JP2011075651A - Optical unit and projection type image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decrease speckle noise related to a projection type image display device using a coherent light source, and to decrease light loss caused by an increase of a divergence angle of light. <P>SOLUTION: An optical unit (for example, a speckle noise decreasing element 20R) includes a pair of lens arrays (incident-side microlens array and exit-side microlens array), and a vibration applying means that vibrates the pair of lens arrays. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique for reducing speckle noise in a projection display apparatus using a coherent light source.

  In recent years, users of projection type video display apparatuses are increasing in demand for projection type video display apparatuses with a large amount of projection light due to the expansion of applications. A conventional light source such as a mercury lamp cannot obtain a sufficient amount of light.

  Therefore, it has been considered that a plurality of laser light sources emit light, and the emitted light is collected by an optical fiber or the like and bundled to be used as a light source for a projection display apparatus.

  However, in a projection display apparatus using a laser light source, there is a problem in that speckle noise occurs due to coherency (coherence) peculiar to laser light and image quality deteriorates. Speckle noise is observed as an irregular granular intensity distribution when coherent light such as laser light is scattered at each point on a rough surface such as a screen and interferes with an irregular phase relationship caused by the surface roughness. It is a phenomenon.

  In order to solve these problems, the projection type display device reduces the speckle noise by installing a light diffusing element in the diverging light path of the projection type image display device and vibrating the light diffusing element in a direction parallel to the traveling direction of the light. An invention of a video display device is disclosed in Patent Document 1.

JP 2008-134269 A

  However, if a light diffusing element is installed in the divergent light path of the projection display apparatus and the light diffusing element vibrates in a direction parallel to the traveling direction of light, the light divergence angle increases. Light with an angle component that cannot be captured is lost.

  Further, in order to prevent this light loss from occurring, a projection lens having a small F-number is required, but the degree of difficulty increases in designing to obtain sufficient imaging performance. The cost increases because it is required.

Accordingly, an object of the present invention is to reduce speckle noise associated with a projection display apparatus using a coherent light source such as a laser light source, and to reduce light loss due to an increase in the light divergence angle.

The present invention is for solving the above-described problem, and the optical unit according to the first aspect (for example, the speckle noise reduction element 20R) includes a pair of lens arrays (an incident side microlens array 310 and an emission side microlens). The gist is provided with a lens array 312) and vibration applying means for vibrating the pair of lens arrays.
Here, the vibration may be any motion that periodically changes within a predetermined range, and includes rotation, swinging, and the like in addition to linear motion. According to this aspect, speckle noise can be reduced, and an increase in the divergence angle of incident light can be suppressed.

In the first aspect, the pair of lens arrays includes a first lens array (incident side microlens array 310) having a focal length f, a second lens array having a focal length f ′, and (exit side microlens array). 312), and when a medium having an absolute refractive index n is interposed between the first lens array and the second lens array, the first lens array and the second lens array , (F + f ′) / n.
That is, if the first lens array and the second lens array have the same focal length f, the distance between the first lens array and the second lens array may be air. If so, it suffices to have an interval of f + f ′.
Further, the projection display apparatus (projection display apparatus 100) according to the second aspect includes a light source unit (light source unit 110) configured by a coherent light source and an optical axis of light emitted from the light source unit. An optical unit that vibrates in a substantially orthogonal direction (for example, speckle noise reduction element 20R), a light modulation element (for example, DMD500R) that modulates light emitted from the light source unit, and modulated by the light modulation element A projection unit that projects light (projection unit 150). The optical unit includes a pair of lens arrays (an incident side microlens array 310 and an emission side microlens array 312).
According to the 2nd aspect, the speckle noise concerning the projection type video display apparatus using a coherent light source can be reduced, and the light loss by increasing the divergence angle of light can be reduced. In the second aspect, when the divergence angle of the light incident on the optical unit is θ, the lens array (incident side microlens array 310) arranged at least on the incident side of the pair of lens arrays is tanθ < The lens diameter d and focal length f of each lens (incident side microlens 311) may be set so as to satisfy the condition of d / 4f.

It is possible to reduce speckle noise related to a projection display apparatus using a coherent light source, and to reduce light loss due to an increase in light divergence angle.

1 is a perspective view showing a projection display apparatus 100 according to a first embodiment. It is the figure which looked at the projection type video display apparatus 100 concerning a 1st embodiment from the side. It is the figure which looked at the projection type video display apparatus 100 concerning a 1st embodiment from the upper part. It is a figure which shows the light source unit 110 which concerns on 1st Embodiment. FIG. 3 is a diagram illustrating a color separation / synthesis unit 140 and a projection unit 150 according to the first embodiment. It is detail drawing of the speckle noise reduction element which concerns on 1st Embodiment. It is an optical path figure of the light which passes the speckle noise reduction element which concerns on 1st Embodiment. FIG. 6 is a diagram illustrating a color separation / synthesis unit 140 and a projection unit 150 according to a first modification. It is the figure which looked at the projection type video display apparatus 100 concerning a 2nd embodiment from the side.

[Summary of Embodiment] A projection display apparatus according to an embodiment has a light source unit configured by a coherent light source and specifications by vibrating, swinging, or rotating so as to be substantially orthogonal to the optical axis of the light source unit. A projection-type image display device comprising: a speckle noise reduction element that reduces light noise; a light modulation element that modulates light emitted from the coherent light source; and a projection unit that projects light modulated by the light modulation element. The speckle noise reduction element has a first lens array having a focal length f and a second lens array having a focal length f ′, and the interval between the media sandwiched between the lens arrays is absolute. When the refractive index is n, it is (f + f ′) / n.

