JP2018090120A - Video display device and video display method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video display device with high visibility and a video display method.SOLUTION: The video display device comprises: a video light projection part 120 that projects video light L1 corresponding to a video to be displayed as a virtual image which is visually recognized through a video projection surface; a concave mirror 130 which guides the video light L1 to the video projection surface; a state determining part 111 that determines a state of the video projection surface; and a video producing part 113 that produces a video so that visibility of the virtual image which is virtually recognized through the video projection surface is improved, on the basis of the determined state by the state determining part 111.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a video display device and a video display method.

  In recent years, so-called head-up displays have been developed as vehicle display devices. For example, Patent Literature 1 discloses a head-up display including first and second displays, a mirror, and an infrared camera. The mirror reflects the emission images of the first and second displays to the front window. The first display outputs data such as vehicle speed and engine speed, which are vehicle information, as an image. The second indicator outputs an image of a road ahead of the vehicle acquired by the infrared camera.

JP 2013-119268 A

  The head-up display of Patent Document 1 further includes a control unit and a raindrop sensor. When the value of the raindrop sensor exceeds a predetermined value, the control unit determines that the external field of view is poor. If the external field of view is poor, the control unit transmits display data based on the imaging data and the warning data to the second display. Thereby, the image of the vehicle information by the first display and the image of the road ahead of the vehicle by the second display are displayed together.

  On the other hand, if the value of the raindrop sensor is equal to or less than the predetermined value, the control unit determines that the external field of view is good. Then, transmission of display data to the second display is stopped. Thereby, only the vehicle information image by the first display is projected and displayed on the front window.

  In such a head-up display, a virtual image is visually recognized through the windshield. For example, a virtual image can be seen from the user (driver in a car) 3 to 5 meters ahead of the windshield. Therefore, the user focuses his eyes in front of the windshield 3 to 5 m. Because of the high transparency of the windshield, the eyes can be focused on the virtual image without being conscious of the windshield surface.

  However, raindrops adhere to the windshield when it rains. Normally, the wiper is operated during rain, but raindrops are attached during the wiper wiping operation. Raindrops are attached to the windshield surface, that is, before the position of the virtual image. For this reason, the windshield surface becomes conspicuous due to a decrease in permeability of the surface of the windshield or irregular reflection due to raindrops. Therefore, it is difficult to naturally focus the eyes on the distance of the virtual image, and there is a problem that visibility is deteriorated. For example, in order to see a virtual image, the eye may be focused on the windshield unintentionally even when trying to focus the eye on the virtual image, which causes fatigue.

  The present invention has been made in view of the above points, and an object thereof is to provide a video display device and a video display method with high visibility.

  An image display apparatus according to an aspect of the present invention includes an image light projection unit that projects image light corresponding to an image displayed as a virtual image that is visually recognized through an image projection surface, and an optical that guides the image light to the image projection surface. System, a state determination unit that determines the state of the video projection plane, and the determination result of the state determination unit, so that the visibility of the virtual image viewed through the video projection plane is improved. A video generation unit that generates a video.

  An image display method according to an aspect of the present invention includes a determination step of determining a state of an image projection surface that projects image light corresponding to an image displayed as a virtual image, and the determination of the image projection surface determined in the determination step. The video generation step for generating the video and the video generated in the video generation step so as to improve the visibility of the virtual image viewed through the video projection plane based on the state, And a projection step for projecting as image light.

  According to the present invention, it is possible to provide a video display device and a video display method with high visibility.

It is a figure which shows typically the motor vehicle carrying the head-up display apparatus. It is a side view which shows typically the structure of the head-up display apparatus installed on the dashboard. It is a side view which shows the structure of an imaging | video light projection part. It is a block diagram which shows the control structure of a head-up display apparatus. It is a table | surface which shows a response | compatibility with a state determination result and the permeability | transmittance of a windshield. It is a flowchart which shows a video display method. It is a figure which shows a response | compatibility with the transparency of a windshield, and the setting of an image display. It is a figure which shows the image | video which changed the whole display size. It is a figure which shows the image | video which changed the display icon size. It is a figure which shows the image | video which changed the brightness | luminance. It is a figure which shows the image | video which changed contrast. It is a figure which shows the image which carried out negative / positive inversion. It is a figure which shows the image | video which carried out 2 gradation. It is a figure which shows the image | video which changed RGB color.

