JP6237124B2 - Two-dimensional image display device, optical scanning device for two-dimensional image display device, scanned surface element, and moving body - Google Patents

Description

  The present invention relates to a two-dimensional image display device, an optical scanning device for the two-dimensional image display device, a scanned surface element, and a moving body.

  The two-dimensional image display device of the present invention can be mounted as a “head-up display device” on various movable mobile bodies such as automobiles, trains, ships, helicopters and airplanes.

  2. Description of the Related Art A two-dimensional image display device that displays a two-dimensional image by scanning a light beam has been proposed as a head-up display device or the like and is being put into practical use (Patent Documents 1 and 2).

In such a two-dimensional image display device, a light beam whose intensity is modulated by an image signal is deflected two-dimensionally by a two-dimensional deflection means.
Then, the scanned surface element is scanned two-dimensionally with the deflected light beam, and a two-dimensional image is formed on the scanned surface element.
The formed two-dimensional image is formed as an enlarged virtual image by a virtual image imaging optical system.

  Then, the imaging light flux is reflected to the observation unit side by the reflecting surface element provided in front of the imaging position of the enlarged virtual image and observed.

  As a light beam used for two-dimensional image formation, as described in Patent Documents 1 and 2, a laser beam having high light energy density and high directivity is suitable.

However, since the laser beam is coherent, “coherent noise” such as speckle tends to appear in the observed image.
Such noise is hereinafter referred to as “coherent noise”. Typical coherent noise is “interference fringes”.

  “Coherent noise” impairs the image quality of an observed image and deteriorates its visibility.

Patent Document 1 discloses the following method as a method for removing coherent noise.
That is, micro lenses (convex cylindrical lenses) are arrayed on the surface to be scanned, and the beam diameter of the coherent light beam for optical scanning is made smaller than the micro lens array pitch.

  Then, the light source is caused to emit light in synchronization with the scanning of the light beam so that the light beam does not irradiate across the boundary portion of the microlens so that the light beam is incident only on the microlens.

  Alternatively, “a light shielding layer is formed at the boundary” so that the light beam does not irradiate the boundary of the microlens.

These methods are effective for removing coherent noise. However, in synchronization with the scanning of the light beam, the light source is pulsed and the light beam is incident only on the microlens. The configuration of is complicated.

  Further, in the method of forming the light shielding layer at the boundary portion, the light beam can be continuously scanned, but the luminance (brightness) of the enlarged virtual image to be displayed is lowered by the light shielding by the light shielding portion.

The present invention has been made in view of the above-described circumstances.
That is, an object of the present invention is to effectively reduce the visibility of coherent noise while maintaining the brightness of an enlarged virtual image displayed by two-dimensional scanning of a coherent light beam.

In the optical scanning device for a two-dimensional image display device according to the present invention, a coherent pixel display beam whose intensity is modulated by an image signal is two-dimensionally deflected by a two-dimensional deflecting means, and the deflected pixel display beam is used. , by scanning the scanning surface element two-dimensionally, in the optical scanning device for two-dimensional image display device for forming a two-dimensional image on the scanned surface element, the surface to be scanned element, the pixel display beam It has a micro convex lens structure in which hexagonal micro convex lenses to be diffused are closely arranged, and the micro convex lenses are hexagonal and arranged in a honeycomb type array to form the micro convex lens structure. The radius of curvature r of the boundary portion of the hexagonal fine convex lens is smaller than the wavelength λ of coherent light constituting the pixel display beam .

  In the optical scanning device for a two-dimensional image display device according to the present invention, it is not necessary to use a light-shielding region at the boundary portion of the fine convex lens, so that the brightness of the displayed two-dimensional image can be satisfactorily maintained.

  Since the micro-convex lenses are arranged in a honeycomb shape, the direction in which the coherent noise is generated is dispersed in three directions, so the contrast of the coherent noise is lowered and is not easily recognized as coherent noise.

  In addition, pixels smaller than the actual lens diameter can be effectively expressed, and the number of effective pixels can be improved.

In the honeycomb-type sequence of micro convex lenses, the aspect ratio: If SY / SX size from 1 Kusure, the degree of X-direction of the diffusion can be made larger than the degree of Y-direction of the diffusion.

It is a figure for demonstrating one Embodiment of a two-dimensional image display apparatus. It is a figure for demonstrating the spreading | diffusion and interference noise generation by a micro convex lens. It is a figure for demonstrating the removal of a coherent noise. It is a figure which shows three examples of the arrangement | sequence form example of a micro convex lens. It is a figure which shows the 5 other examples of the arrangement | sequence form of a micro convex lens. It is a figure for demonstrating an anamorphic micro convex lens. It is a figure explaining the example of a to-be-scanned surface element. It is a figure which shows the other example of the arrangement | sequence form of a micro convex lens.

Hereinafter, embodiments will be described.
FIG. 1 is a diagram for explaining one embodiment of a two-dimensional image display device.

  A two-dimensional image display device described with reference to FIG. 1 is a head-up display device that displays a two-dimensional color image, and FIG. 1A schematically illustrates “the entire device”.

  In FIG. 1A, 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.1 (b), the semiconductor laser shown by code | symbol RS, GS, BS radiates | emits the R, G, B laser beam, respectively.

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

  The laser beam diameter of each color, whose divergence is suppressed by the coupling lenses RCP, GCP, and BCP, is regulated by the aperture RAP, GAP, and BAP.

Each color laser beam whose beam diameter is regulated is incident on 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 by an image signal of a “two-dimensional color image” to be displayed.

  That is, the emission intensity of the semiconductor lasers RS, GS, and BS is modulated by image signals of R, G, and B color components by a driving unit (not shown).

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 this embodiment, the two-dimensional deflection unit 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 means 6 is specifically a MEMS (Micro Electro Mechanical Systems) manufactured as a micro oscillating mirror element by a semiconductor process or the like.