  The speckle noise reduction element has a first lens array having a focal length f and a second lens array having a focal length f ′, and the distance between the media sandwiched between the lens arrays is an absolute refractive index n. (F + f ′) / n. With this configuration, the incident-side divergence angle of the light incident on the speckle noise reduction element can be made the same as the emission-side divergence angle of the emitted light. Accordingly, since the divergence angle of light before and after entering the speckle noise reduction element does not increase, an angle component that cannot be captured by the projection lens is hardly generated, and light loss of the projection display apparatus is reduced. Can do.

  Further, the position and phase of each light beam emitted from the speckle noise reduction element changes with time by vibrating, swinging, or rotating the speckle noise reduction element arranged in the illumination optical system. Thereby, since the angle and phase of each light ray incident on each point on the screen surface change with time, the speckle pattern is superimposed on time, and the speckle noise that is visually recognized is reduced.

  Therefore, in a projection display apparatus using a coherent light source, speckle noise can be reduced and light loss due to an increase in the light divergence angle can be reduced.

[First Embodiment]
(Configuration of projection display device)
Hereinafter, the configuration of the projection display apparatus according to the first embodiment will be described with reference to the drawings. FIG. 1 is a perspective view showing a projection display apparatus 100 according to the first embodiment. FIG. 2 is a side view of the projection display apparatus 100 according to the first embodiment.

  As shown in FIGS. 1 and 2, the projection display apparatus 100 has a housing 200 and projects an image on a projection plane 300. The projection display apparatus 100 is arranged along a first arrangement surface (wall surface 420 shown in FIG. 2) and a second arrangement surface (floor surface 410 shown in FIG. 2) substantially perpendicular to the first arrangement surface.

  Here, in the first embodiment, a case in which the projection display apparatus 100 projects image light onto a projection plane 300 provided on a wall surface is illustrated (wall surface projection). The arrangement of the casing 200 in such a case is referred to as a wall surface projection arrangement. In the first embodiment, the first arrangement surface substantially parallel to the projection surface 300 is the wall surface 420.

  In the first embodiment, a horizontal direction parallel to the projection plane 300 is referred to as a “width direction”. The normal direction of the projection plane 300 is referred to as “depth direction”. A direction orthogonal to both the width direction and the depth direction is referred to as a “height direction”.

  The housing 200 has a substantially rectangular parallelepiped shape. The size of the housing 200 in the depth direction and the size of the housing 200 in the height direction are smaller than the size of the housing 200 in the width direction. The size of the casing 200 in the depth direction is substantially equal to the projection distance from the reflection mirror (concave mirror 152 shown in FIG. 2) to the projection plane 300. In the width direction, the size of the casing 200 is substantially equal to the size of the projection plane 300. In the height direction, the size of the housing 200 is determined according to the position where the projection plane 300 is provided.

  Specifically, the housing 200 includes a projection surface side wall 210, a front surface side wall 220, a bottom plate 230, a top plate 240, a first side surface side wall 250, and a second side surface side wall 260. .

  The projection surface side wall 210 is a plate-like member that faces a first arrangement surface (in the first embodiment, a wall surface 420) substantially parallel to the projection surface 300. The front side wall 220 is a plate-like member provided on the opposite side of the projection plane side wall 210. The bottom plate 230 is a plate-like member that faces a second arrangement surface (in the first embodiment, the floor surface 410) that is substantially perpendicular to the first arrangement surface that is substantially parallel to the projection plane 300. The top plate 240 is a plate-like member provided on the opposite side of the bottom plate 230. The first side wall 250 and the second side wall 260 are plate-like members that form both ends of the housing 200 in the width direction.

  The housing 200 accommodates the light source unit 110, the power supply unit 120, the cooling unit 130, the color separation / combination unit 140, and the projection unit 150. The projection surface side sidewall 210 has a projection surface side recess 160A and a projection surface side recess 160B. The front side wall 220 has a front side convex portion 170. The top plate 240 has a top plate recess 180. The first side wall 250 has a cable terminal 190.

  The light source unit 110 is a unit composed of a plurality of coherent light sources (coherent light source 111 shown in FIG. 4). Each coherent light source is a light source such as an LD (Laser Diode). In the first embodiment, the light source unit 110 includes a red coherent light source that emits red component light R (red coherent light source 111R shown in FIG. 4) and a green coherent light source that emits green component light G (green coherent light shown in FIG. 4). Light source 111G) and a blue coherent light source (blue coherent light source 111B shown in FIG. 4) that emits blue component light B. Details of the light source unit 110 will be described later (see FIG. 4).

  The power supply unit 120 is a unit that supplies power to the projection display apparatus 100. For example, the power supply unit 120 supplies power to the light source unit 110 and the cooling unit 130.

  The cooling unit 130 is a unit that cools a plurality of coherent light sources provided in the light source unit 110. Specifically, the cooling unit 130 cools each coherent light source by cooling a cooling jacket (cooling jacket 131 shown in FIG. 4) on which each coherent light source is placed.

  The cooling unit 130 is configured to cool the power supply unit 120 and the light modulation element (DMD 500 described later) in addition to each coherent light source.

