at automobile100due to acceleration of travelling automobile100. That is, the motion acceleration is the acceleration that acts on automobile100, excluding the gravitational acceleration. The motion acceleration is generated in the direction opposite to the acceleration direction of automobile100, for example.

Note that in the present embodiment, acceleration sensor52directly detects the motion acceleration that acts on automobile100. It should be noted that in the case where acceleration sensor52detects the combined acceleration of the motion acceleration and gravitational acceleration of automobile100, it is possible to use, as detection value G of the motion acceleration of automobile100, a value obtained by dividing, in terms of vector, the value of the gravitational acceleration that acts on automobile100from the detection value of the combined acceleration. In this case, detection value G of acceleration sensor52in a stationary state may be used as the value of the gravitational acceleration that acts on automobile100.

Acceleration sensor52is, for example, a biaxial acceleration sensor, and detects the acceleration in the vertical axis Az direction (vertical direction) and the front-rear axis AX direction (front-rear direction) of automobile100. Note that the vertical axis Az and front-rear axis Ax are virtual axes fixed in automobile100. The front-rear axis AX direction is orthogonal to the vertical axis Az direction. For example, in the case where the attitude of automobile100traveling forward is not tilted in the front-rear direction with respect to road surface600, the motion acceleration that acts on automobile100acts only in the front-rear axis AX direction of automobile100. In view of this, detection value G of acceleration sensor52(i.e., the detection value of the motion acceleration) has only acceleration component Gx in the front-rear axis AX direction (seeFIG.4A). On the other hand, in the case where the attitude of automobile100traveling forward is tilted in, for example, the front-rear direction with respect to road surface600, the motion acceleration that acts on automobile100acts in both the vertical axis Az direction and the front-rear axis AX direction of automobile100. As such, detection value G has acceleration component Gz in the vertical axis Az direction and acceleration component Gx in the front-rear axis AX direction (seeFIG.4B).

Position correction section4calculates the attitude (or more specifically, the attitude angle) of main body part1on the basis of detection value G of acceleration sensor52, and changes the display position of image700at display surface20on the basis of the calculated attitude angle. In this manner, the display position of image700at front shield101changes. As a result, the display position of virtual image300relative to main body part1changes. In this manner, when the attitude of main body part1changes, image display system10changes the display position of image700at display surface20in accordance with the change, and thus image display system10can correct the display position of virtual image300. For example, for first virtual image301, it can be corrected at the specific position where it should be originally superimposed in the real scenery as viewed from user200, and can be displayed in a superimposed manner.

Position correction section4is composed of a microcomputer mainly composed of a CPU and a memory, for example. At least some function (e.g., correction section41) of position correction section4may share one microcomputer with display control section51.

Position correction section4includes correction section41and attitude angle calculation section43.

Attitude angle calculation section43calculates the attitude angle of main body part1on the basis of the time-series data of detection value G (acceleration detection value) of acceleration sensor52. More specifically, attitude angle calculation section43calculates the attitude angle of automobile100on the basis of the time-series data of detection value G of acceleration sensor52, and sets the calculated attitude angle as the attitude angle of main body part1. Specifically, main body part1is fixed to dashboard102such that the upper-lower direction, front-rear direction and horizontal direction of main body part1coincide with the upper-lower direction, front-rear direction and horizontal direction of automobile100. Thus, the attitude angle of main body part1coincides with the attitude angle of automobile100(vehicle body), and the attitude angle of main body part1can be calculated from the attitude angle of automobile100. Note that the attitude angle is an inclination of the vertical axis Az of automobile100from the Earth's vertical line.

In the present embodiment, acceleration sensor52is a biaxial (the vertical axis Az and front-rear axis Ax biaxial) acceleration sensor. As such, detection value G of acceleration sensor52includes acceleration component Gz in the vertical axis Az direction (vertical direction) and acceleration component Gx in the front-rear axis AX direction (front-rear direction). Attitude angle calculation section43calculates arctan (Gz/Gx) as attitude angle β (seeFIG.4).

On the basis of the attitude angle (i.e., the attitude angle of main body part1) calculated by attitude angle calculation section43, correction section41controls the display control section so as to change the display position of image700at display surface20. Through this control, the display position of virtual image300relative to main body part1is corrected in accordance with the attitude angle of main body part1. Correction section41controls display control section51so as to accommodate (reduce) the variation of the position of virtual image300in object space400due to the variation of the attitude angle of main body part1at least for first virtual image301, and changes the position of image700at display surface20.

More specifically, as illustrated inFIG.5AandFIG.5B, in the state where the attitude angle of automobile100is a reference angle (e.g., 0 degrees), correction section41displays virtual image300at a default display position without changing the display position of virtual image300(first virtual image301) relative to main body part1. Here, the default display position of first virtual image301is an approximate center portion of display region401, i.e., a position where optical axis500(seeFIG.5A) passes. Here, first virtual image301represents an arrow indicating “left turn” at a T-junction in front of automobile100. That is, in the field of view of user200, first virtual image301is displayed in a superimposed manner on the T-junction in a real scenery in display region401. In addition, second virtual image302is displayed at a lower left corner in display region401(seeFIG.5B).