  The two-dimensional deflecting means is not limited to this example, but may be of another configuration, for example, a combination of two micro mirrors that swing around one axis so that the swing directions are orthogonal to each other.

  The pixel display beam LC deflected two-dimensionally as described above enters the concave mirror 7 and is reflected toward the scanned surface element 8.

The optical action of the concave mirror 7 is to reflect the incident pixel display beam LC which is deflected two-dimensionally, and to align the direction of the reflected pixel display beam LC in a certain direction.
Accordingly, the pixel display beam LC reflected by the concave mirror 7 is incident on the scanned surface element 8 while being translated in two dimensions along with the deflection by the two-dimensional deflection means 6.
In this way, the scanned surface element 8 is two-dimensionally scanned by the pixel display beam LC, and a “color two-dimensional image” is formed on the scanned surface element 8.

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

Therefore, the “color two-dimensional image” is formed as “a set of pixels displayed at each moment” by two-dimensional scanning with the pixel display beam LC.
The light constituting the “color two-dimensional image” formed on the scanned surface element 8 as described above enters the concave mirror 9 and is reflected.

  Although not shown in FIG. 1, the scanned surface element 8 has a “fine convex lens structure” to be described later. The concave mirror 9 constitutes a virtual image imaging optical system.

The “virtual image imaging optical system” forms an enlarged virtual image 12 of the “color two-dimensional image”.
A reflective surface element 10 is provided on the front side of the imaging position of the magnified virtual image 12, and the light beam that forms the magnified virtual image 12 is reflected toward the viewer 11 (the viewer's eyes are shown in the figure). To do.

  The observer 11 can visually recognize the magnified virtual image 12 by the reflected light.

  As shown in FIG. 1 (a), the vertical direction in the figure is the “Y direction”, and the direction orthogonal to the drawing is the “X direction”.

  In the case shown in FIG. 1A, the Y direction is usually the vertical direction for the observer 11, and this direction is referred to as the “vertical direction”.

The X direction is usually the left-right direction for the observer 11, and this direction is referred to as the “lateral direction”.
Of course, the vertical and horizontal directions in the “vertical direction and horizontal direction” mentioned here are for convenience of explanation.

As described above, the scanned surface element 8 has a “fine convex lens structure”.
As will be described later, the micro-convex lens structure is “the micro-convex lenses are closely arranged at a pitch close to the pixel pitch”.

  The shape of the fine convex lens and the fine convex lens structure will be described later.

Each fine convex lens has a “function of diffusing a pixel display beam LC”.
The diffusion function will be briefly described below.

  In FIG. 1C, reference symbols L <b> 1 to L <b> 4 indicate four pixel display beams incident on the scanned surface element 8.

  These four pixel display beams L1 to L4 are assumed to be pixel display beams incident on the four corners of the two-dimensional image formed on the scanned surface element 8.

  These four pixel display beams L1 to L4 are converted into beams L11 to L14 after passing through the scanned surface element 8.

  If a light beam having a quadrilateral cross section surrounded by the pixel display beams L1 to L4 is incident on the scanned surface element 8, this light beam becomes "a divergent light beam surrounded by the beams L11 to L14".

  Actually, the pixel display beam is incident on a specific portion of the scanned surface element 8 at a certain moment, and is converted into a “divergent light beam” by the fine convex lens.

  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 reflecting surface element 10 irradiates a wide area near the eyes of the observer 11”.

  When there is no diffusion function, the light beam reflected by the reflecting surface element 10 irradiates only “a narrow area near the eyes of the observer 11”.

  For this reason, when the observer 11 moves his / her head and the position of the eyes deviates from the “narrow area”, the observer 11 cannot visually recognize the magnified virtual image 12.

  As described above, by diffusing the pixel display beam LC, the light flux reflected by the reflective surface element 10 irradiates a “wide area near the eyes of the observer 11”.

  Therefore, even if the observer “moves his head a little”, the magnified virtual image 12 can be reliably recognized.

  As described above, in the embodiment described, the pixel display beam LC incident on the scanned surface element 8 is a parallel beam, but after passing through the scanned surface element 8, it becomes a divergent beam.

  The to-be-scanned surface element 8 in the present invention has a “fine convex lens structure” in which fine convex lenses that diffuse the pixel display beam LC are closely arranged at a pitch close to the pixel pitch.

  The fine convex lens is larger than “the beam diameter of the pixel display beam LC”.

  The reason why the fine convex lens is made larger than “the beam diameter of the pixel display beam LC” is to reduce the coherent noise, and this will be described below with reference to FIGS.

In FIG. 2A, reference numeral 802 denotes a scanned surface element.
The scanned surface element 802 has a fine convex lens structure in which fine 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 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. 2A, 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. 2A, the entire pixel display beam 803 is incident on one fine 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. 2A, 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. 2B, 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.

  FIG. 3A shows a state in which the pixel display beam 824 is incident across the two fine convex lenses 822 and 823 of the scanned surface element 821.

The beam diameter of the pixel display beam 824 is equal to the size of the fine convex lens 822 and the like.
In this case, the beam portion incident on the fine convex lens 822 becomes a divergent light beam 826, and the beam portion incident on the fine convex lens 823 is diffused as a divergent light beam 827.

  Since divergent light beams 826 and 827 are diffused away from each other, they do not overlap each other, and therefore no coherent noise is generated in this state.

  That is, coherent noise due to the light beam diffused by the fine convex lens is not generated if the beam diameter of the pixel display beam 824 is made smaller than the size of the fine convex lens 822.

  Specific numerical examples of the diameter of the fine convex lens and the beam diameter of the pixel display beam incident on the scanned surface element will be exemplified.

  It is easy to set the beam diameter of the pixel display beam to, for example, about 150 μm.

