JP2018146900A - Image display apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display apparatus which scans a screen using a laser beam to generate a display image and is capable of easily and smoothly suppressing degradation of visibility of the display image due to an interference pattern.SOLUTION: An image display apparatus 20 includes: a light source 101; a screen 108 on which an image is drawn by two-dimensional scanning using a laser beam; a scan part 106 that scans the laser beam on the screen; a mirror drive circuit 203 that drives the scan part 106; and an optical system that generates a virtual image of the image drawn on the screen 108. For the screen 108, a plurality of lens areas is disposed so as to be arranged in a first direction and a second direction perpendicular to the first direction. The mirror drive circuit 203 is configured to set plural scan lines so that a pitch of the scan lines is smaller than a pitch in the lens area in the second direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image display device that displays an image, and is suitably mounted on a moving body such as a passenger car, for example.

  In recent years, an image display device called a head-up display has been developed, and is mounted on a moving body such as a passenger car. For example, in a head-up display mounted on a passenger car, light modulated by a video signal is projected onto a windshield (windshield), and the reflected light enters the driver's eyes. As a result, the driver can see a virtual image of the image in front of the windshield. For example, the vehicle speed, the outside temperature, etc. are displayed as a virtual image.

  In the head-up display, a laser light source can be used as a light source. In this case, the laser beam scans the screen while being modulated according to the video signal. Thereafter, the laser light is diffused by the screen and guided to an eye box near the driver's eyes. As a result, the driver can see the image (virtual image) satisfactorily and stably even if the driver moves his head slightly. The eye box has, for example, a horizontally long rectangular shape.

  Patent Document 1 below describes an image display device in which a screen is configured by a microlens array in which a plurality of microlenses are arranged. Here, the screen is scanned two-dimensionally with the laser beam by causing the laser beam to scan at high speed in the main scanning direction and scanning the laser beam in the sub-scanning direction orthogonal to the main scanning direction.

JP 2006-90769 A

  When the screen is constituted by the microlens array as described above, the spot diameter of the laser beam on the screen is usually adjusted to be equal to or smaller than the width of each lens. The laser beam is scanned so that the beam spot passes through the center of the lens groups arranged in a line in the scanning direction. When the scanning of one lens group is completed, the same scanning is performed on the next row adjacent to this row. In this way, the lens groups of all the rows on the screen are scanned in order, and one image is generated on the screen.

  In such a scanning method, when the beam spot is shifted from the center of the lens group in each row in the direction perpendicular to the scanning direction, interference fringes are generated in the display image, and the visibility of the display image is lowered. Confirmed by the inventors. For this reason, in this scanning method, the positions of the optical system, the screen, and the like have to be strictly adjusted so that the beam spot passes through the center of each lens group, which requires complicated work. Even if the positions of the optical system, the screen, and the like are properly adjusted, if the screen is deformed due to a subsequent temperature change or the like, a positional deviation occurs between the scanning position of the beam spot and the lens group. For this reason, when the scanning method is used, it is extremely difficult to suppress the interference fringes and maintain the visibility of the display image.

  In view of such problems, the present invention provides an image display that can easily and smoothly suppress a reduction in the visibility of a display image due to interference fringes in an image display device that generates a display image by scanning a screen with laser light. An object is to provide an apparatus.

  A first aspect of the present invention relates to an image display device. An image display device according to this aspect includes a light source that emits laser light, a screen on which an image is drawn by being scanned two-dimensionally with the laser light, and a scanning unit that scans the screen with the laser light. A driving unit that drives the scanning unit so that the laser light moves on the screen along a plurality of scanning lines parallel to the first direction, and an optical system that generates a virtual image of an image drawn on the screen And comprising. A plurality of lens regions are arranged on the screen so as to be aligned in the first direction and a second direction perpendicular to the first direction. The drive unit sets the plurality of scan lines so that a pitch of the scan lines is smaller than a pitch of the lens regions in the second direction.

  According to the image display apparatus according to this aspect, interference fringes generated in the display image when each scanning line is scanned are averaged with each other when recognized by the human eye, and the interference fringes become inconspicuous. Thereby, the fall of the visibility of the display image by an interference fringe can be suppressed. In addition, since the interference fringes based on each scanning line are averaged with each other, even if the screen is deformed due to a temperature change or the like, and the way the interference fringes are generated based on each scanning line is changed, The interference fringes are averaged at any time and become inconspicuous on the display image. Therefore, even if the screen is deformed due to a temperature change or the like, the visibility of the display image is maintained well.

  As described above, according to the present invention, it is possible to smoothly suppress a reduction in the visibility of a display image due to interference fringes with an extremely simple configuration in which the relationship between the pitch of scanning lines and the pitch of lens areas is adjusted. .

  The effects and significance of the present invention will become more apparent from the following description of embodiments. However, the embodiment described below is merely an example when the present invention is implemented, and the present invention is not limited to what is described in the following embodiment.

FIGS. 1A and 1B are diagrams schematically illustrating a usage pattern of the image display device according to the embodiment, and FIG. 1C is a schematic diagram of the configuration of the image display device according to the embodiment. FIG. FIG. 2 is a diagram illustrating a configuration of an irradiation light generation unit and a circuit used for the irradiation light generation unit of the image display device according to the embodiment. FIGS. 3A and 3B are diagrams schematically showing a state in which the screen according to the embodiment is viewed from the incident side and the emitting side of the laser beam. FIG. 4 is an enlarged view of a part of the screen according to the embodiment. FIG. 5A to FIG. 5C are diagrams each illustrating a configuration example of the non-lens region according to the embodiment. FIG. 6A is a perspective view schematically illustrating the configuration of the screen according to the embodiment, and FIG. 6B is a diagram schematically illustrating a scanning method of laser light on the screen. FIG. 7A is a diagram illustrating a screen region setting method according to the embodiment, and FIG. 7B is a diagram illustrating a screen divergence angle setting method according to the embodiment. FIG. 8A is a graph showing the light quantity distribution in the eye box according to Comparative Example 1, and FIG. 8B is a graph showing the light quantity distribution in the eye box according to the embodiment. FIGS. 9A to 9C are diagrams showing a screen position adjusting method according to the embodiment. FIG. 10A is a diagram schematically illustrating a laser beam scanning method according to Comparative Example 2. FIGS. 10B to 10E schematically show interference fringes generated in the display image when the scanning position of the laser light is displaced in the arrangement direction of the second lens portions in the scanning method according to Comparative Example 2, respectively. FIG. FIG. 11A is a diagram schematically illustrating a laser beam scanning method according to the embodiment. 11B to 11E schematically illustrate interference fringes visually recognized in the display image when the scanning position of the laser light is displaced in the arrangement direction of the second lens portions in the scanning method according to the embodiment. FIG. 12A and 12B show captured images obtained by capturing interference fringes generated in a display image when the ratio of the scanning line pitch to the second lens unit pitch is changed in the experiment according to the embodiment. FIG. 13A and 13B show captured images obtained by capturing interference fringes generated in a display image when the ratio of the scanning line pitch to the second lens unit pitch is changed in the experiment according to the embodiment. FIG. 14A and 14B show captured images obtained by capturing interference fringes generated in a display image when the ratio of the scanning line pitch to the pitch of the second lens unit is changed in the experiment according to the embodiment. FIG. FIG. 15A is a diagram illustrating a relationship between the second lens unit and the intensity distribution of the laser beam in the scanning method of the embodiment. FIG. 15B is a diagram showing the relationship between the second lens unit and the intensity distribution of the laser beam in the scanning method of Comparative Example 2. FIG. 16A is a diagram schematically illustrating a state in which the screen according to the modification example 1 is viewed from the laser light incident side, and FIG. 16B is a partially enlarged view of the screen according to the modification example. FIG. 17 is a diagram illustrating a configuration of an irradiation light generation unit and a circuit used for the irradiation light generation unit of the image display device according to the second modification. 18A is a diagram illustrating an example of a screen moving process according to the second modification, and FIG. 18B is an example of an image displayed by moving the screen in the image display device according to the second modification. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, X, Y, and Z axes that are orthogonal to each other are appended to each drawing as appropriate.