On the other hand, as illustrated inFIG.6AandFIG.6B, when the attitude angle of automobile100is shifted from the reference angle and automobile100is tilted rearward for example, correction section41changes the display position of virtual image300(first virtual image301) relative to main body part1from the default display position. Specifically, in this state, display region401(X) moves upward and display region401(Y) is formed at a position shifted upward from display region401(X) in the field of view of user200as illustrated inFIG.6B. In this manner, at a default display position, first virtual image301(X) is displayed at an approximate center portion of display region401(Y). As such, in the field of view of user200, first virtual image301(X) is displayed in a superimposed manner at a position shifted forward from the T-junction in a real scenery. Note that inFIG.6AandFIG.6B, the region where virtual image300can be projected in object space400is displayed as display region401. In addition, a movement of display region401and first virtual image301is caused. In view of this, for discrimination, “X” is attached to the reference numerals of display region401and first virtual image301before the movement, and “Y” is attached to the reference numerals of display region401and first virtual image301after the movement.

In this case, correction section41changes the display position of virtual image300by changing the position of image700at display surface20. As such, as illustrated inFIG.6A, the display position of first virtual image301(X) relative to main body part1moves downward, and first virtual image301(Y) is displayed at a position shifted downward from first virtual image301(X) in display region401(Y). As a result, in the field of view of user200, as illustrated inFIG.6B, first virtual image301(Y) is displayed in a superimposed on manner on the T-junction in a real scenery in display region401(Y). In addition, second virtual image302is displayed at a position at a lower left corner in display region401(Y) (seeFIG.6B).

Details of Attitude Angle Calculation Section

As described above, in image display system10, the attitude angle of main body part1is calculated from the time-series data of detection value G (acceleration detection value) of acceleration sensor52, and the display position of image700at display surface20is corrected in accordance with the attitude angle. At this time, if automobile100is subjected to a disturbance, the attitude angle of main body part1cannot be correctly calculated. In view of this, image attitude angle calculation section43of display system10removes detection value G affected by the disturbance received by automobile100in the time-series data of detection value G of acceleration sensor52to calculate the attitude angle of main body part1. Note that “disturbance” is, for example, an external force that affects the attitude angle of automobile100, such as an upward force that is exerted when automobile100goes over a stone and the like on the road surface or a curb. A configuration of such an attitude angle calculation section is elaborated below.

Attitude angle calculation section43calculates the attitude angle of main body part1on the basis of the time-series data of detection value G of acceleration sensor52. More specifically, as illustrated inFIG.7, attitude angle calculation section43excludes detection value G (acceleration detection value) of acceleration sensor52included in out-of-threshold range period K1(exclusion period) in the operation period (predetermined period) of acceleration sensor52, from the time-series data of detection value G used in the calculation of the attitude angle of main body part1. That is, attitude angle calculation section43calculates the attitude angle of main body part1on the basis of the time-series data of detection value G included in in-threshold value range period K2.

Here, “operation period” is a period in which acceleration sensor52operates to detect the acceleration that acts on automobile100(in the present embodiment, motion acceleration), which may be the entire period or a part of the period during operation of acceleration sensor52. The “out-of-threshold range period K1” is a period in which the ratio W1(=Gz/Gx) of acceleration components Gz and Gx in two directions that constitute detection value G of acceleration sensor52falls outside threshold value range S1. In-threshold value range period K2is a period in which ratio W1falls within threshold value range S1. The “two directions” include the vertical axis Az direction (vertical direction) and the front-rear axis AX direction (front-rear direction) orthogonal to the vertical axis Az direction.

In this manner, attitude angle calculation section43improves the accuracy of the attitude angle of main body part1calculated at correction section41by excluding detection value G included in out-of-threshold range period K1in the operation period of acceleration sensor52from the time-series data of detection value G used in the calculation of the attitude angle of main body part1. As a result, at correction section41, the display position of image700at front shield101can be more accurately corrected.

FIG.8AandFIG.8Bare graphs illustrating time-series data of detection value G for a certain period of acceleration sensor52in the form of points in xz-coordinates. InFIG.8AandFIG.8B, the x axis is front-rear axis Ax of automobile100, and the z axis is the vertical axis Az of automobile100. As illustrated inFIG.8A, when automobile100is subjected to no disturbance, each point indicating detection value G is located on straight line L1with a constant gradient. It should be noted that as illustrated inFIG.8B, when automobile100is subjected to a disturbance, each point indicating detection value G is not only located on straight line L1, but also located at a position shifted from straight line L1.

Straight line L1indicates a distribution of detection value G in the case where automobile100is subjected to no disturbance. The gradient of straight line L1varies depending on the attitude angle of automobile100.FIG.8AandFIG.8Bassume that the attitude angle of automobile100being subjected to no disturbance is 1 degree. For example, depending on whether a passenger is present in the rear seat of automobile100, the attitude angle of automobile100differs, and the gradient of straight line L1also differs.

As illustrated inFIG.8A, through the use of the time-series data of detection value G located on straight line L1when calculating the attitude angle of automobile100, the attitude angle of automobile100can be accurately calculated. The graph ofFIG.8Bbecomes the graph as illustrated inFIG.8Awhen points affected by the disturbance is removed from the graph ofFIG.8B, and this removal corresponds to removal of detection value G detected in the out-of-threshold range period K1illustrated inFIG.7.

That is, detection value G in out-of-threshold range period K1where ratio W1is outside threshold value range S1inFIG.7is detection value G corresponding to points shifted from straight line L1ofFIG.8B. In view of this, the attitude angle of main body part1can be more accurately calculated by excluding detection value G in out-of-threshold range period K1from the time-series data of detection value G used for the calculation of the attitude angle of main body part1.

