Abstract:
A head-up display device includes: a cover having a light-transmissive light exit part; a first case mating with the cover and having a light entry part for entry of display light and a housing part housing a reflecting member; a light source unit outside the housing part; and a second case covering the light source unit and fastened to the first case. The device has a heat radiator of higher rigidity than the second case, having a wall part that externally projects from the housing part through the intervening light entry part, the light source unit affixed to the wall part to diffuse the heat from the light source unit; and includes a mating part in which the second case and the wall part mate together, the second case fastened to the heat radiator at locations to either side of the mating part.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a head-up display device having a favorable assembling property. 
       BACKGROUND ART 
       [0002]    Conventionally, PTL 1 discloses a configuration in which, in a head-up display device for displaying a virtual image in front of a windshield of a vehicle, a light source unit having a back surface to which a heat radiator is attached is provided on the outside of a case that houses a reflecting member for reflecting display light from the light source unit toward the windshield in order to efficiently radiate heat emitted by the light source unit. 
       CITATION LIST 
     Patent Literature(s) 
       [0003]    PTL 1: JP-UM-A-5-23404 
       SUMMARY OF INVENTION 
     Technical Problem(s) 
       [0004]    In the head-up display device disclosed in PTL 1, there is a possibility that an assembling property is further improved in fixing a second case that covers the light source unit fixed to the outside of a first case that houses the reflecting member. 
         [0005]    The invention has been made in view of the above problem, and an object thereof is to provide a head-up display device having a favorable assembling property. 
       Solution to Problem(s) 
       [0006]    A head-up display device according to the invention including 
         [0007]    a cover having a light-transmissive light exit part, 
         [0008]    a first case having a light entry part on which light is incident and a housing part housing a reflecting member for reflecting light incident through the light entry part toward the light exit part, the first case being mated to the cover, 
         [0009]    a light source unit fixed to the outside of the housing part of the first case so that light is incident on the light entry part, and 
         [0010]    a second case covering the light source unit and fixed to the first case with screws, 
         [0011]    the head-up display device being for performing display on the outside by causing the reflecting member to reflect light emitted by the light source unit and transmitting the light through the light exit part of the cover, 
         [0012]    the head-up display device includes: 
         [0013]    a heat radiator having a higher rigidity than a rigidity of the second case and having a wall part protruded in a direction from the inside of the housing part to the outside of the housing part via the light entry part, the wall part being a part to which the light source unit is fixed with screws so that the heat radiator radiates heat of the light source unit, wherein: 
         [0014]    the second case and the wall part have mating parts with which the second case and the wall part are mated to each other; and 
         [0015]    the second case is fixed to the heat radiator or the first case with screws at positions between which the mating parts are interposed. 
       Advantageous Effects of Invention 
       [0016]    According to the invention, it is possible to provide a head-up display device having a favorable assembling property. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0017]      FIG. 1  is a schematic configuration diagram of a head-up display device according to an embodiment of the invention. 
           [0018]      FIG. 2  is a perspective view of a surface of the head-up display device according to the same embodiment. 
           [0019]      FIG. 3  is a perspective view of the surface in a state in which a cover of the head-up display device according to the same embodiment is removed. 
           [0020]      FIG. 4  is a perspective view of a back surface of the head-up display device according to the same embodiment. 
           [0021]      FIG. 5  shows an assembling relationship between a first case and a second case of the head-up display device according to the same embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0022]    Hereinafter, an embodiment of the invention will be described with reference to the attached drawings. 
         [0023]    A head-up display device A according to the invention includes a cover  1 , a first case  2 , a reflecting member  3 , a light source unit  4 , a second case  5 , a control board  6 , and a third case  7  and causes the reflecting member  3  to reflect display light L projected by the light source unit  4  to project and display the display light L on the outside of the cover  1 . 
         [0024]    This head-up display device A is mounted on a vehicle and projects display light L onto a windshield on a driver&#39;s seat side of the vehicle to form a virtual image in front of the windshield. For example, by projecting an instrument image including a driving speed and the like of the vehicle as display light L onto the windshield, a driver can check vehicle information superimposed on a scenery outside the vehicle through the windshield at the time of driving while keeping his/her eyes forward. 
