JP6455802B2 - Image display device, object device, transmission screen and screen - Google Patents

Description

  The present invention relates to an image display device, an object device, a transmissive screen, and a screen, and more specifically, an image display device that forms an image by scanning the screen with light, an object device including the image display device, and scanned with light. The present invention relates to a transmissive screen on which an image is formed and the screen.

  2. Description of the Related Art Conventionally, an image display apparatus includes an optical scanning element that scans an object with light modulated in accordance with an image signal to form an image, and a photodetector that receives inspection light from the optical scanning element. It is known (see, for example, Patent Document 1).

  In the image display device disclosed in Patent Document 1, the image quality cannot be stably improved.

The present invention relates to a transmissive screen, an image forming unit that scans the surface of the transmissive screen with light to form an image within a scanning range, and light detection for detecting scanning light that is light from the image forming unit A light introducing portion that introduces the incident scanning light outside the region where the image is formed within the scanning range, and the light introducing portion includes One surface of a recess provided on the surface, the reflection surface reflecting the incident scanning light toward a side end surface of the transmission screen, and the photodetector propagates through the transmission screen and It is an image display device arranged to receive the scanning light emitted from the transmission screen.

  According to the present invention, the image quality can be stably improved.

1 is a diagram schematically illustrating a configuration of an image display device according to an embodiment. It is a figure for demonstrating a light source part. It is a figure for demonstrating the diffusion effect | action by a micro convex lens structure. FIGS. 4A and 4B are diagrams (No. 1 and No. 2) for explaining the diffusion by the fine convex lens and the generation of coherent noise, respectively. FIG. 5A and FIG. 5B are views (No. 1 and No. 2) for explaining the transmission screen of the present embodiment, respectively. FIGS. 6A and 6B are diagrams (No. 1 and No. 2) for explaining optical scanning with respect to the transmission screen of the comparative example, respectively. FIGS. 7A and 7B are views (No. 1 and No. 2) for explaining optical scanning with respect to the transmission screen of the present embodiment, respectively. FIG. 8A and FIG. 8B are diagrams (No. 1 and No. 2) for explaining the transmission screen of Modification Example 1, respectively. FIG. 9A and FIG. 9B are diagrams (No. 1 and No. 2) for explaining the transmission screen of Modification Example 2, respectively.

  Hereinafter, an embodiment will be described.

  An image display apparatus 1000 according to an embodiment is a head-up display (HUD) that displays a two-dimensional color image, and FIG. 1 schematically illustrates the entire apparatus.

  As an example, the image display apparatus 1000 is mounted on a moving body such as a vehicle, an aircraft, and a ship, and navigation information (for example, speed) necessary for maneuvering the moving body through the windshield 10 (front windshield) of the moving body. , Information such as travel distance) is made visible. In this case, the windshield 10 also functions as a transmission / reflection member that transmits a part of the incident light and reflects at least a part of the remaining part. In the following description, an abc three-dimensional orthogonal coordinate system (coordinate system that moves with the moving body) set for the moving body is used as appropriate. Here, the a direction is the left-right direction of the moving body (the + a direction is the right direction and the -a direction is the left direction), and the b direction is the up-down direction of the moving body (the + b direction is the upward direction and the -b direction is the downward direction). The c direction is the front-rear direction of the moving body (the -c direction is the forward direction and the + c direction is the backward direction). Hereinafter, an example in which the image display apparatus 1000 is mounted on a vehicle (for example, an automobile) will be described.

  In FIG. 1, a portion denoted by reference numeral 100 is a “light source unit”, and a pixel display beam LC for color image display is emitted from the light source unit 100.

  The pixel display beam LC includes one beam of three colors of red (hereinafter referred to as “R”), green (hereinafter referred to as “G”), and blue (hereinafter referred to as “B”). This is a combined beam.

  That is, the light source unit 100 has a configuration as shown in FIG.

  In FIG. 2, a semiconductor laser as a light source indicated by reference signs RS, GS, and BS emits R, G, and B laser beams, respectively. Here, a laser diode (LD) also called an edge emitting laser is used as each semiconductor laser.

  Coupling lenses indicated by reference numerals RCP, GCP, and BCP suppress the divergence of each laser beam emitted from the semiconductor lasers RS, GS, and BS.

  Each color laser beam whose divergence is suppressed by the coupling lenses RCP, GCP, and BCP is shaped by the aperture RAP, GAP, and BAP (the beam diameter is regulated).

The shaped laser beam of each color enters the beam combining prism 101.
The beam combining prism 101 includes a dichroic film D1 that transmits R color light and reflects G light, and a dichroic film D2 that transmits R and G color light and reflects B color light.

  Accordingly, the R, G, and B color laser beams are combined into one beam and emitted from the beam combining prism 101.

The emitted light beam is converted into a “parallel beam” having a predetermined light beam diameter by the lens 102.
This “parallel beam” is the pixel display beam LC.

  The R, G, and B color laser beams constituting the pixel display beam LC are intensity-modulated (according to image data) by an image signal of a “two-dimensional color image” to be displayed.

  Here, the emission intensity of the semiconductor lasers RS, GS, and BS is modulated (directly modulated) by the image signals of the R, G, and B color components by the LD driver 11 as a light source driving unit. Instead of direct modulation, the laser light emitted from each semiconductor laser may be modulated (external modulation) by an optical modulator.