Threshold value range S1is determined in accordance with the state of automobile100. For example, detection values G detected in a certain interval are plotted at the interval on the xz-coordinates as illustrated inFIG.8Bon the basis of the time-series data of detection value G of acceleration sensor52, and a correlation straight line is determined based on the distribution of the plotted points. Then, assuming the correlation straight line as straight line L1, ratio W1may be calculated from the gradient of assumed straight line L1, and a given range centered on ratio W1may be set as threshold value range S1. For example, in the case where the value of ratio W1is 0.1, for example, threshold value range S1may be set within the range of 0.1±0.1, whereas in the case where the value of ratio W1is 0.5, for example, threshold value range S1may be set within the range of 0.5±0.1. In addition, for example, the average value of detection value G detected in a certain interval may be determined at the interval on the basis of detection value G of acceleration sensor52, and the given range centered on the average value may be set as threshold value range S1. For example, in the case where the average value is 0.3, threshold value range S1may be set to 0.3±0.1, for example.

Attitude angle calculation section43includes filter part431and calculation section main body432.

Filter part431removes detection value G included in out-of-threshold range period K1in the time-series data of detection value G of acceleration sensor52, and outputs only detection value G included in in-threshold value range period K2to calculation section main body432. More specifically, filter part431sets threshold value range S1in the above-described manner on the basis of the time-series data of detection value G of acceleration sensor52. Then, every time when the time-series data of detection value G of a certain operation period is acquired from acceleration sensor52, filter part431removes detection value G included in out-of-threshold range period K1in the certain operation period. Then, filter part431outputs detection value G included in in-threshold value range period K2to calculation section main body432.

Note that in the present embodiment, by statistically processing the time-series data of detection value G for each given operation time, out-of-threshold range period K1and in-threshold value range period K2are determined, detection value G in out-of-threshold range period K1is removed, and detection value G in in-threshold value range period K2is output to calculation section main body432. Alternatively, only detection value G within threshold value range S1may be output to calculation section main body432by determining in real time whether detection value G of acceleration sensor52is within threshold value range S1one by one.

On the basis of the time-series data of detection value G output from filter part431, calculation section main body432calculates the attitude angle of automobile100, and sets the calculated attitude angle as the attitude angle of main body part1.

In image display system10according to the present embodiment, attitude angle calculation section43excludes detection value G included in out-of-threshold range period K1in the operation period of acceleration sensor52from the time-series data of detection value G used in the calculation of the attitude angle of main body part1. Thus, the accuracy of the calculated attitude angle of main body part1can be improved. As a result, the display position of image700at front shield101can be more precisely corrected.

Modification of Embodiment 1

Embodiment 1 is merely one of various embodiments of the present invention. Embodiment 1 may be modified in various ways according to the design, etc., as long as objects of the invention can be achieved. Further, the aspects of according to Embodiment 1 is not limited to the embodiment using single image display system10. For example, the aspects according to Embodiment 1 may be embodied with a storage medium storing an image display method, a computer program, or a program and the like. Modifications described below may be appropriately combined in accordance with application.

The above-mentioned image display method is an image display method for controlling image display system10mounted in moving body100. This image display method includes an image projection process of projecting and displaying image700on display object101of moving body100, an attitude angle calculation process of calculating attitude angle β of moving body100on the basis of the time-series data of acceleration detection value G of the acceleration of moving body100in a predetermined period (the operation period of acceleration sensor52), and a display control process of controlling the display position for projecting and displaying image700to display object101in accordance with the attitude angle calculated by the attitude angle calculation process. Acceleration detection value G includes components of two directions, Gz and Gx. In the attitude angle calculation process, acceleration detection value G included in exclusion period K1where ratio W1of components of two directions is outside predetermined range S1in the predetermined period is excluded from the time-series data used for calculation of attitude angle.

Acceleration sensor52is a biaxial acceleration sensor in Embodiment 1, but may be a triaxial acceleration sensor. In this case, as illustrated inFIG.9, ratio W1used for the calculation at filter part431is a value obtained by dividing acceleration component Gz in detection value G of acceleration sensor52by acceleration component Gxy. Acceleration component Gxy is an acceleration component obtained by combining acceleration component Gx in the front-rear axis AX direction (front-rear direction) and acceleration component Gy in the horizontal axis Ay direction (horizontal direction) in detection value G in terms of vector. The horizontal axis Ay direction is orthogonal to both the vertical axis Az direction (vertical direction) and the front-rear axis AX direction (front-rear direction). In this case the above-mentioned two directions in the ratio of acceleration components Gxy and Gz of two directions that constitute detection value G are the vertical axis Az direction and the axis AxY direction of main body part1. The axis Axy is a direction along the acceleration component obtained by combining acceleration component Gx in the front-rear axis AX direction and acceleration component Gy in the horizontal axis Ay direction in detection value G in terms of vector. That is, the axis Axy is an axis along a straight line connecting the origin 0 and the point corresponding to acceleration component Gxy.

According to Modification 1, inclination in the front-rear direction and the inclination in the horizontal direction of the attitude of main body part1(i.e., automobile100) can be detected with acceleration sensor52. Thus, the display position of image700at front shield101can be more precisely corrected.

