JP6700484B2 - Display device for displaying virtual image - Google Patents

Description

  The present invention relates to a display device that displays a virtual image.

  For example, Patent Document 1 describes a display unit including a display and optical members such as lenses and mirrors. The display light from the display unit is reflected to the driver side by the combiner provided on the inner surface of the windshield. The driver sees the display image by superimposing it on the landscape with the display light. The position adjusting means changes the distance between the display and the optical member to move the image formation position of the display image far.

Japanese Patent Laid-Open No. 05-147456

  However, the power supply line and the signal line are connected to the display. Therefore, in order to move the display, a space for moving the power supply line, the signal line, and the like is required, which makes it difficult to reduce the size.

  It is an object of the present invention to provide a display device that can change the position where a virtual image is displayed without moving the image forming unit.

  A display device that displays a virtual image includes an image forming unit that emits a first image light, a first reflecting member that reflects the first image light and emits a second image light, and the second image forming unit. A second reflecting member that reflects image light and emits a third image light, a screen that displays an image based on the third image light, and a projection that projects the image displayed on the screen as a virtual image A first incident point of the first reflecting member on which the central ray of the first image light is incident, and a second reflecting member of the second reflecting member on which the central ray of the second image light is incident. The two incident points and the third incident point of the screen on which the central ray of the third image light is incident are on the same plane, and the screen is in a direction in which the screen approaches or separates from the projection unit. And a screen is moved in the direction, movement of at least one of the first reflecting member and the second reflecting member, a first rotation axis of the first reflecting member perpendicular to the plane. The center ray of the third image light is incident on the screen by the rotation about the center of the second reflection member and the rotation about the second rotation axis of the second reflection member perpendicular to the plane. An optical path length of the central ray of the first image light, an optical path length of the central ray of the second image light, and an optical path of the central ray of the third image light are moved while maintaining the position of the point and moving in parallel. The sum of the lengths is characterized by being constant.

  The position where the virtual image is displayed can be changed without moving the image forming unit.

1 is a configuration diagram of a display device 1 that displays a virtual image according to the first embodiment. FIG. 3 is a partial detailed view of the display device 1 that displays a virtual image according to the first embodiment. 7 is a configuration diagram of a display device 1a that displays a virtual image according to a modified example of the first embodiment. It is a partial detailed view of the display device 1a which displays the virtual image which concerns on a modification. FIG. 6 is a configuration diagram of a display device 1c that displays a virtual image according to the second embodiment. FIG. 6 is a partial detailed view of a display device 1c that displays a virtual image according to the second embodiment. FIG. 9 is a diagram of plane coordinates showing the coordinate position of the mirror according to the second embodiment. FIG. 6 is a diagram showing an example in which only the upper portion of the screen according to the first embodiment is used. 6 is a block diagram showing an example of a configuration of a display device 1c according to Embodiment 2. FIG.

  In the following description, XYZ coordinates are used to simplify the description. The X-axis direction is the left-right direction of the vehicle. The +X axis direction is on the left side with respect to the front of the vehicle. The −X axis direction is on the right side with respect to the front of the vehicle. The Y-axis direction is the vertical direction of the vehicle. The +Y axis direction is the upward direction of the vehicle. That is, the +Y axis direction is the empty direction. The −Y axis direction is the downward direction of the vehicle. That is, the -Y axis direction is the direction of the road surface. The Z-axis direction is the front-back direction of the vehicle. The +Z axis direction is the front direction of the vehicle. That is, the +Z axis direction is the direction in which the virtual image is displayed. The −Z axis direction is the rearward direction of the vehicle. The RX direction is a rotation direction with the X axis as the rotation axis. The +RX direction is clockwise when viewed from the −X axis direction. The −RX direction is counterclockwise when viewed from the −X axis direction.

Embodiment 1.
FIG. 1 is a configuration diagram of a display device 1 that displays a virtual image according to the first embodiment. FIG. 2 is a partial configuration diagram of the display device 1 that displays a virtual image according to the first embodiment.

  The display device 1 is, for example, a display device used for a head-up display (HUD) mounted on a vehicle. In the first embodiment, a windshield type head-up display is shown as an example. A windshield type head-up display reflects information on the windshield to display information within the driver's field of view. However, the display device 1 may be used for a combiner type head-up display. The combiner-type head-up display uses a half mirror (called combiner) that shows the scenery in front of the driver and the image in a superimposed manner.

  An eye box 25 is set in order to display an image in the driver's visual field. The eye box 25 is a region where the driver can visually recognize a virtual image if the eye point 2 is in the range. In FIG. 1, the eye point 2 is located at the center of the eye box 25.

  The display device 1 has a first state in which a virtual image is displayed at the first position and a second state in which a virtual image is displayed at the second position. In the drawings and the following description, the symbols may be attached with “a” or “b”. “A” indicates the first state. Moreover, "b" has shown the 2nd state. Then, when it is not necessary to indicate each state, a code omitting "a" or "b" is used. The reference numerals used in the mathematical formulas are used for the description of the embodiments and the modifications.

  In addition, image light is shown in FIGS. 1 to 8. In each drawing, each image light is indicated by the central ray of the luminous flux of the image light. A light flux is a collection of projected image light rays. The central ray is a ray located at the center of the light flux, and is a light ray passing through the center of the light flux of the image light having an angle of view. In each figure except FIG. 7, the central ray is shown by a dashed line. However, the image light 71 is shown by a solid line. The image light 72 is a virtual ray as described later.

  The display device 1 includes an image forming unit 6, a screen 11, a mirror 31, a mirror 32, and a projection unit 4.

  The image forming unit 6 emits the image light 77. The image forming unit 6 is, for example, a display device.

  The mirror 31 reflects the image light 77 emitted from the image forming unit 6 and emits the reflected light as the image light 76.

  The mirror 32 reflects the image light 76 emitted from the mirror 31 and emits the reflected light as the image light 75.

  The screen 11 displays an image based on the image light 75 emitted from the mirror 32. The screen 11 emits the image light 74 formed based on the image light 75.

  The projection unit 4 projects the image displayed on the screen 11 as a virtual image 21.

  In the above configuration, the first incident point of the mirror 31 on which the central ray of the image light 77 is incident, the second incident point of the mirror 32 on which the central ray of the image light 76 is incident, and the central ray of the image light 75 are incident. The third incident point of the screen 11 is on the same plane. In FIGS. 1 and 2, these points of incidence are on the YZ plane.

  The screen 11 moves (or translates) in a direction of approaching or separating from the projection unit 4. For example, the screen 11 moves in a direction away from the projection unit 4, and moves from the position of the screen 11a to the position of the screen 11b. Further, the screen 11 moves in the direction approaching the projection unit 4 and moves from the position of the screen 11b to the position of the screen 11a.