  The color separation / combination unit 140 combines the red component light R emitted from the red coherent light source, the green component light G emitted from the green coherent light source, and the blue component light B emitted from the blue coherent light source. The color separation / combination unit 140 separates the combined light including the red component light R, the green component light G, and the blue component light B, and modulates the red component light R, the green component light G, and the blue component light B. Further, the color separation / combination unit 140 recombines the red component light R, the green component light G, and the blue component light B, and emits image light to the projection unit 150. Details of the color separation / synthesis unit 140 will be described later (see FIG. 5).

  The projection unit 150 projects the light (image light) emitted from the color separation / synthesis unit 140 onto the projection plane 300. Specifically, the projection unit 150 includes a projection lens group (projection lens group 151 shown in FIG. 5) that projects the light emitted from the color separation / synthesis unit 140 onto the projection plane 300, and the projection lens group. A reflecting mirror (concave mirror 152 shown in FIG. 5) that reflects light toward the projection surface 300; Details of the projection unit 150 will be described later.

  The projection surface side recess 160 </ b> A and the projection surface side recess 160 </ b> B are provided on the projection surface side wall 210 and have a shape that is recessed inside the housing 200. The projection surface side recess 160 </ b> A and the projection surface side recess 160 </ b> B extend to the end of the housing 200. The projection surface side recess 160 </ b> A and the projection surface side recess 160 </ b> B are provided with vent holes that communicate with the inside of the housing 200.

  In the first embodiment, the projection surface side recess 160 </ b> A and the projection surface side recess 160 </ b> B extend along the width direction of the housing 200. For example, the projection surface side recess 160 </ b> A is provided with an air inlet for allowing air outside the housing 200 to enter the housing 200 as a vent. The projection surface side recess 160 </ b> B is provided with an exhaust port for venting air inside the housing 200 to the outside of the housing 200 as a vent.

  The front-side convex portion 170 is provided on the front-side side wall 220 and has a shape protruding to the outside of the housing 200. The front side convex portion 170 is provided at the approximate center of the front side wall 220 in the width direction of the housing 200. A reflection mirror (concave mirror 152 shown in FIG. 5) provided in the projection unit 150 is accommodated in a space formed by the front-side convex portion 170 inside the housing 200.

  The top plate recess 180 is provided in the top plate 240 and has a shape that is recessed inside the housing 200. The top plate recess 180 has an inclined surface 181 that goes down toward the projection plane 300 side. The inclined surface 181 has a transmission region that transmits (projects) the light emitted from the projection unit 150 to the projection surface 300 side.

  The cable terminal 190 is provided on the first side wall 250 and is a terminal such as a power terminal or a video terminal. The cable terminal 190 may be provided on the second side wall 260.

(Arrangement of units in the width direction of the housing)
Below, arrangement | positioning of each unit in the width direction which concerns on 1st Embodiment is demonstrated, referring drawings. FIG. 3 is a view of the projection display apparatus 100 according to the first embodiment as viewed from above.

  As shown in FIG. 3, the projection unit 150 is disposed in the approximate center of the casing 200 in the horizontal direction (width direction of the casing 200) parallel to the projection plane 300.

  The light source unit 110 and the cooling unit 130 are arranged side by side with the projection unit 150 in the width direction of the housing 200. Specifically, the light source unit 110 is arranged side by side on the one side (second side wall 260 side) of the projection unit 150 in the width direction of the casing 200. The cooling unit 130 is arranged side by side on the other side (first side wall 250 side) of the projection unit 150 in the width direction of the casing 200.

  The power supply unit 120 is arranged side by side with the projection unit 150 in the width direction of the housing 200. Specifically, the power supply unit 120 is arranged side by side on the light source unit 110 side with respect to the projection unit 150 in the width direction of the casing 200. The power supply unit 120 is preferably disposed between the projection unit 150 and the light source unit 110.

(Configuration of light source unit)
Hereinafter, the configuration of the light source unit according to the first embodiment will be described with reference to the drawings. FIG. 4 is a diagram illustrating the light source unit 110 according to the first embodiment.

  As shown in FIG. 4, the light source unit 110 includes a plurality of red coherent light sources 111R, a plurality of green coherent light sources 111G, and a plurality of blue coherent light sources 111B.

  As described above, the red coherent light source 111R is a red coherent light source such as an LD that emits the red component light R. The red coherent light source 111R has a head 112R, and an optical fiber 113R is connected to the head 112R.

  The optical fibers 113R connected to the heads 112R of each red coherent light source 111R are bundled by a bundle portion 114R. That is, the light emitted from each red coherent light source 111R is transmitted by each optical fiber 113R and collected in the bundle portion 114R.

  The red coherent light source 111R is placed on the cooling jacket 131R. For example, the red coherent light source 111R is fixed to the cooling jacket 131R by screwing or the like. Therefore, the red coherent light source 111R is cooled by the cooling jacket 131R.

  The green coherent light source 111G is a green coherent light source such as an LD that emits the green component light G as described above. The green coherent light source 111G has a head 112G, and an optical fiber 113G is connected to the head 112G.

  The optical fibers 113G connected to the head 112G of each green coherent light source 111G are bundled by a bundle unit 114G. That is, the light emitted from each green coherent light source 111G is transmitted by each optical fiber 113G and collected in the bundle unit 114G.

  The green coherent light source 111G is placed on the cooling jacket 131G. For example, the green coherent light source 111G is fixed to the cooling jacket 131G by screwing or the like. Therefore, the green coherent light source 111G is cooled by the cooling jacket 131G.

  The coherent light source 111B is a blue coherent light source such as an LD that emits the blue component light B as described above. The blue coherent light source 111B has a head 112B, and an optical fiber 113B is connected to the head 112B.