Embodiment 1 FIG.
<overall structure>
Embodiments of the present invention will be described below with reference to the drawings. In the following description, the video display device according to the present embodiment is a head-up display mounted on an automobile. Further, description will be made assuming that the head-up display device is mounted on the dashboard of the automobile. The head-up display device may be attached to a vehicle other than an automobile or a vehicle other than the vehicle.

  FIG. 1 is a diagram schematically showing a configuration of a head-up display device 100 installed on a dashboard 10 of an automobile 1. In FIG. 1, the driver P is an observer. The head-up display device 100 emits image light L1 that has been generated and adjusted so as to display a desired image. The head-up display device 100 is disposed in front of the steering wheel 12.

  The image light L1 is emitted toward the windshield (front glass) 11. The windshield 11 transmits part of visible light and reflects part of it. Therefore, the windshield 11 reflects the image light L1 in the direction of the driver P. The image light L1 reflected by the windshield 11 enters the eyes of the driver P and forms an image on the retina. At the same time, external light L2 from the outside also enters the windshield 11. The external light L2 passes through the windshield 11 and enters the eyes of the driver P. Therefore, the external light L2 from the outside world and the video light L1 from the head-up display device 100 are overlaid (superimposed), and in the field of view of the driver P, an actual scene of the outside world and an image generated by the head-up display device 100 Will be visible at the same time. The head-up display device 100 displays a virtual image in front of the windshield 11. Thereby, even if the driver P is operating the steering wheel 12, the image can be viewed without dropping the line of sight.

  In the following description, the direction in which the head-up display device 100 is placed on the dashboard 10 of the automobile 1 will be described as a reference. That is, the direction of the automobile 1 is set as a reference direction. For example, the windshield 11 side is assumed to be the front and the driver P side is assumed to be the rear. Similarly, the description will be made with the roof side of the automobile 1 as the upper side, the ground side as the lower side, and the lateral direction (left-right direction) of the automobile 1 as the side.

(Head-up display device 100)
The configuration of the head-up display device 100 will be described in detail with reference to FIG. FIG. 2 is a side view schematically showing the configuration of the head-up display device 100. The head-up display device 100 includes an image light projection unit 120, a control unit 110, and a concave mirror 130.

  The image light projection unit 120 includes a projector that projects the image light L1. Specifically, the image light projection unit 120 includes a light source that generates light, a light modulation element that modulates light generated by the light source in accordance with a control signal, a projection lens that projects light, and the like. For example, a liquid crystal panel that is a light modulation element modulates light from a backlight light source. Alternatively, a scanning mirror such as a MEMS (Micro Electronics Mechanical System) mirror can be used as the light modulation element. In this case, the scanning mirror scans light from a light source such as a laser diode or an LED (Light Emitting Diode) according to the control signal.

  The video light projection unit 120 projects the video light L1 according to the control signal. Specifically, the video light projection unit 120 generates video light L1 corresponding to the projected video and emits it forward. A concave mirror 130 is disposed in front of the image light projection unit 120. Accordingly, the image light L1 from the image light projection unit 120 enters the concave mirror 130.

  The concave mirror 130 reflects the image light L1 from the image light projection unit 120 upward. Since the image light L1 reflected by the concave mirror 130 travels while expanding, the displayed image is enlarged. A windshield 11 is disposed above the concave mirror 130. Therefore, the image light L 1 reflected by the concave mirror 130 enters the windshield 11. The concave mirror 130 constitutes an optical system that guides the image light L1 to the windshield 11. The optical system that guides the image light L1 to the windshield 11 may include other optical components such as a lens and a folding mirror in addition to the concave mirror 130.

  The windshield 11 reflects a part of the incident video light L1 to display a virtual image. Therefore, as described above, the image light reflected by the windshield 11 enters the eyes of the observer P1.

  The control unit 110 is an information processing device having a processor, a memory, and the like, and comprehensively controls the entire head-up display device 100. The controller 110 generates a control signal based on display data input from the outside. Then, the control unit 110 outputs a control signal to the video light projection unit 120.

(Video light projection unit 120)
Next, the configuration of the image light projection unit 120 will be described with reference to FIG. FIG. 3 is a diagram illustrating a configuration of the image light projection unit 120. The image light projection unit 120 includes a light source 121, a light tunnel 122, a Fresnel lens 123, a diffusion plate 124, and a display element 125.