  When the screen 11 moves toward or away from the projection unit 4, movement (or translational movement) of at least one of the mirror 31 and the mirror 32 (the mirror 32 in the first embodiment) is performed on the plane of the mirror 31. Due to the rotation about the vertical rotation axis 101 and the rotation about the rotation axis 102 of the mirror 32 perpendicular to the plane, the center ray of the image light 75 maintains the position of the third incident point on the screen 11. Then, the optical path length of the central ray of the image light 77, the optical path length of the central ray of the image light 76, and the optical path length of the central ray of the image light 75 are constant. The rotation axis 101 of the mirror 31 includes, for example, the first incident point and is fixed.

  Next, the first state will be described while further describing the configuration of the display device 1.

  The image forming unit 6 projects image light. "Image light" is light having image information. The image forming unit 6 projects the image light 75 on the screen 11.

  The image forming unit 6 is, for example, a projector that uses a DMD (Digital Micromirror Device) and a projection lens. Further, the image forming unit 6 may scan the laser beam to form an image on the screen 11, for example.

  The image forming unit 6 emits the image light 77 from the area 61. The area 61 is an area from which the image light 77 is emitted. In FIG. 1, the image light 77 is emitted from the image forming unit 6 in the +Z axis direction. For example, the central ray of the image light 77 is parallel to the Z axis.

  The image light 77 reaches the mirror 31a. Then, the image light 77 is reflected by the mirror 31a. The image light 76a is the image light 77 reflected by the mirror 31a. The mirror 31a reflects the image light 77 emitted from the image forming unit 6.

  The mirror 31a reflects the central ray of the image light 77 at 90 degrees. That is, the incident angle of the central ray of the image light 77 on the mirror 31a is 45 degrees. The reflection angle of the central ray of the image light 76a with respect to the mirror 31a is also 45 degrees. In FIG. 1, the image light 76a travels in the +Y axis direction. For example, the center ray of the image light 76a is parallel to the Y axis.

  The image light 76a reaches the mirror 32a. Then, the image light 76a is reflected by the mirror 32a. The image light 75a is the image light 76a reflected by the mirror 32a. The mirror 32a reflects the image light 76a reflected by the mirror 31a.

  The mirror 32a reflects the central ray of the image light 76a at 90 degrees. That is, the incident angle of the central ray of the image light 76a on the mirror 32a is 45 degrees. Further, the reflection angle of the central ray of the image light 75a with respect to the mirror 32a is also 45 degrees. In FIG. 1, the image light 75a travels in the +Z axis direction. For example, the central ray of the image light 75a is parallel to the Z axis.

  The image light 75a reaches the screen 11a. Then, the image information included in the image light 75a is displayed on the screen 11a.

  An image is displayed on the screen 11 based on the image light 77 projected from the image forming unit 6. The screen 11 has, for example, a screen surface, and the screen surface is a plane perpendicular to the central ray of the image light 75. In the first state, the screen surface of the screen 11a is, for example, a plane perpendicular to the central ray of the image light 75a.

  The screen 11 is, for example, a transmissive screen. The screen 11 is, for example, a microlens array.

  The image light 74 emitted from the screen 11 is formed based on the image light 77. The image light 74 emitted from the screen 11 reaches the projection unit (or the projection unit) 4. In FIG. 1, the image light 74a travels in the +Z axis direction. For example, the center ray of the image light 74a is parallel to the Z axis.

  As will be described later, the central ray of the image light 74a in the first state matches the central ray of the image light 74b in the second state. Therefore, the description of the image light 74b will be substituted by the description of the image light 74a. The optical path length of the central ray of the image light 74a is different from the optical path length of the central ray of the image light 74b. In the first embodiment, the optical path length of the central ray of the image light 74a is shorter than the optical path length of the central ray of the image light 74b.

  The projection unit 4 projects the image formed on the screen 11. Then, the projection unit 4 forms a virtual image. In the first embodiment, for example, the projection unit 4 is a concave mirror.

  The image light 74a reaches the projection unit 4. Then, the projection unit 4 emits the image light 73. In FIG. 1, the image light 73 travels in the +Y axis direction. The central ray of the image light 73 does not necessarily have to be parallel to the Y axis.

  The image light 73 projected by the projection unit 4 reaches the windshield 3, for example. The image light 73 reflected by the projection unit 4 reaches the windshield 3, for example. The image light 73 reaching the windshield 3 is reflected by the windshield 3. In FIG. 1, the image light 71 travels in the −Z axis direction. The central ray of the image light 71 does not necessarily have to be parallel to the Z axis.

  The image light 71 reflected by the windshield 3 reaches the eye box 25 of the driver. The image light 71 is the image light 73 reflected by the windshield 3.

  The image light 71 allows the driver to visually recognize the virtual image 21a. The distance from the eye point 2 to the virtual image 21a is the distance L1. The distance L1 is determined by the total optical path length of the image light 74a and the image light 73.

  The image light 72 is not actual light. It is provisional light obtained by extending the image light 71 toward the virtual images 21a and 21b. Further, the center rays of the image light 73 and the image lights 72 and 71 after that are overlapped in the first state and the second state. Therefore, “a” or “b” is not added to the image lights 73, 72, 71.

  For example, when the image forming unit 6 is a projector, the display distance is fixed. That is, the distance from the image forming unit 6 to the screen 11 is fixed. In the display device 1, the total of the optical path length of the image light 77, the optical path length of the image light 76a and the optical path length of the image light 75a is determined.

  As will be described later, the total of the optical path length of the image light 77, the optical path length of the image light 76b, and the optical path length of the image light 75b is determined. The sum of the optical path lengths of the image light 76a and the image light 75a is equal to the total of the optical path length of the image light 76b and the image light 75b. The optical path length of the image light 77 is the same in the first state and the second state.

  In this way, the image forming unit 6 can display the focused image on the screen 11 according to the determined display distance.

  Next, the operation from the first state to the second state will be described based on FIG.

  The screen 11 moves in the direction of the central ray of the image light 75. Then, the screen 11a moves to the mirror 32 side. That is, as shown in FIG. 2, the screen 11a moves in the −Z direction. The screen 11 before moving is the screen 11a. The screen 11 after the movement is the screen 11b.

  The screen 11a and the screen 11b are parallel to each other. That is, the screen 11 is moving in the direction perpendicular to the screen surface. The center ray of the image light 75 is perpendicular to the screen 11. In FIG. 2, for example, the direction perpendicular to the screen surface of the screen 11 is the Z-axis direction.

According to the movement of the screen, the mirror 31 rotates about the rotation axis (or rotation center) 101. That is, according to this movement, the mirror 31a rotates about the rotation center 101. The mirror 31a rotates in the −RX direction. The rotation angle is the angle A ₁ . The mirror 31 before rotation is the mirror 31a. The mirror 31 after rotation is the mirror 31b.

  The rotation center 101 is perpendicular to the plane containing the central ray of the image light 77 and the central ray of the image light 76a. Further, the rotation center 101 is perpendicular to a plane including the central ray of the image light 77 and the central ray of the image light 76b. In FIG. 2, for example, the rotation center 101 is parallel to the X axis.