  The optical fibers 113B connected to the head 112B of each blue coherent light source 111B are bundled by a bundle unit 114B. That is, the light emitted from each blue coherent light source 111B is transmitted by each optical fiber 113B and collected in the bundle portion 114B.

  The blue coherent light source 111B is placed on the cooling jacket 131B. For example, the blue coherent light source 111B is fixed to the cooling jacket 131B by screwing or the like. Therefore, the blue coherent light source 111B is cooled by the cooling jacket 131B.

(Configuration of color separation / synthesis unit and projection unit)
Hereinafter, configurations of the color separation / synthesis unit and the projection unit according to the first embodiment will be described with reference to the drawings. FIG. 5 is a diagram showing the color separation / synthesis unit 140 and the projection unit 150 according to the first embodiment. The first embodiment exemplifies a projection display apparatus 100 that supports a DLP (Digital Light Processing) method (registered trademark).

  As illustrated in FIG. 5, the color separation / synthesis unit 140 includes a first unit 141 and a second unit 142.

  The first unit 141 combines the red component light R, the green component light G, and the blue component light B, and outputs the combined light including the red component light R, the green component light G, and the blue component light B to the second unit 142. To do.

  Specifically, the first unit 141 includes a plurality of rod integrators (rod integrator 10R, rod integrator 10G and rod integrator 10B), a lens group (lens 21R, lens 21G, lens 21B, lens 22, lens 23), And a mirror group (mirror 31, mirror 32, mirror 33, mirror 34, and mirror 35).

  The rod integrator 10R has a light incident surface, a light emitting surface, and a light reflecting side surface provided from the outer periphery of the light incident surface to the outer periphery of the light emitting surface. The rod integrator 10R makes the red component light R emitted from the optical fiber 113R bundled by the bundle portion 114R uniform. In other words, the rod integrator 10R makes the red component light R uniform by reflecting the red component light R on the light reflection side surface.

  The rod integrator 10G has a light incident surface, a light emitting surface, and a light reflecting side surface provided from the outer periphery of the light incident surface to the outer periphery of the light emitting surface. The rod integrator 10G makes the green component light G emitted from the optical fiber 113G bundled by the bundle portion 114G uniform. That is, the rod integrator 10G makes the green component light G uniform by reflecting the green component light G on the light reflection side surface.

  The rod integrator 10B has a light incident surface, a light emitting surface, and a light reflecting side surface provided from the outer periphery of the light incident surface to the outer periphery of the light emitting surface. The rod integrator 10B makes the blue component light B emitted from the optical fiber 113B bundled by the bundle portion 114B uniform. That is, the rod integrator 10B makes the blue component light B uniform by reflecting the blue component light B on the light reflection side surface.

  Note that the rod integrator 10R, the rod integrator 10G, and the rod integrator 10B may be hollow rods whose light-reflecting side surfaces are configured by mirror surfaces. Further, the rod integrator 10R, the rod integrator 10G, and the rod integrator 10B may be solid rods made of glass or the like.

  The speckle noise reduction element 20R is disposed immediately after the light exit surface of the rod integrator 10R that is substantially conjugate to the light modulation element and the screen surface, and is perpendicular to the optical axis of the red component light R from the rod integrator 10R. Periodically oscillates, swings, or rotates in the direction of. Here, vibration means reciprocating with respect to a specific axis around the optical axis of light, or reciprocating in parallel with the optical axis of light, and oscillation means that the optical axis of light is reciprocated. In contrast, it indicates that the surface moves in a substantially circular plane, and the rotation indicates that the rotation is performed around a specific axis parallel to the optical axis of light. The speckle noise reduction element 20R periodically vibrates, swings, or rotates, so that the red component light R emitted from the rod integrator 20R passes through the speckle noise reduction element 20R and is emitted. The position and phase can be changed according to time.

  The speckle noise reduction element 20G is disposed immediately after the light exit surface of the rod integrator 10G that is a substantially conjugate surface of the light modulation element and the screen surface, and is perpendicular to the optical axis of the green component light G from the rod integrator 10G. Periodically oscillates, swings, or rotates in the direction of. The speckle noise reduction element 20G periodically vibrates, swings, or rotates so that the red component light G emitted from the rod integrator 20G passes through the speckle noise reduction element 20G and is emitted. The position and phase can be changed according to time.

  The speckle noise reduction element 20B is disposed immediately after the light exit surface of the rod integrator 10B, which is a substantially conjugate surface of the light modulation element and the screen surface, and is perpendicular to the optical axis of the blue component light B from the rod integrator 10B. Are periodically vibrated, oscillated, or rotated in the direction of. The speckle noise reducing element 20B periodically vibrates, swings, or rotates so that the green component light B emitted from the rod integrator 20B is emitted from the speckle noise reducing element 20B. When the light passes through the reduction element 20B and is emitted, the emission position and phase of each light beam can be changed according to time.

  Speckle noise is observed as an irregular granular intensity distribution when coherent light such as laser light is scattered at each point on a rough surface such as a screen and interferes with an irregular phase relationship caused by the surface roughness. It is a phenomenon. By oscillating, swinging, or rotating the speckle noise reduction element arranged in the illumination optical system, the position and phase of each light beam emitted from the speckle noise reduction element changes with time. Thereby, since the angle and phase of each light ray incident on each point on the screen surface change with time, the speckle pattern is superimposed on time, and the speckle noise that is visually recognized is reduced.