  The pixel display beam LC emitted from the light source unit 100 enters the two-dimensional deflection unit 6 and is two-dimensionally deflected.

  In the present embodiment, the two-dimensional deflecting means 6 is configured to swing a minute mirror with “two axes orthogonal to each other” as a swing axis.

  That is, the two-dimensional deflection unit 6 is specifically a two-dimensional scanner including a MEMS (Micro Electro Mechanical Systems) mirror manufactured as a micro oscillating mirror element by a semiconductor process or the like. The two-dimensional deflection unit 6 is controlled by the controller 12. Hereinafter, the MEMS mirror of the two-dimensional deflection means 6 is also referred to as “oscillating mirror”.

  The controller 12 generates a synchronization signal (image output signal) based on a detection signal from the PD 13 described later, and outputs it to the LD driver 11. The LD driver 11 causes each semiconductor laser to emit light (lights on) based on the synchronization signal from the controller 12.

  The two-dimensional deflecting means is not limited to this example, but has another configuration, for example, two micro mirrors (for example, a MEMS mirror or a galvano mirror) that swing around one axis, and the swing directions are orthogonal to each other. It may be a combination.

  The pixel display beam LC deflected two-dimensionally as described above enters the scanning mirror 7 (for example, a concave mirror) and is reflected toward the transmission screen 8.

  The scanning mirror 7 is designed to correct the bending of the scanning line (scanning locus) generated on the transmission screen 8.

  The pixel display beam LC reflected by the scanning mirror 7 is incident on the transmission screen 8 while being translated along with the deflection by the two-dimensional deflection means 6, and scans the transmission screen 8 two-dimensionally. That is, the transmission screen 8 is two-dimensionally scanned (for example, raster scan) in the main scanning direction and the sub-scanning direction by the pixel display beam LC.

  By this two-dimensional scanning, a “two-dimensional color image” as an intermediate image is formed on the transmission screen 8. Here, a rectangular image display area (also referred to as an effective scanning area) on the transmission screen 8 is two-dimensionally scanned, and an intermediate image is formed in the image display area (see FIG. 3).

  That is, an intermediate image forming unit (image forming unit) that forms an intermediate image (image) on the transmission screen 8 includes the light source unit 100, the two-dimensional deflection unit 6, and the scanning mirror 7.

  Of course, what is displayed on the transmissive screen 8 at each moment is “only the pixel irradiated with the pixel display beam LC at that moment”.

A color two-dimensional image is formed as a “collection of pixels displayed at each moment” by two-dimensional scanning with a pixel display beam LC.
The “two-dimensional color image” is formed on the transmission screen 8 as described above, and the pixel display beam LC that forms the two-dimensional color image, that is, the light transmitted through the transmission screen 8 is applied to the concave mirror 9 (concave mirror). Incident and reflected.

  Although not shown in FIG. 1, the transmissive screen 8 has a “fine convex lens structure” that transmits each pixel display beam LC in an image display region, as will be described later. The concave mirror 9 constitutes a “virtual image imaging optical system”.

  In the vicinity of the transmission screen 8, a PD 13 (photodiode) as a photodetector for detecting scanning light that is light from the intermediate image forming unit is disposed. The detection signal of the PD 13 is output to the controller 12.

  As will be described in detail later, the concave mirror 9 is a horizontal line in the virtual image of the “two-dimensional color image” (intermediate image) formed on the transmission screen 8 by the influence of the curved windshield 10 that is inclined with respect to the horizontal plane. It is designed and arranged so as to correct the two-dimensional distortion in which the (horizontal line) is vertically convex and the two-dimensional distortion in which the vertical line (vertical line) is horizontally convex.

The “virtual image imaging optical system” forms a virtual image I of the “color image”.
A windshield 10 is disposed in front of the imaging position of the virtual image I, and reflects the light beam that forms the virtual image I toward the observer (for example, the operator of the moving object). The observer visually recognizes a virtual image from an eye box (an area near the eyes of the observer) on the optical path of the laser light reflected by the windshield 10 (transmission / reflection member). Here, the eye box means a range in which a virtual image can be visually recognized without adjusting the position of the viewpoint.

  The observer can visually recognize the virtual image I by the reflected light.

  In the case shown in FIG. 1, the direction a is usually the left-right direction for the observer, and this direction is also referred to as the “lateral direction”. A direction orthogonal to the horizontal direction (direction a) is also referred to as a “vertical direction”.

As described above, the transmission screen 8 has a fine convex lens structure in the image display area.
As will be described later, the micro-convex lens structure is “a plurality of micro-convex lenses (micro lenses) are two-dimensionally arranged closely at a pitch close to the pixel pitch”. That is, the transmissive screen 8 has a microlens array in the image display area.

  Here, the plurality of micro convex lenses are two-dimensionally arranged at a predetermined pitch along the virtual plane so that the convex surface becomes the incident surface. As a specific arrangement form, for example, a matrix-like arrangement in which a direction (X direction) is a row direction and one direction (Y direction) orthogonal to the a direction in the virtual plane is a column direction, or a honeycomb shape (A zigzag array).

  The planar shape of each micro-convex lens is, for example, a circle or a regular N-gon (N is a natural number of 3 or more). Here, each of the fine convex lenses has the same curvature (curvature radius).