  The rotation center 101 is located on the reflecting surface of the mirror 31, for example. The rotation center 101 intersects with the center ray of the image light 77, for example. In this case, the optical path length of the image light 77 does not change between the first state and the second state.

  Further, the mirror 32 moves in a direction perpendicular to the screen surface of the screen 11. The direction perpendicular to the screen surface of the screen 11 is the Z-axis direction. The direction perpendicular to the screen surface of the screen 11 is parallel to the central ray of the image light 75. Then, the mirror 32a moves in the direction opposite to the screen 11a side. The mirror 32a moves in the −Z axis direction.

Further, the mirror 32 rotates about a rotation axis (or rotation center) 102. The mirror 32a rotates in the −RX direction. The rotation angle is the angle A ₂ . The mirror 32 before rotation is the mirror 32a. The mirror 32 after rotation is the mirror 32b.

  The rotation center 102 is, for example, parallel to the rotation center 101. That is, the center of rotation 102 is perpendicular to the plane containing the center ray of the image light 77 and the center rays of the image lights 76a and 76b. Further, the rotation center 102 is perpendicular to a plane including the center rays of the image lights 76a and 76b and the center rays of the image lights 75a and 75b. In FIG. 2, for example, the rotation center 102 is parallel to the X axis. The central ray of the image light 75a and the central ray of the image light 75b overlap each other.

  The rotation center 102 is located on the reflecting surface of the mirror 32, for example. The rotation center 102 intersects with the center ray of the image light 76, for example. That is, the rotation center 102a intersects with the center ray of the image light 76a, for example. The rotation center 102b intersects with the center ray of the image light 76b, for example.

  The mirror 32 before movement and before rotation is the mirror 32a. The mirror 32 after the movement and the rotation is the mirror 32b.

  By this operation, the screen 11 moves to the position of the screen 11b. Further, the mirror 31 moves to the position of the mirror 31b. The mirror 32 moves to the position of the mirror 32b.

  Here, the operation from the first state to the second state has been described. However, by performing the reverse operation, the operation from the second state to the first state is possible.

The angle A ₁ is equal to the angle A ₂ . That is, the relationship between the angle A ₁ and the angle A ₂ is the relationship of Expression 1.
A ₁ =A ₂ (1)

The distance to the center of rotation 102a from the rotation center 101 in the first state and the distance _{L 3.} The distance from the rotation center 101 to the rotation center 102b in the second state is defined as the distance L ₄ . The optical path length of the image light 76b is the distance L ₄ . The moving distance of the mirror 32 is set to a distance L ₅ . That is, the distance from the rotation center 102a to the rotation center 102b is defined as the distance L ₅ . The moving distance of the screen 11 is set to a distance L ₆ .

The movement amount (distance L ₅ ) of the mirror 32 is determined by the sum of the optical path length of the image light 77a, the optical path length of the image light 76a (distance L ₃ ) and the optical path length of the image light 75a. It is determined so as to match the total of the optical path length (distance L ₄ ) of 76b and the optical path length of the image light 75b.

That is, the relationship of the following Expression 2 is satisfied.
(L ₄ +L ₅ )-L ₃ =L ₆ (2)
_{L 5 = L 3 + L 6} -L 4 ··· (2a)

Also, the following relationship holds.
L ₄ ² =L ₃ ² +L ₅ ² (3)

Substituting equation 3 into equation 2a,
L ₅ =L ₃ +L ₆ −(L ₃ ² +L ₅ ² ) ^0.5 (4)
L ₃ +L ₆ −L ₅ =(L ₃ ² +L ₅ ² ) ^0.5
(L ₃ +L ₆ ) ² −2×(L ₃ +L ₆ )×L ₅ +L ₅ ² =L ₃ ² +L ₅ ²
L ₅ ={(L ₃ +L ₆ ) ^2- L ₃ ² }/{2×(L ₃ +L ₆ )}
L ₅ =(2×L ₃ +L ₆ )×L ₆ /{2×(L ₃ +L ₆ )} (4a)

The angle formed by the central ray of the image light 76a and the central ray of the image light 76b is twice the angle A ₁ . Therefore, the following relationship holds.
L ₅ =L ₃ ×tan(2×A ₁ )... (5)
tan(2×A ₁ )=L ₅ /L ₃
A ₁ =(1/2)×tan ⁻¹ (L ₅ /L ₃ ).
A ₁ =(1/2)×tan ⁻¹ [(2×L ₃ +L ₆ )×L ₆ /{2×L ₃ ×(L ₃ +L ₆ )}]...(5a)

The distance L ₆ is determined by the moving amount of the virtual image 21. The moving amount of the virtual image 21 is L ₂ −L ₁ . The distance L ₃ is a design value. The distance L ₅ is obtained from the equation 4a. The angle A ₁ is obtained from the equation 5a. The angle A ₂ is obtained from the expression 1. The angle A ₂ is equal to the angle A ₁ .

  Accordingly, the distance from the eyepoint 2 to the virtual image 21 (or the position of the virtual image 21) can be changed without moving the image forming unit 6.

<Modification>

  FIG. 3 is a configuration diagram of a display device 1a that displays a virtual image according to the modification. FIG. 4 is a partial configuration diagram of a display device 1a that displays a virtual image according to the modification. In the modification, the first state is the same as the first state described with reference to FIGS.

  In the display device 1a of the modified example, the screen 11 and the mirror 32 integrally rotate in the first direction. The first rotation is rotation about the rotation axis (or rotation center) 103. The rotation center 103 is, for example, an end of the screen 11 on the −Y axis direction side. The rotation center 103 is, for example, parallel to the X axis. That is, the rotation center 103 is perpendicular to the plane including the central ray of the image light 77a and the central ray of the image light 76a.

  Further, the mirror 32 makes a second rotation different from the first rotation. That is, the mirror 32 makes the second rotation independently of the screen 11. The rotation center of the second rotation is the rotation axis (or rotation center) 105. The rotation center 105 is, for example, parallel to the X axis. The rotation center 105 is located on the reflecting surface of the mirror 32. The rotation center 105 intersects with the center ray of the image light 76. In the first state, the rotation center 105a intersects the center ray of the image light 76a. In the second state, the rotation center 105b intersects the center ray of the image light 76b.

  The mirror 31 moves in the direction of the central ray of the image light 77. Further, the mirror 31 rotates about a rotation axis (or rotation center) 104. The rotation center 104 is, for example, parallel to the X axis. The rotation center 104 is located on the reflection surface of the mirror 31. The rotation center 104 intersects with the center ray of the image light 77, for example.

  The rotation center 104 corresponds to the rotation center 101 of the display device 1. The rotation center 105 corresponds to the rotation center 102 of the display device 1.

  In the modification, the image light 77 in the first state is shown as the image light 77a. Further, the image light 77 in the second state is shown as image light 77b. The central ray of the image light 77a and the central ray of the image light 77b overlap each other. However, the optical path length of the image light 77a is shorter than the optical path length of the image light 77b.