  The lens 21R is a relay lens that relays the red component light R so that the red component light R is irradiated onto the DMD 500R. The lens 21G is a relay lens that relays the green component light G so that the DMD 500G is irradiated with the green component light G. The lens 21B is a relay lens that relays the blue component light B so that the blue component light B is irradiated onto the DMD 500B.

  The lens 22 is a relay lens for substantially imaging the red component light R and the green component light G on the DMD 500R and DMD 500G while suppressing the expansion of the red component light R and the green component light G. The lens 23 is a relay lens for substantially imaging the blue component light B on the DMD 500B while suppressing the expansion of the blue component light B.

  The mirror 31 reflects the red component light R emitted from the rod integrator 10R. The mirror 32 is a dichroic mirror that reflects the green component light G emitted from the rod integrator 10G and transmits the red component light R. The mirror 33 is a dichroic mirror that transmits the blue component light B emitted from the rod integrator 10B and reflects the red component light R and the green component light G.

  The mirror 34 reflects the red component light R, the green component light G, and the blue component light B. The mirror 35 reflects the red component light R, the green component light G, and the blue component light B to the second unit 142 side. In FIG. 5, each component is shown in a plan view for the sake of simplicity. However, the mirror 35 obliquely reflects the red component light R, the green component light G, and the blue component light B in the height direction. Reflect on.

  The second unit 142 separates the combined light including the red component light R, the green component light G, and the blue component light B, and modulates the red component light R, the green component light G, and the blue component light B. Subsequently, the second unit 142 recombines the red component light R, the green component light G, and the blue component light B, and emits image light to the projection unit 150 side.

  Specifically, the second unit 142 includes a lens 40, a prism 50, a prism 60, a prism 70, a prism 80, a prism 90, and a plurality of DMDs; Digital Micromirror Device (DMD500R, DMD500G, and DMD500B). Have

  The lens 40 is a relay lens that relays light emitted from the first unit 141 so that each color component light is irradiated to each DMD.

  The prism 50 is made of a translucent member and has a surface 51 and a surface 52. An air gap is provided between the prism 50 (surface 51) and the prism 60 (surface 61), and the angle (incident angle) at which the light emitted from the first unit 141 enters the surface 51 is the total reflection angle. Therefore, the light emitted from the first unit 141 is reflected by the surface 51. On the other hand, an air gap is provided between the prism 50 (surface 52) and the prism 70 (surface 71), but the angle at which the light emitted from the first unit 141 enters the surface 52 (incident angle) is all. Since it is smaller than the reflection angle, the light reflected by the surface 51 passes through the surface 52.

  The prism 60 is made of a translucent member and has a surface 61.

  The prism 70 is made of a translucent member and has a surface 71 and a surface 72. An air gap is provided between the prism 50 (surface 52) and the prism 70 (surface 71), and the blue component light B reflected by the surface 72 and the blue component light B emitted from the DMD 500B are formed on the surface 71. Since the incident angle (incident angle) is larger than the total reflection angle, the blue component light B reflected by the surface 72 and the blue component light B emitted from the DMD 500B are reflected by the surface 71.

  The surface 72 is a dichroic mirror surface that transmits the red component light R and the green component light G and reflects the blue component light B. Accordingly, among the light reflected by the surface 51, the red component light R and the green component light G are transmitted through the surface 72, and the blue component light B is reflected by the surface 72. The blue component light B reflected by the surface 71 is reflected by the surface 72.

  The prism 80 is made of a translucent member and has a surface 81 and a surface 82. An air gap is provided between the prism 70 (surface 72) and the prism 80 (surface 81). The red component light R transmitted through the surface 81 and reflected by the surface 82 and the red component emitted from the DMD 500R. Since the angle (incident angle) at which the light R again enters the surface 81 is larger than the total reflection angle, the red component light R transmitted through the surface 81 and reflected by the surface 82 and the red component light R emitted from the DMD 500R are Reflected by the surface 81. On the other hand, since the angle (incident angle) at which the red component light R emitted from the DMD 500R and reflected by the surface 81 and then reflected by the surface 82 is incident on the surface 81 again is smaller than the total reflection angle, it is emitted from the DMD 500R. Then, the red component light R reflected by the surface 82 after being reflected by the surface 81 passes through the surface 81.

  The surface 82 is a dichroic mirror surface that transmits the green component light G and reflects the red component light R. Accordingly, among the light transmitted through the surface 81, the green component light G is transmitted through the surface 82, and the red component light R is reflected by the surface 82. The red component light R reflected by the surface 81 is reflected by the surface 82. The green component light G emitted from the DMD 500G passes through the surface 82.

  Here, the prism 70 separates the combined light including the red component light R and the green component light G and the blue component light B by the surface 72. The prism 80 separates the red component light R and the green component light G by the surface 82. That is, the prism 70 and the prism 80 function as a color separation element that separates each color component light.

  In the first embodiment, the cutoff wavelength of the surface 72 of the prism 70 is provided between a wavelength band corresponding to green and a wavelength band corresponding to blue. The cut-off wavelength of the surface 82 of the prism 80 is provided between a wavelength band corresponding to red and a wavelength band corresponding to green.

  On the other hand, the prism 70 combines the combined light including the red component light R and the green component light G and the blue component light B with the surface 72. The prism 80 combines the red component light R and the green component light G with the surface 82. That is, the prism 70 and the prism 80 function as a color composition element that synthesizes each color component light.

  The prism 90 is made of a translucent member and has a surface 91. The surface 91 is configured to transmit the green component light G. The green component light G incident on the DMD 500G and the green component light G emitted from the DMD 500G pass through the surface 91.