In Embodiment 1, as illustrated inFIG.10, additional periods K3and K4may be provided before and after out-of-threshold range period K1(exclusion period). In this case, in the operation period (predetermined period) of acceleration sensor52, filter part431excludes not only detection value G included in out-of-threshold range period K1, but also detection value G included in additional periods K3and K4. Then, filter part431outputs only the time-series data of the detection value (the detection value of acceleration sensor52) detected in remaining period K5to calculation section main body432. Note that period K5is a period obtained by excluding additional periods K3and K4from in-threshold value range period K2.

With this configuration, not only detection value G in out-of-threshold range period K1, but also detection value G in additional periods K3and K4can be excluded. Additional periods K3and K4are contiguous with out-of-threshold range period K1, and therefore it is highly possible that ratio W1corresponding to detection value G in additional periods K3and K4is a value close to the threshold value of threshold value range S1within threshold value range S1(predetermined range). By excluding such a detection value G in additional periods K3and K4, the attitude angle of main body part1(i.e., the attitude angle of automobile100) can be more accurately calculated.

The lengths of additional periods K3and K4are set to a fixed predetermined length in advance. It should be noted that the lengths of additional periods K3and K4may be changed in accordance with the length of out-of-threshold range period K1. For example, the lengths of additional periods K3and K4may be set to be lengthened as the length of out-of-threshold range period K1is lengthened. In the case where out-of-threshold range period K1is long, it is highly possible that ratio W1corresponding to detection value G in additional periods K3and K4maintains values near the threshold value of threshold value range S1for long periods of time. In view of this, by setting the lengths of additional periods K3and K4in accordance with the length of out-of-threshold range period K1, detection value G whose ratio W1has a value near the threshold value of threshold value range S1can be excluded from detection value G in in-threshold value range period K2. In this manner, the attitude angle of main body part1(i.e., the attitude angle of automobile100) can be more accurately calculated.

In addition, the length of additional period K3may be changed in accordance with the amount of variation of ratio W1acorresponding to the first detection value Ga in the order of time in detection value G in out-of-threshold range period K1. For example, the length of additional period K3may be set to be lengthened as the amount of variation of ratio W1aincreases. In addition, the length of additional period K4may be changed in accordance with the amount of variation of ratio W1bcorresponding to the last detection value Gb in the order of time in detection value G in out-of-threshold range period K1. For example, the length of additional period K4may be set to be lengthened as the amount of variation of ratio W1bincreases. Note that the amount of variation of ratios W1aand W1bis, for example, a deviation amount from the center value of threshold value range S1.

In the case where the amount of variation of ratios W1aand W1bis large, it is highly possible that ratio W1corresponding to detection value G in additional periods K3and K4maintains values near the threshold value of threshold value range S1for long periods of time. In view of this, by setting long lengths of additional periods K3and K4in accordance with the amount of variation of ratios W1aand W1b, detection value G whose ratio W1has a value near the threshold value of threshold value range S1can be excluded from detection value G in in-threshold value range period K2. In this manner, the attitude angle of main body part1(i.e., the attitude angle of automobile100) can be more accurately calculated.

Note that while additional periods K3and K4are provided both before and after out-of-threshold range period K1in the present modification, additional periods K3and K4may be provided at least one of before and after out-of-threshold range period K1.

Other Modifications

Image display system10is not limited to heads-up displays used in automobile100, but can also be applied to moving vehicles other than automobile100, such as motorcycles, trains, aircraft, construction machinery, and ships. Further, image display system10is not limited to moving bodies. For example, image display system10may be used in an amusement facility, a wearable terminal such as a head mounted display (HMD), a medical facility, or a stationary device. Image display system10may also be used as an electronic view finder, for example, incorporated into a digital camera or other equipment.

In comparison with Embodiment 1, Embodiment 2 differs in condition of out-of-threshold range period K1(exclusion period) of filter part431. More specifically, image display system10according to the present embodiment further includes angular velocity sensor53as illustrated inFIG.11. Angular velocity sensor53detects the angular velocity (i.e., pitch angle) around the horizontal axis of automobile100. That is, angular velocity sensor53detects the angular velocity around the horizontal axis of main body part1. Out-of-threshold range period K1of the present embodiment is a period in which angular velocity detection value Q1of angular velocity sensor53that detects the angular velocity (pitch angle) of main body part1is outside threshold value range S2in the operation period (predetermined period) of acceleration sensor52(seeFIG.12).

Specifically, attitude angle calculation section43of the present embodiment excludes acceleration detection value (acceleration sensor52detection value) G included in out-of-threshold range period K1in the operation period of acceleration sensor52from the time-series data of acceleration detection value G used in the calculation of the attitude angle of main body part1. Out-of-threshold range period K1is a period in which angular velocity detection value Q1of angular velocity sensor53that detects the angular velocity of main body part1(i.e., the angular velocity of automobile100) is outside threshold value range S2(predetermined range).

In the present embodiment, threshold value range S2may be set as a given range centered on an average value by determining the average value of angular velocity detection value Q1detected in a certain period at a certain interval on the basis of angular velocity detection value Q1of angular velocity sensor53.

According to the present embodiment, as in Embodiment 1, the accuracy of the attitude angle of main body part1calculated at correction section41can be improved. As a result, the display position of image700at front shield101can be more precisely corrected.