  Next, the operation from the first state to the second state will be described based on FIG.

In FIG. 4, the screen 11 and the mirror 32 rotate about the rotation center 103. The rotation direction is the -RX direction. The rotation angle is the angle A ₅ . The screen 11 before rotation is the screen 11a. The screen 11 after the rotation is the screen 11b.

In response to this movement, the mirror 32 rotates about the rotation center 105. The rotation direction is the -RX direction. The rotation angle is the angle A ₆ . That is, the mirror 32 rotates by the angle A ₄ from the first state. The angle A ₄ is a value obtained by adding the angle A ₅ and the angle A ₆ . The mirror 32 before rotation is the mirror 32a. The mirror 32 after rotation is the mirror 32b.

  The mirror 31 moves in the direction of the central ray of the image light 77. The mirror 31a moves in a direction in which the optical path length of the image light 77 becomes longer. In FIG. 4, the mirror 31a moves in the +Z axis direction.

Further, the mirror 31 rotates around the rotation center 104. The rotation direction is the -RX direction. The rotation angle is the angle A ₃ . The mirror 31 in the first state is the mirror 31a. The mirror 31 in the second state is the mirror 31b.

  By this operation, the screen 11 moves to the position of the screen 11b. The mirror 31 moves to the position of the mirror 31b. The mirror 32 moves to the position of the mirror 32b.

Relationship between the rotation angle A ₅ of the rotation angle A ₃ and the screen 11 of the mirror 31 are in a relation of the following equation 6.
A ₃ =(1/2)×A ₅ +A ₆ (6)

The angle between the center ray of the image light 76a and the center ray of the image light 76b is referred to as an angle A ₇ . The angle between the line segment connecting the rotation center 103 and the rotation center 105a and the center ray of the image light 75a is defined as an angle A ₈ .

A distance from the rotation center 104a in the first state to the rotation center 104b in the second state is a distance L ₇ . That is, the movement amount of the mirror 31 is set to L ₇ . A distance from the screen 11a to the rotation center 105a is set to a distance L ₈ . The distance from the intersection of the central ray of the image light 75a and the screen 11a to the rotation center 103 of the screen 11 is defined as a distance L ₉ . The optical path length (length of the central ray) of the image light 76b is set to a distance L ₁₀ . The distance from the screen 11a to the rotation center 105b is defined as a distance L ₁₁ .

The movement amount L ₇ of the mirror 31 is determined by the sum of the optical path length of the image light 77a, the optical path length of the image light 76a and the optical path length of the image light 75a. It is decided to match the total optical path length of.

The optical path length of the image light 75a (the length of the central ray) is equal to the optical path length of the image light 75b (the length of the central ray). That is, the relationship of the following Expression 7 is satisfied.
L ₃ =(L ₇ +L ₁₀ )... (7)

Also, the following relationship holds.
_{tan (A 8) = L 9} / L 8 ··· (7a)
The following expression 7b is obtained from the expression 7a.
^{_{A 8 = tan -1 (L 9}} / L 8) ··· (7b)

The distance from the rotation center 103 to the rotation center 105b is equal to the distance from the rotation center 103 to the rotation center 105a. Further, the angle formed by the line segment connecting the rotation center 103 and the rotation center 105a and the line segment connecting the rotation center 103 and the rotation center 105b is equal to the angle A ₅ .

The distance L ₁₁ is represented by the following Expression 8. Then, by substituting the equation 7b into the following equation 8, the distance L ₁₁ is obtained.
L ₁₁ =(L ₈ ² +L ₉ ² ) ^0.5 ×cos(A ₈ −A ₅ )...(8)

Also, the following relationship holds.
tan(A ₇ )=(L ₁₁ −L ₈ )/{(L ₈ ² +L ₉ ² ) ^0.5 ×sin(A ₈ −A ₅ )} (9a)
A ₇ =tan ⁻¹ [(L ₁₁ −L ₈ )/{(L ₈ ² +L ₉ ² ) ^0.5 ×sin(A ₈ −A ₅ )}] (9b)
By substituting the equations 7b and 8 into the equation 9b, the angle A ₇ is obtained.

Also, the following relationship holds.
_{L 10 × cos (A 7)} = L 3 -L 9 + (L 8 2 + L 9 2) 0.5 × sin (A 8 -A 5) ··· (10a)
_{L 10 = {L 3 -L 9} + (L 8 2 + L 9 2) 0.5 × sin (A 8 -A 5)} / cos (A 7) ··· (10b)
By substituting the equation 9b into the equation 10b, the distance L ₁₀ is obtained.

From Expression 7, the following Expression 11 is obtained.
_{L 7 = L 3 -L 10 ···} (11)
By substituting the value of the distance L _{10 in} the expression 10b into the expression 11, the distance L ₇ is obtained as in the following expression 11a.
L ₇ =L ₃ −{L ₃ −L ₉ +(L ₈ ² +L ₉ ² ) ^0.5 ×sin(A ₈ −A ₅ )}/cos(A ₇ )...(11a)

Also, the following relationship holds.
A ₇ =2×A ₃ (12a)
A ₃ =A ₇ /2 (12b)
By substituting the value of the angle A ₇ of the expression 9b into the expression 12b, the angle A ₃ is obtained as the following expression 12c.
A ₃ =(1/2)×tan ⁻¹ [(L ₁₁ −L ₈ )/{(L ₈ ² +L ₉ ² ) ^0.5 ×sin(A ₈ −A ₅ )}]...(12c)

Equation 6 to Equation 13 are obtained. By substituting the value of the angle A ₃ of the expression 12b into the expression 13, the expression 13a is obtained. By substituting the expression 9b into the expression 13a, the angle A ₆ is obtained (expression 13b).
A ₆ =A ₃ −(1/2)×A ₅ (13)
_{A 6 = (1/2) × A} 7 - (1/2) × A 5 ··· (13a)
A ₆ =(1/2)×tan ⁻¹ [(L ₁₁ −L ₈ )/{(L ₈ ² +L ₉ ² ) ^0.5 ×sin(A ₈ −A ₅ )}]−(1/2) ×A ₅ ...(13b)

The distances L ₃ , L ₈ and L ₉ are design values. The angle A ₅ is determined from the tilt angle of the virtual image 21b. The angle A ₈ is obtained from the distance L ₈ and the distance L ₉ by the expression 7b. The distance L ₁₁ is calculated from the distance L ₈ , the distance L ₉ , the angle A ₅ and the angle A ₈ by the equation 8. The angle A ₇ is obtained from the distance L ₈ , the distance L ₉ , the distance L ₁₁ , the angle A _5, and the angle A ₈ by the equation 9b. The distance _{L 10} is, by the expression 10b, the distance _{L 3,} the distance _{L 8,} the distance _{L 9,} angle _{A 5,} is determined from the angle _{A 8} and angle _{A 7.} The distance L ₇ is obtained from the distance L ₃ and the distance L ₁₀ by the equation 11. The angle A ₃ is obtained from the angle A _{7 according} to the equation 12b. The angle A ₆ is obtained from the angle A ₃ and the angle A ₅ by the equation 13.

