Image reproduction device

Abstract

This image reproduction device is provided with: a display unit that includes a first region and a second region; a storage unit that stores first content that includes an image and second content that includes an image having a smaller amount of change or a smaller change rate than the first content; and a reproduction control unit that causes the first region to reproduce the first content and causes the second region to reproduce the second content.

Description

Video playback device

[0001] The present disclosure relates to a technology for displaying video on a display device mounted on a moving object.

[0002] Patent Literature 1 discloses a vehicle monitor display system that suppresses monitor sickness in occupants. This vehicle monitor display system provides a display area with margins on the screen of an image monitor, displays content in the display area, and controls movement of the display area on the screen using the margins based on vibrations detected by an input detection device and the position of the occupant's line of sight detected by a position detection device.

[0003] However, the above-mentioned conventional technology avoids monitor sickness in occupants by setting the difference frequency between the vibration frequency of the image monitor and the movement frequency of the occupant's line of sight outside the frequency range of monitor sickness, and does not avoid monitor sickness by reducing the movement of the occupant's line of sight. Therefore, the above-mentioned conventional technology needs further improvement in order to suppress motion sickness in occupants.

[0004] Japanese Patent Application Laid-Open No. 2017-171243

[0005] The present disclosure has been made to solve such problems, and aims to provide a technology that suppresses motion sickness by reducing the movement of the occupant's line of sight.

[0006] A video playback device in one aspect of the present disclosure is a video playback device installed inside a moving body, and includes a display unit including a first area and a second area, a memory unit that stores first content including video and second content including video with a smaller amount of change or rate of change than the first content, and a playback control unit that plays the first content in the first area and plays the second content in the second area.

[0007] According to the present disclosure, motion sickness can be suppressed by reducing the movement of the passenger's line of sight.

[0008] 1 is a diagram illustrating the electrical configuration of a video playback device according to an embodiment of the present disclosure; FIG. 2 is a diagram illustrating a top view of a moving body; FIG. 3 is a diagram illustrating the interior of a moving body equipped with a video playback device; FIG. 4 is a diagram illustrating a first example of video content displayed on a display device; FIG. 5 is a diagram illustrating a second example of video content displayed on a display device; FIG. 6 is a diagram illustrating a third example of video content displayed on a display device; FIG. 7 is a diagram illustrating a fourth example of video content displayed on a display device; and FIG. 8 is a diagram illustrating a fifth example of video content displayed on a display device. A diagram illustrating a method for determining the vertical length of a first display region. A diagram illustrating a method for determining the horizontal length of the first display region. A flowchart illustrating processing performed by a video playback device according to an embodiment of the present disclosure when playing back video content. A flowchart illustrating processing performed by a video playback device according to an embodiment of the present disclosure when switching the position of the first region depending on the seating position of an occupant.

[0009] (Findings that Form the Basis of the Present Disclosure) Development is underway of a device that provides a large screen display between the front and rear seats of a vehicle and presents video content to passengers in the rear seats through this large screen display.

[0010] When video content is displayed on the above-mentioned large-screen display while moving, passengers in the rear seats watch the video content without being able to see the scenery outside the vehicle, which makes them more susceptible to sensory conflict and motion sickness. Furthermore, when passengers move their eyes vertically and horizontally to watch the video content while moving, the sensory conflict in each direction increases, making motion sickness even more likely to occur. Sensory conflict is thought to be one of the causes of motion sickness, and refers to the conflict that occurs when the brain of a passenger in a moving vehicle integrates visual information from the eyes, balance information obtained from the semicircular canals that detect rotation and the otolith organs that detect acceleration, and somatic distance information obtained from the joints and skin.

[0011] On the other hand, research has shown that people who are less susceptible to motion sickness tend to barely move their eyes, or even if they do, the range of movement is small. This is thought to be because the smaller the eye movement, the more sensory conflict is suppressed. Therefore, reducing eye movement is an effective way to prevent motion sickness.

[0012] In the conventional technology shown in Patent Document 1, when the differential frequency between the vehicle width direction displacement frequency of the image monitor and the vehicle width direction eye displacement frequency is included in the frequency range of monitor sickness in the vehicle width direction, movement control of the display range is performed by utilizing the margins on the screen of the image monitor so that the vehicle width direction displacement frequency and the vehicle width direction eye frequency match.

[0013] However, in the conventional technology disclosed in Patent Document 1, the display range is simply shifted so that the vehicle width direction displacement frequency and the vehicle width direction eye line displacement frequency coincide with each other, and the display range is not shifted so as to reduce the change in the occupant's line of sight. Therefore, the conventional technology disclosed in Patent Document 1 needs further improvement in order to suppress motion sickness in occupants.

[0014] Therefore, the inventors discovered that by dividing the display unit into a first area and a second area smaller in area than the first area, displaying a first content including a video in the first area, and displaying a second content with less movement than the first content in the second area, it is possible to reduce the movement of the passenger's line of sight and suppress motion sickness, and this led to the present disclosure.

[0015] (1) A video playback device according to one aspect of the present disclosure is a video playback device installed inside a moving body, and includes: a display unit including a first area and a second area; a memory unit that stores first content including video and second content including video with a smaller amount of change or rate of change than the first content; and a playback control unit that plays the first content in the first area and plays the second content in the second area.