         [0025]    The cover  1  is a cover made of, for example, resin such as polyethylene terephthalate (PET) or polycarbonate (PC). The cover  1  has, for example, a light exit part  10  made of light-transmissive resin such as acrylic resin and transmits display light L reflected by the reflecting member  3 , thereby projecting the display light L onto the windshield. 
         [0026]    The first case  2  is made up of, for example, a case member obtained by performing metal mold casting on aluminum. In the first case  2 , a light entry part  20  for introducing display light L projected by the light source unit  4  is provided in a housing part  21  housing the reflecting member  3 , and the first case  2  is mated to the cover  1 . The light introduced through the light entry part  20  is reflected by the reflecting member  3  housed in the housing part  21 , is transmitted through the light exit part  10  of the cover  1 , and is projected onto the windshield. 
         [0027]    A wall part  22  protruded in a direction from the inside of the housing part  21  to the outside of the housing part  21  via the light entry part  20  is provided on the outside of the housing part  21  of the first case  2 . 
         [0028]    A backlight board  40  (described below) of the light source unit  4  is fixed to the wall part  22  with screws. Heat emitted by the backlight board  40  is transmitted to the whole first case  2  via the wall part  22  and the heat is radiated to an external environment via the first case  2 , and thus the whole first case  2  functions as a heat radiator of the light source unit  4 . 
         [0029]    Note that a heat conductive sheet for bringing the wall part  22  and the light source unit  4  into close contact with each other to reduce a contact thermal resistance may be provided between the wall part  22  and the light source unit  4 . 
         [0030]    The reflecting member  3  is made up of a first reflecting member  30  and a second reflecting member  31 . The first reflecting member is made up of a plane mirror, and the second reflecting member  31  is made up of a concave mirror unit that is rotatable around a rotating shaft  31   a  by power of a drive unit  310 . 
         [0031]    The light source unit  4  includes the backlight board  40 , a reflecting member  41 , and a liquid crystal substrate  42 . 
         [0032]    The backlight board  40  is made up of a circuit board on which an LED (Light Emitting Diode) serving as a light source is mounted and projects display light L at a brightness based on control by the control board  6 . Further, the backlight board  40  is fixed to the wall part  22  with screws so that a surface on which the LED is mounted faces the reflecting member  41  and a surface (back surface) on which the LED is not mounted faces the wall part  22 . 
         [0033]    The reflecting member  41  is made up of a plane mirror and reflects the display light L emitted by the backlight board  40  toward a back surface of the liquid crystal substrate  42 . 
         [0034]    The liquid crystal substrate  42  is made up of, for example, a TFT (Thin Film Transistor) type liquid crystal panel and is placed so that a surface thereof faces the light entry part  20  of the first case  2 . Further, the liquid crystal substrate switches a plurality of pixels to a transmissive/non-transmissive state in accordance with control by the control board  6  and causes the pixels in the transmissive state to transmit the light from the backlight board  40 , thereby projecting a predetermined image as the display light L onto the light entry part  20  of the first case  2 . 
         [0035]    The second case  5  is made of, for example, opaque resin that can be easily molded, such as polypropylene (PP) that is comparatively inexpensive and has light weight, and covers the light source unit  4  and is fixed to the first case  2  with screws. 
         [0036]    The control board  6  is a circuit board on which various electronic elements and wiring for controlling drive of the drive unit  310  of the second reflecting member  31 , the backlight board  40  of the light source unit  4 , and the liquid crystal substrate  42  are mounted. 
         [0037]    The control board  6  is connected to a CAN (Controller Area Network) and forms vehicle information such as a driving speed of the vehicle acquired via the CAN as an instrument image to thereby project the instrument image as display light L onto the light source unit  4 . Further, the control board  6  can adjust a position of a virtual image to a height of an eyepoint of a driver by driving the drive unit  310  and rotating the second reflecting member  31  around the rotating shaft  31   a  to adjust an imaging position of the virtual image in a vertical direction of the windshield. 
         [0038]    The third case  7  is made up of, for example, a flat box-shaped case member made of aluminum and is fixed to the first case  2  with screws to cover the control board  6  so as to prevent the control board  6  from being influenced by an electromagnetic wave from the outside or prevent an electromagnetic wave emitted by the control board  6  from influencing the outside, thereby blocking an influence of an electromagnetic wave between the control board and the external environment. 
         [0039]    (Assembling Relationship Between First Case  2  and Second Case  5 ) 
         [0040]    Screwing of the first case  2  and the second case  5  will be described with reference to  FIG. 5 .  FIG. 5( a )  is a perspective view obliquely seen from a back surface of the head-up display device A and shows screwing of the first case  2  and the second case  5  in a state in which the light source unit  4  is removed from the first case  2 .  FIG. 5( b )  shows a relationship between the wall part  22  of the first case  2  and screw holes  23   a ,  23   b ,  23   c , and  23   d  described below. 