  The screen 11b is inclined with respect to the central ray of the image light 74. Therefore, the virtual image 21b is displayed so as to be inclined with respect to the central ray of the image light 72. For example, when the virtual image 21a is a vertically displayed virtual image, the virtual image 21b is a virtual image inclined forward (+Z axis direction).

As described above, in the display device 1, the screen 11 moves in the direction of the central ray of the image light 75. The mirror 31 rotates at an angle A ₁ . The mirror 32 moves in the direction of the central ray of the image light 75. Then, the mirror 32 rotates at the angle A ₂ . With these, the position where the virtual image is displayed can be changed without moving the image forming unit (or the display).

  Further, in the display device 1 a, the screen 11 and the mirror 32 rotate around the rotation center 103. Further, the mirror 32 rotates about the rotation center 105. The mirror 31 moves in the direction of the central ray of the image light 77. Then, the mirror 31 rotates about the rotation center 104. With these, the position where the virtual image is displayed can be changed without moving the image forming unit (or the display).

  Further, for example, the image light 77 is the first image light. The image light 76 is the second image light. The image light 75 is the third image light. The mirror 31 is a first reflecting member. The mirror 32 is a second reflecting member. The rotation center 101 is the first rotation axis. The rotation center 102 is the second rotation axis. The rotation center 103 is the third rotation axis.

Embodiment 2.
FIG. 5 is a configuration diagram of a display device 1c that displays a virtual image according to the second embodiment. FIG. 6 is a partial configuration diagram of a display device 1c that displays a virtual image according to the second embodiment. The configuration of the second embodiment is the same as that of the first embodiment except the display device 1c. In the following description, elements that are the same as or correspond to those in the first embodiment are designated by the same reference numerals, and differences from the first embodiment will be mainly described.

  In the first embodiment, the center ray of the third image light 75 is perpendicular to the screen 11, but in the second embodiment, the center ray of the third image light 75 is to the screen 11. Not vertical. In the second embodiment, the angle formed by the straight line perpendicular to the screen 11 (that is, the normal line of the screen 11) and the central ray of the third image light 75 is set to the angle θ. Therefore, the third image light 75 is obliquely projected on the screen 11.

  The mirror 31 rotates around the first incident point R1. The mirror 31 rotates about a first rotation axis that includes the first incident point R1 and is perpendicular to the YZ plane. The mirror 31 in the first state is the mirror 31a. The mirror 31 in the second state is the mirror 31b.

  At the first incident point R1 on the reflecting surface of the mirror 31, for example, the central ray of the image light 77 is incident on the mirror 31. In this case, the optical path length of the image light 77 does not change between the first state and the second state.

  The mirror 32 rotates and moves (or translates). The mirror 32 rotates about a second rotation axis that includes the second incident point R2 and is perpendicular to the YZ plane. The mirror 32 in the first state is the mirror 32a. The mirror 32 in the second state is the mirror 32b.

  The central ray of the image light 76 is incident on the second incident point R2 on the reflecting surface of the mirror 32. The central ray of the image light 75 is emitted as reflected light from the second incident point R2.

  The screen 11 translates in a direction of approaching or separating from the projection unit 4. The moving direction of the screen 11 is +Z direction or −Z direction. The moving direction is not limited to this, and may be any direction that causes a change in the optical path length of the image light 74. The screen 11 moves while maintaining a state perpendicular to the image light 74. The screen 11 in the first state is the screen 11a. The screen 11 in the second state is the screen 11b.

  The screen 11 has a screen surface, and the screen surface is a plane whose angle between the normal line and the central ray of the image light 75 is an angle θ. The center ray of the image light 75 is incident on the screen 11 at the third incident point R3.

  When the screen 11 moves, the mirror 31 rotates, and the mirror 32 rotates and moves (or translates), so that the central ray of the image light 75 maintains the position of the third incident point R3 with respect to the screen 11. While moving in parallel.

  The first incident point R1, the second incident point R2, and the third incident point R3 are on the same plane. In FIG. 6, for example, the first incident point R1, the second incident point R2, and the third incident point R3 are on the YZ plane.

  When the screen 11 moves toward or away from the projection unit 4, the third incident point R3 is held at a fixed position on the screen 11, and the first incident point R1 is the image light 77. The second incident point R2, which is located at the intersection of the central ray and the reflecting surface of the mirror 31, passes through the third incident point R3 and forms an image on a straight line forming an angle θ with respect to the normal line of the screen 11. The sum of the distance from the part 6 to the first incident point R1, the distance from the first incident point R1 to the second incident point R2, and the distance from the second incident point R2 to the third incident point R3 is It is located at a fixed point on the reflecting surface of the mirror 32.

  The mirror 31 reflects the central ray of the image light 77 at the first incident point R1 and is arranged so that the central ray of the image light 76 is directed to the second incident point R2. The mirror 32 reflects the central ray of the image light 76 at the second incident point R2, and is arranged so that the central ray of the image light 75 is directed to the third incident point R3. The first rotation axis includes the first incident point R1 and is fixed.

  Next, the operation from the first state to the second state will be described based on FIG.

  In FIG. 6, the screen 11 moves in translation. The moving direction is the -Z direction. The screen 11 before translational movement is the screen 11a. The screen 11 after the translational movement is the screen 11b.

In response to this movement, the mirror 32 rotates and moves. The rotation direction is the -RX direction. The rotation angle is the angle A ₉ . The moving direction is the -Z direction. The mirror 32 before rotation and movement is the mirror 32a. The mirror 32 after rotation and movement is the mirror 32b.

The mirror 31 rotates around the first incident point R1. The rotation direction is the -RX direction. The rotation angle is the angle A ₁₀ . The mirror 31 before rotation is the mirror 31a. The mirror 31 after rotation is the mirror 31b.

  By this operation, the screen 11 moves to the position of the screen 11b. The mirror 32 moves to the position of the mirror 32b. The mirror 31 moves to the position of the mirror 31b.

  Here, the operation from the first state to the second state has been described. However, by performing the reverse operation, the operation from the second state to the first state is possible.

The rotation angle A ₁₀ of the mirror 31 and the rotation angle A ₉ of the mirror 32 are equal. That is, the angle A ₁₀ and the angle A ₉ have the relationship of Expression 15.
A ₁₀ =A ₉ (15)

  The movement position of the mirror 32 is determined so that the optical path lengths of the central rays of the image light in the first state and the second state are equal. In FIG. 6, the optical path length of the image light 77 does not change between the first state and the second state. Therefore, at the moving position of the mirror 32, the sum of the optical path length of the image light 77, the optical path length of the image light 76a and the optical path length of the image light 75a is such that the optical path length of the image light 77, the optical path length of the image light 76b and the image light 75b. It is decided to match the total optical path length of.

