Patent Publication Number: US-2023141871-A1

Title: Projector and design filter

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     The present patent application claims the priority of Japanese patent applications No.2021/182478 filed on Nov. 9, 2021, and No.2022/170483 filed on Oct. 25, 2022, and the entire contents of Japanese patent applications No.2021/182478 and No.2022/170483 are hereby incorporated by reference. 
     TECHNICAL FIELD 
     The present invention relates to a projector and a design filter and, in particular, to a projector and a design filter used in a vehicle interior. 
     BACKGROUND ART 
     A vehicle lamp is known that includes a condenser lens condensing light emitted from a light source, a blind member partially transmitting light condensed at the condenser lens, and a projection lens forming an irradiation pattern by projecting light transmitted at the blind member (see e.g., Patent Literature 1). 
     For the vehicle lamp described in Patent Literature 1, the condenser lens, a filter, and the projection lens are housed in a housing, and respectively fitted and fixed in a condenser lens groove, a filter groove, and a projection lens groove that are included in the housing. Also, in the vehicle lamp described in Patent Literature 1, an irradiation slit partially transmitting light condensed at the condenser lens is provided at a filter as the blind member to form the irradiation pattern. 
     Citation List 
     Patent Literature 
     Patent Literature 1: JP 2020/205237 A 
     SUMMARY OF INVENTION 
     However, in the vehicular lamp described in Patent Literature 1, since the positions of the condenser lens, the filter, and the projection lens are fixed by the housing, the relative positioning accuracy of the condenser lens, the filter, and the projection lens is low and, worse, the projected image may be blurred. Foreign matter such as dust may enter the space where the filter is installed from the outside through the gap between the condenser lens and the housing in the condenser lens groove and the gap between the projection lens and the housing in the projection lens groove. Therefore, the foreign matter may enter and be reflected in the projected image. 
     Also, in order to install the irradiation slit in the filter like the vehicle lamp described in Patent Literature 1, a complicated method of providing a light-blocking layer having a slit on a base material by printing, photolithography, or the like is generally used. Therefore, it becomes costly. 
     It is an object of the present invention to provide a projector that is capable of projecting a clear image in which reflection of foreign matter is suppressed. 
     It is another object of the present invention to provide a projector that can be manufactured at low cost to project a pattern in a vehicle interior, etc., and a pattern filter used in the projector that can be manufactured at low cost. 
     An aspect of the present invention provides a projector and a design filter as defined below. 
     (1) A projector, comprising:
         a light source to emit light;   a design plate comprising a design for projecting;   a first lens part comprising a condenser lens to condense light emitted from the light source and sends to the design plate; and   a second lens part comprising a projection lens to project the design of the design plate,   wherein the first lens part and the second lens part sandwich and fix the design plate to seal the design plate inside.       

     (2) The projector according to (1), wherein the design plate further comprises a transparent substrate and an opacifying film on the transparent substrate comprising a pattern to form the design, and
         wherein a minimum width of the opacifying film is less than 10 μm.       

     (3) The projector according to (1) or (2), wherein a fine part of which at least is partially included in the design of the design plate is not projected at a focused projection image, and
         wherein a brightness between a brightness at a part formed by a light transmitting part of the design and a brightness at a part formed by a light blocking part of the design in the projection image is described by the fine part.       

     (4) A projector, comprising
         a light source to emit light;   a design filter comprising a transparent material comprising a design for projecting; and   a projection lens to magnify and project the design of the design filter,   wherein the design filter comprises a design formed surface, and   wherein the design formed surface comprises a first surface having an angle of not less than 75° and not more than 105° to a thickness direction of the design filter, and a second surface having an angle of not less than 30° and not more than 60° to the thickness direction of the design filter, the first and second surfaces being arranged corresponding to the design.       

     (5) The projector according to (4), wherein the design formed surface of the design filter comprises a base plane comprising the first surface and at least one of a protrusion comprising the two second surfaces opposed to each other and a cavity comprising the two second surfaces opposed to each other. 
     (6) The projector according to (4) or (5), wherein the design filter is plate-shaped and further comprises the design formed surfaces on both surfaces thereof. 
     (7) The projector according to (4) or (5), wherein the design filter comprises a lens part serving as a condenser lens to condense light emitted from the light source on an opposite side of the design formed surface. 
     (8) A design filter, comprising:
         a plate-shaped transparent material comprising a design for projector projection; and
           a design formed surface at both surfaces thereof,   wherein the design formed surface comprises a first surface having an angle of not less than 75° and not more than 105° to a thickness direction of the design filter, and a second surface having an angle of not less than 30° and not more than 60° to the thickness direction of the design filter, the first and second surfaces being arranged corresponding to the design.   