[0016] According to this configuration, the display unit is divided into a first area and a second area smaller than the first area, a first content including a video is displayed in the first area, and a second content having less movement than the first content is displayed in the second area. This allows the occupant to focus on the first content, thereby reducing the movement of the occupant's line of sight and suppressing motion sickness.

[0017] (2) In the video playback device described in (1) above, the vertical length of the first area may be longer than the vertical length of the second area.

[0018] It is said that the direction of shaking of a moving object affects motion sickness in the following order: vertical, front-back, and left-right. With this configuration, the vertical length of the first region is longer than the vertical length of the second region, so that vertical line-of-sight movement can be reduced to suppress motion sickness without impairing the realism of the first content.

[0019] (3) In the video playback device described in (1) or (2) above, the horizontal length of the first area may be longer than the horizontal length of the second area.

[0020] With this configuration, the horizontal length of the first area is longer than the horizontal length of the second area, so that horizontal eye movement can be reduced without compromising the realism of the first content, thereby suppressing motion sickness.

[0021] (4) In the video playback device described in any one of (1) to (3) above, the first content may include an object that changes depending on the position of the first area.

[0022] According to this configuration, it is possible to make the occupant pay more attention to the first content, reduce the movement of the line of sight, and suppress motion sickness.

[0023] (5) In the video playback device described in (4) above, the object may change along a vertical central axis of the first area or along the horizontal central axis.

[0024] According to this configuration, it is possible to display an object that changes on the vertical central axis of the first area or an object that changes on the horizontal central axis of the first area.

[0025] (6) In the video playback device described in any of (1) to (5) above, the playback control unit may set at least one of the ratio of the vertical lengths of the first area and the second area and the ratio of the horizontal lengths of the first area and the second area to a predetermined ratio.

[0026] With this configuration, the first and second areas can be divided vertically at a predetermined ratio, the first and second areas can be divided horizontally at a predetermined ratio, or the first and second areas can be divided vertically, horizontally, and vertically at a predetermined ratio.

[0027] (7) In the video playback device described in (6) above, the moving body may include a seat facing the display unit, and the predetermined ratio may be determined based on the distance between the display unit and the seat.

[0028] According to this configuration, the predetermined ratio can be determined taking into consideration the distance between the display unit and the seat.

[0029] (8) In the video playback device described in any of (1) to (7) above, the moving body may include a seat facing the display unit, and further include an acquisition unit that acquires information indicating the seating position of an occupant in the seat, and the playback control unit may determine the position of the second area depending on the seating position.

[0030] With this configuration, the position of the second area can be determined to be an appropriate position depending on the seating position.

[0031] (9) In the video playback device described in (8) above, the seats include a left seat located on the left side and a right seat located on the right side in the direction of travel of the moving body, and the playback control unit may determine the position of the second area to the right of the first area when the seating position is the left seat, determine the position of the second area to the left of the first area when the seating position is the right seat, and determine the position of the second area to the right and left of the first area when the seating positions are the left seat and the right seat.

[0032] According to this configuration, the center of the first content is positioned in front of the occupant, which reduces the amount of lateral rotation of the neck, allowing the occupant to adopt a comfortable posture.

[0033] (10) In the video playback device described in any of (1) to (9) above, the vertical length of the first area or the ratio of the vertical lengths of the first area and the second area may be determined based on the vertical field of view of an occupant of the moving body.

[0034] According to this configuration, the ratio of the lengths of the first area and the second area in the vertical direction can be determined taking into consideration the vertical field of view of the passenger, thereby ensuring a sense of realism for the first content.

[0035] (11) In the video playback device described in any of (1) to (10) above, the horizontal length of the first area or the ratio of the horizontal lengths of the first area and the second area may be determined based on the horizontal field of view of an occupant of the moving body.

[0036] According to this configuration, the ratio of the lengths of the first area and the second area in the horizontal direction can be determined taking into consideration the horizontal field of view of the passenger, thereby ensuring a sense of realism in the first content.

[0037] (12) In the video playback device described in any one of (1) to (11) above, the vertical length of the first area may be a length that falls within a predetermined vertical field of view angle of an occupant of the moving body.

[0038] According to this configuration, the first content can be displayed so as to fit within a predetermined viewing angle in the vertical direction of the occupant, thereby ensuring a sense of realism for the first content.

[0039] (13) In the video playback device described in any one of (1) to (12) above, the horizontal length of the first area may be a length that falls within a predetermined horizontal field of view angle of an occupant of the moving body.

[0040] According to this configuration, the first content can be displayed so as to fit within a predetermined viewing angle in the horizontal direction of the occupant, thereby ensuring a sense of realism for the first content.

[0041] (14) In the video playback device described in any one of (1) to (13) above, the first content may be a moving image, and the second content may be a blank image in the first area.

[0042] According to this configuration, by having the viewer focus on the first content, movement of the line of sight can be reduced, thereby suppressing motion sickness.

[0043] (15) In the video playback device described in any one of (1) to (14) above, the first area may be located above the second area.

[0044] With this configuration, the center of the image in the first content rises and the face is turned up, increasing the contact area between the back of the head and the headrest and reducing facial vibration, thereby reducing vertical line of sight movement and suppressing motion sickness.

[0045] (16) In the video playback device described in any one of (1) to (15) above, the first region may be larger in area than the second region.