  DMD500R, DMD500G, and DMD500B are configured by a plurality of micromirrors, and the plurality of micromirrors are movable. Each minute mirror basically corresponds to one pixel. The DMD 500R switches whether to reflect the red component light R toward the projection unit 150 by changing the angle of each micromirror. Similarly, the DMD 500G and the DMD 500B switch whether to reflect the green component light G and the blue component light B toward the projection unit 150 by changing the angle of each micromirror.

  The projection unit 150 includes a projection lens group 151 and a concave mirror 152.

  The projection lens group 151 emits light (image light) emitted from the color separation / combination unit 140 to the concave mirror 152 side.

  The concave mirror 152 reflects light (image light) emitted from the projection lens group 151. The concave mirror 152 condenses the image light and then widens the image light. For example, the concave mirror 152 is an aspherical mirror having a concave surface on the projection lens group 151 side.

  The image light collected by the concave mirror 152 passes through a transmission region provided on the inclined surface 181 of the top plate recess 180 provided on the top plate 240. The transmission region provided on the inclined surface 181 is preferably provided in the vicinity of the position where the image light is collected by the concave mirror 152.

  As described above, the concave mirror 152 is accommodated in the space formed by the front side convex portion 170. For example, the concave mirror 152 is preferably fixed inside the front side convex portion 170. In addition, the shape of the inner surface of the front side convex portion 170 is preferably a shape along the concave mirror 152.

(Basic configuration of speckle noise reduction element)
FIG. 6 shows details of the speckle noise reduction element 20R, the speckle noise reduction element 20G, and the speckle noise reduction element 20B. The speckle noise reduction element 20R, the speckle noise reduction element 20G, and the speckle noise reduction element 20B include an incident side microlens array 310, an element substrate 320, an emission side microlens array 312,
And vibration imparting means (not shown).

  The incident side microlens array 310 is an aggregate of hemispherical microlenses formed innumerably on the light incident surface side of the speckle noise reduction element 20R, the speckle noise reduction element 20G, and the speckle noise reduction element 20B. is there. Each lens of the incident side microlens array 310 is a microlens having a refractive index of n and a focal length of f.

  In the element substrate 320, the incident side microlens array 310 and the emission side microlens array 312 are fixed with an ultraviolet curable adhesive. The element substrate 320 is a transparent substrate having a refractive index n and a thickness of 2 f / n.

  The emission side microlens array 312 is an aggregate of hemispherical microlenses formed innumerably on the light emission surface side of the speckle noise reduction element 20R, the speckle noise reduction element 20G, and the speckle noise reduction element 20B. is there. Each lens of the exit side microlens array 312 is a microlens having a refractive index n and a focal length f.

  The incident side microlens array 310, the element substrate 320, and the emission side microlens array 312 are fixed with an ultraviolet curable adhesive, but the present invention is not limited thereto. The side microlens array 312 may be formed by integral molding. By doing so, it is not necessary to attach the incident side microlens array 310, the element substrate 320, and the emission side microlens array 312 or to adjust the optical axis.

  Next, the optical path of light traveling through the speckle noise reducing element 20R, the speckle noise reducing element 20G, and the speckle noise reducing element 20B will be described with reference to FIG. Light emitted from the emission end faces of the rod integrator 10R, rod integrator 10G, and rod integrator 10B is incident on the incident side microlens array 310 that is separated by a distance 2f. The light incident on the incident side microlens array 310 is refracted and passes through the inside of the incident side microlens array 310 and the element substrate 320. Refraction occurs only on the incident surface of the incident side microlens array 310, and no refraction occurs on the boundary surface between the incident side microlens array 310 and the element substrate 320 having the same refractive index.

  Since the element substrate 320 has a thickness of 2 f / n, the light passing through the element substrate 320 forms an image on the emission side microlens array 312 fixed to the emission side of the element substrate 320.

  Since the focal length of the exit side microlens array 312 is f and is the same as that of the entrance side microlens array 310, the entrance side divergence angle θ and the exit side divergence angle η are the same.

  As described above, since the exit-side divergence angle η is the same as the incident-side divergence angle θ, light having an angle that cannot be captured by the projection lens 151 is unlikely to be generated, and light loss used for the projected image is unlikely to occur.

  Next, the speckle noise reduction element 20R, the speckle noise reduction element 20G, and the speckle noise reduction element 20B are vibrated, oscillated, or rotated, so that the optical path length of incident light changes with time, and the speckle noise reduction element. The phenomenon in which the emission position and phase of the light emitted from the light changes with time will be described with reference to FIGS. 7 (a), 7 (b), and 7 (c).

  FIG. 7A is a diagram focusing on a pair of microlenses of the incident side microlens array 310 and the emission side microlens array 312.

  The light emitted from the emission end faces of the rod integrator 10R, the rod integrator 10G, and the rod integrator 10B is incident on the incident side microlens 311 that is separated by a distance 2f. The light incident on the incident side microlens 311 is refracted and passes through the inside of the incident side microlens 311 and the element substrate 320. Refraction occurs only on the incident surface of the incident side microlens 311, and no refraction occurs on the boundary surface between the incident side microlens 311 and the element substrate 320 having the same refractive index.

  Since the thickness of the element substrate 320 is 2 f / n, the light passing through the element substrate 320 forms an image at the center of the emission side microlens 313 fixed to the emission side of the element substrate 320.