  FIGS. 1A and 1B are diagrams schematically illustrating how the image display device 20 is used. FIG. 1A is a schematic view of the inside of the passenger car 1 seen through from the side of the passenger car 1, and FIG. 1B is a view of the passenger car 1 as viewed from the front in the running direction.

  In the present embodiment, the present invention is applied to an in-vehicle head-up display. As shown in FIG. 1A, the image display device 20 is installed inside the dashboard 11 of the passenger car 1.

  As shown in FIGS. 1A and 1B, the image display device 20 projects the laser light modulated by the video signal onto the projection area 13 near the driver seat below the windshield 12. The laser light is reflected by the projection region 13 and is irradiated to a horizontally long region (eye box region) around the eye position of the driver 2. Thus, the predetermined image 30 is displayed as a virtual image in the field of view ahead of the driver 2. The driver 2 can superimpose an image 30 that is a virtual image on the scenery in front of the windshield 12. That is, the image display device 20 forms an image 30 that is a virtual image in a space in front of the projection region 13 of the windshield 12.

  FIG. 1C is a diagram schematically illustrating the configuration of the image display device 20.

  The image display device 20 includes an irradiation light generation unit 21 and a mirror 22. The irradiation light generation unit 21 emits laser light modulated by the video signal. The mirror 22 has a curved reflecting surface, and reflects the laser light emitted from the irradiation light generation unit 21 toward the windshield 12. The laser beam reflected by the windshield 12 is applied to the eyes 2a of the driver 2. The optical system and the mirror 22 of the irradiation light generation unit 21 are designed so that a virtual image 30 is displayed in a predetermined size in front of the windshield 12.

  FIG. 2 is a diagram illustrating a configuration of the irradiation light generation unit 21 of the image display device 20 and a configuration of a circuit used for the irradiation light generation unit 21.

  The irradiation light generation unit 21 includes a light source 101, collimator lenses 102a to 102c, apertures 103a to 103c, a mirror 104, dichroic mirrors 105a and 105b, a scanning unit 106, a correction lens 107, and a screen 108. .

  The light source 101 includes three laser light sources 101a to 101c.

  The laser light source 101a emits laser light having a red wavelength included in the range of 600 to 700 nm, the laser light source 101b emits laser light having a green wavelength included in the range of 600 to 600 nm, and the laser light source 101c is 400 A laser beam having a blue wavelength included in a range of ˜500 nm is emitted. In the present embodiment, in order to display a color image as the image 30, the light source 101 includes these three laser light sources 101a to 101c. When displaying a monochromatic image as the image 30, the light source 101 may include only one laser light source corresponding to the color of the image. The laser light sources 101a to 101c are made of semiconductor lasers, for example.

  Laser light emitted from the laser light sources 101a to 101c is converted into parallel light by the collimator lenses 102a to 102c, respectively. The laser beams transmitted through the collimator lenses 102a to 102c are shaped into circular beams having substantially the same size by the apertures 103a to 103c, respectively. That is, the apertures 103a to 103c constitute a beam shaping unit for aligning the beam size and beam shape of the laser beams emitted from the laser light sources 101a to 101c, respectively.

  Instead of the collimator lenses 102a to 102c, a shaping lens that shapes the laser beam into a circular beam shape and converts it into parallel light may be used. In this case, the aperture can be omitted.

  Thereafter, the optical axes of the laser beams of the respective colors emitted from the laser light sources 101a to 101c are aligned by the mirror 104 and the two dichroic mirrors 105a and 105b. The mirror 104 substantially totally reflects the red laser light transmitted through the collimator lens 102a. The dichroic mirror 105a reflects the green laser light transmitted through the collimator lens 102b and transmits the red laser light reflected by the mirror 104. The dichroic mirror 105b reflects the blue laser light that has passed through the collimator lens 102c, and transmits the red laser light and the green laser light that have passed through the dichroic mirror 105a. The mirror 104 and the two dichroic mirrors 105a and 105b are arranged so that the optical axes of the laser beams of the respective colors emitted from the laser light sources 101a to 101c are aligned. The mirror 104 and the two dichroic mirrors 105a and 105b constitute an optical axis alignment unit that aligns the optical axes of the laser beams emitted from the laser light sources 101a to 101c, respectively.

  The scanning unit 106 reflects the laser light of each color that passes through the dichroic mirror 105b. The scanning unit 106 includes, for example, a micro electro mechanical system (MEMS) mirror, and a mirror 106a on which laser beams of various colors are incident via a dichroic mirror 105b is arranged in an axis parallel to the Y axis according to a drive signal. And a configuration for rotating around an axis parallel to the X axis. By rotating the mirror 106a in this way, the reflection direction of the laser light changes in the in-plane direction of the XZ plane and the in-plane direction of the YZ plane. Thereby, as will be described later, the screen 108 is two-dimensionally scanned by the laser light of each color.

  Here, the scanning unit 106 is configured by a biaxially driven MEMS mirror, but the scanning unit 106 may have other configurations. For example, the scanning unit 106 may be configured by combining a mirror that is rotationally driven around an axis parallel to the Y axis and a mirror that is rotationally driven around an axis parallel to the X axis.

  The correction lens 107 is designed to direct the laser light of each color in the positive direction of the Z axis regardless of the swing angle of the laser light by the scanning unit 106.

  The screen 108 scans the laser beam to form an image, and has an action of diffusing the incident laser beam to a region around the position of the eyes 2a of the driver 2 (eye box region). The screen 108 is made of a transparent resin such as PET (polyethylene terephthalate). The configuration of the screen 108 will be described later with reference to FIGS. 3 (a) to 7 (b).

  The image processing circuit 201 includes an arithmetic processing unit such as a CPU (Central Processing Unit) and a memory, and processes the input video signal to control the laser driving circuit 202 and the mirror driving circuit 203. The laser drive circuit 202 changes the emission intensity of the laser light sources 101a to 101c in accordance with a control signal from the image processing circuit 201. The mirror driving circuit 203 drives the mirror 106 a of the scanning unit 106 in accordance with a control signal from the image processing circuit 201. Control in the image processing circuit 201 during the image display operation will be described later with reference to FIGS. 6B and 11A.

  FIGS. 3A and 3B are diagrams schematically showing a state in which the screen 108 is viewed from the laser light incident side and the light emitting side, respectively. On the upper side of FIG. 3A, an enlarged view of the vicinity of the corners of the screen 108 on the X-axis positive side and the Y-axis positive side from the Y-axis positive side is schematically shown. Further, on the right side of FIG. 3 (b), an enlarged view of the vicinity of the corner on the X-axis negative side and the Y-axis positive side of the screen 108 from the X-axis negative side is schematically shown.

  As shown in FIG. 3 (a), a plurality of first lens portions 108a for diverging laser light in the X-axis direction are provided on the laser light incident side surface (Z-axis negative side surface) of the screen 108. , So as to be aligned in the X-axis direction. The shape of the first lens portion 108a when viewed in the Y-axis direction is a substantially arc shape. The width in the X-axis direction of the first lens unit 108a is, for example, 50 μm.

  As shown in FIG. 3B, a plurality of second lens portions 108b for diverging the laser light in the Y-axis direction are provided on the laser light emission side surface (the Z-axis positive side surface) of the screen 108. And are arranged in the Y-axis direction. The shape of the second lens portion 108b when viewed in the X-axis direction is a substantially arc shape. The width in the Y-axis direction of the second lens unit 108b is, for example, 70 μm. The width of the second lens portion 108b in the Y-axis direction may be the same as the width of the first lens portion 108a in the X-axis direction.