               

     (9) A design filter, comprising:
         a transparent material comprising a design for projector projection;
           a design formed surface; and   a lens part serving as a condenser lens to condense light emitted from a light source of a projector on an opposite side of the design formed surface,   wherein the design formed surface comprises a first surface having an angle of not less than 75° and not more than 105° to a thickness direction of the design filter, and a second surface having an angle of not less than 30° and not more than 60° to the thickness direction of the design filter, the first and second surfaces being arranged corresponding to the design.   
               

     Advantageous Effects of Invention 
     According to an embodiment of the present invention, it is possible to provide a projector that is capable of projecting a clear image in which reflection of foreign matter is suppressed. 
     Also, according to an embodiment of the present invention, it is possible to provide a projector that can be manufactured at low cost to project a pattern in a vehicle interior, etc., and a pattern filter used in the projector that can be manufactured at low cost. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS.  1 A and  1 B  are perspective views respectively showing a projector according to the embodiment of the present invention, which are viewed from different angles. 
         FIG.  2 A  is a side view showing the projector according to the embodiment of the present invention viewed from a light extracting side. 
         FIG.  2 B  is a cross-sectional view showing the projector cut along a line A-A shown in  FIG.  2 A . 
         FIG.  3    is an exploded perspective view showing the projector according to the embodiment of the present invention. 
         FIGS.  4 A to  4 D  are perspective views showing a flow of attaching a first lens part, a design plate, and a second lens part to a body parts. 
         FIG.  5 A  is a cross-sectional view showing the body parts, the first lens part, and the second lens part cut along a line B-B shown in  FIG.  4 D . 
         FIG.  5 B  is the cross-sectional view showing the first lens part  21 , and the second lens part  22 , and the design plate  20  cut along a line C-C shown in  FIG.  4 D . 
         FIG.  6    is a longitudinal cross-sectional view showing an embodiment of design plate according to the embodiment of the present invention. 
         FIG.  7 A  is a schematic view showing an example of design on the design plate according to the embodiment of the present invention. 
         FIG.  7 B  is a schematic view showing a projection image projecting the design of  FIG.  7 A . 
         FIG.  8    is a longitudinal cross-sectional view showing another embodiment of design plate according to the embodiment of the present invention. 
         FIG.  9    is a schematic view explaining a condition causing total reflection when a light blocking part of the design plate includes projection including two inclined surfaces opposed to each other. 
         FIGS.  10 A to  10 C  are schematic views showing an optical path of light entering into the design plate of which angle θ t  are 90° , 140° and 40°, respectively. 
         FIGS.  11 A to  11 E  are cross-sectional views respectively showing arrangement examples of the inclined surface. 
         FIGS.  12 A to  12 C  are cross-sectional views showing variations of the design plate according to the embodiment of the present invention. 
         FIG.  13    is a cross-sectional view showing a projector comprising a design filter according to another embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     (Embodiments) 
       FIGS.  1 A and  1 B  are perspective views respectively showing a projector  1  according to the embodiment of the present invention, which are viewed from different angles.  FIG.  2 A  is a side view showing the projector  1  according to the embodiment of the present invention viewed from a light extracting side.  FIG.  2 B  is a cross-sectional view showing the projector  1  cut along the line A-A shown in  FIG.  2 A .  FIG.  3    is an exploded perspective view showing the projector  1 . 
     The projector  1  is mainly used in a vehicle interior. For example, the projector  1  is attached to a side panel of vehicle compartment, an instrument panel, or a door. The projector  1  projects an image on a door, a floor mattress, a roof, and a decorated panel or a decorated ornament included in the instrument panel or a door trim. 
     The projector  1  includes a light source  11  emitting light, a design plate  20  having a design for projecting, a first lens part  21  comprising a condenser lens  211  condensing light emitted from the light source  11  and sending to the design plate  20 , and a second lens part  22  comprising a projection lens  221  to project expanding the design of the design plate  20 . In the projector  1 , the first lens part  21  and the second lens part  22  sandwich and fix the design plate  20  to seal the design plate  20  inside the first lens part  21  and the second lens part  22 . 
     The light source  11  is a light emitting element comprising a light emitting diode (LED) chips and so on. The light source  11  is mounted on a circuit board  10 . A connector  12  to transmit power and signal to the light source  11  is connected to the circuit board  10 . 
     The circuit board  10  mounting the light source  11 , the first lens part  21 , the second lens part  22 , and the design plate  20  are housed in a body  30  comprising parts  30   a  ,  30   b  ,  30   c  . The body  30  includes an opening  301  to extract light from the projection lens  221  and an opening  302  to connect a connector of an external device to the connector  12 . The body  30  is formed of resins such as Polybutylene terephthalate (PBT) resin, Polypropylene (PP) resin, and Acrylonitrile-Butadiene-Styrene (ABS) resin. 