Note that Embodiment 1 and 2 may be combined. Specifically, attitude angle calculation section43may exclude acceleration detection value G included in the exclusion period in which ratio W1of components of two directions is outside predetermined range S1in the operation period (predetermined period) of acceleration sensor52from the time-series data of acceleration detection value G used for the calculation of attitude angle β, while further excluding the acceleration detection value included in the exclusion period in which angular velocity detection value Q1of the angular velocity of automobile100is outside predetermined range S2from the above-mentioned time-series data of detection value G used for the calculation of attitude angle β. With this configuration, the accuracy of calculated attitude angle β can be further improved.

Modification of Embodiment 2

Embodiment 2 is merely one of various embodiments of the present invention. Embodiment 2 may be modified in various ways according to the design, etc., as long as objects of the invention can be achieved. Further, the aspects of according to Embodiment 2 is not limited to the embodiment using single image display system. For example, the aspects of according to Embodiment 1 may be embodied using a storage medium storing an image display method, a computer program, or a program, and the like. Modifications described below may be appropriately combined.

The above-mentioned image display method is an image display method for controlling image display system10mounted in moving body100. This image display method includes an image projection process of projecting and displaying image700on display object101of moving body100, an attitude angle calculation process of calculating attitude angle β of moving body100on the basis of the time-series data of acceleration detection value G of the acceleration of moving body100in a predetermined period (the operation period of acceleration sensor52), and a display control process of controlling the display position for projecting and displaying image700to display object101in accordance with the attitude angle calculated by the attitude angle calculation process. Acceleration detection value G includes components of two directions, Gz and Gx. In the attitude angle calculation process, acceleration detection value G included in exclusion period K1where angular velocity detection value Q1of the angular velocity of moving body100is outside predetermined range Q2is excluded from the time-series data used for calculation of the attitude angle.

In Embodiment 2, angular velocity sensor53detects the angular velocity around the horizontal axis of automobile100(the pitch angle of automobile100). It should be noted that angular velocity sensor53may detect the angular velocity around the front-rear axis of automobile100(the roll angle of automobile100), or the angular velocity around the vertical axis (the yaw angle) of automobile100. In addition, angular velocity sensor53may detect at least one of the angular velocity around the vertical axis, the angular velocity around the front-rear axis and the angular velocity around the horizontal axis of automobile100. In the case where angular velocity sensor53detects angular velocities around two or more axes, the threshold value range is set for each acceleration around each axis.

In Embodiment 2, as in Embodiment 1, an additional period may be provided before and after out-of-threshold range period K1.

Conclusion

Image display system (10) according to a first aspect is configured to be mounted in moving body (100), image display system (10) including: image projection part (30) configured to display image (700) by projecting image (700) to display object (101) of moving body (100); an attitude angle calculation section (43) configured to calculate attitude angle (β) of moving body (100) on a basis of time-series data of acceleration detection value (G) of an acceleration of moving body (100) in a predetermined period; and display control section (51) configured to control a position where image (700) is displayed and projected at display object (101) in accordance with the attitude angle (β) calculated by attitude angle calculation section (43). Acceleration detection value (G) includes components (Gx, GZ) of two directions. Attitude angle calculation section (43) excludes acceleration detection value (G) included in exclusion period (K1) in which ratio (W1) of the components of two directions is outside predetermined range (S1) in the predetermined period, from the time-series data used for calculation of the attitude angle (β).

With this configuration, attitude angle calculation section (43) excludes acceleration detection value (G) included in exclusion period (K1), from the time-series data of acceleration detection value (G) used for calculation of attitude angle (β) of moving body (100). In this manner, the accuracy of calculated attitude angle (β) can be improved. As a result, the display position of image (700) at display object (101) can be more precisely corrected.

In image display system (10) according to a second aspect, in the first aspect, attitude angle calculation section (43) further excludes acceleration detection value (G) included in exclusion period (K1) in which an angular velocity detection value (Q1) of an angular velocity of moving body (100) is outside predetermined range (S2), from the time-series data used for calculation of the attitude angle (β).

With this configuration, the accuracy of calculated attitude angle (β) can be further improved.

In image display system (10) according to a third aspect, in the first or second aspect, the two directions include a vertical direction (Az axis direction) of moving body (100) and an orthogonal direction orthogonal to the vertical direction (Az axis direction).

With this configuration, with the time-series data of acceleration detection value (G), attitude angle (β) of moving body (100) can be more correctly detected. In this manner, the display position of image (700) at display object (101) can be more precisely corrected.

In image display system (10) according to a fourth aspect, in the third aspect, wherein the orthogonal direction is a front-rear direction (Ax axis direction) of moving body (100).

With this configuration, with the time-series data of acceleration detection value (G), the inclination of the attitude of moving body (100) in the front-rear direction can be detected.

In image display system (10) according to a fifth aspect, in any one of first to third aspects, the two directions are a vertical direction (Az axis direction) of moving body (100), and a direction along acceleration component (Gxy) obtained by combining acceleration component (Gx) in a front-rear direction (Ax axis direction) of moving body (100) and an acceleration component (Gy) in horizontal direction (Ay axis direction) of moving body (100) in acceleration detection value (G) in terms of vector.

With this configuration, with acceleration detection value (G), the inclination of the attitude of moving body (100) in the front-rear direction and the horizontal direction can be detected.

In image display system (10) according to a sixth aspect, in the second aspect, the angular velocity is at least one of an angular velocity around a vertical axis (Az axis direction) of moving body (100), an angular velocity around a front-rear axis (Ax axis direction) of moving body (100), and an angular velocity around a horizontal axis (Ay axis direction) of moving body (100).