  Each fine convex lens has a function of isotropically diffusing the pixel display beam LC. That is, each fine convex lens has an even diffusion power in all directions. The “diffusion function” will be briefly described below.

  In FIG. 3, reference symbols L <b> 1 to L <b> 4 indicate four pixel display beams incident on the transmission screen 8.

  These four pixel display beams L <b> 1 to L <b> 4 are pixel display beams incident on the four corners of the image formed on the transmission screen 8.

  When these four pixel display beams L1 to L4 are transmitted through the transmission screen 8, they are converted into beams L11 to L14.

  If a cross-sectionally surrounded quadrilateral light beam surrounded by the pixel display beams L1 to L4 is incident on the transmission screen 8, this light beam will be "a cross-section surrounded by the beams L11 to L14 is a horizontally long quadrilateral. "Divergent luminous flux".

  This function of the micro-convex lens is a “diffusion function”.

  The “divergent light beam surrounded by the beams L11 to L14” is a result of temporally collecting the pixel display beams thus converted into the divergent light beam.

  The pixel display beam is diffused so that “the light beam reflected by the windshield 10 irradiates a wide area near the eyes of the observer”.

  In the absence of the diffusing function, the light beam reflected by the windshield 10 irradiates only the “narrow region near the eyes of the observer”.

  For this reason, when the observer moves his / her head and the position of the eyes deviates from the “narrow area”, the observer cannot visually recognize the virtual image I.

  As described above, the light beam reflected by the windshield 10 irradiates a “wide area near the eyes of the observer” by diffusing the pixel display beam LC. That is, the eye box can be enlarged.

  Therefore, even if the observer “moves his head a little”, the virtual image I can be reliably recognized.

  Hereinafter, with reference to FIGS. 4A and 4B, diffusion and generation of coherent noise in the microlens array used in the image display area of the transmissive screen 8 will be described.

In FIG. 4A, reference numeral 802 denotes a microlens array. The micro lens array 802 has a micro convex lens structure in which micro convex lenses 801 are arranged. The beam diameter 807 of the “pixel display beam” indicated by reference numeral 803 is smaller than the size of the fine convex lens 801. That is, the size 806 of the fine convex lens 801 is larger than the beam diameter 807. In the present embodiment, the pixel display beam 803 is a laser beam, and forms a Gaussian light intensity distribution around the center of the beam. Therefore, the light beam diameter 807 is a distance in the radial direction of the light beam at which the light intensity in the light intensity distribution decreases to “1 / e ² ”.

In FIG. 4A, the light beam diameter 807 is drawn equal to the size 806 of the fine convex lens 801, but the light beam diameter 807 does not have to be equal to “the size 806 of the fine convex lens 801”.
The size 806 of the fine convex lens 801 may not be taken out.
In FIG. 4A, the entire pixel display beam 803 is incident on one minute convex lens 801 and converted into a diffused light beam 804 having a divergence angle 805. The “divergence angle” may be referred to as “diffusion angle” below.

  In the state of FIG. 4A, there is only one diffused light beam 804 and no interfering light beam, so that no coherent noise is generated. The size of the divergence angle 805 can be set as appropriate depending on the shape of the fine convex lens 801.

  In FIG. 4B, the pixel display beam 811 has a light beam diameter that is twice the arrangement pitch 812 of the fine convex lenses, and is incident across the two fine convex lenses 813 and 814. In this case, the pixel display beam 811 is diffused as two divergent light beams 815 and 816 by the two incident micro convex lenses 813 and 814. The two divergent light beams 815 and 816 overlap in a region 817 and interfere with each other in this portion to generate coherent noise.

  As described above, the head-up display described above can be used for in-vehicle use such as an automobile, for example. The a direction is “lateral direction when viewed from the driver's seat” and the b direction is “vertical direction”.

  In this case, for example, a “navigation image” can be displayed as a virtual image I in front of the windshield 10 of an automobile or the like, and the driver who is an observer moves the line of sight from the front of the windshield 10 while staying in the driver's seat. Can be observed.

  In such a case, as described above, the displayed virtual image I is “a horizontally long image when viewed from the driver”, that is, the image (intermediate image) formed on the microlens array and the virtual image I are a It is generally preferable that the image has a large angle of view in the direction.

In addition, as described above, when the driver who is an observer looks at the display image from the left and right oblique directions, the horizontal direction has a “large viewing angle compared to the vertical direction” so that the display can be recognized. Required.
For this reason, the longitudinal direction (a direction) of the virtual image I is required to have a larger diffusion angle (isotropic diffusion) than the short direction (b direction).

  Therefore, each micro-convex lens (micro lens) of the micro-convex lens structure (micro lens array) is an anamorphic lens having a curvature in the longitudinal direction larger than the short direction of the intermediate image or virtual image I formed on the transmission screen 8. It is preferable that the diffusion angle for diffusing the pixel display beam is “the horizontal direction of the intermediate image is wider than the vertical direction”.

  In this way, it is possible to diverge light within the minimum necessary range that satisfies the required angle of view of the head-up display, improve the light utilization efficiency, and improve the brightness of the display image.