     The part  30   a  and the part  30   b  are fixed by snap-fitting protrusions  305  provided at both side surfaces of the part  30   b  to holes  304  provided on the part  30   a  . In addition, the part  30   a  and the part  30   c  are fixed by snap-fitting protrusions  307  provided at both side surfaces of the part  30   c  to holes  306  provided on the part  30   a  . The circuit board  10  is fixed by sandwiched between the part  30   a  and the part  30   c  . 
     The first lens part  21  includes the condenser lens  211 , a frame part  212  having a box-shape (e.g., rectangular) having one opening in one surface, and a fixing part  215  to fix the first lens part  21  to the second lens part  22  and the body part  30   b  . The condenser lens  211  is located in a surface facing the opening surface of the frame part  212 . The first lens part  21  is formed of resins such as Polycarbonate (PC) resin and Polymethyl methacrylate (PMMA) resin. 
     The second lens part  22  includes the projection lens  221 , a frame part  222  having a box-shape (e.g., rectangular) having one opening in one surface, and a fixing part  225  to fix the second lens part  21  to the first lens part  21  and the body part  30   b  . The projection lens  221  is located in a surface facing the opening surface of the frame part  222 . The second lens part  22  is formed of resins such as Polycarbonate resin and Polymethyl methacrylate resin. 
     In the projector  1 , the first lens part  21  and the second lens part  22  are fixed to facing the opening surface of the frame part  212  and the opening surface of the frame part  222  and wholly adhere an end surface  213  that is an edge of the opening surface of the frame part  212  and an end surface  223  that is an edge of the opening surface of the frame part  222 . Hereby, a space inside the first lens part  21  and the second lens part  22  including the design plate  20  is sealed. In addition, it is preferable to treat polishing the end surface  213  and the end surface  223  to increase sealing. 
     When adhering the first lens part  21  and the second lens part  22 , a portion  214  extended inside from four corners of interior of the frame part  212  and a portion  224  extended inside from four corners of interior of the frame part  222  fixes four corners of the design plate  20  with sandwiching from front and back. 
       FIGS.  4 A to  4 D  are perspective views showing a flow of attaching the first lens part  21 , the design plate  20 , and the second lens part  22  to the part  30   b  of the body  30 . 
     First, as shown in  FIGS.  4 A,  4 B , the second lens part  22  is attached to the part  30   b  of the body  30 . The fixing part  225  is fit in the part  30   b  of the body  30  with facing the opening surface of the frame part  222  upward. 
     Next, as shown in  FIGS.  4 B,  4 C , the design plate  20  is fit into the opening surface of the frame part  222  of the second lens part  22 . The design plate  20  is fit into the opening surface of the frame part  222  to ride the design plate  20  on a portion  224  in the frame part  222  of the second lens part  22 . 
     Next, as shown in  FIGS.  4 C,  4 D , the first lens part  21  is attached to the body part  30   b  . The fixing part  215  is fit into the part  30   b  of the body  30  to face the opening surface of the frame part  212  downward. Herein, a protrusion  226  provided at the fixing part  225  of the second lens part  22  is fit into the hole  216  provided at the fixing part  215  of the first lens part  21 . In addition, when the fixing part  215  is fit in the part  30   b  , protrusions  217  provided at both side surfaces of the fixing part  215  are snap-fit into holes  303  provided at the part  30   b  . 
       FIG.  5 A  is the cross-sectional view showing the part  30   b  of body  30 , the first lens part  21 , and the second lens part  22  cut along the line B-B shown in  FIG.  4 D . 
     As shown in  FIG.  5 A , since the second lens part  22  crushes upward and elastically deforms projections  308  provided at a bottom surface inside the part  30   b  , the second lens part  22  receives upward resilience from the projections  308 . In the meantime, since upward movement of the first lens part  21  and the second lens part  22  is prevented by hooking the projections  217  of the first lens part  21  to the hole  303 , the first lens part  21  and the second lens part  22  are fixed to the part  30   b  . 
       FIG.  5 B  is the cross-sectional view showing the first lens part  21 , and the second lens part  22 , and the design plate  20  cut along the line C-C shown in  FIG.  4 D . As shown in  FIG.  5 B , the first lens part  21  and the second lens part  22  are fixed with adhering the end surface  213  that is the edge of the opening surface of the frame part  212  and the end surface  223  that is the edge of the opening surface of the frame part  222 . And thus, the space inside the first lens part  21  and the second lens part  22  is sealed. In addition, the design plate  20  is fixed by sandwiched with the portion  214  extended inside from the four corners of interior of the frame part  212  and the portion  224  extended inside from the four corners of interior of the frame part  222 . 