With this configuration, with angular velocity detection value (Q1), at least one of the yaw angle, pitch angle, and roll angle of moving body (100) can be detected. In this manner, acceleration detection value (G) of a case where at least one of the yaw angle, pitch angle and roll angle of moving body (100) is significantly changed can be excluded. As a result, the display position of image (700) at display object (101) can be more precisely corrected.

In image display system (10) according to a seventh aspect, in any one of the aspects 1 to 6, attitude angle calculation section (43) excludes acceleration detection value (G) included in an additional period (K3, K4) contiguous with the exclusion period (K1), from the time-series data used for calculation of the attitude angle (β).

With this configuration, not only acceleration detection value (G) in exclusion period (K1), but also acceleration detection value (G) in additional period (K3, K4) can be excluded. Additional periods (K3, K4) are contiguous with exclusion period (K1), and therefore it is highly possible that ratio (W1) corresponding to acceleration detection value (G) in additional period (K3, K4) is a value close to the threshold value of predetermined range (S1) within predetermined range (S1). By excluding acceleration detection value (G) in additional period (K3, K4), attitude angle (β) of moving body (100) can be more accurately calculated.

In image display system (10) according to an eighth aspect, in the seventh aspect, the additional period (K3, K4) is provided at least at one of before and after the exclusion period (K1).

With this configuration, acceleration detection value (G) in additional period (K3, K4) provided at least one of before and after exclusion period (K1) can be excluded.

In image display system (10) according to a ninth aspect, in the seventh or eighth aspect, the longer the exclusion period (K1), the longer the additional period (K3, K4).

With this configuration, it is possible to achieve a setting in which the longer exclusion period (K1), the longer additional period (K3, K4). In the case where exclusion period (K1) is long, it is highly possible that ratio (W1) corresponding to acceleration detection value (G) in additional period (K3, K4) maintains a value near the threshold value of predetermined range (S1) for long periods of time. In view of this, by the setting in which the longer exclusion period (K1), the longer additional period (K3, K4), detection value (G) whose ratio (W1) has a value near the threshold value of predetermined range S1can be excluded from detection value (G) in in-threshold value range period (K2). In this manner, attitude angle (β) of moving body (100) can be more accurately calculated.

Image display system (10) according to a tenth aspect is configured to be mounted in moving body (100), image display system (10) including: image projection part (30) configured to display image (700) by projecting image (700) to display object (101) of moving body (100); an attitude angle calculation section (43) configured to calculate attitude angle (β) of moving body (100) on a basis of time-series data of acceleration detection value (G) of an acceleration of moving body (100) in a predetermined period; and display control section (51) configured to control a position where image (700) is displayed and projected at display object (101) in accordance with the attitude angle (β) calculated by attitude angle calculation section (43). Attitude angle calculation section (43) excludes acceleration detection value (G) included in exclusion period (K1) in which an angular velocity detection value (Q1) of an angular velocity of moving body (100) is outside a predetermined range (S2), from the time-series data used for calculation of the attitude angle (β).

With this configuration, attitude angle calculation section (43) excludes acceleration detection value (G) included in exclusion period (K1) where angular velocity of detection value (Q1) of the angular velocity of moving body (100) is outside predetermined range (S2), from the time-series data of acceleration detection value (G) used for calculation of attitude angle (β) of moving body (100). In this manner, the accuracy of calculated attitude angle (β) can be improved. As a result, the display position of image (700) at display object (101) can be more precisely corrected.

In image display system (10) according to a third aspect, in the first aspect, the two directions include a vertical direction (Az axis direction) of moving body (100) and an orthogonal direction orthogonal to the vertical direction (Az axis direction).

Moving body (100) according to an eleventh aspect includes: image display system (10) according to any one of the first to tenth aspects; and a moving body main body in which image display system (10) is mounted. Display object (101) is a windshield of the moving body main body.

With this configuration, moving body (100) including the image display system (10) can be provided.

An image display method according to a twelfth aspect is a method of controlling image display system (10) configured to be mounted in moving body (100), the method including: image (700) projection process of displaying image (700) by projecting image (700) to display object (101) of moving body (100); attitude angle (β) calculation process of calculating an attitude angle (β) of the moving body on a basis of time-series data of acceleration detection value (G) of an acceleration of moving body (100) in a predetermined period; and a display control process of controlling a position where image (700) is displayed and projected at display object (101) in accordance with the attitude angle (β) calculated by the attitude angle (β) calculation process, wherein acceleration detection value (G) includes components (Gx, GZ) of two directions. The attitude angle (β) calculation process excludes acceleration detection value (G) included in exclusion period (K1) in which ratio (W1) of components of two directions is outside predetermined range (S1) in the predetermined period, from the time-series data used for calculation of the attitude angle (β).

With this configuration, the accuracy of calculated attitude angle (β) can be improved. As a result, the display position of image (700) at display object (101) can be more precisely corrected.