  The light source 121 is an LED (Light Emitting Diode) or the like and emits light. The light enters the light tunnel 122 from the light source 121. The light tunnel 122 is a light guide member having a reflective surface inside, and spreads light from the light source 121 so that light is incident on almost the entire surface of the display element 125. That is, the light tunnel 122 converts light from the LED into planar light. The light that has passed through the light tunnel 122 enters the Fresnel lens 123.

  The Fresnel lens 123 refracts the light emitted from the light tunnel 122. The light that has passed through the Fresnel lens 123 enters the diffusion plate 124. The diffusion plate 124 diffuses light. The light that has passed through the diffusion plate 124 enters the display element 125.

  The display element 125 is a light modulation element such as a liquid crystal panel. The display element 125 is, for example, a transmissive liquid crystal panel, and includes a plurality of pixels arranged in a matrix. Each pixel is controlled according to a control signal. Therefore, the display element 125 modulates light according to the control signal from the control unit 110. Specifically, the display element 125 controls the transmittance for each pixel in accordance with a control signal including gradation data. The light that has passed through the display element 125 becomes video light L1 corresponding to the control signal. Accordingly, the video light projection unit 120 can generate the video light L1 for forming a desired image.

  The image light projection unit 120 is not limited to the one using a transmissive liquid crystal panel, and may use another light modulation element such as a reflective liquid crystal panel or a MEMS mirror. Furthermore, the image light projection unit 120 may include other optical components such as a projection lens.

(Control configuration)
Next, the control configuration of the head-up display device 100 will be described with reference to FIG. FIG. 4 is a block diagram illustrating a control configuration of the head-up display device 100. The control unit 110 includes a state determination unit 111, a display data acquisition unit 112, a video generation unit 113, and a projection control unit 114.

  The display data acquisition unit 112 acquires display data from an external device (not shown). The external device generates display data to be displayed on the head-up display device 100 and outputs the display data to the head-up display device 100. For example, the external device is a car navigation device, another device connected via a CAN (Control Area Network), or the like. The external device may be an external terminal such as a smartphone or a tablet terminal. The display data may be stored in a storage unit (not shown) of the head-up display 100.

  The display data acquisition unit 112 acquires, for example, traveling direction information (right turn, left turn, straight ahead, etc.), distance information to the destination, and the like from the navigation device. The display data acquisition unit 112 acquires travel speed information and the like of the automobile 1 from the control device of the automobile 1 via the CAN. The display data acquisition unit 112 acquires incoming / outgoing information about the telephone function and the mail function from an external terminal. When the external terminal has a navigation application, the display data acquisition unit 112 acquires travel direction information from the navigation application, distance information to the destination, and the like from the external terminal. The display data acquisition unit 112 may acquire these pieces of information as digital data indicating a numerical value, a character string, or the like, or may be acquired as digital data constituting an image. Furthermore, the video may include a captured image captured by a side camera or a rear camera.

  The video generation unit 113 generates a video based on the display data acquired by the display data acquisition unit 112. Then, the projection control unit 114 generates a control signal corresponding to the display video generated by the video generation unit 113. The projection control unit 114 outputs the generated control signal to the light source 121 and the display element 125 of the video light projection unit 120.

  As described above, the video light projection unit 120 emits the video light L1 modulated according to the control signal. Specifically, the light source 121 generates light having a luminance corresponding to a control signal from the projection control unit 114. The display element 125 modulates light from the light source 121. Thereby, the image light L1 corresponding to the display data is projected from the image light projection unit 120. The image light L1 is projected onto the windshield 11 through the concave mirror 130. The windshield 11 serves as an image projection surface.

  The control unit 110 is connected to the state detection unit 160 or can acquire information from the state detection unit 160. The state detection unit 160 detects the state of the windshield 11. That is, the state detection unit 160 detects the permeability of the windshield 11. Specifically, the state detection unit 160 detects whether or not raindrops are attached to the windshield 11. When raindrops are attached, the permeability of the windshield 11 is lowered. Note that the state detection unit 160 may acquire information according to the amount of raindrops attached to the windshield 11. Then, the state detection unit 160 outputs a detection signal corresponding to the detection result to the control unit 110.

  For example, as the state detection unit 160, a water droplet adhesion sensor using an infrared sensor can be used. The water droplet adhesion sensor includes an infrared emitting portion and a light receiving portion on the vehicle interior side of the windshield 11, and detects rainfall based on the infrared return rate. For example, if raindrops are attached to the windshield 11, the infrared ray is diffusely reflected, and the return rate of the infrared ray is lowered. Therefore, the state detection unit 160 can detect the presence / absence of raindrops and the amount of raindrops using the water droplet adhesion sensor.