     In the projector  1 , since the first lens part  21 , the second lens part  22 , and the design plate  20  are fixed with adhering each other, relative positioning accuracy of the condenser lens  211  included in the first lens part  21 , the projection lens  221  included in the second lens part  22 , and the design plate  20  becomes high. Thus, it is possible to control blurring projection image caused by relational shift of the condenser lens  211 , the projection lens  221 , and the design plate  20 . 
     In addition, since the space inside the first lens part  21  and the second lens part  22  is sealed, it is possible to control entering foreign bodies such as dust around the design plate  20 . Thus, it is possible to control reflecting the foreign body to the projection image. 
     In the meantime, a method to fix the first lens part  21 , the second lens part  22 , and the design plate  20  with adhering each other is not limited to the method using snap-fitting with the part  30   b  described above. For example, the first lens part  21  and the second lens part  22  may be fixed by adhesive bond. 
       FIG.  6    is a longitudinal cross-sectional view showing a design plate  20   a  that is an embodiment of the design plate  20 . The design plate  20   a  includes a transparent substrate  201  transmitting light from the light source  11  and an opacifying film  202  that does not transmit the light from the light source  11 . The opacifying film  202  has a predetermined opening pattern constituting a design of the design plate  20   a , and includes a light transmitting part  203  that is an opening and a light blocking part  204  that is not an opening part. 
     A projection image by the projector  1  includes a high brightness region having a pattern corresponding to the pattern of the light transmitting part  203  and a low brightness region having a pattern corresponding to the pattern of the light blocking part  204 . 
     To forming a fine opening pattern on the opacifying film  202  and making the design in the design plate  20   a  fine, it is preferable to form a pattern on the opacifying film  202  formed of metal filmed on the transparent substrate  201  formed of glass by metal etching. By filming metal film using deposit, it is possible to obtain the opacifying film  202  having very thin (approximately 100 nm) film and forming pattern by etching. 
     In this case, the opacifying film  202  consists of laminated film, e.g., comprising an opacifying film  202   a  formed of CrO and an opacifying film  202   b  formed of Cr. In addition, for example, thickness of the opacifying film  202 , the opacifying film  202   a , and the opacifying film  202   b  are respectively 1.1 mm, 8 nm, and 62 nm. A plane size of the design plate  20  is 8 mm×8 mm. 
     When forming a pattern on the opacifying film  202  formed of metal filmed on the transparent substrate  201  formed of glass, it is possible to set a minimum width of the opacifying film  202  forming the pattern (a minimum width of the light blocking part  204  forming the light transmitting parts  203  at both sides of the light blocking part  204 ) at not less than 1 μm, less than 10 μm, in more detail, not less than 1 μm and not more than 5 μm. 
     In addition, when the design of the design plate  20   a  includes a fine part that exceeds resolution of the projection lens  221 , the fine part is not projected in a focused projection image. Specifically, it is impossible to visualize a border between a high brightness region formed by the light transmitting part  203  and a low brightness region formed by the light blocking part  203  in the projection image. The high brightness region and the low brightness region are mixed. And thus, a region having a brightness between these brightness (lower than the high brightness imaged region and higher than the low brightness imaged region) is visualized. 
     That is, it is possible to describe a brightness between the brightness at a part formed by the light transmitting part  203  and the brightness at a part formed by the light blocking part  204  in the projection image by using a fine part that does not imaged by the focused projection image included in the design of the design plate  20   a . 
       FIG.  7 A  is a schematic view showing an example of design on the design plate  20   a .  FIG.  7 B  is a schematic view showing a projection image projecting the design of  FIG.  7 A . A line-and-space pattern (second triangle from left and upper surface of cube) included in the design of  FIG.  7 A  and a dot pattern (third triangle from left and side surface of the cube) are fine patterns that exceed resolution of the projection lens  221 . In the projection image shown in  FIG.  7 B , the region formed by these fine patterns is visualized as a gray region having a brightness between white of the region formed by the light transmitting part  203  (first triangle from left and front surface of the cube) and black of the region formed by the light blocking part  204  (base part). Thus, it is possible to present gradation shown by difference between brightness of three triangles in  FIG.  7 B  or three-dimensional shape expressed by the cube of  FIG.  7 B . 