An image display method according to a thirteenth aspect is a method of controlling image display system (10) configured to be mounted in moving body (100), the method including: image (700) projection process of displaying image (700) by projecting image (700) to display object (101) of moving body (100); attitude angle (β) calculation process of calculating an attitude angle (β) of the moving body on a basis of time-series data of acceleration detection value (G) of an acceleration of moving body (100) in a predetermined period; and a display control process of controlling a position where image (700) is displayed and projected at display object (101) in accordance with the attitude angle (β) calculated by the attitude angle (β) calculation process. The attitude angle (β) calculation process excludes acceleration detection value (G) included in exclusion period (K1) in which an angular velocity detection value (Q1) of an angular velocity of moving body (100) is outside a predetermined range (S2), from the time-series data used for calculation of the attitude angle (β).

With this configuration, the accuracy of calculated attitude angle (β) can be improved. As a result, the display position of image (700) at display object (101) can be more precisely corrected.

A program according to a fourteenth aspect is configured to cause a computer system to execute the image display method according to the twelfth or thirteenth aspect. With this configuration, it is possible to provide a program configured to cause a computer system to execute the image display method.

Overall Configuration of Display Device

FIG.13illustrates automobile1200including display device1100as head-up display (HUD). Display device1100is attached near the top surface of dashboard1220of automobile1200.

Display device1100projects light to region D10within the driver's view indicated with the dashed line at front shield1210. A part of the projected light is transmitted through front shield1210, while another part of the light is reflected by front shield1210. This reflected light travels toward the driver's eyes. The driver perceives the reflected light in his or her eyes as virtual image Vi, which looks like the image of an object on the other side of the front shield (outside automobile1200) against the background of the real object seen through the front shield1210.

FIG.14illustrates an example of region D10as a region to which light is projected by display device1100. As illustrated as the region surrounded by the broken lineFIG.14, region D10is located on the lower side on the driver's seat side of front shield1210. Display device1100attached to dashboard1220projects an image to front shield1210by projecting light to region D10as illustrated inFIG.13. In this manner, virtual image Vi that appears to be an image of an object located outside automobile1200as viewed from the driver is generated.

Note that an image projected to front shield1210may be perceived at a different distance from the driver in virtual image Vi depending on its vertical position in region D10. In the examples ofFIG.13andFIG.14for example, since region D10is located on the lower side than the driver's eye, the image on the lower side in region D10is perceived at a position closer to the driver in virtual image Vi, and an object located at a position on a higher side in the image projected to region D10is perceived as an object located father from the driver in virtual image Vi. The principle behind this perception is explained by a type of geometric perspective (vertical perspective).

FIG.15illustrates an example of a virtual image generated by display device1100, and an example of superimposition of that virtual image and a front scenery of automobile1200as viewed from the driver of traveling automobile1200.

In its entirety,FIG.15schematically illustrates a part of a scenery as viewed from the driver (not illustrated in the drawing) driving automobile1200. It should be noted that the frame of the broken line indicating region D10to which an image is projected from display device1100is illustrated for convenience of description of the present embodiment, and is not perceived as an entity by the driver. The reference numeral1200indicates a hood as a part of automobile1200. In addition, the arrow image indicated with the reference numeral V10is an AR (Augmented Reality) route that is an example of virtual image Vi generated by display device1100and perceived by the driver.

As illustrated inFIG.15, AR route V10as a virtual image is displayed in a superposed manner on the actual scenery in the driver's view. In practice, AR route V10is displayed in a superimposed manner on the road. In this manner, the driver is guided to travel on the belt-shaped region indicated by AR route V10.

Virtual Image Display Position Adjustment Function

FIG.16illustrates a configuration a main part for achieving a virtual image display position adjustment function provided in automobile1200of the present embodiment.

The automobile of the present embodiment includes projection part1101, irradiation part1102, distance measurement part1103, and projection position adjustment operation part1110.

With an input of image data such as an AR route, projection part1101displays a virtual image based on the image data at front shield1210. To be more specific, projection part1101includes a light source part, a scanning part, an optical system and the like. Projection part1101of the present embodiment can project reference line L2of a virtual image at front shield1210.

As illustrated inFIG.17, irradiation part1102irradiates the road in front of the own vehicle over the width direction of the road with visible light serving as reference line L1of the real image. In the present embodiment, irradiation part1102is implemented with a headlight having a projector function.

Distance measurement part1103measures the distance from the own vehicle to reference line L1. Distance measurement part1103is implemented with a visible light stereo camera or the like, for example. Note that distance measurement part1103is not limited to a visible light stereo camera, and may be various devices that can measure the distance to reference line L1. The information about the distance to reference line L1obtained by distance measurement part1103is input to projection part1101.

Projection part1101projects reference line L2of the virtual image at a vertical position corresponding to the distance represented by the information about the distance to reference line L1input from distance measurement part1103. For example, in the case where the distance to reference line L1measured by distance measurement part1103is 50 m, reference line L2of the virtual image that appears to overlap reference line L1of the real image at the position of 50 m is projected on front shield1210.

On the basis of the amount of the operation by the user, projection position adjustment operation part1110adjusts the position in the vertical direction of the virtual image projected to front shield1210by projection part1101. Projection position adjustment operation part1110is provided in a range where the driver's hands can reach even when the driver in a driving posture is viewing the real image and the virtual image from front shield1210. In the present embodiment, projection position adjustment operation part1110is implemented with steering switch1110a.

FIG.18illustrates a front view from a driver. From the driver, reference line L1of the real image from irradiation part1102can be seen. In addition, from the driver, reference line L2of the virtual image projected by projection part1101to front shield1210can be seen.