  FIG. 4 is an enlarged view showing a part of the screen 108. FIG. 4 shows an enlarged part of the screen 108 when the screen 108 is viewed in the laser beam incident direction (Z-axis positive direction). In FIG. 4, the solid line indicates the boundary of the first lens unit 108a, and the broken line indicates the boundary of the second lens unit 108b.

  As shown in FIG. 4, when viewed in the laser beam incident direction (Z-axis positive direction), the region where the first lens unit 108 a and the second lens unit 108 b overlap (the hatched region) One lens region La1 is configured. The lens regions La1 are arranged in a line in the X-axis direction and the Y-axis direction. The laser light incident on each lens region La1 is diffused after being converged in the X-axis direction by the first lens unit 108a, and is diffused after being converged in the Y-axis direction by the second lens unit 108b. In this way, the laser light incident on each lens region La1 is guided to a horizontally long region (eye box region) around the position of the eye 2a of the driver 2.

  Here, the curvature radius Rx of the first lens portion 108a and the curvature radius Ry of the second lens portion 108b are different from each other. The curvature radius Rx is set smaller than the curvature radius Ry. Therefore, the divergence angle that diverges after the laser beam is converged by the first lens unit 108a is larger than the divergence angle that diverges after the laser beam is converged by the second lens unit 108b. By setting the curvatures of the first lens portion 108a and the second lens portion 108b in this manner, the laser light that passes through the screen 108 is transmitted to a horizontally long region (eye box region) around the position of the eye 2a of the driver 2. ). The curvature radii of the first lens unit 108a and the second lens unit 108b are determined according to the shape of the eye box region.

  Returning to FIG. 3A, D <b> 10 is a drawing area of the screen 108. That is, the screen 108 is scanned with the laser beam in the drawing area D10 to form an image. Non-lens regions 108c and 108d of a predetermined size that allow incident light to pass through without divergence are formed at positions above and below the drawing region D10, respectively. The sizes of the non-lens regions 108c and 108d are set to be equal to each other. The width in the X-axis direction of the non-lens regions 108c and 108d is, for example, 50 to 100 μm, and the width in the Y-axis direction is, for example, 100 to 200 μm.

  The non-lens regions 108c and 108d are respectively arranged at intermediate positions of the width of the screen 108 in the X-axis direction. The arrangement positions of the non-lens regions 108c and 108d are not limited to the intermediate position of the width of the screen 108 in the X-axis direction, and may be other positions. Further, the number of the non-lens regions 108c and 108d may not be one each. For example, two or more sets of the non-lens regions 108c and 108d may be arranged with the drawing region D10 interposed therebetween.

  5A to 5C are diagrams illustrating a configuration example of the non-lens region 108c.

  In the configuration example of FIG. 5A, the non-lens region 108c is configured by omitting the first lens portion 108a and the second lens portion 108b. That is, the laser beam incident side (Z-axis negative side) surface and the laser beam emission side (Z-axis positive side) surface of the screen 108 are planes parallel to the XY plane in the non-lens region 108c. .

  In the configuration example of FIG. 5B, by forming a hole penetrating from the laser light incident side (Z-axis negative side) surface of the screen 108 to the laser light emission side (Z-axis positive side) surface, A lens region 108c is configured. In the configuration example of FIG. 5C, the non-lens region 108c is configured by forming a rectangular recess recessed in the Y-axis negative direction from the edge on the Y-axis positive side of the screen 108.

  The configuration of the non-lens region 108c is not limited to the configuration shown in FIGS. 5A to 5C, and may be other configurations as long as the incident light is allowed to pass through without diverging. For example, the shape of the non-lens region 108c when viewed in the Z-axis direction is not limited to a square, and may be another shape such as a circle.

  5A to 5C show a configuration example of the non-lens region 108c arranged on the Y axis positive side, the non-lens region 108d arranged on the Y axis negative side is also shown in FIG. It can be formed in the same manner as (a) to (c).

  FIG. 6A is a perspective view schematically showing the configuration of the screen 108. FIG. 6B is a diagram schematically illustrating a scanning method of the laser beam with respect to the screen 108.

  The incident surface (surface on the negative side of the Z axis) of the screen 108 having the above configuration is scanned in the positive direction of the X axis by the beam B1 on which the laser beams of the respective colors are superimposed. Scan lines L1 to Ln through which the beam B1 passes are set in advance in the Y-axis direction at regular intervals with respect to the incident surface of the screen 108. The start position and the end position of the scanning lines L1 to Ln coincide with each other in the X-axis direction. Therefore, the area surrounding the scanning lines L1 to Ln is a rectangle. The diameter of the beam B1 is set smaller than the width of the second lens unit 108b. For example, the diameter of the beam B1 is set to about 35 to 65 μm.

  The scanning lines L1 to Ln are scanned at a high frequency by the beam B1 in which the laser light of each color is modulated by the video signal, thereby forming an image. The image thus configured is projected onto an area (eye box) around the position of the eye 2a of the driver 2 via the screen 108, the mirror 22 and the windshield 12 (see FIG. 1C). As a result, the driver 2 visually recognizes the image 30 as a virtual image in the space in front of the windshield 12.

  Incidentally, as described above, in the configuration in which the laser beam scans the screen 108 by the scanning unit 106 using MEMS, the scanning speed of the laser beam decreases from the center of the screen 108 toward both ends in the X-axis direction. For this reason, the image on the screen 108 is brighter at both ends in the scanning direction than at the center. If the brightness of the image is non-uniform in this way, it may give a strange feeling to the viewer who has seen the image. The image visually recognized by the observer is preferably as uniform as possible in overall brightness.

  Therefore, in the present embodiment, the divergence angle in the X-axis direction is constant in the predetermined range in the center of the scanning direction (X-axis direction) in the drawing region D10 where the image is drawn, and the predetermined range is excluded. The screen 108 is configured so that the divergence angle in the X-axis direction gradually increases toward the end in the X-axis direction in the range on both sides.

  FIG. 7A is a diagram showing a method for setting the area of the screen 108, and FIG. 7B is a diagram showing a method for setting the divergence angle of the screen 108. In the graph of FIG. 7B, the horizontal axis represents the position of the screen 108 in the X-axis direction, and the vertical axis represents the divergence angle (degree) in the X-axis direction. On the horizontal axis, the intermediate position of the width of the screen 108 (drawing area D10) in the X-axis direction is set to zero.

  As shown in FIG. 7B, in the screen 108, the divergence angle in the X-axis direction is set constant in a predetermined range W0 in the center of the scanning direction (X-axis direction) in the drawing area D10. The predetermined range W0 is a range having a width Δw in the X-axis positive and negative directions from the intermediate position in the X-axis direction of the drawing region D10. The predetermined range W0 is set to a range of 40% to 50% of the entire range of the drawing region D10 in the scanning direction (X-axis direction).

  The screen 108 is set so that the divergence angle in the X-axis direction gradually increases toward the positive and negative ends of the X-axis in the range W1 on both sides excluding the predetermined range W0. More specifically, the divergence angle in the X-axis direction is gradually increased toward the ends of the range W1 on both sides by changing the curvature of the first lens portion 108a included in the range W1 on both sides. ing.

  In order to obtain the divergence angle distribution shown in FIG. 7B, the curvature of the first lens portion 108a gradually changes toward the end in the range W1 on both sides. Specifically, in the range W1 on both sides, the radius of curvature Rx of the first lens portion 108a is gradually reduced toward the end. Thereby, in the range W1 on both sides, the divergence angle in the X-axis direction changes stepwise from about 20 degrees to about 50 degrees.

  In the range W1 on both sides, the curvature of the first lens portion 108a is the same in the group when the plurality of first lens portions 108a adjacent in the X-axis direction are made into one group. It is set to change step by step. In addition, the curvature may be different between the adjacent first lens portions 108a.