  In this case, the size of the fine convex lens constituting the fine convex lens structure may be set to 150 μm or more, for example, 160 μm or 200 μm.

  In the scanned surface element 821 shown in FIG. 3A, the fine convex lenses 822, 823,... Are arranged without a gap.

Therefore, the “boundary width (hereinafter also referred to as“ boundary width ”)” of the adjacent fine convex lens surfaces is 0.
Therefore, the divergent light beams generated from the pixel display beam 824 that enters the fine convex lenses 822 and 823 as shown in the figure are only the divergent light beams 826 and 827.

  However, in the actually formed fine convex lens structure, “the boundary width between adjacent fine convex lenses is not zero”.

  That is, in the actually formed fine convex lens structure as in the scanned surface element 831 shown in FIG. 3B, the boundary portion 835 of the fine convex lenses 833 and 834 is not “width: 0”.

  The boundary portion 835 of the micro convex lenses 833 and 834 has a curved surface that is smoothly continuous microscopically, and a curved surface is formed at the boundary portion 835.

  The curved surface formed in the boundary portion 835 in this way acts as a “micro lens surface” with respect to the incident light portion when the pixel display beam is incident on this portion.

  Accordingly, the pixel display beam 832 incident across the fine convex lenses 833 and 834 generates a divergent light beam 838 together with the divergent light beams 836 and 837.

  The divergent light beam 838 is generated by the lens action of the curved surface of the boundary portion 835 and overlaps and interferes with the divergent light beams 836 and 837 in the regions 839 and 840 to generate coherent noise.

  FIG. 3C is a diagram for explaining “reduction or prevention of coherent noise” in the fine convex lens structure.

  In the micro-convex lens structure, the curved surface shape of the boundary portion 843 where the lens surfaces of the micro-convex lenses 841 and 842 are gently connected itself forms a “micro lens surface”.

  The curvature radius of the curved surface shape of the boundary portion 843 is “r” as shown in the figure.

  Here, for simplicity of explanation, the pixel display beam incident on the fine convex lens structure is referred to as a “monochromatic laser beam having a wavelength of λ”.

  When the curvature radius r of the boundary portion 843 is larger than the wavelength λ of the pixel display beam (r> λ), the curved surface having the curvature radius r has a lens effect on the incident pixel display beam.

  Therefore, in this case, the beam component passing through the boundary portion 843 is diverged and overlaps and interferes with the light beam diffused by the fine convex lenses 841 and 842 to generate coherent noise.

On the other hand, when the radius of curvature r of the boundary portion 843 is smaller than the wavelength λ of the pixel display beam, the boundary portion 843 has a “sub-wavelength structure” with respect to the pixel display beam.
As is well known, the sub-wavelength structure does not cause a lens action for “light having a wavelength larger than that of the sub-wavelength structure”.
Therefore, the boundary portion 843 having a radius of curvature “r” smaller than the wavelength “λ” of the pixel display beam does not act as a “lens”, and transmits the pixel display beam in a straight line.

  That is, in this case, the boundary portion 843 does not diverge the pixel display beam.

  For this reason, the beam portion transmitted straight through the boundary portion 843 and the divergent light beam diffused by the fine convex lenses 841 and 842 do not overlap with each other, and no coherent noise is generated due to interference.

That is, the size relationship between the beam diameter of the pixel display beam: d, the wavelength: λ, the size of the fine convex lens: D, and the radius of curvature of the surface forming the boundary portion: r is preferably determined as follows.
D> d, λ> r.

When the two-dimensional enlarged virtual image to be displayed is a monochrome image, a pixel display beam is formed by monochromatic coherent light having a wavelength: λ.
Therefore, in this case, coherent noise can be suppressed by setting D, d, r, and λ so as to satisfy the magnitude relationship.

  When displaying a two-dimensional color image (enlarged virtual image) as in the embodiment being described, the pixel display beam LC is a combination of R, G, and B beams.

  Assuming that the wavelengths of these three beams are λR (= 640 nm), λG (= 510 nm), and λB (= 445 nm), the magnitude relationship between them is “λR> λG> λB”.

  Therefore, from the viewpoint of preventing coherent noise, the radius of curvature “r” of the “surface forming the boundary” may be smaller than the shortest wavelength: λB, for example, 400 nm.

  However, if a radius of curvature: r (for example, 600 nm) smaller than the longest wavelength: λR is set, coherent noise due to the R component of the image display beam can be prevented.

  That is, coherent noise can be effectively reduced.

If “r (for example, 500 nm) <λG”, coherent noise due to the R component and G component light of the image display beam can be prevented.
When the pixel display beam LC is “combined beam of three colors R, G and B”,
Coherent noise is generated independently for these three color components.
The “total” of coherent noises of these independent three-color R, G, and B beams is visually recognized coherent noise.
Therefore, if no interference noise is detected even in one of the three colors of interference noise, the visually recognized interference noise is greatly improved, contributing to an improvement in the image quality of the observation image.
Therefore, the effect of preventing coherent noise is effective only with “the longest wavelength R component” of the three colors, and then the “reduction effect” is improved in the order of the G component and the B component.
Therefore, if a radius of curvature: r (for example, 600 nm) smaller than the longest wavelength: λR is set, a certain effect can be achieved in reducing coherent noise.
The visibility of the coherent noise is generally higher in the order of R≈G> B, although the noise intensity varies depending on the wavelength, beam diameter, multi / single mode, and the like.
That is, the light of wavelength λB has low visibility of human eyes, and coherent noise is not noticeable.
Therefore, if the radius of curvature: r (for example, 500 nm) smaller than the wavelength: λG is set, the coherent noise due to the light with relatively high visibility: λR and λG can be reduced.
Even if coherent noise is generated by light having a wavelength of low visibility: λB, it is not so noticeable.
Of course, if the curvature radius: r (for example, 400 nm) smaller than the wavelength: λB is set, the coherent noise can be further effectively reduced as described above.