  Alternatively, the state detection unit 160 may detect the state of the windshield 11 by a wiper operation. Whether or not raindrops have adhered can be detected depending on whether or not the vehicle wiper is operating. Furthermore, information according to the amount of raindrops can be acquired by the intermittent period of the wiper operation. When the wiper operation is used, the state detection unit 160 detects the state based on a signal from CAN or the like.

  And the state determination part 111 determines the state of the windshield 11 based on the detection signal from the state detection part 160. FIG. Then, the state determination unit 111 outputs a determination signal indicating the determination result to the video generation unit 113. The video generation unit 113 generates a video based on the determination result.

  Specifically, the state determination unit 111 determines that the permeability of the windshield 11 is reduced as the amount of raindrops increases. FIG. 5 shows the relationship between the result of the state detection by the state detection unit 160 and the transparency. In FIG. 5, two examples of the state detection unit 160 are a water droplet adhesion sensor and a wiper operation. In FIG. 5, the state detection unit 160 detects the state of the windshield 11 in three stages. That is, the state detection unit 160 evaluates the degree of decrease in the permeability of the windshield 11 in three stages of “none”, “small”, and “large”.

  When the state detection unit 160 uses a water droplet adhesion sensor, the state determination unit 111 determines the state of the windshield 11 based on a detection signal from the water droplet adhesion sensor. For example, the return rate of infrared rays decreases as the amount of raindrops increases. Therefore, the state detection unit 160 can detect the amount of raindrops as the infrared return rate decreases. When no raindrop is detected, the state determination unit 111 determines that there is no decrease in permeability. That is, it is not raining and raindrops (water droplets) are not attached to the windshield 11. In this case, since the state detection unit 160 does not detect raindrops, the permeability does not decrease. Further, when the detected amount of raindrop is larger than a predetermined threshold value, it is considered that the decrease in permeability is large. On the other hand, the state detection unit 160 detects raindrops, but when the detected water droplet amount is smaller than the threshold value, the state determination unit 111 determines that the decrease in permeability is small.

  When the state detection unit 160 uses the wiper operation, the state determination unit 111 determines the state of the windshield 11 based on an operation signal indicating the wiper operation. When the wiper operation is non-operating or MIST, the state determination unit 111 determines that there is no decrease in transparency. For example, when raindrops are not attached, the driver P does not operate the wiper. Therefore, when the wiper is not operating, the state determination unit 111 can determine that there is no decrease in transparency. Also. When the wiper operation is INT, the state determination unit 111 determines that the decrease in transparency is small. When the wiper operation is Lo or Hi, the state determination unit 111 determines that the decrease in permeability is large.

  In this way, the state determination unit 111 determines the state of the windshield 11 with reference to the table shown in FIG. The state determination unit 111 can determine the state of the windshield 11 based on the detection signal from the state detection unit 160. Of course, the state determination unit 111 may determine the state of the windshield 11 in four or more stages, or may determine in two stages. When the state of the windshield 11 is divided into two stages, the state determination unit 111 can determine whether there is a decrease in permeability. When the state of the windshield 11 is divided into four or more stages, the state determination unit 111 may set two or more threshold values for the detected amount of raindrops.

  Further, the state detection unit 160 that detects the state of the windshield 11 is not limited to the water droplet adhesion sensor or the wiper operation. Furthermore, the state detection unit 160 may detect the state of the windshield 11 by combining a water droplet adhesion sensor and a wiper operation.

  Next, a video display method by the head-up display device 100 will be described with reference to FIG. FIG. 6 is a flowchart showing a video display method, and specifically shows video change processing corresponding to the state of the windshield 11. Before the process of the flowchart of FIG. 6 starts, the display data acquisition unit 112 acquires display data, and the state detection unit 160 detects the state of the windshield 11.

  First, the state determination unit 111 determines whether or not the transparency of the video projection surface (wind shield 11) is lowered (S11). That is, the state determination unit 111 determines the state of the windshield 11 based on the detection result from the state detection unit 160. The determination of the decrease in the transparency of the video projection surface is performed according to the table of FIG. For example, when no raindrop is detected, the state determination unit 111 determines that there is no decrease in permeability (NO in S11). Alternatively, when the wiper operation is stopped or MIST, the state determination unit 111 determines that there is no decrease in permeability. In this case, the video change process ends. That is, the video generation unit 113 generates a video by normal processing. Then, the image light projection unit 120 generates and emits image light L1 for displaying the default image.