         [0041]    Screw holes  51   a ,  51   b ,  51   c , and  51   d  are provided at four corners of the second case  5 , and the screw holes  23   a ,  23   b ,  23   c , and  23   d  are provided in the first case  2  corresponding to the screw holes  51   a ,  51   b ,  51   c , and  51   d . The second case  5  is fixed to the first case  2  with screws through the corresponding screw holes. 
         [0042]    The screw hole  23   c  and the screw hole  23   d  of the first case  2  are positioned so that the wall part  22  is interposed therebetween, and a grooved mating part  220  is provided in a portion interposed between the screw holes  23   c  and the screw hole  23   d  of the wall part  22 . Meanwhile, a protruded part to be mated to the grooved mating part  220  is provided in the second case  5 . With this, when the second case  5  is fixed to the first case  2  with screws, a side between the screw hole  51   c  and the screw hole  51   d  of the second case  5  is mated to the mating part  220  of the wall part  22 . 
         [0043]    The wall part  22  is protruded from a line segment between the screw hole  23   c  and the screw hole  23   d  in a height direction in order to increase a mating area of the mating part  220  to be mated to the second case  5 . 
         [0044]    The screw hole  23   c  and the screw hole  23   d  of the first case  2  are provided at low positions in the height direction of the wall part  22 , as compared with the screw hole  23   a  and the screw hole  23   b . 
         [0045]    With this configuration, an assembling property of the second case  5  and the first case  2  is improved. 
         [0046]    Specifically, the side of the second case  5  made of resin to be mated to the wall part  22  is not deformed in a thickness direction of the wall part  22  because rigidity thereof is secured by the wall part  22  made of aluminum. This reduces the risk that positions of the screw hole  51   c  and the screw hole  51   d  are shifted from positions corresponding to the screw holes of the first case  2  even in the case where the second case  5  is deformed by a screw fastening torque. Therefore, when assembling is performed by first screwing the screw hole  51   a  and the screw hole  51   b  that are not positioned, the risk of failure of assembly is reduced. 
         [0047]    Further, because the wall part  22  is protruded from the line segment between the screw hole  23   c  and the screw hole  23   d  in the height direction, the fitting area of the mating part  220  to be mated to the second case  5  is increased, and therefore the side between the screw hole  51   c  and the screw hole  51   d  of the second case  5  is provided along the wall part  22  more firmly and is prevented from being deformed in the thickness direction of the wall part  22 . 
         [0048]    The screw hole  23   c  and the screw hole  23   d  of the first case  2  are provided at high positions in the height direction of the wall part  22 , as compared with the screw hole  23   a  and the screw hole  23   b . Therefore, when the screw hole  51   a  and the screw hole  51   b  that are not positioned are screwed first, a deforming direction caused by a screw fastening torque is matched with the thickness direction of the wall part  22 , which reduces the risk that the positions of the screw hole  51   c  and the screw hole  51   d  are shifted from the positions corresponding to the screw holes of the first case  2  due to deformation caused by the screw fastening torque. 
         [0049]    With those effects, it is possible to position the second case  5  while the rigidity in the side between the screw hole  51   c  and the screw hole  51   d  of the second case  5  mated to the wall part  22  is being secured by the wall part  22 , and therefore the assembling property is not lost even in the case where the second case is made of a resin material having a comparatively low rigidity or molding precision thereof is comparatively low. Therefore, it is possible to produce the second case inexpensively while securing the assembling property. 
         [0050]    Note that, in this embodiment, the first case  2  and the wall part  22  are integrally formed by metal mold casting with aluminum so that the first case  2  has both a function of housing the reflecting member  3  and a function as a heat radiator in order to improve a heat radiation property. However, the first case  2  is not limited thereto, and the first case  2  may be made of resin and a metallic heat radiator having the wall part  22  may be separately formed, and the first case  2  and the metallic heat radiator may be combined with each other. 
         [0051]    In the above description, in order to easily understand the invention, description of publicly-known unimportant technical matters has been omitted as appropriate. 
       INDUSTRIAL APPLICABILITY 
       [0052]    The invention is suitable as a head-up display device mounted on a vehicle, a motorcycle, or a move provided with an agricultural machine or a construction machine. 
       REFERENCE SIGNS LIST 
       [0053]    A: head-up display device
 
 1 : cover
 
 10 : light exit part
 
 2 : first case
 
 20 : light entry part
 
 21 : housing part
 
 22 : wall part
 
 220 : mating part
 
 3 : reflecting member
 
 30 : first reflecting member
 
 31 : second reflecting member
 
 31   a : rotating shaft
 
 310 : drive unit
 
 4 : light source unit
 
 40 : backlight board
 
 41 : reflecting member
 
 42 : liquid crystal substrate
 
 5 : second case
 
 6 : control board
 
 7 : third case
 
L: display light