Of course, it is also possible to use “isotropic diffusion” in which the diffusion angles are equal in the vertical direction and the horizontal direction, instead of the “isotropic diffusion” as described above.
However, in the case of a head-up display used for in-vehicle use such as an automobile, it is not easy for the driver to observe the display image from a vertical position.
Therefore, in such a case, as described above, it is preferable from the viewpoint of light utilization efficiency that the diffusion angle for diffusing the pixel display beam is “wider the horizontal direction of the intermediate image than the vertical direction”.

  It has been conventionally known that a micro-convex lens (micro lens) can be formed as an “aspherical surface”.

  The anamorphic lens surface described immediately above is also “aspherical”, but the lens surface of the micro-convex lens can be formed as a more general aspherical surface, and aberration correction can also be performed.

  It is also possible to reduce “diffuse intensity unevenness” by correcting aberrations.

  The micro-convex lens having the micro-convex lens structure diffuses the pixel display beam as described above. However, it may be possible to diffuse only one of the two directions of the x direction and the y direction.

  In such a case, a “fine convex cylinder surface” can be used as the lens surface of the fine convex lens.

  It has been conventionally known that the shape of the micro-convex lens is a hexagonal shape and the arrangement thereof is a honeycomb type in relation to the method of manufacturing the microlens array.

  Hereinafter, the overall configuration of the transmission screen 8 will be described in detail. FIG. 5A shows a plan view of the transmissive screen 8. FIG. 5B shows a cross-sectional view taken along line AA of FIG.

  As an example, as shown in FIG. 5A, the transmission screen 8 has a microlens array as a fine convex lens structure in a predetermined region (image display region) of a substantially rectangular plate-like substrate whose longitudinal direction is the a direction. Is a member formed. Hereinafter, an XYZ three-dimensional orthogonal coordinate system (the X direction coincides with the a direction and the Y direction is orthogonal to the X direction within the surface of the transmissive screen 8) set for the transmissive screen 8 will be described as appropriate. Here, the X direction is the main scanning direction, and the Y direction is the sub-scanning direction.

  As the base material of the transmissive screen 8, for example, a light transmissive material (preferably a material having a higher refractive index than air) such as a transparent resin material or a transparent glass material is used.

  A light introducing portion 8 a for introducing incident scanning light (sampling light) into the inside of the transmissive screen 8 is provided at a predetermined position within the scanning range of the transmissive screen 8 and outside the image display area. The “scanning range” means the entire area including the image display area optically scanned by the two-dimensional deflection unit 6.

  More specifically, as can be seen from FIGS. 5A and 5B, the light introducing portion 8a is located in the vicinity of the −X side of the corner portion on the −X side and + Y side of the image display area of the transmissive screen 8 ( An XZ cross-section formed so as to extend in the Y-axis direction intersecting with an extension line on the −Y side of the image display area that is a scanning start position by the two-dimensional deflection unit 6 (at a position adjacent to the corner) This is an inclined groove (inclined recess) having a triangular shape (for example, a right triangle).

  The inclined groove has an inclined surface which is inclined with respect to the XY plane and faces the −X side end surface of the transmissive screen 8. This inclined surface functions as a reflecting surface that reflects the scanning light incident from the −Z side toward the −X side.

  As the inclined surface, the resin-molded surface or the glass-molded surface of the base material of the transmissive screen 8 may be used as it is, or mirror surface processing or a reflective film coat for increasing the reflectance may be applied.

  The scanning light incident on the inclined surface (reflecting surface) of the light introducing portion 8a is reflected on the −X side and propagates (waveguides) in the −X direction while being subjected to multiple reflection in the transmission screen 8.

  The light propagating through the transmissive screen 8 in the −X direction is transmitted to the −X side of the light introducing portion 8a at the −X side end surface of the transmissive screen 8 (for example, the resin molded end surface or the glass molded end surface of the base material of the transmissive screen 8). The light is emitted (taken out) from a predetermined location. Therefore, this predetermined portion is also referred to as “light extraction portion 8b”.

  The light introducing portion 8a only needs to have a function of directing the traveling direction of the irradiated (incident) scanning light toward the light extracting portion 8b. Instead of the inclined surface, XY in which fine unevenness is formed. The scattering surface may be inclined with respect to the plane.

  Moreover, the light extraction part 8b should just be able to radiate | emit the scanning light which propagates the inside of the permeation | transmission screen 8, and as above-mentioned, you may utilize a resin molding end surface or a glass molding end surface as it is, and in order to raise detection sensitivity, PD13 A lens structure matching the light receiving sensitivity and the size of the light receiving surface may be used.

  PD13 is arrange | positioned so that the scanning light radiate | emitted from the light extraction part 8b can be received. Specifically, the PD 13 is fixed to the screen mounting jig together with the transmissive screen 8 with the light receiving surface facing the + X side of the light extraction portion 8b (FIGS. 7A and 7B). )reference).

  Here, drawing of an image on a transmissive screen by an image display device (for example, HUD) of a comparative example will be described. FIG. 6A shows a plan view of a transmission screen of a comparative example. FIG. 6B shows a cross-sectional view along A′-A ′ of FIG.