  As described above, the size of the fine convex lens constituting the fine convex lens structure is on the order of 100 μm, and this can be realized as a normal “micro lens”.

  Further, a micro convex lens structure in which micro convex lenses are arranged can be realized as a “micro lens array”.

  Therefore, hereinafter, the fine convex lens is also referred to as “micro lens”, and the fine convex lens structure is also referred to as “micro lens array”.

Generally, a microlens array is produced by producing a “mold having a transfer surface of a lens surface array” and transferring the mold surface to a resin material using this mold.
As a method for forming a transfer surface in a mold, a method of forming by using cutting or photolithography is known.

  The transfer surface can be transferred to the resin material by, for example, “injection molding”.

Reducing the radius of curvature at the boundary between adjacent microlenses can be achieved by reducing the boundary width.
A small boundary width can be realized by “sharpening” the boundary formed by the adjacent microlens surfaces.

  Various methods are conventionally known as "a method for reducing the size of the boundary width between adjacent microlenses to a wavelength order" in a mold for a microlens array.

  For example, Patent Document 3 discloses a method in which the radius of curvature of each microlens is increased by anisotropic etching and ion processing, and the non-lens portion at the boundary is eliminated.

  Patent Document 4 discloses a method of removing a flat surface between adjacent microlenses by using isotropic dry etching.

  For example, by using these known methods, it is possible to produce a microlens array in which the radius of curvature of the surface forming the boundary between adjacent microlenses is sufficiently small.

  The two-dimensional image display device (head-up display device) shown in FIG. 1 has been described above.

The concave mirror 7 shown in FIG. 1 has a “function of reflecting the pixel display beam LC incident after being two-dimensionally deflected and aligning the direction of the reflected pixel display beam LC in a certain direction”.
That is, the concave mirror 7 functions as a “deflection range regulating means for regulating the scanning range of the scanned surface element by adjusting the deflection range of the two-dimensionally deflected pixel display beam”.

  Such a deflection range restricting means can be omitted when the deflection angle of the pixel display beam deflected two-dimensionally by the two-dimensional deflecting means 6 is not so large.

  Next, an example of the arrangement form of the micro convex lenses (micro lenses) in the micro convex lens structure (micro lens array) will be described.

  The “effective conditions for reducing the coherent noise” for the microlens array and the microlens are as described above.

  That is, “fine convex lenses larger than the beam diameter of the pixel display beam are closely arranged at a pitch close to the pixel pitch to form a fine convex lens structure”.

If this condition is satisfied, the arrangement of the microlenses may be appropriate. Three specific examples are shown in FIG.
4A is a microlens array 87 in which square-shaped microlenses 8711, 8712,... Are arranged in a square matrix.

  Such an array is called a “square matrix type array”.

  The number of pixels of the two-dimensional image (enlarged virtual image) displayed in the head-up display device is determined by the arrangement period of the microlenses in the microlens array.

  In the case of the square matrix type array in FIG. 4A, the distance between the centers of the microlenses 8711 and 8712 adjacent in the X direction is X1.

  In the drawing, the distance between the centers of the microlenses 8711 and 8721 adjacent in the Y direction is Y1. These X1 and Y1 can be regarded as “effective size of one pixel”.

  The “effective size of one pixel” is hereinafter also referred to as “effective pitch of one pixel” or “effective pixel pitch”.

  4B is a microlens array 88 in which regular hexagonal microlenses 8811, 8821,... Are densely arranged.

  In the arrangement of the microlenses in this case, the arranged microlenses 8811 and the like do not have sides parallel to the X direction.

  That is, since the upper and lower sides of the microlenses arranged in the X direction are “zigzag”, such an arrangement is called “zigzag type arrangement”.

  The microlens array 89 shown in FIG. 4 (c) is an example in which regular hexagonal microlenses 8911, 8921,... Are densely arranged.

  In the arrangement of the microlenses in this case, the arranged microlenses 8911 and the like have sides parallel to the X direction. This arrangement is called an “armchair arrangement”.

  That is, in the arrangement of the microlenses 8911 and the like, the upper side in the Y direction in the hexagonal shape of each arranged microlens is “parallel to the X direction”.

  In the case of such an arrangement, for example, attention is paid to the “upper side in the Y direction” in the arrangement part of the microlenses 8912, 8913, and 8914.

  Then, the “upper side in the Y direction” of the microlens 8913 can be viewed as the “seat part” of the armchair, and the “upper side in the Y direction” of the microlenses 8912 and 8914 can be viewed as the “arm rest part”.

  Therefore, such an arrangement form is called an “armchair type arrangement”.

  The zigzag array and the armchair array are collectively referred to as a “honeycomb array”.

The armchair array shown in FIG. 4C is an array obtained by rotating the zigzag array shown in FIG. 4B by 90 degrees.
In the zigzag array, X2 shown in FIG. 4B can be regarded as “an effective pixel pitch in the X direction” and Y2 as an “effective pixel pitch in the Y direction”.

  In the armchair type arrangement, X3 shown in the figure can be regarded as "effective pixel pitch in the X direction", and Y3 can be regarded as "effective pixel pitch in the Y direction".

  In FIG. 4B, the effective pixel pitch Y2 is the distance between the center of the microlens 8821 and the “midpoint of the right side” of the microlens 8811.

  In FIG. 4C, the effective pixel pitch: X3 is the distance between the midpoint of the sides of the two microlenses that are in contact with the right side of the microlens 8911 and the center of the microlens 8911.

  In the zigzag array, since the effective pixel pitch X2 in the X direction is small, the resolution in the X direction in image display can be improved.

  In the armchair type arrangement, the resolution in the Y direction can be improved.

  As described above, by arranging the micro lenses in the honeycomb type, pixels smaller than the actual lens diameter can be effectively expressed, and the number of effective pixels can be improved.