Reference line L2is projected to a position corresponding to reference line L1, and therefore reference line L2should appear to overlap reference line L1. However, when the attitude angle of automobile1200is changed from the basic attitude, reference line L2does not appear to overlap with reference line L1. For example, when a passenger is in the rear seat, automobile1200is slightly tilted rearward. Then, reference line L2of the virtual image moves upward in accordance with the rearward inclination of automobile1200.

In the present embodiment, the deviation of virtual image in the vertical direction due to the variation of the attitude angle of automobile1200can be manually corrected using projection position adjustment operation part1110.

FIG.19illustrates steering switch1110ahaving functions as projection position adjustment operation part1110. The left end of reference line L2vertically moves in accordance with a vertical operation at left steering switch1110a, and the right end of reference line L2vertically moves in accordance with a vertical operation at right steering switch1110a. In this manner, as illustrated inFIG.18, in the case where reference line L2is shifted in the upward direction than reference line L1, it suffices to operate left and right steering switches1110adownward to move reference line L2to a position overlapping reference line L1. In addition, since the movement amount of left and right ends of reference line L2in the vertical direction can be independently adjusted by the amount of operation of left and right steering switches1110a, adjustment can be performed such that reference line L2overlaps reference line L1even in the case where reference line L2is not parallel to reference line L1but is tilted and shifted with respect to reference line L1. That is, roll correction can be performed.

The above-described virtual image display position adjustment process is performed when a virtual image display position adjustment mode is set by the driver through an operation from an operation part (not illustrated) such as a predetermined operation button. For example, it is preferable that the driver set the virtual image display position adjustment mode at the start of driving to start the driving after the display position of the virtual image is adjusted. That is, since the attitude angle of the automobile changes in accordance with the seated position of the passenger, it is preferable to start the driving after the change in virtual image position due to the change in attitude angle is corrected with projection position adjustment operation part1110.

In addition, an adjustment position of a virtual image may be stored as a calibration value. In this manner, for example, when a passenger is seated in the same position as the case where correction using projection position adjustment operation part1110has been made, the virtual image projection position can be corrected by reading the calibration value stored in projection part1101. As a result, it is possible to reduce the number of manual adjustments with projection position adjustment operation part1110.

As described above, according to Embodiment 3, with projection part1101that projects a virtual image on a display medium such as front shield1210and projects reference line L2of the virtual image, distance measurement part1103that measures the distance to reference line L1included in a real image, and projection position adjustment operation part1110that can adjust the projection position of the virtual image in the vertical direction at the display medium on the basis of the operation amount by the user, a deviation of a displayed virtual image due to a change in the attitude angle of automobile1200can be precisely corrected.

Modifications of Embodiment 3

Embodiment 3 is only an example embodiment for implementing the invention, and the technical scope of the invention should not be interpreted in a limited manner by these examples. In other words, the present invention can be implemented in various ways to the extent that it does not deviate from its gist or its main features.

While irradiation part1102is provided and reference line L1of the real image is formed by irradiation part1102in Embodiment 3, the configuration of forming reference line L1using irradiation part1102is not limitative. For example, a stop line on the road and the like may be reference line L1. In this case, irradiation part1102may be omitted as illustrated inFIG.20. Note that “omit” does not mean that irradiation part1102is omitted from the automobile, but means that irradiation part1102is not used when adjusting the display position of the virtual image.

Note that while irradiation part1102and distance measurement part1103are separated from each other inFIG.16for convenience of illustration, a distance measurement part may be provided for the purpose of emitting light to a fixed distance in the case of a headlight having a projector function and the like. In this case, distance information may not be sent from distance measurement part1103to projection part1101. The reason for this is that it suffices to preliminarily set such that reference line L1is formed by irradiation part1102at a first distance (e.g., 50 m), and that projection part1101projects reference line L2at a position corresponding to the first distance.

Conclusion

As described in Embodiment 3, vehicle (1200) according to an aspect of the present disclosure is vehicle (1200) in which a display device configured to display a virtual image in an overlapping manner on an outside real image as viewed from the user is mounted, and vehicle (1200) includes: projection part (1101) configured to project the virtual image and project reference line (L2) of the virtual image on display medium (1210); distance measurement part (1103) configured to measure the distance to reference line (L1) included in the real image; and projection position adjustment operation part (1110) configured to adjust the projection position of the virtual image in the vertical direction at the display medium (1210) on the basis of the operation amount of the user.

In addition, in vehicle (1200) according to an aspect of the present disclosure, the projection part (1101) projects reference line (L2) of the virtual image at a vertical position corresponding to the distance measured by the distance measurement part (1103).

In addition, in vehicle (1200) according to an aspect of the present disclosure, the projection position adjusted by the projection position adjustment operation part (1110) is stored as a calibration value.

In addition, vehicle (1200) according to an aspect of the present disclosure further includes irradiation part (1102) configured to emit visible light serving as reference line (L1) of the real image to a road in front of the own vehicle.

In addition, in vehicle (1200) according to an aspect of the present disclosure, the irradiation part (1102) is a headlight having a projector function.

This application is entitled to and claims the benefit of Japanese Patent Application No. 2019-059468 and Japanese Patent Application No. 2019-059194 filed on Mar. 26, 2019, the disclosure each of which including the specification, drawings and abstract is incorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

The present invention is useful as a technique of eliminating a deviation of a displayed virtual image in a display device that displays a virtual image in an overlapping manner on an outside real image as viewed from the user, as with a head-up display.

REFERENCE SIGNS LIST