     In addition, it is possible to minimize the design plate  20  if forming fine pattern on the opacifying film  202 . Since size of the projection image multiplies design size of the design plate  20  by magnification of optical system, it is possible to increase magnification with maintaining size of the projection image if the design plate  20  can be minimized. Hereby, it is possible to minimize the projector  1  by shortening distance between the design plate  20  and the projection lens  221  (increasing magnification). That is, it is possible to minimize the projection  1  with maintaining size of the projection image by minimizing the design plate  20 . For example, width W 1  in an optic axis direction of the projector  1  can be set at not more than 35 mm, and width W 2  in a direction perpendicular to the optic axis direction can be set at not more than 13 mm, and angle of view can be set at not less than 20°. 
       FIG.  8    is a longitudinal cross-sectional view showing a design plate  20   b  that is another embodiment of the design plate  20 . The design plate  20   b  is formed of a transparent resin transmitting light from the light source  11 . The design plate  20   b  includes a light transmitting part  207  constituting a plane  205  and a light blocking part  208  constituting an inclined surface  206  inclined to a plane on the plane. 
     The light blocking part  208  blocks light from the light source  11  by using total reflection at the inclined surface  206 . Thus, an inclination angle of the inclined surface  206  is set at an angle such that light entering perpendicular to the design plate  20   b  totally reflects. Therefore, the light blocking part  208  comprising the inclined surface  206  does not transmit light. For example, when the design plate  20   b  is formed of polycarbonate (reflective index is 1.6), light totally reflects as the incident angle is not less than 38.7°, and when the design plate  20   b  is formed of Polymethyl methacrylate (reflective index is 1.5), light totally reflects as the incident angle is not less than 41.8°. 
     The projection image by the projector  1  includes a high brightness region having a pattern corresponding to the pattern of the light transmitting part  207  and a low brightness region having a pattern corresponding to the pattern of the light transmitting part  208 . 
     The design plate  20   b  is formed by microfabricating to a plate molded article and so on. Thus, it is possible to form the design plate  20   b  cheaply compared with design plates such as the design plate  20   a  that is necessary to perform complex processes such as metal film deposition, forming resist pattern by photolithography, and etching. 
     Protrusion formed from the inclined surfaces  206  is provided at the light blocking part  208 . For example, the protrusion formed from the inclined surfaces  206  is a linear protrusion that has a triangle-shaped cross-section formed by two inclined surfaces  206  opposed to each other, or a pyramid protrusion formed from not less than three inclined surfaces  206 . In the meantime, when height of protrusion is limited (e.g., not more than 30 μm) caused by transcription in molding the design plate  20   b  etc., multiple protrusions having low height may be continuously aligned to ensure an area of the light blocking part  208 . 
       FIG.  9    is a schematic view explaining a condition causing total reflection when the light blocking part  208  of the design plate  20   b  includes a protrusion including two inclined surfaces  206  opposed to each other (e.g., the linear protrusion that has a triangle-shaped cross-section formed by the two inclined surfaces  206  opposed to each other, or a quadrangular pyramid protrusion). Herein, an incident angle to the inclined surface  206  (hereinafter it is referred to as the inclined surface  206   a ) where light firstly entering perpendicular to the design plate  20   b  is defined as θ 1 , and an incident angle to the inclined surface  206  (hereinafter it is referred to as the inclined surface  206   b ) where light reflected at the inclined surface  206   a  entering next is defined as θ t . 
     To totally reflect light entering perpendicular to the design plate  20   b  at the inclined surface  206   a , θ 1  is necessary to be set at not less than 38.7° when the design plate  20   b  is formed of polycarbonate. In such case, θ t  is set at not more than 102.6°. θ 1  is necessary to be set at not less than 41.8° when the design plate  20   b  is formed of Polymethyl methacrylate. In such case, θ t  is set at not more than 96.4°. In addition, to totally reflect the totally reflected light at the inclined surface  206   a  at the inclined surface  206   b , θ 2  is necessary to be set at not less than 38.7° when the design plate  20   b  is formed of polycarbonate. In such case, θ t  is set at not less than 85.8°. θ 2  is necessary to be set at not less than 41.8° when the design plate  20   b  is formed of Polymethyl methacrylate. In such case, θ t  is set at not less than 87.9°. 
     Thus, when the design plate  20   b  is formed of polycarbonate, to block light at the light blocking part  208  effectively, it is preferable to set cross-sectional angle θ t  of apex of the protrusion at not less than 85.5° and not more than 102.6°. In addition, when the design plate  20   b  is formed of Polymethyl methacrylate, to block light at the light blocking part  208  effectively, it is preferable to set cross-sectional angle θ t  of apex of the protrusion at not less than 87.9° and not more than 96.4°. 