[0046] According to this configuration, the first region has a larger area than the second region, so that motion sickness can be suppressed without impairing the realism of the first content.

[0047] The present disclosure can also be realized as a video playback program that causes a computer to execute each of the characteristic components included in such a video playback device, or as a video playback system operated by this video playback program. It goes without saying that such a computer program can be distributed on a computer-readable non-transitory recording medium such as a CD-ROM or via a communication network such as the Internet.

[0048] Note that each of the embodiments described below represents a specific example of the present disclosure. The numerical values, shapes, components, steps, and step orders shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concept are described as optional components. Furthermore, in all of the embodiments, the respective contents can be combined.

[0049] (Embodiment) FIG. 1 is a diagram illustrating the electrical configuration of a video playback device 1 according to an embodiment of the present disclosure. The video playback device 1 is installed in the cabin of a vehicle 200 (see FIG. 2). The video playback device 1 is a system that uses a display device 41, an audio device 42, and a lighting device 43 to create an environment within the cabin of the vehicle 200 and guides the occupants of the vehicle 200 to an appropriate state. The vehicle 200 may be any type of vehicle, such as an electric vehicle, a gasoline-powered vehicle, or a hybrid vehicle. In the following description, the occupants are assumed to be people sitting in the back seat. The video playback device 1 may include a diffuser that diffuses a fragrance within the cabin, or a vibration device that applies vibrations to the occupants.

[0050] The video playback device 1 includes a control unit 10 , a display control unit 31 , an audio control unit 32 , an illumination control unit 33 , a display device 41 (an example of a display unit), an audio device 42 , and an illumination device 43 .

[0051] The control unit 10 is configured as a computer including a central processing unit (CPU) and a storage device, and includes a playback control unit 11, a storage unit 12, and an acquisition unit 13. The playback control unit 11 and the acquisition unit 13 may be realized by the CPU executing a video playback program, or may be realized by a dedicated hardware circuit.

[0052] The playback control unit 11 reads the first content from the storage unit 12 and plays the first content in a first area of ​​the display device 41. The playback control unit 11 reads the second content from the storage unit 12 and plays the second content in a second area of ​​the display device 41.

[0053] The first area is a rectangular area provided in the display area of ​​the display device 41, and is an area for displaying the first content. The second area is a rectangular area in the display area of ​​the display device 41 excluding the first area, and is an area for displaying the second content. The area of ​​the first area is larger than that of the second area.

[0054] The first content includes video. The video included in the first content is a moving image. The first content is video content selected by the playback control unit 11 from a plurality of first contents stored in the storage unit 12.

[0055] The second content includes video with a smaller amount of change or rate of change than the first content. The second content is video content selected by the playback control unit 11 from a plurality of second contents stored in the storage unit 12. The video included in the second content is, for example, a still image. This still image may be a black margin image indicating the margin of the first area of ​​the display device 41. The second content may also include a character string indicating a message. Note that the margin image may be colorless (transparent) or may be a color other than black.

[0056] The amount of change refers to the distance an object included in the video moves within the display screen, and the speed of change refers to the speed at which an object included in the video moves within the display screen.

[0057] The playback control unit 11 determines the content for the relaxation phase, the content for the sleep phase, and the content for the wakefulness phase from the departure point until the moving body 200 arrives at the destination, and outputs control signals to the display control unit 31, the sound control unit 32, and the lighting control unit 33 to control the display device 41 to the lighting device 43 so that the determined content is played.

[0058] The relaxation phase is a phase in which the occupant is guided to a relaxed state. The sleep phase is a phase in which the occupant is guided to a sleeping state. The wakefulness phase is a phase in which the occupant is guided to a waking state. The occupant can be comfortably woken up by first guiding the occupant to a relaxed state, then guiding the occupant to a sleeping state, and then guiding the occupant to a waking state. This allows the occupant to be active after arriving at the destination.

[0059] The storage unit 12 is configured as a rewritable nonvolatile storage device such as a flash memory, and stores a plurality of first contents and a plurality of second contents. The plurality of first contents includes, for example, video contents consisting of moving images of natural scenery. The plurality of first contents includes audio contents that reproduce sounds occurring in natural scenery.

[0060] The plurality of second contents may be, for example, contents including a message indicating the current phase in a black still image that is a blank image in the first area.

[0061] The acquisition unit 13 acquires seating position information indicating the seating positions of occupants in the seats from the sensor 20. The seats are rear seats of the vehicle 200 facing the display device 41. The rear seats include a left rear seat located on the left side of the vehicle 200 in the traveling direction, and a right rear seat located on the right side.

[0062] The sensor 20 is a seat pressure sensor provided in each of the left rear seat and the right rear seat. When the sensor 20 detects that an occupant is seated in the left rear seat, it outputs seating position information indicating this to the acquisition unit 13. When the sensor 20 detects that an occupant is seated in the right rear seat, it outputs seating position information indicating this to the acquisition unit 13. When the sensor 20 detects that an occupant is seated in both the left rear seat and the right rear seat, it outputs seating position information indicating this to the acquisition unit 13. Note that the sensor 20 may be a sensor that detects the seating positions of the occupants using a camera.