  In the comparative example, as shown in FIGS. 6A and 6B, a PD (photodiode) for detecting the scanning timing of the laser beam by the transmission screen and the two-dimensional scanner on the screen mounting jig. Is attached. The light receiving surface of the PD faces the same side (−Z side) as the incident surface of the transmissive screen, and the laser beam is within a range including the image drawing area (image display area) of the PD and the transmissive screen by a two-dimensional scanner. Scanned. At this time, the output timing of the synchronization signal (image output signal) to the LD (laser diode) as the light source is adjusted based on the detection signal of the PD when the PD is scanned.

  In this case, since it is necessary to shift the timing at which the PD detects light and the drawing start timing in accordance with the shift in the mounting position of the PD and the transmissive screen with respect to the screen mounting jig, the scanning start timing for each individual image display device Calibration is required. In addition, since it is necessary to scan the range including the PD and the image drawing area, the proportion of time available for image output decreases, and the brightness of the image decreases.

  On the other hand, in this embodiment, as shown in FIGS. 7A and 7B, the scanning range includes the light introducing portion 8a and the image display area, and does not include the position of the PD 13. The light receiving surface of the PD faces the end surface side (+ X side) of the transmissive screen 8 on the −X side.

  Therefore, the scanning light incident on the light introducing portion 8a is reflected to the −X side by the inclined surface, propagates (waveguides) while being reflected in the inside of the transmission screen 8, is emitted from the light extraction portion 8b, and is output from the PD 13 Light is received and detected.

  In this case, since the detection timing of the laser light is determined by the position of the light introducing portion 8a, the beam position can be detected with high accuracy regardless of variations in the attachment positions of the transmission screen 8 and the PD 13. Further, since the scanning range may be a range including the image display area and the light introducing portion 8a, it is possible to secure a sufficient time for image output and output an image with high luminance.

  The image display apparatus 1000 (head-up display) according to the present embodiment described above includes a transmissive screen 8, an image forming unit that scans the surface of the transmissive screen 8 with light, and forms an image within a scanning range, and the image. PD 13 as a light detector for detecting scanning light as light from the forming unit, and is incident on the transmission screen 8 outside the region (image display region) where the image is formed within the scanning range. The light introduction part 8a for introducing the scanning light is provided, and the PD 13 is disposed so as to be able to receive the scanning light that propagates through the transmission screen 8 and is emitted from the transmission screen 8.

  In this case, since the positional relationship between the image display area serving as a reference for detecting the position of the scanning light and the light introducing portion 8a is not changed, the positional relationship between the transmissive screen 8 and the PD 13 (the positional shift due to the assembly or the position due to the temporal change). Even if a deviation occurs, the position of the scanning light can be detected with high accuracy.

  As a result, the image quality can be improved stably.

  On the other hand, in the image display device of Patent Document 1, if a positional relationship between the optical scanning element and the photodetector (photodetector) (including positional deviation during assembly and positional deviation due to aging) occurs, the position of the scanning light Cannot be detected with high accuracy, and as a result, the image quality cannot be stably improved.

  Further, in Patent Document 1, since it is necessary to mount the optical scanning element and the photodetector with high positional accuracy, the mounting cost increases, and the beam scanning area needs to be wider than the image display area. There is a problem that a useless scanning time that does not contribute occurs and it is difficult to ensure the brightness (luminance) of the image.

  Further, in the transmission screen 8, the light introducing portion 8a can be provided in the vicinity of the image display area, and the position of the scanning light can be detected in the immediate vicinity of the image display area. For this reason, it is possible to accurately generate an image output signal (synchronization signal) with respect to the position of the scanning light, and it is not necessary to widen the scanning range with respect to the image display area. It is possible to reduce and secure the brightness (brightness) of the image.

  Further, since the transmission screen 8 is made of a light-transmitting material, the scanning light can be introduced, propagated inside, and emitted by a simple configuration in which a light introduction portion 8a (for example, an inclined groove) is provided on the surface. it can. The transmission screen 8 can be easily manufactured by molding using a transparent resin material or a transparent glass material.

  The light introducing portion 8 a is one surface of an inclined recess (inclined groove) provided on the surface of the transmissive screen 8, and has a reflection surface that reflects incident scanning light toward the side end surface of the transmissive screen 8. Therefore, the scanning light can be reliably emitted from the side end face.

  Further, when the reflecting surface of the light introducing portion 8 a is an inclined surface that is inclined with respect to the surface of the transmission screen 8, the incident scanning light is efficiently (light utilization efficiency) from a narrow range of the side end surface of the transmission screen 8. Can be emitted. As a result, a stable amount of scanning light can be incident on the PD 13.

  Further, when the reflection surface of the light introducing portion 8 a is a scattering surface that is inclined with respect to the surface of the transmission screen 8, the incident scanning light can be emitted from a wide range of the side end surface of the transmission screen 8. As a result, the scanning light can be incident on the PD 13 even if the positional deviation between the PD 13 and the transmission screen 8 is somewhat large.

  In addition, when a lens structure is provided on the side end surface of the transmission screen 8, the scanning light can be stably incident (condensed) on the PD 13.

  In addition, since the light introducing portion 8a is provided on one side of the image display area in the main scanning direction, the expansion of the scanning range in the sub scanning direction can be suppressed as much as possible. Since the scanning speed is usually slower in the sub-scanning direction than in the main scanning direction, enlarging the scanning range in the sub-scanning direction requires a lot of useless scanning time compared to enlarging the scanning range in the main scanning direction. , Leading to a decrease in the brightness of the image.