       FIG.  10 A  is a schematic view showing an optical path of light entering into the design plate  20   b  of which angle θ t  is 90°. In this case, light entering perpendicular to the design plate  20   b  enters into the inclined surface  206   a  at the incident angle of 45° and is totally reflected. And then, the light enters into the inclined surface  206   b  at the incident angle of 45° and is totally reflected, and returns to a light source  11  side. Since the protrusion having the angle θ t  of 90° can be defined by general tool, the special preferable value of the angle θ t  is 90°. 
       FIG.  10 B  is a schematic view showing an optical path of light entering into the design plate  20   b  of which angle θ t  is 140°. In this case, light entering perpendicular to the design plate  20   b  enters into the inclined surface  206   a  at the incident angle of 20°. And then, the light reflects at the inclined surface  206   b  partially transmits the design plate  20   b . 
       FIG.  10 C  is a schematic view showing an optical path of light entering into the design plate  20   b  of which angle θ t  is 40°. In this case, light entering perpendicular to the design plate  20   b  enters into the inclined surface  206   a  at the incident angle of 70° and is totally reflected. However, the light reflects then enters into the inclined surface  206   b  at the incident angle of 30° and partially reflects at the inclined surface  206   b  and transmits the design plate  20   b . 
       FIGS.  11 A to  11 E  are cross-sectional views respectively showing the design plate  20   b  showing an arrangement examples of the inclined surface  206 . 
     The design plate  20   b  shown in  FIG.  11 A  includes a protrusion including the inclined surfaces  206  at one side surface. As described above, the protrusion is preferable to be a protrusion including two inclined surfaces  206  opposed to each other (e.g., the linear projection having a triangle-shaped cross-section formed by the two inclined surfaces  206  opposed to each other, or a quadrangular pyramid protrusion formed by four inclined surfaces  206 ). 
     The design plate  20   b  shown in  FIG.  11 B  includes a cavity including the inclined surfaces  206  at one side surface. As with the protrusion, the cavity is preferable to be a cavity including two inclined surfaces  206  opposed to each other (e.g., the linear cavity having a triangle-shaped cross-section formed by the two inclined surfaces  206  opposed to each other, or a quadrangular pyramid cavity formed by four inclined surfaces  206 ). 
     The design plate  20   b  shown in  FIG.  11 C  includes a protrusion and a cavity including the inclined surface  206  at one side surface. Since transcription of the protrusion in molding is worse than that of the cavity, a curvature R is easily formed at a tip end of the protrusion. Since light is hard to reflect at the R part, the design plate  20   b  is preferable to have only the cavity as shown in  FIG.  11 B  to reduce forming the R as possible. 
     One side surface of the design plate  20   b  shown in  FIGS.  11 A to  11 C  is a surface for forming the design comprising the plane  205  and the inclined surface  206  (hereinafter, it is referred to as a design formed surface). The design plate  20   b  may be attached to the projector  1  with facing the design formed surface to a condenser lens  211  side or a projection lens  221  side. 
     The design plate  20   b  shown in  FIG.  11 D  includes protrusions including the inclined surface  206  at both surfaces. In addition, the design plate  20   b  may include cavities at both surfaces instead of the protrusions. 
     The design plate  20   b  shown in  FIG.  11 E  includes a protrusion or a cavity at both surfaces and includes both the protrusion and the cavity at least one of the surfaces. 
     Both surfaces of the design plate  20   b  shown in  FIGS.  11 D,  11 E  are the design formed surface. In this case, a region where the inclined surface  206  at least one side surface from a region of the design plate  20   b  in a plane direction exists is the light blocking part  208  and a region where the plane  205  exists at both surfaces is the light transmitting part  207 . 
     As shown in  FIGS.  11 D,  11 E , when both surfaces of the design plate  20   b  are defined as the design formed surface, since image formation position by design imaged by one side surface is different from that by design imaged by another side surface, it is possible to broaden description by using the difference of image formation positions. For example, one side surface design can be clearly imaged to a projection surface and another side surface design can be blurry imaged. In the meantime, as shown in  FIGS.  11 A to  11 C , it is preferable to set one side surface as the design formed surface to project whole of design clearly. 