[0063] The seating position information may be input from a remote control (not shown) of the video playback device 1. The remote control is communicably connected to the control unit 10 via a wireless LAN or a short-range wireless communication path. The occupant operates the remote control to input their own seating position, causing the remote control to output the seating position information. The remote control may be a dedicated remote control for the video playback device 1, or may be a mobile information terminal (e.g., a smartphone or tablet computer) carried by the occupant.

[0064] The reproduction control unit 11 may determine the positions of the first and second areas on the display area of ​​the display device 41 based on the seating position information acquired by the acquisition unit 13. This process will be described in detail later.

[0065] The display control unit 31 is composed of a drive circuit that drives the display device 41, and controls the operation of the display device 41 in accordance with control signals from the playback control unit 11. These control signals include trigger signals that indicate the start timing of each phase, video data for playing video content corresponding to the phase, and instruction signals that instruct the display device 41 to be turned on or off.

[0066] The audio control unit 32 is composed of a drive circuit (e.g., an amplifier) ​​that drives the audio device 42, and controls the operation of the audio device 42 in accordance with a control signal from the playback control unit 11. This control signal includes a trigger signal, audio data for playing audio content according to the phase, and an instruction signal that instructs the audio device 42 to be on or off.

[0067] The lighting control unit 33 is composed of a drive circuit that drives the lighting device 43, and controls the operation of the lighting device 43 in accordance with a control signal from the playback control unit 11. This control signal includes a trigger signal, dimming data for dimming the lighting device 43 with a dimming pattern according to the phase, and an instruction signal for instructing the lighting device 43 to be on or off.

[0068] The display device 41 is configured, for example, by a transparent display, and displays video content for guiding the occupant to a state according to the phase under the control of the playback control unit 11. A transmissive organic EL display can be used as the transparent display.

[0069] The sound device 42 is configured by, for example, a speaker, and outputs sound content for guiding the occupant into a state according to the phase under the control of the playback control unit 11 .

[0070] Under the control of the lighting control unit 33, the lighting device 43 adjusts the light inside the vehicle interior 200 to guide the occupants to a state according to the phase.

[0071] FIG. 2 is a top view of the vehicle 200. The vehicle 200 includes a front seat 210 located at the front of the vehicle in the direction of travel, and a rear seat 220 located at the rear of the vehicle in the direction of travel. The front seat 210 includes a left front seat 211 located on the left side of the vehicle in the direction of travel, and a right front seat 212 located on the right side. A driver rides in the left front seat 211 or the right front seat 212. The rear seat 220 includes the left rear seat 221 and right rear seat 222 described above. In this embodiment, the term "occupant" refers to an occupant seated in the rear seat 220.

[0072] The display device 41 is installed between the front seat 210 and the rear seat 220. The display device 41 is a large-screen display whose horizontal length is slightly shorter than the width of the vehicle interior and whose vertical length is slightly shorter than the vertical length of the vehicle interior. The display device 41 may be installed in front of the passenger seat of the front seat 210. If the vehicle 200 has a rear seat behind the rear seat 220, the display device 41 may be installed in front of the rear seat. Multiple display devices 41 may be installed on the left and right sides, and may be installed in positions facing (in front of) the left rear seat 221 and the right rear seat 222, for example. In this case, each display device 41 has a horizontal length slightly shorter than half the width of the vehicle interior.

[0073] FIG. 3 is a diagram showing the interior of a vehicle 200 equipped with the video playback device 1. FIG. 3 shows the interior of the vehicle as viewed from behind the rear seat 220 in the direction of travel. The display device 41 is installed between the front seat (not shown) and the rear seat 220 to separate the front space from the rear space within the vehicle. The lighting device 43 includes a lighting device 43a mounted above the display device 41 and a pair of lighting devices 43b and 43c mounted on the ceiling. The lighting device 43a is installed between the ceiling of the vehicle 200 and the display device 41 so that its longitudinal direction is parallel to the horizontal direction. The lighting devices 43a to 43c are configured, for example, with linear LEDs. The lighting device 43b is mounted on the left edge of the ceiling, and the lighting device 43c is mounted on the right edge of the ceiling. The sound device 42 includes a pair of left and right speakers, and is installed on both sides of the lighting device 43a. Because the display device 41 is a transparent display, the scenery ahead of the moving body 200 passes through the windshield of the moving body 200 and the display device 41. This allows the passenger in the rear seat 220 to view the scenery ahead of the moving body 200 while also viewing the video content displayed by the display device 41.

[0074] 4 is a diagram showing a first example of video content 300 displayed on display device 41. Video content 300 includes a first area 310 located above the display area and a second area 320 located below the display area.

[0075] The vertical length H1 of the first region 310 is longer than the vertical length H2 of the second region 320. The ratio between the lengths H1 and H2 is predetermined, and is, for example, 7:3. However, this is just an example, and the ratio between the lengths H1 and H2 may be 9:1, 8:2, 6:4, etc. The horizontal length of the first region 410 is the same as the horizontal length of the second region 420. An example of the length H1 is 13.07 cm, and an example of the length H2 is 5.95 cm.

[0076] In this example, first area 310 displays first content including a moving image of a natural landscape in which trees grow on moss-covered ground. Also, in this example, second area 320 displays second content in black, which is a blank image of first area 310. Since the current phase is the awakening phase, the second content displays a message indicating that the current phase is the awakening phase.