  The curvature radius Rx of the first lens portion 108a in the predetermined range W0 is set so that the divergence angle in the X-axis direction is about 20 degrees. The curvature radius Rx of the first lens unit 108a in the predetermined range W0 is, for example, 50 μm. The curvature radius Rx of the first lens unit 108a and the curvature radius Ry of the second lens unit 108b in the predetermined range W0 are set to, for example, Rx: Ry = 1: 2.

  FIG. 8A is a graph showing the light quantity distribution in the eye box according to Comparative Example 1, and FIG. 8B is a graph showing the light quantity distribution in the eye box according to the embodiment.

  In Comparative Example 1, the divergence angle of the first lens unit 108a is set to be constant in the entire range of the drawing region D10. In Comparative Example 1, the divergence angles of all the first lens portions 108a are set to about 20 degrees as in the predetermined range W0 in FIG. 7B. In Comparative Example 1, the radius of curvature Rx of the first lens unit 108a is constant in the entire range of the drawing region D10.

  FIGS. 8A and 8B show the light amount distribution (simulation result) in the eye box when the screen 108 according to the comparative example 1 and the screen 108 according to the embodiment are used, respectively. Yes. The screen 108 according to the embodiment has a divergence angle adjusted as shown in FIG.

  In the graphs of FIGS. 8A and 8B, the horizontal axis represents the position of the eye box in the horizontal direction, and the vertical axis represents the light amount per unit time. On the horizontal axis, the intermediate position of the eyebox in the horizontal direction is set to zero. Note that the horizontal direction of the eye box corresponds to the X-axis direction of the screen 108. The vertical axis is normalized with the light quantity at the intermediate position in the horizontal direction of the eye box in the X-axis direction as 1. In FIG. 8B, for convenience, the ranges corresponding to the predetermined range W0 and the ranges W1 on both sides shown in FIG. 7B are shown as W0 and W1, respectively.

  As shown in FIG. 8A, in Comparative Example 1, the amount of light in the eye box increases as it goes toward both ends of the eye box. This is because the scanning speed of the laser beam by the scanning unit 106 becomes slower as it goes to both ends of the drawing region D10 in the X-axis direction. In Comparative Example 1, as described above, the amount of light in the eye box increases as it goes toward both ends of the eye box, so that the brightness of the image 30 visually recognized by the observer becomes non-uniform.

  As shown in FIG. 8B, in the embodiment, as described above, in the range W1 on both sides excluding the predetermined range W0 in the center in the scanning direction (X-axis direction), the divergence angle in the X-axis direction is the end. The screen 108 is configured to gradually increase toward the screen. For this reason, the light quantity of the light in both side portions in the eye box is weakened as compared to the center portion as it goes toward the end. As a result, the brightness of the entire image in the eye box is made closer to uniform. As a result, in the embodiment, the brightness of the image visually recognized by the observer is substantially uniform over the entire area in the eye box.

  8A and 8B, the broken line indicates a level at which the light quantity is 1.2 times the light quantity at the intermediate position in the horizontal direction of the eyebox. In a range where the amount of light is about 1.2 times, the brightness unevenness of the image is small, and thus the change in brightness is hardly visually recognized by human eyes. Therefore, in this range, an image can be displayed without giving an uncomfortable feeling to the observer without adjusting the light quantity in the eye box.

  The predetermined range W0 corresponds to a range in which the light amount is 1.2 times or less of the light amount at the intermediate position in the horizontal direction of the eye box in the eye box. Specifically, in the predetermined range W0, when the intensity of laser light that scans the screen 108 is constant, the amount of laser light that passes through the screen 108 per unit time is drawn in the scanning direction (X-axis direction). The range is set to be 1.2 times or less of the intermediate position of the region D10. The predetermined range W0 is preferably set so as to satisfy this condition.

  When the predetermined range W0 is set to a range of 40% to 50% of the entire drawing area D10 in the scanning direction (X-axis direction), the predetermined range W0 can substantially satisfy the above-described conditions. Therefore, by setting the predetermined range W0 to a range of 40% or more and 50% or less of the entire range of the drawing region D10 in the scanning direction (X-axis direction), the observer can select an image formed in the predetermined range W0. Visible without any discomfort due to uneven brightness.

  FIGS. 9A to 9C are diagrams showing a method for adjusting the position of the screen 108. This position adjustment is performed using a predetermined position adjusting device in the manufacturing process of the image display device 20.

  9A to 9C, the state of the screen 108 is shown on the left side, and the state of the image sensor 301 in the position adjusting device is shown on the right side. The position adjustment device includes a mechanism unit for adjusting the position of the screen 108 in a direction parallel to the XY plane, and an image sensor 301 for receiving light emitted from the screen 108.

  In the position adjustment step, the image processing circuit 201 shown in FIG. 2 controls the laser driving circuit 202 and the mirror driving circuit 203 so that the straight line image R10 extending in the Y-axis direction is drawn on the screen 108. The length of the straight line image R10 in the Y-axis direction is set to be longer than the length of the drawing area D10 in the Y-axis direction, and is set to be substantially the same as the length of the screen 108 in the Y-axis direction, for example. The width of the straight line image R10 in the X-axis direction is set to be substantially the same as the width of the non-lens regions 108c and 108d in the X-axis direction.

  FIG. 9A shows a state in which the screen 108 is positioned at a normal position on a plane parallel to the XY plane. In this case, the upper end portion and the lower end portion of the linear image R10 are positioned in the non-lens regions 108c and 108d, respectively, and pass through the non-lens regions 108c and 108d without being diverged. Thereby, the light ray portions R21 and R22 based on the upper end portion and the lower end portion of the linear image R10 are projected onto the image sensor 301. A central portion other than the upper end portion and the lower end portion of the linear image R10 is diffused in the X-axis direction by the first lens portion 108a (see FIG. 3A) arranged in the drawing region D10. Thereby, the diffused light R23 based on the central portion of the linear image R10 is projected onto the image sensor 301.

  In this case, the position adjustment device detects that the light ray portions R21 and R22 are projected by the same amount on the image pickup element 301, so that the screen 108 is a regular one on a plane parallel to the XY plane. It is determined that it is positioned at a position.

  FIG. 9B shows a state in which the screen 108 is in a position rotated counterclockwise from the normal position on a plane parallel to the XY plane. In this case, only the upper end of the straight line image R10 is positioned in the non-lens region 108c. For this reason, the light ray portion R21 based on the upper end portion of the linear image R10 is projected on the image sensor 301, but the light ray portion R22 based on the lower end portion of the linear image R10 is not projected. The position adjusting device is shown in FIG. 8B with the screen 108 centered on the upper non-lens region 108c based on the fact that only the light ray portion R21 is projected on the image sensor 301 among the light ray portions R21 and R22. Rotate clockwise as indicated by the arrow. As a result, as shown in FIG. 9C, the lower end portion of the linear image R10 is positioned in the non-lens region 108d, and the light ray portion R22 based on the lower end portion is projected onto the image sensor 301.

  In this case, since the light beam portion R21 is projected more on the image sensor 301 than the light beam portion R22, the position adjustment device is configured so that the light beam portions R21 and R22 are projected by the same amount. 108 is moved in the positive direction of the Y-axis as indicated by an arrow in FIG. As a result, the straight line image R10 is positioned with respect to the screen 108 as shown in FIG. The position adjustment device determines that the light ray portions R21 and R22 have the same projection amount on the image sensor 301 and are thus positioned at regular positions on a plane parallel to the XY plane. In this way, after the position adjustment is performed, the screen 108 is fixed in the image display device 20 by fixing means such as an adhesive.