     In the meantime, in the plane  205  constituting the light transmitting part  207 , although an angle to the optic axis is preferable to be set at 90° to further transmit light, it is not limited thereto. The plane  205  may be formed to set the angle that can prevent reflecting light entering perpendicular to the design plate  20   b  and effectively transmit the light. For example, the angle to the optic axis may be set at not less than 75° and not more than 105°. In addition, as described above, the inclined surface  206  is preferable to be formed to prevent transmitting the light entering perpendicular to the design plate  20   b  by total reflection at the inclined surface  206  defining protrusion or cavity. However, it is not limited thereto. The inclined surface  206  may be formed to set the angle that effectively reflects light entering perpendicular to the design plate  20   b  at the inclined surface  206  defining the protrusion or cavity and thus can prevent transmitting effectively. For example, the inclined surface  206  is formed to set the angle to the optic axis at not less than 30° and not more than 60°. Further, it is not necessary to set the plane  205  and the inclined surface  206  to have constant angles. The angles may be different depending on the positions on the design formed surface. Since the design plate  20   b  is normally arranged such that a thickness direction thereof is parallel to the optic axis, the above angles to the optic axis can be translated into angles to the thickness direction of the design plate  20   b . 
       FIGS.  12 A to  12 C  are cross-sectional views showing variations of the design plate  20   b . As shown in  FIGS.  12 A to  12 C , the design plate  20  may include an inclined surface including a curved surface instead of the inclined surface  206  formed of the flat planes. The inclined surface  209   a  shown in  FIGS.  12 A,  12 B  is an inclined surface formed of a curved surface curved outside of the design plate  20   b . The inclined surface  209   b  is an inclined surface formed of a curved surface curved inside of the design plate  20   b . In addition, the embodiment of the curved surface as the inclined surface is not limited thereto. For example, as with the curved surface included in the inclined surface  209   c  shown in  FIG.  12 C , the cross-section may be a wavy curved surface. In the inclined surface including the curved surfaces such as the inclined surfaces  209   a ,  209   b ,  209   c , a region where an angle of the curved surface to the optic axis (the thickness direction of the design plate  20   b ) is not less than 75° and not more than 105° can be used as the light transmitting part  207  and a region where an angle of the curved surface to the optic axis is not less than 30° and not more than 60° can be used as the light blocking part  208 . In addition, a region where an angle of the curved surface to the optic axis is between 60° and 75° can be used as a region for expressing an intermediate brightness between brightness caused by the light transmitting part  207  and brightness caused by the light blocking part  208  in the projection image by the projector  1 . In addition, since the angle to the optic angle changes continuously in the curved surface, it is possible to express the gradation that the brightness in the projection image continuously changes. In addition, as with the inclined surface  206 , a surface formed of a curved surface may be used in place of the plane  205 . In this case, the embodiment of the curved surface is also not particularly limited. A region where an angle of the curved surface to the optic axis (the thickness direction of the design plate  20   b ) is not less than 75° and not more than 105° can be used as the light transmitting part  207 , and a region where an angle of the curved surface to the optic axis is not less than 30° and not more than 60° can be used as the light blocking part  208 . Obviously, the curved surface in place of the plane  205  has a higher rate of region served as the light transmitting part  207  than the curved surface in place of the inclined surface  206 . 
     The design plate  20   b  includes plural embodiments as described above. For example, the design plate  20   b  can be defined as follows. 
     (1) A design filter, comprising:
         a plate-shaped transparent material;   a design for projector projection; and   a design formed surface on at least one surface of the design filer,   wherein the design formed surface comprises a first surface having an angle of not less than 75° and not more than 105° to a thickness direction of the design filter to transmit light, and a second surface having an angle of not less than 30° and not more than 60° to the thickness direction of the design filter to block light, the first and second surfaces being arranged corresponding to the design.       

     (2) The design according to (1), wherein the design formed surface of the design filter comprises a base plane comprising the first surface and at least one of a protrusion comprising the two second surfaces opposed to each other and a cavity comprising the two second surfaces opposed to each other. 
     In examples of the design plate  20   b  shown in  FIGS.  11 A to  11 E , the plane  205  and the inclined surface  206  correspond to the first surface and the second surface, respectively, mentioned in (1) and (2) above. Also, the inclined surface comprising curved surfaces such as the inclined surfaces  209   a  to  209   c  shown in  FIGS.  12 A to  12 C  may include the first surface and the second surface mentioned in (1), (2) above depending on the shape of the curved surface. 
     The design plate  20   b  is a kind of design filter having a design for projecting, and is plate-shaped. However, it is possible to use a design filter having a different shape than the plate-shaped design plate  20   b  for the projection  1 . 
       FIG.  13    is a cross-sectional view showing the projector  1  comprising a design filter  50  that is a design filter according to the other embodiment. The cross-sectional position in  FIG.  13    corresponds to the cross-sectional position in  FIG.  2 B . 
     As with the design plate  20   b , the design filter  50  is formed of transparent material having design for projector projection. The design filter  50  includes a condenser lens. 
     The design filter  50  includes a structure that integrates a design plate comprising a design formed surface at one side surface as with the design plate  20   b  shown in  FIGS.  11 A to  11 C  and the condenser lens. The design filter  50  includes a design formed surface  500  and a condenser lens part  501  serving as a condenser lens arranged at an opposite side of the design formed surface  500  to condense light emitted from the light source  11 . 