  As described above, in the fine convex lens structure (microlens array) of the surface element to be scanned, the boundary between adjacent microlenses has a radius of curvature: r.

  The radius of curvature r is smaller than the wavelength R of the R component of the pixel display beam, for example.

  Therefore, as described above, “coherent noise due to interference of R component coherent light” is prevented.

  However, if the radius of curvature r is larger than the wavelength of the G component light: λG or the wavelength of the B component light: λB of the pixel display beam, these lights are diffused at the boundary and interfere with each other.

  Therefore, coherent noise due to this interference is generated.

  In this case, in the case of the “square matrix array” in FIG. 4A, divergence (diffusion) at the boundary portion occurs in two directions Xa and Ya in the figure, and each causes coherent noise.

  On the other hand, in the arrangement of FIG. 4B, divergence at the boundary portion occurs in three directions 8A, 8B, and 8C. Further, in the case of FIG. 4C, diffusion is performed in three directions 9A, 9B, and 9C.

  That is, the divergence at the boundary portion occurs in two directions in the square matrix arrangement and in three directions in the honeycomb arrangement.

  Therefore, the coherent noise is generated by being distributed in two directions in the square matrix arrangement and in three directions in the honeycomb arrangement.

  That is, the generated coherent noise is “dispersed in two directions” in the square matrix type array, but is “dispersed in three directions” in the honeycomb type array.

  Since the maximum intensity of the coherent light that causes the coherent noise is constant, the greater the number of dispersed light, the weaker the contrast of the generated coherent noise and the less visible it becomes.

  Therefore, in the case where the generation of “coherent noise due to a component having a wavelength smaller than r at the radius of curvature of the boundary portion” is allowed, the arrangement of the microlenses is preferably a “honeycomb arrangement”.

  When the curvature radius r of the boundary portion is “when wavelength is larger than λR”, not only coherent noise due to coherent light of B component and G component but also coherent noise due to coherent light of R component is generated.

  Since the boundary width between the lens surfaces of the adjacent fine convex lenses is very small, the optical energy of the coherent light incident on the boundary width portion is small.

  Therefore, the light energy that generates coherent noise is not large, and even if coherent noise is generated, the contrast is weakened by being dispersed in three directions as described above.

  Therefore, even if coherent noise is generated by coherent light of each component of R, G, and B, the visibility is effectively reduced and becomes inconspicuous.

  As described with reference to FIG. 1A, the virtual image imaging optical system that forms the two-dimensional enlarged virtual image 12 is configured by the concave mirror 9.

  That is, the magnified virtual image 12 is a set of pixel images formed by the concave mirror 9.

  If a microlens that is a microconvex lens has an “anamorphic function”, the diffusion function of the microconvex lens can be made different in two directions orthogonal to each other.

Referring to FIG. 6, reference numeral 80 in FIG. 6 shows individual microlenses (fine convex lenses) densely formed on the scanned surface element 8 as explanatory diagrams.
In the example of FIG. 6, the micro convex lenses 80 are arranged in an “armchair arrangement” having sides parallel to the X direction.
The microconvex lens 80 has different curvature radii in the X direction and the Y direction, and the curvature radius in the X direction: Rx is smaller than the curvature radius in the Y direction: Ry.
Therefore, the power in the X direction of the fine convex lens 80 is larger than the power in the Y direction.
Further, since the curvature is given to both the X direction and the Y direction of the lens surface, the fine convex lens can be formed into a hexagonal shape, and as described above, the “visibility of coherent noise” is weakened and can be made inconspicuous.
FIG. 6 shows a case where a pixel display beam LC is incident on one fine convex lens 80. In FIG. 6, the width in the Y direction of each fine convex lens 80 is longer than the width in the X direction.

The beam diameter of the pixel display beam LC is “ellipse shape long in the Y direction”, and the light beam diameter in the Y direction is made smaller than the diameter of the fine convex lens 80 in the Y direction.
In this way, the pixel display beam LC can be “incident without straddling the lens boundary”, and the cross-sectional shape of the emitted divergent light beam can be an ellipse that is long in the X direction.

  Regardless of the length in the Y direction and the length in the X direction of the fine convex lens, if the curvature in the X direction is larger than the curvature in the Y direction, the beam cross section FX of the divergent beam emitted from each fine convex lens is expressed in the X direction. The Y direction can be longer than the Y direction.

  That is, the viewing angle of the magnified virtual image 12 viewed from the observer 11 can be “large in the X direction”.

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

In this case, the reflecting surface element 10 is an automobile windshield.
In this case, for example, a “navigation image” can be displayed as the enlarged virtual image 12 in front of the windshield, and the driver who is the observer 11 can observe this image while being in the driver's seat.

  In such a case, the magnified virtual image to be displayed is a “horizontal image as viewed from the driver”, that is, the two-dimensional image formed on the microlens array and the magnified virtual image have a large angle of view in the X direction. An “image” is generally preferred.

Further, a “large viewing angle compared to the vertical direction” is required in the horizontal direction so that the driver who is an observer can recognize the display even when viewing the display image from the diagonal direction.
For this reason, a larger diffusion angle (isotropic diffusion) is required in the longitudinal direction (X direction) of the enlarged virtual image than in the short direction (Y direction).

  Therefore, the micro-convex lens of the surface element to be scanned is an anamorphic lens having a curvature larger in the longitudinal direction than the short direction of the two-dimensional image or magnified virtual image formed on the micro lens array, and diffuses the pixel display beam. It is preferable to set the diffusion angle to be "wider the horizontal direction of the two-dimensional image 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 device used for in-vehicle use such as an automobile, the driver rarely observes 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 two-dimensional 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.

  Each micro convex lens (micro lens) in the micro convex lens structure (micro lens array) shown in FIG. 4 was a square or a regular hexagon.