  In the example of FIG. 9B, the upper end portion of the linear image R10 is positioned in the non-lens region 108c. However, both the upper end portion and the lower end portion of the linear image R10 are in the non-lens regions 108c and 108d, respectively. It may happen that it cannot be positioned. In this case, the position adjustment device rotates and moves the screen 108 in a direction parallel to the XY plane by a predetermined adjustment step while referring to the image captured by the image sensor 301, as shown in FIG. 9A. In addition, the position adjustment with respect to the screen 108 is performed so that the upper end portion and the lower end portion of the straight line image R10 are positioned equally to the non-lens regions 108c and 108d, respectively.

  By the way, as described above, when the spot diameter of the laser beam on the screen 108 is set to be equal to or smaller than the width of each lens, as a laser beam scanning method for the screen 108, for example, the laser beam scanning direction (X-axis direction) A method in which the laser beam is scanned so that the beam B1 passes through the center of the lens regions La1 (see FIG. 4) arranged in a row in a row can be used.

  FIG. 10A shows a scanning method (Comparative Example 2) in this case. For convenience, in FIG. 10A, illustration of the first lens portion 108a formed on the incident surface side of the screen 108 is omitted. The broken line in FIG. 10A indicates the boundary of the second lens portion 108b formed on the exit surface side of the screen 108.

  In the scanning method of Comparative Example 2, the scanning lines L1 to Ln are set at the center position in the width direction (Y-axis direction) of the second lens unit 108b. Therefore, the pitch P1 of the second lens portion 108b and the pitch P2 of the scanning lines L1 to Ln are the same. The pitch P1 corresponds to the pitch in the Y-axis direction of the lens region La1 shown in FIG.

  However, in this scanning method, when the positional relationship between the scanning position of the laser beam and the screen 108 is deviated in a direction perpendicular to the scanning direction (Y-axis direction), the inventors have found that interference fringes are generated in the display image. Confirmed by.

  10B to 10E show the positional relationship between the scanning position of the laser beam and the second lens unit 108b in the scanning method according to Comparative Example 2, respectively, in the direction perpendicular to the scanning direction (Y-axis direction). It is a figure which shows typically the interference fringe which arises in the image 30 when it changes to.

  FIG. 10B shows a state where the scanning position of the laser light is positioned at the center position of the second lens portion 108b, that is, the positional relationship between the scanning position of the laser light and the screen 108 is appropriate. Is shown. In this case, no interference fringes are generated in the image 30 as shown in FIG.

  FIGS. 10C to 10E show states of interference fringes when the scanning position of the laser beam is shifted in the Y-axis direction from the center position of the second lens unit 108b. In FIG. 10D, the amount of deviation of the scanning position is larger than in the case of FIG. 10C, and in FIG. 10E, the amount of deviation of the scanning position is larger than in the case of FIG.

  As shown in FIGS. 10C to 10E, in the scanning method of the comparative example 2, the image 30 is displayed when the scanning position of the laser beam is deviated from the center position of the second lens portion 108b in the Y-axis direction. Interference fringes are generated, and the number of interference fringes increases as the amount of deviation increases. Thus, in the scanning method of Comparative Example 2, the visibility of the image 30 is reduced due to the interference fringes generated in the image 30.

  In order to avoid such a problem, in the scanning method of the comparative example 2, when the screen 108 is installed, an operation for strictly adjusting the installation position of the screen 108 so that the laser beam passes through the center of the second lens unit 108b. Is required. However, even when the position of the screen 108 is appropriately adjusted at the time of installation in this way, if the screen 108 is deformed due to a subsequent temperature change or the like, the positional relationship between the scanning position of the laser beam and the second lens unit 108b is lost. Thus, interference fringes are generated in the image 30. For this reason, in the scanning method of Comparative Example 2, it is extremely difficult to suppress the interference fringes and maintain the visibility of the image 30 in a good manner.

  In order to eliminate such inconvenience, in this embodiment, in order to make the interference fringes generated in the image 30 inconspicuous, the scanning method of the laser beam with respect to the screen 108 is adjusted as follows.

  FIG. 11A is a diagram schematically illustrating a laser beam scanning method according to the embodiment. Also in FIG. 11A, for the sake of convenience, the illustration of the first lens portion 108a formed on the incident surface side of the screen 108 is omitted. A broken line in FIG. 11A indicates a boundary of the second lens portion 108b formed on the emission surface side of the screen 108.

  As shown in FIG. 11A, in the scanning method of the embodiment, the pitch P2 of the scanning lines L1 to Ln is set smaller than the pitch P1 of the second lens portion 108b. Therefore, in the predetermined scanning line, the scanning position of the laser beam is shifted in the Y-axis direction with respect to the center position of the second lens portion 108b. In these scanning lines, the amount of deviation of the scanning position of the laser beam (beam B1) with respect to the central position of the second lens unit 108b differs for each scanning line. Furthermore, in a predetermined scanning line, the laser beam (beam B1) may straddle two adjacent second lens portions 108b.

  According to the scanning method of the embodiment, by adjusting the pitch P2 of the scanning lines L1 to Ln as described above, the interference fringes generated in the image 30 can be made inconspicuous as shown in the experimental results later.

  FIGS. 11B to 11E show the positional relationship between the scanning position of the laser beam and the second lens unit 108b in the scanning method according to the embodiment in the direction perpendicular to the scanning direction (Y-axis direction). It is a figure which shows typically the interference fringe which arises in the image 30 when it changes to.

  FIG. 11B shows the state of interference fringes when the positional relationship between the scanning position of the laser beam and the screen 108 is appropriate. 11C to 11E show the state of interference fringes when the scanning position of the laser beam is shifted relative to the screen 108 in the Y-axis direction. In FIG. 11D, the amount of deviation of the scanning position is larger than in the case of FIG. 11C, and in FIG. 11E, the amount of deviation of the scanning position is larger than in the case of FIG.

  As shown in FIG. 11B, in the scanning method of the embodiment, even when the positional relationship between the scanning position of the laser beam and the screen 108 is appropriate, interference fringes can occur in the image 30. However, the interference fringes generated here are very inconspicuous in the image 30 because they are fine and the difference in density is small. In particular, when the background color of the image 30 is black, the interference fringes cannot be substantially visually recognized.

  Further, as shown in FIGS. 11C to 11E, in the scanning method of the embodiment, even when the scanning position of the laser beam is shifted from the normal position in the Y-axis direction, the case of FIG. Interference fringes similar to Here, the interference fringes move in the vertical direction in accordance with the shift amount of the scanning position of the laser light. However, also in these cases, the interference fringes generated in the image 30 are very inconspicuous in the image 30 because they are fine and the difference in light and shade is small as in the case of FIG.

  As described above, according to the scanning method of the present embodiment, the interference fringes generated in the image 30 are fine and the difference in density is small, so that the image 30 can be extremely inconspicuous. Therefore, the visibility of the image 30 can be maintained favorably. Further, even if the scanning position of the laser beam is shifted from the normal position in the Y-axis direction, the way in which the interference fringes are generated does not change substantially. Therefore, even if the screen 108 is deformed due to a temperature change or the like, and the scanning position of the laser beam with respect to the screen 108 is relatively displaced in the Y-axis direction, the visibility of the image 30 can be maintained well. .

<Experiment>
The inventors generate the image 30 when the ratio of the scanning line pitch P2 to the pitch P1 of the second lens portion 108b (pitch in the direction perpendicular to the scanning direction of the lens region La1 shown in FIG. 4) is changed. Interference fringes were confirmed by experiments.

  In the experiment, as in the above embodiment, the screen 108 having the first lens portion 108a and the second lens portion 108b formed on the entrance surface and the exit surface, respectively, was used. For the second lens portion 108b, the divergence angle shown in FIG. 7B is not adjusted, and the divergence angle is the same for all the second lens portions 108b.

  The experimental conditions were set as follows.