  Further, since the light introducing unit 8a is provided at a position corresponding to the scanning start position in the sub-scanning direction of the image display area, it is possible to detect at least a shift between the scanning start timing in the sub-scanning direction and the image output timing. Therefore, the image quality can be improved.

  Further, since the transmissive screen 8 has a microlens array in the image display area, it is possible to further improve the image quality (virtual image visibility).

  Further, since the image display apparatus 1000 further includes a concave mirror 9 (optical system) that guides the light that forms the image from the transmission screen 8 to the transmission / reflection member, the image display device 1000 transmits the virtual image I that is enlarged and suppressed in distortion to the transmission / reflection member. It can be made visible through the.

  Further, in a moving body device including the image display device 1000 and a moving body on which the image display device 1000 is mounted, an observer (for example, a driver of the moving body) can quickly and reliably visually recognize the virtual image I without stress.

  The transmissive screen 8 is a transmissive screen that is scanned with light and forms an image within the scanning range, and a light introducing portion 8a that introduces incident light outside the region where the image is formed within the scanning range. Is provided.

  In this case, it is possible to emit sampling light (scanning light) that is an accurate reference for detecting the position of the scanning light.

  By the way, the timing at which the laser beam is deflected and scanned by the oscillating mirror may slightly deviate depending on the position in the sub-scanning direction. For example, when a linear pattern is drawn in the sub-scanning direction, the straight line is wavy. May be.

  Therefore, in Modification 1 shown in FIG. 8A and FIG. 8B, which is a sectional view taken along the line BB of FIG. 8A, to detect a shift in scanning timing due to a position in the sub-scanning direction. The light introducing portion 18a is formed so as to include a position corresponding to the entire area of the image display area in the sub-scanning direction. In FIGS. 8A and 8B, the screen mounting jig is not shown.

  More specifically, the light introducing portion 18a is formed to be elongated in the Y-axis direction along the −X side side of the image display region so as to protrude to the + Y side and the −Y side from the side.

  In this case, the scattering surface in which fine irregularities are formed on the reflection surface of the light introducing portion 18a (inclined groove) so that the sampling light introduced from an arbitrary position in the Y-axis direction in the light introducing portion 18a reaches the PD 13. It is a surface. In addition, here, the PD 13 is disposed at a position near the −X side of the central portion in the Y axis direction of the end surface on the −X side of the transmission screen, but is disposed at a position shifted in the Y axis direction from this position. Also good.

  In the second modification, the light introducing portion 18a is formed so as to include the position corresponding to the entire area of the image display area in the sub-scanning direction. What is necessary is just to provide in the position corresponding to the whole area of a scanning direction.

  Further, as in Modification 2 shown in FIG. 9A and FIG. 9B, which is a cross-sectional view taken along the line CC of FIG. 9A, the two light introducing portions 28a and 28b are displayed as images. It may be formed individually at two positions corresponding to the scanning start position (the + Y side of the image display area) and the scanning end position (the −Y side of the image display area) in the sub-scanning direction of the area. By measuring the detection timing of the sampling light between these two positions, it is possible to adjust the moving range in the sub-scanning direction and the timing of the image output signal more accurately and improve the image quality. In FIGS. 9A and 9B, the screen mounting jig is not shown.

  In the second modification, the reflecting surface of each light introducing portion may be an inclined surface of an inclined groove or a scattering surface inclined by an inclined groove. One PD 13 may be provided on the −X side of the two light introducing portions 28a and 28b, or one PD 13 may be provided on the −X side in the center of the two light introducing portions 28a and 28b.

  In the second modification, the light introducing section is provided at two positions corresponding to the scanning start position and the scanning end position in the sub-scanning direction of the image display area. It may be provided in at least one of the two positions.

  In the second modification, the two light introducing portions 28a and 28b are provided. However, for example, at least one light introducing portion may be provided between the two light introducing portions 28a and 28b.

  In the second modification, each light introducing portion extends in the Y-axis direction (the inclined surface and the scattering surface face the −X side), but this is not limiting, and in particular, only one PD 13 is provided. When used, at least one of a plurality of (for example, two) light introducing portions may be formed so as to extend in a direction inclined in the Y-axis direction so that the inclined surface or scattering surface faces the PD 13 side. In this case, the scanning light can be efficiently incident on the PD 13.

  Moreover, in the said embodiment and each modification, although the light introduction part is provided in the -X side (one side of the main scanning direction) of an image display area, it replaces with or in addition to this, It may be provided on the + X side (the other side in the main scanning direction). In this case, it is preferable to arrange the PD on the + X side of the transmission screen.

  Moreover, in the said embodiment and each modification, you may give a curvature to the reflective surface of a light introduction part. In short, the light introduction part is a recess provided outside the image display area within the scanning range of the surface of the screen (transmission screen or reflection screen), and the incident scanning light is directed toward the side end face of the screen. It is preferable that it is a recessed part which makes the reflective surface to reflect reflect.

  Moreover, in the said embodiment and each modification, although the light introduction part is provided in the -X side (one side of the main scanning direction) of an image display area, it replaces with or in addition to this, It may be provided on at least one of the + Y side (one side in the sub-scanning direction) and the -Y side (the other side in the sub-scanning direction). In this case, it is preferable to arrange the PD on at least one of the + Y side and the −Y side of the transmission screen.