  FIG. 7B shows an optical path of light when the speckle noise reduction element 20R, the speckle noise reduction element 20G, and the speckle noise reduction element 20B move upward due to vibration with respect to FIG. FIG.

  FIG. 7C shows the optical path of light when the speckle noise reduction element 20R, the speckle noise reduction element 20G, and the speckle noise reduction element 20B move downward due to vibration with respect to FIG. FIG.

  For example, when the speckle noise reducing element 20R, the speckle noise reducing element 20G, and the speckle noise reducing element 20B vibrate up and down, the positions at which the emitted light from the emission side microlens is emitted are shown in FIGS. c) is different. Further, when the speckle noise reducing element 20R, the speckle noise reducing element 20G, and the speckle noise reducing element 20B vibrate up and down, the light that has passed through the different optical path lengths shown in FIGS. Will be imaged. Therefore, the light emitted from the emission side microlens is emitted from the speckle noise reduction element 20R, the speckle noise reduction element 20G, and the speckle noise reduction element 20B as light having different phases.

  As a result, the angle and phase of each light ray incident on each point on the screen surface change with time, so that the speckle pattern is superimposed on time and the speckle noise that is visually recognized is reduced.

(Application configuration of speckle noise reduction element)
Next, returning to FIG. 6, the microlenses of the speckle noise reduction element 20R, the speckle noise reduction element 20G, and the speckle noise reduction element 20B will be described in detail. The speckle noise reduction element 20R, the speckle noise reduction element 20G, and the speckle noise reduction element 20B emit all the incident light when the light emitted from the distance of 2f is within the incident side divergence angle θ. The light can be emitted within an angle η. That is, assuming that the diameters of the incident side microlens 311 and the emission side microlens 313 are d, the relationship between the incident side divergence angle θ and the emission side divergence angle η is θ = η when the following conditions are satisfied.

  If the diameters of the incident-side microlens 311 and the emission-side microlens 313 are designed according to the above conditions, the emission-side divergence angle η is the same as the incident-side divergence angle θ compared to the basic configuration of the speckle noise reduction element. Therefore, it is difficult to generate light at an angle that cannot be captured by the projection lens, and it is difficult to cause light loss used in a projected image.

  In the above embodiment, the element substrate 320 is disposed between the incident-side microlens array 310 and the emission-side microlens array 312, but the present invention is not limited to this configuration, and the incident-side microlens array 310 and the emission-side microlens array 310 are arranged. The side microlens array 312 may be arranged independently, and each distance may be separated by 2f.

[Modification 1]
Hereinafter, Modification Example 1 of the first embodiment will be described with reference to the drawings. In the following, differences from the first embodiment will be mainly described.

  Specifically, in the first embodiment, the light source unit 110 includes a red coherent light source 111R, a green coherent light source 111G, and a blue coherent light source 111B, and the color separation / synthesis unit 140 includes a rod integrator 10R and a rod integrator 10G. And a rod integrator 10R that is substantially conjugate to the screen surface, a speckle noise reduction element R20, a speckle noise reduction element G20, immediately before the light exit surface of the rod integrator 10G and the rod integrator 10B, and A speckle noise reduction element B20 was arranged.

  On the other hand, in the first modification, the light source unit 110 has a white coherent light source, and the color separation / synthesis unit 140 has a single rod integrator 10 </ b> W on a substantially conjugate surface of the screen surface. A speckle noise reduction element W20 is disposed immediately before the light exit surface of the rod integrator 10W.

[Modification 2]
Hereinafter, Modification Example 1 of the first embodiment will be described with reference to the drawings. In the following, differences from the first embodiment will be mainly described.

  Specifically, in the first embodiment, the incident side microlens array 310 and the emission side microlens array 312 are described as having the same focal length f. In Modification 2, a case will be described in which the focal length of the exit-side microlens array 312 is different from the focal length f of the incident-side microlens array 310 (the focal length is f ′).

  The light incident on the incident side microlens array 310 is refracted and passes through the inside of the incident side microlens array 310 and the element substrate 320. The light passing through the inside of the element substrate 320 is fixed to the emission side of the element substrate 320 when the thickness of the element substrate 320 is (f + f ′) / n because the focal length of the emission side microlens array 312 is f ′. An image is formed by the exit side microlens array 312.

  Here, the relationship between the focal length f and the focal length f ′ satisfies f ≦ f ′. By doing so, the relationship between the incident-side divergence angle θ and the emission-side divergence angle η satisfies θ ≧ η. Therefore, light at an angle that cannot be captured by the projection lens 151 is unlikely to be generated, and light loss used for the projected image is unlikely to occur.

  When the incident-side microlens array 310 is composed of n × m microlenses, the exit-side microlens array 312 needs to be composed of n × m microlenses.

(Configuration of color separation / synthesis unit and projection unit)
Hereinafter, configurations of the color separation / synthesis unit and the projection unit according to Modification 1 will be described with reference to the drawings. FIG. 7 is a diagram illustrating the color separation / synthesis unit 140 and the projection unit 150 according to the first modification. In FIG. 7, the same reference numerals are given to the same configurations as those in FIG. 5.

  As shown in FIG. 7, a speckle reduction element W20 is provided instead of the speckle noise reduction element R20, the speckle noise reduction element G20, and the speckle noise reduction element B20. The color separation / synthesis unit 140 includes a rod integrator 10W instead of the rod integrator 10R, the rod integrator 10G, and the rod integrator 10B. The color separation / combination unit 140 includes a lens 21W instead of the lens 21R, the lens 21G, and the lens 21B.