  The shape of the micro-convex lens does not have to be a regular polygon in this way, and may be a shape obtained by extending the micro lens shape shown in FIG. 4 in one direction.

  In this case, a square shape is a “rectangular shape”, and a regular hexagonal shape is an elongated deformed hexagon.

The effective pixel pitch of the fine convex lens structure was X1 to X3 in the X direction and Y1 to Y3 in the Y direction in the arrangement of FIGS.
When the effective pixel pitch in the X direction thus determined is generally “SX” and the effective pixel pitch in the Y direction is generally “SY”, the ratio between the two: SY / SX is referred to as “aspect ratio”.

  In the case of FIG. 4A, the aspect ratio is “Y1 / X1”, and X1 = Y1, so the aspect ratio is 1.

  In the case of FIG. 4B, the aspect ratio is “Y2 / X2”, and Y2> X1, so the aspect ratio is greater than 1.

  In the case of FIG. 4C, the aspect ratio is “Y3 / X3”, and Y3 <X3. Therefore, the aspect ratio is smaller than 1.

  In the fine convex lens structures of the microlens arrays 91 to 95 shown in FIGS. 5A to 5E, the effective pixel pitch is determined as follows in the same manner as in FIG.

  That is, the effective pixel pitches in the X direction and the Y direction are “X11, Y11”, “X12, Y12”, and “X13, Y13” in FIG.

  The micro-convex lens structure of FIG. 5A is an array of rectangular micro-convex lenses 9111, 9112,... 9121,.

  The micro-convex lens structures of the microlens arrays 92 to 95 shown in FIGS. 5B to 5E are honeycomb-type arrays.

  In the honeycomb arrangement shown in FIGS. 5B, 5D, and 5E, the aspect ratios “Y12 / X12” and “Y13 / X13” are both greater than 1.

  In all the five examples of the fine convex lens structure shown in FIG. 5, the “fine convex lens” has a length in the Y direction larger than a length in the X direction.

  Thus, in the case of “a fine convex lens having a shape in which the length in the Y direction is larger than the length in the X direction”, it is easy to make the curvature in the X direction larger than the curvature in the Y direction as the shape of the fine convex lens.

  Therefore, it is easy to realize the “anamorphic optical function in which the power in the X direction is larger than the power in the Y direction”.

  For example, in the case of the example shown in FIG. 5A, specific examples include X11 = 150 μm, Y11 = 200 μm, and aspect ratio = 200/150 = 4/3> 1.

  Of course, in this case, the beam diameter of the pixel display beam is “less than 150 μm in the X direction and less than 200 μm in the Y direction”.

  The arrangement of the micro-convex lenses shown in FIGS. 5B to 5D is a honeycomb-type array, and each micro-convex lens has a “long shape in the Y direction”.

  The arrangement of FIG. 5B is “zigzag type”, and the arrangements of (c) to (e) are all “armchair type”.

  It is a matter of course that both the “zigzag-type vertically long honeycomb array” in FIG. 5B and the “armchair-type vertically long honeycomb array” in FIG. 5C can be used.

  However, the arrangement example of FIG. 5C has the following advantages over the arrangement example of FIG.

  That is, in the arrangement (c), the “difference in size in the X direction and the Y direction” in the micro-convex lens is small and the “difference in effective pixel size” in the vertical and horizontal directions is small in the arrangement (c).

List specific dimensions.
For example, in FIG. 5B, the lens diameter in the X direction of the fine convex lenses 9211 and 9212: R2x = 100 μm, and the lens diameter in the Y direction: R2y = 200 μm.

  At this time, the effective pixel pitch in the X direction (= X12) is 50 μm, and the effective pixel pitch in the Y direction (= Y12) is 150 μm.

  Similarly, in FIG. 5C, the lens diameter in the X direction: R3x = 100 μm and the lens diameter in the Y direction: R3y = 200 μm of the fine convex lenses 9311, 9312 and the like.

In addition, the length of the upper and lower sides of the hexagonal shape such as the fine convex lens 9311 is 50 μm.
At this time, the effective pixel pitch in the X direction (= X13) is 75 μm, and the effective pixel pitch in the Y direction (= Y13) = 100 μm.

  Accordingly, the “effective pixel pitch in the X and Y directions” is “a value closer to each other” in the arrangement (75 μm and 100 μm) in FIG. 5C than in the arrangement (50 μm and 100 μm) in (b).

In FIGS. 5C, 5D and 5E, the effective pixel pitch in the X direction is X13, and the effective pixel pitch in the Y direction is Y13.
This is because the pixel pitch in the X direction and the pixel pitch in the Y direction are defined in the same manner in the honeycomb array (armchair honeycomb array) shown in FIGS.
In FIG. 5D, the fine convex lenses 9411, 9421 and the like have short upper and lower sides parallel to the X direction and long oblique sides.
In FIG. 5E, the fine convex lenses 9511 and 9521 have long upper and lower sides parallel to the X direction and short hypotenuses.
As shown in these figures, the pixel pitch: X13 in the X direction and the pixel pitch: Y13 in the Y direction can be adjusted by deforming the hexagonal shape of the fine convex lens.

As in the case of FIG. 5C, in the arrangements shown in FIGS. 5D and 5E, the “fine convex lens structure is a vertically long structure”, so that “effective pixel pitch equalization in the X and Y directions”. Is possible.
The fine convex lens structures shown in FIGS. 5C to 5E are examples of the fine convex lens structure of the scanned surface element of the present invention.

That is, in the fine convex lens structure shown in FIGS. 5C to 5E, the fine convex lens has a hexagonal shape.
This is an armchair type arrangement in which the upper side of the fine convex lens in the Y direction is parallel to the X direction.

  The effective pixel pitch in the X and Y directions: SX, the aspect ratio of SY: SY / SX is greater than 1.