[0077] A boundary line L1 between the first region 310 and the second region 320 is oriented horizontally. That is, when the display region of the display device 41 is divided by the boundary line L1, the upper rectangular region is the first region 310, and the lower rectangular region is the second region 320.

[0078] The first region 310 has a larger area than the second region 320 and displays the first content consisting of a moving image, while the second region 320 displays a blank image. This allows the occupant to focus on the first content. Here, the first region 310 displays the first content with a reduced vertical width, thereby reducing the occupant's vertical line of sight. As a result, motion sickness in the occupant is suppressed. Furthermore, because the first region 310 has a larger area than the second region 320, the sense of realism of the first content is not impaired. Furthermore, because the first region 310 is located above the second region 320, the center of the image in the first content is raised, and the occupant's face is also raised. As a result, the contact area between the occupant's head and the headrest is increased, reducing vibration of the occupant's face. This reduces the occupant's vertical line of sight, further suppressing motion sickness.

[0079] The playback control unit 11 may display the first content in the first area 310 by applying a trimming process to the first content so that the size of one frame of the image of the first content matches the size of the first area. Alternatively, the playback control unit 11 may display the first content in the first area 310 by applying a reduction process to the first content so that the size of one frame of the image of the first content matches the size of the first area 310. Alternatively, the playback control unit 11 may display the first content in the first area 310 by combining a trimming process and a reduction process so that the size of one frame of the image of the first content matches the size of the first area 310. Furthermore, the first area 310 may be provided on the lower side, and the second area 320 may be provided on the upper side.

[0080] 5 is a diagram showing a second example of video content 400 displayed on display device 41. Video content 400 includes a first area 410 located on the left side of the display area and a second area 420 located on the right side.

[0081] The horizontal length W1 of the first region 410 is longer than the horizontal length W2 of the second region 420. The ratio of the lengths W1 and W2 is predetermined, and is, for example, 6:4. However, this is just an example, and the ratio of the lengths W1 and W2 may be 9:1, 8:2, 7:3, etc. The vertical length of the first region 410 is the same as the vertical length of the second region 420.

[0082] In this example, the first area 410 displays the first content shown in Fig. 4. Also, in this example, the second area 420 displays the second content shown in Fig. 4.

[0083] A boundary line L2 between the first region 410 and the second region 420 faces in the vertical direction. That is, when the display device 41 is divided by the boundary line L2, the rectangular region on the left side is the first region 410, and the rectangular region on the right side is the second region 420. Note that in the example of Fig. 5, the first region 410 is located on the left side and the second region 420 is located on the right side, but this is just an example, and the first region 410 may be located on the right side and the second region 420 may be located on the left side.

[0084] The first region 410 is larger in area than the second region 420 and displays the first content consisting of a moving image, while the second region 420 displays a blank image of the first region 410. This allows the occupant to focus on the first content. Here, the first region 410 displays the first content with a reduced width, thereby reducing the horizontal movement of the occupant's line of sight. As a result, motion sickness in the occupant is suppressed. Furthermore, because the first region 410 is larger in area than the second region 420, the sense of realism of the first content is not impaired. Furthermore, because the first region 410 is located to the left of the second region 420, the center of the first content is positioned directly in front of the occupant sitting in the left rear seat 221, which reduces the need for lateral neck rotation and allows the occupant to assume a more comfortable posture.

[0085] In addition, the playback control unit 11 displays the first content in the first area 410 by applying at least one of a trimming process and a reduction process to the first content so that the size of one frame of the image of the first content becomes the size of the first area 410.

[0086] 6 is a diagram showing a third example of video content 500 displayed on display device 41. Video content 500 includes a first area 510, which is a rectangular area including the upper left vertex of the display area of ​​display device 41, and a second area 520, which is an area other than first area 510 on display device 41 and includes the upper right, lower left, and lower right vertices. In other words, second area 520 has a configuration that combines second area 320 of the first example and second area 420 of the second example. Note that in FIG. 6, the same components as those in FIGS. 4 and 5 are designated by the same reference numerals, and description thereof will be omitted.

[0087] The vertical length H1 of the first region 510 is longer than the vertical length H2 of the second region 520. The horizontal length W1 of the first region 510 is longer than the horizontal length W2 of the second region 520.

[0088] In this example, the first area 510 displays the first content shown in Fig. 4. Also, in this example, the second area 520 displays the second content shown in Fig. 4.

[0089] Boundary line L3 includes horizontal boundary line L31 and vertical boundary line L32. The intersection of boundary line L31 and boundary line L32 is the lower right vertex of first region 510. Note that in the example of Fig. 6, first region 510 is a region that includes the upper left vertex, but this is just an example, and first region 510 may be a rectangular region that includes any one of the upper right, lower left, and lower right vertices.

[0090] The first region 510 has a larger area than the second region 520 and displays the first content consisting of a moving image, while the second region 520 displays a blank image. This allows the occupant to focus on the first content. Here, the first region 510 displays the first content with a reduced width and height, thereby reducing the horizontal and vertical movement of the occupant's line of sight. As a result, motion sickness in the occupant is further suppressed. Furthermore, because the first region 510 has a larger area than the second region 520, the sense of realism of the first content is not impaired. Furthermore, because the first region 510 is located above the second region 520, the center of the image in the first content is raised, and the orientation of the occupant's face is also raised. As a result, the contact area between the back of the occupant's head and the headrest increases, reducing vibration of the occupant's face. Furthermore, since the first area 510 is located to the left of the second area 520, the center of the first content is located in front of the occupant sitting in the left rear seat 221, which reduces the amount of lateral neck rotation and allows the occupant to adopt a comfortable posture.