  Next, a method of calculating the movement position of the mirror 32 will be described. FIG. 7 is a plane coordinate diagram showing the coordinate position of the mirror. Yz coordinates are used to simplify the description. The incident point R1, the incident point R2, and the incident point R3 are on the yz plane. The yz coordinate system is equal to a coordinate system in which the YZ coordinate system of the XYZ coordinate system is rotated clockwise by an angle θ and the positive and negative signs in the Z direction are reversed. That is, the y-axis is equal to the axis obtained by rotating the Y-axis clockwise by the angle θ, the z-axis rotates the Z-axis clockwise by the angle θ, and the positive and negative directions of the Z-axis are reversed. Is equal to the axis obtained by. In the yz coordinate system, when the z coordinate value of the point P is a and the y coordinate value of the point P is b, the coordinates of the point P are expressed as (a, b).

  The origin (0, 0) of the yz coordinate system is the incident point R1. The coordinates of the incident point R2a in the first state are (0, n1). The coordinates of the incident point R2b in the second state are (z2,n2). The coordinates of the incident point R3a in the first state are (m1, n1). The coordinates of the incident point R3b in the second state are (m2, n2).

  A dotted line connecting the incident point R1 and the incident point R2a represents the central ray of the image light 76a in the first state. A dotted line connecting the incident point R2a and the incident point R3a represents the central ray of the image light 75a in the first state. The broken line connecting the incident point R1 and the incident point R2b represents the central ray of the image light 76b in the second state. The broken line connecting the incident point R2b and the incident point R3b represents the central ray of the image light 75b in the second state. The central ray of the image light 77 is omitted because it is the same in the first state and the second state. Hereinafter, the length obtained by removing the optical path length of the image light 77 from the optical path length of the image light from the image forming unit 6 to the screen 11 is referred to as the total optical path length L.

  In order to simplify the explanation, in the first state, the incident point R2a is on the y-axis, and the central ray of the image light 75a is parallel to the z-axis. At this time, the value of the z coordinate of the incident point R2a becomes 0. The y-coordinate value of the incident point R2a is equal to the y-coordinate value n1 of the incident point R3a. Further, since the image light 75a moves in parallel, the image light 75b also becomes parallel to the z axis. Therefore, the y coordinate value of the incident point R2b becomes equal to the y coordinate value n2 of the incident point R3b.

The total optical path length L in the first state is the sum of the distances between the center ray of the image light 76a and the center ray of the image light 75a, and satisfies the following expression 16.
L=n1-m1 (16)

The total optical path length L in the first state and the total optical path length L in the second state are equal. The total optical path length L in the second state is the sum of the distances between the center ray of the image light 76b and the center ray of the image light 75b, and satisfies the following expression 17.
^{L = (z2-m2) +} (z2 2 + n2 2) 0.5 ··· (17)
When Formula 17 is summarized with respect to the z coordinate value z2 of the incident point R2b, the following Formula 18 is obtained.
z2={(L+m2) ² −n2 ² }/{2×(L+m2)} (18)

  By substituting the equation 16 into the equation 18, the z coordinate value z2 of the incident point R2b is obtained.

Further, regarding the angle A ₁₁ formed by the central ray of the image light 76a and the central ray of the image light 76b, the relationship of the following Expression 19 is established.
tan(A ₁₁ )=z2/n2...(19)
A ₁₁ =tan ⁻¹ (z2/n2) (20)

Since the angle A ₁₁ is the rotation angle of the reflected light of the mirror 31 corresponding to the rotation angle A ₁₀ of the mirror 31, the relationship of the following Expression 21 is established.
A ₁₀ =1/2×A ₁₁ (21)

By substituting the equation 20 into the equation 21, the rotation angle A _{10 of the} mirror 31 can be obtained by the following equation 22.
A ₁₀ =1/2×tan ⁻¹ (z2/n2) (22)
Further, from equation 15, since the rotation angle _{A 9} of the rotation angle _{A 10} and the mirror 32 of the mirror 31 are equal, the rotational angle _{A 9} of the mirror 32 is also obtained.

The coordinates (m1, n1) of the incident point R3a in the first state are the coordinate position of the screen 11 before the movement and are design values. From Expression 16, the total optical path length L is obtained. The coordinates (m2, n2) of the incident point R3b in the second state are the coordinate position of the screen 11 after the movement and are design values. From the total optical path length L and Expression 18, the z coordinate value z2 of the incident point R2b is obtained. The rotation angle A ₁₀ of the mirror 31 is obtained from the z coordinate value z2 of the incident point R2b and the expression 22. The rotation angle A ₉ of the mirror 32 is obtained from the rotation angle A ₁₀ and the expression 15.

  As described above, the distance from the eyepoint 2 to the virtual image 21 (or the position of the virtual image 21) can be changed without moving the image forming unit 6.

  Further, the mirror 31 may be moved (or translated). For example, the mirror 31 may be moved in the direction of the central ray of the image light 77. Also in this case, the mirror 31 and the mirror 32 operate so that the optical path length of the image light from the image forming unit 6 to the screen 11 becomes constant. The display device 1c includes movement (or translational movement) of the mirror 31, rotation about the first rotation axis of the mirror 31, and movement of the screen 11 when the screen 11 moves toward or away from the projection unit 4. By the rotation of 32 about the second rotation axis, the central ray of the image light 75 moves in parallel while maintaining the position of the third incident point R3 with respect to the screen 11, and the optical path length of the central ray of the image light 77. The sum of the optical path length of the central ray of the image light 76 and the optical path length of the central ray of the image light 75 may be constant. For example, when the screen 11 moves toward or away from the projection unit 4, the third incident point R3 is held at a fixed position on the screen 11, and the second incident point R2 is the third position. Is located at the intersection of a straight line passing through the incident point R3 of the screen 11 and forming an angle θ with respect to the normal line of the screen 11 and the reflecting surface of the mirror 32, and the first incident point R1 is on the central ray of the image light 77. The distance from the image forming unit 6 to the first incident point R1, the distance from the first incident point R1 to the second incident point R2, and the distance from the second incident point R2 to the third incident point R3. It is located at a point on the reflecting surface of the mirror 31 where the sum is constant. In this case, in one example, the display device 1c is configured such that both the mirror 31 and the mirror 32 move (or translate). In another example, the display device 1c is configured such that, of the mirror 31 and the mirror 32, only the mirror 31 moves (or translates).