  When the permeability is reduced (YES in S11), the state determination unit 111 determines whether or not the reduction rate of the permeability is large (S12). That is, the state determination unit 111 determines the state of the windshield 11 based on the detection result from the state detection unit 160. The determination as to whether the permeability reduction rate is large is made according to the table of FIG. For example, when the detected raindrop amount is small, the state determination unit 111 determines that the decrease in permeability is small (NO in S12). On the other hand, when the detected raindrop amount is large, the state determination unit 111 determines that the decrease in permeability is large (YES in S12). Alternatively, when the wiper operation is INT, the state determination unit 111 determines that the decrease in permeability is small (NO in S12). On the other hand, when the wiper operation is Lo or Hi, the state determination unit 111 determines that the decrease in permeability is large (YES in S12).

  When the state determination unit 111 determines that the decrease in transparency is large (YES in S12), the video generation unit 113 executes a visibility improvement process (large) (S13). When the state determination unit 111 determines that the decrease in transparency is small (NO in S12), the video generation unit 113 executes a visibility improvement process (small) (S14).

  The visibility improving process is a process for improving the visibility of a displayed video. That is, by performing the visibility improving process, it is possible to improve the visibility of a virtual image that is visually recognized through the windshield 11. When the control unit 110 performs the visibility improving process, the video light projecting unit 120 can generate a visibility improved video with improved visibility compared to the default video. The visibility improving process (large) has a greater effect of improving the visibility than the visibility improving process (small).

  That is, when the visibility improvement process (large) is executed, the video generation unit 113 generates a visibility improvement video (large) in which the visibility is greatly improved with respect to the default video. Then, the video light projection unit 120 generates and emits video light L1 for displaying the visibility-enhanced video (large). When the visibility improving process (small) is executed, the video generation unit 113 generates a visibility improving video (small) in which the visibility is slightly improved with respect to the default video. Then, the video light projection unit 120 generates and emits video light L1 for displaying the visibility-enhanced video (small).

  In the present embodiment, the video generation unit 113 performs a process of changing the display size of the virtual image as the visibility improving process. The video generation unit 113 changes the display size according to the degree of decrease in the permeability of the windshield 11 determined by the state determination unit 111. Specifically, when the transparency is lowered, the video generation unit 113 generates a video with a larger virtual image display size. For example, as the visibility improvement process, the video generation unit 113 performs at least one of changing the overall display size and changing the display icon size.

  FIG. 7 is a table showing a specific example of the visibility improving process. FIG. 7 shows a table of the visibility improvement processing (large), the visibility enhancement processing (small), and the processing without the visibility enhancement processing. In FIG. 7, processing for changing the overall display size and display icon size, which is an example of the visibility improving process according to the present embodiment, and luminance and contrast, which are examples of the visibility improving process according to the second embodiment to be described later. , And processing for changing the character (line) thickness. Specifically, the case where there is no decrease in transparency, that is, the case where the visibility improving process is not performed is set as a default.

  A case where the entire display size is changed will be described as the visibility improving process. The entire display size when the visibility improving process is not performed is set as a default size. When the visibility improvement process (small) is performed, the entire display size is set to a medium size larger than the default size. When the visibility improving process (large) is performed, the entire display size is set to a large size larger than the medium size. As described above, the video generation unit 113 changes the enlargement magnification according to the degree of decrease in the permeability of the windshield 11.

  As the visibility improving process, when the entire display size is changed, the effective area used for display by the display element 125 and the non-effective area around it may be changed. For example, in the display element 125, in order to perform distortion correction according to the situation of the windshield 11, not all areas are displayed. That is, the display element 125 is provided with an effective area where display is performed and an ineffective area around it. In the effective area, each pixel performs gradation display, and in the non-effective area, each pixel performs black display.

  In the case of the default size, the video generation unit 113 reduces the effective area in the central portion of the display element 125 and increases the surrounding ineffective area. When the overall display size is increased, the proportion of the effective area may be increased. The video generation unit 113 may generate a video having a size that can be displayed within the effective area of the display element 125. By doing in this way, a visibility improvement process can be performed easily.