     The design formed surface  500  is similar to the design formed surface of the design plate  20   b . For example, the design formed surface  500  is a surface that a first surface such as the plane  205  having an angle of not less than 75° and not more than 105° to the thickness direction (i.e., a direction perpendicular to the flat surface of the design formed surface  500 ) of the design filter  50  to transmit light, and a second surface such as the inclined plane  206  having an angle of not less than 30° and not more than 60° to the thickness direction to block light are arranged corresponding to the design. 
     For the design filter  50 , since the design formed surface  500  and the condenser lens part  501  are included in one part, the projection image does not blur caused by relative shift between the design formed surface  500  and the condenser lens part  501 . 
     The design filter  50  is attached to the projector  1  to face the design formed surface  500  to a projection lens  221  side and face the condenser lens part  501  to a light source  11  side. The condenser lens part  501  is curved to protrude toward the light source  11 . 
     The design filter  50  is used instead of the design plate  20  and the first lens part  21  of the structure including the design plate  20  shown in  FIG.  1 B  and so on. As shown in  FIG.  13   , the design filter  50  includes a frame part  502 , a fixing portion  505 , a hole  506  that have similar function with the frame part  212 , the fixing part  215 , and the hole  216  of the first lens part  21 . 
     In addition, the design filter  50  and the second lens part  22  are fixed with sealing a tip end surface that is an edge around the design formed surface  500  of the design filter  50  and an end surface  223  that is an edge of opening surface of the frame part  222 , and thus a space including the design formed surface  500  inside the design filter  50  and the second lens part  22  is sealed. Thus, it is possible to control entering foreign objects such as dust around the design formed surface  500 . Therefore, it is possible to control reflecting foreign objects to projection image. 
     The design filter  50  is also formed by microfabricating to transparent materials such as resin mold as with the design plate  20   b . Thus, it is possible to form the design filter cheaply compared with a design plate that is necessary to perform complex processes such as metal film deposition, forming resist pattern by photolithography, and etching. 
     Material of the design filter formed by microfabricating transparent materials such as the design plate  20   b  and the design filter  50  may be a material having a character transmitting light emitted from the light source  11 . Especially, it is preferable to be transparent resins that can injection mold such as polycarbonate and acryl. It is possible to further decrease manufacturing cost of the design filter if the material can be formed by injection molding. 
     In addition, the condenser lens  211  is used in examples shown in  FIGS.  2 B  etc., to increase efficiency of utilization of light emitted from the light source  11  in the projector  1 . However, the light emitted from the light source  11  may be entered directly into the design plate  20  or the design filter  50  etc., without using the condenser lens  211 . In addition, the light emitted from the light source  11  may be entered into the design plate  20  or the design filter  50  etc., after reflecting at a mirror. 
     (Effects of embodiments) 
     In the projector  1  according to the above embodiment of the present invention, since the first lens part  21 , the second lens part  22 , and the design plate  20  are fixed with contacting each other, relative positioning accuracy of the condenser lens  211  included in the first lens part  21 , the projection lens  221  included in the second lens part  22 , and the design plate  20  is high. Thus, it is possible to control blurring the projection image caused by the relative position shift of the condenser lens  211 , the projection lens  221 , and the design plate  20 . In addition, since the inside space between the first lens part  21  and the second lens part  22  is sealed, it is possible to control entering foreign objects such as dust around the design plate  20 . Therefore, it is possible to control reflecting foreign object to the projection image. 
     In addition, according to the above embodiment of the present invention, it is possible to provide the projector projection design in the vehicle interior at low cost by using the design filters such as the design plate  20   b  and the design filter  50 , which can be manufactured at lower cost than conventional products. 
     Although the embodiments of the invention have been described, the invention is not to be limited to the embodiments. The various kinds of modifications can be implemented without departing from the gist of the invention. In addition, the constituent elements in the embodiments and examples can be arbitrarily combined without departing from the gist of the invention. 
     In addition, the invention according to claims is not to be limited to the above embodiments and examples. Please note that all combinations of the features described in the embodiments are not necessary to solve the problem of the invention. 
     Reference Signs List
           1  PROJECTOR     2  LIGHT SOURCE     20  DESIGN PLATE     21  FIRST LENS PART     211  CONDENSER LENS     212  FRAME PART     22  SECOND LENS PART     221  PROJECTION LENS     222  FRAME PART     30  BODY     50  DESIGN FILTER     500  DESIGN FORMED SURFACE     501  CONDENSER LENS PART