・ Width of first lens portion 108a: 50 μm
・ Width of the second lens portion 108b: 50 μm
The spread angle of the laser beam by the first lens unit 108a is ± 22 degrees. The spread angle of the laser beam by the second lens unit 108b is ± 10 degrees. The difference between the first lens unit 108a and the second lens unit 108b. Distance: 0.3mm
-Beam diameter on the incident surface of the screen 108 (in the case of FWHM): 45 μm

  Among the above conditions, the spread angle of the laser beam is shown as positive and negative in the direction away from each other about the optical axis of the laser beam. As the screen 108, a screen in which the first lens portion 108a and the second lens portion 108b are respectively formed on the front and back surfaces of a sheet having a thickness of 0.3 mm was used. Therefore, the distance between the first lens portion 108a and the second lens portion 108b was 0.3 mm.

  In the experiment, a white plain image 30 was displayed on the image display device 20 having the same optical system as that in the above embodiment, and the image 30 was captured at the position of the eye box.

  FIG. 12A to FIG. 14B are photographs of images taken in this experiment, respectively. In the upper right corner of each photograph, the ratio (P2 / P1) of the scanning line pitch P2 to the pitch P1 of the second lens portion 108b is added.

  Referring to FIGS. 12A to 14B, it can be seen that according to the scanning method of the embodiment, the difference in density of the interference fringes generated in the image 30 is small, and the interference fringes are not conspicuous. In particular, referring to FIGS. 13A to 14A, when the ratio of the scanning line pitch P2 to the pitch P1 of the second lens portion 108b is in the range of 0.5 to 0.7, the image 30 is generated. It can be seen that the interference fringes are very inconspicuous in the image 30 because the interference fringes are fine and the difference in density is small. In particular, when the ratio of the scanning line pitch P2 to the pitch P1 of the second lens portion 108b is 0.6, almost no interference fringes can be visually recognized in the image 30 as shown in FIG. I understand.

  From the above experimental results, by setting the scanning line pitch P2 smaller than the pitch P1 of the second lens portion 108b (pitch in the direction perpendicular to the scanning direction of the lens region La1 shown in FIG. 4), the image 30 It was confirmed that the interference fringes generated in 1 were made inconspicuous. In particular, by setting the ratio of the scanning line pitch P2 to the pitch P1 of the second lens portion 108b in the range of 0.5 to 0.7, interference fringes generated in the image 30 can be made inconspicuous. It was confirmed that by setting the ratio of the scanning line pitch P2 with respect to the pitch P1 of the second lens portion 108b to about 0.6, it is possible to make the image 30 hardly see any interference fringes. Therefore, the ratio of the scanning line pitch P2 to the pitch P1 of the second lens unit 108b is preferably set in the range of 0.5 to 0.7, and in particular, this ratio is in the vicinity of 0.6. It can be said that setting is preferable.

  In the experiment, the inventors visually confirmed the state of the interference fringes while shifting the scanning position of the laser beam with respect to the screen 108 in the direction perpendicular to the scanning direction. As a result, even if the scanning position of the laser beam with respect to the screen 108 is shifted as described above at the ratio of the pitch P2 to the pitch P1, the interference fringe pattern itself changes substantially even if the interference fringe moves up and down. I didn't. For this reason, deformation or the like occurs in the screen 108 due to a temperature change or the like, and even if the scanning position of the laser beam with respect to the screen 108 is relatively shifted in the direction perpendicular to the scanning direction (Y-axis direction), the interference fringes. It was confirmed that the degradation of the image 30 due to the image could be suppressed and the visibility of the image 30 could be maintained satisfactorily.

  In the scanning method of the embodiment, the reason why the interference fringes are fine and the contrast is small as described above is considered as follows.

  FIG. 15A shows the scanning method of the embodiment, and FIG. 15B shows the scanning method of Comparative Example 2. FIGS. 15A and 15B show the relationship between the second lens portion 108b and the intensity distribution of the laser beam, respectively. The lower part of FIG. 15A shows the intensity distribution when the laser beam scans two scanning lines set in the second lens unit 108b2.

  As shown in FIG. 15A, in the embodiment, the scanning line pitch P2 is set smaller than the pitch P1 of the second lens portion 108b. For this reason, the beam B1 straddles two to three second lens portions 108b (108b-1, 108b-2, 108b-3), and the three second lens portions 108b have different intensity distributions. Light is emitted. One laser beam passes through the plurality of second lens portions 108 b and is emitted, so that the same effect is obtained as when light having the same phase is output from the plurality of openings, and interference fringes are generated in the image 30.

  In the embodiment, when one second lens unit 108b is scanned with a plurality of scanning lines, the intensity of light passing through the three second lens units 108b differs for each line, and thus interference occurs. The stripe pattern is different from each other. Accordingly, while the entire range of the screen 108 is scanned, several kinds of interference fringes having different patterns are generated. At this time, since the scanning frequency for the screen 108 is high as described above, these several kinds of interference fringes are visually recognized in a short time. For this reason, these several kinds of interference fringes are visually averaged (electrically averaged in the case of imaging), and the interference fringes visually recognized as the entire image are thinned and become inconspicuous as a whole. In the scanning method of Comparative Example 2, since only one scanning line is set for one second lens unit 108b, several kinds of interference fringes having different patterns from each other as in the scanning method of the embodiment. Does not occur and the resulting interference fringes are not visually averaged.

  Therefore, regardless of the conditions of the above experiment, the diameter of the beam B1 is set smaller than the width of the lens region La1 in the Y-axis direction (the width of the second lens portion 108b), and the pitch P2 is set smaller than the pitch P1. Then, even if the size of the lens region La1 is different from the above condition, it is assumed that the same effect as the above experiment can be achieved.

<Effect of embodiment>
As described above, according to the present embodiment, the following effects are exhibited.

  As shown in FIG. 11A, the scanning line pitch P2 is set smaller than the pitch P1 of the second lens portion 108b (the pitch in the direction perpendicular to the scanning direction of the lens region La1 shown in FIG. 4). Therefore, as verified in the above experiment, the interference fringes generated in the image 30 can be made inconspicuous. Further, by setting the pitch P2 in this way, even if the screen 108 is deformed due to a temperature change or the like and the scanning position of the laser beam relative to the screen 108 is relatively changed, the interference fringes generated in the image 30 are conspicuous. It can be maintained in a state that is not. Therefore, the visibility of the image 30 can be kept good.

  As verified in the above experiment, the ratio (P2 / P1) of the scanning line pitch P2 to the pitch P1 of the second lens portion 108b (pitch in the direction perpendicular to the scanning direction of the lens region La1) is 0.5. It is preferable to set in the range of 0.7 or more and 0.7 or less. Thereby, as shown to Fig.13 (a)-FIG.14 (a), an interference fringe can be made not conspicuous conspicuously.

  In particular, the ratio (P2 / P1) of the scanning line pitch P2 to the pitch P1 of the second lens portion 108b (pitch in the direction perpendicular to the scanning direction of the lens region La1) may be set to around 0.6. preferable. Thereby, as shown in FIG.13 (b), it can be set as the state from which interference fringes can hardly be visually recognized.

  As shown in FIG. 2, between the light source 101 and the screen 108, a mirror 104 and two dichroic mirrors 105a and 105b (for aligning the optical axes of the laser beams emitted from the three laser light sources 101a to 101c, respectively) An optical axis matching part) is arranged. Thereby, it can suppress that a color breakup arises in an interference fringe. That is, if the optical axes of the laser beams of the respective wavelengths are deviated from each other, the scanning positions of the laser beams of the respective wavelengths on the screen 108 are deviated, and the interference fringes based on the laser beams of the respective wavelengths are deviated. As a result, linear regions of colors based on the respective wavelengths appear at the edges of the interference fringes in a state of being separated from each other. On the other hand, in this embodiment, since the laser light of each wavelength is guided to the screen 108 in a state where the optical axes of the laser light of each wavelength are aligned with each other, the interference fringes based on the laser light of each wavelength are shifted. It does not occur. Therefore, a linear region having a color of each wavelength is generated at the edge of the interference fringe, that is, the color cracking of the interference fringe can be suppressed.