  The case where a display icon size is changed as a visibility improvement process is demonstrated. The display icon size when the visibility improving process is not performed is set as a default size. When the visibility improving process (small) is performed, the display icon size is set to a medium size larger than the default size. When the visibility improving process (large) is performed, the display icon size is set to a large size larger than the medium size. When changing the display icon size as the visibility improving process, the video generated by the video generation unit 113 may be changed.

  The display icon includes an arrow indicating the direction of travel at the intersection (right turn, left turn, straight ahead, etc.), the distance to the intersection, and the name of the intersection. The video generation unit 113 generates a video in which one or more of these display icons are enlarged.

  8 and 9 show specific examples of virtual images that have been subjected to the visibility improving process. 8 and 9, the default video is shown on the left side, and the video on which the visibility improving process has been performed is shown on the right side. FIG. 8 shows a video in which the entire display size is changed, and FIG. 9 shows a video in which the display icon size is changed. 8 and 9 show a virtual image visually recognized through the windshield 11. FIG. The visibility is improved also when the display icon size is changed and when the entire display size is changed.

  In this way, the video generation unit 113 generates video so as to enlarge the overall display size or display icon size of the virtual image. Therefore, even when the state of the windshield 11 changes, the visibility of the virtual image can be improved. When a decrease in the permeability of the windshield 11 is detected, the video generation unit 113 performs a visibility improvement process. Thereby, a virtual image with improved visibility can be displayed.

  Improve visibility, which deteriorates due to raindrops and rainfall during bad weather. Driving fatigue when visibility deteriorates due to raindrops / rainfall during bad weather can be reduced. Since the influence of raindrops is reduced, the deterioration of virtual image visibility can be reduced, and good visibility can be ensured. Furthermore, the driver P can be prevented from feeling bothered during driving. As a result, even when the weather is bad, the driver's turn P can be driven safely and safely.

  Furthermore, as an example of changing the display size, an example of changing the entire display size or the display icon size has been shown, but the display font size may be changed. That is, the number of dots of the display font to be drawn may be increased. The display size may be changed only in one direction in the vertical direction and the horizontal direction. In this case, the display size can be increased even if distortion occurs. Of course, the display size may be changed in both the vertical direction and the horizontal direction.

Embodiment 2. FIG.
In the present embodiment, the visibility improving process is different from that of the first embodiment. In the present embodiment, as the visibility improving process, the video generation unit 113 generates a video so that the virtual image becomes clear. Note that the processing and configuration other than the visibility improvement processing are the same as those in the first embodiment, and thus the description thereof is omitted. As the visibility improving process according to the present embodiment, as shown in FIG. 7, there are a change in luminance, a change in contrast, and a change in the thickness of characters (lines).

  A case where the luminance is changed as the visibility improving process will be described. The brightness when the visibility improving process is not performed is set as the default brightness. When the visibility improving process (small) is performed, the brightness is set to a medium brightness higher than the default brightness. When the visibility improving process (large) is performed, the brightness is set to a higher brightness than the middle brightness. When changing the luminance as the visibility improving process, the light amount of the light source 121 may be controlled.

  A case where the contrast is changed as the visibility improving process will be described. The contrast when the visibility improving process is not performed is set as a default value. When the visibility improving process (small) is performed, the contrast is set to a medium contrast larger than the default value. When the visibility improving process (large) is performed, the contrast is set to a high contrast higher than the medium contrast.

  The case where a character (line) thickness is changed as a visibility improvement process is demonstrated. The contrast when the visibility improving process is not performed is set as a default value. When the visibility improving process (small) is performed, the character (line) thickness is set to a medium size thicker than the default value. When the visibility improving process (large) is performed, the thickness of the character (line) is set to be thicker than the medium size.

  The items of the visibility improving process for clarifying the virtual image are not limited to the items shown in the table of FIG. Any device that can improve visibility in the processing of the video generation unit 113 may be used. For example, as the visibility improving process, the video generation unit 113 may change the chromaticity of the virtual image. For example, it is possible to change the chromaticity of an image by negative-positive-inverting a video for displaying a virtual image, changing to two gradations, changing an RGB color, or the like.

  In negative / positive inversion, high gradation pixels close to white display are changed to low gradation pixels close to black display, and low gradation pixels close to black display are changed to high gradation pixels close to white display. In 2 gradation, a multi-gradation image of 8 bits or the like is converted into a 1-bit (monochrome) 2 gradation image. In the RGB exchange / change, the display color of the direction arrow is changed to the emphasized color.