[0091] 7 is a diagram showing a fourth example of video content 600 displayed on display device 41. Video content 600 includes a first area 610 located at the top of the display area and a second area 620 located at the bottom. The details of the size and proportion of first area 610 are the same as those of first area 310 in FIG. 4, and the details of the size and proportion of second area 620 are the same as those of second area 320 in FIG. 4.

[0092] The video content 600 differs from the video content 300 shown in FIG. 4 in the content of the first content. In the video content 600, the first content includes an object 601 that changes depending on the position of the first region 610. Specifically, the object 601 is a wave object that simulates a wave that changes periodically along a horizontal central axis 602 of the first region 610. The central axis 602 is a horizontally parallel axis that divides the first region 610 equally into upper and lower halves. The object 601 may move from left to right or from right to left along the central axis 602. The object 601 may be a wave object whose waveform oscillates up and down with its antinode located at the center of the central axis. Alternatively, the object 601 may be a wave object including multiple waveform groups that oscillate synchronously and have different amplitudes. These multiple waveform groups may have different brightnesses, or the brightness may change over time. In the first region 610, the background image of the object 601 is a solid black image. However, this is just an example, and the background image of the object 601 can be an image with low brightness, such as gray.

[0093] Here, the object 601 is a wave object, but this is just one example, and any object may be used as long as it changes along the central axis 602. For example, the object 601 may be a spherical object that vibrates along the central axis 602.

[0094] Furthermore, the object 601 may change periodically along a vertical central axis (not shown) of the first region 610. The vertical central axis (not shown) is an axis parallel to the vertical direction that divides the first region 610 equally into left and right halves.

[0095] Video content 600 displays an object 601 that moves along a central axis 602 in a first area 610, and has a second area 620 below it. As with video content 300, this reduces vertical line-of-sight movement and increases the contact area between the back of the head and the headrest, reducing vibrations of the passenger's face. As a result, motion sickness in passengers is suppressed.

[0096] Note that an object 601 may be displayed as the first content in the first area 410 of the video content 400 in FIG. 5 or in the first area 510 of the video content 500 in FIG.

[0097] 8 is a diagram showing a fifth example of video content 700 displayed on display device 41. Video content 700 includes a first area 710 located on the left side of the display area and a second area 720 located on the right side. The details of the size and proportion of first area 710 are the same as those of first area 410 in FIG. 5, and the details of the size and proportion of second area 720 are the same as those of second area 520 in FIG. 5.

[0098] Video content 700 displays a moving object 701 in a first area 710 and a background image of object 701 in a second area 720. The background image of object 701 is continuous with the background image of first area 710. That is, video content 700 is composed of moving images of natural scenery so that moving object 701 is displayed in first area 710. An example of object 701 is a moving object such as an animal. Object 701 moves along a vertical central axis 702 of the first area. In this example, object 701 is a squirrel. This squirrel performs actions such as hopping up and down and moving both arms holding food up and down near its mouth. In this way, the squirrel moves along central axis 702. Meanwhile, second area 720 displays the background image of object 701, thereby achieving the same effect as the black margin image shown in video contents 300, 400, 500, and 600.

[0099] This allows the occupant to focus on the first region 710, reducing horizontal line-of-sight movement of the occupant, thereby suppressing motion sickness in the occupant. Furthermore, because the first region 710 has a larger area than the second region 720, the sense of realism of the first content is not diminished. Furthermore, because the first region 710 is located to the left of the second region 720, the central axis 702 is positioned directly in front of the occupant seated in the left rear seat 221. As a result, the occupant's lateral neck rotation is reduced, allowing the occupant to adopt a more comfortable posture.

[0100] 8, the first region 710 is located on the left side and the second region 720 is located on the right side, but this is just an example, and the first region 710 may be located on the right side and the second region 720 may be located on the left side. Also, the aspect of the video content 700 of the fifth example may be applied to the video content 300 of the first example or the video content 500 of the third example.

[0101] Note that the video including the object 701 and the background image displayed in the first area 710 is an example of the first content, and the background image displayed in the second area 720 is an example of the second content. In the fifth example, the storage unit 12 may store the first content and the second content as one content without separating them.

[0102] The playback control unit 11 sets at least one of the ratio of the vertical length H1 of the first area to the second area and the ratio of the horizontal length of the first area to the second area to a predetermined ratio, which is determined based on the distance L between the display device 41 and the rear seat 220.

[0103] FIG. 9 illustrates a method for determining the vertical length H1 of the first region. The larger the area in which the image is displayed, the more realistic the viewer's sense of presence is, but the viewer must move their line of sight more when viewing. As mentioned above, in a moving vehicle, movement of the viewer's line of sight can induce motion sickness. Therefore, it is desirable to display the image only within the viewing angle of the viewer's effective field of view or stable field of fixation so that the viewer can receive visual information without moving their line of sight more significantly. Such a vertical viewing angle is at most 20 degrees in elevation and at most 25 degrees in depression. Therefore, in this embodiment, the ratio of the vertical length H1 of the first region to the vertical length H2 of the second region is determined based on the occupant's vertical field of view. Specifically, the vertical length H1 of the first region is determined based on the distance L between the rear seat 220 and the display device 41 so that the recommended elevation and depression angles are ensured. Specifically, the length H1 is determined using the following equation (1): An elevation angle of 20 degrees and a depression angle of 25 degrees are examples of predetermined viewing angles.