  As shown in FIG. 2, collimator lenses 102 a to 102 c and apertures 103 a to 103 c (for aligning the beam size and beam shape of laser light emitted from the laser light sources 101 a to 101 c, respectively, between the light source 101 and the screen 108 ( A beam shaping unit) is arranged. Thereby, it is suppressed that the beam B1 of another wavelength protrudes largely around the beam B1 of the predetermined wavelength. Therefore, the interference fringes based on the laser light of each wavelength can be made in substantially the same state, and the occurrence of color breakup in the interference fringes can be suppressed.

  Of the laser light sources 101a to 101c, the laser light source 101a that emits a laser beam having a red wavelength has a larger emission angle of the laser light than the other two laser light sources 101b, and therefore the red color after passing through the aperture 103a. The beam size of the laser beam with the wavelength can be slightly larger than the laser beam with the blue wavelength and the laser beam with the green wavelength. However, also in this case, it is possible to suppress the occurrence of color breakup in the interference fringes by aligning the optical axes of the laser beams having the respective wavelengths as described above.

  In addition, when the screen 108 has the configurations of FIGS. 3A and 3B and FIGS. 5A to 7B, the following effects can be achieved.

  In the drawing area D10 where the image is drawn, in the range W1 on both sides excluding the predetermined range W0 in the center of the scanning direction (X-axis direction), the divergence angle in the X-axis direction gradually increases toward the end. Since the screen 108 is configured, the amount of light on both side portions in the eye box is weaker as compared to the center portion as it goes toward the end. For this reason, the brightness of the entire image in the eye box can be made closer to uniform. Further, since the divergence angle of the screen 108 is constant in the predetermined range W0 in the center of the scanning direction (X-axis direction), it is not necessary to precisely adjust the divergence angle in the entire range in the scanning direction. Therefore, the screen 108 can be easily configured.

  The predetermined range W0 is set to a range of 40% to 50% of the entire range of the drawing region D10 in the scanning direction (X-axis direction). Alternatively, the predetermined range W0 is such that when the intensity of the laser beam that scans the screen 108 is constant, the amount of the laser beam that passes through the screen 108 per unit time is that of the drawing region D10 in the scanning direction (X-axis direction). The range is set to be 1.2 times or less of the intermediate position. By setting the predetermined range W0 in this way, it is possible to allow the observer to visually recognize an image without a sense of incongruity due to uneven brightness, particularly without adjusting the divergence angle in the X-axis direction in the predetermined range W0.

  In the present embodiment, since the first lens portion 108a and the second lens portion 108b are respectively disposed on the incident surface and the exit surface of the screen 108, the first lens portion on the incident surface side. It is only necessary to adjust the divergence angle only for 108a. Therefore, the divergence angle with respect to the screen 108 can be easily adjusted.

  Furthermore, in the present embodiment, non-lens regions 108c and 108d of a predetermined size that allow incident light to pass through without divergence are disposed at positions above and below the drawing region D10, respectively. Accordingly, as described with reference to FIGS. 9A to 9C, the screen 108 can be positioned at a predetermined position on a plane parallel to the XY plane by a simple operation.

<Modification 1>
The embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and the application example of the present invention can be modified in various ways in addition to the above embodiment. Is possible.

  For example, in the above embodiment, the first lens portion 108a and the second lens portion 108b are arranged on the incident surface and the exit surface of the screen 108, respectively. On the other hand, a lens group for diverging laser light in the X-axis direction and the Y-axis direction may be arranged.

  FIG. 16A shows a plurality of lens portions 108e (microlens array) for diverging laser light in the scanning direction (X-axis direction) and the direction perpendicular to the scanning direction (Y-axis direction) on the incident surface of the screen 108. It is a figure which shows the structural example which has arrange | positioned. FIG. 16B is an enlarged view of a partial region of FIG. 16A as viewed from the Z-axis positive side.

  In this configuration, one lens unit 108e corresponds to one lens region La1 shown in FIG.

  As shown in FIGS. 16A and 16B, on the incident surface of the screen 108, a predetermined number of rectangular lens portions 108e in a horizontal direction parallel to the X axis and a vertical direction parallel to the Y axis are seen in plan view. It is formed to line up one by one. The lateral widths Wx of the lens portions 108e are the same, and the vertical widths Wy of the lens portions 108e are also the same. The widths Wx and Wy are about several 50 μm. In the example of FIG. 16B, the width Wx and the width Wy are set to the same size, but the width Wx and the width Wy may be different.

  Each lens unit 108e has a different curvature radius Rx in the X-axis direction and a curvature radius Ry in the Y-axis direction. Here, the curvature radius Rx is set smaller than the curvature radius Ry. Accordingly, in the lens portion 108e, the curvature in the X-axis direction is larger than the curvature in the Y-axis direction. By setting the curvature of the lens portion 108e in this manner, the laser beam transmitted through each lens portion 108e can be efficiently and horizontally elongated around the position of the eye 2a of the driver 2 (eye Box area). The curvature of the lens unit 108e is determined according to the shape of the eye box region.

  In this modified example, the curvature radius Rx of each lens unit 108e is constant in the predetermined range W0 shown in FIG. 7A, and the curvature radius Rx of each lens unit 108e is positive or negative on the X axis in the range W1 on both sides. It can be set so as to become smaller as it goes to both ends. Thereby, the distribution of the divergence angle in the X-axis direction shown in FIG. 7B is realized. In addition, the curvature radius Ry of each lens part 108e is the same in all the lens parts 108e. The relationship between the curvature radius Rx and the curvature radius Ry in the predetermined range W0 is set to Rx: Ry = 1: 2, for example.

  As described above, by setting the curvature radii Rx and Ry of the lens portion 108e, the light quantity distribution shown in FIG. As a result, the brightness of the entire image in the eye box can be made nearly uniform.

  Also in this modified example, non-lens regions 108c and 108d are provided at positions above and below the drawing region D10. Thereby, the screen 108 can be positioned at a predetermined position on the XY plane by the simple operation described with reference to FIGS.

  Similarly to the lens used in the above experiment, the curvature radii Rx of all the lens portions 108e may be set to be the same, and the divergence angles in the X-axis direction of all the lens portions 108e may be the same.

  Note that the inventors differ in the state of interference fringes generated in the image 30 between the case where the screen 108 according to the first modification and the screen 108 according to the above embodiment are scanned by the scanning method according to the above embodiment. Was confirmed visually. As a result, even when the screen 108 of the modification example 1 was used, the effect that the interference fringes can be made inconspicuous in the image 30 was confirmed as in the case of using the screen 108 of the above embodiment.

  However, when the screen 108 according to the above embodiment is used, the color breakup of the interference fringes is suppressed as compared with the case where the screen 108 according to the first modification is used. This is because the first lens unit 108a and the second lens unit 108b are separated from each other in the optical axis direction in the screen 108 of the above-described embodiment, and thus the first lens unit 108a diverges due to the separation distance. It is considered that a slight deviation (parallax) occurs between the focal position of the laser beam near the eye box and the focal position of the laser beam diverged by the second lens unit 108b. It is done.

  Therefore, in order to suppress interference fringes and make the interference fringes less noticeable, as in the above-described embodiment, the laser light is incident on the laser light incident surface only in the X-axis direction (first direction). And a plurality of second lens portions 108b for diverging laser light only in a direction perpendicular to the Y-axis direction (second direction) on the laser light emission surface. It can be said that the screen 108 is preferably used.

  In the above embodiment, the first lens portion 108a is formed on the incident surface of the screen 108, and the second lens portion 108b is formed on the exit surface of the screen 108. However, the laser beam is incident on the incident surface of the screen 108. Are formed in the Y-axis direction (second direction), and a plurality of first lenses for diverging laser light in the X-axis direction (first direction) on the exit surface of the screen 108 are formed. The lens portion 108a may be formed.