  In the above embodiment and each modification, the scanning light introduced from the light introducing portion and propagated through the transmissive screen is taken out from the side end surface of the transmissive screen. However, the present invention is not limited to this. It is also possible to provide a light extraction unit in the optical extraction unit and extract the scanning light from the light extraction unit. As this light extraction portion, a reflection surface (an inclined surface or an inclined scattering surface) that is located on the propagation path of the scanning light from the reflection surface of the inclined groove of the light introducing portion and is inclined in the opposite direction to the reflection surface. And an inclined groove. In this case, it is preferable to arrange the PD at a position where the scanning light reflected by the reflecting surface of the inclined groove can be received (the front side or the back side of the transmission screen).

  Moreover, in the said embodiment and each modification, although the transmissive screen which consists of a material which has a light transmittance is used as it is as a screen scanned with light, it is not restricted to this.

  For example, a reflective screen in which a reflective film is formed over the entire image display area of the transmissive screen may be used.

  In addition, as a screen scanned by light, a light introducing portion provided outside an image display area constituted by a reflecting surface in a scanning range, and light propagation for propagating light introduced from the light introducing portion A reflection screen provided with a structure and a light extraction portion for extracting light propagated through the light propagation structure may be used. Therefore, an image display device provided with this reflective screen can also be provided.

  The light propagation structure of the reflection screen may be, for example, a cylindrical structure (light propagation path) formed of a material that reflects at least part of light, or a pair of light that reflects at least part of light. A structure in which light is propagated between reflecting surfaces may be used. In this case, it is preferable that the light propagation structure is terminated at the side end face of the reflection screen, and a light transmission window (or lens structure) as a light extraction portion is provided on the side end face. In addition, a light extraction portion including an inclined groove having a reflection surface and a light transmission window (or lens structure) may be provided on the front or back surface of the reflection screen, and the light propagation structure may be terminated at the light extraction portion.

  In the above embodiment and each modification, a color image is formed using a plurality of light sources, but a monochrome image may be formed using a single light source.

  In the above-described embodiment and each modification, the fine convex lens structure (microlens array) is provided in the image forming area of the transmission screen. However, the present invention is not limited to this. For example, a diffusion plate having a random uneven structure is provided. Also good. Also in this case, generation of speckle noise can be suppressed to some extent. This diffusing plate may be transmissive or reflective.

  In the above-described embodiment and each modification, a two-dimensional image is formed by two-dimensional scanning using a two-dimensional deflecting unit on the screen. For example, a one-dimensional image including a MEMS mirror, a galvanometer mirror, a polygon mirror, etc. A one-dimensional image may be formed by one-dimensional scanning using a deflection unit.

  Moreover, in the said embodiment and each modification, although LD (edge emitting laser) is used as a light source, not only this but VCSEL (surface emitting laser), lasers other than a semiconductor laser, and light sources other than a laser are used. May be.

Moreover, in the said embodiment and each modification, the photodiode is used as a photodetector, It is not restricted to this, For example, you may use a phototransistor etc.

  In the above embodiment and each modification, the optical system that guides the light from the light source to the transmissive screen 8 can be changed as appropriate. For example, the scanning mirror 7 may be omitted. In this case, the light deflected by the two-dimensional deflection means 6 may be directly incident on the transmission screen 8.

  In the above-described embodiment and each modification, a plane mirror may be provided as the scanning mirror 7 instead of the concave mirror.

  Moreover, in the said embodiment and each modification, it may replace with or add to the concave mirror 9, and may provide a plane mirror and a convex mirror.

  Moreover, in the said embodiment and each modification, although the intermediate image (image display area) on the transmissive screen 8 is a rectangle, it is not restricted to this, For example, parallelograms other than rectangles, such as circular, an ellipse, and a square The regular polygon may be a pentagon or more.

  In addition, the transmission / reflection member is not limited to the windshield of the moving body, but for example, a passenger of the moving body such as a side glass and a rear glass (for example, a pilot, a navigator, a crew member, a passenger) can visually recognize the outside of the moving body. Other window members may be used. Further, the transmission / reflection member is not limited to glass but may be made of resin, for example. Further, the shape of the transmissive reflecting member can be changed as appropriate.

  The transmission / reflection member is formed of a member different from the window member (for example, the windshield) of the moving body, for example, a so-called combiner, and is disposed in front of the window member as viewed from the observer. Also good.

  Moreover, in the said embodiment and each modification, although the image display apparatus demonstrated as an example what was mounted in moving bodies, such as a vehicle, an aircraft, a ship, etc., the point will be as long as it is mounted in an object. good. Also in this case, an object device including an object and an image forming apparatus mounted on the object can obtain the same effects as those of the above-described embodiment and each modification. In this case, the image display apparatus may or may not include a transmission / reflection member as a component. Note that the “object” includes, in addition to a moving object, a permanently installed object and a transportable object.

  Further, the image display device of the present invention is not limited to the one mounted on the object, but can be applied to, for example, a device installed alone or a device that can be attached to a human body (for example, a head mounted display). For example, it can be implemented as an image display device for movie appreciation.

  Below, the thought process which the inventor of this invention came up with with respect to the said embodiment and each modification is demonstrated.