[0104] L*(tan20°+tan25°) ​

[0105] For example, if the distance L is 80 cm to 120 cm, the length H1 is 67 cm to 100 cm. Therefore, in this embodiment, the length H1 is set within a range of 67 cm to 100 cm at most depending on the length of the distance L.

[0106] The vertical length H2 of the second region may be determined using the length H1 determined in this manner so that the ratio between length H1 and length H2 is a predetermined ratio (for example, 7:3), or the value obtained by subtracting length H1 from the vertical length of the display region of display device 41 may be adopted.

[0107] FIG. 10 is a diagram illustrating a method for determining the horizontal length W1 of the first region. The larger the area in which the image is displayed, the more realistic the viewer's sense of presence can be, but the viewer must move their line of sight more when viewing. As mentioned above, in a moving vehicle, movement of the viewer's line of sight can induce motion sickness. Therefore, it is desirable to display the image only within the viewing angle of the viewer's effective visual field or stable fixation field so that the viewer can receive visual information without moving their line of sight significantly. Such a horizontal viewing angle is at most 30 degrees to the left and right. Therefore, in this embodiment, the ratio of the horizontal length W1 of the first region to the horizontal length W2 of the second region is determined based on the passenger's horizontal field of view. More specifically, the horizontal length W1 of the first region is determined based on the distance L between the rear seat 220 and the display device 41 so as to ensure the recommended horizontal viewing angle. Specifically, the length W1 is determined using the following equation (2). In equation (2), the horizontal viewing angle is set to 30 degrees to the left and 30 degrees to the right, for a total of 60 degrees. The 30-degree viewing angles are an example of predetermined viewing angles.

[0108] 2L*tan30°<W1 (2)

[0109] For example, if the distance L is 80 cm to 120 cm, then the length W1 is 93 cm to 139 cm. Therefore, in this embodiment, the length W1 is set to a value within a range of 93 cm to 139 cm at most. Note that if the predetermined horizontal viewing angle is 18 degrees to the left and 18 degrees to the right of the occupant, the length W1 may be set to a value within a range of 52 cm to 78 cm.

[0110] The horizontal length W2 of the second region may be determined using the length W1 determined in this manner so that the ratio between length W1 and length W2 is a predetermined ratio, or the value obtained by subtracting length W1 from the horizontal length of the display region of display device 41 may be adopted.

[0111] FIG. 11 is a flowchart showing a process performed when the video playback device 1 according to the embodiment of the present disclosure plays back video content.

[0112] First, in step S1, the playback control unit 11 selects video content by selecting a first content and a second content to be played from a plurality of first content and a plurality of second content stored in the storage unit 12. For example, the playback control unit 11 selects the first content whose playback time is closest to the travel time from the departure point to the destination input into the navigation device of the mobile object 200. The playback control unit 11 also selects a second content that is pre-recommended to be played for the selected first content. Note that the display mode of the video content including the first and second content is one of the pre-determined display modes of the video contents 300, 400, 500, 600, and 700 shown in FIGS. 4 to 8.

[0113] Next, in step S2, the playback control unit 11 outputs a control signal for playing the video content determined in step S1 to the display control unit 31, and starts playing the first and second content. As a result, the first and second content are displayed on the display device 41 using any one of the display modes of the video content 300, 400, 500, 600, and 700.

[0114] Next, in step S3, the playback control unit 11 performs a process of determining whether to switch phases. In this embodiment, the video content is switched in the order of a relax phase, a sleep phase, and a wake phase. The playback time for each phase is predetermined. Therefore, the playback control unit 11 determines whether the playback time of the video content has reached the end timing of each phase. If the playback control unit 11 determines that the playback time has reached the end timing of each content (YES in step S3), it changes the current phase to the next phase (step S4). On the other hand, if the playback control unit 11 determines that the playback time has not reached the end timing of each content (NO in step S3), the process proceeds to step S5.

[0115] The video content to be played in the next phase is specified in the video content selected in step S1, so the playback control unit 11 simply determines the specified video content as the content to be played in the next phase.

[0116] Next, in step S5, the playback control unit 11 determines whether the playback time of the video content has reached the end timing of the awakening phase. If it is determined that the playback time of the video content has reached the end timing of the awakening phase (YES in step S5), the processing ends. On the other hand, if it is determined that the playback time of the video content has not reached the end timing of the awakening phase (NO in step S5), the processing returns to step S3, and playback of the video content continues.

[0117] 12 is a flowchart illustrating a process performed by the video playback device 1 according to the embodiment of the present disclosure when switching the position of the first area depending on the seating position of the occupant. Note that in this flowchart, the display mode of the video content is assumed to be the display mode of the video content 400 shown in FIG.

[0118] In step S11, the reproduction control unit 11 detects that an occupant is seated in the rear seat 220 from the seating position information acquired by the acquisition unit 13 from the sensor 20. If an occupant is not detected as being seated in the rear seat 220 (NO in step S11), the processing ends, and if an occupant is detected as being seated (YES in step S11), the processing proceeds to step S12.