  10 to 14 show specific examples of virtual images that have been subjected to the visibility improving process. 10 to 14, the default video is shown on the left side, and the video on which the visibility improving process has been performed is shown on the right side. Moreover, FIGS. 10-14 has shown the virtual image visually recognized through the windshield 11. FIG. FIG. 10 shows a luminance change, FIG. 11 shows a contrast change, FIG. 12 shows negative / positive inversion, FIG. 13 shows two gradations, and FIG.

  In addition, as a visibility improvement process, when performing a brightness | luminance change and chromaticity change, you may change a brightness | luminance and chromaticity according to the detection result of an illumination intensity sensor. For example, ambient illuminance is detected by an illuminance sensor mounted on the automobile 1. Then, the luminance and chromaticity may be changed according to the detection result of the illuminance sensor.

  As described above, according to the video display method according to the present embodiment, it is possible to improve the visibility that is deteriorated by raindrops in bad weather. Since the driver P can clearly see the virtual image, driving fatigue when visibility is deteriorated can be reduced.

  For example, even if it rains, the driver P can see a virtual image, but since both the raindrop and the virtual image are close to each other, both are focused. For this reason, the visibility of the virtual image recognition is remarkably deteriorated, and further, the influence causes annoyance during driving or a great fatigue occurs. In particular, it is difficult to recognize a fine dot size image or character due to the influence of the raindrop size or the raindrop amount. However, the visibility can be improved by executing the visibility improving process when raindrops are attached as in the present embodiment. Further, when raindrops are not attached, the normal default image is displayed without performing the visibility improving process. Therefore, when raindrops are not attached, it is possible to display without excessive emphasis, so that driving fatigue can be reduced.

  In the above description, the state detection unit 160 detects the presence / absence of raindrops and a change in rainfall, but it can also cope with other weather conditions. For example, even when the state of the windshield 11 is changed due to snow or dust, the same processing can be performed. For example, the visibility improving process can be performed depending on whether or not the permeability of the windshield 11 is lowered due to snow or dust. Further, two or more visibility enhancement processes may be combined. For example, two or more of a change in the overall display size, a change in display icon size, a luminance change, a contrast change, a character (thickness) thickness change, and a chromaticity change may be combined.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

DESCRIPTION OF SYMBOLS 1 Car 10 Dashboard 11 Windshield 12 Steering wheel P Driver 100 Head-up display device 110 Control unit 111 State determination unit 112 Display data acquisition unit 113 Video generation unit 114 Projection control unit 120 Video light projection unit 121 Light source 122 Light tunnel 123 Fresnel lens 124 Diffuser 125 Display element 130 Concave mirror 160 State detector

Claims (8)

An image light projection unit that projects image light according to an image displayed as a virtual image viewed through the image projection plane;
An optical system for guiding the image light to an image projection surface;
A state determination unit for determining a state of the image projection plane;
Based on the determination result in the state determination unit, a video generation unit that generates the video so as to improve the visibility of the virtual image viewed through the video projection plane;
A video display device comprising:   2. The video generation unit according to claim 1, wherein the video generation unit generates the video so as to increase a display size of the virtual image when the state determination unit determines that the transparency of the video projection plane is reduced. Video display device.   The video display device according to claim 2, wherein the video generation unit increases the display size according to the degree of decrease in the transparency determined by the state determination unit.   The video generation unit generates the video so that the virtual image becomes clear when the state determination unit determines that the transparency of the video projection plane is reduced. The video display device according to item.   The video generation unit makes the virtual image clear by at least one of changing a luminance of the virtual image, changing a contrast, changing a font, changing a line width, and changing a chromaticity. Item 5. The video display device according to Item 4.   The said state determination part determines the state of the said image projection surface according to the detection signal from the water droplet adhesion sensor which detects the water droplet adhering to the said image projection surface. The video display device described in 1. The video display device is mounted on a vehicle,
The video display device according to claim 1, wherein the state determination unit determines a state of the video projection surface in accordance with an operation signal indicating a wiper operation of the vehicle. A determination step of determining a state of a video projection surface that projects video light according to a video displayed as a virtual image;
Based on the state of the video projection plane determined in the determination step, a video generation step for generating the video so that the visibility of the virtual image viewed through the video projection plane is improved,
A projection step of projecting the video generated in the video generation step as video light on the video projection surface;
Video display method.