The “shape of the fine convex lens” as shown in FIGS. 5C to 5E can be arbitrarily selected for controlling the divergence angle of the divergent light beam, for example.
As described above, the shape of the vertically long hexagon of the fine convex lens may be any side length.

Therefore, the armchair-type vertically long honeycomb array can reduce the difference in effective pixel pitch between the X direction (horizontal direction) and the Y direction (vertical direction), in addition to the improvement in luminance and the number of effective pixels.
In the microlens array of FIGS. 5C to 5E described above, each microlens has a hexagonal shape, and the length in the Y direction is larger than the length in the X direction.
For this reason, it is easy to realize the “anamorphic optical function in which the power in the X direction is larger than the power in the Y direction”.
5C to 5E, the effective pixel pitch in the X and Y directions: SX, the aspect ratio of SY: SY / SX is larger than 1.
If the aspect ratio: SY / SX is 1, the resolution in the displayed two-dimensional image can be made equal in the X direction and the Y direction.
Each microlens can have a hexagonal shape, and the aspect ratio of the effective pixel pitch in the X and Y directions can be set to 1 while making the length in the Y direction larger than the length in the X direction.
The arrangement of the microlenses 9611 and the like in the microlens array 96 shown in FIG. 8 is an example in this case.
The arrangement of the microlenses 9611 and the like in the microlens array 96 is an “armchair-type vertically elongated honeycomb arrangement” similar to FIG.
The hexagonal shape of the microlens 9611 and the like is set so that the effective pixel pitch X14 in the X direction is completely equal to the effective pixel pitch Y14 in the Y direction.
Thus, the aspect ratio can be set to 1 in the armchair-type vertically long honeycomb arrangement.
In the case of a fine convex lens that is larger than the beam diameter of the pixel display beam or a fine convex lens that is as large as the beam diameter of the pixel display beam, an image projected as an enlarged virtual image if the aspect ratio of the effective pixel pitch is 1. The reproducibility by the enlarged virtual image is enhanced for the data.
The image data that is projected as an enlarged virtual image by matching the “pixel pitch on the microlens array” of the image data projected as an enlarged virtual image with the effective pixel pitch, or compared with other effective pixel pitches This is because the pixel pitch of the image data on the microlens array of data can be approached.
The armchair-type vertically elongated honeycomb structure has densely arranged hexagonal microlenses.
The hexagonal shape of each microlens is “a shape in which the interval between a pair of two opposite sides of a regular hexagonal shape is expanded in a direction orthogonal to these two sides”.
The two sides are “parallel to one direction of two-dimensional scanning”.
According to such an armchair-type vertically elongated honeycomb structure microlens array, the aspect ratio of the effective pixel pitch in the X and Y directions: SY / SX can be adjusted within a range of 1 or more.
Further, since the microlens array is vertically long, it is easy to realize an “anamorphic optical function in which the power in the X direction is larger than the power in the Y direction”.
In the above description, the vertical direction is described as “vertical direction” and the horizontal direction as “horizontal direction”, but this is for convenience of description.
Which direction is the vertical direction in the actual space depends on the mounting direction of the microlens array to the two-dimensional image display device and the mounting direction of the two-dimensional image display device to a moving body such as a vehicle.
The two-dimensional deflection means 6 performs reciprocal oscillation (oscillation of the second axis) a plurality of times while performing reciprocal oscillation (oscillation of the first axis) about one axis. However, in many cases, the X direction, which is the longitudinal direction of the enlarged virtual image, is set as the scanning direction of the image display beam LC with respect to the microlens array by the swing of the second axis.
Accordingly, the upper and lower sides of the “armchair-type” hexagonal microlens parallel to the X direction are substantially parallel to the scanning direction of the image display beam LC with respect to the microlens array, and the six “armchair-type arrangement” An interval between two sides of the rectangular image display beam closest to the scanning direction with respect to the microlens array, in other words, a side closest to the scanning direction of the image display beam with respect to the microlens array and an opposite side thereof The shape in which the distance between the two is extended in a direction perpendicular to these two sides is an “armchair-type vertically long honeycomb structure”.

  In the head-up display device shown in FIG. 1A, the pixel display beam LC is orthogonally incident on the fine convex lens structure of the scanned surface element 8.

  However, the incident form of the pixel display beam to the scanned surface element is not limited to such “orthogonal incidence”.

  For example, in order to make the head-up display device compact by devising the arrangement of the optical elements from the light source unit to the reflective surface element, an incident form as shown in FIG.

  That is, in the example of FIG. 7A, the pixel display beam LC is incident on the scan surface element 8 with an inclination.

  When the lens surface of the fine convex lens is an “aspherical surface”, the pixel display beam LC is incident with an inclination relative to the optical axis of the aspherical surface, and the aspherical function may not be utilized.

  In such a case, as in the scanned surface element 8a in FIG. 7B, the lens surface optical axis AX of the fine convex lens ML is inclined from the orthogonal direction with respect to the reference surface of the scanned surface element 8a. good.

  In this way, the lens surface optical axis AX can be made parallel to or close to the incident direction of the pixel display beam LC.

  The reference surface of the scanned surface element 8a is a surface on which the micro convex lenses ML are arrayed.

  By doing so, the optical system can be downsized and the light utilization efficiency can be improved, and the “direction of divergence of the pixel display beam by the fine convex lens” can be made uniform.

  The head-up display device described above can be mounted not only on the above-described automobile but also on various movable mobile bodies such as trains, ships, helicopters, and airplanes.

  In this case, the windshield in front of the driver's seat may be a reflecting surface element, and the user sees an “enlarged virtual image of a two-dimensional image” while driving.

  Of course, it goes without saying that the head-up display device can be implemented as, for example, a “two-dimensional image display device for watching movies”.

  The micro-convex lens having the micro-convex lens structure diffuses the pixel display beam as described above. However, it may be considered that only one of the X and Y directions is diffused.