[0119] Next, in step S12, the playback control unit 11 determines, based on the seating position information, whether or not an occupant is seated only in the left rear seat 221. If it is determined that an occupant is seated only in the left rear seat 221 (YES in step S12), the playback control unit 11 sets the second area 420 to the right of the display area of ​​the display device 41 (step S16). As a result, the first area 410 is positioned to the left of the display area, and the center of the first area 410 is positioned directly in front of the occupant seated in the left rear seat 221. On the other hand, if it is determined that an occupant is not seated only in the left rear seat 221 (NO in step S12), the processing proceeds to step S13.

[0120] Next, in step S13, the playback control unit 11 determines, based on the seating position information, whether or not an occupant is seated only in the right rear seat 222. If it is determined that an occupant is seated only in the right rear seat 222 (YES in step S13), the playback control unit 11 sets the second area 420 to the left of the display area of ​​the display device 41 (step S17). As a result, the first area 410 is positioned to the right of the display area, and the center of the first area 410 is positioned directly in front of the occupant seated in the right rear seat 222. On the other hand, if it is determined that an occupant is not seated only in the right rear seat 222 (NO in step S13), the process proceeds to step S14. After step S17 is completed, the process proceeds to step S15.

[0121] Next, in step S14, the playback control unit 11 determines the display positions of the second regions on the left and right of the first region 410. In this case, the display position of the first region 410 is determined to be the center of the display region, and the display positions of a pair of second regions are determined on the left and right sides of the first region 410. The areas of the pair of second regions are equal. Furthermore, it is assumed that the horizontal length W1 of the first region 410 satisfies the condition defined in equation (2). Therefore, the horizontal length of each of the pair of second regions 420 can be half the value obtained by subtracting the length W1 from the horizontal length of the display region of the display device 41.

[0122] In step S15, the playback control unit 11 outputs a control signal to the display control unit 31 to play back the video content on the display device 41, and displays the video content on the display device 41. In this case, the first content is displayed in the first area 410, and the second content is displayed in the pair of second areas 420.

[0123] As described above, according to the video playback device 1 of the present embodiment, the display device 41 is partitioned into a first region and a second region smaller in area than the first region, with a first content including video being displayed in the first region and a second content with less movement than the first content being displayed in the second region. This allows the occupant to focus on the first content, thereby reducing the movement of the occupant's line of sight and reducing motion sickness. Furthermore, because the first region is larger in area than the second region, motion sickness can be reduced without impairing the realism of the first content.

[0124] The present disclosure is useful in the field of preventing motion sickness in passengers of moving vehicles.

Claims

1. A video playback device installed inside a moving body, comprising: a display unit including a first region and a second region; a storage unit storing a first content including video and a second content including video with a smaller amount or speed of change than the first content; and a playback control unit configured to play back the first content in the first region and the second content in the second region.

2. The video playback device according to claim 1, wherein a vertical length of the first region is longer than a vertical length of the second region.

3. The video playback device according to claim 1 or 2, wherein a horizontal length of the first region is longer than a horizontal length of the second region.

4. The video playback device according to claim 1 or 2, wherein the first content includes an object that changes according to a position of the first region.

5. The video playback device according to claim 4, wherein the object changes along a central axis in the vertical direction or the central axis in the horizontal direction of the first region.

6. The video playback device according to claim 1 or 2, wherein the playback control unit sets at least one of a ratio of vertical lengths of the first region and the second region and a ratio of horizontal lengths of the first region and the second region to a predetermined ratio.

7. The video playback device according to claim 6, wherein the moving body includes a seat facing the display unit, and the predetermined ratio is determined based on a distance between the display unit and the seat.

8. The video playback device according to claim 1 or 2, wherein the moving body includes a seat facing the display unit, and further includes an acquisition unit configured to acquire information indicating a seating position of an occupant in the seat, and the playback control unit determines a position of the second region according to the seating position.

9. The video playback device according to claim 8, wherein the seat includes a left seat located on the left side and a right seat located on the right side with respect to a traveling direction of the moving body, and the playback control unit determines the position of the second region to the right of the first region when the seating position is the left seat, determines the position of the second region to the left of the first region when the seating position is the right seat, and determines the position of the second region to the right and left of the first region when the seating position is the left seat and the right seat.

10. The vertical length of the first area or the ratio of the vertical lengths of the first area and the second area is determined based on the vertical field of view of the passengers of the moving body. The video playback device according to claim 1 or 2.

11. The horizontal length of the first area or the ratio of the horizontal lengths of the first area and the second area is determined based on the horizontal field of view of the passengers of the moving body. The video playback device according to claim 1 or 2.

12. The vertical length of the first area has a length that fits within a predetermined vertical viewing angle of the passengers of the moving body. The video playback device according to claim 1 or 2.

13. The horizontal length of the first area has a length that fits within a predetermined horizontal viewing angle of the passengers of the moving body. The video playback device according to claim 1 or 2.

14. The first content is a moving image, and the second content is a blank image of the first area. The video playback device according to claim 1 or 2.

15. The first area is located above the second area. The video playback device according to claim 1 or 2.

16. The size of the area of the first area is larger than that of the second area. The video playback device according to claim 1 or 2.

Images