  White light is incident on the rod integrator 10W from the bundle portion 114W. Here, it should be noted that white light is emitted from the bundle unit 114W.

  For example, the bundle unit 114W may bundle optical fibers that transmit white light emitted from a light source (such as an LD). In such a case, a plurality of coherent light sources that emit white light are provided as the plurality of coherent light sources.

  The bundle unit 114W may bundle the optical fiber 113R, the optical fiber 113G, and the optical fiber 113B. In such a case, as in the first embodiment, a red coherent light source 111R, a green coherent light source 111G, and a blue coherent light source 111B are provided as a plurality of coherent light sources.

  The lens 21 </ b> W is a relay lens that relays white light so that the white light is irradiated to each DMD 500.

[Second Embodiment]
Hereinafter, the second embodiment will be described with reference to the drawings. In the following, differences from the first embodiment will be mainly described.

  Specifically, in the first embodiment, the case where the projection display apparatus 100 projects image light onto the projection plane 300 provided on the wall surface is illustrated. In contrast, the second embodiment exemplifies a case where the projection display apparatus 100 projects image light onto the projection plane 300 provided on the floor (floor projection). The arrangement of the casing 200 in such a case is referred to as a floor projection arrangement.

(Configuration of projection display device)
Hereinafter, the configuration of the projection display apparatus according to the second embodiment will be described with reference to the drawings. FIG. 8 is a side view of the projection display apparatus 100 according to the second embodiment.

  As shown in FIG. 8, the projection display apparatus 100 projects image light onto a projection plane 300 provided on the floor (floor projection). In the second embodiment, the first arrangement surface that is substantially parallel to the projection surface 300 is the floor surface 410. A second arrangement surface that is substantially perpendicular to the first arrangement surface is a wall surface 420.

  In the second embodiment, a horizontal direction parallel to the projection plane 300 is referred to as a “width direction”. The normal direction of the projection plane 300 is referred to as a “height direction”. A direction orthogonal to both the width direction and the height direction is referred to as a “depth direction”.

  In the second embodiment, the housing 200 has a substantially rectangular parallelepiped shape, as in the first embodiment. The size of the housing 200 in the depth direction and the size of the housing 200 in the height direction are smaller than the size of the housing 200 in the width direction. The size of the casing 200 in the height direction is substantially equal to the projection distance from the reflection mirror (concave mirror 152 shown in FIG. 2) to the projection plane 300. In the width direction, the size of the casing 200 is substantially equal to the size of the projection plane 300. In the depth direction, the size of the casing 200 is determined according to the distance from the wall surface 420 to the projection plane 300.

  The projection surface side wall 210 is a plate-like member that faces a first arrangement surface (in the second embodiment, the floor surface 410) substantially parallel to the projection surface 300. The front side wall 220 is a plate-like member provided on the opposite side of the projection plane side wall 210. The top plate 240 is a plate-like member provided on the opposite side of the bottom plate 230. The bottom plate 230 is a plate-like member that faces a second arrangement surface (in the second embodiment, a wall surface 420) other than the first arrangement surface substantially parallel to the projection plane 300. The first side wall 250 and the second side wall 260 are plate-like members that form both ends of the housing 200 in the width direction. In the second embodiment, a red coherent light source, a green coherent light source, a blue coherent light source, or a white coherent light source may be used.

[Other Embodiments]
Although the present invention has been described with reference to the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the first embodiment, the projection plane 300 is provided on the wall surface 420 on which the housing 200 is disposed, but the embodiment is not limited to this. Projection plane 300 may be provided at a position deeper than wall surface 420 in the direction away from housing 200.

  In the second embodiment, the projection plane 300 is provided on the floor surface 410 on which the housing 200 is disposed, but the embodiment is not limited to this. The projection plane 300 may be provided at a position lower than the floor surface 410.

  In the embodiment, a DMD (Digital Micromirror Device) is merely illustrated as the light modulation element. The light modulation element may be a transmissive liquid crystal panel or a reflective liquid crystal panel.

  In the embodiment, a plurality of DMDs are provided as the light modulation elements, but a single DMD may be provided as the light modulation element.

20R, 20G, 20B Speckle noise reduction element (optical unit)
DESCRIPTION OF SYMBOLS 100 Projection type image display apparatus 110 Light source unit 112R, 112G, 112B Coherent light source 150 Projection unit 310, 312 Lens array 311, 313 Micro lens 500R, 500G, 500B Light modulation element

Claims (4)

A pair of lens arrays;
Vibration applying means for periodically moving the pair of lens arrays;
An optical unit comprising: The optical unit according to claim 1, wherein
The pair of lens arrays includes:
A first lens array having a focal length f and a second lens array having a focal length f ′;
The focal length f and the focal length f ′ satisfy f ≦ f ′,
When a medium having an absolute refractive index n is interposed between the first lens array and the second lens array, the first lens array and the second lens array are (f + f ′) / An optical unit characterized by being arranged with an interval of n. A light source unit composed of a coherent light source;
An optical unit that periodically moves so that light emitted from the light source unit passes, a light modulation element that modulates light emitted from the light source unit, and a projection unit that projects light modulated by the light modulation element A projection display apparatus comprising:
The optical unit includes a pair of lens arrays. The projection display apparatus according to claim 3, wherein
When the divergence angle of light incident on the optical unit is θ,
The lens array arranged at least on the incident side of the pair of lens arrays has a lens diameter d and a focal length f set so as to satisfy the condition of tan θ <d / 4f. Type image display device.

Images