  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.

100 light source
LC pixel display beam
6 Two-dimensional deflection means 7 Concave mirror
8 Scanned surface element
9 concave mirror
10 Reflective surface element
11 Observer
12 Enlarged virtual image

JP 2009-128659 A JP 2010-145745 A Japanese Patent No. 4200323 Japanese Patent No. 5010445

Claims (13)

A coherent pixel display beam whose intensity is modulated by an image signal is two-dimensionally deflected by a two-dimensional deflecting means, and the scanned surface element is two-dimensionally scanned by the deflected pixel display beam, In an optical scanning device for a two-dimensional image display device that forms a two-dimensional image on a surface to be scanned,
The scanned surface element has a fine convex lens structure in which hexagonal fine convex lenses for diffusing the pixel display beam are closely arranged,
The fine convex lens has a hexagonal shape and is arranged in a honeycomb type array to form the fine convex lens structure,
For a two-dimensional image display device, wherein the radius of curvature r of the boundary between adjacent hexagonal micro-convex lenses in the micro-convex lens structure is smaller than the wavelength of coherent light constituting the pixel display beam: λ . Optical scanning device. A coherent pixel display beam whose intensity is modulated by an image signal is two-dimensionally deflected by a two-dimensional deflecting means, and the scanned surface element is two-dimensionally scanned by the deflected pixel display beam, In an optical scanning device for a two-dimensional image display device that forms a two- dimensional image on a surface to be scanned ,
The scanned surface element has a fine convex lens structure in which fine convex lenses for diffusing the pixel display beam are closely arranged,
The fine convex lens has a hexagonal shape and is arranged in a honeycomb type array to form the fine convex lens structure,
The pixel display beam is a combination of coherent lights with different wavelengths emitted from two or more light sources into one beam,
A two-dimensional image characterized in that a radius of curvature: r of a boundary portion between adjacent fine convex lenses in the fine convex lens structure is smaller than a longest wavelength: λm among a plurality of coherent light wavelengths constituting a pixel display beam. An optical scanning device for a display device. A coherent pixel display beam whose intensity is modulated by an image signal is two-dimensionally deflected by a two-dimensional deflecting means, and the scanned surface element is two-dimensionally scanned by the deflected pixel display beam, In an optical scanning device for a two-dimensional image display device that forms a two- dimensional image on a surface to be scanned ,
The scanned surface element has a fine convex lens structure in which fine convex lenses for diffusing the pixel display beam are closely arranged at a pitch close to the pixel pitch,
The fine convex lens has a hexagonal shape and is arranged in a honeycomb type array to form the fine convex lens structure,
An optical scanning device for a two-dimensional image display device , wherein the lens surface of the fine convex lens has an aspherical shape, and the optical surface of the lens surface is inclined from the orthogonal direction with respect to the reference surface of the scanning surface element . The optical scanning device for a two-dimensional image display device according to any one of claims 1 to 3,
For a two-dimensional image display device, comprising: a deflection range regulating means for regulating a deflection range of a pixel display beam deflected two-dimensionally by a two-dimensional deflection means and regulating a scanning range of a scanning surface element Optical scanning device. The optical scanning device for a two-dimensional image display device according to any one of claims 1 to 4,
A two-dimensional image display characterized in that the fine convex lens formed on the scanned surface element is an anamorphic lens, and the diffusion angle for diffusing the pixel display beam is wider than the vertical direction in the horizontal direction of the two-dimensional image. Optical scanning device for apparatus. The optical scanning device for a two-dimensional image display device according to claim 5 ,
An optical scanning device for a two-dimensional image display device, characterized in that a cross-sectional shape of a divergent light beam emitted from a fine convex lens formed on a scanned surface element is longer in the horizontal direction of the two-dimensional image than in the vertical direction .   A scanned surface element used in the optical scanning device for a two-dimensional image display device according to any one of claims 1 to 6. A coherent pixel display beam whose intensity is modulated by an image signal is two-dimensionally deflected by a two-dimensional deflecting means, and the scanned surface element is two-dimensionally scanned by the deflected pixel display beam, A two-dimensional image is formed on the scanning surface element, the two-dimensional image is formed as a magnified virtual image by a virtual image imaging optical system, and an imaging light beam is generated by a reflecting surface element provided in front of the imaging position of the magnified virtual image. A two-dimensional image display device that reflects to the observation unit side,
A two-dimensional image display device using the optical scanning device for forming a two-dimensional image according to any one of claims 1 to 6. The two-dimensional image display device according to claim 8,
The front windshield in front of the driver's seat of the movable body that can be driven is used as a reflective surface element, and is mounted on the movable body, and an enlarged virtual image formed in front of the windshield can be observed from the driver's seat. A two-dimensional image display device. In a two-dimensional image display device having a microlens array and a scanning unit for two-dimensionally scanning the microlens array with an image display beam,
In the microlens array, hexagonal microlenses are densely arranged,
The hexagonal shape is a shape in which the interval between a pair of opposing two sides of a regular hexagonal shape is expanded in a direction perpendicular to these two sides,
The two sides, the one of the sides of the hexagon shape, the image display beam wherein the two-dimensional scanning of the microlens array direction most parallel to the near Kunar so set to have been of claim 7, wherein the A two-dimensional image display device characterized by being a scanned surface element . The two-dimensional image display device according to claim 10,
A two-dimensional image display device, wherein an aspect ratio of an effective pixel pitch in a microlens array is 1. The two-dimensional image display device according to claim 10 or 11,
Each lens constituting the microlens array has a lens diameter equal to or larger than the beam diameter of the image display beam.   The mobile body by which the two-dimensional image display apparatus of any one of Claims 10-12 is arrange | positioned so that a user may see the expansion virtual image of a two-dimensional image during a driving | operation.

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