<Modification 2>
In the above embodiment, the position of the screen 108 is fixed. However, the screen 108 may be moved in the Z-axis direction in the image display operation.

  FIG. 17 is a diagram illustrating a configuration of a circuit used for the irradiation light generation unit 21 and the irradiation light generation unit 21 of the image display device 20 according to the second modification.

  As shown in FIG. 17, in this modified example, a drive unit 109 and a screen drive circuit 204 are added compared to the configuration of FIG. The drive unit 109 reciprocates the screen 108 in a direction (Z-axis direction) parallel to the traveling direction of the laser light. The drive part 109 is comprised by the actuator using a coil and a magnet, for example. For example, a holder that holds the screen 108 is supported by the base via a leaf spring so as to be movable in a direction parallel to the traveling direction of the laser light (Z-axis direction). The coil is installed on the holder side, and the magnet is installed on the base side. The screen drive circuit 204 drives the screen 108 according to the control signal from the image processing circuit 201.

  FIG. 18A is a diagram illustrating an example of the moving process of the screen 108 according to the second modification example, and FIG. 18B is displayed by moving the screen 108 in the image display device 20 according to the second modification example. It is a figure which shows an example of the image performed.

  As shown in FIG. 18A, the movement of the screen 108 is repeated with time t0 to t4 as one cycle. Between times t0 and t1, the screen 108 is moved from the initial position Ps0 to the farthest position Ps1, and between times t1 and t4, the screen 108 is returned from the farthest position Ps1 to the initial position Ps0. The moving period of the screen 108, that is, the time from time t0 to t4 is, for example, 1/60 seconds.

  The time t0 to t1 is a period for displaying the depth image M1 spreading in the depth direction in FIG. 18B, and the time t1 to t4 is the vertical image M2 spreading in the vertical direction in FIG. 18B. This is the period for display. In the example of FIG. 18B, the depth image M1 is an arrow for suggesting to the driver 2 the direction in which the passenger car 1 should turn on the road R1 by the navigation function, and the vertical image M2 has a pedestrian H1. This is a marking for alerting the driver 2. For example, the depth image M1 and the vertical image M2 are displayed in different colors.

  At time t0 to t1, the screen 108 is linearly moved from the initial position Ps0 to the farthest position Ps1. As the screen 108 moves, the position where the virtual image in front of the windshield 12 is formed moves in the depth direction. Therefore, when the screen 108 exists at each position in the depth direction of the depth image M1, the laser light sources 101a to 101c are caused to emit light at the timing corresponding to the depth image M1 on the scanning line corresponding to the depth image M1. A depth image M1 as shown in FIG. 18B can be displayed as a virtual image in front of the projection region 13 of the windshield 12.

  On the other hand, since the vertical image M2 does not change in the depth direction and spreads only in the vertical direction, it is necessary to generate a virtual image with the screen 108 fixed at a position corresponding to the vertical image M2. The stop position Ps2 in FIG. 18A is the position of the screen 108 corresponding to the depth position of the vertical image M2. While the screen 108 returns from the farthest position Ps1 to the initial position Ps0, the screen 108 is stopped at the stop position Ps2 from time t2 to time t3. During this period, the laser light sources 101a to 101c are caused to emit light at the timing corresponding to the vertical image M2 on the scanning line corresponding to the vertical image M2, so that the front of the projection region 13 of the windshield 12 is as shown in FIG. It is possible to display a vertical image M2 as shown in FIG.

  The above control is performed by the image processing circuit 201 shown in FIG. By this control, the depth image M1 and the vertical image M2 are displayed as virtual images between time t0 and time t4. In the above control, there is a difference between the display timing of the depth image M1 and the display timing of the vertical image M2, but since this shift is extremely short, the driver 2 is an image obtained by superimposing the depth image M1 and the vertical image M2. Recognize In this way, the driver 2 can view the image (depth image M1 and vertical image M2) based on the video signal in front of the projection area 13 over the landscape including the road R1 and the pedestrian H1.

  In FIG. 18B, since there is one vertical image M2, the stop position Ps2 of the screen 108 is set to one in the process of FIG. 18A, but if there are a plurality of vertical images M2. Accordingly, a plurality of stop positions are set in the process of FIG. However, in the process of FIG. 18A, the time from time t0 to t4 is constant and time t4 is not changed, so that the moving speed of the screen 108 before and after the stop position (in accordance with the increase or decrease in the number of stop positions ( The slope of the waveform in FIG. 18A is changed.

  Also in this modified example 2, interference fringes generated in the image 30 can be suppressed by using the scanning method of the above embodiment.

<Other changes>
In the above embodiment, the light source 101 is configured to include the three laser light sources 101a to 101c. However, a multi-emitting laser light source in which a plurality of light emitting elements having different emission wavelengths are mounted on a substrate of one laser light source, The light source 101 may be used. In this case, the optical axes of the laser beams emitted from the respective light emitting elements are aligned by, for example, a wavelength selective diffraction grating.

  Moreover, in the said embodiment, although the example which applied this invention to the head-up display mounted in the passenger car 1 was shown, this invention is applicable not only to vehicle-mounted but another kind of image display apparatus. It is.

  The configurations of the image display device 20 and the irradiation light generation unit 21 are not limited to the configurations described in FIG. 1C, FIG. 2, and FIG. 17, and can be changed as appropriate. Further, the first lens portion 108a, the second lens portion 108b, and the lens portion 108e may be integrally formed on the screen 108, or a transparent sheet having these lens portions is attached to the base material of the screen 108. It may be a configuration.

  The embodiments of the present invention can be appropriately modified in various ways within the scope of the technical idea shown in the claims.

20 ... Image display device 22 ... Mirror (optical system)
DESCRIPTION OF SYMBOLS 101 ... Light source 106 ... Scanning part 108 ... Screen 108a ... 1st lens part 108b ... 2nd lens part 203 ... Mirror drive circuit (drive part)
La1 ... Lens area P1, P2 ... Pitch L1 to L7 ... Scan line

Claims (6)

A light source that emits laser light;
A screen on which an image is drawn by being scanned two-dimensionally with the laser beam;
A scanning unit for scanning the screen with the laser beam;
A driving unit that drives the scanning unit so that the laser beam moves on the screen along a plurality of scanning lines parallel to a first direction;
An optical system that generates a virtual image of an image drawn on the screen,
In the screen, a plurality of lens regions are arranged so as to be aligned in the first direction and a second direction perpendicular to the first direction, respectively.
The drive unit sets the plurality of scan lines such that a pitch of the scan lines is smaller than a pitch of the lens regions in the second direction;
An image display device characterized by that. The image display device according to claim 1,
The ratio of the pitch of the scanning line to the pitch of the lens region is set in a range of 0.5 to 0.7.
An image display device characterized by that. The image display device according to claim 1,
The ratio of the pitch of the scanning line to the pitch of the lens area is set to around 0.6.
An image display device characterized by that. In the image display device according to any one of claims 1 to 3,
The light source emits a plurality of types of laser beams having different wavelengths,
Between the light source and the screen, provided with an optical axis alignment unit that aligns the optical axes of the plurality of types of laser light,
An image display device characterized by that. The image display device according to claim 4,
A beam shaping unit for aligning beam sizes and beam shapes of the plurality of types of laser light between the light source and the screen,
An image display device characterized by that. The image display device according to claim 4 or 5,
The screen includes a plurality of first lens portions that diverge the laser light only in the first direction on one of the incident surface and the emission surface of the laser light, and the laser light on the other side. A plurality of second lens portions that diverge only in a direction perpendicular to the second direction, and a region in which the first lens portion and the second lens portion overlap when viewed in the incident direction of the laser light, It is the one lens area,
An image display device characterized by that.