In the above description, the case where the angle θ is not 0 is shown, but the angle θ may be 0. Hereinafter, a method of calculating the movement position of the mirror 32 when the angle θ formed by the straight line perpendicular to the screen 11 and the central ray of the third image light 75 is 0 will be described. The y-coordinate value n1 of the incident point R3a in the first state and the y-coordinate value n2 of the incident point R3b in the second state are equal, and the relationship of the following Expression 23 is established.
n2=n1 (23)

By substituting the equations 16 and 23 into the equation 18, the following equation 24 is obtained.
^{z2 = {(n1-m1 +} m2) 2 -n1 2} / {2 × (n1-m1 + m2)} ··· (24)

The distance of the central ray of the image light 76a _{L 3,} since equal y-coordinate value n1 of the incident point R2a, the following expression is established 25.
L ₃ =n1 (25)

Since the moving distance L ₆ of the screen 11 is equal to the distance between the incident point R3b and the incident point R3a, the following expression 26 is established.
^{_{L 6 = {(m2-m1}} ) 2 + (n2-n1) 2} 0.5 ··· (26)
By substituting the equation 23 into the equation 26, the following equation 27 is obtained.
L ₆ =m2-m1 (27)

Since the moving distance L ₅ of the mirror 32 is equal to the distance between the incident point R2b and the incident point R2a, the following expression 28 holds.
L ₅ ={z2 ² +(n2-n1) ² } ^0.5 ...(28)
By substituting the equation 23 into the equation 28, the following equation 29 is obtained.
L ₅ =z2 (29)

By substituting the equations 25, 27 and 29 into the equation 24, the following equation 30a is obtained.
^{_{L 5 = {(L 6 +}} L 3) 2 -L 3 2} / {2 × (L 6 + L 3)} ··· (30)
L ₅ =(2×L ₃ +L ₆ )×L ₆ /{2×(L ₃ +L ₆ )}...(30a)

  Equation 30a is equal to Equation 4a. Therefore, in the second embodiment, when the angle θ formed by the straight line perpendicular to the screen 11 and the central ray of the third image light 75 is set to 0, the arrangement of the image forming unit 6 and the like are excluded. This is equivalent to the form 1.

  FIG. 8 is an example in which only the upper portion of the screen 11 of the first embodiment is used. The central ray 75 of the image light projected on the screen 11 is obliquely projected on the screen 11. On the other hand, the optical axis 80 of the image forming unit 6 is perpendicular to the screen 11.

  The optical path length of the central ray of the image light from the image forming unit 6 to the screen 11 is the same in the case of the screen 11a and the case of the screen 11b. At the same time, the optical path length of the optical axis of the optical system of the display device 1 is the same between the screen 11a and the screen 11b. That is, the projection using only the upper portion of the screen 11 in the display device 1 of the first embodiment has the same effect as that of the second embodiment.

  FIG. 9 is a block diagram showing an example of the configuration of the display device 1c according to the second embodiment. In the example of FIG. 9, the display device 1c has a drive unit 90 that drives the screen 11, the mirror 31, and the mirror 32.

  The drive unit 90 drives the screen 11, the mirror 31, and the mirror 32 so that they operate as described above. The drive unit 90 moves the screen 11 in a direction of approaching or separating from the projection unit 4. At this time, the drive unit 90 moves in parallel while the center ray of the image light 75 maintains the position of the third incident point R3 with respect to the screen 11, and the optical path length of the center ray of the image light 77 and the center of the image light 76. The mirror 31 and the mirror 32 are moved so that the sum of the optical path length of the light beam and the optical path length of the central light beam of the image light 75 becomes constant.

  The drive unit 90 includes, for example, a drive mechanism 91 that drives the screen 11, the mirror 31, and the mirror 32, and a control unit 92 that controls the drive mechanism 91.

  The drive mechanism 91 has, for example, a drive source such as a motor, and a transmission member such as a gear that transmits the drive force from the drive source to the screen 11, the mirror 31, and the mirror 32.

  The controller 92 controls the drive mechanism 91 to control the operations and positions of the screen 11, the mirror 31, and the mirror 32. For example, the control unit 92 controls the positions of the screen 11, the mirror 31, and the mirror 32 such that the distance from the eyepoint 2 to the virtual image 21 increases as the vehicle speed increases, based on the detection result of the speed sensor and the like. To do. For example, the control unit 92 includes a processing unit 92a such as a central processing unit (CPU) and a storage unit 92b such as a semiconductor memory, and the function of the control unit 92 is that the processing unit 92a is stored in the storage unit 92b. It is realized by reading and executing the program. However, the function of the control unit 92 may be realized by a processing circuit which is a dedicated hardware circuit.

  The configuration of the drive unit 90 is not limited to the above. For example, the drive unit 90 includes an operation unit such as a lever that receives an operation force from a user such as a driver, and the operation force applied to the operation unit is displayed on the screen. It may be configured to communicate to 11, the mirror 31, and the mirror 32. In this case, the drive source of the drive mechanism 91 and the control unit 92 may be omitted.

  The drive unit 90 may be applied to the display device 1 according to the first embodiment and the display device 1a according to the modification.

  In each of the above-described embodiments, a term such as “parallel” or “vertical” indicating a positional relationship between components or a shape of a component may be used. These indicate that the range includes a manufacturing tolerance and a variation in assembly. For this reason, when the claims describe the positional relationship between parts or the shape of parts, it is meant to include a range in consideration of manufacturing tolerances, assembly variations, and the like.

  Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments.