  2. Description of the Related Art In recent years, technological development of a HUD (head-up display) mounted on a vehicle, which is expected in the market as an application that allows a driver to recognize warnings and information with a small line of sight movement, is progressing. In particular, with the advancement of in-vehicle sensing technology represented by the term ADAS (Advanced Driving Assistance System), vehicles are able to capture various driving environment information and in-vehicle occupant information. HUD is attracting attention as an “ADAS exit” to be communicated to the driver.

  The HUD projection method is a “panel method” in which an intermediate image is expressed by an imaging device such as liquid crystal or DMD, and a laser beam emitted from a semiconductor laser is scanned by a two-dimensional scanning device including a deflection mirror to form an intermediate image. There is a “laser scanning method”. In particular, the latter laser scanning method is different from the former panel method in which an image is formed by partial light-shielding of full screen light emission, so that light emission / non-light emission can be assigned to each pixel. Can be formed.

  By the way, in a laser scanning type HUD using a deflecting mirror, there is a problem that the image quality deteriorates due to a difference between the timing of operating the deflecting mirror and the timing of image output (laser lighting timing).

  To solve this problem, (1) a method of adding a sensor structure for angle detection to the deflection mirror, (2) a part of light reflected by the deflection mirror is detected by a photodetector placed outside the image forming area, A method of correcting the timing of image output from the position of the photodetector and the detection signal has been studied. However, in (1), the structure of the deflecting mirror is complicated, and it is difficult to manufacture at an appropriate cost. In 2), the photodetector can be mounted with high positional accuracy, a detection timing calibration process is required after mounting, or the scanning area needs to be expanded to an area unrelated to the image, so the time available for image output is short. As a result, there are problems such as difficulty in securing luminance.

  Therefore, the inventor devised the embodiment and each of the modified examples in order to detect the position of the beam with high accuracy and ensure the brightness of the image in order to improve the quality of the laser scanning HUD image. It came to.

  6... Two-dimensional deflecting means (part of the image forming unit) 7. Scanning mirror (part of the image forming unit) 8. Transmission screen (part of the image forming unit) 8 a. Extraction unit, 9 ... concave mirror (optical system), 10 ... windshield (transmission / reflection member), 13 ... PD (photodetector), 100 ... light source unit (part of image forming unit), 1000 ... image display device.

JP 2009-014791 A

Claims (13)

A transmissive screen,
An image forming unit that scans the surface of the transmission screen with light to form an image within a scanning range;
A photodetector for detecting scanning light that is light from the image forming unit,
The transmissive screen is provided with a light introducing portion that introduces the incident scanning light outside a region where the image is formed within the scanning range,
The light introduction part is one surface of a recess provided on the surface, and has a reflection surface that reflects the incident scanning light toward a side end surface of the transmission screen,
The optical detector is an image display device arranged to be able to receive the scanning light propagating through the transmission screen and emitted from the transmission screen. The image display apparatus according to claim 1 , wherein the reflection surface is an inclined surface inclined with respect to the surface. The image display apparatus according to claim 1 , wherein the reflection surface is a scattering surface inclined with respect to the surface. The image display device according to claim 3 , wherein the light introducing unit is provided at a position corresponding to at least the entire region in the sub-scanning direction of a region where the image is formed. The image display apparatus according to any one of claims 1-4, characterized in that the lens structure is provided on the side end surface.   The image display device according to claim 1, wherein the light introduction unit is provided on one side in a main scanning direction of a region where the image is formed.   The image display according to claim 6, wherein the light introducing portion is provided at a position corresponding to at least one of a scanning start position and a scanning end position in a sub-scanning direction of a region where the image is formed. apparatus. The transmission screen, an image display apparatus according to any one of claims 1 to 7, characterized in that it comprises a microlens array in a region where the image is formed. The image display apparatus according to any one of claims 1-8, characterized by further comprising an optical system for guiding the light forming the image from the transparent screen transmissive reflecting member. An image display device according to claim 9 ,
And an object device on which the image display device is mounted. In a transmissive screen that is scanned with light and forms an image within the scanning range,
A light introduction part for introducing incident light is provided outside the region where the image is formed within the scanning range ,
The transmission screen according to claim 1, wherein the light introduction part has a reflection surface that is one surface of a recess provided on a surface and reflects the incident light toward a side end surface . Screen,
An image forming unit that scans the surface of the screen with light to form an image within a scanning range;
A photodetector for detecting scanning light that is light from the image forming unit,
The screen
A light introducing portion that is provided outside the region where the image is formed within the scanning range and introduces the incident scanning light;
A light propagation structure for propagating the scanning light introduced from the light introduction part;
A light extraction part for extracting the scanning light propagated through the light propagation structure,
The light introducing portion is one surface of a recess provided on the surface, and has a reflecting surface that reflects the incident scanning light toward a side end surface of the screen,
The image detector is arranged such that the light detector can receive the scanning light extracted from the light extraction unit. In a screen that is scanned by light and an image is formed within the scanning range,
A light introducing portion that is provided outside a region in which the image is formed within the scanning range and introduces incident light;
A light propagation structure for propagating light introduced from the light introduction part;
And a light extraction portion for extracting light propagated through the optical propagation structure,
The light introducing part is one side of the recess provided in the surface, a screen, characterized in Rukoto that having a reflection surface for the incident light is reflected toward the side end surface.

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