<Appendix>
Hereinafter, modes based on the above description will be additionally described.
(Appendix 1)
An image forming unit that emits a first image light,
A first reflecting member that reflects the first image light to generate second image light;
A second reflecting member that reflects the second image light to generate third image light;
A screen for displaying an image based on the third image light;
A projection unit for projecting an image displayed on the screen,
The first reflecting member rotates about a first axis,
The first axis is located on the reflecting surface of the first reflecting member, is perpendicular to a surface including the central ray of the first image light and the central ray of the second image light, and Intersect with the center ray of the image light of 1,
The second reflecting member rotates about a second axis,
The second axis is located on the reflecting surface of the second reflecting member, is perpendicular to the surface, intersects the central ray of the second image light,
A display device for displaying a virtual image, characterized in that the screen is moved by rotating the first reflecting member and the second reflecting member while keeping the optical path length from the image forming unit to the screen constant.
(Appendix 2)
The screen moves in a first direction parallel to a central ray of the third image light,
The display device for displaying a virtual image according to appendix 1, wherein the second reflecting member moves in the same direction as the screen in the first direction.
(Appendix 3)
The center ray of the first image light and the center ray of the second image light are perpendicular to each other, and the center ray of the second image light and the center ray of the third image light are perpendicular to each other. 1 the reflection member, the second reflection member and the screen are set to the first state,
A state in which the screen is moved in the direction of the second reflecting member is referred to as a second state,
The moving distance of the second reflecting member is L _1, and
When the optical path length of the second image light in the first state is L ₂ ,
The moving distance L ₃ of the second reflecting member is represented by the following equation,
L ₃ =(L ₁ +2×L ₂ )×L ₁ /{2×(L ₁ +L ₂ )}
The rotation angle A ₁ of the first reflecting member is represented by the following equation,
A ₁ =(1/2)×tan ⁻¹ [(L ₁ +2×L ₂ )×L ₁ /{2×L ₂ ×(L ₁ +L ₂ )}]
The display device for displaying a virtual image according to appendix 2, wherein the rotation angle A ₂ of the _second reflection member is equal to the rotation angle A ₁ of the first reflection member.
(Appendix 4)
The screen includes a third axis at an end portion on the first reflecting member side,
The third axis is perpendicular to the plane,
The screen and the second reflecting member rotate about the third axis,
The display device for displaying a virtual image according to appendix 1, wherein the first reflecting member moves toward the image forming unit in a second direction parallel to a central ray of the first image light.
(Appendix 5)
The center ray of the first image light and the center ray of the second image light are perpendicular to each other, and the center ray of the second image light and the center ray of the third image light are perpendicular to each other. The state of the first reflection member, the second reflection member and the screen (11) is set to the first state,
A state in which the screen is rotated about the third axis is referred to as a third state,
The rotation angle of the screen is an angle A ₃ ,
The optical path length of the second image light in the first state is L ₂ ,
The optical path length of the third image light in the first state is L ₄ ,
When the distance from the intersection of the central ray of the third image light and the screen in the first state to the third axis is L ₅ ,
The rotation angle A ₄ before Symbol first axis about the first reflecting member is expressed by the following equation,
A ₄ =(1/2)×tan ⁻¹ [(L ₆ −L ₄ )/{(L ₄ ² +L ₅ ² ) ^0.5 ×sin(A ₆ −A ₃ )}]
The moving distance L7 of the first reflecting member is represented by the following equation,
_{L 7 = L 2 - {L} 2 -L 5 + (L 4 2 + L 5 2) 0.5 × sin (A 6 -A 3)} / cos (A 7)
The rotation angle A5 of about previous SL second axis of the second reflecting _{member, A 5 = (1/2) ×} tan -1 [(L 6 -L 4) represented by the following formula / _{{(L 4 ^{2 + L 5 2) 0.5 ×}} sin (A 6 -A 3)}] - (1/2) × A 3
^{_{A 6 = tan -1 (L 5}} / L 4)
^{_{L 6 = (L 4 2 +}} L 5 2) 0.5 × cos (A 6 -A 3)
A ₇ =tan ⁻¹ [(L ₆ −L ₄ )/{(L ₄ ² +L ₅ ² ) ^0.5 ×sin(A ₆ −A ₃ )}]
The display device for displaying the virtual image as described in appendix 4.

1, 1a, 1c display device, 11, 11a, 11b screen, 2 eyepoints, 21a, 21b virtual image, 25 eyebox, 3 windshield, 31, 32, 31a, 31b, 32a, 32b mirror, 4 projection unit, 6 Image forming section, 61 area, 71, 72, 73, 74a, 74b, 75a, 75b, 76a, 76b, 77 image light, 90 driving section, 91 driving mechanism, 92 control section, 92a processing section, 92b storage section, 101 , 101a, 101b, 102, 102a, 102b, 103, 104, 104a, 104b, 105, 105a, 105b rotation centers, A ₁ , A ₂ , A ₃ , A ₄ , A ₅ , A ₇ , A ₈ , A ₉ , A ₁₀ , A ₁₁ angle, L ₁ , L ₂ , L ₃ , L ₄ , L ₅ , L ₆ , L ₇ , L ₈ , L ₉ , L ₁₀ , L ₁₁ , L distance, R1, R2a, R2b, R3a, R3b incident point.

Claims (5)

An image forming unit that emits a first image light,
A first reflecting member that reflects the first image light and emits a second image light;
A second reflecting member that reflects the second image light and emits a third image light;
A screen for displaying an image based on the third image light;
A projection unit for projecting the image displayed on the screen as a virtual image,
A first incident point of the first reflecting member on which the central ray of the first image light is incident, a second incident point of the second reflecting member on which the central ray of the second image light is incident, And the third incident point of the screen on which the central ray of the third image light is incident is on the same plane,
The screen moves in a direction of approaching or separating from the projection unit,
When the screen moves in the direction, movement of at least one of the first reflecting member and the second reflecting member, centering on a first rotation axis perpendicular to the plane of the first reflecting member Due to the rotation and the rotation about the second rotation axis of the second reflection member which is perpendicular to the plane, the central ray of the third image light moves to the position of the third incident point with respect to the screen. While holding and moving in parallel, the sum of the optical path length of the central ray of the first image light, the optical path length of the central ray of the second image light, and the optical path length of the central ray of the third image light is , A display device for displaying a virtual image, which is characterized by being constant. An angle formed by the center ray of the third image light and the normal line of the screen is an angle θ,
As the screen moves in the direction, the third point of incidence is held in a fixed position on the screen, the second point of incidence passes through the third point of incidence, and the normal of the screen. The first incident point is located on the intersection of a straight line forming the angle θ with respect to a line and the reflecting surface of the second reflecting member, and the first incident point is on the central ray of the first image light. A distance from a part to the first incident point, a distance from the first incident point to the second incident point, and a distance from the second incident point to the third incident point are constant. Is located at a point on the reflecting surface of the first reflecting member,
The first reflecting member is arranged such that the central ray of the first image light is reflected at the first incident point and the central ray of the second image light is directed to the second incident point. ,
The second reflecting member is arranged such that the central ray of the second image light is reflected at the second incident point, and the central ray of the third image light is directed to the third incident point. The display device for displaying the virtual image according to claim 1. An angle formed by the center ray of the third image light and the normal line of the screen is an angle θ,
When the screen moves in the direction, the third incident point is held at a fixed position on the screen, and the first incident point is the center ray of the first image light and the first ray. The second incident point passes through the third incident point and forms an angle θ with respect to the normal line of the screen. A distance from a part to the first incident point, a distance from the first incident point to the second incident point, and a distance from the second incident point to the third incident point are constant. Is located at a point on the reflecting surface of the second reflecting member,
The first reflecting member is arranged such that the central ray of the first image light is reflected at the first incident point and the central ray of the second image light is directed to the second incident point. ,
The second reflecting member is arranged such that the central ray of the second image light is reflected at the second incident point, and the central ray of the third image light is directed to the third incident point. The display device for displaying the virtual image according to claim 1.   The display device for displaying a virtual image according to claim 1, wherein the first rotation axis includes the first incident point and is fixed. The plane is represented by the yz plane,
The z axis of the yz plane is parallel to the central ray of the third image light,
The coordinates of the first incident point on the plane are (0, 0), the coordinates of the third incident point before the screen is moved are (m1, n1), and the coordinates after the screen is moved. The coordinates of the third incident point are (m2, n2), the coordinates of the second incident point after the screen is moved are (z2, y2), and the optical path of the central ray of the second image light is set. If the sum of the length and the optical path length of the central ray of the third image light is L,
The value z2 of the z coordinate of the second incident point satisfies the following equation,
z2={(L+m2) ² −n2 ² }/{2×(L+m2)}
The display device for displaying a virtual image according to claim 4, wherein the y-coordinate value y2 is equal to the y-coordinate value n2.

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